Actions to improve margins by flooding in Potxos ravine and its tributary Valley Park 110 kV in the NPP ASCO; Actuaciones de mejora de margenes de seguridad por inundabilidad en barranco de Potxos y su afluente Vaguada Parque 110 kV en la CN Asco

Energy Technology Data Exchange (ETDEWEB)

Costa, A.; Sabater, J.

2013-07-01

Among the studies aimed at strengthening the security of ANAV (Stress Tests) and has been evaluated the capacity of channels and pipes of the Potxos ravine and its tributary Valley of the 110 kV Park. Considering that these channels are operated and channeled, to carry out the assessment of their capabilities, is evidence that it is feasible to improve the margin of safety against floods, reason by which the actions described later arise.

The glacially overdeepened trough of the Salzach Valley, Austria: Bedrock geometry and sedimentary fill of a major Alpine subglacial basin

Science.gov (United States)

Pomper, Johannes; Salcher, Bernhard C.; Eichkitz, Christoph; Prasicek, Günther; Lang, Andreas; Lindner, Martin; Götz, Joachim

2017-10-01

Overdeepened valleys are unambiguous features of glacially sculpted landscapes. They result from erosion at the bed of the glacier and their size and shape is determined by ice dynamics and the characteristics of the underlying bedrock. Major overdeepened valleys representing vertical bedrock erosion of several hundreds of meters are characteristic features of many trunk valleys in the formerly glaciated parts of the Alpine mountain belt. The thick sedimentary fill usually hinders attempts to unravel bedrock geometry, formation history and fill characteristics. Based on reflection seismic data and core-logs from multiple deep drillings we construct a detailed bedrock model of the Lower Salzach Valley trough, one of the largest overdeepened valleys in the European Alps. The analysed overdeepened structure characterized by a strongly undulating topography. Two reaches of enhanced erosion can be identified and are suggested to be related to variations in bedrock erodibility and a triple glacier confluence. The sedimentary fill shows clear characteristics of rapid infilling and subaqueous fan delta deposits indicate a strong influence of tributary streams. Associated surface lowering of the valley floor had a major impact on tributary stream incision but also on the available ice accumulation area at subsequent glaciations. The extent to which fills of earlier glaciations have been preserved from erosion during the last glacial maximum remains ambiguous and demands further exploration. To our knowledge the presented bedrock model is one of the best defined of any major overdeepened trunk valley.

Annotated checklist and key to the species of amphibians and reptiles inhabiting the northern Peruvian dry forest along the Andean valley of the Marañón River and its tributaries.

Science.gov (United States)

Koch, Claudia; Venegas, Pablo J; Cruz, Roy Santa; BÖhme, Wolfgang

2018-02-22

A checklist of the amphibians and reptiles of 35 localities situated in the northern Peruvian dry forest valley of the Marañón River and its tributaries, containing 14 species of amphibians and 54 species of reptiles, is provided from data collected between July 2005 and April 2014 during several herpetological surveys and from the literature. Detailed accounts are given for each collected species containing morphometric and scalation data, information on natural history, comments regarding their distribution, the conservation status and key literature. Eleven new species were discovered and described during the survey period. At least five additional taxa might also represent new species but more field work and data collection are necessary to determine their status. For two snake species we provide the first country record and for 23 further species new departamental records are provided.

Preliminary results of hydrogeologic investigations Humboldt River Valley, Winnemucca, Nevada

Science.gov (United States)

Cohen, Philip M.

1964-01-01

Most of the ground water of economic importance and nearly all the ground water closely associated with the flow o# the Humboldt River in the. 40-mile reach near Winnemucca, Nev., are in unconsolidated sedimentary deposits. These deposits range in age from Pliocene to Recent and range in character from coarse poorly sorted fanglomerate to lacustrine strata of clay, silt, sand, and gravel. The most permeable deposit consists of sand and gravel of Lake Lahontan age--the so-called medial gravel unit--which is underlain and overlain by fairly impermeable silt and clay also of Lake Lahontan age. The ultimate source of nearly all the water in the study area is precpitation within the drainage basin of the Humboldt River. Much of this water reaches the study, area as flow or underflow of the Humboldt River and as underflow from other valleys tributary to the study area. Little if any flow from the tributary streams in the study area usually reaches the Humboldt River. Most of the tributary streamflow within the study area evaporates or is transpired by vegetation, but a part percolates downward through unconsolidated deposits of the alluvial fans flanking the mountains and move downgradient as ground-water underflow toward the Humboldt River. Areas that contribute significant amounts of ground-water underflow to. the valley of the Humboldt River within the study area are (1) the valley of the Humboldt River upstream from the study area, (2) the Pole Creek-Rock Creek area, (3) Paradise Valley, and (4) Grass Valley and the northwestern slope of the Sonoma Range. The total average underflow from these areas in the period 1949-61 was about 14,000-19,000 acre-feet per year. Much of this underflow discharged into the Humboldt River within the study area and constituted a large part of the base flow of the river. Streamflow in the Humboldt River increases substantially in the early spring, principally because of runoff to the river in the reaches upstream from the study area

Geomorphic controls on Pleistocene knickpoint migration in Alpine valleys

Science.gov (United States)

Leith, Kerry; Fox, Matt; Moore, Jeffrey R.; Brosda, Julian; Krautblatter, Michael; Loew, Simon

2014-05-01

Recent insights into sub-glacial bedrock stress conditions suggest that the erosional efficiency of glaciers may reduce markedly following a major erosional cycle [Leith et al., 2013]. This implies that the formation of large glacial valleys within the Alps is likely to have occurred shortly after the onset of 100 ky glacial-interglacial cycles (at the mid-Pleistocene Revolution (MPR)). The majority of landscape change since this time may have therefore been driven by sub-aerial processes. This hypothesis is supported by observations of hillslope and channel morphology within Canton Valais (Switzerland), where major tributary valleys display a common morphology along their length, hinting at a shared geomorphic history. Glaciers currently occupy the headwaters of many catchments, while the upper reaches of rivers flow across extensive alluvial planes before abruptly transitioning to steep channels consisting of mixed bedrock and talus fan deposits. The rivers then converge to flow out over the alluvial plane of the Rhone Valley. Characteristically rough topographies within the region are suggested to mark the progressive transition from a glacial to fluvially-dominated landscape, and correlate well with steepened river channel sections determined from a 2.5 m resolution LiDAR DEM. We envisage a landscape in which ongoing tectonic uplift drives the emergence of Alpine bedrock through massive sedimentary valley infills (currently concentrated in the Rhone Valley), whose elevation is fixed by the consistent fluvial baselevel at Lake Geneva. As fluvial incision ceases at the onset of glaciation, continued uplift causes the formation of knickpoints at the former transition from bedrock to sedimentary infill. These knickpoints will then propagate upstream during subsequent interglacial periods. By investigating channel morphologies using an approach based on the steady-state form of the stream power equation, we can correlate steepened channel reaches (degraded

Anurans in a Subarctic Tundra Landscape Near Cape Churchill, Manitoba

Science.gov (United States)

Reiter, M.E.; Boal, C.W.; Andersen, D.E.

2008-01-01

Distribution, abundance, and habitat relationships of anurans inhabiting subarctic regions are poorly understood, and anuran monitoring protocols developed for temperate regions may not be applicable across large roadless areas of northern landscapes. In addition, arctic and subarctic regions of North America are predicted to experience changes in climate and, in some areas, are experiencing habitat alteration due to high rates of herbivory by breeding and migrating waterfowl. To better understand subarctic anuran abundance, distribution, and habitat associations, we conducted anuran calling surveys in the Cape Churchill region of Wapusk National Park, Manitoba, Canada, in 2004 and 2005. We conducted surveys along ~l-km transects distributed across three landscape types (coastal tundra, interior sedge meadow-tundra, and boreal forest-tundra interface) to estimate densities and probabilities of detection of Boreal Chorus Frogs (Pseudacris maculata) and Wood Frogs (Lithobates sylvaticus). We detected a Wood Frog or Boreal Chorus Frog on 22 (87%) of 26 transects surveyed, but probability of detection varied between years and species and among landscape types. Estimated densities of both species increased from the coastal zone inland toward the boreal forest edge. Our results suggest anurans occur across all three landscape types in our study area, but that species-specific spatial patterns exist in their abundances. Considerations for both spatial and temporal variation in abundance and detection probability need to be incorporated into surveys and monitoring programs for subarctic anurans.

Growing season boundary layer climate and surface exchanges in a subarctic lichen woodland

Science.gov (United States)

Fitzjarrald, David R.; Moore, Kathleen E.

1994-01-01

Between June and August 1990, observations were made at two surface micrometeorological towers near Schefferville Quebec (54 deg 52 min N, 66 deg 40.5 min W), one in a fen and one in the subarctic lichen woodland, and at four surface climatological stations. Data from these surface stations were supplemented by regular radiosonde launches. Supporting measurements of radiative components and soil temperatures allowed heat and moisture balances to be obtained at two sites. The overall surface meteorological experiment design and results of micrometeorological observations made on a 30-m tower in the lichen woodland are presented here. Seasonal variation in the heat and water vapor transport characteristics illustrate the marked effect of the late summer climatological shift in air mass type. During the first half of the summer, average valley sidewalls only 100 m high are sufficient to channel winds along the valley in the entire convective boundary layer. Channeling effects at the surface, known for some time at the long-term climate station in Schefferville, are observed both at ridge top and in the valley, possibly the response of the flow to the NW-SE orientation of valleys in the region. Diurnal surface temperature amplitude at ridge top (approximately equal to 10 C) was found to be half that observed in the valley. Relatively large differences in precipitation among these stations and the climatological station at Schefferville airport were observed and attributed to the local topography. Eddy correlation observations of the heat, moisture and momentum transports were obtained from a 30-m tower above a sparse (approximately equal to 616 stems/ha) black spruce lichen woodland. Properties of the turbulent surface boundary layer agree well with previous wind tunnel studies over idealized rough surfaces. Daytime Bowen ratios of 2.5-3 are larger than those reported in previous studies. Surface layer flux data quality was assessed by looking at the surface layer heat

Life-Histories of Sub-Arctic Ants

OpenAIRE

Heinze, Jürgen

1993-01-01

Ant species belonging to seven genera occur in habitats near the tree line in the Northern Hemisphere. An analysis of colony founding strategies suggests that in addition to physiological cold resistance, behavioral and sociometric adaptations might be important for survival and propagation of ants in subarctic biomes.

Macrozoobenthos in the subarctic river Tenojoki as an environmental indicator. Tenojoen pohjaelaeimistoe ympaeristoen laadun kuvaajana

Energy Technology Data Exchange (ETDEWEB)

Lax, H.G.; Koskenniemi, E.; Sevola, P.; Bagge, P.

1993-01-01

The macrozoobenthos of the subarctic river Tenojoki and some of its tributaries was studied in June and September 1989 as a part of the environmental monitoring programme. The river (F = 16 386 km[sup 2], length 300 km, L = 2.4 %, Q varies between 30-400 m[sup 3]/s) is situated on the Finnish-Norwegian border and is characterized by sand bottoms interrupted by shorter reaches of gravel and stone bottoms. The water is usually clear (colour < 40 mg Pt/l) and oligotrophic (tot-P < 10 [mu]g/l). The bottom fauna was sampled from 9 stations in the main river and from one station in each of the 5 major tributaries. The sampling methods used were: kick-sampling and imago hand netting from all stations, colonization substrates (stone baskets and bricks) at 9 stations in the main river. The tax a number of the kick-samples varied from 10-15/station in spring (totally 51 taxa) and from 15-25/station in autumn (totally 69 taxa). In spring the river margin (depth 0-25 cm) seemed to be an important habitat for many species especially in the upper parts of the river. In autumn most of the species occurred on deeper bottoms (depth 50-100 cm). The most common feeding types in spring were the collectors (Amaletus inopinatus, Chironomidae) and in autumn the scrapers (Elmidae, Baetidae, Hydroptllidae) and collectors (Chironomidae). The pollution index (LongScoreSystem) indicated that the conditions in the lower part of the main river was more stressing for the bottom fauna than in the upper part. But up to now it seems as if the organic pollution from settlements have had only positive effects on the benthic community

Energy Design Guidelines for High Performance Schools: Arctic and Subarctic Climates

Energy Technology Data Exchange (ETDEWEB)

2004-11-01

The Energy Design Guidelines for High Performance Schools--Arctic and Subarctic Climates provides school boards, administrators, and design staff with guidance to help them make informed decisions about energy and environmental issues important to school systems and communities. These design guidelines outline high performance principles for the new or retrofit design of your K-12 school in arctic and subarctic climates. By incorporating energy improvements into their construction or renovation plans, schools can significantly reduce energy consumption and costs.

A New Xeromorphic Species of Clusia em>(Clusiaceae) from Dry Valleys of Northern Peru

DEFF Research Database (Denmark)

Gustafsson, Mats

2010-01-01

Clusia magnoliiflora M. H. G. Gust. is described as new for the Clusiaceae. It grows in dry scrub in the river valleys of the Marañón and its tributaries in northern Peru, a kind of habitat that harbors very few Clusia species. The species is distinct on account of its extremely thick, obovate le...

Molecular analyses reveal high species diversity of trematodes in a sub-Arctic lake

Science.gov (United States)

Soldánová, Miroslava; Georgieva, Simona; Roháčováa, Jana; Knudsen, Rune; Kuhn, Jesper A.; Henriksen, Eirik H.; Siwertsson, Anna; Shaw, Jenny C.; Kuris, Armand M.; Amundsen, Per-Arne; Scholz, Tomáš; Lafferty, Kevin D.; Kostadinova, Aneta

2017-01-01

To identify trematode diversity and life-cycles in the sub-Arctic Lake Takvatn, Norway, we characterised 120 trematode isolates from mollusc first intermediate hosts, metacercariae from second intermediate host fishes and invertebrates, and adults from fish and invertebrate definitive hosts, using molecular techniques. Phylogenies based on nuclear and/or mtDNA revealed high species richness (24 species or species-level genetic lineages), and uncovered trematode diversity (16 putative new species) from five families typical in lake ecosystems (Allocreadiidae, Diplostomidae, Plagiorchiidae, Schistosomatidae and Strigeidae). Sampling potential invertebrate hosts allowed matching of sequence data for different stages, thus achieving molecular elucidation of trematode life-cycles and exploration of host-parasite interactions. Phylogenetic analyses also helped identify three major mollusc intermediate hosts (Radix balthica, Pisidium casertanum and Sphaerium sp.) in the lake. Our findings increase the known trematode diversity at the sub-Arctic Lake Takvatn, showing that digenean diversity is high in this otherwise depauperate sub-Arctic freshwater ecosystem, and indicating that sub-Arctic and Arctic ecosystems may be characterised by unique trematode assemblages.

Anthropogenic changes in environmental conditions of phytocoenoses of medium sized-sized Ukrainian river valleys (based on the example of the River Tyasmyn – a tributary of the Dnieper

Directory of Open Access Journals (Sweden)

V. V. Lavrov

2016-09-01

Full Text Available The problem of anthropogenic degradation of rivers is usually marked by its multi-sectoral and often international character as well by the large number of sources of environmental threat. Therefore, its solution requires a systematic approach based on transparent and coordinated interagency and international cooperation. The River Dnieper inUkrainehas undergone a remarkable transformation as a result of the construction of a cascade of reservoirs. Anthropogenic damage to the plants and soil that cover its basin have caused damage to the functioning of ecological regimes of theDnieper’s tributaries. Small and medium-sized rivers are dying. In this article, attention is paid to a typical middle-sized (164 km river of theDnieperBasin, the Tyasmyn. Its middle and lower parts are located in the overtransformed Irdyn-Tyasmyn valley. During the last glaciation it formed the central part of the right arm of the ancientDnieper. Regulation of the Tyasmyn runoff, pollution, the creation of theKremenchugreservoir on theDnieper, grazing and recreational load have led to the threat of the river degrading. Therefore, the aim of this article is to characterize the structure of the herbaceous vegetation in the central and lower parts of the Tyasmyn valley and assess the level of its dependence on anthropogenic changes in the conditions of the ecotypes. The methods used are: retrospective and system analysis, comparative ecology (ecological profile or transect, botanic methods, phytoindication, the mapping method and mathematical statistics. The features of changes in environmental conditions of ecotypes of the river valley have been shown through systematic, biomorphological, ecomorphic structure of the herbaceous cover, the ratio of ecological groups and changes in types of ecological strategy of species, phytodiversity. We found 89 species of vascular plants. The most diverse families were Asteraceae, Poaceae and Lamiaceae. The biomorphological range of

Glacial geology of the upper Wairau Valley, Marlborough, New Zealand

International Nuclear Information System (INIS)

McCalpin, J.P.

1992-01-01

Late Pleistocene glaciers in the upper Wairau Valley deposited four groups of moraines inferred to represent one Waimean ice advance, two Otiran ice advances, and an advance of early Aranuian age. The Waimean and early Otiran glaciers advanced into Tarndale Valley, deposited terminal moraines, and shed outwash down both the Alma River and Travellers Valley. The middle Otiran glacier terminated in northern Tarndale Valley and shed outwash from the southern part of its terminus down the Alma River. The north side of the terminus abutted a large ice-dammed lake in the Wairau Gorge, and fan-deltas graded to an old shore level at an elevation of 1040 m. Well-preserved moraines at the mouths of four glaciated tributaries may be middle Otiran recessional, or late Otiran terminal moraines. The latest ice advance extended 11 km down the upper Wairau Valley and deposited a subdued moraine at Island Gully. The composite chronology of the latest glacial advance based on 10 radiocarbon ages suggests it occurred between about 9.5 and 10.2 ka. This age span is similar to that of early Aranuian glacial advances dated by other workers in the Southern Alps, and may reflect Younger Dryas cooling. (author). 22 refs., 10 figs., 3 tabs

Reservoir Operation Rules for Controlling Algal Blooms in a Tributary to the Impoundment of Three Gorges Dam

Directory of Open Access Journals (Sweden)

Jijian Lian

2014-10-01

Full Text Available Since the first impoundment of Three Gorges Dam in 2003, algal blooms occur frequently in the near-dam tributaries. It is widely recognized that the impoundment-induced change in hydrodynamic condition with the lower current velocity will make the eutrophication problem even more severe when an excessive amount of nutrients is already loaded into a reservoir and/or its tributaries. Operation tests carried out by Three Gorges Corporation in 2010 point to some feasible reservoir operation schemes that may have positive impacts on reducing the algal bloom level. In our study, an attempt is made to obtain, through a numerical hydrodynamic and water quality modeling and analysis, the reservoir operation rules that would reduce the level of algal blooms in the Xiangxi River (XXR, a near-dam tributary. Water movements and algal blooms in XXR are simulated and analyzed under different scenarios of one-day water discharge fluctuation or two-week water level variation. The model results demonstrate that the reservoir operations can further increase the water exchange between the mainstream of the Three Gorges Reservoir (TGR and the XXR tributary and thus move a larger amount of algae into the deep water where it will die. Analysis of the model results indicate that the water discharge fluctuation constituted of a lower valley-load flow and a larger flow difference for the short-term operation (within a day, the rise in water level for the medium-term operation (e.g., over weeks, and the combination of the above two for the long-term operation (e.g., over months can be the feasible reservoir operation rules in the non-flood season for TGR.

Surface CO2 Exchange Dynamics across a Climatic Gradient in McKenzie Valley: Effect of Landforms, Climate and Permafrost

Directory of Open Access Journals (Sweden)

Natalia Startsev

2016-11-01

Full Text Available Northern regions are experiencing considerable climate change affecting the state of permafrost, peat accumulation rates, and the large pool of carbon (C stored in soil, thereby emphasizing the importance of monitoring surface C fluxes in different landform sites along a climate gradient. We studied surface net C exchange (NCE and ecosystem respiration (ER across different landforms (upland, peat plateau, collapse scar in mid-boreal to high subarctic ecoregions in the Mackenzie Valley of northwestern Canada for three years. NCE and ER were measured using automatic CO2 chambers (ADC, Bioscientific LTD., Herts, England, and soil respiration (SR was measured with solid state infrared CO2 sensors (Carbocaps, Vaisala, Vantaa, Finland using the concentration gradient technique. Both NCE and ER were primarily controlled by soil temperature in the upper horizons. In upland forest locations, ER varied from 583 to 214 g C·m−2·year−1 from mid-boreal to high subarctic zones, respectively. For the bog and peat plateau areas, ER was less than half that at the upland locations. Of SR, nearly 75% was generated in the upper 5 cm layer composed of live bryophytes and actively decomposing fibric material. Our results suggest that for the upland and bog locations, ER significantly exceeded NCE. Bryophyte NCE was greatest in continuously waterlogged collapsed areas and was negligible in other locations. Overall, upland forest sites were sources of CO2 (from 64 g·C·m−2·year−1 in the high subarctic to 588 g C·m−2·year−1 in mid-boreal zone; collapsed areas were sinks of C, especially in high subarctic (from 27 g·C·m−2 year−1 in mid-boreal to 86 g·C·m−2·year−1 in high subarctic and peat plateaus were minor sources (from 153 g·C·m−2·year−1 in mid-boreal to 6 g·C·m−2·year−1 in high subarctic. The results are important in understanding how different landforms are responding to climate change and would be useful in modeling the

Historical Population Structure of Central Valley Steelhead and Its Alteration by Dams

Directory of Open Access Journals (Sweden)

Steven T. Lindley

2006-02-01

Full Text Available Effective conservation and recovery planning for Central Valley steelhead requires an understanding of historical population structure. We describe the historical structure of the Central Valley steelhead evolutionarily significant unit using a multi-phase modeling approach. In the first phase, we identify stream reaches possibly suitable for steelhead spawning and rearing using a habitat model based on environmental envelopes (stream discharge, gradient, and temperature that takes a digital elevation model and climate data as inputs. We identified 151 patches of potentially suitable habitat with more than 10 km of stream habitat, with a total of 25,500 km of suitable habitat. We then measured the distances among habitat patches, and clustered together patches within 35 km of each other into 81 distinct habitat patches. Groups of fish using these 81 patches are hypothesized to be (or to have been independent populations for recovery planning purposes. Consideration of climate and elevation differences among the 81 habitat areas suggests that there are at least four major subdivisions within the Central Valley steelhead ESU that correspond to geographic regions defined by the Sacramento River basin, Suisun Bay area tributaries, San Joaquin tributaries draining the Sierra Nevada, and lower-elevation streams draining to the Buena Vista and Tulare basins, upstream of the San Joaquin River. Of these, it appears that the Sacramento River basin was the main source of steelhead production. Presently, impassable dams block access to 80% of historically available habitat, and block access to all historical spawning habitat for about 38% of the historical populations of steelhead.

Quantifying Direct and Indirect Impact of Future Climate on Sub-Arctic Hydrology

Science.gov (United States)

Endalamaw, A. M.; Bolton, W. R.; Young-Robertson, J. M.; Morton, D.; Hinzman, L. D.

2016-12-01

Projected future climate will have a significant impact on the hydrology of interior Alaskan sub-arctic watersheds, directly though the changes in precipitation and temperature patterns, and indirectly through the cryospheric and ecological impacts. Although the latter is the dominant factor controlling the hydrological processes in the interior Alaska sub-arctic, it is often overlooked in many climate change impact studies. In this study, we aim to quantify and compare the direct and indirect impact of the projected future climate on the hydrology of the interior Alaskan sub-arctic watersheds. The Variable Infiltration Capacity (VIC) meso-scale hydrological model will be implemented to simulate the hydrological processes, including runoff, evapotranspiration, and soil moisture dynamics in the Chena River Basin (area = 5400km2), located in the interior Alaska sub-arctic region. Permafrost and vegetation distribution will be derived from the Geophysical Institute Permafrost Lab (GIPL) model and the Lund-Potsdam-Jena Dynamic Global Model (LPJ) model, respectively. All models will be calibrated and validated using historical data. The Scenario Network for Alaskan and Arctic Planning (SNAP) 5-model average projected climate data products will be used as forcing data for each of these models. The direct impact of climate change on hydrology is estimated using surface parameterization derived from the present day permafrost and vegetation distribution, and future climate forcing from SNAP projected climate data products. Along with the projected future climate, outputs of GIPL and LPJ will be incorporated into the VIC model to estimate the indirect and overall impact of future climate on the hydrology processes in the interior Alaskan sub-arctic watersheds. Finally, we will present the potential hydrological and ecological changes by the end of the 21st century.

New data on the Western Transylvanides along the Ampoi Valley (Southern Apuseni Mts., Romania

Directory of Open Access Journals (Sweden)

Erika Suciu-Krausz

2006-04-01

Full Text Available In order to clarify some of the issues regarding the mineralogical content and the source area of the Cretaceous deposits from Ampoi Valley basin (Southern Apuseni Mountains fourteen lithologic logs were drawn from the Ampoi Valley both side tributaries (Slatinii, Ruzi, Vâltori, Valea lui Paul, Feneş, Călineasa, Fierului Brook, Bobului, Satului, Tăuţi, Galaţi, Presaca Ampoiului, Valea Mică and Valea Mare brooks. The main sedimentary rock types were identified (conglomerates, wacke and lithic sandstones, clays, and marls. The sandstones were classified according to the ternary diagrams. Their petrographic features revealed both a magmatic and a metamorphic source area for them.

Geomorphological characteristics of increased landslide activity in the Gudbrandsdalen valley, Norway

Science.gov (United States)

Heyerdahl, Håkon; Høydal, Øyvind

2016-04-01

The Gudbrandsdalen valley in Eastern Norway lies in a region where annual precipitation is generally low (down to 300 mm/year). The landslide activity has consequently historically been low, although the lower part of the valley sides generally is draped with thick layers of Quaternary deposits, primarily of glacial or glaciofluvial origin. The perception of natural hazards in the valley was previously primarily connected to flooding in the main river in the valley bottom during early summer, due to large discharges resulting from snowmelt in the mountainous regions west and east of the valley. However, several high-intensity events have changed the image of the region. Starting with a localized, but intense, landslide event in the Northern part of the valley in year 2008, two larger events covering almost the entire valley occurred in the years 2011 and 2013. A high number of landslides was triggered in all these events, including many flash floods and debris flows/debris slides in small and steep tributary rivers along the valley slopes. Landslide triggering covers different release mechanisms: In 2008, landslides were triggered without precipitation in not-frozen soil deposits without snow cover in the lower part of the valley. Groundwater flow through the permeable bedrock ("Otta schist") resulting from snow-melt in the elevated mountainous areas caused landslide triggering due to positive pore-water pressures forming at the bedrock surface below soil deposits, or at depressions in the terrain. Subsequent rainfall resulted in even more landslides being released. In later events (years 2011 and 2013) many landslides were caused by surface water taking new paths downslope, often due to man-made changes in existing waterways (typically poorly planned drainage solutions or new roads). Relatively small discharges in slopes with unconsolidated and easily erodible glacial deposits (typically lateral moraine) in many cases lead to small initial slides that down

Duck Valley Habitat Enhancement and Protection, 2001-2002 Progress Report.

Energy Technology Data Exchange (ETDEWEB)

Allen, Mattie H.; Sellman, Jake (Shoshone-Paiute Nation, Duck Valley Indian Reservation, Owyhee, NV)

2003-03-01

The Duck Valley Indian Reservation's Habitat Enhancement project is an ongoing project designed to enhance and protect critical riparian areas, natural springs, the Owhyee River and its tributaries, and native fish spawning areas on the Reservation. The project commenced in 1997 and addresses the Northwest Power Planning Council's measures 10.8C.2, 10.8C.3, and 10.8C.5 of the 1994 Columbia River Basin Fish and Wildlife Program. The performance period covers dates from April 2001 through August 2002.

UV-absorbing compounds in subarctic herbarium bryophytes

Energy Technology Data Exchange (ETDEWEB)

Huttunen, S. [Botany Division, Department of Biology, P.O. Box 3000, FIN-90 014 University of Oulu (Finland)]. E-mail: satu.huttunen@oulu.fi; Lappalainen, N.M. [Botany Division, Department of Biology, P.O. Box 3000, FIN-90 014 University of Oulu (Finland); Turunen, J. [Botany Division, Department of Biology, P.O. Box 3000, FIN-90 014 University of Oulu (Finland)

2005-01-01

The UV-B-absorbing compounds of herbarium specimens of 10 subarctic bryophyte species collected during the years 1926-1996 and available at the Botanical Museum, University of Oulu, were studied. We studied whether herbarium specimens reflect changes in the past radiation climate through their methanol-extractable compounds. The order of gametophytes based on the average amount of total compounds (sum of A{sub 280-320nm}) per mass from the lowest to the highest was Polytrichum commune, Pleurozium schreberi, Hylocomium splendens, Sphagnum angustifolium, Dicranum scoparium, Funaria hygrometrica, Sphagnum fuscum, Sphagnum warnstorfii, Sphagnum capillifolium and Polytrichastrum alpinum, and the amount of UV-B-absorbing compounds per specific surface area correlated with the summertime daily global radiation and latitude. P. alpinum, F. hygrometrica and three Sphagnum species seem to be good indicators for further studies. The amount of UV-B-absorbing compounds revealed no significant trends from the 1920s till the 1990s, with the exception of S. capillifolium, which showed a significant decreasing trend. - UV-B-absorbing compounds in subarctic herbarium bryophytes indicate the radiation climate of the collecting site and time.

UV-absorbing compounds in subarctic herbarium bryophytes

International Nuclear Information System (INIS)

Huttunen, S.; Lappalainen, N.M.; Turunen, J.

2005-01-01

The UV-B-absorbing compounds of herbarium specimens of 10 subarctic bryophyte species collected during the years 1926-1996 and available at the Botanical Museum, University of Oulu, were studied. We studied whether herbarium specimens reflect changes in the past radiation climate through their methanol-extractable compounds. The order of gametophytes based on the average amount of total compounds (sum of A 280-320nm ) per mass from the lowest to the highest was Polytrichum commune, Pleurozium schreberi, Hylocomium splendens, Sphagnum angustifolium, Dicranum scoparium, Funaria hygrometrica, Sphagnum fuscum, Sphagnum warnstorfii, Sphagnum capillifolium and Polytrichastrum alpinum, and the amount of UV-B-absorbing compounds per specific surface area correlated with the summertime daily global radiation and latitude. P. alpinum, F. hygrometrica and three Sphagnum species seem to be good indicators for further studies. The amount of UV-B-absorbing compounds revealed no significant trends from the 1920s till the 1990s, with the exception of S. capillifolium, which showed a significant decreasing trend. - UV-B-absorbing compounds in subarctic herbarium bryophytes indicate the radiation climate of the collecting site and time

ICMS tributary administration

Directory of Open Access Journals (Sweden)

Francisco Santana de Souza

2007-12-01

Full Text Available This work aims to analyze the essential tools for the management of the ICMS (Value-Added Tax on Sales and Services. It was developed a calculation proce­dure of this tax which permits to demonstrate the importance of correctly perform fiscal and accounting entries. In order to demonstrate this calculation procedure, it was used Financial Mathematics concepts of simple interest and simple trade discount together with article 33, 1989 of ICMS Law of the State of São Paulo. It was concluded that it is essential to have a precise ICMS tributary administration, in order to firstly avoid contentious administrative tributary which would imply ad­ditional and unnecessary costs to the organization and secondly to use tax evasion correctly in order to avoid excessive taxes payment. Thus, the appropriate use of both instruments will reflect into a positive cash flow for the organization.

Geohydrology and Water Quality of the Valley-Fill Aquifer System in the Upper Sixmile Creek and West Branch Owego Creek Valleys in the Town of Caroline, Tompkins County, New York

Science.gov (United States)

Miller, Todd S.

2009-01-01

, a school, and several farms and small businesses. Most groundwater that is withdrawn from pumped wells is returned to the groundwater system via septic systems. Groundwater in the upper and basal confined aquifers in the upper Sixmile Creek valley is under artesian conditions everywhere except where the water discharges to springs along bluffs in the western end of the Sixmile Creek valley. Principal sources of recharge to the confined aquifers are (1) the sides of the valley where the confined aquifers may extend up along the flank of the bedrock valley wall and crop out at land surface or are overlain and in contact with surficial coarse-grained deltaic and fluvial sediments that provide a pathway through which direct precipitation and seepage losses from tributary streams can reach the buried aquifers, or (2) where the buried aquifers are isolated and receive recharge only from adjacent fine-grained sediment and bedrock. The base-flow and runoff components of total streamflow at two streamgages, Sixmile Creek at Brooktondale and Sixmile Creek at Bethel Grove, were calculated using hydrograph-separation techniques from 2003 to 2007 discharge records. Base flow constituted 64 and 56 percent of the total annual flow at the Brooktondale and Bethel Grove streamgages, respectively. Water-quality samples were collected from 2003 to 2005, with 10 surface-water samples collected seasonally during base-flow conditions at the Sixmile Creek at Brooktondale streamgage, and 12 samples were collected during base-flow conditions at several selected tributaries from 2004 to 2005. The predominant cation detected in the surface-water samples was calcium, but moderate amounts of magnesium, silica, and sodium were also detected; the major anions were bicarbonate, chloride, and sulfate. Sodium and chloride concentrations were relatively low in all samples but increased downstream from the Sixmile Creek sampling site at Six Hundred Road near Slaterville Springs, NY, to B

Seismic response of the geologic structure underlying the Roman Colosseum and a 2-D resonance of a sediment valley

Directory of Open Access Journals (Sweden)

P. Labak

1995-06-01

Full Text Available The seismic response of the geologic structure beneath the Colosseum is investigated using a two-dimensional modeling for a vertically incident plane SH wave. Computations indicate that the southern part of the Colosseum may be exposed to a seismic ground motion with significantly larger amplitudes, differential motion and longer duration than the northern part. because the southern part of the Colosseum is underlain by a sedimentfilled valley created by sedimentary filling of the former tributary of the River Tiber. A 2-D resonance may develop in the valley. Unlike the previous theoretical studies on 2-D resonance in sediment-filled valleys, an effect of heterogeneous valley surroundings on the resonance is partly investigated. A very small sensitivity of the maximum spectral amplifications connected with the fundamental and first higher modes to the presence of a horizontal surface layer (with an intermediate velocity in the valley surroundings is observed in the studied models.

Depth to water in the western Snake River Plain and surrounding tributary valleys, southwestern Idaho and eastern Oregon, calculated using water levels from 1980 to 1988

Science.gov (United States)

Maupin, Molly A.

1991-01-01

The vulnerability of ground water to contamination in Idaho is being assessed by the ISHW/DEQ (Idaho Department of Health and Welfare, Division of Environmental Quality), using a modified version of the Environmental Protection Agency DRASTIC methods (Allers and others, 1985). The project was designed as a technique to: (1) Assign priorities for development of ground-water management and monitoring programs; (2) build support for, and public awareness of, vulnerability of ground water to contamination; (3) assist in the development of regulatory programs; and (4) provide access to technical data through the use of a GIS (geographic information system) (C. Grantham, Idaho Department of Health and Welfare, written commun., 1989). Digital representation of first-encountered water below land surface is an important element in evaluating vulnerability of ground water to contamination. Depth-to-water values were developed using existing data and computer software to construct a GIS data set to be combined with a soils data set developed by the SCS (Soul Conservation Service) and the IDHW/WQB (Idaho Department of Health and Welfare/Water Quality Bureau), and a recharge data set developed by the IDWR/RSF (idaho Department of Water Resources/Remote Sensing Facility). The USGS (U.S. Geological Survey) has developed digital depth-to-water values for eleven 1:100,00-scale quadrangles on the eastern Snake River Plain and surrounding tributary valleys.

Depth to water in the eastern Snake River Plain and surrounding tributary valleys, southwestern Idaho and eastern Oregon, calculated using water levels from 1980 to 1988

Science.gov (United States)

Maupin, Molly A.

1992-01-01

The vulnerability of ground water to contamination in Idaho is being assessed by the IDHW/DEQ (Idaho Department of Health and Welfare, Division of Environmental Quality), using a modified version of the Environmental Orotection Agency DRASTIC methods (Allers and others, 1985). The project was designed as a technique to: (1) Assign priorities for development of ground-water management and monitoring programs; (2) build support for, and public awareness of, vulnerability or ground water to contamination; (3) assist in the development of regulatory programs; and (4) provide access to technical data through the use of a GIS (geographic information system) (C. Grantha,, Idaho Department of Health and Welfare, written commun., 1989). A digital representation of first-encountered water below land surface is an important element in evaluating vulnerability of ground water to contamination. Depth-to-water values were developed using existing data and computer software to construct a GIS data set to be combined with a sols data set developed by the SCS (Soil Conservation Service) and IDHW/WQB (Idaho Department of Health and Welfare/Water Quality Bureau), and a recharge data set developed by the IDWR/RSF (Idaho Department of Water Resources/Remote Sensing Facility). The USGS (U.S. Geological Survey) developed digital depth-to-water values for eleven 1:100,000-scale quadrangles on the eastern Snake River Plain and surrounding tributary valleys.

Tributaries as richness source for Oligochaeta assemblage (Annelida of Neotropical dammed river

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FH Ragonha

Full Text Available Tributaries may serve as richness source for the river main channel and the zoobenthos community is a good tool to verify this kind of pattern. In this study, we aimed to characterize the benthic invertebrate assemblage in three tributaries associated to the Paraná River main channel, focusing in Oligochaeta community. We hypothesized that (i in tributaries, Oligochaeta are richer than the main river (Paraná River and (ii dammed tributary (Paranapanema River is poorly diverse than the others. Samples were conducted in Paranapanema, Baía and Ivinhema tributaries using a modified Petersen grab along three transects (samples conducted inside the tributary, in the mouth of each tributary and inside Paraná River. To analyze (i the difference between the richness and density among the tributaries and the Paraná River and (ii effect of each tributary transect on the Oligochaeta richness we used a nonparametric Kruskal-Wallis test. Changes in environmental variables and in richness and composition of Oligochaeta were summarized by Canonic Correspondence Analysis. It was registered 21 different benthic invertebrates taxa, being Oligochaeta assemblage with the highest density. Within Oligochaeta, Narapa bonettoi was the most abundant species, followed by Haplotaxis aedochaeta and Paranadrilus descolei. In our results we refused both hypotheses, because we did not found significant differences for richness and density between the tributaries and the main river, and also no difference between the three transects of each tributary were found. However, the tributaries less influenced by damming, especially the Baía recorded high richness. This corroborates their importance to diversity in the floodplain and the species of Oligochaeta reflect the peculiar characteristics of habitats within each tributaries.

Ground-water flow and simulated effects of development in Paradise Valley, a basin tributary to the Humboldt River in Humboldt County, Nevada

Science.gov (United States)

Prudic, David E.; Herman, M.E.

1996-01-01

A computer model was used to characterize ground-water flow in Paradise Valley, Nevada, and to evaluate probable long-term effects of five hypothetical development scenarios. One finding of the study is that concentrating pumping at the south end of Paradise Valley may increase underflow from the adjacent Humboldt River valley, and might affect flow in the river.

Lead and other heavy metals in stream sediments in the area of Meža valley

Directory of Open Access Journals (Sweden)

Julija Fux

2007-12-01

Full Text Available In the Meža valley, lead – zinc ore has been exploited and processed for more than 300 years, which has strongly influenced the environment.Previous investigation shave shown increased concentrations of lead and some other metals. At the end of the 20th century, the Meža River was considered a stream with the highest concentrations of heavy metals in Slovenia.When the mine and processing plants ceased to operate, the direct transfer of heavy metals into the environment has strongly decreased. However, the deposits of poor ore and wastes from ore processing have remained as an indirect source of heavy metal pollution. From those places heavy metals have been washed out into the nearby streams, and carried into the Meža River and further into the Drava River. Chemical analysis of the Meža River and its tributaries has shown heavy pollution of the upper Meža River sediments with lead, zinc, molybdenum and cadmium, and partly with arsenic. In the lower Meža valley, those concentrations are mildly decreased. Concentrations of cobalt, chrome, copper and nickel are increased in the area around Ravne as a result of the ironworks industry. Mušenik and Jančarjev potok, both tributaries of the Meža River, contribute a high portion of heavy metal load to the Meža River. A specific case is Helenski potok,in which the concentrations of heavy metals strongly surpass the concentrations measured at all other locations. Although more than 10 years have passed since the mine and ore processing plant in the upper Meža valley were closed, the production has ceased and the rehabilitation measures have been taken, the environment in the upper Meža valley is still highly polluted.

Potential impacts of damming the Juba Valley, western Somalia: Insights from geomorphology and alluvial history

Science.gov (United States)

Williams, Martin

2014-05-01

In 1988 plans were well advanced to dam the Juba River in western Somalia. The aims of the Baardheere Dam Project were to generate hydroelectric power for the capital Mogadishu, and to provide water for irrigation in the Juba Valley. A reconnaissance survey on foot along 500 km of the river upstream of the proposed dam site at Baardheere and detailed geomorphic mapping from air photos provided a basis for reconstructing the late Quaternary alluvial history of the river and for assessing the potential impact of the proposed dam. The Juba River rises in the Ethiopian Highlands and is the only river in Somalia that flows to the sea. Its history reflects climatic events in Ethiopia, where the Rift Valley lakes were very low during the LGM (21±2 ka), and high for about 5, 000 years before and after then. Cave deposits in Somalia indicate wetter conditions at 13, 10, 7.5 and 1.5 ka. Alluvial terraces in the Juba Valley range in age from late Pleistocene to late Holocene but only attain a few metres above the present floodplain. This is because the dry tributary valleys contain limestone caves and fissures that divert any high flows from the parent river underground, a process not known when the project was first approved. The oldest preserved terrace was cemented by calcrete by 40 ka. Alluvial gravels were deposited at the outlet of dry tributary valleys during times of episodic high-energy flow between 26 ka and 28 ka. Finely laminated shelly sands accumulated at 10 ka to form the 5 m terrace. The 2 m terrace was laid down 3.2 ka ago as a slackwater deposit. The lack of high-level alluvial terraces raises doubts over plans to dam the river, since rapid leakage would occur from side valleys and the reservoir would not attain the height needed to generate hydroelectric power. It would submerge all existing arable land along the river. Finally, the presence in the late Holocene alluvium of the sub-fossil gastropods Bulinus truncatus and Biomphalaria pfeifferi, which are

Temperature and Discharge on a Highly Altered Stream in Utah's Cache Valley

OpenAIRE

Pappas, Andy

2013-01-01

To study the River Continuum Concept (RCC) and the Serial Discontinuity Hypothesis (SDH), I looked at temperature and discharge changes along 52 km of the Little Bear River in Cache Valley, Utah. The Little Bear River is a fourth order stream with one major reservoir, a number of irrigation diversions, and one major tributary, the East Fork of the Little Bear River. Discharge data was collected at six sites on 29 September 2012 and temperature data was collected hourly at eleven sites from 1 ...

Lagrangian study of transport of subarctic water across the Subpolar Front in the Japan Sea

Science.gov (United States)

Prants, Sergey V.; Uleysky, Michael Yu.; Budyansky, Maxim V.

2018-05-01

The southward near-surface transport of transformed subarctic water across the Subpolar Front in the Japan Sea is simulated and analyzed based on altimeter data from January 1, 1993 to December 31, 2017. Computing Lagrangian indicators for a large number of synthetic particles, advected by the AVISO velocity field, we find preferred transport pathways across the Subpolar Front. The southward transport occurs mainly in the central part of the frontal zone due to suitable dispositions of mesoscale eddies promoting propagation of subarctic water to the south. It is documented with the help of Lagrangian origin and L-maps and verified by the tracks of available drifters. The transport of transformed subarctic water to the south is compared with the transport of transformed subtropical water to the north simulated by Prants et al. (Nonlinear Process Geophys 24(1):89-99, 2017c).

Geomorphic and erosion studies at the Western New York Nuclear Service Center, West Valley, New York

International Nuclear Information System (INIS)

Boothroyd, J.C.; Timson, B.S.; Dana, R.H. Jr.

1979-12-01

This report is one in a series of related reports presenting the results of a study to evaluate the containment capability of a low-level, solid radioactive waste-burial ground at West valley, NY. This project is the first portion of a detailed geomorphic and erosion study of the reach of Buttermilk Creek adjacent to the waste-burial site. Buttermilk Creek valley is being actively modified by fluvial transport, lateral channel scour, and landsliding. High surface runoff rates create highly variable but enhanced stream flows that result in coarse-gravel sediment transport within the active channel. The active channel morphology indicates that braided stream processes are common in Buttermilk, leading to active channel down-cutting and lateral migration. Where lateral migration of the active channel has undercut valley wall slopes, large-scale landsliding enhances valley wall retreat. A major site of historical and recent slide activity lies adjacent to the low-level burial trenches. Initial, post-glacial Buttermilk Creek incision began before 9920 +- 240 B.P., the age of the oldest dated fluvial terrace. Future evolution of the system is expected to proceed by Buttermilk valley lowering, tributary and landslide widening, and stream capture

Mercury Contributions from Flint Creek and other Tributaries to the Upper Clark Fork River in Northwestern Montana

Science.gov (United States)

Langner, H.; Young, M.; Staats, M. F.

2013-12-01

Methylmercury contamination in biota is a major factor diminishing the environmental quality of the Upper Clark Fork River (CFR), e.g. by triggering human consumption limits of fish. The CFR is subject to one of the largest Superfund cleanup projects in the US, but remediation and restoration is currently focused exclusively on other mining-related contaminants (As, Cu, Zn, Pb, Cd), which may be counterproductive with respect to the bio-availability of mercury, for example by creation of wetlands along mercury-contaminated reaches of the river. The identification and elimination of Hg sources is an essential step toward reducing the methylmercury exposure in the biota of the CFR watershed because a strong correlation exists between total mercury levels in river sediment and methylmercury levels in aquatic life. We analyzed duplicate samples from the top sediment layer of the main stem and significant tributaries to the Clark Fork River along a 240 km reach between Butte, MT and downstream of the Missoula Valley. Mercury concentrations were 1.3 × 1.6 (mean × SD, n = 35) in the main stem. Concentrations in tributaries varied widely (0.02 to 85 mg/kg) and seemed only loosely related to the number of historic precious metal mines in the watershed. In the upper reach of the CFR, elevated Hg levels are likely caused by residual contaminated sediments in the flood plain. Levels tend to decrease downstream until Drummond, MT, where Flint Creek contributes a significant amount of mercury, causing Hg levels in the main stem CFR to increase from 0.7 to 4 mg/kg. Levels continue to decrease downstream. Flint Creek is the single largest contributor of Hg to the CFR. Detailed sampling of the main stem Flint Creek and tributaries (26 sites) showed extremely high levels in two tributaries (22 to 85 mg/kg) where historic milling operations were located. Elimination of these point sources may be accomplished comparatively economically and may significantly reduce mercury levels in

Aufeis accumulations in stream bottoms in arctic and subarctic environments as a possible indicator of geologic structure: Chapter F in Recent U.S. Geological Survey studies in the Tintina Gold Province, Alaska, United States, and Yukon, Canada--results of a 5-year project

Science.gov (United States)

Wanty, Richard B.; Wang, Bronwen; Vohden, Jim; Day, Warren C.; Gough, Larry P.; Gough, Larry P.; Day, Warren C.

2007-01-01

Thick accumulations of ice, called “aufeis,” form during winter along stream and river valleys in arctic and subarctic regions. In high-gradient alpine streams, aufeis forms mostly as a result of ground-water discharge into the stream channel. The ice occludes this discharge, perturbing the steady-state condition, and causing an incremental rise in the local water table until discharge occurs higher on the stream bank above the previously formed ice. Successive freezing of onlapping ice layers can lead to aufeis accumulations several meters thick.

Bacterial community structure and soil properties of a subarctic tundra soil in Council, Alaska.

Science.gov (United States)

Kim, Hye Min; Jung, Ji Young; Yergeau, Etienne; Hwang, Chung Yeon; Hinzman, Larry; Nam, Sungjin; Hong, Soon Gyu; Kim, Ok-Sun; Chun, Jongsik; Lee, Yoo Kyung

2014-08-01

The subarctic region is highly responsive and vulnerable to climate change. Understanding the structure of subarctic soil microbial communities is essential for predicting the response of the subarctic soil environment to climate change. To determine the composition of the bacterial community and its relationship with soil properties, we investigated the bacterial community structure and properties of surface soil from the moist acidic tussock tundra in Council, Alaska. We collected 70 soil samples with 25-m intervals between sampling points from 0-10 cm to 10-20 cm depths. The bacterial community was analyzed by pyrosequencing of 16S rRNA genes, and the following soil properties were analyzed: soil moisture content (MC), pH, total carbon (TC), total nitrogen (TN), and inorganic nitrogen (NH4+ and NO3-). The community compositions of the two different depths showed that Alphaproteobacteria decreased with soil depth. Among the soil properties measured, soil pH was the most significant factor correlating with bacterial community in both upper and lower-layer soils. Bacterial community similarity based on jackknifed unweighted unifrac distance showed greater similarity across horizontal layers than through the vertical depth. This study showed that soil depth and pH were the most important soil properties determining bacterial community structure of the subarctic tundra soil in Council, Alaska. © 2014 The Authors. FEMS Microbiology Ecology published by John Wiley & Sons Ltd on behalf of the Federation of European Microbiological Societies.

Hydrogeology and water quality of the West Valley Creek Basin, Chester County, Pennsylvania

Science.gov (United States)

Senior, Lisa A.; Sloto, Ronald A.; Reif, Andrew G.

1997-01-01

The West Valley Creek Basin drains 20.9 square miles in the Piedmont Physiographic Province of southeastern Pennsylvania and is partly underlain by carbonate rocks that are highly productive aquifers. The basin is undergoing rapid urbanization that includes changes in land use and increases in demand for public water supply and wastewater disposal. Ground water is the sole source of supply in the basin.West Valley Creek flows southwest in a 1.5-mile-wide valley that is underlain by folded and faulted carbonate rocks and trends east-northeast, parallel to regional geologic structures. The valley is flanked by hills underlain by quartzite and gneiss to the north and by phyllite and schist to the south. Surface water and ground water flow from the hills toward the center of the valley. Ground water in the valley flows west-southwest parallel to the course of the stream. Seepage investigations identified losing reaches in the headwaters area where streams are underlain by carbonate rocks and gaining reaches downstream. Tributaries contribute about 75 percent of streamflow. The ground-water and surface-water divides do not coincide in the carbonate valley. The ground-water divide is about 0.5 miles west of the surface-water divide at the eastern edge of the carbonate valley. Underflow to the east is about 1.1 inches per year. Quarry dewatering operations at the western edge of the valley may act partly as an artificial basin boundary, preventing underflow to the west. Water budgets for 1990, a year of normal precipitation (45.8 inches), and 1991, a year of sub-normal precipitation (41.5 inches), were calculated. Streamflow was 14.61 inches in 1990 and 12.08 inches in 1991. Evapotranspiration was estimated to range from 50 to 60 percent of precipitation. Base flow was about 62 percent of streamflow in both years. Exportation by sewer systems was about 3 inches from the basin and, at times, equaled base flow during the dry autumn of 1991. Recharge was estimated to be 18

Estimation of stream conditions in tributaries of the Klamath River, northern California

Science.gov (United States)

Manhard, Christopher V.; Som, Nicholas A.; Jones, Edward C.; Perry, Russell W.

2018-01-01

Because of their critical ecological role, stream temperature and discharge are requisite inputs for models of salmonid population dynamics. Coho Salmon inhabiting the Klamath Basin spend much of their freshwater life cycle inhabiting tributaries, but environmental data are often absent or only seasonally available at these locations. To address this information gap, we constructed daily averaged water temperature models that used simulated meteorological data to estimate daily tributary temperatures, and we used flow differentials recorded on the mainstem Klamath River to estimate daily tributary discharge. Observed temperature data were available for fourteen of the major salmon bearing tributaries, which enabled estimation of tributary-specific model parameters at those locations. Water temperature data from six mid-Klamath Basin tributaries were used to estimate a global set of parameters for predicting water temperatures in the remaining tributaries. The resulting parameter sets were used to simulate water temperatures for each of 75 tributaries from 1980-2015. Goodness-of-fit statistics computed from a cross-validation analysis demonstrated a high precision of the tributary-specific models in predicting temperature in unobserved years and of the global model in predicting temperatures in unobserved streams. Klamath River discharge has been monitored by four gages that broadly intersperse the 292 kilometers from the Iron Gate Dam to the Klamath River mouth. These gages defined the upstream and downstream margins of three reaches. Daily discharge of tributaries within a reach was estimated from 1980-2015 based on drainage-area proportionate allocations of the discharge differential between the upstream and downstream margin. Comparisons with measured discharge on Indian Creek, a moderate-sized tributary with naturally regulated flows, revealed that the estimates effectively approximated both the variability and magnitude of discharge.

Landform Evolution of the Zanskar Valley, Ladakh Himalaya.

Science.gov (United States)

Chahal, P.; Kumar, A.; Sharma, P.; Sundriyal, Y.; Srivastava, P.

2017-12-01

Zanskar River flow from south-west to north-east, perpendicularly through Higher Himalayan crystalline sequences, Tethyan sedimentary sequences, and Indus Molasses; and finally merge with the Indus River at Nimu. Geologically, the Indus valley is bounded by Ladakh Batholith in the north and highly folded and thrusted Zanskar mountain ranges in the south. Sedimentary sequences of Zanskar ranges are largely of continental origin, which were uplifted and deformed via several north verging thrusts, where Zanskar counter thrust, Choksti and Indus-Bazgo thrusts are important thrust zone, and there is atleast 36 km of crustal shortening in the Zanskar section which continued from middle Miocene to the late Pleistocene. This shortening is accommodated mainly by north or north-east directed Zanskar backthrusts. Two major tributaries of Zanskar: Tsrapchu and Doda, flow in the headwaters, along the strike of South Tibetan Detachment System (STDs), an east-west trending regional fault. The present study incorporate field sedimentology, geomorphology and chronology of landform associated with Zanskar valley. In the upper Zanskar, alluvial fan, valley fill and strath terraces configured the major landforms with paleo-lake deposits­­­ in the area between the fans. The lower catchment, at the confluence of Zanskar and Indus rivers, exhibit mainly valley fill terraces and strath terraces. Chronology suggests diachronous aggradation in the upper and lower Zanskar catchments. In the upper Zanskar large scale valley aggradation took place with simultaneously fan progradation and flooding events from 45-15 ka. Luminescence chronology of the lower Zanskar indicates aggradation from 145-55 ka and 18-12 ka. The two aggradation basins are separated by a deep V-shaped gorge which is approximately 60 km long. The longitudinal profile of the Zanskar River shows several local convexities marking knick point zone, which suggests tectonically controlled topography.

Occurrence and Transport of Diazinon in the Sacramento River and Selected Tributaries, California, during Two Winter Storms, January?February 2001

Science.gov (United States)

Dileanis, Peter D.; Brown, David L.; Knifong, Donna L.; Saleh, Dina

2003-01-01

Diazinon, an organophosphate insecticide, is applied as an orchard dormant spray in the Sacramento Valley during the winter months when the area receives most of its annual rainfall. During winter rainstorms that frequently follow dormant spray applications, some of the applied pesticide is transported in storm runoff to the Sacramento River and its tributaries. Diazinon is also used to control insect pests on residential and commercial properties in urban areas and is frequently detected in urban storm runoff draining into the Sacramento River system. Between January 24 and February 14, 2001, diazinon concentrations and loads were measured in the Sacramento River and selected tributaries during two winter storms that occurred after dormant spray applications were made to orchards in the Sacramento Valley. Water samples were collected at 21 sites that represented agricultural and urban inputs on a variety of scales, from small tributaries and drains representing local land use to main-stem river sites representing regional effects. Concentrations of diazinon ranged from below laboratory reporting levels to 1,380 nanograms per liter (ng/L), with a median of 55 ng/L during the first monitored storm and 26 ng/L during the second. The highest concentrations were observed in small channels draining predominantly agricultural land. About 26,000 pounds of diazinon were reported applied to agricultural land in the study area just before and during the monitoring period. About 0.2 percent of the applied insecticide appeared to be transported to the lower Sacramento River during that period. The source of about one third of the total load measured in the lower Sacramento River appears to be in the portion of the drainage basin upstream of the city of Colusa. About 12 percent of the diazinon load in the lower Sacramento River was transported from the Feather River Basin, which drains much of the mountainous eastern portions of the Sacramento River Basin. Diazinon use in the

PEARLS OF THE PČINJA VALLEY – RURAL TOURISM ATTRACTIONS OF THIS AREA

Directory of Open Access Journals (Sweden)

Svetlana Trajković

2013-10-01

Full Text Available River Valley Pčinja, with its source part and tributaries that make up the Aegean Sea with its configuration, where the gorge turns between nearby mountains and flat areas, meadows, gardens and of our arable land, remains of old mills, houses and villages, which, still do not leave the inhabitants of this region, contains tourist potential. This valley is adorned with rich flora and fauna where one can see examples of the unique flora and fauna, with its diversity and natural material in the form of a "devil's stone" Witness antiquities and places of worship as well as a special value of the Monastery of St. Prohor of Pcinja. The pleasant climate and in some areas of the river gurgling disrupts primordial peace and makes the holiday for eyes, soul of every lover of nature.

Estimation of permafrost thawing rates in a sub-arctic catchment using recession flow analysis

Directory of Open Access Journals (Sweden)

S. W. Lyon

2009-05-01

Full Text Available Permafrost thawing is likely to change the flow pathways taken by water as it moves through arctic and sub-arctic landscapes. The location and distribution of these pathways directly influence the carbon and other biogeochemical cycling in northern latitude catchments. While permafrost thawing due to climate change has been observed in the arctic and sub-arctic, direct observations of permafrost depth are difficult to perform at scales larger than a local scale. Using recession flow analysis, it may be possible to detect and estimate the rate of permafrost thawing based on a long-term streamflow record. We demonstrate the application of this approach to the sub-arctic Abiskojokken catchment in northern Sweden. Based on recession flow analysis, we estimate that permafrost in this catchment may be thawing at an average rate of about 0.9 cm/yr during the past 90 years. This estimated thawing rate is consistent with direct observations of permafrost thawing rates, ranging from 0.7 to 1.3 cm/yr over the past 30 years in the region.

Wind-driven circulation in the subarctic north Pacific using altimeter ...

Indian Academy of Sciences (India)

R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

of the wind stress curl are also related to the variation of the subarctic gyre. Though the correlation .... mum in spring, accounting for 41% of all the vari- ance. This estimate ..... plays an important role as a western boundary and it is also located ...

Interrelations among pyroclastic surge, pyroclastic flow, and lahars in Smith Creek valley during first minutes of 18 May 1980 eruption of Mount St. Helens, USA

Science.gov (United States)

Brantley, S.R.; Waitt, R.B.

1988-01-01

A devastating pyroclastic surge and resultant lahars at Mount St. Helens on 18 May 1980 produced several catastrophic flowages into tributaries on the northeast volcano flank. The tributaries channeled the flows to Smith Creek valley, which lies within the area devastated by the surge but was unaffected by the great debris avalanche on the north flank. Stratigraphy shows that the pyroclastic surge preceded the lahars; there is no notable "wet" character to the surge deposits. Therefore the lahars must have originated as snowmelt, not as ejected water-saturated debris that segregated from the pyroclastic surge as has been inferred for other flanks of the volcano. In stratigraphic order the Smith Creek valley-floor materials comprise (1) a complex valley-bottom facies of the pyroclastic surge and a related pyroclastic flow, (2) an unusual hummocky diamict caused by complex mixing of lahars with the dry pyroclastic debris, and (3) deposits of secondary pyroclastic flows. These units are capped by silt containing accretionary lapilli, which began falling from a rapidly expanding mushroom-shaped cloud 20 minutes after the eruption's onset. The Smith Creek valley-bottom pyroclastic facies consists of (a) a weakly graded basal bed of fines-poor granular sand, the deposit of a low-concentration lithic pyroclastic surge, and (b) a bed of very poorly sorted pebble to cobble gravel inversely graded near its base, the deposit of a high-concentration lithic pyroclastic flow. The surge apparently segregated while crossing the steep headwater tributaries of Smith Creek; large fragments that settled from the turbulent surge formed a dense pyroclastic flow along the valley floor that lagged behind the front of the overland surge. The unusual hummocky diamict as thick as 15 m contains large lithic clasts supported by a tough, brown muddy sand matrix like that of lahar deposits upvalley. This unit contains irregular friable lenses and pods meters in diameter, blocks incorporated from

33 CFR 117.591 - Charles River and its tributaries.

Science.gov (United States)

2010-07-01

... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Charles River and its tributaries... BRIDGES DRAWBRIDGE OPERATION REGULATIONS Specific Requirements Massachusetts § 117.591 Charles River and its tributaries. (a) The following requirements apply to all bridges across the Charles River and it's...

Geohydrology and water quality of the stratified-drift aquifers in Upper Buttermilk Creek and Danby Creek Valleys, Town of Danby, Tompkins County, New York

Science.gov (United States)

Miller, Todd S.

2015-11-20

In 2006, the U.S. Geological Survey, in cooperation with the Town of Danby and the Tompkins County Planning Department, began a study of the stratified-drift aquifers in the upper Buttermilk Creek and Danby Creek valleys in the Town of Danby, Tompkins County, New York. In the northern part of the north-draining upper Buttermilk Creek valley, there is only one sand and gravel aquifer, a confined basal unit that overlies bedrock. In the southern part of upper Buttermilk Creek valley, there are as many as four sand and gravel aquifers, two are unconfined and two are confined. In the south-draining Danby Creek valley, there is an unconfined aquifer consisting of outwash and kame sand and gravel (deposited by glacial meltwaters during the late Pleistocene Epoch) and alluvial silt, sand, and gravel (deposited by streams during the Holocene Epoch). In addition, throughout the study area, there are several small local unconfined aquifers where large tributaries deposited alluvial fans in the valley.

Trichinella in arctic, subarctic and temperate regions

DEFF Research Database (Denmark)

Kapel, C. M O

1997-01-01

The transmission and occurrence of Trichinella spp according to the zoogeography of different climatic conditions, socioeconomy and human activity are discussed. Comparing arctic, subarctic and temperate regions, it appears that the species of Trichinella present, the composition of the fauna...... and the human activity are all very important interacting factors affecting epidemiology. In Greenland, where only sylvatic trichinellosis is present, the high prevalence in wildlife appears closely connected with polar bear hunting. In the Scandinavian countries, the prevalence of both sylvatic and domestic...

Pulsed flows, tributary inputs, and food web structure in a highly regulated river

Science.gov (United States)

Sabo, John; Caron, Melanie; Doucett, Richard R.; Dibble, Kimberly L.; Ruhi, Albert; Marks, Jane; Hungate, Bruce; Kennedy, Theodore A.

2018-01-01

1.Dams disrupt the river continuum, altering hydrology, biodiversity, and energy flow. Although research indicates that tributary inputs have the potential to dilute these effects, knowledge at the food web level is still scarce.2.Here we examined the riverine food web structure of the Colorado River below Glen Canyon Dam, focusing on organic matter sources, trophic diversity, and food chain length. We asked how these components respond to pulsed flows from tributaries following monsoon thunderstorms that seasonally increase streamflow in the American Southwest.3.Tributaries increased the relative importance of terrestrial organic matter, particularly during the wet season below junctures of key tributaries. This contrasted with the algal-based food web present immediately below Glen Canyon Dam.4.Tributary inputs during the monsoon also increased trophic diversity and food chain length: food chain length peaked below the confluence with the largest tributary (by discharge) in Grand Canyon, increasing by >1 trophic level over a 4-5 kilometre reach possibly due to aquatic prey being flushed into the mainstem during heavy rain events.5.Our results illustrate that large tributaries can create seasonal discontinuities, influencing riverine food web structure in terms of allochthony, food web diversity, and food chain length.6.Synthesis and applications. Pulsed flows from unregulated tributaries following seasonal monsoon rains increase the importance of terrestrially-derived organic matter in large, regulated river food webs, increasing food chain length and trophic diversity downstream of tributary inputs. Protecting unregulated tributaries within hydropower cascades may be important if we are to mitigate food web structure alteration due to flow regulation by large dams. This is critical in the light of global hydropower development, especially in megadiverse, developing countries where dam placement (including completed and planned structures) is in tributaries.

The fishermen were right: experimental evidence for tributary refuge hypothesis during floods.

Science.gov (United States)

Koizumi, Itsuro; Kanazawa, Yukiyo; Tanaka, Yuuki

2013-05-01

Fishermen often anecdotally report an unexpected increase of fish caught in small tributary streams during floods, presumably due to refuge-seeking behavior from the main stem. From a population perspective, this implies the significance of refuge habitats and connectivity for population viability against natural disturbances. Despite the plausibility, however, surprisingly few studies have examined the tributary refuge hypothesis, mainly due to the difficulty in field survey during floods. Here, we made use of a large-scale controlled flood to assess whether fishes move into tributaries during flooding in the main stem. A planned water release from the Satsunai River Dam located on Hokkaido Island in Japan rapidly increased the main stem discharge by more than 20-fold. Before, during, and after flooding censuses in four tributaries provided evidence of the refuge-seeking behavior of fishes from the main stem. For example, more than 10 Dolly Varden char, a salmonid fish, were caught in a tributary during the flood, even though almost no individuals were captured before or after the flood. The fish responded immediately to the flooding, suggesting the need for studies during disturbances. In addition, the likelihood of refuge movements varied among tributaries, suggesting the importance of local environmental differences between tributary and the main stem habitats. This is the first study to experimentally confirm the tributary refuge hypothesis, and underscores the roles of habitat diversity and connectivity during disturbances, even though some habitats are not used during normal conditions.

Aircraft-measured indirect cloud effects from biomass burning smoke in the Arctic and subarctic

Directory of Open Access Journals (Sweden)

L. M. Zamora

2016-01-01

Full Text Available The incidence of wildfires in the Arctic and subarctic is increasing; in boreal North America, for example, the burned area is expected to increase by 200–300 % over the next 50–100 years, which previous studies suggest could have a large effect on cloud microphysics, lifetime, albedo, and precipitation. However, the interactions between smoke particles and clouds remain poorly quantified due to confounding meteorological influences and remote sensing limitations. Here, we use data from several aircraft campaigns in the Arctic and subarctic to explore cloud microphysics in liquid-phase clouds influenced by biomass burning. Median cloud droplet radii in smoky clouds were  ∼  40–60 % smaller than in background clouds. Based on the relationship between cloud droplet number (Nliq and various biomass burning tracers (BBt across the multi-campaign data set, we calculated the magnitude of subarctic and Arctic smoke aerosol–cloud interactions (ACIs, where ACI  =  (1∕3 × dln(Nliq∕dln(BBt to be  ∼  0.16 out of a maximum possible value of 0.33 that would be obtained if all aerosols were to nucleate cloud droplets. Interestingly, in a separate subarctic case study with low liquid water content ( ∼  0.02 g m−3 and very high aerosol concentrations (2000–3000 cm−3 in the most polluted clouds, the estimated ACI value was only 0.05. In this case, competition for water vapor by the high concentration of cloud condensation nuclei (CCN strongly limited the formation of droplets and reduced the cloud albedo effect, which highlights the importance of cloud feedbacks across scales. Using our calculated ACI values, we estimate that the smoke-driven cloud albedo effect may decrease local summertime short-wave radiative flux by between 2 and 4 W m−2 or more under some low and homogeneous cloud cover conditions in the subarctic, although the changes should be smaller in high surface albedo regions of the

Coho Salmon Habitat in a Changing Environment-Green Valley Creek, Graton, California

Science.gov (United States)

O'Connor, M. D.; Kobor, J. S.; Sherwood, M. N.

2013-12-01

Green Valley Creek (GVC) is a small (101 sq km) aquatic habitat refugium in the Russian River watershed (3,840 sq km) in coastal northern California. Coho salmon (Onchorhynchus kisutch) is endangered per the Federal Endangered Species Act, and GVC is one stream where coho have persisted. Fish surveys in GVC have found high species diversity, growth rates, and over-summer survival. The upper portion of GVC comprises a principal tributary (20 sq km) that provides spawning and rearing habitat for coho. The second principal tributary, Atascadero Creek, is comparable in size, but has few fish. Atascadero Creek and lower GVC have broad, densely vegetated floodplains. A Recovery Plan for the Central Coastal California coho Evolutionarily Significant Unit has been developed by the National Marine Fisheries Service (NMFS), which applies to the Russian River and its tributaries. Cooperative research regarding fish populations and habitat, a captive breeding and release program for native coho salmon, and efforts to plan for and restore habitat are ongoing. These regional efforts are particularly active in GVC, and participants include NMFS, the California Department of Fish and Wildlife, the Gold Ridge Resource Conservation District, the California Coastal Conservancy, the University of California Cooperative Extension, and the National Fish and Wildlife Foundation, among others. Our research focuses on hydrologic, geomorphic and hydrogeologic characteristics of the watershed in relation to aquatic habitat. Natural watershed factors contributing to habitat for coho include proximity to the coastal summer fog belt with cool temperatures, the Wilson Grove Formation aquifer that maintains dry season stream flow, and structural geology favorable for active floodplain morphology. Human impacts include water use and agriculture and rural residential development. Historic human impacts include stream clearing and draining of wetlands and floodplain for agriculture, which likely

Residues of cypermethrin and endosulfan in soils of Swat valley

Directory of Open Access Journals (Sweden)

M. Nafees

2009-05-01

Full Text Available Swat Valley was studied for two widely used pesticides; cypermethrin and endosulfan. A total of 63 soil samples were collected from 27 villages selected for this purpose. The collected soil samples were extracted with n-hexane, pesticides were separated, identified and quantified by a GC-ECD system. Endosulfan was 0.24 - 1.51 mg kg-1 and 0.13 - 12.67 mg kg-1 in rainfed and irrigated areas, respectively. The residual level of cypermethrin was comparatively high with a level of0.14 to 27.62 mg kg-1 and 0.05 to 73.75 mg kg-1 in rainfed and irrigated areas, respectively. For assessing the possible causes of pesticide residues in soil, 360 farmers were interviewed. It was found that both, cypermethrin and endosulfan, apart from agriculture were also widely misused for fishing in the entire stretch of River Swat and its tributaries. River Swat is used for irrigation in Swat Valley and this wide misuse of pesticides can also contribute to pesticide residue in soil.

Selected References on Arctic and Subarctic Prehistory and Ethnology. Revised.

Science.gov (United States)

Fitzhugh, William, Comp.; Loring, Stephen, Comp.

This bibliography provides an introduction to the current literature, in English, on arctic and subarctic prehistory and ethnology. Leads for further research will be found in section 1. Publications listed are not available from the Smithsonian Institution but copies may be found in larger libraries or obtained through inter-library loan.…

Titan's fluvial valleys: Morphology, distribution, and spectral properties

Science.gov (United States)

Langhans, M.H.; Jaumann, R.; Stephan, K.; Brown, R.H.; Buratti, B.J.; Clark, R.N.; Baines, K.H.; Nicholson, P.D.; Lorenz, R.D.; Soderblom, L.A.; Soderblom, J.M.; Sotin, Christophe; Barnes, J.W.; Nelson, R.

2012-01-01

Titan's fluvial channels have been investigated based on data obtained by the Synthetic Aperture Radar (SAR) instrument and the Visible and Infrared Mapping Spectrometer (VIMS) onboard the Cassini spacecraft. In this paper, a database of fluvial features is created based on radar-SAR data aiming to unveil the distribution and the morphologic and spectral characteristics of valleys on Titan on a global scale. It will also study the spatial relations between fluvial valleys and Titan's geologic units and spectral surface units which have become accessible thanks to Cassini-VIMS data. Several distinct morphologic types of fluvial valleys can be discerned by SAR-images. Dendritic valley networks appear to have much in common with terrestrial dendritic systems owing to a hierarchical and tree-shaped arrangement of the tributaries which is indicative of an origin from precipitation. Dry valleys constitute another class of valleys resembling terrestrial wadis, an indication of episodic and strong flow events. Other valley types, such as putative canyons, cannot be correlated with rainfall based on their morphology alone, since it cannot be ruled out that they may have originated from volcanic/tectonic action or groundwater sapping. Highly developed and complex fluvial networks with channel lengths of up to 1200 km and widths of up to 10 km are concentrated only at a few locations whereas single valleys are scattered over all latitudes. Fluvial valleys are frequently found in mountainous areas. Some terrains, such as equatorial dune fields and undifferentiated plains at mid-latitudes, are almost entirely free of valleys. Spectrally, fluvial terrains are often characterized by a high reflectance in each of Titan's atmospheric windows, as most of them are located on Titan's bright 'continents'. Nevertheless, valleys are spatially associated with a surface unit appearing blue due to its higher reflection at 1.3??m in a VIMS false color RGB composite with R: 1.59/1.27??m, G: 2

Processes of Terrace Formation on the Piedmont of the Santa Cruz River Valley During Quaternary Time, Green Valley-Tubac Area, Southeastern Arizona

Science.gov (United States)

Lindsey, David A.; Van Gosen, Bradley S.

2010-01-01

In this report we describe a series of stepped Quaternary terraces on some piedmont tributaries of the Santa Cruz River valley in southeastern Arizona. These terraces began to form in early Pleistocene time, after major basin-and-range faulting ceased, with lateral planation of basin fill and deposition of thin fans of alluvium. At the end of this cycle of erosion and deposition, tributaries of the Santa Cruz River began the process of dissection and terrace formation that continues to the present. Vertical cutting alternated with periods of equilibrium, during which streams cut laterally and left thin deposits of channel fill. The distribution of terraces was mapped and compiled with adjacent mapping to produce a regional picture of piedmont stream history in the middle part of the Santa Cruz River valley. For selected tributaries, the thickness of terrace fill was measured, particle size and lithology of gravel were determined, and sedimentary features were photographed and described. Mapping of terrace stratigraphy revealed that on two tributaries, Madera Canyon Wash and Montosa Canyon Wash, stream piracy has played an important role in piedmont landscape development. On two other tributaries, Cottonwood Canyon Wash and Josephine Canyon Wash, rapid downcutting preempted piracy. Two types of terraces are recognized: erosional and depositional. Gravel in thin erosional terraces has Trask sorting coefficients and sedimentary structures typical of streamflood deposits, replete with bar-and-swale surface topography on young terraces. Erosional-terrace fill represents the channel fill of the stream that cuts the terrace; the thickness of the fill indicates the depth of channel scour. In contrast to erosional terraces, depositional terraces show evidence of repeated deposition and net aggradation, as indicated by their thickness (as much as 20+ m) and weakly bedded structure. Depositional terraces are common below mountain-front canyon mouths where streams drop their

Collembola at three alpine subarctic sites resistant to twenty years of experimental warming

Czech Academy of Sciences Publication Activity Database

Alatalo, J.M.; Jägerbrand, A.K.; Čuchta, Peter

2015-01-01

Roč. 5, December (2015), s. 18161 ISSN 2045-2322 Institutional support: RVO:60077344 Keywords : Collembola * alpine subarctic sites * experimental warming Subject RIV: EH - Ecology, Behaviour Impact factor: 5.228, year: 2015

Geologic and hydrologic research at the Western New York Nuclear Service Center, West Valley, New York. Final report, August 1982-December 1983

International Nuclear Information System (INIS)

Albanese, J.R.; Anderson, S.L.; Fakundiny, R.H.; Potter, S.M.; Rogers, W.B.; Whitbeck, L.F.; LaFleur, R.G.; Boothroyd, J.C.; Timson, B.S.

1984-06-01

This report is the last in a series by the New York State Geological Survey on studies funded by the US Nuclear Regulatory Commission. The report covers five important aspects of the geology and hydrology of the Western New York Nuclear Service Center, near West Valley, New York: geomorphology, stratigraphy, sedimentology, surface water, and radionuclide analyses. We reviewed past research on these subjects and present new data obtained in the final phase of NYSGS research at the site. Also presented are up-to-date summaries of the present knowledge of geomorphology and stratigraphy. The report contains a significant bibliography of previous West Valley studies. Appendices include a report on the Fall 1983 Drilling Project and the procedures used, history and prognosis of Cattaraugus Creek and tributaries down cutting, and bar modification and landslide processes of Buttermilk Valley. 100 references, 7 figures, 7 tables

The Tributary Regime in the oil sector

International Nuclear Information System (INIS)

Carta Petrolera

1998-01-01

The tributary regime of the oil sector, is framed by the fiscal crisis that the country, maxim if one keeps in mind the importance of the fiscal revenues originated in the exploitation of these resources in Colombia, so much for the tribute coming from the foreign investment of the sector, like for the utilities generated by ECOPETROL and its impact in the public finances. However in front of this focus, the strategic importance of maintaining the investment in hydrocarbons and the paper that the fiscal politics and the tributary politics for the sector should play in the future and they constitute the government's key pieces

Assessing the link between coastal urbanization and the quality of nekton habitat in mangrove tidal tributaries

Science.gov (United States)

Krebs, Justin M.; Bell, Susan S.; McIvor, Carole C.

2014-01-01

To assess the potential influence of coastal development on habitat quality for estuarine nekton, we characterized body condition and reproduction for common nekton from tidal tributaries classified as undeveloped, industrial, urban or man-made (i.e., mosquito-control ditches). We then evaluated these metrics of nekton performance, along with several abundance-based metrics and community structure from a companion paper (Krebs et al. 2013) to determine which metrics best reflected variation in land-use and in-stream habitat among tributaries. Body condition was not significantly different among undeveloped, industrial, and man-made tidal tributaries for six of nine taxa; however, three of those taxa were in significantly better condition in urban compared to undeveloped tributaries. Palaemonetes shrimp were the only taxon in significantly poorer condition in urban tributaries. For Poecilia latipinna, there was no difference in body condition (length–weight) between undeveloped and urban tributaries, but energetic condition was significantly better in urban tributaries. Reproductive output was reduced for both P. latipinna (i.e., fecundity) and grass shrimp (i.e., very low densities, few ovigerous females) in urban tributaries; however a tradeoff between fecundity and offspring size confounded meaningful interpretation of reproduction among land-use classes for P. latipinna. Reproductive allotment by P. latipinna did not differ significantly among land-use classes. Canonical correspondence analysis differentiated urban and non-urban tributaries based on greater impervious surface, less natural mangrove shoreline, higher frequency of hypoxia and lower, more variable salinities in urban tributaries. These characteristics explained 36 % of the variation in nekton performance, including high densities of poeciliid fishes, greater energetic condition of sailfin mollies, and low densities of several common nekton and economically important taxa from urban tributaries

The scales of variability of stream fish assemblage at tributary confluences

Directory of Open Access Journals (Sweden)

István Czeglédi

2015-12-01

Full Text Available Tributary confluences play an important role in the dispersal of organisms, and consequently, in shaping regional scale diversity in stream networks. Despite their importance in dispersal processes, little is known about how ecological assemblages are organized in these habitats. We studied the scales of variability of stream fish assemblages over three seasons using a hierarchical sampling design, which incorporated three tributaries, three sites at the mouth of each tributary and using four sampling units at each site. We found strong scale dependent variability in species richness, composition and relative abundance. Most of the variation was accounted for by the interactive effect of season, between stream and between site effects, while habitat structure of the sampling units had a relatively minor role. Species richness showed a continuous decrease from the mainstem river in most cases, while species composition and relative abundance changed less consistently along the longitudinal profile. Consequently, we found that not only the junctions presented a strong filter on the species pool, but some species were filtered out if they passed this critical habitat bottleneck. Spatial position of the tributaries along the river also contributed to assemblage variability in the confluences. Overall, our results suggest high variability in fish assemblages across multiple scales at tributary confluences. Environmental management should take a more critical care on the filtering role of tributary confluences in species dispersal, for better understanding patterns and processes in the branches of dendritic stream networks.

Hydrogeology and groundwater quality of the glaciated valleys of Bradford, Tioga, and Potter Counties, Pennsylvania

Science.gov (United States)

Williams, John H.; Taylor, Larry E.; Low, Dennis J.

1998-01-01

The most important sources of groundwater in Bradford, Tioga, and Potter Counties are the stratified-drift aquifers. Saturated sand and gravel primarily of outwash origin forms extensive unconfined aquifers in the valleys. Outwash is underlain in most major valleys by silt, clay, and very fine sand of lacustrine origin that comprise extensive confining units. The lacustrine confining units locally exceed 100 feet in thickness. Confined aquifers of ice-contact sand and gravel are buried locally beneath the lacustrine deposits. Bedrock and till are the basal confining units of the stratifies-drift aquifer systems. Recharge to the stratified-drift aquifers if by direct infiltration of precipitation, tributary-stream infiltration, infiltration of unchanneled runoff at the valley walls, and groundwater inflow from the bedrock and till uplands. Valley areas underlain by superficial sand and gravel contribute about 1 million gallons per day per square mile of water from precipitation to the aquifers. Tributary streams provide recharge of nearly 590 gallons per day per foot of stream reach. Water is added at the rate of 1 million gallons per day per square mile of bordering uplands not drained by tributary streams to the stratified-drift aquifers from unchanneled runoff and groundwater inflow. Induced infiltration can be a major source of recharge to well fields completed in unconfined stratified-drift aquifers that are in good hydraulic connection with surface water. The well fields of an industrial site in North Towanda, a public-water supplier at Tioga Point, and the U.S. Fish and Wildlife Service at Asaph accounted for 75 percent of the 10.8 million gallons per day pf groundwater withdrawn by public suppliers and other selected users in 1985. The well fields tap stratified-drift aquifers that are substantially recharged by induced infiltration or tributary-stream infiltration. Specific-capacity data from 95 wells indicate that most wells completed in stratified

Water Quality in Tortum Stream and its Tributaries (Erzurum/Turkey

Directory of Open Access Journals (Sweden)

Mine KÖKTÜRK

2015-04-01

Full Text Available This study was undertaken with the aim of determining the effects of domestic waste and hydroelectric dams on water quality in the Tortum Stream and its tributaries. Water samples were taken monthly from nine sampling points of Tortum Stream and its tributaries between July 2012 and May 2013. Analyzed for temperature (°C, pH, dissolved oxygen (DO, total suspended solids (TSS, alkalinity, Ca, total hardness, sulfate (SO4, ammonia-nitrogen (N-NH3−, nitrite-nitrogen (N-NO2− and nitrate nitrogen (N-NO3− as well as total phosphorus (TP, total orthophosphate (TO, total iron and silica (SiO2 were carried out. Physical and chemical characteristics of Tortum Stream and its tributaries which were examined according to the Water Framework Directive and the Water Pollution Control Regulations. It can be said that the stream has a low water quality standard except for water temperature, dissolved oxygen and sulfate. The results showed that Tortum Stream and tributaries are under threat because of domestic waste, fertilizers and hydroelectric constructions.

[BIODIVERSITY OF ACANTHOCEPHALANS (ACANTHOCEPHALA) IN FRESHWATER FISHES OF ASIATIC SUB-ARCTIC REGION].

Science.gov (United States)

Atrashkevich, G I; Mikhailova, E I; Orlovskaya, O M; Pospekhov, V V

2016-01-01

The analysis of taxonomical and ecological diversity of acanthocephalans in fishes of Asiatic sub-Arctic region freshwaters, summarizing changes in modern views on species composition, life cycles, and ecology of background groups of these parasites is given. A priority role of studies provided by O. N. Bauer and his scientific school in organization and development of these aspects of acanthocephalology is demonstrated. Special attention is paid to the assessment of acanthocephalan biodiversity of the genus Neoechinorhynchus, the background group of freshwater fish parasites of the Asiatic sub-Arctic region, and an original key for their species is given. The distribution of acanthocephalans of the genus Acanthocephalus in northeastern Asia is analyzed and prospective study of this parasite group, evolutionary associated with freshwater isopods of the genus Asellus as intermediate hosts, is outlined. The absence of documented evidences on intermediate hosts of other background parasites of freshwater fishes in the region, acanthocephalans of the genus Metechinorhynchus, is revealed. It is assumed that subsequent taxonomic revisions based both on morphological and molecular genetic studies are necessary for the reliable revealing of species composition in each genus of the background acanthocephalans from freshwater fishes of Northern Asia. Theoretical significance of the study of acanthocephalan life cycles and revealing their natural intermediate hosts for the reliable estimation of structural and functional organization of their host-parasite systems in different parts of the range is substantiated and the possibility of the distribution of taxonomic conclusions in new territories is analyzed. A brief annotated taxonomical list of freshwater acanthocephalans of the Asiatic sub-Arctic region is given.

Responses of non-methane biogenic volatile organic compound emissions to climate change in boreal and subarctic ecosystems

Energy Technology Data Exchange (ETDEWEB)

Faubert, P.

2010-07-01

Non-methane biogenic volatile organic compound emissions (BVOCs) have important roles in the global atmospheric chemistry but their feedbacks to climate change are still unknown. This thesis reports one of the first estimates of BVOC emissions from boreal and subarctic ecosystems. Most importantly, this thesis assesses the BVOC emission responses to four effects of climate change in these ecosystems: (1) the direct effect of warming, and its indirect effects via (2) water table drawdown, (3) change in the vegetation composition, and (4) enhanced UV-B radiation. BVOC emissions were measured using a conventional chamber method in which the compounds were collected on adsorbent and later analyzed by gas chromatography-mass spectrometry. On a subarctic heath, warming by only 1.9-2.5 degC doubled the monoterpene and sesquiterpene emissions. Such a high increase of BVOC emissions under a conservative warming cannot be predicted by the current models, which underlines the importance of a focus on BVOC emissions from the Subarctic under climate change. On a subarctic peatland, enhanced UV-B did not affect the BVOC emissions but the water table level exerted the major effect. The water table drawdown experimentally applied on boreal peatland microcosms decreased the emissions of monoterpenes and other VOCs (BVOCs with a lifetime>1 d) for the hollows (wet microsites) and that of all BVOC groups for the lawns (moderately wet microsites). The warming treatment applied on the lawn microcosms decreased the isoprene emission. The removal of vascular plants in the hummock (dry microsites) microcosms decreased the emissions of monoterpenes while the emissions between the microcosms covered with Sphagnum moss and bare peat were not different. In conclusion, the results presented in this thesis indicate that climate change has complex effects on the BVOC emissions. These results make a significant contribution to improving the modeling of BVOC emissions for a better understanding of

Flow Patterns in an Open Channel Confluence with Increasingly Dominant Tributary Inflow

Directory of Open Access Journals (Sweden)

Laurent Schindfessel

2015-08-01

Full Text Available Despite the ratio of incoming discharges being recognized as a key parameter in open-channel confluence hydrodynamics, little is known about the flow patterns when the tributary provides more than 90% of the total discharge. This paper offers a systematic study of flow features when the tributary becomes increasingly dominant in a 90° confluence with a fixed concordant bed. Large-eddy simulations are used to investigate the three-dimensional complex flow patterns for three different discharge ratios. It is found that the tributary flow impinges on the opposing bank when the tributary flow becomes sufficiently dominant, causing a recirculating eddy in the upstream channel of the confluence, which induces significant changes in the incoming velocity distribution. Moreover, it results in stronger helicoidal cells in the downstream channel, along with zones of upwelling flow. In turn, the changed flow patterns also influence the mixing layer and the flow recovery. Finally, intermittent events of stronger upwelling flow are discerned. Improved understanding of flow patterns at confluences where the tributary is dominant is applicable to both engineering and earth sciences.

Hydromorphodynamic effects of the width ratio and local tributary widening on discordant confluences

Science.gov (United States)

Guillén-Ludeña, S.; Franca, M. J.; Alegria, F.; Schleiss, A. J.; Cardoso, A. H.

2017-09-01

River training works performed in the last couple of centuries constrained the natural dynamics of channel networks in locations that include the confluences between tributaries and main channels. As a result, the dynamics of these confluences are currently characterized by homogeneous flow depths, flow velocities, and morphologic conditions, which are associated with impoverished ecosystems. The widening of river reaches is seen as a useful measure for river restoration, as it enhances the heterogeneity in flow depths, flow velocities, sediment transport, and bed substrates. The purpose of this study is to analyze the effects of local widening of the tributary mouth as well as the effects of the ratio between the width of the tributary and that of the main channel on the flow dynamics and bed morphology of river confluences. For that purpose, 12 experiments were conducted in a 70° laboratory confluence. In these experiments, three unit-discharge ratios were tested (qr = 0.37, 0.50, and 0.77) with two width ratios and two tributary configurations. The unit-discharge ratio is defined as the unit discharge in the tributary divided by that of the main channel, measured upstream of the confluence. The width ratio, which is defined as the width of the tributary divided by that of the main channel, was modified by changing the width of the main channel from 0.50 to 1.00 m (corresponding to Br = 0.30 and 0.15 respectively). The tributary configurations consisted of (i) a straight reach with a constant width (the so-called reference configuration) and (ii) a straight reach with a local widening at the downstream end (the so-called widened configuration). During the experiments, a uniform sediment mixture was continuously supplied to both channels. This experimental setup is novel among existing experimental studies on confluence dynamics, as it addresses new confluence configurations and includes a continuous sediment supply to both channels. The experiments were run

Tillage and straw management affect PM10 emission potential in subarctic Alaska

Science.gov (United States)

Emission of PM10 (particulates =10 um in diameter regulated by many nations as an air pollutant) from agricultural soils can impact regional air quality. Little information exists that describes the potential for PM10 and airborne dust emissions from subarctic soils or agricultural soils subject to ...

Enzymology under global change: organic nitrogen turnover in alpine and sub-Arctic soils

NARCIS (Netherlands)

Weedon, J.T.; Aerts, R.; Kowalchuk, G.A.; van Bodegom, P.M.

2011-01-01

Understanding global change impacts on the globally important carbon storage in alpine, Arctic and sub-Arctic soils requires knowledge of the mechanisms underlying the balance between plant primary productivity and decomposition. Given that nitrogen availability limits both processes, understanding

Enzymology under global change: organic nitrogen turnover in alpine and sub-Arctic soils.

NARCIS (Netherlands)

Weedon, J.T.; Aerts, R.; Kowalchuk, G.A.; van Bodegom, P.M.

2011-01-01

Understanding global change impacts on the globally important carbon storage in alpine, Arctic and sub-Arctic soils requires knowledge of the mechanisms underlying the balance between plant primary productivity and decomposition. Given that nitrogen availability limits both processes, understanding

Youth Environmental Science Outreach in the Mushkegowuk Territory of Subarctic Ontario, Canada

Science.gov (United States)

Karagatzides, Jim D.; Kozlovic, Daniel R.; De Iuliis, Gerry; Liberda, Eric N.; General, Zachariah; Liedtke, Jeff; McCarthy, Daniel D.; Gomez, Natalya; Metatawabin, Daniel; Tsuji, Leonard J. S.

2011-01-01

We connected youth of the Mushkegowuk Territory (specifically Fort Albany First Nation) with environmental science and technology mentors in an outreach program contextualized to subarctic Ontario that addressed some of the environmental concerns identified by members of Fort Albany First Nation. Most activities were community-based centering on…

Three-spined stickleback Gasterosteus aculeatus, as a possible paratenic host for salmonid nematodes in a subarctic lake.

Science.gov (United States)

Braicovich, Paola E; Kuhn, Jesper A; Amundsen, Per-Arne; Marcogliese, David J

2016-03-01

In Takvatn, a subarctic lake in northern Norway, 35 of 162 three-spined sticklebacks examined were infected with 106 specimens of third-stage larvae of Philonema oncorhynchi. The prevalence and mean intensity of P. oncorhynchi were 10 % and 2.0 in 2013 and 24 % and 3.0 in 2014, respectively. A single specimen of Cystidicola farionis was found in an additional sample. While the latter is considered an accidental infection, three-spined sticklebacks may function as paratenic hosts of P. oncorhynchi, potentially enhancing its transmission to salmonids due to their central role in the lacustrine food web of this subarctic lake.

33 CFR 334.460 - Cooper River and tributaries at Charleston, SC.

Science.gov (United States)

2010-07-01

... 33 Navigation and Navigable Waters 3 2010-07-01 2010-07-01 false Cooper River and tributaries at... ARMY, DEPARTMENT OF DEFENSE DANGER ZONE AND RESTRICTED AREA REGULATIONS § 334.460 Cooper River and tributaries at Charleston, SC. (a) The areas: (1) That portion of the Cooper River beginning on the west shore...

Quantifying dust input to the Subarctic North Pacific - Results from surface sediments and sea water thorium isotope measurements

Science.gov (United States)

Winckler, G.; Serno, S.; Hayes, C.; Anderson, R. F.; Gersonde, R.; Haug, G. H.

2012-12-01

The Subarctic North Pacific is one of the three primary high-nutrient-low chlorophyll regions of the modern ocean, where the biological pump is relatively inefficient at transferring carbon from the atmosphere to the deep sea. The system is thought to be iron-limited. Aeolian dust is a significant source of iron and other nutrients that are essential for the health of marine ecosystems and potentially a controlling factor of the high-nutrient-low chlorophyll status of the Subarctic North Pacific. However, constraining the size of the dust flux to the surface ocean remains difficult. Here we apply two different approaches, based on surface sediment and water column samples, respectively, obtained during the SO202/INOPEX research cruise to the Subarctic North Pacific in 2009. We map the spatial patterns of Th/U isotopes, helium isotopes and rare earth elements across surface sediments from 37 multi-core core-top sediments across the Subarctic North Pacific. In order to deconvolve the detrital endmembers in regions of the North Pacific affected by volcanic material, IRD and hemipelagic input, we use a combination of trace elements with distinct characteristics in the different endmembers. This approach allows us to calculate the relative aeolian fraction, and in combination with Thorium230-normalized mass flux data, to quantify the dust supply. Secondly, we present an innovative approach to use paired Thorium-232 and Thorium-230 concentrations of upper-ocean seawater at 7 stations along the INOPEX track. Thorium-232 in the upper water column is dominantly derived from dissolution of aeolian dust, whereas Thorium-230 data provide a measure of the thorium removal from the surface waters and, thus, allow us to derive Thorium-232 fluxes. Combined with a mean Thorium-232 concentration in dust and estimate of the thorium solubility, the Thorium-232 flux can be translated in a dust flux to the surface ocean. Dust flux estimates for the Subarctic North Pacific will be

Xenoestrogens in the River Elbe and its tributaries

International Nuclear Information System (INIS)

Stachel, Burkhard; Ehrhorn, Ute; Heemken, Olaf-Peter; Lepom, Peter; Reincke, Heinrich; Sawal, Georg; Theobald, Norbert

2003-01-01

High concentrations of organic chemicals in the River Elbe may be detrimental to aquatic organisms. - 4-Alkylphenols, 4-alkylphenol ethoxylates, 4-alkylphenoxy carboxylates, bisphenol A, bisphenol F, 4-hydroxyacetophenon, 4-hydroxybenzoic acid and steroid hormones were analyzed in water samples of the River Elbe and its tributaries Schwarze Elster, Mulde, Saale, Havel and Schwinge. Additionally, freshly deposited sediments (FDS, composite samples) of the River Elbe and its tributaries were analyzed. The concentrations in water samples ranged from (in ng/l): bisphenol A 4 to 92, branched nonylphenol 13 to 87, branched nonylphenol ethoxylates <0.5 to 120, 4-tert. nonylphenoxy carboxylates <10 to 940 and 4-hydroxybenzoic acid 4 to 12. Steroid hormones were only detected in the Czech tributaries Jizera and Vltava in concentrations near the limit of quantification. In FDS samples the concentrations amounted to (in μg/kg d.w.): bisphenol A 10-380, branched nonylphenol 27-430, branched nonylphenol ethoxylates 24-3700, nonylphenoxy carboxylates <50 and 4-hydroxybenzoic acid 23-4400. Increased bisphenol A concentrations were found in water and FDS samples taken from the Czech-German border at Schmilka and the mouth of the Schwinge (only water sample). According to studies conducted in the Elbe Estuary and the German Bight, the River Elbe must be considered as a major source of pollution for the North Sea in respect of the compounds analyzed. A comparison of bisphenol A concentrations, 4-alkylphenols and the corresponding ethoxylates analyzed in the River Elbe and its tributaries with those found in other German surface waters indicated a low level of contamination. The evaluation of the data based on LOEC-values indicated that the concentrations were well below the effectivity threshold for some 4-alkylphenols. According to recent ecotoxicological investigations, for example, with prosobranch snails, bisphenol A concentrations found in water samples of the River Elbe and

Carbon monoxide and methane in the North American Arctic and Subarctic troposphere - July-August 1988

Science.gov (United States)

Harriss, Robert C.; Sachse, Glen W.; Hill, Gerald F.; Wade, Larry; Bartlett, Karen B.; Collins, James E.; Steele, L. P.; Novelli, Paul C.

1992-01-01

Enhanced concentrations of CH4 in the unpolluted atmospheric mixed layer over both Arctic and subarctic tundra landscapes are documented here using data from the NASA Arctic Boundary Layer Expedition (ABLE 3A). The CH4 concentration gradients were determined mainly by interactions of biogenic emission from wet tundra and turbulent mixing proceses. The gradient were most frequently associated with intrusion of upper tropospheric or stratospheric air into the midtroposphere, emissions from forest and tundra fires, and long-range transport of enhanced concentration of these gases from unidentified sources. Summertime haze layers exhibited midtropospheric enhancements of CH4 similar to those measured in winter Arctic events. The observations confirm the importance of Arctic and Subarctic wetland environments as a regional source of global atmospheric CH4.

Recent changes in aquatic biota in subarctic Fennoscandia - the role of global and local environmental variables

Science.gov (United States)

Weckström, Jan; Leppänen, Jaakko; Sorvari, Sanna; Kaukolehto, Marjut; Weckström, Kaarina; Korhola, Atte

2013-04-01

The Arctic, representing a fifth of the earth's surface, is highly sensitive to the predicted future warming and it has indeed been warming up faster than most other regions. This makes the region critically important and highlights the need to investigate the earliest signals of global warming and its impacts on the arctic and subarctic aquatic ecosystems and their biota. It has been demonstrated that many Arctic freshwater ecosystems have already experienced dramatic and unpreceded regime shifts during the last ca. 150 years, primarily driven by climate warming. However, despite the indisputable impact of climate-related variables on freshwater ecosystems other, especially local-scale catchment related variables (e.g. geology, vegetation, human activities) may override the climate signal and become the primary factor in shaping the structure of aquatic ecosystems. Although many studies have contributed to an improved understanding of limnological and hydrobiological features of Artic and subarctic lakes, much information is still needed especially on the interaction between the biotic and abiotic components, i.e. on factors controlling the food web dynamics in these sensitive aquatic ecosystems. This is of special importance as these lakes are of great value in water storage, flood prevention, and maintenance of biodiversity, in addition to which they are vital resources for settlement patterns, food production, recreation, and tourism. In this study we compare the pre-industrial sediment assemblages of primary producers (diatoms and Pediastrum) and primary consumers (cladoceran and chironomids) with their modern assemblages (a top-bottom approach) from 50 subarctic Fennoscandian lakes. We will evaluate the recent regional pattern of changes in aquatic assemblages, and assess how coherent the lakes' responses are across the subarctic area. Moreover, the impact of global (e.g. climate, precipitation) and local (e.g. lake and its catchment characteristics) scale

Allochthonous Carbon--a Major Driver of Bacterioplankton Production in the Subarctic Northern Baltic Sea.

Science.gov (United States)

Figueroa, D; Rowe, O F; Paczkowska, J; Legrand, C; Andersson, A

2016-05-01

Heterotrophic bacteria are, in many aquatic systems, reliant on autochthonous organic carbon as their energy source. One exception is low-productive humic lakes, where allochthonous dissolved organic matter (ADOM) is the major driver. We hypothesized that bacterial production (BP) is similarly regulated in subarctic estuaries that receive large amounts of riverine material. BP and potential explanatory factors were measured during May-August 2011 in the subarctic Råne Estuary, northern Sweden. The highest BP was observed in spring, concomitant with the spring river-flush and the lowest rates occurred during summer when primary production (PP) peaked. PLS correlations showed that ∼60% of the BP variation was explained by different ADOM components, measured as humic substances, dissolved organic carbon (DOC) and coloured dissolved organic matter (CDOM). On average, BP was threefold higher than PP. The bioavailability of allochthonous dissolved organic carbon (ADOC) exhibited large spatial and temporal variation; however, the average value was low, ∼2%. Bioassay analysis showed that BP in the near-shore area was potentially carbon limited early in the season, while BP at seaward stations was more commonly limited by nitrogen-phosphorus. Nevertheless, the bioassay indicated that ADOC could contribute significantly to the in situ BP, ∼60%. We conclude that ADOM is a regulator of BP in the studied estuary. Thus, projected climate-induced increases in river discharge suggest that BP will increase in subarctic coastal areas during the coming century.

Impacts of Climate Change Induced Vegetation Responses on BVOC Emissions from Subarctic Heath Ecosystems

DEFF Research Database (Denmark)

Valolahti, Hanna Maritta

The role of biogenic volatile organic compounds (BVOCs) affecting Earths’ climate system is one of the greatest uncertainties when modelling the global climate change. BVOCs presence in the atmosphere can have both positive and negative climate feedback mechanisms when they involve atmospheric...... chemistry and physics. Vegetation is the main source of BVOCs. Their production is directly linked to temperature and the foliar biomass. On global scale, vegetation in subarctic and arctic regions has been modeled to have only minor contribution to annual total BVOC emissions. In these regions cold...... temperature has been regulating annual plant biomass production, but ongoing global warming is more pronounced in these regions than what the global average is. This may increase the importance of subarctic and arctic vegetation as a source of BVOC emissions in near future. This thesis aims to increase...

Export production in the subarctic North Pacific over the last 800 kyrs: No evidence for iron fertilization?

Science.gov (United States)

Kienast, S.S.; Hendy, I.L.; Crusius, J.; Pedersen, Thomas F.; Calvert, S.E.

2004-01-01

The subarctic North Pacific is a high nitrate-low chlorophyll (HNLC) region, where phytoplankton growth rates, especially those of diatoms, are enhanced when micro-nutrient Fe is added. Accordingly, it has been suggested that glacial Fe-laden dust might have increased primary production in this region. This paper reviews published palaeoceanographic records of export production over the last 800 kyrs from the open North Pacific (north of ???35??N). We find different patterns of export production change over time in the various domains of the North Pacific (NW and NE subarctic gyres, the marginal seas and the transition zone). However, there is no compelling evidence for an overall increase in productivity during glacials in the subarctic region, challenging the paradigm that dust-born Fe fertilization of this region has contributed to the glacial draw down of atmospheric CO2. Potential reasons for the lack of increased glacial export production include the possibility that Fe-fertilization rapidly drives the ecosystem towards limitation by another nutrient. This effect would have been exacerbated by an even more stable mixed layer compared to today. ?? The Oceanographic Society of Japan.

Changing times, changing stories: Generational differences in climate change perspectives from four remote indigenous communities in Subarctic Alaska

Science.gov (United States)

Herman-Mercer, Nicole M.; Matkin, Elli; Laituri, Melinda J.; Toohey, Ryan C; Massey, Maggie; Elder, Kelly; Schuster, Paul F.; Mutter, Edda A.

2016-01-01

Indigenous Arctic and Subarctic communities currently are facing a myriad of social and environmental changes. In response to these changes, studies concerning indigenous knowledge (IK) and climate change vulnerability, resiliency, and adaptation have increased dramatically in recent years. Risks to lives and livelihoods are often the focus of adaptation research; however, the cultural dimensions of climate change are equally important because cultural dimensions inform perceptions of risk. Furthermore, many Arctic and Subarctic IK climate change studies document observations of change and knowledge of the elders and older generations in a community, but few include the perspectives of the younger population. These observations by elders and older generations form a historical baseline record of weather and climate observations in these regions. However, many indigenous Arctic and Subarctic communities are composed of primarily younger residents. We focused on the differences in the cultural dimensions of climate change found between young adults and elders. We outlined the findings from interviews conducted in four indigenous communities in Subarctic Alaska. The findings revealed that (1) intergenerational observations of change were common among interview participants in all four communities, (2) older generations observed more overall change than younger generations interviewed by us, and (3) how change was perceived varied between generations. We defined “observations” as the specific examples of environmental and weather change that were described, whereas “perceptions” referred to the manner in which these observations of change were understood and contextualized by the interview participants. Understanding the differences in generational observations and perceptions of change are key issues in the development of climate change adaptation strategies.

Hillslope failure and paraglacial reworking of sediments in response to glacier retreat, Fox Valley, New Zealand.

Science.gov (United States)

McColl, Samuel T.; Fuller, Ian C.; Anderson, Brian; Tate, Rosie

2017-04-01

Climate and glacier fluctuations influence sediment supply to glacier forelands, which in turn influences down-valley hazards to infrastructure and tourism within glacier forelands. At Fox Glacier, one of New Zealand's most iconic and popular glaciers, rapid retreat has initiated a range of hillslope and valley floor responses, that present a cascade of hazards and changes that need to be carefully managed. Fox Glacier has retreated many kilometres historically, with 2.6 km of retreat since the mid-20th century, and a phase of rapid retreat of 50-340 m per year since 2009. To study the system response to past and ongoing glacial retreat at the Fox valley, morphological changes are being observed using time-lapse photography and the annual collection of high-resolution digital elevation models (DEMs) and orthophoto mosaics. The DEMs are being produced using Structure from Motion photogrammetry from UAV/RPAS and helicopter platforms, and are being used, along with manual ground surveying, to produce ground surface change models (DoDs; DEMs of Difference) and sediment budgets for the valley. Results from time-lapse photography and DoDs show that glacial retreat has initiated destabilisation and (mostly chronic) mass movement of surficial glacial sediments on the valley slopes near the glacier terminus. Alluvial fans farther down valley are actively growing, reworking glacial and landslide sediments from tributary catchments. These paraglacial sediments being delivered to the proglacial river from the glacier terminus and alluvial fans are driving aggradation of the valley floor of decimetres to metres per year and maintaining a highly dynamic braid plain. Valley floor changes also include the melting of buried dead ice, which are causing localised subsidence at the carpark and one of the alluvial fans. The unstable slopes and active debris fans, aggrading and highly active river channel, ground subsidence, add to the spectacle but also the hazards of the Fox valley

Nekton community structure varies in response to coastal urbanization near mangrove tidal tributaries

Science.gov (United States)

Krebs, Justin M.; McIvor, Carole C.; Bell, Susan S.

2014-01-01

To assess the potential influence of coastal development on estuarine-habitat quality, we characterized land use and the intensity of land development surrounding small tidal tributaries in Tampa Bay. Based on this characterization, we classified tributaries as undeveloped, industrial, urban, or man-made (i.e., mosquito-control ditches). Over one third (37 %) of the tributaries have been heavily developed based on landscape development intensity (LDI) index values >5.0, while fewer than one third (28 %) remain relatively undeveloped (LDI < 3.0). We then examined the nekton community from 11 tributaries in watersheds representing the four defined land-use classes. Whereas mean nekton density was independent of land use, species richness and nekton-community structure were significantly different between urban and non-urban (i.e., undeveloped, industrial, man-made) tributaries. In urban creeks, the community was species-poor and dominated by high densities of poeciliid fishes, Poecilia latipinna and Gambusia holbrooki, while typically dominant estuarine taxa including Menidia spp., Fundulus grandis, and Adinia xenica were in low abundance and palaemonid grass shrimp were nearly absent. Densities of economically important taxa in urban creeks were only half that observed in five of the six undeveloped or industrial creeks, but were similar to those observed in mosquito ditches suggesting that habitat quality in urban and mosquito-ditch tributaries is suboptimal compared to undeveloped tidal creeks. Furthermore, five of nine common taxa were rarely collected in urban creeks. Our results suggest that urban development in coastal areas has the potential to alter the quality of habitat for nekton in small tidal tributaries as reflected by variation in the nekton community.

Providing an Authentic Research Experience for University of the Fraser Valley Undergraduate Students by Investigating and Documenting Seasonal and Longterm Changes in Fraser Valley Stream Water Chemistry.

Science.gov (United States)

Gillies, S. L.; Marsh, S. J.; Peucker-Ehrenbrink, B.; Janmaat, A.; Bourdages, M.; Paulson, D.; Groeneweg, A.; Bogaerts, P.; Robertson, K.; Clemence, E.; Smith, S.; Yakemchuk, A.; Faber, A.

2017-12-01

Undergraduate students in the Geography and Biology Departments at the University of the Fraser Valley (UFV) have been provided the opportunity to participate in the time series sampling of the Fraser River at Fort Langley and Fraser Valley tributaries as part of the Global Rivers Observatory (GRO, www.globalrivers.org) which is coordinated by Woods Hole Oceanographic Institution and Woods Hole Research Center. Student research has focussed on Clayburn, Willband and Stoney Creeks that flow from Sumas Mountain northwards to the Fraser River. These watercourses are increasingly being impacted by anthropogenic activity including residential developments, industrial activity, and agricultural landuse. Students are instructed in field sampling protocols and the collection of water chemistry data and the care and maintenance of the field equipment. Students develop their own research projects and work in support of each other as teams in the field to collect the data and water samples. Students present their findings as research posters at local academic conferences and at UFV's Student Research Day. Through their involvement in our field research our students have become more aware of the state of our local streams, the methods used to monitor water chemistry and how water chemistry varies seasonally.

Tolerance of an expanding subarctic shrub, Betula glandulosa, to simulated caribou browsing.

Directory of Open Access Journals (Sweden)

Emilie Champagne

Full Text Available Densification of the shrub layer has been reported in many subarctic regions, raising questions about the implication for large herbivores and their resources. Shrubs can tolerate browsing and their level of tolerance could be affected by browsing and soils productivity, eventually modifying resource availability for the caribou. Our objective was to assess the compensatory growth potential of a subarctic shrub, Betula glandulosa Michx., in relation with caribou browsing and nutriment availability for the plants. We used a simulated browsing (0, 25 and 75% of available shoots and nitrogen-fertilisation (0 and 10 g m(-2 experiment to test two main hypotheses linking tolerance to resource availability, the Compensatory Continuum Hypothesis and the Growth Rate Hypothesis as well as the predictions from the Limiting Resource Model. We seek to explicitly integrate the relative browsing pressure in our predictions since the amount of tissues removed could affect the capacity of long-lived plants to compensate. Birches fully compensated for moderate browsing with an overall leaf biomass similar to unbrowsed birches but undercompensated under heavy browsing pressure. The main mechanism explaining compensation appears to be the conversion of short shoots into long shoots. The leaf area increased under heavy browsing pressure but only led to undercompensation. Fertilisation for two consecutive years did not influence the response of birch, thus we conclude that our results support the LRM hypothesis of equal tolerance under both high and low nitrogen availability. Our results highlight that the potential for compensatory growth in dwarf birch is surpassed under heavy browsing pressure independently of the fertilisation regime. In the context of the worldwide decline in caribou herds, the reduction in browsing pressure could act synergistically with global climate change to promote the current shrub expansion reported in subarctic regions.

Association of climatic factors with infectious diseases in the Arctic and subarctic region--a systematic review.

Science.gov (United States)

Hedlund, Christina; Blomstedt, Yulia; Schumann, Barbara

2014-01-01

The Arctic and subarctic area are likely to be highly affected by climate change, with possible impacts on human health due to effects on food security and infectious diseases. To investigate the evidence for an association between climatic factors and infectious diseases, and to identify the most climate-sensitive diseases and vulnerable populations in the Arctic and subarctic region. A systematic review was conducted. A search was made in PubMed, with the last update in May 2013. Inclusion criteria included human cases of infectious disease as outcome, climate or weather factor as exposure, and Arctic or subarctic areas as study origin. Narrative reviews, case reports, and projection studies were excluded. Abstracts and selected full texts were read and evaluated by two independent readers. A data collection sheet and an adjusted version of the SIGN methodology checklist were used to assess the quality grade of each article. In total, 1953 abstracts were initially found, of which finally 29 articles were included. Almost half of the studies were carried out in Canada (n=14), the rest from Sweden (n=6), Finland (n=4), Norway (n=2), Russia (n=2), and Alaska, US (n=1). Articles were analyzed by disease group: food- and waterborne diseases, vector-borne diseases, airborne viral- and airborne bacterial diseases. Strong evidence was found in our review for an association between climatic factors and food- and waterborne diseases. The scientific evidence for a link between climate and specific vector- and rodent-borne diseases was weak due to that only a few diseases being addressed in more than one publication, although several articles were of very high quality. Air temperature and humidity seem to be important climatic factors to investigate further for viral- and bacterial airborne diseases, but from our results no conclusion about a causal relationship could be drawn. More studies of high quality are needed to investigate the adverse health impacts of weather and

Carbon monoxide and methane in the North American Arctic and Subarctic troposphere - July-August 1988

Energy Technology Data Exchange (ETDEWEB)

Harriss, R.C.; Sachse, G.W.; Hill, G.F.; Wade, L.; Bartlett, K.B.; Collins, J.E.; Steele, L.P.; Novelli, P.C. (New Hampshire Univ., Durham (United States) NASA, Langley Research Center, Hampton, VA (United States) Lockheed Engineering Sciences Co., Hampton, VA (United States) Science and Technology Corp., Hampton, VA (United States) Cooperative Inst. for Research in Environmental Sciences, Boulder, CO (United States))

1992-10-01

Enhanced concentrations of CH4 in the unpolluted atmospheric mixed layer over both Arctic and subarctic tundra landscapes are documented here using data from the NASA Arctic Boundary Layer Expedition (ABLE 3A). The CH4 concentration gradients were determined mainly by interactions of biogenic emission from wet tundra and turbulent mixing proceses. The gradient were most frequently associated with intrusion of upper tropospheric or stratospheric air into the midtroposphere, emissions from forest and tundra fires, and long-range transport of enhanced concentration of these gases from unidentified sources. Summertime haze layers exhibited midtropospheric enhancements of CH4 similar to those measured in winter Arctic events. The observations confirm the importance of Arctic and Subarctic wetland environments as a regional source of global atmospheric CH4. 33 refs.

Intensive land use in the Swedish mountains between AD 800 and 1200 led to deforestation and ecosystem transformation with long-lasting effects.

Science.gov (United States)

Östlund, Lars; Hörnberg, Greger; DeLuca, Thomas H; Liedgren, Lars; Wikström, Peder; Zackrisson, Olle; Josefsson, Torbjörn

2015-10-01

Anthropogenic deforestation has shaped ecosystems worldwide. In subarctic ecosystems, primarily inhabited by native peoples, deforestation is generally considered to be mainly associated with the industrial period. Here we examined mechanisms underlying deforestation a thousand years ago in a high-mountain valley with settlement artifacts located in subarctic Scandinavia. Using the Heureka Forestry Decision Support System, we modeled pre-settlement conditions and effects of tree cutting on forest cover. To examine lack of regeneration and present nutrient status, we analyzed soil nitrogen. We found that tree cutting could have deforested the valley within some hundred years. Overexploitation left the soil depleted beyond the capacity of re-establishment of trees. We suggest that pre-historical deforestation has occurred also in subarctic ecosystems and that ecosystem boundaries were especially vulnerable to this process. This study improves our understanding of mechanisms behind human-induced ecosystem transformations and tree-line changes, and of the concept of wilderness in the Scandinavian mountain range.

Population dynamics and life history strategies of the dominant copepods in a sub-arctic Greenlandic fjord

DEFF Research Database (Denmark)

Kjellerup, Sanne; Nielsen, Torkel Gissel

Investigations of the Arctic and Sub-Arctic pelagic food web have previously focused on the copepod genus Calanus, as they often dominate the mesozooplankton community and serve as a lipid rich food source for higher trophic levels. However, if night samples are considered a different food web...... might emerges with the omnivorous copepod Metridia spp. in a major role. Biology of Metridia is practically unknown but deviates from Calanus e.g. Metridia does not hibernate but stays active yearlong benefiting from being omnivore. In the present study abundance, depth distribution, and egg and pellet...... hibernating Calanus. M. longa might thereby also have a central role in the lipid rich food chain which is a distinct feature for Arctic and Sub-Arctic ecosystems...

Year-round presence of neonicotinoid insecticides in tributaries to the Great Lakes, USA

Science.gov (United States)

To better understand the transport of neonicotinoid insecticides to a sensitive freshwater ecosystem, monthly samples (October 2015-September 2016) were collected from 10 major tributaries to the Great Lakes, USA. For the monthly tributary samples, neonicotinoids were detected in...

Hydrology of two slopes in subarctic Yukon, Canada

Science.gov (United States)

Carey, Sean K.; Woo, Ming-Ko

1999-11-01

Two subarctic forested slopes in central Wolf Creek basin, Yukon, were studied in 1996-1997 to determine the seasonal pattern of the hydrologic processes. A south-facing slope has a dense aspen forest on silty soils with seasonal frost only and a north-facing slope has open stands of black spruce and an organic layer on top of clay sediments with permafrost. Snowmelt is advanced by approximately one month on the south-facing slope due to greater radiation receipt. Meltwater infiltrates its seasonally frozen soil with low ice content, recharging the soil moisture reservoir but yielding no lateral surface or subsurface flow. Summer evaporation depletes this recharged moisture and any additional rainfall input, at the expense of surface or subsurface flow. The north-facing slope with an ice rich substrate hinders deep percolation. Snow meltwater is impounded within the organic layer to produce surface runoff in rills and gullies, and subsurface flow along pipes and within the matrix of the organic soil. During the summer, most subsurface flows are confined to the organic layer which has hydraulic conductivities orders of magnitudes larger than the underlying boulder-clay. Evaporation on the north-facing slope declines as both the frost table and the water table descend in the summer. A water balance of the two slopes demonstrates that vertical processes of infiltration and evaporation dominate moisture exchanges on the south-facing slope, whereas the retardation of deep drainage by frost and by clayey soil on the permafrost slope promotes a strong lateral flow component, principally within the organic layer. These results have the important implication that permafrost slopes and organic horizons are the principal controls on streamflow generation in subarctic catchments.

Climate change-induced vegetation change as a driver of increased subarctic biogenic volatile organic compound emissions.

Science.gov (United States)

Valolahti, Hanna; Kivimäenpää, Minna; Faubert, Patrick; Michelsen, Anders; Rinnan, Riikka

2015-09-01

Emissions of biogenic volatile organic compounds (BVOCs) have been earlier shown to be highly temperature sensitive in subarctic ecosystems. As these ecosystems experience rapidly advancing pronounced climate warming, we aimed to investigate how warming affects the BVOC emissions in the long term (up to 13 treatment years). We also aimed to assess whether the increased litterfall resulting from the vegetation changes in the warming subarctic would affect the emissions. The study was conducted in a field experiment with factorial open-top chamber warming and annual litter addition treatments on subarctic heath in Abisko, northern Sweden. After 11 and 13 treatment years, BVOCs were sampled from plant communities in the experimental plots using a push-pull enclosure technique and collection into adsorbent cartridges during the growing season and analyzed with gas chromatography-mass spectrometry. Plant species coverage in the plots was analyzed by the point intercept method. Warming by 2 °C caused a 2-fold increase in monoterpene and 5-fold increase in sesquiterpene emissions, averaged over all measurements. When the momentary effect of temperature was diminished by standardization of emissions to a fixed temperature, warming still had a significant effect suggesting that emissions were also indirectly increased. This indirect increase appeared to result from increased plant coverage and changes in vegetation composition. The litter addition treatment also caused significant increases in the emission rates of some BVOC groups, especially when combined with warming. The combined treatment had both the largest vegetation changes and the highest BVOC emissions. The increased emissions under litter addition were probably a result of a changed vegetation composition due to alleviated nutrient limitation and stimulated microbial production of BVOCs. We suggest that the changes in the subarctic vegetation composition induced by climate warming will be the major factor

Moisture effects on temperature sensitivity of CO2 exchange in a subarctic heath ecosystem

DEFF Research Database (Denmark)

Illeris, Lotte; Christensen, TR; Mastepanov, M

2004-01-01

Carbon fluxes between natural ecosystems and the atmosphere have received increased attention in recent years due to the impact they have on climate. In order to investigate independently how soil moisture and temperature control carbon fluxes into and out of a dry subarctic dwarf shrub dominated...

The water quality of the river Svratka and its tributaries

Directory of Open Access Journals (Sweden)

Jan Grmela

2013-01-01

Full Text Available Water quality in river depends on water quality of its tributaries. During the year 2011 nine selected sites downstream under the Vír dam (from 108 to 79 river km were monitored. For observation were chosen tributaries Besének, Loučka, Nedvědička, Chlebský creek, Hodonínka, Vrtěžířský creek and Tresný creek. At the same time samples from the places above and under the whole monitored section of the river were taken. Basic physicochemical parameters were monitored monthly during the vegetation period. Flow velocity and discharge were assessed three times. Based on the water quality evaluation of, the river Svratka and its tributaries Hodonínka, Vrtěžířský creek and Tresný creek belong to the second quality class, tributaries Besének, Loučka, Nedvědička and Chlebský belong to the third quality class. In the monitored section the retention of phosphorus in annual amount about 2.2 tons were occurance. Annual volume of phosphorus at the end of observed section (upstream the Tišnov town was nearly 17.5 tons. Annual total balance of nitrogen at the end of monitored section was 700 tons per year and 6000 tons of carbon per year. The major source of these nutrients is the river Loučka.

The transformation and fate of sub-Arctic microphytobenthos carbon revealed through 13C-labeling

DEFF Research Database (Denmark)

Oakes, Joanne M.; Rysgaard, Søren; Glud, Ronnie N.

2016-01-01

Microphytobenthos (MPB) at higher latitudes has been poorly studied. This study used pulse-chase C-13-labeling to investigate the production, processing, and fate of MPB-derived carbon (MPB-C) in sub-Arctic intertidal sediments over 31 d. Gross primary production (2.1 mmolCm(-2)h(-1)+/- 0.4 mmol...... accounted for49.8% of this C-13. The C-13 content of sediment organic carbon declined over time, but>31% of the C-13 fixed within the first tidal cycle remained after 31 d, suggesting that sub-Arctic MPB may contribute to coastal carbon retention during the productive season. Over 21 d, 10.6% of the fixed C......-13 was removed via DIC fluxes and 0.3% via DOC fluxes from inundated sediment, and 0.6% as CO2 from exposed sediment. The greatest loss of C-13 (38.2%) was via unmeasured pathways, including resuspension and/or removal by mobile consumers. The rates of MPB-C production and the relative importance...

33 CFR 117.801 - Newtown Creek, Dutch Kills, English Kills and their tributaries.

Science.gov (United States)

2010-07-01

... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Newtown Creek, Dutch Kills, English Kills and their tributaries. 117.801 Section 117.801 Navigation and Navigable Waters COAST GUARD....801 Newtown Creek, Dutch Kills, English Kills and their tributaries. (a) The following requirements...

Catastrophic valley fills record large Himalayan earthquakes, Pokhara, Nepal

Science.gov (United States)

Stolle, Amelie; Bernhardt, Anne; Schwanghart, Wolfgang; Hoelzmann, Philipp; Adhikari, Basanta R.; Fort, Monique; Korup, Oliver

2017-12-01

Uncertain timing and magnitudes of past mega-earthquakes continue to confound seismic risk appraisals in the Himalayas. Telltale traces of surface ruptures are rare, while fault trenches document several events at best, so that additional proxies of strong ground motion are needed to complement the paleoseismological record. We study Nepal's Pokhara basin, which has the largest and most extensively dated archive of earthquake-triggered valley fills in the Himalayas. These sediments form a 148-km2 fan that issues from the steep Seti Khola gorge in the Annapurna Massif, invading and plugging 15 tributary valleys with tens of meters of debris, and impounding several lakes. Nearly a dozen new radiocarbon ages corroborate at least three episodes of catastrophic sedimentation on the fan between ∼700 and ∼1700 AD, coinciding with great earthquakes in ∼1100, 1255, and 1344 AD, and emplacing roughly >5 km3 of debris that forms the Pokhara Formation. We offer a first systematic sedimentological study of this formation, revealing four lithofacies characterized by thick sequences of mid-fan fluvial conglomerates, debris-flow beds, and fan-marginal slackwater deposits. New geochemical provenance analyses reveal that these upstream dipping deposits of Higher Himalayan origin contain lenses of locally derived river clasts that mark time gaps between at least three major sediment pulses that buried different parts of the fan. The spatial pattern of 14C dates across the fan and the provenance data are key to distinguishing these individual sediment pulses, as these are not evident from their sedimentology alone. Our study demonstrates how geomorphic and sedimentary evidence of catastrophic valley infill can help to independently verify and augment paleoseismological fault-trench records of great Himalayan earthquakes, while offering unparalleled insights into their long-term geomorphic impacts on major drainage basins.

Sustainable Agriculture and Climate Change: Producing Potatoes (Solanum tuberosum L. and Bush Beans (Phaseolus vulgaris L. for Improved Food Security and Resilience in a Canadian Subarctic First Nations Community

Directory of Open Access Journals (Sweden)

Christine D. Barbeau

2015-05-01

Full Text Available Aboriginal people in Canada experience disproportionately high rates of diet-related illnesses, such as obesity and diabetes. Food insecurity has been identified as a contributing factor to these illnesses along with a loss of traditional lifestyle. Current food systems within northern subarctic and arctic regions of Canada rely heavily on imported foods that are expensive (when available, and are environmentally unsustainable. A warming subarctic and arctic climate present challenges, but also offers the opportunity for local agricultural production that can increase food security and promote a more sustainable food system. In this study the feasibility of sustainably growing potatoes (Solanum tuberosum L. utilizing agroforestry practices to enhance food security in remote subarctic communities is explored through a case study in Fort Albany First Nation in northern Ontario, Canada. Potato crops were grown over a two-year period and rotated into plots that had been planted with green bush beans (Phaseolus vulgaris L.. Results showed that potatoes and bush beans could be grown successfully in the subarctic without the use of greenhouses with yields comparable to more conventional high-input agricultural methods. In subarctic Canada, sustainable local food production can help to promote social capital, healthier lifestyles, and food security.

Water Quality Assessment of Danjiangkou Reservoir and its Tributaries in China

Science.gov (United States)

Liu, Linghua; Peng, Wenqi; Wu, Leixiang; Liu, Laisheng

2018-01-01

Danjiangkou Reservoir is an important water source for the middle route of the South to North Water Diversion Project in China, and water quality of Danjiangkou Reservoir and its tributaries is crucial for the project. The purpose of this study is to evaluate the water quality of Daniiangkou Reservoir and its tributaries based on Canadian Council of Ministers of the Environment Water Quality Index (CCMEWQI). 22 water quality parameters from 25 sampling sites were analyzed to calculate WQI. The results indicate that water quality in Danjiangkou Reservoir area, Hanjiang River and Danjiang River is excellent. And the seriously polluted tributary rivers were Shending River, Jianghe River, Sihe River, Tianhe River, Jianhe River and Jiangjun River. Water quality parameters that cannot meet the standard limit for drinking water source were fecal coliform bacteria, CODcr, CODMn, BOD5, NH3-N, TP, DO, anionic surfactant and petroleum. Fecal coliform bacteria, TP, ammonia nitrogen, CODMn were the most common parameters to fail.

Water Quality Assessment Using Benthic Macroinvertebrates in Saigon River and Its Tributaries, Vietnam

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Duc Pham Anh

2016-06-01

Full Text Available This study to enhance the discussion about the usefulness of benthic macroinvertebrates for water quality assessment in Saigon River and its tributaries. Data from 16 sites were used as a representative example for Saigon River and its tributaries in the area of basin over 4,500 km2, the length through provinces of Tay Ninh, Binh Phuoc, Binh Duong, and Ho Chi Minh City of about 280 km. The data covered the period of dry and rainy seasons in 2015, the survey sampled 16 sites (32 events of the Saigon River and its tributaries selected. To implement this evaluation, the analyses were based on MRC methods and classifications these improved by the scientific group.

Molecular analyses reveal high species diversity of trematodes in a sub-Arctic lake

Czech Academy of Sciences Publication Activity Database

Soldánová, Miroslava; Georgieva, Simona; Roháčová, Jana; Knudsen, R.; Kuhn, J. A.; Henriksen, E. H.; Siwertsson, A.; Shaw, J. C.; Kuris, A. M.; Amundsen, P.-A.; Scholz, Tomáš; Lafferty, K. D.; Kostadinova, Aneta

2017-01-01

Roč. 47, č. 6 (2017), s. 327-345 ISSN 0020-7519 R&D Projects: GA ČR GA15-14198S; GA ČR GAP505/10/1562 Institutional support: RVO:60077344 Keywords : Trematode diversity * intermediate hosts * phylogeny * mitochondrial DNA * nuclear DNA * Lake Takvatn * Norway * Sub-Arctic Subject RIV: EG - Zoology OBOR OECD: Zoology Impact factor: 3.730, year: 2016

Suspended-sediment trapping in the tidal reach of an estuarine tributary channel

Science.gov (United States)

Downing-Kunz, Maureen; Schoellhamer, David H.

2015-01-01

Evidence of decreasing sediment supply to estuaries and coastal oceans worldwide illustrates the need for accurate and updated estimates. In the San Francisco Estuary (Estuary), recent research suggests a decrease in supply from its largest tributaries, implying the increasing role of smaller, local tributaries in sediment supply to this estuary. Common techniques for estimating supply from tributaries are based on gages located above head of tide, which do not account for trapping processes within the tidal reach. We investigated the effect of a tidal reach on suspended-sediment discharge for Corte Madera Creek, a small tributary of the Estuary. Discharge of water (Q) and suspended-sediment (SSD) were observed for 3 years at two locations along the creek: upstream of tidal influence and at the mouth. Comparison of upstream and mouth gages showed nearly 50 % trapping of upstream SSD input within the tidal reach over this period. At the storm time scale, suspended-sediment trapping efficiency varied greatly (range −31 to 93 %); storms were classified as low- or high-yield based on upstream SSD. As upstream peak Q increased, high-yield storms exhibited significantly decreased trapping. Tidal conditions at the mouth—ebb duration and peak ebb velocity—during storms had a minor effect on sediment trapping, suggesting fluvial processes dominate. Comparison of characteristic fluvial and tidal discharges at the storm time scale demonstrated longitudinal differences in the regulating process for SSD. These results suggest that SSD from gages situated above head of tide overestimate sediment supply to the open waters beyond tributary mouths and thus trapping processes within the tidal reach should be considered.

Conceptualising the interactive effects of climate change and biological invasions on subarctic freshwater fish.

Science.gov (United States)

Rolls, Robert J; Hayden, Brian; Kahilainen, Kimmo K

2017-06-01

Climate change and species invasions represent key threats to global biodiversity. Subarctic freshwaters are sentinels for understanding both stressors because the effects of climate change are disproportionately strong at high latitudes and invasion of temperate species is prevalent. Here, we summarize the environmental effects of climate change and illustrate the ecological responses of freshwater fishes to these effects, spanning individual, population, community and ecosystem levels. Climate change is modifying hydrological cycles across atmospheric, terrestrial and aquatic components of subarctic ecosystems, causing increases in ambient water temperature and nutrient availability. These changes affect the individual behavior, habitat use, growth and metabolism, alter population spawning and recruitment dynamics, leading to changes in species abundance and distribution, modify food web structure, trophic interactions and energy flow within communities and change the sources, quantity and quality of energy and nutrients in ecosystems. Increases in temperature and its variability in aquatic environments underpin many ecological responses; however, altered hydrological regimes, increasing nutrient inputs and shortened ice cover are also important drivers of climate change effects and likely contribute to context-dependent responses. Species invasions are a complex aspect of the ecology of climate change because the phenomena of invasion are both an effect and a driver of the ecological consequences of climate change. Using subarctic freshwaters as an example, we illustrate how climate change can alter three distinct aspects of species invasions: (1) the vulnerability of ecosystems to be invaded, (2) the potential for species to spread and invade new habitats, and (3) the subsequent ecological effects of invaders. We identify three fundamental knowledge gaps focused on the need to determine (1) how environmental and landscape characteristics influence the

A refined model of Quaternary valley downcutting emphasizing the interplay between tectonically triggered regressive erosion and climatic cyclicity

Science.gov (United States)

Demoulin, A.; Beckers, A.; Rixhon, G.; Braucher, R.; Bourlès, D.; Siame, L.

2012-04-01

While climatic models of valley downcutting discuss the origin of terrace staircases in valleys of middle Europe within the frame of alternating cold and temperate periods of the Quaternary, other models, starting from a base level fall imposed by an initial tectonic signal, describe the response of the drainage network mainly as the propagation of an erosion wave from the place of base level fall (the margin of the uplifted region) toward the headwaters, the two types of model being rarely confronted. In the Ardennes (West Europe), cosmogenic 10Be and 26Al ages have recently been calculated for the abandonment of the Younger Main Terrace (YMT) level (Rixhon et al., 2011), a prominent feature at mid-height of the valleysides marking the starting point of the mid-Pleistocene phase of deep river incision in the massif. These ages show that the terrace has been abandoned diachronically as the result of a migrating erosion wave that started at 0.73 Ma in the Meuse catchment just north of the massif, soon entered the latter, and is still visible in the current long profiles of the Ardennian Ourthe tributaries as knickpoints disturbing their upper reaches. At first glance, these new findings are incompatible with the common belief that the terraces of the Ardennian rivers were generated by a climatically triggered stepwise general incision of the river profiles. However, several details of the terrace staircases (larger than average vertical spacing between the YMT and the next younger terrace, varying number of post-YMT terraces in trunk stream, tributaries and subtributaries) show that a combination of the climatic and tectonic models of river incision is able to satisfactorily account for all available data. The cosmogenic ages of the YMT also point out a particular behaviour of the migrating knickpoints, which apparently propagated on average more slowly in the main rivers than in the tributaries, in contradiction with the relation that makes knickpoint celerity

Decadal Variations of the Western Subarctic Gyre and Main Pycnocline Depth due to Wind Stress Change in the Northern North Pacific

Science.gov (United States)

Nagano, A.; Wakita, M.

2017-12-01

From the late 1990s to the early 2000s, the western subarctic gyre of the North Pacific, a cyclonic circulation in the western subarctic region, shrank northward associated with a decadal increase of sea surface height (SSH). This gyre change displaced the main pycnocline (halocline) downward and is expected to contribute to the deepening of the overlying temperature minimum layer. This is considered to affect the biogeochemical conditions in the western subarctic region, where is known as substantially slow ocean acidification region. In this study, on the basis of wind stress field data in the subpolar region (40˚N—54˚N, 160˚E—135˚W) during 1979—2014 provided by U.S. National Centers for Environmental Prediction/National Center for Atmospheric Research reanalysis, we estimated the variation in SSH, solving the vorticity gradient equation on the beta plane. Decadal increase in SSH at Station K2 (47˚N, 160˚E), representative point of the western subarctic region, was well produced by the calculation, and the correlation coefficient with altimetric SSH exceeds 0.6. The calculated SSH variation consists of the variations due to the barotropic and baroclinic Rossby wave modes. The gyre shrinkage is found to be caused primarily by the barotropic response to the wind change in the whole subpolar region and secondary by the first baroclinic response. Meanwhile, the decadal deepening of the main pycnocline at K2 is attributed to the baroclinic responses of the higher (second, third, and fourth) vertical modes to the local wind change.

Importance of measuring discharge and sediment transport in lesser tributaries when closing sediment budgets

Science.gov (United States)

Griffiths, Ronald E.; Topping, David J.

2017-11-01

Sediment budgets are an important tool for understanding how riverine ecosystems respond to perturbations. Changes in the quantity and grain size distribution of sediment within river systems affect the channel morphology and related habitat resources. It is therefore important for resource managers to know if a river reach is in a state of sediment accumulation, deficit or stasis. Many sediment-budget studies have estimated the sediment loads of ungaged tributaries using regional sediment-yield equations or other similar techniques. While these approaches may be valid in regions where rainfall and geology are uniform over large areas, use of sediment-yield equations may lead to poor estimations of loads in regions where rainfall events, contributing geology, and vegetation have large spatial and/or temporal variability. Previous estimates of the combined mean-annual sediment load of all ungaged tributaries to the Colorado River downstream from Glen Canyon Dam vary by over a factor of three; this range in estimated sediment loads has resulted in different researchers reaching opposite conclusions on the sign (accumulation or deficit) of the sediment budget for particular reaches of the Colorado River. To better evaluate the supply of fine sediment (sand, silt, and clay) from these tributaries to the Colorado River, eight gages were established on previously ungaged tributaries in Glen, Marble, and Grand canyons. Results from this sediment-monitoring network show that previous estimates of the annual sediment loads of these tributaries were too high and that the sediment budget for the Colorado River below Glen Canyon Dam is more negative than previously calculated by most researchers. As a result of locally intense rainfall events with footprints smaller than the receiving basin, floods from a single tributary in semi-arid regions can have large (≥ 10 ×) differences in sediment concentrations between equal magnitude flows. Because sediment loads do not

Building on Sub-Arctic Soil: Geopolymerization of Muskeg to a Densified Load-Bearing Composite.

Science.gov (United States)

Waetzig, Gregory R; Cho, Junsang; Lacroix, Max; Banerjee, Sarbajit

2017-11-07

The marshy water-saturated soil typical of the sub-Arctic represents a considerable impediment to the construction of roads, thereby greatly hindering human habitation and geological excavation. Muskeg, the native water-laden topsoil characteristic of the North American sub-Arctic, represents a particularly vexing challenge for road construction. Muskeg must either be entirely excavated, or for direct construction on muskeg, a mix of partial excavation and gradual compaction with the strategic placement of filling materials must be performed. Here, we demonstrate a novel and entirely reversible geopolymerization method for reinforcing muskeg with wood fibers derived from native vegetation with the addition of inorganic silicate precursors and without the addition of extraneous metal precursors. A continuous siloxane network is formed that links together the muskeg, wood fibers, and added silicates yielding a load-bearing and low-subsidence composite. The geopolymerization approach developed here, based on catalyzed formation of a siloxane network with further incorporation of cellulose, allows for an increase of density as well as compressive strength while reducing the compressibility of the composite.

Wintertime phytoplankton bloom in the Subarctic Pacific supported by continental margin iron

International Nuclear Information System (INIS)

Lam, Phoebe J.; Bishop, James K.B.; Henning, Cara C.; Marcus, Matthew A.; Waychunas, Glenn A.; Fung, Inez

2004-01-01

Heightened biological activity was observed in February 1996 in the high-nutrient low-chlorophyll (HNLC) subarctic North Pacific Ocean, a region that is thought to be iron-limited. Here we provide evidence supporting the hypothesis that Ocean Station Papa (OSP) in the subarctic Pacific received a lateral supply of particulate iron from the continental margin off the Aleutian Islands in the winter, coincident with the observed biological bloom. Synchrotron X-ray analysis was used to describe the physical form, chemistry, and depth distributions of iron in size fractionated particulate matter samples. The analysis reveals that discrete micron-sized iron-rich hotspots are ubiquitous in the upper 200m at OSP, more than 900km from the closest coast. The specifics of the chemistry and depth profiles of the Fe hot spots trace them to the continental margins. We thus hypothesize that iron hotspots are a marker for the delivery of iron from the continental margin. We confirm the delivery of continental margin iron to the open ocean using an ocean general circulation model with an iron-like tracer source at the continental margin. We suggest that iron from the continental margin stimulated a wintertime phytoplankton bloom, partially relieving the HNLC condition

Doubled volatile organic compound emissions from subarctic tundra under simulated climate warming.

Science.gov (United States)

Faubert, Patrick; Tiiva, Päivi; Rinnan, Asmund; Michelsen, Anders; Holopainen, Jarmo K; Rinnan, Riikka

2010-07-01

*Biogenic volatile organic compound (BVOC) emissions from arctic ecosystems are important in view of their role in global atmospheric chemistry and unknown feedbacks to global warming. These cold ecosystems are hotspots of climate warming, which will be more severe here than averaged over the globe. We assess the effects of climatic warming on non-methane BVOC emissions from a subarctic heath. *We performed ecosystem-based chamber measurements and gas chromatography-mass spectrometry (GC-MS) analyses of the BVOCs collected on adsorbent over two growing seasons at a wet subarctic tundra heath hosting a long-term warming and mountain birch (Betula pubescens ssp. czerepanovii) litter addition experiment. *The relatively low emissions of monoterpenes and sesquiterpenes were doubled in response to an air temperature increment of only 1.9-2.5 degrees C, while litter addition had a minor influence. BVOC emissions were seasonal, and warming combined with litter addition triggered emissions of specific compounds. *The unexpectedly high rate of release of BVOCs measured in this conservative warming scenario is far above the estimates produced by the current models, which underlines the importance of a focus on BVOC emissions during climate change. The observed changes have implications for ecological interactions and feedback effects on climate change via impacts on aerosol formation and indirect greenhouse effects.

That mighty pantun river and its tributaries

Directory of Open Access Journals (Sweden)

Ding Choo Ming

2010-04-01

Full Text Available Known as pantun to the Malays in Brunei, Malaysia, Pattani, Riau, Singapore, and Southern Phillipines, it is called peparikan to the Javanese, sesindiran to the Sundanese and many other different names in different ethnic groups in the different parts of the Indo-Malay world, which is made up of Brunei, Indonesia, Malaysia, Singapore, Pattani in southern Thailand, and Mindanao in the southern Philippines. In almost every settlement that sprang up along the major rivers and tributaries in the Indo-Malay world, the pantun blend well with their natural and cultural surroundings. In this article, the geographical extent of the pantun family in the Indo-Malay world is likened to a mighty river that has a complex network of tributaries all over the Indo-Malay world. Within the Indo-Malay world, it is the movement of the peoples help the spread of pantun from one area to the other and makes it an art form of immensely rich and intricate as can be seen from the examples given.

Analysis of anaerobic BTX biodegradation in a subarctic aquifer using isotopes and benzylsuccinates.

Science.gov (United States)

McKelvie, Jennifer R; Lindstrom, Jon E; Beller, Harry R; Richmond, Sharon A; Sherwood Lollar, Barbara

2005-12-01

In situ biodegradation of benzene, toluene, and xylenes in a petroleum hydrocarbon contaminated aquifer near Fairbanks, Alaska was assessed using carbon and hydrogen compound specific isotope analysis (CSIA) of benzene and toluene and analysis of signature metabolites for toluene (benzylsuccinate) and xylenes (methylbenzylsuccinates). Carbon and hydrogen isotope ratios of benzene were between -25.9 per thousand and -26.8 per thousand for delta13C and -119 per thousand and -136 per thousand for delta2H, suggesting that biodegradation of benzene is unlikely at this site. However, biodegradation of both xylenes and toluene were documented in this subarctic aquifer. Biodegradation of xylenes was indicated by the presence of methylbenzylsuccinates with concentrations of 17-50 microg/L in three wells. Anaerobic toluene biodegradation was also indicated by benzylsuccinate concentrations of 10-49 microg/L in the three wells with the highest toluene concentrations (1500-5000 microg/L toluene). Since benzylsuccinate typically accounts for a very small fraction of the toluene present in groundwater (generally data is particularly valuable given the challenge of verifying biodegradation in subarctic environments where degradation rates are typically much slower than in temperate environments.

Uptake of pulse injected nitrogen by soil microbes and mycorrhizal and non-mycorrhizal plants in a species-diverse subarctic heath ecosystem

DEFF Research Database (Denmark)

Andresen, Louise Christoffersen; Jonasson, Sven; Strom, Lena

2008-01-01

15N labeled ammonium, glycine or glutamic acid was injected into subarctic heath soil in situ, with the purpose of investigating how the nitrogen added in these pulses was subsequently utilized and cycled in the ecosystem. We analyzed the acquisition of 15N label in mycorrhizal and non-mycorrhiza......15N labeled ammonium, glycine or glutamic acid was injected into subarctic heath soil in situ, with the purpose of investigating how the nitrogen added in these pulses was subsequently utilized and cycled in the ecosystem. We analyzed the acquisition of 15N label in mycorrhizal and non...

Diversity of active aerobic methanotrophs along depth profiles of arctic and subarctic lake water column and sediments

Science.gov (United States)

He, Ruo; Wooller, Matthew J.; Pohlman, John W.; Quensen, John; Tiedje, James M.; Leigh, Mary Beth

2012-01-01

Methane (CH4) emitted from high-latitude lakes accounts for 2–6% of the global atmospheric CH4 budget. Methanotrophs in lake sediments and water columns mitigate the amount of CH4 that enters the atmosphere, yet their identity and activity in arctic and subarctic lakes are poorly understood. We used stable isotope probing (SIP), quantitative PCR (Q-PCR), pyrosequencing and enrichment cultures to determine the identity and diversity of active aerobic methanotrophs in the water columns and sediments (0–25 cm) from an arctic tundra lake (Lake Qalluuraq) on the north slope of Alaska and a subarctic taiga lake (Lake Killarney) in Alaska's interior. The water column CH4 oxidation potential for these shallow (~2m deep) lakes was greatest in hypoxic bottom water from the subarctic lake. The type II methanotroph, Methylocystis, was prevalent in enrichment cultures of planktonic methanotrophs from the water columns. In the sediments, type I methanotrophs (Methylobacter, Methylosoma and Methylomonas) at the sediment-water interface (0–1 cm) were most active in assimilating CH4, whereas the type I methanotroph Methylobacter and/or type II methanotroph Methylocystis contributed substantially to carbon acquisition in the deeper (15–20 cm) sediments. In addition to methanotrophs, an unexpectedly high abundance of methylotrophs also actively utilized CH4-derived carbon. This study provides new insight into the identity and activity of methanotrophs in the sediments and water from high-latitude lakes.

On the use of mulching to mitigate permafrost thaw due to linear disturbances in sub-arctic peatlands

Science.gov (United States)

The presence or absence of permafrost significantly influences the hydrology and ecology of northern watersheds. Resource exploration activities are currently having noticeable effects on hydrological and ecological processes in sub-arctic peatlands. Disturbances such as seismic cutlines can result ...

Floods of November-December 1950 in the Central Valley basin, California

Science.gov (United States)

Paulsen, C.G.

1953-01-01

The flood of November-December 1950 in the Central Valley basin was the greatest in most parts of the basin since the turn of the century and probably was exceeded in the lower San Joaquin River basin only by the historic flood of 1862. In respect to monetary loss, the 1950 flood was the most disastrous in the history of the basin. Loss of life was remarkably small when one considers the extensive damage and destruction to homes and other property, which is estimated at 33 million dollars. Outstanding features of the flood were its unprecedented occurrence so early in the winter flood season, its magnitude in respect to both peak and volume in most major tributaries, and the occurrence of a succession of near-peak flows with a period of three weeks. The flood was caused by a series of storms during the period November 16 to December 8, which brought exceptionally warm, moisture-laden air inland against the Sierra Nevada range and caused intense rainfall, instead of snowfall, at unusually high altitudes. Basin-wide totals of rainfall during the period ranged from 30 inches over the Yuba and American River basins to 13 inches over the upper Sacramento and Feather River basins. Based on continuous records of discharge on major tributaries for periods ranging from 22 to 55 years and averaging about 43 years, the 1950 flood peaks were the greatest of record on the American, Cosumnes, Mokelumne, Stanislaus, Tuolumne, Merced, Chowchilla, Fresno, lower San Joaquin, Kings, Kaweah, Tule, and Kern Rivers. Second highest peak of record occurred during the flood of March 1928 on the Yuba, American and Mokelumne Rivers; the flood of Marcn 1940 on Cosumnes River; the flood of January 1911 on the Stanislaus and Tuolumne Rivers; the flood of December 1937 on the Merced, Kings, and Kaweah Rivers; the flood of March 1938 on the Chowchilla, Fresno, and lower San Joaquin Rivers; and the flood of March 1943 on the Tule and Kern Rivers. Peak discharges for 1950 did not exceed previous

Carbon dioxide exchange in subarctic ecosystems measured by a micrometeorological technique

International Nuclear Information System (INIS)

Aurela, M.

2005-01-01

The atmospheric CO 2 concentration and the surface air temperatures have increased since the pre-industrial era, and the increase in both is predicted to continue during the 21st century. The feedback mechanisms between the changing climate and the carbon cycle are complex, and more information is needed about carbon exchange in different ecosystems. Northern Finland lies in the transition zone between boreal forest and tundra where the ecosystems are especially sensitive to any changes in the climate. In 1995-2004, micrometeorological eddy covariance measurements were conducted to yield continuous data on the CO 2 exchange between the atmosphere and the biosphere in northern Finland on four different ecosystems: an aapa mire, a mountain birch forest, a Scots pine forest and a Norway spruce forest. A measurement system enabling year-round measurements in the harsh subarctic conditions was developed and shown to be suitable for long-term exchange studies. A comparison of the CO 2 flux components, photosynthesis and respiration, at different ecosystems in the European subarctic and arctic regions showed that the leaf area index (LAI) is the key determinant of the gross photosynthetic rates, explaining greatest part of the variation between these ecosystems. Respiration did not show such a strong correlation with LAI, but in general, high respiration rates were related to high values of LAI. The first continuous round-the-year measurements of net ecosystem CO 2 exchange on a subarctic wetland were conducted at Kaamanen. The winter-time CO 2 efflux (of about 90 g CO 2 m -2 yr -1 ) was shown to constitute an essential part of the annual CO 2 balance (of -79 g CO 2 m -2 yr -1 in 1997-2002). The annual CO 2 balances at all sites in northern Finland were relatively small compared with those in lower latitudes. The interannual variation of the CO 2 balance at Kaamanen was marked (-15 to -195 g CO 2 m -2 yr -1 ) during the years 1997-2002. The most important factor

The Arctic-Subarctic Sea Ice System is Entering a Seasonal Regime: Implications for Future Arctic Amplication

Science.gov (United States)

Haine, T. W. N.; Martin, T.

2017-12-01

The loss of Arctic sea ice is a conspicuous example of climate change. Climate models project ice-free conditions during summer this century under realistic emission scenarios, reflecting the increase in seasonality in ice cover. To quantify the increased seasonality in the Arctic-Subarctic sea ice system, we define a non-dimensional seasonality number for sea ice extent, area, and volume from satellite data and realistic coupled climate models. We show that the Arctic-Subarctic, i.e. the northern hemisphere, sea ice now exhibits similar levels of seasonality to the Antarctic, which is in a seasonal regime without significant change since satellite observations began in 1979. Realistic climate models suggest that this transition to the seasonal regime is being accompanied by a maximum in Arctic amplification, which is the faster warming of Arctic latitudes compared to the global mean, in the 2010s. The strong link points to a peak in sea-ice-related feedbacks that occurs long before the Arctic becomes ice-free in summer.

Human exposure to soil contaminants in subarctic Ontario, Canada

Directory of Open Access Journals (Sweden)

Ellen Stephanie Reyes

2015-05-01

Full Text Available Background: Chemical contaminants in the Canadian subarctic present a health risk with exposures primarily occurring via the food consumption. Objective: Characterization of soil contaminants is needed in northern Canada due to increased gardening and agricultural food security initiatives and the presence of known point sources of pollution. Design: A field study was conducted in the western James Bay Region of Ontario, Canada, to examine the concentrations of polychlorinated biphenyls, dichlorodiphenyltrichloroethane and its metabolites (ΣDDT, other organochlorines, and metals/metalloids in potentially contaminated agriculture sites. Methods: Exposure pathways were assessed by comparing the estimated daily intake to acceptable daily intake values. Ninety soil samples were collected at random (grid sampling from 3 plots (A, B, and C in Fort Albany (on the mainland, subarctic Ontario, Canada. The contaminated-soil samples were analysed by gas chromatography with an electron capture detector or inductively coupled plasma mass spectrometer. Results: The range of ΣDDT in 90 soil samples was below the limit of detection to 4.19 mg/kg. From the 3 soil plots analysed, Plot A had the highest ΣDDT mean concentration of 1.12 mg/kg, followed by Plot B and Plot C which had 0.09 and 0.01 mg/kg, respectively. Concentrations of other organic contaminants and metals in the soil samples were below the limit of detection or found in low concentrations in all plots and did not present a human health risk. Conclusions: Exposure analyses showed that the human risk was below regulatory thresholds. However, the ΣDDT concentration in Plot A exceeded soil guidelines set out by the Canadian Council of Ministers of the Environment of 0.7 mg/kg, and thus the land should not be used for agricultural or recreational purposes. Both Plots B and C were below threshold limits, and this land can be used for agricultural purposes.

Geographic Distribution of Ammonia-Oxidizing Archaea along the Kuril Islands in the Western Subarctic Pacific

Directory of Open Access Journals (Sweden)

Hongmei Jing

2017-06-01

Full Text Available Community composition and abundance of ammonia-oxidizing archaea (AOA in the ocean were affected by different physicochemical conditions, but their responses to physical barriers (such as a chain of islands were largely unknown. In our study, geographic distribution of the AOA from the surface photic zone to the deep bathypelagic waters in the western subarctic Pacific adjacent to the Kuril Islands was investigated using pyrosequencing based on the ammonia monooxygenase subunit A (amoA gene. Genotypes of clusters A and B dominated in the upper euphotic zone and the deep waters, respectively. Quantitative PCR assays revealed that the occurrence and ammonia-oxidizing activity of ammonia-oxidizing archaea (AOA reached their maxima at the depth of 200 m, where a higher diversity and abundance of actively transcribed AOA was observed at the station located in the marginal sea exposed to more terrestrial input. Similar community composition of AOA observed at the two stations adjacent to the Kuril Islands maybe due to water exchange across the Bussol Strait. They distinct from the station located in the western subarctic gyre, where sub-cluster WCAII had a specific distribution in the surface water, and this sub-cluster seemed having a confined distribution in the western Pacific. Habitat-specific groupings of different WCB sub-clusters were observed reflecting the isolated microevolution existed in cluster WCB. The effect of the Kuril Islands on the phylogenetic composition of AOA between the Sea of Okhotsk and the western subarctic Pacific is not obvious, possibly because our sampling stations are near to the Bussol Strait, the main gateway through which water is exchanged between the Sea of Okhotsk and the Pacific. The vertical and horizontal distribution patterns of AOA communities among stations along the Kuril Islands were essentially determined by the in situ prevailing physicochemical gradients along the two dimensions.

Analysis of the Carmel Valley alluvial ground-water basin, Monterey County, California

Science.gov (United States)

Kapple, Glenn W.; Mitten, Hugh T.; Durbin, Timothy J.; Johnson, Michael J.

1984-01-01

A two-dimensional, finite-element, digital model was developed for the Carmel Valley alluvial ground-water basin using measured, computed, and estimated discharge and recharge data for the basin. Discharge data included evapotranspiration by phreatophytes and agricultural, municipal, and domestic pumpage. Recharge data included river leakage, tributary runoff, and pumping return flow. Recharge from subsurface boundary flow and rainfall infiltration was assumed to be insignificant. From 1974 through 1978, the annual pumping rate ranged from 5,900 to 9,100 acre-feet per year with 55 percent allotted to municipal use principally exported out of the valley, 44 percent to agricultural use, and 1 percent to domestic use. The pumpage return flow within the valley ranged from 900 to 1,500 acre-feet per year. The aquifer properties of transmissivity (about 5,900 feet squared per day) and of the storage coefficient (0.19) were estimated from an average alluvial thickness of 75 feet and from less well-defined data on specific capacity and grain-size distribution. During calibration the values estimated for hydraulic conductivity and storage coefficient for the lower valley were reduced because of the smaller grain size there. The river characteristics were based on field and laboratory analyses of hydraulic conductivity and on altitude survey data. The model is intended principally for simulation of flow conditions using monthly time steps. Time variations in transmissivity and short-term, highrecharge potential are included in the model. The years 1974 through 1978 (including "pre-" and "post-" drought) were selected because of the extreme fluctuation in water levels between the low levels measured during dry years and the above-normal water levels measured during the preceding and following wet years. Also, during this time more hydrologic information was available. Significantly, computed water levels were generally within a few feet of the measured levels, and computed

Timing, frequency and environmental conditions associated with mainstem-tributary movement by a lowland river fish, golden perch (Macquaria ambigua.

Directory of Open Access Journals (Sweden)

Wayne M Koster

Full Text Available Tributary and mainstem connections represent important links for the movement of fish and other biota throughout river networks. We investigated the timing, frequency and environmental conditions associated with movements by adult golden perch (Macquaria ambigua between the mainstem of the mid-Murray River and a tributary, the Goulburn River, in south-eastern Australia, using acoustic telemetry over four years (2007-2011. Fish were tagged and released in autumn 2007-2009 in the mid-Murray (n = 42 and lower Goulburn (n = 37 rivers within 3-6 km of the mid-Murray-lower Goulburn junction. 38% of tagged fish undertook mainstem-tributary movements, characterised mostly by temporary occupation followed by return of fish to the original capture river. Approximately 10% of tagged fish exhibited longer-term shifts between the mainstem and tributary. Movement of fish from the tributary into the mainstem occurred primarily during the spawning season and in some years coincided with the presence of golden perch eggs/larvae in drift samples in the mainstem. Many of the tributary-to-mainstem movements occurred during or soon after changes in flow. The movements of fish from the mainstem into the tributary were irregular and did not appear to be associated with spawning. The findings show that golden perch moved freely across the mainstem-tributary interface. This demonstrates the need to consider the spatial, behavioural and demographic interdependencies of aquatic fauna across geographic management units such as rivers.

Timing, frequency and environmental conditions associated with mainstem-tributary movement by a lowland river fish, golden perch (Macquaria ambigua).

Science.gov (United States)

Koster, Wayne M; Dawson, David R; O'Mahony, Damien J; Moloney, Paul D; Crook, David A

2014-01-01

Tributary and mainstem connections represent important links for the movement of fish and other biota throughout river networks. We investigated the timing, frequency and environmental conditions associated with movements by adult golden perch (Macquaria ambigua) between the mainstem of the mid-Murray River and a tributary, the Goulburn River, in south-eastern Australia, using acoustic telemetry over four years (2007-2011). Fish were tagged and released in autumn 2007-2009 in the mid-Murray (n = 42) and lower Goulburn (n = 37) rivers within 3-6 km of the mid-Murray-lower Goulburn junction. 38% of tagged fish undertook mainstem-tributary movements, characterised mostly by temporary occupation followed by return of fish to the original capture river. Approximately 10% of tagged fish exhibited longer-term shifts between the mainstem and tributary. Movement of fish from the tributary into the mainstem occurred primarily during the spawning season and in some years coincided with the presence of golden perch eggs/larvae in drift samples in the mainstem. Many of the tributary-to-mainstem movements occurred during or soon after changes in flow. The movements of fish from the mainstem into the tributary were irregular and did not appear to be associated with spawning. The findings show that golden perch moved freely across the mainstem-tributary interface. This demonstrates the need to consider the spatial, behavioural and demographic interdependencies of aquatic fauna across geographic management units such as rivers.

Timing, Frequency and Environmental Conditions Associated with Mainstem–Tributary Movement by a Lowland River Fish, Golden Perch (Macquaria ambigua)

Science.gov (United States)

Koster, Wayne M.; Dawson, David R.; O’Mahony, Damien J.; Moloney, Paul D.; Crook, David A.

2014-01-01

Tributary and mainstem connections represent important links for the movement of fish and other biota throughout river networks. We investigated the timing, frequency and environmental conditions associated with movements by adult golden perch (Macquaria ambigua) between the mainstem of the mid-Murray River and a tributary, the Goulburn River, in south-eastern Australia, using acoustic telemetry over four years (2007–2011). Fish were tagged and released in autumn 2007–2009 in the mid-Murray (n = 42) and lower Goulburn (n = 37) rivers within 3–6 km of the mid-Murray-lower Goulburn junction. 38% of tagged fish undertook mainstem–tributary movements, characterised mostly by temporary occupation followed by return of fish to the original capture river. Approximately 10% of tagged fish exhibited longer-term shifts between the mainstem and tributary. Movement of fish from the tributary into the mainstem occurred primarily during the spawning season and in some years coincided with the presence of golden perch eggs/larvae in drift samples in the mainstem. Many of the tributary-to-mainstem movements occurred during or soon after changes in flow. The movements of fish from the mainstem into the tributary were irregular and did not appear to be associated with spawning. The findings show that golden perch moved freely across the mainstem–tributary interface. This demonstrates the need to consider the spatial, behavioural and demographic interdependencies of aquatic fauna across geographic management units such as rivers. PMID:24788137

Predicting the occurrence of cold water patches at intermittent and ephemeral tributary confluences with warm rivers

Science.gov (United States)

Small, cold tributary streams can provide important thermal refuge habitat for cold-water fishes such as Pacific salmon (Oncorhynchus spp.) residing in warm, downstream receiving waters. We investigated the potential function of small perennial and non-perennial tributary stream...

The importance of colony structure versus shoot morphology for the water balance of 22 subarctic bryophyte species

NARCIS (Netherlands)

Elumeeva, Tatiana G.; Soudzilovskaia, Nadejda A.; During, Heinjo J.; Cornelissen, Johannes H.C.

Questions: What are the water economy strategies of the dominant subarctic bryophytes in terms of colony and shoot traits? Can colony water retention capacity be predicted from morphological traits of both colonies and separate shoots? Are suites of water retention traits consistently related to

Characterization of down-valley winds in stable stratification from the KASCADE field campaign and WRF mesoscale simulations

International Nuclear Information System (INIS)

Duine, Gert-Jan

2015-01-01

This thesis investigates down-valley wind characteristics in complex terrain of moderate oro-graphy for a mid-latitude area. The work was motivated by safety regulation in the context of sanitary impact of the Cadarache centre on its close surroundings. Cadarache is one of the research centres of 'Commissariat a l'Energie Atomique et aux Energies Alternatives' (CEA), located in southeastern France. It is embedded in a small valley, the Cadarache Valley (CV), which is one of the tributaries of the larger Durance Valley (DV). The two valleys are distinct in width (1 - 2 vs. 5 km for CV and DV, respectively), length (5 vs. more than 60 km), depth (100 vs. 200 m and higher) and slope angle (1 degree vs. 0.2 degree on average along the valleys main axis), and therefore react differently under stable conditions. Stable stratifications regularly occur in the region due to frequent weak synoptic forcing and clear sky conditions. During such conditions, dilution of pollutants can become weak; this is one of the major motivations of the present study. To investigate the valley wind behaviour, the KASCADE (Katabatic winds and Stability over Cadarache for Dispersion of Effluents) campaign has been designed. It was conducted in the winter of 2013 including continuous observations (flux tower, Sodar and Cadarache observational network) covering a 3-month period and 23 intensive observation periods (IOPs). During the IOPs tethered balloon experiments were conducted and radio-soundings were launched. An IOP was carried out when weak synoptic forcing periods and clear skies were expected, started at 12 UTC and lasted 24 hours. A calibration experiment served for sensor correction purposes, resulting in a high quality data set of a well-documented campaign (http://kascade.sedoo.fr/). The valley flows at the local and regional scale are characterized from observations analysis and IOP simulations with the non-hydrostatic WRF model. The analysis shows that the Cadarache

Modeling groundwater/surface-water interactions in an Alpine valley (the Aosta Plain, NW Italy): the effect of groundwater abstraction on surface-water resources

Science.gov (United States)

Stefania, Gennaro A.; Rotiroti, Marco; Fumagalli, Letizia; Simonetto, Fulvio; Capodaglio, Pietro; Zanotti, Chiara; Bonomi, Tullia

2018-02-01

A groundwater flow model of the Alpine valley aquifer in the Aosta Plain (NW Italy) showed that well pumping can induce river streamflow depletions as a function of well location. Analysis of the water budget showed that ˜80% of the water pumped during 2 years by a selected well in the downstream area comes from the baseflow of the main river discharge. Alluvial aquifers hosted in Alpine valleys fall within a particular hydrogeological context where groundwater/surface-water relationships change from upstream to downstream as well as seasonally. A transient groundwater model using MODFLOW2005 and the Streamflow-Routing (SFR2) Package is here presented, aimed at investigating water exchanges between the main regional river (Dora Baltea River, a left-hand tributary of the Po River), its tributaries and the underlying shallow aquifer, which is affected by seasonal oscillations. The three-dimensional distribution of the hydraulic conductivity of the aquifer was obtained by means of a specific coding system within the database TANGRAM. Both head and flux targets were used to perform the model calibration using PEST. Results showed that the fluctuations of the water table play an important role in groundwater/surface-water interconnections. In upstream areas, groundwater is recharged by water leaking through the riverbed and the well abstraction component of the water budget changes as a function of the hydraulic conditions of the aquifer. In downstream areas, groundwater is drained by the river and most of the water pumped by wells comes from the base flow component of the river discharge.

Occurrence and transport of diazinon in the Sacramento River, California, and selected tributaries during three winter storms, January-February 2000

Science.gov (United States)

Dileanis, Peter D.; Bennett, Kevin P.; Domagalski, Joseph L.

2002-01-01

The organophosphate pesticide diazinon is applied as a dormant orchard spray in the Sacramento Valley, California, during the winter when the area receives a majority of its annual rainfall. Dormant spray pesticides, thus, have the potential to wash off the areas of application and migrate with storm runoff to streams in the Sacramento River Basin. Previous monitoring studies have shown that rain and associated runoff from winter storms plays an important role in the transport of diazinon from point of application to the Sacramento River and tributaries. Between January 30 and February 25, 2000, diazinon concentrations in the Sacramento River and selected tributaries were monitored on 5 consecutive days during each of three winter storms that moved through the Sacramento Valley after diazinon had been applied to orchards in the basin. Water samples were collected at 17 sites chosen to represent the effect of upstream land use at local and regional scales. Most samples were analyzed using an enzyme-linked immunosorbent assay (ELISA). Analysis by gas chromatography with electron capture detector and thermionic specific detector (GC/ECD/TSD) and gas chromatography with mass spectrometry (GC/MS) was done on split replicates from over 30 percent of the samples to confirm ELISA results and to provide lower analytical reporting limits at selected sites [30 ng/L (nanogram per liter) for ELISA, 20 ng/L for GC/ECD/TSD, and 2 ng/L for GC/MS]. Concentrations determined from ELISA analyses were consistently higher than concentrations for split samples analyzed by gas chromatography methods. Because of bias between diazinon concentrations using ELISA and gas chromatography methods, results from ELISA analyses were not compared to water-quality criteria. Load calculations using the ELISA analyses are similarly biased. Because the bias was consistent, however, the ELISA data is useful in site-to-site comparisons used to rank the relative levels and contributions of diazinon from

Sub-arctic hydrology and climate change : a case study of the Tana River Basin in Northern Fennoscandia

NARCIS (Netherlands)

Dankers, Rutger

2002-01-01

The most significant changes in climate, due to the well-known enhanced greenhouse effect, are generally expected to occur at northern high latitudes. Sub-arctic environments, that are dominated by the presence of a seasonal snow cover, may therefore be particularly sensitive to global warming. The

CO2 and CH4 in sea ice from a subarctic fjord under influence of riverine input

DEFF Research Database (Denmark)

Crabeck, O.; Delille, B.; Thomas, D. N.

2014-01-01

We present CH4 concentration [CH4] and the partial pressure of CO2 (pCO2) in bulk sea ice from subarctic, land-fast sea ice in the Kapisillit fjord, Greenland. The bulk ice [CH4] ranged from 1.8 to 12.1 nmol L−1, which corresponds to a partial pressure range of 3 to 28 ppmv. This is markedly higher......-saturated compared to the atmosphere (390 ppmv). Our study adds to the few existing studies of CH4 and CO2 in sea ice and concludes that sub-arctic sea can be a sink for atmospheric CO2, while being a net source of CH4. Processes related to the freezing and melting of sea ice represents large unknowns...... to the exchange of CO2 but also CH4. It is therefore imperative to assess the consequences of these unknowns through further field campaigns and targeted research under other sea ice conditions at both hemispheres....

Valley-dependent band structure and valley polarization in periodically modulated graphene

Science.gov (United States)

Lu, Wei-Tao

2016-08-01

The valley-dependent energy band and transport property of graphene under a periodic magnetic-strained field are studied, where the time-reversal symmetry is broken and the valley degeneracy is lifted. The considered superlattice is composed of two different barriers, providing more degrees of freedom for engineering the electronic structure. The electrons near the K and K' valleys are dominated by different effective superlattices. It is found that the energy bands for both valleys are symmetric with respect to ky=-(AM+ξ AS) /4 under the symmetric superlattices. More finite-energy Dirac points, more prominent collimation behavior, and new crossing points are found for K' valley. The degenerate miniband near the K valley splits into two subminibands and produces a new band gap under the asymmetric superlattices. The velocity for the K' valley is greatly renormalized compared with the K valley, and so we can achieve a finite velocity for the K valley while the velocity for the K' valley is zero. Especially, the miniband and band gap could be manipulated independently, leading to an increase of the conductance. The characteristics of the band structure are reflected in the transmission spectra. The Dirac points and the crossing points appear as pronounced peaks in transmission. A remarkable valley polarization is obtained which is robust to the disorder and can be controlled by the strain, the period, and the voltage.

Bacterial carbon cycling in a subarctic fjord

DEFF Research Database (Denmark)

Middelboe, Mathias; Glud, Ronnie Nøhr; Sejr, M.K.

2012-01-01

of viruses on bacterial mortality (4–36% of cell production) and carbon cycling. Heterotrophic bacterial consumption was closely coupled with autochthonous BDOC production, and the majority of the primary production was consumed by pelagic bacteria at all seasons. The relatively low measured BGE emphasized......In this seasonal study, we examined the environmental controls and quantitative importance of bacterial carbon consumption in the water column and the sediment in the subarctic Kobbefjord, Greenland. Depth-integrated bacterial production in the photic zone varied from 5.0 ± 2.7 mg C m−2 d−1...... in February to 42 ± 28 mg C m−2 d−1 in May and 34 ± 7 mg C m−2 d−1 in September, corresponding to a bacterial production to primary production ratio of 0.34 ± 0.14, 0.07 ± 0.04, and 0.08 ± 0.06, respectively. Based on measured bacterial growth efficiencies (BGEs) of 0.09–0.10, pelagic bacterial carbon...

Oxygen and silicon stable isotopes of diatom silica. Reconstructing changes in surface water hydrography and silicic acid utilization in the late Pleistocene subarctic Pacific

Energy Technology Data Exchange (ETDEWEB)

Maier, Edith

2014-03-05

Deglacial variations in upper ocean nutrient dynamics and stratification in high latitudes, as well as associated changes in thermohaline overturning circulation, are thought to have played a key role in changing atmospheric CO{sub 2} concentrations. This thesis examines the relationship between past changes in subarctic Pacific upper ocean stratification and nutrient (silicic acid) utilization, using oxygen and silicon stable isotopes of diatom silica, for the first time at millennial-scale resolution and analyzed with a new and efficient instrumentation set-up. The isotopic data, presented in three manuscripts, show a consistent picture of millennial-scale variability in upper ocean stratification and silicic acid utilization during the last ∝50 ka BP, e.g. indicating that the subarctic Pacific was a source region for atmospheric CO{sub 2} during the last deglaciation (late Heinrich Stadial 1 and the Boelling/Alleroed). The presented results demonstrate the high potential of combined diatom oxygen and silicon stable isotope analysis especially for, but not restricted to, marine regions characterized by a low biogenic carbonate content like the subarctic Pacific and the Southern Ocean.

Oxygen and silicon stable isotopes of diatom silica. Reconstructing changes in surface water hydrography and silicic acid utilization in the late Pleistocene subarctic Pacific

International Nuclear Information System (INIS)

Maier, Edith

2014-01-01

Deglacial variations in upper ocean nutrient dynamics and stratification in high latitudes, as well as associated changes in thermohaline overturning circulation, are thought to have played a key role in changing atmospheric CO 2 concentrations. This thesis examines the relationship between past changes in subarctic Pacific upper ocean stratification and nutrient (silicic acid) utilization, using oxygen and silicon stable isotopes of diatom silica, for the first time at millennial-scale resolution and analyzed with a new and efficient instrumentation set-up. The isotopic data, presented in three manuscripts, show a consistent picture of millennial-scale variability in upper ocean stratification and silicic acid utilization during the last ∝50 ka BP, e.g. indicating that the subarctic Pacific was a source region for atmospheric CO 2 during the last deglaciation (late Heinrich Stadial 1 and the Boelling/Alleroed). The presented results demonstrate the high potential of combined diatom oxygen and silicon stable isotope analysis especially for, but not restricted to, marine regions characterized by a low biogenic carbonate content like the subarctic Pacific and the Southern Ocean.

Stream seepage and groundwater levels, Wood River Valley, south-central Idaho, 2012-13

Science.gov (United States)

Bartolino, James R.

2014-01-01

Stream discharge and water levels in wells were measured at multiple sites in the Wood River Valley, south-central Idaho, in August 2012, October 2012, and March 2013, as a component of data collection for a groundwater-flow model of the Wood River Valley aquifer system. This model is a cooperative and collaborative effort between the U.S. Geological Survey and the Idaho Department of Water Resources. Stream-discharge measurements for determination of seepage were made during several days on three occasions: August 27–28, 2012, October 22–24, 2012, and March 27–28, 2013. Discharge measurements were made at 49 sites in August and October, and 51 sites in March, on the Big Wood River, Silver Creek, their tributaries, and nearby canals. The Big Wood River generally gains flow between the Big Wood River near Ketchum streamgage (13135500) and the Big Wood River at Hailey streamgage (13139510), and loses flow between the Hailey streamgage and the Big Wood River at Stanton Crossing near Bellevue streamgage (13140800). Shorter reaches within these segments may differ in the direction or magnitude of seepage or may be indeterminate because of measurement uncertainty. Additional reaches were measured on Silver Creek, the North Fork Big Wood River, Warm Springs Creek, Trail Creek, and the East Fork Big Wood River. Discharge measurements also were made on the Hiawatha, Cove, District 45, Glendale, and Bypass Canals, and smaller tributaries to the Big Wood River and Silver Creek. Water levels in 93 wells completed in the Wood River Valley aquifer system were measured during October 22–24, 2012; these wells are part of a network established by the U.S. Geological Survey in 2006. Maps of the October 2012 water-table altitude in the unconfined aquifer and the potentiometric-surface altitude of the confined aquifer have similar topology to those on maps of October 2006 conditions. Between October 2006 and October 2012, water-table altitude in the unconfined aquifer rose by

Hydrochemical and isotope study to trace the movement of pollutants from the Akuosu - Sukobri tributary into the Owabi reservoir

International Nuclear Information System (INIS)

Frimpong, E.O.

2011-01-01

Surface water and sediment samples of the Akuosu - Sukobri tributary were analyzed to asses the movement of heavy metal pollution into the Owabi reservoir. Whilst the Akuosu - Sukobri tributary is acidic, the Owabi reservoir is basic. The concentration of Na, K, Mg, Ca, Cl, SO 4 , As, Mn, Cr, Cu, Zn are all below world normal averages in the water but they exceed these world averages in the sediments. HEI, HPI and C d show that the part of the Akuosu - Sukobri tributary at Suame Magazine, Anomagye Township and Bohyen are polluted whilst pollution is minimal at the part of the tributary in the Owabi Forest Reserve as well as the Owabi reservoir. Sediment pollution assessment was carried out using enrichment factor (EF), geoaccumulation index (I geo ) and pollution load index (PLI). EF shows that the sediments are enriched in the heavy metals. The I geo values revealed that the sediments are significantly accumulated with Pb, Cu and Cr whilst the PLI suggest that the sediments are moderately polluted. An integrated approach of pollution indices, principal component analysis (PCA) and cluster analysis (CA) was employed to evaluate the intensity and sources of pollution in the tributary and the reservoir. This showed that the major ions mainly originated from domestic waste whilst the heavy metals come from the various anthropogenic activities along the tributary especially the Suame Magazine part of the Akuosu - Sukobri tributary. Isotope analysis of the water showed that the water is mainly of meteoric origin with very little enrichment probably due to evaporation and mixing along the way before the Akuoso-Sukobri tributary joins the Owabi reservoir. (au)

Sediment budgets of unglaciated alpine catchments - the example of the Johnsbach and Schöttlbach valleys in Styria

Science.gov (United States)

Sass, Oliver; Rascher, Eric; Stangl, Johannes; Lutzmann, Silke

2017-04-01

Extensive research has been performed in glacier forefields and in glaciated catchments in order to predict their future behaviour in a warming climate. However, the majority of medium-scale torrential catchments in the European Alps are non-glaciated and their response to disturbance events (e.g. changing climate) is more subtle and hard to predict. We report from two torrential catchments in the Eastern Alps, the Johnsbach and the Schöttlbach valleys, that have been monitored for several years. The catchments are located in Styria (Austria) and are remarkably similar in terms of size (60-70 km3) and elevation (600/800 - 2400 m). The main difference is the geological setting of the sediment delivering areas which is limestone and brittle dolomite at Johnsbach, and a prominent late-pleistocene valley fill at Schöttlbach, respectively. Slope processes in both areas were monitored by means of repeated TLS surveys of active slope and channel areas and by ALS and/or UAV surveys. Fluvial transport in the main channels was measured using Helly-Smith samplers and recorded continuously by means of new developed, low-budget sediment impact sensors (SIS). In both areas, the catchment output was quantified: by regular surveys of a retention basin at Schöttlbach and by a bedload measurement station (geophone sill) at Johnsbach. The results show that at Johnsbach, the sediment source areas are active tributary trenches in the lower third of the catchment. The sediments derive from brittle dolomite rockwalls and are transported to the main river episodically during rainstorm events. In a 2-yr period, 7400 m3 yr-1 were eroded in the surveyed areas and 9900 m3 yr-1 m3 yr-1 were deposited; of this amount, only a minor portion of 650 m3 yr-1 reached the Johnsbach River. The degree of coupling between tributaries and creek is strongly influenced by anthropogenic measures, e.g. former disturbance by gravel mining and undersized bridge openings. Besides limited bank erosion

Prevalence and distribution of pox-like lesions, avian malaria, and mosquito vectors in Kipahulu valley, Haleakala National Park, Hawai'i, USA

Science.gov (United States)

Aruch, Samuel; Atkinson, Carter T.; Savage, Amy F.; LaPointe, Dennis

2007-01-01

We determined prevalence and altitudinal distribution of introduced avian malarial infections (Plasmodium relictum) and pox-like lesions (Avipoxvirus) in forest birds from Kīpahulu Valley, Haleakalā National Park, on the island of Maui, and we identified primary larval habitat for the mosquito vector of this disease. This intensively managed wilderness area and scientific reserve is one of the most pristine areas of native forest remaining in the state of Hawai‘i, and it will become increasingly important as a site for restoration and recovery of endangered forest birds. Overall prevalence of malarial infections in the valley was 8% (11/133) in native species and 4% (4/101) in nonnative passerines; prevalence was lower than reported for comparable elevations and habitats elsewhere in the state. Infections occurred primarily in ‘Apapane (Himatione sanguinea) and Hawai‘i ‘Amakihi (Hemignathus virens) at elevations below 1,400 m. Pox-like lesions were detected in only two Hawai‘i ‘Amakihi (2%; 2/94) at elevations below 950 m. We did not detect malaria or pox in birds caught at 1,400 m in upper reaches of the valley. Adult mosquitoes (Culex quinquefasciatus) were captured at four sites at elevations of 640, 760, 915, and 975 m, respectively. Culex quinquefasciatus larvae were found only in rock holes along intermittent tributaries of the two largest streams in the valley, but not in standing surface water, pig wallows, ground pools, tree cavities, and tree fern cavities. Mosquito populations in the valley are low, and they are probably influenced by periods of high rainfall that flush stream systems.

Experimentally increased nutrient availability at the permafrost thaw front selectively enhances biomass production of deep-rooting subarctic peatland species

NARCIS (Netherlands)

Keuper, Frida; Dorrepaal, Ellen; van Bodegom, Peter M.; van Logtestijn, Richard; Venhuizen, Gemma; van Hal, Jurgen; Aerts, Rien

2017-01-01

Climate warming increases nitrogen (N) mineralization in superficial soil layers (the dominant rooting zone) of subarctic peatlands. Thawing and subsequent mineralization of permafrost increases plant-available N around the thaw-front. Because plant production in these peatlands is N-limited, such

Recent dynamics of arctic and sub-arctic vegetation

International Nuclear Information System (INIS)

Epstein, Howard E; Myers-Smith, Isla; Walker, Donald A

2013-01-01

We present a focus issue of Environmental Research Letters on the ‘Recent dynamics of arctic and sub-arctic vegetation’. The focus issue includes three perspective articles (Verbyla 2011 Environ. Res. Lett. 6 041003, Williams et al 2011 Environ. Res. Lett. 6 041004, Loranty and Goetz 2012 Environ. Res. Lett. 7 011005) and 22 research articles. The focus issue arose as a result of heightened interest in the response of high-latitude vegetation to natural and anthropogenic changes in climate and disturbance regimes, and the consequences that these vegetation changes might have for northern ecosystems. A special session at the December 2010 American Geophysical Union Meeting on the ‘Greening of the Arctic’ spurred the call for papers. Many of the resulting articles stem from intensive research efforts stimulated by International Polar Year projects and the growing acknowledgment of ongoing climate change impacts in northern terrestrial ecosystems. (synthesis and review)

Tidal and meteorological forcing of sediment transport in tributary mudflat channels.

Science.gov (United States)

Ralston, David K; Stacey, Mark T

2007-06-01

Field observations of flow and sediment transport in a tributary channel through intertidal mudflats indicate that suspended sediment was closely linked to advection and dispersion of a tidal salinity front. During calm weather when tidal forcing was dominant, high concentrations of suspended sediment advected up the mudflat channel in the narrow region between salty water from San Francisco Bay and much fresher runoff from the small local watershed. Salinity and suspended sediment dispersed at similar rates through each tidal inundation, such that during receding ebbs the sediment pulse had spread spatially and maximum concentrations had decreased. Net sediment transport was moderately onshore during the calm weather, as asymmetries in stratification due to tidal straining of the salinity front enhanced deposition, particularly during weaker neap tidal forcing. Sediment transport by tidal forcing was periodically altered by winter storms. During storms, strong winds from the south generated wind waves and temporarily increased suspended sediment concentrations. Increased discharge down the tributary channels due to precipitation had more lasting impact on sediment transport, supplying both buoyancy and fine sediment to the system. Net sediment transport depended on the balance between calm weather tidal forcing and perturbations by episodic storms. Net transport in the tributary channel was generally off-shore during storms and during calm weather spring tides, and on-shore during calm weather neap tides.

Comparative responses of phenology and reproductive development to simulated environmental change in sub-arctic and high arctic plants

Energy Technology Data Exchange (ETDEWEB)

Wookey, P A; Welker, J M; Callaghan, T V [Inst. of Terrestrial Ecology, Merlewood Research Station, Grange-over-Sands, Cumbria (United Kingdom); Parsons, A N; Potter, J A; Lee, J A; Press, M C [Dept. of Environmental Biology, Univ. of Manchester, Manchester (United Kingdom)

1993-01-01

The effects of temperature, precipitation and nutrient perturbations, and their interactions, are being assessed on two contrasting arctic ecosystems to simulate impacts of climate change. One, a high arctic polar semi-desert community, is characterized by a sparse, low and aggregated vegetation cover where plant proliferation is by seedlings, whereas the other, a sub-arctic dwarf shrub health, is characterized by a complete, vegetation cover of erect, clonal dwarf shrubs which spread vegetatively. The developmental processes of seed production were shown to be highly sensitive, even within one growing season to specific environmental perturbations which differed between sites. At the polar semi-desert site, there was a striking effect of the temperature enhancement treatments on phenology and seed-setting of Dryas octopetala ssp. octopetala, with almost no seed-setting occurring in plots experiencing ambient temperatures. By contrast, there were no significant effects of temperature enhancement alone on fruit production of Empetrum hermaphroditum at the sub-Arctic dwarf shrub heath site, although fruit production was significantly influenced by the application of nutrients and/or water. The response of dominant high arctic dwarf shrub to increased temperature suggests that any climate warming may stimulate seed-set. This could be particularly important in the high Arctic where colonization can proceed in areas dominated by bare ground and where genetic recombination may be needed to generate tolerance to predicted changes of great magnitude. In the sub-Arctic, however the closed vegetation is dominated by clonally-proliferating species. Plant fitness will increase here in response to any increased vegetative growth resulting from higher nutrient availability in warmer organic soils. (ua) (59 refs.)

Landscape evolution in south-central Minnesota and the role of geomorphic history on modern erosional processes

Science.gov (United States)

Gran, K.B.; Belmont, P.; Day, S.S.; Finnegan, N.; Jennings, C.; Lauer, J.W.; Wilcock, P.R.

2011-01-01

The Minnesota River Valley was carved during catastrophic drainage of glacial Lake Agassiz at the end of the late Pleistocene. The ensuing base-level drop on tributaries created knickpoints that excavated deep valleys as they migrated upstream. A sediment budget compiled in one of these tributaries, the Le Sueur River, shows that these deep valleys are now the primary source of sediment to the Minnesota River. To compare modern sediment loads with pre-European settlement erosion rates, we analyzed incision history using fluvial terrace ages to constrain a valley incision model. Results indicate that even thoughthe dominant sediment sources are derived from natural sources (bluffs, ravines, and streambanks), erosion rates have increased substantially, due in part to pervasive changes in watershed hydrology.

Northern Great Plains Network water quality monitoring design for tributaries to the Missouri National Recreational River

Science.gov (United States)

Rowe, Barbara L.; Wilson, Stephen K.; Yager, Lisa; Wilson, Marcia H.

2013-01-01

The National Park Service (NPS) organized more than 270 parks with important natural resources into 32 ecoregional networks to conduct Inventory and Monitoring (I&M) activities for assessment of natural resources within park units. The Missouri National Recreational River (NRR) is among the 13 parks in the NPS Northern Great Plain Network (NGPN). Park managers and NGPN staff identified surface water resources as a high priority vital sign to monitor in park units. The objectives for the Missouri NRR water quality sampling design are to (1) assess the current status and long-term trends of select water quality parameters; and (2) document trends in streamflow at high-priority stream systems. Due to the large size of the Missouri River main stem, the NGPN water quality design for the Missouri NRR focuses on wadeable tributaries within the park unit. To correlate with the NGPN water quality protocols, monitoring of the Missouri NRR consists of measurement of field core parameters including dissolved oxygen, pH, specific conductance, and temperature; and streamflow. The purpose of this document is to discuss factors examined for selection of water quality monitoring on segments of the Missouri River tributaries within the Missouri NRR.Awareness of the complex history of the Missouri NRR aids in the current understanding and direction for designing a monitoring plan. Historical and current monitoring data from agencies and entities were examined to assess potential NGPN monitoring sites. In addition, the U.S. Environmental Protection Agency 303(d) list was examined for the impaired segments on tributaries to the Missouri River main stem. Because major tributaries integrate water quality effects from complex combinations of land use and environmental settings within contributing areas, a 20-mile buffer of the Missouri NRR was used to establish environmental settings that may impact the water quality of tributaries that feed the Missouri River main stem. For selection of

Effect of agriculture on water quality of Lake Biwa tributaries, Japan

International Nuclear Information System (INIS)

Nakano, Takanori; Tayasu, Ichiro; Yamada, Yoshihiro; Hosono, Takahiro; Igeta, Akitake; Hyodo, Fujio; Ando, Atsushi; Saitoh, Yu; Tanaka, Takuya; Wada, Eitaro; Yachi, Shigeo

2008-01-01

We investigated the effects of natural environments and human activity on Lake Biwa, central Japan. We determined the concentrations of 19 elements and the compositions of stable S and Sr isotopes in the main tributaries of the lake and compared them with the corresponding values obtained from the lake water during the circulation period. Results of a principal component analysis indicated that the components dissolved in the lower reaches of the tributaries can be divided into group 1 (HCO 3 , SO 4 , NO 3 , Ca, Mg, Sr) and group 2 components (Cl, Br, Na, K, Ba, Rb, Cs). The concentrations of group 1 components were high in the rivers of the southern area, which is urbanized and densely populated, and the eastern area, which consists of plains where agriculture predominates, compared with the rivers of the northern and western areas, which are mostly mountainous and sparsely populated. The concentrations of group 2 components tended to be high in the river water of industrial areas. The δ 34 S values of SO 4 in the river water converged to 0 ± 2 per mille as the SO 4 concentration increased and, excluding the areas where limestone is extensively distributed, as the HCO 3 concentration increased. In particular, both the δ 34 S values (0 ± 2 per mille ) and the 87 Sr/ 86 Sr ratios (0.7117 ± 0.0005) fell within narrow ranges in the small and medium rivers of the eastern plain area, where rice is widely grown. These values agreed respectively with the δ 34 S values of the fertilizers used in the Lake Biwa basin and the soil-exchangeable 87 Sr/ 86 Sr in the eastern plain. The characteristics of water quality in the small and medium rivers of the eastern area can be explained by a model in which sulfuric, nitric, and bicarbonic acids generated by the decomposition of agricultural fertilizer and paddy rice selectively leached out alkaline-earth elements adsorbed on the soil and sediments of the plain or dissolved calcium carbonate enriched with Mg and Sr. Compared

77 FR 33237 - Saline Valley Warm Springs Management Plan/Environmental Impact Statement, Death Valley National...

Science.gov (United States)

2012-06-05

... Valley Warm Springs Management Plan/Environmental Impact Statement, Death Valley National Park, Inyo... an Environmental Impact Statement for the Saline Valley Warm Springs Management Plan, Death Valley... analysis process for the Saline Valley Warm Springs Management Plan for Death Valley [[Page 33238...

Evidences of Seasonal Variation in Altimetry Derived Ocean Tides in the Subarctic Ocean

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Hok Sum Fok

2013-01-01

Full Text Available While the barotropic ocean tides in the deep ocean are well modeled to ~2 cm RMS, accurate tidal prediction in the ice-covered polar oceans and near coastal regions remain elusive. A notable reason is that the most accurate satellite altimeters (TOPEX/Jason-1/-2, whose orbits are optimized to minimize the tidal aliasing effect, have spatial coverage limited to largely outside of the polar ocean. Here, we update the assessment of tidal models using 7 contemporary global and regional models, and show that the altimetry sea surface height (SSH anomaly residual after tidal correction is 9 - 12 cm RMS in the Subarctic Ocean. We then address the hypothesis whether plausible evidence of variable tidal signals exist in the seasonally ice-covered Subarctic Ocean, where the sea ice cover is undergoing rapid thinning. We first found a difference in variance reduction for multi-mission altimeter SSH anomaly residuals during the summer and winter seasons, with the residual during winter season 15 - 30% larger than that during the summer season. Experimental seasonal ocean tide solutions derived from satellite altimetry reveals that the recovered winter and summer tidal constituents generally differ by a few cm in amplitude and tens of degrees in phase. Relatively larger seasonal tidal patterns, in particular for M2, S2 and K1 tides, have been identified in the Chukchi Sea study region near eastern Siberia, coincident with the seasonal presence and movement of sea ice.

Diversity and population structure of Marine Group A bacteria in the Northeast subarctic Pacific Ocean

OpenAIRE

Allers, Elke; Wright, Jody J; Konwar, Kishori M; Howes, Charles G; Beneze, Erica; Hallam, Steven J; Sullivan, Matthew B

2012-01-01

Marine Group A (MGA) is a candidate phylum of Bacteria that is ubiquitous and abundant in the ocean. Despite being prevalent, the structural and functional properties of MGA populations remain poorly constrained. Here, we quantified MGA diversity and population structure in relation to nutrients and O2 concentrations in the oxygen minimum zone (OMZ) of the Northeast subarctic Pacific Ocean using a combination of catalyzed reporter deposition fluorescence in situ hybridization (CARD-FISH) and ...

Importance of Ekman transport and gyre circulation change on seasonal variation of surface dissolved iron in the western subarctic North Pacific

Science.gov (United States)

Nakanowatari, Takuya; Nakamura, Tomohiro; Uchimoto, Keisuke; Nishioka, Jun; Mitsudera, Humio; Wakatsuchi, Masaaki

2017-05-01

Iron (Fe) is an essential nutrient for marine phytoplankton and it constitutes an important element in the marine carbon cycle in the ocean. This study examined the mechanisms controlling seasonal variation of dissolved Fe (dFe) in the western subarctic North Pacific (WSNP), using an ocean general circulation model coupled with a simple biogeochemical model incorporating a dFe cycle fed by two major sources (atmospheric dust and continental shelf sediment). The model reproduced the seasonal cycle of observed concentrations of dFe and macronutrients at the surface in the Oyashio region with maxima in winter (February-March) and minima in summer (July-September), although the simulated seasonal amplitudes are a half of the observed values. Analysis of the mixed-layer dFe budget indicated that both local vertical entrainment and lateral advection are primary contributors to the wintertime increase in dFe concentration. In early winter, strengthened northwesterly winds excite southward Ekman transport and Ekman upwelling over the western subarctic gyre, transporting dFe-rich water southward. In mid to late winter, the southward western boundary current of the subarctic gyre and the outflow from the Sea of Okhotsk also bring dFe-rich water to the Oyashio region. The contribution of atmospheric dust to the dFe budget is several times smaller than these ocean transport processes in winter. These results suggest that the westerly wind-induced Ekman transport and gyre circulation systematically influence the seasonal cycle of WSNP surface dFe concentration.

Seasonal variations in suspended-sediment dynamics in the tidal reach of an estuarine tributary

Science.gov (United States)

Downing-Kunz, Maureen A.; Schoellhamer, David H.

2013-01-01

Quantifying sediment supply from estuarine tributaries is an important component of developing a sediment budget, and common techniques for estimating supply are based on gages located above tidal influence. However, tidal interactions near tributary mouths can affect the magnitude and direction of sediment supply to the open waters of the estuary. We investigated suspended-sediment dynamics in the tidal reach of Corte Madera Creek, an estuarine tributary of San Francisco Bay, using moored acoustic and optical instruments. Flux of both water and suspended-sediment were calculated from observed water velocity and turbidity for two periods in each of wet and dry seasons during 2010. During wet periods, net suspended-sediment flux was seaward; tidally filtered flux was dominated by the advective component. In contrast, during dry periods, net flux was landward; tidally filtered flux was dominated by the dispersive component. The mechanisms generating this landward flux varied; during summer we attributed wind–wave resuspension in the estuary and subsequent transport on flood tides, whereas during autumn we attributed increased spring tide flood velocity magnitude leading to local resuspension. A quadrant analysis similar to that employed in turbulence studies was developed to summarize flux time series by quantifying the relative importance of sediment transport events. These events are categorized by the direction of velocity (flood vs. ebb) and the magnitude of concentration relative to tidally averaged conditions (relatively turbid vs. relatively clear). During wet periods, suspended-sediment flux was greatest in magnitude during relatively turbid ebbs, whereas during dry periods it was greatest in magnitude during relatively turbid floods. A conceptual model was developed to generalize seasonal differences in suspended-sediment dynamics; model application to this study demonstrated the importance of few, relatively large events on net suspended-sediment flux

Concentrations and loads of suspended sediment-associated pesticides in the San Joaquin River, California and tributaries during storm events

Science.gov (United States)

Hladik, M.L.; Domagalski, Joseph L.; Kuivila, K.M.

2009-01-01

Current-use pesticides associated with suspended sediments were measured in the San Joaquin River, California and its tributaries during two storm events in 2008. Nineteen pesticides were detected: eight herbicides, nine insecticides, one fungicide and one insecticide synergist. Concentrations for the herbicides (0.1 to 3000 ng/g; median of 6.1 ng/g) were generally greater than those for the insecticides (0.2 to 51 ng/g; median of 1.5 ng/g). Concentrations in the tributaries were usually greater than in the mainstem San Joaquin River and the west side tributaries were higher than the east side tributaries. Estimated instantaneous loads ranged from 1.3 to 320 g/day for herbicides and 0.03 to 53 g/day for insecticides. The greatest instantaneous loads came from the Merced River on the east side. Instantaneous loads were greater for the first storm of 2008 than the second storm in the tributaries while the instantaneous loads within the San Joaquin River were greater during the second storm. Pesticide detections generally reflected pesticide application, but other factors such as physical-chemical properties and timing of application were also important to pesticide loads.

Quantification and dating of floodplain sedimentation in a medium-sized catchment of the German uplands: a case study from the Aar Valley in the southern Rhenish Massif, Germany

Directory of Open Access Journals (Sweden)

Stolz, Christian

2013-09-01

Full Text Available The distribution, thickness and composition of the floodplain sediments in the valleys of the Aar and its tributaries (Taunus Mountains were investigated by way of extensive fieldwork at 25 locations. In the entire catchment area, 48.8 million tons of loamy f loodplain fines could be assessed. Most of these were deposited since late medieval times due to extensive historical land use and forest clearing, especially in the mining region along the middle course of the Aar. In its lower course, the enhanced sedimentation of loamy f loodplain sediments started during the Bronze Age.

Latest Pleistocene and Holocene glacial events in the Colonia valley, Northern Patagonia Icefield, southern Chile

Science.gov (United States)

Nimick, David A.; Mcgrath, Daniel; Mahan, Shannon; Friesen, Beverly A.; Leidich, Jonathan

2016-01-01

The Northern Patagonia Icefield (NPI) is the primary glaciated terrain worldwide at its latitude (46.5–47.5°S), and constraining its glacial history provides unique information for reconstructing Southern Hemisphere paleoclimate. The Colonia Glacier is the largest outlet glacier draining the eastern NPI. Ages were determined using dendrochronology, lichenometry, radiocarbon, cosmogenic 10Be and optically stimulated luminescence. Dated moraines in the Colonia valley defined advances at 13.2 ± 0.95, 11.0 ± 0.47 and 4.96 ± 0.21 ka, with the last being the first constraint on the onset of Neoglaciation for the eastern NPI from a directly dated landform. Dating in the tributary Cachet valley, which contains an ice-dammed lake during periods of Colonia Glacier expansion, defined an advance at ca. 2.95 ± 0.21 ka, periods of advancement at 810 ± 49 cal a BP and 245 ± 13 cal a BP, and retreat during the intervening periods. Recent Colonia Glacier thinning, which began in the late 1800s, opened a lower-elevation outlet channel for Lago Cachet Dos in ca. 1960. Our data provide the most comprehensive set of Latest Pleistocene and Holocene ages for a single NPI outlet glacier and expand previously developed NPI glacial chronologies.

Use of ground-water reservoirs for storage of surface water in the San Joaquin Valley, California

Science.gov (United States)

Davis, G.H.; Lofgren, B.E.; Mack, Seymour

1964-01-01

occurs in alluvial and lacustrine deposits of late Pliocene age or older; and 3) a body of saline connate water contained in marine sediments of middle Pliocene or older age, which underlies the fresh-water body throughout the area. In much of the eastern part of the valley, especially in the areas of the major streams, the Corcoran clay member is not present and ground water occurs as one fresh-water body to considerable depth. The ground-water body is replenished by infiltration of rainfall, by infiltration from streams, canals, and ditches, by underflow entering the valley from tributary stream canyons, and by infiltration of excess irrigation water. In much of the valley, however, the annual rainfall is so low that little penetrates deeply, and soil-moisture deficiency is perennial. Infiltration from stream channels and canals and from irrigated fields are the principal sources of groundwater recharge. The ground-water storage capacity of the San Joaquin Valley has been estimated in an earlier report (Davis and others, 1959) as 93 million acre-feet. This is the quantity of water that would drain by gravity from the valley deposits if the regional water level were lowered from 10 to 200 feet below the land surface. Storage capacity was estimated for only the part of the valley considered to be potentially usable as a ground-water reservoir. In this study, a 200foot depth was selected as a practical valley-wide depth limit for unwatering under full utilization of the ground-water reservoir, even though in localized areas sections in excess of 350 feet in depth have already been dewatered. Some of the factors that locally limit the utilization of the ground-water reservoir are inferior water quality, relatively impermeable surface soils, and relatively impermeable subsurface deposits. On the basis of a detailed analysis of la peg model, the subsurface geology of the San Joaquin Valley was subdivided into predominantly permeable and impermeable zones in the 1

Habitat relationships and larval drift of native and nonindigenous fishes in neighboring tributaries of a coastal California river

Science.gov (United States)

Bret C. Harvey; Jason L. White; Rodney J. Nakamoto

2002-01-01

Abstract - Motivated by a particular interest in the distribution of the nonindigenous, piscivorous Sacramento pikeminnow, Ptychocheilus grandis, we examined fish-habitat relationships in small tributaries (draining 20-200 km 2 )in the Eel River drainage of northwestern California.We sampled juvenile and adult fish in 15 tributaries in both the summer and...

Paleoproductivity and intermediate-water ventilation in the subarctic Northwest Pacific during the last deglaciation

Science.gov (United States)

Khim, B.; Ikehara, K.; Sagawa, T.; Shibahara, A.; Yamamoto, M.

2010-12-01

Laminated sediments during the last deglaciation in the subarctic North Pacific indicate significant depletion of dissolved oxygen concentration at intermediate water depths. Such a strong oxygen minimum zone results primarily from a combination of high surface water productivity and poor ventilation of intermediate waters. We investigated a variety of paleoclimatic proxies using about 8-m long piston core sediment (GH02-1030; 42o13.770N, 144o12.530E; water depth, 1212 m) obtained from the continental slope off Tokachi (eastern Hokkaido Island), which is the main path of the southwestward Oyashio Current in the subarctic Northwest Pacific. Laminated sediments were identified at the two horizons in the core GH02-1030; the upper one at 11.4-12.2 cal.kyr BP and the lower one at 14.1-14.7 cal.kyr BP, corresponding to Bølling-Allerød (B/A) and Preboreal (PB), respectively. Between these laminated layers, Younger Dryas occurred. Both laminated sediment layers are characterized by Bolivina tumida, B. pacifica, and Buliminella tenuata, indicating dysoxic bottom water conditions. Increased Mg/Ca-derived intermediate-water temperature and δ18OW values at B/A and PB periods suggest the poor ventilation of intermediate water because of the surface water freshening (i.e., decrease of surface-water salinity). UK'37-derived temperature record also supports the increase of surface-water temperature during B/A and PB intervals. During the last deglaciation, short-chain C14-C18 n-fatty acids, derived mainly from marine organisms, showed higher concentrations, indicating the increased surface-water production, and at the same time, abundant lignin reflected more contribution of terrigenous organic matter, supporting increased freshwater discharge. Variation of CaCO3 contents show remarkable double peaks, corresponding to B/A and PB periods, respectively, leading to the increase of TOC contents. Opal contents also follow similar pattern to CaCO3 contents, but are much less than the

Valley polarization in bismuth

Science.gov (United States)

Fauque, Benoit

2013-03-01

The electronic structure of certain crystal lattices can contain multiple degenerate valleys for their charge carriers to occupy. The principal challenge in the development of valleytronics is to lift the valley degeneracy of charge carriers in a controlled way. In bulk semi-metallic bismuth, the Fermi surface includes three cigar-shaped electron valleys lying almost perpendicular to the high symmetry axis known as the trigonal axis. The in-plane mass anisotropy of each valley exceeds 200 as a consequence of Dirac dispersion, which drastically reduces the effective mass along two out of the three orientations. According to our recent study of angle-dependent magnetoresistance in bismuth, a flow of Dirac electrons along the trigonal axis is extremely sensitive to the orientation of in-plane magnetic field. Thus, a rotatable magnetic field can be used as a valley valve to tune the contribution of each valley to the total conductivity. As a consequence of a unique combination of high mobility and extreme mass anisotropy in bismuth, the effect is visible even at room temperature in a magnetic field of 1 T. Thus, a modest magnetic field can be used as a valley valve in bismuth. The results of our recent investigation of angle-dependent magnetoresistance in other semi-metals and doped semiconductors suggest that a rotating magnetic field can behave as a valley valve in a multi-valley system with sizeable mass anisotropy.

Hydraulic and water-quality data collection for the investigation of Great Lakes tributaries for Asian carp spawning and egg-transport suitability

Science.gov (United States)

Murphy, Elizabeth A.; Jackson, P. Ryan

2013-01-01

If the invasive Asian carps (bighead carp Hypophthalmichthys nobilis and silver carp Hypophthalmichthys molitrix) migrate to the Great Lakes, in spite of the efforts to stop their advancement, these species will require the fast-flowing water of the Great Lakes tributaries for spawning and recruitment in order to establish a growing population. Two Lake Michigan tributaries (the Milwaukee and St. Joseph Rivers) and two Lake Erie tributaries (the Maumee and Sandusky Rivers) were investigated to determine if these tributaries possess the hydraulic and water-quality characteristics to allow successful spawning of Asian carps. To examine this issue, standard U.S. Geological Survey sampling protocols and instrumentation for discharge and water-quality measurements were used, together with differential global positioning system data for georeferencing. Non-standard data-processing techniques, combined with detailed laboratory analysis of Asian carp egg characteristics, allowed an assessment of the transport capabilities of each of these four tributaries. This assessment is based solely on analysis of observed data and did not utilize the collected data for detailed transport modeling.

Greening Turner Valley

International Nuclear Information System (INIS)

Byfield, M.

2010-01-01

This article discussed remedial activities undertaken in the Turner Valley. Remedial action in the valley must satisfy the financial concerns of engineers and investors as well as the environmental concerns of residents and regulators. Natural gas production in the Turner Valley began in 1914. The production practices were harmful and wasteful. Soil and water pollution was not considered a problem until recently. The impacts of cumulative effects and other pollution hazards are now being considered as part of many oil and gas environmental management programs. Companies know it is cheaper and safer to prevent pollutants from being released, and more efficient to clean them up quickly. Oil and gas companies are also committed to remediating historical problems. Several factors have simplified remediation plans in the Turner Valley. Area real estate values are now among the highest in Alberta. While the valley residents are generally friendly to the petroleum industry, strong communication with all stakeholders in the region is needed. 1 fig.

Assessment of the pollution in Aghien lagoon and its tributaries ...

African Journals Online (AJOL)

The influence of the pollutants in surface water quality when used for drinking water is of great concern in many developing countries. This study seeks to characterize the types of pollution in Aghien lagoon and its tributaries. For the sampling, water was taken at a depth of 50 cm from the earth surface. Samples were ...

Watershed and discharge influences on the phase distribution and tributary loading of total mercury and methylmercury into Lake Superior

International Nuclear Information System (INIS)

Babiarz, Christopher; Hoffmann, Stephen; Wieben, Ann; Hurley, James; Andren, Anders; Shafer, Martin; Armstrong, David

2012-01-01

Knowledge of the partitioning and sources of mercury are important to understanding the human impact on mercury levels in Lake Superior wildlife. Fluvial fluxes of total mercury (Hg T ) and methylmercury (MeHg) were compared to discharge and partitioning trends in 20 sub-basins having contrasting land uses and geological substrates. The annual tributary yield was correlated with watershed characteristics and scaled up to estimate the basin-wide loading. Tributaries with clay sediments and agricultural land use had the largest daily yields with maxima observed near the peak in water discharge. Roughly 42% of Hg T and 57% of MeHg was delivered in the colloidal phase. Tributary inputs, which are confined to near-shore zones of the lake, may be more important to the food-web than atmospheric sources. The annual basin-wide loading from tributaries was estimated to be 277 kg yr −1 Hg T and 3.4 kg yr −1 MeHg (5.5 and 0.07 mg km −2 d −1 , respectively). - Highlights: ► The highest mercury yields occurred during spring melt except in forested watersheds. ► Roughly half of the mercury yield occurred in the colloidal phase. ► About 277 kg of Hg T and 3.4 kg of MeHg were delivered annually via tributaries. ► Whole-water MeHg loading was roughly equivalent to the estimated atmospheric loading. ► Watersheds with peat, loam or sandy soils deliver more MeHg than those with clays. - Tributary inputs, which are confined to the near-shore zones of Lake Superior, provide more mercury to these sensitive aquatic habitats than direct atmospheric deposition.

Chronostratigraphic study of the Grottaperfetta alluvial valley in the city of Rome (Italy: investigating possible interaction between sedimentary and tectonic processes

Directory of Open Access Journals (Sweden)

G. Di Giulio

2008-06-01

Full Text Available We carried out geomorphologic and geological investigations in a south-eastern tributary valley of the Tiber River in Rome, the Grottaperfetta valley, aimed to reconstruct its buried geometry. Since results of the geomorphologic study evidenced anomalies of the stream beds, we performed geoelectric and boreholes prospecting to check whether recent faulting, rather than an inherited structural control, possibly contributed to the evolution of the alluvial valley. Vertical offsets of the stratigraphic horizons across adjacent boreholes were evidenced within the Late Pleistocene-Holocene alluvium and its substratum. In order to rule out the effects of irregular geometry of the alluvial deposits, we focussed on sectors where vertical offsets affected all the stratigraphic horizons (alluvium and pre-Holocene substratum, showing an increasing displacement with depth. We identified a site where repeated displacements occur coupled with a lateral variation of soil resistivity, and we drilled an oblique borehole aimed to cross and sample the possible fault zone affecting the terrain. A 7 cm thick granular layer, inclined 50°÷70° on the horizontal, was recovered 5 m b.g., and it was interpreted as the filling material of a fracture. The convergence of the reported features with independent evidence from geoelectric and geomorphologic investigations leads to hypothesize the presence of a faulting zone within the Holocene alluvial terrains and to propose the excavation of a trench to verify this hypothesis.

Methanethiol Concentrations and Sea-Air Fluxes in the Subarctic NE Pacific Ocean

Science.gov (United States)

Kiene, R. P.; Williams, T. E.; Esson, K.; Tortell, P. D.; Dacey, J. W. H.

2017-12-01

Exchange of volatile organic sulfur from the ocean to the atmosphere impacts the global sulfur cycle and the climate system and is thought to occur mainly via the gas dimethylsulfide (DMS). DMS is produced during degradation of the abundant phytoplankton osmolyte dimethylsulfoniopropionate (DMSP) but bacteria can also convert dissolved DMSP into the sulfur gas methanethiol (MeSH). MeSH has been difficult to measure in seawater because of its high chemical and biological reactivity and, thus, information on MeSH concentrations, distribution and sea-air fluxes is limited. We measured MeSH in the northeast subarctic Pacific Ocean in July 2016, along transects with strong phytoplankton abundance gradients. Water samples obtained with Niskin bottles were analyzed for MeSH by purge-and-trap gas chromatography. Depth profiles showed that MeSH concentrations were high near the surface and declined with depth. Surface waters (5 m depth) had an average MeSH concentration of 0.75 nM with concentrations reaching up to 3nM. MeSH concentrations were correlated (r = 0.47) with microbial turnover of dissolved DMSP which ranged up to 236 nM per day. MeSH was also correlated with total DMSP (r = 0.93) and dissolved DMS (r = 0.63), supporting the conclusion that DMSP was a major precursor of MeSH. Surface water MeSH:DMS concentration ratios averaged 0.19 and ranged up to 0.50 indicating that MeSH was a significant fraction of the volatile sulfur pool in surface waters. Sea-air fluxes of MeSH averaged 15% of the combined DMS+MeSH flux, therefore MeSH contributed an important fraction of the sulfur emitted to the atmosphere from the subarctic NE Pacific Ocean.

Intra-basin variability of snowmelt water balance calculations in a subarctic catchment

Science.gov (United States)

McCartney, Stephen E.; Carey, Sean K.; Pomeroy, John W.

2006-03-01

The intra-basin variability of snowmelt and melt-water runoff hydrology in an 8 km2 subarctic alpine tundra catchment was examined for the 2003 melt period. The catchment, Granger Creek, is within the Wolf Creek Research Basin, Yukon, which is typical of mountain subarctic landscapes in northwestern Canada. The study catchment was segmented into nine internally uniform zones termed hydrological response units (HRUs) based on their similar hydrological, physiographic, vegetation and soil properties. Snow accumulation exhibited significant variability among the HRUs, with greatest snow water equivalent in areas of tall shrub vegetation. Melt began first on southerly exposures and at lower elevations, yet average melt rates for the study period varied little among HRUs with the exception of those with steep aspects. In HRUs with capping organic soils, melt water first infiltrated this surface horizon, satisfying its storage capacity, and then percolated into the frozen mineral substrate. Infiltration and percolation into frozen mineral soils was restricted where melt occurred rapidly and organic soils were thin; in this case, melt-water delivery rates exceeded the frozen mineral soil infiltration rate, resulting in high runoff rates. In contrast, where there were slower melt rates and thick organic soils, infiltration was unlimited and runoff was suppressed. The snow water equivalent had a large impact on runoff volume, as soil storage capacity was quickly surpassed in areas of deep snow, diverting the bulk of melt water laterally to the drainage network. A spatially distributed water balance indicated that the snowmelt freshet was primarily controlled by areas with tall shrub vegetation that accumulate large quantities of snow and by alpine areas with no capping organic soils. The intra-basin water balance variability has important implications for modelling freshet in hydrological models.

Macroinvertebrate and organic matter export from headwater tributaries of a Central Appalachian stream

Data.gov (United States)

U.S. Environmental Protection Agency — The dataset contains physicochemical and biological data from 12 headwater tributaries of Clemons Fork in Robinson Forest, KY. This dataset is associated with the...

Fecal-indicator bacteria in the Allegheny, Monongahela, and Ohio Rivers and selected tributaries, Allegheny County, Pennsylvania, 2001-2005

Science.gov (United States)

Buckwalter, Theodore F.; Zimmerman, Tammy M.; Fulton, John W.

2006-01-01

Concentrations of fecal-indicator bacteria were determined in 1,027 water-quality samples collected from July 2001 through August 2005 during dry- (72-hour dry antecedent period) and wet-weather (48-hour dry antecedent period and at least 0.3 inch of rain in a 24-hour period) conditions in the Allegheny, Monongahela, and Ohio Rivers (locally referred to as the Three Rivers) and selected tributaries in Allegheny County. Samples were collected at five sampling sites on the Three Rivers and at eight sites on four tributaries to the Three Rivers having combined sewer overflows. Water samples were analyzed for three fecal-indicator organisms fecal coliform, Escherichia coli (E. coli), and enterococci bacteria. Left-bank and right-bank surface-water samples were collected in addition to a cross-section composite sample at each site. Concentrations of fecal coliform, E. coli, and enterococci were detected in 98.6, 98.5, and 87.7 percent of all samples, respectively. The maximum fecal-indicator bacteria concentrations were collected from Sawmill Run, a tributary to the Ohio River; Sawmill Run at Duquesne Heights had concentrations of fecal coliform, E. coli, and enterococci of 410,000, 510,000, and 180,000 col/100 mL, respectively, following a large storm. The samples collected in the Three Rivers and selected tributaries frequently exceeded established recreational standards and criteria for bacteria. Concentrations of fecal coliform exceeded the Pennsylvania water-quality standard (200 col/100 mL) in approximately 63 percent of the samples. Sample concentrations of E. coli and enterococci exceeded the U.S. Environmental Protection Agency (USEPA) water-quality criteria (235 and 61 col/100 mL, respectively) in about 53 and 47 percent, respectively, of the samples. Fecal-indicator bacteria were most strongly correlated with streamflow, specific conductance, and turbidity. These correlations most frequently were observed in samples collected from tributary sites. Fecal

Hydrochemistry of the Mahomet Bedrock Valley Aquifer, East-Central Illinois: indicators of recharge and ground-water flow

Science.gov (United States)

Panno, S.V.; Hackley, Keith C.; Cartwright, K.; Liu, Chao-Li

1994-01-01

A conceptual model of the ground-water flow and recharge to the Mahomet Bedrock Valley Aquifer (MVA), east-central Illinois, was developed using major ion chemistry and isotope geochemistry. The MVA is a 'basal' fill in the east-west trending buried bedrock valley composed of clean, permeable sand and gravel to thicknesses of up to 61 m. It is covered by a thick sequence of glacial till containing thinner bodies of interbedded sand and gravel. Ground water from the MVA was found to be characterized by clearly defined geochemical regions with three distinct ground-water types. A fourth ground-water type was found at the confluence of the MVA and the Mackinaw Bedrock Valley Aquifer (MAK) to the west. Ground water in the Onarga Valley, a northeastern tributary of the MVA, is of two types, a mixed cation-SO42- type and a mixed cation-HCO3- type. The ground water is enriched in Na+, Ca2+, Mg2+, and SO42- which appears to be the result of an upward hydraulic gradient and interaction of deeper ground water with oxidized pyritic coals and shale. We suggest that recharge to the Onarga Valley and overlying aquifers is 100% from bedrock (leakage) and lateral flow from the MVA to the south. The central MVA (south of the Onarga Valley) is composed of relatively dilute ground water of a mixed cation-HCO3- type, with low total dissolved solids, and very low concentrations of Cl- and SO42-. Stratigraphic relationships of overlying aquifers and ground-water chemistry of these and the MVA suggest recharge to this region of the MVA (predominantly in Champaign County) is relatively rapid and primarily from the surface. Midway along the westerly flow path of the MVA (western MVA), ground water is a mixed cation-HCO3- type with relatively high Cl-, where Cl- increases abruptly by one to ??? two orders of magnitude. Data suggest that the increase in Cl- is the result of leakage of saline ground water from bedrock into the MVA. Mass-balance calculations indicate that approximately 9.5% of

Water quality in Italy: Po River and its tributaries

International Nuclear Information System (INIS)

Crosa, G.; Marchetti, R.

1993-01-01

For Italy's Po River hydrological basin, artificial reservoirs have a great importance; water reserve is about 1600 million cubic meters for the hydroelectric reservoirs and about 76 million cubic meters for irrigation. The principal factors determining the water quality of the Po River and its tributaries are examined. Organic micropollutants, metals and the microbial load are the principal parameters altering the quality of the waters; dilution is the prevailing factor reducing this contamination

33 CFR 334.450 - Cape Fear River and tributaries at Sunny Point Army Terminal, Brunswick County, N.C.; restricted...

Science.gov (United States)

2010-07-01

... 33 Navigation and Navigable Waters 3 2010-07-01 2010-07-01 false Cape Fear River and tributaries... AND RESTRICTED AREA REGULATIONS § 334.450 Cape Fear River and tributaries at Sunny Point Army Terminal, Brunswick County, N.C.; restricted area. (a) The area. That portion of Cape Fear River due west of the main...

Modeling the Influence of Variable Tributary Inflow on Circulation and Contaminant Transport in a Water Supply Reservoir

Science.gov (United States)

Nguyen, L. H.; Wildman, R.

2012-12-01

This study characterizes quantitatively the flow and mixing regimes of a water supply reservoir, while also conducting numerical tracer experiments on different operation scenarios. We investigate the effects of weather events on water quality via storm water inflows. Our study site the Kensico Reservoir, New York, the penultimate reservoir of New York City's water supply, is never filtered and thus dependent on stringent watershed protection. This reservoir must meet federal drinking water standards under changing conditions such as increased suburban, commercial, and highway developments that are much higher than the rest of the watershed. Impacts from these sources on water quality are magnified by minor tributary flows subject to contaminants from development projects as other tributaries providing >99% of water to this reservoir are exceedingly clean due to management practices upstream. These threats, coupled with possible changes in the frequency/intensity of weather events due to climate change, increase the potential for contaminants to enter the reservoir and drinking water intakes. This situation provides us with the unique ability to study the effects of weather events on water quality via insignificant storm water inflows, without influence from the major tributaries due to their pristine water quality characteristics. The concentration of contaminants at the drinking water intake depends partially on transport from their point of entry in the reservoir. Thus, it is crucial to understand water circulation in this reservoir and to estimate residence times and water ages at different locations and under different hydrologic scenarios. We described water age, residence time, thermal structure, and flow dynamics of tributary plumes in Kensico Reservoir during a 22-year simulation period using a two-dimensional hydrodynamic and water quality model (CE-QUAL-W2). Our estimates of water age can reach a maximum of ~300 days in deep-reservoir-cells, with

Concentration, flux, and trend estimates with uncertainty for nutrients, chloride, and total suspended solids in tributaries of Lake Champlain, 1990–2014

Science.gov (United States)

Medalie, Laura

2016-12-20

The U.S. Geological Survey, in cooperation with the New England Interstate Water Pollution Control Commission and the Vermont Department of Environmental Conservation, estimated daily and 9-month concentrations and fluxes of total and dissolved phosphorus, total nitrogen, chloride, and total suspended solids from 1990 (or first available date) through 2014 for 18 tributaries of Lake Champlain. Estimates of concentration and flux, provided separately in Medalie (2016), were made by using the Weighted Regressions on Time, Discharge, and Season (WRTDS) regression model and update previously published WRTDS model results with recent data. Assessment of progress towards meeting phosphorus-reduction goals outlined in the Lake Champlain management plan relies on annual estimates of phosphorus flux. The percent change in annual concentration and flux is provided for two time periods. The R package EGRETci was used to estimate the uncertainty of the trend estimate. Differences in model specification and function between this study and previous studies that used WRTDS to estimate concentration and flux using data from Lake Champlain tributaries are described. Winter data were too sparse and nonrepresentative to use for estimates of concentration and flux but were sufficient for estimating the percentage of total annual flux over the period of record. Median winter-to-annual fractions ranged between 21 percent for total suspended solids and 27 percent for dissolved phosphorus. The winter contribution was largest for all constituents from the Mettawee River and smallest from the Ausable River. For the full record (1991 through 2014 for total and dissolved phosphorus and chloride and 1993 through 2014 for nitrogen and total suspended solids), 6 tributaries had decreasing trends in concentrations of total phosphorus, and 12 had increasing trends; concentrations of dissolved phosphorus decreased in 6 and increased in 8 tributaries; fluxes of total phosphorus decreased in 5 and

Relative importance of plant uptake and plant associated denitrification for removal of nitrogen from mine drainage in sub-arctic wetlands.

Science.gov (United States)

Hallin, Sara; Hellman, Maria; Choudhury, Maidul I; Ecke, Frauke

2015-11-15

Reactive nitrogen (N) species released from undetonated ammonium-nitrate based explosives used in mining or other blasting operations are an emerging environmental problem. Wetlands are frequently used to treat N-contaminated water in temperate climate, but knowledge on plant-microbial interactions and treatment potential in sub-arctic wetlands is limited. Here, we compare the relative importance of plant uptake and denitrification among five plant species commonly occurring in sub-arctic wetlands for removal of N in nitrate-rich mine drainage in northern Sweden. Nitrogen uptake and plant associated potential denitrification activity and genetic potential for denitrification based on quantitative PCR of the denitrification genes nirS, nirK, nosZI and nosZII were determined in plants growing both in situ and cultivated in a growth chamber. The growth chamber and in situ studies generated similar results, suggesting high relevance and applicability of results from growth chamber experiments. We identified denitrification as the dominating pathway for N-removal and abundances of denitrification genes were strong indicators of plant associated denitrification activity. The magnitude and direction of the effect differed among the plant species, with the aquatic moss Drepanocladus fluitans showing exceptionally high ratios between denitrification and uptake rates, compared to the other species. However, to acquire realistic estimates of N-removal potential of specific wetlands and their associated plant species, the total plant biomass needs to be considered. The species-specific plant N-uptake and abundance of denitrification genes on the root or plant surfaces were affected by the presence of other plant species, which show that both multi- and inter-trophic interactions are occurring. Future studies on N-removal potential of wetland plant species should consider how to best exploit these interactions in sub-arctic wetlands. Copyright © 2015 Elsevier Ltd. All rights

Design of a sediment-monitoring gaging network on ephemeral tributaries of the Colorado River in Glen, Marble, and Grand Canyons, Arizona

Science.gov (United States)

Griffiths, Ronald E.; Topping, David J.; Anderson, Robert S.; Hancock, Gregory S.; Melis, Theodore S.

2014-01-01

Management of sediment in rivers downstream from dams requires knowledge of both the sediment supply and downstream sediment transport. In some dam-regulated rivers, the amount of sediment supplied by easily measured major tributaries may overwhelm the amount of sediment supplied by the more difficult to measure lesser tributaries. In this first class of rivers, managers need only know the amount of sediment supplied by these major tributaries. However, in other regulated rivers, the cumulative amount of sediment supplied by the lesser tributaries may approach the total supplied by the major tributaries. The Colorado River downstream from Glen Canyon has been hypothesized to be one such river. If this is correct, then management of sediment in the Colorado River in the part of Glen Canyon National Recreation Area downstream from the dam and in Grand Canyon National Park may require knowledge of the sediment supply from all tributaries. Although two major tributaries, the Paria and Little Colorado Rivers, are well documented as the largest two suppliers of sediment to the Colorado River downstream from Glen Canyon Dam, the contributions of sediment supplied by the ephemeral lesser tributaries of the Colorado River in the lowermost Glen Canyon, and Marble and Grand Canyons are much less constrained. Previous studies have estimated amounts of sediment supplied by these tributaries ranging from very little to almost as much as the amount supplied by the Paria River. Because none of these previous studies relied on direct measurement of sediment transport in any of the ephemeral tributaries in Glen, Marble, or Grand Canyons, there may be significant errors in the magnitudes of sediment supplies estimated during these studies. To reduce the uncertainty in the sediment supply by better constraining the sediment yield of the ephemeral lesser tributaries, the U.S. Geological Survey Grand Canyon Monitoring and Research Center established eight sediment-monitoring gaging

Ecohydrological Controls on Intra-Basin Alpine Subarctic Water Balances

Science.gov (United States)

Carey, S. K.; Ziegler, C. M.

2007-12-01

In the mountainous Canadian subarctic, elevation gradients control the disposition of vegetation, permafrost, and characteristics of the soil profile. How intra-basin ecosystems combine to control catchment-scale water and biogeochimcal cycling is uncertain. To this end, a multi-year ecohydrological investigation was undertaken in Granger Basin (GB), a 7.6 km2 sub-basin of the Wolf Creek Research Basin, Yukon Territory, Canada. GB was divided into four sub-basins based on the dominant vegetation and permafrost status, and the timing and magnitude of hydrological processes were compared using hydrometric and hydrochemical methods. Vegetation plays an important role in end-of-winter snow accumulation as snow redistribution by wind is controlled by roughness length. In sub-basins of GB with tall shrubs, snow accumulation is enhanced compared with areas of short shrubs and tundra vegetation. The timing of melt was staggered with elevation, although melt-rates were similar among the sub-basins. Runoff was enhanced at the expense of infiltration in tall shrub areas due to high snow water equivalent and antecedent soil moisture. In the high-elevation tundra sub-basin, thin soils with cold ground temperatures resulted in increased surface runoff. For the freshet period, the lower and upper sub-basins accounted for 81 % of runoff while accounting for 58 % of the total basin area. Two-component isotopic hydrograph separation revealed that during melt, pre-event water dominated in all sub-basins, yet those with greater permafrost disposition and taller shrubs had increased event-water. Dissolved organic carbon (DOC) spiked prior to peak freshet in each sub-basin except for the highest with thin soils, and was associated with flushing of surficial organic soils. For the post-melt period, all sub-basins have similar runoff contributions. Solute and stable isotope data indicate that in sub-basins dominated by permafrost, supra-permafrost runoff pathways predominate as flow

Valley-filtered edge states and quantum valley Hall effect in gated bilayer graphene.

Science.gov (United States)

Zhang, Xu-Long; Xu, Lei; Zhang, Jun

2017-05-10

Electron edge states in gated bilayer graphene in the quantum valley Hall (QVH) effect regime can carry both charge and valley currents. We show that an interlayer potential splits the zero-energy level and opens a bulk gap, yielding counter-propagating edge modes with different valleys. A rich variety of valley current states can be obtained by tuning the applied boundary potential and lead to the QVH effect, as well as to the unbalanced QVH effect. A method to individually manipulate the edge states by the boundary potentials is proposed.

Fluxes of Methane and Carbon Dioxide from a Subarctic Lake

DEFF Research Database (Denmark)

Jammet, Mathilde Manon

) and carbon dioxide (CO2) with the atmosphere. Yet uncertainties in the magnitude and drivers of these fluxes remain, partly due to a lack of direct observations covering all seasons of the year, but also because of the diversity in measurement methods that often miss components of the transport processes......Ongoing climate warming is expected to affect the carbon functioning of subarctic ecosystems. Lakes and wetlands, which are common ecosystems of the high northern latitudes, are of utmost interest in this context because they exchange large amounts of the climate-forcing gases methane (CH4......-out and the release of CH4 and CO2 was established. These results underline the crucial importance of shoulder seasons in the annual carbon emissions from seasonally frozen lakes. Overall, the lake was an important annual source of carbon to the atmosphere, partially compensating the higher, annual sink function...

Spawning and nursery habitats of neotropical fish species in the tributaries of a regulated river

Science.gov (United States)

Makrakis, Maristela Cavicchioli; da Silva, Patrícia S.; Makrakis, Sergio; de Lima, Ariane F.; de Assumpção, Lucileine; de Paula, Salete; Miranda, Leandro E.; Dias, João Henrique Pinheiro

2012-01-01

This chapter provides information on ontogenetic patterns of neotropical fish species distribution in tributaries (Verde, Pardo, Anhanduí, and Aguapeí rivers) of the Porto Primavera Reservoir, in the heavily dammed Paraná River, Brazil, identifying key spawning and nursery habitats. Samplings were conducted monthly in the main channel of rivers and in marginal lagoons from October through March during three consecutive spawning seasons in 2007-2010. Most species spawn in December especially in Verde River. Main river channels are spawning habitats and marginal lagoons are nursery areas for most fish, mainly for migratory species. The tributaries have high diversity of larvae species: a total of 56 taxa representing 21 families, dominated by Characidae. Sedentary species without parental care are more abundant (45.7%), and many long-distance migratory fish species are present (17.4%). Migrators included Prochilodus lineatus, Rhaphiodon vulpinus, Hemisorubim platyrhynchos, Pimelodus maculatus, Pseudoplatystoma corruscans, Sorubim lima, two threatened migratory species: Salminus brasiliensis and Zungaro jahu, and one endangered migratory species: Brycon orbignyanus. Most of these migratory species are vital to commercial and recreational fishing, and their stocks have decreased drastically in the last decades, attributed to habitat alteration, especially impoundments. The fish ladder at Porto Primavera Dam appears to be playing an important role in re-establishing longitudinal connectivity among critical habitats, allowing ascent to migratory fish species, and thus access to upstream reaches and tributaries. Establishment of Permanent Conservation Units in tributaries can help preserve habitats identified as essential spawning and nursery areas, and can be key to the maintenance and conservation of the fish species in the Paraná River basin.

Willamette Valley Ecoregion: Chapter 3 in Status and trends of land change in the Western United States--1973 to 2000

Science.gov (United States)

Wilson, Tamara S.; Sorenson, Daniel G.

2012-01-01

The Willamette Valley Ecoregion (as defined by Omernik, 1987; U.S. Environmental Protection Agency, 1997) covers approximately 14,458 km² (5,582 mi2), making it one of the smallest ecoregions in the conterminous United States. The long, alluvial Willamette Valley, which stretches north to south more than 193 km and ranges from 32 to 64 km wide, is nestled between the sedimentary and metamorphic Coast Ranges (Coast Range Ecoregion) to the west and the basaltic Cascade Range (Cascades Ecoregion) to the east (fig. 1). The Lewis and Columbia Rivers converge at the ecoregion’s northern boundary in Washington state; however, the majority of the ecoregion falls within northwestern Oregon. Interstate 5 runs the length of the valley to its southern boundary with the Klamath Mountains Ecoregion. Topography here is relatively flat, with elevations ranging from sea level to 122 m. This even terrain, coupled with mild, wet winters, warm, dry summers, and nutrient-rich soil, makes the Willamette Valley the most important agricultural region in Oregon. Population centers are concentrated along the valley floor. According to estimates from the Oregon Department of Fish and Wildlife (2006), over 2.3 million people lived in Willamette Valley in 2000. Portland, Oregon, is the largest city, with 529,121 residents (U.S. Census Bureau, 2000). Other sizable cities include Eugene, Oregon; Salem (Oregon’s state capital); and Vancouver, Washington. Despite the large urban areas dotting the length of the Willamette Valley Ecoregion, agriculture and forestry products are its economic foundation (figs. 2,3). The valley is a major producer of grass seed, ornamental plants, fruits, nuts, vegetables, and grains, as well as poultry, beef, and dairy products. The forestry and logging industries also are primary employers of the valley’s rural residents (Rooney, 2008). These activities have affected the watershed significantly, with forestry and agricultural runoff contributing to river

Distribution of agrochemicals in the lower Mississippi River and its tributaries

Science.gov (United States)

Pereira, W.E.; Rostad, C.E.; Leiker, T.J.

1990-01-01

The Mississippi River and its tributaries drain extensive agricultural regions of the Mid-Continental United States. Millions of pounds of herbicides are applied annually in these areas to improve crop yields. Many of these compounds are transported into the river from point and nonpoint sources, and eventually are discharged into the Gulf of Mexico. Studies being conducted by the U.S. Geological Survey along the lower Mississippi River and its major tributaries, representing a 2000 km river reach, have confirmed that several triazine and acetanilide herbicides and their degradation products are ubiquitous in this riverine system. These compounds include atrazine and its degradation products desethyl and desisopropylatrazine, cyanazine, simazine, metolachlor, and alachlor and its degradation products 2-chloro-2',6'-diethylacetanilide, 2-hydroxy-2',6-diethylacetanilide and 2,6-diethylaniline. Loads of these compounds were determined at 16 different sampling stations. Stream-load calculations provided information concerning (a) conservative or nonconservative behavior of herbicides; (b) point sources or nonpoint sources; (c) validation of sampling techniques; and (d) transport past each sampling station.

The influence of tributary flow density differences on the hydrodynamic behavior of a confluent meander bend and implications for flow mixing

Science.gov (United States)

Herrero, Horacio S.; Díaz Lozada, José M.; García, Carlos M.; Szupiany, Ricardo N.; Best, Jim; Pagot, Mariana

2018-03-01

The goal of this study is to evaluate the influence of tributary flow density differences on hydrodynamics and mixing at a confluent meander bend. A detailed field characterization is performed using an Acoustic Doppler Current Profiler (ADCP) for quantification of the 3D flow field, flow discharge and bathymetry, as well as CTD measurements (conductivity, temperature, depth) to characterize the patterns of mixing. Satellite images of the confluence taken at complementary times to the field surveys were analyzed to evaluate the confluence hydrodynamics at different flow conditions. The results illustrate the differences in hydrodynamics and mixing length in relation to confluences with equal density tributaries. At low-density differences, and higher discharge ratio (Qr) between the two rivers, the flow is similar to equi-density confluent meander bends. In contrast, at high-density differences (low Qr), the tributary flow is confined to near the confluence but the density difference causes the flow to move across channel. In this case, the density difference causes the lateral spread of the tributary flow to be greater than at a greater Qr when the density difference is less. These results illustrate the potential importance of density differences between tributaries in determining the rate and spatial extent of mixing and sediment dispersal at confluent meander bends.

Valley development on Hawaiian volcanoes

International Nuclear Information System (INIS)

Baker, V.R.; Gulick, V.C.

1987-01-01

Work in progress on Hawaiian drainage evolution indicates an important potential for understanding drainage development on Mars. Similar to Mars, the Hawaiian valleys were initiated by surface runoff, subsequently enlarged by groundwater sapping, and eventually stabilized as aquifers were depleted. Quantitative geomorphic measurements were used to evaluate the following factors in Hawaiian drainage evolution: climate, stream processes, and time. In comparing regions of similar climate, drainage density shows a general increase with the age of the volcani island. With age and climate held constant, sapping dominated valleys, in contrast to runoff-dominated valleys, display the following: lower drainage densities, higher ratios of valley floor width to valley height, and more positive profile concavities. Studies of stream junction angles indicate increasing junction angles with time on the drier leeward sides of the major islands. The quantitative geomorphic studies and earlier field work yielded important insights for Martian geomorphology. The importance of ash mantling in controlling infiltration on Hawaii also seems to apply to Mars. The Hawaiian valley also have implications for the valley networks of Martian heavily cratered terrains

Main tributary influence on the River Vardar water quantity

International Nuclear Information System (INIS)

Unevska, Blaga; Stojov, Vasko; Milevski, Josif

2004-01-01

Hydrology in all catchments is defined like complex of geophysics and hydro-geologic parameters. Regular defining on the hydrological parameters is essential for planning, improving and developing management on every country. The main aim of this topic is to demonstrate disparity disposal on water resources in Republic of Macedonia depending on the different catchments areas. Here will be talk about different percentage of tributaries, which have influence on river Vardar. River Vardar is main recipient on water in Macedonia.(Author)

Results of the flowmeter-injection test in the Long Valley Exploratory Well (Phase II), Long Valley, California

Science.gov (United States)

Morin, R.H.; Sorey, M.L.; Jacobson, R.D.

1993-01-01

Bayboro Harbor and the Port of St. Petersburg, Florida, form a manmade basin adjacent to Tampa Bay that may supply turbid water to the bay and subsequently affect light penetration in water in the bay. To address concerns about the nature and extent of this potential problem, resuspension of bottom sediments, sedimentation, and tributary storm discharge in the basin were studied. Study results indicated that tidal currents, wind waves, and seiche motions do not resuspend bottom sediments. The maneuvering of a cruise ship in the port resuspended bottom sediments, but these sediments settled within 2 hours. Tidal currents and wave action were not large enough o prevent the resuspended sediments from settling in the basin. Analysis of bathymetric surveys of the port made in 1981, 1986, 1987, and 1989 indicates that the cruise ship has deepened the port along its route and that the displaced sediment has been deposited elsewhere within the port. The storm discharge from two tributaries and the effect of tributary storm runoff on the water quality of the harbor were studied during a storm on November 9, 1989. Booker Creek, which drains an urban watershed, was stratified with a thin layer of turbid freshwater flowing into the harbor over a layer of less turbid saltwater. Salt Creek, which primarily drains Lake Maggiore, was only partially stratified and was less turbid. The turbid water from the creeks increased the turbidity only slightly in the harbor, probably because of mixing with less turbid water and particle settling. Thus, the basin provides mixing and settling, which diminish and eliminate the potentially adverse effect on Tampa Bay from tributary storm runoff and large vessel traffic in the basin.

Experimentally increased nutrient availability at the permafrost thaw front selectively enhances biomass production of deep-rooting subarctic peatland species.

Science.gov (United States)

Keuper, Frida; Dorrepaal, Ellen; van Bodegom, Peter M; van Logtestijn, Richard; Venhuizen, Gemma; van Hal, Jurgen; Aerts, Rien

2017-10-01

Climate warming increases nitrogen (N) mineralization in superficial soil layers (the dominant rooting zone) of subarctic peatlands. Thawing and subsequent mineralization of permafrost increases plant-available N around the thaw-front. Because plant production in these peatlands is N-limited, such changes may substantially affect net primary production and species composition. We aimed to identify the potential impact of increased N-availability due to permafrost thawing on subarctic peatland plant production and species performance, relative to the impact of increased N-availability in superficial organic layers. Therefore, we investigated whether plant roots are present at the thaw-front (45 cm depth) and whether N-uptake ( 15 N-tracer) at the thaw-front occurs during maximum thaw-depth, coinciding with the end of the growing season. Moreover, we performed a unique 3-year belowground fertilization experiment with fully factorial combinations of deep- (thaw-front) and shallow-fertilization (10 cm depth) and controls. We found that certain species are present with roots at the thaw-front (Rubus chamaemorus) and have the capacity (R. chamaemorus, Eriophorum vaginatum) for N-uptake from the thaw-front between autumn and spring when aboveground tissue is largely senescent. In response to 3-year shallow-belowground fertilization (S) both shallow- (Empetrum hermaphroditum) and deep-rooting species increased aboveground biomass and N-content, but only deep-rooting species responded positively to enhanced nutrient supply at the thaw-front (D). Moreover, the effects of shallow-fertilization and thaw-front fertilization on aboveground biomass production of the deep-rooting species were similar in magnitude (S: 71%; D: 111% increase compared to control) and additive (S + D: 181% increase). Our results show that plant-available N released from thawing permafrost can form a thus far overlooked additional N-source for deep-rooting subarctic plant species and increase their

Understanding erosion rates in the Himalayan orogen: A case study from the Arun Valley

Science.gov (United States)

Olen, Stephanie M.; Bookhagen, Bodo; Hoffmann, Bernd; Sachse, Dirk; Adhikari, D. P.; Strecker, Manfred R.

2015-10-01

Understanding the rates and pattern of erosion is a key aspect of deciphering the impacts of climate and tectonics on landscape evolution. Denudation rates derived from terrestrial cosmogenic nuclides (TCNs) are commonly used to quantify erosion and bridge tectonic (Myr) and climatic (up to several kiloyears) time scales. However, how the processes of erosion in active orogens are ultimately reflected in 10Be TCN samples remains a topic of discussion. We investigate this problem in the Arun Valley of eastern Nepal with 34 new 10Be-derived catchment-mean denudation rates. The Arun Valley is characterized by steep north-south gradients in topography and climate. Locally, denudation rates increase northward, from <0.2 mm yr-1 to ~1.5 mm yr-1 in tributary samples, while main stem samples appear to increase downstream from ~0.2 mm yr-1 at the border with Tibet to 0.91 mm yr-1 in the foreland. Denudation rates most strongly correlate with normalized channel steepness (R2 = 0.67), which has been commonly interpreted to indicate tectonic activity. Significant downstream decrease of 10Be concentration in the main stem Arun suggests that upstream sediment grains are fining to the point that they are operationally excluded from the processed sample. This results in 10Be concentrations and denudation rates that do not uniformly represent the upstream catchment area. We observe strong impacts on 10Be concentrations from local, nonfluvial geomorphic processes, such as glaciation and landsliding coinciding with areas of peak rainfall rates, pointing toward climatic modulation of predominantly tectonically driven denudation rates.

Mercury and Methylmercury Related to Historical Mercury Mining in Three Major Tributaries to Lake Berryessa, Upper Putah Creek Watershed, California

Science.gov (United States)

Sparks, G. C.; Alpers, C. N.; Horner, T. C.; Cornwell, K.; Izzo, V.

2016-12-01

The relative contributions of total mercury (THg) and methylmercury (MeHg) from upstream historical mercury (Hg) mining districts were examined in the three largest tributaries to Lake Berryessa, a reservoir with water quality impaired by Hg. A fish consumption advisory has been issued for the reservoir; also, in a study of piscivorous birds at 25 California reservoirs, blood samples from Lake Berryessa grebes had the highest THg concentration state-wide. The third and fourth largest historical Hg-producing mining districts in California are within the study area. These mining districts are located within the Pope Creek, Upper Putah Creek, and Knoxville-Eticuera Creeks watersheds. Downstream of the reservoir, Lower Putah Creek drains into the Yolo Bypass, a major source of THg and MeHg to the Sacramento-San Joaquin Delta. Study objectives included: (1) determining if tributaries downstream of historical Hg mining districts and draining to the reservoir are continuing sources of THg and MeHg; (2) characterizing variability of water and streambed sediment parameters in upstream and downstream reaches of each creek; and (3) estimating loads of suspended sediment, THg, and MeHg entering the reservoir from each tributary. Water samples were collected from October 2012 to September 2014 during non-storm and storm events along each tributary and analyzed for general water quality field parameters; unfiltered THg and MeHg; total suspended solids; and total particulate matter. Discharge measurements were made at the time of sample collection; flow and concentration data were combined to compute daily loads. To determine spatial variability, 135 streambed sediment samples were analyzed for THg, organic content (loss on ignition), and grain-size distribution. All three tributaries contribute THg and MeHg to the reservoir. Some consistent spatial trends in THg (water) concentrations were observed over multiple sampling events; THg (water) decreased from upstream to downstream

Alternative technologies for remediation of technogenic barrens in the Kola Subarctic

Science.gov (United States)

Koptsik, G. N.; Koptsik, S. V.; Smirnova, I. E.

2016-11-01

The efficiency of remediation of technogenic barrens under the reduction of air pollutant emissions from the Severonikel smelter in the Kola Subarctic is determined largely by the soil state and the technology applied. The covering of the contaminated soils with artificially made material based on organomineral substrates and the following liming and fertilization promoted a sharp and long-term reduction of acidity, decrease in the biological availability of heavy metals, increase in the supply with nutrients, and improvement of the life state of willow and birch plantations. The effect of economically more profitable chemo-phytostabilization is short-term; it requires constant maintenance. Under the current production and a high level of soil contamination, repeated measures are required to optimize the soil reaction, supply with nutrients, and to correct the availability of heavy metals in the soils based on the results of continuous monitoring

UDASH – Unified Database for Arctic and Subarctic Hydrography

Directory of Open Access Journals (Sweden)

A. Behrendt

2018-06-01

Full Text Available UDASH (Unified Database for Arctic and Subarctic Hydrography is a unified and high-quality temperature and salinity data set for the Arctic Ocean and the subpolar seas north of 65° N for the period 1980–2015. The archive aims at including all publicly available data and so far consists of 288 532 oceanographic profiles measured mainly with conductivity–temperature–depth (CTD probes, bottles, mechanical thermographs and expendable thermographs. The data were collected by ships, ice-tethered profilers, profiling floats and other platforms. To achieve a uniform quality level, suitable for a wide range of oceanographic analyses, approximately 74 million single measurements of temperature and salinity were thoroughly quality checked. A large number of duplicate and erroneous profiles were detected and not included in the archive. Data outliers were flagged for quick identification. The final archive provides a unique and simple way of accessing most of the available temperature and salinity data for the Arctic Ocean and can be downloaded from https://doi.pangaea.de/10.1594/PANGAEA.872931.

Radioecology of tritiated water in subarctic soils and vegetation

International Nuclear Information System (INIS)

Salonen, L.; Miettinen, J.K.

1982-01-01

The residence times of tritium in various types of soils and plants have been determined in southern and northern Finland. The experiments were conducted in forest and agricultural environments where tritiated water was applied to the soil surface in the form of a single fall of rain. After that the movement and loss of tritiated water from the unsaturated zone was followed over a 2-4-year period in some forest areas. Uptake and loss of tritium in the tissue-free water and organic compounds of some native plants was studied in each area. The results indicated that in the subarctic area the half-residence times of tritium in soils and plants were greatly dependent on the climatic conditions at the time of the labelling and during the short growing seasons and also on the rate of water movement in the soil. In the experiments started during the best growing season the half-residence times in soil and plants do not differ from those determined in more temperate latitudes. (author)

Effects of a controlled under-ice oil spill on invertebrates of an arctic and a subarctic stream

Energy Technology Data Exchange (ETDEWEB)

Miller, M.C.; Stout, J.R.; Alexander, V.

1986-01-01

The short-term drift of macroinvertebrates is documented following two controlled oil spills placed under ice in an arctic (Imnavait Creek) and subarctic (Poker-Caribou Creek) stream just as ice covered the water in early winter. No mortality was observed, but several species responded by differentially drifting from the oil-impacted areas during the following days. In the arctic stream, Trichotanypus posticalis (Diptera) showed a significant increase in drift for the first few days. There was also an overall increase in drift of total organisms post spill. Phaenospectra sp. 1, the numerical dominant, decreased its nocturnal drifting compared with the upstream control station in the 5 days post spill. In the subarctic stream, Skwala sp. 1 (Plecoptera), Prosimulium sp. 1 (Simulidae) and Pseudodiamesa sp. 1 showed significant increase din drift post spill. Among the species of benthic invertebrates sampled with a Hess sampler (WILDCO, Saginaw, Mich.), only the density of Nemoura sp. 1 declined significantly post spill. Polar ordinations using percent difference showed that the oil-treated stations separated from the control stations in both the drift and the Hess bottom samples. Colonization of artificial substrates in Imnavait Creek during the winter following the spill was almost non-existent. In Poker-Caribou Creek much colonization took place over the winter with significantly more occurring on unoiled rocks as compared with oiled rocks.

Transformation of leaf litter by insect herbivory in the Subarctic: Consequences for soil biogeochemistry under global change

Science.gov (United States)

Kristensen, J. A.; Metcalfe, D. B.; Rousk, J.

2017-12-01

Climate warming may increase insect herbivore ranges and outbreak intensities in arctic ecosystems. Thorough understanding of the implications of these changes for ecosystem processes is essential to make accurate predictions of surface-atmosphere carbon (C) feedbacks. Yet, we lack a comprehensive understanding of the impacts of herbivore outbreaks on soil microbial underpinnings of C and nitrogen (N) fluxes. Here, we investigate the growth responses of heterotrophic soil decomposers and C and N mineralisation to simulated defoliator outbreaks in Subarctic birch forests. In microcosms, topsoil was incubated with leaf litter, insect frass, mineral N and combinations of the three; all was added in equal amounts of N. A higher fraction of added C and N was mineralised during outbreaks (frass addition) relative to non-outbreak years (litter addition). However, under high mineral N-availability in the soil of the kind likely under longer periods of enhanced insect herbivory (litter+mineral N), the mineralised fraction of added C decreased while the mineralised fraction of N increased substantially, which suggest a shift towards more N-mining of the organic substrates. This shift was accompanied by higher fungal dominance, and may facilitate soil C-accumulation assuming constant quality of C-inputs. Thus, long-term increases of insect herbivory, of the kind observed in some areas and projected by some models, may facilitate higher ecosystem C-sink capacity in this Subarctic ecosystem.

Longitudinal gradient in limnological variables in the Upper Paraná River: a brief description and the importance of undammed tributaries

Directory of Open Access Journals (Sweden)

Natália Fernanda Santana

2017-12-01

Full Text Available Abstract Aim: Describe the limnological pattern in a longitudinal gradient in the Paraná River, a highly dammed river, in a stretch localized between two dams, but rich in undammed tributaries. Methods Twelve transects in the longitudinal gradient of the Paraná River were sampled, with the first transect being placed right after Porto Primavera dam, and the last one in the lotic region of the Itaipu dam. In each of these transects, water transparency, electrical conductivity, pH, total nitrogen and total phosphorous were analyzed. Results In those regions nearer Porto Primavera dam it was observed high values of water transparency and low values of nitrogen and phosphorous. The values of water transparency decreased and the values of nitrogen and phosphorous increased as the distance from Porto Primavera dam increased. Because the new tributaries connect to the Paraná River, with the sites farer from Porto Primavera dam presenting values similar to those prior its construction. Conclusions Increase in the nutrients concentration and changes in ecological integrity are probably due to the presence of the undammed tributaries. They are originate in different river basins and therefore contribute to the Paraná River in distinct manners. Results presented here are an indicative of the fundamental importance of undammed tributaries in mitigating damming negative impacts in extremely dammed rivers and highlight the importance of keeping such tributaries free of dams.

Report of the 2004 Workshop on In Situ Iron Enrichment Experiments in the Eastern and Western Subarctic Pacific

OpenAIRE

Takeda, Shigenobu; Wong, C.S.

2006-01-01

Foreword 1. BACKGROUND AND OBJECTIVES (pdf, 0.1 Mb) 2. 2004 WORKSHOP SUMMARY (pdf, < 0.1 Mb) 2.1. What have we learned from the enrichment experiments? 2.2 What are the outstanding questions? 2.3 Recommendations for SEEDS-II 3. EXTENDED ABSTRACTS OF THE 2004 WORKSHOP 3.1 Synthesis of the Iron Enrichment Experiments: SEEDS and SERIES (pdf, 0.5 Mb) Iron fertilization experiment in the western subarctic Pacific (SEEDS) by At...

Alien roadside species more easily invade alpine than lowland plant communities in a subarctic mountain ecosystem.

Directory of Open Access Journals (Sweden)

Jonas J Lembrechts

Full Text Available Effects of roads on plant communities are not well known in cold-climate mountain ecosystems, where road building and development are expected to increase in future decades. Knowledge of the sensitivity of mountain plant communities to disturbance by roads is however important for future conservation purposes. We investigate the effects of roads on species richness and composition, including the plant strategies that are most affected, along three elevational gradients in a subarctic mountain ecosystem. We also examine whether mountain roads promote the introduction and invasion of alien plant species from the lowlands to the alpine zone. Observations of plant community composition were made together with abiotic, biotic and anthropogenic factors in 60 T-shaped transects. Alpine plant communities reacted differently to road disturbances than their lowland counterparts. On high elevations, the roadside species composition was more similar to that of the local natural communities. Less competitive and ruderal species were present at high compared with lower elevation roadsides. While the effects of roads thus seem to be mitigated in the alpine environment for plant species in general, mountain plant communities are more invasible than lowland communities. More precisely, relatively more alien species present in the roadside were found to invade into the surrounding natural community at high compared to low elevations. We conclude that effects of roads and introduction of alien species in lowlands cannot simply be extrapolated to the alpine and subarctic environment.

Alien roadside species more easily invade alpine than lowland plant communities in a subarctic mountain ecosystem.

Science.gov (United States)

Lembrechts, Jonas J; Milbau, Ann; Nijs, Ivan

2014-01-01

Effects of roads on plant communities are not well known in cold-climate mountain ecosystems, where road building and development are expected to increase in future decades. Knowledge of the sensitivity of mountain plant communities to disturbance by roads is however important for future conservation purposes. We investigate the effects of roads on species richness and composition, including the plant strategies that are most affected, along three elevational gradients in a subarctic mountain ecosystem. We also examine whether mountain roads promote the introduction and invasion of alien plant species from the lowlands to the alpine zone. Observations of plant community composition were made together with abiotic, biotic and anthropogenic factors in 60 T-shaped transects. Alpine plant communities reacted differently to road disturbances than their lowland counterparts. On high elevations, the roadside species composition was more similar to that of the local natural communities. Less competitive and ruderal species were present at high compared with lower elevation roadsides. While the effects of roads thus seem to be mitigated in the alpine environment for plant species in general, mountain plant communities are more invasible than lowland communities. More precisely, relatively more alien species present in the roadside were found to invade into the surrounding natural community at high compared to low elevations. We conclude that effects of roads and introduction of alien species in lowlands cannot simply be extrapolated to the alpine and subarctic environment.

Distribution and speciation of heavy metals in sediments from the mainstream, tributaries, and lakes of the Yangtze River catchment of Wuhan, China

International Nuclear Information System (INIS)

Yang Zhifeng; Wang Ying; Shen Zhenyao; Niu Junfeng; Tang Zhenwu

2009-01-01

A comparative study of the heavy metal (As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn) concentrations in sediments collected from the mainstream, tributaries, and lakes of the Yangtze River catchment of Wuhan, China, was conducted. Compared with the maximum background values in Wuhan Province soils, Cd was the metal with the highest contamination level, especially in the mainstream, followed by Zn and Cu. In a few samples from tributaries and lakes, the Hg concentration was very high compared to background levels. The concentrations of As and Ni in all sites fluctuated close to background levels. Partitioning of speciation of each heavy metal in sediments was similar for samples taken from the mainstream, tributaries, and lakes. Compared to the other metals studied, Cd, Cu, Zn, and Pb had higher bioavailability in the three zones, which means they pose a higher ecological risk. Significant correlations among group a (Zn, Cu, and Pb, r > 0.9) and group b (Cr and Ni, r = 0.978) in the mainstream; Hg, Cu, Cd, and Pb in lakes (r > 0.9); and Cu and Pb (r > 0.9) in tributaries were observed using Cluster and correlation analysis. However, a low correlation between As and the other elements in the three zones was shown. Overall, 63.6% of samples from the mainstream, 75.0% from tributaries, and 88.9% from lakes exhibited low and moderate ecological risk of heavy metals, and the potential ecological risks in the mainstream and tributaries were higher than those in lakes.

We adapt… but is it good or bad? Locating the political ecology and social-ecological systems debate in reindeer herding in the Swedish Sub-Arctic.

NARCIS (Netherlands)

Gallardo, Gloria; Saunders, Fred; Sokolova, Tatiana; Börebäck, Kristina; van Laerhoven, F.S.J.; Kokko, Suvi; Tuvendal, Magnus

2017-01-01

Abstract Reindeer herding (RDH) is a livelihood strategy deeply connected to Sami cultural tradition. This article explores the implications of two theoretical and methodological approaches for grasping complex socioenvironmental relationships of RDH in Subarctic Sweden. Based on joint fieldwork,

Analysis of Mining-induced Valley Closure Movements

Science.gov (United States)

Zhang, C.; Mitra, R.; Oh, J.; Hebblewhite, B.

2016-05-01

Valley closure movements have been observed for decades in Australia and overseas when underground mining occurred beneath or in close proximity to valleys and other forms of irregular topographies. Valley closure is defined as the inward movements of the valley sides towards the valley centreline. Due to the complexity of the local geology and the interplay between several geological, topographical and mining factors, the underlying mechanisms that actually cause this behaviour are not completely understood. A comprehensive programme of numerical modelling investigations has been carried out to further evaluate and quantify the influence of a number of these mining and geological factors and their inter-relationships. The factors investigated in this paper include longwall positional factors, horizontal stress, panel width, depth of cover and geological structures around the valley. It is found that mining in a series passing beneath the valley dramatically increases valley closure, and mining parallel to valley induces much more closure than other mining orientations. The redistribution of horizontal stress and influence of mining activity have also been recognised as important factors promoting valley closure, and the effect of geological structure around the valley is found to be relatively small. This paper provides further insight into both the valley closure mechanisms and how these mechanisms should be considered in valley closure prediction models.

A mesoscale iron enrichment in the western subarctic Pacific induces a large centric diatom bloom.

Science.gov (United States)

Tsuda, Atsushi; Takeda, Shigenobu; Saito, Hiroaki; Nishioka, Jun; Nojiri, Yukihiro; Kudo, Isao; Kiyosawa, Hiroshi; Shiomoto, Akihiro; Imai, Keiri; Ono, Tsuneo; Shimamoto, Akifumi; Tsumune, Daisuke; Yoshimura, Takeshi; Aono, Tatsuo; Hinuma, Akira; Kinugasa, Masatoshi; Suzuki, Koji; Sohrin, Yoshiki; Noiri, Yoshifumi; Tani, Heihachiro; Deguchi, Yuji; Tsurushima, Nobuo; Ogawa, Hiroshi; Fukami, Kimio; Kuma, Kenshi; Saino, Toshiro

2003-05-09

We have performed an in situ test of the iron limitation hypothesis in the subarctic North Pacific Ocean. A single enrichment of dissolved iron caused a large increase in phytoplankton standing stock and decreases in macronutrients and dissolved carbon dioxide. The dominant phytoplankton species shifted after the iron addition from pennate diatoms to a centric diatom, Chaetoceros debilis, that showed a very high growth rate, 2.6 doublings per day. We conclude that the bioavailability of iron regulates the magnitude of the phytoplankton biomass and the key phytoplankton species that determine the biogeochemical sensitivity to iron supply of high-nitrate, low-chlorophyll waters.

Hydrogeology and water quality of the stratified-drift aquifer in the Pony Hollow Creek Valley, Tompkins County, New York

Science.gov (United States)

Bugliosi, Edward F.; Miller, Todd S.; Reynolds, Richard J.

2014-01-01

away from groundwater mounds that have formed beneath upland tributaries that lose water where they flow on alluvial fans on the margins of the valley. In some places, groundwater that would normally flow toward streams is intercepted by pumping wells. Surface-water samples were collected in 2001 at four sites including Carter, Pony Hollow (two sites), and Chafee Creeks, and from six wells throughout the aquifer. Calcium dominates the cation composition and bicarbonate dominates the anion composition in groundwater and surface-water samples and none of the common inorganic constituents collected exceeded any Federal or State water-quality standards. Groundwater samples were collected from six wells all completed in the unconfined sand and gravel aquifer. Concentrations of calcium and magnesium dominated the ionic composition of the groundwater in all wells sampled. Nitrate, orthophosphate, and trace metals were detected in all groundwater samples, but none were more than U.S. Environmental Protection Agency or New York State Department of Health regulatory limits.

Bioassessment metrics and deposited sediments in tributaries of the Chattooga river watershed

Science.gov (United States)

Erica Chiao; J. Bruce Wallace

2003-01-01

Excessive sedimentation places waters of the Chattooga River network at risk of biological impairment. Monitoring efforts could be improved by including metrics that are responsive to changes in levels of fine sediments. We sampled three habitats (riffle, depositional, bedrock outcrop) for benthic macroinvertebrates at four sites in three low-order, tributary reaches...

Management of Water Quantity and Quality Based on Copula for a Tributary to Miyun Reservoir, Beijing

Science.gov (United States)

Zang, N.; Wang, X.; Liang, P.

2017-12-01

Due to the complex mutual influence between water quantity and water quality of river, it is difficult to reflect the actual characters of the tributaries to reservoir. In this study, the acceptable marginal probability distributions for water quantity and quality of reservoir inflow were calculated. A bivariate Archimedean copula was further applied to establish the joint distribution function of them. Then multiple combination scenarios of water quantity and water quality were designed to analyze their coexistence relationship and reservoir management strategies. Taking Bai river, an important tributary into the Miyun Reservoir, as a study case. The results showed that it is feasible to apply Frank copula function to describe the jointed distribution function of water quality and water quantity for Bai river. Furthermore, the monitoring of TP concentration needs to be strengthen in Bai river. This methodology can be extended to larger dimensions and is transferable to other reservoirs via establishment of models with relevant data for a particular area. Our findings help better analyzing the coexistence relationship and influence degree of the water quantity and quality of the tributary to reservoir for the purpose of water resources protection.

Copper, cadmium, and zinc concentrations in aquatic food chains from the Upper Sacramento River (California) and selected tributaries

Science.gov (United States)

Saiki, M.K.; Castleberry, D. T.; May, T. W.; Martin, B.A.; Bullard, F. N.

1995-01-01

Metals enter the Upper Sacramento River above Redding, California, primarily through Spring Creek, a tributary that receives acid-mine drainage from a US EPA Superfund site known locally as Iron Mountain Mine. Waterweed (Elodea canadensis) and aquatic insects (midge larvae, Chironomidae; and mayfly nymphs, Ephemeroptera) from the Sacramento River downstream from Spring Creek contained much higher concentrations of copper (Cu), cadmium (Cd), and zinc (Zn) than did similar taxa from nearby reference tributaries not exposed to acid-mine drainage. Aquatic insects from the Sacramento River contained especially high maximum concentrations of Cu (200 mg/kg dry weight in midge larvae), Cd (23 mg/kg dry weight in mayfly nymphs), and Zn (1,700 mg/kg dry weight in mayfly nymphs). Although not always statistically significant, whole-body concentrations of Cu, Cd, and Zn in fishes (threespine stickleback, Gasterosteus aculeatus; Sacramento sucker, Catostomus occidentalis; Sacramento squawfish, Ptychocheilus grandis; and chinook salmon, Oncorhynchus tshawytasch) from the Sacramento River were generally higher than in fishes from the reference tributaries.

Permafrost Thaw increases Emissions of Nitrous Oxide from Subarctic Peatlands

Science.gov (United States)

Voigt, C.; Marushchak, M. E.; Lamprecht, R. E.; Jackowicz-Korczynski, M.; Lindgren, A.; Mastepanov, M.; Christensen, T. R.; Granlund, L.; Tahvanainen, T.; Martikainen, P. J.; Biasi, C.

2017-12-01

Permafrost soils in the Arctic are thawing, exposing not only carbon but also large nitrogen stocks. The decomposition of this vast pool of long-term immobile C and N stocks results in the release of greenhouse gases to the atmosphere. Among these, carbon dioxide (CO2) and methane (CH4) are being studied extensively, and gaseous C release from thawing permafrost is known to be substantial. Most recent studies, however, show that Arctic soils may further be a relevant source of the strong greenhouse gas nitrous oxide (N2O). As N2O is almost 300 times more powerful in warming the climate than CO2 based on a 100-yr time horizon, the release of N2O from thawing permafrost could create a significant non-carbon permafrost-climate feedback. To study the effect of permafrost thaw on N2O fluxes, we collected peat mesocosms from a Subarctic permafrost peatland, and subjected these intact soil-plant systems to sequential thawing from the top of the active layer down to the upper permafrost layer. Measurements of N2O fluxes were coupled with detailed soil analyses and process studies. Since N2O fluxes are highly dependent on moisture conditions and vegetation cover, we applied two distinct moisture treatments (dry vs. wet) and simulated permafrost thaw in vegetated as well as in naturally bare mesocosms. Under dry conditions, permafrost thaw clearly increased N2O emissions. We observed the largest post-thaw emissions from bare peat surfaces, a typical landform in subarctic peatlands previously identified as hot spots for Arctic N2O emissions. There, permafrost thaw caused a five-fold increase in emissions (0.56 vs. 2.81 mg N2O m-2 d-1). While water-logged conditions suppressed N2O emissions, the presence of vegetation lowered, but did not prevent post-thaw N2O release. Based on these findings, we show that one fourth of the Arctic land area could be vulnerable for N2O emissions when permafrost thaws. Our results demonstrate that Arctic N2O emissions may be larger than

Suspended sediments from upstream tributaries as the source of downstream river sites

Science.gov (United States)

Haddadchi, Arman; Olley, Jon

2014-05-01

Understanding the efficiency with which sediment eroded from different sources is transported to the catchment outlet is a key knowledge gap that is critical to our ability to accurately target and prioritise management actions to reduce sediment delivery. Sediment fingerprinting has proven to be an efficient approach to determine the sources of sediment. This study examines the suspended sediment sources from Emu Creek catchment, south eastern Queensland, Australia. In addition to collect suspended sediments from different sites of the streams after the confluence of tributaries and outlet of the catchment, time integrated suspended samples from upper tributaries were used as the source of sediment, instead of using hillslope and channel bank samples. Totally, 35 time-integrated samplers were used to compute the contribution of suspended sediments from different upstream waterways to the downstream sediment sites. Three size fractions of materials including fine sand (63-210 μm), silt (10-63 μm) and fine silt and clay (<10 μm) were used to find the effect of particle size on the contribution of upper sediments as the sources of sediment after river confluences. And then samples were analysed by ICP-MS and -OES to find 41 sediment fingerprints. According to the results of Student's T-distribution mixing model, small creeks in the middle and lower part of the catchment were major source in different size fractions, especially in silt (10-63 μm) samples. Gowrie Creek as covers southern-upstream part of the catchment was a major contributor at the outlet of the catchment in finest size fraction (<10 μm) Large differences between the contributions of suspended sediments from upper tributaries in different size fractions necessitate the selection of appropriate size fraction on sediment tracing in the catchment and also major effect of particle size on the movement and deposition of sediments.

Controls and variability of solute and sedimentary fluxes in Arctic and sub-Arctic Environments

Science.gov (United States)

Dixon, John

2015-04-01

Six major factors consistently emerge as controls on the spatial and temporal variability in sediment and solute fluxes in cold climates. They are climatic, geologic, physiographic or relief, biologic, hydrologic, and regolith factors. The impact of these factors on sediment and solute mass transfer in Arctic and sub-Arctic environments is examined. Comparison of non-glacierized Arctic vs. subarctic drainage basins reveals the effects of these controls. All drainage basins exhibit considerable variability in rates of sediment and solute fluxes. For the non-glacierized drainage basins there is a consistent increase in sediment mass transfer by slope processes and fluvial processes as relief increases. Similarly, a consistent increase in sediment mass transfer by slope and fluvial processes is observed as total precipitation increases. Similar patterns are also observed with respect to solute transport and relief and precipitation. Lithologic factors are most strongly observed in the contrast between volcanic vs. plutonic igneous bedrock substrates. Basins underlain by volcanic rocks display greater mass transfers than those underlain by plutonic rocks. Biologic influences are most strongly expressed by variations in extent of vegetation cover and the degree of human interference, with human impacted basins generating greater fluxes. For glacierized basins the fundamental difference to non-glacierized basins is an overall increase in mean annual mass transfers of sediment and a generally smaller magnitude solute transfer. The principal role of geology is observed with respect to lithology. Catchments underlain by limestone demonstrate substantially greater solute mass transfers than sediment transfer. The influence of relief is seen in the contrast in mass transfers between upland and lowland drainage basins with upland basins generating greater sediment and solute transfers than lowland basins. For glacierized basins the effects of biology and regolith appear to be

Distribution and movement of Big Spring spinedace (Lepidomeda mollispinis pratensis) in Condor Canyon, Meadow Valley Wash, Nevada

Science.gov (United States)

Jezorek, Ian G.; Connolly, Patrick J.

2013-01-01

Big Spring spinedace (Lepidomeda mollispinis pratensis) is a cyprinid whose entire population occurs within a section of Meadow Valley Wash, Nevada. Other spinedace species have suffered population and range declines (one species is extinct). Managers, concerned about the vulnerability of Big Spring spinedace, have considered habitat restoration actions or translocation, but they have lacked data on distribution or habitat use. Our study occurred in an 8.2-km section of Meadow Valley Wash, including about 7.2 km in Condor Canyon and 0.8 km upstream of the canyon. Big Spring spinedace were present upstream of the currently listed critical habitat, including in the tributary Kill Wash. We found no Big Spring spinedace in the lower 3.3 km of Condor Canyon. We tagged Big Spring spinedace ≥70 mm fork length (range 70–103 mm) with passive integrated transponder tags during October 2008 (n = 100) and March 2009 (n = 103) to document movement. At least 47 of these individuals moved from their release location (up to 2 km). Thirty-nine individuals moved to Kill Wash or the confluence area with Meadow Valley Wash. Ninety-three percent of movement occurred in spring 2009. Fish moved both upstream and downstream. We found no movement downstream over a small waterfall at river km 7.9 and recorded only one fish that moved downstream over Delmue Falls (a 12-m drop) at river km 6.1. At the time of tagging, there was no significant difference in fork length or condition between Big Spring Spinedace that were later detected moving and those not detected moving. We found no significant difference in fork length or condition at time of tagging of Big Spring spinedace ≥70 mm fork length that were detected moving and those not detected moving. Kill Wash and its confluence area appeared important to Big Spring spinedace; connectivity with these areas may be key to species persistence. These areas may provide a habitat template for restoration or translocation. The lower 3.3 km of

Fish migration between a temperate reservoir and its main tributary

Czech Academy of Sciences Publication Activity Database

Hladík, Milan; Kubečka, Jan

2003-01-01

Roč. 504, - (2003), s. 251-266 ISSN 0018-8158. [Reservoir Limnology and Water Quality /4./. České Budějovice, 12.08.2002-16.08.2002] R&D Projects: GA ČR GA206/02/0520; GA AV ČR IBS6017004; GA AV ČR IAA6017201; GA AV ČR KSK6005114 Institutional research plan: CEZ:AV0Z6017912 Keywords : freshwater fish migration * reservoir-tributary ecotone * spawning Subject RIV: EH - Ecology, Behaviour Impact factor: 0.720, year: 2003

The impact of a tributary that carries high amounts of bed-load on the deposition of sediment downstream of a run-of river plant; Die Auswirkungen eines Geschiebe fuehrenden Zubringers auf die Verlandungssituation im Unterwasser eines Laufkraftwerkes

Energy Technology Data Exchange (ETDEWEB)

Schneider, Josef; Sindelar, Christine; Feldbacher, Rupert; Knoblauch, Helmut [TU Graz (Austria). Inst. fuer Wasserbau und Wasserwirtschaft

2011-07-01

For guaranteeing a sustainable sediment management on a chain of run-of river plants in the Salzach valley in Austria nearly annual flushings have been performed. The sediments that are removed out of the reservoirs tend to deposit immediately downstream of the dams mainly at the outlet of the turbines due to widening or reduced slope. During the physical model tests, which were performed for the hydro power plant St. Veit, it could be observed that the boundary conditions were obviously wrong because in the prototype much more sediment was settled as in the model. A downstream located tributary was found responsible because of its dumping of high amounts of bed load into the river Salzach. This led to a backwater flow respectively reduced shear stresses. Further model tests resulted in a successful solution which mitigates the situation substantially. (orig.)

A landscape scale valley confinement algorithm: Delineating unconfined valley bottoms for geomorphic, aquatic, and riparian applications

Science.gov (United States)

David E. Nagel; John M. Buffington; Sharon L. Parkes; Seth Wenger; Jaime R. Goode

2014-01-01

Valley confinement is an important landscape characteristic linked to aquatic habitat, riparian diversity, and geomorphic processes. This report describes a GIS program called the Valley Confinement Algorithm (VCA), which identifies unconfined valleys in montane landscapes. The algorithm uses nationally available digital elevation models (DEMs) at 10-30 m resolution to...

Ground-Water Budgets for the Wood River Valley Aquifer System, South-Central Idaho, 1995-2004

Science.gov (United States)

Bartolino, James R.

2009-01-01

The Wood River Valley contains most of the population of Blaine County and the cities of Sun Valley, Ketchum, Haley, and Bellevue. This mountain valley is underlain by the alluvial Wood River Valley aquifer system which consists of a single unconfined aquifer that underlies the entire valley, an underlying confined aquifer that is present only in the southernmost valley, and the confining unit that separates them. The entire population of the area depends on ground water for domestic supply, either from domestic or municipal-supply wells, and rapid population growth since the 1970s has caused concern about the long-term sustainability of the ground-water resource. To help address these concerns this report describes a ground-water budget developed for the Wood River Valley aquifer system for three selected time periods: average conditions for the 10-year period 1995-2004, and the single years of 1995 and 2001. The 10-year period 1995-2004 represents a range of conditions in the recent past for which measured data exist. Water years 1995 and 2001 represent the wettest and driest years, respectively, within the 10-year period based on precipitation at the Ketchum Ranger Station. Recharge or inflow to the Wood River Valley aquifer system occurs through seven main sources (from largest to smallest): infiltration from tributary canyons, streamflow loss from the Big Wood River, areal recharge from precipitation and applied irrigation water, seepage from canals and recharge pits, leakage from municipal pipes, percolation from septic systems, and subsurface inflow beneath the Big Wood River in the northern end of the valley. Total estimated mean annual inflow or recharge to the aquifer system for 1995-2004 is 270,000 acre-ft/yr (370 ft3/s). Total recharge for the wet year 1995 and the dry year 2001 is estimated to be 270,000 acre-ft/yr (370 ft3/s) and 220,000 acre-ft/yr (300 ft3/s), respectively. Discharge or outflow from the Wood River Valley aquifer system occurs through

Effects of climate on organic carbon and the ratio of planktonic to benthic primary producers in a subarctic lake during the past 45 years

NARCIS (Netherlands)

Rosén, Peter; Cunningham, Laura; Vonk, Jorien; Karlsson, Jan

The effects of climatic variables on lake-water total organic carbon (TOC) concentrations and benthic and pelagic primary producers during the past 45 yr were assessed using the sediment records of two subarctic lakes, one with mires and one without mires connected to the lake. The lake with a mire

Assessing the potential for rainbow trout reproduction in tributaries of the Mountain Fork River below Broken Bow Dam, southeastern Oklahoma

Science.gov (United States)

Long, James M.; Starks, Trevor A.; Farling, Tyler; Bastarache, Robert

2016-01-01

Stocked trout (Salmonidae) in reservoir tailwater systems in the Southern United States have been shown to use tributary streams for spawning and rearing. The lower Mountain Fork of the Little River below Broken Bow Dam is one of two year-round tailwater trout fisheries in Oklahoma, and the only one with evidence of reproduction by stocked rainbow trout (Oncorhynchus mykiss). Whether stocked trout use tributaries in this system for spawning is unknown. Furthermore, an

Small martian valleys: Pristine and degraded morphology

International Nuclear Information System (INIS)

Baker, V.R.; Partridge, J.B.

1986-01-01

The equatorial heavily cratered uplands of Mars are dissected by two classes of small valleys that are intimately associated in compound networks. Pristine valleys with steep valley walls preferentially occupy downstream portions of compound basins. Degraded valleys with eroded walls are laterally more extensive and have higher drainage densities than pristine valleys. Morphometric and crater-counting studies indicate that relatively dense drainage networks were emplaced on Mars during the heavy bombardment about 4.0 b.y. ago. Over a period of approximately 10 8 years, these networks were degraded and subsequently invaded by headwardly extending pristine valleys. The pristine valleys locally reactivated the compound networks, probably through sapping processes dependent upon high water tables. Fluvial activity in the heavily cratered uplands generally ceased approximately 3.8--3.9 b.y. ago, coincident with the rapid decline in cratering rates. The relict compound valleys on Mars are morphometrically distinct from most terrestrial drainage systems. The differences might be caused by a Martian valley formation episode characterized by hyperaridity, by inadequate time for network growth, by very permeable rock types, or by a combination of factors

Use of historical sources in a study of the 1895 floods on the Danube River and its tributaries

Directory of Open Access Journals (Sweden)

Melo Marián

2014-01-01

Full Text Available Hydrological data series that are measured on the Danube River are temporally limited. Instrumental flow data can be prolonged by documentary data from historical sources in archives. This paper deals with knowledge gained by studies of historical materials regarding the 1895 catastrophic floods on the Danube River and its tributaries as reflected in the contemporary local press and also in studies of other historical records (flood marks, chronicles, books and photos. Records from the newspapers (Wiener Zeitung, Preßburger Zeitung, The New York Times and Komáromi Lapok and other analysed sources show the relatively large territorial impact of the floods in March and April 1895, which affected not only the Danube and its tributaries, but also some neighboring basins. Catastrophic consequences of the flood were especially reported from the lower parts of the Danube River (from its confluence with the Drava River up to the mouth of the Black Sea and the tributaries of the Tisza and Sava rivers. In 1895, the second highest flood after the 2006 flood on the Lower Danube was observed since 1841.

Geologic summary of the Owens Valley drilling project, Owens and Rose Valleys, Inyo County, California

International Nuclear Information System (INIS)

Schaer, D.W.

1981-07-01

The Owens Valley Drilling Project consists of eight drill holes located in southwest Inyo County, California, having an aggregate depth of 19,205 feet (5853 m). Project holes penetrated the Coso Formation of upper Pliocene or early Pleistocene age and the Owens Lake sand and lakebed units of the same age. The project objective was to improve the reliability of uranium-potential-resource estimates assigned to the Coso Formation in the Owens Valley region. Uranium-potential-resource estimates for this area in $100 per pound U 3 O 8 forward-cost-category material have been estimatd to be 16,954 tons (15,384 metric tons). This estimate is based partly on project drilling results. Within the Owens Valley project area, the Coso Formation was encountered only in the Rose Valley region, and for this reason Rose Valley is considered to be the only portion of the project area favorable for economically sized uranium deposits. The sequence of sediments contained in the Owens Valley basin is considered to be largely equivalent but lithologically dissimilar to the Coso Formation of Haiwee Ridge and Rose Valley. The most important factor in the concentration of significant amounts of uranium in the rock units investigated appears to be the availability of reducing agents. Significant amounts of reductants (pyrite) were found in the Coso Formation. No organic debris was noted. Many small, disconnected uranium occurrences, 100 to 500 ppM U 3 O 8 , were encountered in several of the holes

Valley dependent transport in graphene L junction

Science.gov (United States)

Chan, K. S.

2018-05-01

We studied the valley dependent transport in graphene L junctions connecting an armchair lead and a zigzag lead. The junction can be used in valleytronic devices and circuits. Electrons injected from the armchair lead into the junction is not valley polarized, but they can become valley polarized in the zigzag lead. There are Fermi energies, where the current in the zigzag lead is highly valley polarized and the junction is an efficient generator of valley polarized current. The features of the valley polarized current depend sensitively on the widths of the two leads, as well as the number of dimers in the armchair lead, because this number has a sensitive effect on the band structure of the armchair lead. When an external potential is applied to the junction, the energy range with high valley polarization is enlarged enhancing its function as a generator of highly valley polarized current. The scaling behavior found in other graphene devices is also found in L junctions, which means that the results presented here can be extended to junctions with larger dimensions after appropriate scaling of the energy.

Evaluation of Water Quality for Two St. Johns River Tributaries Receiving Septic Tank Effluent, Duval County, Florida

Science.gov (United States)

Wicklein, Shaun M.

2004-01-01

Tributary streamflow to the St. Johns River in Duval County is thought to be affected by septic tank leachate from residential areas adjacent to these tributaries. Water managers and the city of Jacksonville have committed to infrastructure improvements as part of a management plan to address the impairment of tributary water quality. In order to provide data to evaluate the effects of future remedial activities in selected tributaries, major ion and nutrient concentrations, fecal coliform concentrations, detection of wastewater compounds, and tracking of bacterial sources were used to document septic tank influences on the water quality of selected tributaries. The tributaries Fishing Creek and South Big Fishweir Creek were selected because they drain subdivisions identified as high priority locations for septic tank phase-out projects: the Pernecia and Murray Hill B subdivisions, respectively. Population, housing (number of residences), and septic tank densities for the Murray Hill B subdivision are greater than those for the Pernecia subdivision. Water-quality samples collected in the study basins indicate influences from ground water and septic tanks. Estimated concentrations of total nitrogen ranged from 0.33 to 2.86 milligrams per liter (mg/L), and ranged from less than laboratory reporting limit (0.02 mg/L) to 0.64 mg/L for total phosphorus. Major ion concentrations met the State of Florida Class III surface-water standards; total nitrogen and total phosphorus concentrations exceeded the U.S. Environmental Protection Agency Ecoregion XII nutrient criteria for rivers and streams 49 and 96 percent of the time, respectively. Organic wastewater compounds detected at study sites were categorized as detergents, antioxidants and flame retardants, manufactured polycarbonate resins, industrial solvents, and mosquito repellent. The most commonly detected compound was para-nonylphenol, a breakdown product of detergent. Results of wastewater sampling give evidence that

Sphagnum-dwelling testate amoebae in subarctic bogs are more sensitive to soil warming in the growing season than in winter: the results of eight-year field climate manipulations.

Science.gov (United States)

Tsyganov, Andrey N; Aerts, Rien; Nijs, Ivan; Cornelissen, Johannes H C; Beyens, Louis

2012-05-01

Sphagnum-dwelling testate amoebae are widely used in paleoclimate reconstructions as a proxy for climate-induced changes in bogs. However, the sensitivity of proxies to seasonal climate components is an important issue when interpreting proxy records. Here, we studied the effects of summer warming, winter snow addition solely and winter snow addition together with spring warming on testate amoeba assemblages after eight years of experimental field climate manipulations. All manipulations were accomplished using open top chambers in a dry blanket bog located in the sub-Arctic (Abisko, Sweden). We estimated sensitivity of abundance, diversity and assemblage structure of living and empty shell assemblages of testate amoebae in the living and decaying layers of Sphagnum. Our results show that, in a sub-arctic climate, testate amoebae are more sensitive to climate changes in the growing season than in winter. Summer warming reduced species richness and shifted assemblage composition towards predominance of xerophilous species for the living and empty shell assemblages in both layers. The higher soil temperatures during the growing season also decreased abundance of empty shells in both layers hinting at a possible increase in their decomposition rates. Thus, although possible effects of climate changes on preservation of empty shells should always be taken into account, species diversity and structure of testate amoeba assemblages in dry subarctic bogs are sensitive proxies for climatic changes during the growing season. Copyright © 2011 Elsevier GmbH. All rights reserved.

"mus co shee": Indigenous Plant Foods and Horticultural Imperialism in the Canadian Sub-Arctic.

Science.gov (United States)

Soloway, Beverly

2015-01-01

The 17th-century arrival of the Hudson's Bay Company in Rupert's Land disrupted Mushkegowuk (Cree) hunter-gatherer society by replacing the collection of indigenous plant foods with a British planted-food model. Within a hundred years of British contact, new foodways relied upon hunting and gardening, bringing a loss in heritage plant food knowledge. Mushkegowuk living in the sub-arctic today have minimal knowledge of edible indigenous plants. Dependence on limited local gardening or imported grocery store vegetables has affected diet, nutrition, and cultural systems. In addition to exploring plant food gathering and gardening history in the Hudson Bay Lowlands, this paper demonstrates how re-discovering lost foodway knowledge can contribute to the health and well-being of those living in the far north.

Impacts of extreme winter warming events on plant physiology in a sub-Arctic heath community.

Science.gov (United States)

Bokhorst, Stef; Bjerke, Jarle W; Davey, Matthew P; Taulavuori, Kari; Taulavuori, Erja; Laine, Kari; Callaghan, Terry V; Phoenix, Gareth K

2010-10-01

Insulation provided by snow cover and tolerance of freezing by physiological acclimation allows Arctic plants to survive cold winter temperatures. However, both the protection mechanisms may be lost with winter climate change, especially during extreme winter warming events where loss of snow cover from snow melt results in exposure of plants to warm temperatures and then returning extreme cold in the absence of insulating snow. These events cause considerable damage to Arctic plants, but physiological responses behind such damage remain unknown. Here, we report simulations of extreme winter warming events using infrared heating lamps and soil warming cables in a sub-Arctic heathland. During these events, we measured maximum quantum yield of photosystem II (PSII), photosynthesis, respiration, bud swelling and associated bud carbohydrate changes and lipid peroxidation to identify physiological responses during and after the winter warming events in three dwarf shrub species: Empetrum hermaphroditum, Vaccinium vitis-idaea and Vaccinium myrtillus. Winter warming increased maximum quantum yield of PSII, and photosynthesis was initiated for E. hermaphroditum and V. vitis-idaea. Bud swelling, bud carbohydrate decreases and lipid peroxidation were largest for E. hermaphroditum, whereas V. myrtillus and V. vitis-idaea showed no or less strong responses. Increased physiological activity and bud swelling suggest that sub-Arctic plants can initiate spring-like development in response to a short winter warming event. Lipid peroxidation suggests that plants experience increased winter stress. The observed differences between species in physiological responses are broadly consistent with interspecific differences in damage seen in previous studies, with E. hermaphroditum and V. myrtillus tending to be most sensitive. This suggests that initiation of spring-like development may be a major driver in the damage caused by winter warming events that are predicted to become more

Interannual Variability of Carbon Dioxide, Methane and Nitrous Oxide Fluxes in Subarctic European Russian Tundra

Science.gov (United States)

Marushchak, M. E.; Voigt, C.; Gil, J.; Lamprecht, R. E.; Trubnikova, T.; Virtanen, T.; Kaverin, D.; Martikainen, P. J.; Biasi, C.

2017-12-01

Southern tundra landscapes are particularly vulnerable to climate warming, permafrost thaw and associated landscape rearrangement due to near-zero permafrost temperatures. The large soil C and N stocks of subarctic tundra may create a positive feedback for warming if released to the atmosphere at increased rates. Subarctic tundra in European Russia is a mosaic of land cover types, which all play different roles in the regional greenhouse gas budget. Peat plateaus - massive upheaved permafrost peatlands - are large storehouses of soil carbon and nitrogen, but include also bare peat surfaces that act as hot-spots for both carbon dioxide and nitrous oxide emissions. Tundra wetlands are important for the regional greenhouse gas balance since they show high rates of methane emissions and carbon uptake. The most dominant land-form is upland tundra vegetated by shrubs, lichens and mosses, which displays a close-to-neutral balance with respect to all three greenhouse gases. The study site Seida (67°03'N, 62°56'E), located in the discontinuous permafrost zone of Northeast European Russia, incorporates all these land forms and has been an object for greenhouse gas investigations since 2007. Here, we summarize the growing season fluxes of carbon dioxide, methane and nitrous oxide measured by chamber techniques over the study years. We analyzed the flux time-series together with the local environmental data in order to understand the drivers of interannual variability. Detailed soil profile measurements of greenhouse gas concentrations, soil moisture and temperature provide insights into soil processes underlying the net emissions to the atmosphere. The multiannual time-series allows us to assess the importance of the different greenhouse gases and landforms to the overall climate forcing of the study region.

Selenium and other elements in freshwater fishes from the irrigated San Joaquin Valley, California

Science.gov (United States)

Saiki, M.K.; Jennings, M.R.; May, T.W.

1992-01-01

Arsenic (As), chromium (Cr), mercury (Hg), and selenium (Se) were measured in composite whole-body samples of five fishes — bluegill (Lepomis macrochirus), common carp (Cyprinus carpio), mosquitofish (Gambusia affinis), largemouth bass (Micropterus salmoides), and Sacramento blackfish (Orthodon microlepidotus) — from the San Joaquin River system to determine if concentrations were elevated from exposure to agricultural subsurface (tile) drainage. Except for Cr, the concentrations of these elements in fishes from one or more sites were elevated; however, only Se approached concentrations that may adversely affect survival, growth, or reproduction in warm water fishes. Moreover, only Se among the four measured elements exhibited a geographic (spatial) pattern that coincided with known inflows of tile drainage to the San Joaquin River and its tributaries. Historical data from the Grassland Water District (Grasslands; a region exposed to concentrated tile drainage) suggested that concentrations of Se in fishes were at maximum during or shortly after 1984 and have been slightly lower since then. The recent decline of Se concentrations in fishes from the Grasslands could be temporary if additional acreages of irrigated lands in this portion of the San Joaquin Valley must be tile-drained to protect agricultural crops from rising groundwater tables.

Comparisons between POC and zooplankton swimmer flux from sediment traps in the subarctic and subtropical North Pacific

Science.gov (United States)

Yokoi, Naoya; Abe, Yoshiyuki; Kitamura, Minoru; Honda, Makio C.; Yamaguchi, Atsushi

2018-03-01

Seasonal changes in zooplankton swimmer (ZS) abundance, biomass and community structure were evaluated based on samples collected by moored sediment traps at a depth of 200 m in the subarctic (SA) and subtropical (ST) western North Pacific. Based on these samples, we made comparisons on two topics: 1) latitudinal (subarctic vs. subtropical) changes in ZS abundance, biomass and community and 2) quantitative differences between the ZS and particle organic carbon (POC) fluxes based on data from moored or drifting sediment traps. The results showed that the ZS flux was greater in the SA (annual mean: 311 ind. m-2 day-1 or 258 mg C m-2 day-1) than in the ST (135 ind. m-2 day-1 or 38 mg C m-2 day-1). The peak ZS flux was observed from July-August in the SA and from April-May in the ST. The dominant taxa were Copepoda and Chaetognatha in the SA and Ostracoda and Mollusca in the ST. These latitudinal differences are likely related to the dominance of large-sized Copepoda in the SA, regional differences in the timing of the spring phytoplankton bloom, and the magnitude and size structure of primary producers. The percent composition of ZS to the total C flux (= ZS+POC flux) varied by region: 85-95% in the SA and 47-75% in the ST. These differences between the ZS composition and the total C flux are most likely caused by the dominance of large-sized Copepoda (Neocalanus spp. and Eucalanus bungii) in the SA.

Phytoplankton growth and microzooplankton grazing along a sub-Arctic fjord (Godthåbsfjord, West Greenland)

DEFF Research Database (Denmark)

Calbet, A.; Riisgaard, Karen; Saiz, E.

2011-01-01

the nutrient rich waters in the upwelling area in the vicinity of the glacier. Most of the grazing impact was on the 20 µm microzooplankton, as deducted from additional dilution experiments removing > 20 µm. Overall, little......We evaluated the role of microzooplankton (sensu latto, grazers sea transect in the Greenland subarctic fjord, Godthåbfjord. Based on the distribution of size fractionated chlorophyll a (chl a) concentrations...... we established four zones: i) Fyllas Bank, characterized by deep chl a maxima (ca. 30-40 m) consisting of large cells; ii) the mouth and main branch of the fjord, where phytoplankton was relatively homogeneously distributed in the upper 30 m layer; iii) inner waters influenced by glacial melt water...

Duck Valley Habitat Enhancement and Protection, 2000 Annual Report.

Energy Technology Data Exchange (ETDEWEB)

Dodson, Guy; Pero, Vincent (Shoshone-Paiute Nation, Duck Valley Indian Reservation, Owyhee, NV)

2000-01-01

The Duck Valley Indian Reservations' Habitat Enhancement project is an ongoing project designed to enhance and protect the critical riparian areas, natural springs, and native fish spawning areas on the Reservation. The project was begun in 1997 with the hiring of a fisheries biologist and the creation of a new department for the Tribes. The project's goals are to protect and enhance the springs, Owyhee River, its tributaries, and to develop a database that can be used by other fisheries professionals which includes information on water quality and fish composition, health, abundance, and genetic makeup. One habitat portion of the project is a focus on protection the numerous springs that provide clean, cool water to the Owyhee River. This will be accomplished through enclosure fences of the spring heads and water troughs to provide clean cool drinking water for wildlife and livestock. Another habitat portion of the project involves protecting headwater areas of streams with native fish populations. This is accomplished through enclosure fencing and riparian plantings on any eroded or degraded banks in the enclosure area. Finally, we monitor and evaluate the areas protected and enhanced. This is accomplished through biological sampling for temperature, Oxygen, sedimentation, and measurements of water depth, bank height and undercut, and width of stream. With the habitat and biological indices we will be able to evaluate how well protective measures are doing, and where to focus future efforts.

Microscopic Identification of Prokaryotes in Modern and Ancient Halite, Saline Valley and Death Valley, California

Science.gov (United States)

Schubert, Brian A.; Lowenstein, Tim K.; Timofeeff, Michael N.

2009-06-01

Primary fluid inclusions in halite crystallized in Saline Valley, California, in 1980, 2004-2005, and 2007, contain rod- and coccoid-shaped microparticles the same size and morphology as archaea and bacteria living in modern brines. Primary fluid inclusions from a well-dated (0-100,000 years), 90 m long salt core from Badwater Basin, Death Valley, California, also contain microparticles, here interpreted as halophilic and halotolerant prokaryotes. Prokaryotes are distinguished from crystals on the basis of morphology, optical properties (birefringence), and uniformity of size. Electron micrographs of microparticles from filtered modern brine (Saline Valley), dissolved modern halite crystals (Saline Valley), and dissolved ancient halite crystals (Death Valley) support in situ microscopic observations that prokaryotes are present in fluid inclusions in ancient halite. In the Death Valley salt core, prokaryotes in fluid inclusions occur almost exclusively in halite precipitated in perennial saline lakes 10,000 to 35,000 years ago. This suggests that trapping and preservation of prokaryotes in fluid inclusions is influenced by the surface environment in which the halite originally precipitated. In all cases, prokaryotes in fluid inclusions in halite from the Death Valley salt core are miniaturized (<1 μm diameter cocci, <2.5 μm long, very rare rod shapes), which supports interpretations that the prokaryotes are indigenous to the halite and starvation survival may be the normal response of some prokaryotes to entrapment in fluid inclusions for millennia. These results reinforce the view that fluid inclusions in halite and possibly other evaporites are important repositories of microbial life and should be carefully examined in the search for ancient microorganisms on Earth, Mars, and elsewhere in the Solar System.

Topological Valley Transport in Two-dimensional Honeycomb Photonic Crystals.

Science.gov (United States)

Yang, Yuting; Jiang, Hua; Hang, Zhi Hong

2018-01-25

Two-dimensional photonic crystals, in analogy to AB/BA stacking bilayer graphene in electronic system, are studied. Inequivalent valleys in the momentum space for photons can be manipulated by simply engineering diameters of cylinders in a honeycomb lattice. The inequivalent valleys in photonic crystal are selectively excited by a designed optical chiral source and bulk valley polarizations are visualized. Unidirectional valley interface states are proved to exist on a domain wall connecting two photonic crystals with different valley Chern numbers. With the similar optical vortex index, interface states can couple with bulk valley polarizations and thus valley filter and valley coupler can be designed. Our simple dielectric PC scheme can help to exploit the valley degree of freedom for future optical devices.

Geologic map of the upper Arkansas River valley region, north-central Colorado

Science.gov (United States)

Kellogg, Karl S.; Shroba, Ralph R.; Ruleman, Chester A.; Bohannon, Robert G.; McIntosh, William C.; Premo, Wayne R.; Cosca, Michael A.; Moscati, Richard J.; Brandt, Theodore R.

2017-11-17

This 1:50,000-scale U.S. Geological Survey geologic map represents a compilation of the most recent geologic studies of the upper Arkansas River valley between Leadville and Salida, Colorado. The valley is structurally controlled by an extensional fault system that forms part of the prominent northern Rio Grande rift, an intra-continental region of crustal extension. This report also incorporates new detailed geologic mapping of previously poorly understood areas within the map area and reinterprets previously studied areas. The mapped region extends into the Proterozoic metamorphic and intrusive rocks in the Sawatch Range west of the valley and the Mosquito Range to the east. Paleozoic rocks are preserved along the crest of the Mosquito Range, but most of them have been eroded from the Sawatch Range. Numerous new isotopic ages better constrain the timing of both Proterozoic intrusive events, Late Cretaceous to early Tertiary intrusive events, and Eocene and Miocene volcanic episodes, including widespread ignimbrite eruptions. The uranium-lead ages document extensive about 1,440-million years (Ma) granitic plutonism mostly north of Buena Vista that produced batholiths that intruded an older suite of about 1,760-Ma metamorphic rocks and about 1,700-Ma plutonic rocks. As a result of extension during the Neogene and possibly latest Paleogene, the graben underlying the valley is filled with thick basin-fill deposits (Dry Union Formation and older sediments), which occupy two sub-basins separated by a bedrock high near the town of Granite. The Dry Union Formation has undergone deep erosion since the late Miocene or early Pliocene. During the Pleistocene, ongoing steam incision by the Arkansas River and its major tributaries has been interrupted by periodic aggradation. From Leadville south to Salida as many as seven mapped alluvial depositional units, which range in age from early to late Pleistocene, record periodic aggradational events along these streams that are

Mechanical control over valley magnetotransport in strained graphene

Energy Technology Data Exchange (ETDEWEB)

Ma, Ning, E-mail: maning@stu.xjtu.edu.cn [Department of Physics, MOE Key Laboratory of Advanced Transducers and Intelligent Control System, Taiyuan University of Technology, Taiyuan 030024 (China); Department of Applied Physics, MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter, Xi' an Jiaotong University, Xi' an 710049 (China); Zhang, Shengli, E-mail: zhangsl@mail.xjtu.edu.cn [Department of Applied Physics, MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter, Xi' an Jiaotong University, Xi' an 710049 (China); Liu, Daqing, E-mail: liudq@cczu.edu.cn [School of Mathematics and Physics, Changzhou University, Changzhou 213164 (China)

2016-05-06

Recent experiments report that the graphene exhibits Landau levels (LLs) that form in the presence of a uniform strain pseudomagnetic field with magnitudes up to hundreds of tesla. We further reveal that the strain removes the valley degeneracy in LLs, and leads to a significant valley polarization with inversion symmetry broken. This accordingly gives rise to the well separated valley Hall plateaus and Shubnikov–de Haas oscillations. These effects are absent in strainless graphene, and can be used to generate and detect valley polarization by mechanical means, forming the basis for the new paradigm “valleytronics” applications. - Highlights: • We explore the mechanical strain effects on the valley magnetotransport in graphene. • We analytically derive the dc collisional and Hall conductivities under strain. • The strain removes the valley degeneracy in Landau levels. • The strain causes a significant valley polarization with inversion symmetry broken. • The strain leads to the well separated valley Hall and Shubnikov–de Haas effects.

Is the mineralisation response to root exudation controlled by the microbial stoichiometric demand in subarctic soils?

Science.gov (United States)

Rousk, Johannes; Hicks, Lettice; Leizeaga, Ainara; Michelsen, Anders; Rousk, Kathrin

2017-04-01

Climate change will expose arctic and subarctic systems to warming and a shift towards plant communities with more rhizosphere labile C input. Labile C can also increase the rate of loss of native soil organic matter (SOM); a phenomenon termed 'priming'. We investigated how warming (+1.1˚ C over ambient using open top chambers) and the addition of plant litter (90 g m-2 y-1) or organic nitrogen (N) (fungal fruit bodies; 90 g m-2 y-1) in the Subarctic influenced the susceptibility of SOM mineralisation to priming, and its microbial underpinnings. Root exudation were simulated with the addition of labile organic matter both in the form of only labile C (13C-glucose) or in the form of labile C and N (13C-alanine). We hypothesized that labile C would induce a higher mineralization of N than C sourced from SOM ("N mining"); a response unrelated to microbial growth responses. We also hypothesized that the N mining effect would be more pronounced in climate change simulation treatments of higher C/N (plant litter) than treatments with lower C/N (fungal fruitbodies and warming), with the control treatments intermediate. We also hypothesized that the addition of labile C and N would not result in selective N mining, but instead coupled responses of C and N mineralisation sourced from SOM; a response that would coincide with stimulated microbial growth responses. Labile C appeared to inhibit the mineralisation of C from SOM by up to 60% within hours. In contrast, the mineralisation of N from SOM was stimulated by up to 300%. These responses occurred rapidly and were unrelated to microbial successional dynamics, suggesting catabolic responses. Considered separately, the labile-C inhibited C mineralisation is compatible with previously reported findings termed 'preferential substrate utilisation' or 'negative apparent priming', while the stimulated N mineralisation responses echo recent reports of 'real priming' of SOM mineralisation. However, C and N mineralisation responses

RUNOFF POTENTIAL OF MUREŞ RIVER UPPER BASIN TRIBUTARIES

Directory of Open Access Journals (Sweden)

V. SOROCOVSCHI

2012-03-01

Full Text Available Runoff Potential of Mureş River Upper Basin Tributaries. The upper basin of the Mureş River includes a significant area of the Eastern Carpathians central western part with different runoff formation conditions. In assessing the average annual runoff potential we used data from six gauging stations and made assessments on three distinct periods. Identifying the appropriate areas of the obtained correlations curves (between specific average runoff and catchments mean altitude allowed the assessment of potential runoff at catchment level and on geographical units. The potential average runoff is also assessed on altitude intervals of the mentioned areas. The runoff potential analysis on hydrographic basins, geographical units and altitude intervals highlights the variant spatial distribution of this general water resources indicator in the different studied areas.

Seasonal changes in the radiation balance of subarctic forest and tundra

International Nuclear Information System (INIS)

Lafleur, P.M.; Renzetti, A.V.; Bello, R.

1993-01-01

This paper examines the seasonal behavior of the components of the radiation budget of subarctic tundra and open forest near Churchill, Manitoba. Data were collected between late February and August 1990. The presence of the winter snowpack is the most important factor which affects the difference in radiation balances of tundra and forest. Overall, net radiation was about four to five times larger over the forest when snow covered the ground. Albedo differences were primarily responsible for this difference in net radiation; however, somewhat smaller net longwave losses were experienced at the tundra site. The step decrease in albedo from winter to summer (i.e. snow-covered to snow-free conditions) was significant at both sites. The forest albedo decreased by about three-fold while the tundra experienced a seven-fold decrease. Net radiation at both sites increased in direct response to the albedo change. Transmissivity of the atmosphere near Churchill also appeared to change at about the same time as the loss of the snow cover and may be related to changing air masses which bring about the final snow melt

[Ecological characteristics of phytoplankton in Suining tributary under bio-remediation].

Science.gov (United States)

Liu, Dongyan; Zhao, Jianfu; Zhang, Yalei; Ma, Limin

2005-04-01

Based on the analyses of phytoplankton community in the treated and untreated reaches of Suining tributary of Suzhou River, this paper studied the effects of bio-remediation on phytoplankton. As the result of the remediation, the density and Chl-a content of phytoplankton in treated reach were greatly declined, while the species number and Shannon-Wiener diversity index ascended obviously. The percentage of Chlorophyta and Baeillariophyta ascended, and some species indicating medium-and oligo-pollution were found. All of these illustrated that bio-remediation engineering might significantly benefit to the improvement of phytoplankton community structure and water quality.

Environmentally relevant chemical mixtures of concern in waters of United States tributaries to the Great Lakes

Science.gov (United States)

Elliott, Sarah M.; Brigham, Mark E.; Kiesling, Richard L.; Schoenfuss, Heiko L.; Jorgenson, Zachary G.

2018-01-01

The North American Great Lakes are a vital natural resource that provide fish and wildlife habitat, as well as drinking water and waste assimilation services for millions of people. Tributaries to the Great Lakes receive chemical inputs from various point and nonpoint sources, and thus are expected to have complex mixtures of chemicals. However, our understanding of the co‐occurrence of specific chemicals in complex mixtures is limited. To better understand the occurrence of specific chemical mixtures in the US Great Lakes Basin, surface water from 24 US tributaries to the Laurentian Great Lakes was collected and analyzed for diverse suites of organic chemicals, primarily focused on chemicals of concern (e.g., pharmaceuticals, personal care products, fragrances). A total of 181 samples and 21 chemical classes were assessed for mixture compositions. Basin wide, 1664 mixtures occurred in at least 25% of sites. The most complex mixtures identified comprised 9 chemical classes and occurred in 58% of sampled tributaries. Pharmaceuticals typically occurred in complex mixtures, reflecting pharmaceutical‐use patterns and wastewater facility outfall influences. Fewer mixtures were identified at lake or lake‐influenced sites than at riverine sites. As mixture complexity increased, the probability of a specific mixture occurring more often than by chance greatly increased, highlighting the importance of understanding source contributions to the environment. This empirically based analysis of mixture composition and occurrence may be used to focus future sampling efforts or mixture toxicity assessments. 

Differentiation of Municipalities in São Paulo State based on Constitutional Transferences and Income Tributary Taxes

Directory of Open Access Journals (Sweden)

Maria Aparecida Gouvêa

2009-04-01

Full Text Available This paper is part of a large study that combines several groups of municipalities in São Paulo State that are analyzed through multivariate statistical techniques. This study is intended to indicate whether the variables per capita transfer amounts from the Municipalities Participation Fund [MPF], Product and Service Circulation Tax Quota [ICMS] and collected tributary income have different average values among the municipalities of São Paulo State that present different economic and social situations according to the social responsibility index. The evaluation was carried out by multivariate analysis of variance. The results show that the tributary income has the greater difference of average among the groups. It was also found that MPF distribution criteria are applied differently and contribute to the available income fairness, giving support to local governments in the development of public policy.

The geochemistry of groundwater resources in the Jordan Valley: The impact of the Rift Valley brines

Science.gov (United States)

Farber, E.; Vengosh, A.; Gavrieli, I.; Marie, Amarisa; Bullen, T.D.; Mayer, B.; Polak, A.; Shavit, U.

2007-01-01

The chemical composition of groundwater in the Jordan Valley, along the section between the Sea of Galilee and the Dead Sea, is investigated in order to evaluate the origin of the groundwater resources and, in particular, to elucidate the role of deep brines on the chemical composition of the regional groundwater resources in the Jordan Valley. Samples were collected from shallow groundwater in research boreholes on two sites in the northern and southern parts of the Jordan Valley, adjacent to the Jordan River. Data is also compiled from previous published studies. Geochemical data (e.g., Br/Cl, Na/Cl and SO4/Cl ratios) and B, O, Sr and S isotopic compositions are used to define groundwater groups, to map their distribution in the Jordan valley, and to evaluate their origin. The combined geochemical tools enabled the delineation of three major sources of solutes that differentially affect the quality of groundwater in the Jordan Valley: (1) flow and mixing with hypersaline brines with high Br/Cl (>2 ?? 10-3) and low Na/Cl (shallow saline groundwaters influenced by brine mixing exhibit a north-south variation in their Br/Cl and Na/Cl ratios. This chemical trend was observed also in hypersaline brines in the Jordan valley, which suggests a local mixing process between the water bodies. ?? 2007 Elsevier Ltd. All rights reserved.

Impacts of twenty years of experimental warming on soil carbon, nitrogen, moisture and soil across alpine/subarctic tundra communities

DEFF Research Database (Denmark)

M. Alatalo, Juha; K. Jägerbrand, Annika; Juhanson, Jaanis

2017-01-01

High-altitude and alpine areas are predicted to experience rapid and substantial increases in future temperature, which may have serious impacts on soil carbon, nutrient and soil fauna. Here we report the impact of 20 years of experimental warming on soil properties and soil mites in three...... contrasting plant communities in alpine/subarctic Sweden. Long-term warming decreased juvenile oribatid mite density, but had no effect on adult oribatids density, total mite density, any major mite group or the most common species. Long-term warming also caused loss of nitrogen, carbon and moisture from...

Diazotrophy in alluvial meadows of subarctic river systems.

Directory of Open Access Journals (Sweden)

Thomas H DeLuca

Full Text Available There is currently limited understanding of the contribution of biological N2 fixation (diazotrophy to the N budget of large river systems. This natural source of N in boreal river systems may partially explain the sustained productivity of river floodplains in Northern Europe where winter fodder was harvested for centuries without fertilizer amendments. In much of the world, anthropogenic pollution and river regulation have nearly eliminated opportunities to study natural processes that shaped early nutrient dynamics of large river systems; however, pristine conditions in northern Fennoscandia allow for the retrospective evaluation of key biochemical processes of historical significance. We investigated biological N2 fixation (diazotrophy as a potential source of nitrogen fertility at 71 independent floodplain sites along 10 rivers and conducted seasonal and intensive analyses at a subset of these sites. Biological N2 fixation occurred in all floodplains, averaged 24.5 kg N ha(-1 yr(-1 and was down regulated from over 60 kg N ha(-1 yr(-1 to 0 kg N ha(-1 yr(-1 by river N pollution. A diversity of N2-fixing cyanobacteria was found to colonize surface detritus in the floodplains. The data provide evidence for N2 fixation to be a fundamental source of new N that may have sustained fertility at alluvial sites along subarctic rivers. Such data may have implications for the interpretation of ancient agricultural development and the design of contemporary low-input agroecosystems.

Channel planform change and detachment of tributary: A study on the Haora and Katakhal Rivers, Tripura, India

Science.gov (United States)

Bandyopadhyay, Shreya; Saha, Sushmita; Ghosh, Kapil; Kumar De, Sunil

2013-07-01

The main objective of the paper is to find the probable causes behind the shifting course of the Haora River, one of the major rivers of West Tripura and detachment of one of its major tributaries, the Katakhal River. From a recent satellite image, we observed that the River Haora has changed its course drastically near the confluence. Earlier, it used to take a sharp northward bend to meet with the River Titas immediately after crossing the Indo-Bangladesh border; but presently it is flowing westward to do so. Moreover, the Katakhal River, a right bank tributary of the River Haora, that used to flow through the northern side of the city of Agartala and meet with the River Haora at Bangladesh, is no longer a tributary of the Haora River. Now it is completely detached from the Haora River and meets with the River Titas separately. Spatiotemporal maps have been used to detect the changes. Field investigation, with the help of GPS, has been done in order to find the link between the Haora River and the Katakhal River within the Indian territory. Changing patterns of the Haora and Katakhal River confluences are also analysed, and earlier courses are identified. The shifting trends of both of these two rivers are found along the flanks of the interfluvial area because of microscale tectonic activity, i.e., upliftment of the interfluvial zone.

Potential Relationships Between Urban Development and the Trophic Status of Tampa Bay Tributaries and Lake Thonotosassa, Further the Potential Effect on Public Health

Science.gov (United States)

MorenoMadrinan, Max J.; Allhamdan, Mohammad; Rickman, Douglas L.; Estes, Maury

2010-01-01

This slide presentation reviews the use of remote sensing to monitor the relationships between the urban development and water quality in Tampa Bay and the tributaries. It examines the changes in land cover/land use (LU/LC) and the affects that this change has on the water quality of Tampa Bay, Lake Thonotosassa and the tributaries, and that shows the ways that these changes can be estimated with remote sensing.

Application of global datasets for hydrological modelling of a remote, snowmelt driven catchment in the Canadian Sub-Arctic

Science.gov (United States)

Casson, David; Werner, Micha; Weerts, Albrecht; Schellekens, Jaap; Solomatine, Dimitri

2017-04-01

Hydrological modelling in the Canadian Sub-Arctic is hindered by the limited spatial and temporal coverage of local meteorological data. Local watershed modelling often relies on data from a sparse network of meteorological stations with a rough density of 3 active stations per 100,000 km2. Global datasets hold great promise for application due to more comprehensive spatial and extended temporal coverage. A key objective of this study is to demonstrate the application of global datasets and data assimilation techniques for hydrological modelling of a data sparse, Sub-Arctic watershed. Application of available datasets and modelling techniques is currently limited in practice due to a lack of local capacity and understanding of available tools. Due to the importance of snow processes in the region, this study also aims to evaluate the performance of global SWE products for snowpack modelling. The Snare Watershed is a 13,300 km2 snowmelt driven sub-basin of the Mackenzie River Basin, Northwest Territories, Canada. The Snare watershed is data sparse in terms of meteorological data, but is well gauged with consistent discharge records since the late 1970s. End of winter snowpack surveys have been conducted every year from 1978-present. The application of global re-analysis datasets from the EU FP7 eartH2Observe project are investigated in this study. Precipitation data are taken from Multi-Source Weighted-Ensemble Precipitation (MSWEP) and temperature data from Watch Forcing Data applied to European Reanalysis (ERA)-Interim data (WFDEI). GlobSnow-2 is a global Snow Water Equivalent (SWE) measurement product funded by the European Space Agency (ESA) and is also evaluated over the local watershed. Downscaled precipitation, temperature and potential evaporation datasets are used as forcing data in a distributed version of the HBV model implemented in the WFLOW framework. Results demonstrate the successful application of global datasets in local watershed modelling, but

Examining the relationship between mercury and organic matter in lake sediments along a latitudinal transect in subarctic Canada

Science.gov (United States)

Galloway, Jennifer M.; Sanei, Hamed; Parsons, Michael; Swindles, Graeme T.; Macumber, Andrew L.; Patterson, R. Timothy; Palmer, Michael; Falck, Hendrik

2016-04-01

The accumulation of Hg in aquatic environments at both high and low latitudes can be controlled by organic matter through algal scavenging, thus complicating the interpretation of historical Hg profiles in lake sediments1,2,3. However, other recent studies suggest that algal scavenging is not important in governing Hg flux to sediments4, in some cases because of dilution by inorganic materials5. This study examines relationships between Hg and organic matter (OM) in over 100 lakes located between 60.5 and 65.4 °N and crossing the latitudinal tree-line in subarctic Canada. The latitudinal gradient approach in our study offers an opportunity to better understand climate and environmental controls on OM accumulation and its role in influencing Hg deposition in subarctic lacustrine environments. We used Rock Eval 6 pyrolysis to determine total organic carbon (TOC%), S1 (soluble OM consisting of degradable lipids and algal pigments), S2 (OM derived from highly aliphatic biomacromolecule structure of algal cell walls), and S3 (OM dominated by carbohydrates, lignins, and plant materials). Total Hg in sediments was measured using thermal decomposition, amalgamation, and atomic absorption spectrophotometry. In these lake sediments, S2 composes the majority of TOC (Pearson's r = 0.978, porganic matter and mercury in recent lake sediment: the physical-geochemical aspects. Appl Geochem 21: 1900-12. 2Outridge, P.M., Sanei, H., Stern, G.A., Hamilton, P.B., Goodarzi, F. 2007. Evidence for control of mercury accumulation rates in Canadian high Arctic lake sediments by variations of aquatic primary productivity. Environ Sci Technol 41: 5259-65. 3Wu, F., Zu, L., Liao, H., Guo, F., Zhao, X., Giesy, J. 2013. Relationship between mercury and organic carbon in sediment cores from Lakes Qinghai and Chenghai, China. J Soils Sediments 13: 1084-1092.4Kirk, J.L., Muir, D.C.G., Antoniades, D., Douglas, M.S.V., Evans, M.S., Jackson, T.A., Kling, H., Lamoureux, S., Lim, D.S.S., Pienitz, R

27 CFR 9.27 - Lime Kiln Valley.

Science.gov (United States)

2010-04-01

... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Lime Kiln Valley. 9.27... OF THE TREASURY LIQUORS AMERICAN VITICULTURAL AREAS Approved American Viticultural Areas § 9.27 Lime Kiln Valley. (a) Name. The name of the viticultural area described in this section is “Lime Kiln Valley...

A valley-filtering switch based on strained graphene.

Science.gov (United States)

Zhai, Feng; Ma, Yanling; Zhang, Ying-Tao

2011-09-28

We investigate valley-dependent transport through a graphene sheet modulated by both the substrate strain and the fringe field of two parallel ferromagnetic metal (FM) stripes. When the magnetizations of the two FM stripes are switched from the parallel to the antiparallel alignment, the total conductance, valley polarization and valley conductance excess change greatly over a wide range of Fermi energy, which results from the dependence of the valley-related transmission suppression on the polarity configuration of inhomogeneous magnetic fields. Thus the proposed structure exhibits the significant features of a valley-filtering switch and a magnetoresistance device.

A valley-filtering switch based on strained graphene

International Nuclear Information System (INIS)

Zhai Feng; Ma Yanling; Zhang Yingtao

2011-01-01

We investigate valley-dependent transport through a graphene sheet modulated by both the substrate strain and the fringe field of two parallel ferromagnetic metal (FM) stripes. When the magnetizations of the two FM stripes are switched from the parallel to the antiparallel alignment, the total conductance, valley polarization and valley conductance excess change greatly over a wide range of Fermi energy, which results from the dependence of the valley-related transmission suppression on the polarity configuration of inhomogeneous magnetic fields. Thus the proposed structure exhibits the significant features of a valley-filtering switch and a magnetoresistance device. (paper)

Electrical valley filtering in transition metal dichalcogenides

Science.gov (United States)

Hsieh, Tzu-Chi; Chou, Mei-Yin; Wu, Yu-Shu

2018-03-01

This work investigates the feasibility of electrical valley filtering for holes in transition metal dichalcogenides. We look specifically into the scheme that utilizes a potential barrier to produce valley-dependent tunneling rates, and perform the study with both a k .p -based analytic method and a recursive Green's function-based numerical method. The study yields the transmission coefficient as a function of incident energy and transverse wave vector, for holes going through lateral quantum barriers oriented in either armchair or zigzag directions, in both homogeneous and heterogeneous systems. The main findings are the following: (1) The tunneling current valley polarization increases with increasing barrier width or height; (2) both the valley-orbit interaction and band structure warping contribute to valley-dependent tunneling, with the former contribution being manifest in structures with asymmetric potential barriers, and the latter being orientation dependent and reaching maximum for transmission in the armchair direction; and (3) for transmission ˜0.1 , a tunneling current valley polarization of the order of 10 % can be achieved.

Water resources of Parowan Valley, Iron County, Utah

Science.gov (United States)

Marston, Thomas M.

2017-08-29

Parowan Valley, in Iron County, Utah, covers about 160 square miles west of the Red Cliffs and includes the towns of Parowan, Paragonah, and Summit. The valley is a structural depression formed by northwest-trending faults and is, essentially, a closed surface-water basin although a small part of the valley at the southwestern end drains into the adjacent Cedar Valley. Groundwater occurs in and has been developed mainly from the unconsolidated basin-fill aquifer. Long-term downward trends in groundwater levels have been documented by the U.S. Geological Survey (USGS) since the mid-1950s. The water resources of Parowan Valley were assessed during 2012 to 2014 with an emphasis on refining the understanding of the groundwater and surface-water systems and updating the groundwater budget.Surface-water discharge of five perennial mountain streams that enter Parowan Valley was measured from 2013 to 2014. The total annual surface-water discharge of the five streams during 2013 to 2014 was about 18,000 acre-feet (acre-ft) compared to the average annual streamflow of about 22,000 acre-ft from USGS streamgages operated on the three largest of these streams from the 1940s to the 1980s. The largest stream, Parowan Creek, contributes more than 50 percent of the annual surface-water discharge to the valley, with smaller amounts contributed by Red, Summit, Little, and Cottonwood Creeks.Average annual recharge to the Parowan Valley groundwater system was estimated to be about 25,000 acre-ft from 1994 to 2013. Nearly all recharge occurs as direct infiltration of snowmelt and rainfall on the Markagunt Plateau east of the valley. Smaller amounts of recharge occur as infiltration of streamflow and unconsumed irrigation water near the east side of the valley on alluvial fans associated with mountain streams at the foot of the Red Cliffs. Subsurface flow from the mountain block to the east of the valley is a significant source of groundwater recharge to the basin-fill aquifer

Temporal changes of meadow and peatbog vegetation in the landscape of a small-scale river valley in Central Roztocze

Directory of Open Access Journals (Sweden)

Bożenna Czarnecka

2015-07-01

Full Text Available The Szum is a right-side tributary of the Tanew River crossing the southern escarpment zone of the Central Roztocze region (SE Poland. Downstream of the strict river break in a section between the 10th and 12th km of the river course in the Szum valley, meadow and peatbog complexes have developed, associated with semi-hydrogenic and marshy soils. In an area of approx. 13 ha of the most valuable non-forest habitats, a variety of plant communities have been identified, including habitats of the Natura 2000 network and habitats that are protected under the Regulation of the Minister of the Environment (2001. These are, for instance, meadow associations Lysimachio vulgaris-Filipenduletum, Lythro-Filipenduletum, Filipendulo ulmariae-Menthetum longifoliae, Angelico-Cirsietum oleracei, and Cirsietum rivularis. The moss–sedge and sphagnum bog communities comprise noteworthy associations Caricetum limosae, Rhynchosporetum albae, Caricetum lasiocarpae, Caricetum paniceo-lepidocarpae, Caricetum davallianae, and Sphagnetum magellanici. These communities are composed of ca. 160 vascular plant species and 40 moss and liverwort species. In 1999–2014, the greatest changes occurred within macroforb meadows, i.e. small Angelico-Cirsietum oleracei and Cirsietum rivularis patches have been transformed into Lysimachio vulgaris-Filipenduletum, while some patches of the latter association have been transformed into a Caricetum acutiformis rush. Several patches of bog-spring associations Caricetum paniceo-lepidocarpae and Carici canescentis-Agrostietum caninae have been irretrievably destroyed. Sphagnetum magellanici appears to be the least stable community among the preserved peatbogs. The changes of meadow and peatbog vegetation observed for the last 15 years are a consequence of natural processes that take place in the river valley and to a large extent human activity connected with the so-called small-scale water retention as well as the presence of a beaver

EPA Region 1 - Valley Depth in Meters

Science.gov (United States)

Raster of the Depth in meters of EPA-delimited Valleys in Region 1.Valleys (areas that are lower than their neighbors) were extracted from a Digital Elevation Model (USGS, 30m) by finding the local average elevation, subtracting the actual elevation from the average, and selecting areas where the actual elevation was below the average. The landscape was sampled at seven scales (circles of 1, 2, 4, 7, 11, 16, and 22 km radius) to take into account the diversity of valley shapes and sizes. Areas selected in at least four scales were designated as valleys.

Socio-economic status and environmental problems affecting the fishermen along the river tributaries of Dagupan City

Directory of Open Access Journals (Sweden)

Sally A. Jarin

2018-02-01

Full Text Available This study was conducted to determine the socio-economic status of the fishermen along the river tributaries of Dagupan City and to study the environment problems affecting the fishermen along the river tributaries of Dagupan City. This study used a mixed method research design and utilized a survey questionnaire to gather response from 60 fishers selected through proportionate sampling. The fishermen along the tributaries of Dagupan City are mostly male, young adult with family of their own, attended primary education, and belong to big family size. All respondents owned houses made only of light materials. Shrimps and crabs were the most frequently caught species now compared to many small pelagic fishes before, when there were no aquaculture structures like fish pens and cages. Fishermen were limited to the ownership of passive fishing gears like gill nets, skylab, skyblue, and liftnet. Fishpen or cage structures were owned by big businessmen while the fishers served only as caretakers. The respondents are worried on the decrease of fish catch. It is recommended that the government of the City of Dagupan should continue its program in demolishing pen and cage structures to free the rivers from pollution of feed inputs. Management and economic measures should be considered in order to gain significant effect on income of the fishermen. In designing management systems which have income improvement as a goal, appropriate implementation, monitoring and evaluation initiatives should be conducted and taken cared of for sustainable income improvement of farmers in the community of Dagupan and, perhaps, wealth distribution.

Preliminary hydrogeologic assessment near the boundary of the Antelope Valley and El Mirage Valley groundwater basins, California

Science.gov (United States)

Stamos, Christina L.; Christensen, Allen H.; Langenheim, Victoria

2017-07-19

The increasing demands on groundwater for water supply in desert areas in California and the western United States have resulted in the need to better understand groundwater sources, availability, and sustainability. This is true for a 650-square-mile area that encompasses the Antelope Valley, El Mirage Valley, and Upper Mojave River Valley groundwater basins, about 50 miles northeast of Los Angeles, California, in the western part of the Mojave Desert. These basins have been adjudicated to ensure that groundwater rights are allocated according to legal judgments. In an effort to assess if the boundary between the Antelope Valley and El Mirage Valley groundwater basins could be better defined, the U.S. Geological Survey began a cooperative study in 2014 with the Mojave Water Agency to better understand the hydrogeology in the area and investigate potential controls on groundwater flow and availability, including basement topography.Recharge is sporadic and primarily from small ephemeral washes and streams that originate in the San Gabriel Mountains to the south; estimates range from about 400 to 1,940 acre-feet per year. Lateral underflow from adjacent basins has been considered minor in previous studies; underflow from the Antelope Valley to the El Mirage Valley groundwater basin has been estimated to be between 100 and 1,900 acre-feet per year. Groundwater discharge is primarily from pumping, mostly by municipal supply wells. Between October 2013 and September 2014, the municipal pumpage in the Antelope Valley and El Mirage Valley groundwater basins was reported to be about 800 and 2,080 acre-feet, respectively.This study was motivated by the results from a previously completed regional gravity study, which suggested a northeast-trending subsurface basement ridge and saddle approximately 3.5 miles west of the boundary between the Antelope Valley and El Mirage Valley groundwater basins that might influence groundwater flow. To better define potential basement

Optically initialized robust valley-polarized holes in monolayer WSe2

KAUST Repository

Hsu, Wei-Ting

2015-11-25

A robust valley polarization is a key prerequisite for exploiting valley pseudospin to carry information in next-generation electronics and optoelectronics. Although monolayer transition metal dichalcogenides with inherent spin–valley coupling offer a unique platform to develop such valleytronic devices, the anticipated long-lived valley pseudospin has not been observed yet. Here we demonstrate that robust valley-polarized holes in monolayer WSe2 can be initialized by optical pumping. Using time-resolved Kerr rotation spectroscopy, we observe a long-lived valley polarization for positive trion with a lifetime approaching 1 ns at low temperatures, which is much longer than the trion recombination lifetime (~10–20 ps). The long-lived valley polarization arises from the transfer of valley pseudospin from photocarriers to resident holes in a specific valley. The optically initialized valley pseudospin of holes remains robust even at room temperature, which opens up the possibility to realize room-temperature valleytronics based on transition metal dichalcogenides.

Valley-orbit hybrid states in Si quantum dots

Science.gov (United States)

Gamble, John; Friesen, Mark; Coppersmith, S. N.

2013-03-01

The conduction band for electrons in layered Si nanostructures oriented along (001) has two low-lying valleys. Most theoretical treatments assume that these valleys are decoupled from the long-wavelength physics of electron confinement. In this work, we show that even a minimal amount of disorder (a single atomic step at the quantum well interface) is sufficient to mix valley states and electron orbitals, causing a significant distortion of the long-wavelength electron envelope. For physically realistic electric fields and dot sizes, this valley-orbit coupling impacts all electronic states in Si quantum dots, implying that one must always consider valley-orbit hybrid states, rather than distinct valley and orbital degrees of freedom. We discuss the ramifications of our results on silicon quantum dot qubits. This work was supported in part by ARO (W911NF-08-1-0482) and NSF (DMR-0805045).

Quality of groundwater and surface water, Wood River Valley, south-central Idaho, July and August 2012

Science.gov (United States)

Hopkins, Candice B.; Bartolino, James R.

2013-01-01

Residents and resource managers of the Wood River Valley of south-central Idaho are concerned about the effects that population growth might have on the quality of groundwater and surface water. As part of a multi-phase assessment of the groundwater resources in the study area, the U.S. Geological Survey evaluated the quality of water at 45 groundwater and 5 surface-water sites throughout the Wood River Valley during July and August 2012. Water samples were analyzed for field parameters (temperature, pH, specific conductance, dissolved oxygen, and alkalinity), major ions, boron, iron, manganese, nutrients, and Escherichia coli (E.coli) and total coliform bacteria. This study was conducted to determine baseline water quality throughout the Wood River Valley, with special emphasis on nutrient concentrations. Water quality in most samples collected did not exceed U.S. Environmental Protection Agency standards for drinking water. E. coli bacteria, used as indicators of water quality, were detected in all five surface-water samples and in two groundwater samples collected. Some analytes have aesthetic-based recommended drinking water standards; one groundwater sample exceeded recommended iron concentrations. Nitrate plus nitrite concentrations varied, but tended to be higher near population centers and in agricultural areas than in tributaries and less populated areas. These higher nitrate plus nitrite concentrations were not correlated with boron concentrations or the presence of bacteria, common indicators of sources of nutrients to water. None of the samples collected exceeded drinking-water standards for nitrate or nitrite. The concentration of total dissolved solids varied considerably in the waters sampled; however a calcium-magnesium-bicarbonate water type was dominant (43 out of 50 samples) in both the groundwater and surface water. Three constituents that may be influenced by anthropogenic activity (chloride, boron, and nitrate plus nitrite) deviate from this

Fertility status of cultivated floodplain soils in the Zambezi Valley, northern Zimbabwe

Science.gov (United States)

Chimweta, M.; Nyakudya, I. W.; Jimu, L.

2018-06-01

Flood-recession cropping improves smallholder farmers' household food security. The objective of this study was to determine the fertility status of cultivated Zambezi Valley floodplain soils, in northern Zimbabwe. The study was conducted at three sites, along tributaries of Musengezi River. Soil samples were taken at 0.20 m depth increments to 0.60 m from hydromorphologically stratified fields, during the cropping season. Sampling points were replicated twice in each stratum at points equidistant from river edges. Relative elevations of sampling points were measured using levelling equipment. Soil was analysed using: core method for bulk density, hydrometer method for texture, loss on ignition for soil organic carbon (SOC), Kjeldahl procedure for total nitrogen (N), 0.01 M CaCl2 for pH, and Inductively Coupled Plasma (ICP) for Mehlich 3 extractable elements. Data from soil analyses were subjected to One Way Analysis of Variance and Pearson's correlation analysis. Bulk density ranged from 1.2 to 1.4 g cm-3 and it was negatively related to distance from river; and positively related to elevation at two sites. Highest values for SOC and total N were 2.04% and 0.36% respectively. Soil pH ranged from 7.70 to 8.60. Soil organic carbon and N were positively related to distance from river but negatively related to elevation. Threshold concentrations for deficiency: fertilizer microdosing are among possible fertility management options.

Fena Valley Reservoir watershed and water-balance model updates and expansion of watershed modeling to southern Guam

Science.gov (United States)

Rosa, Sarah N.; Hay, Lauren E.

2017-12-01

measured values for the gaging stations on the Almagosa, Maulap, and Imong Rivers—tributaries to the Fena Valley Reservoir—with Nash-Sutcliffe efficiency values of 0.87 or higher. The southern Guam watershed model simulated the total volume of the critical dry season (January to May) streamflow for the entire simulation period within –0.54 percent at the Almagosa River, within 6.39 percent at the Maulap River, and within 6.06 percent at the Imong River.The recalibrated water-balance model of the Fena Valley Reservoir generally simulated monthly reservoir storage volume with reasonable accuracy. For the calibration and verification periods, errors in end-of-month reservoir-storage volume ranged from 6.04 percent (284.6 acre-feet or 92.7 million gallons) to –5.70 percent (–240.8 acre-feet or –78.5 million gallons). Monthly simulation bias ranged from –0.48 percent for the calibration period to 0.87 percent for the verification period; relative error ranged from –0.60 to 0.88 percent for the calibration and verification periods, respectively. The small bias indicated that the model did not consistently overestimate or underestimate reservoir storage volume.In the entirety of southern Guam, the watershed model has a “satisfactory” to “very good” rating when simulating monthly mean streamflow for all but one of the gaged watersheds during the verification period. The southern Guam watershed model uses a more sophisticated climate-distribution scheme than the older model to make use of the sparse climate data, as well as includes updated land-cover parameters and the capability to simulate closed depression areas.The new Fena Valley Reservoir water-balance model is useful as an updated tool to forecast short-term changes in the surface-water resources of Guam. Furthermore, the now spatially complete southern Guam watershed model can be used to evaluate changes in streamflow and recharge owing to climate or land-cover changes. These are substantial

Development and application of sedimentary pigments for assessing effects of climatic and environmental changes on subarctic lakes in northern Sweden

DEFF Research Database (Denmark)

Reuss, Nina Steenberg; Leavitt, Peter R.; Hall, Roland I.

2010-01-01

to the modern tree line. The spatial survey of sedimentary pigments was analyzed using principle components analysis (PCA) and redundancy analysis (RDA). PCA explained 73-83% of variance in pigment abundance and composition, whereas RDA explained 22-32% of variation in fossil assemblages. Dissolved organic...... transitions in the phototrophic community during the late Holocene were less easily interpreted. Terrestrial vegetation development thus appears to be of utmost importance for the regulation of primary production in oligotrophic alpine and subarctic lakes and climate impacts on lakes, whereas other basin...

California's Central Valley Groundwater Study: A Powerful New Tool to Assess Water Resources in California's Central Valley

Science.gov (United States)

Faunt, Claudia C.; Hanson, Randall T.; Belitz, Kenneth; Rogers, Laurel

2009-01-01

Competition for water resources is growing throughout California, particularly in the Central Valley. Since 1980, the Central Valley's population has nearly doubled to 3.8 million people. It is expected to increase to 6 million by 2020. Statewide population growth, anticipated reductions in Colorado River water deliveries, drought, and the ecological crisis in the Sacramento-San Joaquin Delta have created an intense demand for water. Tools and information can be used to help manage the Central Valley aquifer system, an important State and national resource.

Treatability study on the Bear Creek Valley characterization area at the Oak Ridge Y-12 Plant, Oak Ridge, Tennessee. Phase II work plan for S-3 site contaminated groundwater interception--in-field media evaluation and groundwater capture methods

International Nuclear Information System (INIS)

1996-12-01

A treatability study is being conducted to support implementation:of early actions at the S-3 Site in the Bear Creek Valley (BCV) Characterization Area (CA). The objectives of the early actions Will be (1) to reduce concentrations of uranium and nitrate in Bear Creek and (2) to reduce contaminants of concern in North Tributary (NT)-1 and NT-2. The BCV CA is located within the US DOE's Oak Ridge Reservation in Tennessee. Hazardous and radioactive materials from the Y-12 Plant operations were, disposed of at various sites within BCV. Groundwater and surface water in the BCV CA have been contaminated. The remedial investigation (RI) for the BCV CA identified that the greatest mass flux of contaminants from the various sources migrates via groundwater at the source and discharges to surface water in Bear Creek and its tributaries. In the RI, the combined discharge from the S-3 Site and the Boneyard/Burnyard (BYBY) was identified as accounting for 75% of the cancer risk and more than 80% of the chemical toxicity to Potential downgradient human receptors. In addition, the S-3 Site has caused degradation of surface water quality in upper Bear Creek and two of its tributaries. The BCV CA treatability study focuses on capture and treatment of shallow groundwater before it discharges to tributary waters. The objectives Of treatment of this groundwater are (1) to reduce the concentrations of uranium and nitrate in NT-1 and Bear Creek such that the concentrations of these chemicals in surface water and groundwater are reduced to acceptable levels, (2) to reduce the concentrations of nitrate and metals, and reduce the overall concentration of total dissolved solids; and (3) to hydraulically contain the plume of contaminated, groundwater that is moving in bedrock in the Nolichucky Shale such that the rate of contaminant discharge will be reduced in the long term. The objective of Phase II is to produce conceptual designs for treatment system configurations

Wetland development, permafrost history and nutrient cycling inferred from late Holocene peat and lake sediment records in subarctic Sweden

DEFF Research Database (Denmark)

Kokfelt, U.; Reuss, N.; Struyf, E.

2010-01-01

to re-deposition of peat into one of the lakes after ca. 2,100 cal BP, and stimulated primary productivity in the other lake at ca. 1,900-1,800 cal BP. Carbonate precipitation appears to have been suppressed when acidic poor fen and bog (palsa) communities dominated the catchment mire, and permafrost...... insight into nutrient and permafrost dynamics in a subarctic wetland and imply that continued permafrost decay and related vegetation changes towards minerotrophy may increase carbon and nutrient storage of mire deposits and reduce nutrient fluxes in runoff. Rapid permafrost degradation may on the other...

Valley and spin thermoelectric transport in ferromagnetic silicene junctions

International Nuclear Information System (INIS)

Ping Niu, Zhi; Dong, Shihao

2014-01-01

We have investigated the valley and spin resolved thermoelectric transport in a normal/ferromagnetic/normal silicene junction. Due to the coupling between the valley and spin degrees of freedom, thermally induced pure valley and spin currents can be demonstrated. The magnitude and sign of these currents can be manipulated by adjusting the ferromagnetic exchange field and local external electric field, thus the currents are controllable. We also find fully valley and/or spin polarized currents. Similar to the currents, owing to the band structure symmetry, tunable pure spin and/or valley thermopowers with zero charge counterpart are generated. The results obtained here suggest a feasible way of generating a pure valley (spin) current and thermopower in silicene

Some factors effecting algal consumption in subarctic Ephemeroptera, Plecoptera, and Simuliidae

Energy Technology Data Exchange (ETDEWEB)

Moore, J.W.

1977-01-01

Some of the factors influencing algal consumption in the mayflies Leptophlebia nebulosa, Cinygmula tarda, Baetis foemina and B. cf. bicaudatus, the plecopterans Arcynopteryx signata, Nemoura cinctipes and N. oregonensis and in the dipterans Simulium arcticum, S. venustum and S. decorum were investigated between June 1975 and June 1976 in several streams in the Canadian subarctic. Algae represented up to 65% of the gut contents of L. nebulosa but only 0--8% in the other mayflies. They were important in the plecopterans (85--90%) but less so (2--13%) in the simuliids. Most of the interspecies variability in algal consumption could be explained in terms of food availability. This factor was in turn dependent on the density and attachment characteristics of the flora and the strength of their cell wall. Feeding intensity in most species was low between October and April, reaching it peak in July and August. From 51 to 83% of intraspecies feeding variability was due to changing temperature, followed in importance by water velocity in the dipterans and food availability in the mayflies. All species in this latter group ceased feeding in the final instar stages.

Wintertime pytoplankton bloom in the Subarctic Pacific supportedby continental margin iron

Energy Technology Data Exchange (ETDEWEB)

Lam, Phoebe J.; Bishop, James K.B.; Henning, Cara C.; Marcus,Matthew A.; Waychunas, Glenn A.; Fung, Inez

2004-06-08

Heightened biological activity was observed in February 1996in the high-nutrient low-chlorophyll (HNLC) subarctic North PacificOcean, a region that is thought to beiron-limited. Here we provideevidence supporting the hypothesis that Ocean Station Papa (OSP) in thesubarctic Pacific received a lateral supply of particulate iron from thecontinental margin off the Aleutian Islands in the winter, coincidentwith the observed biological bloom. Synchrotron X-ray analysis was usedto describe the physical form, chemistry, and depth distributions of ironin size fractionated particulate matter samples. The analysis revealsthat discrete micron-sized iron-rich hotspots are ubiquitous in the upper200m at OSP, more than 900km from the closest coast. The specifics of thechemistry and depth profiles of the Fe hot spots trace them to thecontinental margins. We thus hypothesize that iron hotspots are a markerfor the delivery of iron from the continental margin. We confirm thedelivery of continental margin iron to the open ocean using an oceangeneral circulation model with an iron-like tracer source at thecontinental margin. We suggest that iron from the continental marginstimulated a wintertime phytoplankton bloom, partially relieving the HNLCcondition.

Distributions and seasonal abundances of krill eggs and larvae in the sub-Arctic Godthåbsfjord, SW Greenland

DEFF Research Database (Denmark)

Teglhus, Frederik Wolff; Agersted, Mette Dalgaard; Akther, Hasna

2015-01-01

The larval krill community (Thysanoessa spp.) was investigated along the sub-Arctic Godthåbsfjord, SW Greenland, in June 2010. In addition, the progress of krill development from egg to furcilia was studied from March to August 2010 in a fjord branching off the Godthåbsfjord. Krill spawned from...... and furcilia stages lasted 22 and 63 d, respectively. The growth rate from metanauplius to calyptopis was 0.12 d−1, while the growth rate across all developmental stages was 0.05 d−1. Mortality rates were calculated as 25% from eggs to nauplii, 48% from eggs to calyptopes and 83% from eggs to furcilia. During...

Anatomical structure overrides temperature controls on magnesium uptake - calcification in the Arctic/subarctic coralline algae Leptophytum laeve and Kvaleya epilaeve (Rhodophyta; Corallinales)

Science.gov (United States)

Nash, Merinda C.; Adey, Walter

2018-02-01

Calcified coralline red algae are ecologically key organisms in photic benthic environments. In recent decades they have become important climate proxies, especially in the Arctic and subarctic. It has been widely accepted that magnesium content in coralline tissues is directly a function of ambient temperature, and this is a primary basis for their value as a climate archive. In this paper we show for two genera of Arctic/subarctic corallines, Leptophytum laeve and Kvaleya epilaeve, that previously unrecognised complex tissue and cell wall anatomy bears a variety of basal signatures for Mg content, with the accepted temperature relationship being secondary. The interfilament carbonate has lower Mg than adjacent cell walls and the hypothallial cell walls have the highest Mg content. The internal structure of the hypothallial cell walls can differ substantially from the perithallial radial cell wall structure. Using high-magnification scanning electron microscopy and etching we expose the nanometre-scale structures within the cell walls and interfilament. Fibrils concentrate at the internal and external edges of the cell walls. Fibrils ˜ 10 nm thick appear to thread through the radial Mg-calcite grains and form concentric bands within the cell wall. This banding may control Mg distribution within the cell. Similar fibril banding is present in the hypothallial cell walls but not the interfilament. Climate archiving with corallines can achieve greater precision with recognition of these parameters.

Organochlorine residues in sediments from selected tributaries to Manila Bay, Philippines

International Nuclear Information System (INIS)

Bajet, C.M.; Varca, L.M.; Navarro, M.P.

1999-01-01

Sediment borne pesticides are the major route of transport of pesticides in the marine environment and benthic dwellers, filter feeders and the flora/fauna closely associated with the sediments could greatly be affected. This paper focuses on the monitoring of organochlorine pesticides in sediments collected from the mouth of rivers draining to Manila Bay and relate to the contribution of inland activities to the overall pollution of the Bay. Sediments from 14-25 tributaries were collected in 1996 to 1998 and analyzed for the presence of HCB, aldrin, dieldrin, lindane, DDT, DDE, DDD, endosulfan I, endosulfan II and endosulfan sulfate using GLC-ECD

Engineering assessment of inactive uranium mill tailings: Monument Valley Site, Monument Valley, Arizona

Energy Technology Data Exchange (ETDEWEB)

1981-10-01

Ford, Bacon and Davis Utah Inc. has reevalated the Monument Valley site in order to revise the March 1977 engineering assessment of the problems resulting from the existence of radioactive uranium mill tailings at Monument Valley, Arizona. This engineering assessment has included the preparation of topographic maps, the performance of core drillings and radiometric measurements sufficient to determine areas and volumes of tailings and radiation exposure of individuals and nearby populations, the investigations of site hydrology and meteorology, and the evaluation and costing of alternative corrective actions. Radon gas released from the 1.1 million tons of tailings at the Monument Valley site constitutes the most significant environmental impact, although windblown tailings and external gamma radiation also are factors. The four alternative actions presented in this engineering assessment range from millsite decontamination with the addition of 3 m of stabilization cover material (Option I), to removal of the tailings to remote disposal sites and decontamination of the tailings site (Options II through IV). Cost estimates for the four options range from about $6,600,000 for stabilization in-place, to about $15,900,000 for disposal at a distance of about 15 mi. Three principal alternatives for reprocessing the Monument Valley tailings were examined: heap leaching; Treatment at an existing mill; and reprocessing at a new conventional mill constructed for tailings reprocessing. The cost of the uranium recovery is economically unattractive.

Engineering assessment of inactive uranium mill tailings: Monument Valley Site, Monument Valley, Arizona

International Nuclear Information System (INIS)

1981-10-01

Ford, Bacon and Davis Utah Inc. has reevalated the Monument Valley site in order to revise the March 1977 engineering assessment of the problems resulting from the existence of radioactive uranium mill tailings at Monument Valley, Arizona. This engineering assessment has included the preparation of topographic maps, the performance of core drillings and radiometric measurements sufficient to determine areas and volumes of tailings and radiation exposure of individuals and nearby populations, the investigations of site hydrology and meteorology, and the evaluation and costing of alternative corrective actions. Radon gas released from the 1.1 million tons of tailings at the Monument Valley site constitutes the most significant environmental impact, although windblown tailings and external gamma radiation also are factors. The four alternative actions presented in this engineering assessment range from millsite decontamination with the addition of 3 m of stabilization cover material (Option I), to removal of the tailings to remote disposal sites and decontamination of the tailings site (Options II through IV). Cost estimates for the four options range from about $6,600,000 for stabilization in-place, to about $15,900,000 for disposal at a distance of about 15 mi. Three principal alternatives for reprocessing the Monument Valley tailings were examined: heap leaching; Treatment at an existing mill; and reprocessing at a new conventional mill constructed for tailings reprocessing. The cost of the uranium recovery is economically unattractive

Sustainable agricultural development in inland valleys

NARCIS (Netherlands)

Zwart, S.J.

2018-01-01

The inland valley in Africa are common landscapes that have favorable conditions for agricultural production. Compared to the surrounding uplands they are characterized by a relatively high and secure water availability and high soil fertility levels. Inland valleys thus have a high agricultural

Approaches to restoration of oak forests on farmed lowlands of the Mississippi River and its tributaries

Science.gov (United States)

Emile S. Gardiner; Daniel C. Dey; John A. Stanturf; Brian Roy. Lockhart

2010-01-01

The lowlands associated with the Mississippi River and its tributaries historically supported extensive broadleaf forests that were particularly rich in oak (Quercus spp.) species. Beginning in the 1700s, deforestation for agriculture substantially reduced the extent of the original forest, and fragmented the remainder into small parcels. More...

Valley-polarized quantum transport generated by gauge fields in graphene

Science.gov (United States)

Settnes, Mikkel; Garcia, Jose H.; Roche, Stephan

2017-09-01

We report on the possibility to simultaneously generate in graphene a bulk valley-polarized dissipative transport and a quantum valley Hall effect by combining strain-induced gauge fields and real magnetic fields. Such unique phenomenon results from a ‘resonance/anti-resonance’ effect driven by the superposition/cancellation of superimposed gauge fields which differently affect time reversal symmetry. The onset of a valley-polarized Hall current concomitant to a dissipative valley-polarized current flow in the opposite valley is revealed by a {{e}2}/h Hall conductivity plateau. We employ efficient linear scaling Kubo transport methods combined with a valley projection scheme to access valley-dependent conductivities and show that the results are robust against disorder.

Groundwater availability of the Central Valley Aquifer, California

Science.gov (United States)

Faunt, Claudia C.

2009-01-01

California's Central Valley covers about 20,000 square miles and is one of the most productive agricultural regions in the world. More than 250 different crops are grown in the Central Valley with an estimated value of $17 billion per year. This irrigated agriculture relies heavily on surface-water diversions and groundwater pumpage. Approximately one-sixth of the Nation's irrigated land is in the Central Valley, and about one-fifth of the Nation's groundwater demand is supplied from its aquifers. The Central Valley also is rapidly becoming an important area for California's expanding urban population. Since 1980, the population of the Central Valley has nearly doubled from 2 million to 3.8 million people. The Census Bureau projects that the Central Valley's population will increase to 6 million people by 2020. This surge in population has increased the competition for water resources within the Central Valley and statewide, which likely will be exacerbated by anticipated reductions in deliveries of Colorado River water to southern California. In response to this competition for water, a number of water-related issues have gained prominence: conservation of agricultural land, conjunctive use, artificial recharge, hydrologic implications of land-use change, and effects of climate variability. To provide information to stakeholders addressing these issues, the USGS Groundwater Resources Program made a detailed assessment of groundwater availability of the Central Valley aquifer system, that includes: (1) the present status of groundwater resources; (2) how these resources have changed over time; and (3) tools to assess system responses to stresses from future human uses and climate variability and change. This effort builds on previous investigations, such as the USGS Central Valley Regional Aquifer System and Analysis (CV-RASA) project and several other groundwater studies in the Valley completed by Federal, State and local agencies at differing scales. The

Complex Population Structure of Lyme Borreliosis Group Spirochete Borrelia garinii in Subarctic Eurasia

Science.gov (United States)

Comstedt, Pär; Asokliene, Loreta; Eliasson, Ingvar; Olsen, Björn; Wallensten, Anders; Bunikis, Jonas; Bergström, Sven

2009-01-01

Borrelia garinii, a causative agent of Lyme borreliosis in Europe and Asia, is naturally maintained in marine and terrestrial enzootic cycles, which primarily involve birds, including seabirds and migratory passerines. These bird groups associate with, correspondingly, Ixodes uriae and Ixodes ricinus ticks, of which the latter species may bite and transmit the infection to humans. Studies of the overlap between these two natural cycles of B. garinii have been limited, in part due to the absence of representative collections of this spirochete's samples, as well as of the lack of reliable measure of the genetic heterogeneity of its strains. As a prerequisite for understanding the epidemiological correlates of the complex maintenance of B. garinii, the present study sought to assess the diversity and phylogenetic relationships of this species' strains from its natural hosts and patients with Lyme borreliosis from subarctic Eurasia. We used sequence typing of the partial rrs-rrl intergenic spacer (IGS) of archived and prospective samples of B. garinii from I. uriae ticks collected predominantly on Commander Islands in North Pacific, as well as on the islands in northern Sweden and arctic Norway. We also typed B. garinii samples from patients with Lyme borreliosis and I. ricinus ticks infesting migratory birds in southern Sweden, or found questing in selected sites on the islands in the Baltic Sea and Lithuania. Fifty-two (68%) of 77 B. garinii samples representing wide geographical range and associated with I. ricinus and infection of humans contributed 12 (60%) of total 20 identified IGS variants. In contrast, the remaining 25 (32%) samples recovered from I. uriae ticks from a few islands accounted for as many as 10 (50%) IGS types, suggesting greater local diversity of B. garinii maintained by seabirds and their ticks. Two IGS variants of the spirochete in common for both tick species were found in I. ricinus larvae from migratory birds, an indication that B

An example of Alaknanda valley, Garhwal Himalaya, India

Indian Academy of Sciences (India)

2014) have been best explained by the geometry .... flows through narrow valley confined by the steep valley slopes. ... valley (figure 3b) which opens up around Srina- ... Method. 4.1 Drainage basin and stream network. Digital Elevation Model (DEM) helps in extracting ... was processed to fill the pits or sinks, and to obtain.

Geologic Map of the House Rock Valley Area, Coconino County, Northern Arizona

Science.gov (United States)

Billingsley, George H.; Priest, Susan S.

2010-01-01

. Other lands include about 13 sections of Arizona State land, about ? of a section of private land along House Rock Wash, and about 1? sections of private land at Cliff Dwellers Lodge, Vermilion Cliffs Lodge, and Marble Canyon, Arizona. Landmark features within the map area include the Vermilion Cliffs, Paria Plateau, Marble Canyon, and House Rock Valley. Surface drainage in House Rock Valley is to the east toward the Colorado River in Marble Canyon. Large tributaries of Marble Canyon from north to south include Badger Canyon, Soap Creek, Rider Canyon, North Canyon, Bedrock Canyon, and South Canyon. Elevations range from about 2,875 ft (876 m) at the Colorado River in the southeast corner of the map to approximately 7,355 ft (2,224 m) on the east rim of Paria Plateau along the north-central edge of the map area. Three small settlements are in the map area along U.S. Highway 89A, Cliff Dwellers Lodge, Vermilion Cliffs Lodge, and Marble Canyon, Arizona. The community of Jacob Lake is about 9 mi (14.5 km) west of House Rock Valley on the Kaibab Plateau. Lees Ferry is 5 mi (8 km) north of Marble Canyon and marks the confluence of the Paria and Colorado Rivers and the beginning of Marble Canyon. U.S. Highway 89A provides access to the northern part of the map area. Dirt roads lead south into House Rock Valley from U.S. Highway 89A and are collectively maintained by the Bureau of Land Management, the U.S. National Forest Service, and the Grand Canyon Trust. House Rock Valley is one of the few remaining areas where uniform geologic mapping is needed for connectivity to the regional Grand Canyon geologic framework. This information is useful to Federal and State resource managers who direct environmental and land management programs that encompass such issues as range management, biological studies, flood control, water, and mineral-resource investigations. The geologic information will support future and ongoing geologic investigations and scientific studies

Use of flow-normalization to evaluate nutrient concentration and flux changes in Lake Champlain tributaries, 1990-2009

Science.gov (United States)

Medalie, Laura; Hirsch, Robert M.; Archfield, Stacey A.

2012-01-01

The U.S. Geological Survey evaluated 20 years of total phosphorus (P) and total nitrogen (N) concentration data for 18 Lake Champlain tributaries using a new statistical method based on weighted regressions to estimate daily concentration and flux histories based on discharge, season, and trend as explanatory variables. The use of all the streamflow discharge values for a given date in the record, in a process called "flow-normalization," removed the year-to-year variation due to streamflow and generated a smooth time series from which trends were calculated. This approach to data analysis can be of great value to evaluations of the success of restoration efforts because it filters out the large random fluctuations in the flux that are due to the temporal variability in streamflow. Results for the full 20 years of record showed a mixture of upward and downward trends for concentrations and yields of P and N. When the record was broken into two 10-year periods, for many tributaries, the more recent period showed a reversal in N from upward to downward trends and a similar reversal or reduction in magnitude of upward trends for P. Some measures of P and N concentrations and yields appear to be related to intensity of agricultural activities, point-source loads of P, or population density. Total flow-normalized P flux aggregated from the monitored tributaries showed a decrease of 30 metric tons per year from 1991 to 2009, which is about 15% of the targeted reduction established by the operational management plan for the Lake Champlain Basin.

Chemical pollution in the Arctic and Sub-Arctic marine ecosystems: an overview of current knowledge

Energy Technology Data Exchange (ETDEWEB)

Savinova, T N; Gabrielsen, G W; Falk-Petersen, S

1995-02-01

This report is part of a research project in the framework of the Norwegian-Russian Environmental Cooperation, which was initiated in 1991 to elucidate the present status of environmental contaminants in the highly sensitive Arctic aquatic ecosystem, with special focus on sea birds. Although these ecosystems are the least polluted areas in the world, they are contaminated. The main pathways of contamination into Arctic and sub-Arctic marine ecosystems are atmospheric transport, ocean currents and rivers and in some areas, dumping and ship accidents. A literature survey reveals: (1) there is a lack of data from several trophic levels, (2) previous data are difficult to compare with recent data because of increased quality requirement, (3) not much has been done to investigate the effects of contaminants on the cellular level, at individual or population levels. 389 refs., 7 figs., 32 tabs.

Nutrient concentrations and loads and Escherichia coli densities in tributaries of the Niantic River estuary, southeastern Connecticut, 2005 and 2008–2011

Science.gov (United States)

Mullaney, John R.

2013-01-01

Nutrient concentrations and loads and Escherichia coli (E. coli) densities were studied in 2005 and from 2008 through 2011 in water-quality samples from tributaries of the Niantic River Estuary in southeastern Connecticut. Data from a water-quality survey of the base flow of subbasins in the watershed in June 2005 were used to determine the range of total nitrogen concentrations (0.09 to 2.4 milligrams per liter), instantaneous loads (less than 1 to 62 pounds per day) and the yields of total nitrogen ranging from 0.02 to 11.2 pounds per square mile per day (less than 1 to 7.2 kilograms per hectare per year) from basin segments. Nitrogen yields were positively correlated with the amount of developed land in each subbasin. Stable isotope measurements of nitrate (δ15N) and oxygen (δ18O) ranged from 3.9 to 9.4 per mil and 0.7 to 4.1 per mil, respectively, indicating that likely sources of nitrate in base flow are soil nitrate and ammonium fertilizers, sewage or animal waste, or a mixture of these sources. Continuous streamflow and monthly water-quality sampling, with additional storm event sampling, were conducted at the three major tributaries (Latimer Brook, Oil Mill Brook, and Stony Brook) of the Niantic River from October 2008 through September 2011. Samples were analyzed for nitrogen and phosphorus constituents and E. coli densities. Total freshwater discharge from these tributaries, which is reduced by upstream withdrawals, ranged from 25.9 to 37.8 million gallons per day. Total nitrogen and phosphorus concentrations generally were low, with the mean values below the U.S. Environmental Protection Agency recommended nutrient concentration values of 0.71 milligram per liter and 0.031 milligram per liter, respectively. Total nitrogen was predominantly in the form of total ammonia plus organic nitrogen at the Oil Mill Brook and Stony Brook sites and in the form of nitrate at Latimer Brook. Annual total nitrogen loads that flowed into the Niantic River estuary from

California's restless giant: the Long Valley Caldera

Science.gov (United States)

Hill, David P.; Bailey, Roy A.; Hendley, James W.; Stauffer, Peter H.; Marcaida, Mae

2014-01-01

Scientists have monitored geologic unrest in the Long Valley, California, area since 1980. In that year, following a swarm of strong earthquakes, they discovered that the central part of the Long Valley Caldera had begun actively rising. Unrest in the area persists today. The U.S. Geological Survey (USGS) continues to provide the public and civil authorities with current information on the volcanic hazard at Long Valley and is prepared to give timely warnings of any impending eruption.

Microbial control of soil organic matter mineralization responses to labile carbon in subarctic climate change treatments.

Science.gov (United States)

Rousk, Kathrin; Michelsen, Anders; Rousk, Johannes

2016-12-01

Half the global soil carbon (C) is held in high-latitude systems. Climate change will expose these to warming and a shift towards plant communities with more labile C input. Labile C can also increase the rate of loss of native soil organic matter (SOM); a phenomenon termed 'priming'. We investigated how warming (+1.1 °C over ambient using open top chambers) and litter addition (90 g m -2  yr -1 ) treatments in the subarctic influenced the susceptibility of SOM mineralization to priming, and its microbial underpinnings. Labile C appeared to inhibit the mineralization of C from SOM by up to 60% within hours. In contrast, the mineralization of N from SOM was stimulated by up to 300%. These responses occurred rapidly and were unrelated to microbial successional dynamics, suggesting catabolic responses. Considered separately, the labile C inhibited C mineralization is compatible with previously reported findings termed 'preferential substrate utilization' or 'negative apparent priming', while the stimulated N mineralization responses echo recent reports of 'real priming' of SOM mineralization. However, C and N mineralization responses derived from the same SOM source must be interpreted together: This suggested that the microbial SOM-use decreased in magnitude and shifted to components richer in N. This finding highlights that only considering SOM in terms of C may be simplistic, and will not capture all changes in SOM decomposition. The selective mining for N increased in climate change treatments with higher fungal dominance. In conclusion, labile C appeared to trigger catabolic responses of the resident microbial community that shifted the SOM mining to N-rich components; an effect that increased with higher fungal dominance. Extrapolating from these findings, the predicted shrub expansion in the subarctic could result in an altered microbial use of SOM, selectively mining it for N-rich components, and leading to a reduced total SOM-use. © 2016 John Wiley

Antibiotic contamination in a typical developing city in south China: occurrence and ecological risks in the Yongjiang River impacted by tributary discharge and anthropogenic activities.

Science.gov (United States)

Xue, Baoming; Zhang, Ruijie; Wang, Yinghui; Liu, Xiang; Li, Jun; Zhang, Gan

2013-06-01

The occurrence and distribution of ten selected antibiotics from three groups (sulfonamides, macrolides, and trimethoprim) were investigated in the Yongjiang River, which flows through Nanning City, a typical developing city in China. The study also assessed the ecological risks and the potential effects caused by discharge from tributaries and anthropogenic activities. Concentrations of most of the antibiotics were elevated along the section of the river in the urban area, highlighting the significant impact of high population density and human activities on the presence of antibiotics in the environment. The concentrations in the tributaries (ranged from not detected to 1336ngL(-1)) were generally higher than those in the main stream (ranged from not detected to 78.8ngL(-1)), but both areas contained the same predominant antibiotics, revealing the importance of tributary discharge as a source of antibiotic pollution. A risk assessment for the surface water contamination revealed that sulfamethoxazole and erythromycin posed high ecological risks to the most sensitive aquatic organisms (Synechococcus leopoliensis and Pseudokirchneriella subcapitata, respectively) in the midstream and some tributaries. Most of the selected antibiotics presented high ecological risks (risk quotients up to 95) in the sediments. Copyright © 2013 Elsevier Inc. All rights reserved.

Valley Fever

Science.gov (United States)

... valley fever. These fungi are commonly found in soil in specific regions. The fungi's spores can be stirred into the air by ... species have a complex life cycle. In the soil, they grow as a mold with long filaments that break off into airborne ...

Mass movements in the Rio Grande Valley (Quebrada de Humahuaca, Northwestern Argentina: a methodological approach to reduce the risk

Directory of Open Access Journals (Sweden)

G. Marcato

2009-10-01

Full Text Available Slope processes such as slides and debris flows, are among the main events that induce effects on the Rio Grande sediment transport capacity. The slides mainly affect the slope of the Rio Grande river basin while debris and mud flows phenomena take place in the tributary valleys. In the past decades several mass movements occurred causing victims and great damages to roads and villages and therefore hazard assessment and risk mitigation is of paramount importance for a correct development of the area. This is also an urgent need since the Quebrada de Humahuaca was recently included in the UNESCO World Cultural Heritage. The growing tourism business may lead to an uncontrolled urbanization of the valley with the consequent enlargement of threatened areas.

In this framework mitigation measures have to take into account not only technical aspects related to the physical behaviour of the moving masses but also environmental and sociological factors that could influence the effectiveness of the countermeasures.

Mitigation of landslide effects is indeed rather complex because of the large extension of the territory and the particular geological and geomorphological setting. Moreover the necessity to maintain the natural condition of the area as prescribed by UNESCO, make this task even more difficult.

Nowadays no in-depth study of the entire area exists, therefore an integrated and multidisciplinary investigation plan is going to be set up including geological and geomorphological investigations as well as archaeological and historical surveys. The better understanding of geomorphological evolution processes of the Quebrada de Humahuaca will bridge the gap between the necessity of preservation and the request of safety keeping of the recommendation by UNESCO.

Mass movements in the Rio Grande Valley (Quebrada de Humahuaca, Northwestern Argentina): a methodological approach to reduce the risk

Science.gov (United States)

Marcato, G.; Pasuto, A.; Rivelli, F. R.

2009-10-01

Slope processes such as slides and debris flows, are among the main events that induce effects on the Rio Grande sediment transport capacity. The slides mainly affect the slope of the Rio Grande river basin while debris and mud flows phenomena take place in the tributary valleys. In the past decades several mass movements occurred causing victims and great damages to roads and villages and therefore hazard assessment and risk mitigation is of paramount importance for a correct development of the area. This is also an urgent need since the Quebrada de Humahuaca was recently included in the UNESCO World Cultural Heritage. The growing tourism business may lead to an uncontrolled urbanization of the valley with the consequent enlargement of threatened areas. In this framework mitigation measures have to take into account not only technical aspects related to the physical behaviour of the moving masses but also environmental and sociological factors that could influence the effectiveness of the countermeasures. Mitigation of landslide effects is indeed rather complex because of the large extension of the territory and the particular geological and geomorphological setting. Moreover the necessity to maintain the natural condition of the area as prescribed by UNESCO, make this task even more difficult. Nowadays no in-depth study of the entire area exists, therefore an integrated and multidisciplinary investigation plan is going to be set up including geological and geomorphological investigations as well as archaeological and historical surveys. The better understanding of geomorphological evolution processes of the Quebrada de Humahuaca will bridge the gap between the necessity of preservation and the request of safety keeping of the recommendation by UNESCO.

Plastic debris in 29 Great Lakes tributaries: Relations to watershed attributes and hydrology

Science.gov (United States)

Baldwin, Austin K.; Corsi, Steven; Mason, Sherri A.

2016-01-01

Plastic debris is a growing contaminant of concern in freshwater environments, yet sources, transport, and fate remain unclear. This study characterized the quantity and morphology of floating micro- and macroplastics in 29 Great Lakes tributaries in six states under different land covers, wastewater effluent contributions, population densities, and hydrologic conditions. Tributaries were sampled three or four times each using a 333 μm mesh neuston net. Plastic particles were sorted by size, counted, and categorized as fibers/lines, pellets/beads, foams, films, and fragments. Plastics were found in all 107 samples, with a maximum concentration of 32 particles/m3 and a median of 1.9 particles/m3. Ninety-eight percent of sampled plastic particles were less than 4.75 mm in diameter and therefore considered microplastics. Fragments, films, foams, and pellets/beads were positively correlated with urban-related watershed attributes and were found at greater concentrations during runoff-event conditions. Fibers, the most frequently detected particle type, were not associated with urban-related watershed attributes, wastewater effluent contribution, or hydrologic condition. Results from this study add to the body of information currently available on microplastics in different environmental compartments, including unique contributions to quantify their occurrence and variability in rivers with a wide variety of different land-use characteristics while highlighting differences between surface samples from rivers compared with lakes.

Plastic Debris in 29 Great Lakes Tributaries: Relations to Watershed Attributes and Hydrology.

Science.gov (United States)

Baldwin, Austin K; Corsi, Steven R; Mason, Sherri A

2016-10-04

Plastic debris is a growing contaminant of concern in freshwater environments, yet sources, transport, and fate remain unclear. This study characterized the quantity and morphology of floating micro- and macroplastics in 29 Great Lakes tributaries in six states under different land covers, wastewater effluent contributions, population densities, and hydrologic conditions. Tributaries were sampled three or four times each using a 333 μm mesh neuston net. Plastic particles were sorted by size, counted, and categorized as fibers/lines, pellets/beads, foams, films, and fragments. Plastics were found in all 107 samples, with a maximum concentration of 32 particles/m 3 and a median of 1.9 particles/m 3 . Ninety-eight percent of sampled plastic particles were less than 4.75 mm in diameter and therefore considered microplastics. Fragments, films, foams, and pellets/beads were positively correlated with urban-related watershed attributes and were found at greater concentrations during runoff-event conditions. Fibers, the most frequently detected particle type, were not associated with urban-related watershed attributes, wastewater effluent contribution, or hydrologic condition. Results from this study add to the body of information currently available on microplastics in different environmental compartments, including unique contributions to quantify their occurrence and variability in rivers with a wide variety of different land-use characteristics while highlighting differences between surface samples from rivers compared with lakes.

Nematic and Valley Ordering in Anisotropic Quantum Hall Systems

Science.gov (United States)

Parameswaran, S. A.; Abanin, D. A.; Kivelson, S. A.; Sondhi, S. L.

2010-03-01

We consider a multi-valley two dimensional electron system in the quantum Hall effect (QHE) regime. We focus on QHE states that arise due to spontaneous breaking of the valley symmetry by the Coulomb interactions. We show that the anisotropy of the Fermi surface in each valley, which is generally present in such systems, favors states where all the electrons reside in one of the valleys. In a clean system, the valley ordering occurs via a finite temperature Ising-like phase transition, which, owing to the Fermi surface anisotropy, is accompanied by the onset of nematic order. In a disordered system, domains of opposite polarization are formed, and therefore long-range valley order is destroyed, however, the resulting state is still compressible. We discuss the transport properties in ordered and disordered regimes, and point out the possible relation of our results to recent experiments in AlAs [1]. [1] Y. P. Shkolnikov, S. Misra, N. C. Bishop, E. P. De Poortere, and M. Shayegan, Observation of Quantum Hall ``Valley Skyrmions", Phys. Rev. Lett. 95, 068809 (2005)[2] D.A. Abanin, S.A. Parameswaran, S.A. Kivelson and S.L. Sondhi, Nematic and Valley Ordering in Anisotropic Quantum Hall Systems, to be published.

Petroleum hydrocarbon biodegradation under seasonal freeze-thaw soil temperature regimes in contaminated soils from a sub-Arctic site.

Science.gov (United States)

Chang, Wonjae; Klemm, Sara; Beaulieu, Chantale; Hawari, Jalal; Whyte, Lyle; Ghoshal, Subhasis

2011-02-01

Several studies have shown that biostimulation in ex situ systems such as landfarms and biopiles can facilitate remediation of petroleum hydrocarbon contaminated soils at sub-Arctic sites during summers when temperatures are above freezing. In this study, we examine the biodegradation of semivolatile (F2: C10-C16) and nonvolatile (F3: C16-C34) petroleum hydrocarbons and microbial respiration and population dynamics at post- and presummer temperatures ranging from -5 to 14 °C. The studies were conducted in pilot-scale tanks with soils obtained from a historically contaminated sub-Arctic site in Resolution Island (RI), Canada. In aerobic, nutrient-amended, unsaturated soils, the F2 hydrocarbons decreased by 32% during the seasonal freeze-thaw phase where soils were cooled from 2 to -5 °C at a freezing rate of -0.12 °C d(-1) and then thawed from -5 to 4 °C at a thawing rate of +0.16 °C d(-1). In the unamended (control) tank, the F2 fraction only decreased by 14% during the same period. Biodegradation of individual hydrocarbon compounds in the nutrient-amended soils was also confirmed by comparing their abundance over time to that of the conserved diesel biomarker, bicyclic sesquiterpanes (BS). During this period, microbial respiration was observed, even at subzero temperatures when unfrozen liquid water was detected during the freeze-thaw period. An increase in culturable heterotrophs and 16S rDNA copy numbers was noted during the freezing phase, and the (14)C-hexadecane mineralization in soil samples obtained from the nutrient-amended tank steadily increased. Hydrocarbon degrading bacterial populations identified as Corynebacterineae- and Alkanindiges-related strains emerged during the freezing and thawing phases, respectively, indicating there were temperature-based microbial community shifts.

Temperature and substrate controls on intra-annual variation in ecosystem respiration in two subarctic vegetation types

DEFF Research Database (Denmark)

Grogan, Paul; Jonasson, Sven Evert

2005-01-01

significantly to ecosystem respiration during most phases of winter and summer in the two vegetation types. Ecosystem respiration rates through the year did not differ significantly between vegetation types despite substantial differences in biomass pools, soil depth and temperature regime. Most (76...... contributions of bulk soil organic matter and plant-associated carbon pools to ecosystem respiration is critical to predicting the response of arctic ecosystem net carbon balance to climate change. In this study, we determined the variation in ecosystem respiration rates from birch forest understory and heath......-92%) of the intra-annual variation in ecosystem respiration rates from these two common mesic subarctic ecosystems was explained using a first-order exponential equation relating respiration to substrate chemical quality and soil temperature. Removal of plants and their current year's litter significantly reduced...

Parasite infracommunities of Leporinus friderici: A comparison of three tributaries of the Jurumirim Reservoir in southeastern Brazil

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FÁBIO H. YAMADA

Full Text Available ABSTRACT The degradation and homogenization of natural habitats is considered a major cause of biotic homogenization. Many studies have been undertaken on the effects of dams on aquatic wildlife, in particular fish assemblages. But how do dams affect the parasitic fauna of such fish? The aim of the present study was to examine parasitic similarity, comparing the diversity and structure of parasite communities of Leporinus friderici (Characiformes, Anostomidae in three upstream tributaries under the influence of the Jurumirim Dam on the Upper Paranapanema River in southeastern Brazil. The present study did not find any significant differences in parasite communities among populations of L. friderici in the three upstream tributaries. This result highlights that dams promote and facilitate the dispersal of organisms between localities, and therefore the spatial homogenization of parasite communities. Overall, the results suggest that fish parasite assemblages can provide suitable data for evaluating biotic homogenization caused by dams.

Valley photonic crystals for control of spin and topology.

Science.gov (United States)

Dong, Jian-Wen; Chen, Xiao-Dong; Zhu, Hanyu; Wang, Yuan; Zhang, Xiang

2017-03-01

Photonic crystals offer unprecedented opportunity for light manipulation and applications in optical communication and sensing. Exploration of topology in photonic crystals and metamaterials with non-zero gauge field has inspired a number of intriguing optical phenomena such as one-way transport and Weyl points. Recently, a new degree of freedom, valley, has been demonstrated in two-dimensional materials. Here, we propose a concept of valley photonic crystals with electromagnetic duality symmetry but broken inversion symmetry. We observe photonic valley Hall effect originating from valley-dependent spin-split bulk bands, even in topologically trivial photonic crystals. Valley-spin locking behaviour results in selective net spin flow inside bulk valley photonic crystals. We also show the independent control of valley and topology in a single system that has been long pursued in electronic systems, resulting in topologically-protected flat edge states. Valley photonic crystals not only offer a route towards the observation of non-trivial states, but also open the way for device applications in integrated photonics and information processing using spin-dependent transportation.

Valley Hall effect and Nernst effect in strain engineered graphene

Science.gov (United States)

Niu, Zhi Ping; Yao, Jian-ming

2018-04-01

We theoretically predict the existence of tunneling valley Hall effect and Nernst effect in the normal/strain/normal graphene junctions, where a strained graphene is sandwiched by two normal graphene electrodes. By applying an electric bias a pure transverse valley Hall current with longitudinal charge current is generated. If the system is driven by a temperature bias, a valley Nernst effect is observed, where a pure transverse valley current without charge current propagates. Furthermore, the transverse valley current can be modulated by the Fermi energy and crystallographic orientation. When the magnetic field is further considered, we obtain a fully valley-polarized current. It is expected these features may be helpful in the design of the controllable valleytronic devices.

Disorder-dependent valley properties in monolayer WSe2

KAUST Repository

Tran, Kha

2017-07-19

We investigate the effect of disorder on exciton valley polarization and valley coherence in monolayer WSe2. By analyzing the polarization properties of photoluminescence, the valley coherence (VC) and valley polarization (VP) are quantified across the inhomogeneously broadened exciton resonance. We find that disorder plays a critical role in the exciton VC, while affecting VP less. For different monolayer samples with disorder characterized by their Stokes shift (SS), VC decreases in samples with higher SS while VP does not follow a simple trend. These two methods consistently demonstrate that VC as defined by the degree of linearly polarized photoluminescence is more sensitive to disorder, motivating further theoretical studies.

The Role of Source Material in Basin Sedimentation, as Illustrated within Eureka Valley, Death Valley National Park, CA.

Science.gov (United States)

Lawson, M. J.; Yin, A.; Rhodes, E. J.

2015-12-01

Steep landscapes are known to provide sediment to sink regions, but often petrological factors can dominate basin sedimentation. Within Eureka Valley, in northwestern Death Valley National Park, normal faulting has exposed a steep cliff face on the western margin of the Last Chance range with four kilometers of vertical relief from the valley floor and an angle of repose of nearly 38 degrees. The cliff face is composed of Cambrian limestone and dolomite, including the Bonanza King, Carrara and Wood Canyon formations. Interacting with local normal faulting, these units preferentially break off the cliff face in coherent blocks, which result in landslide deposits rather than as finer grained material found within the basin. The valley is well known for a large sand dune, which derives its sediment from distal sources to the north, instead of from the adjacent Last Chance Range cliff face. During the Holocene, sediment is sourced primary from the northerly Willow Wash and Cucomungo canyon, a relatively small drainage (less than 80 km2) within the Sylvan Mountains. Within this drainage, the Jurassic quartz monzonite of Beer Creek is heavily fractured due to motion of the Fish Valley Lake - Death Valley fault zone. Thus, the quartz monzonite is more easily eroded than the well-consolidated limestone and dolomite that forms the Last Change Range cliff face. As well, the resultant eroded material is smaller grained, and thus more easily transported than the limestone. Consequently, this work highlights an excellent example of the strong influence that source material can have on basin sedimentation.

Increasing frequency of plastic particles ingested by seabirds in the subarctic North Pacific

Science.gov (United States)

Robards, Martin D.; Piatt, John F.; Wohl, Kenton D.

1995-01-01

We examined gut contents of 1799 seabirds comprising 24 species collected in 1988-1990 to assess the types and quantities of plastic particles ingested by seabirds in the subarctic waters of Alaska. Of the 15 species found to ingest plastic, most were surface-feeders (shearwaters, petrels, gulls) or plankton-feeding divers (auklets, puffins). Of 4417 plastic particles examined, 76% were industrial pellets and 21% were fragments of ‘user’ plastic. Ingestion rates varied geographically, but no trends were evident and rates of plastic ingestion varied far more among species within areas than within species among areas. Comparison with similar data from 1968 seabirds comprising 37 species collected in 1969-1977 revealed that plastic ingestion by seabirds has increased significantly during the 10–15-year interval between studies. This was demonstrated by: (i) an increase in the total number of species ingesting plastic; (ii) an increase in the frequency of occurrence of plastic particles within species that ingested plastic; and, (iii) an increase in the mean number of plastic particles ingested by individuals of those species.

UAV Remote Sensing Surveillance of a Mine Tailings Impoundment in Sub-Arctic Conditions

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Anssi Rauhala

2017-12-01

Full Text Available Mining typically involves extensive areas where environmental monitoring is spatially sporadic. New remote sensing techniques and platforms such as Structure from Motion (SfM and unmanned aerial vehicles (UAVs may offer one solution for more comprehensive and spatially continuous measurements. We conducted UAV campaigns in three consecutive summers (2015–2017 at a sub-Arctic mining site where production was temporarily suspended. The aim was to monitor a 0.5 km2 tailings impoundment and measure potential subsidence of tailings. SfM photogrammetry was used to produce yearly topographical models of the tailings surface, which allowed the amount of surface displacement between years to be tracked. Ground checkpoints surveyed in stable areas of the impoundment were utilized in assessing the vertical accuracy of the models. Observed surface displacements were linked to a combination of erosion, tailings settlement, and possible compaction of the peat layer underlying the tailings. The accuracy obtained indicated that UAV-assisted monitoring of tailings impoundments is sufficiently accurate for supporting impoundment management operations and for tracking surface displacements in the decimeter range.

Antifan activism as a response to MTV's The Valleys

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Bethan Jones

2015-06-01

Full Text Available MTV has launched several reality TV shows in the United Kingdom, but one, The Valleys (2012–14, about youth moving from the South Wales Valleys to Cardiff, has received much criticism. Grassroots criticism of the show arose, and a Valleys-centric campaign, The Valleys Are Here, took direct action. I adopt Jonathan Gray's definition of antifans to complicate ideas of fan activism. I utilize comments and posts made on the Valleys Are Here Twitter feed and Facebook account, as well as the organization's Web site, to examine the ways in which they encourage activism among antifans of the series. I pay particular attention to activist calls for MTV to be held accountable for its positioning of Wales and the Valleys, and to how it encourages participation among varied groups of people whose common denominator is their dislike of the series. Fan activism is not exclusive to people who consider themselves fans, and notions of fan activism can be complicated by drawing in antifans.

Concentration, flux, and the analysis of trends of total and dissolved phosphorus, total nitrogen, and chloride in 18 tributaries to Lake Champlain, Vermont and New York, 1990–2011

Science.gov (United States)

Medalie, Laura

2013-01-01

Annual concentration, flux, and yield for total phosphorus, dissolved phosphorus, total nitrogen, and chloride for 18 tributaries to Lake Champlain were estimated for 1990 through 2011 using a weighted regression method based on time, tributary streamflows (discharges), and seasonal factors. The weighted regression method generated two series of daily estimates of flux and concentration during the period of record: one based on observed discharges and a second based on a flow-normalization procedure that removes random variation due to year-to-year climate-driven effects. The flownormalized estimate for a given date is similar to an average estimate of concentration or flux that would be made if all of the observed discharges for that date were equally likely to have occurred. The flux bias statistic showed that 68 of the 72 flux regression models were minimally biased. Temporal trends in the concentrations and fluxes were determined by calculating percent changes in flow-normalized annual fluxes for the full period of analysis (1990 through 2010) and for the decades 1990–2000 and 2000–2010. Basinwide, flow-normalized total phosphorus flux decreased by 42 metric tons per year (t/yr) between 1990 and 2010. This net result reflects a basinwide decrease in flux of 21 metric tons (t) between 1990 and 2000, followed by a decrease of 20 t between 2000 and 2010; both results were largely influenced by flux patterns in the large tributaries on the eastern side of the basin. A comparison of results for total phosphorus for the two separate decades of analysis found that more tributaries had decreasing concentrations and flux rates in the second decade than the first. An overall reduction in dissolved phosphorus flux of 0.7 t/yr was seen in the Lake Champlain Basin during the full period of analysis. That very small net change in flux reflects substantial reductions between 1990 and 2000 from eastern tributaries, especially in Otter Creek and the LaPlatte and Winooski

Nitrogen fixation, denitrification, and ecosystem nitrogen pools in relation to vegetation development in the Subarctic

DEFF Research Database (Denmark)

Sørensen, Pernille Lærkedal; Jonasson, Sven Evert; Michelsen, Anders

2006-01-01

Nitrogen (N) fixation, denitrification, and ecosystem pools of nitrogen were measured in three subarctic ecosystem types differing in soil frost-heaving activity and vegetation cover. N2-fixation was measured by the acetylene reduction assay and converted to absolute N ecosystem input by estimates...... of conversion factors between acetylene reduction and 15N incorporation. One aim was to relate nitrogen fluxes and nitrogen pools to the mosaic of ecosystem types of different stability common in areas of soil frost movements. A second aim was to identify abiotic controls on N2-fixation by simultaneous...... measurements of temperature, light, and soil moisture. Nitrogen fixation rate was high with seasonal input estimated at 1.1 g N m2 on frostheaved sorted circles, which was higher than the total plant N content and exceeded estimated annual plant N uptake several-fold but was lower than the microbial N content...

The quasi-steady state of the valley wind system

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Juerg eSchmidli

2015-12-01

Full Text Available The quasi-steady-state limit of the diurnal valley wind system is investigated overidealized three-dimensional topography. Although this limit is rarely attained inreality due to ever-changing forcings, the investigation of this limit canprovide valuable insight, in particular on the mass and heat fluxes associatedwith the along-valley wind. We derive a scaling relation for the quasi-steady-state along-valleymass flux as a function of valley geometry, valley size, atmospheric stratification,and surface sensible heat flux forcing. The scaling relation is tested by comparisonwith the mass flux diagnosed from numerical simulations of the valleywind system. Good agreement is found. The results also provide insight into the relationbetween surface friction and the strength of the along-valley pressure gradient.

Direct measurement of exciton valley coherence in monolayer WSe2

KAUST Repository

Hao, Kai

2016-02-29

In crystals, energy band extrema in momentum space can be identified by a valley index. The internal quantum degree of freedom associated with valley pseudospin indices can act as a useful information carrier, analogous to electronic charge or spin. Interest in valleytronics has been revived in recent years following the discovery of atomically thin materials such as graphene and transition metal dichalcogenides. However, the valley coherence time—a crucial quantity for valley pseudospin manipulation—is difficult to directly probe. In this work, we use two-dimensional coherent spectroscopy to resonantly generate and detect valley coherence of excitons (Coulomb-bound electron–hole pairs) in monolayer WSe₂ (refs ,). The imposed valley coherence persists for approximately one hundred femtoseconds. We propose that the electron–hole exchange interaction provides an important decoherence mechanism in addition to exciton population recombination. This work provides critical insight into the requirements and strategies for optical manipulation of the valley pseudospin for future valleytronics applications.

Uncertainty assessment of a polygon database of soil organic carbon for greenhouse gas reporting in Canada’s Arctic and sub-arctic

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M.F. Hossain

2014-08-01

Full Text Available Canada’s Arctic and sub-arctic consist 46% of Canada’s landmass and contain 45% of the total soil organic carbon (SOC. Pronounced climate warming and increasing human disturbances could induce the release of this SOC to the atmosphere as greenhouse gases. Canada is committed to estimating and reporting the greenhouse gases emissions and removals induced by land use change in the Arctic and sub-arctic. To assess the uncertainty of the estimate, we compiled a site-measured SOC database for Canada’s north, and used it to compare with a polygon database, that will be used for estimating SOC for the UNFCCC reporting. In 10 polygons where 3 or more measured sites were well located in each polygon, the site-averaged SOC content agreed with the polygon data within ±33% for the top 30 cm and within ±50% for the top 1 m soil. If we directly compared the SOC of the 382 measured sites with the polygon mean SOC, there was poor agreement: The relative error was less than 50% at 40% of the sites, and less than 100% at 68% of the sites. The relative errors were more than 400% at 10% of the sites. These comparisons indicate that the polygon database is too coarse to represent the SOC conditions for individual sites. The difference is close to the uncertainty range for reporting. The spatial database could be improved by relating site and polygon SOC data with more easily observable surface features that can be identified and derived from remote sensing imagery.

Heavy metals in tributaries of Pampulha Reservoir, Minas Gerais

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A. C. RIETZLER

Full Text Available A great amount of heavy metals enter Pampulha Reservoir via it's main tributaries (Sarandi and Ressaca. Although no water quality classification has been carried out for these tributaries, the reservoir is expected to be in class 2 of the CONAMA-86 system. As part of a monitoring scheme of the Pampulha Watershed, heavy metals (Zn, Pb, Cd, Ni, Cu, Cr, Mn and Fe were investigated in the water at a control site (considered free from direct human influence and at potential sites of toxicity and contamination during August (dry season and November (wet season of 1998. The results for the first sampling period showed relatively high concentrations of zinc (0.22 mg.L-1 in the upper portion of the reservoir. The highest values of nickel and chromium (0.19 and 0.89 mg.L-1, respectively were found in the initial portion of the Sarandi Stream, while the highest concentrations of lead (0.05 mg.L-1, cadmium (0.014 mg.L-1, manganese (0.43 mg.L-1 and iron (15.25 mg.L-1 were detected in the Ressaca Stream by the landfill dump of Belo Horizonte. A relatively high concentration of cadmium was also detected at the confluence of the two streams. During the second sampling period, there was an increase in the concentrations of zinc at all sampling sites except the control, with values varying from 0.71 mg.L-1 (the Sarandi Stream to 2.50 mg.L-1 (the Ressaca Stream. Lead, cadmium, nickel and chromium concentrations were also higher in the Ressaca Stream, but not detected at the other sampling sites. Copper values were higher than in the first period: 0.10 mg.L-1 at the control up to 0.38 mg.L-1 at the confluence of the streams. Similar results were found for manganese and iron, with values reaching up to 19.30 and 125 mg.L-1, respectively. Moreover, all values recorded in the second sampling period were much higher than recommended for class 2 waters. These results emphasize the need for such monitoring in relation to better water quality management of this reservoir.

Heavy metals in tributaries of Pampulha Reservoir, Minas Gerais

Directory of Open Access Journals (Sweden)

RIETZLER A. C.

2001-01-01

Full Text Available A great amount of heavy metals enter Pampulha Reservoir via it's main tributaries (Sarandi and Ressaca. Although no water quality classification has been carried out for these tributaries, the reservoir is expected to be in class 2 of the CONAMA-86 system. As part of a monitoring scheme of the Pampulha Watershed, heavy metals (Zn, Pb, Cd, Ni, Cu, Cr, Mn and Fe were investigated in the water at a control site (considered free from direct human influence and at potential sites of toxicity and contamination during August (dry season and November (wet season of 1998. The results for the first sampling period showed relatively high concentrations of zinc (0.22 mg.L-1 in the upper portion of the reservoir. The highest values of nickel and chromium (0.19 and 0.89 mg.L-1, respectively were found in the initial portion of the Sarandi Stream, while the highest concentrations of lead (0.05 mg.L-1, cadmium (0.014 mg.L-1, manganese (0.43 mg.L-1 and iron (15.25 mg.L-1 were detected in the Ressaca Stream by the landfill dump of Belo Horizonte. A relatively high concentration of cadmium was also detected at the confluence of the two streams. During the second sampling period, there was an increase in the concentrations of zinc at all sampling sites except the control, with values varying from 0.71 mg.L-1 (the Sarandi Stream to 2.50 mg.L-1 (the Ressaca Stream. Lead, cadmium, nickel and chromium concentrations were also higher in the Ressaca Stream, but not detected at the other sampling sites. Copper values were higher than in the first period: 0.10 mg.L-1 at the control up to 0.38 mg.L-1 at the confluence of the streams. Similar results were found for manganese and iron, with values reaching up to 19.30 and 125 mg.L-1, respectively. Moreover, all values recorded in the second sampling period were much higher than recommended for class 2 waters. These results emphasize the need for such monitoring in relation to better water quality management of this reservoir.

Photon wavelength dependent valley photocurrent in multilayer MoS2

Science.gov (United States)

Guan, Hongming; Tang, Ning; Xu, Xiaolong; Shang, LiangLiang; Huang, Wei; Fu, Lei; Fang, Xianfa; Yu, Jiachen; Zhang, Caifeng; Zhang, Xiaoyue; Dai, Lun; Chen, Yonghai; Ge, Weikun; Shen, Bo

2017-12-01

The degree of freedom (DOF) of the K (K') valley in transition-metal dichalcogenides, especially molybdenum disulfide (MoS2), offers an opportunity for next-generation valleytronics devices. In this work, the K (K') valley DOF of multilayer MoS2 is studied by means of the photon wavelength dependent circular photogalvanic effect (CPGE) at room temperature upon a strong external out-of-plane electric field induced by an ionic liquid (IL) gate, which breaks the spatial-inversion symmetry. It is demonstrated that only on resonant excitations in the K (K') valley can the valley-related CPGE signals in multilayer MoS2 with an IL gate be detected, indicating that the valley contrast is indeed regenerated between the K and K' valleys when the electric field is applied. As expected, it can also be seen that the K (K') valley DOF in multilayer MoS2 can be modulated by the external electric field. The observation of photon wavelength dependent valley photocurrent in multilayer MoS2, with the help of better Ohmic contacts, may pave a way for optoelectronic applications of valleytronics in the future.

Spin-valley splitting of electron beam in graphene

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Yu Song

2016-11-01

Full Text Available We study spatial separation of the four degenerate spin-valley components of an electron beam in a EuO-induced and top-gated ferromagnetic/pristine/strained graphene structure. We show that, in a full resonant tunneling regime for all beam components, the formation of standing waves can lead sudden phase jumps ∼−π and giant lateral Goos-Hänchen shifts as large as the transverse beam width, while the interplay of the spin and valley imaginary wave vectors in the modulated regions can lead differences of resonant angles for the four spin-valley flavors, manifesting a spin-valley beam splitting effect. The splitting effect is found to be controllable by the gating and strain.

The carbon stable isotope biogeochemistry of streams, Taylor Valley, Antarctica

International Nuclear Information System (INIS)

Lyons, W.B.; Leslie, D.L.; Harmon, R.S.; Neumann, K.; Welch, K.A.; Bisson, K.M.; McKnight, D.M.

2013-01-01

Highlights: ► δ 13 C-DIC reported from McMurdo Dry Valleys, Antarctica, streams. ► Stream water δ 13 C PDB values range −9.4‰ to +5.1‰, largely inorganic in character. ► Atmospheric exchange is the dominant control on δ 13 C-DIC. - Abstract: The McMurdo Dry Valleys region of Antarctica is the largest ice-free region on the continent. This study reports the first C stable isotope measurements for dissolved inorganic C present in ephemeral streams in four dry valleys that flow for four to twelve weeks during the austral summer. One of these valleys, Taylor Valley, has been the focus of the McMurdo Dry Valleys Long-Term Ecological Research (MCM-LTER) program since 1993. Within Taylor Valley, numerous ephemeral streams deliver water to three perennially ice-covered, closed-basin lakes: Lake Fryxell, Lake Hoare, and Lake Bonney. The Onyx River in the Wright Valley, the longest river in Antarctica, flows for 40 km from the Wright Lower Glacier and Lake Brownworth at the foot of the glacier to Lake Vanda. Streamflow in the McMurdo Dry Valley streams is produced primarily from glacial melt, as there is no overland flow. However, hyporheic zone exchange can be a major hydrogeochemical process in these streams. Depending on landscape position, these streams vary in gradient, channel substrate, biomass abundance, and hyporheic zone extent. This study sampled streams from Taylor, Wright, Garwood, and Miers Valleys and conducted diurnal sampling of two streams of different character in Taylor Valley. In addition, transect sampling was undertaken of the Onyx River in Wright Valley. The δ 13 C PDB values from these streams span a range of greater than 14‰, from −9.4‰ to +5.1‰, with the majority of samples falling between −3‰ and +2‰, suggesting that the C stable isotope composition of dissolved C in McMurdo Dry Valley streams is largely inorganic in character. Because there are no vascular plants on this landscape and no groundwater input to these

Approaches to restoration of oak forests on farmed lowlands of the Mississippi river and its tributaries (Avances en la restauración de bosques de roble en tierras bajas agrícolas del Río Mississippi y sus tributaries)

Science.gov (United States)

E.S. Gardiner; D.C. Dey; John Stanturf; B.R. Lockhart

2010-01-01

The lowlands associated with the Mississippi River and its tributaries historically supported extensive broadleaf forests that were particularly rich in oak (Quercus spp.) species. Beginning in the 1700s, deforestation for agriculture substantially reduced the extent of the original forest, and fragmented the remainder into small parcels. More recently, declines in...

Valley-polarized quantum transport generated by gauge fields in graphene

DEFF Research Database (Denmark)

Settnes, Mikkel; Garcia, Jose H; Roche, Stephan

2017-01-01

We report on the possibility to simultaneously generate in graphene a bulk valley-polarized dissipative transport and a quantum valley Hall effect by combining strain-induced gauge fields and real magnetic fields. Such unique phenomenon results from a ‘resonance/anti-resonance’ effect driven by t...... Kubo transport methods combined with a valley projection scheme to access valley-dependent conductivities and show that the results are robust against disorder....

Electrical control of the anomalous valley Hall effect in antiferrovalley bilayers

Science.gov (United States)

Tong, Wen-Yi; Duan, Chun-Gang

2017-08-01

In analogy to all-electric spintronics, all-electric valleytronics, i.e., valley manipulation via electric means, becomes an exciting new frontier as it may bring revolutions in the field of data storage with ultra-high speed and ultra-low power consumption. The existence of the anomalous valley Hall effect in ferrovalley materials demonstrates the possibility of electrical detection for valley polarization. However, in previously proposed valley-polarized monolayers, the anomalous valley Hall effect is controlled by external magnetic fields. Here, through elaborate structural design, we propose the antiferrovally bilayer as an ideal candidate for realizing all-electric valleytronic devices. Using the minimal k.p model, we show that the energy degeneracy between valley indexes in such system can be lifted by electric approaches. Subsequently, the anomalous valley Hall effect strongly depends on the electric field as well. Taking the bilayer VSe2 as an example, all-electric tuning and detecting of anomalous valley Hall effect is confirmed by density-functional theory calculations, indicating that the valley information in such antiferrovalley bilayer can be reversed by an electric field perpendicular to the plane of the system and easily probed through the sign of the Hall voltage.

Water-quality and biological conditions in selected tributaries of the Lower Boise River, southwestern Idaho, water years 2009-12

Science.gov (United States)

Etheridge, Alexandra B.; MacCoy, Dorene E.; Weakland, Rhonda J.

2014-01-01

Water-quality conditions were studied in selected tributaries of the lower Boise River during water years 2009–12, including Fivemile and Tenmile Creeks in 2009, Indian Creek in 2010, and Mason Creek in 2011 and 2012. Biological samples, including periphyton biomass and chlorophyll-a, benthic macroinvertebrates, and fish were collected in Mason Creek in October 2011. Synoptic water-quality sampling events were timed to coincide with the beginning and middle of the irrigation season as well as the non-irrigation season, and showed that land uses and irrigation practices affect water quality in the selected tributaries. Large increases in nutrient and sediment concentrations and loads occurred over relatively short stream reaches and affected nutrient and sediment concentrations downstream of those reaches. Escherichia coli (E. coli) values increased in study reaches adjacent to pastured lands or wastewater treatment plants, but increased E. coli values at upstream locations did not necessarily affect E. coli values at downstream locations. A spatial loading analysis identified source areas for nutrients, sediment, and E. coli, and might be useful in selecting locations for water-quality improvement projects. Effluent from wastewater treatment plants increased nutrient loads in specific reaches in Fivemile and Indian Creeks. Increased suspended-sediment loads were associated with increased discharge from irrigation returns in each of the studied tributaries. Samples collected during or shortly after storms showed that surface runoff, particularly during the winter, may be an important source of nutrients in tributary watersheds with substantial agricultural land use. Concentrations of total phosphorus, suspended sediment, and E. coli exceeded regulatory water-quality targets or trigger levels at one or more monitoring sites in each tributary studied, and exceedences occurred during irrigation season more often than during non-irrigation season. As with water

Anatomical structure overrides temperature controls on magnesium uptake – calcification in the Arctic/subarctic coralline algae Leptophytum laeve and Kvaleya epilaeve (Rhodophyta; Corallinales

Directory of Open Access Journals (Sweden)

M. C. Nash

2018-02-01

Full Text Available Calcified coralline red algae are ecologically key organisms in photic benthic environments. In recent decades they have become important climate proxies, especially in the Arctic and subarctic. It has been widely accepted that magnesium content in coralline tissues is directly a function of ambient temperature, and this is a primary basis for their value as a climate archive. In this paper we show for two genera of Arctic/subarctic corallines, Leptophytum laeve and Kvaleya epilaeve, that previously unrecognised complex tissue and cell wall anatomy bears a variety of basal signatures for Mg content, with the accepted temperature relationship being secondary. The interfilament carbonate has lower Mg than adjacent cell walls and the hypothallial cell walls have the highest Mg content. The internal structure of the hypothallial cell walls can differ substantially from the perithallial radial cell wall structure. Using high-magnification scanning electron microscopy and etching we expose the nanometre-scale structures within the cell walls and interfilament. Fibrils concentrate at the internal and external edges of the cell walls. Fibrils  ∼  10 nm thick appear to thread through the radial Mg-calcite grains and form concentric bands within the cell wall. This banding may control Mg distribution within the cell. Similar fibril banding is present in the hypothallial cell walls but not the interfilament. Climate archiving with corallines can achieve greater precision with recognition of these parameters.

Groundwater quality in Coachella Valley, California

Science.gov (United States)

Dawson, Barbara J. Milby; Belitz, Kenneth

2012-01-01

Groundwater provides more than 40 percent of California’s drinking water. To protect this vital resource, the State of California created the Groundwater Ambient Monitoring and Assessment (GAMA) Program. The Priority Basin Project of the GAMA Program provides a comprehensive assessment of the State’s groundwater quality and increases public access to groundwater-quality information. Coachella Valley is one of the study areas being evaluated. The Coachella study area is approximately 820 square miles (2,124 square kilometers) and includes the Coachella Valley groundwater basin (California Department of Water Resources, 2003). Coachella Valley has an arid climate, with average annual rainfall of about 6 inches (15 centimeters). The runoff from the surrounding mountains drains to rivers that flow east and south out of the study area to the Salton Sea. Land use in the study area is approximately 67 percent (%) natural, 21% agricultural, and 12% urban. The primary natural land cover is shrubland. The largest urban areas are the cities of Indio and Palm Springs (2010 populations of 76,000 and 44,000, respectively). Groundwater in this basin is used for public and domestic water supply and for irrigation. The main water-bearing units are gravel, sand, silt, and clay derived from surrounding mountains. The primary aquifers in Coachella Valley are defined as those parts of the aquifers corresponding to the perforated intervals of wells listed in the California Department of Public Health database. Public-supply wells in Coachella Valley are completed to depths between 490 and 900 feet (149 to 274 meters), consist of solid casing from the land surface to a depth of 260 to 510 feet (79 to 155 meters), and are screened or perforated below the solid casing. Recharge to the groundwater system is primarily runoff from the surrounding mountains, and by direct infiltration of irrigation. The primary sources of discharge are pumping wells, evapotranspiration, and underflow to

Nonvascular contribution to ecosystem NPP in a subarctic heath during early and late growing season

DEFF Research Database (Denmark)

Campioli, Matteo; Samson, Roeland; Michelsen, Anders

2009-01-01

significant when vascular plants are less active and ecosystems act as a source of carbon (C). To clarify these dynamics, nonvascular and vascular aboveground NPP was compared for a subarctic heath during two contrasting periods of the growing season, viz. early-mid summer and late summer-early autumn...... measurements of shoot length increase. Vascular NPP was determined by harvesting shrub and herb apical growth and considering production due to stem secondary growth of shrubs. Hylocomium splendens and Pleurozium schreberi showed highest biomass growth in late summer, whereas for D. elongatum this occurred...... weight m-2 d-1, in early and late summer, respectively, whereas in the same periods vascular NPP was 3.6 and 1.1 g dry weight m-2 d-1. The contribution of nonvascular NPP to total aboveground NPP was therefore minor in early summer but substantial in late summer, when 25% of the C accumulated...

Feasibility analysis of a smart grid photovoltaics system for the subarctic rural region in Alaska

Science.gov (United States)

Yao, Lei

A smart grid photovoltaics system was developed to demonstrate that the system is feasible for a similar off-grid rural community in the subarctic region in Alaska. A system generation algorithm and a system business model were developed to determine feasibility. Based on forecasts by the PV F-Chart software, a 70° tilt angle in winter, and a 34° tilt angle in summer were determined to be the best angles for electrical output. The proposed system's electricity unit cost was calculated at 32.3 cents/kWh that is cheaper than current unsubsidized electricity price (46.8 cents/kWh) in off-grid rural communities. Given 46.8 cents/kWh as the electricity unit price, the system provider can break even when 17.3 percent of the total electrical revenue through power generated by the proposed system is charged. Given these results, the system can be economically feasible during the life-cycle period. With further incentives, the system may have a competitive advantage.

The relative contributions of biological and abiotic processes to carbon dynamics in subarctic sea ice

DEFF Research Database (Denmark)

Søgaard, Dorte Haubjerg; Thomas, David; Rysgaard, Søren

2013-01-01

Knowledge on the relative effects of biological activity and precipitation/dissolution of calcium carbonate (CaCO3) in influencing the air-ice CO2 exchange in sea-ice-covered season is currently lacking. Furthermore, the spatial and temporal occurrence of CaCO3 and other biogeochemical parameters...... in sea ice are still not well described. Here we investigated autotrophic and heterotrophic activity as well as the precipitation/dissolution of CaCO3 in subarctic sea ice in South West Greenland. Integrated over the entire ice season (71 days), the sea ice was net autotrophic with a net carbon fixation...... and CaCO3 precipitation. The net biological production could only explain 4 % of this sea-ice-driven CO2 uptake. Abiotic processes contributed to an air-sea CO2 uptake of 1.5 mmol m(-2) sea ice day(-1), and dissolution of CaCO3 increased the air-sea CO2 uptake by 36 % compared to a theoretical estimate...

Numerical responses of saproxylic beetles to rapid increases in dead wood availability following geometrid moth outbreaks in sub-arctic mountain birch forest.

Science.gov (United States)

Vindstad, Ole Petter Laksforsmo; Schultze, Sabrina; Jepsen, Jane Uhd; Biuw, Martin; Kapari, Lauri; Sverdrup-Thygeson, Anne; Ims, Rolf Anker

2014-01-01

Saproxylic insects play an important part in decomposing dead wood in healthy forest ecosystems, but little is known about their role in the aftermath of large-scale forest mortality caused by pest insect outbreaks. We used window traps to study short-term changes in the abundance and community structure of saproxylic beetles following extensive mortality of mountain birch in sub-arctic northern Norway caused by an outbreak of geometrid moths. Three to five years after the outbreak, the proportion of obligate saproxylic individuals in the beetle community was roughly 10% higher in forest damaged by the outbreak than in undamaged forest. This was mainly due to two early-successional saproxylic beetle species. Facultative saproxylic beetles showed no consistent differences between damaged and undamaged forest. These findings would suggest a weak numerical response of the saproxylic beetle community to the dead wood left by the outbreak. We suggest that species-specific preferences for certain wood decay stages may limit the number of saproxylic species that respond numerically to an outbreak at a particular time, and that increases in responding species may be constrained by limitations to the amount of dead wood that can be exploited within a given timeframe (i.e. satiation effects). Low diversity of beetle species or slow development of larvae in our cold sub-arctic study region may also limit numerical responses. Our study suggests that saproxylic beetles, owing to weak numerical responses, may so far have played a minor role in decomposing the vast quantities of dead wood left by the moth outbreak.

Numerical responses of saproxylic beetles to rapid increases in dead wood availability following geometrid moth outbreaks in sub-arctic mountain birch forest.

Directory of Open Access Journals (Sweden)

Ole Petter Laksforsmo Vindstad

Full Text Available Saproxylic insects play an important part in decomposing dead wood in healthy forest ecosystems, but little is known about their role in the aftermath of large-scale forest mortality caused by pest insect outbreaks. We used window traps to study short-term changes in the abundance and community structure of saproxylic beetles following extensive mortality of mountain birch in sub-arctic northern Norway caused by an outbreak of geometrid moths. Three to five years after the outbreak, the proportion of obligate saproxylic individuals in the beetle community was roughly 10% higher in forest damaged by the outbreak than in undamaged forest. This was mainly due to two early-successional saproxylic beetle species. Facultative saproxylic beetles showed no consistent differences between damaged and undamaged forest. These findings would suggest a weak numerical response of the saproxylic beetle community to the dead wood left by the outbreak. We suggest that species-specific preferences for certain wood decay stages may limit the number of saproxylic species that respond numerically to an outbreak at a particular time, and that increases in responding species may be constrained by limitations to the amount of dead wood that can be exploited within a given timeframe (i.e. satiation effects. Low diversity of beetle species or slow development of larvae in our cold sub-arctic study region may also limit numerical responses. Our study suggests that saproxylic beetles, owing to weak numerical responses, may so far have played a minor role in decomposing the vast quantities of dead wood left by the moth outbreak.

Seasonal and spatial patterns of heterotrophic bacterial production, respiration, and biomass in the subarctic NE Pacific

Science.gov (United States)

Sherry, Nelson D.; Boyd, Philip W.; Sugimoto, Kugako; Harrison, Paul J.

1999-11-01

Heterotrophic bacterial biomass, production, and respiration rates were measured during winter, spring, and summer in the subarctic NE Pacific from September 1995 to June 1997. Sampling took place on six cruises at five hydrographic stations along the east/west line-P transect from slope waters at P4 (1200 m depth) to the open-ocean waters at Ocean Station Papa (OSP) (4250 m depth). Interannual variability was small relative to seasonal and spatial variability. Biomass, derived from cell counts (assuming 20 fg C cell -1), was ca. 12 μg C l -1 in the winter and increased to 20-35 μg C l -1 in the spring and summer all along line-P. Bacterial production from [ 3H]-thymidine and [ 14C]-leucine incorporation rates was lowest in the winter (ca. 0.5 μg C l -1 d -1) with little spatial variability. Production increased 10-fold in spring at P4 (to ca. 4.5 μg C l -1 d -1). In contrast, only a 2-fold increase in bacterial production was observed over this period at the more oceanic stations. Rates of production in late summer were highest over the annual cycle at all stations ranging from ca. 6 at P4 to ca. 2 μg C l -1 d -1 at OSP. Bacterial (rates increased >10-fold to ca. 100 μg C l -1 d -1 at P4 in the summer, but, interestingly, did not increase from spring to summer at the more oceanic stations. Thus bacterial growth efficiency, defined as production/(production+respiration), decreased in the spring westwards from the slope waters (P4) to the open-ocean (OSP), but increased westwards in the summer. Bacterial production was highly correlated with temperature at OSP ( r2=0.88) and less so at P4 ( r2=0.50). The observed temporal and spatial trends presented in this study suggest that seasonal changes in bacterial biomass were greatly affected by changes in loss processes, that bacterial biomass is regulated by different processes than bacterial production, and that bacterial production alone, without respiration measurements, is not a robust proxy for bacterial

EPA Region 1 - Map Layers for Valley ID Tool (Hosted Feature Service)

Science.gov (United States)

The Valley Service Feature Layer hosts spatial data for EPA Region 1's Valley Identification Tool. These layers contain attribute information added by EPA R1 GIS Center to help identify populated valleys:- Fac_2011NEI: Pollution sources selected from the National Emissions Inventory (EPA, 2011).- NE_Towns_PopValleys: New England Town polygons (courtesy USGS), with Population in Valleys and Population Density in Valleys calculated by EPA R1 GIS, from 2010 US Census blocks. - VT_E911: Vermont residences (courtesy VT Center for Geographic Information E-911).

Valley photonic crystals for control of spin and topology

Energy Technology Data Exchange (ETDEWEB)

Dong, Jian-Wen; Chen, Xiao-Dong; Zhu, Hanyu; Wang, Yuan; Zhang, Xiang

2016-11-28

Photonic crystals offer unprecedented opportunity for light manipulation and applications in optical communication and sensing1,2,3,4. Exploration of topology in photonic crystals and metamaterials with non-zero gauge field has inspired a number of intriguing optical phenomena such as one-way transport and Weyl points5,6,7,8,9,10. Recently, a new degree of freedom, valley, has been demonstrated in two-dimensional materials11,12,13,14,15. Here, we propose a concept of valley photonic crystals with electromagnetic duality symmetry but broken inversion symmetry. We observe photonic valley Hall effect originating from valley-dependent spin-split bulk bands, even in topologically trivial photonic crystals. Valley–spin locking behaviour results in selective net spin flow inside bulk valley photonic crystals. We also show the independent control of valley and topology in a single system that has been long pursued in electronic systems, resulting in topologically-protected flat edge states. Valley photonic crystals not only offer a route towards the observation of non-trivial states, but also open the way for device applications in integrated photonics and information processing using spin-dependent transportation.

Albemarle Sound demonstration study of the national monitoring network for US coastal waters and their tributaries

Science.gov (United States)

Michelle Moorman; Sharon Fitzgerald; Keith Loftin; Elizabeth Fensin

2016-01-01

The U.S. Geological Survey’s (USGS) is implementing a demonstration project in the Albemarle Sound for the National Monitoring Network for U.S. coastal waters and their tributaries. The goal of the National Monitoring Network is to provide information about the health of our oceans and coastal ecosystems and inland influences on coastal waters for improved resource...

Geologic features of the Connecticut Valley, Massachusetts, as related to recent floods

Science.gov (United States)

Jahns, Richard Henry

1947-01-01

This report gives the results of a geologic study of certain features that bear upon the recent flood behavior of rivers flowing in the Massachusetts part of the Connecticut Valley. It is in part an outline of the physiographic history of the Connecticut River, a 'history that is treated in progressively greater detail as it concerns events occurring from Mesozoic time to the present, and in part a discussion of erosional and depositional processes associated with the extraordinary floods of March 1936 and September 1938. The Connecticut River flows southward through Massachusetts in a broad lowland area of more than 400 square miles and is joined in this area by four large tributaries, the Deerfield and Westfield Rivers from the west and the Millers and Chicopee Rivers from the east. The lowland area, or :Connecticut Valley province, is flanked on the west by the Berkshire Hills, a, deeply incised uplifted plateau, and on the east by the central upland, or Worcester .County plateau, a lower upland marked by rolling topography. Most of the broad, relatively flat valley floor is underlain by Triassic sedimentary rocks. Rising above it, however, are the prominent Holyoke-Mount Tom and Deerfield Ranges, which consist in large part of dark-colored igneous rocks, also of Triassic age. There is evidence of several cycles of erosion in central western Massachusetts, the last two of which are of Tertiary age and appear to have reached nature and very youthful stages of topographic development, respectively. Immediately prior to the glacial epoch, therefore, the Connecticut River flowed in a fairly narrow, deep gorge, which it had incised in the rather flat 5ottom of the valley that it had formed at an earlier stage. A Pleistocene crustal subsidence probably of several hundred feet, for which there has been only partial compensation in postglacial time, was responsible for the present position of much of this gorge below sea level. That an estuary does not now occupy the

Breathing Valley Fever

Centers for Disease Control (CDC) Podcasts

2014-02-04

Dr. Duc Vugia, chief of the Infectious Diseases Branch in the California Department of Public Health, discusses Valley Fever.  Created: 2/4/2014 by National Center for Emerging and Zoonotic Infectious Diseases (NCEZID).   Date Released: 2/5/2014.

Groundwater-flow and land-subsidence model of Antelope Valley, California

Science.gov (United States)

Siade, Adam J.; Nishikawa, Tracy; Rewis, Diane L.; Martin, Peter; Phillips, Steven P.

2014-01-01

Antelope Valley, California, is a topographically closed basin in the western part of the Mojave Desert, about 50 miles northeast of Los Angeles. The Antelope Valley groundwater basin is about 940 square miles and is separated from the northern part of Antelope Valley by faults and low-lying hills. Prior to 1972, groundwater provided more than 90 percent of the total water supply in the valley; since 1972, it has provided between 50 and 90 percent. Most groundwater pumping in the valley occurs in the Antelope Valley groundwater basin, which includes the rapidly growing cities of Lancaster and Palmdale. Groundwater-level declines of more than 270 feet in some parts of the groundwater basin have resulted in an increase in pumping lifts, reduced well efficiency, and land subsidence of more than 6 feet in some areas. Future urban growth and limits on the supply of imported water may increase reliance on groundwater.

Phytoplankton growth and herbivory in the subarctic Pacific: A chemotaxonomic analysis

International Nuclear Information System (INIS)

Welschmeyer, N.; Goericke, R.; Strom, S.; Peterson, W.

1991-01-01

Chlorophyll crops in the subarctic Pacific are low and relatively constant throughout the year; however, net growth of phytoplankton occurs when natural water is enclosed in incubation containers and exposed to adequate irradiance. Pigment-based measurements of taxon-specific growth rates and taxon-specific grazing pressure were made in an attempt to understand the dynamic processes leading to the net growth of phytoplankton in bottles. Specific growth rates, determined from 14 C labeling of chromatographically separated pigments showed that fucoxanthin-containing cells (diatoms) were the fastest growing microalgae; a rapid net accumulation of fucoxanthin also occurred. Independent measurements of specific growth rates, determined from chromatographic analysis of microzooplankton dilution experiments, also showed that fucoxanthin-containing cells had the highest specific growth rates. Importantly, microzooplankton grazing rates on fucoxanthin-containing cells were only about half the specific growth rate; hence, the resultant bloom of fucoxanthin. The authors speculate that the lag in chlorophyll growth that has been reported previously is an artifact of subculturing; fast-growing, but dilute, fucoxanthin-containing cells do not become a significant portion of the total chlorophyll signal until late in the experiment. Other diagnostic carotenoids, such as 19'-hexanoyloxyfucoxanthin and 19'-butanoyloxyfucoxanthin, remained nearly constant through long-term incubations. However, they became actively 14 C labeled and showed positive specific rates of growth. Dilution experiments showed that their specific growth rate was compensated by microzooplankton grazing

Organic iron (III) complexing ligands during an iron enrichment experiment in the western subarctic North Pacific

Science.gov (United States)

Kondo, Yoshiko; Takeda, Shigenobu; Nishioka, Jun; Obata, Hajime; Furuya, Ken; Johnson, William Keith; Wong, C. S.

2008-06-01

Complexation of iron (III) with natural organic ligands was investigated during a mesoscale iron enrichment experiment in the western subarctic North Pacific (SEEDS II). After the iron infusions, ligand concentrations increased rapidly with subsequent decreases. While the increases of ligands might have been partly influenced by amorphous iron colloids formation (12-29%), most in-situ increases were attributable to the Dilution of the fertilized patch may have contributed to the rapid decreases of the ligands. During the bloom decline, ligand concentration increased again, and the high concentrations persisted for 10 days. The conditional stability constant was not different between inside and outside of the fertilized patch. These results suggest that the chemical speciation of the released iron was strongly affected by formation of the ligands; the production of ligands observed during the bloom decline will strongly impact the iron cycle and bioavailability in the surface water.

Enhanced valley splitting in monolayer WSe2 due to magnetic exchange field.

Science.gov (United States)

Zhao, Chuan; Norden, Tenzin; Zhang, Peiyao; Zhao, Puqin; Cheng, Yingchun; Sun, Fan; Parry, James P; Taheri, Payam; Wang, Jieqiong; Yang, Yihang; Scrace, Thomas; Kang, Kaifei; Yang, Sen; Miao, Guo-Xing; Sabirianov, Renat; Kioseoglou, George; Huang, Wei; Petrou, Athos; Zeng, Hao

2017-08-01

Exploiting the valley degree of freedom to store and manipulate information provides a novel paradigm for future electronics. A monolayer transition-metal dichalcogenide (TMDC) with a broken inversion symmetry possesses two degenerate yet inequivalent valleys, which offers unique opportunities for valley control through the helicity of light. Lifting the valley degeneracy by Zeeman splitting has been demonstrated recently, which may enable valley control by a magnetic field. However, the realized valley splitting is modest (∼0.2 meV T -1 ). Here we show greatly enhanced valley spitting in monolayer WSe 2 , utilizing the interfacial magnetic exchange field (MEF) from a ferromagnetic EuS substrate. A valley splitting of 2.5 meV is demonstrated at 1 T by magnetoreflectance measurements and corresponds to an effective exchange field of ∼12 T. Moreover, the splitting follows the magnetization of EuS, a hallmark of the MEF. Utilizing the MEF of a magnetic insulator can induce magnetic order and valley and spin polarization in TMDCs, which may enable valleytronic and quantum-computing applications.

Activity and diversity of methane-oxidizing bacteria along a Norwegian sub-Arctic glacier forefield.

Science.gov (United States)

Mateos-Rivera, Alejandro; Øvreås, Lise; Wilson, Bryan; Yde, Jacob C; Finster, Kai W

2018-05-01

Methane (CH4) is one of the most abundant greenhouse gases in the atmosphere and identification of its sources and sinks is crucial for the reliability of climate model outputs. Although CH4 production and consumption rates have been reported from a broad spectrum of environments, data obtained from glacier forefields are restricted to a few locations. We report the activities of methanotrophic communities and their diversity along a chronosequence in front of a sub-Arctic glacier using high-throughput sequencing and gas flux measurements. CH4 oxidation rates were measured in the field throughout the growing season during three sampling times at eight different sampling points in combination with laboratory incubation experiments. The overall results showed that the methanotrophic community had similar trends of increased CH4 consumption and increased abundance as a function of soil development and time of year. Sequencing results revealed that the methanotrophic community was dominated by a few OTUs and that a short-term increase in CH4 concentration, as performed in the field measurements, altered slightly the relative abundance of the OTUs.

Baseline Channel Geometry and Aquatic Habitat Data for Selected Streams in the Matanuska-Susitna Valley, Alaska

Science.gov (United States)

Curran, Janet H.; Rice, William J.

2009-01-01

Small streams in the rapidly developing Matanuska-Susitna Valley in south-central Alaska are known to support anadromous and resident fish but little is known about their hydrologic and riparian conditions, or their sensitivity to the rapid development of the area or climate variability. To help address this need, channel geometry and aquatic habitat data were collected in 2005 as a baseline of stream conditions for selected streams. Three streams were selected as representative of various stream types, and one drainage network, the Big Lake drainage basin, was selected for a systematic assessment. Streams in the Big Lake basin were drawn in a Geographic Information System (GIS), and 55 reaches along 16 miles of Meadow Creek and its primary tributary Little Meadow Creek were identified from orthoimagery and field observations on the basis of distinctive physical and habitat parameters, most commonly gradient, substrate, and vegetation. Data-collection methods for sites at the three representative reaches and the 55 systematically studied reaches consisted of a field survey of channel and flood-plain geometry and collection of 14 habitat attributes using published protocols or slight modifications. Width/depth and entrenchment ratios along the Meadow-Little Meadow Creek corridor were large and highly variable upstream of Parks Highway and lower and more consistent downstream of Parks Highway. Channel width was strongly correlated with distance, increasing downstream in a log-linear relation. Runs formed the most common habitat type, and instream vegetation dominated the habitat cover types, which collectively covered 53 percent of the channel. Gravel suitable for spawning covered isolated areas along Meadow Creek and about 29 percent of Little Meadow Creek. Broad wetlands were common along both streams. For a comprehensive assessment of small streams in the Mat-Su Valley, critical additional data needs include hydrologic, geologic and geomorphic, and biologic data

Potential hydrologic characterization wells in Amargosa Valley

International Nuclear Information System (INIS)

Lyles, B.; Mihevc, T.

1994-09-01

More than 500 domestic, agricultural, and monitoring wells were identified in the Amargosa Valley. From this list, 80 wells were identified as potential hydrologic characterization wells, in support of the US Department of Energy (DOE) Underground Test Area/Remedial Investigation and Feasibility Study (UGTA/RIFS). Previous hydrogeologic studies have shown that groundwater flow in the basin is complex and that aquifers may have little lateral continuity. Wells located more than 10 km or so from the Nevada Test Site (NTS) boundary may yield data that are difficult to correlate to sources from the NTS. Also, monitoring well locations should be chosen within the guidelines of a hydrologic conceptual model and monitoring plan. Since these do not exist at this time, recompletion recommendations will be restricted to wells relatively close (approximately 20 km) to the NTS boundary. Recompletion recommendations were made for two abandoned agricultural irrigation wells near the town of Amargosa Valley (previously Lathrop Wells), for two abandoned wildcat oil wells about 10 km southwest of Amargosa Valley, and for Test Well 5 (TW-5), about 10 km east of Amargosa Valley

Effects of fluvial processes in different order river valleys on redistribution and storage of particle-bound radioactive caesium-137 in area of significant Chernobyl fallout and impact on linked rivers with lower contamination levels

Science.gov (United States)

Belyaev, Vladimir; Golosov, Valentin; Shamshurina, Evgeniya; Ivanov, Maxim; Ivanova, Nadezhda; Bezukhov, Dmitry; Onda, Yuichi; Wakiyama, Yoshifumi; Evrard, Olivier

2015-04-01

Detailed investigations of the post-fallout fate of radionuclide contamination represent an important task in terms of environmental quality assessment. In addition, particle-bound radionuclides such as the most widespread anthropogenic isotope caesium-137 can be used as tracers for quantitative assessment of different sediment redistribution processes. In landscapes of humid plains with agriculture-dominated land use the post-fallout redistribution of caesium-137 is primarily associated with fluvial activity of various scales in cascade systems starting from soil erosion on cultivated hillslopes through gully and small dry valley network into different order perennial streams and rivers. Our investigations in the so-called Plavsk hotspot (area of very high Chernobyl caesium-137 contamination within the Plava River basin, Tula Region, Central European Russia) has been continuing for more than 15 years by now, while the time passed since the Chernobyl disaster and associated radioactive fallout (1986) is almost 29 years. Detailed information on the fluvial sediment and associated caesium-137 redistribution has been obtained for case study sites of different size from individual cultivated slopes and small catchments of different size (2-180 km2) to the entire Plava River basin scale (1856 km2). It has been shown that most of the contaminated sediment over the time passed since the fallout has remained stored within the small dry valleys of the 1-4 Hortonian order and local reservoirs (>70%), while only about 5% reached the 5-6 order valleys (main tributaries of the Plava River) and storage of the Plava floodplain itself represents as low as 0.3% of the basin-scale total sediment production from eroded cultivated hillslopes. Nevertheless, it has been shown that contaminated sediment yield from the Plava River basin exerts significant influence on less polluted downstream-linked river system. Recent progress of the investigations involved sampling of 7 detailed depth

MX Siting Investigation. Gravity Survey - Sevier Desert Valley, Utah.

Science.gov (United States)

1981-01-24

Cheyenne, Wyoming. DMAHTC reduces the data to Simple Bouguer Anomaly (see Section A1.4, Appendix Al.0). The Defense Mapping Agency Aerospace Center...Desert Valley, Utah ......... 2 2 Topographic Setting - Sevier Desert Valley, Utah . 3 LIST OF DRAWINGS Drawing Number 1 Complete Bouguer Anomaly...gravity stations were distributed throughout the valley at an approxi- mate interval of 1.4 miles (2.3 km). Drawing 1 is a Complete Bouguer Anomaly

Sutter Buttes-the lone volcano in California's Great Valley

Science.gov (United States)

Hausback, Brain P.; Muffler, L.J. Patrick; Clynne, Michael A.

2011-01-01

The volcanic spires of the Sutter Buttes tower 2,000 feet above the farms and fields of California's Great Valley, just 50 miles north-northwest of Sacramento and 11 miles northwest of Yuba City. The only volcano within the valley, the Buttes consist of a central core of volcanic domes surrounded by a large apron of fragmental volcanic debris. Eruptions at the Sutter Buttes occurred in early Pleistocene time, 1.6 to 1.4 million years ago. The Sutter Buttes are not part of the Cascade Range of volcanoes to the north, but instead are related to the volcanoes in the Coast Ranges to the west in the vicinity of Clear Lake, Napa Valley, and Sonoma Valley.

Gravity and magnetic data of Midway Valley, southwest Nevada

International Nuclear Information System (INIS)

Ponce, D.A.; Langenheim, V.E.; Sikora, R.F.

1993-01-01

Detailed gravity and ground magnetic data collected along five traverses across Midway Valley on the eastern flank of Yucca Mountain in southwest Nevada are described. These data were collected as part of an effort to evaluate faulting in the vicinity of proposed surface facilities for a potential nuclear waste repository at Yucca Mountain. Geophysical data show that Midway Valley is bounded by large gravity and magnetic anomalies associated with the Bow Ridge and Paintbrush Canyon faults, on the west side of Exile Hill and on the west flank of Fran Ridge, respectively. In addition, Midway Valley itself is characterized by a number of small-amplitude anomalies that probably reflect small-scale faulting beneath Midway Valley

27 CFR 9.208 - Snake River Valley.

Science.gov (United States)

2010-04-01

... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Snake River Valley. 9.208... Snake River Valley. (a) Name. The name of the viticultural area described in this section is “Snake River Valley”. For purposes of part 4 of this chapter, “Snake River Valley” is a term of viticultural...

Subglacial tunnel valleys in the Alpine foreland: an example from Bern, Switzerland

International Nuclear Information System (INIS)

Duerst Stucki, M.; Reber, R.; Schlunegger, F.

2010-01-01

The morphology of the Alpine and adjacent landscapes is directly related to glacial erosion and associated sediment transport. Here we report the effects of glacio-hydrologic erosion on bedrock topography in the Swiss Plateau. Specifically, we identify the presence of subsurface valleys beneath the city of Bern and discuss their genesis. Stratigraphic investigations of more than 4'000 borehole data within a 430 km 2 -large area reveal the presence of a network of >200 m-deep and 1'000 m-wide valleys. They are flat floored with steep sided walls and are filled by Quaternary glacial deposits. The central valley beneath Bern is straight and oriented towards the NNW, with valley flanks more than 20 o steep. The valley bottom has an irregular undulating profile along the thalweg, with differences between sills and hollows higher than 50-100 m over a reach of 4 km length. Approximately 500 m high bedrock highlands flank the valley network. The highlands are dissected by up to 80 m-deep and 500 m-broad hanging valleys that currently drain away from the axis of the main valley. We interpret the valleys beneath the city of Bern to be a tunnel valley network which originated from subglacial erosion by melt water. The highland valleys served as proglacial meltwater paths and are hanging with respect to the trunk system, indicating that these incipient highland systems as well as the main gorge beneath Bern formed by glacial melt water under pressure. (authors)

Gate-tunable valley-spin filtering in silicene with magnetic barrier

Energy Technology Data Exchange (ETDEWEB)

Wu, X. Q., E-mail: xianqiangzhe@126.com [National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093 (China); Meng, H. [School of Physics and Telecommunication Engineering, Shanxi University of Technology, Hanzhong 723001 (China)

2015-05-28

We theoretically study the valley- and spin-resolved scattering through magnetic barrier in a one layer thick silicene, using the mode-matching method for the Dirac equation. We show that the spin-valley filtering effect can be achieved and can also be tuned completely through both a top and bottom gate. Moreover, when reversing the sign of the staggered potential, we find the direction of the valley polarization is switched while the direction of spin polarization is unchanged. These results can provide some meaningful information to design valley valve residing on silicene.

Investigation on the 1970s and 1980s droughts in four tributaries of the Niger River Basin (West Africa).

CSIR Research Space (South Africa)

Badou, DF

2015-07-01

Full Text Available this question, we evaluated spatio-temporal pattern of rainfall and runoff in four tributaries (Sota, Alibori, Mekrou and Kompa-gorou) of the Niger River basin, covering a total area of 40,000km2 for the period 1971 to 2010. First, decadal rainfall variability...

VALDRIFT 1.0: A valley atmospheric dispersion model with deposition

Energy Technology Data Exchange (ETDEWEB)

Allwine, K.J.; Bian, X.; Whiteman, C.D.

1995-05-01

VALDRIFT version 1.0 is an atmospheric transport and diffusion model for use in well-defined mountain valleys. It is designed to determine the extent of ddft from aedal pesticide spraying activities, but can also be applied to estimate the transport and diffusion of various air pollutants in valleys. The model is phenomenological -- that is, the dominant meteorological processes goveming the behavior of the valley atmosphere are formulated explicitly in the model, albeit in a highly parameterized fashion. The key meteorological processes treated are: (1) nonsteady and nonhomogeneous along-valley winds and turbulent diffusivities, (2) convective boundary layer growth, (3) inversion descent, (4) noctumal temperature inversion breakup, and (5) subsidence. The model is applicable under relatively cloud-free, undisturbed synoptic conditions and is configured to operate through one diumal cycle for a single valley. The inputs required are the valley topographical characteristics, pesticide release rate as a function of time and space, along-valley wind speed as a function of time and space, temperature inversion characteristics at sunrise, and sensible heat flux as a function of time following sunrise. Default values are provided for certain inputs in the absence of detailed observations. The outputs are three-dimensional air concentration and ground-level deposition fields as a function of time.

Valley-selective optical Stark effect probed by Kerr rotation

Science.gov (United States)

LaMountain, Trevor; Bergeron, Hadallia; Balla, Itamar; Stanev, Teodor K.; Hersam, Mark C.; Stern, Nathaniel P.

2018-01-01

The ability to monitor and control distinct states is at the heart of emerging quantum technologies. The valley pseudospin in transition metal dichalcogenide (TMDC) monolayers is a promising degree of freedom for such control, with the optical Stark effect allowing for valley-selective manipulation of energy levels in WS2 and WSe2 using ultrafast optical pulses. Despite these advances, understanding of valley-sensitive optical Stark shifts in TMDCs has been limited by reflectance-based detection methods where the signal is small and prone to background effects. More sensitive polarization-based spectroscopy is required to better probe ultrafast Stark shifts for all-optical manipulation of valley energy levels. Here, we show time-resolved Kerr rotation to be a more sensitive probe of the valley-selective optical Stark effect in monolayer TMDCs. Compared to the established time-resolved reflectance methods, Kerr rotation is less sensitive to background effects. Kerr rotation provides a fivefold improvement in the signal-to-noise ratio of the Stark effect optical signal and a more precise estimate of the energy shift. This increased sensitivity allows for observation of an optical Stark shift in monolayer MoS2 that exhibits both valley and energy selectivity, demonstrating the promise of this method for investigating this effect in other layered materials and heterostructures.

Four newly recorded species of Dryopteridaceae from Kashmir valley, India

Directory of Open Access Journals (Sweden)

SHAKOOR AHMAD MIR

2014-04-01

Full Text Available Mir SA, Mishra AK, Reshi ZA, Sharma MP. 2014. Four newly recorded species of Dryopteridaceae from Kashmir valley, India. Biodiversitas 15: 6-11. Habitat diversity, elevation, cloud cover, rainfall, seasonal and temperature variations have created many ideal sites for the luxuriant growth of pteridophytes in the Kashmir valley, yet all the regions of the valley have not been surveyed. In Kashmir valley the family Dryopteridaceae is represented by 31 species. During the recent extensive field surveys of Shopian district four more species viz., Dryopteris caroli-hopei Fraser-Jenkins, Dryopteris blanfordii subsp. nigrosquamosa (Ching Fraser-Jenkins, Dryopteris pulvinulifera (Bedd. Kuntze and Polystichum Nepalense (Spreng C. Chr. have been recorded for the first time from the valley. The taxonomic description, synonyms, distribution and photographs of each species are given in this article.

Impact of decade-long warming, nutrient addition and shading on emission and carbon isotopic composition of CO2 from two subarctic dwarf shrub heaths

DEFF Research Database (Denmark)

Ravn, Nynne R.; Ambus, Per Lennart; Michelsen, Anders

2017-01-01

This study investigated ecosystem respiration, soil respiration and carbon isotopic composition in CO2 emitted from two subarctic shrub heaths with contrasting moisture regimes. The reported measurements were conducted 22 years (mesic heath) and 12 years (wet heath) upon initiation of in situ...... the growing season. However, there was a tendency across growing season towards an increased δ13C source value after 22 years of warming in the mesic shrub heath, and the effect was statistically significant in June, indicating increased decomposition of 13C enriched material. Hence, although more of the old...

Ventilation potential during the emissions survey in Toluca Valley, Mexico

Science.gov (United States)

Ruiz Angulo, A.; Peralta, O.; Jurado, O. E.; Ortinez, A.; Grutter de la Mora, M.; Rivera, C.; Gutierrez, W.; Gonzalez, E.

2017-12-01

During the late-spring early-summer measurements of emissions and pollutants were carried out during a survey campaign at four different locations within the Toluca Valley. The current emissions inventory typically estimates the generation of pollutants based on pre-estimated values representing an entire sector function of their activities. However, those factors are not always based direct measurements. The emissions from the Toluca Valley are rather large and they could affect the air quality of Mexico City Valley. The air masses interchange between those two valleys is not very well understood; however, based on the measurements obtained during the 3 months campaign we looked carefully at the daily variability of the wind finding a clear signal for mountain-valley breeze. The ventilation coefficient is estimated and the correlations with the concentrations at the 4 locations and in a far away station in Mexico City are addressed in this work. Finally, we discuss the implication of the ventilation capacity in air quality for the system of Valleys that include Mexico City.

Aerial radiological survey of the creeks and tributaries near the Rancho Seco Nuclear Generation Station, Clay Station, California. Date of survey: December 1984

International Nuclear Information System (INIS)

1986-06-01

Radiological contamination due to man-made radionuclides was detected using hand-held instruments in the summer of 1984 in the creeks and tributaries near the Rancho Seco Nuclear Generating Station at Clay Station, California. To help determine the extent of the contamination an aerial radiological survey centered over the creeks and tributaries and including the Rancho Seco facility was conducted during the period 3 to 15 December 1984. Radiological contaminants were detected along a 9-mile segment of the system of creeks in the area. These contaminants included cesium-134, cesium-137, and cobalt-60. Radiation measurements away from the contaminated areas were the same as those made during the aerial radiological survey conducted in 1980

Fitness-valley crossing with generalized parent-offspring transmission.

Science.gov (United States)

Osmond, Matthew M; Otto, Sarah P

2015-11-01

Simple and ubiquitous gene interactions create rugged fitness landscapes composed of coadapted gene complexes separated by "valleys" of low fitness. Crossing such fitness valleys allows a population to escape suboptimal local fitness peaks to become better adapted. This is the premise of Sewall Wright's shifting balance process. Here we generalize the theory of fitness-valley crossing in the two-locus, bi-allelic case by allowing bias in parent-offspring transmission. This generalization extends the existing mathematical framework to genetic systems with segregation distortion and uniparental inheritance. Our results are also flexible enough to provide insight into shifts between alternate stable states in cultural systems with "transmission valleys". Using a semi-deterministic analysis and a stochastic diffusion approximation, we focus on the limiting step in valley crossing: the first appearance of the genotype on the new fitness peak whose lineage will eventually fix. We then apply our results to specific cases of segregation distortion, uniparental inheritance, and cultural transmission. Segregation distortion favouring mutant alleles facilitates crossing most when recombination and mutation are rare, i.e., scenarios where crossing is otherwise unlikely. Interactions with more mutable genes (e.g., uniparental inherited cytoplasmic elements) substantially reduce crossing times. Despite component traits being passed on poorly in the previous cultural background, small advantages in the transmission of a new combination of cultural traits can greatly facilitate a cultural transition. While peak shifts are unlikely under many of the common assumptions of population genetic theory, relaxing some of these assumptions can promote fitness-valley crossing. Copyright © 2015 Elsevier Inc. All rights reserved.

Subglacial tunnel valleys in the Alpine foreland: an example from Bern, Switzerland

Energy Technology Data Exchange (ETDEWEB)

Duerst Stucki, M.; Reber, R.; Schlunegger, F.

2010-12-15

The morphology of the Alpine and adjacent landscapes is directly related to glacial erosion and associated sediment transport. Here we report the effects of glacio-hydrologic erosion on bedrock topography in the Swiss Plateau. Specifically, we identify the presence of subsurface valleys beneath the city of Bern and discuss their genesis. Stratigraphic investigations of more than 4'000 borehole data within a 430 km{sup 2}-large area reveal the presence of a network of >200 m-deep and 1'000 m-wide valleys. They are flat floored with steep sided walls and are filled by Quaternary glacial deposits. The central valley beneath Bern is straight and oriented towards the NNW, with valley flanks more than 20 {sup o} steep. The valley bottom has an irregular undulating profile along the thalweg, with differences between sills and hollows higher than 50-100 m over a reach of 4 km length. Approximately 500 m high bedrock highlands flank the valley network. The highlands are dissected by up to 80 m-deep and 500 m-broad hanging valleys that currently drain away from the axis of the main valley. We interpret the valleys beneath the city of Bern to be a tunnel valley network which originated from subglacial erosion by melt water. The highland valleys served as proglacial meltwater paths and are hanging with respect to the trunk system, indicating that these incipient highland systems as well as the main gorge beneath Bern formed by glacial melt water under pressure. (authors)

Ozone Laminae and Their Entrainment Into a Valley Boundary Layer, as Observed From a Mountaintop Monitoring Station, Ozonesondes, and Aircraft Over California's San Joaquin Valley

Science.gov (United States)

Faloona, I. C.; Conley, S. A.; Caputi, D.; Trousdell, J.; Chiao, S.; Eiserloh, A. J., Jr.; Clark, J.; Iraci, L. T.; Yates, E. L.; Marrero, J. E.; Ryoo, J. M.; McNamara, M. E.

2016-12-01

The San Joaquin Valley of California is wide ( 75 km) and long ( 400 km), and is situated under strong atmospheric subsidence due, in part, to the proximity of the midlatitude anticyclone of the Pacific High. The capping effect of this subsidence is especially prominent during the warm season when ground level ozone is a serious air quality concern across the region. While relatively clean marine boundary layer air is primarily funneled into the valley below the strong subsidence inversion at significant gaps in the upwind Coast Range mountains, airflow aloft also spills over these barriers and mixes into the valley from above. Because this transmountain flow occurs under the influence of synoptic subsidence it tends to present discrete, laminar sheets of differing air composition above the valley boundary layer. Meanwhile, although the boundary layers tend to remain shallow due to the prevailing subsidence, orographic and anabatic venting of valley boundary layer air around the basin whips up a complex admixture of regional air masses into a "buffer layer" just above the boundary layer (zi) and below the lower free troposphere. We present scalar data of widely varying lifetimes including ozone, methane, NOx, and thermodynamic observations from upwind and within the San Joaquin Valley to better explain this layering and its subsequent erosion into the valley boundary layer via entrainment. Data collected at a mountaintop monitoring station on Chews Ridge in the Coast Range, by coastal ozonesondes, and aircraft are analyzed to document the dynamic layering processes around the complex terrain surrounding the valley. Particular emphasis will be made on observational methods whereby distal ozone can be distinguished from the regional ozone to better understand the influence of exogenous sources on air quality in the valley.

Geomorphological hazards in Swat valley, Pakistan

International Nuclear Information System (INIS)

Usman, A.

1999-01-01

This study attempts to describe, interpret and analyze, in depth, the varied geomorphological hazards and their impacts prevailing in the swat valley locate in the northern hilly and mountainous regions of Pakistan. The hills and mountains re zones of high geomorphological activity with rapid rates of weathering, active tectonic activities, abundant precipitation, rapid runoff and heavy sediment transport. Due to the varied topography, lithology, steep slope, erodible soil, heavy winter snowfall and intensive rainfall in the spring and summer seasons, several kinds of geomorphological hazards, such as geomorphic gravitational hazards, Fluvial hazards, Glacial hazards, Geo tectonic hazards, are occurring frequently in swat valley. Amongst them, geomorphic gravitational hazards, such as rock fall rock slide, debris slide mud flow avalanches, are major hazards in mountains and hills while fluvial hazards and sedimentation are mainly confined to the alluvial plain and lowlands of the valley. The Getechtonic hazards, on the other hand, have wide spread distribution in the valley the magnitude and occurrence of each king of hazard is thus, varied according to intensity of process and physical geographic environment. This paper discusses the type distribution and damage due to the various geomorphological hazards and their reduction treatments. The study would to be of particular importance and interest to both natural and social scientists, as well as planner, environmentalists and decision-makers for successful developmental interventions in the region. (author)

A new Proposal to Mexico Valley Zonification

Science.gov (United States)

Flores-Estrella, H. C.; Yussim, S.; Lomnitz, C.

2004-12-01

The effects of the Michoacan earthquake (19th September, 1985, Mw 8.1) in Mexico City caused a significant change in the political, social and scientific history, as it was considered the worst seismic disaster ever lived in Mexico. Since then, numerous efforts have been made to understand and determine the parameters that caused the special features registered. One of these efforts had began on 1960 with the work by Marsal and Masari, who published the Mexico Valley seismological and geotechnical zonification (1969), based on gravimetric and shallow borehole data. In this work, we present a revision of the studies that proposed the zonification, a description of the valley geology, and basing on it we propose a new zonification for Mexico Valley.

Hybrid spin and valley quantum computing with singlet-triplet qubits.

Science.gov (United States)

Rohling, Niklas; Russ, Maximilian; Burkard, Guido

2014-10-24

The valley degree of freedom in the electronic band structure of silicon, graphene, and other materials is often considered to be an obstacle for quantum computing (QC) based on electron spins in quantum dots. Here we show that control over the valley state opens new possibilities for quantum information processing. Combining qubits encoded in the singlet-triplet subspace of spin and valley states allows for universal QC using a universal two-qubit gate directly provided by the exchange interaction. We show how spin and valley qubits can be separated in order to allow for single-qubit rotations.

Morphological variation among populations of Hemigrammus coeruleus (Characiformes: Characidae in a Negro River tributary, Brazilian Amazon

Directory of Open Access Journals (Sweden)

Henrique Lazzarotto

2017-03-01

Full Text Available ABSTRACT We explored patterns of phenotypic variation in Hemigrammus coeruleus from the Unini River basin, a blackwater river in the Brazilian Amazon. Geometric morphometrics was used to evaluate variation in body shape among populations from four tributaries (UN2-UN5. We found no evidence for sexual dimorphism in body size and shape. However, morphological differences among populations were detected as the analyses recovered significant groups corresponding to each sub-basin, with some overlap among them. The populations from UN2, UN3 and UN5 had more elongate bodies than fish from UN4. The most morphologically divergent population belonged to UN4, the tributary with the most divergent environmental conditions and the only one with seasonally-muddy waters. The morphological variation found among these populations is likely due to phenotypic plasticity or local adaptation, arising as a product of divergent ecological selection pressures among sub-basins. This work constitutes one of the first to employ a population-level geometric morphometric approach to assess phenotypic variation in Amazonian fishes. This method was able to distinguish subtle differences in body morphology, and its use with additional species can bring novel perspectives on the evaluation of general patterns of phenotypic differentiation in the Amazon.

Responses of fungal root colonization, plant cover and leaf nutrients to long-term exposure to elevated atmospheric CO₂ and warming in a subarctic birch forest understory

DEFF Research Database (Denmark)

Olsrud, Maria; Carlsson, Bengt Å.; Svensson, Brita M.

2010-01-01

Responses of the mycorrhizal fungal community in terrestrial ecosystems to global change factors are not well understood. However, virtually all land plants form symbiotic associations with mycorrhizal fungi, with approximately 20% of the plants' net primary production transported down...... by mycorrhizal and other root-associated fungi to global change factors of all the fungal types studied could have broad implications for plant community structure and biogeochemistry of subarctic ecosystems....

Graphene valley pseudospin filter using an extended line defect

Science.gov (United States)

Gunlycke, Daniel; White, Carter

2011-03-01

Although graphene exhibits excellent electron and thermal transport properties, it does not have an intrinsic band gap, required to use graphene as a replacement material for silicon and other semiconductors in conventional electronics. The band structure of graphene with its two cones near the Fermi level, however, offers opportunities to develop non-traditional applications. One such avenue is to exploit the valley degeneracy in graphene to develop valleytronics. A central component in valleytronics is the valley filter, just as the spin filter is central in spintronics. Herein, we present a two-dimensional valley filter based on scattering of electrons and holes off a recently observed extended line defect [Nat. Nanotech.5, 326 (2010)] within graphene. The transmission probability depends strongly on the valley pseudospin and the angle of incidence of the incident quasiparticles. Quasiparticles arriving at the line defect at a high angle of incidence lead to a valley polarization of the transmitted beam that is near 100 percent. This work was supported by ONR, directly and through NRL.

Hydrological responses to channelization and the formation of valley plugs and shoals

Science.gov (United States)

Pierce, Aaron R.; King, Sammy L.

2017-01-01

Rehabilitation of floodplain systems focuses on restoring interactions between the fluvial system and floodplain, however, there is a paucity of information on the effects of valley plugs and shoals on floodplain hydrological processes. We investigated hydrologic regimes in floodplains at three valley plug sites, two shoal sites, and three unchannelized sites. Valley plug sites had altered surface and sub-surface hydrology relative to unchannelized sites, while only sub-surface hydrology was affected at shoal sites. Some of the changes were unexpected, such as reduced flood duration and flood depth in floodplains associated with valley plugs. Our results emphasize the variability associated with hydrologic processes around valley plugs and our rudimentary understanding of the effects associated with these geomorphic features. Water table levels were lower at valley plug sites compared to unchannelized sites, however, valley plug sites had a greater proportion of days when water table inundation was above mean root collar depth than both shoal and unchannelized sites as a result of lower root collar depths and higher deposition rates. This study has provided evidence that valley plugs can affect both surface and sub-surface hydrology in different ways than previously thought and illustrates the variability in hydrological responses to valley plug formation.

Detailed study of selenium and other constituents in water, bottom sediment, soil, alfalfa, and biota associated with irrigation drainage in the Uncompahgre Project area and in the Grand Valley, west-central Colorado, 1991-93

Science.gov (United States)

Butler, D.L.; Wright, W.G.; Stewart, K.C.; Osmundson, B.C.; Krueger, R.P.; Crabtree, D.W.

1996-01-01

transport to streams and irrigation drains that are tributary to the Gunnison, Uncompahgre, and Colorado Rivers. Selenium concentrations in about 64\\x11percent of water samples collected from the lower Gunnison River and about 50 percent of samples from the Colorado River near the Colorado-Utah State line exceeded the U.S.\\x11Environmental Protection Agency criterion of 5\\x11micrograms per liter for protection of aquatic life. Almost all selenium concentrations in samples collected during the nonirrigation season from Mancos Shale areas exceeded the aquatic-life criterion. The maximum selenium concentrations in surface-water samples were 600\\x11micrograms per liter in the Uncompahgre Project area and 380\\x11micrograms per liter in the Grand Valley. Irrigation drainage from the Uncompahgre Project and the Grand Valley might account for as much as 75 percent of the selenium load in the Colorado River near the Colorado-Utah State line. The primary source areas of selenium were the eastern side of the Uncompahgre Project and the western one-half of the Grand Valley, where there is extensive irrigation on soils derived from Mancos Shale. The largest mean selenium loads from tributary drainages were 14.0 pounds per day from Loutsenhizer Arroyo in the Uncompahgre Project and 12.8 pounds per day from Reed Wash in the Grand Valley. Positive correlations between selenium loads and dissolved-solids loads could indicate that salinity-control projects designed to decrease dissolved-solids loads also could decrease selenium loads from the irrigated areas. Selenium concentrations in irrigation drainage in the Grand Valley were much higher than concentrations predicted by simple evaporative concentration of irrigation source water. Selenium probably is removed from pond water by chemical and biological processes and incorporated into bottom sediment. The maximum selenium concentration in bottom sediment was 47 micrograms per gram from a pond on the eastern side of the

Fluoroscopy-guided endovenous sclerotherapy using a microcatheter prior to endovenous laser ablation: Comparison between liquid and foam sclerotherapy for varicose tributaries

Energy Technology Data Exchange (ETDEWEB)

Park, Sang Woo; Yun, Ik Jin; Hwang, Jae Joon; Lee, Song Am; Kim, Jun Seok; Chee, Hyun Keun; Chang, Il Soo [Konkuk University Hospital, Konkuk University School of Medicine, Seoul (Korea, Republic of)

2014-08-15

To compare the efficacy and adverse effects of endovenous foam sclerotherapy (EFS) and liquid sclerotherapy (ELS) using a microcatheter for the treatment of varicose tributaries. From December 2007 to January 2009, patients with venous reflux in the saphenous vein were enrolled. The foam or liquid sclerosant was injected through a microcatheter just before endovenous laser ablation (EVLA). Patients were evaluated for the technical success, clinical success, and procedure-related complications during the procedure and follow-up visits. A total of 94 limbs were included: 48 limbs (great saphenous vein [GSV], 35; small saphenous vein [SSV], 13) were managed using EFS and EVLA (foam group; FG), and 46 limbs (GSV, 37; SSV, 9) were treated by ELS and EVLA (liquid group; LG). Varicose tributaries demonstrated complete sclerosis in 92.7% with FG and in 71.8% with LG (p = 0.014). Bruising (78.7% in FG vs. 73.2% in LG, p > 0.05), pain or tenderness (75.6% in FG vs. 51.2% in LG, p = 0.0237) were noted. Hyperpigmentation (51.2% in FG vs. 46.2% in LG, p > 0.05) was found. Endovenous foam sclerotherapy using a microcatheter is more effective than ELS for eliminating remnant varicose tributaries prior to EVLA. However, EFS is more commonly associated with local complications such as pain or tenderness than ELS. Furthermore, both techniques seem to prolong the duration of hyperpigmentation along with higher costs.

IDENTIFICATION AND ASSESSMENT OF DOMOIC ACID PRODUCTION IN OCEANIC PSEUDO-NITZSCHIA (BACILLARIOPHYCEAE) FROM IRON-LIMITED WATERS IN THE NORTHEAST SUBARCTIC PACIFIC(1).

Science.gov (United States)

Marchetti, Adrian; Lundholm, Nina; Kotaki, Yuichi; Hubbard, Katherine; Harrison, Paul J; Virginia Armbrust, E

2008-06-01

We identified and investigated the potential toxicity of oceanic Pseudo-nitzschia species from Ocean Station Papa (OSP), located in a high-nitrate, low-chlorophyll (HNLC) region of the northeast (NE) subarctic Pacific Ocean. Despite their relatively low abundances in the indigenous phytoplankton assemblage, Pseudo-nitzschia species richness is high. The morphometric characteristics of five oceanic Pseudo-nitzschia isolates from at least four species are described using SEM and TEM. The species identified are Pseudo-nitzschia dolorosa Lundholm et Moestrup, P. granii Hasle, P. heimii Manguin, and P. cf. turgidula (Hust.) Hasle. Additional support for the taxonomic classifications based on frustule morphology is provided through the sequencing of the internal transcribed spacer 1 (ITS1) rDNA. Pseudo-nitzschia species identification was also assessed by the construction of ITS1 clone libraries and using automated ribosomal intergenic spacer analysis (ARISA) for environmental samples collected during the Subarctic Ecosystem Response to Iron Enrichment Study (SERIES), conducted in close proximity to OSP in July of 2002. Based on ITS1 sequences, the presence of P. granii, P. heimii, P. cf. turgidula, and at least five other putative, unidentified Pseudo-nitzschia ITS1 variants was confirmed within iron-enriched phytoplankton assemblages at OSP. None of the oceanic isolates produced detectable levels of particulate domoic acid (DA) when in prolonged stationary phase due to silicic acid starvation. The lack of detectable concentrations of DA suggests that either these strains produce very little or no toxin, or that the physiological conditions required to promote particulate DA production were not met and thus differ from their coastal, toxigenic congeners. © 2008 Phycological Society of America.

CO2 emissions from a temperate drowned river valley estuary adjacent to an emerging megacity (Sydney Harbour)

Science.gov (United States)

Tanner, E. L.; Mulhearn, P. J.; Eyre, B. D.

2017-06-01

The Sydney Harbour Estuary is a large drowned river valley adjacent to Sydney, a large urban metropolis on track to become a megacity; estimated to reach a population of 10 million by 2100. Monthly underway surveys of surface water pCO2 were undertaken along the main channel and tributaries, from January to December 2013. pCO2 showed substantial spatio-temporal variability in the narrow high residence time upper and mid sections of the estuary, with values reaching a maximum of 5650 μatm in the upper reaches and as low as 173 μatm in the mid estuary section, dominated by respiration and photosynthesis respectively. The large lower estuary displayed less variability in pCO2 with values ranging from 343 to 544 μatm controlled mainly by tidal pumping and temperature. Air-water CO2 emissions reached a maximum of 181 mmol C m-2 d-1 during spring in the eutrophic upper estuary. After a summer high rainfall event nutrient-stimulated biological pumping promoted a large uptake of CO2 transitioning the Sydney Harbour Estuary into a CO2 sink with a maximum uptake of rate of -10.6 mmol C m-2 d-1 in the mid-section of the estuary. Annually the Sydney Harbour Estuary was heterotrophic and a weak source of CO2 with an air-water emission rate of 1.2-5 mmol C m-2 d-1 (0.4-1.8 mol C m-2 y-1) resulting in a total carbon emission of around 930 tonnes per annum. CO2 emissions (weighted m3 s-1 of discharge per km2 of estuary surface area) from Sydney Harbour were an order of magnitude lower than other temperate large tectonic deltas, lagoons and engineered systems of China, India, Taiwan and Europe but were similar to other natural drowned river valley systems in the USA. Discharge per unit area appears to be a good predictor of CO2 emissions from estuaries of a similar climate and geomorphic class.

The California Valley grassland

Science.gov (United States)

Keeley, J.E.; Schoenherr, Allan A.

1990-01-01

Grasslands are distributed throughout California from Oregon to Baja California Norte and from the coast to the desert (Brown 1982) (Figure 1). This review will focus on the dominant formation in cismontane California, a community referred to as Valley Grassland (Munz 1959). Today, Valley Grassland is dominated by non-native annual grasses in genera such as Avena (wild oat), Bromus (brome grass), and Hordeum (barley), and is often referred to as the California annual grassland. On localized sites, native perennial bunchgrasses such as Stipa pultra (purple needle grass) may dominate and such sites are interpreted to be remnants of the pristine valley grassland. In northwestern California a floristically distinct formation of the Valley Grassland, known as Coast Prairie (Munz 1959) or Northern Coastal Grassland (Holland and Keil 1989) is recognized. The dominant grasses include many native perennial bunchgrasses in genera such as Agrostis, Calamagrostis, Danthonia, Deschampsia, Festuca, Koeleria and Poa (Heady et al. 1977). Non-native annuals do not dominate, but on some sites non-native perennials like Anthoxanthum odoratum may colonize the native grassland (Foin and Hektner 1986). Elevationally, California's grasslands extend from sea level to at leas 1500 m. The upper boundary is vague because montane grassland formations are commonly referred to as meadows; a community which Munz (1959) does not recognize. Holland and Keil (1989) describe the montane meadow as an azonal community; that is, a community restricted not so much to a particular climatic zone but rather controlled by substrate characteristics. They consider poor soil-drainage an over-riding factor in the development of montane meadows and, in contrast to grasslands, meadows often remain green through the summer drought. Floristically, meadows are composed of graminoids; Cyperaceae, Juncaceae, and rhizomatous grasses such as Agropyron (wheat grass). Some bunchgrasses, such as Muhlenbergia rigens, are

Radio-iodine in thyroid glands of swans, farm animals and humans, also in algae and river water from the Thames Valley, England

Energy Technology Data Exchange (ETDEWEB)

Howe, J.R.; Lloyd, M.K.

1986-01-01

A highly sensitive counting system has been used to measure radio-iodine in environmental samples from the Thames Valley. Iodine-125 and occasionally iodine-131 have been found in the thyroid glands of most of the swans that have died on the River Thames, the River Wey and the Grand Union Canal, and in algae and water samples from the Thames and many of its tributaries. The presence of this activity is ascribed to the waste discarded into the drainage system by hospitals and research laboratories, reaching the rivers via the effluent from sewage treatment works. The Thames is used as a source of drinking water, particularly in London and its western approaches. Weed and water samples collected from river water abstraction points, reservoirs, tap water supplies, and animal water troughs fed from this supply all contained low levels of iodine-125. The drinking water route can account for the iodine-125 found in the thyroids of farm animals from west Surrey and in a few people living in London. The amounts found constitute a trivial radiation dose to man and animals as they are far below the acceptable limit of exposure for man.

Groundwater quality in the Antelope Valley, California

Science.gov (United States)

Dawson, Barbara J. Milby; Belitz, Kenneth

2012-01-01

Groundwater provides more than 40 percent of California’s drinking water. To protect this vital resource, the State of California created the Groundwater Ambient Monitoring and Assessment (GAMA) Program. The Priority Basin Project of the GAMA Program provides a comprehensive assessment of the State’s groundwater quality and increases public access to groundwater-quality information. Antelope Valley is one of the study areas being evaluated. The Antelope study area is approximately 1,600 square miles (4,144 square kilometers) and includes the Antelope Valley groundwater basin (California Department of Water Resources, 2003). Antelope Valley has an arid climate and is part of the Mojave Desert. Average annual rainfall is about 6 inches (15 centimeters). The study area has internal drainage, with runoff from the surrounding mountains draining towards dry lakebeds in the lower parts of the valley. Land use in the study area is approximately 68 percent (%) natural (mostly shrubland and grassland), 24% agricultural, and 8% urban. The primary crops are pasture and hay. The largest urban areas are the cities of Palmdale and Lancaster (2010 populations of 152,000 and 156,000, respectively). Groundwater in this basin is used for public and domestic water supply and for irrigation. The main water-bearing units are gravel, sand, silt, and clay derived from surrounding mountains. The primary aquifers in Antelope Valley are defined as those parts of the aquifers corresponding to the perforated intervals of wells listed in the California Department of Public Health database. Public-supply wells in Antelope Valley are completed to depths between 360 and 700 feet (110 to 213 meters), consist of solid casing from the land surface to a depth of 180 to 350 feet (55 to 107 meters), and are screened or perforated below the solid casing. Recharge to the groundwater system is primarily runoff from the surrounding mountains, and by direct infiltration of irrigation and sewer and septic

The Health Valley: Global Entrepreneurial Dynamics.

Science.gov (United States)

Dubuis, Benoit

2014-12-01

In the space of a decade, the Lake Geneva region has become the Health Valley, a world-class laboratory for discovering and developing healthcare of the future. Through visionary individuals and thanks to exceptional infrastructure this region has become one of the most dynamic in the field of innovation, including leading scientific research and exceptional actors for the commercialization of academic innovation to industrial applications that will improve the lives of patients and their families. Here follows the chronicle of a spectacular expansion into the Health Valley.

Solar energy innovation and Silicon Valley

Science.gov (United States)

Kammen, Daniel M.

2015-03-01

The growth of the U. S. and global solar energy industry depends on a strong relationship between science and engineering innovation, manufacturing, and cycles of policy design and advancement. The mixture of the academic and industrial engine of innovation that is Silicon Valley, and the strong suite of environmental policies for which California is a leader work together to both drive the solar energy industry, and keep Silicon Valley competitive as China, Europe and other area of solar energy strength continue to build their clean energy sectors.

Nitrogen Uptake During Fall, Winter and Spring Differs Among Plant Functional Groups in a Subarctic Heath Ecosystem

DEFF Research Database (Denmark)

Larsen, Klaus Steenberg; Michelsen, Anders; Jonasson, Sven

2012-01-01

Nitrogen (N) is a critical resource for plant growth in tundra ecosystems, and species differences in the timing of N uptake may be an important feature regulating community composition and ecosystem productivity. We added 15N-labelled glycine to a subarctic heath tundra dominated by dwarf shrubs...... to 37 ± 7% by April indicating significant microbial N turnover prior to spring thaw. Only the evergreen dwarf shrubs showed active 15N acquisition before early May indicating that they had the highest potential of all functional groups for acquiring nutrients that became available in early spring....... The faster-growing deciduous shrubs did not resume 15N acquisition until after early May indicating that they relied more on nitrogen made available later during the spring/early summer. The graminoids and mosses had no significant increases in 15N tracer recovery or tissue 15N tracer concentrations after...

The impact of enhanced ultraviolet-B radiation on litter quality and decomposition processes in Vaccinium leaves from the Subarctic

International Nuclear Information System (INIS)

Gehrke, C.; Johanson, U.; Callaghan, T.V.; Chadwick, D.; Robinson, C.H.

1995-01-01

The aim of this study was to investigate how UV-B radiation will affect 1) the quality of plant litter grown under different UV-B levels in the Subarctic and 2) decomposition under different UV-B levels. The deciduous dwarf shrubs Vaccinium uliginosum and V. myrtillus grew under ambient and enhanced UV-B (corresponding to 15% ozone depletion) in a natural heath ecosystem in the Subarctic. After two growing seasons senesced leaves were collected and decomposed in a 2 × 2 factorial experiment under both laboratory conditions for 62 d (V. uliginosum: no UV-B and 10 kJ m -2 d -1 UV- B BE ) and under field conditions for twelve months (V. myrtillus: ambient and enhanced UV-B corresponding 15% ozone depletion). Additionally, colonization and growth of decomposing fungi were studied on leaves decomposed without and with UV-B in the laboratory. The enhanced UV-B during growth changed the litter quality (decrease in α-cellulose, increase in tannins). Subsequently the microbial respiration was decreased. This and the decreased cellulose/lignin ratio may have led to the lower relative mass loss due to treatments as detected both after 62 d decomposition in the laboratory and after twelve months decomposition in the field. The UV-B during decomposition decreased the proportion of lignin in the plant residues, which is possibly due to photodegradation by UV-B. Total microbial respiration decreased, indicating the decomposers' sensitivity to UV-B. In general, the litter decomposing under UV-B was less colonized by fungal decomposers. Mucor hiemalis and Truncatella truncata were significantly more abundant in the control, indicating sensitivity to UV-B radiation, while Penicillium brevicompactum was equally abundant in the UV-B and control. There is strong indication of a change in decomposer fungal community structure due to UV-B. Just one of the three fungal species common on the control litter was dominant on leaves decomposed under UV-B. (author)

The impact of enhanced ultraviolet-B radiation on litter quality and decomposition processes in Vaccinium leaves from the Subarctic

Energy Technology Data Exchange (ETDEWEB)

Gehrke, C.; Johanson, U. [Lund Univ. (Sweden); Callaghan, T. V.; Chadwick, D.; Robinson, C. H.

1995-03-15

The aim of this study was to investigate how UV-B radiation will affect 1) the quality of plant litter grown under different UV-B levels in the Subarctic and 2) decomposition under different UV-B levels. The deciduous dwarf shrubs Vaccinium uliginosum and V. myrtillus grew under ambient and enhanced UV-B (corresponding to 15% ozone depletion) in a natural heath ecosystem in the Subarctic. After two growing seasons senesced leaves were collected and decomposed in a 2 × 2 factorial experiment under both laboratory conditions for 62 d (V. uliginosum: no UV-B and 10 kJ m{sup -2} d{sup -1} UV- B{sub BE}) and under field conditions for twelve months (V. myrtillus: ambient and enhanced UV-B corresponding 15% ozone depletion). Additionally, colonization and growth of decomposing fungi were studied on leaves decomposed without and with UV-B in the laboratory. The enhanced UV-B during growth changed the litter quality (decrease in α-cellulose, increase in tannins). Subsequently the microbial respiration was decreased. This and the decreased cellulose/lignin ratio may have led to the lower relative mass loss due to treatments as detected both after 62 d decomposition in the laboratory and after twelve months decomposition in the field. The UV-B during decomposition decreased the proportion of lignin in the plant residues, which is possibly due to photodegradation by UV-B. Total microbial respiration decreased, indicating the decomposers' sensitivity to UV-B. In general, the litter decomposing under UV-B was less colonized by fungal decomposers. Mucor hiemalis and Truncatella truncata were significantly more abundant in the control, indicating sensitivity to UV-B radiation, while Penicillium brevicompactum was equally abundant in the UV-B and control. There is strong indication of a change in decomposer fungal community structure due to UV-B. Just one of the three fungal species common on the control litter was dominant on leaves decomposed under UV-B. (author)

The impact of enhanced ultraviolet-B radiation on litter quality and decomposition processes in Vaccinium leaves from the Subarctic

Energy Technology Data Exchange (ETDEWEB)

Gehrke, C [Lund Univ., Dept. of Plant Ecology, Lund (Sweden); Johanson, U [Lund Univ., Dept. of Plant Physiology, Lund (Sweden); Callaghan, T V; Chadwick, D; Robinson, C H [Merlewood Research Station, Inst. of Terrestrial Ecology, Cumbira (United Kingdom)

1995-05-01

The aim of this study was to investigate how UV-B radiation will affect (1) the quality of plant litter grown under differente UV-B levels in the Subarctic and (2) decomposition under different UV-B levels. The deciduous dwarf shrubs Vaccinium uliginosum and V. myrtillus grew under ambient and enchanced UV-B (corresponding to 15% ozone depletion) in a natural health ecosystem in the Subarctic. After two growing seasons senesced leaves were collected and decomposed in a 2 x 2 factorial experiment under both laboratory conditions for 62 d (V. uliginosum: no UV-B and 10 kJ m{sup -2} d{sup -1} UV-B{sub BE}) and under field conditions for twelve months (V. myrtillus: ambient and enhanced UV-B corresponding 15% ozone depletion). Additionally, colonization and growth of decomposing fungi were studied on leaves decomposed without and with UV-B in the laboratory. The enhanced UV-B during growth changed the litter quality (decrease in {alpha}-cellulose, increase in tannins). Subsequently the microbial respiration was decreased. This and the decreased cellulose/lignin ratio may have led to the lower relative mass loss due to treatments as detected both after 62 d decomposition in the laboratory and after twelve months decompositon in the field. The UV-B during decomposition decreased the proportion of lignin in the plant residues, which is possibly due to photodegradation by UV-B. Total microbial respiration decreased, indicating the decomposers` sensitivity to UV-B. In general, the litter decomposing under UV-B was less colonized by fungal decomposers. Mucor hiemalis and Truncatella truncata were significantly more abundant in the control, indicating sensitivity to UV-B radiation, while Penicillium brevicompactum was equally abundant in the UV-B and control. There is strong indication of a change in decomposer fungal community structure due to UV-B. Just one of the three fungal species common on the control litter was dominant on leaves decomposed under UV-B. (au) (44 refs.)

Iron availability, nitrate uptake, and exportable new production in the subarctic Pacific. [phytoplankton population growth support and atmospheric CO2 removal

Science.gov (United States)

Banse, Karl

1991-01-01

This paper presents a critique of experimental data and papers by Martin et al. (1989, 1990), who suggested that the phytoplankton growth is iron-limited and that, small additions of iron to large subarctic ocean areas might be a way of removing significant amounts of atmospheric CO2 by increasing phytoplancton growth. Data are presented to show that, in the summer of 1987, the phytoplankton assemblage as a whole was not iron limited, as measured by the bulk removal of nitrate or by the increase of chlorophyll. It is suggested that grazing normally prevents the phytoplankton from reaching concentrations that reduce the iron (and nitrate) to levels that depress division rates drastically.

Biogeochemical studies of wintering waterfowl in the Imperial and Sacramento Valleys

Energy Technology Data Exchange (ETDEWEB)

Koranda, J.J.; Stuart, M.; Thompson, S.; Conrado, C.

1979-10-01

Trace and major elemental composition were determined in the organs of wintering waterfowl in the Imperial and Sacramento Valleys of California, and in soils, sediments, and agricultural fertilizer that constitute the various sources of elements in the waterfowl. These data provide a biogeochemical baseline for waterfowl populations wintering in an area being developed for geothermal power. This baseline in the Imperial Valley is affected by soil and sediment composition, agricultural effluents in irrigation and stream water, and spent shot deposited by hunters in waterfowl habitats. The waterfowl acquire a set of trace elements from these sources and concentrations increase in their organs over the wintering period. Nickel, arsenic, selenium, bromine, and lead are the primary elements acquired from soil sources, agricultural effluents, and spent shot in the Imperial Valley. The assessment of effects from geothermal effluents on waterfowl populations in complex because there are large influxes of materials into the Imperial Valley ecosystem that contain trace elements, i.e., irrigation water, phosphatic fertilizers, pesticides, and lead shot. Multiple sources exist for many elements prominent in the expected geothermal effluents. The relationships between the two California valleys, the Imperial and Sacramento, are apparent in the trace element concentrations in the organs of waterfowl obtained in those two valleys. Arsenic is absent in the waterfowl organs obtained in the Sacramento Valley and relatively common in the Imperial Valley waterfowl. The effect of any release of geothermal effluent in the Imperial Valley waterfowl habitats will be difficult to describe because of the complexity of the biogeochemical baseline and the multiple sources of trace and major elements in the ecosystem.

Diverse Mesorhizobium bacteria nodulate native Astragalus and Oxytropis in arctic and subarctic areas in Eurasia.

Science.gov (United States)

Ampomah, Osei Yaw; Mousavi, Seyed Abdollah; Lindström, Kristina; Huss-Danell, Kerstin

2017-01-01

Rhizobia nodulating native Astragalus and Oxytropis spp. in Northern Europe are not well-studied. In this study, we isolated bacteria from nodules of four Astragalus spp. and two Oxytropis spp. from the arctic and subarctic regions of Sweden and Russia. The phylogenetic analyses were performed by using sequences of three housekeeping genes (16S rRNA, rpoB and recA) and two accessory genes (nodC and nifH). The results of our multilocus sequence analysis (MLSA) of the three housekeeping genes tree showed that all the 13 isolates belonged to the genus Mesorhizobium and were positioned in six clades. Our concatenated housekeeping gene tree also suggested that the isolates nodulating Astragalus inopinatus, Astragalus frigidus, Astragalus alpinus ssp. alpinus and Oxytropis revoluta might be designated as four new Mesorhizobium species. The 13 isolates were grouped in three clades in the nodC and nifH trees. 15 N analysis suggested that the legumes in association with these isolates were actively fixing nitrogen. Copyright © 2016 Elsevier GmbH. All rights reserved.

Short-term variability in bacterial abundance, cell properties, and incorporation of leucine and thymidine in subarctic sea ice

DEFF Research Database (Denmark)

Kaartokallio, H.; Sogaard, D. H.; Norman, L.

2013-01-01

Sea ice is a biome of immense size and provides a range of habitats for diverse microbial communities, many of which are adapted to living at low temperatures and high salinities in brines. We measured simultaneous incorporation of thymidine (TdR) and leucine (Leu), bacterial cell abundance...... and cell population properties (by flow cytometry) in subarctic sea ice in SW Greenland. Short-term temporal variability was moderate, and steep environmental gradients, typical for sea ice, were the main drivers of the variability in bacterial cell properties and activity. Low nucleic acid (LNA) bacteria...... and marine biofilm systems. Leu: TdR ratios were high (up to >300) in lowermost ice layers, and when compared to published respiration measurements, these results suggest non-specific Leu incorporation. There was evidence of polyhydroxyalkanoate (PHA)-containing bacteria in the sea ice, shown by brightly...

Goldstone-Apple Valley Radio Telescope System Theory of Operation

Science.gov (United States)

Stephan, George R.

1997-01-01

The purpose of this learning module is to enable learners to describe how the Goldstone-Apple Valley Radio Telescope (GAVRT) system functions in support of Apple Valley Science and Technology Center's (AVSTC) client schools' radio astronomy activities.

Summary of the engineering assessment of inactive uranium mill tailings: Monument Valley site, Monument Valley, Arizona

International Nuclear Information System (INIS)

1981-10-01

Ford, Bacon and Davis Utah Inc. has reevaluated the Monument Valley site in order to revise the March 1977 engineering assessment of the problems resulting from the existence of radioactive uranium mill tailings at Monument Valley, Arizona. This engineering assessment has included the preparation of topographic maps, the performance of core drillings and radiometric measurements sufficient to determine areas and volumes of tailings and radiation exposures of individuals and nearby populations, the investigations of site hydrology and meteorology, and the evaluation and costing of alternative corrective actions. Radon gas released from the 1.1 million tons of tailings at the Monument Valley site constitutes the most significant environmental impact, although windblown tailings and external gamma radiation also are factors. The four alternative actions presented in this engineering assessment range from millsite decontamination with the addition of 3 m of stabilization cover material to removal of the tailings to remote disposal sites and decontamination of the tailings site. Cost estimates for the four options range from about $6,600,000 for stabilization in-place, to about $15,900,000 for disposal at a distance of about 15 mi. Three principal alternatives for reprocessing the Monument Valley tailings were examined: heap leaching, treatment at an existing mill; and reprocessing at a new conventional mill constructed for tailings reprocessing. The cost of the uranium recovered would be more than $500/lb of U 3 O 8 by heap leach or conventional plant processes. The spot market price for uranium was $25/lb early in 1981. Therefore, reprocessing the tailings for uranium recovery is economically unattractive

Gravel sediment routing from widespread, low-intensity landscape disturbance, Current River basin, Missouri

Science.gov (United States)

Jacobson, Robert B.; Gran, K.B.

1999-01-01

During the last 160 years, land-use changes in the Ozarks have had the potential to cause widespread, low-intensity delivery of excess amounts of gravel-sized sediment to stream channels. Previous studies have indicated that this excess gravel bedload is moving in wave-like forms through Ozarks drainage basins. The longitudinal, areal distribution of gravel bars along 160 km of the Current River, Missouri, was evaluated to determine the relative effects of valley-scale controls, tributary basin characteristics, and lagged sediment transport in creating areas of gravel accumulations. The longitudinal distribution of gravel-bar area shows a broad scale wave-like form with increases in gravel-bar area weakly associated with tributary junctions. Secondary peaks of gravel area with 1·8–4·1 km spacing (disturbance reaches) are superimposed on the broad form. Variations in valley width explain some, but not all, of the short-spacing variation in gravel-bar area. Among variables describing tributary drainage basin morphometry, present-day land use and geologic characteristics, only drainage area and road density relate even weakly to gravel-bar areal inventories. A simple, channel network-based sediment routing model shows that many of the features of the observed longitudinal gravel distribution can be replicated by uniform transport of sediment from widespread disturbances through a channel network. These results indicate that lagged sediment transport may have a dominant effect on the synoptic spatial distribution of gravel in Ozarks streams; present-day land uses are only weakly associated with present-day gravel inventories; and valley-scale characteristics have secondary controls on gravel accumulations in disturbance reaches.

Water isotope composition as a tracer for study of mixing processes in rivers. Part II. Determination of mixing degrees in the tributary-main river systems

International Nuclear Information System (INIS)

Owczarczyk, A.; Wierzchnicki, R.; Zimnicki, R.; Ptaszek, S.; Palige, J.; Dobrowolski, A.

2006-01-01

Two river-tributary systems have been chosen for the investigation of mixing processes: the Narew River-the Bug River-Zegrzynski Reservoir and the Bugo-Narew River-the Vistula River. In both river systems, several profiles for the water sampling have been selected down to the tributary confluent line. Each sample position has been precisely determined by means of GPS. Then, the δDi have been measured in IRMS (isotope ratio mass spectroscopy). The δD distributions in selected profiles have been presented for both investigated river systems. Presented results will be applied for the verification of the mathematical model for transport and mixing in river systems

Channel-morphology data for the Tongue River and selected tributaries, southeastern Montana, 2001-02

Science.gov (United States)

Chase, Katherine J.

2004-01-01

Coal-bed methane exploration and production have begun within the Tongue River watershed in southeastern Montana. The development of coal-bed methane requires production of large volumes of ground water, some of which may be discharged to streams, potentially increasing stream discharge and sediment load. Changes in stream discharge or sediment load may result in changes to channel morphology through changes in erosion and vegetation. These changes might be subtle and difficult to detect without baseline data that indicate stream-channel conditions before extensive coal-bed methane development began. In order to provide this baseline channel-morphology data, the U.S. Geological Survey, in cooperation with the Bureau of Land Management, collected channel-morphology data in 2001-02 to document baseline conditions for several reaches along the Tongue River and selected tributaries. This report presents channel-morphology data for five sites on the mainstem Tongue River and four sites on its tributaries. Bankfull, water-surface, and thalweg elevations, channel sections, and streambed-particle sizes were measured along reaches near streamflow-gaging stations. At each site, the channel was classified using methods described by Rosgen. For six sites, bankfull discharge was determined from the stage- discharge relation at the gage for the stage corresponding to the bankfull elevation. For three sites, the step-backwater computer model HEC-RAS was used to estimate bankfull discharge. Recurrence intervals for the bankfull discharge also were estimated for eight of the nine sites. Channel-morphology data for each site are presented in maps, tables, graphs, and photographs.

Topographic evolution of Yosemite Valley from Low Temperature Thermochronology

Science.gov (United States)

Tripathy-Lang, A.; Shuster, D. L.; Cuffey, K. M.; Fox, M.

2014-12-01

In this contribution, we interrogate the timing of km-scale topography development in the region around Yosemite Valley, California. Our goal is to determine when this spectacular glacial valley was carved, and how this might help address controversy surrounding the topographic evolution of the Sierra Nevada. At the scale of the range, two rival hypotheses are each supported by different datasets. Low-temperature thermochronology supports the idea that the range has been high-standing since the Cretaceous, whereas geomorphic evidence suggests that much of the elevation of the Sierra Nevada was attained during the Pliocene. Recent work by McPhillips and Brandon (2012) suggests instead that both ideas are valid, with the range losing much elevation during the Cenozoic, but regaining it during Miocene surface uplift.At the local scale, the classic study of Matthes (1930) determined that most of Yosemite Valley was excavated by the Sherwin-age glaciation that ended ~1 Ma. The consensus view is in agreement, although some argue that nearby comparable valleys comparable were carved long ago (e.g., House et al., 1998). If the Quaternary and younger glaciations were responsible for the bulk of the valley's >1 km depth, we might expect apatite (U-Th)/He ages at the valley floor to be histories at these locations, these data constrain patterns of valley topography development through time. We also supplement these data with zircon 4He/3He thermochronometry, which is a newly developed method that provides information on continuous cooling paths through ~120-220 °C. We will present both the apatite and zircon 4He/3He data and, in conjunction with thermo-kinematic modeling, discuss the ability and limitations of these data to test models of Sierra Nevada topography development through time. Matthes (1930) USGS Professional Paper House et al. (1998) Nature McPhillips and Brandon (2012) American Journal of Science

Optimal decentralized valley-filling charging strategy for electric vehicles

International Nuclear Information System (INIS)

Zhang, Kangkang; Xu, Liangfei; Ouyang, Minggao; Wang, Hewu; Lu, Languang; Li, Jianqiu; Li, Zhe

2014-01-01

Highlights: • An implementable charging strategy is developed for electric vehicles connected to a grid. • A two-dimensional pricing scheme is proposed to coordinate charging behaviors. • The strategy effectively works in decentralized way but achieves the systematic valley filling. • The strategy allows device-level charging autonomy, and does not require a bidirectional communication/control network. • The strategy can self-correct when confronted with adverse factors. - Abstract: Uncoordinated charging load of electric vehicles (EVs) increases the peak load of the power grid, thereby increasing the cost of electricity generation. The valley-filling charging scenario offers a cheaper alternative. This study proposes a novel decentralized valley-filling charging strategy, in which a day-ahead pricing scheme is designed by solving a minimum-cost optimization problem. The pricing scheme can be broadcasted to EV owners, and the individual charging behaviors can be indirectly coordinated. EV owners respond to the pricing scheme by autonomously optimizing their individual charge patterns. This device-level response induces a valley-filling effect in the grid at the system level. The proposed strategy offers three advantages: coordination (by the valley-filling effect), practicality (no requirement for a bidirectional communication/control network between the grid and EV owners), and autonomy (user control of EV charge patterns). The proposed strategy is validated in simulations of typical scenarios in Beijing, China. According to the results, the strategy (1) effectively achieves the valley-filling charging effect at 28% less generation cost than the uncoordinated charging strategy, (2) is robust to several potential affecters of the valley-filling effect, such as (system-level) inaccurate parameter estimation and (device-level) response capability and willingness (which cause less than 2% deviation in the minimal generation cost), and (3) is compatible with

Geothermal resource assessment of western San Luis Valley, Colorado

Energy Technology Data Exchange (ETDEWEB)

Zacharakis, Ted G.; Pearl, Richard Howard; Ringrose, Charles D.

1983-01-01

The Colorado Geological Survey initiated and carried out a fully integrated assessment program of the geothermal resource potential of the western San Luis Valley during 1979 and 1980. The San Luis Valley is a large intermontane basin located in southcentral Colorado. While thermal springs and wells are found throughout the Valley, the only thermal waters found along the western part of the Valley are found at Shaw Warm Springs which is a relatively unused spring located approximately 6 miles (9.66 km) north of Del Norte, Colorado. The waters at Shaws Warm Spring have a temperature of 86 F (30 C), a discharge of 40 gallons per minute and contain approximately 408 mg/l of total dissolved solids. The assessment program carried out din the western San Luis Valley consisted of: soil mercury geochemical surveys; geothermal gradient drilling; and dipole-dipole electrical resistivity traverses, Schlumberger soundings, Audio-magnetotelluric surveys, telluric surveys, and time-domain electro-magnetic soundings and seismic surveys. Shaw Warm Springs appears to be the only source of thermal waters along the western side of the Valley. From the various investigations conducted the springs appear to be fault controlled and is very limited in extent. Based on best evidence presently available estimates are presented on the size and extent of Shaw Warm Springs thermal system. It is estimated that this could have an areal extent of 0.63 sq. miles (1.62 sq. km) and contain 0.0148 Q's of heat energy.

Valley-controlled propagation of pseudospin states in bulk metacrystal waveguides

Science.gov (United States)

Chen, Xiao-Dong; Deng, Wei-Min; Lu, Jin-Cheng; Dong, Jian-Wen

2018-05-01

Light manipulations such as spin-direction locking propagation, robust transport, quantum teleportation, and reconfigurable electromagnetic pathways have been investigated at the boundaries of photonic systems. Recently by breaking Dirac cones in time-reversal-invariant photonic crystals, valley-pseudospin coupled edge states have been employed to realize selective propagation of light. Here, we realize the controllable propagation of pseudospin states in three-dimensional bulk metacrystal waveguides by valley degree of freedom. Reconfigurable photonic valley Hall effect is achieved for frequency-direction locking propagation in such a way that the propagation path can be tunable precisely by scanning the working frequency. A complete transition diagram is illustrated on the valley-dependent pseudospin states of Dirac-cone-absent photonic bands. A photonic blocker is proposed by cascading two inversion asymmetric metacrystal waveguides in which pseudospin-direction locking propagation exists. In addition, valley-dependent pseudospin bands are also discussed in a realistic metamaterials sample. These results show an alternative way toward molding the pseudospin flow in photonic systems.

Valley-symmetric quasi-1D transport in ballistic graphene

Science.gov (United States)

Lee, Hu-Jong

We present our recent studies on gate-defined valley-symmetric one-dimensional (1D) carrier guiding in ballistic monolayer graphene and valley-symmetry-protected topological 1D transport in ballistic bilayer graphene. Successful carrier guiding was realized in ballistic monolayer graphene even in the absence of a band gap by inducing a high distinction ( more than two orders of magnitude) in the carrier density between the region of a quasi-1D channel and the rest of the top-gated regions. Conductance of a channel shows quantized values in units of 4e2/ h, suggesting that the valley symmetry is preserved. For the latter, the topological 1D conduction was realized between two closely arranged insulating regions with inverted band gaps, induced under a pair of split dual gating with polarities opposite to each other. The maximum conductance along the boundary channel showed 4e2/ h, again with the preserved valley symmetry. The 1D topological carrier guiding demonstrated in this study affords a promising route to robust valleytronic applications and sophisticated valley-associated functionalities based on 2D materials. This work was funded by the National Research Foundation of Korea.

Valley-dependent spin-orbit torques in two-dimensional hexagonal crystals

KAUST Repository

Li, Hang; Wang, Xuhui; Manchon, Aurelien

2016-01-01

We study spin-orbit torques in two-dimensional hexagonal crystals such as graphene, silicene, germanene, and stanene. The torque possesses two components, a fieldlike term due to inverse spin galvanic effect and an antidamping torque originating from Berry curvature in mixed spin-k space. In the presence of staggered potential and exchange field, the valley degeneracy can be lifted and we obtain a valley-dependent Berry curvature, leading to a tunable antidamping torque by controlling the valley degree of freedom. The valley imbalance can be as high as 100% by tuning the bias voltage or magnetization angle. These findings open new venues for the development of current-driven spin-orbit torques by structural design.

Valley-dependent spin-orbit torques in two-dimensional hexagonal crystals

KAUST Repository

Li, Hang

2016-01-11

We study spin-orbit torques in two-dimensional hexagonal crystals such as graphene, silicene, germanene, and stanene. The torque possesses two components, a fieldlike term due to inverse spin galvanic effect and an antidamping torque originating from Berry curvature in mixed spin-k space. In the presence of staggered potential and exchange field, the valley degeneracy can be lifted and we obtain a valley-dependent Berry curvature, leading to a tunable antidamping torque by controlling the valley degree of freedom. The valley imbalance can be as high as 100% by tuning the bias voltage or magnetization angle. These findings open new venues for the development of current-driven spin-orbit torques by structural design.

West Valley Demonstration Project, West Valley, New York: Annual report

International Nuclear Information System (INIS)

1989-01-01

Under the West Valley Demonstration Project Act, Public Law 96-368, liquid high-level radioactive waste stored at the Western New York Nuclear Services Center, West Valley, New York, that resulted from spent nuclear fuel reprocessing operations conducted between 1966 and 1972, is to be solidified in borosilicate glass and transported to a federal repository for geologic disposal. A major milestone was reached in May 1988 when the Project began reducing the volume of the liquid high-level waste. By the end of 1988, approximately 15 percent of the initial inventory had been processed into two waste streams. The decontaminated low-level liquid waste is being solidified in cement. The high-level waste stream is being stored in an underground tank pending its incorporation into borosilicate glass. Four tests of the waste glass melter system were completed. These tests confirmed equipment operability, control system reliability, and provided samples of waste glass for durability testing. In mid-1988, the Department validated an integrated cost and schedule plan for activities required to complete the production of the waste borosilicate glass. Design of the radioactive Vitrification Facility continued

Biodiversity of microcrustaceans (Cladocera, Copepoda in a lowland river ecosystem

Directory of Open Access Journals (Sweden)

Maciej Karpowicz

2016-06-01

Full Text Available This study presents comprehensive research on microcrustacean diversity in different types of aquatic environments in the Upper Narew Valley over five years. A total of 559 samples were analyzed, and 74 species of crustacean zooplankton were identified. Metacyclops planus (Gurney, 1909 is a new species for the fauna of Poland and was found in oxbow lakes and tributary streams. The results of the study suggest that oxbow lakes, with more than 80% of all recorded species, may significantly contribute to the regional biodiversity of floodplain rivers. The highest crustacean community diversity was observed in the semi-lotic oxbow lakes, which emphasizes the role of intermediate disturbance in enhancing biodiversity of water bodies in river valleys. Generally, more “heterogeneous” habitats, such as small oxbow lakes and tributary streams, had higher crustacean species richness. However, a sampling station that was quite “homogeneous”, the Narew River upstream the Siemianówka Reservoir, had high crustacean species richness. The species accumulation curves revealed that approximately 50 - 100 zooplankton samples taken from different environments of river valley are required to establish crustacean species richness. These data could be important for river catchment management and could act as pilot survey data for monitoring plans.

Seasonal climate manipulations have only minor effects on litter decomposition rates and N dynamics but strong effects on litter P dynamics of sub-arctic bog species.

Science.gov (United States)

Aerts, R; Callaghan, T V; Dorrepaal, E; van Logtestijn, R S P; Cornelissen, J H C

2012-11-01

Litter decomposition and nutrient mineralization in high-latitude peatlands are constrained by low temperatures. So far, little is known about the effects of seasonal components of climate change (higher spring and summer temperatures, more snow which leads to higher winter soil temperatures) on these processes. In a 4-year field experiment, we manipulated these seasonal components in a sub-arctic bog and studied the effects on the decomposition and N and P dynamics of leaf litter of Calamagrostis lapponica, Betula nana, and Rubus chamaemorus, incubated both in a common ambient environment and in the treatment plots. Mass loss in the controls increased in the order Calamagrostis Litter chemistry showed within each incubation environment only a few and species-specific responses. Compared to the interspecific differences, they resulted in only moderate climate treatment effects on mass loss and these differed among seasons and species. Neither N nor P mineralization in the litter were affected by the incubation environment. Remarkably, for all species, no net N mineralization had occurred in any of the treatments during 4 years. Species differed in P-release patterns, and summer warming strongly stimulated P release for all species. Thus, moderate changes in summer temperatures and/or winter snow addition have limited effects on litter decomposition rates and N dynamics, but summer warming does stimulate litter P release. As a result, N-limitation of plant growth in this sub-arctic bog may be sustained or even further promoted.

Medicinal plants of Usherai valley, Dir, NWFP, Pakistan

International Nuclear Information System (INIS)

Hazarat, A.; Shah, J.; Ahmad, S.; Nasir, M.; Jan, A.K.; Skindar

2010-01-01

This research is based on the results of an ethno-botanical research conducted in Usherai Valley. The main objective was to enlist the wealth of medicinal plants. In total 50 species, belonging to 32 families of wild herbs, shrubs and trees were found to be used as medicinal plants by the inhabitants in the valley. (author)

AIR POLLUTION FEATURES OF THE VALLEY-BASED TOWNS IN HUNGARY

Directory of Open Access Journals (Sweden)

Z. UTASI

2016-03-01

Full Text Available There are 30 valley-based towns with >10,000 inhabitants in Hungary, filled by 1.023 million people i.e. 10 % of the population. Two criteria are used to define the valley-based town. They are: (i Vertical difference between the lowest point in the town and the highest one around it should be >100 m. At the same time, (ii the same difference on the opposite side should be >50 m. Air pollution data by the National Air Pollution Observation Network are used. Five contaminants were selected and analysed for 2007, 2010 and 2013. Due to a sharp reduction in the network, we could find data for a small part of the valley-based towns. Control towns with equal air-quality observations and similar cumulative number of inhabitants were also selected. The contaminants and the number of the settlements are: NO2 manual (14 valley-based vs. 2x14 control, NO2 automatic (8 vs. 8, SO2 automatic (7 vs. 2x6, PM10 automatic (8 vs. 2x7 and PM10 deposition manual (6 vs. 8. Average values, as well as high concentration episodes (>98%thresholds are equally analysed and evaluated. The main conclusion is that there are so big differences between the years both in absolute values and relative sequence of valley-based and control groups that the analysed there years is not enough to make any final conclusion. For step-over frequencies, however valley-based towns have some advantage, possibly due to the valley-hill wind system.

Debris Flow Occurrence and Sediment Persistence, Upper Colorado River Valley, CO.

Science.gov (United States)

Grimsley, K J; Rathburn, S L; Friedman, J M; Mangano, J F

2016-07-01

Debris flow magnitudes and frequencies are compared across the Upper Colorado River valley to assess influences on debris flow occurrence and to evaluate valley geometry effects on sediment persistence. Dendrochronology, field mapping, and aerial photographic analysis are used to evaluate whether a 19th century earthen, water-conveyance ditch has altered the regime of debris flow occurrence in the Colorado River headwaters. Identifying any shifts in disturbance processes or changes in magnitudes and frequencies of occurrence is fundamental to establishing the historical range of variability (HRV) at the site. We found no substantial difference in frequency of debris flows cataloged at eleven sites of deposition between the east (8) and west (11) sides of the Colorado River valley over the last century, but four of the five largest debris flows originated on the west side of the valley in association with the earthen ditch, while the fifth is on a steep hillslope of hydrothermally altered rock on the east side. These results suggest that the ditch has altered the regime of debris flow activity in the Colorado River headwaters as compared to HRV by increasing the frequency of debris flows large enough to reach the Colorado River valley. Valley confinement is a dominant control on response to debris flows, influencing volumes of aggradation and persistence of debris flow deposits. Large, frequent debris flows, exceeding HRV, create persistent effects due to valley geometry and geomorphic setting conducive to sediment storage that are easily delineated by valley confinement ratios which are useful to land managers.

Assessing dam development, land use conversion, and climate change pressures on tributary river flows and water quality of the Mekong's Tonle Sap basin.

Science.gov (United States)

Cochrane, T. A.; Arias, M. E.; Oeurng, C.; Arnaiz, M.; Piman, T.

2016-12-01

The Tonle Sap Lake is Southeast Asia's most productive freshwater fishery, but the productivity of this valuable ecosystem is under threat from extensive development in the lower Mekong. With dams potentially blocking all major tributaries along the lower Mekong River, the role of local Tonle Sap basin tributaries for maintaining environmental flows, sediment loads, and fish recruitment is becoming increasingly critical. Development within the Tonle Sap basin, however, is not stagnant. Developers are proposing extensive dam development in key Tonle Sap tributaries (see Figure). Some dams will provide hydroelectricity and others will provide opportunities for large-scale irrigation resulting in agro-industrial expansion. There is thus an immediate need to assess the current situation and understand future effects of dam development and land use conversion under climate change on local riverine ecosystems. A combination of remote sensing, field visits, and hydro-meteorological data analyses enabled an assessment of water infrastructure and agricultural development in the basin. The application of SWAT for modelling flows and water quality combined with HEC-RESSIM for reservoir operations enabled for a holistic modelling approach. Initial results show that dams and land use change dominate flow and water quality responses, when compared to climate change. Large ongoing dam and irrigation development in the Pursat and Battambang subbasins will critically alter the natural river flows to the Tonle Sap Lake. Some of the observed dams did not have provisions for sediment flushing, clearing of flooded areas, fish passages, or other environmental protection measures. Poor planning and operation of this infrastructure could have dire consequences on the fragile riverine ecosystem of Tonle Sap tributaries, resulting in fish migration barriers, losses in aquatic habitats, and ecological degradation. The seemingly chaotic development in the Tonle Sap basin induces a great level

Groundwater quality in the Owens Valley, California

Science.gov (United States)

Dawson, Barbara J. Milby; Belitz, Kenneth

2012-01-01

Groundwater provides more than 40 percent of California’s drinking water. To protect this vital resource, the State of California created the Groundwater Ambient Monitoring and Assessment (GAMA) Program. The Priority Basin Project of the GAMA Program provides a comprehensive assessment of the State’s groundwater quality and increases public access to groundwater-quality information. Owens Valley is one of the study areas being evaluated. The Owens study area is approximately 1,030 square miles (2,668 square kilometers) and includes the Owens Valley groundwater basin (California Department of Water Resources, 2003). Owens Valley has a semiarid to arid climate, with average annual rainfall of about 6 inches (15 centimeters). The study area has internal drainage, with runoff primarily from the Sierra Nevada draining east to the Owens River, which flows south to Owens Lake dry lakebed at the southern end of the valley. Beginning in the early 1900s, the City of Los Angeles began diverting the flow of the Owens River to the Los Angeles Aqueduct, resulting in the evaporation of Owens Lake and the formation of the current Owens Lake dry lakebed. Land use in the study area is approximately 94 percent (%) natural, 5% agricultural, and 1% urban. The primary natural land cover is shrubland. The largest urban area is the city of Bishop (2010 population of 4,000). Groundwater in this basin is used for public and domestic water supply and for irrigation. The main water-bearing units are gravel, sand, silt, and clay derived from surrounding mountains. Recharge to the groundwater system is primarily runoff from the Sierra Nevada, and by direct infiltration of irrigation. The primary sources of discharge are pumping wells, evapotranspiration, and underflow to the Owens Lake dry lakebed. The primary aquifers in Owens Valley are defined as those parts of the aquifers corresponding to the perforated intervals of wells listed in the California Department of Public Health database

Ground water in Fountain and Jimmy Camp Valleys, El Paso County, Colorado with a section on Computations of drawdowns caused by the pumping of wells in Fountain Valley

Science.gov (United States)

Jenkins, Edward D.; Glover, Robert E.

1964-01-01

The part of Fountain Valley considered in this report extends from Colorado Springs to the Pueblo County line. It is 23 miles long and has an area of 26 square miles. The part of Jimmy Camp Valley discussed is 11 miles long and has an area of 9 square miles. The topography is characterized by level flood plains and alluvial terraces that parallel the valley and by rather steep hills along the valley sides. The climate is semiarid, average annual precipitation being about 13 inches. Farming and stock raising are the principal occupations in the valleys; however, some of the agricultural land near Colorado Springs is being used for housing developments. The Pierre Shale and alluvium underlie most of the area, and mesa gravel caps the shale hills adjacent to Fountain Valley. The alluvium yields water to domestic, stock, irrigation, and public-supply wells and is capable of yielding large quantities of water for intermittent periods. Several springs issue along the sides of the valley at the contact of the mesa gravel and the underlying Pierre Shale. The water table ranges in depth from less than 10 feet along the bottom lands to about 80 feet along the sides of the valleys; the saturated thickness ranges from less than a foot to about 50 feet. The ground-water reservoir in Fountain Valley is recharged by precipitation that falls within the area, by percolation from Fountain Creek, which originates in the Pikes Peak, Monument Valley, and Rampart Range areas, and by seepage from irrigation water. This reservoir contains about 70,000 acre-feet of ground water in storage. The ground-water reservoir in Jimmy Camp Valley is recharged from precipitation that falls within the area, by percolation from Jimmy Camp Creek during periods of streamflow, and by seepage from irrigation water. The Jimmy Camp ground-water reservoir contains about 25,000 acre-feet of water in storage. Ground water is discharged from the area by movement to the south, by evaporation and transpiration in

Replacement cost valuation of Northern Pintail (Anas acuta) subsistence harvest in Arctic and sub-Arctic North America

Science.gov (United States)

Goldstein, Joshua H.; Thogmartin, Wayne E.; Bagstad, Kenneth J.; Dubovsky, James A.; Mattsson, Brady J.; Semmens, Darius J.; López-Hoffman, Laura; Diffendorfer, James E.

2014-01-01

Migratory species provide economically beneficial ecosystem services to people throughout their range, yet often, information is lacking about the magnitude and spatial distribution of these benefits at regional scales. We conducted a case study for Northern Pintails (hereafter pintail) in which we quantified regional and sub-regional economic values of subsistence harvest to indigenous communities in Arctic and sub-Arctic North America. As a first step, we used the replacement cost method to quantify the cost of replacing pintail subsistence harvest with the most similar commercially available protein (chicken). For an estimated annual subsistence harvest of ˜15,000 pintail, our mean estimate of the total replacement cost was ˜$63,000 yr−1 ($2010 USD), with sub-regional values ranging from \\$263 yr−1 to \\$21,930 yr−1. Our results provide an order-of-magnitude, conservative estimate of one component of the regional ecosystem-service values of pintails, providing perspective on how spatially explicit values can inform migratory species conservation.

Valley-chiral quantum Hall state in graphene superlattice structure

Science.gov (United States)

Tian, H. Y.; Tao, W. W.; Wang, J.; Cui, Y. H.; Xu, N.; Huang, B. B.; Luo, G. X.; Hao, Y. H.

2016-05-01

We theoretically investigate the quantum Hall effect in a graphene superlattice (GS) system, in which the two valleys of graphene are coupled together. In the presence of a perpendicular magnetic field, an ordinary quantum Hall effect is found with the sequence σxy=ν e^2/h(ν=0,+/-1,+/-2,\\cdots) . At the zeroth Hall platform, a valley-chiral Hall state stemming from the single K or K' valley is found and it is localized only on one sample boundary contributing to the longitudinal conductance but not to the Hall conductivity. Our findings may shed light on the graphene-based valleytronics applications.

Concentrations and loads of nutrients in the tributaries of the Lake Okeechobee watershed, south-central Florida, water years 2004-2008

Science.gov (United States)

Byrne, Michael J.; Wood, Molly S.

2011-01-01

Lake Okeechobee in south-central Florida is the second largest freshwater lake in the contiguous United States. Excessive phosphorus loading, harmful high and low water levels, and rapid expansion of non-native vegetation have threatened the health of the lake in recent decades. A study was conducted to monitor discharge and nutrient concentrations from selected tributaries into Lake Okeechobee and to evaluate nutrient loads. The data analysis was performed at 16 monitoring stations from December 2003 to September 2008. Annual and seasonal discharge measured at monitoring stations is affected by rainfall. Hurricanes affected three wet years (2004, 2005, and the latter part of 2008) and resulted in substantially greater discharge than the drought years of 2006, 2007, and the early part of 2008. Rainfall supplies about 50 percent of the water to Lake Okeechobee, discharge from the Kissimmee River supplies about 25 percent, and discharge from tributaries and groundwater seepage along the lake perimeter collectively provide the remaining 25 percent. Annually, tributary discharge from basins located on the west side of the Kissimmee River is about 5 to 6 times greater than that from basins located on the east side. For the purposes of this study, the basins on the east side of the Kissimmee River are called "priority basins" because of elevated phosphorus concentrations, while those on the west side are called "nonpriority" basins. Total annual discharge in the non-priority basins ranged from 245,000 acre-feet (acre-ft) in 2007 to 1,322,000 acre-ft in 2005, while annual discharge from the priority basins ranged from 41,000 acre-ft in 2007 to 219,000 acre-ft in 2005. Mean total phosphorus concentrations ranged from 0.10 to 0.54 milligrams per liter (mg/L) at the 16 tributaries during 2004–2008. Mean concentrations were significantly higher at priority basin sites than at non-priority basin sites, particularly at Arbuckle Creek and C 41A Canal. Concentrations of organic

Commercial production of ethanol in the San Luis Valley, Colorado. Final report

Energy Technology Data Exchange (ETDEWEB)

Hewlett, E.M.; Erickson, M.V.; Ferguson, C.D.; Boswell, B.S.; Walter, K.M.; Hart, M.L.; Sherwood, P.B.

1983-07-01

The commercial feasibility of producing between 76 and 189 million liters (20 to 50 million gallons) of ethanol annually in the San Luis Valley, Colorado using geothermal energy as the primary heat source was assessed. The San Luis Valley is located in south-central Colorado. The valley is a high basin situated approximately 2316 meters (7600 feet) above sea level which contains numerous warm water wells and springs. A known geothermal resource area (IGRA) is located in the east-central area of the valley. The main industry in the valley is agriculture, while the main industry in the surrounding mountains is lumber. Both of these industries can provide feedstocks for the production of ethanol.

Cryostratigraphy and sedimentology of high-Arctic fjord-valleys

OpenAIRE

Gilbert, Graham Lewis

2018-01-01

Fjord-valleys, as sediment-filled palaeofjords, are characteristic of formerly glaciated mountainous coastal areas. High-Arctic fjord-valleys commonly host permafrost, but are poorly accessible and hence have drawn relatively little research. The research presented in this thesis combines the methods of cryostratigraphy, clastic sedimentology, sequence stratigraphy, geomorphology and geochronology to investigate the sedimentary infilling, permafrost formation and late Quaternary landscape dev...

Linking carbon and nitrogen cycling: Environmental transcription of mmoX, pmoA, and nifH by methane oxidizing Proteobacteria in a Sub-Arctic palsa peatland

Science.gov (United States)

Liebner, Susanne; Svenning, Mette M.

2013-04-01

Sub-Arctic terrestrial ecosystems are currently affected by climate change which causes degradation of stored organic carbon and emissions of greenhouse gases from microbial processes. Methane oxidizing bacteria (MOB) mitigate methane emissions and perform an important function in the soil-atmosphere interaction. In this study we investigated presence and environmental transcription of functional genes of MOB along the degradation of permafrost in a Sub-Arctic palsa peatland using molecular approaches. The acidic and oligotrophic peatland hosts a small number of active MOB among a seemingly specialized community. The methanotrophic community displayed a broad functional potential by transcribing genes for key enzymes involved in both carbon and nitrogen metabolisms including particulate and soluble methane monoogygenase (pMMO and sMMO) as well as nitrogenase. Transcription of mmoX that encodes for a subunit of the sMMO suggests an ecological importance of sMMO with a broad substrate range in this peatland. In situ transcripts of mmoX were tracked mainly to Methylocella related Beijerinckiaceae, and to relatives of Methylomonas while Methylocystis constituting the dominant group which utilizes pMMO. These results address interesting questions concerning in-situ substrate preferences of MOB, and the general importance of species that lack a pMMO for mitigating methane emissions. The importance of MOB for the nitrogen budget in this low pH, nitrogen limited habitat was identified by nifH transcripts of native methanotrophs. Hence, methane oxidizing Proteobacteria show an extended functional repertoire and importance for the biogeochemical cycling in this dynamic ecosystem of degrading permafrost.

Elemental composition and optical properties reveal changes in dissolved organic matter along a permafrost thaw chronosequence in a subarctic peatland

Energy Technology Data Exchange (ETDEWEB)

Hodgkins, Suzanne; Tfaily, Malak M.; Podgorski, David C.; McCalley, Carmody; Saleska, Scott; Crill, Patrick M.; Rich, Virginia; Chanton, Jeffrey; Cooper, William T.

2016-08-01

The fate of carbon stored in permafrost-zone peatlands represents a significant uncertainty in global climate modeling. Given that the breakdown of dissolved organic matter (DOM) is often a major pathway for decomposition in peatlands, knowledge of DOM reactivity under different permafrost regimes is critical for determining future climate feedbacks. To explore the effects of permafrost thaw and resultant plant succession on DOM reactivity, we used a combination of Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS), UV/Vis absorbance, and excitation-emission matrix spectroscopy (EEMS) to examine the DOM elemental composition and optical properties of 27 pore water samples gathered from various sites along a permafrost thaw sequence in Stordalen Mire, a thawing subarctic peatland in northern Sweden. The presence of dense Sphagnum moss, a feature that is dominant in the intermediate thaw stages, appeared to be the main driver of variation in DOM elemental composition and optical properties at Stordalen. Specifically, DOM from sites with Sphagnum had greater aromaticity, higher average molecular weights, and greater O/C, consistent with a higher abundance of phenolic compounds that likely inhibit decomposition. These compounds are released by Sphagnum and may accumulate due to inhibition of phenol oxidase activity by the acidic pH at these sites. In contrast, sites without Sphagnum, specifically fully-thawed rich fens, had more saturated, more reduced compounds, which were high in N and S. Optical properties at rich fens were indicated the presence of microbially-derived DOM, consistent with the higher decomposition rates previously measured at these sites. These results indicate that Sphagnum acts as an inhibitor of rapid decomposition and CH4 release in thawing subarctic peatlands, consistent with lower rates of CO2 and CH4 production previously observed at these sites. However, this inhibitory effect may disappear if Sphagnumdominated bogs

Elemental composition and optical properties reveal changes in dissolved organic matter along a permafrost thaw chronosequence in a subarctic peatland

Science.gov (United States)

Hodgkins, Suzanne B.; Tfaily, Malak M.; Podgorski, David C.; McCalley, Carmody K.; Saleska, Scott R.; Crill, Patrick M.; Rich, Virginia I.; Chanton, Jeffrey P.; Cooper, William T.

2016-08-01

The fate of carbon stored in permafrost-zone peatlands represents a significant uncertainty in global climate modeling. Given that the breakdown of dissolved organic matter (DOM) is often a major pathway for decomposition in peatlands, knowledge of DOM reactivity under different permafrost regimes is critical for determining future climate feedbacks. To explore the effects of permafrost thaw and resultant plant succession on DOM reactivity, we used a combination of Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS), UV/Vis absorbance, and excitation-emission matrix spectroscopy (EEMS) to examine the DOM elemental composition and optical properties of 27 pore water samples gathered from various sites along a permafrost thaw sequence in Stordalen Mire, a thawing subarctic peatland in northern Sweden. The presence of dense Sphagnum moss, a feature that is dominant in the intermediate thaw stages, appeared to be the main driver of variation in DOM elemental composition and optical properties at Stordalen. Specifically, DOM from sites with Sphagnum had greater aromaticity, higher average molecular weights, and greater O/C, consistent with a higher abundance of phenolic compounds that likely inhibit decomposition. These compounds are released by Sphagnum and may accumulate due to inhibition of phenol oxidase activity by the acidic pH at these sites. In contrast, sites without Sphagnum, specifically fully-thawed rich fens, had more saturated, more reduced compounds, which were high in N and S. Optical properties at rich fens indicated the presence of microbially-derived DOM, consistent with the higher decomposition rates previously measured at these sites. These results indicate that Sphagnum acts as an inhibitor of rapid decomposition and CH4 release in thawing subarctic peatlands, consistent with lower rates of CO2 and CH4 production previously observed at these sites. However, this inhibitory effect may disappear if Sphagnum-dominated bogs

Large tunable valley splitting in edge-free graphene quantum dots on boron nitride

Science.gov (United States)

Freitag, Nils M.; Reisch, Tobias; Chizhova, Larisa A.; Nemes-Incze, Péter; Holl, Christian; Woods, Colin R.; Gorbachev, Roman V.; Cao, Yang; Geim, Andre K.; Novoselov, Kostya S.; Burgdörfer, Joachim; Libisch, Florian; Morgenstern, Markus

2018-05-01

Coherent manipulation of the binary degrees of freedom is at the heart of modern quantum technologies. Graphene offers two binary degrees: the electron spin and the valley. Efficient spin control has been demonstrated in many solid-state systems, whereas exploitation of the valley has only recently been started, albeit without control at the single-electron level. Here, we show that van der Waals stacking of graphene onto hexagonal boron nitride offers a natural platform for valley control. We use a graphene quantum dot induced by the tip of a scanning tunnelling microscope and demonstrate valley splitting that is tunable from -5 to +10 meV (including valley inversion) by sub-10-nm displacements of the quantum dot position. This boosts the range of controlled valley splitting by about one order of magnitude. The tunable inversion of spin and valley states should enable coherent superposition of these degrees of freedom as a first step towards graphene-based qubits.

Completely independent electrical control of spin and valley in a silicene field effect transistor

International Nuclear Information System (INIS)

Zhai, Xuechao; Jin, Guojun

2016-01-01

One-atom-thick silicene is a silicon-based hexagonal-lattice material with buckled structure, where an electron fuses multiple degrees of freedom including spin, sublattice pseudospin and valley. We here demonstrate that a valley-selective spin filter (VSSF) that supports single-valley and single-spin transport can be realized in a silicene field effect transistor constructed of an npn junction, where an antiferromagnetic exchange field and a perpendicular electric field are applied in the p -doped region. The nontrivial VSSF property benefits from an electrically controllable state of spin-polarized single-valley Dirac cone. By reversing the electric field direction, the device can operate as a spin-reversed but valley-unreversed filter due to the dependence of band gap on spin and valley. Further, we find that all the possible spin-valley configurations of VSSF can be achieved just by tuning the electric field. Our findings pave the way to the realization of completely independent electrical control of spin and valley in silicene circuits. (paper)

Commercial production of ethanol in the San Luis Valley, Colorado. Final Report

Energy Technology Data Exchange (ETDEWEB)

Hewlett, E.M.; Erickson, M.V.; Ferguson, C.D.; Sherwood, P.B.; Boswell, B.S.; Walter, K.M.; Hart, M.L.

1983-07-01

The purpose of this study is to assess the commercial feasibility of producing between 76 and 189 million liters (20 and 50 million gallons) of ethanol annually in the San Luis Valley, Colorado using geothermal energy as the primary heat source. The San Luis Valley is located in south-central Colorado. The valley is a high basin situated approximately 2316 meters (7600 feet) above sea level which contains numerous warm water wells and springs. A known geothermal resource area (KGRA) is located in the east-central area of the valley. The main industry in the valley is agriculture, while the main industry in the surrounding mountains is lumber. Both of these industries can provide feedstock for the production of ethanol.

Ultrafast generation of pseudo-magnetic field for valley excitons in WSe2 monolayers

KAUST Repository

Kim, J.

2014-12-04

The valley pseudospin is a degree of freedom that emerges in atomically thin two-dimensional transition metal dichalcogenides (MX2). The capability to manipulate it, in analogy to the control of spin in spintronics, can open up exciting opportunities. Here, we demonstrate that an ultrafast and ultrahigh valley pseudo-magnetic field can be generated by using circularly polarized femtosecond pulses to selectively control the valley degree of freedom in monolayer MX2. Using ultrafast pump-probe spectroscopy, we observed a pure and valley-selective optical Stark effect in WSe2 monolayers from the nonresonant pump, resulting in an energy splitting of more than 10 milli-electron volts between the K and K′ valley exciton transitions. Our study opens up the possibility to coherently manipulate the valley polarization for quantum information applications.

Ultrafast generation of pseudo-magnetic field for valley excitons in WSe2 monolayers

KAUST Repository

Kim, J.; Hong, X.; Jin, C.; Shi, S.-F.; Chang, C.-Y. S.; Chiu, Ming-Hui; Li, Lain-Jong; Wang, F.

2014-01-01

The valley pseudospin is a degree of freedom that emerges in atomically thin two-dimensional transition metal dichalcogenides (MX2). The capability to manipulate it, in analogy to the control of spin in spintronics, can open up exciting opportunities. Here, we demonstrate that an ultrafast and ultrahigh valley pseudo-magnetic field can be generated by using circularly polarized femtosecond pulses to selectively control the valley degree of freedom in monolayer MX2. Using ultrafast pump-probe spectroscopy, we observed a pure and valley-selective optical Stark effect in WSe2 monolayers from the nonresonant pump, resulting in an energy splitting of more than 10 milli-electron volts between the K and K′ valley exciton transitions. Our study opens up the possibility to coherently manipulate the valley polarization for quantum information applications.

The lakes of the Jordan Rift Valley

International Nuclear Information System (INIS)

Gat, J.R.

2001-01-01

This paper presents a summary of the proceedings of a workshop on the Lakes of the Jordan Rift Valley that was held in conjunction with the CRP on The Use of Isotope Techniques in Lake Dynamics Investigations. The paper presents a review of the geological, hydrogeological and physical limnological setting of the lakes in the Jordan Rift Valley, Lake Hula, Lake Kinneret and the Dead Sea. This is complemented by a description of the isotope hydrology of the system that includes the use of a wide range of isotopes: oxygen-18, deuterium, tritium, carbon-14, carbon-13, chlorine isotopes, boron-11 and helium-3/4. Environmental isotope aspects of the salt balances of the lakes, their palaeolimnology and biogeochemical tracers are also presented. The scope of application of isotopic tracers is very broad and provides a clear insight into many aspects of the physical, chemical and biological limnology of the Rift Valley Lakes. (author)

West Valley Reprocessing Plant. Safety analysis plant, supplement 18

International Nuclear Information System (INIS)

1975-01-01

Supplement 18 contains the following additions to Appendix II--5.0 Geology and Seismology: Section 12 ''Seismic Investigations for Spent Fuel Reprocessing Facility at West Valley, New York,'' October 20, 1975, and Section 13 ''Earthquake Return Period Analysis at West Valley, New York, for Nuclear Fuel Services, Inc.'' November 5, 1975

Wind Regimes in Complex Terrain of the Great Valley of Eastern Tennessee

Energy Technology Data Exchange (ETDEWEB)

Birdwell, Kevin R. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

2011-05-01

This research was designed to provide an understanding of physical wind mechanisms within the complex terrain of the Great Valley of Eastern Tennessee to assess the impacts of regional air flow with regard to synoptic and mesoscale weather changes, wind direction shifts, and air quality. Meteorological data from 2008 2009 were analyzed from 13 meteorological sites along with associated upper level data. Up to 15 ancillary sites were used for reference. Two-step complete linkage and K-means cluster analyses, synoptic weather studies, and ambient meteorological comparisons were performed to generate hourly wind classifications. These wind regimes revealed seasonal variations of underlying physical wind mechanisms (forced channeled, vertically coupled, pressure-driven, and thermally-driven winds). Synoptic and ambient meteorological analysis (mixing depth, pressure gradient, pressure gradient ratio, atmospheric and surface stability) suggested up to 93% accuracy for the clustered results. Probabilistic prediction schemes of wind flow and wind class change were developed through characterization of flow change data and wind class succession. Data analysis revealed that wind flow in the Great Valley was dominated by forced channeled winds (45 67%) and vertically coupled flow (22 38%). Down-valley pressure-driven and thermally-driven winds also played significant roles (0 17% and 2 20%, respectively), usually accompanied by convergent wind patterns (15 20%) and large wind direction shifts, especially in the Central/Upper Great Valley. The behavior of most wind regimes was associated with detectable pressure differences between the Lower and Upper Great Valley. Mixing depth and synoptic pressure gradients were significant contributors to wind pattern behavior. Up to 15 wind classes and 10 sub-classes were identified in the Central Great Valley with 67 joined classes for the Great Valley at-large. Two-thirds of Great Valley at-large flow was defined by 12 classes. Winds

Sampling little fish in big rivers: Larval fish detection probabilities in two Lake Erie tributaries and implications for sampling effort and abundance indices

Science.gov (United States)

Pritt, Jeremy J.; DuFour, Mark R.; Mayer, Christine M.; Roseman, Edward F.; DeBruyne, Robin L.

2014-01-01

Larval fish are frequently sampled in coastal tributaries to determine factors affecting recruitment, evaluate spawning success, and estimate production from spawning habitats. Imperfect detection of larvae is common, because larval fish are small and unevenly distributed in space and time, and coastal tributaries are often large and heterogeneous. We estimated detection probabilities of larval fish from several taxa in the Maumee and Detroit rivers, the two largest tributaries of Lake Erie. We then demonstrated how accounting for imperfect detection influenced (1) the probability of observing taxa as present relative to sampling effort and (2) abundance indices for larval fish of two Detroit River species. We found that detection probabilities ranged from 0.09 to 0.91 but were always less than 1.0, indicating that imperfect detection is common among taxa and between systems. In general, taxa with high fecundities, small larval length at hatching, and no nesting behaviors had the highest detection probabilities. Also, detection probabilities were higher in the Maumee River than in the Detroit River. Accounting for imperfect detection produced up to fourfold increases in abundance indices for Lake Whitefish Coregonus clupeaformis and Gizzard Shad Dorosoma cepedianum. The effect of accounting for imperfect detection in abundance indices was greatest during periods of low abundance for both species. Detection information can be used to determine the appropriate level of sampling effort for larval fishes and may improve management and conservation decisions based on larval fish data.

Size effects in many-valley fluctuations in semiconductors

International Nuclear Information System (INIS)

Sokolov, V.N.; Kochelap, V.A.

1995-08-01

We present the results of theoretical investigations of nonhomogeneous fluctuations in submicron active regions of many-valley semiconductors with equivalent valleys(Ge, Si-type), where the dimension 2d of the region is comparable to or less than the intervalley diffusion relaxation length L iv . It is shown that for arbitrary orientations of the valley axes (the crystal axes) with respect to lateral sample surfaces, the fluctuation spectra depend on the bias voltage applied to the layer in the region of weak nonheating electric fields. The new physical phenomenon is reported: the fluctuation spectra depend on the sample thickness, with 2d iv the suppression of fluctuations arises for fluctuation frequencies ω -1 iv , τ -1 iv is the characteristic intervalley relaxation time. (author). 43 refs, 5 figs

Energy Band Gap Dependence of Valley Polarization of the Hexagonal Lattice

Science.gov (United States)

Ghalamkari, Kazu; Tatsumi, Yuki; Saito, Riichiro

2018-02-01

The origin of valley polarization of the hexagonal lattice is analytically discussed by tight binding method as a function of energy band gap. When the energy gap decreases to zero, the intensity of optical absorption becomes sharp as a function of k near the K (or K') point in the hexagonal Brillouin zone, while the peak intensity at the K (or K') point keeps constant with decreasing the energy gap. When the dipole vector as a function of k can have both real and imaginary parts that are perpendicular to each other in the k space, the valley polarization occurs. When the dipole vector has only real values by selecting a proper phase of wave functions, the valley polarization does not occur. The degree of the valley polarization may show a discrete change that can be relaxed to a continuous change of the degree of valley polarization when we consider the life time of photo-excited carrier.

Asymmetric valley-resolved beam splitting and incident modes in slanted graphene junctions

International Nuclear Information System (INIS)

Hsieh, S. H.; Chu, C. S.

2016-01-01

Electron injection into a graphene sheet through a slanted armchair graphene nanoribbon (AGNR) is investigated. An incident mode, or subband, in the AGNR is valley-unpolarized. Our attention is on the valley-resolved nature of the injected electron beams and its connection to the incident mode. It is known for a normal injection that an incident mode will split symmetrically into two valley-resolved beams of equal intensity. We show, in contrast, that slanted injections result in asymmetric valley-resolved beam splitting. The most asymmetric beam splitting cases, when one of the valley-resolved beams has basically disappeared, are found and the condition derived. This is shown not due to trigonal warping because it holds even in the low incident energy regime, as long as collimation allows. These most asymmetric beam splitting cases occur at energies within an energy interval near and include the subband edge of an incident mode. The physical picture is best illustrated by a projection of the slanted AGNR subband states onto that of the 2D graphene sheet. It follows that the disappearing of a valley-resolved beam coincides with the situation that the group velocities of the projected states in the corresponding valley are in backward directions

The Drentsche Aa valley system

International Nuclear Information System (INIS)

Gans, W. de.

1981-01-01

This thesis is composed of five papers concerned with Late Quaternary geology and geomorphology of the Aa valley system. The correlation and chronostratigraphic position of the layers have been established by radiocarbon dating. (Auth.)

Land Subsidence Caused by Groundwater Exploitation in Quetta Valley, Pakistan

Directory of Open Access Journals (Sweden)

Najeebullah Kakar

2016-12-01

Full Text Available Land subsidence is affecting several metropolitan cities in developing as well as developed countries around the world such as Nagoya (Japan, Shanghai (China, Venice (Italy and San Joaquin valley (United States. This phenomenon is attributed to natural as well as anthropogenic activities that include extensive groundwater withdrawals. Quetta is the largest city of Balochistan province in Pakistan. This valley is mostly dry and ground water is the major source for domestic and agricultural consumption. The unplanned use of ground water resources has led to the deterioration of water quality and quantity in the Quetta valley. Water shortage in the region was further aggravated by the drought during (1998-2004 that hit the area forcing people to migrate from rural to urban areas. Refugees from the war torn neighboring Afghanistan also contributed to rapid increase in population of Quetta valley that has increased from 0.26 million in 1975 to 3.0 million in 2016. The objective of this study was to measure the land subsidence in Quetta valley and identify the effects of groundwater withdrawals on land subsidence. To achieve this goal, data from five Global Positioning System (GPS stations were acquired and processed. Furthermore the groundwater decline data from 41 observation wells during 2010 to 2015 were calculated and compared with the land deformation. The results of this study revealed that the land of Quetta valley is subsiding from 30mm/y on the flanks to 120 mm/y in the central part. 1.5-5.0 m/y of groundwater level drop was recorded in the area where the rate of subsidence is highest. So the extensive groundwater withdrawals in Quetta valley is considered to be the driving force behind land subsidence.

Direct measurement of exciton valley coherence in monolayer WSe2

KAUST Repository

Hao, Kai; Moody, Galan; Wu, Fengcheng; Dass, Chandriker Kavir; Xu, Lixiang; Chen, Chang Hsiao; Sun, Liuyang; Li, Ming-yang; Li, Lain-Jong; MacDonald, Allan H.; Li, Xiaoqin

2016-01-01

In crystals, energy band extrema in momentum space can be identified by a valley index. The internal quantum degree of freedom associated with valley pseudospin indices can act as a useful information carrier, analogous to electronic charge

Valley polarization in magnetically doped single-layer transition-metal dichalcogenides

KAUST Repository

Cheng, Yingchun

2014-04-28

We demonstrate that valley polarization can be induced and controlled in semiconducting single-layer transition-metal dichalcogenides by magnetic doping, which is important for spintronics, valleytronics, and photonics devices. As an example, we investigate Mn-doped MoS2 by first-principles calculations. We study how the valley polarization depends on the strength of the spin orbit coupling and the exchange interaction and discuss how it can be controlled by magnetic doping. Valley polarization by magnetic doping is also expected for other honeycomb materials with strong spin orbit coupling and the absence of inversion symmetry.

Optically initialized robust valley-polarized holes in monolayer WSe2

KAUST Repository

Hsu, Wei-Ting; Chen, Yen-Lun; Chen, Chiang-Hsiao; Liu, Pang-Shiuan; Hou, Tuo-Hung; Li, Lain-Jong; Chang, Wen-Hao

2015-01-01

a unique platform to develop such valleytronic devices, the anticipated long-lived valley pseudospin has not been observed yet. Here we demonstrate that robust valley-polarized holes in monolayer WSe2 can be initialized by optical pumping. Using time

Rapid responses of permafrost and vegetation to experimentally increased snow cover in sub-arctic Sweden

International Nuclear Information System (INIS)

Johansson, Margareta; Bosiö, Julia; Akerman, H Jonas; Jackowicz-Korczynski, Marcin; Christensen, Torben R; Callaghan, Terry V

2013-01-01

Increased snow depth already observed, and that predicted for the future are of critical importance to many geophysical and biological processes as well as human activities. The future characteristics of sub-arctic landscapes where permafrost is particularly vulnerable will depend on complex interactions between snow cover, vegetation and permafrost. An experimental manipulation was, therefore, set up on a lowland peat plateau with permafrost, in northernmost Sweden, to simulate projected future increases in winter precipitation and to study their effects on permafrost and vegetation. After seven years of treatment, statistically significant differences between manipulated and control plots were found in mean winter ground temperatures, which were 1.5 ° C higher in manipulated plots. During the winter, a difference in minimum temperatures of up to 9 ° C higher could be found in individual manipulated plots compared with control plots. Active layer thicknesses increased at the manipulated plots by almost 20% compared with the control plots and a mean surface subsidence of 24 cm was recorded in the manipulated plots compared to 5 cm in the control plots. The graminoid Eriophorum vaginatum has expanded in the manipulated plots and the vegetation remained green longer in the season. (letter)

Channel incision and suspended sediment delivery at Caspar Creek, Mendocino County, California

Science.gov (United States)

Nicholas J. Dewey; Thomas E. Lisle; Leslie M. Reid

2003-01-01

Tributary and headwater valleys in the Caspar Creek watershed,in coastal Mendocino County, California,show signs of incision along much of their lengths.An episode of incision followed initial-entry logging which took place between 1860 and 1906. Another episode of incision cut into skid-trails created for second-entry logging in the 1970's.

Interaction of valleys and circulation patterns (CPs on spatial precipitation patterns in southern Germany

Directory of Open Access Journals (Sweden)

M. Liu

2013-11-01

Full Text Available Topography exerts influence on the spatial precipitation distribution over different scales, known typically at the large scale as the orographic effect, and at the small scale as the wind-drift rainfall (WDR effect. At the intermediate scale (1~10 km, which is characterized by secondary mountain valleys, topography also demonstrates some effect on the precipitation pattern. This paper investigates such intermediate-scale topographic effects on precipitation patterns, focusing on narrow-steep valleys in the complex terrain of southern Germany, based on the daily observations over a 48 yr period (1960~2007 from a high-density rain-gauge network covering two sub-areas, Baden-Wuerttemberg (BW and Bavaria (BY. Precipitation data at the valley and non-valley stations are compared under consideration of the daily general circulation patterns (CPs classified by a fuzzy rule-based algorithm. Scatter plots of precipitation against elevation demonstrate a different behavior of valley stations comparing to non-valley stations. A detailed study of the precipitation time series for selected station triplets, each consisting of a valley station, a mountain station and an open station have been investigated by statistical analysis with the Kolmogorov–Smirnov (KS test supplemented by the One-way analysis of variance (One-way ANOVA and a graphical comparison of the mean precipitation amounts. The results show an interaction of valley orientation and the direction of the CPs at the intermediate scale, i.e. when the valley is shielded from the CP which carries the precipitation, the precipitation amount within the valley is comparable to that on the mountain crest, and both larger than the precipitation at the open station. When the valley is open to the CP, the precipitation within the valley is similar to the open station but much less than that on the mountain. Such phenomenon where the precipitation is "blind" to the valleys at the intermediate scale

Food web topology and parasites in the pelagic zone of a subarctic lake

Science.gov (United States)

Amundsen, Per-Arne; Lafferty, K.D.; Knudsen, R.; Primicerio, R.; Klemetsen, A.; Kuris, A.M.

2009-01-01

Parasites permeate trophic webs with their often complex life cycles, but few studies have included parasitism in food web analyses. Here we provide a highly resolved food web from the pelagic zone of a subarctic lake and explore how the incorporation of parasites alters the topology of the web. 2. Parasites used hosts at all trophic levels and increased both food-chain lengths and the total number of trophic levels. Their inclusion in the network analyses more than doubled the number of links and resulted in an increase in important food-web characteristics such as linkage density and connectance. 3. More than half of the parasite taxa were trophically transmitted, exploiting hosts at multiple trophic levels and thus increasing the degree of omnivory in the trophic web. 4. For trophically transmitted parasites, the number of parasite-host links exhibited a positive correlation with the linkage density of the host species, whereas no such relationship was seen for nontrophically transmitted parasites. Our findings suggest that the linkage density of free-living species affects their exposure to trophically transmitted parasites, which may be more likely to adopt highly connected species as hosts during the evolution of complex life cycles. 5. The study supports a prominent role for parasites in ecological networks and demonstrates that their incorporation may substantially alter considerations of food-web structure and functioning. ?? 2009 British Ecological Society.

Valley plugs, land use, and phytogeomorphic response: Chapter 14

Science.gov (United States)

Pierce, Aaron R.; King, Sammy L.; Shroder, John F.

2013-01-01

Anthropogenic alteration of fluvial systems can disrupt functional processes that provide valuable ecosystem services. Channelization alters fluvial parameters and the connectivity of river channels to their floodplains which is critical for productivity, nutrient cycling, flood control, and biodiversity. The effects of channelization can be exacerbated by local geology and land-use activities, resulting in dramatic geomorphic readjustments including the formation of valley plugs. Considerable variation in the response of abiotic processes, including surface hydrology, subsurface hydrology, and sedimentation dynamics, to channelization and the formation of valley plugs. Altered abiotic processes associated with these geomorphic features and readjustments influence biotic processes including species composition, abundance, and successional processes. Considerable interest exists for restoring altered fluvial systems and their floodplains because of their social and ecological importance. Understanding abiotic and biotic responses of channelization and valley-plug formation within the context of the watershed is essential to successful restoration. This chapter focuses on the primary causes of valley-plug formation, resulting fluvial-geomorphic responses, vegetation responses, and restoration and research needs for these systems.

Magnetoelectric control of valley and spin in a silicene nanoribbon modulated by the magnetic superlattices

Energy Technology Data Exchange (ETDEWEB)

An, Xing-Tao, E-mail: anxt@hku.hk

2015-03-20

The control of valley and spin degrees of freedom and the transport properties of electrons in a zigzag silicene nanoribbon modulated by the magnetic superlattices are investigated theoretically. Due to the valley–spin locking effect in silicene, the valley degree of freedom can be controlled by magnetic means. The valley or/and spin selection induced by the exchange field result in the perfect spin–valley filter and tunneling magnetoresistance effect in the double ferromagnetic barriers on the surface of the silicene nanoribbon. It is more interesting that there are valley-resolved minigaps and minibands in the zigzag silicene nanoribbon modulated by the magnetic superlattices which give rise to the periodically modulated spin (or/and valley) polarization and tunneling magnetoresistance. The results obtained may have certain practical significance in applications for future valleytronic and spintronic devices. - Highlights: • The valley can be controlled by a magnetic field in silicene. • The valley-resolved miniband transport is studied in the silicene superlattices. • There are the perfect spin–valley filter and tunneling magnetoresistance effect.

75 FR 48359 - Blackstone River Valley National Heritage Corridor Commission: Notice of Meeting

Science.gov (United States)

2010-08-10

... DEPARTMENT OF THE INTERIOR Office of the Secretary Blackstone River Valley National Heritage..., United States Code, that a meeting of the John H. Chafee Blackstone River Valley National Heritage..., Blackstone River Valley National Heritage Corridor Commission, One Depot Square, Woonsocket, RI 02895, Tel...

Modeling a two-layer flow system at the subarctic, subalpine tree line during snowmelt

Science.gov (United States)

Leenders, Erica E.; Woo, Ming-Ko

2002-10-01

In the subarctic it is common to encounter a two-layer flow system consisting of a porous organic cover overlying frozen or unfrozen mineral soils with much lower hydraulic conductivities. The "simple lumped reservoir parametric," or "semidistributed land-use-based runoff processes" (SLURP), model was adapted to simulate runoff generated by such a flow system from an upland shrub land to an open woodland downslope. A subalpine site in Wolf Creek, Yukon, Canada, was subdivided into two aggregated simulation areas (ASA), each being a unit characterized by a set of parameters. The model computes the vertical water balance and flow generation from several storages, and then routes the water out of the ASA. When applied to the 1999 snowmelt season, the model simulated the very low lateral flow and a large increase in storage in the mineral soil, as was observed in the field. The model was used to assess the sensitivity of the two-layer flow system under a range of temperature, snow cover, and frost conditions. Results show that within the range of possible climatic conditions, the hydrologic system is unlikely to yield significant runoff across the subalpine tree line, but if ground ice is abundant in the soil pores, percolation will be limited and fast flow from the surface layer is enhanced.

The Biogeochemical Response to Inter-decadal Atmospheric Forcing Across Watershed Scales in Canada's Subarctic

Science.gov (United States)

Spence, C.

2016-12-01

Rapid landscape changes in the circumpolar north have been documented, including degradation of permafrost and alteration of vegetation communities. These are widely expected to have profound impacts on the freshwater fluxes of solutes, carbon and nitrogen across the Arctic domain. However, there have been few attempts to document trends across the diversity of landscapes in the circumpolar north, mostly due to a dearth of long term data. Some of the fastest rates of warming over the last thirty years have occurred in Canada's Northwest Territories, so this region should already exhibit changes in aquatic chemistry. Observations of chemical loads in streams draining the ice-poor discontinuous permafrost subarctic Canadian Shield region were analyzed with the goal of determining how basins across scales have responded to changes in atmospheric forcing. Smaller streams, with much closer linkages to terrestrial processes, experienced a synchrony among hydrological and biogeochemical processes that enhanced chemical flux above that in their larger counterparts. This demonstrates that there are differences in resiliency and resistance across scales to climate change. These results highlight the importance of biogeochemical process understanding to properly explain and predict how chemical loading scales from headwaters to river mouths. This is important information if society is to properly adapt policies for effluent discharge, nearshore marine management, among others.

Habitat quality of a subarctic nursery ground for 0-group plaice ( Pleuronectes platessa L.)

Science.gov (United States)

Freitas, Vânia; Campos, Joana; Skreslet, Stig; van der Veer, Henk W.

2010-07-01

Habitat quality of a subarctic nursery ground in northern Norway for 0-group plaice Pleuronectes platessa was investigated by following settlement, mortality and growth during 2005 and 2006. Newly settled individuals were first observed in the end of May to early June and settlement lasted until mid-July. Densities peaked in early July and were comparable to those reported in temperate nursery grounds. Mortality estimates after settlement differed between 0.062 d -1 in 2005 and 0.025 d -1 in 2006. Potential predators appeared to be rather similar as those reported in other areas: the brown shrimp Crangoncrangon, the shore crab Carcinus maenas and demersal fish species (gadoids). Population mean growth indicated linear growth until August leveling-off afterwards. 0-group plaice reached a lower mean size (5-6 cm) at the end of the growing season than in temperate areas probably due to later settlement timing in combination with lower summer-autumn water temperatures. The comparison of observed growth rates with predictions of maximum growth models indicated a similar pattern as observed in temperate nursery grounds: Growth appeared to be maximal except for the period after summer. Whether or not this was related to changes in food quality throughout the season, to interspecies competition or to emigration remains to be elucidated.

Rock-fall potential in the Yosemite Valley, California

Science.gov (United States)

Wieczorek, G.F.; Morrissey, M.M.; Iovine, Giulio; Godt, Jonathan

1999-01-01

We used two methods of estimating rock-fall potential in the Yosemite Valley, California based on (1) physical evidence of previous rock-fall travel, in which the potential extends to the base of the talus, and (2) theoretical potential energy considerations, in which the potential can extend beyond the base of the talus, herein referred to as the rock-fall shadow. Rock falls in the valley commonly range in size from individual boulders of less than 1 m3 to moderate-sized falls with volumes of about 100,000 m3. Larger rock falls exceeding 100,000 m3, referred to as rock avalanches, are considered to be much less likely to occur based on the relatively few prehistoric rock-fall avalanche deposits in the Yosemite Valley. Because the valley has steep walls and is relatively narrow, there are no areas that are absolutely safe from large rock avalanches. The map shows areas of rock-fall potential, but does not predict when or how frequently a rock fall will occur. Consequently, neither the hazard in terms of probability of a rock fall at any specific location, nor the risk to people or facilities to such events can be assessed from this map.

Radiation processing of temperate fruits of Kashmir valley

International Nuclear Information System (INIS)

Hussain, Peerzada R.; Meena, Raghuveer S.; Dar, Mohd A.; Wani, Ali M.

2011-01-01

Kashmir valley is famous for its temperate horticulture. Main temperate fruits grown commercially in the valley include apple, pear, peach, plum, cherry, strawberry and apricot. These fruits being perishable and susceptible to microbial spoilage, have a short shelf-life. The short shelf-life in an impediment in their transportation and marketing and results in huge losses. Study was carried out at NRL, Srinagar to investigate the effect of gamma irradiation on the keeping quality of most of these fruits. The effect of gamma irradiation alone and in combination with other techniques like controlled low temperature storage, edible polysaccharide coating and calcium chloride treatment was studied in detail. The results revealed that there is a great potential for the use of radiation in extending the storage life of most of the temperate fruits produced in the valley of Kashmir. (author)

Regolith transport in the Dry Valleys of Antarctica

Science.gov (United States)

Putkonen, J.; Rosales, M.; Turpen, N.; Morgan, D.; Balco, G.; Donaldson, M.

2007-01-01

The stability of ground surface and preservation of landforms that record past events and environments is of great importance as the geologic and climatic history is evaluated in the Dry Valleys of Antarctica. Currently little is known about the regolith transport that tends to eradicate and confound this record and regolith transport is itself an environmental indicator. Based on analyses of repeat photographs, soil traps, and pebble transport distances, it was found that there is a large spatial variation in topographic diffusivities at least in the annual basis and that counter intuitively the highest topographic diffusivities are found in the alpine valleys that are located farther inland from the coast where the lowest topographic diffusivities were recorded. An average topographic diffusivity for the Dry Valleys was determined to be 10M-5–10-4 m2

Diversity and ecological ranges of plant species from dry inter-Andean valleys

DEFF Research Database (Denmark)

Quintana, Catalina

found on steep slopes and in ravines. These areas of original dry valley vegetation preserve many wild relatives of cultivated plants on the one hand and old lineages of other wild plant groups. Dry inter-Andean valleys (DIAVs) in Ecuador therefore makeup a biodiversity hot spot for both plants......Dry valleys in the American Andes and other mountains have provided excellent agricultural lands since millennia. Besides agriculture, wood extraction and the establishment of urban areas have diminished the native vegetation of these valleys. Consequently the original vegetation is now mostly...... and animals, but unfortunately only very few botanical studies have been carried out in these areas. This thesis intends to shed light on the vegetation of the Dry Ecuadorean Inter-Andean Valleys in four chapters, each with a different focus. 1) A review paper that summarizes all scientific knowledge...

Comparison of snow melt properties across multiple spatial scales and landscape units in interior sub-Arctic boreal Alaskan watersheds

Science.gov (United States)

Bennett, K. E.; Cherry, J. E.; Hiemstra, C. A.; Bolton, W. R.

2013-12-01

Interior sub-Arctic Alaskan snow cover is rapidly changing and requires further study for correct parameterization in physically based models. This project undertook field studies during the 2013 snow melt season to capture snow depth, snow temperature profiles, and snow cover extent to compare with observations from the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor at four different sites underlain by discontinuous permafrost. The 2013 melt season, which turned out to be the latest snow melt period on record, was monitored using manual field measurements (SWE, snow depth data collection), iButtons to record temperature of the snow pack, GoPro cameras to capture time lapse of the snow melt, and low level orthoimagery collected at ~1500 m using a Navion L17a plane mounted with a Nikon D3s camera. Sites were selected across a range of landscape conditions, including a north facing black spruce hill slope, a south facing birch forest, an open tundra site, and a high alpine meadow. Initial results from the adjacent north and south facing sites indicate a highly sensitive system where snow cover melts over just a few days, illustrating the importance of high resolution temporal data capture at these locations. Field observations, iButtons and GoPro cameras show that the MODIS data captures the melt conditions at the south and the north site with accuracy (2.5% and 6.5% snow cover fraction present on date of melt, respectively), but MODIS data for the north site is less variable around the melt period, owing to open conditions and sparse tree cover. However, due to the rapid melt rate trajectory, shifting the melt date estimate by a day results in a doubling of the snow cover fraction estimate observed by MODIS. This information can assist in approximating uncertainty associated with remote sensing data that is being used to populate hydrologic and snow models (the Sacramento Soil Moisture Accounting model, coupled with SNOW-17, and the Variable

Ten-year trends of atmospheric mercury in the high Arctic compared to Canadian sub-Arctic and mid-latitude sites

Directory of Open Access Journals (Sweden)

A. S. Cole

2013-02-01

Full Text Available Global emissions of mercury continue to change at the same time as the Arctic is experiencing ongoing climatic changes. Continuous monitoring of atmospheric mercury provides important information about long-term trends in the balance between transport, chemistry, and deposition of this pollutant in the Arctic atmosphere. Ten-year records of total gaseous mercury (TGM from 2000 to 2009 were analyzed from two high Arctic sites at Alert (Nunavut, Canada and Zeppelin Station (Svalbard, Norway; one sub-Arctic site at Kuujjuarapik (Nunavik, Québec, Canada; and three temperate Canadian sites at St. Anicet (Québec, Kejimkujik (Nova Scotia and Egbert (Ontario. Five of the six sites examined showed a decreasing trend over this time period. Overall trend estimates at high latitude sites were: −0.9% yr⁻¹ (95% confidence limits: −1.4, 0 at Alert and no trend (−0.5, +0.7 at Zeppelin Station. Faster decreases were observed at the remainder of the sites: −2.1% yr⁻¹ (−3.1, −1.1 at Kuujjuarapik, −1.9% yr⁻¹ (−2.1, −1.8 at St. Anicet, −1.6% yr⁻¹ (−2.4, −1.0 at Kejimkujik and −2.2% yr⁻¹ (−2.8, −1.7 at Egbert. Trends at the sub-Arctic and mid-latitude sites agree with reported decreases in background TGM concentration since 1996 at Mace Head, Ireland, and Cape Point, South Africa, but conflict with estimates showing an increase in global anthropogenic emissions over a similar period. Trends in TGM at the two high Arctic sites were not only less negative (or neutral overall but much more variable by season. Possible reasons for differences in seasonal and overall trends at the Arctic sites compared to those at lower latitudes are discussed, as well as implications for the Arctic mercury cycle. The first calculations of multi-year trends in reactive gaseous mercury (RGM and total particulate mercury (TPM at Alert were also performed, indicating increases from 2002 to 2009

Pesticide presence in Great Lakes tributaries and comparison to ToxCast and other water quality benchmarks to screen for potential biological effects

Science.gov (United States)

Product Description:Pesticides are a broad category of current use chemicals that pose potential threats to aquatic organisms in and around the Great Lakes basin. In this study, we monitored for over 200 pesticides or their break down products in 16 major tributaries to the Great...

Best management practices plan for Phase II of the Bear Creek Valley treatability study, Oak Ridge Y-12 Plant, Oak Ridge, Tennessee

International Nuclear Information System (INIS)

1997-09-01

The Oak Ridge Y-12 Plant is currently under a Federal Agreement to define soil and groundwater contamination and develop remedies to protect human health and the environment. The western end of the site is known to have a former nitric acid disposal pit that has been remediated and capped. Remedial investigation data indicate this pit was a source of nitrate, uranium, technetium, and other metals contamination in groundwater. The downgradient receptor of this contamination includes Bear Creek and its tributaries. A feasibility study is under way to develop a remedy to prevent further contaminant migration to this receptor. To support the feasibility study, the treatability study is being completed to examine groundwater treatment at the S-3 site. This document serves as the top-level command medium for Phase II of the Bear Creek Valley (BCV) Treatability Study and, as such, will be the primary resource for management and implementation of field activities. Many of the details and standard operating procedures referred to herein can be found in other Lockheed Martin Energy Systems, Inc. (Energy Systems), documents. Several supporting documents specific to this project are also cited. These include the Sampling and Analysis Plan (SAP), the Health and Safety Plan (HASP), and the Waste Management Plan (WMP)

75 FR 17756 - Blackstone River Valley National Heritage Corridor Commission: Notice of Meeting

Science.gov (United States)

2010-04-07

... DEPARTMENT OF THE INTERIOR Office of the Secretary Blackstone River Valley National Heritage..., United States Code, that a meeting of the John H. Chafee Blackstone River Valley National Heritage... the meeting to: Jan H. Reitsma, Executive Director, John H. Chafee, Blackstone River Valley National...

West Valley Demonstration Project Annual Site Environmental Report Calendar Year 2004

Energy Technology Data Exchange (ETDEWEB)

West Valley Nuclear Services Company (WVNSCO) and URS Group, Inc.

2005-09-30

Annual Site Environmental Report for the West Valley Demonstration Project (WVDP) for Calendar Year 2004. The report summarizes the environmental protection program at the West Valley Demonstration Project for CY 2004.

West Valley Demonstration Project Annual Site Environmental Report Calendar Year 2004

International Nuclear Information System (INIS)

2005-01-01

Annual Site Environmental Report for the West Valley Demonstration Project (WVDP) for Calendar Year 2004. The report summarizes the environmental protection program at the West Valley Demonstration Project for CY 2004

Infill of tunnel valleys associated with landward‐flowing ice sheets

DEFF Research Database (Denmark)

Moreau, Julien; Huuse, Mads

2014-01-01

The southern termination of the Middle and Late Pleistocene Scandinavian ice sheets was repeatedly located in the southern North Sea (sNS) and adjacent, north-sloping land areas. Giant meltwater-excavated valleys (tunnel valleys) formed at the southern termination of the ice sheets and contain...

Long-term addition of fertilizer, labile carbon, and fungicide alters the biomass of plant functional groups in a subarctic-alpine community

DEFF Research Database (Denmark)

Haugwitz-Hardenberg-Reventlow, M S; Michelsen, A.

2011-01-01

experiment on a subarctic-alpine fellfield dominated by woody evergreen shrubs, bryophytes, and lichens. To manipulate nutrient availability additions of NPK fertilizer, labile C, and fungicide (benomyl) were done in a fully factorial design, replicated in six blocks. The treatments were run for 10 years...... vascular plant groups. Also, limitation of soil nutrient availability caused by labile C addition decreased the relative proportion of green shoots in evergreen shrubs, although these were expected to cope better with the nutrient limitation than the opportunistic graminoids, which, by contrast, were...... unaffected. Reduced fungal biomass due to benomyl addition was accompanied by increased evergreen shrub and clubmoss biomass. Taken together, the effects of treatments were most pronounced 16 years after initiation of the experiment, but despite changes in biomass the overall plant community composition...

Effects of coal-mine discharges on the quality of the Stonycreek River and its tributaries, Somerset and Cambria counties, Pennsylvania

Science.gov (United States)

Williams, Donald R.; Sams, James I.; Mulkerrin, Mary E.

1996-01-01

This report describes the results of a study by the U.S. Geological Survey, done in cooperation with the Somerset Conservation District, to locate and sample abandoned coal-mine discharges in the Stonycreek River Basin, to prioritize the mine discharges for remediation, and to determine the effects of the mine discharges on water quality of the Stonycreek River and its major tributaries. From October 1991 through November 1994, 270 abandoned coal-mine discharges were located and sampled. Discharges from 193 mines exceeded U.S. Environmental Protection Agency effluent standards for pH, discharges from 122 mines exceeded effluent standards for total-iron concentration, and discharges from 141 mines exceeded effluent standards for total-manganese concentration. Discharges from 94 mines exceeded effluent standards for all three constituents. Only 40 mine discharges met effluent standards for pH and concentrations of total iron and total manganese.A prioritization index (PI) was developed to rank the mine discharges with respect to their loading capacity on the receiving stream. The PI lists the most severe mine discharges in a descending order for the Stonycreek River Basin and for subbasins that include the Shade Creek, Paint Creek, Wells Creek, Quemahoning Creek, Oven Run, and Pokeytown Run Basins.Passive-treatment systems that include aerobic wetlands, compost wetlands, and anoxic limestone drains (ALD's) are planned to remediate the abandoned mine discharges. The successive alkalinity-producing-system treatment combines ALD technology with the sulfate reduction mechanism of the compost wetland to effectively remediate mine discharge. The water quality and flow of each mine discharge will determine which treatment system or combination of treatment systems would be necessary for remediation.A network of 37 surface-water sampling sites was established to determine stream-water quality during base flow. A series of illustrations show how water quality in the mainstem

Makran Mountain Range, Indus River Valley, Pakistan, India

Science.gov (United States)

1984-01-01

The enormous geologic pressures exerted by continental drift can be very well illustrated by the long northward curving parallel folded mountain ridges and valleys of the coastal Makran Range of Pakistan (27.0N, 66.0E). As a result of the collision of the northward bound Indian sub-continent into the Asian Continent, the east/west parallel range has been bent in a great northward arc and forming the Indus River valley at the interface of the collision.

pH gradients in the diffusive boundary layer of subarctic macrophytes

KAUST Repository

Hendriks, Iris E.; Duarte, Carlos M.; Marbà , Nú ria; Krause-Jensen, Dorte

2017-01-01

Highly productive macrophytes produce diurnal and seasonal cycles in CO concentrations modulated by metabolic activity, which cause discrepancies between pH in the bulk water and near seaweed blades, especially when entering the diffusion boundary layer (DBL). Calcifying epiphytic organisms living in this environment are therefore exposed to a different pH environment than that of the water column. To evaluate the actual pH environment on blade surfaces, we measured the thickness of the DBL and pH gradients within it for six subarctic macrophytes: Fucus vesiculosus, Ascophyllum nodosum, Ulva lactuca, Zostera marina, Saccharina longicruris, and Agarum clathratum. We measured pH under laboratory conditions at ambient temperatures (2–3 °C) and slow, stable flow over the blade surface at five light intensities (dark, 30, 50, 100 and 200 µmol photons m s). Boundary layer thickness ranged between 511 and 1632 µm, while the maximum difference in pH (∆pH) between the blade surface and the water column ranged between 0.4 ± 0.14 (average ± SE; Zostera) and 1.2 ± 0.13 (average ± SE; Ulva) pH units. These differences in pH are larger than predictions for pH changes in the bulk water by the end of the century. A simple quadratic model best described the relationship between light intensity and maximum ∆pH, pointing at relatively low optimum PAR of between 28 and 139 µmol photons m s to reach maximum ∆pH. Elevated pH at the blade surface may provide chemical “refugia” for calcifying epiphytic organisms, especially during summer at higher latitudes where photoperiods are long.

pH gradients in the diffusive boundary layer of subarctic macrophytes

KAUST Repository

Hendriks, Iris E.

2017-06-20

Highly productive macrophytes produce diurnal and seasonal cycles in CO concentrations modulated by metabolic activity, which cause discrepancies between pH in the bulk water and near seaweed blades, especially when entering the diffusion boundary layer (DBL). Calcifying epiphytic organisms living in this environment are therefore exposed to a different pH environment than that of the water column. To evaluate the actual pH environment on blade surfaces, we measured the thickness of the DBL and pH gradients within it for six subarctic macrophytes: Fucus vesiculosus, Ascophyllum nodosum, Ulva lactuca, Zostera marina, Saccharina longicruris, and Agarum clathratum. We measured pH under laboratory conditions at ambient temperatures (2–3 °C) and slow, stable flow over the blade surface at five light intensities (dark, 30, 50, 100 and 200 µmol photons m s). Boundary layer thickness ranged between 511 and 1632 µm, while the maximum difference in pH (∆pH) between the blade surface and the water column ranged between 0.4 ± 0.14 (average ± SE; Zostera) and 1.2 ± 0.13 (average ± SE; Ulva) pH units. These differences in pH are larger than predictions for pH changes in the bulk water by the end of the century. A simple quadratic model best described the relationship between light intensity and maximum ∆pH, pointing at relatively low optimum PAR of between 28 and 139 µmol photons m s to reach maximum ∆pH. Elevated pH at the blade surface may provide chemical “refugia” for calcifying epiphytic organisms, especially during summer at higher latitudes where photoperiods are long.

Transport of regional pollutants through a remote trans-Himalayan valley in Nepal

Directory of Open Access Journals (Sweden)

S. Dhungel

2018-01-01

Full Text Available Anthropogenic emissions from the combustion of fossil fuels and biomass in Asia have increased in recent years. High concentrations of reactive trace gases and light-absorbing and light-scattering particles from these sources form persistent haze layers, also known as atmospheric brown clouds, over the Indo–Gangetic plains (IGP from December through early June. Models and satellite imagery suggest that strong wind systems within deep Himalayan valleys are major pathways by which pollutants from the IGP are transported to the higher Himalaya. However, observational evidence of the transport of polluted air masses through Himalayan valleys has been lacking to date. To evaluate this pathway, we measured black carbon (BC, ozone (O3, and associated meteorological conditions within the Kali Gandaki Valley (KGV, Nepal, from January 2013 to July 2015. BC and O3 varied over both diurnal and seasonal cycles. Relative to nighttime, mean BC and O3 concentrations within the valley were higher during daytime when the up-valley flow (average velocity of 17 m s−1 dominated. BC and O3 concentrations also varied seasonally with minima during the monsoon season (July to September. Concentrations of both species subsequently increased post-monsoon and peaked during March to May. Average concentrations for O3 during the seasonally representative months of April, August, and November were 41.7, 24.5, and 29.4 ppbv, respectively, while the corresponding BC concentrations were 1.17, 0.24, and 1.01 µg m−3, respectively. Up-valley fluxes of BC were significantly greater than down-valley fluxes during all seasons. In addition, frequent episodes of BC concentrations 2–3 times higher than average persisted from several days to a week during non-monsoon months. Our observations of increases in BC concentration and fluxes in the valley, particularly during pre-monsoon, provide evidence that trans-Himalayan valleys are important conduits for transport of

Transport of regional pollutants through a remote trans-Himalayan valley in Nepal

Science.gov (United States)

Dhungel, Shradda; Kathayat, Bhogendra; Mahata, Khadak; Panday, Arnico

2018-01-01

Anthropogenic emissions from the combustion of fossil fuels and biomass in Asia have increased in recent years. High concentrations of reactive trace gases and light-absorbing and light-scattering particles from these sources form persistent haze layers, also known as atmospheric brown clouds, over the Indo-Gangetic plains (IGP) from December through early June. Models and satellite imagery suggest that strong wind systems within deep Himalayan valleys are major pathways by which pollutants from the IGP are transported to the higher Himalaya. However, observational evidence of the transport of polluted air masses through Himalayan valleys has been lacking to date. To evaluate this pathway, we measured black carbon (BC), ozone (O3), and associated meteorological conditions within the Kali Gandaki Valley (KGV), Nepal, from January 2013 to July 2015. BC and O3 varied over both diurnal and seasonal cycles. Relative to nighttime, mean BC and O3 concentrations within the valley were higher during daytime when the up-valley flow (average velocity of 17 m s-1) dominated. BC and O3 concentrations also varied seasonally with minima during the monsoon season (July to September). Concentrations of both species subsequently increased post-monsoon and peaked during March to May. Average concentrations for O3 during the seasonally representative months of April, August, and November were 41.7, 24.5, and 29.4 ppbv, respectively, while the corresponding BC concentrations were 1.17, 0.24, and 1.01 µg m-3, respectively. Up-valley fluxes of BC were significantly greater than down-valley fluxes during all seasons. In addition, frequent episodes of BC concentrations 2-3 times higher than average persisted from several days to a week during non-monsoon months. Our observations of increases in BC concentration and fluxes in the valley, particularly during pre-monsoon, provide evidence that trans-Himalayan valleys are important conduits for transport of pollutants from the IGP to the

Diversity of inland valleys and opportunities for agricultural development in Sierra Leone.

Directory of Open Access Journals (Sweden)

Elliott Ronald Dossou-Yovo

Full Text Available Inland valleys are becoming increasingly important agricultural production areas for rural households in sub-Saharan Africa due to their relative high and secure water availability and soil fertility. In addition, inland valleys are important as water buffer and biodiversity hot spots and they provide local communities with forest, forage, and fishing resources. As different inland-valley ecosystem functions may conflict with agricultural objectives, indiscriminate development should be avoided. This study aims to analyze the diversity of inland valleys in Sierra Leone and to develop guidelines for more precise interventions. Land use, biophysical and socio-economic data were analyzed on 257 inland valleys using spatial and multivariate techniques. Five cluster groups of inland valleys were identified: (i semi-permanently flooded with high soil organic carbon (4.2% and moderate available phosphorus (10.2 ppm, mostly under natural vegetation; (ii semi-permanently flooded with low soil organic carbon (1.5% and very low available phosphorus (3.1 ppm, abandoned by farmers; (iii seasonally flooded with moderate soil organic carbon (3.1% and low available phosphorus (8.3 ppm, used for rainfed rice and off-season vegetables produced without fertilizer application for household consumption and market; (iv well drained with moderate soil organic carbon (3.8% and moderate available phosphorus (10.0 ppm, used for rainfed rice and off-season vegetables produced with fertilizer application for household consumption and market; and (v well drained with moderate soil organic carbon (3.6% and moderate available phosphorus (11 ppm, used for household consumption without fertilizer application. Soil organic carbon, available phosphorus, hydrological regime, physical accessibility and market opportunity were the major factors affecting agricultural intensification of inland valleys. Opening up the areas in which inland valleys occur through improved roads and

Evaluating sediment transport in flood-driven ephemeral tributaries using direct and acoustic methods.

Science.gov (United States)

Stark, K.

2017-12-01

One common source of uncertainty in sediment transport modeling of large semi-arid rivers is sediment influx delivered by ephemeral, flood-driven tributaries. Large variations in sediment delivery are associated with these regimes due to the highly variable nature of flows within them. While there are many sediment transport equations, they are typically developed for perennial streams and can be inaccurate for ephemeral channels. Discrete, manual sampling is labor intensive and requires personnel to be on site during flooding. In addition, flooding within these tributaries typically last on the order of hours, making it difficult to be present during an event. To better understand these regimes, automated systems are needed to continuously sample bedload and suspended load. In preparation for the pending installation of an automated site on the Arroyo de los Piños in New Mexico, manual sediment and flow samples have been collected over the summer monsoon season of 2017, in spite of the logistical challenges. These data include suspended and bedload sediment samples at the basin outlet, and stage and precipitation data from throughout the basin. Data indicate a complex system; flow is generated primarily in areas of exposed bedrock in the center and higher elevations of the watershed. Bedload samples show a large coarse-grained fraction, with 50% >2 mm and 25% >6 mm, which is compatible with acoustic measuring techniques. These data will be used to inform future site operations, which will combine direct sediment measurement from Reid-type slot samplers and non-invasive acoustic measuring methods. Bedload will be indirectly monitored using pipe-style microphones, plate-style geophones, channel hydrophones, and seismometers. These instruments record vibrations and acoustic signals from bedload impacts and movement. Indirect methods for measuring of bedload have never been extensively evaluated in ephemeral channels in the southwest United States. Once calibrated

Persistence of bacterial pathogens, antibiotic resistance genes, and enterococci in tidal creek tributaries.

Science.gov (United States)

Jones, Chance E; Maddox, Anthony; Hurley, Dorset; Barkovskii, Andrei L

2018-05-19

Intertidal creeks form the primary hydrologic link between estuaries and land-based activities on barrier islands. Fecal indicators Enterococcus spp. (Entero1), pathogens Shigella spp. (ipaH), Salmonella spp. (invA), E. coli of EHEC/EPEC groups (eaeA), E. coli of EAEC, EIEC, and UPEC groups (set1B), E. coli of STEC group (stx1); and tetracycline resistance genes (tet(B), tet(C), tet(D), tet(E), tet(K), tet(Q), tet(W), and tet(X); TRG) were detected in the headwater of Oakdale Creek (Sapelo Island, GA) receiving runoffs from Hog Hammock village. Excavation of drainage ditches around the village caused a high increase in the incidence of the above determinants. Water samples were collected from the headwater, transferred to diffusion chambers, submersed in the headwater, saltmarsh, and mouth of the creek; and the determinants were monitored for 3 winter months. With some exceptions, their persistence decreased in order headwater > saltmarsh > mouth. Genes associated with Enterococcus spp. were the most persistent at all the sites, following in the headwater with determinants for Salmonella spp. and E. coli of EAEC, EIEC, and UPEC groups. In the mouth, the most persistent gene was eaeA indicating EHEC, EPEC, and STEC. Tet(B) and tet(C) persisted the longest in headwater and saltmarsh. No TRG persisted after 11 days in the mouth. Most determinants revealed correlations with temperature and pH, and inverse correlations with dissolved oxygen. Decay rates of the above determinants varied in the range of -0.02 to -0.81/day, and were up to 40 folds higher in the saltmarsh and mouth than in the headwater. Our data demonstrated that water parameters could to some extent predict a general trend in the fate of virulence and antibiotic resistance determinants in tidal creek tributaries but strongly suggested that their persistence in these tributaries cannot be predicted from that of enterococci, or extrapolated from one biological contaminant to another. Copyright

Year-round presence of neonicotinoid insecticides in tributaries to the Great Lakes, USA

Science.gov (United States)

Hladik, Michelle; Corsi, Steven; Kolpin, Dana W.; Baldwin, Austin K.; Blackwell, Brett R.; Cavallin, Jenna E.

2018-01-01

To better characterize the transport of neonicotinoid insecticides to the world's largest freshwater ecosystem, monthly samples (October 2015–September 2016) were collected from 10 major tributaries to the Great Lakes, USA. For the monthly tributary samples, neonicotinoids were detected in every month sampled and five of the six target neonicotinoids were detected. At least one neonicotinoid was detected in 74% of the monthly samples with up to three neonicotinoids detected in an individual sample (10% of all samples). The most frequently detected neonicotinoid was imidacloprid (53%), followed by clothianidin (44%), thiamethoxam (22%), acetamiprid (2%), and dinotefuran (1%). Thiacloprid was not detected in any samples. The maximum concentration for an individual neonicotinoid was 230 ng L−1 and the maximum total neonicotinoids in an individual sample was 400 ng L−1. The median detected individual neonicotinoid concentrations ranged from non-detect to 10 ng L−1. The detections of clothianidin and thiamethoxam significantly increased as the percent of cultivated crops in the basins increased (ρ = 0.73, P = .01; ρ = 0.66, P = .04, respectively). In contrast, imidacloprid detections significantly increased as the percent of the urbanization in the basins increased (ρ = 0.66, P = .03). Neonicotinoid concentrations generally increased in spring through summer coinciding with the planting of neonicotinoid-treated seeds and broadcast applications of neonicotinoids. More spatially intensive samples were collected in an agriculturally dominated basin (8 sites along the Maumee River, Ohio) twice during the spring, 2016 planting season to provide further information on neonicotinoid inputs to the Great Lakes. Three neonicotinoids were ubiquitously detected (clothianidin, imidacloprid, thiamethoxam) in all water samples collected within this basin. Maximum individual neonicotinoid concentrations was 330 ng L−1�

Hydrologic and Geomorphic Impacts of Glacial Lake Outburst Floods From Low-Order Tributaries

Science.gov (United States)

McCoy, S. W.; Jacquet, J.; McGrath, D.; George, D. L.; Koschitzki, R.; Nimick, D.; Fahey, M. J.; Okuinghttons, J.

2017-12-01

Lakes dammed by glacial ice or moraines are common features in the headwaters of both glaciated and recently deglaciated catchments. These dams can fail releasing water in a glacial lake outburst flood (GLOF), which raises the question: do GLOFs from low-order tributaries significantly alter the hydrology and sediment transport regimes of the large mainstem rivers to which they drain? Here we use repeat satellite imagery, in situ measurements, and 2D hydrodynamic modeling to quantify the hydrologic and geomorphic changes that resulted from 22 GLOFs that occurred between 2008 and 2016 from Lago Cachet Dos, Patagonia, Chile. We find that the complicated flood path that includes two lakes and a broad floodplain can dampen peak discharges from over 15,000 m³/s at the source lake to generally less than 2,000 m³/s where the floods enter the mainstem Rio Baker, 40 km downstream. Despite this dampening of GLOF peak discharge, peak discharges still exceeded the peak annual discharge of the Rio Baker, the largest river in Chile by volume, by 1 to 2 times, which in turn increased the frequency and magnitude of flood events. We also document the sediment dynamics in the source lake, where we find that over 25,000,000 m³ of stored sediment was removed during the GLOF cycle that began in 2008. Further downstream, repeat satellite imagery reveals that the large discharges associated with GLOFs produced a nonsteady channel configuration in which old stable channels were abandoned, many new channels were formed, and conveyance capacity changed, best illustrated by the 200 m of delta progradation from the GLOF-affected tributary into the Rio Baker that locally narrowed the Rio Baker channel width from 300 m to 60 m. In total, this analysis demonstrates that GLOFs from distant source lakes can have an outsized impact, both in terms of changing flood characteristics as well as sediment transport, even on the largest river systems.

Geohydrology, water quality, and simulation of groundwater flow in the stratified-drift aquifer system in Virgil Creek and Dryden Lake Valleys, Town of Dryden, Tompkins County, New York

Science.gov (United States)

Miller, Todd S.; Bugliosi, Edward F.

2013-01-01

stratified-drift aquifers at the Valley Heads Moraine, which consists of heterogeneous sediments including coarse-grained outwash and kame sediments, as well as zones containing till with a fine-grained matrix. In the southern part of the study area, the confining units are thin and likely to be discontinuous in some places, resulting in windows of permeable sediment, which can more readily transmit recharge from precipitation and from tributaries that lose water as they flow over the valley floor. In contrast, in the northern part of the study area, the confining units are thick, continuous, and comprise homogeneous fine-grained sediments that more effectively confine the aquifers than in the southern part of the study area. Most groundwater in the northern part of the study area discharges to the Village of Dryden municipal production wells, to the outlet to Dryden Lake, to Virgil Creek, and as groundwater underflow that exits the northern boundary of the study area. Most northward-flowing groundwater in the southern part of the study area discharges to Dryden Lake, to the inlet to Dryden Lake, and to homeowner, nonmunicipal community (a mobile home community and several apartments), and commercial wells. Most of this pumped water is returned to the groundwater system via septic systems. Most southward-flowing groundwater in the southern part of the study area discharges to the headwaters of Owego Creek and to agricultural wells; some flow also exits the southern boundary of the study area as groundwater underflow. The largest user of groundwater in the study area is the Village of Dryden. Water use in the village has approximately tripled between the early 1970s when withdrawals ranged between 18 and 30 million gallons per year (Mgal/yr) and from 2000 through 2008 when withdrawals ranged between 75 and 85 Mgal/yr. The estimated groundwater use by homeowners, nonmunicipal communities, and small commercial facilities outside the area supplied by the Village of Dryden

Structural evolution of the east Sierra Valley system (Owens Valley and vicinity), California: a geologic and geophysical synthesis

Science.gov (United States)

Stevens, Calvin H.; Stone, Paul; Blakely, Richard J.

2013-01-01

The tectonically active East Sierra Valley System (ESVS), which comprises the westernmost part of the Walker Lane-Eastern California Shear Zone, marks the boundary between the highly extended Basin and Range Province and the largely coherent Sierra Nevada-Great Valley microplate (SN-GVm), which is moving relatively NW. The recent history of the ESVS is characterized by oblique extension partitioned between NNW-striking normal and strike-slip faults oriented at an angle to the more northwesterly relative motion of the SN-GVm. Spatially variable extension and right-lateral shear have resulted in a longitudinally segmented valley system composed of diverse geomorphic and structural elements, including a discontinuous series of deep basins detected through analysis of isostatic gravity anomalies. Extension in the ESVS probably began in the middle Miocene in response to initial westward movement of the SN-GVm relative to the Colorado Plateau. At ca. 3-3.5 Ma, the SN-GVm became structurally separated from blocks directly to the east, resulting in significant basin-forming deformation in the ESVS. We propose a structural model that links high-angle normal faulting in the ESVS with coeval low-angle detachment faulting in adjacent areas to the east.

Clean Cities Award Winning Coalition: Coachella Valley

Energy Technology Data Exchange (ETDEWEB)

ICF Kaiser

1999-05-20

Southern California's Coachella Valley became a Clean Cities region in 1996. Since then, they've made great strides. SunLine Transit, the regional public transit provider, was the first transit provider to replace its entire fleet with compressed natural gas buses. They've also built the foundation for a nationally recognized model in the clean air movement, by partnering with Southern California Gas Company to install a refueling station and developing a curriculum for AFV maintenance with the College of the Desert. Today the valley is home to more than 275 AFVs and 15 refueling stations.

Some Environmental Issues of Inland Valleys: A Case Study | Asiam ...

African Journals Online (AJOL)

The study concluded that inland valleys can be real environmental liability because produce from such valleys can be polluted and hence can be a source of social conflict particularly when they fringe mineral concessions as the adverse impacts could be unfortunately attributed to mining activity and similar land uses.

Parking Space Occupancy at Rail Stations in Klang Valley

Directory of Open Access Journals (Sweden)

Ho Phooi Wai

2017-01-01

Full Text Available The development of Klang Valley Integrated Rapid Transit system in Klang Valley, Malaysia has been quickly gaining momentum during the recent years. There will be two new MRT lines (MRT Line 1 and MRT Line 2 and one new LRT line (LRT Line 3 extended from the current integrated rail transit system by year 2020 with more than 90 new rail stations. With the substantial addition of potential rail passengers, there are doubts whether the existing Park and Ride facilities in Klang Valley are able to accommodate the future parking space demand at rail stations. This research studies the parking occupancy at various Park and Ride facilities in Klang Valley namely Taman Jaya, Asia Jaya, Taman Paramount, Taman Bahagia and Kelana Jaya by applying the non-conventional method utilizing Google Earth imageries. Results showed that the parking occupancy rate at these LRT stations were 100% or more before the commencement of LRT extension (Kelana Jaya and Ampang Lines in 2016 and in the range of 36% to 100% after the commencement of LRT extension due to the additionally built car parks and changes in parking pattern with dispersed passenger traffic.

Martian channels and valleys - Their characteristics, distribution, and age

Science.gov (United States)

Carr, M. H.; Clow, G. D.

1981-01-01

The distribution and ages of Martian channels and valleys, which are generally believed to have been cut by running water, are examined with particular emphasis on the small branching networks referred to as runoff channels or valley networks. Valleys at latitudes from 65 deg S to 65 deg N were surveyed on Viking images at resolutions between 125 and 300 m. Almost all of the valleys are found in the old cratered terrain, in areas characterized by high elevations, low albedos and low violet/red ratios. The networks are deduced to have formed early in the history of the planet, with a formation rate declining rapidly shortly after the decline of the cratering rate 3.9 billion years ago. Two types of outflow channels are distinguished: unconfined, in which broad swaths of terrain are scoured, and confined, in which flow is restricted to discrete channels. Both types start at local sources, and have formed episodically throughout Martian history. Fretted channels, found mainly in two latitude belts characterized by relatively rapid erosion along escarpments, are explained by the lateral enlargement of other channels by mass wasting.

Reporting on nuclear power: the Tennessee Valley case

International Nuclear Information System (INIS)

Shapley, D.

1977-01-01

The Tennessee Valley Authority (TVA), by deciding to have 90 percent of its new generating capacity nuclear, has made the valley a testing ground for civilian nuclear power, but valley newspapers have not provided consumers with enough information on either the pros or cons. A 1975 Browns Ferry plant fire, the most serious in the history of the civilian nuclear industry, prompted some nuclear critics to question TVA's competence to plan and manage the program. Newspapers carried wire-service stories of the fire, while their editorials gave strong support to TVA and the effort to reopen the plant. Valley newspapers have traditionally favored TVA as a powerful economic and political force which has brought many benefits. Local pride in the Oak Ridge Laboratory and plant facilities and the Federal fast-breeder reactor project headquarters also enhanced the positive attitude of the press, which tended to report details but not question nuclear safety or TVA ability. Newspapers have also failed to question TVA's claims that rates will decline as nuclear plants begin operating. A review of relevant news stories during the 1975--1976 period addresses the press coverage and notes its failure to question whether power demands justify TVA's plant construction program. Knowledgeable consultants are available to provide information on the issues, while editors are advised to give comprehensive, critical coverage and avoid promotion

Into the deep: A coarse-grained carbonate turbidite thalweg generated by gigantic submarine chutes

Science.gov (United States)

Mulder, Thierry; Gillet, Hervé; Reijmer, John; Droxler, André; cavailhes, Thibault; Hanquiez, Vincent; Fauquembergue, Kelly; Bujan, Stéphane; Blanck, David; bashah, Sara; Guiastrennec, Léa; Fabregas, Natacha; Recouvreur, Audrey; Seibert, Chloé

2017-04-01

New high-resolution multibeam mapping, in the Southeastern Bahamas, images in exquisite details the southern part of Exuma Sound, and its unchartered transition area to the deep abyssal plain of the Western North Atlantic bounded by the Bahama Escarpment (BE) between San Salvador Island and Samana Cay, referred here to the San Salvador abyssal plain. The transition area is locally referred to as Crooked Island Passage, loosely delineated by Crooked, Long, and Conception Islands, Rum and Samana Cays. Surprisingly in such a pure carbonate landscape, the newly established map reveals the detailed and complex morphology of a giant valley formed by numerous gravity flows originated in Exuma Sound itself, in addition to many secondary slope gullies and smaller tributaries draining the surrounding upper slopes. The valley referred here as the Exuma canyon system starts with a perched valley with low sinuosity, characterized by several flow restrictions and knickpoints initiated by the presence of drowned isolated platforms and merging tributaries. The valley abruptly transforms itself into a deep incised canyon, rivaling the depth of the Colorado Grand Canyon, through two major knickpoints with outsized chutes exceeding several hundred of meters in height, a total of 1600-1800 m. The sudden transformation of the wide valley into a deep narrow canyon, occurring when the flows incised deep into an underlying lower Cretaceous drowned carbonate platform, generates a huge hydraulic jump and creates an enormous plunge pool and related deposits with mechanisms comparable to the ones operating along giant subaerial waterfalls. The high kinetic flow energy, constrained by this narrow and deeply incised canyon, formed, when it is released at its mouth in the abyssal plain, a wide deep-sea channel with well-developed levees and fan, made of coarse-grained carbonate defined layers separated by fine carbonate sediments mixed with fine siliciclastics transported along the BE by the

Decision analysis framing study; in-valley drainage management strategies for the western San Joaquin Valley, California

Science.gov (United States)

Presser, Theresa S.; Jenni, Karen E.; Nieman, Timothy; Coleman, James

2010-01-01

Constraints on drainage management in the western San Joaquin Valley and implications of proposed approaches to management were recently evaluated by the U.S. Geological Survey (USGS). The USGS found that a significant amount of data for relevant technical issues was available and that a structured, analytical decision support tool could help optimize combinations of specific in-valley drainage management strategies, address uncertainties, and document underlying data analysis for future use. To follow-up on USGS's technical analysis and to help define a scientific basis for decisionmaking in implementing in-valley drainage management strategies, this report describes the first step (that is, a framing study) in a Decision Analysis process. In general, a Decision Analysis process includes four steps: (1) problem framing to establish the scope of the decision problem(s) and a set of fundamental objectives to evaluate potential solutions, (2) generation of strategies to address identified decision problem(s), (3) identification of uncertainties and their relationships, and (4) construction of a decision support model. Participation in such a systematic approach can help to promote consensus and to build a record of qualified supporting data for planning and implementation. In December 2008, a Decision Analysis framing study was initiated with a series of meetings designed to obtain preliminary input from key stakeholder groups on the scope of decisions relevant to drainage management that were of interest to them, and on the fundamental objectives each group considered relevant to those decisions. Two key findings of this framing study are: (1) participating stakeholders have many drainage management objectives in common; and (2) understanding the links between drainage management and water management is necessary both for sound science-based decisionmaking and for resolving stakeholder differences about the value of proposed drainage management solutions. Citing

Occurrence and variability of mining-related lead and zinc in the Spring River flood plain and tributary flood plains, Cherokee County, Kansas, 2009--11

Science.gov (United States)

Juracek, Kyle E.

2013-01-01

Historical mining activity in the Tri-State Mining District (TSMD), located in parts of southeast Kansas, southwest Missouri, and northeast Oklahoma, has resulted in a substantial ongoing input of cadmium, lead, and zinc to the environment. To provide some of the information needed to support remediation efforts in the Cherokee County, Kansas, superfund site, a 4-year study was begun in 2009 by the U.S. Geological Survey that was requested and funded by the U.S. Environmental Protection Agency. A combination of surficial-soil sampling and coring was used to investigate the occurrence and variability of mining-related lead and zinc in the flood plains of the Spring River and several tributaries within the superfund site. Lead- and zinc-contaminated flood plains are a concern, in part, because they represent a long-term source of contamination to the fluvial environment. Lead and zinc contamination was assessed with reference to probable-effect concentrations (PECs), which represent the concentrations above which adverse aquatic biological effects are likely to occur. The general PECs for lead and zinc were 128 and 459 milligrams per kilogram, respectively. The TSMD-specific PECs for lead and zinc were 150 and 2,083 milligrams per kilogram, respectively. Typically, surficial soils in the Spring River flood plain had lead and zinc concentrations that were less than the general PECs. Lead and zinc concentrations in the surficial-soil samples were variable with distance downstream and with distance from the Spring River channel, and the largest lead and zinc concentrations usually were located near the channel. Lead and zinc concentrations larger than the general or TSMD-specific PECs, or both, were infrequent at depth in the Spring River flood plain. When present, such contamination typically was confined to the upper 2 feet of the core and frequently was confined to the upper 6 inches. Tributaries with few or no lead- and zinc-mined areas in the basin—Brush Creek

BPA/Lower Valley transmission project. Final environmental impact statement

International Nuclear Information System (INIS)

1998-06-01

Bonneville Power Administration and Lower Valley Power and Light, Inc. propose to solve a voltage stability problem in the Jackson and Afton, Wyoming areas. Lower Valley buys electricity from BPA and then supplies it to the residences and businesses of the Jackson and Afton, Wyoming areas. BPA is considering five alternatives. For the Agency Proposed Action, BPA and Lower Valley would construct a new 115-kV line from BPA's Swan Valley Substation near Swan Valley in Bonneville County, Idaho about 58 km (36 miles) east to BPA's Teton Substation near Jackson in Teton County, Wyoming. The new line would be next to an existing 115-kV line. The Single-Circuit Line Alternative has all the components of the Agency Proposed Action except that the entire line would be supported by single-circuit wood pole H-frame structures. the Short Line Alternative has all the components of the Single-Circuit Line Alternative except it would only be half as long. BPA would also construct a new switching station near the existing right-of-way, west or north of Targhee Tap. Targhee Tap would then be removed. For the Static Var Compensation Alternative, BPA would install a Static Var Compensator (SVC) at Teton or Jackson Substation. An SVC is a group of electrical equipment placed at a substation to help control voltage on a transmission system. The No Action Alternative assumes that no new transmission line is built, and no other equipment is added to the transmission system

Vitrification facility at the West Valley Demonstration Project

International Nuclear Information System (INIS)

DesCamp, V.A.; McMahon, C.L.

1996-07-01

This report is a description of the West Valley Demonstration Project's vitrification facilities from the establishment of the West Valley, NY site as a federal and state cooperative project to the completion of all activities necessary to begin solidification of radioactive waste into glass by vitrification. Topics discussed in this report include the Project's background, high-level radioactive waste consolidation, vitrification process and component testing, facilities design and construction, waste/glass recipe development, integrated facility testing, and readiness activities for radioactive waste processing

Rift Valley fever potential mosquito vectors and their infection status ...

African Journals Online (AJOL)

Background: Rift Valley fever (RVF) is a mosquito-borne viral zoonotic disease. Rift Valley fever virus (RVFV) has been isolated from more than 40 species of mosquitoes from eight genera. This study was conducted to determine the abundance of potential mosquito vectors and their RVFV infection status in Ngorongoro ...

Hydrogeologic Framework and Ground Water in Basin-Fill Deposits of the Diamond Valley Flow System, Central Nevada

Science.gov (United States)

Tumbusch, Mary L.; Plume, Russell W.

2006-01-01

The Diamond Valley flow system, an area of about 3,120 square miles in central Nevada, consists of five hydrographic areas: Monitor, Antelope, Kobeh, and Diamond Valleys and Stevens Basin. Although these five areas are in a remote part of Nevada, local government officials and citizens are concerned that the water resources of the flow system eventually could be further developed for irrigation or mining purposes or potentially for municipal use outside the study area. In order to better understand the flow system, the U.S. Geological Survey in cooperation with Eureka, Lander, and Nye Counties and the Nevada Division of Water Resources, is conducting a multi-phase study of the flow system. The principal aquifers of the Diamond Valley flow system are in basin-fill deposits that occupy structural basins comprised of carbonate rocks, siliciclastic sedimentary rocks, igneous intrusive rocks, and volcanic rocks. Carbonate rocks also function as aquifers, but their extent and interconnections with basin-fill aquifers are poorly understood. Ground-water flow in southern Monitor Valley is from the valley margins toward the valley axis and then northward to a large area of discharge by evapotranspiration (ET) that is formed south of a group of unnamed hills near the center of the valley. Ground-water flow from northern Monitor Valley, Antelope Valley, and northern and western parts of Kobeh Valley converges to an area of ground-water discharge by ET in central and eastern Kobeh Valley. Prior to irrigation development in the 1960s, ground-water flow in Diamond Valley was from valley margins toward the valley axis and then northward to a large discharge area at the north end of the valley. Stevens Basin is a small upland basin with internal drainage and is not connected with other parts of the flow system. After 40 years of irrigation pumping, a large area of ground-water decline has developed in southern Diamond Valley around the irrigated area. In this part of Diamond

Groundwater budgets for Detrital, Hualapai, and Sacramento Valleys, Mohave County, Arizona, 2007-08

Science.gov (United States)

Garner, Bradley D.; Truini, Margot

2011-01-01

The United States Geological Survey, in cooperation with the Arizona Department of Water Resources, initiated an investigation of the hydrogeology and water resources of Detrital, Hualapai, and Sacramento Valleys in northwestern Arizona in 2005, and this report is part of that investigation. Water budgets were developed for Detrital, Hualapai, and Sacramento Valleys to provide a generalized understanding of the groundwater systems in this rural area that has shown some evidence of human-induced water-level declines. The valleys are within the Basin and Range physiographic province and consist of thick sequences of permeable alluvial sediment deposited into basins bounded by relatively less permeable igneous and metamorphic rocks. Long-term natural recharge rates (1940-2008) for the alluvial aquifers were estimated to be 1,400 acre-feet per year (acre-ft/yr) for Detrital Valley, 5,700 acre-ft/yr for Hualapai Valley, and 6,000 acre-ft/yr for Sacramento Valley. Natural discharge rates were assumed to be equal to natural recharge rates, on the basis of the assumption that all groundwater withdrawals to date have obtained water from groundwater storage. Groundwater withdrawals (2007-08) for the alluvial aquifers were less than 300 acre-ft/yr for Detrital Valley, about 9,800 acre-ft/yr for Hualapai Valley, and about 4,500 acre-ft/yr for Sacramento Valley. Incidental recharge from leaking water-supply pipes, septic systems, and wastewater-treatment plants accounted for about 35 percent of total recharge (2007-08) across the study area. Natural recharge and discharge values in this study were 24-50 percent higher than values in most previously published studies. Water budgets present a spatially and temporally "lumped" view of water resources and incorporate many sources of uncertainty in this study area where only limited data presently are available.

Diurnal cycle of air pollution in the Kathmandu Valley, Nepal: 2. Modeling results

Science.gov (United States)

Panday, Arnico K.; Prinn, Ronald G.; SchäR, Christoph

2009-11-01

After completing a 9-month field experiment studying air pollution and meteorology in the Kathmandu Valley, Nepal, we set up the mesoscale meteorological model MM5 to simulate the Kathmandu Valley's meteorology with a horizontal resolution of up to 1 km. After testing the model against available data, we used it to address specific questions to understand the factors that control the observed diurnal cycle of air pollution in this urban basin in the Himalayas. We studied the dynamics of the basin's nocturnal cold air pool, its dissipation in the morning, and the subsequent growth and decay of the mixed layer over the valley. During mornings, we found behavior common to large basins, with upslope flows and basin-center subsidence removing the nocturnal cold air pool. During afternoons the circulation in the Kathmandu Valley exhibited patterns common to plateaus, with cooler denser air originating over lower regions west of Kathmandu arriving through mountain passes and spreading across the basin floor, thereby reducing the mixed layer depth. We also examined the pathways of pollutant ventilation out of the valley. The bulk of the pollution ventilation takes place during the afternoon, when strong westerly winds blow in through the western passes of the valley, and the pollutants are rapidly carried out through passes on the east and south sides of the valley. In the evening, pollutants first accumulate near the surface, but then are lifted slightly when katabatic flows converge underneath. The elevated polluted layers are mixed back down in the morning, contributing to the morning pollution peak. Later in the morning a fraction of the valley's pollutants travels up the slopes of the valley rim mountains before the westerly winds begin.

PROFILE OF SOCIAL SERVICES FROM JIU VALLEY IN LIGHT PROFESSIONALS PERCEPTION. QUALITATIVE APPROACH

Directory of Open Access Journals (Sweden)

FELICIA ANDRIONI

2012-10-01

Full Text Available This study aims to analyse Jiu Valley social services profile using a qualitative perspective – focus grup analysis, by investigating perceptions of social services professionals from Jiu Valley, Hunedoara County, Romania. The qualitative methods of investigation, particularly important in achieving a comprehensive profile of social services from the Jiu Valley was to achieve a focused discussion sessions on social services. The following objectives were targeted by focus group: analysis of social professionals’ perception on social services from the Jiu Valley, Hunedoara County and identifying internal and external factors, to put their mark on the functioning of social services. Upon completion of discussions session focusing on social services in the Jiu Valley to conclude on the following aspects: social professionals perceive favorable development of social services in the Jiu Valley region in the period 2002-2008, and considering the dynamic development of these services is progressive. There are a number of elements which are seen by professionals as catalysts for the proper functioning and development of social services and factors inhibiting or blocking the functioning of these services.

West Valley facility spent fuel handling, storage, and shipping experience

International Nuclear Information System (INIS)

Bailey, W.J.

1990-11-01

The result of a study on handling and shipping experience with spent fuel are described in this report. The study was performed by Pacific Northwest Laboratory (PNL) and was jointly sponsored by the US Department of Energy (DOE) and the Electric Power Research Institute (EPRI). The purpose of the study was to document the experience with handling and shipping of relatively old light-water reactor (LWR) fuel that has been in pool storage at the West Valley facility, which is at the Western New York Nuclear Service Center at West Valley, New York and operated by DOE. A subject of particular interest in the study was the behavior of corrosion product deposits (i.e., crud) deposits on spent LWR fuel after long-term pool storage; some evidence of crud loosening has been observed with fuel that was stored for extended periods at the West Valley facility and at other sites. Conclusions associated with the experience to date with old spent fuel that has been stored at the West Valley facility are presented. The conclusions are drawn from these subject areas: a general overview of the West Valley experience, handling of spent fuel, storing of spent fuel, rod consolidation, shipping of spent fuel, crud loosening, and visual inspection. A list of recommendations is provided. 61 refs., 4 figs., 5 tabs

Rod consolidation at the West Valley Demonstration Project

International Nuclear Information System (INIS)

Bailey, W.J.

1986-12-01

A rod consolidation demonstration with irradiated pressurized water reactor fuel was recently conducted by personnel from Nuclear Assurance Corporation and West Valley Nuclear Services Company at the West Valley Demonstration Project in West Valley, New York. The rod consolidation demonstration involved pulling all of the fuel rods from six fuel Assemblies. In general, the rod pulling proceeded smoothly. The highest compaction ratio attained was 1:8:1. Among the total of 1074 fuel rods were some known degraded rods (they had collapsed cladding, a result of in-reactor fuel densification), but no rods were broken or dropped during the demonstration. One aim was to gather information on the effect of rod consolidation operations on the integrity of the fuel rods during subsequent handling and storage. Another goal was to collect information on the condition and handling of intact, damaged, and failed fuel that has been in storage for an extended period. 9 refs., 8 figs., 1 tab

Salinity and resource management in the Hunter Valley

Energy Technology Data Exchange (ETDEWEB)

Creelman, R.A.; Cooke, R.; Simons, M. [RA Creelman & Associates (Australia)

1995-08-01

If excess water salinity is to be managed in the Hunter Valley, its causes and behaviour must be understood. Although Hunter Valley hydrology, hydrogeology and hydrogeochemistry require further study, there is now enough information available to begin the development of both temporal and spatial models as valley management tools. Currently the Department of Water Resources is developing a model known as Integrated Water Quality and Quantity Model (IQQM). IQQM which includes a salinity module is essentially a surface water simulation model. It wll enable testing of alternate management and operation policies such as the salinity property rights trading scheme recently introduced by the EPA to manage salt release from coal mines and power stations. An overview is presented of the progress made to date on the salinity module for IQQM, and an outline is given of the geological and hydrogeochemical concepts that have been assembled to support the salinity module of IQQM. 17 refs., 3 figs., 1 tab.

The Uncanny Valley and Nonverbal Communication in Virtual Characters

DEFF Research Database (Denmark)

Tinwell, Angela; Grimshaw, Mark Nicholas; Abdel Nabi, Debbie

2014-01-01

This chapter provides an overview of a current research project investigating the Uncanny Valley phenomenon in realistic, human-like virtual characters. !e research methods used in this Work include a retrospective of both empirical studies and philosophical writings on the Uncanny. No other...... research has explored the notion that realistic, human-like, virtual characters are regarded less favorably due to a perceived diminished degree of responsiveness in facial expression, specifically, nonverbal communication (NVC) in the upper face region. So far, this research project has provided the first...... empirical evidence to test the Uncanny Valley phenomenon in the domain of animated video game characters with speech, as opposed to just still, unresponsive images, as used in previous studies. Based on the results of these experiments, a conceptual framework of the Uncanny Valley in virtual characters has...

Generation of valley-polarized electron beam in bilayer graphene

International Nuclear Information System (INIS)

Park, Changsoo

2015-01-01

We propose a method to produce valley-polarized electron beams using a bilayer graphene npn junction. By analyzing the transmission properties of electrons through the junction with zigzag interface in the presence of trigonal warping, we observe that there exist a range of incident energies and barrier heights in which transmitted electrons are well polarized and collimated. From this observation and by performing numerical simulations, it is demonstrated that valley-dependent electronic currents with nearly perfect polarization can be generated. We also show that the peak-to-peak separation angle between the polarized currents is tunable either by incident energy or by barrier height each of which is controlled by using top and back gate voltages. The results can be used for constructing an electron beam splitter to produce valley-polarized currents

Generation of valley-polarized electron beam in bilayer graphene

Science.gov (United States)

Park, Changsoo

2015-12-01

We propose a method to produce valley-polarized electron beams using a bilayer graphene npn junction. By analyzing the transmission properties of electrons through the junction with zigzag interface in the presence of trigonal warping, we observe that there exist a range of incident energies and barrier heights in which transmitted electrons are well polarized and collimated. From this observation and by performing numerical simulations, it is demonstrated that valley-dependent electronic currents with nearly perfect polarization can be generated. We also show that the peak-to-peak separation angle between the polarized currents is tunable either by incident energy or by barrier height each of which is controlled by using top and back gate voltages. The results can be used for constructing an electron beam splitter to produce valley-polarized currents.

Vertical ozone transport in the Alps (VOTALP): the valley experiment 1996

Energy Technology Data Exchange (ETDEWEB)

Furger, M; Dommen, J; Graber, W K; Prevot, A; Poggio, L; Andreani, S; Keller, J; Portmann, W; Buerki, D; Erne, R; Richter, R; Tinguely, M [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

1997-06-01

The EU project VOTALP started its valley campaign in the summer of 1996 in the Mesolcina valley. The influence of thermal circulations on ozone concentrations and on the exchange of ozone and its photochemical precursors between the valley atmosphere and the free troposphere above was the main focus of the study. PSI has participated with various measurement systems (conventional meteorological surface stations, radiosondes, scidar/DOAS systems, chemical analysers). An overview of PSI`s activities in the field campaign is given, and some preliminary results are presented. (author) 1 fig., 2 tabs., 2 refs.

75 FR 70020 - Central Valley Project Improvement Act, Water Management Plans

Science.gov (United States)

2010-11-16

... office on Central Valley Project water conservation best management practices that shall ``* * * develop... DEPARTMENT OF THE INTERIOR Bureau of Reclamation Central Valley Project Improvement Act, Water Management Plans AGENCY: Bureau of Reclamation, Interior ACTION: Notice of Availability. SUMMARY: The...

76 FR 12756 - Central Valley Project Improvement Act, Water Management Plans

Science.gov (United States)

2011-03-08

... office on Central Valley Project water conservation best management practices that shall ``* * * develop... DEPARTMENT OF THE INTERIOR Bureau of Reclamation Central Valley Project Improvement Act, Water Management Plans AGENCY: Bureau of Reclamation, Interior. ACTION: Notice of availability. SUMMARY: The...