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Fish assemblages were sampled in 195 randomly selected lakes in the northeastern United States during the summers of 1991-1994. Most lakes in northern Maine had three to seven minnow species, constituting 40-80% of species in each lake. Lakes in New Jersey, southern New York, and...
Bythotrephes cederstroemi is a non-indigenous predaceous zooplankter invading North American freshwater lakes in the Great Lakes region. We present seasonal population abundance values for both Bythotrephes and Leptodora kindtii from Lake Michigamme, Michigan for the years ...
Regulatory agencies must develop fish consumption advisories for many lakes and rivers with limited resources. Process-based mathematical models are potentially valuable tools for developing regional fish advisories. The Regional Mercury Cycling model (R-MCM) was specifically d...
2010-01-01
Reader Lake and Elbow Lake, two high-altitude lakes in the Uinta Mountains of Utah, are located approximately 2km apart, at similar elevations, and within identical vegetation communities. Loss on ignition, carbon to nitrogen ratios, biogenic silica, and sediment grain size were analyzed throughout percussion cores retrieved from both lakes to construct continuous time series spanning 14 to ca. 2ka BP. Given the proximity of the lakes, it is assumed that both were subjected to the same climatic forcing over this time. Accordingly, the first goal of this study was to consider these two multiproxy datasets in concert to yield an integrated paleoclimate record for this region. Close inspection of the records identified discrepancies indicating that the lakes responded to climate changes i...
Regulatory agencies are confronted with a daunting task of developing fish consumption advisories for a large number of lakes and rivers with little resources. A feasible mechanism to develop region-wide fish advisories is by using a process-based mathematical model. One model of...
2010-01-01
The Nebraska Sand Hills are a distinctive eco-region in the semi-arid Great Plains of the western United States. The water table underlying the Sand Hills is part of the High Plains/Ogallala aquifer, an important water resource for the central Great Plains. Lake levels are affected directly by fluctuations in the water table, which is recharged primarily by local precipitation and responds quickly to climatically induced changes in regional water balance. Instrumental records are available for only 50100years, and paleolimnological data provide important insights into the extremes and variability in moisture balance over longer time scales. A set of 69 lakes from across Nebraska was used to establish a statistical relationship between diatom community composition and water depth. This...
The EPA Region VII Superfund office and the EPA National Risk Management Research Laboratory (NRMRL) Mine Waste Technology Program (MWTP)have been conducting a field scale technology demonstration of an in situ treatment of the Anchor Hill Pit Lake at the Gilt Edge Mine Superfund...
Numerical simulation of the paleohydrology of glacial Lake Oshkosh, eastern Wisconsin, USA
2008-01-01
Proglacial lakes, formed during retreat of the Laurentide ice sheet, evolved quickly as outlets became ice-free and the earth deformed through glacial isostatic adjustment. With high-resolution digital elevation models (DEMs) and GIS methods, it is possible to reconstruct the evolution of surface hydrology. When a DEM deforms through time as predicted by our model of viscoelastic earth relaxation, the entire surface hydrologic system with its lakes, outlets, shorelines and rivers also evolves without requiring assumptions of outlet position. The method is applied to proglacial Lake Oshkosh in Wisconsin (13,600 to 12,900cal yr BP). Comparison of predicted to observed shoreline tilt indicates the ice sheet was about 400m thick over the Great Lakes region. During ice sheet recession, each...
2010-01-01
A frequency-domain electromagnetic (FDEM) survey can be used to select locations for the more quantitative and labor-intensive electrical resistivity surveys. The FDEM survey rapidly characterized the groundwater-flow directions and configured the saline plumes caused by evaporation from several groundwater-dominated lakes in the Nebraska Sand Hills, USA. The FDEM instrument was mounted on a fiberglass cart and towed by an all-terrain vehicle, covering about 25km/day. Around the saline lakes, areas with high electrical conductivity are consistent with the regional and local groundwater flow directions. The efficacy of this geophysical approach is attributed to: the high contrast in electrical conductivity between various groundwater zones; the shallow location of the saline zones; minima...
2010-01-01
Several natural and anthropogenic tracers have been used to evaluate groundwater residence time within a karstic limestone aquifer in southeastern New Mexico, USA. Natural groundwater discharge occurs in the lower Pecos Valley from a region of karst springs, wetlands and sinkhole lakes at Bitter Lakes National Wildlife Refuge, on the northeast margin of the Roswell Artesian Basin. The springs and sinkholes are formed in gypsum bedrock that serves as a leaky confining unit for an artesian aquifer in the underlying San Andres limestone. Because wetlands on the Refuge provide habitat for threatened and endangered species, there is concern about the potential for contamination by anthropogenic activity in the aquifer recharge area. Estimates of the time required for groundwater to travel throu...
1992-01-01
Preindustrial and present-day lake water pH, acid neutralizing capacity (ANC), total monomeric aluminum Al(sub m), and dissolved organic carbon (DOC) were inferred from the species composition of diatom and chrysophyte microfossils in the tops (present-day inferences) and bottoms (pre-1850 inferences) of sediment cores collected from a statistically selected set of Adirondack lakes. Results from the study lakes were extrapolated to a predefined target population of 675 low-alkalinity Adirondack region lakes. Estimates of preindustrial to present-day changes in lake water chemistry show that approximately 25-35% of the target population has acidified. The magnitude of acidification was greatest in the low-alkalinity lakes of the southwestern Adirondacks, an area with little geological ability to neutralize acidic deposition and receives the highest annual ...
We collected samples from apparently healthy geese in the Playa Lakes Region (USA) during the winters of 2000a??01 and 2001a??02 to determine whether carriers of Pasteurella multocida, the bacterium that causes avian cholera, were present in wild populations. With the use of methods developed in laboratory challenge trials (Samuel et al., 2003a) and a serotype-specific polymerase chain reaction method for identification of P. multocida serotype 1, we found that a small proportion of 322 wild birds (
Preindustrial and present-day lake water pH, acid neutralizing capacity (ANC), total monomeric aluminum Al(sub m), and dissolved organic carbon (DOC) were inferred from the species composition of diatom and chrysophyte microfossils in the tops (present-day inferences) and bottoms (pre-1850 inferences) of sediment cores collected from a statistically selected set of Adirondack lakes. Results from the study lakes were extrapolated to a predefined target population of 675 low-alkalinity Adirondack region lakes. Estimates of preindustrial to present-day changes in lake water chemistry show that approximately 25-35% of the target population has acidified. The magnitude of acidification was greatest in the low-alkalinity lakes of the southwestern Adirondacks, an area with little geological ability to neutralize acidic deposition and receives the highest annual average rainfall in the region. The authors estimate that approximately 80% of the target population lakes with present-day measured pH = or < 5.2 and 30-45% of lakes with pH between 5.2 and 6.0 have undergone large declines in pH and ANC, and concomitant increases in Al(sub m). Estimated changes in (DOC) were small and show no consistent pattern in the acidified lakes. The study provides the first statistically based regional evaluation of the extent of lake acidification in the Adirondacks.
1992-01-01
Preindustrial and present-day lake water pH, acid neutralizing capacity (ANC), total monomeric aluminum Al(sub m), and dissolved organic carbon (DOC) were inferred from the species composition of diatom and chrysophyte microfossils in the tops (present-day inferences) and bottoms (pre-1850 inferences) of sediment cores collected from a statistically selected set of Adirondack lakes. Results from the study lakes were extrapolated to a predefined target population of 675 low-alkalinity Adirondack region lakes. Estimates of preindustrial to present-day changes in lake water chemistry show that approximately 25-35% of the target population has acidified. The magnitude of acidification was greatest in the low-alkalinity lakes of the southwestern Adirondacks, an area with little geological ability to neutralize acidic deposition and receives the highest annual average rainfall in the region. The authors estimate that approximately 80% of the target population lakes with present-day measured pH = or < 5.2 and 30-45% of lakes with pH between 5.2 and 6.0 have undergone large declines in pH and ANC, and concomitant increases in Al(sub m). Estimated changes in (DOC) were small and show no consistent pattern in the acidified lakes. The study provides the first statistically based regional evaluation of the extent of lake acidification in the Adirondacks.
Use of remotely sensed data to estimate the flow of water to a playa lake
2006-01-01
The presence of water on Rosamond lake presents potential operational hazards and environmental issues for Edwards Air Force Base (EAFB). This research tests the utility of threshold precipitation in predicting inundation of Rosamond lake. Arcview v.3.2, with the ESRI extension `watershed delineator' and detailed field investigations were used to delineate the watershed and determine elevation-bounded intervals based on soil types and vegetation types and densities. The natural resource conservation service curve number approach was used to estimate the initial abstraction of precipitation, infiltration, runoff, and estimate the threshold depth of precipitation. Climatic data from the western regional climate center and remotely sensed data from the USA Army Corps of Engineers Cold Regions...
1992-01-01
Preindustrial and present day lake water pH, acid neutralizing capacity (ANC), total monomeric aluminum and dissolved organic carbon (DOC) were inferred from the species composition of diatom and chrysophyte microfossils in the tops (present day inferences) and bottoms (pre-1850s inferences) of sediment cores collected from a statistically selected set of Adirondack lakes. Results from the study lakes were extrapolated to a predefined target population of 675 low-alkalinity Adirondack region lakes. Estimates of preindustrial to present day changes in lake water chemistry show that ca 25-35% of the target population has acidified. The magnitude of acidification was greatest in the low alkalinity lakes of the southwestern Adirondacks, an area with little geological ability to neutralize acidic deposition and which receives the highest annual rainfall in the region. It is estimated that ca 80% of the target population lakes with present day measured pH[>=]5.2 and 30-45% of lakes with pH between 5.2 and 6.0 have undergone large declines in pH and ANC, and concommitant increases in Al. Estimated changes in DOC were small and show no consistent pattern in the acidified lakes. 84 refs., 8 figs., 4 tabs.
Ecological consequences of early Late Pleistocene megadroughts in tropical Africa
2007-10-16
Full Text Available.Extremely arid conditions in tropical Africa occurred in several discrete episodes between 135 and 90 ka, as demonstrated by lake core and seismic records from multiple basins [Scholz CA, Johnson TC, Cohen AS, King JW, Peck J, Overpeck JT, Talbot MR, Brown ET, Kalindekafe L, Amoako PYO, et al. (2007) Proc Natl Acad Sci USA 104:16416–16421]. This resulted in extraordinarily low lake levels, even in Africa's deepest lakes. On the basis of well dated paleoecological records from Lake Malawi, which reflect both local and regional conditions, we show that this aridity had severe consequences for terrestrial and aquatic ecosystems. During the most arid phase, there was extremely low pollen production and limited charred-particle deposition, indicating insufficient vegetation to maintain substantial fires, and the Lake Malawi watershed experienced cool, semidesert conditions (<400 mm/yr precipitation). Fossil and sedimentological data show that Lake Malawi itself, currently 706 m deep, was reduced to an ≈125 m deep saline, alkaline, well mixed lake. This episode of aridity was far more extreme than any experienced in the Afrotropics during the Last Glacial Maximum (≈35–15 ka). Aridity diminished after 95 ka, lake levels rose erratically, and salinity/alkalinity declined, reaching near-modern conditions after 60 ka. This record of lake levels and changing limnological conditions provides a framework for interpreting the evolution of the Lake Malawi fish and invertebrate species flocks. Moreover, this record, coupled with other regional records of early Late Pleistocene aridity, places new constraints on models of Afrotropical biogeographic refugia and early modern human population expansion into and out of tropical Africa.
2008-01-01
It is widely recognized that wetlands, especially those rich in organic matter and receiving appreciable atmospheric mercury (Hg) inputs, are important sites of methylmercury (MeHg) production. Extensive wetlands in the southeastern United States have many ecosystem attributes ideal for promoting high MeHg production rates. However, relatively few mercury cycling studies have been conducted in these environments. We conducted a landscape scale study examining Hg cycling in coastal Louisiana (USA) including four field trips conducted between August 2003 and May 2005. Sites were chosen to represent different ecosystem types, including: a large shallow eutrophic estuarine lake (Lake Pontchartrain), three rivers draining into the lake, a cypress-tupelo dominated freshwater swamp, and six emergent marshes ranging from a freshwater marsh dominated by Panicum ...
2010-01-01
This study utilizes Landsat TM, ASTER and Synthetic Aperture Radar (SAR)-derived DEMs in conjunction with Geographic Information Systems (GIS) in order to reevaluate previously-published interpretations of glacial landforms in and around Devil's Lake State Park, south-central Wisconsin, USA. Devil's Lake sits in a gorge carved into the southern flank of a doubly-plunging syncline known as the Baraboo Hills through which the Wisconsin or some other river flowed prior to the last ice age. During the last glacial maximum about 18,000B.P., an outlet glacier of the Laurentide Ice Sheet called the Green Bay Lobe extended southward into south-central Wisconsin and left behind extensive glacial landforms such as moraines, drumlins and eskers. During advance of the Green Bay Lobe into the region, D...
Climate change in the Tahoe basin: regional trends, impacts and drivers
2010-01-01
The purpose of this study was to quantify the decadal-scale time trends in air temperature, precipitation phase and intensity, spring snowmelt timing, and lake temperature in the Tahoe basin, and to relate the trends to large-scale regional climatic trends in the western USA. Temperature data for six long-term weather stations in the Tahoe region were analyzed for trends in annual and monthly means of maximum and minimum daily temperature. Precipitation data at Tahoe City were analyzed for trends in phase (rain versus snow), decadal standard deviation, and intensity of rainfall. Daily streamflow data for nine gaging stations in and around the Tahoe basin were examined for trends in snowmelt timing, by two methods, and an existing record for the temperature of Lake Tahoe was updated. The re...
FACTORS AFFECTING ENHANCED MERCURY BIOACCUMULATION IN INLAND LAKES OF ISLE ROYALE NATIONAL PARK, USA
Recent results have shown that 6 of the 43 inland lakes of Isle Royale National Park, the largest island in Lake Superior, contain northen pike with mercury concentrations exceeding health conxumption advisory levels (
This presentation will include a discussion of the application of the Lake Michigan Ecosystem Model (LM-Eco Model) for investigation of spatial and temporal trends of aquatic invasive species in Lake Michigan, USA....
2010-01-01
Records from lake sediment cores are critical for assessing the relative stability of climate and ecosystems over the Holocene. Duck Lake in south-central Lower Michigan, USA, was the focus of a study that identified how changes in the geochemical variables in lake sediments relate to variations in regional climate and local land use during the Holocene. More than 8.5m of lacustrine sediment were recovered using Livingston and freeze corers and analyzed for organic carbon, inorganic (carbonate) carbon, total nitrogen, and trace metals. Repeating packages of sediment (110cm thick) that grade from light (inorganic carbon-rich) to dark (organic carbon-rich) were found from the surface to a depth of about 8m. Variations in the high-resolution gray scale data from core X-radiographs ar...
Crystalline rocks of the Lake Superior region, United States. Part 2
1983-10-01
This report is a compendium of the available information on exposed crystalline rocks in the Lake Superior region (Wisconsin, Minnesota, and the Upper Peninsula of Michigan). This volume contains maps of the geology of the Lake Superior region, the tectonics of the region, and the distribution of crystalline rock bodies in the region. 16 references.
2007-01-01
Torpedograss, Panicum repens L., is an adventive, rhizomatous grass species that has become an invasive weed of terrestrial, wetland, and aquatic environments in tropical and subtropical regions worldwide. Until recently, strategies for controlling torpedograss in the USA have focused almost exclusively on mechanical and chemical methods, either alone or in combination, with varied results. A survey of the arthropods and nematodes currently associated with the plant in Lake Okeechobee, Florida, was conducted as part of a feasibility study to determine whether torpedograss is an appropriate target for a classical biological control program. Overall, approximately 4,000 arthropods and 400 nematode specimens were collected. Sweep, clipped vegetation, and soil core samples were dominated by representatives of the arthropod orders Hemiptera, Hymenoptera, ...
Lakes are abundant landforms and important ecosystems in Alaska, but are unevenly distributed on the landscape with expansive lake-poor regions and several lake-rich regions. Such lake-rich areas are termed lake districts and have landscape characteristics that can be considered distinctive in similar respects to mountain ranges. In this report, we explore the nature of lake-rich areas by quantitatively identifying Alaska's lake districts, describing and comparing their physical characteristics, and analyzing how Alaska lake districts are naturally organized and correspond to climatic and geophysical characteristics, as well as studied and managed by people. We use a digital dataset (National Hydrography Dataset) of lakes greater than 1 hectare, which includes 409,040 individual lakes and represents 3.3 percent of the land-surface area of Alaska.
2003-04-01
Low ratios of N:P and low underwater irradiance control dominance of cyanobacteria in a subtropical lake. - A long-term (28-year) data set was used to investigate historical changes in concentrations of phosphorus (P), nitrogen (N), N:P ratios, and Secchi disk transparency in a shallow subtropical lake (Lake Okeechobee, Florida, USA). The aim was to evaluate changes in the risk of N{sub 2}-fixing cyanobacterial blooms, which have infrequently occurred in the lake's pelagic zone. Predictions regarding bloom risk were based on previously published N:P ratio models. Temporal trends in the biomass of cyanobacteria were evaluated using phytoplankton data collected in 1974, 1989-1992, and 1997-2000. Concentrations of pelagic total P increased from near 50 {mu}g l{sup -1} in the mid-1970s to over 100 {mu}g l{sup -1} in the late 1990s. Coincidentally, the total N:P (mass) ratio decreased from 30:1 to below 15:1, and soluble N:P ratio decreased from 15:1 to near 6:1, in the lake water. Published empirical models predict that current conditions favor cyanobacteria. The observations confirm this prediction: cyanobacteria presently account for 50-80% of total phytoplankton biovolume. The historical decrease in TN:TP ratio in the lake can be attributed to a decreased TN:TP ratio in the inflow water and to a decline in the lake's assimilation of P, relative to N. Coincident with these declines in total and soluble N:P ratios, Secchi disk transparency declined from 0.6 m to near 0.3 m, possibly due to increased mineral turbidity in the lake water. Empirical models predict that under the turbid, low irradiance conditions that prevail in this lake, non-heterocystous cyanobacteria should dominate the phytoplankton. Our observations confirmed this prediction: non-N{sub 2}-fixing taxa (primarily Oscillatoria and Lyngbya spp.) typically dominated the cyanobacteria community during the last decade. The only exception was a year with very low water levels, when heterocystous N{sub 2}-fixing Anabaena became dominant. In the near-shore regions of this shallow lake, low N:P ratios potentially favor blooms of N{sub 2}-fixing cyanobacteria, but their occurrence in the pelagic zone is restricted by low irradiance and lack of stable stratification.
1992-10-01
In this report, the mechanism of forming acid rain in the atmosphere and the process of its fall to ground, the mechanism of withering forests by acid substances, and the process of acidifying lakes and marshes are explained. Moreover, the monitoring networks for acid rain and the countermeasures are described. Acid rain is the pollution phenomena related to all environment, that is, atmosphere, hydrosphere, soilsphere, biosphere and so on, and it is a local environmental pollution problem, and at the same time, an international, global environmental pollution problem. In Japan, acid rain has fallen, but the acidification of lakes and marshes is not clear, and the damage to forests is on small scale. However in East Asia region, the release of sulfur oxides and nitrogen oxides is much, and the increase of the effects of acid rain is expected. It is necessary to devise the measures for preventing the damage due to acid rain. The global monitoring networks of World Meteorological Organization and United Nations Environment Program, and those in Europe, USA and Japan are described. The monitoring of acid rain in Japan is behind that in Europe and USA. (K.I.).
AN UPDATE ON MERCURY LOADINGS, TRANSPORT, AND FATE IN LAKE MICHIGAN
Mr. Rygwelski will present the results of a screening model to address the sources, transport, and fate of mercury from the Lake Michigan Mass Balance Study. The Lake Michigan Mass Balance Study is being spearheaded by the USEPA Great Lakes National Program Office, Region V, and ...
2009-01-01
This study compares and contrasts the dynamics of phytoplankton, zooplankton, and nutrients in two of the largest shallow lakes in the USA (Lake Apopka, Florida) and Europe (Lago Trasimeno, Umbria, Italy) and considers particularly the biomass ratio of zooplankton to phytoplankton (BZ:BP) in relation to nutrient levels and in the context of data from other subtropical and temperate lakes. Lake Apopka is hypereutrophic with higher concentrations of total phosphorus (TP), nitrogen (TN), and nearly an order of magnitude higher BP than Lago Trasimeno. However, combined data from the two lakes can be fit to a single loglog regression model that explains 72% of the variability in BP based on TP. In contrast, BZ has a significant positive loglog relationship with TP only for Lago Trasimeno,...
2010-01-01
Lakes with complex morphologies and with different geologic and land-use characteristics in their sub-watersheds could have large differences in natural and anthropogenic chemical inputs to sub-basins in the lake. Lake Mead in southern Nevada and northern Arizona, USA, is one such lake. To assess variations in chemical histories from 1935 to 1998 for major sub-basins of Lake Mead, four sediment cores were taken from three different parts of the reservoir (two from Las Vegas Bay and one from the Overton Arm and Virgin Basin) and analyzed for major and trace elements, radionuclides, and organic compounds. As expected, anthropogenic contaminant inputs are greatest to Las Vegas Bay reflecting inputs from the Las Vegas urban area, although concentrations are low compared to sediment quality gui...
The paper is part of the variability study component of the Paleoecological Investigation of Recent Lake Acidification I (PIRLA I) Project. The study was designed to assess the variability in diatom and chrysophyte assemblages within a lake, and the variability associated with enumerating inferring pH from these assemblages. The results presented in the paper serve as a partial basis for assessing the uncertainty associated with the diatom and chrysophyte analyses of all PIRLA I study lakes. A major conclusion of the study is that a single sediment core can adequately represent the overall trends that have occurred in a lake.
1991-01-01
The paper is part of the variability study component of the Paleoecological Investigation of Recent Lake Acidification I (PIRLA I) Project. The study was designed to assess the variability in diatom and chrysophyte assemblages within a lake, and the variability associated with enumerating inferring pH from these assemblages. The results presented in the paper serve as a partial basis for assessing the uncertainty associated with the diatom and chrysophyte analyses of all PIRLA I study lakes. A major conclusion of the study is that a single sediment core can adequately represent the overall trends that have occurred in a lake.
Borax Lake, a thermal lake confined within a biomorphic mound, Pueblo Valley, Oregon, USA
2010-01-01
Relations among geothermal system dynamics, evolution of an 8-m thick biomorphic mound, and requirements to protect critical habitat of Gila boraxobius, a fish protected under the Endangered Species Act of 1973, were explored at Borax Lake, a shallow thermal lake in the tectonically active northwestern Basin-and-Range Province. Neutral pH, thermal water at ~105^oC discharges within a carrot-shaped vent at a depth of 29m and rapidly mixes within the vent and lake which is mostly
Aerosol extinction profile over the river Volga along the path Moscow-Nizniy Novgorod-Moscow
1994-12-31
The experimental data of the backscatter coefficient profile and aerosol pollution over the river Volga along the path Moscow-Nizniy Novgorod-Moscow obtained with the eye-safe backscatter compact lidar during the complex ecological expedition on the board ship ``Ilia Repin`` 28 June--7 July 1993 are presented. The authors detected the visible and invisible aerosols layers and smoke plume over industrial and ship chimneys. The data obtained in similar conditions allowed them to find out a pollution-free regions. These regions, such as the village Ples, with a clear atmosphere placed far from towns or industrial areas are considered as a base or background ones for an aerosol pollution degree estimation within industrial centers and over the. Plesheevo Lake near the Russian-USA ecological station are presented.
In this first large-scale study of mercury (Hg) in Lake Mead, USA, the nation's largest man- made reservoir, total-Hg concentrations were determined in the skeletal muscle of 339 fish collected during the Fall of 1998 and the Spring of 1999. Five species of fish representing ...
LAKE MICHIGAN MASS BALANCE PROJECT: ATRAZINE MODELLING RESULTS
The triazine herbicide, atrazine, is used worldwide to control broadleaf and grassy weeds in agricultural regions. Atrazine is extensively used for corn crops in the midwestern US, the Great Lakes region, and in the Lake Michigan basin and has been cited as an emerging pollutant ...
Development of realistic lake resource management strategies that have utility across diverse geopolitical areas is undoubtedly a difficult task. A regional approach, the aquatic ecoregion approach, is employed to examine spatial patterns in ambient phosphorus (TP) levels, secchi...
Glacial distribution and mass balance in the Yarlung Zangbo River and its influence on lakes
2010-01-01
Glaciers in the Yarlung Zangbo River witness severe glacial retreat nowadays, which gives important influence on lake processes in the region. We have studied glacial distribution, glacial mass balance and found large deficit in glacial mass and its impact in the region. Our study also integrated the variation in glacial-fed lakes of the Nam Co and Ranwu Lake, and presented an initial assessment of the impact of glacial mass balance on lakes. The study has shown a significant contribution of glacial melting to recent lake expansion and lake level rising.
Landscape-Based Assessment of Human Disturbance for Michigan Lakes
2010-01-01
Assessment of lake impairment status and identification of threats type and source is essential for protection of intact, enhancement of modified, and restoration of impaired lakes. For regions in which large numbers of lakes occur, such assessment has usually been done for only small fractions of lakes due to resource and time limitation. This study describes a process for assessing lake impairment status and identifying which human disturbances have the greatest impact on each lake for all lakes that are 2ha or larger in the state of Michigan using readily available, georeferenced natural and human disturbance databases. In-lake indicators of impairment are available for only a small subset of lakes in Michigan. Using statistical relationships between the in-lake indicators and land...
1995-01-01
The present report describes the results of research carried out following the Chernobyl accident to analyse the behaviour of radionuclides in some Italian lakes. The following lacustrine systems were examined: volcanic lakes Bolsena, Bracciano and Vico (central Italy) and lake Como (north Italy) whose drainage area is located in the Alpine region. The average residence times of 137Cs in water of volcanic lakes are much higher than the radionuclide residence time in lake Como. As quantitative analyses can show, the differences between the mean water retention times of the examined lakes do not suffice to explain this occurrence. Some peculiar seasonal effects (thermal stratification of water and ice/snow melting in lake drainage area) and high sedimentation rates are responsible of 137Cs efficient removal from water of lake Como
Historical trace metal loading to a large river recorded in the sediments of Lake St. Croix, USA
2010-01-01
The global cycling of anthropogenic trace metals intensified during the twentieth century, impacting aquatic systems throughout the world. There are, however, few quantitative records showing the history of this contamination in large rivers. Here we present a well-dated sedimentary record of trace metal accumulation in Lake St. Croix, a natural riverine lake on the St. Croix River (Minnesota and Wisconsin, USA), revealing the history of heavy metal inputs to the river over the past 200years. Concentrations of Hg, Pb, Ag, Cd, Cr and Zn and stable Pb isotopes were measured in eight 210Pb-dated sediment cores collected from profundal depositional areas throughout the lake. Time trends of trace metal concentrations and accumulation rates differed greatly between the upper lake (above Valley...
2005-01-01
Abstract 1 One proposed approach to improving biological control of bark beetles (Coleoptera: Scolytidae; alt. Curculionidae: Scolytinae) is to manipulate predator movement using semiochemicals. However, selective manipulation is impeded by attraction of both predators and pests to bark beetle pheromones. 2 The primary bark beetle affecting pine plantations in Wisconsin, U.S.A., is the pine engraver, Ips pini (Say). Other herbivores include Ips grandicollis (Eichhoff) and Dryophthorus americanus Bedel (Curculionidae). The predominant predators are the beetles Thanasimus dubius (Cleridae) and Platysoma cylindrica (Histeridae). 3 We conducted field assays using two enantiomeric ratios of ipsdienol, and frontalin plus a-pinene. Ipsdienol is the principal pheromone component of I. pini, and fr...
Predation history and vulnerability: Conservation of the stickleback adaptive radiation
2010-01-01
Recent adaptive radiations offer special insight into the processes that generate biodiversity. The loss of unique members of such radiations undermines their collective evolutionary potential, as well as the ability of scientists to compare divergent populations, thereby devaluing the entire radiation as a system of study. To illustrate our case, we consider the adaptive radiation of the threespine stickleback fish (Gasterosteus aculeatus) in light of anthropogenic threats. Specifically, we consider the effects of stocking with rainbow trout, Onchorynchus mykiss, on populations of stickleback in lakes of two types in the Cook Inlet Region of Alaska, USA: (1) those in which salmonids are native and (2) those historically devoid of predatory fish. Many populations in this second class exhib...
2005-01-01
Abstract: Evaluating bird population trends requires baseline data. In North America the earliest population data available are those from the late 1960s. Forest conditions in the northern Great Lake states (U.S.A.), however, have undergone succession since the region was originally cut over around the turn of the twentieth century, and it is expected that bird populations have undergone concomitant change. We propose pre-Euro-American settlement as an alternative baseline for assessing changes in bird populations. We evaluated the amount, quality, and distribution of breeding bird habitat during the mid-1800s and early 1990s for three forest birds: the Pine Warbler ( Dendroica pinus), Blackburnian Warbler ( D. fusca), and Black-throated Green Warbler ( D. virens). We constructed models of...
2005-01-01
Ascertaining the relative effects of factors such as weather and predation on population dynamics, and determining the time scales on which they operate, is important to our understanding of basic ecology and pest management. In this study, we sampled the pine engraver Ips pini (Say) (Coleoptera: Scolytidae) and its predominant predators Thanasimus dubius (F.) (Coleoptera: Cleridae) and Platysoma cylindrica (Paykull) (Coleoptera: Histeridae) in red pine plantations in Wisconsin, USA, over 2years. We sampled both the prey and predators using flight traps baited with the synthetic aggregation pheromone of I. pini. Flight models were constructed using weather variables (temperature and precipitation), counts of bark beetles and their predators, and temporal variables to incorporate possible...
2010-01-01
Over the past century, annual snowfall has increased across the `snow-belt' region of the Upper Peninsula of Michigan, yet total annual precipitation has not changed, with potential impacts on hydrological processes and ecosystem composition. Using an integrated hydrochemical approach, we characterized groundwater discharge and quantified the contribution of snow- and rain-derived waters to groundwater for an old-growth riparian area within the Huron Mountains in northern Michigan. We then quantified the relative contribution of lateral, hillslope-derived groundwater and upstream lake water to streamwater, and the extent of hyporheic zone expansion and contraction during one growing season. During a period of above-average snowfall, yet below average growing season precipitation, 80% of th...
Extent, pattern, and multifunctionality of treed habitats on farms in Vermont, USA
2010-01-01
Agroecosystems can serve as multifunctional landscapes when treed habitats such as woodlots, hedgerows, riparian buffers, windbreaks, and orchards, are conserved on farms. We investigated the extent, pattern, and multifunctionality of on-farm treed habitats for 16 Vermont farms in the Lamoille watershed of the Lake Champlain Basin. The site was selected because the land use pattern is representative of the region, containing a mixture of agriculture and forest in different habitat types. We used a GIS-based approach to delineate treed habitats on farms and conducted semi-structured interviews with farmers to explore their perception of the functions of treed habitats. Through an evaluation of the relationship between farm characteristics and spatial attributes of treed habitats, we found f...
2009-01-01
The main limiting factor on the accuracy of Interferometric SAR measurements (InSAR) comes from phase propagation delays through the troposphere. The delay can be divided into a stratified component, which correlates with the topography and often dominates the tropospheric signal, and a turbulent component. We use Global Atmospheric Models (GAM) to estimate the stratified phase delay and delay-elevation ratio at epochs of SAR acquisitions, and compare them to observed phase delay derived from SAR interferograms. Three test areas are selected with different geographic and climatic environments and with large SAR archive available. The Lake Mead, Nevada, USA is covered by 79 ERS1/2 and ENVISAT acquisitions, the Haiyuan Fault area, Gansu, China, by 24 ERS1/2 acquisitions, and the Afar region,...
The Upper Great Lakes workshop, sponsored by the U.S. Environmental Protection Agency (USEPA), was held at the University of Michigan in Ann Arbor, Michigan from 4-7 May 1998 to discuss some of the potential consequences of climate change in the Upper Great Lakes region (e.g., Mi...
Application of Satellite Observations to Manage Natural Disasters in the Lake Victoria Basin
Lake Victoria, the second largest fresh water lake in the Eastern part of Africa is a vital natural resource for the economic well being and prosperity of over 30 million people located in riparian regions of Uganda, ...
Recent studies (Levitus et al., .2000) suggest a warming of the world ocean over the past 50 years. This could be occurring in the Great Lakes also but thermal measurements are lacking. Historical trends in natural phenomena, such as the duration of ice cover on lakes, provide in...
Modeling pyrite oxidation in arid environments
1998-09-15
Understanding future pit lake water quality has become an important element in permitting open pit mines, due to the potential long-term water quality impacts on ecological receptors. Quantifying pyrite oxidation kinetics is anintegral part of this analysis. To date, constraints resulting from low moisture content in the arid regions of the southwestern USA that host many large, disseminated deposits have not been considered. In this study, laboratory humidity cells routinely used to simulate pyrite reactivity were found to overestimate pyrite oxidation rates in arid environments by a factor of {gt} 2 compared to the same material emplaced in the field. Increasing particle size also resulted in decreasing reactivity, with 16-64 mm diameter grains {lt} 50% as reactive as 4-16 mm diameter grains. A pyrite oxidation model that incorporates both fracture and porous media pyrite oxidation using site-specific data, e.g. wall rock geometry, moisture content, etc., was developed to simulate wall rock reactivity in arid environments. The results demonstrated a 3-fold reduction in oxidized wall rock thickness in arid environments compared to assumptions of constant 100% moisture, with a concomitant reduction in solute loading to the incipient pit lake. 25 refs., 6 figs.
2010-01-01
We assessed options for mitigating greenhouse gas emissions from electricity generation in the US Great Lakes States, a region heavily dependent on coal-fired power plants. A proposed 600MW power plant in northern Lower Michigan, USA provided context for our evaluation. Options to offset fossil CO2 emissions by 20% included biomass fuel substitution from (1) forest residuals, (2) short-rotation woody crops, or (3) switchgrass; (4) biologic sequestration in forest plantations; and (5) geologic sequestration using CO2 capture. Review of timber product output data, land cover data, and expected energy crop productivity on idle agriculture land within 120km of the plant revealed that biomass from forestry residuals has the potential to offset 6% and from energy crops 27% of the annual fossil f...
Further analysis of respiration in a North American lake ecosystem
1984-01-01
High respiratory quotients (RQ = DIC accumulation/DO uptake) in a marl lake-ecosystem (Lawrence Lake, MI, USA) were caused by extra DIC produced by anaerobic respiration at the bottom and an exaggeration of the proportions of anaerobic DIC by oxygenic photosynthesis in the water column during winter stratification. At Lawrence Lake the areal RQ's used to compare North American lake ecosystems by Rich and Devol (1978) were distorted by photosynthesis in the water column both summer and winter, but were not inflated by re-dissolved carbonate sediments. The fundamental RQ was a better estimate of the RQ of lake-ecosystem DIC regeneration than the areal RQ.
2007-01-01
In order to assess biological recovery from acidification, as well as differences in community composition between manipulated and un-manipulated lakes, a study was conducted to investigate the long-term changes in the phytoplankton communities of four lakes (Clearwater Lake, Middle Lake, Hannah Lake, and Lohi Lake) located within 15 km of Sudbury, Ontario, an area significantly damaged by sulphur dioxide and metals from local smelter emissions. The study compared changes in the phytoplankton communities in the lakes over the last two to three decades, and evaluated them against data collected since 1980 from reference lakes within the same biogeographic region but beyond the influence of the Sudbury smelters. The paper provided background on emissions and biological recovery in the area as well as on the results of the study. It was concluded that there was evidence of ...
1994-01-01
A monitoring program was initiated to assess long-term trends in the composition of benthic invertebrate communities in acid-stressed softwater lakes. This report summarizes results of the spring 1988 survey of benthic invertebrates in the littoral zones of 12 headwater lakes. The sampling protocol employed a kick-and-sweep technique to collect benthos at five sites in the nearshore area of the littoral zone of each lake. Water chemistry was sampled at a mid-lake reference station and at each of the five littoral benthic sites in each lake. The report also summarizes the local geological characteristics and the climate and vegetation of the region, and maps are provided of the study lakes along with details of the sampling sites and an inventory of the fish species present in each lake.
2005-01-01
Paleohydrology studies at Mathews Pond and Whitehead Lake in northern Maine revealed synchronous changes in lake levels from about 12,00014C yrs BP to the present. We analyzed gross sediment structure, organic and carbonate content, mineral grain size, and macrofossils of six cores from each of the two lakes, and obtained 72 radiocarbon dates. Interpretation of this paleo-environmental data suggests that the late-glacial and Younger Dryas climate was dry, and lake levels were low. Early Holocene lake levels were considerably higher but declined for an interval from about 8000 to 720014C yrs BP. Sediment of both lakes contains evidence of a dry period at 740014C yrs BP (8200cal yr). Lake levels of both sites declined abruptly about 480014C yrs BP and remained low until 300014C y...
Ecosystem Science (Program Description)
... the Caribbean, and the Antarctic, including deserts, estuaries, lakes, prairies, various forests ... Wilson Boulevard, Arlington, Virginia 22230, USA Tel: (703) 292-5111, FIRS: (800) 877-8339 | TDD ...
ENANTIOSELECTIVITY IN THE BIODEGRADATION OF PCB ATROPISOMERS
Microcosms inoculated with sediment from two locations in a contaminated reservoir, Lake Hartwell, SC, USA, degraded certain PCB atropisomers enantioselectively while other atropisomers were degraded in racemic proportions. The microcosms were spiked with either 234-236 PCB (PCB...
2010-09-01
Reproductive abnormalities in alligators exposed to contaminants in Lake Apopka, Florida, USA represent a clear example of endocrine disruption in wildlife. Several of these contaminants that...Full Text Available
Ionic alkylleads in herring gulls from the Great Lakes region
Herring gull (Larus argentatus) tissues, collected from various breeding colonies in the Great Lakes, were examined to determine alkyllead levels and possible alkyllead sources into the Great Lakes region. Ionic trialkyl- and dialkyllead species (R/sub 3/Pb/sup +/, R/sub 2/Pb/sup 2 +/; R = Me, Et) were quantitated by gas chromatography-atomic absorption spectrometry. The extraction procedure was tested at trace levels (3-4 ppb as Pb) with four domestic chicken (Gallus domesticus) tissues. Trimethyllead was found in two avian species and all examined tissues. Methyllead levels frequently exceeded ethyllead levels with no direct automotive source. Correlation between alkyllead levels in herring gull tissue and lake sediment lead levels suggests possible methylation but not ethylation of inorganic lead. The methyllead concentration trend in gull tissues. Lake Ontario > Lake Huron approx. = Lake Erie > Lake Superior, was opposite to the ethyllead concentration trend, Lake Superior > Lake Huron > Lake Erie approx. = Lake Ontario. 40 references, 3 figures, 7 tables.
Ionic alkylleads in herring gulls from the Great Lakes region
1986-10-01
Herring gull (Larus argentatus) tissues, collected from various breeding colonies in the Great Lakes, were examined to determine alkyllead levels and possible alkyllead sources into the Great Lakes region. Ionic trialkyl- and dialkyllead species (R/sub 3/Pb/sup +/, R/sub 2/Pb/sup 2 +/; R = Me, Et) were quantitated by gas chromatography-atomic absorption spectrometry. The extraction procedure was tested at trace levels (3-4 ppb as Pb) with four domestic chicken (Gallus domesticus) tissues. Trimethyllead was found in two avian species and all examined tissues. Methyllead levels frequently exceeded ethyllead levels with no direct automotive source. Correlation between alkyllead levels in herring gull tissue and lake sediment lead levels suggests possible methylation but not ethylation of inorganic lead. The methyllead concentration trend in gull tissues. Lake Ontario > Lake Huron approx. = Lake Erie > Lake Superior, was opposite to the ethyllead concentration trend, Lake Superior > Lake Huron > Lake Erie approx. = Lake Ontario. 40 references, 3 figures, 7 tables.
1984-01-01
A field program was conducted in 1980 and 1981 on three lakes in Kejimkujik National Park, Nova Scotia, to study plankton-water chemistry relationships in a region of potential acid precipitation stress. The phytoplankton of Kejimkujik Lake was dominated by diatoms. Pebbleloggitch Lake was dominated by chlorophytes and chrysophytes, and Beaverskin Lake was dominated by cyanophytes. Kejimkujik Lake had the highest total algal cell volume per liter, and Pebbleloggitch Lake the lowest. Rotifer populations composed the majority of the zooplankton communities, while the crustacean zooplankton were dominated by the acid-tolerant copepod Diaptomus minutus. Kejimkujik Lake had the lowest zooplankton biomass and Pebbleloggitch Lake the highest zooplankton biomass per cu m. A pattern of highest algal density in Beaverskin Lake, but highest zooplankton density in Pebbleloggitch Lake emerged in both years. This is likely an effect of abundant, but unsuitable food (blue-green algae) in Beaverskin Lake and important detrital food resources in Pebbleloggitch Lake in both years. Multiple regression analysis of water chemistry variables with plankton species produce many significant effects, but failed to show clear patterns. Cause and effect relationships in aquatic ecosystems are poorly delineated by such techniques. 37 references, 2 figures, 7 tables.
Biological studies of atmospheric deposition impact on biota in Kola North Mountain Lakes, Russia
1996-12-31
In the framework of the AL:PE projects, biological studies of phyto-, zooplankton and zoobenthos communities of a small lakes situated in Chuna tundra and Chibiny mountains in Murmansk region were performed in 1993-1995. The lakes are the typical oligotrophic mountain lakes. In the Chibiny lake phytoplankton were presented mostly by species from rock catchment area. Summer phytoplankton state in the lakes showed no acidification in 1993-1995. However, the great number dead cells of acid tolerance diatoms, such as Tabellaria flocculosa found in the Chuna lake in summer period, may indicate a presence of acid episodes. Zooplankton of the lakes is typical for high oligotrophic mountain lakes. However, lack of the acid sensitive daphniidae cladocerans seems to be a result of acidification effects. There were no significant relationships between benthic invertebrates species composition and present water acidity of the lakes. The typical for mountain lakes taxa (Prodiamesinae chironomids, stone flies and mayflies) were found in lake shore and streams. Despite the only little evidence of damage in biota, the further biological studies would be useful for long-term monitoring of the mountain lakes.
The Lake Superior region (Wisconsin, the Upper Peninsula of Michigan, and Minnesota) contains 41 Precambrian crystalline rock complexes comprising 64 individual but related rock bodies with known surface exposures. Each complex has a map area greater than 78 km/sup 2/. About 54% of the rock complexes have areas of up to 500 km/sup 2/, 15% fall between 500 km/sup 2/ and 1000 km/sup 2/, 19% lie between 1000 km/sup 2/ and 2500 km/sup 2/, and 12% are over 2500 km/sup 2/. Crystalline rocks of the region vary widely in composition, but they are predominantly granitic. Repeated thermo-tectonic events have produced early Archean gneisses, migmatites, and amphibolites with highly tectonized fabrics that impart a heterogeneous and anisotropic character to the rocks. Late Archean rocks are usually but not invariably gneissose and migmatitic. Proterozoic rocks of the region include synorogenic (foliated) granitic rocks, anorogenic (non-foliated) granites, and the layered gabbro-anorthosite-troctolite intrusives of the rift-related Keweenawan igneous activity. Compared with the Archean rocks of the region, the Proterozoic bodies generally lack highly tectonized fabrics and have more definable contacts where visible. Anorogenic intrusions are relatively homogeneous and isotropic. On the basis of observed geologic characteristics, postorogenic and anorogenic crystalline rock bodies located away from recognized tectonic systems have attributes that make them relatively more desirable as a possible site for a nuclear waste repository in the region. This study was conducted at Argonne National Laboratory under the sponsorship of the US Department of Energy through the Office of Crystalline Repository Development at Battelle Memorial Institute, Columbus, Ohio. 84 references, 4 figures, 3 tables.
The Lake Superior region (Wisconsin, the Upper Peninsula of Michigan, and Minnesota) contains 41 Precambrian crystalline rock complexes comprising 64 individual but related rock bodies with known surface exposures. Each complex has a map area greater than 78 km/sup 2/. About 54% of the rock complexes have areas of up to 500 km/sup 2/, 15% fall between 500 km/sup 2/ and 1000 km/sup 2/, 19% lie between 1000 km/sup 2/ and 2500 km/sup 2/, and 12% are over 2500 km/sup 2/. Crystalline rocks of the region vary widely in composition, but they are predominantly granitic. Repeated thermo-tectonic events have produced early Archean gneisses, migmatites, and amphibolites with highly tectonized fabrics that impart a heterogeneous and anisotropic character to the rocks. Late Archean rocks are usually but not invariably gneissose and migmatitic. Proterozoic rocks of the region include synorogenic (foliated) granitic rocks, anorogenic (non-foliated) granites, and the layered gabbro-anorthosite-troctolite intrusives of the rift-related Keweenawan igneous activity. Compared with the Archean rocks of the region, the Proterozoic bodies generally lack highly tectonized fabrics and have more definable contacts where visible. Anorogenic intrusions are relatively homogeneous and isotropic. On the basis of observed geologic characteristics, postorogenic and anorogenic crystalline rock bodies located away from recognized tectonic systems have attributes that make them relatively more desirable as a possible site for a nuclear waste repository in the region. This study was conducted at Argonne National Laboratory under the sponsorship of the US Department of Energy through the Office of Crystalline Repository Development at Battelle Memorial Institute, Columbus, Ohio. 84 references, 4 figures, 3 tables.
1984-01-01
The Lake Superior region (Wisconsin, the Upper Peninsula of Michigan, and Minnesota) contains 41 Precambrian crystalline rock complexes comprising 64 individual but related rock bodies with known surface exposures. Each complex has a map area greater than 78 km/sup 2/. About 54% of the rock complexes have areas of up to 500 km/sup 2/, 15% fall between 500 km/sup 2/ and 1000 km/sup 2/, 19% lie between 1000 km/sup 2/ and 2500 km/sup 2/, and 12% are over 2500 km/sup 2/. Crystalline rocks of the region vary widely in composition, but they are predominantly granitic. Repeated thermo-tectonic events have produced early Archean gneisses, migmatites, and amphibolites with highly tectonized fabrics that impart a heterogeneous and anisotropic character to the rocks. Late Archean rocks are usually but not invariably gneissose and migmatitic. Proterozoic rocks of the region include synorogenic (foliated) granitic rocks, anorogenic (non-foliated) granites, and the layered gabbro-anorthosite-troctolite intrusives of the rift-related Keweenawan igneous activity. Compared with the Archean rocks of the region, the Proterozoic bodies generally lack highly tectonized fabrics and have more definable contacts where visible. Anorogenic intrusions are relatively homogeneous and isotropic. On the basis of observed geologic characteristics, postorogenic and anorogenic crystalline rock bodies located away from recognized tectonic systems have attributes that make them relatively more desirable as a possible site for a nuclear waste repository in the region. This study was conducted at Argonne National Laboratory under the sponsorship of the US Department of Energy through the Office of Crystalline Repository Development at Battelle Memorial Institute, Columbus, Ohio. 84 references, 4 figures, 3 tables.
Biomagnification of persistent organic contaminants in Great Slave Lake food webs
1994-12-31
Great Slave Lake is a large, subarctic lake which receives the majority of its water from the Slave, Peace, and Athabasca Rivers watershed. Increased development in the southern region of the watershed may provide a significant source of organic contaminants to the lake in addition to contaminants entering the lake via direct atmospheric deposition. Here the authors report the results of a study comparing organic contaminant concentrations in lake trout, burbot, and whitefish collected near the Slave River outflow and in a region of Great Slave Lake which is believed to be minimally affected by the Slave River. They also use stable isotope analyses to infer spatial differences in fish feeding habits between the two regions of the lake and to investigate how food habits may affect organic contaminant biomagnification. Finally, the authors compare their Great Slave Lake data with studies conducted from other regions of the Arctic and subarctic. This allows them to infer how the Slave River inflow may affect organic contaminant concentrations and biomagnification in the Great Slave Lake ecosystem.
Whole-lake burdens and spatial distribution of cadmium in sediments of Wisconsin seepage lakes, USA
Cadmium was quantified in the surface sediments of six seepage lakes ranging from 8 to 70 ha in surface area, 6 to 20 m in maximum depth, 5.2 to 7.0 in mean epilimnetic pH, and 1.7 to 6.8 mg.L-1 in dissolved organic carbon. Within each lake, dry-weight concentrations of cadmium (range, 0.02-7.17 mu g.g(-1)) were positively correlated with volatile matter content of the sediments, which increased with water depth. Volumetric concentrations (i.e., mass per volume of met sediment) were correlated with water depth in only one lake, and they more accurately represented the spatial distribution of sedimentary cadmium within the lakes. Analysis of sediment cores from two of the lakes indicated that surface sediments were enriched with cadmium. The source of cadmium and the within-lake processes controlling deposition to the sediments were presumably similar among the lakes, as demonstrated by the strong correlation between lake area and whole-lake burdens of cadmium in the surface sediments (range, 625-5785 g/lake). Hence, cadmium in these lakes appears to be derived largely from atmospheric deposition. When normalized for lake area, cadmium burdens in the surface sediments ranged from 62 to 92 g.ha(-1) and were strongly correlated with dissolved organic carbon, but not with lake pH, which suggests a link between the transport of cadmium and organic matter to the sediments.
2008-01-01
Summary 1. Ecosystems can enhance the biodiversity of adjacent ecosystems through subsidies of prey, nutrients and also habitat. For example, trees can fall into aquatic ecosystems and act as a subsidy that increases aquatic habitat heterogeneity. This habitat subsidy is vulnerable in lakes where anthropogenic development of shorelines coincides with a thinning of riparian forests and the removal of these dead trees (termed coarse woody debris: CWD). How the disruption of this subsidy affects lake ecosystems is not well understood. 2. We performed a whole ecosystem experiment on Little Rock Lake, a small (18 ha), undeveloped, and unfished lake in Vilas County, WI, U.S.A., that is divided into two similar-sized basins by a double poly-vinyl chloride curtain that prevents both fish and water...
Origin of drumlins on the floor of Lake Ontario and in upper New York State
2007-01-01
Upper New York State, USA contains one of the largest drumlin fields (12,000km2) on the North America continent consisting of some 10,000 drumlins located between Lake Ontario in the north and the Finger Lakes; drumlin-like bedforms have also recently been discovered in deep water (200m) on the nearby floor of the Rochester Basin in Lake Ontario. The New York State drumlin field was produced under the Laurentide Ice Sheet 18,000years ago when it extended southwards to terminate against the Allegheny Plateau. Outcrops of drumlin cores exposed by erosion along the Lake Ontario shoreline provide windows into the stratigraphy and sedimentology of the northern part of the field. Sedimentological description of 10 coastal drumlin cores, combined with quantitative morphometric analysis o...
Anthropogenic impacts recorded in recent sediments from Otisco Lake, New York, USA
2010-01-01
Geochemical analysis of 210Pb-dated sediment cores from Otisco Lake (New York) combined with analysis of recent land cover change in the watershed revealed the history of land use change, lake management, and industrial pollution since European settlement in the northeastern US. Clearance of forestland for agriculture characterized the early settlement era that was marked in the Otisco Lake sediments by a decline in organic carbon (OC) and OC:N ratios, which indicate a change in the sources of organic matter to the lake. Agricultural land use reached its greatest areal extent in the Otisco watershed around 1900, followed by field abandonment and reforestation over the last century. In the 1920s sediment accumulation rates began to increase coincident with residential development along the ...
Program Overview Information for Launch Binders
NCI Community Cancer Centers Program Program Overview Our Lady of the Lake Regional Medical Center 1 A. Name and location of hospital: Our Lady of the Lake Regional Medical Center, 5000 Hennessey Blvd., Baton Rouge, LA 70808 B. Name
EPA-ORD GREAT LAKES INVASIVE SPECIES INITIATIVE: MONITORING AND MODELING
ORD research presented will inform developing Regional efforts to establish early detection/rapid response strategies for the Great Lakes coastal region, and may assist development of a national model....
A REVIEW OF THE LEECHES (ANNELIDA:HIRUDINEA) IN THE GREAT LAKES REGION
The leeches of the Great Lakes region compose a significant part of the North American freshwater fauna in numbers of species (43 taxa) and are considered biologically important as parasites and predators. This report presents the taxonomy and identification of these for the Grea...
Atmospheric deposition of cadmium in the northeastern USA
2007-06-15
Lake sediment cores, dated by {sup 210}Pb, were collected from Spectacle Pond (SP), Massachusetts, and Side Pistol Lake (SPL) and Sargent Mountain Pond (SMP), Maine, USA. SP is a kettle seepage lake in granitic sand and gravel. SMP is a drainage pond on granite with little soil in the small watershed. SPL is a drainage lake in granitic till. The three cores were analyzed for total Cd. For SP and SMP, maximum concentrations of 1.7 and 3.9 mg/kg, four and eight times background concentrations, respectively, occur in the late 1960s. Accumulation rates reach maximum values concurrently with concentration and are 0.054 and 0.016 {mu}g/cm{sup 2}/a, more than 10 times background. Concentration and accumulation rate age relationships in SMP and SP are similar for background values, timing and magnitude of increase to peak values, and the decrease nearly to background values since about 1975. The chemical response to decreased atmospheric deposition lags in SPL sediment. Kettle-like lakes more clearly indicate changes in atmospheric deposition than drainage lakes.
The authors measured variability in the composition of diatom and chrysophyte assemblages, and the pH inferred from these assemblages, in sediment samples from Big Moose Lake, in the Adirondack Mountains of New York. eplicate samples were analyzed from (1) a single sediment. core...
1982-01-01
The population dynamics of aplanktonic rotifer (Polyarthra vulgaris) were examined in a brown water, acid lake in northern Michigan, USA. Predation by Chaoborus punctipennis and low food (Navicula spp. and Cyclotella spp.) concentrations were the main factors limiting P. vulgaris populations of all factors examined. The data presented here support a hypothesis for zooplankton limitation by an invertebrate predator.
Moving the coal: a Seaway Review supplement on coal transportation
A number of short articles deal with the movement of coal on the Great Lakes: major harbors and terminal facilities with loading and unloading capacity (this means good economics, especially with no demurrage charges); transhipment capability; major coal deposits and railways in the USA and their interrelationships with Great Lakes and Seaway traffic; projected coal traffic on particular routes; and export feasibility studies and terminal storage (including environmental effects). (LTN)
Moving the coal: a Seaway Review supplement on coal transportation
A number of short articles deal with the movement of coal on the Great Lakes: major harbors and terminal facilities with loading and unloading capacity (this means good economics, especially with no demurrage charges); transhipment capability; major coal deposits and railways in the USA and their interrelationships with Great Lakes and Seaway traffic; projected coal traffic on particular routes; and export feasibility studies and terminal storage (including environmental effects). (LTN)
Coastal wetlands of the Laurentian Great Lakes (USA and Canada) are among the most biologically diverse ecosystems of the world. However, since the 1970s the presence of opportunistic plant species such as common reed (Phragmites australis [Cav.] Steudel) have increased in Great ...
The Sulphur Bank Mercury Mine, located on the shore of Clear Lake, Lake County, California, is a potential source for a modern-day mercury flux into the local aquatic ecosystem. Surface mining created the Herman Pit, a 9.3 ha open pit with a depth
FACTORS AFFECTING ENHANCED MERCURY BIOACCUMULATION IN INLAND LAKES OF ISLE ROYALE NATIONAL PARK, USA
We investigated factors causing mercury (Hg) concentrations in northern pike to exceed the consumption advisory level in some inland lakes of Isle Royale National Park. Using Hg-clean techniques, we collected water, zooplankton, macroinvertebrates, and fishes in 1998 and 1999 fro...
Modelling the effects of inflow parameters on lake water quality
2003-01-01
A one-dimensional lake water quality model which includes water temperature, phytoplankton, phosphorus as phosphate, nitrogen as ammonia, nitrogen as nitrate and dissolved oxygen concentrations, previously calibrated for Lake Calhoun (USA) is applied to Uokiri Lake (Japan) for the year 1994. The model simulated phytoplankton and nutrient concentrations in the lake from July to November. Most of the water quality parameters are found to be the same as for Lake Calhoun. To predict probable lake water quality deterioration from algal blooming due to increased nutrient influx from river inflow, the model was run for several inflow water conditions. Effects of inflow nutrient concentration, inflow volume, inflow water temperatures are presented separately. The effect of each factor is considered in isolation although in reality more than one factor can change simultaneously. From the results it is clear that inflow nutrient concentration, inflow volume and inflow water temperature show very regular and reasonable impacts on lake water quality. Publisher: Springer Other identifier: swin:7304 Language: English Source: Environmental Modeling and Assessment, Vol. 8, no. 2 (June 2003), p. 63-70 Rights: Copyright © 2003 Kluwer Academic Publishers.
Whole lake selective withdrawal experiment to control harmful cyanobacteria in an urban impoundment
2009-01-01
Different environmental conditions support optimal growth by Aphanizomenon and Microcystis in Ford Lake, Michigan, USA, based on weekly species biovolume and water chemistry measurements from June through October 2005-2007. Experimental withdrawal of hypolimnetic water through the outlet dam was conducted in 2006, with 2005 and 2007 acting as control years, to test theory regarding management of nuisance and toxic cyanobacteria. The dynamics of Aphanizomenon and Microcystis blooms in Ford Lake appear to be driven largely by NO3- concentrations, with higher levels shifting the advantage to Microcystis (P
2010-01-01
In inland waters, transparent exopolymer particles (TEP) can affect carbon export and sequestration in sediments with consequences for lake C budgets. We measured TEP concentration in 32 lakes from two contrasting lake districts covering wide ranges in biological and chemical characteristics. North temperate lakes, located in a wet region, have low to moderate ionic strength and low to high dissolved organic carbon with corresponding variation in color (light absorbance). Mediterranean lakes located in a semiarid region were characterized by high ionic strength and high concentrations of dissolved organic carbon but low color. TEP concentrations were large relative to the living portion of the particulate organic carbon pool in both Mediterranean (36%) and north temperate (33%) lakes. TEP ...
Metal Status of Soils and Plants Irrigated with Water from Lake Iznik, Turkey
2009-01-01
Lake Iznik, located in the southeast part of the Marmara region in Turkey, is considered the largest lake in the region. Soil pollution from irrigation with lake water has become an important concern for arable lands surrounding the lake. Therefore, a study was conducted to investigate trace element contamination of soils and plants irrigated with water from the lake, which has been polluted with industrial and municipal wastes. Eleven different crops grown in 30 different horticultural fields, consistently irrigated with lake water, were studied. To determine pollutant concentrations, soils, plants, and water were sampled and analyzed for both total and extractable iron (Fe), manganese (Mn), zinc (Zn), copper (Cu), cobalt (Co), nickel (Ni), chromium (Cr), lead (Pb), and cadmium (Cd). Iron...
Whole-lake burdens and spatial distribution of cadmium in sediments of Wisconsin seepage lakes, USA
2000-06-01
Cadmium was quantified in the surface sediments of six seepage lakes ranging from 8 to 70 ha in surface area, 6 to 20 m in maximum depth, 5.2 to 7.0 in mean epilimnetic pH, and 1.7 to 6.8 mg{sm_bullet}L{sup {minus}1} in dissolved organic carbon. Within each lake, dry-weight concentrations of cadmium were positively correlated with volatile matter content of the sediments, which increased with water depth. Volumetric concentrations were correlated with water depth in only one lake, and they more accurately represented the spatial distribution of sedimentary cadmium within the lakes. Analysis of sediment cores from two of the lakes indicated that surface sediments were enriched with cadmium. The source of cadmium and the within-lake processes controlling deposition to the sediments were presumably similar among the lakes, as demonstrated by the strong correlation between lake area and whole-lake burdens of cadmium in the surface sediments. Hence, cadmium in these lakes appears to be derived largely from atmospheric deposition. When normalized for lake area, cadmium burdens in the surface sediments ranged from 62 to 92 g{sm_bullet}ha{sup {minus}1} and were strongly correlated with dissolved organic carbon, but not with lake pH, which suggests a link between the transport of cadmium and organic matter to the sediments.
DEFINING REGIONAL POPULATIONS OF LAKES FOR THE ASSESSMENT OF SURFACE WATER QUALITY
Topographic maps are commonly used to define populations of lakes in regional surveys of surface water quality. o illustrate the effect of different maps on that process, we compared the lakes represented on the 1:250,000 scale maps used for the Northeast Region of the Eastern La...
The presentation slides include: The SPoRT Center, History and Future of SPoRT, Great Lakes Applications, Great Lakes Forecasting Issues, Applications to the WRF-EMS, Precipitation Science, Lake Effect ...
The presentation slides include: The SPoRT Center, History and Future of SPoRT, Great Lakes Applications, Great Lakes Forecasting Issues, Applications to the WRF-EMS, Precipitation Science, Lake Effect ...
1991-12-31
The amounts and concentration of radiocaesium in fishes and in lake water, taken from major lakes in the Varese region for the periods pre and post Chernobyl are reported. Some relationships are obtained which permit to forecast the intake on behalf of the fishes knowing the quantity of radioactivity entering into the lake bed. (15 tabs; 18 figs).
Large Water Management Projects and Schistosomiasis Control, Dongting Lake Region, China
2007-07-01
Full Text Available.Construction of the Three Gorges Dam across the Yangtze River will substantially change the ecology of the Dongting Lake in southern China. In addition, the Central and Hunan Provinces’ governmental authorities have instigated a Return Land to Lake Program that will extend the Dongting Lake surface area from the current 2,681 km
Lake Titicaca - Physics of an Inherited Hydropower Macroproject Proposal
2007-03-19
Shared almost evenly by Peru and Bolivia, Lake Titicaca is situated on an Altiplano endorheic region of the northern Andes Mountains. Rio Desaguadero is the lake only outlet. From 1908, several macro-engineers speculated on the creation of a second, completely artificial, outlet for Lake Titicaca freshwater. Here we reconsider several 20th Century macroproject proposals, with the goal of examining and enhancing this technically interesting South American 21st Century Macro-engineering inheritance.
A regional scale model for oxygen in lake hypolimnia.
2006-04-10
DescriptionThe concentration of oxygen in the water of lakes, especially in deeper water near the sediment, is one of the most important characteristics of a lake. It influences the type of chemical reactions that can occur and what animals live in the sediment, if any. The oxygen concentration may be used with other properties to measure the overall quality of lakes, something that is needed for the Water Framework Directive. The oxygen concentration can not be measured every two weeks or so in the many [continued...]
A method to predict streamflow for ungauged basins of the Mid-Atlantic Region, USA was applied to the Rappahannock watershed in Virginia, USA. The method separates streamflow time series into magnitude and time sequence components. It uses the regionalized flow duration curve (RF...
2010-01-01
Summary Polycyclic aromatic hydrocarbons (PAHs) are usually loaded through atmospheric deposition into a water body and eventually into sediments. We study the PAHs from a 22-cm sediment core collected from the subtropical Feitsui Reservoir in Taiwan, and find the PAHs deposition characteristics in the reservoir, the man-made water body, is different from those in natural water bodies. The surficial sedimentary PAH fluxes are significantly higher than those in the European high altitude mountain lakes and those in the northeastern USA urban/industrial lakes. However, the catchment-corrected PAH fluxes normalized by the ratios of the catchment area to the water surface area are comparable to those of remote lakes in Europe and USA, suggesting the sedimentary PAHs in the reservoir is fluvial...
2000-02-21
This document concerns the supply of 6000 cryogenic temperature sensors for the Large Hadron Collider. The Finance Committee is invited to agree to the negotiation of a contract with LAKE SHORE CRYOTRONICS, INC. (USA), without competitive tendering, for the supply of 6000 cryogenic temperature sensors for a total amount of 694 860 US dollars (1 081 500 Swiss francs), not subject to revision. The above amount in Swiss francs has been calculated using the rate of exchange stipulated in the tender. LAKE SHORE CRYOTRONICS, INC. has declared the following origin of the equipment relating to this adjudication proposal: USA-100%. The expenditure for the cryogenic temperature sensors will be reimbursed to CERN by the Department of Energy of the Government of the United States of America within the framework of the Accelerator Protocol to the Co-operation Agreement with the USA concerning their contribution towards the LHC machine.
Seismic-reflection profiles from Lake Wales, Blue Lake, Lake Letta, and Lake Apthorp located along the Lake Wales Ridge in central Florida provide local detail within the regional hydrogeologic framework as described by litho- and hydrostratigraphic cross sections. Lakes located with the mantled karst region have long been considered to be sinkhole lakes, originating from subsidence activity. High-resolution seismic- reflection data confirm this origin for these four lakes. The geologic framework of the Lake Wales Ridge has proven to be a suitable geologic setting for continuous high-resolution seismic-reflection profiling in lakes; however, the nature of the lake-bottom sediments largely controls the quality of the seismic data. In lakes with significant organic-rich bottom deposits, interpretable record was limited to areas where organic deposits were minimal. In lakes with clean, sandy bottoms, the seismic-reflection methods were highly successful in obtaining data that can be correlated with sublake subsidence features. These techniques are useful in examining sublake geology and providing a better understanding of how confining units are affected by subsidence in a region where their continuity is of significant importance to local lake hydrology. Although local geologic control around each lake generally corresponds to the regional geologic framework, local deviations from regional geologic trends occur in sublake areas affected by subsidence activity. Each of the four lakes examined represents a unique set of geologic controls and provides some degree of structural evidence of subsidence activity. Sublake geologic structures identified include: (1) marginal lake sediments dipping into bathymetric lows, (2) lateral discontinuity of confining units including sags and breaches, (3) the disruption and reworking of overlying unconsolidated siliciclastic sediments as they subside into the underlying irregular limestone surface, and (4) sublake regions where confining units appear to remain intact and unaffected by nearby subsidence activity. Each lake likely is underlain by several piping features rather than one large subsidence feature.
Holocene climate on the Modoc Plateau, northern California, USA: the view from Medicine Lake
2009-01-01
Medicine Lake is a small (165ha), relatively shallow (average 7.3m), intermediate elevation (2,036m) lake located within the summit caldera of Medicine Lake volcano, Siskiyou County, California, USA. Sediment cores and high-resolution bathymetric and seismic reflection data were collected from the lake during the fall of 1999 and 2000. Sediments were analyzed for diatoms, pollen, density, grain size (sand/mud ratio), total organic carbon (TOC), and micro-scale fabric analysis. Using both 14C (AMS) dating and tephrochronology, the basal sediments were estimated to have been deposited about 11,400calyear BP, thus yielding an estimated average sedimentation rate of about 20.66cm/1,000year. The lowermost part of the core (11,40010,300calyear BP) contains the transition fro...
1997-02-01
Contemporary phytoplankton and palaeolimnological studies were made of the algal responses to acidification and liming in three lakes in Halsingland, central Sweden (Njupfatet, Sjosjon, Djuptjarn). The pH inferences suggest that at least some lakes in this region are susceptible to atmospheric acidification. The response of the diatoms to liming is discussed, in particular the rapid expansion at Njupfatet, of Cyclotella glomerata, a diatom which was also present in Sjosjon for a period prior to acidification, and at other lakes in south-west Sweden. Possible reasons for the expansion of this small centric diatom are discussed.
Hierarchical models of very large problems, dilemmas, prospects, and an agenda for the future
Interdisciplinary approaches to the modeling of global problems are discussed in terms of multilevel cooperation. A multilevel regionalized model of the Lake Erie Basin is analyzed along with a multilevel regionalized ...
2010-01-01
Lakes are key sites for studying paleoclimates. Llancanelo Lake (southern Mendoza Province, western Argentina) is an endoreic, highly saline water body located in the southern extreme of a tectonic basin, the Central or Huarpes Depression. The lake is located between the Andean Cordillera, San Rafael Block and Payenia Volcanic Field. The lake evolved as a major regional depocenter during the Pliocene-Quaternary, hence it contains important thicknesses of intra and extra basinal clastic and evaporitic sediments mainly dominated by volcaniclastic products. The main conditioning factors in the lake evolution were arc and back-arc volcanism as well as climatic changes. Geomorphological and sedimentary evidence supports the hypothesis that the lake was in past times larger than in present days....
Laguna de Bay: Institutional development and change for lake basin management:
2006-01-01
Abstract Laguna de Bay is a large, shallow lake located near Manila, Philippines. The lake is drained by the Pasig River, which flows to Manila Bay. It periodically reverses direction, bringing saline water into this predominately freshwater body. The lake has historically been of great importance to locals who depend on it for fish and related livelihoods. Recently, it also has been considered a source of potable water for the Manila region. The intense land use in the watershed has caused enhanced siltation, and the lake has also been plagued by overfishing, intense aquaculture and water pollution from industrial and domestic sources. This paper overviews these issues and examines the role of the Laguna Lake Development Authority in developing and conserving the lake basin's resources. T...
Increase of urban lake salinity by road deicing salt
2008-01-01
Over 317,000 tonnes of road salt (NaCl) are applied annually for road deicing in the Twin Cities Metropolitan Area (TCMA) of Minnesota. Although road salt is applied to increase driving safety, this practice influences environmental water quality. Thirteen lakes in the TCMA were studied over 46months to determine if and how they respond to the seasonal applications of road salt. Sodium and chloride concentrations in these lakes were 10 and 25 times higher, respectively, than in other non-urban lakes in the region. Seasonal salinity/chloride cycles in the lakes were correlated with road salt applications: High concentrations in the winter and spring, especially near the bottom of the lakes, were followed by lower concentrations in the summer and fall due to flushing of the lakes by rainfa...
Evolution of supra-glacial lakes across the Greenland Ice Sheet
2009-01-01
We used 268 cloud-free Moderate-resolution Imaging Spectroradiometer (MODIS) images from 2003 and 20052007 to study the seasonal evolution of supra-glacial lakes in three different regions of the Greenland Ice Sheet. Lake area estimates were obtained by developing an automated classification method for their identification based on 250m resolution MODIS surface reflectance observations. Widespread supra-glacial lake formation and drainage is observed across the ice sheet, with a 23week delay in the evolution of total supra-glacial lake area in the northern areas compared to the south-west. The onset of lake growth varies by up to one month inter-annually, and lakes form and drain at progressively higher altitudes during the melt season. A positive correlation was found between th...
2008-01-01
Abstract The temporal and spatial variations in the rate of sedimentation and sediment resuspension in Lake Rehtijarvi (southern Finland) were studied by sediment traps deployed in the stratifying and non-stratifying regions of the lake. Both the gross sedimentation rate and the resuspension rate recorded by near-bottom traps were significantly higher in the stratifying region (
The focus of this report is on regional distribution of the herpetofauna of the Lake Michigan Drainage Basin. The introduction includes a brief discussion of plant communities and their associated herpetofauna, and the importance of hibernacula and migration routes. Some aspects of the status, distribution, habitat, and life history of the amphibians and reptiles of the Basin are described in an annotated checklist. Special attention is given to uncommon and endangered species. Species range is shown on distribution maps.
1976-07-01
The focus of this report is on regional distribution of the herpetofauna of the Lake Michigan Drainage Basin. The introduction includes a brief discussion of plant communities and their associated herpetofauna, and the importance of hibernacula and migration routes. Some aspects of the status, distribution, habitat, and life history of the amphibians and reptiles of the Basin are described in an annotated checklist. Special attention is given to uncommon and endangered species. Species range is shown on distribution maps.
An evaluation of the Regional Mercury Cycling Model (R-MCM, a steady-state fate and transport model used to simulate mercury concentrations in lakes) is presented based on its application to a series of 91 lakes in Vermont and New Hampshire. Visual and statistical analyses are pr...
The effects of species immigrations and changing conditions on isoetid communities
2009-01-01
Historical data from the 1930s were compared with new data gathered during the 2000s to evaluate the effects of increased numbers of larger stature submersed species (both elodeids and characeans) on resident isoetid communities. The cover and species richness of submersed species were assessed in 23 seepage lakes in northwestern Wisconsin, USA, using randomly located 1mx1m plots. Water clarity, conductivity and residential land use were determined on a whole-lake basis and the sediment type and water depth were recorded at each plot. The probability of elodeids or characeans occurring in isoetid plots increased with the number of elodeids and characeans gained by a lake since the 1930s, with additions ranging from two to 15 species per lake. However, not all species were equally likely to...
2010-01-01
We present a 3-year study of concentrations and sulfur isotope values (d34S, D33S, and D36S) of sulfur compounds in the water column of Fayetteville Green Lake (NY, USA), a stratified (meromictic) euxinic lake with moderately high sulfate concentrations (12-16mM). We utilize our results along with numerical models (including transport within the lake) to identify and quantify the major biological and abiotic processes contributing to sulfur cycling in the system. The isotope values of sulfide and zero-valent sulfur across the redox-interface (chemocline) change seasonally in response to changes in sulfide oxidation processes. In the fall, sulfide oxidation occurs primarily via abiotic reaction with oxygen, as reflected by an increase in sulfide d34S at the redox interface. Interestingly, S...
2009-01-01
Turquoise Lake is a water-supply reservoir located north of the historic Sugarloaf Mining district near Leadville, Colorado, USA. Elevated water levels in the reservoir may increase flow of low-quality water from abandoned mine tunnels in the Sugarloaf District and degrade water quality downstream. The objective of this study was to understand the sources of water to Dinero mine drainage tunnel and evaluate whether or not there was a direct hydrologic connection between Dinero mine tunnel and Turquoise Lake from late 2002 to early 2008. This study utilized hydrograph data from nearby draining mine tunnels and the lake, and stable isotope (d18O and d2H) data from the lake, nearby draining mine tunnels, imported water, and springs to characterize water sources in the study area. Hydrograph r...
2008-01-01
Summary Salinity in estuaries is highly variable due to river discharge, tidal motion, and winds. Information on the spatial and temporal changes in salinity can provide important ecological indications, but accurate monitoring of the space-time variability for a large estuary is often costly and time-consuming. This study applied remote sensing techniques to develop a salinity prediction model for Lake Pontchartrain, a large estuarine lake located in the Northern Gulf of Mexico, USA. "Ground truth" salinity was measured along two transects across the lake and near the shoreline. Water-leaving reflectance from the measurement locations was extracted from Landsat Thematic Mapper (TM) images pre-processed through "banding" noise reduction and radiometrical correction approaches. Ordinary lea...
2010-01-01
Polybrominated diphenyl ethers in Lake Ontario watershed sediments were assessed for benthic bioavailability through the use of biota-sediment accumulation factors. Sediments from lake and Rochester Harbor (lower Genesee River) areas were investigated. Congeners 47, 66, 85, 99 and 100 were detected in tissues of the oligochaete Lumbriculus variegatus. Biota-sediment accumulation factors ranged from 3.95 (congener 154) to 19.5 (congener 28) and were higher at the Lake Ontario area. The lower biota-sediment accumulation factors for the Rochester Harbor sediment may result from a higher fraction of black carbon generally expected in highly urbanized rivers. Degree of bromination may reduce bioavailability.
2008-01-01
Despite the ecological and economic importance of Great Salt Lake (GSL), little is known about the input and biogeochemical cycling of nutrients and trace elements in the lake. In response to increasing public concern regarding anthropogenic inputs to the GSL ecosystem, the US Geological Survey (USGS) and US Fish and Wildlife Service (USFWS) initiated coordinated studies to quantify and evaluate the significance of nutrient and Hg inputs into GSL. A 6 per mille decrease in delta15N observed in brine shrimp (Artemia franciscana) samples collected from GSL during summer time periods is likely due to the consumption of cyanobacteria produced in freshwater bays entering the lake. Supporting data collected from the outflow of Farmington Bay indicates decreasing trends in delta15N in particulate organic matter (POM) during ...
2008-01-01
Despite the ecological and economic importance of Great Salt Lake (GSL), little is known about the input and biogeochemical cycling of nutrients and trace elements in the lake. In response to increasing public concern regarding anthropogenic inputs to the GSL ecosystem, the US Geological Survey (USGS) and US Fish and Wildlife Service (USFWS) initiated coordinated studies to quantify and evaluate the significance of nutrient and Hg inputs into GSL. A 6permil decrease in d15N observed in brine shrimp (Artemia franciscana) samples collected from GSL during summer time periods is likely due to the consumption of cyanobacteria produced in freshwater bays entering the lake. Supporting data collected from the outflow of Farmington Bay indicates decreasing trends in d15N in particulate organic mat...
Evaluation and management of non-point source pollutants in the Lake Tahoe watershed
1994-12-31
Lake Tahoe, California-Nevada, one of the most oligotrophic lakes in the world, is experiencing decreased water clarity and increased periphyton growth, and water supplies drawing from the lake are experiencing increased algal-related tastes and odors. The growth of algae in Lake Tahoe is primarily limited by the nitrogen (nitrate and ammonia) loads to the lake, which have been increasing over the years. The nitrogen that is causing the increased fertilization of the lake is primarily derived from atmospheric sources through precipitation onto the lake`s surface. A potentially highly significant source of atmospheric nitrogen in the Lake Tahoe Basin is automobile, bus, and truck engine exhaust discharge of NOx. The fertilization of lawns and other shrubbery, including golf courses, within the Lake Tahoe Basin is also leading to significant growths of attached algae in the nearshore waters of the lake. The fertilizers are transported via groundwater to the nearshore areas of the lake. In order to prevent further deterioration of Lake Tahoe`s eutrophication-related water quality, there is immediate need to control atmospheric input of nitrate and ammonia to the lake`s surface, and to control use of fertilizers on lawns, shrubbery, and golf courses in the watershed. The states of California and Nevada, and the Tahoe Regional Planning Authority need to focus considerable attention on the determination of whether restricting NOx emissions from vehicular traffic within the basin would have a significant beneficial impact on Lake Tahoe`s water clarity.
1997-09-01
Sediments cores were collected from lakes in the Devils Lake Basin in North Dakota, USA, to determine if mercury (Hg) accumulation chronologies from sediment-core data are good indicators of variations in Hg accumulation rates in saline lakes. Sediment cores from Creel Bay and Main Bay, Devils Lakewere examined. The maximum Hg concentration in the Creel Bay core was 0.15 {mu}g/g at 8 to 9 centimetres. The maximum Hg concentration in the Main Bay core was 0.07 {mu}g/g at 5 to 7 centimetres. The general decreases in Hg concentrations with depth are attributed to historic variations in atmospheric Hg deposition rate. Hg stratigraphies combined with {sup 210}Pb and {sup 137}Cs dating analyses yield Hg chronologies that indicate a general increase in Hg accumulation rates in Devils Lake since the middle of the 19th century. Mean modern Hg accumulation rates in Creel Bay were 4.9 ng/cm{sup 2}/annum and rates in Main Bay were 1.8 ng/cm{sup 2}/annum. Mean preindustrial Hg accumulation rates in Creel Bay were 1.2 ng/m{sup 2}/annum and rates in Main Bay were 1.6 ng/cm{sup 2}/annum. Low Hg concentrations in recent sediments in the Devils Lake Basin, along with similarities in Hg accumulation rates between lakes in the Devils Lake Basin and other lakes in the northern interior of North America, indicate that local sources of Hg are not important. Results indicate that accurate Hg chronologies are discernible in sediment cores collected from saline lakes. However, spatial and temporal variations in lake level and water chemistry common to saline lakes make interpretation of radioisotopic and geochemical chronologies difficult. Hg geochemistry in Devils Lake is dynamic. The absolute amount of sediment transported to Devils Lake, along with the associated Hg and total organic carbon, and the distribution of sedimentation patterns in Devils Lake may be affected by changing lake levels. 29 refs., 8 refs., 3 tabs.
1993-05-01
Chemistry, stable isotope, and tritium contents of thermal/mineral waters in the Clear Lake region were used to evaluate conventional and hot dry rock (HDR) geothermal potential for electrical generation. Thermal/mineral waters of the Clear Lake region are broadly classified as thermal meteoric and connate types based on chemical and isotopic criteria. Ratios of conservative components such as B/Cl are extremely different among all thermal/mineral waters of the Clear Lake region except for clusters of waters emerging from specific areas such as the Wilbur Springs district and the Agricultural Park area south of Mt. Konocti. In contrast ratios of conservative components in large, homogeneous geothermal reservoirs are constant. Stable isotope values of Clear Lake region waters show a mixing trend between thermal meteoric and connate (generic) end-members. The latter end-member has enriched {delta}D as well as enriched {delta}{sup 18}O, from typical high-temperature geothermal reservoir waters. Tritium data indicate most Clear Lake region waters are mixtures of old and young fluid components. Subsurface equilibration temperature of most thermal/mineral waters of the Clear Lake region is {le}150{degree}C based on chemical geothermometers but it is recognized that Clear Lake region waters are not typical geothermal fluids and that they violate rules of application of many geothermometers. The combined data indicate that no large geothermal reservoir underlies the Clear Lake region and that small localized reservoirs have equilibration temperatures {le}150{degree}C (except for Sulphur Bank mine). HDR technologies are probably the best way to commercially exploit the known high-temperatures existing beneath the Clear Lake region particularly within and near the main Clear Lake volcanic field.
1989-01-01
The report examines the potential impact of acid precipitation on lacustrine birds in Quebec. The first report determines the composition of bird communities at lakes in regions with various levels of deposition and sensitivity. Visits were made to 146 lakes located in the most important Quebec biomes to count the birds and describe the morphometry, the water quality, biological factors, the riparian soils, and the aquatic and riparian vegetation. The second report describes the lake habitats and the potential effects of acidification on the habitats in the temperate zone and the semi-arctic zones of Quebec. The aquatic and riparian vegetation of 78 lakes in southern Quebec and 68 lakes in northern Quebec are briefly described and related to the regional characteristics of the environments in which they occur, the morphometry and water quality of the lakes, and the features of the riparian soils.
Paleohydrology of Lake Nhaucati (southern Mozambique), 400AD to present
2008-01-01
This paper investigates the correlations between lake level change, rainfall variability and general atmospheric forcing in southern Africa. The analysis of fossil diatom assemblages in a sediment sequence from the small, rain-fed Lake Nhaucati, southern Mozambique, is presented and discussed in relation to regional palaeoclimate data. The accumulation of organic sediments in Lake Nhaucati began 1,600years ago when the lake level was rising. Lithology and pollen suggest a low stand at 800AD, which correlates with other climate proxies from the summer rainfall region of southern Africa. The diatom assemblage suggests that lake levels were high between 900 and 1300AD, with shorter low stands at c.1100 and 1200AD. The period after 1400AD was marked by a slow rate of accumulation and...
EASTERN LAKE SURVEY - PHASE II QUALITY ASSURANCE REPORT
The Eastern Lake Survey - Phase II report describes and evaluates the quality assurance program employed during this study of regional surface water chemistry. The Quality Assurance Program was designed to ensure that all samples were collected and analyzed consistently, to verif...
2010-01-01
A diatom assemblage found in bottom sediments of mountain oligotrophic lakes in the Amguema River basin (Ervynaigytgyn, Matachingaigytgyn, Ekitiki) is presented for the first time. For each taxon, data on the occurrence in the Beringia region are given. Three new combinations are suggested.
A REGIONAL ECOLOGICAL ANALYSIS OF THE GREAT LAKES BASIN
The U.S. Environmental Protection Agency (EPA) and Natural Resources Canada: Canada Centre for Remote Sensing (CCRS) are conducting a cooperative research landscape ecological study of the Great Lakes Basin. The analyses will include the areas located along the border of the Unit...
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