Sample records for crust rainy lake

  1. Petrology of the Rainy Lake area, Minnesota, USA-implications for petrotectonic setting of the archean southern Wabigoon subprovince of the Canadian Shield (United States)

    Day, W.C.


    The Rainy Lake area in northern Minnesota and southwestern, Ontario is a Late Archean (2.7 Ga) granite-greenstone belt within the Wabigoon subprovince of the Canadian Shield. In Minnesota the rocks include mafic and felsic volcanic rocks, volcaniclastic, chemical sedimentary rocks, and graywacke that are intrucded by coeval gabbro, tonalite, and granodiorite. New data presented here focus on the geochemistry and petrology of the Minnesota part of the Rainy Lake area. Igneous rocks in the area are bimodal. The mafic rocks are made up of three distinct suites: (1) low-TiO2 tholeiite and gabbro that have slightly evolved Mg-numbers (63-49) and relatively flat rare-earth element (REE) patterns that range from 20-8 x chondrites (Ce/YbN=0.8-1.5); (2) high-TiO2 tholeiite with evolved Mg-numbers (46-29) and high total REE abundances that range from 70-40 x chondrites (Ce/YbN=1.8-3.3), and (3) calc-alkaline basaltic andesite and geochemically similar monzodiorite and lamprophyre with primitive Mg-numbers (79-63), enriched light rare-earth elements (LREE) and depleted heavy rare-earth elements (HREE). These three suites are not related by partial melting of a similar source or by fractional crystallization of a common parental magma; they resulted from melting of heterogeneous Archean mantle. The felsic rocks are made up of two distinct suites: (1)low-Al2O3 tholeiitic rhyolite, and (2) high-Al2O3 calc-alkaline dacite and rhyolite and consanguineous tonalite. The tholeiitic felsic rocks are high in Y, Zr, Nb, and total REE that are unfractionated and have pronounced negative Eu anomalies. The calcalkaline felsic rocks are depleted in Y, Zr, and Nb, and the REE that are highly fractionated with high LREE and depleted HREE, and display moderate negative Eu anomalies. Both suites of felsic rocks were generated by partial melting of crustal material. The most reasonable modern analog for the paleotectonic setting is an immature island arc. The bimodal volcanic rocks are

  2. Rainy Day Stocks

    DEFF Research Database (Denmark)

    Gormsen, Niels Joachim; Greenwood, Robin

    We study the good- and bad-times performance of equity portfolios formed on characteristics. Many characteristics associated with good performance during bad times—value, profitability, small size, safety, and total volatility—also perform well during good times. Stocks with characteristics...... generated during good times. We also show how an investor can build a “rainy day” portfolio that minimizes underperformance during bad times...

  3. That Rainy Day

    Institute of Scientific and Technical Information of China (English)



    Many things have happened since I began to remember things. Pleasant or sad, they've left some impressions on my mind. Some are fading from my memory while others are and will be remembered for ever as if they had happened yesterday, and the scene on that rainy day is just one of such memories. It was on July 7th, 1990, the first day of the 3-day college entrance examination. I got up early that morning, feeling so excited and nervous that I lost all my appetite. What's worse, it began raining, adding vexat...

  4. Ensamble de crustáceos bentónicos en un lago salino tropical Benthic crustaceans assemblage in a tropical, saline lake

    Directory of Open Access Journals (Sweden)

    Ma. del Carmen Hernández


    Full Text Available El presente trabajo reconoce la composición, estructura y distribución espacial del ensamble de crustáceos bentónicos de Alchichica, un lago salino tropical ubicado en el extremo oriental del altiplano mexicano. El lago presenta una riqueza taxonómica de crustáceos bentónicos compuesta por 1 anfípodo (Hyalella azteca, 1 isópodo (Caecidotea williamsi y 2 ostrácodos (Limnocythere inopinata y Candona sp.. Comparada con otros lagos tropicales, la riqueza de especies es reducida. A pesar de lo anterior, es importante mencionar el grado elevado de endemismo representado por C. williamsi, recientemente descrita para el lago Alchichica; adicionalmente, es factible que tanto Candona como H. azteca sean especies nuevas y endémicas del lago. Los crustáceos bentónicos se distribuyen desde la zona litoral hasta la zona más profunda del lago (62 m con abundancias y riqueza taxonómica variables. Los ostrácodos fueron los crustáceos que con mayor frecuencia se recolectaron en el lago, en la zona litoral, en el talud, y en la zona profunda de la que son habitantes exclusivos. Los anfípodos constituyeron el segundo grupo en abundancia de la zona litoral y talud y estuvieron ausentes en la zona profunda. Los isópodos sólo se encuentran asociados a los depósitos de tufa, hábitat característico del lago que se extiende a lo largo del talud, por lo que con las técnicas de muestreo tradicional empleadas en el presente estudio no fueron capturados. En este ensamble de crustáceos predominan las especies de desarrollo directo y con posiciones tróficas que incluyen componentes herbívoros (H. azteca, omnívoros (C. williamsi y bacterívoros (L. inopinata y Candona sp..This work acknowledges the composition, structure and spatial distribution of the benthic crustaceans assemblage of Alchichica, a tropical saline lake located in the easternmost portion of the Mexican highlands. The benthic crustaceans' assemblage was comprised by 1 amphipod

  5. Mafic granulite xenoliths in the Chilka Lake suite, Eastern Ghats Belt, India: evidence of deep-subduction of residual oceanic crust

    Directory of Open Access Journals (Sweden)

    S. Bhattacharya


    Full Text Available Granulite xenoliths preserve key geochemical and isotopic signatures of their mantle source regions. Mafic granulite and pyroxinite xenoliths within massif-type charnockitic rocks from the Eastern Ghats Belt have recently been reported by us. The mafic granulite xenoliths from the Chilka Lake granulite suite with abundant prograde biotite are geochemically akin to Oceanic Island Basalt (OIB. They can be distinguished from the hornblende-mafic granulite xenoliths with signatures of Arc-derived basalt occurring in the other suites of the Eastern Ghats Belt. These two groups of xenoliths in the Paleoproterozoic Eastern Ghats Province have quite distinct Nd-model ages- 1.9 Ga and 2.5 Ga respectively, which may be interpreted as their crustal residence ages. Strong positive Nb anomalies, indicating subducted oceanic crust in the source, LREE enrichment and strongly fractionated REE pattern are key geochemical signatures attesting to their origin as OIB-type magma. Also low Yb and Sc contents and high (La / YbN ratios can be attributed to melting in the presence of residual garnet and hence at great depths (> 80 km. The variable enrichment in radiogenic 87Sr, between 0.70052 and 0.71092 at 1.9 Ga and less radiogenic 143Nd between ε-1.54 and 7.46 are similar to those of the OIBs compared to MORBs. As OIBs commonly contain some recycled oceanic crust in their sources, we suggest that the residue of the oceanic crust from a previous melting event (~ 2.5 Ga that produced the Arc-derived basalts (protoliths of hornblende-mafic granulite xenoliths could have subducted to great depths and mechanically mixed with the mantle peridotite. A subsequent re-melting event of this mixed source might have occurred at ca. 1.9 Ga as testified by the crustal residence ages of the biotite-mafic granulite xenoliths of the Chilka Lake granulite suite.

  6. Distribuição vertical da comunidade fitoplanctônica do lago dos Tigres (Goiás, Brasil - DOI: 10.4025/actascibiolsci.v30i1.1446 Vertical distribution of phytoplankton communities in Tigres Lake (Goiás, Brazil during the rainy and dry seasons - DOI: 10.4025/actascibiolsci.v30i1.1446

    Directory of Open Access Journals (Sweden)

    Ina de Souza Nogueira


    Full Text Available O lago dos Tigres é um lago do tipo vale bloqueado, sendo que não foi registrado estudo evidenciando a distribuição vertical fitoplanctônica para esse tipo de lago; dessa forma, esta pesquisa assume um caráter pioneiro. Objetivou-se, nesse trabalho, o reconhecimento temporal e espacial dos padrões verticais de atributos da comunidade fitoplanctônica, detectar os grupos funcionais fitoplanctônicos dominantes e descritivos do sistema e relacioná-los com características limnológicas. O lago estudado foi caracterizado como polimítico quente, sendo que ocorreram eventuais estratificações térmicas nas estações de maior profundidade. Os períodos de seca e início de chuva apresentaram-se tanto limnologicamente (evidenciado pela ACP quanto biologicamente (observado pela ACC distintos. Os meses de seca apresentaram maiores concentrações de nutrientes e maiores transparências. Nesses meses, também foi registrado predomínio dos grupos funcionais Lo, Y , N e W1. Os meses de chuvas apresentaram maiores temperaturas e menores transparências, sendo que os grupos funcionais predominantes foram S1, T e N. Avaliando conjuntamente as características limnológicas, o biovolume e os grupos funcionais, pode-se concluir que o perfil vertical do lago dos Tigres é oligo-mesotróficoTigres Lake is a blocked valley lake, with no registered studies of phytoplankton vertical distribution for that lake type; as such, our work assumes a pioneering nature. The aim of this study was to recognize temporally and spatially the vertical patterns of phytoplankton community attributes, to detect the dominant and descriptive phytoplankton functional groups, and relate them to limnological characteristics. Tigres Lake was characterized as a warm polymictic lake, featuring occasional thermal stratification in deeper stations. The dry and early rainy seasons presented limnological (evidenced by PCA and biological (observed by CCA differences. The dry months

  7. SHRIMP-RG U-Pb isotopic systematics of zircon from the Angel Lake orthogneiss, East Humboldt Range, Nevada: Is this really archean crust? (United States)

    Premo, Wayne R.; Castineiras, Pedro; Wooden, Joseph L.


    New SHRIMP-RG (sensitive high-resolution ion microprobe-reverse geometry) data confirm the existence of Archean components within zircon grains of a sample from the orthogneiss of Angel Lake, Nevada, United States, previously interpreted as a nappe of Archean crust. However, the combined evidence strongly suggests that this orthogneiss is a highly deformed, Late Cretaceous monzogranite derived from melting of a sedimentary source dominated by Archean detritus. Zircon grains from the same sample used previously for isotope dilution-thermal ionization mass spectrometry (ID-TIMS) isotopic work were analyzed using the SHRIMP-RG to better define the age and origin of the orthogneiss. Prior to analysis, imaging revealed a morphological variability and intragrain, polyphase nature of the zircon population. The SHRIMP-RG yielded 207Pb/206Pb ages between ca. 2430 and 2580 Ma (a best-fit mean 207Pb/206Pb age of 2531 ± 19 Ma; 95% confidence) from mostly rounded to subrounded zircons and zircon components (cores). In addition, several analyses from rounded to subrounded cores or grains yielded discordant 207Pb/206Pb ages between ca. 1460 and ca. 2170 Ma, consistent with known regional magmatic events. All cores of Proterozoic to latest Archean age were encased within clear, typically low Th/U (206Pb/238U ages between 72 and 91 Ma, consistent with magmatic ages from Lamoille Canyon to the south. An age of ca. 90 Ma is suggested, the younger 206Pb/238U ages resulting from Pb loss. The Cretaceous and Precambrian zircon components also have distinct trace element characteristics, indicating that these age groups are not related to the same igneous source. These results support recent geophysical interpretations and negate the contention that the Archean-Proterozoic boundary extends into the central Great Basin area. They further suggest that the world-class gold deposits along the Carlin Trend are not underlain by Archean cratonal crust, but rather by the Proterozoic Mojave

  8. 87Sr/86Sr Ratios in Carbonate From the Red Lake and Steep Rock Groups in Canada Suggest Rb-enriched Continental Crust was Influencing Seawater Chemistry Prior to 3.0 Ga (United States)

    Satkoski, A.; Fralick, P. W.; Beard, B. L.; Johnson, C.


    Previous work has suggested that prior to 2.5 Ga, Sr isotope compositions of seawater were essentially mantle buffered and the effects of continental weathering on seawater chemistry were negligible. To test this, we collected Sr isotope data from 2.93 and 2.80 Ga carbonates that are part of the Red Lake and Steep Rock groups (Canada), respectively. To better understand carbonate formation and any post-depositional alteration, Sr isotopes are considered with O isotopes and REEs, as well as Rb and Sr contents, including correction for decay of 87Rb. All samples have Y/Ho ratios higher than chondrite and have positive La anomalies, which, combined with low Rb contents suggests that clastic contamination is negligible. Samples we consider near pristine have δ18O (VSMOW) values >20‰. Samples with the highest Y/Ho ratios and largest La anomalies from Red Lake and Steep Rock have initial 87Sr/86Sr ratios of 0.7018-0.7020. This Sr isotope composition is significantly more radiogenic than contemporaneous mantle (0.7011-0.7012), especially at a time when the isotopic difference between the crust and mantle was much less than today. This implies that radiogenic continental crust was emergent and shed detritus into the world's oceans prior to 3.0 Ga, in contrast with proposals for submerged continental crust, but in line with new estimates that continental crust at 3.0 Ga was 60-70% of current volume. We contend that this large amount of crust combined with enhanced Archean weathering could account for the radiogenic Sr isotope compositions we report here, and suggests a significant impact from continental weathering on ocean chemistry during the Archean.

  9. Lake (United States)

    Wien, Carol Anne


    The lake is blue black and deep. It is a glaciated finger lake, clawed out of rock when ice retracted across Nova Scotia in a northerly direction during the last ice age. The lake is narrow, a little over a mile long, and deep, 90 to 190 feet in places according to local lore, off the charts in others. The author loves to swim there, with a sense…

  10. Electrical Structure and Fault Features of Crust and Upper Mantle beneath the Western Margin of the Qinghai-Tibet Plateau: Evidence from the Magnetotelluric Survey along Zhada-Quanshui Lake Profile

    Institute of Scientific and Technical Information of China (English)

    Jin Sheng; Ye Gaofeng; Wei Wenbo; Deng Ming; Jing Jian'en


    The magnetotelluric (MT) survey along the Zhada (札达)-Quanshui (泉水) Lake profile on the western margin of the Qinghai (青海)-Tibet plateau shows that the study area is divided into three tectonic provinces by the Yalung Tsangpo and Bangong (班公)-Nujiang (怒江) sutures. From south to north these are the Himalayan terrane, Gangdise terrane, and Qiangtang (羌塘) terrane. For the study area, there are widespread high-conductivity layers in the mid and lower crust, the top layers of which fluctuate intensively. The high-conductivity layer within the Gangdise terrane is deeper than those within the Qiangtang terrane and the Himalaya terrane, and the deepest high-conductivity layer is to the south of the Bangong-Nujiang suture. The top surface of the high-conductivity layer in the south of the Bangong-Nujiang suture is about 20 km lower than that in the north of it. The high-conductivity layer within the Gangdise terrane dips toward north and there are two high-conductivity layers within the crust of the southern Qiangtang terrane. In the upper crust along the profile, there are groups of lateral electrical gradient zones or distortion zones of different scales and occurrence indicating the distribution of faults and sutures along the profile. According to the electrical structure, the structural characteristics and space distribution of the Yalung Tsangpo suture,Bangong-Nujiang suture, and the major faults of Longmucuo (龙木错) and Geerzangbu are inferred.

  11. Analysis of a Rare Continuous Rainy Process in Midsummer

    Institute of Scientific and Technical Information of China (English)


    [Objective] The research aimed to analyze a rare low temperature and rainy weather process which happened in Anhui Province from July 22 to August 14,2009.[Method] Based on the data of conventional observation,NCEP analysis field and automatic station,a rare low temperature and rainy weather process which occurred in Anhui Province from July 22 to August 14,2009 was analyzed.The formation reason of continuous rainy process in midsummer was discussed.The circulation characteristics and influence systems of c...

  12. Number of winter rainy days reconstructed from southwestern tree rings

    Energy Technology Data Exchange (ETDEWEB)

    Woodhouse, C. [NOAA Paleoclimatology Program, Boulder, CO (United States); Meko, D. [Univ. of Arizona, Tucson, AZ (United States)


    The objective of this paper is to explore the usefulness of tree-ring data for quantifying the temporal variability of winter rainy-day frequency over the past three centuries in the southwestern United States. The climatological variable, number of rainy days, has not previously been used in dendroclimatic reconstructions. It is reasonable to expect that the number of rainy days might be more strongly related than total precipitation to seasonally aggregated moisture conditions sensed by trees, especially in areas where rainfall from infrequent, heavy storms may run off before much moisture is absorbed into the soil. This study uses a network of tree-ring chronologies with a common time period 1702-1983 to reconstruct number of winter rainy days for a sub-region within the Southwest. The variance in the rainy day record explained by the tree-ring chronologies exceeds the 60% variance commonly yielded from arid-site trees in western North America. Calibration and verification statistics are highly significant, and a comparison with an independent gauge record helps validate the reconstruction. Conceptually and by the objective criterion of percent variance explained, number of rainy days appears, for this region, to be superior to total winter precipitation as a climatic variable for tree-ring reconstruction. 17 refs., 4 figs.

  13. SHRIMP-RG U-Pb isotopic systematics of zircon from the Angel Lake orthogneiss, East Humboldt Range, Nevada: is this really Archean crust? REPLY (United States)

    Premo, Wayne R.


    The comments from McGrew and Snoke are well received and their concerns for the interpretations in our paper (Premo et al., 2008), which questions the original contention that the Angel Lake orthogneiss is an Archean rock, are many and varied—all of which we will attempt to address. As they point out, this issue is an important one as this particular crustal exposure may delimit the southwestern extent of the Archean Wyoming province (Foster et al., 2006; Mueller and Frost, 2006), which has implications for the true crustal evolution of this region of the Great Basin and perhaps more importantly its relationship (if any) to the location of the world-class gold deposits of north-central Nevada (e.g., Howard, 2003).


    Directory of Open Access Journals (Sweden)



    Full Text Available Pluviometric hazards in the rainy summer of 2014 in Oltenia. After the rainy spring of 2014, marked by five waves of pouring rains which caused floods and water bogging on crops, the rainy period also continued in the summer months reaching its peak in July. Air temperature which has been cool in some interval, but close to normal led to some gradual delays in June and July, and only in August some gradual enforcements brought the crops to a normal stage. The most intense rainfall of the summer was registered in the interval 27-31 July 2014 . The analysis of climatic conditions in the south-west of Romania in the summer of 2014 is a continuation of some extended studies on climate variability. The paper is useful to specialists, doctoral candidates and master graduates and to all people interested in the climate’s evolution.

  15. Assessment of the ecological status and threats of Welala and Shesher wetlands, lake Tana Sub-Basin (Ethiopia)

    NARCIS (Netherlands)

    Atnafu, N.; Dejen, E.; Vijverberg, J.


    The ecological status of the Welala and Shesher Wetlands, on the eastern side of Lake Tana, were studied during pre-rainy, main-rainy, post-rainy and dry seasons from May 2009 to January 2010. Species composition, diversity and abundance of macrophytes, benthic macro-invertebrates and birds were

  16. Freshly brewed continental crust (United States)

    Gazel, E.; Hayes, J. L.; Caddick, M. J.; Madrigal, P.


    Earth's crust is the life-sustaining interface between our planet's deep interior and surface. Basaltic crusts similar to Earth's oceanic crust characterize terrestrial planets in the solar system while the continental masses, areas of buoyant, thick silicic crust, are a unique characteristic of Earth. Therefore, understanding the processes responsible for the formation of continents is fundamental to reconstructing the evolution of our planet. We use geochemical and geophysical data to reconstruct the evolution of the Central American Land Bridge (Costa Rica and Panama) over the last 70 Ma. We also include new preliminary data from a key turning point (~12-6 Ma) from the evolution from an oceanic arc depleted in incompatible elements to a juvenile continental mass in order to evaluate current models of continental crust formation. We also discovered that seismic P-waves (body waves) travel through the crust at velocities closer to the ones observed in continental crust worldwide. Based on global statistical analyses of all magmas produced today in oceanic arcs compared to the global average composition of continental crust we developed a continental index. Our goal was to quantitatively correlate geochemical composition with the average P-wave velocity of arc crust. We suggest that although the formation and evolution of continents may involve many processes, melting enriched oceanic crust within a subduction zone, a process probably more common in the Achaean where most continental landmasses formed, can produce the starting material necessary for juvenile continental crust formation.

  17. Evolution of the Chilka Lake granulite complex, northern Eastern Ghats Belt, India: First evidence of ~ 780 Ma decompression of the deep crust and its implication on the India-Antarctica correlation (United States)

    Bose, S.; Das, K.; Torimoto, J.; Arima, M.; Dunkley, D. J.


    High-grade para- and orthogneissic rocks near the Chilka Lake granulite complex, northern part of the Eastern Ghats Belt show complex structural and petrological history. Based on field and petrographic characters, five (M1-M5) metamorphic events could be identified. The earliest metamorphic event (M1) produced amphibolite grade mineral assemblage which produced the peak granulite (M2) assemblages at 900-950 °C, 8.5-9.0 kbar. The third metamorphic event caused decompression of the deeper crust up to 700-800 °C, 6.0-6.5 kbar. This was followed by cooling (M4) and subsequent thermal overprinting (M5). Fluid-composition during M3 was dominated by high-density CO2 and changed to low-density mixed CO2-H2O during the M3. Zircon U-Pb SHRIMP data suggest 781 ± 9 Ma age for M3 event. Texturally constrained monazite U-Th-Pb EPMA data, on the other hand, yield a group age of 988 ± 23 Ma from grain interior, which can signifies the age of M2 event. Few spots with younger dates in the range of 550-500 Ma are also noted. This interpretation changes the existing tectonothermal history of northern Eastern Ghats Belt. Our data show that the two adjacent crustal domains of the Eastern Ghats Belt show distinctly contrasting Neoproterozoic histories. While the central Domain 2 evolved through early anticlockwise P-T path culminating in ultrahigh temperature, the northern Domain 3 evolved through a clockwise P-T path. It appears that the Domain 3 was contiguous to East Antarctica and became part of the Eastern Ghats Belt during the assembly of Gondwana. The ca. 780 Ma decompression event in the northern Eastern Ghats Belt opens up new possibilities for interpreting the breakup of Rodinia.

  18. Network global navigation satellite system survey to harmonize water-surface elevation data for the Rainy River Basin (United States)

    Ziegeweid, Jeffrey R.; Silliker, R. Jason; Densmore, Brenda K.; Krahulik, Justin


    Continuously recording water-level streamgages in Rainy Lake and Namakan Reservoir are used to regulate water levels according to rule curves established in 2000 by the International Joint Commission; however, water levels at streamgages were referenced to a variety of vertical datums, confounding efforts to model the flow of water through the system, regulate water levels during periods of high inflow, and evaluate the effectiveness of the rule curves. In October 2014, the U.S. Geological Survey, Natural Resources Canada, International Joint Commission, and National Park Service began a joint field study with the goal of obtaining precise elevations referenced to a uniform vertical datum for all reference marks used to set water levels at streamgages throughout Rainy Lake and Namakan Reservoir. This report was prepared by the U.S. Geological Survey in cooperation with Natural Resources Canada, International Joint Commission, and National Park Service.Three field crews deployed Global Navigation Satellite System receivers statically over 16 reference marks colocated with active and discontinued water-level streamgages throughout Rainy River, Rainy Lake, Namakan Reservoir, and select tributaries of Rainy Lake and Namakan Reservoir. A Global Navigation Satellite System receiver also was deployed statically over a National Geodetic Survey cooperative base network control station for use as a quality-control reference mark. Satellite data were collected simultaneously during a 5-day period and processed independently by the U.S. Geological Survey and Natural Resources Canada to obtain accurate positioning and elevations for the 17 surveyed reference marks. Processed satellite data were used to convert published water levels to elevations above sea level referenced to the Canadian Geodetic Vertical Datum of 2013 in order to compare water-surface elevations referenced to a uniform vertical datum throughout the study area. In this report, an “offset” refers to the


    Institute of Scientific and Technical Information of China (English)

    HUANG Xian-xiang; YAN Li-jun; SHI Neng


    By using the significance test of two-dimensional wind field anomalies and Monte Carlo simulation experiment scheme, the significance features of wind field anomalies are investigated in relation to flood/drought during the annually first rainy season in south China. Results show that western Pacific subtropical high and wind anomalies over the northeast of Lake Baikal and central Indian Ocean are important factors. Wind anomalies over the northern India in January and the northwest Pacific in March may be strong prediction signals. Study also shows that rainfall in south China bears a close relation to the geopotential height filed over the northern Pacific in March.

  20. Identification of rainy periods from ground based microwave radiometry

    Directory of Open Access Journals (Sweden)

    Ada Vittoria Bosisio


    Full Text Available In this paper the authors present the results of a study aiming at detecting rainy data in measurements collected by a dual band ground-based radiometer. The proposed criterion is based on the ratio of the brightness temperatures observed in the 20-30 GHz band without need of any ancillary information. A major result obtained from the probability density of the ratio computed over one month of data is the identification of threshold values between clear sky, cloudy sky and rainy sky, respectively. A linear fit performed by using radiometric data and concurrent rain gauge measurements shows a correlation coefficient equal to 0.56 between the temperature ratio and the observed precipitation.

  1. Global warming induced hybrid rainy seasons in the Sahel (United States)

    Salack, Seyni; Klein, Cornelia; Giannini, Alessandra; Sarr, Benoit; Worou, Omonlola N.; Belko, Nouhoun; Bliefernicht, Jan; Kunstman, Harald


    The small rainfall recovery observed over the Sahel, concomitant with a regional climate warming, conceals some drought features that exacerbate food security. The new rainfall features include false start and early cessation of rainy seasons, increased frequency of intense daily rainfall, increasing number of hot nights and warm days and a decreasing trend in diurnal temperature range. Here, we explain these mixed dry/wet seasonal rainfall features which are called hybrid rainy seasons by delving into observed data consensus on the reduction in rainfall amount, its spatial coverage, timing and erratic distribution of events, and other atmospheric variables crucial in agro-climatic monitoring and seasonal forecasting. Further composite investigations of seasonal droughts, oceans warming and the regional atmospheric circulation nexus reveal that the low-to-mid-level atmospheric winds pattern, often stationary relative to either strong or neutral El-Niño-Southern-Oscillations drought patterns, associates to basin warmings in the North Atlantic and the Mediterranean Sea to trigger hybrid rainy seasons in the Sahel. More challenging to rain-fed farming systems, our results suggest that these new rainfall conditions will most likely be sustained by global warming, reshaping thereby our understanding of food insecurity in this region.

  2. Predictability of rainy season onset and cessation in east Africa (United States)

    Joseph, B.-M.


    PREDICTABILITY OF RAINY SEASONS ONSET AND CESSATION IN EAST AFRICA Boyard-Micheau Joseph, Camberlin Pierre, Kenya and northern Tanzania mainly display bimodal rainfall regimes, which are controlled by the annual migration of the Intertropical Convergence Zone on both sides of the equator. In the low-income, semi-arid areas, food security is highly dependent on cereal yields (maize, millet and sorghum). Vulnerability is aggravated by the fact that these crops are mostly rainfed, and rely on the performance of the two, relatively brief rainy seasons. This performance depends on a combination of several rainy season characteristics, or rainfall descriptors, such as the onset and cessation dates of the rains, the frequency of rainy days, their intensity and the occurrence of wet/dry spells. The prediction of these descriptors some time (>15 days) before the real onset of the rainy season can be seen as a useful tool to help in the establishment of agricultural adaptation strategies. The main objective consists to understand linkages between regional variability of these rainfall descriptors and global modes of the climate system, in order to set up efficient predictive tools based on Model Output Statistics (MOS). The rainfall descriptors are computed from daily rainfall data collected for the period 1961-2001 from the Kenya Meteorological Department, the IGAD Climate Prediction and Application Center and the Tanzania Meteorological Agency. An initial spatial coherence analysis assesses the potential predictability of each descriptor, permitting eventually to eliminate those which are not spatially coherent, on the assumption that low spatial coherence denotes low potential predictability. Rainfall in East Africa simulated by a 24-ensemble member of the ECHAM 4.5 atmospheric general circulation model is compared with observations, to test the reproducibility of the rainfall descriptors. Canonical Correlation Analysis is next used to

  3. Icelandic-type crust (United States)

    Foulger, G.R.; Du, Z.; Julian, B.R.


    Numerous seismic studies, in particular using receiver functions and explosion seismology, have provided a detailed picture of the structure and thickness of the crust beneath the Iceland transverse ridge. We review the results and propose a structural model that is consistent with all the observations. The upper crust is typically 7 ?? 1 km thick, heterogeneous and has high velocity gradients. The lower crust is typically 15-30 ?? 5 km thick and begins where the velocity gradient decreases radically. This generally occurs at the V p ??? 6.5 km s-1 level. A low-velocity zone ??? 10 000 km2 in area and up to ??? 15 km thick occupies the lower crust beneath central Iceland, and may represent a submerged, trapped oceanic microplate. The crust-mantle boundary is a transition zone ???5 ?? 3 km thick throughout which V p increases progressively from ???7.2 to ???8.0 km s-1. It may be gradational or a zone of alternating high- and low-velocity layers. There is no seismic evidence for melt or exceptionally high temperatures in or near this zone. Isostasy indicates that the density contrast between the lower crust and the mantle is only ???90 kg m-3 compared with ???300 kg m-3 for normal oceanic crust, indicating compositional anomalies that are as yet not understood. The seismological crust is ???30 km thick beneath the Greenland-Iceland and Iceland-Faeroe ridges, and eastern Iceland, ???20 km beneath western Iceland, and ???40 km thick beneath central Iceland. This pattern is not what is predicted for an eastward-migrating plume. Low attenuation and normal V p/V s ratios in the lower crust beneath central and southwestern Iceland, and normal uppermost mantle velocities in general, suggest that the crust and uppermost mantle are subsolidus and cooler than at equivalent depths beneath the East Pacific Rise. Seismic data from Iceland have historically been interpreted both in terms of thin-hot and thick-cold crust models, both of which have been cited as supporting the plume

  4. Irregular Information of the Rainstorm in a Continuous Rainy Weather

    Institute of Scientific and Technical Information of China (English)

    LI; Ming-juan


    [Objective]The research aimed to analyze irregular information of the local rainstorm process (during 5-6 September,2009) in autumn continuous rainy weather in north Shaanxi. [Method] Based on V-3θ chart, routine observation data provided by Micaps system, satellite cloud chart and data at 100 automatic meteorological stations of Shaanxi, for rainstorm process in autumn continuous rainy weather in north Shaanxi during 4-10 September, 2009, by using structure analysis method, irregular information in local rainstorm weather was analyzed. [Result]In whole precipitation process, atmospheric structure in rainstorm zone presented obvious evolution process. Before precipitation, typical atmospheric structure information of the sudden convective weather appeared. Obvious ultra-low temperature structure appeared at 200 hPa, and consistent clockwise rotation flow was at vertical wind field. Meanwhile, water vapor was sufficient, and unstable energy existed at low layer. Structure characteristic of the convective strong precipitation appeared by advancing for 12h. As precipitation weakened, unstable energy was released, and ultra-low temperature disappeared. [Conclusion]The research provided some thoughts for the forecast of such weather process.

  5. Rainy Season Assessment of Azraq Basin in Eastern Jordan

    Directory of Open Access Journals (Sweden)

    R.S. Shatnawi


    Full Text Available This study considers the rainfall pattern in the Azraq basin in the Eastern part of Jordan. Azraq Basin is an extensive inland drainage system lying in the steppe and desert to the east of Jordan. The Azraq area is around 17,000 km2, which accounts for about 15% of the country’s total area, stretching from the lava peaks of Jebel Arab in southern Syria to Wadi Sirhan in northern Saudi Arabia. The Basin is considered part of the desert where the annual precipitation is estimated to be less than 150 mm/year and some areas receiving as little as 50 mm rainfall annually. Dry and hot climate during the summer and very cold winter with little rain falls in the form of thunderstorms and is similar to the continental climate of the desert climate where the big difference in temperature between day and night. The study aimed at assessing the rainy season’s conditions in the basin. The data for three rain gauges with monthly records of rainfall between (1960-2010 are used in the analysis. These stations are: Azraq, Um Alquttein and Deir Alkahf stations. The rainy seasons in the study area seem to get shorter and shifted in their start. The highest percentage of rain falls in the middle stage of the season (i.e., between December and February. This percentage is getting increased for Azraq and Deir Alkahf stations; however Um Alquttein shows a cyclic pattern of rainfall during the different seasons.

  6. Raising the continental crust (United States)

    Campbell, Ian H.; Davies, D. Rhodri


    The changes that occur at the boundary between the Archean and Proterozoic eons are arguably the most fundamental to affect the evolution of Earth's continental crust. The principal component of Archean continental crust is Granite-Greenstone Terranes (GGTs), with granites always dominant. The greenstones consist of a lower sequence of submarine komatiites and basalts, which erupted onto a pre-existing Tonalite-Trondhjemite-Granodiorite (TTG) crust. These basaltic rocks pass upwards initially into evolved volcanic rocks, such as andesites and dacites and, subsequently, into reworked felsic pyroclastic material and immature sediments. This transition coincides with widespread emplacement of granitoids, which stabilised (cratonised) the continental crust. Proterozoic supra-crustal rocks, on the other hand, are dominated by extensive flat-lying platform sequences of mature sediments, which were deposited on stable cratonic basements, with basaltic rocks appreciably less abundant. The siliceous TTGs cannot be produced by direct melting of the mantle, with most hypotheses for their origin requiring them to be underlain by a complimentary dense amphibole-garnet-pyroxenite root, which we suggest acted as ballast to the early continents. Ubiquitous continental pillow basalts in Archean lower greenstone sequences require the early continental crust to have been sub-marine, whereas the appearance of abundant clastic sediments, at higher stratigraphic levels, shows that it had emerged above sea level by the time of sedimentation. We hypothesise that the production of komatiites and associated basalts, the rise of the continental crust, widespread melting of the continental crust, the onset of sedimentation and subsequent cratonisation form a continuum that is the direct result of removal of the continent's dense amphibole-garnet-pyroxenite roots, triggered at a regional scale by the arrival of a mantle plume at the base of the lithosphere. Our idealised calculations suggest

  7. A Lagrangian identification of the main sources of moisture affecting northeastern Brazil during its pre-rainy and rainy seasons.

    Directory of Open Access Journals (Sweden)

    Anita Drumond

    Full Text Available This work examines the sources of moisture affecting the semi-arid Brazilian Northeast (NEB during its pre-rainy and rainy season (JFMAM through a Lagrangian diagnosis method. The FLEXPART model identifies the humidity contributions to the moisture budget over a region through the continuous computation of changes in the specific humidity along back or forward trajectories up to 10 days period. The numerical experiments were done for the period that spans between 2000 and 2004 and results were aggregated on a monthly basis. Results show that besides a minor local recycling component, the vast majority of moisture reaching NEB area is originated in the south Atlantic basin and that the nearby wet Amazon basin bears almost no impact. Moreover, although the maximum precipitation in the "Poligono das Secas" region (PS occurs in March and the maximum precipitation associated with air parcels emanating from the South Atlantic towards PS is observed along January to March, the highest moisture contribution from this oceanic region occurs slightly later (April. A dynamical analysis suggests that the maximum precipitation observed in the PS sector does not coincide with the maximum moisture supply probably due to the combined effect of the Walker and Hadley cells in inhibiting the rising motions over the region in the months following April.

  8. Disaggregation of Rainy Hours: Compared Performance of Various Models. (United States)

    Ben Haha, M.; Hingray, B.; Musy, A.

    In the urban environment, the response times of catchments are usually short. To de- sign or to diagnose waterworks in that context, it is necessary to describe rainfall events with a good time resolution: a 10mn time step is often necessary. Such in- formation is not always available. Rainfall disaggregation models have thus to be applied to produce from rough rainfall data that short time resolution information. The communication will present the performance obtained with several rainfall dis- aggregation models that allow for the disaggregation of rainy hours into six 10mn rainfall amounts. The ability of the models to reproduce some statistical character- istics of rainfall (mean, variance, overall distribution of 10mn-rainfall amounts; ex- treme values of maximal rainfall amounts over different durations) is evaluated thanks to different graphical and numerical criteria. The performance of simple models pre- sented in some scientific papers or developed in the Hydram laboratory as well as the performance of more sophisticated ones is compared with the performance of the basic constant disaggregation model. The compared models are either deterministic or stochastic; for some of them the disaggregation is based on scaling properties of rainfall. The compared models are in increasing complexity order: constant model, linear model (Ben Haha, 2001), Ormsbee Deterministic model (Ormsbee, 1989), Ar- tificial Neuronal Network based model (Burian et al. 2000), Hydram Stochastic 1 and Hydram Stochastic 2 (Ben Haha, 2001), Multiplicative Cascade based model (Olsson and Berndtsson, 1998), Ormsbee Stochastic model (Ormsbee, 1989). The 625 rainy hours used for that evaluation (with a hourly rainfall amount greater than 5mm) were extracted from the 21 years chronological rainfall series (10mn time step) observed at the Pully meteorological station, Switzerland. The models were also evaluated when applied to different rainfall classes depending on the season first and on the

  9. Objective identification research on cold vortex and mid-summer rainy periods in Northeast China

    Institute of Scientific and Technical Information of China (English)

    龚志强; 封泰晨; 房一禾


    Considering the differences between the Northeast China Cold Vortex (CV) and the Mid-Summer (MS) rainy period and their corresponding atmospheric circulations are comprehensively analyzed, and the objective identification methods of defining the annual beginning and ending dates of Northeast China CV and MS rainy periods are developed respectively. The annual beginning date of the CV (MS) rainy period is as follows. In a period from April to August, if daily regional mean precipitation ryi is larger than yearly regional mean precipitation R (or 2R) on a certain day, the station precipitation rs is larger than the station yearly mean precipitation hri (or 2hri) in at least 50%of stations in Northeast China, and this condition is satisfied in the following 2 (7) days, then this date is defined as the beginning date of the CV (MS) rainy period. While the definition of the ending date of the MS rainy period shows the opposite process to its beginning date. With this objective identification method, the multi-year average (1981–2010) beginning date of the CV rainy period is May 3, the beginning date of the MS rainy period is June 27, the ending day of the CV rainy period is defined as the day before the beginning date of the MS rainy period, and the ending date of the MS rainy period is August 29. Meanwhile, corresponding anomaly analysis at a 500-hPa geopotential height, 850-hPa wind, Omega and relative humidity fields all show that the definitions of the average beginning and ending dates of the CV and MS rainy periods have a certain circulation meaning. Furthermore, the daily evolution of the CV index, meridional and zonal wind index, etc. all show that these objectively defined beginning and ending dates of the CV and MS rainy periods have climate significance.

  10. Aspects Concerning the Rainy Spells in the Western Plain of Romania



    The present work analyses the rainy spells on the territory of the Western Plain at the North of the Mureş River. Daily precipitation data were used from a number of 5 weather stations and for a period of 42 years (1961-2002). Only the stations with a common observation period were chosen. Periods with two or more consecutive rainy days were studied and the analyses show a total of about 7,000 rainy spells. The number of the rainy spells grows from the South to the North once with the latitud...

  11. Aspects Concerning the Rainy Spells in the Western Plain of Romania

    Directory of Open Access Journals (Sweden)



    Full Text Available The present work analyses the rainy spells on the territory of the Western Plain at the North of the Mureş River. Daily precipitation data were used from a number of 5 weather stations and for a period of 42 years (1961-2002. Only the stations with a common observation period were chosen. Periods with two or more consecutive rainy days were studied and the analyses show a total of about 7,000 rainy spells. The number of the rainy spells grows from the South to the North once with the latitude but also from the West to the East, once with the altitude. Within a year may occur, on the average, about 30-35 rainy spells with an average duration of 4 days. The duration of the rainy spells varies between 2-19 days. On the analysed territory, 119-141 rainy days may occur annually, on the average. Namely, on this territory it rains on the average about 4-4.5 months a year. Most of the rainy days were recorded in the intervals November-January and April-June.

  12. Objective identification research on cold vortex and mid-summer rainy periods in Northeast China (United States)

    Gong, Zhi-Qiang; Feng, Tai-Chen; Fang, Yi-He


    Considering the differences between the Northeast China Cold Vortex (CV) and the Mid-Summer (MS) rainy period and their corresponding atmospheric circulations are comprehensively analyzed, and the objective identification methods of defining the annual beginning and ending dates of Northeast China CV and MS rainy periods are developed respectively. The annual beginning date of the CV (MS) rainy period is as follows. In a period from April to August, if daily regional mean precipitation ryi is larger than yearly regional mean precipitation R (or 2R) on a certain day, the station precipitation rs is larger than the station yearly mean precipitation (or 2) in at least 50% of stations in Northeast China, and this condition is satisfied in the following 2 (7) days, then this date is defined as the beginning date of the CV (MS) rainy period. While the definition of the ending date of the MS rainy period shows the opposite process to its beginning date. With this objective identification method, the multi-year average (1981-2010) beginning date of the CV rainy period is May 3, the beginning date of the MS rainy period is June 27, the ending day of the CV rainy period is defined as the day before the beginning date of the MS rainy period, and the ending date of the MS rainy period is August 29. Meanwhile, corresponding anomaly analysis at a 500-hPa geopotential height, 850-hPa wind, Omega and relative humidity fields all show that the definitions of the average beginning and ending dates of the CV and MS rainy periods have a certain circulation meaning. Furthermore, the daily evolution of the CV index, meridional and zonal wind index, etc. all show that these objectively defined beginning and ending dates of the CV and MS rainy periods have climate significance. Project supported by the National Natural Science Foundation of China (Grant Nos. 41205040 and 41375078), the State Key Development Program for Basic Research, China (Grant No. 2012CB955203), and the Special

  13. Physics of Neutron Star Crusts

    Directory of Open Access Journals (Sweden)

    Chamel Nicolas


    Full Text Available The physics of neutron star crusts is vast, involving many different research fields, from nuclear and condensed matter physics to general relativity. This review summarizes the progress, which has been achieved over the last few years, in modeling neutron star crusts, both at the microscopic and macroscopic levels. The confrontation of these theoretical models with observations is also briefly discussed.

  14. Phytoplankton dynamics of a tropical river: A dry and rainy season ...

    African Journals Online (AJOL)

    ... dynamics of a tropical river: A dry and rainy season comparison. ... Qualitative phytoplankton samples were collected by towing 55 ìm mesh plankton net while quantitative samples were obtained by sedimenting a known volume of water ...

  15. Summary appraisals of the Nation's ground-water resources; Souris-Red-Rainy region (United States)

    Reeder, Harold O.


    A broad-perspective analysis of the ground-water resources and present and possible future water development and management in the Souris-Red-Rainy Region is presented. The region includes the basins of the Souris River within Montana and North Dakota; the Red River of the North in South Dakota, North Dakota, and Minnesota; and the Rainy River within Minnesota. The region includes 59,645 square miles, mostly in North Dakota and Minnesota.

  16. Analysis on the Precipitation Characteristics in the Rainy Season in Liupanshui City in Recent 50 Years

    Institute of Scientific and Technical Information of China (English)


    [Objective] The research aimed to study the variation rule of precipitation in the rainy season in Liupanshui City in recent 50 years. [Method] Based on the monthly precipitation data from three observatories (Liuzhi, Panxian and Shuicheng) of Liupanshui City from May to September during 1960-2009, the interannual, interdecadal variation and mutation characteristics of precipitation in the rainy season in Liupanshui City in recent 50 years were analyzed by using the linear tendency estimation, sliding T-tes...

  17. Forecasting of Amount of Rainfall in Rainy Season by using Information Obtained from El Nino Data (United States)

    Yamada, Fujihiro; Yamamoto, Nobuyuki; Sugimoto, Shigeyuki; Ichiyanagi, Katsuhiro; Hibino, Yasuyuki; Nakano, Hiroyuki; Mizuno, Katsunori; Yukita, Kazuto; Goto, Yasuyuki

    In electric power system operation and dam management, it is important that we forecast the rainfall depth in the rainy season. This paper studies the technique using neural network in order to forecast the amount of rainfall in rainy season on upper district of dam for hydro power plant. A case study was carried out on Central Japan. We were able to confirm the effectiveness of the information obtained from El Nino and La Nina data.

  18. Creep behavior of microbiotic crust

    Institute of Scientific and Technical Information of China (English)


    The creep behavior of microbiotic crust at room temperature was revealed by the creep bending tests of cantilever beam under constant-load conditions.The variation in the deflection with time can be depicted well by a standard creep curve.Creep rupture is a fundamental failure mechanism of microbiotic crust due to creep.A simple theory was then applied to describe this new me-chanical behavior.The existence of creep phenomenon brings into question the validity of widely used methods for measuring the strength of microbiotic crust.

  19. Crust Formation in Aluminum Cells (United States)

    Oedegard, R.; Roenning, S.; Rolseth, S.; Thonstad, J.


    This paper examines the catalytic effects offlourides on the ϒ→α-Al2O3 phase transformation by heat treating commercial alumina samples with 2wt% additions of different flouride compounds. The various additives were ranked according to their effect on transformation temperature. Experiments were conducted to explain the high temperature coherence of crusts. The findings indicate that an alumina network is formed during ϒ→α phase transformation, which reinforces the crust on top of the cryolite bath.

  20. Evaporative sodium salt crust development and its wind tunnel derived transport dynamics under variable climatic conditions (United States)

    Nield, Joanna M.; McKenna Neuman, Cheryl; O'Brien, Patrick; Bryant, Robert G.; Wiggs, Giles F. S.


    Playas (or ephemeral lakes) can be significant sources of dust, but they are typically covered by salt crusts of variable mineralogy and these introduce uncertainty into dust emission predictions. Despite the importance of crust mineralogy to emission potential, little is known about (i) the effect of short-term changes in temperature and relative humidity on the erodibility of these crusts, and (ii) the influence of crust degradation and mineralogy on wind speed threshold for dust emission. Our understanding of systems where emission is not driven by impacts from saltators is particularly poor. This paper describes a wind tunnel study in which dust emission in the absence of saltating particles was measured for a suite of climatic conditions and salt crust types commonly found on Sua Pan, Botswana. The crusts were found to be non-emissive under climate conditions characteristic of dawn and early morning, as compared to hot and dry daytime conditions when the wind speed threshold for dust emission appears to be highly variable, depending upon salt crust physicochemistry. Significantly, sodium sulphate rich crusts were found to be more emissive than crusts formed from sodium chloride, while degraded versions of both crusts had a lower emission threshold than fresh, continuous crusts. The results from this study are in agreement with in-situ field measurements and confirm that dust emission from salt crusted surfaces can occur without saltation, although the vertical fluxes are orders of magnitude lower (∼10 μg/m/s) than for aeolian systems where entrainment is driven by particle impact.

  1. Comparison of Freshwater Mollusc Assemblages between Dry and Rainy Season in Situ Gede System, Bogor, Indonesia (United States)

    Priawandiputra, W.; Nasution, D. J.; Prawasti, T. S.


    Anthropogenic activities, which reduced and damaged natural situ (freshwater ponds), also reduced fauna diversity in its aquatic ecosystem. Freshwater molluscs in the situ, one of the largest numbers of animals group with documented extinction, may also be impacted. The aims of this study were to record and to compare the abundance and species composition of freshwater molluscs between dry and rainy season in three situ. The freshwater molluscs were determined by twelve sampling points in Situ Gede (SG), Situ Panjang (SP) and Situ Burung (SB). Samplings were conducted once during dry season (August 2015) and rainy season (February 2016). Total abundance of molluscs encountered was 4321 individuals, which was comprised of 76 bivalve individuals (1.75 %) and 4245 gastropods individuals (98.44%). The abundance of molluscs were generally higher in rainy season than in dry season in all situ, while species richness showed the contrary. The species composition was significantly different between dry and rainy season in SP and SB but no significant differences was found in SG. From eight dominant species, there were six dominant species such as Filopaludina javanica, Melanoides tuberculata, Thiara scabra, Sermyla requeti, Pila scutata (gastropods) and Pilsbryoconcha exilis (bivalve) which were found in high numbers during dry season while two gastropod species (Pomacea canaliculata and Wattebledia crosseana) was numbered higher in rainy season than dry season.

  2. Variation Characteristics of Low Temperature and Rainy Weather in Guangxi during Spring Sowing Period of Recent 50 Years

    Institute of Scientific and Technical Information of China (English)


    [Objective] The research aimed to study the variation characteristics of low temperature and rainy weather in Guangxi during spring sowing period of recent 50 years.[Method] Based on the daily average temperature data from 1961 to 2010 at 88 meteorological stations in Guangxi,yearly days and end date of low temperature and rainy weather during spring sowing period were carried out statistics.The variation characteristics of low temperature and rainy weather in Guangxi during spring sowing period of recent 5...

  3. The distribution of Aedes aegypti (diptera, culicidae) in eight selected parks of Lahore, using oviposition traps during rainy season. (United States)

    Ahmad Qureshi, Ejaz Mahmood; Tabinda, Amtul Bari; Vehra, Seemal


    To investigate the seasonal distribution of immature habitat of Aedes aegypti mosquito species and its association with environmental and climatic conditions. This descriptive study was conducted in eight parks in Lahore, Pakistan, over three years from 2011 to 2013.A total of 2,496 ovitraps were placed in environmentally different conditions near water channels, thick vegetation cover/shades, clean/unclean sites and places where there was lot of human activity. Each trap was monitored weekly in early rainy, late rainy, early post-rainy and late post-rainy seasons of each of the three years to determine the presence of Aedes aegypti larvae by measuring ovitrap index. SPSS19 was used for data analysis. The value for ovitrap index was found highest in late rainy season (20.83). High association was observed with environmental conditions (povitrap index with water channel, vegetation cover, cleanliness and human activity was significant in all four seasons (p=-0.000). With temperature, this association was significant only in early post-rainy (p=-0.000) and late post-rainy seasons (p=0.024). With humidity, it was significant in early post-rainy and late post-rainy seasons (p=-0.000 and p=0.024) while with rainfall, the association was significant in all seasons (p=0.000). Abundance and occurrence frequency of Aedes aegypti had a positive association with deteriorating environmental and seasonal climatic conditions.

  4. Palaeomagnetism and the continental crust

    Energy Technology Data Exchange (ETDEWEB)

    Piper, J.D.A.


    This book is an introduction to palaeomagnetism offering treatment of theory and practice. It analyzes the palaeomagnetic record over the whole of geological time, from the Archaean to the Cenozoic, and goes on to examine the impact of past geometries and movements of the continental crust at each geological stage. Topics covered include theory of rock and mineral magnetism, field and laboratory methods, growth and consolidation of the continental crust in Archaean and Proterozoic times, Palaeozoic palaeomagnetism and the formation of Pangaea, the geomagnetic fields, continental movements, configurations and mantle convection.

  5. Uncertainties in projected climate changes of the rainy season over West Africa related to bias adjustment (United States)

    Nikulin, Grigory; Bosshard, Thomas; Wilcke, Renate; Yang, Wei; Kjellström, Erik; Bärring, Lars


    Bias adjustment has become an integral part of pre-processing of climate simulations for use in impact modeling studies. Considered now as a necessary step to deal with inability of climate models to accurately simulate the present/recent climate, bias adjustment is a statistical approach missing physical arguments. Even if bias adjustment is widely used nowadays it is still a topic for debates and criticism. One of the main questions is what level of uncertainty does bias adjustment introduce to future climate projections? In this study, using an ensemble of the CORDEX-Africa simulations, we investigate potential impact of bias adjustment on the simulated rainy season in West Africa. A number of characteristics reflecting different aspects of the rainy season are used, namely: onset and cessation of the rainy season, mean intensity, total amount of precipitation and intra-seasonal variability within the rainy season. All these characteristics are evaluated in the original CORDEX-Africa simulations and in bias-adjusted ones for a reference period first and then future climate projections of these characteristics are compared between two ensembles. Additionally, we examine how bias adjustment may impact selection of a smaller more manageable ensemble of regional climate simulations from a grand one.

  6. Reduced herbivory during simulated ENSO rainy events increases native herbaceous plants in semiarid Chile

    NARCIS (Netherlands)

    Manrique, R.; Gutierrez, J.R.; Holmgren, M.; Squeo, F.A.


    El Niño Southern Oscillation (ENSO) events have profound consequences for the dynamics of terrestrial ecosystems. Since increased climate variability is expected to favour the invasive success of exotic species, we conducted a field experiment to study the effects that simulated rainy ENSO events in

  7. Feeding Ecology of Taruca (Hippocamelus antisensis Populations during the Rainy and Dry Seasons in Central Peru

    Directory of Open Access Journals (Sweden)

    Carla Gazzolo


    Full Text Available Tarucas (Hippocamelus antisensis live in rocky areas in the Andes, from northern Peru to northern Argentina. Microhistological analyses on their feeding ecology during the rainy and dry seasons were done at a National Park and a Landscape Reserve. The diet was diverse and more than 50 species were identified from the feces. Grass species were most often detected as eaten by taruca during the rainy season comprising near 70% of the consumed fragments with 35 plant species identified as eaten then. In the dry season, around 50 species were identified as eaten by tarucas, mostly dicotyledonous. The main species consumed in both seasons were Werneria nubigena, Poa gymnantha, Senecio comosus, and Ephedra americana. The ecological density was an intermediate value compared to other observed values in Peru. This is the first study to find the importance of grasses for tarucas, selected when soft, during the rainy season. A possible overlap with domestic ungulates’ diets should be explored, helping the conservation of taruca and generating an adequate management of the species and the ecosystem. There is a change in the palatable offer of food items during the rainy season, when most of the Gramineae species are tender.

  8. Evaluation of the Seasonal and Spatial Lake Level Change Using by Worldview-2 Satellite Images in the Egirdir Lake (Turkey) (United States)

    Sener, Erhan; Sener, Sehnaz; Uysal, Rahmi; Bulut, Cafer


    Eğirdir Lake is located in the Lake District, it is fourth largest lake and the second largest freshwater lake in Turkey. The lake is still drinking water sources in many residential areas. In this study two Worldview-2 satellite imagery which is high resolution 8-band has been used. The imagery covering the whole lake and belongs to date 10.05.2010 and 24.10.2010. Using Coastal Band (1.Band), Blue (2.Band), Green (3.Band), Yellow (4.Band) and Red (5.Band) on that satellite, seasonal water level in the rainy and dry periods in the selected pilot areas of the Eğirdir Lake has been aimed to determine. In this context, firstly Atmospheric Correction is applied to reduce their atmospheric effects. In order to mask of surface water The Normalized Water Different Index (NWDI) has been applied. Then seasonally varying fields has been identified with change analysis applied to two different image.

  9. Statistics of Magnetar Crusts Magnetoemission (United States)

    Kondratyev, V. N.; Korovina, Yu. V.


    Soft repeating gamma-ray (SGR) bursts are considered as magnetoemission of crusts of magnetars (ultranamagnetized neutron stars). It is shown that all the SGR burst observations can be described and systematized within randomly jumping interacting moments model including quantum fluctuations and internuclear magnetic interaction in an inhomogeneous crusty nuclear matter.

  10. Statistics of Magnetar Crusts Magnetoemission

    Directory of Open Access Journals (Sweden)

    Kondratyev V. N.


    Full Text Available Soft repeating gamma-ray (SGR bursts are considered as magnetoemission of crusts of magnetars (ultranamagnetized neutron stars. It is shown that all the SGR burst observations can be described and systematized within randomly jumping interacting moments model including quantum fluctuations and internuclear magnetic interaction in an inhomogeneous crusty nuclear matter.

  11. Crustal structure between Lake Mead, Nevada, and Mono Lake, California (United States)

    Johnson, Lane R.


    Interpretation of a reversed seismic-refraction profile between Lake Mead, Nevada, and Mono Lake, California, indicates velocities of 6.15 km/sec for the upper layer of the crust, 7.10 km/sec for an intermediate layer, and 7.80 km/sec for the uppermost mantle. Phases interpreted to be reflections from the top of the intermediate layer and the Mohorovicic discontinuity were used with the refraction data to calculate depths. The depth to the Moho increases from about 30 km near Lake Mead to about 40 km near Mono Lake. Variations in arrival times provide evidence for fairly sharp flexures in the Moho. Offsets in the Moho of 4 km at one point and 2 1/2 km at another correspond to large faults at the surface, and it is suggested that fracture zones in the upper crust may displace the Moho and extend into the upper mantle. The phase P appears to be an extension of the reflection from the top of the intermediate layer beyond the critical angle. Bouguer gravity, computed for the seismic model of the crust, is in good agreement with the measured Bouguer gravity. Thus a model of the crustal structure is presented which is consistent with three semi-independent sources of geophysical data: seismic-refraction, seismic-reflection, and gravity.

  12. Interactive effects of moss-dominated crusts and Artemisia ordosica on wind erosion and soil moisture in Mu Us sandland, China. (United States)

    Yang, Yongsheng; Bu, Chongfeng; Mu, Xingmin; Shao, Hongbo; Zhang, Kankan


    To better understand the effects of biological soil crusts (BSCs) on soil moisture and wind erosion and study the necessity and feasibility of disturbance of BSCs in the Mu Us sandland, the effects of four treatments, including moss-dominated crusts alone, Artemisia ordosica alone, bare sand, and Artemisia ordosica combined with moss-dominated crusts, on rainwater infiltration, soil moisture, and annual wind erosion were observed. The major results are as follows. (1) The development of moss-dominated crusts exacerbated soil moisture consumption and had negative effects on soil moisture in the Mu Us sandland. (2) Moss-dominated crusts significantly increased soil resistance to wind erosion, and when combined with Artemisia ordosica, this effect became more significant. The contribution of moss-dominated crusts under Artemisia ordosica was significantly lower than that of moss-dominated crusts alone in sites where vegetative coverage > 50%. (3) Finally, an appropriate disturbance of moss-dominated crusts in the rainy season in sites with high vegetative coverage improved soil water environment and vegetation succession, but disturbance in sites with little or no vegetative cover should be prohibited to avoid the exacerbation of wind erosion.

  13. Spatial and Temporal Variability of Rainfall in Eastern Amazon during the Rainy Season (United States)

    Batista da Silva Ferreira, Douglas; Barreiros de Souza, Everaldo; Cavalcanti de Moraes, Bergson; Meira Filho, Luiz Gylvan


    Empirical orthogonal functions (EOF) and composites analysis were employed on pentad data in order to investigate the tropical atmospheric-ocean patterns over the Atlantic Ocean and the spatial-temporal characteristics of the rainfall in eastern Amazon during the peak of the rainy season (February to April). The EOF results evidenced that the Intertropical Convergence Zone (ITCZ) is the main rainfall-producing system in eastern Amazon during the rainy season. Conditions associated with the southward SST gradient in the intertropical Atlantic formed the dynamic patterns that favored the position of the ITCZ to south of the equator, thus explaining the predominance of positive precipitation anomalies in eastern Amazon, especially in the state of Maranhão and northeastern Pará during the February and April months. PMID:25793218

  14. Interannual variability in rainy season characteristics over the Limpopo region of southern Africa (United States)

    Reason, C. J. C.; Hachigonta, S.; Phaladi, R. F.


    This study focuses on the interannual variability of dry spell frequencies, dry and wet spell characteristics and onset dates of the austral summer rainy season over the Limpopo region (22-25 °S, 27-32 °E) of northern South Africa. These characteristics of the rainy season are of considerable interest to farmers, water resource managers and other user groups. The Limpopo region supports a large rural population dependent on rain-fed agriculture as well as significant biodiversity, particularly in the Kruger National/Limpopo Transfrontier Park. It is also a region prone to devastating floods and droughts. Evidence is presented that summer dry spell frequency and onset date are related to ENSO via changes in regional circulation. Niño 3.4 sea surface temperature (SST) anomalies appear to show a robust relationship with dry spell frequency during the 1979-2002 period analysed. Anomalies in onset date of the rainy season during 1979-2002 appear to be inversely related to Niño 3.4 SST, with the relationship strengthening after 1986. These results suggest that there may be some predictability in these parameters, particularly in dry spell frequency during austral summer, based on existing skill in predicting tropical Pacific SST. Copyright

  15. Fewer rainy days and more extreme rainfall by the end of the century in Southern Africa (United States)

    Pohl, Benjamin; Macron, Clémence; Monerie, Paul-Arthur


    Future changes in the structure of daily rainfall, especially the number of rainy days and the intensity of extreme events, are likely to induce major impacts on rain-fed agriculture in the tropics. In Africa this issue is of primary importance, but the agreement between climate models to simulate such descriptors of rainfall is generally poor. Here, we show that the climate models used for the fifth assessment report of IPCC simulate a marked decrease in the number of rainy days, together with a strong increase in the rainfall amounts during the 1% wettest days, by the end of the 21st century over Southern Africa. These combined changes lead to an apparent stability of seasonal totals, but are likely to alter the quality of the rainy season. These evolutions are due to the superposition of slowly-changing moisture fluxes, mainly supported by increased hygrometric capacity associated with global warming, and unchanged short-term atmospheric configurations in which extreme events are embedded. This could cause enhanced floods or droughts, stronger soil erosion and nutriment loss, questioning the sustainability of food security for the 300 million people currently living in Africa south of the Equator.

  16. Regulatory factors in crustacean zooplankton assemblages in mountain lakes of northern Chilean Patagonia (38-41°S: a comparison with Bulgarian counterparts (42°N Factores reguladores en ensambles de crustáceos zooplanctónicos en lagos de montaña del norte de la Patagonia chilena (38-41°S: una comparación con sus contrapartes de Bulgaria (42°N

    Directory of Open Access Journals (Sweden)

    Patricio De los Ríos-Escalante


    Full Text Available Chilean Patagonia has protected mountainous areas with evergreen native forests; in which the lakes and rivers, of volcanic or glacial origin, are oligotrophic. In Bulgaria, there are mountainous zones with native forests and associated lakes of volcanic origin. The aim of the present study is to carry out a preliminary comparison of zooplanktonic crustaceans in lake ecosystems associated with native forests of Chilean Patagonia and of Bulgarian mountains. The study revealed that the lakes studied in Chilean Patagonia are associated mainly with Nothofagus forests; they are oligotrophic, with a low number of zooplanktonic crustacean species. Similar results were observed for Bulgarian mountain lakes associated with Fagus forests. A null model analysis of species co-occurrence was applied to the two groups of lakes, and the result revealed the absence of regulatory factors in species associations. These studies agree with similar descriptions of lakes in Andean Patagonia and New Zealand. They highlight the important role of native Nothofagus forests in Argentina and Chile, and of Fagus forests with associated soil properties in Bulgaria, in the oligotrophy of the lakes studied.La Patagonia de Chile tiene una serie de áreas protegidas con bosques nativos perennes asociados a lagos y ríos oligotróficos y de origen glacial. Por otro lado en Bulgaria hay una serie de zonas montañosas con lagos asociados de origen volcánico o glacial. El objetivo del presente trabajo es realizar una primera descripción de especies de crustáceos zooplanctónicos en ecosistemas lacustres asociados a bosques nativos en la Patagonia de Chile y en las montañas de Bulgaria. Los estudios indican que los lagos de la Patagonia de Chile están asociados principalmente con bosques de Nothofagus, mientras que similares resultados fueron observados en lagos de Bulgaria con bosques de Fagus. La regresión lineal entre concentración de clorofila y número de especies para

  17. Continental crust generated in oceanic arcs (United States)

    Gazel, Esteban; Hayes, Jorden L.; Hoernle, Kaj; Kelemen, Peter; Everson, Erik; Holbrook, W. Steven; Hauff, Folkmar; van den Bogaard, Paul; Vance, Eric A.; Chu, Shuyu; Calvert, Andrew J.; Carr, Michael J.; Yogodzinski, Gene M.


    Thin oceanic crust is formed by decompression melting of the upper mantle at mid-ocean ridges, but the origin of the thick and buoyant continental crust is enigmatic. Juvenile continental crust may form from magmas erupted above intra-oceanic subduction zones, where oceanic lithosphere subducts beneath other oceanic lithosphere. However, it is unclear why the subduction of dominantly basaltic oceanic crust would result in the formation of andesitic continental crust at the surface. Here we use geochemical and geophysical data to reconstruct the evolution of the Central American land bridge, which formed above an intra-oceanic subduction system over the past 70 Myr. We find that the geochemical signature of erupted lavas evolved from basaltic to andesitic about 10 Myr ago--coincident with the onset of subduction of more oceanic crust that originally formed above the Galápagos mantle plume. We also find that seismic P-waves travel through the crust at velocities intermediate between those typically observed for oceanic and continental crust. We develop a continentality index to quantitatively correlate geochemical composition with the average P-wave velocity of arc crust globally. We conclude that although the formation and evolution of continents may involve many processes, melting enriched oceanic crust within a subduction zone--a process probably more common in the Archaean--can produce juvenile continental crust.

  18. InSAR observations of lake loading at Yangzhuoyong Lake, Tibet: Constraints on crustal elasticity (United States)

    Zhao, Wenliang; Amelung, Falk; Doin, Marie-Pierre; Dixon, Timothy H.; Wdowinski, Shimon; Lin, Guoqing


    We use Envisat 2003-2010 InSAR imagery over Yangzhuoyong Lake in southeastern Tibet to study the elastic response of the Earth's crust to variations in lake level. The net lake level drop during our study period is ∼3 m with seasonal variations of more than 1 m. The time-series close to the lake center shows a high correlation with the lake level history. Near the lake center the unit response with respect to lake level change is 2.5 mm/m in radar line-of-sight direction, or ∼2.7 mm/yr in vertical direction, corresponding to a vertical response of ∼4.3 mm/Gt load change. We show that the observations are most sensitive to the elastic properties of the crust in the 5-15 km depth range and explain them with a layered elastic half-space model with a Young's modulus of 50 ± 9GPa Young's modulus in the top 15 km of the crust and using moduli inferred from seismology at greater depth. The inferred Young's modulus is ∼25% smaller than the seismic modulus, which we attribute to damaged rock and the presence of fluids.

  19. Eruptive behavior of the Marum/Mbwelesu lava lake, Vanuatu and comparisons with lava lakes on Earth and Io (United States)

    Radebaugh, Jani; Lopes, Rosaly M.; Howell, Robert R.; Lorenz, Ralph D.; Turtle, Elizabeth P.


    Observations from field remote sensing of the morphology, kinematics and temperature of the Marum/Mbwelesu lava lake in the Vanuatu archipelago in 2014 reveal a highly active, vigorously erupting lava lake. Active degassing and fountaining observed at the 50 m lava lake led to large areas of fully exposed lavas and rapid ( 5 m/s) movement of lava from the centers of upwelling outwards to the lake margins. These rapid lava speeds precluded the formation of thick crust; there was never more than 30% non-translucent crust. The lava lake was observed with several portable, handheld, low-cost, near-infrared imagers, all of which measured temperatures near 1000 °C and one as high as 1022 °C, consistent with basaltic temperatures. Fine-scale structure in the lava fountains and cooled crust was visible in the near infrared at 5 cm/pixel from 300 m above the lake surface. The temperature distribution across the lake surface is much broader than at more quiescent lava lakes, peaking 850 °C, and is attributed to the highly exposed nature of the rapidly circulating lake. This lava lake has many characteristics in common with other active lava lakes, such as Erta Ale in Ethiopia, being confined, persistent and high-temperature; however it was much more active than is typical for Erta Ale, which often has > 90% crust. Furthermore, it is a good analogue for the persistent, high-temperature lava lakes contained within volcanic depressions on Jupiter's moon Io, such as Pele, also believed from spacecraft and ground-based observations to exhibit similar behavior of gas emission, rapid overturn and fountaining.

  20. Impact of low-temperature, overcast and rainy weather during the reproductive growth stage on lodging resistance of rice

    National Research Council Canada - National Science Library

    Fei Weng; Wujun Zhang; Xiaoran Wu; Xia Xu; Yanfeng Ding; Ganghua Li; Zhenghui Liu; Shaohua Wang


    The objectives of this study were to explore the mechanism by which the lodging resistance of the rice population during the late growth period responds to low-temperature, overcast and rainy weather...

  1. Effects of age and season on haematological parameters of donkeys during the rainy and cold-dry seasons (United States)

    Zakari, Friday Ocheja; Ayo, Joseph Olusegun; Rekwot, Peter Ibrahim; Kawu, Mohammed Umar


    The aim of the study was to investigate the effects of age and season on haematological parameters of donkeys at rest during the rainy and cold-dry seasons. Thirty healthy donkeys divided into three groups based on their age served as the subjects. During each season, blood sample was collected from each donkey thrice, 2 weeks apart, for haematological analysis, and the dry-bulb temperature (DBT), relative humidity (RH) and temperature-humidity index (THI) were obtained thrice each day during the experimental period using standard procedures. During the rainy season, the mean DBT (33.05 ± 0.49 °C), RH (73.63 ± 1.09 %) and THI (84.39 ± 0.71) were higher ( P blood cell (RBC)], haemoglobin concentration (Hb), mean corpuscular volume (MCV), mean corpuscular haemoglobin (MCH), platelet count (PLT), leucocyte count [white blood cell (WBC)], lymphocyte count (LYM) and neutrophil/lymphocyte ratio (N/L) were higher ( P < 0.05) in adults than foals during the rainy season. The MCV, MCH, WBC, NEU, LYM and PLT of adult and yearling donkeys were higher ( P < 0.05) during the rainy than the cold-dry season. The PCV, RBC, Hb, MCV, MCH, and NEU of foals were higher in the rainy than the cold-dry season. The N/L of adult and foal donkeys were higher ( P < 0.05) in the rainy than in the cold-dry season. In conclusion, PCV, RBC, Hb and LYM were considerably higher in foals than yearlings or adults during the rainy season, while erythrocytic indices and platelet counts were higher in adults or yearlings than in foals in both seasons. Erythrocytic indices, PLT and N/L were higher in the rainy than the cold-dry season in adults, yearlings and foals.

  2. Dry and wet rainy seasons in the Mantaro river basin (Central Peruvian Andes

    Directory of Open Access Journals (Sweden)

    Y. Silva


    Full Text Available Monthly precipitation data from the period of 1970 to 2004 from 38 meteorological stations in the Mantaro river basin were used to classify the rainy seasons (September–April of each year into anomalously dry or wet, and to determine the basin-wide extent of the anomalies based on the Standardized Precipitation Index (SPI. The wet periods mostly occurred in the early 1970's and during the first half of the 1980's, except for the event that occurred in the 1993/94 period which was the strongest and most generalized in the analyzed period. The dry periods occurred mostly during the second half of the 1980's and the 1990's. Consistent with this, a negative trend in precipitation of 2% per decade was found for the rainy season, due mainly to a stronger trend (−4%/decade during the peak phase (January–March.

    Despite previously reported significant negative correlations between El Niño-Southern Oscillation (ENSO and rainfall during the peak of the rainfall season, the similar amplitude variability of precipitation during the onset phase of the rainfall season (September–December, which is uncorrelated with ENSO, participate to the reduction of the absolute correlation for the full rainfall season. Correlations between rainfall in the Mantaro basin and sea surface temperature (SST in the tropical Atlantic are significant only near the end of the rainy season, with more rain associated with a weaker north-south difference in SST in the tropical Atlantic.

  3. Pulsar glitches: The crust is not enough

    CERN Document Server

    Andersson, N; Ho, W C G; Espinoza, C M


    Pulsar glitches are traditionally viewed as a manifestation of vortex dynamics associated with a neutron superfluid reservoir confined to the inner crust of the star. In this Letter we show that the non-dissipative entrainment coupling between the neutron superfluid and the nuclear lattice leads to a less mobile crust superfluid, effectively reducing the moment of inertia associated with the angular momentum reservoir. Combining the latest observational data for prolific glitching pulsars with theoretical results for the crust entrainment we find that the required superfluid reservoir exceeds that available in the crust. This challenges our understanding of the glitch phenomenon, and we discuss possible resolutions to the problem.

  4. Stratification at the Earth's largest hyperacidic lake and its consequences (United States)

    Caudron, Corentin; Campion, Robin; Rouwet, Dmitri; Lecocq, Thomas; Capaccioni, Bruno; Syahbana, Devy; Suparjan; Purwanto, Bambang Heri; Bernard, Alain


    Volcanic lakes provide windows into the interior of volcanoes as they integrate the heat flux discharged by a magma body and condense volcanic gases. Volcanic lake temperatures and geochemical compositions therefore typically serve as warnings for resumed unrest or prior to eruptions. If acidic and hot, these lakes are usually considered to be too convective to allow any stratification within their waters. Kawah Ijen volcano, featuring the largest hyperacidic lake on Earth (volume of 27 million m3), is less homogeneous than previously thought. Hourly temperature measurements reveal the development of a stagnant layer of cold waters (<30 °C), overlying warmer and denser water (generally above 30 °C and density ∼1.083 kg/m3). Examination of 20 yrs of historical records and temporary measurements show a systematic thermal stratification during rainy seasons. The yearly rupture of stratification at the end of the rainy season causes a sudden release of dissolved gases below the cold water layer which appears to generate a lake overturn, i.e. limnic eruption, and a resonance of the lake, i.e. a seiche, highlighting a new hazard for these extreme reservoirs. A minor non-volcanic event, such as a heavy rainfall or an earthquake, may act as a trigger. The density driven overturn requires specific salinity-temperature conditions for the colder and less saline top water layer to sink into the hot saline water. Spectacular degassing occurs when the dissolved gases, progressively stored during the rainy season due to a weakened diffusion of carbon dioxide in the top layer, are suddenly released. These findings challenge the homogenization assumption at acidic lakes and stress the need to develop appropriate monitoring setups.

  5. Increasing levels of crude protein in multiple supplements for grazing beef heifers in rainy season

    Directory of Open Access Journals (Sweden)

    Lívia Vieira de Barros


    Full Text Available The objective was to evaluate the effect of multiple supplements with differents levels of crude protein (CP or mineral supplements on the nutritional parameters and performance of beef heifers grazing Uruchloa decumbens in the rainy season. A complete random design was employed. The treatments were made up of increasing levels of CP in the multiple supplements and a control treatment (MM in which animals were offered only mineral mixture. Multiple supplements contained 17; 30; 43 and 56% of CP, for treatments CP17; CP30; CP43 and CP56, respectively. Average daily gain (ADG (g was 447.7; 554.6; 638.4; 587.9; 590.4, for treatments MM, CP17; CP30; CP43 and CP56, respectively. A quadratic effect of the levels of crude protein was found (p< 0.10 on ADG. A greater intake of dry matter (DM, organic matter (OM, CP, ether extract (EE, non-fibrous carbohydrates (NFC, total digestible nutrients (TDN, and digested dry matter (p< 0.10 was found in animals supplemented with multiple supplements. Multiple supplements increased the apparent digestibility coefficient of DM, CP, EE and NFC. Supply of multiple multiple supplements for heifers grazing in medium to high quality pastures in the rainy season improves the performance of the animals.

  6. Model Development for Risk Assessment of Driving on Freeway under Rainy Weather Conditions.

    Directory of Open Access Journals (Sweden)

    Xiaonan Cai

    Full Text Available Rainy weather conditions could result in significantly negative impacts on driving on freeways. However, due to lack of enough historical data and monitoring facilities, many regions are not able to establish reliable risk assessment models to identify such impacts. Given the situation, this paper provides an alternative solution where the procedure of risk assessment is developed based on drivers' subjective questionnaire and its performance is validated by using actual crash data. First, an ordered logit model was developed, based on questionnaire data collected from Freeway G15 in China, to estimate the relationship between drivers' perceived risk and factors, including vehicle type, rain intensity, traffic volume, and location. Then, weighted driving risk for different conditions was obtained by the model, and further divided into four levels of early warning (specified by colors using a rank order cluster analysis. After that, a risk matrix was established to determine which warning color should be disseminated to drivers, given a specific condition. Finally, to validate the proposed procedure, actual crash data from Freeway G15 were compared with the safety prediction based on the risk matrix. The results show that the risk matrix obtained in the study is able to predict driving risk consistent with actual safety implications, under rainy weather conditions.

  7. Molecular mobility in crispy bread crust

    NARCIS (Netherlands)

    Nieuwenhuijzen, van N.H.


    The aim of the PhD study on molecular mobility was to analyse the molecular grounds for the deterioration of crispy/crunchy characteristics of cellular solid foods. A fresh baguette for example has a crispy crust and a moist and soft interior. Moisture migrates from crumb to crust. Already at a wate

  8. Eocene deep crust at Ama Drime, Tibet

    DEFF Research Database (Denmark)

    Kellett, Dawn; Cottle, John; Smit, Matthijs Arjen


    burial and exhumation of a cold subducted slab. The rocks instead resulted from crustal thickening during the early stages of continental collision, and resided in the lower-middle crust for >20 m.y. before they were exhumed and reheated. These new data provide solid evidence for the Indian crust having...

  9. Water Uptake Mechanism in Crispy Bread Crust

    NARCIS (Netherlands)

    Nieuwenhuijzen, van N.H.; Meinders, M.B.J.; Tromp, R.H.; Hamer, R.J.; Vliet, van T.


    Crispness is an important quality characteristic of dry solid food products such as crispy rolls. Its retention is directly related to the kinetics of water uptake by the crust. In this study, a method for the evaluation of the water sorption kinetics in bread crust is proposed. Two different sorpti

  10. Variabilities in Rainfall Onset, Cessation and Length of Rainy Season for the Various Agro-Ecological Zones of Ghana

    Directory of Open Access Journals (Sweden)

    Leonard K. Amekudzi


    Full Text Available This paper examines the onset and cessation dates of the rainy season over Ghana using rain gauge data from the Ghana Meteorological Agency (GMet over the period of 1970–2012. The onset and cessation dates were determined from cumulative curves using the number of rainy days and rainfall amount. In addition, the inter-annual variability of the onset and cessation dates for each climatic zone was assessed using wavelet analysis. A clear distinction between the rainfall characteristics and the length of the rainy season in the various climatic zones is discussed. The forest and coastal zones in the south had their rainfall onset from the second and third dekads of March. The onset dates of the transition zone were from the second dekad of March to the third dekad of April. Late onset, which starts from the second dekad of April to the first dekad of May, was associated with the savannah zone. The rainfall cessation dates in the forest zone were in the third dekad of October to the first dekad of November, and the length of the rainy season was within 225–240 days. The cessation dates of the coastal zone were within the second and third dekad of October, and the length of rainy season was within 210–220 days. Furthermore, the transition zone had cessation dates in the second to third dekad of October, and the length of the rainy season was within 170–225 days. Lastly, the savannah zone had cessation dates within the third dekad of September to the first dekad of October, and the length of rainy season was within 140–180 days. The bias in the rainfall onset, cessation and length of the rainy season was less than 10 days across the entire country, and the root mean square error (RMSE was in the range of 5–25 days. These findings demonstrate that the onset derived from the cumulative rainfall amount and the rainy days are in consistent agreement. The wavelet power spectrum and its significant peaks showed evidence of variability in the

  11. Lake Cadagno

    DEFF Research Database (Denmark)

    Tonolla, Mauro; Storelli, Nicola; Danza, Francesco


    Lake Cadagno (26 ha) is a crenogenic meromictic lake located in the Swiss Alps at 1921 m asl with a maximum depth of 21 m. The presence of crystalline rocks and a dolomite vein rich in gypsum in the catchment area makes the lake a typical “sulphuretum ” dominated by coupled carbon and sulphur cyc...


    Directory of Open Access Journals (Sweden)

    Karistsapol Nooprom


    Full Text Available Broccoli (Brassica oleracea var. italica is one of the most popular vegetable crops in many countries of the world as its nutritional importance. It has the most exacting climatic and cultural requirements, which limit its commercial production to a few favored locations. In Thailand, broccoli has been expending in recent years and amount of increasing production. It is best planted in the North where the weather is cool or in the Northeast during winter season. The South has tropical climates and raining all year round, but farmers can produce broccoli during early summer by using the heat-tolerant varieties. Although the broccoli is highly priced and still wanted by consumers in the rainy season, the farmers might not choose to grow as the problems with low productivity. Thus, the selection of suitable planting dates and varieties is crucial for successful cultivation during rainy season in the South. The experiment was performed to evaluate the effects of planting dates and broccoli varieties on their growth and yield responses during rainy season. Four broccoli varieties: ‘Top Green’, ‘Green Queen’, ‘Yok Kheo’ and ‘Special’ were plated for six planting dates: July, August, September, October, November and December at Prince of Songkla University, Thailand, between July, 2011 and January, 2012. Split-plot in a randomized complete block design was used in this experiment with four replications. This study showed that four broccoli varieties had highly seedling survival rates of 70.31-99.22% when planting in July-December except ‘Special’ of 54.68% when planting in August. ‘Yok Kheo’ had plant diameter of 67.54-75.24 cm when planting in July and December, not significantly different from ‘Top Green’ planting in July, August and November of 69.15-71.24 cm and ‘Green Queen’ in July and September of 68.69-68.88 cm. The highest total yield was obtained by ‘Yok Kheo

  13. Analysis of non-rainy attenuation on earth-space path in Ota, Southwest Nigeria (United States)

    Omotosho, T. V.; Akinwumi, S. A.; Usikalu, M. R.; Ometan, O. O.; Adewusi, M. O.; Abdullah, M.


    Propagation effects due to atmospheric gases and tropospheric scintillation requires accurate modelling in the design of satellite communication systems. The combination of the two attenuation phenomena was observed within the period of August 2014 to December 2015. The result of this paper presents the on-going observation and data analysis of non-rainy attenuation on earth-space path in Ota, Southwest Nigeria. Results of clear-sky attenuation vary between 0 dBm and 4.85 dBm in January and February 2015 respectively. While a value of 4.23 dBm and 4.75 dBm were observed in October 2014 and 2015 respectively. The results will be useful for satellite communication system design and will be submitted to ITU-R Study group 3 Databank.


    Directory of Open Access Journals (Sweden)

    Petre GÂŞTESCU


    Full Text Available Limnology is a border discipline between geography, hydrology and biology, and is also closely connected with other sciences, from it borrows research methods. Physical limnology (the geography of lakes, studies lake biotopes, and biological limnology (the biology of lakes, studies lake biocoenoses. The father of limnology is the Swiss scientist F.A. Forel, the author of a three-volume entitled Le Leman: monographie limnologique (1892-1904, which focuses on the geology physics, chemistry and biology of lakes. He was also author of the first textbook of limnology, Handbuch der Seenkunde: allgemeine Limnologie,(1901. Since both the lake biotope and its biohydrocoenosis make up a single whole, the lake and lakes, respectively, represent the most typical systems in nature. They could be called limnosystems (lacustrine ecosystems, a microcosm in itself, as the American biologist St.A. Forbes put it (1887.

  15. Making continental crust: The sanukitoid connection

    Institute of Scientific and Technical Information of China (English)

    Yoshiyuki TATSUMI


    The average continental crust possesses intermediate compositions that typify arc magmatism and as a result it is believed to have been created at ancient convergent plate boundaries. One possible mechanism for intermediate continental crust formation is the direct production of andesitic melts in the upper mantle. Sanukitoids, which characterize the Setouchi volcanic belt, SW Japan, include unusually high-Mg andesites (HMA). They were generated by slab melting and subsequent melt-mantle interactions under unusual tectonic settings such as where warm lithosphere subducts into hot upper mantle. Such conditions would have existed in the Archean. Hydrous HMA magmas are likely to have solidified within the crust to form HMA plutons, which were then remelted to produce differentiated sanukitoids. At present, generation and differentiation of HMA magmas may be taking place in the Izu-Bonin-Mariana arc-trench system (IBM), because (1) HMA magmatism characterizes the initial stages of the iBM evolution and (2) the IBM middle crust exhibits Vp identical to that of the bulk continental crust. Vp estimates for plutonic rocks with HMA compositions support this. However tonalitic composition for middle-crust-forming rocks cannot be ruled out, suggesting an alternative possibility that the continental crust has been created by differentiation of mantle-derived basaltic magmas.

  16. Attributing the Risk of Late Onset of the Rainy Season in Southern Africa to Climate Change (United States)

    Wolski, P.; Stone, D. A.; Tadross, M. A.; Hewitson, B.; Wehner, M. F.


    Rainfed subsistence agriculture in Sub-Saharan Africa accounts for approximately 96% of all cropland. This, combined with strong intra-seasonal and interannual variability of rains makes food production sensitive to climate variations, and increases the potential and frequent occurrence of climate-triggered famines. Farmers often identify the timing of the onset of the growing season (in many areas dependent predominantly on rainfall) as a key climate characteristic which influences crop yields, influences planting activities, and can be used to adapt to changing seasonal conditions without requiring additional resources. It is thus important to understand factors affecting the timing of the onset of rains, particularly how anthropogenic climate change may increase the risk of later onsets. Here, we present a study designed to assess the level of influence of anthropogenic CO2 emissions on the risk of late onset in southern Africa. Considering numerous definitions of rainy season onset, we use one that describes onset related to the growing of maize, as it is the most wide-ranging and consumed staple in the region. Attribution is done using a risk-based event attribution methodology in which we use dedicated simulations by AGCMs (HadAM3p-N96 and CAM5.1-1degree) performed in the framework of the Climate of the 20th Century Plus (C20C+) Detection and Attribution Project. These simulations enable comparison of event (in our case the timing of the onset of a particular rainy season) probabilities under real world climates with those under a climate that might have been had human activities not emitted greenhouse gases. The fraction of risk of later onsets, attributable to an increase in greenhouse gases, is done in a spatially-explicit way for onset events derived from observed and reanalysis data for the 2007-2014 period.

  17. Microphytic crusts: 'topsoil' of the desert (United States)

    Belnap, Jayne


    Deserts throughout the world are the home of microphytic, or cryptogamic, crusts. These crusts are dominated by cyanobacteria, previously called blue-green algae, and also include lichens, mosses, green algae, microfungi and bacteria. They are critical components of desert ecosystems, significantly modifying the surfaces on which they occur. In the cold deserts of the Colorado Plateau (including parts of Utah, Arizona, Colorado, and New Mexico), these crusts are extraordinarily well-developed, and may represent 70-80% of the living ground cover.

  18. Eocene deep crust at Ama Drime, Tibet

    DEFF Research Database (Denmark)

    Kellett, Dawn; Cottle, John; Smit, Matthijs Arjen


    for burial of the lower Indian crust beneath Tibet reported from the central-eastern Himalaya. Granulite-facies overprinting followed at ca. 15–13 Ma, as indicated by U-Pb zircon ages. Unlike ultrahigh-pressure eclogites of the northwest Himalaya, the Ama Drime eclogites are not characteristic of rapid...... burial and exhumation of a cold subducted slab. The rocks instead resulted from crustal thickening during the early stages of continental collision, and resided in the lower-middle crust for >20 m.y. before they were exhumed and reheated. These new data provide solid evidence for the Indian crust having...

  19. Crust rheology, slab detachment and topography (United States)

    Duretz, T.; Gerya, T. V.


    The collision between continents following the closure of an ocean can lead to the subduction of continental crust. The introduction of buoyant crust within subduction zones triggers the development of extensional stresses in slabs which eventually result in their detachment. The dynamic consequences of slab detachment affects the development of topography, the exhumation of high-pressure rocks and the geodynamic evolution of collision zones. We employ two-dimensional thermo-mechanical modelling in order to study the importance of crustal rheology on the evolution of spontaneous subduction-collision systems and the occurrence of slab detachment. The modelling results indicate that varying the rheological structure of the crust can results in a broad range of collisional evolutions involving slab detachment, delamination (associated to slab rollback), or the combination of both mechanisms. By enhancing mechanical coupling at the Moho, a strong crust leads to the deep subduction of the crust (180 km). These collisions are subjected to slab detachment and subsequent coherent exhumation of the crust accommodated by eduction (inversion of subduction sense) and thrusting. In these conditions, slab detachment promotes the development of a high (> 4.5 km) and narrow (delamination of the lithosphere, preventing slab detachment to occur. Further shortening leads to buckling and thickening of the crust resulting in the development of topographic bulging on the lower plate. Collisions involving rheologically layered crust are characterised by a decoupling level at mid-crustal depths. These initial condition favours the delamination of the upper crust as well as the deep subduction of the lower crust. These collisions are thus successively affected by delamination and slab detachment and both processes contribute to the exhumation of the subducted crust. A wide (> 200 km) topographic plateau develops as the results of the buoyant extrusion of the upper crust onto the foreland

  20. Biogenic crust dynamics on sand dunes

    CERN Document Server

    Kinast, Shai; Yizhaq, Hezi; Ashkenazy, Yosef


    Sand dunes are often covered by vegetation and biogenic crusts. Despite their significant role in dune stabilization, biogenic crusts have rarely been considered in studies of dune dynamics. Using a simple model, we study the existence and stability ranges of different dune-cover states along gradients of rainfall and wind power. Two ranges of alternative stable states are identified: fixed crusted dunes and fixed vegetated dunes at low wind power, and fixed vegetated dunes and active dunes at high wind power. These results suggest a cross-over between two different forms of desertification.

  1. The importance of bank vole density and rainy winters in predicting nephropathia epidemica incidence in Northern Sweden.

    Directory of Open Access Journals (Sweden)

    Hussein Khalil

    Full Text Available Pathogenic hantaviruses (family Bunyaviridae, genus Hantavirus are rodent-borne viruses causing hemorrhagic fever with renal syndrome (HFRS in Eurasia. In Europe, there are more than 10,000 yearly cases of nephropathia epidemica (NE, a mild form of HFRS caused by Puumala virus (PUUV. The common and widely distributed bank vole (Myodes glareolus is the host of PUUV. In this study, we aim to explain and predict NE incidence in boreal Sweden using bank vole densities. We tested whether the number of rainy days in winter contributed to variation in NE incidence. We forecast NE incidence in July 2013-June 2014 using projected autumn vole density, and then considering two climatic scenarios: 1 rain-free winter and 2 winter with many rainy days. Autumn vole density was a strong explanatory variable of NE incidence in boreal Sweden in 1990-2012 (R2 = 79%, p<0.001. Adding the number of rainy winter days improved the model (R2 = 84%, p<0.05. We report for the first time that risk of NE is higher in winters with many rainy days. Rain on snow and ground icing may block vole access to subnivean space. Seeking refuge from adverse conditions and shelter from predators, voles may infest buildings, increasing infection risk. In a rainy winter scenario, we predicted 812 NE cases in boreal Sweden, triple the number of cases predicted in a rain-free winter in 2013/2014. Our model enables identification of high risk years when preparedness in the public health sector is crucial, as a rainy winter would accentuate risk.

  2. The importance of bank vole density and rainy winters in predicting nephropathia epidemica incidence in Northern Sweden. (United States)

    Khalil, Hussein; Olsson, Gert; Ecke, Frauke; Evander, Magnus; Hjertqvist, Marika; Magnusson, Magnus; Löfvenius, Mikaell Ottosson; Hörnfeldt, Birger


    Pathogenic hantaviruses (family Bunyaviridae, genus Hantavirus) are rodent-borne viruses causing hemorrhagic fever with renal syndrome (HFRS) in Eurasia. In Europe, there are more than 10,000 yearly cases of nephropathia epidemica (NE), a mild form of HFRS caused by Puumala virus (PUUV). The common and widely distributed bank vole (Myodes glareolus) is the host of PUUV. In this study, we aim to explain and predict NE incidence in boreal Sweden using bank vole densities. We tested whether the number of rainy days in winter contributed to variation in NE incidence. We forecast NE incidence in July 2013-June 2014 using projected autumn vole density, and then considering two climatic scenarios: 1) rain-free winter and 2) winter with many rainy days. Autumn vole density was a strong explanatory variable of NE incidence in boreal Sweden in 1990-2012 (R2 = 79%, p<0.001). Adding the number of rainy winter days improved the model (R2 = 84%, p<0.05). We report for the first time that risk of NE is higher in winters with many rainy days. Rain on snow and ground icing may block vole access to subnivean space. Seeking refuge from adverse conditions and shelter from predators, voles may infest buildings, increasing infection risk. In a rainy winter scenario, we predicted 812 NE cases in boreal Sweden, triple the number of cases predicted in a rain-free winter in 2013/2014. Our model enables identification of high risk years when preparedness in the public health sector is crucial, as a rainy winter would accentuate risk.

  3. Microbial Response to UV Exposure and Nitrogen Limitation in Desert Soil Crusts (United States)

    Fulton, J. M.; Van Mooy, B. A.


    Microbiotic soil crusts have diverse biomarker distributions and C and N stable isotopic compositions that covary with soil type. Sparse plant cover and the relative lack of soil disturbance in arid/semi-arid landscapes allows populations of soil cyanobacteria to develop along with fungi and heterotrophic bacteria. Microbial communities in this extreme environment depend in part on the production of scytonemin, a UV protective pigment, by cyanobacteria near the top of the crust. N limitation of microbial growth also affects soil crust population dynamics, increasing the requirement of N2fixation by diazotrophic cyanobacteria. We collected 56 soil crust samples from 27 locations throughout the Great Salt Lake Desert, including four transects spanning high-elevation, erosion-dominated soils to lower elevation soils dominated by silt-accumulation. Erosion-dominated soil surfaces included rounded gravel and cobbles; in the interstices there were poorly-developed microbiotic crusts on sandy loam with low δ15N values near 0‰ that point toward microbial growth dependent on cyanobacterial N2 fixation. Nutrients regenerated by heterotrophic bacteria may have been eroded from the system, providing a positive feedback for N2 fixation. High scytonemin:chlorophyll a ratios suggest that cyanobacteria required enhanced protection from UV damage in these crusts. A similar increase in scytonemin:chlorophyll a ratio during soil crust rehydration experiments also points toward the importance of UV protection. Glycolipid:phospholipid ratios were lowest where N2 fixation was favored, however, suggesting that the cyanobacterial population was relatively small, possibly because of the metabolic cost of N2fixation. Microbiotic crusts on silt loam soils, on the other hand, had higher δ15N values between 3.5 and 7.8‰, consistent with heterotrophic growth and nutrient recycling. Lower scytonemin:chlorophyll a ratios suggest that relatively high photosynthetic activity was supported in

  4. Temperature distribution in magnetized neutron star crusts

    CERN Document Server

    Geppert, U; Page, D


    We investigate the influence of different magnetic field configurations on the temperature distribution in neutron star crusts. We consider axisymmetric dipolar fields which are either restricted to the stellar crust, ``crustal fields'', or allowed to penetrate the core, ``core fields''. By integrating the two-dimensional heat transport equation in the crust, taking into account the classical (Larmor) anisotropy of the heat conductivity, we obtain the crustal temperature distribution, assuming an isothermal core. Including quantum magnetic field effects in the envelope as a boundary condition, we deduce the corresponding surface temperature distributions. We find that core fields result in practically isothermal crusts unless the surface field strength is well above $10^{15}$ G while for crustal fields with surface strength above a few times $10^{12}$ G significant deviations from isothermality occur at core temperatures inferior or equal to $10^8$ K. At the stellar surface, the cold equatorial region produce...

  5. Neutron Star Crust and Molecular Dynamics Simulation

    CERN Document Server

    Horowitz, C J; Schneider, A; Berry, D K


    In this book chapter we review plasma crystals in the laboratory, in the interior of white dwarf stars, and in the crust of neutron stars. We describe a molecular dynamics formalism and show results for many neutron star crust properties including phase separation upon freezing, diffusion, breaking strain, shear viscosity and dynamics response of nuclear pasta. We end with a summary and discuss open questions and challenges for the future.

  6. Early formation of evolved asteroidal crust. (United States)

    Day, James M D; Ash, Richard D; Liu, Yang; Bellucci, Jeremy J; Rumble, Douglas; McDonough, William F; Walker, Richard J; Taylor, Lawrence A


    Mechanisms for the formation of crust on planetary bodies remain poorly understood. It is generally accepted that Earth's andesitic continental crust is the product of plate tectonics, whereas the Moon acquired its feldspar-rich crust by way of plagioclase flotation in a magma ocean. Basaltic meteorites provide evidence that, like the terrestrial planets, some asteroids generated crust and underwent large-scale differentiation processes. Until now, however, no evolved felsic asteroidal crust has been sampled or observed. Here we report age and compositional data for the newly discovered, paired and differentiated meteorites Graves Nunatak (GRA) 06128 and GRA 06129. These meteorites are feldspar-rich, with andesite bulk compositions. Their age of 4.52 +/- 0.06 Gyr demonstrates formation early in Solar System history. The isotopic and elemental compositions, degree of metamorphic re-equilibration and sulphide-rich nature of the meteorites are most consistent with an origin as partial melts from a volatile-rich, oxidized asteroid. GRA 06128 and 06129 are the result of a newly recognized style of evolved crust formation, bearing witness to incomplete differentiation of their parent asteroid and to previously unrecognized diversity of early-formed materials in the Solar System.

  7. Distribution of Nile perch Lates niloticus in southern Lake Victoria is determined by depth and dissolved oxygen concentrations

    NARCIS (Netherlands)

    Goudswaard, P.C.; Katunzi, E.F.B.; Wanink, J.H.; Witte, F.


    Although Nile perch Lates niloticus is assumed to be sensitive to low oxygen concentrations, it was found in deep water in Lake Victoria, where oxygen depletion is common during the rainy season. Since factors determining Nile perch distribution are not well understood its spatial distribution in

  8. 76 FR 45311 - International Joint Commission Public Hearings on Binational Management of Lake of the Woods and... (United States)


    ... International Joint Commission Public Hearings on Binational Management of Lake of the Woods and Rainy River Watershed The International Joint Commission (IJC) will hold public hearings on the final report of its.... Section, International Joint Commission, 2000 L Street, NW., Suite 615, Washington, DC 20440, Fax:...

  9. Modeling of wastewater quality in an urban area during festival and rainy days. (United States)

    Obaid, H A; Shahid, S; Basim, K N; Chelliapan, S


    Water pollution during festival periods is a major problem in all festival cities across the world. Reliable prediction of water pollution is essential in festival cities for sewer and wastewater management in order to ensure public health and a clean environment. This article aims to model the biological oxygen demand (BOD(5)), and total suspended solids (TSS) parameters in wastewater in the sewer networks of Karbala city center during festival and rainy days using structural equation modeling and multiple linear regression analysis methods. For this purpose, 34 years (1980-2014) of rainfall, temperature and sewer flow data during festival periods in the study area were collected, processed, and employed. The results show that the TSS concentration increases by 26-46 mg/l while BOD(5) concentration rises by 9-19 mg/l for an increase of rainfall by 1 mm during festival periods. It was also found that BOD(5) concentration rises by 4-17 mg/l for each increase of 10,000 population.

  10. Superiority of Filtered Tailings Storage Facility to Conventional Tailings Impoundment in Southern Rainy Regions of China

    Directory of Open Access Journals (Sweden)

    Shuai Li


    Full Text Available In order to evaluate the superiority of a filtered tailings storage facility (FTSF to conventional tailings impoundment in the southern rainy regions of China (SRRC, the tailings slurry leakage and pollution accident occurring at the wet tailings dam (WTD of Yinshan were analyzed, the properties of the tailings were tested in a laboratory, and the possibility of tailings liquefaction was evaluated. Comparisons of the slope stabilities of the filtered tailings dam (FTD and WTD in normal operation, flood, continuous rainfall, and earthquake situations were simulated using the Slide software. The results show that the FTD has less chance of seepage, lower failure probability, and limited potential destructiveness than the WTD with average slope safety factors of 2.120 for normal operation, 1.919 for flooding, 1.204 for continuous rainfall, and 1.724 for a magnitude-6.0 earthquake. The disaster chain model of the WTD of Yinshan belongs to the bursting and slippage chain. As the most safe and effective active prevention measure, the FTSF has the advantages of saving water, protecting the environment, improving its stability in flood and rainfall situations, and reducing the dam failure probability and potential losses, which is greatly applicable to the SRRC.

  11. Multiscale characteristics of the rainy season rainfall and interdecadal decaying of summer monsoon in North China

    Institute of Scientific and Technical Information of China (English)

    DAI Xingang; WANG Ping; CHOU Jifan


    This paper focuses on the rainfall spectrum and its evolution of North China in rainy season with summer monsoon decaying in interdecadal time scale. The interannual component of the rainfall is the dominant part, accounting for 85% of the total variance, and has been changed significantly during the last 30 years. According to wavelet analysis its 5a periodic spectrum suddenly disappeared in the late 1960s, and its biennial oscillation gradually become weaker and weaker since 1970, accompanied by the summer monsoon decaying. Contrarily, the interdecadal component is principal in the summer monsoon over North China and is very similar to the counterpart of the rainfall. Their interdecadal parts are significantly correlated, and the correlation coefficient is nearly equal to the one of the original sequences. Besides, the dry and wet climate alternated with the monsoon abrupt changes in the 1960s and the 1970s over East Asia, apart from North China, climate drifted from a light drought to a severe drought during the past 30 years.

  12. Molecular Epidemiology of Cholera Outbreaks during the Rainy Season in Mandalay, Myanmar. (United States)

    Roobthaisong, Amonrattana; Okada, Kazuhisa; Htun, Nilar; Aung, Wah Wah; Wongboot, Warawan; Kamjumphol, Watcharaporn; Han, Aye Aye; Yi, Yi; Hamada, Shigeyuki


    Cholera, caused by Vibrio cholerae, remains a global threat to public health. In Myanmar, the availability of published information on the occurrence of the disease is scarce. We report here that cholera incidence in Mandalay generally exhibited a single annual peak, with an annual average of 312 patients with severe dehydration over the past 5 years (since 2011) and was closely associated with the rainy season. We analyzed cholera outbreaks, characterized 67 isolates of V. cholerae serogroup O1 in 2015 from patients from Mandalay, and compared them with 22 V. cholerae O1 isolates (12 from Mandalay and 10 from Yangon) in 2014. The isolates carried the classical cholera toxin B subunit (ctxB), the toxin-co-regulated pilus A (tcpA) of Haitian type, and repeat sequence transcriptional regulator (rstR) of El Tor type. Two molecular typing methods, pulsed-field gel electrophoresis and multiple-locus variable-number tandem repeat analysis (MLVA), differentiated the 89 isolates into seven pulsotypes and 15 MLVA profiles. Pulsotype Y15 and one MLVA profile (11, 7, 7, 16, 7) were predominantly found in the isolates from cholera outbreaks in Mandalay, 2015. Pulsotypes Y11, Y12, and Y15 with some MLVA profiles were detected in the isolates from two remote areas, Mandalay and Yangon, with temporal changes. These data suggested that cholera spread from the seaside to the inland area in Myanmar.

  13. Constraints on the upper crustal magma reservoir beneath Yellowstone Caldera inferred from lake-seiche induced strain observations (United States)

    Luttrell, Karen; Mencin, David; Francis, Oliver; Hurwitz, Shaul


    Seiche waves in Yellowstone Lake with a ~78-minute period and heights 11 Pa s. These strain observations and models provide independent evidence for the presence of partially molten material in the upper crust, consistent with seismic tomography studies that inferred 10%–30% melt fraction in the upper crust.

  14. Geomorphology, hydrology, and ecology of Lake Urema, central Mozambique, with focus on lake extent changes (United States)

    Böhme, Beate; Steinbruch, Franziska; Gloaguen, Richard; Heilmeier, Hermann; Merkel, Broder

    Lake Urema is one of the most important ecological features of Gorongosa National Park, located in central Mozambique, in the East African Rift System. Understanding hydrology and ecology of the lake and its tributaries is particularly important for the conservation of the Park’s floodplain habitats and its biodiversity. There are concerns that hydrological boundary conditions and ecology of Lake Urema have changed in recent years. Possible causes for this change include climatic and land use changes as well as tectonic and geomorphological processes. In this study, a multi-temporal and multi-disciplinary approach was applied to investigate the dynamics and control mechanisms of Lake Urema. Principal methods comprised remote sensing analyses of time series of Landsat and ASTER data, geomorphological interpretations of a Digital Terrain Model (DTM) as well as field investigations such as analyses of water quality and sediment composition. The waters of Lake Urema have a low mineralization and pH values approximately neutral. The spatially dominant sediment type has a pure clay texture consisting of kaolinite and smectite. The sandy type consists of quartz, kali felspar, and plagioclase. The results of the supervised classifications for the satellite images from 1979 to 2000 showed that the lake’s extent ranged between 17 km 2 (09/1995) and 25 km 2 (08/1979). Above average rainfall was responsible for the extreme lake size in May 1997 (104 km 2). The interpretations of the Digital Terrain Model demonstrated that alluvial fans limit the Urema basin from all sides and make Lake Urema a form of “reservoir lake”. The control mechanisms of the hydrological regime of Lake Urema, such as the contribution of groundwater, are not yet fully understood. The lake’s condition during the rainy season was not investigated. In the future, investigations of the sources and amounts of sediment input into the lake should be conducted.

  15. Do water level fluctuations influence production of walleye and yellow perch young-of-the-year in large northern lakes? (United States)

    Larson, James H.; Staples, David F.; Maki, Ryan P.; Vallazza, Jon M.; Knights, Brent C.; Peterson, Kevin E.


    Many ecological processes depend on the regular rise and fall of water levels (WLs), and artificial manipulations to WL regimes can impair important ecosystem services. Previous research has suggested that differences in WL between late summer and early spring may alter the suitability of shoals used by Walleyes Sander vitreus for spawning. Other species, such as the Yellow Perch Perca flavescens, are unlikely to be affected in the same way by WL fluctuations because their spawning requirements are quite different. We used 11–23 years of data from six northern Minnesota lakes to assess the effects of WL fluctuations on the abundances of young-of-the-year (age-0) Walleyes and Yellow Perch. In two lakes (Rainy Lake and Lake Kabetogama), a change in WL management occurred in 2000, after which these lakes saw increased age-0 Walleye abundance, while the other study lakes experienced decreases or no change. Rainy Lake and Lake Kabetogama also had increases in age-0 Yellow Perch, but another study lake did also. We used partial least-squares regression to assess whether WL metrics were associated with variation in age-0 Walleye and Yellow Perch abundances, but WL metrics were seldom associated with age-0 abundance for either species. Our analysis suggested a potential influence of WL regulation on age-0 Walleye abundance, but we found no evidence that early spring access to spawning shoals was the mechanism by which this occurred.

  16. The Continental Crust: A Geophysical Approach (United States)

    Christensen, Nikolas I.

    Nearly 80 years ago, Yugoslavian seismologist Andrija Mohorovicic recognized, while studying a Balkan earthquake, that velocities of seismic waves increase abruptly at a few tens of kilometers depth , giving rise to the seismological definition of the crust. Since that discovery, many studies concerned with the nature of both the continental and oceanic crusts have appeared in the geophysical literature.Recently, interest in the continental crust has cascaded. This is largely because of an infusion of new data obtained from major reflection programs such as the Consortium for Continental Reflection Profiling (COCORP) and British Institutions Reflection Profiling Syndicate (BIRPS) and increased resolution of refraction studies. In addition, deep continental drilling programs are n ow in fashion. The Continental Crust: A Geophysical Approach is a summary of present knowledge of the continental crust. Meissner has succeeded in writing a book suited to many different readers, from the interested undergraduate to the professional. The book is well documented , with pertinent figures and a complete and up-to-date reference list.

  17. Growth of the lower continental crust (United States)

    Rudnick, Roberta L.


    One of the largest uncertainties in crustal composition and growth models is the nature of the lower continental crust. Specifically, by what processes is it formed and modified, and when is it formed, particularly in reference to the upper crust? The main reason for this lack of information is the scarcity of lower crustal rock samples. These are restricted to two types: rocks which outcrop in granulite facies terrains and granulite facies xenoliths which are transported to the earth's surface by young volcanics. The important conclusions arising from the xenolith studies are: the majority of mafic lower crustal xenoliths formed through cumulate process, resitic xenoliths are rare; and formation and metamorphism of the deep crust is intimately linked to igneous activity and/or orogeny which are manifest in one form or another at the earth's surface. Therefore, estimates of crustal growth based on surface exposures is representative, although the proportion of remobilized pre-existing crust may be significantly greater at the surface than in the deep crust.

  18. Crust formation in drying colloidal suspensions

    KAUST Repository

    Style, R. W.


    During the drying of colloidal suspensions, the desiccation process causes the suspension near the air interface to consolidate into a connected porous matrix or crust. Fluid transport in the porous medium is governed by Darcy\\'s law and the equations of poroelasticity, while the equations of colloid physics govern processes in the suspension. We derive new equations describing this process, including unique boundary conditions coupling the two regions, yielding a moving-boundary model of the concentration and stress profiles during drying. A solution is found for the steady-state growth of a nedimensional crust during constant evaporation rate from the surface. The solution is used to demonstrate the importance of the system boundary conditions on stress profiles and diffusivity in a drying crust. © 2011 The Royal Society.

  19. The Early Evolution of Mars' Crust (United States)

    Samuel, H.; Baratoux, D.; Kurita, K.


    The Mars crustal density and thickness have been recently re-evaluated using petrological constraints from remote sensing, in-situ data, and SNC meteorites. This work indicates that the present-day Martian crust is denser and thicker than previously proposed if essentially basaltic in composition. As a consequence, the average crustal thickness would be commensurable with the depth of the basalt/eclogite transition, re-opening the question of crustal recycling on Early Mars and more generally throughout all its history. We have therefore investigated the conditions under which a thick ancient crust with an eclogitic root could survive through the history of Mars using numerical modelling. Delamination may occur if the combination of poorly constrained physical parameters induces the presence of gravitationally unstable layers and favors a rheological decoupling. To study the conditions and the time scales for the occurrence of crustal delamination on Mars, we investigated the influence of critical parameters for a plausible range of values corresponding to the Martian mantle. For each case we follow the dynamic evolution over geological times of a three-layer system (i.e., crust-mantle with a distinction between low pressure, buoyant basaltic crust and higher pressure, denser eclogitic material). We systematically varied four governing parameters within plausible ranges: (1) the basalt-eclogite transition depth, (2) the density difference between the mantle and the basaltic crust, (3) the density difference between the eclogitic crust and the lithosphere & mantle, (4) the viscous rheology. These experiments allow determining the average Martian crustal thickness at early and late evolutionary stages.

  20. Hafnium isotope stratigraphy of ferromanganese crusts (United States)

    Lee, D.-C.; Halliday, A.N.; Hein, J.R.; Burton, K.W.; Christensen, J.N.; Gunther, D.


    A Cenozoic record of hafnium isotopic compositions of central Pacific deep water has been obtained from two ferromanganese crusts. The crusts are separated by more than 3000 kilometers but display similar secular variations. Significant fluctuations in hafnium isotopic composition occurred in the Eocene and Oligocene, possibly related to direct advection from the Indian and Atlantic oceans. Hafnium isotopic compositions have remained approximately uniform for the past 20 million years, probably reflecting increased isolation of the central Pacific. The mechanisms responsible for the increase in 87Sr/86Sr in seawater through the Cenozoic apparently had no effect on central Pacific deep-water hafnium.

  1. Temporal dynamics of airborne fungi in Havana (Cuba) during dry and rainy seasons: influence of meteorological parameters (United States)

    Almaguer, Michel; Aira, María-Jesús; Rodríguez-Rajo, F. Javier; Rojas, Teresa I.


    The aim of this paper was to determine for first time the influence of the main meteorological parameters on the atmospheric fungal spore concentration in Havana (Cuba). This city is characterized by a subtropical climate with two different marked annual rainfall seasons during the year: a "dry season" and a "rainy season". A nonviable volumetric methodology (Lanzoni VPPS-2000 sampler) was used to sample airborne spores. The total number of spores counted during the 2 years of study was 293,594, belonging to 30 different genera and five spore types. Relative humidity was the meteorological parameter most influencing the atmospheric concentration of the spores, mainly during the rainy season of the year. Winds coming from the SW direction also increased the spore concentration in the air. In terms of spore intradiurnal variation we found three different patterns: morning maximum values for Cladosporium, night peaks for Coprinus and Leptosphaeria, and uniform behavior throughout the whole day for Aspergillus/ Penicillium."

  2. Relationships between Rainy Days, Mean Daily Intensity, and Seasonal Rainfall over the Koyna Catchment during 1961–2005 (United States)

    Nandargi, S.; Mulye, S. S.


    There are limitations in using monthly rainfall totals in studies of rainfall climatology as well as in hydrological and agricultural investigations. Variations in rainfall may be considered to result from frequency changes in the daily rainfall of the respective regime. In the present study, daily rainfall data of the stations inside the Koyna catchment has been analysed for the period of 1961–2005 to understand the relationship between the rain and rainy days, mean daily intensity (MDI) and seasonal rainfall over the catchment on monthly as well as seasonal scale. Considering the topographical location of the catchment, analysis of seasonal rainfall data of 8 stations suggests that a linear relationship fits better than the logarithmic relationship in the case of seasonal rainfall versus mean daily intensity. So far as seasonal rainfall versus number of rainy days is considered, the logarithmic relationship is found to be better. PMID:22654646

  3. Relationships between Rainy Days, Mean Daily Intensity, and Seasonal Rainfall over the Koyna Catchment during 1961–2005

    Directory of Open Access Journals (Sweden)

    S. Nandargi


    Full Text Available There are limitations in using monthly rainfall totals in studies of rainfall climatology as well as in hydrological and agricultural investigations. Variations in rainfall may be considered to result from frequency changes in the daily rainfall of the respective regime. In the present study, daily rainfall data of the stations inside the Koyna catchment has been analysed for the period of 1961–2005 to understand the relationship between the rain and rainy days, mean daily intensity (MDI and seasonal rainfall over the catchment on monthly as well as seasonal scale. Considering the topographical location of the catchment, analysis of seasonal rainfall data of 8 stations suggests that a linear relationship fits better than the logarithmic relationship in the case of seasonal rainfall versus mean daily intensity. So far as seasonal rainfall versus number of rainy days is considered, the logarithmic relationship is found to be better.

  4. The rainy season increases the abundance and richness of the aquatic insect community in a Neotropical reservoir

    Directory of Open Access Journals (Sweden)

    HS Santana

    Full Text Available Alterations in aquatic systems and changes in water levels, whether due to rains or dam-mediated control can cause changes in community structure, forcing the community to readjust to the new environment. This study tested the hypothesis that there is an increase in the richness and abundance of aquatic insects during the rainy season in the Serra da Mesa Reservoir, with the premise that increasing the reservoir level provides greater external material input and habitat diversity, and, therefore, conditions that promote colonization by more species. We used the paired t test to test the differences in richness, beta diversity, and abundance, and a Non-metric Multidimensional Scaling (NMDS was performed to identify patterns in the community under study. Additionally, Pearson correlations were analyzed between the richness, abundance, and beta diversity and the level of the reservoir. We collected 35,028 aquatic insect larvae (9,513 in dry period and 25,515 in the rainy season, predominantly of the Chironomidae family, followed by orders Ephemeroptera, Trichoptera, and Odonata. Among the 33 families collected, only 12 occurred in the dry season, while all occurred in the rainy season. These families are common in lentic environments, and the dominance of Chironomidae was associated with its fast colonization, their behavior of living at high densities and the great tolerance to low levels of oxygen in the environment. The hypothesis was confirmed, as the richness, beta diversity, and abundance were positively affected by the increase in water levels due to the rainy season, which most likely led to greater external material input, greater heterogeneity of habitat, and better conditions for colonization by several families.

  5. Cytotoxic and genotoxic assessment of surface water from São Paulo State, Brazil, during the rainy and dry seasons. (United States)

    Salles, Fernanda Junqueira; de Toledo, Maria Cecília Barbosa; César, Ana Cristina Gobbo; Ferreira, Gabriel Martins; Barbério, Agnes


    The aim of this study was to determine if the cytotoxic and genotoxic responses of Allium cepa are effective biomarkers of harmful effects caused by polluted river water and if changes in the responses reflect seasonality in the harmful effects. Samples were collected in the dry season (August 2011 and 2012) and rainy season (February 2012 and 2013) at sampling points on the Jaguari River and the Ribeirão Lavapés, in Brazil. Allium cepa bulbs were exposed to the samples, to positive controls (15 µg/L methyl methanesulfonate), and to negative controls (tap water). Three root tips from each bulb were then stained using the Feulgen reaction, then the micronucleus frequency, the mitotic index, and mitotic anomalies were measured. The total number of anomalies (stickiness, c-mitosis, multipolarity, chromosome bridges, and unidentified anomalies) in the rainy season (8.61 ± 3.65) and dry season (7.07 ± 2.96) were significantly different (U = 11.31, p = 0.04). Toxicity, indicated by the formation of micronuclei and the mitotic index, was higher in the February 2012 samples than in the August 2012 samples. The mean manganese concentration (0.13 mg/L) in the rainy season samples was higher than the maximum concentration permitted by the Brazilian National Environmental Council (<0.1 mg/L) and the manganese concentrations positively correlated with chromosomal aberration induction (p = 0.01, r = 0.69). In conclusion, the rainy season samples were more toxic than the dry season samples. This was probably related to rain water carrying compounds with potentially negative impacts into the rivers. These findings highlight the importance of biomonitoring studies and of treating wastewater in urban areas.

  6. Morphogenesis of dwarf elephant grass clones in response to intensity and frequency of defoliation in dry and rainy seasons

    Directory of Open Access Journals (Sweden)

    Carlos Augusto de Miranda Gomide


    Full Text Available The aim of this study was to evaluate during the dry and rainy seasons the morphogenesis traits of two clones of dwarf elephant grass under different management strategies. The study was conducted in a factorial 2 × 2 × 3 design, using two clones, one green and one purple, two residual heights, 25 and 45 cm, and three frequencies of defoliation according to the light interception of 90, 95 and 100%. The design was a randomized block with three replications. The variables were leaf elongation and leaf senescence rate, stem elongation rate and phyllochron. The leaf lifespan and the number of living leaves per tiller were also estimated. The clones presented low stem elongation rates, showing adaptation for grazing use. In the rainy season, the light interception of 100% promoted the highest stem elongation rate and increased the leaf senescence rate. In the dry season, the leaf elongation rate (LER was higher for the purple clone than for the green one (23 vs 15 In the rainy season, the LER of the green clone exceeded that of the purple one by 71% (149 vs. 87 The phyllochron varied among clones only in the rainy season, when the value was 4.6 days.leaf-1 for the green clone and 8.4 days.leaf-1 for the purple one; both of these values are below the mean value observed during the drought (21,6 days.leaf-1. The residual heights did not affect, in an isolated way, any of the variables. The clones are well adapted to grazing, presenting low stem elongation rates. The interval between defoliations should consider the scope of light interception between 90 and 95%. The green clone, with a greater flow of biomass, requires handling with shorter defoliation intervals.

  7. Pulsar Glitches: The Crust may be Enough

    CERN Document Server

    Piekarewicz, J; Horowitz, C J


    Pulsar glitches-the sudden spin-up in the rotational frequency of a neutron star-suggest the existence of an angular-momentum reservoir confined to the inner crust of the neutron star. Large and regular glitches observed in the Vela pulsar have originally constrained the fraction of the stellar moment of inertia that must reside in the solid crust to about 1.4%. However, crustal entrainment-which until very recently has been ignored-suggests that in order to account for the Vela glitches, the fraction of the moment of inertia residing in the crust must increase to about 7%. This indicates that the required angular momentum reservoir may exceed that which is available in the crust. We explore the possibility that uncertainties in the equation of state provide enough flexibility for the construction of models that predict a large crustal thickness and consequently a large crustal moment of inertia. Given that analytic results suggest that the crustal moment of inertia is sensitive to the transition pressure at ...

  8. Dew formation and activity of biological crusts

    NARCIS (Netherlands)

    Veste, M.; Heusinkveld, B.G.; Berkowicz, S.M.; Breckle, S.W.; Littmann, T.; Jacobs, A.F.G.


    Biological soil crusts are prominent in many drylands and can be found in diverse parts of the globe including the Atacama desert, Chile, the Namib desert, Namibia, the Succulent-Karoo desert, South Africa, and the Negev desert, Israel. Because precipitation can be negligible in deserts ¿ the

  9. Norwegian crusted scabies: an unusual case presentation. (United States)

    Maghrabi, Michael M; Lum, Shireen; Joba, Ameha T; Meier, Molly J; Holmbeck, Ryan J; Kennedy, Kate


    Scabies is a contagious condition that is transmitted through direct contact with an infected person and has been frequently associated with institutional and healthcare-facility outbreaks. The subtype Norwegian crusted scabies can masquerade as other dermatologic diseases owing to the heavy plaque formation. Successful treatment has been documented in published reports, including oral ivermectin and topical permethrin. Few case studies documenting the treatment of Norwegian crusted scabies have reported the use of surgical debridement as an aid to topical and/or oral treatment when severe plaque formation has been noted. A nursing home patient was admitted to the hospital for severe plaque formation of both feet. A superficial biopsy was negative for both fungus and scabies because of the severity of the plaque formation on both feet. The patient underwent a surgical, diagnostic biopsy of both feet, leading to the diagnosis of Norwegian crusted scabies. A second surgical debridement was then performed to remove the extensive plaque formation and aid the oral ivermectin and topical permethrin treatment. The patient subsequently made a full recovery and was discharged back to the nursing home. At 2 and 6 months after treatment, the patient remained free of scabies infestation, and the surgical wound had healed uneventfully. The present case presentation has demonstrated that surgical debridement can be complementary to the standard topical and oral medications in the treatment of those with Norwegian crusted scabies infestation.

  10. Infestation of Caliothrips phaseoli (Thysanoptera: Thripidae) on Bean Cultivars Grown in the Winter, Rainy, and Dry Seasons in Brazil. (United States)

    Boiça Júnior, Arlindo Leal; Costa, Eduardo Neves; De Souza, Bruno Henrique Sardinha; Da Silva, Anderson Gonçalves; Chiorato, Alisson Fernando


    The present study aimed to identify common bean (Phaseolus vulgaris L.) cultivars less susceptible to Caliothrips phaseoli (Hood) in different growing seasons, to evaluate whether climatic conditions influence plant resistance to C. phaseoli infestation, and to investigate the preferred plant part for insect feeding. Eighteen common bean cultivars were evaluated in the winter season, and 19 cultivars were assessed in the rainy and dry seasons, under field conditions in the municipality of Jaboticabal, state of São Paulo, Brazil. Infestation of C. phaseoli nymphs in the upper and lower parts of the beans plants was recorded at weekly intervals from 25 days after plant emergence (DAE) to 60 DAE. In the winter season, the cultivars 'IAC Galante,' 'IAC Centauro,' 'IAC Carioca Eté,' and 'IAC Formoso' had significantly lower number of thrips than the cultivar 'IAC Diplomata.' In the rainy season, the cultivars 'IAC Harmonia' and 'IPR Siriri' had the lowest thrips infestation, differing from the cultivars 'BRS Pontal' and 'IAC Una.' The bean cultivars were equally susceptible to C. phaseoli in the dry season. The results suggest that C. phaseoli nymphs prefer to infest leaves of the lower part of bean plants, like most generalist herbivorous insects. In the winter and dry seasons, the highest thrips infestation was observed at 60 DAE, while in the rainy season, it was recorded from 32 to 46 DAE. Overall, C. phaseoli infestation on bean cultivars was not influenced by either temperature, relative humidity, or rainfall.

  11. Playa Lakes (United States)

    Kansas Data Access and Support Center — This digital dataset provides information about the spatial distribution of soil units associated with playa lakes. Specific soil types have been designated by the...

  12. Comparison between the Spectra of Gamma Radiation for Climate Dry Periods and Rainy in the Southeast of Brazil (United States)

    Gomes, M. P.; Martin, I. M.


    Through this work, present themselves the results obtained for the spectra of ionizing radiation (X-rays and gamma) environmental southeast Brazil for the periods of dry and rainy climate, respectively. One of the objectives this work is promoting through analysis of the results a better understand, in the educational area, the physical processes related to the background radiation of the places where measurements were made. In Brazil, there is still little information about the radiation from soil, radon gas atmospheric, cosmic and artificial origin. Measurements of gamma radiation spectra were performed with a scintillator of NaI (Tl) (volume 300 cm3) mounted within an aluminum cell and coupled to a photomultiplier tube, which in turn is coupled through an interface to specify a notebook for storage of data. The measurement of X and gamma rays photons occur of way omnidirectional without distinction as to direction. The data acquisition was performed at fixed intervals of 1 minute continuously for the entire period of dry climate (June to October) and rainy (December 2012 to January 2013). Figures 1 and 2 show the results obtained for both periods, dry and rainy, respectively. Regarding the graph of Figure 1, is evidenced a cycle of 24 hours in the radiation spectrum. In this period without rain the radiation increases always between sunrise sunset until 11 - 12 hours local, due to the increased presence of radon gas (222Rn) which decays after 3.8 days in 214Pb and 214Bi, emitting photons in the range of energy the detector is measuring (0.030 to 3.0 MeV). The graph in Figure 2 shows that during the rainy period, there was a significant increase in radiation intensity, in addition to that already shown in the dry times that for certain time intervals. This increase is due to when occurs precipitation, the amount of radon gas increases because of the phenomenon of washing the lower atmosphere where the gas is suspended and diluted in water droplets. In the rainy

  13. Petrological and two-phase flow modelling of deep arc crust: insights on continental crust formation (United States)

    Riel, Nicolas; Bouilhol, Pierre; van Hunen, Jeroen; Cornet, Julien


    The genesis of felsic crust is generally attributed to two main processes: the differentiation of primary magmas by crystallization within the crust or uppermost mantle and the partial melting of older crustal rocks. The Mixing/Assimilation/Hybridization of these magmas in the deep crust (MASH zone) and their subsequent segregation constitutes the principal process by which continents have become differentiated into a more mafic, residual lower crust and a more felsic and hydrated upper crust. Although this model describes qualitatively how continental crust forms, little is known on the physical and chemical mechanisms occurring at the root of volcanic arcs. To assess the dynamics of partial melting, melt injection and hybridization in the deep crust, a new 2-D two-phase flow code using finite volume method has been developed. The formulation takes into account: (i) melt flow through porosity waves/channels, (ii) heat transfer, assuming local thermal equilibrium between solid and liquid, (iii) thermodynamic modelling of stable phases and (iv) injection of mantle-derived melt at the Moho. Our parametric study shows that pressure, heat influx and melt:rock ratio are the main parameters controlling the volume and composition of differentiated magma. Overall the composition of segregated products scatters in two groups: felsic (80-68% SiO2) and intermediate (60-52% SiO2), with an average andesitic composition. The bimodal distribution is controlled by amphibole which buffer the composition of segregated products to high SiO2-content when stable. As the amphibole-out melting reaction is crossed segregated products become intermediate. When compared to available geological evidence, the liquid line of descent of mantle-derived magma do not fit the Mg# versus silica trends of exposed volcanic arcs. Instead our modelling results show that reactive flow of those same magma through a mafic crust is able to reproduce such trends.

  14. Possible Changes in the Characteristics of the Rainy Season over Northern South America: Results from a Regional Climate Simulation (United States)

    Vasconcelos, Francisco; Costa, Alexandre; Gandu, Adilson; Sales, Domingo; Araújo, Luiz


    Regional Climate Simulations were performed with RAMS6.0 to evaluate possible changes in the behaviour of the rainy season over the Amazon region, within the CORDEX domain of the Inter-tropical Americas. We forced the regional model using data from one of the CMIP5 participants (HadGEM2-ES), both for the Historical Experiment (1980-2005) and along the XXI century under RCP 8.5 (heavy-emission scenario). Regarding projections, we analyzed results for three time slices, short (2014-2035), middle (2044-2065) and long term (2078-2099), according to the following steps. First, the spatially averaged precipitation in non-overlapping pentads over 7 sub-regions over northern South America was calculated ("boxes" 1 to 7). Then, we calculated the climatological annual cycle for each one of them. Finally, dates of the onset and demise of the rainy season are found, validating the model results against GPCP observations and checking for projected changes. In general, in the Historical Experiment, the model delays the onset of the rainy season over the northern areas and anticipates it over most inland sub-regions. Over eastern Amazon, the regional model represents it properly, besides a delay in the demise of about one month. In short-term projections, there is a slight increase in precipitation and a modest anticipation of the rainy season onset in the coastal areas. Projected changes in the annual cycle of most sub-regions are relatively modest for the short-term and mid-term periods, but may become very significant by the end of the century. Over Colombia (Box 1), which has a bimodal precipitation annual cycle, the model projects a late century increase in the first precipitation peak. Little change is projected for the two boxes roughly covering Venezuela, the Guianas and the northernmost portion of northern Brazilian states (Boxes 2 and 3). The box covering northern Peru and Ecuador (Box 4) shows increased March-April precipitation, but with no significant changes in the

  15. Thermal imaging of Erta 'Ale active lava lake (Ethiopia) (United States)

    Spampinato, L.; Oppenheimer, C.; Calvari, S.; Cannata, A.; Montalto, P.


    Active lava lakes represent the uppermost portion of a volume of convective magma exposed to the atmosphere, and provide open windows on magma dynamics within shallow reservoirs. Erta ‘Ale volcano located within the Danakil Depression in Ethiopia, hosts one of the few permanent convecting lava lakes, active at least since the last century. We report here the main features of Erta ‘Ale lake surface investigated using a hand-held infrared thermal camera between 11 and 12 November 2006. In both days, the lake surface was mainly characterized by efficient magma circulation reflecting in the formation of well-marked incandescent cracks and wide crust plates. These crossed the lake from the upwelling to the downwelling margin with mean speeds ranging between 0.01 and 0.15 m s-1. Hot spots opened eventually in the middle of crust plates and/or along cracks. These produced explosive activity lasting commonly between ~10 and 200 sec. Apparent temperatures at cracks ranged between ~700 and 1070˚C, and between ~300 and 500˚C at crust plates. Radiant power output of the lake varied between ~45 and 76 MW according to the superficial activity and continuous resurfacing of the lake. Time series analysis of the radiant power output data reveals cyclicity with a period of ~10 min. The combination of visual and thermal observations with apparent mean temperatures and convection rates allows us to interpret these signals as the periodic release of hot overpressured gas bubbles at the lake surface.

  16. Intensive Ammonia and Methane Oxidation in Organic Liquid Manure Crusts

    DEFF Research Database (Denmark)

    Nielsen, Daniel Aagren; Nielsen, Lars Peter; Schramm, Andreas;

    of the crusts. PCR targeting the unique methane and ammonia monooxygenases were applied together with FISH to detect the presence of the two bacterial groups. Potential activity was assessed by short term slurry incubations of crust samples while monitoring NO2- production or CH4 consumption. Crusts were...... also CH4 emission mitigation, an organic surface crust can be effective if populations of MOB and AOB are allowed to build up....

  17. Microbial community structure in three deep-sea carbonate crusts

    NARCIS (Netherlands)

    Heijs, S. K.; Aloisi, G.; Bouloubassi, I.; Pancost, R. D.; Pierre, C.; Damste, J. S. Sinninghe; Gottschal, J. C.; van Elsas, J. D.; Forney, L. J.


    Carbonate crusts in marine environments can act as sinks for carbon dioxide. Therefore, understanding carbonate crust formation could be important for understanding global warming. In the present study, the microbial communities of three carbonate crust samples from deep-sea mud volcanoes in the eas

  18. Permeability of crust is key to crispness retention

    NARCIS (Netherlands)

    Hirte, A.; Hamer, R.J.; Meinders, M.B.J.; Primo-Martin, C.


    Bread loses crispness rapidly after baking because water originating from the wet crumb accumulates in the dry crust. This water accumulation might be increased by the dense and low permeable character of the bread crust. Our objective was to investigate the influence of permeability of the crust on

  19. Permeability of crust is key to crispness retention

    NARCIS (Netherlands)

    Hirte, A.; Hamer, R.J.; Meinders, M.B.J.; Primo-Martin, C.


    Bread loses crispness rapidly after baking because water originating from the wet crumb accumulates in the dry crust. This water accumulation might be increased by the dense and low permeable character of the bread crust. Our objective was to investigate the influence of permeability of the crust on

  20. Density Sorting During the Evolution of Continental Crust (United States)

    Kelemen, P. B.; Behn, M. D.; Hacker, B. R.


    We consider two settings - in addition to "delamination" of arc lower crust - in which dense, mafic eclogites founder into the convecting mantle while buoyant, felsic lithologies accumulate at the base of evolving continental crust. Arc processes play a central role in generating continental crust, but it remains uncertain how basaltic arc crust is transformed to andesitic continental crust. Dense, SiO2-poor products of fractionation may founder from the base of arc crust by "delamination", but lower arc crust after delamination has significantly different trace elements compared to lower continental crust (LCC). In an alternative model, buoyant magmatic rocks generated at arcs are first subducted, mainly via subduction erosion. Upon heating, these buoyant lithologies ascend through the mantle wedge or along a subduction channel, and are "relaminated" at
the base of overlying crust (e.g., Hacker et al EPSL 11, AREPS 15). Average buoyant lavas and plutons
for the Aleutians, Izu-Bonin-Marianas, Kohistan and Talkeetna arcs fall within the range of estimated LCC major and trace elements. Relamination is more efficient in generating continental crust than delamination. Himalayan cross-sections show Indian crust thrust beneath Tibetan crust, with no intervening mantle. There is a horizontal Moho at ca 80 km depth, extending from thickened Indian crust, across the region where Tibetan crust overlies Indian crust, into thickened Tibetan crust. About half the subducted Indian crust is present, whereas the other half is missing. Data (Vp/Vs; Miocene lavas formed by interaction of continental crust with mantle; xenolith thermometry) indicate 1000°C or more from ca 50 km depth to the Moho since the Miocene. We build on earlier studies (LePichon et al Tectonics 92, T'phys 97; Schulte-Pelkum et al Nature 05; Monsalve et al JGR 08) to advance the hypothesis that rapid growth of garnet occurs at 70-80 km and 1000°C within subducting Indian crust. Dense eclogites founder

  1. Crusted Scabies in the Burned Patient

    DEFF Research Database (Denmark)

    Berg, Jais Oliver; Alsbjørn, Bjarne


    The objectives of this study were 1) to describe a case of crusted scabies (CS) in a burned patient, which was primarily undiagnosed and led to a nosocomial outbreak in the burn unit; 2) to analyze and discuss the difficulties in diagnosing and treating this subset of patients with burn injury......; and 3) to design a treatment strategy for future patients. Case analysis and literature review were performed. The index patient had undiagnosed crusted scabies (sive Scabies norvegica) with the ensuing mite hyperinfestation when admitted to the department with minor acute dermal burns. Conservative...... healing and autograft healing were impaired because of the condition. Successful treatment of the burns was only accomplished secondarily to scabicide treatment. An outbreak of scabies among staff members indirectly led to diagnosis. CS is ubiquitous, and diagnosis may be difficult. This is the first...

  2. Towards a metallurgy of neutron star crusts

    CERN Document Server

    Kobyakov, D


    In the standard picture of the crust of a neutron star, matter there is simple: a body-centered-cubic (bcc) lattice of nuclei immersed in an essentially uniform electron gas. We show that at densities above that for neutron drip ($\\sim4\\times10^11$) g cm$^{-3}$ or roughly one thousandth of nuclear matter density, the interstitial neutrons give rise to an attractive interaction between nuclei that renders the lattice unstable. We argue that the likely equilibrium structure is similar to that in displacive ferroelectric materials such as BaTiO$_3$. As a consequence, properties of matter in the inner crust are expected to be much richer than previously appreciated and we mention consequences for observable neutron star properties.

  3. Towards a metallurgy of neutron star crusts. (United States)

    Kobyakov, D; Pethick, C J


    In the standard picture of the crust of a neutron star, matter there is simple: a body-centered-cubic lattice of nuclei immersed in an essentially uniform electron gas. We show that, at densities above that for neutron drip (∼ 4 × 1 0(11)  g cm(-3) or roughly one-thousandth of nuclear matter density), the interstitial neutrons give rise to an attractive interaction between nuclei that renders the lattice unstable. We argue that the likely equilibrium structure is similar to that in displacive ferroelectric materials such as BaTiO3. As a consequence, the properties of matter in the inner crust are expected to be much richer than previously appreciated, and we mention possible consequences for observable neutron star properties.

  4. Excited nuclei in neutron star crusts

    CERN Document Server

    Takibayev, Nurgali; Nasirova, Diana


    The paper considers the chains of successive electron capture reactions by nuclei of the iron group which take place in the crystal structures of neutron star envelopes. It is shown that as a result of such reactions the daughter nuclei in excited states accumulate within certain layers of neutron star crusts. The phonon model of interactions is proposed between the excited nuclei in the crystalline structure, as well as formation of highly excited nuclear states which emit neutrons and higher energy photons.

  5. Lime-Crusted Rammed Earth: Materials Study


    Mileto, Camilla; Vegas López-Manzanares, Fernando; Alejandre, Francisco Javier; Martín, Juan Jesús; Garcia Soriano, Lidia


    This study analyses the durability of rammed-earth wall construction techniques. The analysis focuses on three medieval masonry types from the Castle of Villavieja (Castellón, Spain) using two variations of lime-reinforced rammed earth in its walls: lime-crusted rammed earth and brick-reinforced rammed earth. Materials analysis reveals the good properties of the materials used in the outer wall facing despite its age. It also clearly shows how deterioration depends more on the construction t...

  6. Topological characterization of neutron star crusts

    CERN Document Server

    Dorso, C O; López, J A


    Neutron star crusts are studied using a classical molecular dynamics model developed for heavy ion reactions. After the model is shown to produce a plethora of the so-called "pasta" shapes, a series of techniques borrowed from nuclear physics, condensed matter physics and topology are used to craft a method that can be used to characterize the shape of the pasta structures in an unequivocal way.

  7. Cyclic growth in Atlantic region continental crust (United States)

    Goodwin, A. M.


    Atlantic region continental crust evolved in successive stages under the influence of regular, approximately 400 Ma-long tectonic cycles. Data point to a variety of operative tectonic processes ranging from widespread ocean floor consumption (Wilson cycle) to entirely ensialic (Ampferer-style subduction or simple crustal attenuation-compression). Different processes may have operated concurrently in some or different belts. Resolving this remains the major challenge.

  8. FAST TRACK PAPER: Older crust underlies Iceland (United States)

    Foulger, G. R.


    The oldest rocks outcropping in northwest Iceland are ~16 Myr old and in east Iceland ~13 Myr. The full plate spreading rate in this region during the Cenozoic has been ~2 cm a-1, and thus these rocks are expected to be separated by ~290 km. They are, however, ~500 km apart. The conclusion is inescapable that an expanse of older crust ~210 km wide underlies Iceland, submerged beneath younger lavas. This conclusion is independent of any considerations regarding spreading ridge migrations, jumps, the simultaneous existence of multiple active ridges, three-dimensionality, or subsidence of the lava pile. Such complexities bear on the distribution and age of the older crust, but not on its existence or its width. If it is entirely oceanic its maximum age is most likely 26-37 Ma. It is at least 150 km in north-south extent, but may taper and extend beneath south Iceland. Part of it might be continental-a southerly extension of the Jan Mayen microcontinent. This older crust contributes significantly to crustal thickness beneath Iceland and the ~40 km local thickness measured seismically is thus probably an overestimate of present-day steady-state crustal production at Iceland.

  9. Pyrolysis of waste plastic crusts of televisions. (United States)

    Liu, Xinmin; Wang, Zhen; Xu, Dongyan; Guo, Qingjie


    The disposal of waste plastic crusts of televisions is an issue that is gaining increasing interest around the world. In this investigation, the pyrolysis and catalytic cracking of the waste television crusts mainly composed of acrylonitrile--butadiene-styrene copolymer was studied. Thermogravimetric analysis was used for initial characterization of the pyrolysis of the waste plastic, but most of the investigations were carried out using a 600 mL tubing reactor. Effects of temperature, reaction time and catalyst on the pyrolysis of the waste television crusts were investigated. The results showed that the oil yield increased with increasing temperature or with prolongation of reaction time. With increasing temperature, the generating percentage of gasoline and diesel oil increased, but the heavy oil yield decreased. Zinc oxide, iron oxide and fluid catalytic cracking catalyst (FCC catalyst) were employed to perform a series of experiments. It was demonstrated that the liquid product was markedly improved and the reaction temperature decreased 100 degrees C when FCC was used. The composition ofpyrolysis oils was analysed using gas chromatography-mass spectrometry, and they contained 36.49% styrene, 19.72% benzenebutanenitrile, 12.1% alpha-methylstyrene and 9.69% dimethylbenzene.

  10. Total digestible nutrient levels in supplements for finishing steers in the rainy season: nutritional characteristics and microbial efficiency

    Directory of Open Access Journals (Sweden)

    Jefferson Fabiano Werner Koscheck


    Full Text Available The objective of this study was to evaluate the effects of total digestible nutrient (TDN levels in supplements on rumen pH, ruminal ammonia nitrogen concentration, intake and digestibility, nitrogen balance and microbial efficiency in beef cattle grazing on Marandu grass during the rainy season. The supplements comprised a mineral mixture, ground corn grain, soybean hulls, roasted soybeans and urea:ammonium sulfate. The mineral mix (MM and supplements were supplied at 800, 1,600 and 2,400 g/animal/day, contained 500, 1,000 and 1,500 g of TDN, respectively, and were termed S500, S1000 and S1500. Supplemental crude protein (CP was fixed at 300g animal/day for all supplementing strategies. Four crossbred rumen-fistulated steers, with an average weight of 512kg, were utilized. The animals were distributed in a 4×4 Latin square in four paddocks of 0.25 ha. The rumen nitrogen concentration was increased by 63% after four hours of supplementation. Supplements with increased TDN levels did not alter the total dry matter and forage intakes, although the TDN levels linearly increased the non-fibrous carbohydrates intake. Additionally, most supplements did not alter the digestibility of the diet nutrients.The nitrogen balance was similar in all treatments. However, supplements with the highest TDN levels linearly improved the microbial efficiency of finishing beef cattle that were pasture-grazed during the rainy season. Supplements with in creasing TDN levels improve the microbial efficiency during the rainy season.

  11. A study on the predictability of the transition day from the dry to the rainy season over South Korea (United States)

    Lee, Sang-Min; Nam, Ji-Eun; Choi, Hee-Wook; Ha, Jong-Chul; Lee, Yong Hee; Kim, Yeon-Hee; Kang, Hyun-Suk; Cho, ChunHo


    This study was conducted to evaluate the prediction accuracies of THe Observing system Research and Predictability EXperiment (THORPEX) Interactive Grand Global Ensemble (TIGGE) data at six operational forecast centers using the root-mean square difference (RMSD) and Brier score (BS) from April to July 2012. And it was performed to test the precipitation predictability of ensemble prediction systems (EPS) on the onset of the summer rainy season, the day of withdrawal in spring drought over South Korea on 29 June 2012 with use of the ensemble mean precipitation, ensemble probability precipitation, 10-day lag ensemble forecasts (ensemble mean and probability precipitation), and effective drought index (EDI). The RMSD analysis of atmospheric variables (geopotential-height at 500 hPa, temperature at 850 hPa, sea-level pressure and specific humidity at 850 hPa) showed that the prediction accuracies of the EPS at the Meteorological Service of Canada (CMC) and China Meteorological Administration (CMA) were poor and those at the European Center for Medium-Range Weather Forecasts (ECMWF) and Korea Meteorological Administration (KMA) were good. Also, ECMWF and KMA showed better results than other EPSs for predicting precipitation in the BS distributions. It is also evaluated that the onset of the summer rainy season could be predicted using ensemble-mean precipitation from 4-day leading time at all forecast centers. In addition, the spatial distributions of predicted precipitation of the EPS at KMA and the Met Office of the United Kingdom (UKMO) were similar to those of observed precipitation; thus, the predictability showed good performance. The precipitation probability forecasts of EPS at CMA, the National Centers for Environmental Prediction (NCEP), and UKMO (ECMWF and KMA) at 1-day lead time produced over-forecasting (under-forecasting) in the reliability diagram. And all the ones at 2˜4-day lead time showed under-forecasting. Also, the precipitation on onset day of

  12. Fluorescent bioaerosol particle, molecular tracer, and fungal spore concentrations during dry and rainy periods in a semi-arid forest (United States)

    Ila Gosselin, Marie; Rathnayake, Chathurika M.; Crawford, Ian; Pöhlker, Christopher; Fröhlich-Nowoisky, Janine; Schmer, Beatrice; Després, Viviane R.; Engling, Guenter; Gallagher, Martin; Stone, Elizabeth; Pöschl, Ulrich; Huffman, J. Alex


    Bioaerosols pose risks to human health and agriculture and may influence the evolution of mixed-phase clouds and the hydrological cycle on local and regional scales. The availability and reliability of methods and data on the abundance and properties of atmospheric bioaerosols, however, are rather limited. Here we analyze and compare data from different real-time ultraviolet laser/light-induced fluorescence (UV-LIF) instruments with results from a culture-based spore sampler and offline molecular tracers for airborne fungal spores in a semi-arid forest in the southern Rocky Mountains of Colorado. Commercial UV-APS (ultraviolet aerodynamic particle sizer) and WIBS-3 (wideband integrated bioaerosol sensor, version 3) instruments with different excitation and emission wavelengths were utilized to measure fluorescent aerosol particles (FAPs) during both dry weather conditions and periods heavily influenced by rain. Seven molecular tracers of bioaerosols were quantified by analysis of total suspended particle (TSP) high-volume filter samples using a high-performance anion-exchange chromatography system with pulsed amperometric detection (HPAEC-PAD). From the same measurement campaign, Huffman et al. (2013) previously reported dramatic increases in total and fluorescent particle concentrations during and immediately after rainfall and also showed a strong relationship between the concentrations of FAPs and ice nuclei (Huffman et al., 2013; Prenni et al., 2013). Here we investigate molecular tracers and show that during rainy periods the atmospheric concentrations of arabitol (35.2 ± 10.5 ng m-3) and mannitol (44.9 ± 13.8 ng m-3) were 3-4 times higher than during dry periods. During and after rain, the correlations between FAP and tracer mass concentrations were also significantly improved. Fungal spore number concentrations on the order of 104 m-3, accounting for 2-5 % of TSP mass during dry periods and 17-23 % during rainy periods, were obtained from scaling the

  13. New index of ferromanganese crusts reflecting oceanic environmental oxidation

    Institute of Scientific and Technical Information of China (English)

    WU GuangHai; ZHOU HuaiYang; ZHANG HaiSheng; LING HongFei; MA WeiLin; ZHAO HongQiao; CHEN JianLin; LIU JieHong


    Ferromanganese crusts (hereinafter crusts)form in aerobic environment and the environmental oxidation degree is recorded by the redox sensitive element Co in the crusts.The ages of the layers from the surface to bottom of the crusts are determined,and main element contents at high resolution along the depth sections of three crusts from the Pacific Ocean are analyzed by an electron microprobe.Thus the variations of Co/(Fe+Mn)and Co/(Ni+Cu)with age/depth of the crust layers are obtained.By comparing the ratios of co/(Fe+Mn)and Co/(Ni+Cu)with theδ18O curves of the Pacific benthic foraminifera,we find that these two ratios can reflect the variation of the environmental oxidation state under which the crust layers deposit.The evolution of the oxidation degree reflected by the two indexes resembles the evolution of temperature since the Oligocene reflected by theδ18O curves of the Pacific benthic foraminifera.This suggests that the crust-forming environment after the Oligocene is controlled mainly by the oxygen-rich bottom water originated from the Antarctic bottom water (AABW).However it is not the case prior to the Oligocene.Furthermore it suggests that the environmental oxidation degree controls the formation of the crusts and the Co contents in the crusts.This explains why the Co contents in the crusts increase with time up to now.

  14. New index of ferromanganese crusts reflecting oceanic environmental oxidation

    Institute of Scientific and Technical Information of China (English)


    Ferromanganese crusts (hereinafter crusts) form in aerobic environment and the environmental oxida-tion degree is recorded by the redox sensitive element Co in the crusts. The ages of the layers from the surface to bottom of the crusts are determined, and main element contents at high resolution along the depth sections of three crusts from the Pacific Ocean are analyzed by an electron microprobe. Thus the variations of Co/(Fe+Mn) and Co/(Ni+Cu) with age/depth of the crust layers are obtained. By comparing the ratios of Co/(Fe+Mn) and Co/(Ni+Cu) with the δ 18O curves of the Pacific benthic foraminifera, we find that these two ratios can reflect the variation of the environmental oxidation state under which the crust layers deposit. The evolution of the oxidation degree reflected by the two indexes resembles the evo-lution of temperature since the Oligocene reflected by the δ 18O curves of the Pacific benthic foraminif-era. This suggests that the crust-forming environment after the Oligocene is controlled mainly by the oxygen-rich bottom water originated from the Antarctic bottom water (AABW). However it is not the case prior to the Oligocene. Furthermore it suggests that the environmental oxidation degree controls the formation of the crusts and the Co contents in the crusts. This explains why the Co contents in the crusts increase with time up to now.

  15. Seasonal morphological variability in an in situ Cyanobacteria monoculture: example from a persistent Cylindrospermopsis bloom in Lake Catemaco, Veracruz, Mexico

    Directory of Open Access Journals (Sweden)

    Owen Lind


    Full Text Available The phrase cyanobacteria bloom implies a transient condition in which one to few species dominates communities. In this paper we describe a condition in which the bloom is of multi-year duration consisting of different morphologies of a single cyanobacteria species. Lake Catemaco, Veracruz, México maintained a year-round massive (108 trichomes L-1 population of potentially toxin-producing cyanobacteria, Cylindrospermopsis spp. The trichomes are present as straight and coiled morphotypes.  The relative trichome morphology abundance varied with rainy (June – October and dry seasons (November – May, but total trichome abundance did not vary.  Coiled trichomes and heterocytes (occurring only on coiled trichomes were significantly more abundant, both absolutely and relatively, during the dry season. Both coiled trichome and heterocyte mean volumes were significantly smaller during the rainy season than during the dry season.  Biovolumes were largest in January when water temperature was 5º C cooler suggesting buoyancy as a morphology-determining factor. However, with a more than three-fold lower TIN concentration during the dry season, we hypothesized that the coiled morphotype became abundant primarily because it formed heterocytes, which the straight morphotype did not. Spatial trichome and heterocyte abundance differences were small among the 15 lake sites (average CV for all dates = 20%. However, there was a pattern of increased heterocyte and coiled trichome abundance from lake inflow, as a nitrogen source, to outflow during the rainy season. The total volume of heterocytes per litre of lake water increased progressively four-fold from a minimum early in the rainy season to a maximum at the end of the dry season. Morphological diversity, as seen in Lake Catemaco, can partially compensate for the lack of species diversity in determination of community structure.

  16. Great Lakes (United States)

    Edsall, Thomas A.; Mac, Michael J.; Opler, Paul A.; Puckett Haecker, Catherine E.; Doran, Peter D.


    The Great Lakes region, as defined here, includes the Great Lakes and their drainage basins in Minnesota, Wisconsin, Illinois, Indiana, Ohio, Pennsylvania, and New York. The region also includes the portions of Minnesota, Wisconsin, and the 21 northernmost counties of Illinois that lie in the Mississippi River drainage basin, outside the floodplain of the river. The region spans about 9º of latitude and 20º of longitude and lies roughly halfway between the equator and the North Pole in a lowland corridor that extends from the Gulf of Mexico to the Arctic Ocean.The Great Lakes are the most prominent natural feature of the region (Fig. 1). They have a combined surface area of about 245,000 square kilometers and are among the largest, deepest lakes in the world. They are the largest single aggregation of fresh water on the planet (excluding the polar ice caps) and are the only glacial feature on Earth visible from the surface of the moon (The Nature Conservancy 1994a).The Great Lakes moderate the region’s climate, which presently ranges from subarctic in the north to humid continental warm in the south (Fig. 2), reflecting the movement of major weather masses from the north and south (U.S. Department of the Interior 1970; Eichenlaub 1979). The lakes act as heat sinks in summer and heat sources in winter and are major reservoirs that help humidify much of the region. They also create local precipitation belts in areas where air masses are pushed across the lakes by prevailing winds, pick up moisture from the lake surface, and then drop that moisture over land on the other side of the lake. The mean annual frost-free period—a general measure of the growing-season length for plants and some cold-blooded animals—varies from 60 days at higher elevations in the north to 160 days in lakeshore areas in the south. The climate influences the general distribution of wild plants and animals in the region and also influences the activities and distribution of the human

  17. Hydrology and water quality of East Lake Tohopekaliga, Osceola County, Florida (United States)

    Schiffer, Donna M.


    East Lake Tohopekaliga, one of the major lakes in central Florida, is located in the upper Kissimmee River basin in north-east Osceola County. It is one of numerous lakes in the upper basin used for flood control, in addition to recreation and some irrigation of surrounding pasture. This report is the fourth in a series of lake reconnaissance studies in the Kissimmee River basin prepared in cooperation with the South Florida Water Management District. The purpose of the report is to provide government agencies and the public with a brief summary of the lake 's hydrology and water quality. Site information is given and includes map number, site name, location, and type of data available (specific conductivity, pH, alkalinity, turbidity, color, dissolved oxygen, hardness, dissolved chlorides, dissolved sodium, dissolved calcium, dissolved magnesium, dissolved potassium, nitrogen, ammonia, nitrates, carbon and phosphorus). The U.S. Geological Survey (USGS) maintained a lake stage gaging station on East Lake Tohopekaliga from 1942 to 1968. The South Florida Water Management District has recorded lake stage since 1963. Periodic water quality samples have been collected from the lake by the South Florida Water Management District and USGS. Water quality and discharge data have been collected for one major tributary to the lake, Boggy Creek. Although few groundwater data are available for the study area, results of previous studies of the groundwater resources of Osceola County are included in this report. To supplement the water quality data for East Lake Tohopekaliga, water samples were collected at selected sites in November 1982 (dry season) and in August 1983 (rainy season). Samples were taken at inflow points, and in the lake, and vertical profiles of dissolved oxygen and temperature were measured in the lake. A water budget from an EPA report on the lake is also included. (Lantz-PTT)

  18. Variation of limnological parameters in a tropical lake used for tilapia cage farming

    Directory of Open Access Journals (Sweden)

    Graciele P. Venturoti


    Full Text Available The aim of this study was to assess the effects of tilapia cage culture on the water quality and sediment of Palminhas Lake during both the dry and rainy seasons. Eight sites within the lake (four in fish farms and four in areas without fish farms and one site on an affluent stream were sampled monthly from February 2011 to January 2012. Dissolved oxygen and pH were significantly lower at fish farm sites than at locations without farms, while chlorophyll a was higher at fish farm sites. Moreover, large seasonal variations were observed, which were not related to the fish farms. The Secchi disc depth and ammonia nitrogen level were significantly higher during the dry season, but temperature, dissolved oxygen, pH, total phosphorus and chlorophyll a were significantly higher during the rainy season. The affluent stream contributed substantially to lake eutrophication. Palminhas Lake is mesotrophic and has exhibited a progressive worsening in water quality over the past 20 years. These changes were not caused by fish farming alone but probably by other anthropic activities in the areas surrounding the lake.

  19. Lava lake surface characterization by thermal imaging: Erta 'Ale volcano (Ethiopia) (United States)

    Spampinato, L.; Oppenheimer, C.; Calvari, S.; Cannata, A.; Montalto, P.


    Active lava lakes represent the exposed, uppermost part of convecting magma systems and provide windows into the dynamics of magma transport and degassing. Erta 'Ale volcano located within the Danakil Depression in Ethiopia hosts one of the few permanent convecting lava lakes, probably active for a century or more. We report here on the main features of the lava lake surface based on observations from an infrared thermal camera made on 11 November 2006. Efficient magma circulation was reflected in the sustained transport of the surface, which was composed of pronounced incandescent cracks that separated wide plates of cooler crust. These crossed the lake from the upwelling to the downwelling margin with mean speeds ranging between 0.01 and 0.15 m s-1. Hot spots eventually opened in the middle of crust plates and/or along cracks. These produced mild explosive activity lasting commonly between ˜10 and ˜200 s. Apparent temperatures of cracks ranged between ˜700 and 1070°C, and of crust between ˜300 and 500°C. Radiant power output of the lake varied between ˜45 and 76 MW according to the superficial activity and continuous resurfacing of the lake. Time series analysis of the radiant power output data reveals cyclicity with a period of ˜10 min. The combination of visual and thermal observations with apparent mean temperatures and convection rates allows us to interpret these signals as the periodic release of hot overpressured gas bubbles at the lake surface.

  20. The effect of thicker oceanic crust in the Archaean on the growth of continental crust through time (United States)

    Wilks, M. E.


    Present crustal evolution models fail to account for the generation of the large volume of continental crust in the required time intervals. All Archaean plate tectonic models, whether invoking faster spreading rates, similar to today's spreading rates, or longer ridge lengths, essentially propose that continental crust has grown by island arc accretion due to the subduction of oceanic crust. The petrological differences that characterize the Archaean from later terrains result from the subduction of hotter oceanic crust into a hotter mantle. If the oceanic crust was appreciably thicker in the Archaean, as geothermal models would indicate, this thicker crust is surely going to have an effect on tectonic processes. A more valid approach is to compare the possible styles of convergence of thick oceanic crust with modern convergence zones. The best modern analog occurs where thick continental crust is colliding with thick continental crust. Oceanic crustal collision on the scale of the present-day Himalayan continental collision zone may have been a frequent occurrence in the Archaean, resulting in extensive partial melting of the hydrous underthrust oceanic crust to produce voluminous tonalite melts, leaving a depleted stabilized basic residuum. Present-day island arc accretion may not have been the dominant mechanism for the growth of the early Archaean crust.

  1. Plant species visited by the Horned Sungem Heliactin bilophus (Aves, Trochilidae at Chapada dos Veadeiros, during the rainy season

    Directory of Open Access Journals (Sweden)

    Gabriel Baruffaldi Ghiringhello


    Full Text Available The feeding habits of the Horned Sungem remain little known. This study aimed to identify the plant species most often visited by H. bilophus with feeding purposes (consumption of nectar during the rainy season at Chapada dos Veadeiros National Park, Goiás. Observations were made during two rainy seasons (January 2006 and February 2008. The methodology consisted of walking through trails within two areas of campo sujo and two areas of campo rupestre. The record of an individual consuming the nectar of a flowering plant was considered to constitute a visit. A total of 296 visits were observed, comprising eight species of shrubs and herbs. The most often visited plant species were Bauhinia tenella (Caesalpinoideae and Vochysia pumila (Vochysiaceae in campo sujo, and Lychnophora ericoides (Asteraceae in campo rupestre. These three species were commonly found at the study sites. In both physiognomies, Heliactin bilophus consumed the nectar of few plant species. The most frequently visited species bore high numbers of flowers.


    Institute of Scientific and Technical Information of China (English)

    蔡学湛; 吴滨; 温珍治


    Relationship between the variations of West Pacific subtropical high indices in the summer half of the year and preceding SST in North Pacific was examined based on a data set of 1951 - 2000. The correlation between the subtropical high indices and preceding SST in the equatorial East Pacific was the strongest among the others, and has great persistency from last autumn to spring. It is indicated that ENSO events appeared about six months earlier than the change of the subtropical high activities, and the subtropical high intensities enhanced (weakened) and western ridge point was westward (eastward) in the year of El Nino(La Nina) events. It was also observed that there were similar interdecadal oscillation and abrupt variations between Nino3 SST, subtropical high intensities and rainfall of rainy season in Fujian. Therefore, experiments were made on rainfall distribution of rainy season in Fujian. The results showed that the distribution was directly affected by the subtropical high activities, pronouncedly caused by ENSO effect.

  3. Impact of low-temperature, overcast and rainy weather during the reproductive growth stage on lodging resistance of rice (United States)

    Weng, Fei; Zhang, Wujun; Wu, Xiaoran; Xu, Xia; Ding, Yanfeng; Li, Ganghua; Liu, Zhenghui; Wang, Shaohua


    The objectives of this study were to explore the mechanism by which the lodging resistance of the rice population during the late growth period responds to low-temperature, overcast and rainy weather during the reproductive growth stage. Field experiments were conducted using indica rice Yliangyou2 (lodging-resistance variety), IIyou084 (lodging-susceptible variety) and japonica rice Wuyunjing23 (lodging-resistance variety) and W3668 (lodging- susceptible variety) in 2013 (high temperature and strong radiation during the rice reproductive growth stage), 2012 and 2014 (low temperature and weak radiation during rice reproductive growth stage). The results showed that the length of the basal internodes and the height of the gravitational centres were greater in plants grown in 2014. Dry weight of basal culms, culm diameter, lignin content and total content of structural carbohydrates (lignin and cellulose) in basal internodes were reduced in these plants, causing a significant reduction in the bending stress and lodging resistance of the rice stems. Low-temperature, overcast and rainy weather had a greater effect on lodging resistance in indica rice compared with japonica rice. This was reflected in a greater reduction in the lignin content of the indica rice stems, which yielded a significantly lower breaking strength and bending stress.

  4. Cadmium, copper and lead in macroalgae from the Veracruz Reef System, Gulf of Mexico: spatial distribution and rainy season variability. (United States)

    Horta-Puga, Guillermo; Cházaro-Olvera, Sergio; Winfield, Ignacio; Avila-Romero, Marisol; Moreno-Ramírez, Margarita


    This study focused on the spatial distribution of trace metals in the Veracruz Reef System in the Southern Gulf of Mexico, and its variability in the early (July) and late (September) rainy season of 2008, by analyzing the concentration of Cd, Cu and Pb in benthic macroalgae. Mean concentrations are lower (Pb 295 ± 347 ng g(-1), Cd 17.9 ± 15.0 ng g(-1)), or similar (Cu 3.4 ± 4.5 μg g(-1)) to those reported from other coastal areas. Cd and Pb concentrations are influenced by the discharge of the Jamapa River, evidencing a fluvial control on coastal trace metal levels. Also, Cd and Cu concentrations were lower in the late rainy season, when there is a high load of suspended sediments derived from fluvial discharge, which probably adsorb dissolved metals decreasing their bioavailability. Pb concentrations have been decreasing in the last two decades in the SGM, after the banning of leaded-gasoline in the late 20th century.

  5. Radiogenic heat production in the continental crust (United States)

    Jaupart, Claude; Mareschal, Jean-Claude; Iarotsky, Lidia


    The thermal structure and evolution of continents depend strongly on the amount and distribution of radioactive heat sources in the crust. Determining the contribution of crustal rocks beneath a superficial layer is a major challenge because heat production depends weakly on major element composition and physical properties such as seismic wavespeed and density. Enriched granitic intrusives that lie at the current erosion level have a large impact on the surface heat flux but little influence on temperatures in the deep crust. Many lower crustal rocks that are poor in heat producing elements are restites from ancient orogenic events, implying that enrichment of the upper crust was achieved at the expense of deeper crustal levels. For the same total heat production, concentrating heat sources in an upper layer acts to reduce temperatures in the lower crust, thereby allowing stabilization of the crust. The present-day structure of the crust is a consequence of orogeny and should not be adopted for thermal models of the orogenic event itself. This review summarizes information extracted from large data sets on heat flow and heat production and provides estimates of crustal stratification and heat production in several geological provinces. Analysis of global and regional data sets reveals the absence of a positive correlation between surface heat flow and crustal thickness, showing that the average crustal heat production is not constant. Differences of heat flow between geological provinces are due in large part to changes of crustal structure and bulk composition. Collating values of the bulk crustal heat production in a few age intervals reveals a clear trend of decrease with increasing age. This trend can be accounted for by radioactive decay, indicating that thermal conditions at the time of crustal stabilization have not changed significantly. For the average crustal thickness of 40 km, Moho temperatures are near solidus values at the time of stabilization

  6. Reconstruction of the past flow channels in the early Holocene at Lake Tonle Sap, Cambodia (United States)

    Haraguchi, T.; Yonenobu, H.; Tokunaga, T.; Shimoda, I.


    Lake Tonle Sap is located at the central part of Cambodia, South-East Asia. In rainy season, the water body swells with the water depth accordingly increasing from 1 up to 10 meters due to a pulsive intrusion from the Mekong River. The lake is therefore a vital reservoir that protects the region from flooding. It is paleolimnologically important to better understand how the lake has gained the function controlling water balance of this region. We undertook an extensive echo-sounding exploration at the lake in order to clarify the subsurface structure of Lake Tonle Sap. The survey was conducted in rainy seasons from 2009 to 2012. Sediment cores were collected at three sites at the middle part of the lake. Echo sounding was undertaken over the whole part of the lake using a single-channel sub-bottom profiling system (Stratabox, SyQwest Inc.). A prominent sound frequency of 10 KHz was selected in order to observe structure of reflectance planes up to the 40-m depth. In consequence, we discovered deposited valleys forming a complex network of past flow channels. The subsurface structure of the lake bed was mostly complacent showing a strongly reflecting plane observed at the depth of 1-2 meters; the sediments mainly consisted of mud. A number of valley-shaped reflecting planes were observed at the depth of 10-14 meters. Radiocarbon dates of carbonaceous materials collected at the vally bottom were around 10 ka calBP. A 3-D reconstruction presented a complex network of deposited flow channels.

  7. The algal growth-limiting nutrient of lakes located at Mexico’s Mesa Central

    Directory of Open Access Journals (Sweden)

    Fernando W. Bernal-Brooks


    Full Text Available This paper reports on the algal growth-limiting nutrients of five lakes located on Mexico’s Mesa Central - a topic poorly known in the regional limnology of Mexico. The five case studies involved three contiguous watersheds of Michoacán State and provided a trophic state variation from mesotrophic to hypereutrophic; the case studies included Lakes Zirahuén, Pátzcuaro, Teremendo, Cuitzeo and the Cointzio Reservoir. The fieldwork involved the collection of physical and chemical data (including nutrients from each case study during the dry and rainy seasons of 2010. Additionally, water samples (1 L were obtained and filtered (0.45 µm in the laboratory to keep the nutrient content available for bioassays. The chemical analyses suggested a phosphorus (P limitation in the Cointzio Reservoir, Lake Teremendo and Lake Zirahuén relative to an N:P>16:1. There was a nitrogen (N limitation at three sampling stations of Lake Pátzcuaro, with an N:P<16:1. As result of the bioassays conducted in July 2012, the Cointzio Reservoir and Lake Teremendo appeared to be P-limited and Lake Pátzcuaro appeared to be N-limited at three sampling stations. Lake Zirahuén showed seasonal variation, with an N limitation during the dry season and a P limitation during the wet season. Those cases with similar results from both methods confirmed the limiting nutrient identification. Lake Cuitzeo, Lake Zirahuén (dry season, and the shallowest sampling station in Lake Pátzcuaro produced unclear results because of divergent outcomes. In terms of the algal growth potential, the Cointzio Reservoir remained unaltered from one season to the next. However, for most of the lakes (with the exception of Lake Pátzcuaro sites 2 and 4, the rainy season provided a dilution effect. Effective lake management depends on a clear recognition of such elements that are in control of the aquatic productivity. In the area of Michoacán, both N and P may act as limiting nutrients.

  8. Longitudinal photosynthetic gradient in crust lichens' thalli. (United States)

    Wu, Li; Zhang, Gaoke; Lan, Shubin; Zhang, Delu; Hu, Chunxiang


    In order to evaluate the self-shading protection for inner photobionts, the photosynthetic activities of three crust lichens were detected using Microscope-Imaging-PAM. The false color images showed that longitudinal photosynthetic gradient was found in both the green algal lichen Placidium sp. and the cyanolichen Peltula sp. In longitudinal direction, all the four chlorophyll fluorescence parameters Fv/Fm, Yield, qP, and rETR gradually decreased with depth in the thalli of both of these two lichens. In Placidium sp., qN values decreased with depth, whereas an opposite trend was found in Peltula sp. However, no such photosynthetic heterogeneity was found in the thalli of Collema sp. in longitudinal direction. Microscope observation showed that photobiont cells are compactly arranged in Placidium sp. and Peltula sp. while loosely distributed in Collema sp. It was considered that the longitudinal photosynthetic heterogeneity was ascribed to the result of gradual decrease of incidence caused by the compact arrangement of photobiont cells in the thalli. The results indicate a good protection from the self-shading for the inner photobionts against high radiation in crust lichens.

  9. Mesoscopic pinning forces in neutron star crusts

    CERN Document Server

    Seveso, Stefano; Grill, Fabrizio; Haskell, Brynmor


    The crust of a neutron star is thought to be comprised of a lattice of nuclei immersed in a sea of free electrons and neutrons. As the neutrons are superfluid their angular momentum is carried by an array of quantized vortices. These vortices can pin to the nuclear lattice and prevent the neutron superfluid from spinning down, allowing it to store angular momentum which can then be released catastrophically, giving rise to a pulsar glitch. A crucial ingredient for this model is the maximum pinning force that the lattice can exert on the vortices, as this allows us to estimate the angular momentum that can be exchanged during a glitch. In this paper we perform, for the first time, a detailed and quantitative calculation of the pinning force \\emph{per unit length} acting on a vortex immersed in the crust and resulting from the mesoscopic vortex-lattice interaction. We consider realistic vortex tensions, allow for displacement of the nuclei and average over all possible orientation of the crystal with respect to...

  10. Shear modulus of neutron star crust

    CERN Document Server

    Baiko, D A


    Shear modulus of solid neutron star crust is calculated by thermodynamic perturbation theory taking into account ion motion. At given density the crust is modelled as a body-centered cubic Coulomb crystal of fully ionized atomic nuclei of one type with the uniform charge-compensating electron background. Classic and quantum regimes of ion motion are considered. The calculations in the classic temperature range agree well with previous Monte Carlo simulations. At these temperatures the shear modulus is given by the sum of a positive contribution due to the static lattice and a negative $\\propto T$ contribution due to the ion motion. The quantum calculations are performed for the first time. The main result is that at low temperatures the contribution to the shear modulus due to the ion motion saturates at a constant value, associated with zero-point ion vibrations. Such behavior is qualitatively similar to the zero-point ion motion contribution to the crystal energy. The quantum effects may be important for li...

  11. Crusted Demodicosis in an Immunocompetent Pediatric Patient

    Directory of Open Access Journals (Sweden)

    Guillermo Antonio Guerrero-González


    Full Text Available Demodicosis refers to the infestation by Demodex spp., a saprophytic mite of the pilosebaceous unit. Demodex proliferation can result in a number of cutaneous disorders including pustular folliculitis, pityriasis folliculorum, papulopustular, and granulomatous rosacea, among others. We report the case of a 7-year-old female presenting with pruritic grayish crusted lesions over her nose and cheeks, along with facial erythema, papules, and pustules. The father referred chronic use of topical steroids. A potassium hydroxide mount of a pustule scraping revealed several D. folliculorum mites. Oral ivermectin (200 μg/kg, single dose plus topical permethrin 5% lotion applied for 3 consecutive nights were administered. Oral ivermectin was repeated every week and oral erythromycin plus topical metronidazole cream was added. The facial lesions greatly improved within the following 3 months. While infestation of the pilosebaceous unit by Demodex folliculorum mites is common, only few individuals present symptoms. Demodicosis can present as pruritic papules, pustules, plaques, and granulomatous facial lesions. To our knowledge, this is the first reported case of facial crusted demodicosis in an immunocompetent child. The development of symptoms in this patient could be secondary to local immunosuppression caused by the chronic use of topical steroids.

  12. Does subduction zone magmatism produce average continental crust (United States)

    Ellam, R. M.; Hawkesworth, C. J.


    The question of whether present day subduction zone magmatism produces material of average continental crust composition, which perhaps most would agree is andesitic, is addressed. It was argued that modern andesitic to dacitic rocks in Andean-type settings are produced by plagioclase fractionation of mantle derived basalts, leaving a complementary residue with low Rb/Sr and a positive Eu anomaly. This residue must be removed, for example by delamination, if the average crust produced in these settings is andesitic. The author argued against this, pointing out the absence of evidence for such a signature in the mantle. Either the average crust is not andesitic, a conclusion the author was not entirely comfortable with, or other crust forming processes must be sought. One possibility is that during the Archean, direct slab melting of basaltic or eclogitic oceanic crust produced felsic melts, which together with about 65 percent mafic material, yielded an average crust of andesitic composition.

  13. Methanotrophy and chemoautotrophy within the redox gradient of a large and deep tropical lake (Lake Kivu, East Africa) (United States)

    Morana, Cedric; Borges, Alberto V.; Darchambeau, François; Roland, Fleur; Montante, Laetitia; Descy, Jean-Pierre; Bouillon, Steven


    Lake Kivu (East Africa) is a large (2370 km2) and deep (maximum depth of 485 m) meromictic lake. Its vertical structure consists of an oxic and nutrient-poor mixed layer down to 70 m maximum, and a permanently anoxic monimolimnion rich in dissolved gases (methane and carbon dioxide) and inorganic nutrients. Seasonal variation of the vertical position of the oxic-anoxic interface is driven by contrasting precipitation and wind speed regimes between rainy (October-May) and dry (June-September) season, the latter being characterized by a deepening of the oxic zone, and an increased input of dissolved gases and inorganic nutrients. Our work aimed at quantifying methanotrophic and chemoautotrophic production within the redox gradient of Lake Kivu and identifying the micro-organisms involved in these processes using phospholipid-derived fatty acid markers and their carbon stable isotope composition. Our approach combined both natural stable isotope abundance analysis and 13C-labelling (13C-DIC ; 13C-CH4) experiments. Sampling was carried out at two stations in Lake Kivu during rainy (February 2012) and dry (September 2012) season conditions. Methanotrophic bacterial production rates were highly variable (from 0.1 to 7.0 μmol C L-1 d-1), but maximum values were always observed at the oxic-anoxic interface when the CH4:O2 ratio varied between 0.1 and 10, suggesting that the majority of methane was oxidized aerobically. Furthermore, strong stable isotope labelling of monounsaturated C16 fatty acids indicate that active methane oxidizers were related to the group of type I aerobic methanotrophs (gammaproteobacteria). Despite the dominance of aerobic methane oxidation, significant methanotrophic bacterial production rates were found below the oxic-anoxic interface during the rainy season, indicating that at least a fraction of the upcoming methane may be oxidized anaerobically. This observation was further confirmed by the strong labelling at these depths of the 10Me16

  14. Semen variables and sperm membrane protein profile of Saanen bucks ( Capra hircus) in dry and rainy seasons of the northeastern Brazil (3°S) (United States)

    van Tilburg, M. F.; Salles, M. G. F.; Silva, M. M.; Moreira, R. A.; Moreno, F. B.; Monteiro-Moreira, A. C. O.; Martins, J. A. M.; Cândido, M. J. D.; Araújo, A. A.; Moura, A. A. A.


    The Saanen is a highly productive breed, and for this reason, it has been raised in Brazil, but mostly under climate conditions completely different from where the breed originated. The objective of this study was to investigate variations in semen parameters and sperm membrane proteins from Saanen bucks ( n = 7) raised in Northeastern Brazil, during dry season (September, October, and November) and rainy season (March, April, and May). We showed that during the dry season, sperm motility, concentration, and the percentage of normal sperm decreased as compared to the rainy season. Rectal temperatures of bucks had no significant ( p > 0.05) variations during the dry and rainy seasons. However, temperatures of left and right skin testis were higher ( p < 0.05) during the dry as compared to the rainy season. Expression of three proteins (lysine-specific demethylase 5D, adenosine triphosphate (ATP) synthase subunit d, and radial spoke head protein 9 homolog) in sperm membrane were more intense in rainy season and only one protein (cytosol aminopeptidase) had greater expression in the dry season of the year. Our results show that mechanisms of testicular thermoregulation of Saanen bucks did not prevent a decrease in seminal parameters during the dry season. This deterioration may be related to reduced expression of proteins associated with important functions in sperm membrane.

  15. Meteorological context of the onset and end of the rainy season in Central Amazonia during the GoAmazon2014/5

    Directory of Open Access Journals (Sweden)

    J. A. Marengo


    Full Text Available The onset and demise of the rainy season in Amazonia are assessed in this study using meteorological data from the GoAmazon experiment, with a focus on the 2014–2015 rainy season. In addition, global reanalyses are also used to identify changes in circulation leading to the establishment of the rainy season in the region. Our results show that the onset occurred in January 2015, 2–3 pentads later than normal, and the rainy season during the austral summer of 2015 contained several periods with consecutive dry days in both Manacapuru and Manaus, which are not common for the wet season, and resulted in below-normal precipitation. The onset of the rainy season has been strongly associated with changes in large-scale weather conditions in the region due to the effect of the Madden–Julian Oscillation (MJO. Regional thermodynamic indices and the height of the boundary layer did not present a significant difference between the onset and demise of the wet season of 2015. This suggests that local changes, such as those in the regional thermodynamic characteristics, may not have influenced its onset. Thus, variability of the large-scale circulation was responsible for regional convection and rainfall changes in Amazonia during the austral summer of 2014–2015.

  16. A Crust-based Method of Reconstructing Human Bone

    Institute of Scientific and Technical Information of China (English)

    MA Shu-chao; LIU Yi


    We present a crust-based procedure for modeling human being’s bone, which is based on voronoi diagram and its dual, Delaunay triangulation. In three-dimensional space, the crust algorithm can generate a 3D-model using a set of sample points. The purposes of this paper is to extract precise contour from CT series, then refer to these contours as sample points, and then apply the crust algorithm to these sample points to get three dimensional mesh.

  17. Cementing mechanism of algal crusts from desert area

    Institute of Scientific and Technical Information of China (English)


    34-, 17-, 4-, 1.5-year old natural algal crusts were collected from Shapotou Scientific Station of the Chinese Academy of Sciences, 40-day old field and greenhouse artificial algal crusts were in situ developed in the same sandy soil and the same place (37°27′N, 104°57′E). Their different cohesions both against wind force and pressure were measured respectively by a sandy wind-tunnel experiment and a penetrometer. On the basis of these algal crusts, the cementing mechanism was revealed from many subjects and different levels. The results showed that in the indoor artificial crusts with the weakest cohesion bunchy algal filaments were distributed in the surface of the crusts, produced few extracellular polymers (EPS), the binding capacity of the crusts just accomplished by mechanical bundle of algal filaments. For field crusts, most filaments grew toward the deeper layers of algal crusts, secreted much more EPS, and when organic matter content was more than 2.4 times of chlorophyll a, overmuch organic matter (primarily is EPS) began to gather onto the surface of the crusts and formed an organic layer in the relatively lower micro-area, and this made the crust cohesion increase 2.5 times. When the organic layer adsorbed and intercepted amounts of dusts, soil particles and sand grains scattered down from wind, it changed gradually into an inorganic layer in which inorganic matter dominated, and this made the crusts cohesion further enhanced 2-6 times. For crust-building species Microcoleus vaginatus, 88.5% of EPS were the acidic components, 78% were the acidic proteglycan of 380 kD. The uronic acid content accounted for 8% of proteglycan, and their free carboxyls were important sites of binding with metal cations from surrounding matrix.

  18. Treatment of crusted scabies with albendazole: A case report. (United States)

    Douri, Thaer; Shawaf, A Z


    Crusted scabies is a severe variant of scabies caused by the ectoparasite Sarcoptes scabiei. It is characterized by high mite burden, extensive hyperkeratotic scaling, crusted lesions, variable pruritus, generalized lymphadenopathy, erythroderma, and eosinophilia, in some cases. There is an increased incidence of crusted scabies, particularly among patients with HIV infection. We describe a 22-year-old Syrian immunocompetent female who had hyperkeratotic psoriasiform plaques and hyperkeratosis without itching. She was treated with oral albendazole and topical crotamiton with salicylic acid 5 percent.

  19. Scales of Heterogeneities in the Continental Crust and Upper Mantle


    M. Tittgemeyer; F. Wenzel; Trond Ryberg; Fuchs, K


    A seismological characterization of crust and upper mantle can refer to large-scale averages of seismic velocities or to fluctuations of elastic parameters. Large is understood here relative to the wavelength used to probe the earth. In this paper we try to characterize crust and upper mantle by the fluctuations in media properties rather than by their average velocities. As such it becomes evident that different scales of heterogeneities prevail in different layers of crust mantle. Although ...

  20. Sero-epidemiological evaluation of changes in Plasmodium falciparum and Plasmodium vivax transmission patterns over the rainy season in Cambodia

    Directory of Open Access Journals (Sweden)

    Cook Jackie


    Full Text Available Abstract Background In Cambodia, malaria transmission is low and most cases occur in forested areas. Sero-epidemiological techniques can be used to identify both areas of ongoing transmission and high-risk groups to be targeted by control interventions. This study utilizes repeated cross-sectional data to assess the risk of being malaria sero-positive at two consecutive time points during the rainy season and investigates who is most likely to sero-convert over the transmission season. Methods In 2005, two cross-sectional surveys, one in the middle and the other at the end of the malaria transmission season, were carried out in two ecologically distinct regions in Cambodia. Parasitological and serological data were collected in four districts. Antibodies to Plasmodium falciparum Glutamate Rich Protein (GLURP and Plasmodium vivax Merozoite Surface Protein-119 (MSP-119 were detected using Enzyme Linked Immunosorbent Assay (ELISA. The force of infection was estimated using a simple catalytic model fitted using maximum likelihood methods. Risks for sero-converting during the rainy season were analysed using the Classification and Regression Tree (CART method. Results A total of 804 individuals participating in both surveys were analysed. The overall parasite prevalence was low (4.6% and 2.0% for P. falciparum and 7.9% and 6.0% for P. vivax in August and November respectively. P. falciparum force of infection was higher in the eastern region and increased between August and November, whilst P. vivax force of infection was higher in the western region and remained similar in both surveys. In the western region, malaria transmission changed very little across the season (for both species. CART analysis for P. falciparum in the east highlighted age, ethnicity, village of residence and forest work as important predictors for malaria exposure during the rainy season. Adults were more likely to increase their antibody responses to P. falciparum during the

  1. Bathymetry of Lake Michigan (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Bathymetry of Lake Michigan has been compiled as a component of a NOAA project to rescue Great Lakes lake floor geological and geophysical data and make it more...

  2. Bathymetry of Lake Ontario (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Bathymetry of Lake Ontario has been compiled as a component of a NOAA project to rescue Great Lakes lake floor geological and geophysical data and make it more...

  3. Designated Wildlife Lakes - points (United States)

    Minnesota Department of Natural Resources — This is a point shapefile of Designated Wildlife Lakes in Minnesota. This shapefile was created by converting lake polygons from the Designated Wildlife Lakes...

  4. Great Lakes Bathymetry (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Bathymetry of Lakes Michigan, Erie, Saint Clair, Ontario and Huron has been compiled as a component of a NOAA project to rescue Great Lakes lake floor geological and...

  5. Bathymetry of Lake Superior (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Bathymetry of Lake Superior has been compiled as a component of a NOAA project to rescue Great Lakes lake floor geological and geophysical data and make it more...

  6. Hydrography - Lakes Assessments - Attaining (United States)

    NSGIC GIS Inventory (aka Ramona) — This layer shows only attaining lakes of the Integrated List. The Lakes Integrated List represents lake assessments in an integrated format for the Clean Water Act...

  7. Bathymetry of Lake Huron (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Bathymetry of Lake Huron has been compiled as a component of a NOAA project to rescue Great Lakes lake floor geological and geophysical data and make it more...

  8. Drilling the Oceanic Lower Crust and Mantle (United States)


    compositional range observed in basaltic lava lakes, sills, and plutons like Skaergaard . The tuning of convection, crystallization kinetics, and phase...during the initial stages of the opening of the North Atlantic Ocean. Field and petrographic investigation of the Skaergaard intrusion, the Kruuse*Fjord...compositions, olivine varying from Fo03 to Fo30, that is comparable to what is observed in layered intrusions like the Bushveld and Skaergaard

  9. Crust formation and its effect on the molten pool coolability

    Energy Technology Data Exchange (ETDEWEB)

    Park, R.J.; Lee, S.J.; Sim, S.K. [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)


    Experimental and analytical studies of the crust formation and its effect on the molten pool coolability have been performed to examine the crust formation process as a function of boundary temperatures as well as to investigate heat transfer characteristics between molten pool and overlying water in order to evaluate coolability of the molten pool. The experimental test results have shown that the surface temperature of the bottom plate is a dominant parameter in the crust formation process of the molten pool. It is also found that the crust thickness of the case with direct coolant injection into the molten pool is greater than that of the case with a heat exchanger. Increasing mass flow rate of direct coolant injection to the molten pool does not affect the temperature of molten pool after the crust has been formed in the molten pool because the crust behaves as a thermal barrier. The Nusselt number between the molten pool and the coolant of the case with no crust formation is greater than that of the case with crust formation. The results of FLOW-3D analyses have shown that the temperature distribution contributes to the crust formation process due to Rayleigh-Benard natural convection flow.

  10. Quantifying glassy and crystalline basalt partitioning in the oceanic crust (United States)

    Moore, Rachael; Ménez, Bénédicte


    The upper layers of the oceanic crust are predominately basaltic rock, some of which hosts microbial life. Current studies of microbial life within the ocean crust mainly focus on the sedimentary rock fraction, or those organisms found within glassy basalts while the potential habitability of crystalline basalts are poorly explored. Recently, there has been recognition that microbial life develops within fractures and grain boundaries of crystalline basalts, therefore estimations of total biomass within the oceanic crust may be largely under evaluated. A deeper understanding of the bulk composition and fractionation of rocks within the oceanic crust is required before more accurate estimations of biomass can be made. To augment our understanding of glassy and crystalline basalts within the oceanic crust we created two end-member models describing basalt fractionation: a pillow basalt with massive, or sheet, flows crust and a pillow basalt with sheeted dike crust. Using known measurements of massive flow thickness, dike thickness, chilled margin thickness, pillow lava size, and pillow lava glass thickness, we have calculated the percentage of glassy versus crystalline basalts within the oceanic crust for each model. These models aid our understanding of textural fractionation within the oceanic crust, and can be applied with bioenergetics models to better constrain deep biomass estimates.

  11. Nitrogen fixation in biological soil crusts from southeast Utah, USA (United States)

    Belnap, J.


    Biological soil crusts can be the dominant source of N for arid land ecosystems. We measured potential N fixation rates biweekly for 2 years, using three types of soil crusts: (1) crusts whose directly counted cells were >98% Microcoleus vaginatus (light crusts); (2) crusts dominated by M. vaginatus, but with 20% or more of the directly counted cells represented by Nostoc commune and Scytonema myochrous (dark crusts); and (3) the soil lichen Collema sp. At all observation times, Collema had higher nitrogenase activity (NA) than dark crusts, which had higher NA than light crusts, indicating that species composition is critical when estimating N inputs. In addition, all three types of crusts generally responded in a similar fashion to climate conditions. Without precipitation within a week of collection, no NA was recorded, regardless of other conditions being favorable. Low (26??C) temperatures precluded NA, even if soils were moist. If rain or snow melt had occurred 3 or less days before collection, NA levels were highly correlated with daily average temperatures of the previous 3 days (r2=0.93 for Collema crusts; r2=0.86 for dark crusts and r2=0.83 for light crusts) for temperatures between 1??C and 26??C. If a precipitation event followed a long dry period, NA levels were lower than if collection followed a time when soils were wet for extended periods (e.g., winter). Using a combination of data from a recording weather datalogger, time-domain reflectometry, manual dry-down curves, and N fixation rates at different temperatures, annual N input from the different crust types was estimated. Annual N input from dark crusts found at relatively undisturbed sites was estimated at 9 kg ha-1 year-1. With 20% cover of the N-fixing soil lichen Collema, inputs are estimated at 13 kg ha-1 year-1. N input from light crusts, generally indicating soil surface disturbance, was estimated at 1.4 kg ha-1 year-1. The rates in light crusts are expected to be highly variable, as

  12. Generation of continental crust in intra-oceanic arcs (United States)

    Gazel, E.; Hayes, J. L.; Kelemen, P. B.; Everson, E. D.; Holbrook, W. S.; Vance, E.


    The origin of continental crust is still an unsolved mystery in the evolution of our planet. Although the best candidates to produce juvenile continental crust are intra-oceanic arcs these systems are dominated by basaltic lavas, and when silicic magmas are produced, the incompatible-element compositions are generally too depleted to be a good match for continental crust estimates. Others, such as the W. Aleutians, are dominated by andesitic melts with trace element compositions similar to average continental crust. In order to evaluate which intra-oceanic arcs produced modern continental crust, we developed a geochemical continental index (CI) through a statistical analysis that compared all available data from modern intra-oceanic arcs with global estimates of continental crust. Our results suggest that magmas from Costa Rica (100 have the least continent-like geochemical signatures. In these arcs the subducting plate is old (>100 Ma), not overprinted by enriched intraplate volcanism and the geochemistry may be dominated by slab-derived, aqueous fluids. We also found a strong correlation between the CI and average crustal P-wave velocity, validating the geochemical index with the available seismic data for intra-oceanic arcs. In conclusion, the production of young continental crust with compositions similar to Archean continental crust is an unusual process, limited to locations where there are especially voluminous partial melts of oceanic crust.

  13. Biological Soil Crusts: Webs of Life in the Desert (United States)

    Belnap, Jayne


    Although the soil surface may look like dirt to you, it is full of living organisms that are a vital part of desert ecosystems. This veneer of life is called a biological soil crust. These crusts are found throughout the world, from hot deserts to polar regions. Crusts generally cover all soil spaces not occupied by green plants. In many areas, they comprise over 70% of the living ground cover and are key in reducing erosion, increasing water retention, and increasing soil fertility. In most dry regions, these crusts are dominated by cyanobacteria (previously called blue-green algae), which are one of the oldest known life forms. Communities of soil crusts also include lichens, mosses, microfungi, bacteria, and green algae. These living organisms and their by-products create a continuous crust on the soil surface. The general color, surface appearance, and amount of coverage of these crusts vary depending on climate and disturbance patterns. Immature crusts are generally flat and the color of the soil, which makes them difficult to distinguish from bare ground. Mature crusts, in contrast, are usually bumpy and dark-colored due to the presence of lichens, mosses, and high densities of cyanobacteria and other organisms.

  14. Crustal redistribution, crust-mantle recycling and Phanerozoic evolution of the continental crust (United States)

    Clift, Peter D.; Vannucchi, Paola; Morgan, Jason Phipps


    We here attempt a global scale mass balance of the continental crust during the Phanerozoic and especially the Cenozoic (65 Ma). Continental crust is mostly recycled back into the mantle as a result of the subduction of sediment in trenches (1.65 km 3/a), by the subduction of eroded forearc basement (1.3 km 3/a) and by the delamination of lower crustal material from orogenic plateaus (ca. 1.1 km 3/a). Subduction of rifted crust in continent-continent collision zones (0.4 km 3/a), and dissolved materials fixed into the oceanic crust (ca. 0.4 km 3/a) are less important crustal sinks. At these rates the entire continental crust could be reworked in around 1.8 Ga. Nd isotope data indicate that ca. 80% of the subducted continental crust is not recycled by melting at shallow levels back into arcs, but is subducted to depth into the upper mantle. Continent-continent collision zones do not generally form new crust, but rather cause crustal loss by subduction and as a result of their physical erosion, which exports crust from the orogen to ocean basins where it may be subducted. Regional sedimentation rates suggest that most orogens have their topography eliminated within 100-200 million years. We estimate that during the Cenozoic the global rivers exported an average of 1.8 km 3/a to the oceans, approximately balancing the subducted loss. Accretion of sediment to active continental margins is a small contribution to crustal construction (ca. 0.3 km 3/a). Similarly, continental large igneous provinces (flood basalts) represent construction of only around 0.12 km 3/a, even after accounting for their intrusive roots. If oceanic plateaus are accreted to continental margins then they would average construction rates of 1.1 km 3/a, meaning that to keep constant crustal volumes, arc magmatism would have to maintain production of around 3.8 km 3/a (or 94 km 3/Ma/km of trench). This slightly exceeds the rates derived from sparse seismic experiments in oceanic arc systems. Although

  15. Great Lakes Science Center (United States)

    Federal Laboratory Consortium — Since 1927, Great Lakes Science Center (GLSC) research has provided critical information for the sound management of Great Lakes fish populations and other important...

  16. Delineating the decadal expansion of Lake Basaka (Ethiopia) using various image interpretation techniques (United States)

    Olumana Dinka, Megersa


    Lake Basaka is expanding at a significant rate. Before the establishment of Matahara Sugar Plantation, the lake was like a small surface pond created during rainy season and used as grazing area. The lake expansion has certain negative consequences to the region. Thus, appropriate method of quantification of the Lake expansion is extremely important. In this particular study, the areal expansion of the Lake Basaka and sugarcane plantation was analysed. Four LandSat images (1973, 1986, 2000 and 2008) were taken for the cloud-free period and processed in ERDAS Imagine and ArcGIS softwares. Three techniques were employed in the delineation of the areas of the lake and plantation: visual interpretation of FCC in GIS, enhancements and advanced classification in ERDAS Imagine. The study result shows that Lake Basaka expansion is very significant and the increment is geometric rather than linear. Overall, the finding indicates that visual image interpretation gives a fast and accurate indication of the Lake Basaka expansion compared to image enhancement and classification techniques.

  17. Characterization of the rainy season in Burkina Faso and it's representation by regional climate models

    Energy Technology Data Exchange (ETDEWEB)

    Ibrahim, B.; Karambiri, H. [Institut International d' Ingenierie de l' Eau et de l' Environnement (2iE), Ouagadougou 01 (Burkina Faso); Polcher, J. [Laboratoire de Meteorologie Dynamique du CNRS, Institut Pierre Simon Laplace, Paris Cedex 05 (France); Rockel, B. [Helmholtz-Zentrum Geesthacht Institute of Coastal Research/Group Regional Atmospheric Modeling, Geesthacht (Germany)


    West African monsoon is one of the most challenging climate components to model. Five regional climate models (RCMs) were run over the West African region with two lateral boundary conditions, ERA-Interim re-analysis and simulations from two general circulation models (GCMs). Two sets of daily rainfall data were generated from these boundary conditions. These simulated rainfall data are analyzed here in comparison to daily rainfall data collected over a network of ten synoptic stations in Burkina Faso from 1990 to 2004. The analyses are based on a description of the rainy season throughout a number of it's characteristics. It was found that the two sets of rainfall data produced with the two driving data present significant biases. The RCMs generally produce too frequent low rainfall values (between 0.1 and 5 mm/day) and too high extreme rainfalls (more than twice the observed values). The high frequency of low rainfall events in the RCMs induces shorter dry spells at the rainfall thresholds of 0.1-1 mm/day. Altogether, there are large disagreements between the models on the simulate season duration and the annual rainfall amounts but most striking are their differences in representing the distribution of rainfall intensity. It is remarkable that these conclusions are valid whether the RCMs are driven by re-analysis or GCMs. In none of the analyzed rainy season characteristics, a significant improvement of their representation can be found when the RCM is forced by the re-analysis, indicating that these deficiencies are intrinsic to the models. (orig.)

  18. Biological soil crusts in a xeric Florida shrubland: composition, abundance, and spatial heterogeneity of crusts with different disturbance histories. (United States)

    Hawkes, C V; Flechtner, V R


    Biological soil crusts consisting of algae, cyanobacteria, lichens, fungi, bacteria, and mosses are common in habitats where water and nutrients are limited and vascular plant cover is discontinuous. Crusts alter soil factors including water availability, nutrient content, and erosion susceptibility, and thus are likely to both directly and indirectly affect plants. To establish this link, we must first understand the crust landscape. We described the composition, abundance, and distribution of microalgae in crusts from a periodically burned, xeric Florida shrubland, with the goal of understanding the underlying variability they create for vascular plants, as well as the scale of that variability. This is the first comprehensive study of crusts in the southeastern United States, where the climate is mesic but sandy soils create xeric conditions. We found that crusts were both temporally and spatially heterogeneous in depth and species composition. For example, cyanobacteria and algae increased in abundance 10-15 years after fire and away from dominant shrubs. Chlorophyll a levels recovered rapidly from small-scale disturbance relative to intact crusts, but these disturbances added to crust patchiness. Plants less than 1 m apart can experience different crust environments that may alter plant fitness, plant interactions, and plant community composition.

  19. Low-Reflectance Material in Mercury's Crust (United States)

    Denevi, B. W.; Robinson, M. S.; Murchie, S. L.; Blewett, D. T.; Holsclaw, G. M.; McClintock, W. E.; McCoy, T. J.; McNutt, R. L.; Solomon, S. C.


    Mercury's reflectance and spectral slope are broadly similar to that of the lunar nearside. However, a host of Earth-based measurements and spacecraft data indicate that the composition and physical makeup of their surfaces may exhibit significant differences. Apollo samples and orbital remote sensing show that the lunar nearside surface is generally high in FeO (6 to 20 wt %) while the farside surface abundance is somewhat lower (3 to 10 wt %). Earth-based remote sensing of Mercury indicates that its surface contains less than 6 wt % FeO and perhaps even lower than 3 wt %. The reflectance of the Moon, and most likely Mercury, is controlled to first order by variations in iron and titanium abundances. If Mercury's ferrous iron content is much lower than that of the lunar nearside, then why is its reflectance comparable (0.019 vs. 0.021 at phase angle 65°, respectively)? Two-color vidicon observations by Mariner 10 revealed patchy low-reflectance, relatively blue units within Mercury's crust. Hapke and coworkers first speculated that opaque minerals (most likely ilmenite) could explain the color and reflectance of this low-reflectance component. Multispectral image data obtained by MESSENGER during its January 2008 flyby of Mercury covered new terrain and provided higher resolution, better signal-to-noise ratio, and extended wavelength coverage above that obtained by Mariner 10. The new data confirmed the existence of the low-reflectance material (LRM) and its relatively blue color and provide much better geologic context to interpret the origin of this material. MESSENGER multispectral data show the LRM to be widespread across the surface and to occur at depth within the crust. Three key observations show the vertical distribution of LRM. First the rims and floors of 100-km-scale craters within the Caloris basin are composed of LRM, streamers of LRM occur in ejecta traceable back to outcrops in crater floors (e.g. Mozart), and large continuous sections of ejecta

  20. Moho vs crust-mantle boundary: Evolution of an idea (United States)

    O'Reilly, Suzanne Y.; Griffin, W. L.


    The concept that the Mohorovicic Discontinuity (Moho) does not necessarily coincide with the base of the continental crust as defined by rock-type compositions was introduced in the early 1980s. This had an important impact on understanding the nature of the crust-mantle boundary using information from seismology and from deep-seated samples brought to the surface as xenoliths in magmas, or as tectonic terranes. The use of empirically-constrained P-T estimates to plot the locus of temperature vs depth for xenoliths defined a variety of geotherms depending on tectonic environment. The xenolith geotherms provided a framework for constructing lithological sections through the deep lithosphere, and revealed that the crust-mantle boundary in off-craton regions commonly is transitional over a depth range of about 5-20 km. Early seismic-reflection data showed common layering near the Moho, correlating with the petrological observation of multiple episodes of basaltic intrusion around the crust-mantle boundary. Developments in seismology, petrophysics and experimental petrology have refined interpretation of lithospheric domains. The expansion of in situ geochronology (especially zircon U-Pb ages and Hf-isotopes; Os isotopes of mantle sulfides) has defined tectonic events that affected whole crust-mantle sections, and revealed that the crust-mantle boundary can change in depth through time. However, the nature of the crust-mantle boundary in cratonic regions remains enigmatic, mainly due to lack of key xenoliths or exposed sections. The observation that the Moho may lie significantly deeper than the crust-mantle boundary has important implications for modeling the volume of the crust. Mapping the crust using seismic techniques alone, without consideration of the petrological problems, may lead to an overestimation of crustal thickness by 15-30%. This will propagate to large uncertainties in the calculation of elemental mass balances relevant to crust-formation processes

  1. Symmetry energy effects in the neutron star crust properties

    CERN Document Server

    Porebska, J


    Different shapes of the nuclear symmetry energy leads to a different crust-core transition point in the neutron star. The basic properties of a crust, like thickness, mass and moment of inertia were investigated for various forms of the symmetry energy.

  2. Continental crust composition constrained by measurements of crustal Poisson's ratio (United States)

    Zandt, George; Ammon, Charles J.


    DECIPHERING the geological evolution of the Earth's continental crust requires knowledge of its bulk composition and global variability. The main uncertainties are associated with the composition of the lower crust. Seismic measurements probe the elastic properties of the crust at depth, from which composition can be inferred. Of particular note is Poisson's ratio,Σ ; this elastic parameter can be determined uniquely from the ratio of P- to S-wave seismic velocity, and provides a better diagnostic of crustal composition than either P- or S-wave velocity alone1. Previous attempts to measure Σ have been limited by difficulties in obtaining coincident P- and S-wave data sampling the entire crust2. Here we report 76 new estimates of crustal Σ spanning all of the continents except Antarctica. We find that, on average, Σ increases with the age of the crust. Our results strongly support the presence of a mafic lower crust beneath cratons, and suggest either a uniformitarian craton formation process involving delamination of the lower crust during continental collisions, followed by magmatic underplating, or a model in which crust formation processes have changed since the Precambrian era.

  3. Structure of the Crust and the Lithosperic Mantle in Siberia

    DEFF Research Database (Denmark)

    Cherepanova, Yulia

    the development of a new regional crustal model, SibCrust, that is a digital crustal model for both the Siberian Craton and the West Siberian Basin. The SibCrust model, constrained by digitizing of all available seismic profiles and crustal velocity models across the Siberia, also includes a critical quality...

  4. Estimation of the eddy diffusivity coefficient in a warm monomictic tropical Lake

    Directory of Open Access Journals (Sweden)

    David A. Salas de León


    Full Text Available We used a two-year dataset (1998-1999 of monthly temperature profiles from Lake Alchichica, Mexico to estimate values of the vertical coefficient of eddy diffusivity. This lake is located in a tropical region at high altitude and shows considerable seasonal variations (i.e., rainy and dry seasons. It has an area of 2.3 km2 and a mean depth of 40.9 m. Alchichica is a warm monomictic lake, which annually becomes isothermal near the end of December or early January at the onset of the dry season and remains stratified for the rest of the year (from late March or early April to early December during the warm-rainy season. Mathematical models of the spatial and temporal variation of passive substances in lakes and oceans require a quantitative formulation of the vertical transport. Vertical mixing is generally a function of the density profile, which, in lakes, can be directly related to the temperature profile. A widely used method to estimate the vertical diffusion coefficients in lakes from temperature data is the flux-gradient method. In the present study, we applied a simple approach to calculate the eddy diffusivity coefficient (Kz based on the solution of the vertical component of the modeled temperature equation. We characterized the eddy diffusivity coefficient (Kz in Lake Alchichica as a dynamic coefficient that changes during the year, between years, and with depth, ranging from 10-10 to 10-6 m2 s-1, whereas typical values of Kz in thermally stratified lakes range from 10-9 to 10-2 m2 s-1. As expected, we found the lowest values in the deeper regions of the lake, and that the temporal variation of temperature with depth showed a quasi-bimodal shape from one year to the next. We also found a structure of alternating peaks and troughs in the vertical Kz, which indicates a response to oscillating vertical mixing. We concluded that the solution of the vertical component of the temperature equation could be a useful tool to estimate the eddy

  5. Field temperature measurements at Erta'Ale Lava Lake, Ethiopia (United States)

    Burgi, Pierre-Yves; Caillet, Marc; Haefeli, Steven


    The shield volcano Erta'Ale, situated in the Danakil Depression, Ethiopia, is known for its active lava lake. In February 2001, our team visited this lake, located inside an 80-m-deep pit, to perform field temperature measurements. The distribution and variation of temperature inside the lake were obtained on the basis of infrared radiation measurements performed from the rim of the pit and from the lake shores. The crust temperature was also determined from the lake shores with a thermocouple to calibrate the pyrometer. We estimated an emissivity of the basalt of 0.74 from this experiment. Through the application of the Stefan-Boltzmann law, we then obtained an estimate of the total radiative heat flux, constrained by pyrometer measurements of the pit, and visual observations of the lake activity. Taking into account the atmospheric convective heat flux, the convected magma mass flux needed to balance the energy budget was subsequently derived and found to represent between 510 and 580 kg s-1. The surface circulation of this mass flux was also analyzed through motion processing techniques applied to video images of the lake. Electronic supplementary material to this paper can be obtained by using the Springer LINK server located at

  6. Continental Crust Growth as a Result of Continental Collision: Ocean Crust Melting and Melt Preservation (United States)

    Niu, Y.; Zhao, Z.; Zhou, S.; Zhu, D.; Dong, G.; Mo, X.; Xie, G.; Dong, X.


    The significance of the continental crust (CC) on which we live is self-evident. However, our knowledge remains limited on its origin, its way and rate of growth, and how it has acquired the “andesitic” composition from mantle derived magmas. Compared to rocks formed from mantle derived magmas in all tectonic settings, volcanic arc rocks associated with oceanic lithosphere subduction share some common features with the CC; both are relatively depleted in “fluid-insoluble” elements (e.g., Nb, Ta and Ti), but enriched in “fluid-soluble” elements (e.g., U, K and Pb). These chemical characteristics are referred to as the “arc-like signature”, and point to a genetic link between subduction-zone magmatism and CC formation, thus leading to the “island-arc” model widely accepted for the origin of the CC over the past 40 years. However, it has been recognized also that this “island-arc” model has several difficulties. These include (1) bulk arc crust (AC) is basaltic, whereas the bulk CC is andesitic [1]; (2) AC has a variably large Sr excess whereas the CC is Sr deficient [2]; and (3) AC production is mass-balanced by subduction-erosion and sediment recycling, thus contributing no new mass to CC growth, at least in the Phanerozoic [3,4]. Our data on magmatic rocks (both volcanic and intrusive) formed during the India-Asia continental collision (~65 - ~45Ma) [5] show a remarkable compositional similarity to the bulk CC with the typical “arc-like signature” [6]. Also, these syncollisional felsic rocks exhibit strong mantle isotopic signatures, implying that they were recently derived from a mantle source. The petrology and geochemistry of these syncollisional felsic rocks is most consistent with an origin via partial melting of upper oceanic crust (i.e., last fragments of underthrusting oceanic crust) under amphibolite facies conditions, adding net mantle-derived materials to form juvenile CC mass. This leads to the logical and testable hypothesis

  7. Sublacustrine precipitation of hydrothermal silica in rift lakes: evidence from Lake Baringo, central Kenya Rift Valley (United States)

    Renaut, R. W.; Jones, B.; Tiercelin, J.-J.; Tarits, C.


    Many lakes in volcanic regions are fed by hot springs that, in some basins, can contribute a large percentage of the annual recharge, especially during times of aridity. It is important to recognize any contemporary hydrothermal contribution in paleoenvironmental reconstruction of lake basins because recharge from thermal waters can potentially confuse paleoclimatic signals preserved in the lacustrine sedimentary record. Hot spring deposits (travertine, sinter) provide the most tangible evidence for thermal recharge to lakes. Although subaerial spring deposits have been widely studied, lacustrine thermal spring deposits, especially sublacustrine siliceous sinters, remain poorly known. Detailed field, petrographic and scanning electron microscope (SEM) studies have been made of fossil sublacustrine sinter exposed at Soro hot springs along the northeastern shoreline of Ol Kokwe, a volcanic island in Lake Baringo, Kenya. Modern hot springs at Soro, which discharge Na-HCO 3-Cl waters from a deep reservoir (˜180 °C ), have thin (1-10 mm), friable microbial silica crusts around their subaerial vents, but thicker (>1 cm) sinter deposits are not forming. The fossil sinter, which is present as intergranular cements and crusts in littoral conglomerates and sandstones, is composed mainly of opaline silica (opal-A). Three types of fossil sinter are recognized: (1) massive structureless silica, which fills intergranular pores and forms crusts up to 5 cm thick; (2) pore-lining silica, some of which is isopachous, and (3) laminated silica crusts, which formed mainly on the upper surfaces of detrital particles. All three types contain well-preserved diatoms including lacustrine planktonic forms. Microbial remains, mainly filamentous and coccoid bacteria (including cyanobacteria) and extracellular polymeric gels, are locally abundant in the opaline silica, together with detrital clays and thin laminae composed of authigenic chlorite (?). Most of the hydrothermal silica

  8. Development of Soil Crusts Under Simulated Rainfall and Crust Formation on a Loess Soil as Influenced by Polyacrylamide

    Institute of Scientific and Technical Information of China (English)

    HU Xia; LIU Lian-You; LI Shun-Jiang; CAI Qiang-Guo; L(U) Yan-Li; GUO Jin-Rui


    This study evaluated the morphological characteristics and dynamic variation in characteristics of soil crust and identified the relationships between soil crust and splash erosion under simulated rainfall.The effect of polyacrylamide (PAM) on soil aggregate stabilization and crust formation was also investigated.A laboratory rainfall simulation experiment was carried out using soil sample slices.The slices were examined under a polarized light microscopy and a scanning electron microscope (SEM).The results revealed that the soil crusts were thin and were characterized by a greater density,higher shear strength,finer porosity,and lower saturated hydraulic conductivity than the underlying soil.Two types of crusts,i.e.,structural and depositional crusts,were observed.Soil texture was determined to be the most important soil variable influencing surface crust formation; depositional crust formation was primarily related to the skeleton characteristics of the soil and happened when the soil contained a high level of medium and large aggregates.The crust formation processes observed were as follows:1) The fine particles on the soil surface became spattered,leached,and then rough in response to raindrop impact and 2) the fine particles were washed into the subsoil pores while a compact dense layer concurrently formed at soil surface due to the continual compaction by the raindrops.Therefore,the factors that influenced structural crust formation were a large amount of fine particles in the soil surface,continual impact of raindrops,dispersion of aggregates into fine particles,and the formation of a compact dense layer concurrently at the soil surface.It was concluded that the most important factor in the formation of soil crusts was raindrop impact.When polyacrylamide (PAM) was applied,it restored the soil structure and greatly increased soil aggregate stabilization.This effectively prevented crust formation.However,this function of PAM was not continuously effective and

  9. Dust Generation Resulting from Desiccation of Playa Systems: Studies on Mono and Owens Lakes, California (United States)

    Gill, Thomas Edward


    Playas, evaporites, and aeolian sediments frequently are linked components within the Earth system. Anthropogenic water diversions from terminal lakes form playas that release fugitive dust. These actions, documented worldwide, simulate aeolian processes activated during palaeoclimatic pluvial/interpluvial transitions, and have significant environmental impacts. Pluvial lakes Russell and Owens in North America's Great Basin preceded historic Mono and Owens Lakes, now desiccated by water diversions into dust-generating, evaporite -encrusted playas. Geochemical and hydrologic cycles acting on the Owens (Dry) Lake playa form three distinct crust types each year. Although initial dust production results from deflation of surface efflorescences after the playa dries, most aerosols are created by saltation abrasion of salt/silt/clay crusts at crust/ sand sheet contacts. The warm-season, clastic "cemented" crust is slowest to degrade into dust. If the playa surface is stabilized by an unbroken, non-efflorescent crust, dust formation is discouraged. When Mono Lake's surFace elevation does not exceed 1951 meters (6400 feet), similar processes will also generate dust from its saline lower playa. Six factors--related to wind, topography, groundwater, and sediments--control dust formation at both playas. These factors were combined into a statistical model relating suspended dust concentrations to playa/lake morphometry. The model shows the extent and severity of Mono Lake dust storms expands significantly below the surface level 6376 feet (1943.5 meters). X-ray diffraction analysis of Mono Basin soils, playa sediments, and aerosols demonstrates geochemical cycling of materials through land, air and water during Mono Lake's 1982 low stand. Soils and clastic playa sediments contain silicate minerals and tephra. Saline groundwater deposited calcite, halite, thenardite, gaylussite, burkeite and glauberite onto the lower playa. Aerosols contained silicate minerals (especially

  10. Koerajuhi amet lisab tavatööle vürtsi / Rainer Lang, Andres Vesselov, Rainis Oper ; interv. Tanel Saarmann

    Index Scriptorium Estoniae

    Lang, Rainer


    Koerajuhid piirivalve-seersant Rainer Lang Saatsest, piirivalve-veebel Rainis Oper Värskast ning Saatse kordoni ülem piirivalve-kapten Andres Vesselov räägivad koerajuhiks saamisest ning teenistuskoerte koolitamisest. Lisa: Kagu PVP teenistuskoerad; Osalemine võistlustel 2008

  11. Statistical analysis of the relationship between climate-induced maize yield and rainy-season precipitation across Inner Mongolia, North China (United States)

    Huang, Jin; Chen, Xin; Zhou, Limin; Xue, Yan; Lin, Jie


    Exploring possible relationships between climate-induced maize yield and rainy-season precipitation under climate change is fundamental to science-based decision for food security in Inner Mongolia Autonomous Region (IMAR). To determine the relationship of maize yield with precipitation variables across IMAR during 1960-2012, we selected 11 precipitation indices of rainy season and divided IMAR into four sub-regions—west, middle, east, and northeast using principal component analysis and K-means clustering methods. Results show that climate-induced maize yield is more sensitive to precipitation variability in the west and middle IMAR. The most important precipitation factor that limits maize yield is moderate precipitation days in these two sub-regions. Moreover, west and middle Inner Mongolia was dominated by decreasing precipitation during the rainy season. Furthermore, the El Niño/La Niña-Southern Oscillation cycle has the significant influence on the rainy-season precipitation in the west and middle IMAR.

  12. Depletion of Stem Water of Sclerocarya birrea Agroforestry Tree Precedes Start of Rainy Season in West African Sudanian Zone (United States)

    Ceperley, Natalie; Mande, Theophile; Parlange, Marc B.


    Understanding water use by agroforestry trees in dry-land ecosystems is essential for improving water management. Agroforestry trees are valued and promoted for many of their ecologic and economic benefits but are often criticized as competing for valuable water resources. In order to understand the seasonal patterns of source water used by agroforestry trees, samples from rain, ground, and surface water were collected weekly in the subcatchment of the Singou watershed that is part of the Volta Basin. Soil and vegetation samples were collected from and under a Sclerocarya birrea agroforstry trees located in this catchment in sealed vials, extracted, and analyzed with a Picarro L2130-i CRDS to obtain both δO18 and δDH fractions. Meteorological measurements were taken with a network of wireless, autonomous stations that communicate through the GSM network (Sensorscope) and two complete eddy-covariance energy balance stations, in addition to intense monitoring of sub-canopy solar radiation, throughfall, stemflow, and soil moisture. Examination of the time series of δO18 concentrations confirm that values in soil and xylem water are coupled, both becoming enriched during the dry season and depleted during the rainy season. Xylem water δO18 levels drops to groundwater δO18 levels in early March when trees access groundwater for leafing out, however soil water does not reach this level until soil moisture increases in mid-June. The relationship between the δDH and δO18 concentrations of water extracted from soil and tree samples do not fall along the global meteoric water line. In order to explore whether this was a seasonally driven, we grouped samples into an "evaporated" group or a "meteoric" group based on the smaller residual to the respective lines. Although more soil samples were found along the m-line during the rainy season than tree samples or dry season soil samples, there was no significant difference in days since rain for any group This suggests that

  13. Effects of Supplements with Different Protein Contents on Nutritional Performance of Grazing Cattle During the Rainy Season. (United States)

    Figueiras, J F; Detmann, E; Franco, M O; Batista, E D; Reis, W L S; Paulino, M F; Valadares Filho, S C


    The objective of this study was to evaluate the effects of supplements with different crude protein (CP) contents on grazing cattle intake, digestibility, ruminal fermentation pattern, and nitrogen (N) metabolism characteristics during the rainy season. Five ruminal and abomasal cannulated Holstein×Zebu steers (296 kg body weight, BW) were used in a 5×5 Latin square design. The animals grazed five signal grass paddocks (0.34 ha). The five treatments evaluated were: Control (no supplement) and 1.0 g of supplement/kg BW with 0, 330, 660, and 1,000 g of CP/kg as-fed. The supplement was composed of starch, soybean meal, urea, and ammonium sulphate. There was a positive linear effect (p≤0.033) of the CP content in the supplements on the organic matter (OM), CP, and digested OM intakes. The provision of supplements did not increase (p≥0.158), on average, total and ruminal digestibilities of OM and CP. However, the increase in CP content in the supplements caused a positive linear effect (p≤0.018) on ruminal digestibilities of OM and CP. Additionally, a quadratic effect of the CP contents of the supplements were observed (p = 0.041) for the ruminal digestibility of neutral detergent fiber corrected for ash and protein, with the highest estimate obtained with the CP content of 670 g/kg. The supply of supplements increased (psupplements. The apparent N balance and relative N balance (g/g N intake) were not, on average, changed (p≥0.164) by the supplements supply. However, both showed a tendency of a linear increase (p≤0.099) with increasing supplement CP content. The supplements increased (p = 0.007) microbial N production in the rumen, which also changed linearly and positively (p = 0.016) with increasing supplement CP content. In conclusion, protein supplementation in grazing cattle during the rainy season, while stimulating voluntary forage intake, results in higher efficiency of N utilization when compared to energy supplementation. This is a possible

  14. Revised method to detect the onset and demise dates of the rainy season in the South American Monsoon areas (United States)

    Garcia, Sâmia R.; Calheiros, Alan J. P.; Kayano, Mary T.


    This paper proposes the detection of dates for the onset and demise of the rainy season (ONR and DER, respectively) for some areas within the South American monsoon system (SAMS) region using procedures based on indices which could be easily calculated and subjected to very simple criterion. Previously, the time series of the averaged antisymmetric outgoing longwave radiation ([AOLR]) in each region of interest was used by some authors to detect ONR and DER. This method is referred to as OLD. First, it was proposed in this paper to smooth this time series with the five-pentad running mean ([RM_AOLR]). This modified method is called NEW. Then, an additional modification was adopted by smoothing the [AOLR] with the three-pentad running mean but with the [AOLR] in the most recent pentad being replaced by its climatological value ([RM_AOLRCLI]). This method is called NEW_CLI. For these methods, the criterion was that the first pentad with negative (positive) [AOLR] (or [RM_AOLR] or [RM_AOLRCLI]) is the ONR (DER) date in the region of interest. All these methods were applied for the Central Amazon (CAM) and Western-Central Brazil (WCB) regions during the rainy seasons in the 2001-2013 period. The efficiency of these methods was analyzed using the precipitation estimated from the Tropical Rainfall Measuring Mission (TRMM) Multisatellite Precipitation Analysis. The spatial average of the TRMM ([TRMM]) time series with threshold values, which depends on the area and season, was used to determine the ONR and DER dates. In this case, the single method based on the threshold value is called RAIN, and the method which considers the persistence of dry or wet condition is referred to as NEW_RAIN. Comparisons between the methods were performed by calculating the root mean square error (RMSE) when ONR and DER dates obtained from a given method were considered as the true dates. The advantages and disadvantages of the methods were discussed here. It was previously noted that the

  15. Geothermal activity and hydrothermal mineral deposits at southern Lake Bogoria, Kenya Rift Valley: Impact of lake level changes (United States)

    Renaut, Robin W.; Owen, R. Bernhart; Ego, John K.


    Lake Bogoria, a saline alkaline closed-lake in a drainage basin of Neogene volcanic rocks in the central Kenya Rift, is fed partly by ∼200 hot alkaline springs located in three groups along its margins. Hot springs along the midwest shoreline (Loburu, Chemurkeu) and their travertine deposits have been studied, but little is known about the geothermal activity at southern Lake Bogoria. Observations, field measurements and analyses (geochemical and mineralogical) of the spring waters and deposits, spanning three decades, show that the southern spring waters are more saline, the hydrothermal alteration there is more intense, and that most hot spring deposits are siliceous. Geothermal activity at southern Lake Bogoria (Ng'wasis, Koibobei, Losaramat) includes littoral boiling springs and geysers, with fumaroles at slightly higher elevations. Modern spring deposits are ephemeral sodium carbonates, opal-A crusts and silica gels. Local fossil spring deposits include diatomaceous silica-cemented conglomerates that formed subaqueously when the lake was then dilute and higher than today, and outlying calcite tufa deposits. In contrast, mineral deposits around neighbouring fumarole vents and sites of hydrothermal alteration include clays (kaolinite), sulfate minerals (jarosite, alunite), and Fe-oxyhydroxides linked to rising acidic fluids. When lake level falls, the zone of acidity moves downwards and may overprint older alkaline spring deposits. In contrast, rising lake level leads to lake water dilution and vents in the lower parts of the acidic zone may become dilute alkaline springs. The new evidence at Lake Bogoria shows the potential for using the mineralogy of geothermal sediments to indicate former changes in lake level.

  16. Soil crusts to warm the planet (United States)

    Garcia-Pichel, Ferran; Couradeau, Estelle; Karaoz, Ulas; da Rocha Ulisses, Nunes; Lim Hsiao, Chiem; Northen, Trent; Brodie, Eoin


    Soil surface temperature, an important driver of terrestrial biogeochemical processes, depends strongly on soil albedo, which can be significantly modified by factors such as plant cover. In sparsely vegetated lands, the soil surface can also be colonized by photosynthetic microbes that build biocrust communities. We used concurrent physical, biochemical and microbiological analyses to show that mature biocrusts can increase surface soil temperature by as much as 10 °C through the accumulation of large quantities of a secondary metabolite, the microbial sunscreen scytonemin, produced by a group of late-successional cyanobacteria. Scytonemin accumulation decreases soil albedo significantly. Such localized warming had apparent and immediate consequences for the crust soil microbiome, inducing the replacement of thermosensitive bacterial species with more thermotolerant forms. These results reveal that not only vegetation but also microorganisms are a factor in modifying terrestrial albedo, potentially impacting biosphere feedbacks on past and future climate, and call for a direct assessment of such effects at larger scales. Based on estimates of the global biomass of cyanobacteria in soil biocrusts, one can easily calculate that there must currently exist about 15 million metric tons of scytonemin at work, warming soil surfaces worldwide

  17. A new crystalline phase in magnetar crusts

    CERN Document Server

    Bedaque, Paulo F; Ng, Nathan; Sen, Srimoyee


    We show that ions at the low densities and high magnetic fields relevant to the outer crust of magnetars form a novel crystalline phase where ions are strongly coupled along the magnetic field and loosely coupled in the transverse direction. The underlying cause is the anisotropic screening of the Coulomb force by electrons in the presence of a strongly quantizing magnetic field which leads to Friedel oscillations in the ion-ion potential. In particular, the Friedel oscillations are much longer-ranged in the direction of the magnetic field than is the case in the absence of magnetic fields, a factor that has been neglected in previous studies. These "Friedel crystals" have very anisotropic elastic moduli, with potentially interesting implications for the Quasi-periodic Oscillations seen in the X-ray flux of magnetars during their giant flares. We find the minimum energy configuration of ions taking into account these anisotropic effects and find that, depending on the density, temperature and magnetic field s...

  18. Living in Salt: The formation and development of extremophile habitats and biosignatures within salt crusts of the hyperarid Atacama Desert (United States)

    Finstad, K. M.; Amundson, R.


    It has become increasing apparent that salt-rich deposits are present on the Martian surface and that aqueous alteration has occurred sometime during the planet's past. In the hyperarid Atacama Desert in Chile, an important Earth-based analogue to Mars, microbial life has been discovered inhabiting halite (NaCl) surface crust deposits. Is it possible that similar salt deposits on Mars once harbored microbial life? If so, what adaptations were likely necessary for survival in such an environment and what biosignatures are expected to remain? Although this fascinating ecosystem in the Atacama Desert has been recognized, neither the physical processes of halite crust formation, nor the microorganisms residing within the salts have been extensively studied. To better understand the formation and geochemical dynamics of this unique habitat, we chose two sites within the Atacama Desert which exhibit both active crust formation as well as the presence of microbial communities: one site is on a dry Holocene age lake bed, while the other is of Pleistocene age. At each site soil profiles were excavated and total geochemical analyses were performed. Field observations clearly showed that the soils exhibited transitions of carbonate to sulfate to chloride salt deposition with decreasing depth, and that the thickness and mass of halite in the surficial crust was related to the age of the soil. Isotope profiles of carbon, nitrogen, and sulfur from these soils were also analyzed. Once exposed to the atmosphere, the halite crusts reside in a dynamic state of dissolution and erosion by wind and fog, and reformation due to fog and dew. In the crust nodules, microbial communities were sampled, in centimeter increments from the surface, for carbon, nitrogen, and sulfur isotope/concentration profiles. Our analyses help elucidate the physical and geochemical processes linked to the formation and evolution of these dynamic salt crusts, and the imprint of microbial life within them. A

  19. The stability of the crust of the dwarf planet Ceres (United States)

    Formisano, M.; Federico, C.; De Angelis, S.; De Sanctis, M. C.; Magni, G.


    In this article, we study the possibility that Ceres has, or had in the past, a crust heavier than a pure or muddy ice mantle, in principle gravitationally unstable. Such a structure is not unusual in the Solar system: Callisto is an example. In this work, we test how the composition (i.e. the volumetric quantity of ice) and the size of the crust can affect its survival during thermo-physical evolution after differentiation. We have considered two different configurations: the first characterized by a dehydrated silicate core and a mantle made of pure ice, the second with a hydrated silicate core and a muddy mantle (ice with silicate impurities). In both cases, the crust is composed of a mixture of ice and silicates. These structures are constrained by a recent measurement of the mean density by Park et al. The Rayleigh-Taylor instability, which operates in such an unstable structure, could reverse all or part of the crust. The whole unstable crust (or part of it) can interact chemically with the underlying mantle and what is currently observed could be a partially/totally new crust. Our results suggest that, in the case of a pure ice mantle, the primordial crust has not survived until today, with a stability timespan always less than 3 Gyr. Conversely, in the case of a muddy mantle, with some `favourable' conditions (low volumetric ice percentage in the crust and small crustal thickness), the primordial crust could be characterized by a stability timespan compatible with the lifetime of the Solar system.

  20. Relamination of mafic subducting crust throughout Earth's history (United States)

    Maunder, Ben; van Hunen, Jeroen; Magni, Valentina; Bouilhol, Pierre


    Earth has likely cooled by several hundred degrees over its history, which has probably affected subduction dynamics and associated magmatism. Today, the process of compositional buoyancy driven upwelling, and subsequent underplating, of subducted materials (commonly referred to as ;relamination;) is thought to play a role in the formation of continental crust. Given that Archean continental crust formation is best explained by the involvement of mafic material, we investigate the feasibility of mafic crust relamination under a wide range of conditions applicable to modern and early Earth subduction zones, to assess if such a process might have been viable in an early Earth setting. Our numerical parametric study illustrates that the hotter, thicker-crust conditions of the early Earth favour the upward relamination of mafic subducting crust. The amount of relaminating subducting crust is observed to vary significantly, with subduction convergence rate having the strongest control on the volume of relaminated material. Indeed, removal of the entire mafic crust from the subducting slab is possible for slow subduction (∼2 cm/yr) under Archean conditions. We also observe great variability in the depth at which this separation occurs (80-120 km), with events corresponding to shallower detachment being more voluminous, and that relaminating material has to remain metastably buoyant until this separation depth, which is supported by geological, geophysical and geodynamical observations. Furthermore, this relamination behaviour is commonly episodic with a typical repeat time of approximately 10 Myrs, similar to timescales of episodicity observed in the Archean rock record. We demonstrate that this relamination process can result in the heating of considerable quantities of mafic material (to temperatures in excess of 900 °C), which is then emplaced below the over-riding lithosphere. As such, our results have implications for Archean subduction zone magmatism, for

  1. Bathymetry of Lake Erie and Lake Saint Clair (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Bathymetry of Lake Erie and Lake Saint Clair has been compiled as a component of a NOAA project to rescue Great Lakes lake floor geological and geophysical data and...

  2. Collective Modes in the Superfluid Inner Crust of Neutron Stars

    CERN Document Server

    Urban, Michael


    The neutron-star inner crust is assumed to be superfluid at relevant temperatures. The contribution of neutron quasiparticles to thermodynamic and transport properties of the crust is therefore strongly suppressed by the pairing gap. Nevertheless, the neutron gas still has low-energy excitations, namely long-wavelength collective modes. We summarize different approaches to describe the collective modes in the crystalline phases of the inner crust and present an improved model for the description of the collective modes in the pasta phases within superfluid hydrodynamics.

  3. Researchers Reveal Ecological Roles of Biological Soil Crusts in Desert

    Institute of Scientific and Technical Information of China (English)


    @@ Biological soil crust is a complex organic integrity of cyanobacteria, green algae, lichens and mosses, fungi, and other bacteria. This is a common and widespread phenomenon in desert areas all over the world. Biologically,this kind of soil crust differs a lot from physical ones in terms of physical and chemical properties, and become important biological factors in vegetation succession. Despite its unassuming appearance, the crust plays a significant role in the desert ecosystem, involving the process of soil formation, stability and fertility,the prevention of soil erosion by water or wind, the increased possibility of vascular plants colonization, and the stabilization of sand dunes.

  4. Hawaiian submarine manganese-iron oxide crusts - A dating tool? (United States)

    Moore, J.G.; Clague, D.A.


    Black manganese-iron oxide crusts form on most exposed rock on the ocean floor. Such crusts are well developed on the steep lava slopes of the Hawaiian Ridge and have been sampled during dredging and submersible dives. The crusts also occur on fragments detached from bedrock by mass wasting, on submerged coral reefs, and on poorly lithified sedimentary rocks. The thickness of the crusts was measured on samples collected since 1965 on the Hawaiian Ridge from 140 dive or dredge localities. Fifty-nine (42%) of the sites were collected in 2001 by remotely operated vehicles (ROVs). The thinner crusts on many samples apparently result from post-depositional breakage, landsliding, and intermittent burial of outcrops by sediment. The maximum crust thickness was selected from each dredge or dive site to best represent crusts on the original rock surface at that site. The measurements show an irregular progressive thickening of the crusts toward the northwest-i.e., progressive thickening toward the older volcanic features with increasing distance from the Hawaiian hotspot. Comparison of the maximum crust thickness with radiometric ages of related subaerial features supports previous studies that indicate a crust-growth rate of about 2.5 mm/m.y. The thickness information not only allows a comparison of the relative exposure ages of two or more features offshore from different volcanoes, but also provides specific age estimates of volcanic and landslide deposits. The data indicate that some of the landslide blocks within the south Kona landslide are the oldest exposed rock on Mauna Loa, Kilauea, or Loihi volcanoes. Crusts on the floors of submarine canyons off Kohala and East Molokai volcanoes indicate that these canyons are no longer serving as channelways for downslope, sediment-laden currents. Mahukona volcano was approximately synchronous with Hilo Ridge, both being younger than Hana Ridge. The Nuuanu landslide is considerably older than the Wailau landslide. The Waianae

  5. Physiological Response of Local and Saanen x Local Cross Goats during the Late Rainy Season in North-eastern Brazil

    Directory of Open Access Journals (Sweden)

    Degli, P.


    Full Text Available In order to compare in vivo performance and environmental adaptation of two genetic types of goats raised in north-eastern Brazil, 20 females (10 local and 10 Saanen x local were used in this experiment. During the late rainy season the goats were monitored for the following parameters: body weight, body (BT and skin temperature (ST, respiratory (RR and heart rate (HR as well as the air temperature (AT and humidity (HU in the pens in the morning (MR and afternoon (AR. From May to June the crossbred goats showed a significant gain (P< 0.05; the live weight of F1 was superior to the local goats (P< 0.05 at the end of the experiment. The physiological response during the AR was significantly superior to MR (P< 0.05 for all parameters. The local goats achieved the highest values of BT and ST during the experiment. On average, the physiological rhythms (RR and HR were higher in crossbred than local goats. In conclusion, crossbred goats showed to be less at risk to environmental stress condition in north-eastern Brazil.

  6. Short range tracking of rainy clouds by multi-image flow processing of X-band radar data

    Directory of Open Access Journals (Sweden)

    Mesin Luca


    Full Text Available Abstract Two innovative algorithms for motion tracking and monitoring of rainy clouds from radar images are proposed. The methods are generalizations of classical optical flow techniques, including a production term (modelling formation, growth or depletion of clouds in the model to be fit to the data. Multiple images are processed and different smoothness constraints are introduced. When applied to simulated maps (including additive noise up to 10 dB of SNR showing formation and propagation of objects with different directions and velocities, the algorithms identified correctly the production and the flow, and were stable to noise when the number of images was sufficiently high (about 10. The average error was about 0.06 pixels (px per sampling interval (ΔT in identifying the modulus of the flow (velocities between 0.25 and 2 px/ΔT were simulated and about 1° in detecting its direction (varying between 0° and 90°. An example of application to X-band radar rainfall rate images detected during a stratiform rainfall is shown. Different directions of the flow were detected when investigating short (10 min or long time ranges (8 h, in line with the chaotic behaviour of the weather condition. The algorithms can be applied to investigate the local stability of meteorological conditions with potential future applications in nowcasting.


    Directory of Open Access Journals (Sweden)

    G. M. J. HASAN


    Full Text Available Climate, one of the major controlling factors for well-being of the inhabitants in the world, has been changing in accordance with the natural forcing and manmade activities. Bangladesh, the most densely populated countries in the world is under threat due to climate change caused by excessive use or abuse of ecology and natural resources. This study checks the rainfall patterns and their associated changes in the north-eastern part of Bangladesh mainly Sylhet city through statistical analysis of daily rainfall data during the period of 1957 - 2006. It has been observed that a good correlation exists between the monthly mean and daily maximum rainfall. A linear regression analysis of the data is found to be significant for all the months. Some key statistical parameters like the mean values of Coefficient of Variability (CV, Relative Variability (RV and Percentage Inter-annual Variability (PIV have been studied and found to be at variance. Monthly, yearly and seasonal variation of rainy days also analysed to check for any significant changes.

  8. Lake metabolism scales with lake morphometry and catchment conditions

    DEFF Research Database (Denmark)

    Stæhr, Peter A.; Baastrup-Spohr, Lars; Jensen, Kaj Sand


    We used a comparative data set for 25 lakes in Denmark sampled during summer to explore the influence of lake morphometry, catchment conditions, light availability and nutrient input on lake metabolism. We found that (1) gross primary production (GPP) and community respiration (R) decline with lake...... in lake morphometry and catchment conditions when comparing metabolic responses of lakes to human impacts....

  9. Regional three-dimensional seismic velocity model of the crust and uppermost mantle of northern California (United States)

    Thurber, C.; Zhang, H.; Brocher, T.; Langenheim, V.


    We present a three-dimensional (3D) tomographic model of the P wave velocity (Vp) structure of northern California. We employed a regional-scale double-difference tomography algorithm that incorporates a finite-difference travel time calculator and spatial smoothing constraints. Arrival times from earthquakes and travel times from controlled-source explosions, recorded at network and/or temporary stations, were inverted for Vp on a 3D grid with horizontal node spacing of 10 to 20 km and vertical node spacing of 3 to 8 km. Our model provides an unprecedented, comprehensive view of the regional-scale structure of northern California, putting many previously identified features into a broader regional context and improving the resolution of a number of them and revealing a number of new features, especially in the middle and lower crust, that have never before been reported. Examples of the former include the complex subducting Gorda slab, a steep, deeply penetrating fault beneath the Sacramento River Delta, crustal low-velocity zones beneath Geysers-Clear Lake and Long Valley, and the high-velocity ophiolite body underlying the Great Valley. Examples of the latter include mid-crustal low-velocity zones beneath Mount Shasta and north of Lake Tahoe. Copyright 2009 by the American Geophysical Union.

  10. Characteristics of Autumn Overcast and Rainy Weather in Zhoukou%周口秋季连阴雨天气气候特征

    Institute of Scientific and Technical Information of China (English)

    李辉; 董彬


    Based on the research methods and experiences both at home and abroad, the precipitation data in Zhoukou during 1961 -2011 was statistically analyzed with the NCEP reanalysis data and conventional weather map, the laws of autumn overcast and rainy weather were found out and the atmospheric circulation features of the autumn overcast and rainy weather were analyzed. As indicated by the results, the continuous rainy weather in autumn in Zhoukou City appeared with an average frequency of 1. 6 years, the continuous rainy weather for over seven days had a frequency of 0.7 year, and-the continuous rainy weather for over ten days showed a frequency of five years, both were the mosi in September. The autumn rainy weather appeared mostly in 1970s and 80s, two times a year; the continuous rainy weather for over 10 days appeared frequently since 1990s and 21st century, accounting for about 50%. The rainfall amount of autumn continuous rainy weather was generally about 30 -50 mm, then followed by ≥50 mm, the rainfall amount ≥100 mm mainly appeared in 1980s and since 21st century. The autumn continuous rainy weather was co-influenced by middle-high latitude westerly wind system and middle-high subtropical system, and the middle-high latitude systems were mainly divided into four types, including double-resistance low-voltage type, single-resistance low-voltage type, straight circulation type and two troughs and one ridge north type.%在借鉴国内外学者研究方法和经验的基础上,基于NCEP再分析资料和常规天气图等资料,对周口1961 ~2011年的降水资料进行统计对比分析,找出秋季连阴雨的规律,并对周口秋季连阴雨过程进行大气环流特征分析.结果表明,周口市秋季连阴雨平均1.6年一遇,7d以上的连阴雨平均约0.7年一遇,≥10 d的长连阴雨平均5年一遇,7d以上的连阴雨及≥10 d的长连阴雨均是9月份出现最多.秋季连阴雨20世纪70、80年代出现

  11. Nuclear superfluidity and cooling time of neutron-star crust

    Energy Technology Data Exchange (ETDEWEB)

    Monrozeau, C.; Margueron, J. [Institut de Physique Nucleaire, Universite Paris Sud, F-91406 Orsay CEDEX (France); Sandulescu, N. [Institut de Physique Nucleaire, Universite Paris Sud, F-91406 Orsay CEDEX (France); Institute of Physics and Nuclear Engineering, RO-76900 Bucharest (Romania)


    We analyse the effect of neutron superfluidity on the cooling time of inner crust matter in neutron stars, in the case of a rapid cooling of the core. The specific heat of the inner crust, which determines the thermal response of the crust, is calculated in the framework of HFB approach at finite temperature. The calculations are performed with two paring forces chosen to simulate the pairing properties of uniform neutron matter corresponding respectively to Gogny-BCS approximation and to many-body techniques including polarisation effects. Using a simple model for the heat transport across the inner crust, it is shown that the two pairing forces give very different values for the cooling time. (authors)

  12. Formation and development of salt crusts on soil surfaces

    KAUST Repository

    Dai, Sheng


    The salt concentration gradually increases at the soil free surface when the evaporation rate exceeds the diffusive counter transport. Eventually, salt precipitates and crystals form a porous sodium chloride crust with a porosity of 0.43 ± 0.14. After detaching from soils, the salt crust still experiences water condensation and salt deliquescence at the bottom, brine transport across the crust driven by the humidity gradient, and continued air-side precipitation. This transport mechanism allows salt crust migration away from the soil surface at a rate of 5 μm/h forming salt domes above soil surfaces. The surface characteristics of mineral substrates and the evaporation rate affect the morphology and the crystal size of precipitated salt. In particular, substrate hydrophobicity and low evaporation rate suppress salt spreading.

  13. A chemical and petrological model of the lunar crust (United States)

    Spudis, Paul D.; Davis, Philip A.


    Information is given on the composition and structure of the lunar crust. A lunar model is illustrated, indicating that it has essentially two layers, anorthositic mixed rocks overlaying a generally noritic crystalline basement. Implications relative to lunar evolution are discussed.

  14. Strange Stars: Can Their Crust Reach the Neutron Drip Density?

    Institute of Scientific and Technical Information of China (English)

    Hai Fu; Yong-Feng Huang


    The electrostatic potential of electrons near the surface of static strange stars at zero temperature is studied within the frame of the MIT bag model. We find that for QCD parameters within rather wide ranges, if the nuclear crust on the strange star is at a density leading to neutron drip, then the electrostatic potential will be insufficient to establish an outwardly directed electric field, which is crucial for the survival of such a crust. If a minimum gap width of 200 fm is brought in as a more stringent constraint, then our calculations will completely rule out the possibility of such crusts. Therefore, our results argue against the existence of neutron-drip crusts in nature.

  15. Breaking strain of neutron star crust and gravitational waves. (United States)

    Horowitz, C J; Kadau, Kai


    Mountains on rapidly rotating neutron stars efficiently radiate gravitational waves. The maximum possible size of these mountains depends on the breaking strain of the neutron star crust. With multimillion ion molecular dynamics simulations of Coulomb solids representing the crust, we show that the breaking strain of pure single crystals is very large and that impurities, defects, and grain boundaries only modestly reduce the breaking strain to around 0.1. Because of the collective behavior of the ions during failure found in our simulations, the neutron star crust is likely very strong and can support mountains large enough so that their gravitational wave radiation could limit the spin periods of some stars and might be detectable in large-scale interferometers. Furthermore, our microscopic modeling of neutron star crust material can help analyze mechanisms relevant in magnetar giant flares and microflares.

  16. [Crusted scabies induced by topical corticosteroids: A case report]. (United States)

    Bilan, P; Colin-Gorski, A-M; Chapelon, E; Sigal, M-L; Mahé, E


    The frequency of scabies is increasing in France. Crusted (or Norwegian) scabies is a very contagious form of scabies because of the huge number of mites in the skin. It is observed in patients suffering from immunodepression, motor or sensory deficiency, or mental retardation. The clinical presentation, except for the classic manifestation of scabies, is characterized by crusted lesions. Treatment is not easy and requires hospitalization. Topical corticosteroids are frequently used for children's dermatological diseases. Their long-term and inappropriate application in an infested scabies child can induce crusted scabies. We report on a case of an 8-year-old boy who developed crusted scabies induced by topical corticosteroid application. We discuss the therapeutic aspects of this severe form of scabies.

  17. Intensive Ammonia and Methane Oxidation in Organic Liquid Manure Crusts

    DEFF Research Database (Denmark)

    Nielsen, Daniel Aagren; Nielsen, Lars Peter; Schramm, Andreas

    of the crusts. PCR targeting the unique methane and ammonia monooxygenases were applied together with FISH to detect the presence of the two bacterial groups. Potential activity was assessed by short term slurry incubations of crust samples while monitoring NO2- production or CH4 consumption. Crusts were......Intensive agricultural practice leads to periodic accumulation of enormous amounts of liquid manure (slurry) from animal husbandry, and large quantities of environmentally hazardous ammonia and methane are emitted from the manure storages. Floating surface crusts have been suggested to harbour...... methane oxidizing bacteria (MOB) and are known to accumulate nitrite and nitrate, indicating the presence of ammonia oxidizers (AOB). We have surveyed six manure tanks with organic covers to investigate the prevalence of MOB and AOB and to link the potential activity with physical and chemical aspects...

  18. Russian Federation Snow Depth and Ice Crust Surveys (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Russian Federation Snow Depth and Ice Crust Surveys, dataset DSI-9808, contains routine snow surveys that run throughout the cold season every 10 days (every five...

  19. Sediment budget including the role of floodplains: the case of Lake Tana Basin (Ethiopia) (United States)

    Lemma, Hanibal; Admasu, Teshager; Dessie, Mekete; Fentie, Derbew; Poesen, Jean; Lanckriet, Sil; Adgo, Enyew; Nyssen, Jan


    Based on the collection of a large new dataset, we quantify the sediment 1) mobilized on the hillslopes surrounding Lake Tana (Ethiopia), 2) stored on the floodplains, 3) transported into the lake, 4) deposited in the lake and 5) delivered out of the lake so as to establish a sediment budget. In 2012 and 2013, suspended sediment concentration (SSC) and discharge measurements were made at 13 monitoring stations, including two lake outlets. 4635 SSC samples were collected and sediment rating curves that account for land cover conditions and rainfall seasonality were established for the 11 river stations, and mean monthly SSC was calculated for the outlets. Effects of the floodplain on rivers' sediment yield (SY) were investigated using the measurements at the upper and lower stations of Gilgel Abay, Gumara, Megech and Rib Rivers. SY from ungauged rivers was assessed using a model that includes catchment area and rainfall, whereas bedload and direct sediment input from lake shores were estimated. As a result, the gross annual SY from both gauged and ungauged rivers, bedload and lake shores was ca. 3.14 million tons, dominantly from Gilgel Abay and Gumara Rivers. The 0.48 million tons sedimentation in floodplains indicate that the floodplains serve as sediment sink. Moreover, annually about 1.09 million tons of sediment leaves the lake through the two outlets. Annual deposition in Lake Tana was about 1.56 million tons with a trapping efficiency of 60%. Furthermore, SSC and SY are generally higher at the beginning of the rainy season because soil in cultivated fields is bare and loose due to frequent ploughing and seedbed preparation. Later on in the season, increased crop and vegetation cover lead to a decrease in sediment supplies. Based on the established sediment budget and its calculated components, one can conclude that the expected lifetime of Lake Tana (20,396 years) is longer than what was anticipated in earlier studies.

  20. Impacts of the Nuclear Symmetry Energy on Neutron Star Crusts

    CERN Document Server

    Bao, Shishao


    Using the relativistic mean-field theory, we adopt two different methods, namely, the coexisting phase method and the self-consistent Thomas-Fermi approximation, to study the impacts of the nuclear symmetry energy on properties of neutron star crusts within a wide range of densities. It is found that the nuclear symmetry energy and its density slope play an important role in determining the pasta phases and the crust-core transition.

  1. Chemical composition of upper crust in eastern China

    Institute of Scientific and Technical Information of China (English)

    鄢明才; 迟清华; 顾铁新; 王春书


    In an area of 3. 3 ×106 km" within eastern China, 28 253 rock samples were collected systematically and combined into 2 718 composite samples which were analyzed by 15 reliable methods using national preliminary certified reference materials (CRMs) for data quality monitoring. The average chemical compositions of the exposed crust, the sedimentary cover and the exposed basement as well as the upper crust for 76 chemical elements in eastern China are given.

  2. Source of Lake Vostok Cations Constrained with Strontium Isotopes (United States)

    Lyons, William; Welch, Kathleen; Priscu, John; Tranter, Martyn; Royston-Bishop, George


    Lake Vostok is the largest sub-glacial lake in Antarctica. The primary source of our current knowledge regarding the geochemistry and biology of the lake comes from the analysis of refrozen lake water associated with ice core drilling. Several sources of dissolved ions and particulate matter to the lake have been proposed, including materials from the melted glacier ice, the weathering of underlying geological materials, hydrothermal activity and underlying, ancient evaporitic deposits. A sample of Lake Vostok Type 1 accretion ice has been analyzed for its 87Sr/86Sr signature as well as its major cation and anion and Sr concentrations. The strontium isotope ratio of 0.71655 and the Ca/Sr ratio in the sample strongly indicate that the major source of the Sr is from aluminosilicate minerals from the continental crust. These data imply that at least a portion of the other cations in the Type 1 ice also are derived from continental crustal materials and not hydrothermal activity, the melted glacier ice, or evaporitic sources.

  3. Interannual water level variations in Lake Izabal, Guatemala, Centroamerica, using radar altimetry and its relationship with oceanographic features (United States)

    Medina, C.; Gomez-Enri, J.; Alonso, J.; Villares, P.; Arias, M.; Catalan, M.; Labrador, I.


    It is well known that ocean-atmosphere dynamic affects the weather conditions over the continents and the ocean itself. The hydrologic cycle is driven by climatic parameters like precipitation, temperature, evaporation, winds and humidity. Hence, the river's water discharges and lake water level variations are impelled by climatic conditions also. Lake Izabal is the largest one in Guatemala; its main tributary is the Polochic River. Its level is related to the Polochic Rivers runoff and therefore to the precipitation/evaporation over its catchment area. The Lake Izabal water level fluctuations are driven by the annual cycle of rainy and dry seasons. In this study the ENVISAT RA-2 Geophysical Data Records orbits over the lake, coupled with in-situ measurements are used in order to determine and characterize the lake level fluctuations. The precipitation records over the lake's catchment area are also analyzed. In addition, some relationships of the lake level interannual variations with the climate indexes of Southern Oscillation Index SOI and the Tropical North Atlantic NATL were investigated. The main result is that the abrupt lake level rise in July 2006 is correlated to an abnormal precipitation in June 2006. Theoretically, this was forced by "La Nina" Southern Oscillation events during early 2006.

  4. Structure and composition of the continental crust in East China

    Institute of Scientific and Technical Information of China (English)

    高山; 骆庭川; 张本仁; 张宏飞; 韩吟文; 赵志丹; KERN; Hartmut


    Crustal structures of nine broad tectonic units in China, except the Tarim craton, are derived from 18 seismic refraction profiles including 12 geoscience transects. Abundances of 63 major, trace and rare earth elements in the upper crust in East China are estimated. The estimates are based on sampling of 11 451 individual rock samples over an area of 950 000 km~2, from which 905 large composite samples are prepared and analyzed by 13 methods. The middle, lower and total crust compositions of East China are also estimated from studies of exposed crustal cross sections and granulite xenoliths and by correlation of seismic data with lithologies. All the tectonic units except the Tarim craton and the Qinling orogen show a four-layered crustal structure, consisting of the upper, middle, upper lower, and lowermost crusts. P-wave velocities of the bulk lower crust and total crust are 6.8—7.0 and 6.4—6.5 km/s, respectively. They are slower by 0.2—0.4 km/s than the global averages. The bulk lower crust is su

  5. Volcanic Lake System at Aso Volcano, Japan: Fluctuations in the Supply of Volcanic Fluid from the Hydrothermal System beneath the Crater Lake (Invited) (United States)

    Terada, A.; Hashimoto, T.; Kagiyama, T.


    /s) and enthalpy (1,800-3,000 kJ/kg) for the fluid supplied to the lake. We assumed that the fluid is mixture of high-temperature steam (800 °C) and liquid water (100 °C), and assessed their mass fluxes. The liquid water flux shows a seasonal variation, lagging the rainy season by 2 months, suggesting that a proportion of the liquid water is groundwater. The pattern of fluctuations in the flux of high-temperature steam shows a relation with the amplitude of continuous volcanic tremor. We consider that heating of the hydrothermal system drives the tremor.

  6. [Response of fine root decomposition to simulated nitrogen deposition in Pleioblastus amarus plantation, rainy area of West China]. (United States)

    Tu, Li-Hua; Chen, Gang; Peng, Yong; Hu, Hong-Ling; Hu, Ting-Xing; Zhang, Jian


    As an important contributor to carbon (C) flux in the global C cycle, fine root litter decomposition in forests has the potential to be affected by the elevated nitrogen (N) deposition observed globally. From November 2007 to January 2013, a field experiment involving monthly simulated deposition of N in a Pleioblastus amarus plantation was conducted in the Rainy Area of West China. Four levels of nitrogen deposition were included as control (0 g N x m(-2) x a(-1)), low nitrogen (5 g N x m(-2) x a(-1)), medium nitrogen (15 g N x m(-2) x a(-1)) and high nitrogen (30 g N x m(-2) x a(-1)). After 3 years of simulated N deposition experiment (January 2011) , a two-year fine root decomposition experiment was conducted in the simulated N deposition plots using litterbag method, under monthly experimental N deposition. The decomposition rates of fine roots were fast first and then slow. Mass loss of fine roots in the first year of decomposition was up to 60%, and the change of the remaining mass was very slow in the second year. The time of 50% and 95% mass loss of fine roots was 1.20 and 5.17 years, respectively, under the conditions of no addition N input. In general, decomposition rates were underestimated using negative exponential model. Simulated N deposition significantly inhibited the decomposition of fine roots. The remaining mass in the high nitrogen treatment was 51.0% higher than that in the control, after two years of decomposition. Simulated N deposition increased C, P and K contents in the remaining mass of litter. Compared with the control, soil pH decreased significantly in the medium and high nitrogen treatments, soil organic C, total N, ammonium and nitrate contents and fine root biomass of P. amarus increased significantly in the high nitrogen treatment after simulated N deposition for 4. 5 years. Key words: nitrogen deposition; fine root decomposition; Pleioblastus amarus.

  7. Unusual past dry and wet rainy seasons over Southern Africa and South America from a climate perspective

    Directory of Open Access Journals (Sweden)

    Omar Bellprat


    Full Text Available Southern Africa and Southern South America have experienced recent extremes in dry and wet rainy seasons which have caused severe socio-economic damages. Selected past extreme events are here studied, to estimate how human activity has changed the risk of the occurrence of such events, by applying an event attribution approach (Stott et al., 2004comprising global climate models of Coupled Model Intercomparison Project 5 (CMIP5. Our assessment shows that models' representation of mean precipitation variability over Southern South America is not adequate to make a robust attribution statement about seasonal rainfall extremes in this region. Over Southern Africa, we show that unusually dry austral summers as occurred during 2002/2003 have become more likely, whereas unusually wet austral summers like that of 1999/2000 have become less likely due to anthropogenic climate change. There is some tentative evidence that the risk of extreme high 5-day precipitation totals (as observed in 1999/2000 have increased in the region. These results are consistent with CMIP5 models projecting a general drying trend over SAF during December–January–February (DJF but also an increase in atmospheric moisture availability to feed heavy rainfall events when they do occur. Bootstrapping the confidence intervals of the fraction of attributable risk has demonstrated estimates of attributable risk are very uncertain, if the events are very rare. The study highlights some of the challenges in making an event attribution study for precipitation using seasonal precipitation and extreme 5-day precipitation totals and considering natural drivers such as ENSO in coupled ocean–atmosphere models.

  8. Using Moving North Pacific Index to Improve Rainy Season Rainfall Forecast over the Yangtze River Basin by Analog Error Correction

    Institute of Scientific and Technical Information of China (English)


    A new analog error correction (AEC) scheme based on the moving North Pacifi c index (MNPI) is designed in this study. This scheme shows obvious improvement in the prediction skill of the operational coupled general circulation model (CGCM) of the National Climate Center of China for the rainy season rainfall (RSR) anomaly pattern correlation coeffi cient (ACC) over the mid-to-lower reaches of the Yangtze River (MLRYR). A comparative analysis indicates that the eff ectiveness of the new scheme using the MNPI is better than the system error correction scheme using the North Pacifi c index (NPI). A Euclidean distance-weighted mean rather than a traditional arithmetic mean, is applied to the integration of the analog year’s prediction error fi elds. By using the MNPI AEC scheme, independent sample hindcasts of RSR during the period 2003–2009 are then evaluated. The results show that the new scheme exhibited a higher forecast skill during 2003–2009, with an average ACC of 0.47;while the ACC for the NPI case was only 0.19. Furthermore, the forecast skill of the RSR over the MLRYR is examined. In the MNPI case, empirical orthogonal function (EOF) was used in the degree compression of the prediction error fi elds from the CGCM, whereas the AEC scheme was applied only to its fi rst several EOF components for which the accumulative explained variance accounted for 80%of the total variance. This further improved the ACC of the independent sample hindcasts to 0.55 during the 7-yr period.

  9. DNR 24K Lakes (United States)

    Minnesota Department of Natural Resources — Medium scale lake polygons derived from the National Wetlands Inventory (NWI) polygons and MnDOT Basemap lake delineations. Integrated with the DNR 24K Streams...

  10. Lake trout rehabilitation in Lake Ontario (United States)

    Elrod, Joseph H.; O'Gorman, Robert; Schneider, Clifford P.; Eckert, Thomas H.; Schaner, Ted; Bowlby, James N.; Schleen, Larry P.


    Attempts to maintain the native lake trout (Salvelinus namaycush) population in Lake Ontario by stocking fry failed and the species was extirpated by the 1950s. Hatchery fish stocked in the 1960s did not live to maturity because of sea lamprey (Petromyzon marinus) predation and incidental commercial harvest. Suppression of sea lampreys began with larvicide treatments of Lake Ontario tributaries in 1971 and was enhanced when the tributaries of Oneida Lake and Lake Erie were treated in the 1980s. Annual stocking of hatchery fish was resumed with the 1972 year class and peaked at about 1.8 million yearlings and 0.3 million fingerlings from the 1985–1990 year classes. Survival of stocked yearlings declined over 50% in the 1980 s and was negatively correlated with the abundance of lake trout > 550 mm long (r = −0.91, P < 0.01, n = 12). A slot length limit imposed by the State of New York for the 1988 fishing season reduced angler harvest. Angler harvest in Canadian waters was 3 times higher in eastern Lake Ontario than in western Lake Ontario. For the 1977–1984 year classes, mean annual survival rate of lake trout age 6 and older was 0.45 (range: 0.35–0.56). In U.S. waters during 1985–1992, the total number of lake trout harvested by anglers was about 2.4 times greater than that killed by sea lampreys. The number of unmarked lake trout < 250 mm long in trawl catches in 1978–1992 was not different from that expected due to loss of marks and failure to apply marks at the hatchery, and suggested that recruitment of naturally-produced fish was nil. However, many of the obstacles which may have impeded lake trout rehabilitation in Lake Ontario during the 1980s are slowly being removed, and there are signs of a general ecosystem recovery. Significant recruitment of naturally produced lake trout by the year 2000, one interim objective of the rehabilitation plan for the Lake, may be achieved.

  11. Lead isotopic evolution of Archean continental crust, Northern Tanzania (United States)

    Bellucci, J. J.; McDonough, W. F.; Rudnick, R. L.; Walker, R. J.


    The continental crust is stratified in composition; the upper crust is generally enriched in highly incompatible trace elements relative to the lower crust [1]. The Western Granulite section of the Mozambique Belt of Northern Tanzania yields Archean Nd model ages and has zircons with U-Pb ages of ~2.6 Ga [2,3], but was strongly re-worked during the Pan-African Orogeny, ca. 560 Ma [2,3,4]. Here we use time-integrated Pb isotopic modeling for lower and middle crustal xenoliths, as well as upper crustal granulites to determine the timing of, and degree of intra-crustal differentiation. The Pb isotopic compositions of most feldspars in the lower crustal samples, measured via LA-MC-ICPMS, fall on the trend defined by the Tanzanian Craton [5] and therefore, were most likely extracted from the mantle at a similar time, ca. 2.7 Ga. However, some xenoliths fall off this trend and show enrichment in 207Pb/204Pb, which we interpret as reflecting derivation from more heterogeneous mantle than that sampled in the Tanzanian Craton. In contrast to lower crustal xenoliths from the Tanzanian Craton [5], we see no single feldspar Pb-Pb isochrons, which indicates complete re-homogenization of the Pb isotopic composition of the feldspars in the lower crust of the Mozambique Belt during the Pan-African Orogeny, and heating to > 600°C [5]. Using time integrated Pb modeling, the upper crust of the Western Granulites is enriched in U by ˜ 2.5 relative to that of the lower crust, which must have taken place around the time of mantle extraction (ca. 2.7 Ga). In addition, these calculations are consistent with a Th/U ratio of ˜ 4 for the bulk lower crust and ˜ 3 for the bulk upper crust. The common Pb isotopic composition of a single middle crustal xenolith implies a Th/U of 20, but is unlikely to be generally representative of the middle crust. [1] Rudnick, R. L. and Gao, S. (2003). In the Crust, vol. 3, Treatise on Geochemistry:1-64. [2] Mansur, A. (2008) Masters Thesis, University of


    African Journals Online (AJOL)

    selected satellite lakes and Mara River in Lake Victoria basin, during wet and dry seasons in. 2002. Samples ... The wet season recorded higher biomass in all satellite lakes than during the dry season (t = 2.476, DF ..... communication. Urbana ...

  13. Effects of crust and cracks on simulated catchment discharge and soil loss

    NARCIS (Netherlands)

    Stolte, J.; Ritsema, C.J.; Roo, de A.P.J.


    Sealing, crusting and cracking of crusts of the soil surface has been observed in many parts of the world in areas with sandy, silty and loamy soils. Sealing and crust formation occurs under the influence of rain storm and drying weather. With prolonged drying, surface crusts might crack, leading to

  14. Effect of water activity on fracture and acoustic characteristics of a crust model

    NARCIS (Netherlands)

    Primo-Martín, C.; Sözer, N.; Hamer, R.J.; Vliet, T. van


    A crust model is described that is suited to study crispness of bread crusts as a function of steady state water activity. The study of crispness of this type of products as a function of water activity is complicated since the way a bread crust fractures does not depend on the crust only but also o

  15. Effect of water activity on fracture and acoustic characteristics of a crust model

    NARCIS (Netherlands)

    Primo-Martín, C.; Sözer, N.; Hamer, R.J.; Vliet, T. van


    A crust model is described that is suited to study crispness of bread crusts as a function of steady state water activity. The study of crispness of this type of products as a function of water activity is complicated since the way a bread crust fractures does not depend on the crust only but also

  16. Incidence of Bacterial Disease and Yield of Broccoli as Influenced by Different Rain Protectors and Varieties during the Rainy Season in Southern Thailand


    Karistsapol Nooprom; Quanchit Santipracha


    This study is mainly focused on evaluating the effects of different rain protectors and broccoli varieties to find out whether rain protector and variety is suitable or not for broccoli production during rainy season. Broccoli was experimented at Prince of Songkla University, Hat Yai, Songkhla, southern Thailand. Study revealed that broccoli growing under plastic sheet and green shade net had lower incidence of soft rot disease (1.62 and 3.75%, respectively) than those grown in open field (13...

  17. Carbon cycling of Lake Kivu (East Africa: net autotrophy in the epilimnion and emission of CO2 to the atmosphere sustained by geogenic inputs.

    Directory of Open Access Journals (Sweden)

    Alberto V Borges

    Full Text Available We report organic and inorganic carbon distributions and fluxes in a large (>2000 km2 oligotrophic, tropical lake (Lake Kivu, East Africa, acquired during four field surveys, that captured the seasonal variations (March 2007-mid rainy season, September 2007-late dry season, June 2008-early dry season, and April 2009-late rainy season. The partial pressure of CO2 (pCO2 in surface waters of the main basin of Lake Kivu showed modest spatial (coefficient of variation between 3% and 6%, and seasonal variations with an amplitude of 163 ppm (between 579±23 ppm on average in March 2007 and 742±28 ppm on average in September 2007. The most prominent spatial feature of the pCO2 distribution was the very high pCO2 values in Kabuno Bay (a small sub-basin with little connection to the main lake ranging between 11,213 ppm and 14,213 ppm (between 18 and 26 times higher than in the main basin. Surface waters of the main basin of Lake Kivu were a net source of CO2 to the atmosphere at an average rate of 10.8 mmol m(-2 d(-1, which is lower than the global average reported for freshwater, saline, and volcanic lakes. In Kabuno Bay, the CO2 emission to the atmosphere was on average 500.7 mmol m(-2 d(-1 (∼46 times higher than in the main basin. Based on whole-lake mass balance of dissolved inorganic carbon (DIC bulk concentrations and of its stable carbon isotope composition, we show that the epilimnion of Lake Kivu was net autotrophic. This is due to the modest river inputs of organic carbon owing to the small ratio of catchment area to lake surface area (2.15. The carbon budget implies that the CO2 emission to the atmosphere must be sustained by DIC inputs of geogenic origin from deep geothermal springs.

  18. The nature of orogenic crust in the central Andes (United States)

    Beck, Susan L.; Zandt, George


    The central Andes (16°-22°S) are part of an active continental margin mountain belt and the result of shortening of the weak western edge of South America between the strong lithospheres of the subducting Nazca plate and the underthrusting Brazilian shield. We have combined receiver function and surface wave dispersion results from the BANJO-SEDA project with other geophysical studies to characterize the nature of the continental crust and mantle lithospheric structure. The major results are as follows: (1) The crust supporting the high elevations is thick and has a felsic to intermediate bulk composition. (2) The relatively strong Brazilian lithosphere is underthrusting as far west (65.5°W) as the high elevations of the western part of the Eastern Cordillera (EC) but does not underthrust the entire Altiplano. (3) The subcrustal lithosphere is delaminating piecemeal under the Altiplano-EC boundary but is not completely removed beneath the central Altiplano. The Altiplano crust is characterized by a brittle upper crust decoupled from a very weak lower crust that is dominated by ductile deformation, leading to lower crustal flow and flat topography. In contrast, in the high-relief, inland-sloping regions of the EC and sub-Andean zone, the upper crust is still strongly coupled across the basal thrust of the fold-thrust belt to the underthrusting Brazilian Shield lithosphere. Subcrustal shortening between the Altiplano and Brazilian lithosphere appears to be accommodated by delamination near the Altiplano-EC boundary. Our study suggests that orogenic reworking may be an important part of the "felsification" of continental crust.

  19. Lithospheric cooling as a basin forming mechanism within accretionary crust. (United States)

    Holt, P. J.; Allen, M.; van Hunen, J.; Björnseth, H. M.


    Widely accepted basin forming mechanisms are limited to flexure of the lithosphere, lithospheric stretching, lithospheric cooling following rifting and, possibly, dynamic topography. In this work forward models have been used to investigate lithospheric growth due to cooling beneath accretionary crust, as a new basin forming mechanism. Accretionary crust is formed from collision of island arcs, accretionary complexes and fragments of reworked older crust at subduction zones, and therefore has thin lithosphere due to melting and increased convection. This is modeled using a 1D infinite half space cooling model similar to lithospheric cooling models for the oceans. The crustal composition and structure used in the models has been varied around average values of accretionary crust to represent the heterogeneity of accretionary crust. The initial mantle lithosphere thickness used in the model was 20 km. The model then allows the lithosphere to thicken as it cools and calculates the subsidence isostatically. The model produces sediment loaded basins of 2-7 km for the various crustal structures over 250 Myrs. Water-loaded tectonic subsidence curves from the forward models were compared to tectonic subsidence curves produced from backstripping wells from the Kufrah and Ghadames basins, located on the accretionary crust of North Africa. A good match between the subsidence curves for the forward model and backstripping is produced when the best estimates for the crustal structure, composition and the present day thickness of the lithosphere for North Africa are used as inputs for the forward model. This shows that lithospheric cooling provides a good method for producing large basins with prolonged subsidence in accretionary crust without the need for initial extension.

  20. Contrasting effects of microbiotic crusts on runoff in desert surfaces (United States)

    Kidron, Giora J.; Monger, H. Curtis; Vonshak, Ahuva; Conrod, William


    Microbiotic crusts (MCs) play an important role in surface hydrology by altering runoff yield. In order to study the crust's role on water redistribution, rainfall and runoff were measured during 1998-2000 at three sites within the northern Chihuahuan Desert, New Mexico, USA: the Sevilleta National Wildlife Refuge (SEV), the White Sands National Monument (WS), and the Jornada Experimental Range (JER). Whereas quartz and gypsum sand characterize the SEV and WS sites, respectively, both of which have high infiltration rates, silty alluvial deposits characterize the JER site. Runoff was measured in four pairs of 1.8-6.4 m 2 plots having MCs, one of which was scalped in each pair. No runoff was generated at WS, whether on the crusted or the scalped plots. Runoff was however generated at SEV and JER, being higher on the crusted plots at SEV and lower on the JER plots. The results were explained by the combined effect of (a) parent material and (b) the crust properties, such as species composition, microrelief (surface roughness) and exopolysaccharide (EPS) content (reflected in the ratio of carbohydrates to chlorophyll). Whereas the effective rainfall, the fines and the EPS content were found to explain runoff initiation, the effective rainfall and the crust microrelief were found to explain the amount of runoff at SEV and JER where runoff generation took place. The findings attest to the fundamental role of the parent material and the crust's species composition and properties on runoff and hence to the complex interactions and the variable effects that MCs have on dryland hydrology.

  1. Assessment of Concentration and Variations due to Seasonal Effect on the Presence of Heavy Metals in the Water of Upper Lake

    Directory of Open Access Journals (Sweden)

    Ranjana Talwar


    Full Text Available Water is the most precious gift of nature and is a valued natural resource for the existence of living beings. Management of this natural resource is thus of utmost importance. The present study was carried out to determine the presence of a few heavy metals viz, lead, chromium, copper and mercury in the various samples of Upper Lake, Bhopal. The samples were analyzed during both the pre-monsoon and the post-monsoon season. From the observations it was concluded that a general increase in the concentration was observed in the post monsoon season due to surface runoff coming into the lake water in the rainy season.

  2. Modelling of seasonal and long-term trends in lake salinity in southwestern Victoria, Australia. (United States)

    Yihdego, Yohannes; Webb, John


    In southwestern Victoria a large number of lakes are scattered across the volcanic plains; many have problems with increasing salinity. To identify the hydrologic components behind this problem, three lakes, Burrumbeet, Linlithgow and Buninjon, were selected for detailed water and salt budget modelling using monthly values of rainfall, evaporation, surface inflow and outflow, and groundwater inflow and outflow (using the new modified difference method developed in this study). On average, rainfall begins to exceed evaporation with the onset of winter rainfall in May, so lake levels rise and lake salinities decline. The modelled lakes have become more saline over the last decade, a time of drought with below average rainfall, and all eventually dried out, their salinities rising to very high levels as they shallowed. Lake Burrumbeet is generally much less saline than Lakes Linlithgow and Buninjon, because it has substantial groundwater outflow, probably due to leakage through one or more volcanic necks. This limits the amount of time the lake water is subject to evaporation, and also allows significant salt export. The other lakes do not leak. The modelling indicates that when the lakes dry out, salt is lost from the lake-beds, probably due to wind deflation of salt crusts and leakage into the underlying groundwater. The removal of salt during drying-out phases resets the salinity of the lakes, limiting their ability to become more saline with time. Drying-out phases may therefore be essential in preventing the increased salinisation of lakes and wetland environments across the volcanic plains. Copyright © 2012 Elsevier Ltd. All rights reserved.

  3. Artificial intelligence systems for rainy areas detection and convective cells' delineation for the south shore of Mediterranean Sea during day and nighttime using MSG satellite images (United States)

    Tebbi, Mohsene Abdelfettah; Haddad, Boualem


    The aim of this study is to investigate the potential of cloud classification by means of support vector machines using high resolution images from northern Algeria. The images were taken from the Spinning Enhanced Visible and Infrared Imager (SEVIRI) on board of the Meteosat Second Generation (MSG) satellite. An automatic system was developed to operate during both day and nighttime by following two steps of data processing. The first aims to detect rainy areas in cloud systems, whereas the second delineates convective cells from stratiform ones. A set of 12 spectral parameters was selected to extract information about cloud properties, which are different from day to night. The training and validation steps of this study were performed by in-situ rainfall measurement data, collected during the rainy season of years 2011 and 2012 via automatic rain gauge stations distributed in northern Algeria. Artificial neural networks (ANNs) and support vector machine (SVM) were explored, by combining spectral parameters derived from MSG images. Better performances were obtained by the SVM classifier, in terms of Critical Success Index and Probability of Detection for rainy areas detection (CSI = 0.81, POD = 91%), and also for convective/stratiform delineation (CSI = 0.55, POD = 74%).

  4. Examination of Libby, Montana, Fill Material for Background Levels of Amphibole from the Rainy Creek Complex Using Scanning Electron Microscopy and X-Ray Microanalysis (United States)

    Adams, David T.; Langer, William H.; Hoefen, Todd M.; Van Gosen, Bradley S.; Meeker, Gregory P.


    Natural background levels of Libby-type amphibole in the sediment of the Libby valley in Montana have not, up to this point, been determined. The purpose of this report is to provide the preliminary findings of a study designed by both the U.S. Geological Survey and the U.S. Environmental Protection Agency and performed by the U.S. Geological Survey. The study worked to constrain the natural background levels of fibrous amphiboles potentially derived from the nearby Rainy Creek Complex. The material selected for this study was sampled from three localities, two of which are active open-pit sand and gravel mines. Seventy samples were collected in total and examined using a scanning electron microscope equipped with an energy dispersive x-ray spectrometer. All samples contained varying amounts of feldspars, ilmenite, magnetite, quartz, clay minerals, pyroxene minerals, and non-fibrous amphiboles such as tremolite, actinolite, and magnesiohornblende. Of the 70 samples collected, only three had detectable levels of fibrous amphiboles compatible with those found in the rainy creek complex. The maximum concentration, identified here, of the amphiboles potentially from the Rainy Creek Complex is 0.083 percent by weight.

  5. Distribution of contagious and environmental mastitis agents isolated from milk samples collected from clinically health buffalo cows between brazilian dry and rainy seasons of the year

    Directory of Open Access Journals (Sweden)

    R.P. Maia


    Full Text Available The present study was performed to evaluate the microbiological characteristics of clinically health quarters submitted to milking and also to observe the distribution of contagious and environmental agents between brazilian dry and rainy seasons of the year. During nine months 734 quarters from 37 buffalo cows were submitted monthly to udder inspection, palpation and strip cup test before milking. 734 asseptic milk samples were inoculated in 10% ovine blood agar and in MacConkey agar media, then incubated for 72 hours at 37oC. Among the 580 isolated microrganisms, 182 (31,38% were recovered from samples collected during the rainy season and 398 (68,62% from the dry season. In the rainy period the most prevalent agents were: bacteria from the genus Corynebacterium sp (53,30%, Staphylococcus sp (19,78% and Rhodococcus equi (13,74%. In the dry period, the commonest ones were: Corynebacterium sp (44,97%, Staphylococcus sp (18,84% and Micrococcus sp (9,55%. The results demonstrated that the methods used to select health quarters in brazilian dairy buffalo farms allow the transmission of contagious bacteria during both seasons of the year, maintaining Ital.J.Anim.Sci. vol. 6, (Suppl. 2, 896-899, 2007 897 VIII World Buffalo Congress agents known to cause mainly subclinical inflammatory reactions that compromise cronically the physiology and production of the mammary gland.

  6. Physical, chemical and microbiological aspects during the dry and rainy seasons in a pond covered by macrophyte used in aquaculture water supply

    Directory of Open Access Journals (Sweden)

    Samuel Generoso Dias

    Full Text Available AIM: The water quality of a pond covered by macrophytes and used as a water supply for aquaculture was evaluated during the dry and rainy seasons; METHODS: Six points were established for water sampling, at water inflow and outflow. Samplings were carried out monthly between June 2008 and May 2009; RESULTS: Inflow points P1, P2 and P3 in the pond had higher nutrient concentrations and high trophic rates. Moreover, capybaras in the area caused sediment suspension and an increase in fecal coliforms. There was significant difference (p < 0.05 in the concentrations of nutrients in water between the dry and rainy seasons. The outflow of water caused by rain carried the material around the pond directly into the water; CONCLUSIONS: The system studied was influenced by rain and lack of adequate management of the surrounding area. Water quality was deteriorated by increase in nutrient concentrations, fecal coliforms and reduction of dissolved oxygen in the water during the rainy season. This was due to allochthonous material from the area surrounding the pond that affected negatively the supply system.

  7. Natural events of anoxia and low respiration index in oligotrophic lakes of the Atlantic Tropical Forest (United States)

    Marotta, H.; Fontes, M. L. S.; Petrucio, M. M.


    Hypoxia is a well-recognized condition reducing biodiversity and increasing greenhouse gas emissions in aquatic ecosystems, especially under warmer temperatures of tropical waters. Anoxia is a natural event commonly intensified by human-induced organic inputs in inland waters. Here, we assessed the partial pressure of O2 (pO2) and CO2 (pCO2), and the ratio between them (represented by the respiration index, RI) in two oligotrophic lakes of the Atlantic Tropical Forest, encompassing dry and rainy seasons over 19 months. We formulated the hypothesis that thermal stratification events could be coupled to natural hypoxia in deep waters of both lakes. Our results indicated a persistence of CO2 emissions from these tropical lakes to the atmosphere, on average ± standard error (SE) of 17.4 mg C m-2 h-1 probably subsided by terrestrial C inputs from the forest. Additionally, the thermal stratification during the end of the dry season and the rainy summer was coupled to anoxic events and very low RI in deep waters, and to significantly higher pO2 and RI at the surface (about 20 000 μatm and 1.0, respectively). In contrast, the water mixing during dry seasons at the beginning of the winter was related to a strong destratification in pO2, pCO2 and RI in surface and deep waters, without reaching any anoxic conditions throughout the water column. These findings confirm our hypothesis, suggesting that lakes of the Atlantic Tropical Forest could be dynamic, but especially sensitive to organic inputs. Natural anoxic events indicate that tropical oligotrophic lakes might be highly influenced by human land uses, which increase organic discharges into the watershed.

  8. Eutrophication potential of lakes: an integrated analysis of trophic state, morphometry, land occupation, and land use

    Directory of Open Access Journals (Sweden)

    RF Silvino

    Full Text Available AbstractDespite being inside a protected area, Lake Sumidouro has been impacted by the anthropogenic occupation of the surrounding area since the 1970’s, compromising the ecological integrity of the lake and the sustainable use of natural resources. This study examined the current trophic classification of the lake and developed methods for improving it through an integrated analysis of morphometric and limnological parameters, land use and land occupation in the watershed, and eutrophication potential. Data for the limnological parameters, land use and land occupation, and morphometric characteristics of Lake Sumidouro were collected in the rainy and dry seasons of 2009 and 2010. Depending on the trophic classification system used, Lake Sumidouro is classified as oligotrophic to hypereutrophic. In our study, the highest concentration of nutrients occurred in the rainy season, indicating that high nutrient inputs played an important role during this period. Areas of anthropogenic occupation comprised approximately 62.9% of the total area of the watershed, with pasture and urban settlement as the main types of land use. The influent total phosphorus load was estimated to be 15,824.3 kg/year. To maintain mesotrophic conditions, this load must be reduced by 29.4%. By comparing the isolated use of trophic state indices, this study demonstrated that comparing the trophic state classification with morphometric analyses, land use and land occupation types in the watershed, and potential phosphorus load provided better information to guide management actions for restoration and conservation. Furthermore, this approach also allowed for evaluating the vulnerability of the environment to the eutrophication process.

  9. Os and U-Th isotope signatures of arc magmatism near Mount Mazama, Crater Lake, Oregon (United States)

    Ankney, Meagan E.; Shirey, Steven B.; Hart, Garret L.; Bacon, Charles R.; Johnson, Clark M.


    Interaction of mantle melts with the continental crust can have significant effects on the composition of the resulting melts as well as on the crust itself, and tracing this interaction is key to our understanding of arc magmatism. Lava flows and pyroclastic deposits erupted from ∼50 to 7.7 ka at Mt. Mazama (Crater Lake, Oregon) were analyzed for their Re/Os and U-Th isotopic compositions. Mafic lavas from monogenetic vents around Mt. Mazama that erupted during the buildup to its climactic eruption have lower 187Os/188Os ratios (0.1394 to 0.1956) and high 230Th excess ((230Th/238U)0 of 1.180 to 1.302), whereas dacites and rhyodacites tend to have higher 187Os/188Os ratios (0.2292 to 0.2788) and significant 238U excess ((230Th/238U)0 of 0.975 to 0.989). The less radiogenic Os isotope compositions of the mafic lavas can be modeled by assimilation of young (∼2.5 to 7 Ma), mafic lower crust that was modified during regional extension, whereas the more radiogenic Os isotope compositions of the dacites and rhyodacites can be attributed to assimilation of older (∼10 to 16 Ma), mid to upper crust that acquired its composition during an earlier period of Cascade magmatism. Production of Th excesses in the lower crust requires very young garnet formation accompanying dehydration melting in the lower crust at less than a few 100 ka by heat from recent basaltic magma injection. The results from this study suggest that the combination of Os and Th isotopes may be used to provide insights into the timescales of evolution of the continental crust in arc settings, as well as the influence of the crust on erupted magmas, and suggest a link between the age and composition of the lower and upper crust to regional tectonic extension and/or earlier Cascade magmatism.

  10. Changes in lakes water volume and runoff over ungauged Sahelian watersheds (United States)

    Gal, L.; Grippa, M.; Hiernaux, P.; Peugeot, C.; Mougin, E.; Kergoat, L.


    A large part of the Sahel consists of endorheic hydrological systems, where reservoirs and lakes capture surface runoff during the rainy season, making water available during the dry season. Monitoring and understanding the dynamics of these lakes and their relationships to the ecohydrological evolution of the region is important to assess past, present and future changes of water resources in the Sahel. Yet, most of Sahelian watersheds are still ungauged or poorly gauged, which hinders the assessment of the water flows feeding the lakes and the overall runoff over their watershed. In this paper, a methodology is developed to estimate water inflow to lakes for ungauged watersheds. It is tested for the Agoufou lake in the Gourma region in Mali, for which in situ water height measurements and surface areas estimations by remote sensing are simultaneously available. A Height-Volume-Area (HVA) model is developed to relate water volume to water height and lake surface area. This model is combined to daily evaporation and precipitation to estimate water inflow to the lake, which approximates runoff over the whole watershed. The ratio between annual water inflow and precipitation increases over the last sixty years as a result of a significant increase in runoff coefficient over the Agoufou watershed. The method is then extended to derive water inflow to three other Sahelian lakes in Mauritania and Niger. No in situ measurements are available and lake surface areas estimation by remote sensing is the only source of information. Dry season surface area changes and estimated evaporation are used to select a suited VA relationship for each case. It is found that the ratio between annual water inflow and precipitation has also increased in the last 60 years over these watersheds, although trends at the Mauritanian site are not statistically significant. The remote sensing approach developed in this study can be easily applied to recent sensors such as Sentinel-2 or Landsat-8

  11. Phytoplankton variability in Lake Fraijanes, Costa Rica, in response to local weather variation

    Directory of Open Access Journals (Sweden)

    Gerardo Umaña-Villalobos


    Full Text Available Phytoplankton species show a variety in morphology which is the result of adaptations to pelagic life including responses to fluctuations in water column dynamics driven by weather conditions. This has been reported in the oceans and in Northern temperate lakes. In order to observe whether tropical freshwater phytoplankton responds to seasonal variation in weather, the weekly variation in temperature of the water column and phytoplankton composition was studied in Lake Fraijanes, Costa Rica, a shallow (6.2m lake at 1 640m above sea level. A chain of data loggers for temperature was placed in the deepest point in the lake to register temperature every hour at four different depths, and phytoplankton samples were retrieved every week for a year. Additional monthly samples for nutrients were taken at two depths. Notwithstanding its shallowness, the lake developed a thermal gradient which kept the water column stratified for several months during dry season. Whole lake overturns occurred during cold spells with intense precipitation. Phytoplankton changed throughout the year mainly through a shift in dominant taxa. From September to February the lake was frequently mixed by rain storms and windy weather. At this time, phytoplankton was dominated by Chlorococcal green algae. From March to June, the lake was stratified and warmer. Phytoplankton became dominated by Cyanobateria, mainly colonial Chroococcales. The rainy season started again in May 2009. During June and July the lake started to mix intermittently during rain events and phytoplankton showed a brief increase in the contribution of Chlorococcales. These changes fitted well to a general model of phytoplankton succession based on functional groups identified according to their morphology and adaptations.

  12. LITHOPROBE: a scientific update-new images of the continental crust (United States)

    Clowes, Ron M.


    Seismic line run across the continental margin northeast of Newfoundland help determine the nature of extensional tectonics and associated sedimentary basin evolution on the rifted margin. The GLIMPCE Transect has enabled a glimpse of the mid-continent crust by recording marine reflection data in the Great Lakes. The sections from Lake Superior reveal — 10 km of sediments overlying a 20 km thick sequence of strongly reflective volcanics and inter-flow sediments, perhaps representing the greatest vertical extent of intra-continental rift deposits on Earth.The original Archean/Early Proterozoic crust is greatly thinned beneath the rift basin. In the Lake Huron/Georgian Bay profile, the Grenville front is imaged as the westernmost reflection of a spectacular 70 km wide band of southeast-dipping reflections that clearly truncates prominent sub-horizontal crustal reflections of the Superior granite-rhyolite terrane. The Kapuskasing Structure Zone is a sequence of lower crustal rocks that have been thrust upward along the Ivanhoe Lake cataclastic zone and are now exposed at the surface. As part of the Kapuskasing Transect, 340 km of regional deep reflection data and 20 km of " high resolution" data (20 m station spacing, 20 m source interval and a higher sweep range) over the cataclastic zone were recorded in 1987-1988. The Abitibi sub-province of Ontario and Quebec contains mineralized belts for which it is famous. As a preliminary program for the Abitibi-Grenville Transect, 130 km of regional and 65 km of high-resolution Seismic profiles also were recorded in 1987-1988. These were centred over major fault zones with which mineralization is related. Data quality is excellent and the data are in the process of being interpreted.

  13. Two-Dimensional Porosity of Crusted Silty Soils: Indicators of Soil Quality in Semiarid Rangelands?



    Little is known about the morphological characteristics of pores in soil crusts. The objective was to characterize the 2D-porosity (amount, shape, size and area of pores) of soil crusts to ascertain their potential as indicators of soil quality for natural crusted soils. 2D-porosity was described in thin sections and measured by image analysis of polished resin-impregnated soil blocks. Physical soil crust and incipient biological soil crusts appear to be the lowest-quality soil...

  14. Dynamics of Pre-3 Ga Crust-Mantle Evolution (United States)

    Patchett, P. J.; Chase, C. G.; Vervoort, J. D.


    During 3.0 to 2.7 Ga, the Earth's crust underwent a non-uniformitarian change from a pre-3.0 Ga environment where long-term preservation of cratons was rare and difficult, to post-2.7 Ga conditions where cratons were established and new continental crust generation took place largely at craton margins. Many models view the Earth's surface during pre-3 Ga time as broadly equivalent to the post 2.7 Ga regime. Any such uniformitarian or gradual evolution cannot explain the conundrum that only a tiny amount of pre-3 Ga crust is preserved today coupled with the fact that very little pre-3 Ga crust was incorporated into the large amount of new craton that came into existence during 3.0-2.7 Ga. If large volumes of pre-3 Ga continental crust existed, it disappeared either just prior to 3 Ga, or during 3.0-2.7 Ga. To explain sudden appearance of surviving but dominantly juvenile continental crust in a model where continents were large prior to 3 Ga, it would be necessary either that pre-3 Ga continent was recycled into the mantle at sites systematically different from those where new 3.0-2.7 Ga crust was made, or that widespread continent destruction preceded the 3.0-2.7 Ga crustal genesis. From expected mantle overturn in response to the heat budget, it is likely that most pre-3 Ga crust was both more mafic and shorter-lived than after 3 Ga. Although Nd and Hf ratios for pre-3 Ga rocks are uncertain due to polymetamorphism, it appears that depleted upper mantle was widespread by 2.7 Ga, even pre-3 Ga. Depletion may have been largely achieved by formation, subduction and storage of mafic crust for periods of 200-500 m.y. The rapid change to large surviving continents during 3.0-2.7 Ga was due to declining mantle overturn, and particularly to development of the ability to maintain subduction in one zone of the earth's surface for the time needed to allow evolution to felsic igneous rock compositions. In as much as storage of subducted slabs is probably occurring today, and

  15. Linking biological soil crust diversity to ecological functions (United States)

    Glaser, Karin; Borchhardt, Nadine; Schulz, Karoline; Mikhailyuk, Tatiana; Baumann, Karen; Leinweber, Peter; Ulf, Karsten


    Biological soil crusts (BSCs) are an association of different microorganisms and soil particles in the top millimeters of the soil. They are formed by algae, cyanobacteria, microfungi, bacteria, bryophytes and lichens in various compositions. Our aim was to determine and compare the biodiversity of all occurring organisms in biogeographically different habitats, ranging from polar (both Arctic and Antarctic), subpolar (Scandinavia), temperate (Germany) to dry regions (Chile). The combination of microscopy and molecular techniques (next-generation sequencing) revealed highly diverse crust communities, whose composition clustered by region and correlates with habitat characteristics such as water content. The BSC biodiversity was then linked to the ecological function of the crusts. The functional role of the BSCs in the biogeochemical cycles of carbon, nitrogen and phosphorous is evaluated using an array of state of the art soil chemistry methods including Py-FIMS (pyrolysis field ionization mass spectrometry) and XANES (x-ray absorbance near edge structure). Total P as well as P fractions were quantified in all BSCs, adjacent soil underneath and comparable nearby soil of BSC-free areas revealing a remarkable accumulation of total phosphorous and a distinct pattern of P fractions in the crust. Further, we observed an indication of a different P-speciation composition in the crust compared with BSC-free soil. The data allow answering the question whether BSCs act as sink or source for these compounds, and how biodiversity controls the biogeochemical function of BSCs.

  16. Measurement of129I in ferromanganese crust with AMS

    Institute of Scientific and Technical Information of China (English)

    JI Lihong; LIU Guangshan; CHEN Zhigang; HUANG Yipu; XING Na; JIANG Shan; HE Ming


    In the present study, the analytical method for129iodine (129I) in ferromanganese crusts is developed and 129iodine/127iodine (129I/127I) ratio in ferromanganese crusts is measured by the accelerator mass spectrometry (AMS). The developed method is applied to analyze129I/127I ratio in two ferromanganese crusts MP5D44 and CXD08-1 collected from the Mid-Pacific Ocean. The results show that129I/127I ratio in MP5D44 and CXD08-1 crusts varies from 7×10–14 to 1.27×10–12, with the lowest value falling on the detection limit level of AMS reported by previous literatures. For the depth distribution of129I/127I, it is found that both MP5D44 and CXD08-1 crusts have two growth generations, and the129I/127I profiles in two generations all displayed an approximate exponential decay. According to the129I/127I ratio, the generate age of bottom layer of MP5D44 and CXD08-1 was estimated to be 54.77 and 69.69 Ma, respectively.

  17. Microenvironments and microscale productivity of cyanobacterial desert crusts (United States)

    Garcia-Pichel, F.; Belnap, Jayne


    We used microsensors to characterize physicochemical microenvironments and photosynthesis occurring immediately after water saturation in two desert soil crusts from southeastern Utah, which were formed by the cyanobacteria Microcoleus vaginatus Gomont, Nostoc spp., and Scytonema sp. The light fields within the crusts presented steep vertical gradients in magnitude and spectral composition. Near-surface light-trapping zones were formed due to the scattering nature of the sand particles, but strong light attenuation resulted in euphotic zones only ca. 1 mm deep, which were progressively enriched in longer wavelengths with depth. Rates of gross photosynthesis (3.4a??9.4 mmol O2A?ma??2A?ha??1) and dark respiration (0.81a??3.1 mmol Oa??2A?ma??2A?ha??1) occurring within 1 to several mm from the surface were high enough to drive the formation of marked oxygen microenvironments that ranged from oxygen supersaturation to anoxia. The photosynthetic activity also resulted in localized pH values in excess of 10, 2a??3 units above the soil pH. Differences in metabolic parameters and community structure between two types of crusts were consistent with a successional pattern, which could be partially explained on the basis of the microenvironments. We discuss the significance of high metabolic rates and the formation of microenvironments for the ecology of desert crusts, as well as the advantages and limitations of microsensor-based methods for crust investigation.

  18. Evolution of the earth's crust: Evidence from comparative planetology (United States)

    Lowman, P. D., Jr.


    Geochemical data and orbital photography from Apollo, Mariner, and Venera missions were combined with terrestrial geologic evidence to study the problem of why the earth has two contrasting types of crust (oceanic and continental). The following outline of terrestrial crustal evolution is proposed. A global crust of intermediate to acidic composition, high in aluminum, was formed by igneous processes early in the earth's history; portions survive in some shield areas as granitic and anorthositic gneisses. This crust was fractured by major impacts and tectonic processes, followed by basaltic eruptions analogous to the lunar maria and the smooth plains of the north hemisphere of Mars. Seafloor spreading and subduction ensued, during which portions of the early continental crust and sediments derived therefrom were thrust under the remaining continental crust. The process is exemplified today in regions such as the Andes/Peru-Chile trench system. Underplating may have been roughly concentric, and the higher radioactive element content of the underplated sialic material could thus eventually cause concentric zones of regional metamorphism and magmatism.

  19. Controls on the chemical composition of saline surface crusts and emitted dust from a wet playa in the Mojave Desert (USA) (United States)

    Goldstein, Harland L.; Breit, George N.; Reynolds, Richard L.


    Saline-surface crusts and their compositions at ephemeral, dry, and drying lakes are important products of arid-land processes. Detailed understanding is lacking, however, about interactions among locally variable hydrogeologic conditions, compositional control of groundwater on vadose zone and surface salts, and dust composition. Chemical and physical data from groundwater, sediments, and salts reveal compositional controls on saline-surface crusts across a wet playa, Mojave Desert, with bearing on similar settings elsewhere. The compositions of chemically and isotopically distinctive shallow (elements in the vadose zone diminishes the concentrations of potentially toxic elements in surface salts, but creates a reservoir of these elements that may be brought to the surface during wetter conditions or by human disturbance. Selective wind-erosion loss of sulfate salts was identified by the compositional contrast between surface salt crusts and underlying groundwater. At the sub-basin scale, compositional links exist among groundwater, salt crusts, and dust from wet playas. Across the study basin, however, lateral variations in groundwater and solid-salt compositions are produced by hydrogeologic heterogeneity.

  20. Anisotropic crystal structure of magnetized neutron star crust (United States)

    Baiko, D. A.; Kozhberov, A. A.


    Although crystallized neutron star crust is responsible for many fascinating observational phenomena, its actual microscopic structure in tremendous gravitational and magnetic fields is not understood. Here we show that in a non-uniform magnetic field, three-dimensional ionic Coulomb crystals comprising the crust may stretch or shrink while their electrostatic pressure becomes anisotropic. The pressure depends non-linearly on the magnitude of the stretch, so that a continuous magnetic field evolution may result in an abrupt crystal elongation or contraction. This may provide a trigger for magnetar activity. A phonon mode instability is revealed, which sets the limits of magnetic field variation beyond which the crystal is destroyed. These limits sometimes correspond to surprisingly large deformations. It is not known what happens to crust matter subject to a pressure anisotropy exceeding these limits. We hypothesize that the ion system then possesses a long-range order only in one or two dimensions, that is becomes a liquid crystal.

  1. Vortex pinning and dynamics in the neutron star crust

    CERN Document Server

    Wlazłowski, Gabriel; Magierski, Piotr; Bulgac, Aurel; Forbes, Michael McNeil


    The nature of the interaction between superfluid vortices and the neutron star crust, conjectured by Anderson and Itoh in 1975 to be at the heart vortex creep and the cause of glitches, has been a longstanding question in astrophysics. Previous estimates of the vortex-"nucleus" interaction have been error-prone, being either phenomenological or derived from tiny differences of large energies of stationary configurations. Using a qualitatively new approach, we follow the dynamics as superfluid vortices move in response to the presence of "nuclei" (nuclear defects in the crust). The resulting motion is perpendicular to the force, similar to the motion of a spinning top when pushed. We show that nuclei repel vortices in the neutron star crust, leading thus to interstitial vortex pinning, and characterize the force as a function of the vortex-nucleus separation.

  2. Magnetic field evolution in magnetar crusts through three dimensional simulations

    CERN Document Server

    Gourgouliatos, Konstantinos N; Hollerbach, Rainer


    Current models of magnetars require extremely strong magnetic fields to explain their observed quiescent and bursting emission, implying that the field strength within the star's outer crust is orders of magnitude larger than the dipole component inferred from spin-down measurements. This presents a serious challenge to theories of magnetic field generation in a proto-neutron star. Here, we present detailed modelling of the evolution of the magnetic field in the crust of a neutron star through 3-D simulations. We find that, in the plausible scenario of equipartition of energy between global-scale poloidal and toroidal magnetic components, magnetic instabilities transfer energy to non-axisymmetric, kilometre-sized magnetic features, in which the local field strength can greatly exceed that of the global-scale field. These intense small-scale magnetic features can induce high energy bursts through local crust yielding, and the localised enhancement of Ohmic heating can power the star's persistent emission. Thus...

  3. Neutrino-pair bremsstrahlung in a neutron star crust

    CERN Document Server

    Ofengeim, D D; Yakovlev, D G


    Based on the formalism by Kaminker et al. (Astron. Astrophys. 343 (1999) 1009) we derive an analytic approximation for neutrino-pair bremsstrahlung emissivity due to scattering of electrons by atomic nuclei in the neutron star crust of any realistic composition. The emissivity is expressed through generalized Coulomb logarithm which we fit by introducing an effective potential of electron-nucleus scattering. In addition, we study the conditions at which the neutrino bremsstrahlung in the crust is affected by strong magnetic fields. The results can be applied for modelling of many phenomena in neutron stars, such as thermal relaxation in young isolated neutron stars and in accreting neutron stars with overheated crust in soft X-ray transients.

  4. Sulfur and metal fertilization of the lower continental crust (United States)

    Locmelis, Marek; Fiorentini, Marco L.; Rushmer, Tracy; Arevalo, Ricardo; Adam, John; Denyszyn, Steven W.


    Mantle-derived melts and metasomatic fluids are considered to be important in the transport and distribution of trace elements in the subcontinental lithospheric mantle. However, the mechanisms that facilitate sulfur and metal transfer from the upper mantle into the lower continental crust are poorly constrained. This study addresses this knowledge gap by examining a series of sulfide- and hydrous mineral-rich alkaline mafic-ultramafic pipes that intruded the lower continental crust of the Ivrea-Verbano Zone in the Italian Western Alps. The pipes are relatively small (tectonic architecture of any given terrain, metals and volatiles stored in the lower continental crust may become available as sources for subsequent ore-forming processes, thus enhancing the prospectivity of continental block margins for a wide range of mineral systems.

  5. Light dark matter scattering in outer neutron star crusts

    CERN Document Server

    Cermeño, Marina; Silk, Joseph


    We calculate for the first time the phonon excitation rate in the outer crust of a neutron star due to scattering from light dark matter (LDM) particles gravitationally boosted into the star. We consider dark matter particles in the sub-GeV mass range scattering off a periodic array of nuclei through an effective scalar-vector interaction with nucleons. We find that LDM effects cause a modification of the net number of phonons in the lattice as compared to the standard thermal result. In addition, we estimate the contribution of LDM to the ion-ion thermal conductivity in the outer crust and find that it can be significantly enhanced at large densities. Our results imply that for magnetized neutron stars the LDM-enhanced global conductivity in the outer crust will tend to reduce the anisotropic heat conduction between perpendicular and parallel directions to the magnetic field.

  6. Rapid rotational crust-core relaxation in magnetars

    CERN Document Server

    Sedrakian, Armen


    If a magnetar interior $B$-field exceeds $10^{15}$ G it will unpair the proton superconductor in the star's core by inducing diamagnetic currents which destroy the Cooper pair coherence. Then, the $P$-wave neutron superfluid in these non-superconducting regions will couple to the stellar plasma by scattering of protons off the quasiparticles confined in the cores of neutron vortices via the strong (nuclear) force. The dynamical time-scales associated with this interaction span from several minutes at the crust-core interface to a few seconds in the deep core. We show that (a) the rapid crust-core coupling is incompatible with oscillation models of magnetars which decouple completely the core superfluid from the crust and (b) magnetar precession is damped by the coupling of normal fluids to the superfluid core and, if observed, needs to be forced or continuously excited by seismic activity.

  7. Light dark matter scattering in outer neutron star crusts (United States)

    Cermeño, Marina; Pérez-García, M. Ángeles; Silk, Joseph


    We calculate for the first time the phonon excitation rate in the outer crust of a neutron star due to scattering from light dark matter (LDM) particles gravitationally boosted into the star. We consider dark matter particles in the sub-GeV mass range scattering off a periodic array of nuclei through an effective scalar-vector interaction with nucleons. We find that LDM effects cause a modification of the net number of phonons in the lattice as compared to the standard thermal result. In addition, we estimate the contribution of LDM to the ion-ion thermal conductivity in the outer crust and find that it can be significantly enhanced at large densities. Our results imply that for magnetized neutron stars the LDM-enhanced global conductivity in the outer crust will tend to reduce the anisotropic heat conduction between perpendicular and parallel directions to the magnetic field.

  8. Vortex Pinning and Dynamics in the Neutron Star Crust. (United States)

    Wlazłowski, Gabriel; Sekizawa, Kazuyuki; Magierski, Piotr; Bulgac, Aurel; Forbes, Michael McNeil


    The nature of the interaction between superfluid vortices and the neutron star crust, conjectured by Anderson and Itoh in 1975 to be at the heart vortex creep and the cause of glitches, has been a long-standing question in astrophysics. Using a qualitatively new approach, we follow the dynamics as superfluid vortices move in response to the presence of "nuclei" (nuclear defects in the crust). The resulting motion is perpendicular to the force, similar to the motion of a spinning top when pushed. We show that nuclei repel vortices in the neutron star crust, and characterize the force per unit length of the vortex line as a function of the vortex element to the nucleus separation.

  9. Implication of Flow in the Lower Crust on Strain Localization (United States)

    Le Pourhiet, Laetitia


    A major difference between oceanic and continental crust is the capacity of the lower crust to flow. This has been the moto of the research group centered around Genia Burov over the last 15 years and I will try to summarize the results of number of numerical models run in different geodynamic setting to tackle the question of the rheology of the lithosphere and crust at the scale of plate tectonics. I will insist on how apriori very complex numerical models have helped the community to build our intuition on geodynamics processes and change the way of thinking the interactions between mantle process and crustal processes which are the core of plate tectonic and beyond. I will finally discuss what have we learn about the rheology of the lithosphere so far and how we intend to pursues evgeni's fundamental contribution to the field.

  10. Formation of hybrid arc andesites beneath thick continental crust (United States)

    Straub, Susanne M.; Gomez-Tuena, Arturo; Stuart, Finlay M.; Zellmer, Georg F.; Espinasa-Perena, Ramon; Cai, Yue; Iizuka, Yoshiyuki


    Andesite magmatism at convergent margins is essential for the differentiation of silicate Earth, but no consensus exists as to andesite petrogenesis. Models proposing origin of primary andesite melts from mantle and/or slab materials remain in deadlock with the seemingly irrefutable petrographic and chemical evidence for andesite formation through mixing of basaltic mantle melts with silicic components from the overlying crust. Here we use 3He/4He ratios of high-Ni olivines to demonstrate the mantle origin of basaltic to andesitic arc magmas in the central Mexican Volcanic Belt (MVB) that is constructed on ~ 50 km thick continental crust. We propose that the central MVB arc magmas are hybrids of high-Mg# > 70 basaltic and dacitic initial mantle melts which were produced by melting of a peridotite subarc mantle interspersed with silica-deficient and silica-excess pyroxenite veins. These veins formed by infiltration of reactive silicic components from the subducting slab. Partial melts from pyroxenites, and minor component melts from peridotite, mix in variable proportions to produce high-Mg# basaltic, andesitic and dacitic magmas. Moderate fractional crystallization and recharge melt mixing in the overlying crust produces then the lower-Mg# magmas erupted. Our model accounts for the contrast between the arc-typical SiO2 variability at a given Mg# and the strong correlation between major element oxides SiO2, MgO and FeO which is not reproduced by mantle-crust mixing models. Our data further indicate that viscous high-silica mantle magmas may preferentially be emplaced as intrusive silicic plutonic rocks in the crust rather than erupt. Ultimately, our results imply a stronger turnover of slab and mantle materials in subduction zones with a negligible, or lesser dilution, by materials from the overlying crust.

  11. Lake retention of manufactured nanoparticles

    NARCIS (Netherlands)

    Koelmans, A.A.; Quik, J.T.K.; Velzeboer, I.


    For twenty-five world lakes and three engineered nanoparticles (ENP), lake retention was calculated using a uniformly mixed lake mass balance model. This follows similar approaches traditionally used in water quality management. Lakes were selected such that lake residence times, depths and areal hy

  12. Lake retention of manufactured nanoparticles

    NARCIS (Netherlands)

    Koelmans, A.A.; Quik, J.T.K.; Velzeboer, I.


    For twenty-five world lakes and three engineered nanoparticles (ENP), lake retention was calculated using a uniformly mixed lake mass balance model. This follows similar approaches traditionally used in water quality management. Lakes were selected such that lake residence times, depths and areal hy

  13. Salting our freshwater lakes. (United States)

    Dugan, Hilary A; Bartlett, Sarah L; Burke, Samantha M; Doubek, Jonathan P; Krivak-Tetley, Flora E; Skaff, Nicholas K; Summers, Jamie C; Farrell, Kaitlin J; McCullough, Ian M; Morales-Williams, Ana M; Roberts, Derek C; Ouyang, Zutao; Scordo, Facundo; Hanson, Paul C; Weathers, Kathleen C


    The highest densities of lakes on Earth are in north temperate ecosystems, where increasing urbanization and associated chloride runoff can salinize freshwaters and threaten lake water quality and the many ecosystem services lakes provide. However, the extent to which lake salinity may be changing at broad spatial scales remains unknown, leading us to first identify spatial patterns and then investigate the drivers of these patterns. Significant decadal trends in lake salinization were identified using a dataset of long-term chloride concentrations from 371 North American lakes. Landscape and climate metrics calculated for each site demonstrated that impervious land cover was a strong predictor of chloride trends in Northeast and Midwest North American lakes. As little as 1% impervious land cover surrounding a lake increased the likelihood of long-term salinization. Considering that 27% of large lakes in the United States have >1% impervious land cover around their perimeters, the potential for steady and long-term salinization of these aquatic systems is high. This study predicts that many lakes will exceed the aquatic life threshold criterion for chronic chloride exposure (230 mg L(-1)), stipulated by the US Environmental Protection Agency (EPA), in the next 50 y if current trends continue.

  14. Reduced and unstratified crust in CV chondrite parent body. (United States)

    Ganino, Clément; Libourel, Guy


    Early Solar System planetesimal thermal models predict the heating of the chondritic protolith and the preservation of a chondritic crust on differentiated parent bodies. Petrological and geochemical analyses of chondrites have suggested that secondary alteration phases formed at low temperatures (hydrothermal fluid. Putative 'onion shell' structures are not anymore a requirement for the CV parent body crust.Meteorites may unlock the history of the early solar system. Here, the authors find, through Ca-Fe-rich secondary phases, that the distinction between reduced and oxidized CV chondrites is invalid; therefore, CV3 chondrites are asteroid fragments that percolated heterogeneously via porous flow of hydrothermal fluid.

  15. Laboratory experiments duplicate conditions in the Earth’s crust (United States)

    Peselnick, L.; Dieterich, J.H.; Stewart, R.M.


    An experimental device that simulates conditions in the Earth's crust at depths of up to 30 kilometers has been constructed by geophysicists working at the U.S Geological Survey laboratories in Menlo Park, California. A high pressure "bomb" is being used to experimentally measure the velocity of seismic waves in different types of rock at various confining pressures and temperatures. The principal purpose of these measurements is to determine the elastic and non-elastic properties of rocks and minerals under conditions of high-pressure such as exist deep in the Earth's crust

  16. Dust Emissions from Undisturbed and Disturbed, Crusted Playa Surfaces: Cattle Trampling Effect (United States)

    Zobeck, T. M.; Baddock, M. C.; van Pelt, R.; Fredrickson, E. L.


    Dry playa lake beds can be a significant source of fine dust emissions during high wind events in arid and semiarid landscapes. The physical and chemical properties of the playa surface control the amount and properties of the dust emitted. In this study, we use a field wind tunnel to quantify the dust emissions from a bare, fine-textured playa surface located in the Chihuahua Desert at the Jornada Experimental Range, near Las Cruces, New Mexico, USA. We tested natural, undisturbed crusted surfaces and surfaces that had been subjected to two levels of domestic animal disturbance. The animal disturbance was provided by trampling produced from one and ten passes along the length of the wind tunnel by a 630 kg Angus-Hereford cross cow. The trampling broke the durable crust and created loose erodible material. Each treatment (natural crust, one pass, and ten passes) was replicated three times. A push-type wind tunnel with a 6 m long, 0.5 m wide, and 1 m high test section was used to generate dust emissions under controlled conditions. Clean medium sand was dropped onto the playa surface to act as an abrader material. The tunnel wind speed was equivalent to 15 m/s at a height of 2 m over a smooth soil surface. The tunnel was initially run for ten minutes, with no abrader added. A second 30 minute run was subsequently sampled as abrader was added to the wind stream. Dust and saltating material were collected using an isokinetic slot sampler at the end of the tunnel. Total airborne dust was collected on two 25 cm x 20 cm glass fiber filters (GFF) and measured using a GRIMM particle monitor every 6 sec throughout each test run. Disturbance by trampling generated increased saltating material and airborne dust. The amount of saltating material measured during the initial (no abrader added) run was approximately 70% greater and 5.8 times the amount of saltating material measured on the one pass and ten pass plots, respectively, compared with that observed on the undisturbed

  17. 2016 Lake Michigan Lake Trout Working Group Report (United States)

    Madenjian, Charles P.; Breidert, Brian; Boyarski, David; Bronte, Charles R.; Dickinson, Ben; Donner, Kevin; Ebener, Mark P.; Gordon, Roger; Hanson, Dale; Holey, Mark; Janssen, John; Jonas, Jory; Kornis, Matthew; Olsen, Erik; Robillard, Steve; Treska, Ted; Weldon, Barry; Wright, Greg D.


    This report provides a review on the progression of lake trout rehabilitation towards meeting the Salmonine Fish Community Objectives (FCOs) for Lake Michigan (Eshenroder et. al. 1995) and the interim goal and evaluation objectives articulated in A Fisheries Management Implementation Strategy for the Rehabilitation of Lake Trout in Lake Michigan (Dexter et al. 2011); we also include data describing lake trout stocking and mortality to portray the present state of progress towards lake trout rehabilitation.

  18. An earthquake study in the Lake Baringo basin of the central Kenya Rift (United States)

    Tongue, Jane; Maguire, Peter; Burton, Paul


    A 100 × 80 km 2 earthquake recording network was operated for three months (January-March 1990) in the Lake Baringo region of the Kenya Rift Valley. Twenty-nine seismic sites were occupied by short-period stations over a region including the Elgeyo escarpment, the Kerio Valley, the Tugen Hills and Lake Baringo itself. Eighty local events of ML Lake Baringo at a depth of about 5 km and occurring as swarm activity. Ninety percent of the events occurred at depths shallower than 12 km. The brittle-ductile transition zone in this area is determined at a depth of 12-16 km, similar to that in the Lake Bogoria area immediately to the south. A preliminary study of focal mechanisms of suitable events indicates WNW-ESE extension across the Lake Baringo basin and suggests the presence of sub-vertical rupture surfaces beneath the lake. These may be caused by the insertion of basic dykes into the upper crust, and the rupture process assisted by high temperature and pressure geothermal fluids. The inversion of local P-wave arrival time data for the upper crustal velocity structure beneath Lake Baringo identifies a low-velocity zone beneath surface geothermal activity, a relationship previously demonstrated for the Lake Bogoria region.

  19. Experimental study on the P wave velocity in rocks from lower crust and crust-mantle transitional zone beneath the Hannuoba

    Institute of Scientific and Technical Information of China (English)


    Cenozoic basalt-borne mafic granulite-facies plagioclase pyroxenite and eclogite-facies garnet pyroxenite xenoliths from the Hannuoba, as well as nearby Archean terrain granulites, are selected for the experimental study on the P wave velocity at high temperature and high pressure in order to reveal the present-day compositional features for the lower crust and crust-mantle transitional zone. Results show that mafic xenoliths have high Vp (7.0~8.0 km/s), in contrast, the Archean terrain granulites have low Vp (<7.0 km/s). High Vp mafic xenoliths can represent the present-day compositional features for the lower crust and crust-mantle transitional zone beneath the Hannuoba. This provides new evidence for the crust vertical growth and the formation of the crust-mantle transitional zone resulting from the magma underplating. Low Vp Archean granulite still remains the characteristics of the early lower crust.

  20. Influences of the Weather and Climate on Wintering Migratory Bird in Dongting Lake

    Institute of Scientific and Technical Information of China (English)

    HUANG; Ju-mei; NIU; Ling-zhi; YAO; Yi; QIN; Hong


    [Objective] The research aimed to study influences of the weather and climate on wintering migratory bird in Dongting Lake. [Method] Bird analysis data provided by East Dongting Lake National Nature Reserve and wintering migratory bird monitoring data in big and small west lakes in recent 5 years were used. By combing water level data and various meteorological factors in Chenglingji, wintering migratory bird in Dongting Lake was analyzed. [Result] Abnormal precipitation led to drought or flood in Dongting Lake, causing significant adverse effect on the birds. Abnormal climate was important reason for that wintering migratory bird greatly reduced, such as high temperature and later going south of the strong cold air. Extreme weather and climate events led that some birds in Dongting Lake significantly reduced. Meteorological element had certain influence to bird survey. We should select a reasonable investigation time based on weather and climate. In Birding Festival, weather had little effect on bird species observation. In the migratory season of bird, we could see many birds in fine cold weather after a strong cold air, which suitable for observing bird. When it was low temperature or less rain in autumn, and was high temperature or more rain and sunshine in early winter, it was suitable for migratory birds wintering in Dongting Lake. Ardea cinerea, Anser fabalis and Anser erythropus were more in sunny days while Phalacrocorax carbo was more in rainy weather. Grus grus was more in heavy wind weather while Recurvirostra avosetta was more in small wind weather. [Conclusion] The research provided scientific basis for studying migratory bird in east Dongting Lake.

  1. Hydrography - Lakes Assessments - Non Attaining (United States)

    NSGIC GIS Inventory (aka Ramona) — This layer shows only non attaining lakes of the Integrated List. The Lakes Integrated List represents lake assessments in an integrated format for the Clean Water...

  2. Boat Dwellers of Weishan Lake

    Institute of Scientific and Technical Information of China (English)



    IN the south of Shandong Province, Weishan Lake is the largest freshwater lake in northern China. Under the bright blue sky, it gleams like a large mirror. "As the sun is about to set, Weishan Lake is quiet…" Humming

  3. Nature of the crust under Afar: new igneous, not thinned continental (United States)

    Mohr, Paul


    Thinned continental crust is considered absent from beneath Afar, except for isolated remnants such as comprise the Danakil Block. The Ethiopian Plateau sialic crust thins abruptly across the plateau-Afar margin to abut new igneous crust under Afar, generated during the early development of the Red Sea basin. Analyses of stretching and sea-floor spreading amounts elsewhere in the Red Sea and Gulf of Aden basins are employed to support this concept. The dual layering of the Afar crust, and the similarity of P-wave velocities in these layers to velocities in sialic crust, lead to the proposal that new continental crust can be generated at magmatic rift zones.

  4. Hornblendite delineates zones of mass transfer through the lower crust (United States)

    Daczko, Nathan R.; Piazolo, Sandra; Meek, Uvana; Stuart, Catherine A.; Elliott, Victoria


    Geochemical signatures throughout the layered Earth require significant mass transfer through the lower crust, yet geological pathways are under-recognized. Elongate bodies of basic to ultrabasic rocks are ubiquitous in exposures of the lower crust. Ultrabasic hornblendite bodies hosted within granulite facies gabbroic gneiss of the Pembroke Valley, Fiordland, New Zealand, are typical occurrences usually reported as igneous cumulate hornblendite. Their igneous features contrast with the metamorphic character of their host gabbroic gneiss. Both rock types have a common parent; field relationships are consistent with modification of host gabbroic gneiss into hornblendite. This precludes any interpretation involving cumulate processes in forming the hornblendite; these bodies are imposter cumulates. Instead, replacement of the host gabbroic gneiss formed hornblendite as a result of channeled high melt flux through the lower crust. High melt/rock ratios and disequilibrium between the migrating magma (granodiorite) and its host gabbroic gneiss induced dissolution (grain-scale magmatic assimilation) of gneiss and crystallization of mainly hornblende from the migrating magma. The extent of this reaction-replacement mechanism indicates that such hornblendite bodies delineate significant melt conduits. Accordingly, many of the ubiquitous basic to ultrabasic elongate bodies of the lower crust likely map the ‘missing’ mass transfer zones.

  5. Rainfall intensity effects on crusting and mode of seedling ...

    African Journals Online (AJOL)


    Sep 3, 2014 ... However, soils with extensive cracking are likely to have higher EMP and lower MED ... impact and rapid wetting (Liu et al., 2011). Moreover, higher ... formation of crusts at the soil–atmosphere interface adversely affects crop ...

  6. The off-crust origin of granite batholiths

    Institute of Scientific and Technical Information of China (English)

    Antonio Castro


    Granitod batholiths of I-type features (mostly granodiorites and tonalites), and particularly those forming the large plutonic associations of active continental margins and intracontinental collisional belts, represent the most outstanding magmatic episodes occurred in the continental crust. The origin of magmas, however, remains controversial. The application of principles from phase equilibria is crucial to understand the problem of granitoid magma generation. An adequate comparison between rock com-positions and experimental liquids has been addressed by using a projected compositional space in the plane F(Fe þ Mg)eAnorthiteeOrthoclase. Many calc-alkaline granitoid trends can be considered cotectic liquids. Assimilation of country rocks and other not-cotectic processes are identified in the projected diagram. The identification of cotectic patterns in batholith implies high temperatures of magma segregation and fractionation (or partial melting) from an intermediate (andesitic) source. The com-parison of batholiths with lower crust granulites, in terms of major-element geochemistry, yields that both represent liquids and solid residues respectively from a common andesitic system. This is compatible with magmas being formed by melting, and eventual reaction with the peridotite mantle, of subducted mélanges that are finally relaminated as magmas to the lower crust. Thus, the off-crust generation of granitoids batholiths constitutes a new paradigm in which important geological implica-tions can be satisfactorily explained. Geochemical features of Cordilleran-type batholiths are totally compatible with this new conception.

  7. Oceanic crust recycling and the formation of lower mantle heterogeneity (United States)

    van Keken, Peter E.; Ritsema, Jeroen; Haugland, Sam; Goes, Saskia; Kaneshima, Satoshi


    The Earth's lower mantle is heterogeneous at multiple scales as demonstrated for example by the degree-2 distribution of LLSVPs seen in global tomography and widespread distribution of small scale heterogeneity as seen in seismic scattering. The origin of this heterogeneity is generally attributed to leftovers from Earth's formation, the recycling of oceanic crust, or a combination thereof. Here we will explore the consequences of long-term oceanic crust extraction and recycling by plate tectonics. We use geodynamical models of mantle convection that simulate plates in an energetically consistent manner. The recycling of oceanic crust over the age of the Earth produces persistent lower mantle heterogeneity while the upper mantle tends to be significantly more homogeneous. We quantitatively compare the predicted heterogeneity to that of the present day Earth by tomographic filtering of the geodynamical models and comparison with S40RTS. We also predict the scattering characteristics from S-P conversions and compare these to global scattering observations. The geophysical comparison shows that lower mantle heterogeneity is likely dominated by long-term oceanic crust recycling. The models also demonstrate reasonable agreement with the geochemically observed spread between HIMU-EM1-DMM in ocean island basalts as well as the long-term gradual depletion of the upper mantle as observed in Lu-Hf systematics.

  8. Fracture behaviour of bread crust: Effect of bread cooling conditions

    NARCIS (Netherlands)

    Primo-Martín, C.; Beukelaer, H. de; Hamer, R.J.; Vliet, T. van


    The effect of air and vacuum cooling on the fracture behaviour and accompanying sound emission, moisture content and crispness of bread crust were investigated. Vacuum cooling resulted in rapid evaporative cooling of products that contained high moisture content. Fracture experiments showed a clear

  9. Crusted scabies in a chid with systemic lupus erythematosus

    Directory of Open Access Journals (Sweden)

    Nurimar C.F. Wanke


    Full Text Available A child with systemic lupus erythematosus who has been treated with prednisone for three years, developed crusted scabies. Scrapings from lesions revealed Sarcoptes scabiei adult mites mad eggs. The patient died with septicemia and renal failure soon after starting topical 20% sulfur. A marked improvement was observed in the cutaneous lesions.

  10. Fracture behaviour of bread crust: Effect of bread cooling conditions

    NARCIS (Netherlands)

    Primo Martin, C.; Beukelaer, de H.J.; Hamer, R.J.; Vliet, van T.


    The effect of air and vacuum cooling on the fracture behaviour and accompanying sound emission, moisture content and crispness of bread crust were investigated. Vacuum cooling resulted in rapid evaporative cooling of products that contained high moisture content. Fracture experiments showed a clear

  11. Water Sorption and Transport in Dry, Crispy Bread Crust

    NARCIS (Netherlands)

    Meinders, M.B.J.; Nieuwenhuijzen, N.H. van; Tromp, R.H.; Hamer, R.J.; Vliet, T. van


    Water - sorption and dynamic properties of bread crust have been studied in gravimetric sorption experiments. Water uptake and loss were measured while relative humidity (RH) was stepwise increased or decreased (isotherm experiment) or varied between two adjusted values (oscillatory experiment). Exp

  12. Water sorption and transport in dry crispy bread crust

    NARCIS (Netherlands)

    Meinders, M.B.J.; Nieuwenhuijzen, van N.H.; Tromp, R.H.; Hamer, R.J.; Vliet, van T.


    Water sorption and dynamical properties of bread crust have been studied using gravimetric sorption experiments. Water uptake and loss were followed while relative humidity (RH) was stepwise in- or decreased (isotherm experiment) or varied between two adjusted values (oscillatory experiment). Experi

  13. Magnetization of the oceanic crust: TRM or CRM? (United States)

    Raymond, C. A.; Labrecque, J. L.


    A model was proposed in which chemical remanent magnetization (CRM) acquired within the first 20 Ma of crustal evolution may account for 80% of the bulk natural remanent magnetization (NRM) of older basalts. The CRM of the crust is acquired as the original thermoremanent magnetization (TRM) is lost through low temperature alteration. The CRM intensity and direction are controlled by the post-emplacement polarity history. This model explains several independent observations concerning the magnetization of the oceanic crust. The model accounts for amplitude and skewness discrepancies observed in both the intermediate wavelength satellite field and the short wavelength sea surface magnetic anomaly pattern. It also explains the decay of magnetization away from the spreading axis, and the enhanced magnetization of the Cretaceous Quiet Zones while predicting other systematic variations with age in the bulk magnetization of the oceanic crust. The model also explains discrepancies in the anomaly skewness parameter observed for anomalies of Cretaceous age. Further studies indicate varying rates of TRM decay in very young crust which depicts the advance of low temperature alteration through the magnetized layer.

  14. Pristine Igneous Rocks and the Genesis of Early Planetary Crusts (United States)

    Warren, Paul H.; Lindstrom, David (Technical Monitor)


    Our studies are highly interdisciplinary, but are focused on the processes and products of early planetary and asteroidal differentiation, especially the genesis of the ancient lunar crust. The compositional diversity that we explore is the residue of process diversity, which has strong relevance for comparative planetology.

  15. Gold in meteorites and in the earth's crust (United States)

    Jones, Robert Sprague


    The reported gold contents of meteorites range from 0.0003 to 8.74 parts per million. Gold is siderophilic, and the greatest amounts in meteorites are in the iron phases. Estimates ,of the gold content of the earth's crust are in the range of 0.001 to 0.006 parts per million.

  16. The off-crust origin of granite batholiths

    Directory of Open Access Journals (Sweden)

    Antonio Castro


    Full Text Available Granitod batholiths of I-type features (mostly granodiorites and tonalites, and particularly those forming the large plutonic associations of active continental margins and intracontinental collisional belts, represent the most outstanding magmatic episodes occurred in the continental crust. The origin of magmas, however, remains controversial. The application of principles from phase equilibria is crucial to understand the problem of granitoid magma generation. An adequate comparison between rock compositions and experimental liquids has been addressed by using a projected compositional space in the plane F(Fe + Mg–Anorthite–Orthoclase. Many calc-alkaline granitoid trends can be considered cotectic liquids. Assimilation of country rocks and other not-cotectic processes are identified in the projected diagram. The identification of cotectic patterns in batholith implies high temperatures of magma segregation and fractionation (or partial melting from an intermediate (andesitic source. The comparison of batholiths with lower crust granulites, in terms of major-element geochemistry, yields that both represent liquids and solid residues respectively from a common andesitic system. This is compatible with magmas being formed by melting, and eventual reaction with the peridotite mantle, of subducted mélanges that are finally relaminated as magmas to the lower crust. Thus, the off-crust generation of granitoids batholiths constitutes a new paradigm in which important geological implications can be satisfactorily explained. Geochemical features of Cordilleran-type batholiths are totally compatible with this new conception.

  17. Fracture behaviour of bread crust: Effect of ingredient modification

    NARCIS (Netherlands)

    Primo-Martin, C.; Beukelaer, de H.J.; Hamer, R.J.; Vliet, van T.


    The influence of the formulation on the crispness of bread crust was studied. Crispness is a relevant sensory attribute that depends on several factors particularly the plasticizer content (water), the mechanical properties of the solid matrix and the morphological architecture of the bread. Enzymes

  18. Evolution of Fractal Parameters through Development Stage of Soil Crust (United States)

    Ospina, Abelardo; Florentino, Adriana; Tarquis, Ana Maria


    Soil surface characteristics are subjected to changes driven by several interactions between water, air, biotic and abiotic components. One of the examples of such interactions is provided through biological soil crusts (BSC) in arid and semi-arid environments. BSC are communities composed of cyanobacteria, fungi, mosses, lichens, algae and liverworts covering the soil surface and play an important role in ecosystem functioning. The characteristics and formation of these BSC influence the soil hydrological balance, control the mass of eroded sediment, increase stability of soil surface, and influence plant productivity through the modification of nitrogen and carbon cycle. The site of this work is located at Quibor and Ojo de Agua (Lara state, Venezuela). The Quibor Depression in Venezuela is a major agricultural area being at semi-arid conditions and limited drainage favor the natural process of salinization. Additionally, the extension and intensification of agriculture has led to over-exploitation of groundwater in the past 30 years (Méndoza et al., 2013). The soil microbial crust develops initially on physical crusts which are mainly generated since wetting and drying, being a recurrent feature in the Quíbor arid zone. The microbiotic crust is organic, composed of macro organisms (bryophytes and lichens) and microorganisms (cyanobacteria, fungi algae, etc.); growing on the ground, forming a thickness no greater than 3 mm. For further details see Toledo and Florentino (2009). This study focus on characterize the development stage of the BSC based on image analysis. To this end, grayscale images of different types of biological soil crust at different stages where taken, each image corresponding to an area of 12.96 cm2 with a resolution of 1024x1024 pixels (Ospina et al., 2015). For each image lacunarity and fractal dimension through the differential box counting method were calculated. These were made with the software ImageJ/Fraclac (Karperien, 2013

  19. Helium isotopes in ferromanganese crusts from the central Pacific Ocean (United States)

    Basu, S.; Stuart, F.M.; Klemm, V.; Korschinek, G.; Knie, K.; Hein, J.R.


    Helium isotopes have been measured in samples of two ferromanganese crusts (VA13/2 and CD29-2) from the central Pacific Ocean. With the exception of the deepest part of crust CD29-2 the data can be explained by a mixture of implanted solar- and galactic cosmic ray-produced (GCR) He, in extraterrestrial grains, and radiogenic He in wind-borne continental dust grains. 4He concentrations are invariant and require retention of less than 12% of the in situ He produced since crust formation. Loss has occurred by recoil and diffusion. High 4He in CD29-2 samples older than 42 Ma are correlated with phosphatization and can be explained by retention of up to 12% of the in situ-produced 4He. 3He/4He of VA13/2 samples varies from 18.5 to 1852 Ra due almost entirely to variation in the extraterrestrial He contribution. The highest 3He/4He is comparable to the highest values measured in interplanetary dust particles (IDPs) and micrometeorites (MMs). Helium concentrations are orders of magnitude lower than in oceanic sediments reflecting the low trapping efficiency for in-falling terrestrial and extraterrestrial grains of Fe-Mn crusts. The extraterrestrial 3He concentration of the crusts rules out whole, undegassed 4–40 μm diameter IDPs as the host. Instead it requires that the extraterrestrial He inventory is carried by numerous particles with significantly lower He concentrations, and occasional high concentration GCR-He-bearing particles.

  20. Continental crust formation on early Earth controlled by intrusive magmatism (United States)

    Rozel, A. B.; Golabek, G. J.; Jain, C.; Tackley, P. J.; Gerya, T.


    The global geodynamic regime of early Earth, which operated before the onset of plate tectonics, remains contentious. As geological and geochemical data suggest hotter Archean mantle temperature and more intense juvenile magmatism than in the present-day Earth, two crust-mantle interaction modes differing in melt eruption efficiency have been proposed: the Io-like heat-pipe tectonics regime dominated by volcanism and the “Plutonic squishy lid” tectonics regime governed by intrusive magmatism, which is thought to apply to the dynamics of Venus. Both tectonics regimes are capable of producing primordial tonalite-trondhjemite-granodiorite (TTG) continental crust but lithospheric geotherms and crust production rates as well as proportions of various TTG compositions differ greatly, which implies that the heat-pipe and Plutonic squishy lid hypotheses can be tested using natural data. Here we investigate the creation of primordial TTG-like continental crust using self-consistent numerical models of global thermochemical convection associated with magmatic processes. We show that the volcanism-dominated heat-pipe tectonics model results in cold crustal geotherms and is not able to produce Earth-like primordial continental crust. In contrast, the Plutonic squishy lid tectonics regime dominated by intrusive magmatism results in hotter crustal geotherms and is capable of reproducing the observed proportions of various TTG rocks. Using a systematic parameter study, we show that the typical modern eruption efficiency of less than 40 per cent leads to the production of the expected amounts of the three main primordial crustal compositions previously reported from field data (low-, medium- and high-pressure TTG). Our study thus suggests that the pre-plate-tectonics Archean Earth operated globally in the Plutonic squishy lid regime rather than in an Io-like heat-pipe regime.

  1. Continental crust formation on early Earth controlled by intrusive magmatism. (United States)

    Rozel, A B; Golabek, G J; Jain, C; Tackley, P J; Gerya, T


    The global geodynamic regime of early Earth, which operated before the onset of plate tectonics, remains contentious. As geological and geochemical data suggest hotter Archean mantle temperature and more intense juvenile magmatism than in the present-day Earth, two crust-mantle interaction modes differing in melt eruption efficiency have been proposed: the Io-like heat-pipe tectonics regime dominated by volcanism and the "Plutonic squishy lid" tectonics regime governed by intrusive magmatism, which is thought to apply to the dynamics of Venus. Both tectonics regimes are capable of producing primordial tonalite-trondhjemite-granodiorite (TTG) continental crust but lithospheric geotherms and crust production rates as well as proportions of various TTG compositions differ greatly, which implies that the heat-pipe and Plutonic squishy lid hypotheses can be tested using natural data. Here we investigate the creation of primordial TTG-like continental crust using self-consistent numerical models of global thermochemical convection associated with magmatic processes. We show that the volcanism-dominated heat-pipe tectonics model results in cold crustal geotherms and is not able to produce Earth-like primordial continental crust. In contrast, the Plutonic squishy lid tectonics regime dominated by intrusive magmatism results in hotter crustal geotherms and is capable of reproducing the observed proportions of various TTG rocks. Using a systematic parameter study, we show that the typical modern eruption efficiency of less than 40 per cent leads to the production of the expected amounts of the three main primordial crustal compositions previously reported from field data (low-, medium- and high-pressure TTG). Our study thus suggests that the pre-plate-tectonics Archean Earth operated globally in the Plutonic squishy lid regime rather than in an Io-like heat-pipe regime.

  2. Primitive layered gabbros from fast-spreading lower oceanic crust. (United States)

    Gillis, Kathryn M; Snow, Jonathan E; Klaus, Adam; Abe, Natsue; Adrião, Alden B; Akizawa, Norikatsu; Ceuleneer, Georges; Cheadle, Michael J; Faak, Kathrin; Falloon, Trevor J; Friedman, Sarah A; Godard, Marguerite; Guerin, Gilles; Harigane, Yumiko; Horst, Andrew J; Hoshide, Takashi; Ildefonse, Benoit; Jean, Marlon M; John, Barbara E; Koepke, Juergen; Machi, Sumiaki; Maeda, Jinichiro; Marks, Naomi E; McCaig, Andrew M; Meyer, Romain; Morris, Antony; Nozaka, Toshio; Python, Marie; Saha, Abhishek; Wintsch, Robert P


    Three-quarters of the oceanic crust formed at fast-spreading ridges is composed of plutonic rocks whose mineral assemblages, textures and compositions record the history of melt transport and crystallization between the mantle and the sea floor. Despite the importance of these rocks, sampling them in situ is extremely challenging owing to the overlying dykes and lavas. This means that models for understanding the formation of the lower crust are based largely on geophysical studies and ancient analogues (ophiolites) that did not form at typical mid-ocean ridges. Here we describe cored intervals of primitive, modally layered gabbroic rocks from the lower plutonic crust formed at a fast-spreading ridge, sampled by the Integrated Ocean Drilling Program at the Hess Deep rift. Centimetre-scale, modally layered rocks, some of which have a strong layering-parallel foliation, confirm a long-held belief that such rocks are a key constituent of the lower oceanic crust formed at fast-spreading ridges. Geochemical analysis of these primitive lower plutonic rocks--in combination with previous geochemical data for shallow-level plutonic rocks, sheeted dykes and lavas--provides the most completely constrained estimate of the bulk composition of fast-spreading oceanic crust so far. Simple crystallization models using this bulk crustal composition as the parental melt accurately predict the bulk composition of both the lavas and the plutonic rocks. However, the recovered plutonic rocks show early crystallization of orthopyroxene, which is not predicted by current models of melt extraction from the mantle and mid-ocean-ridge basalt differentiation. The simplest explanation of this observation is that compositionally diverse melts are extracted from the mantle and partly crystallize before mixing to produce the more homogeneous magmas that erupt.

  3. [Diversity of nitrogen-fixing microorganisms in biological soil crusts of copper mine wastelands]. (United States)

    Zhan, Jing; Yang, Gui-De; Sun, Qing-Ye


    Biological soil crusts play an important role in increasing the accumulation of organic matter and nitrogen in re-vegetated mining wastelands. The diversity of nitrogen-fixing microorganisms in three types of biological soil crusts (algal crust, moss crust and algal-moss crust) from two wastelands of copper mine tailings were investigated by polymerase chain reaction-denaturing gradient gel electrophoresis, based on the nifH gene of diazotrophs, to investigate: The diversity of nifH gene in the crusts of mine wastelands, and whether and how the nifH gene diversity in the crusts could be affected by the development of plant communities. The algal crust on the barren area displayed the highest nifH gene diversity, followed by the algal-moss crusts within vascular plant communities, and the moss crust displayed the lowest nifH gene diversity. The diversity of diazotrophs in algal-moss crust within vascular plant communities decreased with the increase of height and cover of vascular plant communities. No significant relationship was found between wasteland properties (pH, water content, contents of organic matter, nitrogen and phosphorus and heavy metal concentration) and nifH gene diversity in the crusts. Sequencing and phylogenetic analysis indicated that most nitrogen-fixing taxa in the crusts of mine wastelands belonged to Cyanobacteria, especially nonheterocystous filamentous Cyanobacteria.

  4. [Effects of soil crusts on surface hydrology in the semiarid Loess hilly area]. (United States)

    Wei, Wei; Wen, Zhi; Chen, Li-Ding; Chen, Jin; Wu, Dong-Ping


    Soil crusts are distributed extensively in the Chinese Loess Plateau and play key roles in surface hydrological processes. In this study, a typical loess hilly region in Anjiagou catchment, Dingxi city, Gansu province was selected as the study region, and soil crusts in the catchment were investigated. Then, the hydrological effect of soil crusts was studied by using multi-sampling and hydrological monitoring experiments. Several key results were shown as follows. Firstly, compared with bared soil without crust cover, soil crusts can greatly reduce the bulk density, improve the porosity of soil, and raise the holding capacity of soil moisture which ranges from 1.4 to 1.9 times of that of bared soil. Secondly, the role of soil crust on rainfall interception was very significant. Moss crust was found to be strongest on rainfall interception, followed by synantectic crusts and lichen crusts. Bared soil without covering crusts was poorest in resisting rainfall splash. Thirdly, hydrological simulation experiments indicate that soil crusts play a certain positive role in promoting the water infiltration capacity, and the mean infiltration rate of the crusted soil was 2 times higher than that of the no-crust covered soils. While the accumulated infiltrated water amounts was also far higher than that of the bared soil.

  5. Formation of lower continental crust by relamination of buoyant arc lavas and plutons (United States)

    Kelemen, Peter B.; Behn, Mark D.


    The formation of the Earth's continents is enigmatic. Volcanic arc magmas generated above subduction zones have geochemical compositions that are similar to continental crust, implying that arc magmatic processes played a central role in generating continental crust. Yet the deep crust within volcanic arcs has a very different composition from crust at similar depths beneath the continents. It is therefore unclear how arc crust is transformed into continental crust. The densest parts of arc lower crust may delaminate and become recycled into the underlying mantle. Here we show, however, that even after delamination, arc lower crust still has significantly different trace element contents from continental lower crust. We suggest that it is not delamination that determines the composition of continental crust, but relamination. In our conceptual model, buoyant magmatic rocks generated at arcs are subducted. Then, upon heating at depth, they ascend and are relaminated at the base of the overlying crust. A review of the average compositions of buoyant magmatic rocks -- lavas and plutons -- sampled from the Aleutians, Izu-Bonin-Marianas, Kohistan and Talkeetna arcs reveals that they fall within the range of estimated major and trace elements in lower continental crust. Relamination may thus provide an efficient process for generating lower continental crust.

  6. Seasonal prevalence of antibodies to Leptospira interrogans in Antillean manatees from a landlocked lake in Tabasco, Mexico. (United States)

    Aragón-Martínez, Arianna; Olivera-Gómez, León D; Jiménez-Domínguez, Darwin


    Factors that alter the dynamics of ecologic systems can influence transmission of infectious diseases and may lead to decreases in natural populations. Leptospirosis is a cosmopolitan disease of zoonotic importance that affects most mammals. At the southern Gulf of Mexico, Antillean manatees (Trichechus manatus manatus) inhabit highly variable environments, with extended floods during the rainy season and drought conditions during the dry season that affect food availability and the thermal environment for manatees. We tested for changes in prevalence and titers of antibodies to 12 serovars of Leptospira interrogans in manatees between dry and rainy seasons. We determined titers for L. interrogans through microscopic agglutination tests (MAT) from 10 manatees, six during the dry season (DS), and six during the rainy season (RS) in Laguna de las Ilusiones, a landlocked lake hosting a population of about 20 manatees. All individuals were antibody positive (titers ≥ 100) to at least one serovar. The serovars bataviae, bratislava, canicola, and icterohaemorrhagiae had overall prevalences ≥ 50%; bataviae, bratislava, and canicola had prevalences ≥ 50% during both seasons. Serovars icterohaemorrhagiae and pyrogenes had prevalences ≥ 50% during DS and pomona, tarassovi, wolfii, and autumnalis during RS. Significant differences in prevalence between seasons were found for pomona, tarassovi, and autumnalis. Titers of tarassovi, wolfii, autumnalis, and bataviae were significantly higher during RS. There was a high prevalence of L. interrogans during the RS independent of high availability of plant foods, coinciding with the epizootiology of the bacteria that are endemic to tropical regions. Another factor possibly influencing prevalence is high anthropogenic pressure at the lake, causing an increase in potential sources of infection. Because of possible cross-reaction in MAT, further research is needed on the molecular discrimination of serovars in animals in the

  7. Shallow and deep controls on lava lake surface motion at Kīlauea Volcano (United States)

    Patrick, M. R.; Orr, T.; Swanson, D. A.; Lev, E.


    Lava lakes provide a rare window into magmatic behavior, and lake surface motion has been used to infer deeper properties of the magmatic system. At Halema'uma'u Crater, at the summit of Kīlauea Volcano, multidisciplinary observations for the past several years indicate that lava lake surface motion can be broadly divided into two regimes: 1) stable and 2) unstable. Stable behavior is driven by lava upwelling from deeper in the lake (presumably directly from the conduit) and is an intrinsic process that drives lava lake surface motion most of the time. This stable behavior can be interrupted by periods of unstable flow (often reversals) driven by spattering - a shallowly-rooted process often extrinsically triggered by small rockfalls from the crater wall. The bursting bubbles at spatter sources create void spaces and a localized surface depression which draws and consumes surrounding surface crust. Spattering is therefore a location of lava downwelling, not upwelling. Stable (i.e. deep, upwelling-driven) and unstable (i.e. shallow, spattering-driven) behavior often alternate through time, have characteristic surface velocities, flow directions and surface temperature regimes, and also correspond to changes in spattering intensity, outgassing rates, lava level and seismic tremor. These results highlight that several processes, originating at different depths, can control the motion of the lava lake surface, and long-term interdisciplinary monitoring is required to separate these influences. These observations indicate that lake surface motion is not always a reliable proxy for deeper lake or magmatic processes. From these observations, we suggest that shallow outgassing (spattering), not lake convection, drives the variations in lake motion reported at Erta 'Ale lava lake.

  8. Comparison of element abundance between the exposed crust of the continent of China and the global averaged upper continental crust: Constraints on crustal evolution and some speculations

    Institute of Scientific and Technical Information of China (English)

    WANG Yang


    Based on the results of a study of regional element abundance in eastern China and the 1:200 000 geochemical surveys in northern Xinjiang, the element geochemical characteristics of the exposed crust in 23 tectonic units of the continent of China are summarized.Compared with the global average abundance of the upper continental crust, the exposed crust of the continent of China is compositionally more evolved than the upper crust of the island arc, but less evolved than the mature Precambrian Canadian shield. The exposed crust of the North China and Yangtze platforms has a lower SiO2 content, but markedly higher CaO and MgO contents due to the presence of widespread carbonate strata, which suggests that we should not neglect the contribution of carbonate rocks in the study of the exposed crust and the element abundance of the upper crust, in comparison with two recently published average compositional models of the global upper continental crust,the exposed crust of the continent of China is depleted in Au,Hg, Mo, Sn, and W, which suggests that their abundance in the present global models is overestimated. The exposed crust of the North China plat form and the Qinling-Dabieshan fold belt to its south has lower μ(238U/204pb) values(8), but other regions of the continent of China exhibit much higher μ values, which implies that the low μ feature of the North China platform and its adjacent regions does not have global significance. Considering the apparent lateral variation in composition of the exposed crust for the tectonic units of the continent of China, there is no adequate reason to take the average upper crust compositional model of the North China platform and its adjacent regions as a reliable composition representative for Chinese and global upper continental crust composition.

  9. Physical, chemical, and mineralogical data from surficial deposits, groundwater levels, and water composition in the area of Franklin Lake playa and Ash Meadows, California and Nevada (United States)

    Goldstein, Harland L.; Breit, George N.; Yount, James C.; Reynolds, Richard L.; Reheis, Marith C.; Skipp, Gary L.; Fisher, Eric M.; Lamothe, Paul J.


    This report presents data and describes the methods used to determine the physical attributes, as well as the chemical and mineralogical composition of surficial deposits; groundwater levels; and water composition in the area of Franklin Lake playa and Ash Meadows, California and Nevada. The results support studies that examine (1) the interaction between groundwater and the ground surface, and the transport of solutes through the unsaturated zone; (2) the potential for the accumulation of metals and metalloids in surface crusts; (3) emission of dust from metal-rich salt crust; and (4) the effects of metal-rich dusts on human and ecosystem health. The evaporation of shallow (salt in the subsurface and (or) the formation of salt crusts at the ground surface. Ground-surface characteristics such as hardness, electrical conductivity, and mineralogy depend on the types and forms of these salt crusts. In the study area, salt crusts range from hard and bedded to soft and loose (Reynolds and others, 2009). Depending on various factors such as the depth and composition of groundwater and sediment characteristics of the unsaturated zone, salt crusts may accumulate relatively high contents of trace elements. Soft, loose salt crusts are highly vulnerable to wind erosion and transport. These vulnerable crusts, which may contain high contents of potentially toxic trace elements, can travel as atmospheric dust and affect human and ecosystem health at local to regional scales.

  10. Percutaneous quadriceps tendon pie-crusting release of extension contracture of the knee

    National Research Council Canada - National Science Library

    Liu, H X; Wen, H; Hu, Y Z; Yu, H C; Pan, X Y


    ...: percutaneous quadriceps tendon pie-crusting release. Percutaneous pie-crusting release was performed using an 18-gauge needle to puncture the stiff fibrous band of the distal and lateral quadriceps tendon under maximum knee flexion...

  11. Great Lakes Teacher's Guide. (United States)

    Reid, Ron

    The Great Lakes are one of the world's greatest reservoirs of fresh water, the foundation of Ontario's economic development, a primary force in ecological systems, and a base for pleasure and recreation. They are also a magnificent resource for the teachers of Ontario. Study of the Great Lakes can bring to life the factors that shape the ecology…

  12. Marine lakes of Indonesia

    NARCIS (Netherlands)

    Becking, Leontine Elisabeth


    The objective of this thesis was to obtain insight into the processes that play a role in biodiversity patterns of tropical marine species by using marine lakes as a model. Marine lakes are landlocked water bodies that maintain a marine character through narrow submarine connections to the sea. Two

  13. The Great Lakes. (United States)

    Seasons, 1987


    The Great Lakes are one of the world's greatest reserviors of fresh water, the foundation of Ontario's economic development, a primary force in ecological systems, and a base for pleasure and recreation. These lakes and their relationship with people of Canada and the United States can be useful as a subject for teaching the impact of human…

  14. Marine lakes of Indonesia

    NARCIS (Netherlands)

    Becking, Leontine Elisabeth


    The objective of this thesis was to obtain insight into the processes that play a role in biodiversity patterns of tropical marine species by using marine lakes as a model. Marine lakes are landlocked water bodies that maintain a marine character through narrow submarine connections to the sea. Two

  15. Incidence of Bacterial Disease and Yield of Broccoli as Influenced by Different Rain Protectors and Varieties during the Rainy Season in Southern Thailand

    Directory of Open Access Journals (Sweden)

    Karistsapol Nooprom


    Full Text Available This study is mainly focused on evaluating the effects of different rain protectors and broccoli varieties to find out whether rain protector and variety is suitable or not for broccoli production during rainy season. Broccoli was experimented at Prince of Songkla University, Hat Yai, Songkhla, southern Thailand. Study revealed that broccoli growing under plastic sheet and green shade net had lower incidence of soft rot disease (1.62 and 3.75%, respectively than those grown in open field (13.33% while their growing under plastic sheet (1.50% had lower incidence of black rot disease than those grown under green shade net and open field (18.75 and 32.88%, respectively. All broccoli varieties were found to be statistically different in their response towards soft rot and black rot diseases. However, the Top Green had the highest diseases incidence (8.33 and 21.08%, respectively while the Yok Kheo had the lowest diseases incidence (4.62 and 0.00%, respectively. The highest total yield was obtained from the Yok Kheo when those grown under plastic sheet (13.48 t/ha while the Top Green had lowest yield when those grown in open field (3.94 t/ha. Therefore, the most suitable method for broccoli production during rainy season in southern Thailand was to grow under plastic sheet and green shade net by using the three varieties of broccoli.

  16. Comparison of protein and energy supplementation to mineral supplementation on feeding behavior of grazing cattle during the rainy to the dry season transition. (United States)

    Brandão, Rita Kelly Couto; de Carvalho, Gleidson Giordano Pinto; Silva, Robério Rodrigues; Dias, Daniel Lucas Santos; Mendes, Fabrício Bacelar Lima; Lins, Túlio Otávio Jardim D'Almeida; Filho, George Abreu; de Souza, Sinvaldo Oliveira; Barroso, Daniele Soares; de Almeida Rufino, Luana Marta; Tosto, Manuela Silva Libânio


    The aim of this study was to evaluate the effects of protein-energy or mineral supplementation on the ingestive behavior of dairy steers on pasture in the post-weaning phase during the rainy to dry season transition. Twenty-two ½ Holstein-Zebu dairy steers with an average initial body weight of 234 ± 16 kg were distributed into a completely randomized design into two groups: protein-energy supplementation and mineral supplementation offered ad libitum. The steers receiving protein-energy supplementation showed higher (P energy supplementation had longer period in grazing and spent on average more time per period eating at the trough (P  0.05). The supply of protein-energy supplement does not change the feeding behavior, except for an increase in the time spent feeding at the trough. The intake of protein-energy supplement improved the of DM and NDF feed efficiencies in grazing cattle during the rainy to the dry season transition.

  17. Balance characteristics of multivariate background error covariance for rainy and dry seasons and their impact on precipitation forecasts of two rainfall events (United States)

    Chen, Yaodeng; Xia, Xue; Min, Jinzhong; Huang, Xiang-Yu; Rizvi, Syed R. H.


    Atmospheric moisture content or humidity is an important analysis variable of any meteorological data assimilation system. The humidity analysis can be univariate, using humidity background (normally short-range numerical forecasts) and humidity observations. However, more and more data assimilation systems are multivariate, analyzing humidity together with wind, temperature and pressure. Background error covariances, with unbalanced velocity potential and humidity in the multivariate formulation, are generated from weather research and forecasting model forecasts, collected over a summer rainy season and a winter dry season. The unbalanced velocity potential and humidity related correlations are shown to be significantly larger, indicating more important roles unbalanced velocity potential and humidity play, in the rainy season than that in the dry season. Three cycling data assimilation experiments of two rainfall events in the middle and lower reaches of the Yangtze River are carried out. The experiments differ in the formulation of the background error covariances. Results indicate that only including unbalanced velocity potential in the multivariate background error covariance improves wind analyses, but has little impact on temperature and humidity analyses. In contrast, further including humidity in the multivariate background error covariance although has a slight negative effect on wind analyses and a neutral effect on temperature analyses, but significantly improves humidity analyses, leading to precipitation forecasts more consistent with China Hourly Merged Precipitation Analysis.

  18. Lake trout in northern Lake Huron spawn on submerged drumlins (United States)

    Riley, Stephen C.; Binder, Thomas; Wattrus, Nigel J.; Faust, Matthew D.; Janssen, John; Menzies, John; Marsden, J. Ellen; Ebener, Mark P.; Bronte, Charles R.; He, Ji X.; Tucker, Taaja R.; Hansen, Michael J.; Thompson, Henry T.; Muir, Andrew M.; Krueger, Charles C.


    Recent observations of spawning lake trout Salvelinus namaycush near Drummond Island in northern Lake Huron indicate that lake trout use drumlins, landforms created in subglacial environments by the action of ice sheets, as a primary spawning habitat. From these observations, we generated a hypothesis that may in part explain locations chosen by lake trout for spawning. Most salmonines spawn in streams where they rely on streamflows to sort and clean sediments to create good spawning habitat. Flows sufficient to sort larger sediment sizes are generally lacking in lakes, but some glacial bedforms contain large pockets of sorted sediments that can provide the interstitial spaces necessary for lake trout egg incubation, particularly if these bedforms are situated such that lake currents can penetrate these sediments. We hypothesize that sediment inclusions from glacial scavenging and sediment sorting that occurred during the creation of bedforms such as drumlins, end moraines, and eskers create suitable conditions for lake trout egg incubation, particularly where these bedforms interact with lake currents to remove fine sediments. Further, these bedforms may provide high-quality lake trout spawning habitat at many locations in the Great Lakes and may be especially important along the southern edge of the range of the species. A better understanding of the role of glacially-derived bedforms in the creation of lake trout spawning habitat may help develop powerful predictors of lake trout spawning locations, provide insight into the evolution of unique spawning behaviors by lake trout, and aid in lake trout restoration in the Great Lakes.

  19. Influence of Earth crust composition on continental collision style in Precambrian conditions: Results of supercomputer modelling (United States)

    Zavyalov, Sergey; Zakharov, Vladimir


    A number of issues concerning Precambrian geodynamics still remain unsolved because of uncertainity of many physical (thermal regime, lithosphere thickness, crust thickness, etc.) and chemical (mantle composition, crust composition) parameters, which differed considerably comparing to the present day values. In this work, we show results of numerical supercomputations based on petrological and thermomechanical 2D model, which simulates the process of collision between two continental plates, each 80-160 km thick, with various convergence rates ranging from 5 to 15 cm/year. In the model, the upper mantle temperature is 150-200 ⁰C higher than the modern value, while the continental crust radiogenic heat production is higher than the present value by the factor of 1.5. These settings correspond to Archean conditions. The present study investigates the dependence of collision style on various continental crust parameters, especially on crust composition. The 3 following archetypal settings of continental crust composition are examined: 1) completely felsic continental crust; 2) basic lower crust and felsic upper crust; 3) basic upper crust and felsic lower crust (hereinafter referred to as inverted crust). Modeling results show that collision with completely felsic crust is unlikely. In the case of basic lower crust, a continental subduction and subsequent continental rocks exhumation can take place. Therefore, formation of ultra-high pressure metamorphic rocks is possible. Continental subduction also occurs in the case of inverted continental crust. However, in the latter case, the exhumation of felsic rocks is blocked by upper basic layer and their subsequent interaction depends on their volume ratio. Thus, if the total inverted crust thickness is about 15 km and the thicknesses of the two layers are equal, felsic rocks cannot be exhumed. If the total thickness is 30 to 40 km and that of the felsic layer is 20 to 25 km, it breaks through the basic layer leading to

  20. Permanent components of the crust, geoid and ocean depth tides (United States)

    Sun, Wenke; Sjöberg, Lars E.


    The tidal deformation caused by the luni-solar potential includes not only a periodic part, but also a time-independent part, called the permanent tide. How to deal with the tidal correction in gravimetric observations, especially the treatment of the permanent tide, has been discussed for a long time, since some practical and physical problems exist anyhow. A resolution adopted by IAG (1983) was that the permanent tidal attraction of the Moon and the Sun should be eliminated, but the permanent tidal deformation of the Earth be maintained. This is called zero gravity, and the geoid associated with it is the zero geoid. As to the crust deformation, Poutanen et al. (Poutanen, M., Vermeer, M., Mäkinen, J., 1996. The permanent tide in GPS positioning. Journal of Geodesy 70, 499-504.) suggested that co-ordinates should be reduced to the zero crust, i.e. the crust that includes the effect of the permanent tide. This research shows that horizontal components of the permanent earth tides, which are not considered in recent studies, are also important in GPS positioning and geoid determination. Since the tide-generating potential can be expanded into harmonics and divided into two parts (geodetic coefficients and the group of harmonic waves), the permanent earth tides can be easily obtained by multiplying the amplitude of the zero-frequency wavelength by the corresponding geoid geodetic coefficient. Formulas for both elastic and fluid cases are presented. Numerical results for the elastic case show that he vertical permanent crust (zero crust), geoid and ocean depth tides reach -12.0, -5.8 and 6.1 cm at the poles, and 5.9, 2.9 and -3.0 cm at the equator, respectively. The horizontal permanent crust, geoid and ocean depth tide components reach as much as 2.5, 8.7 and 6.3 cm, respectively. According to the solution of IAG (1983), the permanent vertical components are kept in GPS positioning and geoid computation. Thus, it is natural to include the horizontal components

  1. Experimental constraints on phase relations in subducted continental crust (United States)

    Hermann, Jörg


    Synthesis piston cylinder experiments were carried out in the range 2.0-4.5 GPa and 680-1,050 °C to investigate phase relations in subducted continental crust. A model composition (KCMASH) has been used because all major ultrahigh-pressure (UHP) minerals of the whole range of rock types typical for continental crust can be reproduced within this system. The combination of experimental results with phase petrologic constraints permits construction of a UHP petrogenetic grid. The phase relations demonstrate that the most important UHP paragenesis consists of coesite, kyanite, phengite, clinopyroxene, and garnet in subducted continental crust. Below 700 °C talc is stable instead of garnet. As most of these minerals are also stable at much lower pressure and temperature conditions it is thus not easy to recognize UHP metamorphism in subducted crust. A general feature, however, is the absence of feldspars at H2O-saturated conditions. Plagioclase is never stable at UHP conditions, but K-feldspar can occur in H2O-undersaturated rocks. Mineral compositions in the experiments are fully buffered by coexisting phases. The Si content of phengite and biotite increase with increasing pressure. At 4.0 GPa, 780 °C, biotite contains 3.28 Si per formula unit, which is most probably caused by solid solution of biotite with talc. Above 800 °C, the CaAl2SiO6 component in clinopyroxene buffered with kyanite, coesite and a Mg-phase increases with increasing temperature, providing a tool to distinguish between 'cold' and 'hot' eclogites. Up to 10% Ca-eskolaite (Ca0.5[]0.5AlSi2O6) in clinopyroxene has been found at the highest temperature and pressure investigated (>900 °C, 4.5 GPa). Garnet buffered with coesite, kyanite and clinopyroxene displays an increase of grossular component with increasing pressure for a given temperature. Although the investigated system represents a simplification with respect to natural rocks, it helps to constrain general features of subducted continental

  2. Seismic lamination and anisotropy of the Lower Continental Crust (United States)

    Meissner, Rolf; Rabbel, Wolfgang; Kern, Hartmut


    Seismic lamination in the lower crust associated with marked anisotropy has been observed at various locations. Three of these locations were investigated by specially designed experiments in the near vertical and in the wide-angle range, that is the Urach and the Black Forrest area, both belonging to the Moldanubian, a collapsed Variscan terrane in southern Germany, and in the Donbas Basin, a rift inside the East European (Ukrainian) craton. In these three cases, a firm relationship between lower crust seismic lamination and anisotropy is found. There are more cases of lower-crustal lamination and anisotropy, e.g. from the Basin and Range province (western US) and from central Tibet, not revealed by seismic wide-angle measurements, but by teleseismic receiver function studies with a P-S conversion at the Moho. Other cases of lamination and anisotropy are from exhumed lower crustal rocks in Calabria (southern Italy), and Val Sesia and Val Strona (Ivrea area, Northern Italy). We demonstrate that rocks in the lower continental crust, apart from differing in composition, differ from the upper mantle both in terms of seismic lamination (observed in the near-vertical range) and in the type of anisotropy. Compared to upper mantle rocks exhibiting mainly orthorhombic symmetry, the symmetry of the rocks constituting the lower crust is either axial or orthorhombic and basically a result of preferred crystallographic orientation of major minerals (biotite, muscovite, hornblende). We argue that the generation of seismic lamination and anisotropy in the lower crust is a consequence of the same tectonic process, that is, ductile deformation in a warm and low-viscosity lower crust. This process takes place preferably in areas of extension. Heterogeneous rock units are formed that are generally felsic in composition, but that contain intercalations of mafic intrusions. The latter have acted as heat sources and provide the necessary seismic impedance contrasts. The observed

  3. Crustal structure in the Elko-Carlin Region, Nevada, during Eocene gold mineralization: Ruby-East Humboldt metamorphic core complex as a guide to the deep crust (United States)

    Howard, K.A.


    The deep crustal rocks exposed in the Ruby-East Humboldt metamorphic core complex, northeastern Nevada, provide a guide for reconstructing Eocene crustal structure ???50 km to the west near the Carlin trend of gold deposits. The deep crustal rocks, in the footwall of a west-dipping normal-sense shear system, may have underlain the Pin??on and Adobe Ranges about 50 km to the west before Tertiary extension, close to or under part of the Carlin trend. Eocene lakes formed on the hanging wall of the fault system during an early phase of extension and may have been linked to a fluid reservoir for hydrothermal circulation. The magnitude and timing of Paleogene extension remain indistinct, but dikes and tilt axes in the upper crust indicate that spreading was east-west to northwest-southeast, perpendicular to a Paleozoic and Mesozoic orogen that the spreading overprinted. High geothermal gradients associated with Eocene or older crustal thinning may have contributed to hydrothermal circulation in the upper crust. Late Eocene eruptions, upper crustal dike intrusion, and gold mineralization approximately coincided temporally with deep intrusion of Eocene sills of granite and quartz diorite and shallower intrusion of the Harrison Pass pluton into the core-complex rocks. Stacked Mesozoic nappes of metamorphosed Paleozoic and Precambrian rocks in the core complex lay at least 13 to 20 km deep in Eocene time, on the basis of geobarometry studies. In the northern part of the complex, the presently exposed rocks had been even deeper in the late Mesozoic, to >30 km depths, before losing part of their cover by Eocene time. Nappes in the core plunge northward beneath the originally thicker Mesozoic tectonic cover in the north part of the core complex. Mesozoic nappes and tectonic wedging likely occupied the thickened midlevel crustal section between the deep crustal core-complex intrusions and nappes and the overlying upper crust. These structures, as well as the subsequent large

  4. Lake metabolism scales with lake morphometry and catchment conditions

    DEFF Research Database (Denmark)

    Stæhr, Peter A.; Baastrup-Spohr, Lars; Jensen, Kaj Sand;


    We used a comparative data set for 25 lakes in Denmark sampled during summer to explore the influence of lake morphometry, catchment conditions, light availability and nutrient input on lake metabolism. We found that (1) gross primary production (GPP) and community respiration (R) decline with lake...... area, water depth and drainage ratio, and increase with algal biomass (Chl), dissolved organic carbon (DOC) and total phosphorus (TP); (2) all lakes, especially small with less incident light, and forest lakes with high DOC, have negative net ecosystem production (NEP ... decreases with lake area and water depth as a consequence of lower input of nutrients and organic matter per unit water volume; (4) the influence of benthic processes on free water metabolic measures declines with increasing lake size; and (5) with increasing lake size, lake metabolism decreases...

  5. A New Device for Studying Deep-Frying Behavior of Batters and Resulting Crust Properties

    NARCIS (Netherlands)

    Visser, J.E.; Beukelaer, de H.J.; Hamer, R.J.; Vliet, van T.


    The formation and properties of a crust during and after deep frying are difficult to study. Batter pickup (the amount of batter adhering to a product) and core properties affect crust formation and properties of the crust in such way that it is difficult to compare batters of different viscosity or

  6. Composition and origin of ferromanganese crusts from equatorial western Pacific seamounts (United States)

    Wang, Guozhi; Jansa, Luba; Chu, Fengyou; Zou, Can; Sun, Guosheng


    In the equatorial western Pacific, iron-manganese oxyhydroxide crusts (Fe-Mn crusts) and nodules form on basaltic seamounts and on the top of drowned carbonate platform guyots that have been swept free of pelagic sediments. To date, the Fe-Mn crusts have been considered to be almost exclusively of abiotic origin. However, it has recently been suggested that these crusts may be a result of biomineralization. Although the Fe-Mn crust textures in the equatorial western Pacific are similar to those constructed by bacteria and algae, and biomarkers also document the existence of bacteria and algae dispersed within the Fe-Mn crusts, the precipitation, accumulation and distribution of elements, such as Fe, Mn, Ni and Co in Fe-Mn crusts are not controlled by microbial activity. Bacteria and algae are only physically incorporated into the crusts when dead plankton settle on the ocean floor and are trapped on the crust surface. Geochemical evidence suggests a hydrogenous origin of Fe-Mn crusts in the equatorial western Pacific, thus verifying a process for Fe-Mn crusts that involves the precipitation of colloidal phases from seawater followed by extensive scavenging of dissolved trace metals into the mineral phase during crust formation.

  7. A New Device for Studying Deep-Frying Behavior of Batters and Resulting Crust Properties

    NARCIS (Netherlands)

    Visser, J.E.; Beukelaer, de H.J.; Hamer, R.J.; Vliet, van T.


    The formation and properties of a crust during and after deep frying are difficult to study. Batter pickup (the amount of batter adhering to a product) and core properties affect crust formation and properties of the crust in such way that it is difficult to compare batters of different viscosity or

  8. Tillage and farmyard manure efects on crusting and compacting soils at Katumani, Semi-arid Kenya

    NARCIS (Netherlands)

    Biamah, E.K.; Sterk, G.; Stroosnijder, L.


    In semi-arid Kenya, the most dominatn soil types are of limited agricultural productivity due to crusting and compaction. The occurence of soil crusting and compaction is attributed to seasonal rainfall characteristics, physical soil properties and bad tillage practices. Soil crusting and compaction

  9. Magnetic and gravity studies of Mono Lake, east-central, California (United States)

    Athens, Noah D.; Ponce, David A.; Jayko, Angela S.; Miller, Matt; McEvoy, Bobby; Marcaida, Mae; Mangan, Margaret T.; Wilkinson, Stuart K.; McClain, James S.; Chuchel, Bruce A.; Denton, Kevin M.


    From August 26 to September 5, 2011, the U.S. Geological Survey (USGS) collected more than 600 line-kilometers of shipborne magnetic data on Mono Lake, 20 line-kilometers of ground magnetic data on Paoha Island, 50 gravity stations on Paoha and Negit Islands, and 28 rock samples on Paoha and Negit Islands, in east-central California. Magnetic and gravity investigations were undertaken in Mono Lake to study regional crustal structures and to aid in understanding the geologic framework, in particular regarding potential geothermal resources and volcanic hazards throughout Mono Basin. Furthermore, shipborne magnetic data illuminate local structures in the upper crust beneath Mono Lake where geologic exposure is absent. Magnetic and gravity methods, which sense contrasting physical properties of the subsurface, are ideal for studying Mono Lake. Exposed rock units surrounding Mono Lake consist mainly of Quaternary alluvium, lacustrine sediment, aeolian deposits, basalt, and Paleozoic granitic and metasedimentary rocks (Bailey, 1989). At Black Point, on the northwest shore of Mono Lake, there is a mafic cinder cone that was produced by a subaqueous eruption around 13.3 ka. Within Mono Lake there are several small dacite cinder cones and flows, forming Negit Island and part of Paoha Island, which also host deposits of Quaternary lacustrine sediments. The typical density and magnetic properties of young volcanic rocks contrast with those of the lacustrine sediment, enabling us to map their subsurface extent.

  10. Giant pulsar glitches and the inertia of neutron star crusts (United States)

    Delsate, T.; Chamel, N.; Gürlebeck, N.; Fantina, A. F.; Pearson, J. M.; Ducoin, C.


    Giant pulsar frequency glitches as detected in the emblematic Vela pulsar have long been thought to be the manifestation of a neutron superfluid permeating the inner crust of a neutron star. However, this superfluid has been recently found to be entrained by the crust, and as a consequence it does not carry enough angular momentum to explain giant glitches. The extent to which pulsar-timing observations can be reconciled with the standard vortex-mediated glitch theory is studied considering the current uncertainties on dense-matter properties. To this end, the crustal moment of inertia of glitching pulsars is calculated employing a series of different unified dense-matter equations of state.

  11. Symmetry energy, unstable nuclei, and neutron star crusts

    CERN Document Server

    Iida, Kei


    Phenomenological approach to inhomogeneous nuclear matter is useful to describe fundamental properties of atomic nuclei and neutron star crusts in terms of the equation of state of uniform nuclear matter. We review a series of researches that we have developed by following this approach. We start with more than 200 equations of state that are consistent with empirical masses and charge radii of stable nuclei and then apply them to describe matter radii and masses of unstable nuclei, proton elastic scattering and total reaction cross sections off unstable nuclei, and nuclei in neutron star crusts including nuclear pasta. We finally discuss the possibility of constraining the density dependence of the symmetry energy from experiments on unstable nuclei and even observations of quasi-periodic oscillations in giant flares of soft gamma-ray repeaters.

  12. Symmetry energy, unstable nuclei and neutron star crusts

    Energy Technology Data Exchange (ETDEWEB)

    Iida, Kei [Kochi University, Department of Natural Science, Kochi (Japan); RIKEN Nishina Center, Saitama (Japan); Oyamatsu, Kazuhiro [RIKEN Nishina Center, Saitama (Japan); Aichi Shukutoku University, Department of Human Informatics, Aichi (Japan)


    The phenomenological approach to inhomogeneous nuclear matter is useful to describe fundamental properties of atomic nuclei and neutron star crusts in terms of the equation of state of uniform nuclear matter. We review a series of researches that we have developed by following this approach. We start with more than 200 equations of state that are consistent with empirical masses and charge radii of stable nuclei and then apply them to describe matter radii and masses of unstable nuclei, proton elastic scattering and total reaction cross sections off unstable nuclei, and nuclei in neutron star crusts including nuclear pasta. We finally discuss the possibility of constraining the density dependence of the symmetry energy from experiments on unstable nuclei and even observations of quasi-periodic oscillations in giant flares of soft gamma-ray repeaters. (orig.)

  13. Geoelectromagnetic investigation of the earth’s crust and mantle

    CERN Document Server

    Rokityansky, Igor I


    Electrical conductivity is a parameter which characterizes composition and physical state of the Earth's interior. Studies of the state equations of solids at high temperature and pressure indicate that there is a close relation be­ tween the electrical conductivity of rocks and temperature. Therefore, measurements of deep conductivity can provide knowledge of the present state and temperature of the Earth's crust and upper mantle matter. Infor­ mation about the temperature of the Earth's interior in the remote past is derived from heat flow data. Experimental investigation of water-containing rocks has revealed a pronounced increase of electrical conductivity in the temperature range D from 500 to 700 DC which may be attributed to the beginning of fractional melting. Hence, anomalies of electrical conductivity may be helpful in identitying zones of melting and dehydration. The studies of these zones are perspective in the scientific research of the mobile areas of the Earth's crust and upper mantle where t...

  14. Spin diffusive modes and thermal transport in neutron star crusts

    CERN Document Server

    Sedrakian, Armen


    In this contribution we first review a method for obtaining the collective modes of pair-correlated neutron matter as found in a neutron star inner crust. We discuss two classes of modes corresponding to density and spin perturbations with energy spectra $\\omega = \\omega_0 + \\alpha q^2$, where $\\omega_0 = 2\\Delta$ is the threshold frequency and $\\Delta$ is the gap in the neutron fluid spectrum. For characteristic values of Landau parameters in neutron star crusts the exitonic density modes have $\\alpha 0$ and they exist above $\\omega_0$ which implies that these modes are damped. As an application of these findings we compute the thermal conductivity due to spin diffusive modes and show that it scales as $T^{1/2} \\exp(-2\\omega_0/T)$ in the case where their two-by-two scattering cross-section is weakly dependent on temperature.

  15. Crusted (Norwegian) scabies following systemic and topical corticosteroid therapy. (United States)

    Binić, Ivana; Janković, Aleksandar; Jovanović, Dragan; Ljubenović, Milanka


    It is a case study of a 62-yr-old female with crusted (Norwegian) scabies, which appeared during her treatment with systemic and topical corticosteroid therapy, under the diagnosis of erythroderma. In the same time, the patient had been suffered from hypothyoidism, and her skin changes were misdiagnosed, because it was thought that they are associated with her endocrine disorder. Suddenly, beside the erythema, her skin became hyperkeratotic, with widespread scaling over the trunk and limbs, and crusted lesions appeared on her scalp and ears. The microscopic examination of the skin scales with potassium hydroxide demonstrated numerous scabies mites and eggs. Repeated topical treatments with lindan, benzoyl benzoat and 10% precipitated sulphur ointment led to the complete resolution of her skin condition.

  16. The outer crust of non-accreting cold neutron stars

    CERN Document Server

    Ruster, S B; Schaffner-Bielich, J; Ruster, Stefan B.; Hempel, Matthias; Schaffner-Bielich, Jurgen


    The properties of the outer crust of non-accreting cold neutron stars are studied by using modern nuclear data and theoretical mass tables updating in particular the classic work of Baym, Pethick and Sutherland. Experimental data from the atomic mass table from Audi, Wapstra, and Thibault of 2003 is used and a thorough comparison of many modern theoretical nuclear models, relativistic and non-relativistic ones, is performed for the first time. In addition, the influences of pairing and deformation are investigated. State-of-the-art theoretical nuclear mass tables are compared in order to check their differences concerning the neutron dripline, magic neutron numbers, the equation of state, and the sequence of neutron-rich nuclei up to the dripline in the outer crust of non-accreting cold neutron stars.

  17. Obstacle performance of cobalt-enriching crust wheeled mining vehicle

    Institute of Scientific and Technical Information of China (English)

    HUANG Zhong-hua; LIU Shao-jun; XIE Ya


    A cobalt-enriching crust mining vehicle with four independent driven wheels was proposed. The influence of center-of-gravity position of mining vehicle on obstacle performance was studied. The results show that the mining vehicle has optimal obstacle performance with center-of-gravity position in the middle of suspension. A virtual prototype based on ADAMS software was built and its obstacle performance was simulated. Simulation results show that the mining vehicle with four independent driven wheels has excellent obstacle performance, the maximum climbing capacity is no less than 30°, the maximal ditch width and shoulder height are no less than wheel radius ofmining vehicle. Thus wheeled mining vehicle is feasible for cobalt-enriching crust commercial mining.

  18. Neutrino oscillations in the presence of the crust magnetization

    Energy Technology Data Exchange (ETDEWEB)

    Syska, J., E-mail: [Department of Field Theory and Particle Physics, Institute of Physics, University of Silesia, Katowice (Poland)


    It is noted that the crustal magnetic spectrum exhibits the signal from the partly correlated domain dipoles on the space-scale up to approximately 500 km. This suggests the nonzero correlation among the dynamical variables of the ferromagnetic magnetization phenomenon on the small domain scale inside the earth's crust also. Therefore the influence of the mean of the zero component of the polarization on the CP matter-induced violation indexes is discussed.

  19. Synthetic petroleum stability under thermobaric conditions of the Earth crust (United States)

    Serovaiskii, Aleksandr; Kolesnikov, Anton; Kutcherov, Vladimir


    Nowadays there are several dozens of large crude oil deposits at the depth more than 10 km (Kutcherov and Krayushkin, 2010). The existence of such deep oil fields at the depth exceeding conventional "oil window" could be explained by the migration of the deep fluid from the asthenosphere. This fluid migrates up to the surface and forms oil and gas deposits in different kind of rocks in the on various depths of the Earth's crust. Crude oil consists of a great numbers of different hydrocarbons. Its precise molecular composition is impossible to investigate nowadays. Instead of the natural hydrocarbons mixture synthetic petroleum with simpler composition was used in the experiments. The synthetic petroleum stability was investigated at the Earth crust thermobaric conditions corresponding to the depth down to 50 km. The experiments were carried out in Diamond Anvil Cells (DAC) with the internal resistive heating. Raman spectroscopy was used to analyse the petroleum composition. The analysis of the sample was made in situ during the experiment. Ruby and Sm:YAG Raman shifts were the controllers of the temperature and pressure inside the sample (Trots et al., 2012; Mao et al., 1986). Three series of the experiments were carried out at 320°C and 0.7GPa, 420°C and 1.2GPa, 450°C and 1.4GPa. After the experiment the Raman spectra of the sample was compared to the reference spectra of the petroleum before the experiment. The comparison showed no changes in the sample's composition after the experiment. Obtained data may explain the existence of deep oil fields located deeper than the "oil window". It can broaden the knowledge about the existing range of depths for the crude oil and natural gas deposits in the Earth crust. The evidence of the petroleum existence in the Earth low crust may support the existence of unconventional, deep abyssal hydrocarbons source.

  20. Continental crust under the southern Porcupine Seabight west of Ireland (United States)

    Makris, J.; Egloff, R.; Jacob, A. W. B.; Mohr, P.; Murphy, T.; Ryan, P.


    Two new seismic refraction/wide-angle reflection profiles demonstrate that the crust beneath the southern Porcupine Seabight, out to water depths in excess of 4000 m, is of continental type. They also reveal the rifted margin of the Porcupine basin on its eastern side. Crustal thickness under the Seabight, inclusive of sediments which are up to 6 km thick, decreases from 23 km in the east to about 10 km at a sharp continent-ocean transition in the west.

  1. The complex isostatic equilibration of Australia's deep crust. (United States)

    Aitken, Alan; Gross, Lutz; Altinay, Cihan


    A recent study, using a new finite-element based gravity inversion method has modelled in high-resolution the density and pressure fields for the Australian continent. Here we analyse the pressure results to consider how Australia's lower-crust and Moho contribute to the isostatic equilibration of topography and crustal masses. We find that the situation is more complex than the commonly applied model of isostatic compensation through crustal thickness variations. Key differences include low pressure-variability at ca. 30-35 km, suggesting that the thickness of the felsic-intermediate crust equilibrates most of the upper-crustal loads; increasing pressure-variability between 30-50 km, suggesting that positively buoyant deep-crustal roots generate disequilibrium. These large roots have previously been inferred to represent mafic underplates. Pressure-variability in the uppermost lithospheric mantle reduces to a minimum at ~125 km depth, suggesting that these loads are compensated by dense mantle at ~100 km depth, rather than by crustal loads or topography. This raises the notion that Australia's lithosphere is isostatically compensated at two levels: Crustal compensation involving topography and the felsic to intermediate crust; and deep-lithosphere compensation involving the mafic lower crust and lithospheric mantle. Rather than its traditional role of compensating for crustal masses, the Moho in this case appears to be a source of isostatic disequilibrium, acting in a separate cell with lithospheric mantle density sources. These results imply that, for cratonised continents like Australia, the notion of crustal isostasy is a poor descriptor of the system.

  2. Analysis of the black crust on Saint Michael's Church (United States)

    Popister, I.; Zeman, A.


    The goal of the present study is to characterize the black crust on the main stone used at Saint Michael's Church in Cluj-Napoca, Romania. The gases in the atmosphere, along with natural and artificial pollutants can cause damage the integrity of the stone when it comes in contact with the stone's chemistry. In order to explain the mechanism of stone decay due to black crust it is necessary to know what "weathering" means, so it must be seen as a complex process that consists of: type of material, the environment in which the material is located, and the amount of time required for the process to take place. Each material has particular properties, due to its composition and genesis. When it comes in contact with the acidity of the "acid rain" (caused by sulphur, nitrogen oxides and carbon dioxide), the rain penetrates into the pore structure, corroding it and "allowing" the atmospheric particles to penetrate the stone. St. Michael's Church is one of the oldest Gothic architectural monuments in Cluj, Romania, being built predominantly from Cenozoic (Upper Eocene) limestone, locally known as the Cluj Limestone. The main quarry was in Baciu, near Cluj. The samples that were collected from the Saint Michael's Church were characterized by means of: optical microscope, Scattering Electronic Microscope, thin sections, EDS The samples that were collected from the Saint Michael's Church went through a series of tests: optical microscope, Scattering Electronic Microscope, thin sections, EDX, and cross-section. The optical microscope analysis of the thin sections revealed that the black crust layer is approximately 0.01mm, and in the sample there are perfectly shaped ooides, which is characteristic to this type of limestone. The SEM analysis shows a resedimentation layer on the surface of the black crust, which occurred probably due to the effect of acid rain. Further information regarding the results of the test will be presented on the poster.

  3. Crusted (Norwegian) Scabies Following Systemic and Topical Corticosteroid Therapy


    Binić, Ivana; Janković, Aleksandar; Jovanović, Dragan; Ljubenović, Milanka


    It is a case study of a 62-yr-old female with crusted (Norwegian) scabies, which appeared during her treatment with systemic and topical corticosteroid therapy, under the diagnosis of erythroderma. In the same time, the patient had been suffered from hypothyoidism, and her skin changes were misdiagnosed, because it was thought that they are associated with her endocrine disorder. Suddenly, beside the erythema, her skin became hyperkeratotic, with widespread scaling over the trunk and limbs, a...

  4. The Seismic Structure of the Crust of Madagascar (United States)

    Wysession, M. E.; Andriampenomanana Ny Ony, F. S. T.; Tsiriandrimanana, R.; Pratt, M. J.; Aleqabi, G. I.; Wiens, D. A.; Nyblade, A.; Shore, P.; Rambolamanana, G.; Tilmann, F. J.


    The structure of Madagascar's crust is determined using both body wave receiver functions as well as an analysis of surface waves using ambient-noise and two-plane-wave earthquake surface waves analyses. The primary data used are from the 2011-2013 MACOMO (Madagascar, the Comoros, and Mozambique) broadband seismic array from the PASSCAL program of IRIS (Incorporated Research Institutions for Seismology), funded by the NSF. Additional data came from the RHUM-RUM project (led by G. Barruol and K. Sigloch), the Madagascar Seismic Profile (led by F. Tilmann), and the GSN. The crustal structure of Madagascar, which had previously only been inferred from a gravity survey assuming isostasy, shows a strong correlation with its tectonic history. Crustal thicknesses are greatest, reaching 45 km, along the spine of Madagascar's mountains, which run north-south across the island. Crustal thicknesses thin to the east and west, which are both regions of tectonic separation, however, with very different results. Extensive crustal thinning occurred along the western coasts of Madagascar when the island rifted away from mainland Africa beginning 160 Ma ago. The crust is as thin as 20 km here, but the thickness of basin sediments is as great as 9 km, with the crystalline basement continental crust thinning to 12 km at its thinnest. Along the east coast, the crustal thickness is within the 33-38 km range, but it is thickest in the two places where mesoarchaean crust was rifted off from the Indian subcontinent when it broke away from Madagascar. Surface wave studies show that velocities beneath Madagascar are generally slow, when compared to global models such as AK135. This appears to be due to the occurrence of Cenozoic intraplate volcanism in three regions of Madagascar (north, central, and southwest), each of which has strong underlying seismic low-velocity anomalies in the lithospheric mantle and asthenosphere.

  5. Scales and effects of fluid flow in the upper crust. (United States)

    Cathles, L M


    Two of the most important agents of geological change, solar energy and internal heat from the mantle, meet and battle for dominance in propelling aqueous and related fluids in the earth's upper crust. Which prevails and how they interact are subjects of active research. Recent work has demonstrated that both agents can propel fluids over nearly continental-scale distances in a fashion that influences a host of important geological processes and leaves a record in chemical alteration, mineral deposits, and hydrocarbon resources.

  6. The continental record and the generation of continental crust


    Cawood, Peter Anthony; Hawkesworth, Chris; Dhuime, Bruno Philippe Marcel


    Continental crust is the archive of Earth history. The spatial and temporal distribution of Earth's record of rock units and events is heterogeneous; for example, ages of igneous crystallization, metamorphism, continental margins, mineralization, and seawater and atmospheric proxies are distributed about a series of peaks and troughs. This distribution reflects the different preservation potential of rocks generated in different tectonic settings, rather than fundamental pulses of activity, a...

  7. Biological soil crusts as an integral component of desert environments (United States)

    Belnap, Jayne; Weber, Bettina


    The biology and ecology of biological soil crusts, a soil surface community of mosses, lichens, cyanobacteria, green algae, fungi, and bacteria, have only recently been a topic of research. Most efforts began in the western U.S. (Cameron, Harper, Rushforth, and St. Clair), Australia (Rogers), and Israel (Friedmann, Evenari, and Lange) in the late 1960s and 1970s (e.g., Friedmann et al. 1967; Evenari 1985reviewed in Harper and Marble 1988). However, these groups worked independently of each other and, in fact, were often not aware of each other’s work. In addition, biological soil crust communities were seen as more a novelty than a critical component of dryland ecosystems. Since then, researchers have investigated many different aspects of these communities and have shown that although small to microscopic, biological soil crusts are critical in many ecological processes of deserts. They often cover most of desert soil surfaces and substantially mediate inputs and outputs from desert soils (Belnap et al. 2003). They can be a large source of biodiversity for deserts, as they can contain more species than the surrounding vascular plant community (Rosentreter 1986). These communities are important in reducing soil erosion and increasing soil fertility through the capture of dust and the fixation of atmospheric nitrogen and carbon into forms available to other life forms (Elbert et al. 2012). Because of their many effects on soil characteristics, such as external and internal morphological characteristics, aggregate stability, soil moisture, and permeability, they also affect seed germination and establishment and local hydrological cycles. Covering up to 70% of the surface area in many arid and semi-arid regions around the world (Belnap and Lange 2003), biological soil crusts are a key component within desert environments.

  8. Q-tubes, Q-rings and Q-crusts

    CERN Document Server

    Sakai, Nobuyuki; Nakao, Ken-ichi


    We re-analyse scalar field theories which allow Q-ball solutions. We find new types of non-topological solitons: tube-shaped in SO(2) models, ring-shaped in SO(3) models, and crust-shaped in SO(3)\\times U(1) models. Although their field configurations are analogous to cosmic global strings or global monopoles, their gravitational mass are finite without gauge fields.

  9. Granulites: Melts and fluids in the deep crust (United States)

    Valley, John W.


    Known examples of granulite facies metamorphism span at least 3.5 by. of Earth history. Mineralogic geobarometry indicates that such metamorphism has occurred in the deep crust, typically at 20 to 30 km (6 to 9 kbar). Geothermometry indicates that peak T = 700 to 900 C and therefore that T was elevated by at least 200 C over an anorgenic geotherm of 15 to 20 C/km. Commonly invoked sources of heat include rising magmas, radioactive decay insulated by continent/continent collision, mantle volatiles, or crustal thinning. Present day crustal thicknesses are normal beneath exposed granulite terranes and the common absence of evidence for post-metamorphic underplating suggests synmetamorphic thicknesses of 60 to 80 km. Thus granulites form in tectonically active regions of thickened crust and elevated geotherm. Xenolith suites suggest that granulite facies mineralogy persists in the deepest crust after tectonism in spite of declining temperature to greenschist/amphibolite facies conditions. The relative proportions of granulite terranes that are formed by Adirondack-type metamorphism dominantly magmatic/fluid-absent), India-type metamorphism (CO2 saturated), or some combination of 1 and 2 remains an important tectonic question.

  10. Fluid Release and the Deformation of Subducting Crust (United States)

    Maunder, Benjamin; van Hunen, Jeroen; Magni, Valentina; Bouilhol, Pierre


    It is known that slab dehydration is crucial in subduction dynamics and for the formation of arc-magmatism. Previous studies of this process have constrained this intake and subsequent release of fluids into the mantle wedge by considering the stability hydrous phases within the slab. Other, more dynamical effects of this hydration state and partial melting have also been suggested, such as the possibility of "cold plumes", crustal delamination, and subduction channel return flow. These processes have been inferred to play a role in the generation of continental crust over time through accumulation and melting beneath the overriding plate. Water content and melt fraction have a strong control on the rheology of the system. Therefore we investigate the effect of these parameters on the dynamics of a subducting slab, with the aim to establish the physical bounds on the delamination process. To do this we use a coupled geodynamical-petrological model that tracks dehydration and melting reactions in order to factor in the rheological effect of metamorphism and magmatism on slab and mantle wedge dynamics. We focus primarily on the strength of the subducting crust and the possibility of delamination. We then extend this investigation by considering whether early earth crust formation could have been the result of such a processes by looking at a hypothetical Archean setting.

  11. Pinned vortex hopping in a neutron star crust

    CERN Document Server

    Haskell, Brynmor


    The motion of superfluid vortices in a neutron star crust is at the heart of most theories of pulsar glitches. Pinning of vortices to ions can decouple the superfluid from the crust and create a reservoir of angular momentum. Sudden large scale unpinning can lead to an observable glitch. In this paper we investigate the scattering of a free vortex off a pinning potential and calculate its mean free path, in order to assess whether unpinned vortices can skip multiple pinning sites and come close enough to their neighbours to trigger avalanches, or whether they simply hop from one pinning site to another giving rise to a more gradual creep. We find that there is a significant range of parameter space in which avalanches can be triggered, thus supporting the hypothesis that they may lie at the origin of pulsar glitches. For realistic values of the pinning force and superfluid drag parameters we find that avalanches are more likely in the higher density regions of the crust where pinning is stronger. Physical dif...

  12. Primary carbonatite melt from deeply subducted oceanic crust

    Energy Technology Data Exchange (ETDEWEB)

    Walter, M.J.; Bulanova, G.P.; Armstrong, L.S.; Keshav, S.; Blundy, J.D.; Gudfinnesson, G.; Lord, O.T.; Lennie, A.R.; Clark, S.M.; Smith, C.B.; Gobbo, L.


    Partial melting in the Earth's mantle plays an important part in generating the geochemical and isotopic diversity observed in volcanic rocks at the surface. Identifying the composition of these primary melts in the mantle is crucial for establishing links between mantle geochemical 'reservoirs' and fundamental geodynamic processes. Mineral inclusions in natural diamonds have provided a unique window into such deep mantle processes. Here they provide exper8imental and geochemical evidence that silicate mineral inclusions in diamonds from Juina, Brazil, crystallized from primary and evolved carbonatite melts in the mantle transition zone and deep upper mantle. The incompatible trace element abundances calculated for a melt coexisting with a calcium-titanium-silicate perovskite inclusion indicate deep melting of carbonated oceanic crust, probably at transition-zone depths. Further to perovskite, calcic-majorite garnet inclusions record crystallization in the deep upper mantle from an evolved melt that closely resembles estimates of primitive carbonatite on the basis of volcanic rocks. Small-degree melts of subducted crust can be viewed as agents of chemical mass-transfer in the upper mantle and transition zone, leaving a chemical imprint of ocean crust that can possibly endure for billions of years.

  13. Reflection attributes of paragneiss in the upper crust

    Institute of Scientific and Technical Information of China (English)


    The integrated study of the geological and seismic reflection data from the drilling area of CCSD has discovered that the density and the P-wave velocity of orthogneiss are almost the same as that of the paragneiss in the area; but the orthogneiss and the paragneiss hold different reflection attributes. The strong seismic reflector packes coinciding spatially with the paragneiss suites have implied that the paragneiss buried in the metamorphic crust itself can cause bone-like seismic reflector sets. The P-wave velocity of paragneiss shows little apparent difference with that of the orthogneiss; but its transverse wave velocity is lower, with the Vp/Vs ratios being high. The paragneiss has partially inherited the layering structures and textures of the protolithe of sedimentary rocks, hence shows strong heterogeneity and anisotropy, that is why the paragneiss are able to produce the bone-like reflectors in the upper crust. The low transverse wave velocity of paragneiss often means weak shear resistance, which will further cause cracks or fractures in the rock, consequentially increase its porosity and permeability during tectonic movements, and form the paragneiss reservoirs of low-permeability zones for gases uplifted from the deeper crust. Because the paragneiss in the crustal metamorphic basement can cause the seismic reflectors, seismic reflection sections are able to provide information about the paragneiss under certain prerequisites.

  14. Radiogenic heat production, thermal regime and evolution of continental crust (United States)

    Mareschal, Jean-Claude; Jaupart, Claude


    Heat flow and heat production data complement seismic information and provide strong constraints on crustal composition, thickness and evolution. They have helped understand the nature of the Mohorovicic discontinuity and the variations in seismic velocities below the Moho. Notably, heat flow studies have delineated the vertical distribution of heat producing elements throughout the crust and in the upper most mantle lithosphere. Analysis of global data sets on heat flow and crustal thickness demonstrate that there is no correlation between these two variables. This is due to the large spatial variations in crustal composition and heat production that exist within a single geological province. For a given crustal thickness, the Moho temperature varies within a wide range (≈ 300 K) depending on surface heat flux and crustal heat production. Thus one cannot use generic models based on a “type” crustal column to calculate crustal geotherms. In stable regions, lower crustal temperatures depend on the amount and vertical distribution of heat producing elements in the crust. These temperatures determine the conditions of crustal stability and impose a limit on the maximum thickness of a stabilized crust.

  15. Attenuation of S wave in the crust of Ordos massif

    Institute of Scientific and Technical Information of China (English)

    LIU Hong-gui; CHUO Yong-qing; CHEN Shu-qing; JIN Chun-hua


    We presented attenuation characteristics of S waves in the crust of Ordos massif. Using 487 pieces of digital oscillograms of 19 seismic events recorded by 32 seismologic stations located on Ordos massif and its surroundings, we have calculated the parameter of three-segment geometric attenuation and give the relation of inelastic attenuation Q value with frequency in the crust of Ordos massif, site responses of 32 stations, and source parameters of 19 events by the genetic algorithm. The results indicate that Q value (at 1 Hz) of S-wave in the crust of Ordos massif is much larger than that in the geologically active tectonic region. The site responses of the 32 stations in the high-frequency section do not show clear amplification effect except one or two stations, while in the low-frequency section, there is difference among the stations. The logarithmic value of seismic moment and the magnitude ML of 19 seismic events has a very good linear relationship.

  16. Investigation of Biological Soil Crusts Metabolic Webs Using Exometabolomic Analysis (United States)

    Northen, T.; Karaoz, U.; Jenkins, S.; Lau, R.; Bowen, B.; Cadillo-Quiroz, H.; Garcia-Pichel, F.; Brodie, E.; Richard, B.


    Desert biological soil crusts are simple cyanobacteria-dominated surface soil microbial communities found in areas with infrequent wetting, often extreme temperatures, low coverage of vascular plants and constitute the world's largest biofilm. They exist for extended periods in a desiccated dormant state, yet rapidly re-boot metabolism within minutes of wetting. These soil microbial communities are highly dependent on filamentous cyanobacteria such as Microcoleus vaginatusto stabilize the soil and to act as primary producers for the community through the release carbon sources to feed a diversity of heterotrophs. Exometabolomic analysis was performed using liquid chromatography coupled to tandem mass spectrometry on biological soil crust pore water and spent media of key soil bacterial isolates. Comparison of spent vs. fresh media was used to determine uptake or release of metabolites by specific microbes. To link pore water experiments with isolate studies, metabolite extracts of authentic soil were used as supplements for isolate exometabolomic profiling. Our soil metabolomics methods detected hundreds of metabolites from soils including may novel compounds. Only a small set of which being targeted by all isolates. Beyond these few metabolites, the individual bacteria examined showed specialization towards specific metabolites. Surprisingly, many of the most abundant oligosaccharides and other metabolites were ignored by these isolates. The observed specialization of biological soil crust bacteria may play a significant role in determining community structure.

  17. Potentially exploitable supercritical geothermal resources in the ductile crust (United States)

    Watanabe, Noriaki; Numakura, Tatsuya; Sakaguchi, Kiyotoshi; Saishu, Hanae; Okamoto, Atsushi; Ingebritsen, Steven E.; Tsuchiya, Noriyoshi


    The hypothesis that the brittle–ductile transition (BDT) drastically reduces permeability implies that potentially exploitable geothermal resources (permeability >10−16 m2) consisting of supercritical water could occur only in rocks with unusually high transition temperatures such as basalt. However, tensile fracturing is possible even in ductile rocks, and some permeability–depth relations proposed for the continental crust show no drastic permeability reduction at the BDT. Here we present experimental results suggesting that the BDT is not the first-order control on rock permeability, and that potentially exploitable resources may occur in rocks with much lower BDT temperatures, such as the granitic rocks that comprise the bulk of the continental crust. We find that permeability behaviour for fractured granite samples at 350–500 °C under effective confining stress is characterized by a transition from a weakly stress-dependent and reversible behaviour to a strongly stress-dependent and irreversible behaviour at a specific, temperature-dependent effective confining stress level. This transition is induced by onset of plastic normal deformation of the fracture surface (elastic–plastic transition) and, importantly, causes no ‘jump’ in the permeability. Empirical equations for this permeability behaviour suggest that potentially exploitable resources exceeding 450 °C may form at depths of 2–6 km even in the nominally ductile crust.

  18. Potentially exploitable supercritical geothermal resources in the ductile crust (United States)

    Watanabe, Noriaki; Numakura, Tatsuya; Sakaguchi, Kiyotoshi; Saishu, Hanae; Okamoto, Atsushi; Ingebritsen, Steven E.; Tsuchiya, Noriyoshi


    The hypothesis that the brittle-ductile transition (BDT) drastically reduces permeability implies that potentially exploitable geothermal resources (permeability >10-16 m2) consisting of supercritical water could occur only in rocks with unusually high transition temperatures such as basalt. However, tensile fracturing is possible even in ductile rocks, and some permeability-depth relations proposed for the continental crust show no drastic permeability reduction at the BDT. Here we present experimental results suggesting that the BDT is not the first-order control on rock permeability, and that potentially exploitable resources may occur in rocks with much lower BDT temperatures, such as the granitic rocks that comprise the bulk of the continental crust. We find that permeability behaviour for fractured granite samples at 350-500 °C under effective confining stress is characterized by a transition from a weakly stress-dependent and reversible behaviour to a strongly stress-dependent and irreversible behaviour at a specific, temperature-dependent effective confining stress level. This transition is induced by onset of plastic normal deformation of the fracture surface (elastic-plastic transition) and, importantly, causes no `jump' in the permeability. Empirical equations for this permeability behaviour suggest that potentially exploitable resources exceeding 450 °C may form at depths of 2-6 km even in the nominally ductile crust.

  19. Formation and evolution of Precambrian continental crust in South China

    Institute of Scientific and Technical Information of China (English)

    ZHENG YongFei; ZHANG ShaoBing


    The occurrence of zircons with U-Pb ages of ~3.8 Ga and Hf model ages of ~4.0 Ga in South China suggests the existence of the Hadean crustal remnants in South China. Furthermore, a detrital zircon with a U-Pb age as old as 4.1 Ga has been found in Tibet. This is the oldest zircon so far reported in China. These results imply that continental crust was more widespread than previously thought in the late Hadean, but its majority was efficiently reworked into Archean continental crust. On the basis of available zircon U-Pb age and Hf isotope data, it appears that the growth of continental crust in South China started since the early Archean, but a stable cratonic block through reworking did not occur until the Paleoproterozoic. Thus the operation of some form of plate tectonics may occur in China continents since Eoarchean. The initial destruction of the South China craton was caused by intensive magmatic activity in association with the assembly and breakup of the supercontinent Rodinia during the Neoproterozoic. However, most of the Archean and Paleoproterozoic crustal materials in South China do not occur as surface rocks, but exist as sporadic crustal remnants. Nevertheless, the occurrence of Neoproterozoic magmatism is still a signature to distinguish South China from North China.

  20. Mechanical Properties of non-accreting Neutron Star Crusts

    CERN Document Server

    Hoffman, Kelsey


    The mechanical properties of a neutron star crust, such as breaking strain and shear modulus, have implications for the detection of gravitational waves from a neutron star as well as bursts from Soft Gamma-ray Repeaters (SGRs). These properties are calculated here for three different crustal compositions for a non-accreting neutron star that results from three different cooling histories, as well as for a pure iron crust. A simple shear is simulated using molecular dynamics to the crustal compositions by deforming the simulation box. The breaking strain and shear modulus are found to be similar in the four cases, with a breaking strain of ~0.1 and a shear modulus of ~10^{30} dyne cm^{-2} at a density of \\rho = 10^{14} g cm^{-3} for simulations with an initially perfect BCC lattice. With these crustal properties and the observed properties of {PSR J2124-3358} the predicted strain amplitude of gravitational waves for a maximally deformed crust is found to be greater than the observational upper limits from LIG...

  1. Ecology under lake ice. (United States)

    Hampton, Stephanie E; Galloway, Aaron W E; Powers, Stephen M; Ozersky, Ted; Woo, Kara H; Batt, Ryan D; Labou, Stephanie G; O'Reilly, Catherine M; Sharma, Sapna; Lottig, Noah R; Stanley, Emily H; North, Rebecca L; Stockwell, Jason D; Adrian, Rita; Weyhenmeyer, Gesa A; Arvola, Lauri; Baulch, Helen M; Bertani, Isabella; Bowman, Larry L; Carey, Cayelan C; Catalan, Jordi; Colom-Montero, William; Domine, Leah M; Felip, Marisol; Granados, Ignacio; Gries, Corinna; Grossart, Hans-Peter; Haberman, Juta; Haldna, Marina; Hayden, Brian; Higgins, Scott N; Jolley, Jeff C; Kahilainen, Kimmo K; Kaup, Enn; Kehoe, Michael J; MacIntyre, Sally; Mackay, Anson W; Mariash, Heather L; McKay, Robert M; Nixdorf, Brigitte; Nõges, Peeter; Nõges, Tiina; Palmer, Michelle; Pierson, Don C; Post, David M; Pruett, Matthew J; Rautio, Milla; Read, Jordan S; Roberts, Sarah L; Rücker, Jacqueline; Sadro, Steven; Silow, Eugene A; Smith, Derek E; Sterner, Robert W; Swann, George E A; Timofeyev, Maxim A; Toro, Manuel; Twiss, Michael R; Vogt, Richard J; Watson, Susan B; Whiteford, Erika J; Xenopoulos, Marguerite A


    Winter conditions are rapidly changing in temperate ecosystems, particularly for those that experience periods of snow and ice cover. Relatively little is known of winter ecology in these systems, due to a historical research focus on summer 'growing seasons'. We executed the first global quantitative synthesis on under-ice lake ecology, including 36 abiotic and biotic variables from 42 research groups and 101 lakes, examining seasonal differences and connections as well as how seasonal differences vary with geophysical factors. Plankton were more abundant under ice than expected; mean winter values were 43.2% of summer values for chlorophyll a, 15.8% of summer phytoplankton biovolume and 25.3% of summer zooplankton density. Dissolved nitrogen concentrations were typically higher during winter, and these differences were exaggerated in smaller lakes. Lake size also influenced winter-summer patterns for dissolved organic carbon (DOC), with higher winter DOC in smaller lakes. At coarse levels of taxonomic aggregation, phytoplankton and zooplankton community composition showed few systematic differences between seasons, although literature suggests that seasonal differences are frequently lake-specific, species-specific, or occur at the level of functional group. Within the subset of lakes that had longer time series, winter influenced the subsequent summer for some nutrient variables and zooplankton biomass. © 2016 The Authors. Ecology Letters published by CNRS and John Wiley & Sons Ltd.

  2. Yellowstone Lake Nanoarchaeota

    Directory of Open Access Journals (Sweden)

    Scott eClingenpeel


    Full Text Available Considerable Nanoarchaeota novelty and diversity were encountered in Yellowstone Lake, Yellowstone National Park, where sampling targeted lake floor hydrothermal vent fluids, streamers and sediments associated with these vents, and in planktonic photic zones in three different regions of the lake. Significant homonucleotide repeats (HR were observed in pyrosequence reads and in near full-length Sanger sequences, averaging 112 HR per 1,349 bp clone and could confound diversity estimates derived from pyrosequencing, resulting in false nucleotide insertions or deletions (indels. However, Sanger sequencing of two different sets of PCR clones (110 bp, 1349 bp demonstrated that at least some of these indels are real. The majority of the Nanoarchaeota PCR amplicons were vent associated; however, curiously, one relatively small Nanoarchaeota OTU (70 pyrosequencing reads was only found in photic zone water samples obtained from a region of the lake furthest removed from the hydrothermal regions of the lake. Extensive pyrosequencing failed to demonstrate the presence of an Ignicoccus lineage in this lake, suggesting the Nanoarchaeota in this environment are associated with novel Archaea hosts. Defined phylogroups based on near full-length PCR clones document the significant Nanoarchaeota 16S rRNA gene diversity in this lake and firmly establish a terrestrial clade distinct from the marine Nanoarcheota as well as from other geographical locations.

  3. Yellowstone lake nanoarchaeota. (United States)

    Clingenpeel, Scott; Kan, Jinjun; Macur, Richard E; Woyke, Tanja; Lovalvo, Dave; Varley, John; Inskeep, William P; Nealson, Kenneth; McDermott, Timothy R


    Considerable Nanoarchaeota novelty and diversity were encountered in Yellowstone Lake, Yellowstone National Park (YNP), where sampling targeted lake floor hydrothermal vent fluids, streamers and sediments associated with these vents, and in planktonic photic zones in three different regions of the lake. Significant homonucleotide repeats (HR) were observed in pyrosequence reads and in near full-length Sanger sequences, averaging 112 HR per 1349 bp clone and could confound diversity estimates derived from pyrosequencing, resulting in false nucleotide insertions or deletions (indels). However, Sanger sequencing of two different sets of PCR clones (110 bp, 1349 bp) demonstrated that at least some of these indels are real. The majority of the Nanoarchaeota PCR amplicons were vent associated; however, curiously, one relatively small Nanoarchaeota OTU (71 pyrosequencing reads) was only found in photic zone water samples obtained from a region of the lake furthest removed from the hydrothermal regions of the lake. Extensive pyrosequencing failed to demonstrate the presence of an Ignicoccus lineage in this lake, suggesting the Nanoarchaeota in this environment are associated with novel Archaea hosts. Defined phylogroups based on near full-length PCR clones document the significant Nanoarchaeota 16S rRNA gene diversity in this lake and firmly establish a terrestrial clade distinct from the marine Nanoarcheota as well as from other geographical locations.

  4. Ecology of playa lakes (United States)

    Haukos, David A.; Smith, Loren M.


    Between 25,000 and 30,000 playa lakes are in the playa lakes region of the southern high plains (Fig. 1). Most playas are in west Texas (about 20,000), and fewer, in New Mexico, Oklahoma, Kansas, and Colorado. The playa lakes region is one of the most intensively cultivated areas of North America. Dominant crops range from cotton in southern areas to cereal grains in the north. Therefore, most of the native short-grass prairie is gone, replaced by crops and, recently, grasses of the Conservation Reserve Program. Playas are the predominant wetlands and major wildlife habitat of the region.More than 115 bird species, including 20 species of waterfowl, and 10 mammal species have been documented in playas. Waterfowl nest in the area, producing up to 250,000 ducklings in wetter years. Dominant breeding and nesting species are mallards and blue-winged teals. During the very protracted breeding season, birds hatch from April through August. Several million shorebirds and waterfowl migrate through the area each spring and fall. More than 400,000 sandhill cranes migrate through and winter in the region, concentrating primarily on the larger saline lakes in the southern portion of the playa lakes region.The primary importance of the playa lakes region to waterfowl is as a wintering area. Wintering waterfowl populations in the playa lakes region range from 1 to 3 million birds, depending on fall precipitation patterns that determine the number of flooded playas. The most common wintering ducks are mallards, northern pintails, green-winged teals, and American wigeons. About 500,000 Canada geese and 100,000 lesser snow geese winter in the playa lakes region, and numbers of geese have increased annually since the early 1980’s. This chapter describes the physiography and ecology of playa lakes and their attributes that benefit waterfowl.

  5. Heavy Metal Enrichment History in annually laminated Lake Tiefer See (NE-Germany) and Lake Czechowskie (N-Poland) (United States)

    Hoelzmann, Philipp; Dräger, Nadine; Kienel, Ulrike; Ott, Florian; Brauer, Achim


    Within the Virtual Institute of Integrated Climate and Landscape Evolution Analyses (ICLEA) high-resolution geo-archives (e.g. lakes as natural data loggers) of the northeastern german and northern polish lowlands are investigated to identify influences of land-use on the landscape evolution. For two annually laminated lake sediment records, situated in rural environments in NE-Germany (Lake Tiefer See) and N-Poland (Czechowskie Lake), we present a detailed heavy metal enrichment history for Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, and Zn for the last two hundred years at 1 cm intervals. Both lakes show a similar pattern of relatively low heavy metal concentrations if compared to the so-called index of geoaccumulation (Müller 1979), which is based on the average global metal content in shales (Turekian and Wedepohl, 1961). Only Pb, Zn and Cd show a clear parallel pattern of enrichment in both lakes starting around 1850 according to mainly atmospheric input due to increasing industrialization within the framework of the Industrial Revolution. Highest input for Cd, Zn, and Pb occur around 1960 to 1980 and thereafter a clear pattern of declining anthropogenic input is registered. On the base of heavy-metal analysis of pre-industrial sediments and different sediment types (e.g. calcareous gyttja, organic gyttja etc.) the local and specific geogenic background values for various metals are determined. These results provide means to calculate and quantify with sub-decadal resolution anthropogenic heavy metal accumulations and enrichment factors as well as to define regional measures for a state of reference, reflecting natural conditions without human impact. Müller, G. (1979): Schwermetalle in den Sedimenten des Rheins - Veränderungen seit 1971. Umschau 79: 778-783. Turekian, K. and Wedepohl, K. (1961): Distribution of the elements in some major units of the earth's crust. Bull.Geol.Soc.Am. 72: 175-192.

  6. Spatial-temporal variations of dominant drought/flood modes and the associated atmospheric circulation and ocean events in rainy season over the east of China (United States)

    Huang, Shaoni; Huang, Fei


    By using Season-reliant Empirical Orthogonal Function (S-EOF) analysis, three dominant modes of the spatial-temporal evolution of the drought/flood patterns in the rainy season over the east of China are revealed for the period of 1960-2004. The first two leading modes occur during the turnabout phase of El Niño-Southern Oscillation (ENSO) decaying year, but the drought/flood patterns in the rainy season over the east of China are different due to the role of the Indian Ocean (IO). The first leading mode appears closely correlated with the ENSO events. In the decaying year of El Niño, the associated western North Pacific (WNP) anticyclone located over the Philippine Sea persists from the previous winter to the next early summer, transports warm and moist air toward the southern Yangtze River in China, and leads to wet conditions over this entire region. Therefore, the precipitation anomaly in summer exhibits a `Southern Flood and Northern Drought' pattern over East China. On the other hand, the basin-wide Indian Ocean sea surface temperature anomaly (SSTA) plays a crucial role in prolonging the impact of ENSO on the second mode during the ENSO decaying summer. The Indian Ocean basin mode (IOBM) warming persists through summer and unleashes its influence, which forces a Matsuno-Gill pattern in the upper troposphere. Over the subtropical western North Pacific, an anomalous anticyclone forms in the lower troposphere. The southerlies on the northwest flank of this anticyclone increase the moisture transport onto central China, leading to abundant rainfall over the middle and lower reaches of the Yangtze River and Huaihe River valleys. The anomalous anticyclone causes dry conditions over South China and the South China Sea (SCS). The precipitation anomaly in summer exhibits a `Northern Flood and Southern Drought' pattern over East China. Therefore, besides the ENSO event the IOBM is an important factor to influence the drought/flood patterns in the rainy season over

  7. Evaluation of the efficiency of the photo Fenton disinfection of natural drinking water source during the rainy season in the Sahelian region

    Energy Technology Data Exchange (ETDEWEB)

    Ndounla, J., E-mail: [Ecole Polytechnique Fédérale de Lausanne, Institute of Chemical Sciences and Engineering GPAO, Station 6, CH 1015 Lausanne (Switzerland); Institut International d' Ingénierie de l' Eau et de l' Environnement, Laboratoire Eau, Dépollution, Ecosystème et Santé (LEDES), 01 BP 594 Ouagadougou 01 (Burkina Faso); Pulgarin, C., E-mail: [Ecole Polytechnique Fédérale de Lausanne, Institute of Chemical Sciences and Engineering GPAO, Station 6, CH 1015 Lausanne (Switzerland)


    The photo-disinfection of water from two different wells (W1, pH: 4.6–5.1 ± 0.02) and (W2 pH: 5.6–5.7 ± 0.02) was carried out during the rainy season at Ouagadougou–Burkina Faso, West Africa. The weather variation during the rainy season significantly affects the photo-disinfection processes (solar disinfection and photo-Fenton). The dilution of the water by rainwater highly affected the chemical composition of the wells' water used in this study; very low iron contents Compared to the ones recorded during the dry season were recorded in all water samples. Both photo-disinfection processes were used to treat 25 L of water in a compound parabolic collector (CPC). None of them have shown the total inactivation of both wild enteric bacteria strains (total coliforms/E. coli and Salmonella spp.) involved in the treatment. However, the total coliforms/E. coli strains were totally inactivated during the exposure under most of the photo-Fenton treatment. Also, the remaining strains, especially those of Salmonella spp. were achieved during the subsequent 24 h of dark storage under the action of the Fenton process. Under uniquely solar radiation, total inactivation was recorded only in the total coliforms/E. coli strains. The impact of the available irradiance on the efficiency of the photo-Fenton disinfection of natural water was highlighted during the exposure under high intermittent solar radiation. The impact of the HCO{sub 3}{sup −} concentration of both wells' water on the evolution of the pH during the photo-disinfection was recorded. Drastic decrease was noticed after the initial fast increase in presence of low HCO{sub 3}{sup −} concentration while a steady state was observed after the increase in presence of higher concentration. The redox activities of the nitrogen components of the water during both photo-disinfection processes have led to increased concentration of nitrite in all the cases and variations were noticed in that of nitrate and

  8. Energy conservation in the earth's crust and climate change. (United States)

    Mu, Yao; Mu, Xinzhi


    Among various matters which make up the earth's crust, the thermal conductivity of coal, oil, and oil-gas, which are formed over a long period of geological time, is extremely low. This is significant to prevent transferring the internal heat of the earth to the thermal insulation of the surface, cooling the surface of the earth, stimulating biological evolution, and maintaining natural ecological balance as well. Fossil energy is thermal insulating layer in the earth's crust. Just like the function of the thermal isolation of subcutaneous fatty tissue under the dermis of human skin, it keeps the internal heat within the organism so it won't be transferred to the skin's surface and be lost maintaining body temperature at low temperatures. Coal, oil, oil-gas, and fat belong to the same hydrocarbons, and the functions of their thermal insulation are exactly the same. That is to say, coal, oil, and oil-gas are just like the earth's "subcutaneous fatty tissue" and objectively formed the insulation protection on earth's surface. This paper argues that the human large-scale extraction of fossil energy leads to damage of the earth's crust heat-resistant sealing, increasing terrestrial heat flow, or the heat flow as it is called, transferring the internal heat of the earth to Earth's surface excessively, and causing geotemperature and sea temperature to rise, thus giving rise to global warming. The reason for climate warming is not due to the expansion of greenhouse gases but to the wide exploitation of fossil energy, which destroyed the heat insulation of the earth's crust, making more heat from the interior of the earth be released to the atmosphere. Based on the energy conservation principle, the measurement of the increase of the average global temperature that was caused by the increase of terrestrial heat flow since the Industrial Revolution is consistent with practical data. This paper illustrates "pathogenesis" of climate change using medical knowledge. The

  9. Biological soil crusts in Chile along the precipitation gradient (United States)

    Samolov, Elena; Glaser, Karin; Baumann, Karen; Leinweber, Peter; Jung, Patrick; Büdel, Burkhard; Mikhailyuk, Tatiana; Karsten, Ulf


    Biological soil crusts in Chile along a precipitation gradient Elena Samolov* (1), Karin Glaser (1), Karen Baumann (2), Peter Leinweber (2), Patrick Jung (3), Burkhard Büdel (3), Tatiana Mikhailyuk (4) and Ulf Karsten (1) (1) Institute of Biological Sciences - Applied Ecology and Phycology, University of Rostock, Rostock, Germany, (2) Faculty of Agricultural and Environmental Sciences - Soil Sciences, University of Rostock, Rostock, Germany (3) University of Kaiserslautern, Kaiserslautern, Germany (4) M.H. Kholodny Institute of Botany, National Academy of Science of Ukraine, Kyiv, Ukraine * Biological soil crusts (BSCs) are an association of different microorganisms and soil particles in the top millimeters of the soil. They are formed by algae, cyanobacteria, microfungi, bacteria, bryophytes and lichens in various compositions; together with their by-products they create a micro-ecosystem that performs important ecological functions, e.g. primary production, nitrogen fixation, mineralization and stabilization of soils. These top-soil assemblages are almost unstudied in South America (Büdel et al. 2016). Therefore, our aim is to investigate for the first time biodiversity of the key photosynthetic organisms, green algae and cyanobacteria following a precipitation gradient along the west coast of Chile. We are applying polyphasic approach - a combination of microscopy, culture dependent (16S and 18S rRNA, ITS) and culture independent molecular techniques (NGS). First results, based on culturing and light microscopy, showed high diversity of eukaryotic algae in biocrusts from humid regions, followed by semi-arid regions. Lichen dominated biocrusts from arid regions were characterized by a high diversity of green algae, while cyanobacteria were scarcely present. The functional role of the BSCs in the biogeochemical cycle of phosphorous (P) was evaluated using state of the art analytical methods including 31P-NMR (nuclear magnetic


    Directory of Open Access Journals (Sweden)



    Full Text Available Present paper deals with the physic-chemical parameters of Naspur lake, Manchiryal mandal, Aailabad district. The work was carried out during the period of Sep-2011 to Aug 2012.This lake was established for Irrigation, Drinking water and Fish culture purpose last two decades back. It was in the out of 7 km distance from Manchiryal town. Singareni coal mine employs are living in the Manchiryal town, day by day expanding of city population last two decades .In rainy season it’s receiving city sewage .industrial wastes, coalmine dust run off to the lake. This type of water injuries to the health of human other aquatic fauna. So there is an urgent requirement for its extent of pollution which will help us in further management of conservation. During the study period examine the physic-chemical parameters such as: atmosphere temperature, water temperature, pH, electrical conductivity, alkalinity, total hardness, TDS, Ca.Mg, chlorides, sulphates and phosphate, following stranded methods (APHA 1998. Now this lake is becoming eutrophic nature.

  11. Bloedite sedimentation in a seasonally dry saline lake (Salada Mediana, Spain) (United States)

    Mees, Florias; Castañeda, Carmen; Herrero, Juan; Van Ranst, Eric


    Salt crusts covering the surface of the Salada Mediana, a seasonally dry saline lake in northern Spain, consist predominantly of bloedite (Na 2Mg(SO 4) 2.4H 2O). Microscopic features of the crust were investigated to understand processes of bloedite sedimentation. This study was combined with satellite and airborne observations, revealing asymmetrical concentric and parallel-linear patterns, related to wind action. Gypsum (CaSO 4.H 2O) and glauberite (Na 2Ca(SO 4) 2) in the calcareous sediments below the crust, and abundant eugsterite (Na 4Ca(SO 4) 3.2H 2O) along the base of the crust, largely formed at a different stage than bloedite. The main part of the crust consists predominantly of coarse-crystalline xenotopic-hypidiotopic bloedite, but fan-like aggregates with downward widening, radial aggregates, surface layers with vertically aligned elongated crystals, and partially epitaxial coatings occur as well. The upper part of the crust is marked by a bloedite-thenardite (Na 2SO 4) association, recording a change in brine composition that is not in agreement with results of modelling of local brine evolution. A thin fine-grained thenardite-dominated surface formed in part by subaqueous settling of crystals, but there are also indications for development by transformation of bloedite. Surface features include fan-like bloedite aggregates with upward widening, formed by bottom growth. Overall, the Salada Mediana crusts record a complex history of bloedite and thenardite precipitation by various processes.

  12. Effect of Phosphatization on Element Concentration of Cobalt-Rich Ferromanganese Crusts

    Institute of Scientific and Technical Information of China (English)

    PAN Jiahua; E. H. De CARLO; YANG Yi; LIU Shuqin; YOU Guoqin


    A detailed study on a small scale of the effect of phosphatization on the chemistry of marine cobalt-rich ferromanganese crusts supplies useful information for the evaluation and comprehensive utilization of crust mineral resources. Sub-samples from top to bottom of a 10-cm thick sample from the NW Pacific Magellan seamount were taken at 5 mm intervals. The concentration profiles of ore-forming and rare earth elements show that obvious differences exist between young unphosphatized crusts and old phosphatized crusts. In the old crusts Fe, Mn, Si, Al, Zn, Mg, Co, Ni and Cu elements are depleted and Ca, P, Sr, Ba and Pb elements are enriched. The order of depletion is Co > Ni > Mg > Al > Mn >Si> Cu > Zn > Fe, while the order of enrichment is P > Ca > Ba > Pb > Sr. The phosphate mineral controls the concentration variation of the ore-forming elements in crusts and causes loss of the main ore-forming elements such as Co and Ni. The phosphatization also affects the abundance of REEs in the crusts. REEs are more abundant and the content of Ce in old crusts is higher than that in young crusts, however, the pattern of REEs and their fractionation characteristics in new and old crusts are not fundamentally changed. A Y-positive anomaly in old crusts has no relationship to the phosphatization.

  13. Structure and dynamics of phytoplankton in an Amazon lake, Brazil

    Directory of Open Access Journals (Sweden)

    Ise de Goreth Silva


    Full Text Available Natural lake systems represent important reservoirs for residential water supply, fish production, recreational activities and enjoyment of their natural beauty. Nevertheless, human impacts may affect their health status resulting in degradation and loss of biodiversity. The aim of the present study was to obtain data on the health status of a natural lake located in an indigenous reservation in the Brazilian Amazon, using the phytoplankton community changes along the rainy (June and dry (November seasons of 2006. We collected water (temperature, pH, Secchi depth and conductivity and phytoplankton samples from the subsurface, middle of the water column, and approximately 30cm above the bottom, over 24-hour sampling periods, from a central station in the lake. Samples taken from biotic and abiotic variables were correlated using canonical correspondence analysis (CCA. Results showed that the lake exhibited high temperatures in both seasons, and showed thermal stratification only during the rainy season. Dissolved oxygen exhibited a clinograde pattern in the rainy season and high oxygen in the hypolimnion in the dry season. In the rainy season, the water near the bottom was acidic, turbid and had a greater concentration of phosphorus. Dissolved oxygen, conductivity, pH, nitrite, total phosphorus and total dissolved phosphorus exhibited diel variations in the rainy season, whereas water temperature, dissolved oxygen, total nitrogen and total dissolved phosphorus exhibited significant differences between hours of the day in the dry season. The phytoplankton was represented by 39 taxa, and Chlorophyta showed the greatest species richness, totaling 25 taxa. Among Chlorophyta, desmids were the most diverse, accounting 52%. Bacillariophyta (nine species was the second most diverse group. Cyanophyta was represented by three species, including Merismopedia tenuissima, the most abundant taxon. Despite the occurrence of taxa that indicate organic pollution

  14. Magma underplating and Hannuoba present crust-mantle transitional zone composition: Xenolith petrological and geochemical evidence

    Institute of Scientific and Technical Information of China (English)

    FAN Qicheng; ZHANG Hongfu; SUI Jianli; ZHAI Mingguo; SUN Qian; LI Ni


    On the basis of mineral assemblage, mineralogy, petrology, and major, trace elemental and isotopic geochemistry of the underplated granulite- and eclogite-facies accumulate, peridotite and pyroxenite xenoliths entrained in Hannuoba Cenozoic basalts, this work constrained the petrological constituents for the crust-mantle transitional zone, which is supported by the results of high-temperature and pressure velocity experiments on rocks and geophysics deep survey. Present lower part of lower crust is mainly composed of granulite-facies mafic accumulates (dominantly plagioclase websterite) and crust-mantle transitional zone dominantly composed of eclogite-facies pyroxenites with or without garnet and spinel lherzolites; Archaean terrain granulite is only nominally early lower crust. Magma underplating in the crust-mantle boundary led to the crustal vertical accretion and the formation of the crust-mantle transitional zone, which is a significant mechanism for the chemical adjustment of the crust-mantle boundary since the Phanerozoic.

  15. Equation of state and thickness of the inner crust of neutron stars

    CERN Document Server

    Grill, Fabrizio; Providência, Constança; Vidaña, Isaac; Avancini, Sidney S


    The cell structure of $\\beta$-stable clusters in the inner crust of cold and warm neutron stars is studied within the Thomas-Fermi approach using relativistic mean field nuclear models. The relative size of the inner crust and the pasta phase of neutron stars is calculated, and the effect of the symmetry energy slope parameter, $L$, on the profile of the neutron star crust is discussed. It is shown that while the size of the total crust is mainly determined by the incompressibility modulus, the relative size of the inner crust depends on $L$. It is found that the inner crust represents a larger fraction of the total crust for smaller values of $L$. Finally, it is shown that at finite temperature the pasta phase in $\\beta$-equilibrium matter essentially melts above $5-6$ MeV, and that the onset density of the rodlike and slablike structures does not depend on the temperature.

  16. Can lake sensitivity to desiccation be predicted from lake geometry? (United States)

    Torabi Haghighi, Ali; Menberu, Meseret Walle; Aminnezhad, Mousa; Marttila, Hannu; Kløve, Bjørn


    Declining lake levels (Aral Sea syndrome) can be caused by changes in climate, increased water use or changed regulation patterns. This paper introduces a novel lake geometry index (LGI) to quantify lake hydrological characteristics. The index was developed using a large representative dataset of lake hypsographic characteristics from 152 lakes and man-made reservoirs. Using the LGI index, lakes can be classified into five groups: groups 1-4 when LGI is 0.5-2.5, 2.5-4.5, 4.5-6.5 and 6.5-8.5, respectively, and group 5 when LGI is >8.5. Naturally shallow and vast lakes and wetlands fall into the first group and deep man-made reservoirs in narrow valleys are in group 5. The response of three different lake systems (LGI 0.75, 2.75 and 6.5) to different water flow scenarios was then simulated using the water balance equation. From this, the index 'potential lake area' (Apot) was developed to show lake responses to changed hydro-climatological conditions. Apot and LGI can be used to classify lakes into open or closed systems. Simulations showed that lakes with low LGI have a shorter response time to flow and climate changes. As a result, the impact of water balance restoration is faster for lakes with low LGI than for lakes with high LGI. The latter are also more vulnerable to climate variation and change.

  17. How Does Boiling in the Earth's Crust Influence Metal Speciation and Transport? (United States)

    Kam, K.; Lemke, K.


    The presence of large quantities of precious metals, such as gold and copper, near the Earth's surface (upper crust) is commonly attributed to transport in aqueous solution and precipitation upon variations in temperature and pressure. As a consequence, gold exploration is closely linked to solution chemistry, i.e. hydrothermal processes involving aqueous fluids with densities of around unity. However, as crustal fluids buoyantly ascend, boiling produces a coexisting low-density aqueous liquid with fundamentally different physical and chemical properties, and a, most importantly, a high affinity for coinage metals (Heinrich et al., Econ Geol., 1992, 87, 1566). From recent experimental studies of Au (Hurtig and Williams-Jones, 2014, Geochim. Cosmochim. Acta,, 127, 304), we know that metal speciation in this low-density phase differs fundamentally from that observed in bulk solution, clearly, with important implications for Au, and metal speciation in general, transport and ore concentrations processes (these processes would also be operable in industrial geothermal plants given the quite special solvent properties of steam). In brief, this study focuses on the speciation of select metal halides in bulk solution as well as in water vapor, and is driven by our need to understand the solvent properties of around 2.0x109 cubic kilometers of free water (or 2,500 times as much water as stored in all lakes and rivers) present in the Earth's crust. The scope of this study has particular applications in the geothermal and oil industries, as both deal with high temperature low-density aqueous fluids. Understanding how metal halide species behave upon boiling can also provide insight into how metals, such as copper and silver, coat turbine equipment and steam piping in geothermal plants, ultimately rendering these components inoperable. This study will also provide preliminary results from mass spectrometric experiments of transition metal halides, and will be augmented with

  18. Halls Lake 1990 (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Salt marsh habitats along the shoreline of Halls Lake are threatened by wave erosion, but the reconstruction of barrier islands to reduce this erosion will modify or...

  19. Sunk Lake Natural Area (United States)

    US Fish and Wildlife Service, Department of the Interior — The Sunk Lake Natural Area Management Plan guides the long-range development of the Natural Area by identifying and integrating appropriate habitats, management...

  20. Lake Transect : 1986 (United States)

    US Fish and Wildlife Service, Department of the Interior — This document summarizes transect surveys that were done at four different lakes on St. Vincent National Wildlife Refuge in 1986. Lists of the plant species found at...

  1. Lake Transect : 1988 (United States)

    US Fish and Wildlife Service, Department of the Interior — This document summarizes transect surveys that were done at four different lakes on St. Vincent National Wildlife Refuge in 1988. Lists of the plant species found at...

  2. Lake Transect : 1989 (United States)

    US Fish and Wildlife Service, Department of the Interior — This document summarizes transect surveys that were done at four different lakes on St. Vincent National Wildlife Refuge in 1989. Lists of the plant species found...

  3. History of Lake Andes (United States)

    US Fish and Wildlife Service, Department of the Interior — Information about the history and management of Lake Andes is compiled in this report. It is intended to help future refuge managers become acquainted with the...

  4. Lake Level Reconstructions (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Records of past lake levels, mostly related to changes in moisture balance (evaporation-precipitation). Parameter keywords describe what was measured in this data...

  5. Great Lakes Ice Charts (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Charts show ice extent and concentration three times weekly during the ice season, for all lakes except Ontario, from the 1973/74 ice season through the 2001/2002...

  6. The influence of Castanhão reservoir on nutrient and suspended matter transport during rainy season in the ephemeral Jaguaribe river (CE, Brazil). (United States)

    Molisani, M M; Becker, H; Barroso, H S; Hijo, C A G; Monte, T M; Vasconcellos, G H; Lacerda, L D


    Measurements of nutrient and suspended matter concentrations and loads entering and leaving the Castanhão reservoir during the rainy season were carried out to assess the influence of this large reservoir on land-sea fluvial transport in the ephemeral Jaguaribe river basin. Spatial variation indicated statistically significant attenuation of concentrations only for total phosphorous and suspended matter across the reservoir. Strong retention of nutrients and suspended matter loads by the reservoir was observed with average trapping efficiency of 89% for dissolved silicon, 98% of soluble reactive phosphorus, 71% for ammonium, 87% for total nitrogen, 98% for total phosphorus and 97% for suspended matter compared to the reservoir inflow. The dam operational procedure defined by the ephemeral conditions of the river reduced water releases compared to reservoir inflow and induced strong retention of nutrient and suspended matter loads within the reservoir when fluvial transfer occurs in this semiarid watershed.

  7. Chase Lake Wetland Management District, Chase Lake National Wildlife Refuge, Chase Lake Prairie Project: Annual narrative report: 1997 (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual narrative report for Chase Lake WMD, Chase Lake NWR, Chase Lake Prairie Project, and Halfway Lake NWR outlines Refuge accomplishments during the 1997...

  8. Is Lake Tahoe Terminal? (United States)

    Coats, R. N.; Reuter, J.; Heyvaert, A.; Lewis, J.; Sahoo, G. B.; Schladow, G.; Thorne, J. H.


    Lake Tahoe, an iconic ultra-oligotrophic lake in the central Sierra Nevada, has been studied intensively since 1968, with the goal of understanding and ultimately controlling its eutrophication and loss of clarity. Research on the lake has included a) periodic profiles of primary productivity, nutrients, temperature, and plankton; b) Secchi depth; c) nutrient limitation experiments; d) analysis of sediment cores; e) radiocarbon dating of underwater in-place tree stumps; g) analysis of long-term temperature trends. Work in its watershed has included a) monitoring of stream discharge, sediment and nutrients at up to 20 stream gaging stations; b) monitoring of urban runoff water quality at selected sites; c) development of a GIS data base, including soils, vegetation, and land use. Based on these studies, we know that a) primary productivity in the lake is limited by phosphorus, and continues to increase; b) the loss of clarity continues, but at a declining rate; c) the lake has been warming since 1970, and its resistance to deep mixing is increasing; d) historically the lake level drops below the outlet elevation about one year in seven; e) 6300 to 4300 yrs BP lake level was below the present outlet elevation long enough for large trees to grow; f) the date of the peak snowmelt runoff is shifting toward earlier dates; g) after accounting for annual runoff, loads of nutrients and suspended sediment have declined significantly in some basin streams since 1980. Downscaled outputs from GCM climatic models have recently been used to drive hydrologic models and a lake clarity model, projecting future trends in the lake and watersheds. Results show a) the temperature and thermal stability will likely continue to increase, with deep mixing shutting down in the latter half of this century; b) the lake may drop below the outlet for an extended period beginning about 2085; c) the annual snowpack will continue to decline, with earlier snowmelt and shift from snowfall to rain; d

  9. The impacts of NOM from on the water quality of the streams and lakes (United States)

    Lee, Sang Hee; Lee, Soohyung; Lee, Junbae; Khan, Jong beom; Lee, Seyong; Lee, Yunkyung; Hur, Jin; Lee, Hanseam; Shin, Hyunsang


    The COD levels of the Lake Daechung, one of a major source of drinking water, have been increased since 1994 whereas the BOD levels have been decreased. Those increases raise the concerns about the effectiveness of water treatment system or the unmanageable contaminant sources such as ROMs (Refractory Organic Matters). Nine basic water quality factors such as COD, TOC, DOC, T-N, T-P, etc. (every week) and NOM (Natural Organic Matters, every month) in the up and down streams of Juwon and Pumgok and related junction with the Lake Daechung were monitored from June to Nov., 2015 in order to investigate the impacts on the water quality of the Lake Daechung. Resulting from the monitoring, the increases in the COD, TOC and DOC suggested that the heavy rainfall (>50 mm/day) could lead to the influx of ROM to the streams. Furthermore, increases in the EE intensities of EEM in July, Aug., and Sep., suggested that the rainfall would deliver the terrestrial ROM to the streams. However, it is difficult to recognize the similar changes in the lake Daechung due to the larger water capacity. The water samples collected from streams during the rainy period were fractionated using XAD columns and pH adjustment. The DOC composition(%) of humic and fulvic fraction in upstream of which basin was composed by forestry were higher than those in downstream affected by various land uses implying that more organic materials in upstream would be originated from the forestry than those in downstream. and hydrophilic The increases in the DOC of the related fractions, SUVA and EEM of the samples collected during the rainy season implied that heavy rainfall would lead for the terrestrial NOM to enter the streams whereas the concentration of the biopolymer were increased in the streams during the dry season. In summary, this study suggested that the ROM originated from forestry could be entered in the streams and some of anthropogenic chemicals such as biocide and nitrophenols accumulated in the


    Schulz, Klaus J.


    The mineral-resource potential of the Whisker Lake Wilderness in northeastern Wisconsin was evaluated. Only a strip along the southwest corner of the wilderness is assessed as having probable mineral-resource potential. If mineral deposits exist, they probably are of the massive sulfide type. The geologic terrain precludes the presence of fossil fuel resources. Sand and gravel and peat in swampy lowlands are the only resources of the Whisker lake Wilderness.

  11. Levels of ground corn supplied to beef heifers at pasture during the rainy season: productive performance, intake, digestibility and microbial efficiency

    Directory of Open Access Journals (Sweden)

    Darcilene Maria de Figueiredo


    Full Text Available The objective was to evaluate the effect of four levels of ground corn supply on nutritional parameters, microbial synthesis efficiency and growing performance of beef heifers, at the rainy season. For such, 28 crossbred yearling heifers, with initial age of 16-17 months and initial weight of 255 ± 31.0 kg were distributed into five paddoks of B. decumbens, of 2.0 ha each, with average potentially digestible DM availability of 2,377.0 kg/ha. For each one of the lots, one of the following supplements was daily supplied: mineral mix exclusively or with ground corn at levels 0.25, 0.50, 0.75 or 1.00 kg/day. The experiment was arranged in completely randomized design with five treatments (supplements, five repetitions for the groups receiving exclusive mineral mix or mineral mix plus corn on the level of 0.50 kg/day and six repetitions for those receiving the other supplements. There was a response of 0.092 kg of weight gain for every 1 kg of ground corn supplied to the animals, and no substitution effect was verified on the dry matter intake of pasture. The increase in ground corn levels increased metabolizable energy intake, which is explained by the crescent linear effect on digestible dry matter intake, on apparent digestibility of dry matter and organic matter as well as on the levels of total digestible nutrients of the diet consistent with the increase in intake of the most digestible ingredient, ground corn. In the same way, there was a positive linear effect for apparent digestibility of neutral detergent fiber. The supplementation provided linear positive effect on the flow of microbial nitrogen compounds (MICN for the small intestine, and did not affect the microbial synthesis efficiency. The supply of energetic supplement for beef heifers, at pasture, during the rainy season increases the use of the forage and consequently, weight gain.

  12. Contamination of drinking water sources during the rainy season in an urban post-conflict community in Guinea Bissau: implications for sanitation priority. (United States)

    Colombatti, R; Vieira, C S; Bassani, F; Cristofoli, R; Coin, A; Bertinato, L; Riccardi, F


    Since the 1998 civil warcholera outbreaks and waterborne infections have been a major cause of morbidity and mortality during the rainy season in Guinea Bidsau. Our survey aims at: (1) describing the distribution, characteristics and use of water sources and sewage facilities in a central area of the capital city of Bissau; (2) determining the microbiological quality of drinking water during the rainy season. After mapping of the Cuntum 3 study area, water sources' and latrines' location, characteristics and use were determined by visual inspection and interviews with householders. Microbiological analyses were peformed from water sources for evaluation of total Coliforms, E. coli, Enterococcus faecalis. Twelve water sources (9 wells, 3 taps) and 15 latrines were identified and used by 444 inhabitants. Water sources and latrines were at less than 5 meters distance apart. Wells were self-built, hand-dug, shallow (4-6 meters), unprotected. Taps were located outdoor. Latrines were self-built, open air, unprotected. None of the houses had a bathroom. Maintenance of wells, taps and latrines is not performed on regular basis and well's handling habits are not safe. Well and tap water showed heavy faecal contamination with more than 1000 CFU/100 ml. The contamination of drinking water in Bissau due to poor construction, maintenance and improperuse ten years after the civil war, demonstrates the need to allocate resources after conflicts in the area of water and sanitation. Both should be included as a priority in post-conflict reconstruction programs in order to reduce cholera outbreaks and diarrhoea related mortality.

  13. Resilience and Restoration of Lakes

    Directory of Open Access Journals (Sweden)

    Kathryn L. Cottingham


    Full Text Available Lake water quality and ecosystem services are normally maintained by several feedbacks. Among these are nutrient retention and humic production by wetlands, nutrient retention and woody habitat production by riparian forests, food web structures that cha nnel phosphorus to consumers rather than phytoplankton, and biogeochemical mechanisms that inhibit phosphorus recycling from sediments. In degraded lakes, these resilience mechanisms are replaced by new ones that connect lakes to larger, regional economi c and social systems. New controls that maintain degraded lakes include runoff from agricultural and urban areas, absence of wetlands and riparian forests, and changes in lake food webs and biogeochemistry that channel phosphorus to blooms of nuisance al gae. Economic analyses show that degraded lakes are significantly less valuable than normal lakes. Because of this difference in value, the economic benefits of restoring lakes could be used to create incentives for lake restoration.

  14. Cyanobacterial crust induction using two non-previously tested cyanobacterial inoculants: crusting capability and role of EPSs (United States)

    Mugnai, Gianmarco; Rossi, Federico; De Philippis, Roberto


    The use of cyanobacteria as soil improvers and bio-conditioners (a technique often referred to as algalization) has been studied for decades. Several studies proved that cyanobacteria are feasible eco-friendly candidates to trigger soil fertilization and enrichment from agricultural to arid and hyper-arid systems. This approach can be successful to achieve stabilization and rehabilitation of degraded environments. Much of the effectiveness of algalization is due to the productivity and the characteristics of extracellular polysaccharides (EPSs) which, among their features, embed soil particles and promote the development of a first stable organo-mineral layer (cyanobacterial crusts). In natural settings, cyanobacterial crust induction represents a first step of a succession that may lead to the formation of mature biological soil crusts (Lan et al., 2014). The aim of this research was to investigate the crusting capabilities, and the characteristics of excreted EPSs by two newly tested non-heterocystous cyanobacterial inoculants, in microcosm experiments carried out using oligothrophic sand collected from sand dunes in Negev Desert, Israel. The cyanobacteria tested were Schizothrix AMPL1601, originally isolated from biocrusts collected in Hobq Desert, Inner Mongolia (China) and Leptolyngbia ohadii, originally isolated from biocrusts collected in Negev Desert, Israel. Inoculated microcosms were maintained at 30 °C in a growth chamber under continuous illumination and minimal water availability. Under such stressing conditions, and for a three-months incubation time, the growth and the colonization of the strains in the microcosms were monitored. At the same time, EPSs production and their chemical and macromolecular characteristics were determined by applying a methodology optimized for the purpose. Notably, EPSs were analyzed in two operationally-defined fractions, one more dispersed in the crust matrix (loosely bound EPSs, LB-EPSs) and one more condensed and

  15. Is Lake Chabot Eutrophic? (United States)

    Pellegrini, K.; Logan, J.; Esterlis, P.; Lew, A.; Nguyen, M.


    Introduction/Abstract: Lake Chabot is an integral part of the East Bay watershed that provides habitats for animals and recreation for humans year-round. Lake Chabot has been in danger of eutrophication due to excessive dumping of phosphorous and nitrogen into the water from the fertilizers of nearby golf courses and neighboring houses. If the lake turned out to be eutrophified, it could seriously impact what is currently the standby emergency water supply for many Castro Valley residents. Eutrophication is the excessive richness of nutrients such as nitrogen and phosphorus in a lake, usually as a result of runoff. This buildup of nutrients causes algal blooms. The algae uses up most of the oxygen in the water, and when it dies, it causes the lake to hypoxify. The fish in the lake can't breathe, and consequently suffocate. Other oxygen-dependant aquatic creatures die off as well. Needless to say, the eutrophication of a lake is bad news for the wildlife that lives in or around it. The level of eutrophication in our area in Northern California tends to increase during the late spring/early summer months, so our crew went out and took samples of Lake Chabot on June 2. We focused on the area of the lake where the water enters, known on the map as Honker Bay. We also took readings a ways down in deeper water for comparison's sake. Visually, the lake looked in bad shape. The water was a murky green that glimmered with particulate matter that swirled around the boat as we went by. In the Honker Bay region where we focused our testing, there were reeds bathed in algae that coated the surface of the lake in thick, swirling patterns. Surprisingly enough, however, our test results didn't reveal any extreme levels of phosphorous or nitrogen. They were slightly higher than usual, but not by any significant amount. The levels we found were high enough to stimulate plant and algae growth and promote eutrophication, but not enough to do any severe damage. After a briefing with a

  16. Tewaukon – Clouds LakeLake Elsie – Storm Lake and Wild Rice Refuges Narrative Reports : 1939-1956 : From Sand Lake National Wildlife Refuge (United States)

    US Fish and Wildlife Service, Department of the Interior — These narrative reports summarize refuge activities from 1939 to 1956 for Lake Tewaukon Refuge, Clouds Lake Refuge, Lake Elsie Refuge, Storm Lake Refuge, Wild Rice...


    The Product is the paper "Pulp and Paper Mills as Sources of Toxaphene to Lake Superior and Northern Lake Michigan" published in the Journal of Great Lakes Research, 25(2):383-394 International Association of Great Lakes 1999.

  18. Invasive alien species water hyacinth Eichhornia crassipes as abode for macroinvertebrates in hypertrophic Ramsar Site, Lake Xochimilco, Mexico. (United States)

    Rocha-Ramirez, A; Robles-Valderrama, E; Ramirez-Flores, E


    This paper presents information on the density, diversity and functional feeding groups of macroinvertebrate assemblages associated with water hyacinth in Antiguo Canal Cuemanco, part of Lake Xochimilco in Mexico City. Rare (low frequency and density) and dominant (high frequency and density) taxa prevailed in the assemblages, with the most predominant being Hyalella azteca, Chironomus plumosus and Ischnura denticollis. Nonmetric Multidimensional Scaling confirmed two climatic seasons: warm-rainy and cold-dry; the former with the highest diversity and density of taxa. Canonical Correspondence Analysis showed that conductivity, nitrates and turbidity explained the density variations of taxa. Antiguo Canal Cuemanco waters are spatially homogeneous with the characteristics of hypertrophic shallow lakes, inhabited by scrapers and gathering-collectors. The species found were tolerant to organic pollution.

  19. Glacial lake inventory and lake outburst potential in Uzbekistan. (United States)

    Petrov, Maxim A; Sabitov, Timur Y; Tomashevskaya, Irina G; Glazirin, Gleb E; Chernomorets, Sergey S; Savernyuk, Elena A; Tutubalina, Olga V; Petrakov, Dmitriy A; Sokolov, Leonid S; Dokukin, Mikhail D; Mountrakis, Giorgos; Ruiz-Villanueva, Virginia; Stoffel, Markus


    Climate change has been shown to increase the number of mountain lakes across various mountain ranges in the World. In Central Asia, and in particular on the territory of Uzbekistan, a detailed assessment of glacier lakes and their evolution over time is, however lacking. For this reason we created the first detailed inventory of mountain lakes of Uzbekistan based on recent (2002-2014) satellite observations using WorldView-2, SPOT5, and IKONOS imagery with a spatial resolution from 2 to 10m. This record was complemented with data from field studies of the last 50years. The previous data were mostly in the form of inventories of lakes, available in Soviet archives, and primarily included localized in-situ data. The inventory of mountain lakes presented here, by contrast, includes an overview of all lakes of the territory of Uzbekistan. Lakes were considered if they were located at altitudes above 1500m and if lakes had an area exceeding 100m(2). As in other mountain regions of the World, the ongoing increase of air temperatures has led to an increase in lake number and area. Moreover, the frequency and overall number of lake outburst events have been on the rise as well. Therefore, we also present the first outburst assessment with an updated version of well-known approaches considering local climate features and event histories. As a result, out of the 242 lakes identified on the territory of Uzbekistan, 15% are considered prone to outburst, 10% of these lakes have been assigned low outburst potential and the remainder of the lakes have an average level of outburst potential. We conclude that the distribution of lakes by elevation shows a significant influence on lake area and hazard potential. No significant differences, by contrast, exist between the distribution of lake area, outburst potential, and lake location with respect to glaciers by regions. Copyright © 2017 Elsevier B.V. All rights reserved.

  20. Seismic image of the Ivanhoe Lake Fault Zone in the Kapuskasing Uplift of the Canadian Shield (United States)

    Wu, Jianjun; Mereu, Robert F.; Percival, John A.


    The Kapuskasing uplift, located in the central Canadian shield, represents an oblique exposure of the Archean middle to lower crust. The Ivanhoe Lake fault zone, believed to be the basal thrust carrying the high-grade rocks of the Kapuskasing zone over the low-grade Abitibi greenstone belt, holds the key to understanding the nature and evolution of the Kapuskasing uplift. Despite numerous geological and geophysical studies, including LITHOPROBE deep seismic reflection profiles, and because of very limited bedrock exposure in the area, the shallow structure of the Ivanhoe Lake fault zone remains obscure. Here we present results obtained by reprocessing data from a LITHOPROBE seismic reflection profile across the fault zone. For the first time, the Ivanhoe Lake fault zone is clearly imaged on the seismic section as a series of west-dipping reflectors with an average dip of 20°, which can be traced to the surface. The results support the conclusion that fault zones form good reflectors.

  1. Methanotrophy within the water column of a large meromictic tropical lake (Lake Kivu, East Africa) (United States)

    Morana, C.; Borges, A. V.; Roland, F. A. E.; Darchambeau, F.; Descy, J.-P.; Bouillon, S.


    The permanently stratified Lake Kivu is one of the largest freshwater reservoirs of dissolved methane (CH4) on Earth. Yet CH4 emissions from its surface to the atmosphere have been estimated to be 2 orders of magnitude lower than the CH4 upward flux to the mixed layer, suggesting that microbial CH4 oxidation is an important process within the water column. A combination of natural abundance stable carbon isotope analysis (δ13C) of several carbon pools and 13CH4-labelling experiments was carried out during the rainy and dry season to quantify (i) the contribution of CH4-derived carbon to the biomass, (ii) methanotrophic bacterial production (MBP), and (iii) methanotrophic bacterial growth efficiency (MBGE), defined as the ratio between MBP and gross CH4 oxidation. We also investigated the distribution and the δ13C of specific phospholipid fatty acids (PLFAs), used as biomarkers for aerobic methanotrophs. Maximal MBP rates were measured in the oxycline, suggesting that CH4 oxidation was mainly driven by oxic processes. Moreover, our data revealed that methanotrophic organisms in the water column oxidized most of the upward flux of CH4, and that a significant amount of CH4-derived carbon was incorporated into the microbial biomass in the oxycline. The MBGE was variable (2-50%) and negatively related to CH4 : O2 molar ratios. Thus, a comparatively smaller fraction of CH4-derived carbon was incorporated into the cellular biomass in deeper waters, at the bottom of the oxycline where oxygen was scarce. The aerobic methanotrophic community was clearly dominated by type I methanotrophs and no evidence was found for an active involvement of type II methanotrophs in CH4 oxidation in Lake Kivu, based on fatty acids analyses. Vertically integrated over the water column, the MBP was equivalent to 16-60% of the average phytoplankton particulate primary production. This relatively high magnitude of MBP, and the substantial contribution of CH4-derived carbon to the overall

  2. Records from Lake Qinghai: Holocene climate history of Northeastern Tibetan Plateau linking to global change (United States)

    An, Z.; Colman, S.; Zhou, W.; Brown, E.; Li, X.; Jull, T.; Wang, S.; Liu, W.; Sun, Y.; Lu, X.; Song, Y.; Chang, H.; Cai, Y.; Xu, H.; Wang, X.; Liu, X.; Wu, F.; Han, Y.; Cheng, P.; Ai, L.; Wang, Z.; Qiang, X.; Shen, J.; Zhu, Y.; Wu, Z.; Liu, X.


    Lake Qinghai (99°36'-100°16'E, 36°32'-37°15'N ) of the north eastern margin of Tibet Plateau is the largest inland lake of China. It sits on the transitional zone of Asian monsoon- arid areas, receives influences of Asian monsoons and Westerlies, thus sensitive to global climate changes. Although previous studies had investigated Holocene climate change of Lake Qinghai area, it is rare to see precise Holocene climatic sequences of Lake Qinghai, nor in-depth discussions on controlling factors of Lake Qinghai climate changes. In Year 2005, with support from ICDP, Chinese Academy of Sciences (CAS), Chinese Ministry of Science and Technology (MOST) and National Science Foundation of China (NSFC), Drilling, Observation and Sampling of the Earths Continental Crust Corporation (DOSECC) and Institute of Earth Environment, Chinese Academy of Sciences (IEECAS) took a series of shallows cores from the southern basin of Lake Qinghai. West sub-basin sediments display Holocene lacustrine feature for the upper 5m, while the 5-18m are interbeded sediments of shallow lake, eolian-lacustrine and eolian loess. Chinese and US scientists with support from NSFC, MOST, CAS and NSF analysed 1F core from west sub-basin depocenter of the south basin with multiple physical, chemical, biological approaches. By comparing with modern process observation records, we obtained proxies that respectfully reflect precipitation, temperature and lake salinity changes, etc., reconstructed high resolution time sequences of magnetic susceptibility, colour scale, grain size, Corg, C/N, δ13Corg, carbonate, δ13C and δ18O of carbonate and ostracodes, elements, char-soot,Uk'37 and %C37:4 as well as pollen of the last 13Ka. They indicate the climatic change history of Lake Qinghai since past 13Ka, and agreeable evidences are found from adjacent tree ring and stalagmite records. Comparison of Lake Qinghai Holocene climate change sequence with those from high altitude ice core, stalagmites and ocean

  3. Pseudotachylytes of the Deep Crust: Examples from a Granulite-Facies Shear Zone (United States)

    Orlandini, O.; Mahan, K. H.; Regan, S.; Williams, M. L.; Leite, A.


    The Athabasca Granulite Terrane is an exhumed section of deep continental crust exposed in the western Canadian shield. The terrane hosts the 1.88 Ga Cora Lake shear zone, a 3-5 km wide sinistral and extensional oblique-slip system that was active at high-pressure granulite-grade conditions ( ~1.0 GPa, >800°C to ~0.8 GPa and 700 °C). Pseudotachylyte, a glassy vein-filling substance that results from frictional melting during seismic slip, is common in ultramylonitic strands of the shear zone, where veins run for tens of meters subparallel to foliation. Some but not all PST veins have been overprinted with the Cora Lake shear zone foliation, and undeformed PST locally bears microlitic garnet. The frictional melts that quench into PST may reach >1400 °C, but are extremely localized and cool to country rock temperatures within minutes, resulting in glass and/or microlitic mineral growths. The melt itself is thought by many to be in disequilibrium with the host rock due to its rapid nature, but during cooling equilibrium is probably reached at small scales. This allows for microprobe analysis of adjacent microlites for thermobarometric calculations. Preliminary results from undeformed (e.g., youngest of multiple generations) PST suggest that quenching occurred in upper amphibolite facies ambient conditions and is compatible with later stages of Cora Lake shear zone activity. Host-rock mylonites contain abundant garnet and pyroxene sigma clasts indicating sinistral shear, and where PST-bearing slip surfaces are found at low angles to the foliation, they display sinistral offset. The host rock contains abundant macroscopic and microscopic sinistral shear fracture systems (e.g., Riedel [R], Y, and P displacement surfaces) within the immediate proximity of PST veins, indicating a complex interplay of brittle and ductile behavior that is interpreted to be genetically related to the formation of the PST. The shear fracture systems are characterized by sharply bounded

  4. Reconstruction of food webs in biological soil crusts using metabolomics. (United States)

    Baran, Richard; Brodie, Eoin L.; Mayberry-Lewis, Jazmine; Nunes Da Rocha, Ulisses; Bowen, Benjamin P.; Karaoz, Ulas; Cadillo-Quiroz, Hinsby; Garcia-Pichel, Ferran; Northen, Trent R.


    Biological soil crusts (BSCs) are communities of organisms inhabiting the upper layer of soil in arid environments. BSCs persist in a dessicated dormant state for extended periods of time and experience pulsed periods of activity facilitated by infrequent rainfall. Microcoleus vaginatus, a non-diazotrophic filamentous cyanobacterium, is the key primary producer in BSCs in the Colorado Plateau and is an early pioneer in colonizing arid environments. Over decades, BSCs proceed through developmental stages with increasing complexity of constituent microorganisms and macroscopic properties. Metabolic interactions among BSC microorganisms probably play a key role in determining the community dynamics and cycling of carbon and nitrogen. However, these metabolic interactions have not been studied systematically. Towards this goal, exometabolomic analysis was performed using liquid chromatography coupled to tandem mass spectrometry on biological soil crust pore water and spent media of key soil bacterial isolates. Comparison of spent vs. fresh media was used to determine uptake or release of metabolites by specific microbes. To link pore water experiments with isolate studies, metabolite extracts of authentic soil were used as supplements for isolate exometabolomic profiling. Our soil metabolomics methods detected hundreds of metabolites from soils including many novel compounds. Overall, Microcoleus vaginatus was found to release and utilize a broad range of metabolites. Many of these metabolites were also taken up by heterotrophs but there were surprisingly few metabolites uptaken by all isolates. This points to a competition for a small set of central metabolites and specialization of individual heterotrophs towards a diverse pool of available organic nutrients. Overall, these data suggest that understanding the substrate specialization of biological soil crust bacteria can help link community structure to nutrient cycling.

  5. Continental crust anisotropy measurements from tectonic tremor in Cascadia (United States)

    Huesca-Pérez, Eduardo; Ortega, Roberto; Valenzuela, Raúl W.


    We present new observations of crustal anisotropy in the southern Cascadia fore arc from tectonic tremor. The abundance of tremor activity in Oregon and northern California during slow-slip events offers an enormous amount of information with which to measure and analyze anisotropy in the upper brittle continental crust. To accomplish this, we performed analyses of wave polarization and shear wave splitting of tectonic tremor signals by using three component broadband seismic stations. The splitting times range between 0.11 and 0.32 s and are consistent with typical values observed in the continental crust. Fast polarization azimuths are, in general, margin parallel and trend N-S, which parallels the azimuths of the maximum compressive stresses observed in this region. This pattern is likely to be controlled by the stress field. Comparatively, the anisotropic structure of fast directions observed in the northern section of the Cascadia margin is oblique with respect to the southern section of Cascadia, which, in general, trends E-W and is mainly controlled by active faulting and geological structures. Source distribution analysis using a bivariate normal distribution that expresses the distribution of tremors in a preferred direction shows that in northern California and Oregon, the population of tremors tends to distribute parallel to fast polarization azimuths and maximum compressive stresses, suggesting that both tremor propagation and anisotropy are influenced by the stress field. Results show that the anisotropy reflects an active tectonic process that involves the northward movement of the Oregon Block, which is rotating as a rigid body. In northern Cascadia, previous results of anisotropy show that the crust is undergoing a shortening process due to velocity differences between the Oregon Block and the North America plate, which is moving more slowly with respect to the Oregon Block, making it clash against Vancouver Island.

  6. Biomineralisation of the ferromanganese crusts in the Western Pacific Ocean (United States)

    Jiang, Xiao-Dong; Sun, Xiao-Ming; Guan, Yao; Gong, Jun-Li; Lu, Yang; Lu, Rong-Fei; Wang, Chi


    Ferromanganese (Fe-Mn) crusts are deep-sea sedimentary polymetallic minerals that are explored for their economic potential, particularly for Mn, Cu, Co, Ni and rare earth elements (REEs). The precipitation mechanism of the metallic elements in crusts has remained controversial between chemical oxidation (abiotic origin) and microbial enzymatic processes (biomineralization). In this study, the microbial mineralization in ferromanganese crusts from the Western Pacific Ocean was explored. Scanning electron microscope (SEM) and transmission electron microscope (TEM) analyses showed abundant micron-scale spherical aggregates of Mn-oxide filaments (20-80 nm), which are closely associated with filamentous cells within the biofilm (biofilm mineralization) exist within the stromatolitic structure. The high-throughput sequencing of 16S rRNA and phylogenetic analysis suggests that biofilms are dominated by three Mn-oxidizing bacterial species from the families Bacillus, Arthrobacter and Pseudomonas. In addition, Mn concentration in the biofilms is approximately 108 times that of the associated seawater (2.3 ppb Mn). Iron (16.2 wt%), Cu (0.11 wt%), Co (0.719 wt%) and Ni (0.459 wt%) were found in the biofilms via X-ray Fluorescence Spectrometer (XRF) and Inductively Coupled Plasma Mass Spectrometry (ICP-MS). We suggest that biomineralization provides a new perspective for understanding Fe-Mn crustal-related mineral deposits, and the ultra-high microbial trace element enrichment ability is noteworthy. Utilization of microbial activities in accumulating precious metals from seawater may offer a viable alternative for the world's metal production in the future.

  7. Tírez lake as a terrestrial analog of Europa. (United States)

    Prieto-Ballesteros, Olga; Rodríguez, Nuria; Kargel, Jeffrey S; Kessler, Carola González; Amils, Ricardo; Remolar, David Fernández


    Tírez Lake (La Mancha, central Spain) is proposed as a terrestrial analogue of Europa's ocean. The proposal is based on the comparison of the hydrogeochemistry of Tírez Lake with the geochemical features of the alteration mineralogy of meteoritic precursors and with Galileo's Near Infrared Mapping Spectrometer data on Europa's surface. To validate the astrobiological potential of Tírez Lake as an analog of Europa, different hydrogeochemical, mineral, and microbial analyses were performed. Experimental and theoretical modeling helped to understand the crystallization pathways that may occur in Europa's crust. Calculations about the oxidation state of the hypothetical Europan ocean were estimated to support the sulfate-rich neutral liquid model as the origin of Europa's observed hydrated minerals and to facilitate their comparison with Tírez's hydrogeochemistry. Hydrogeochemical and mineralogical analyses showed that Tírez waters corresponded to Mg-Na-SO(4)-Cl brines with epsomite, hexahydrite, and halite as end members. A preliminary microbial ecology characterization identified two different microbial domains: a photosynthetically sustained community represented by planktonic/benthonic forms and microbial mat communities, and a subsurficial anaerobic realm in which chemolithotrophy predominates. Fluorescence in situ hybridization has been used to characterize the prokaryotic diversity of the system. The subsurficial community seemed to be dominated by sulfate-reducing bacteria and methanogens. Frozen Tírez brines were analyzed by Fourier-transform infrared techniques providing spectra similar to those reported previously using pure components and to the Galileo spectral data. Calorimetric measurements of Tírez brines showed pathways and phase metastability for magnesium sulfate and sodium chloride crystallization that may aid in understanding the processes involved in the formation of Europa's icy crust. The use of fluorescence hybridization techniques for

  8. Evidence of Lake Trout reproduction at Lake Michigan's mid-lake reef complex (United States)

    Janssen, J.; Jude, D.J.; Edsall, T.A.; Paddock, R.W.; Wattrus, N.; Toneys, M.; McKee, P.


    The Mid-Lake Reef Complex (MLRC), a large area of deep (> 40 m) reefs, was a major site where indigenous lake trout (Salvelinus namaycush) in Lake Michigan aggregated during spawning. As part of an effort to restore Lake Michigan's lake trout, which were extirpated in the 1950s, yearling lake trout have been released over the MLRC since the mid-1980s and fall gill net censuses began to show large numbers of lake trout in spawning condition beginning about 1999. We report the first evidence of viable egg deposition and successful lake trout fry production at these deep reefs. Because the area's existing bathymetry and habitat were too poorly known for a priori selection of sampling sites, we used hydroacoustics to locate concentrations of large fish in the fall; fish were congregating around slopes and ridges. Subsequent observations via unmanned submersible confirmed the large fish to be lake trout. Our technological objectives were driven by biological objectives of locating where lake trout spawn, where lake trout fry were produced, and what fishes ate lake trout eggs and fry. The unmanned submersibles were equipped with a suction sampler and electroshocker to sample eggs deposited on the reef, draw out and occasionally catch emergent fry, and collect egg predators (slimy sculpin Cottus cognatus). We observed slimy sculpin to eat unusually high numbers of lake trout eggs. Our qualitative approaches are a first step toward quantitative assessments of the importance of lake trout spawning on the MLRC.

  9. The neutron star inner crust and symmetry energy

    CERN Document Server

    Grill, Fabrizio; Providência, Constança


    The cell structure of clusters in the inner crust of a cold \\beta-equilibrium neutron star is studied within a Thomas Fermi approach and compared with other approaches which include shell effects. Relativistic nuclear models are considered. We conclude that the symmetry energy slope L may have quite dramatic effects on the cell structure if it is very large or small. Rod-like and slab-like pasta clusters have been obtained in all models except one with a large slope L.

  10. Thermochemical structure of the Earth's mantle and continental crust

    DEFF Research Database (Denmark)

    Guerri, Mattia

    task. In this thesis, I adopt a multidisciplinary approach geared towards the unification of geochemical and geophysical constraints within a framework provided by theoretical and experimental mineral and rock physics. In the first part, I focus on the Continental crust, assessing the relations between...... elastic properties and chemical composition taking into account the thermal and pressure effects. I found that even small amounts of H2O have an extremely high impact on the elastic properties of crustal rock. In addition, I show the potential that modifications in the stable mineralogical assemblage have...

  11. Stability of Hall equilibria in neutron star crusts


    Marchant P.; Reisenegger A.; Valdivia J.A.; Hoyos J.H.


    In the solid crusts of neutron stars, the advection of the magnetic field by the current-carrying electrons, an effect known as Hall drift, should play a very important role as the ions remain essentially fixed (as long as the solid does not break). Although Hall drift preserves the magnetic field energy, it has been argued that it may drive a turbulent cascade to scales at which Ohmic dissipation becomes effective, allowing a much faster decay in objects with very strong fields. On the other...

  12. Lake Morphometry for NHD Lakes in Ohio Region 5 HUC (United States)

    U.S. Environmental Protection Agency — Lake morphometry metrics are known to influence productivity in lakes and are important for building various types of ecological and environmental models of lentic...

  13. Lake Morphometry for NHD Lakes in California Region 18 HUC (United States)

    U.S. Environmental Protection Agency — Lake morphometry metrics are known to influence productivity in lakes and are important for building various types of ecological and environmental models of lentic...

  14. Lake Morphometry for NHD Lakes in Tennessee Region 6 HUC (United States)

    U.S. Environmental Protection Agency — Lake morphometry metrics are known to influence productivity in lakes and are important for building various types of ecological and environmental models of lentic...


    African Journals Online (AJOL)

    Studies on phytoplankton species diversity and abundance were carried out in 8 selected satellite lakes within the Lake ... species of blue green algae such as Spirulina spp. are sources of ... scientific and conservation interests. This study ...

  16. Gold distribution in Archean continental crust: Evaluating the effects of intracrustal differentiation in the Tanzanian Craton (United States)

    Long, K.; Rudnick, R. L.; McDonough, W. F.; Manya, S.


    We have evaluated the vertical distribution of gold in variably metamorphosed igneous rocks in the Tanzanian Craton: 2.6 Ga upper-crustal greenschist-facies greenstone belt basalts and andesites from the Lake Victoria Gold Field of northern Tanzania, and compositionally similar 2.6 Ga lower-crustal mafic granulite-facies xenoliths that were carried in rift-related basalts that erupted nearby. We implemented the preconcentration method of Pitcairn et al. (2006), which utilizes chromatographic separation of gold from acid-digested rocks using diisobutyl ketone (DIBK), followed by standard addition ICP-MS to determine the distribution of gold in the crust. Repeat analyses of the certified reference material TDB-1, a whole-rock powder diabase dike from Tremblay Lake, Saskatchewan, Canada (certified gold concentration = 6.3 × 1.0 ng/g), yielded an average gold concentration of 6.5 × 1.1 ng/g. Results were reproducible to within 17% for rock powder aliquots between 200-600 mg (n=38), where 400 mg sample aliquots were reproducible to within 6% (n=9), and 600 mg aliquots were reproducible to within 4.5% (n=4). Better reproducibility for the greater sample aliquots likely reflects the 'nugget' effect. Rock samples in the 0.1-0.8 ng/g gold concentration range reproduced to within 27% for 400-600 mg sample aliquots. Although the lavas come from an area containing gold deposits, all were more than 5 km from any gold mine. The Tanzanian greenstone belt basalts have the highest gold concentrations (9 ng/g to 62 μg/g, ave. = 40 (+68/-25) ng/g, 1σ (n=10)), followed by the greenstone belt andesites (0.4 to 120 ng/g, ave. = 1.1 (+0.9/-0.5) ng/g, 1σ (n=14)). The lowest concentrations were observed in the granulite-facies lower-crustal xenoliths (0.1 to 3.3 ng/g, ave. = 0.3 (+0.3/-0.1) ng/g, 1σ (n=21)). Gold is incompatible in silicates and can partition into hydrothermal and/or magmatic fluid or vapour during high-grade metamorphic dehydration reactions or partial melting

  17. Formation of Fast-Spread Ocean Crust : Crystallographic Preferred Orientations From a Reference Lower Crust Section in the Oman Ophiolite (United States)

    Ildefonse, B.; Mueller, T.; Mock, D.; Koepke, J.


    About 20 years ago, two competing models were proposed for the formation of the lower, gabbroic crust at fast-spreading ridges. The lower crust is either formed by downward flow of mushy material from the shallow axial melt lens (gabbro glacier), or by sill intrusions (sheeted sills). To further test these end-member models, we characterized the vertical distribution of Crystallographic Preferred Orientations (CPO) in Wadi Gideah gabbro section (Sumail ophiolite, Sultanate Oman), using the Electron Backscattered Diffraction (EBSD) technique. CPO were measured on 67 gabbro samples, documenting a 5 km thick section, with an average interval of 80 m between samples. EBSD data sets were processed using MTEX, a free Matlab toolbox. Average misorientation in grains (angle between each pixel orientation and mean orientation of the grain) is very low ( 0.25°). This is consistent with magmatic flow in these rocks, and the paucity of crystal-plastic overprint. The strength (J index) of plagioclase CPO increases down-section, with a more pronounced variability in the layered gabbros. For clinopyroxene, the difference between upper (foliated) and lower (layered) gabbros is stronger, with low J in upper gabbros, and higher and more variable J in lower gabbros. In upper gabbros the symmetry of plagioclase and clinopyroxene CPO progressively evolves downward to progressively more oblate. Continuing down-section, the trend reverses, with progressively more prolate CPO in lower gabbros. The crystallographic fabric variability in the lower crust section calls for distinct formation mechanisms in the upper and lower gabbros. It is consistent with a hybrid model for crustal formation (Boudier et al., 1996, doi:10.1016/0012-821X(96)00167-7). The genesis of the upper foliated gabbro can be at least partly explained by the gabbro glacier model, while the continuous emplacement of sheeted sills at various depths is a more plausible model for the lower layered gabbro section.

  18. Lake Michigan lake trout PCB model forecast post audit (United States)

    Scenario forecasts for total PCBs in Lake Michigan (LM) lake trout were conducted using the linked LM2-Toxics and LM Food Chain models, supported by a suite of additional LM models. Efforts were conducted under the Lake Michigan Mass Balance Study and the post audit represents th...

  19. Mono Lake Excursion Reviewed (United States)

    Liddicoat, J. C.; Coe, R. S.


    The Mono Lake Excursion as recorded in the Mono Basin, CA, has an older part that is about negative 30 degrees inclination and about 300 degrees declination during low relative field intensity. Those paleomagnetic directions are closely followed by greater than 80 degrees positive inclination and east declination of about 100 degrees during higher relative field intensity. A path of the Virtual Geomagnetic Poles (VGPs) for the older part followed from old to young forms a large clockwise loop that reaches 35 degrees N latitude and is centered at about 35 degrees E longitude. That loop is followed by a smaller one that is counterclockwise and centered at about 70 degrees N latitude and 270 degrees E longitude (Denham & Cox, 1971; Denham, 1974; Liddicoat & Coe, 1979). The Mono Lake Excursion outside the Mono Basin in western North America is recorded as nearly the full excursion at Summer Lake, OR (Negrini et al., 1984), and as the younger portion of steep positive inclination/east declination in the Lahontan Basin, NV. The overall relative field intensity during the Mono Lake Excursion in the Lahontan Basin mirrors very closely the relative field intensity in the Mono Basin (Liddicoat, 1992, 1996; Coe & Liddicoat, 1994). Using 14C and 40Ar/39Ar dates (Kent et al., 2002) and paleoclimate and relative paleointensity records (Zimmerman et al., 2006) for the Mono Lake Excursion in the Mono Basin, it has been proposed that the Mono Lake Excursion might be older than originally believed and instead be the Laschamp Excursion at about 40,000 yrs B.P. (Guillou et al., 2004). On the contrary, we favor a younger age for the Mono Lake Excursion, about 32,000 yrs B.P., using the relative paleointensity in the Mono Basin and Lahontan Basin and 14C dates from the Lahontan Basin (Benson et al., 2002). The age of about 32,000 yrs B.P. is also in accord with the age (32,000- 34,000 yrs B.P.) reported by Channell (2006) for the Mono Lake Excursion at ODP Site 919 in the Irminger Basin

  20. Outer crust of a cold non-accreting magnetar

    CERN Document Server

    Basilico, D; Roca-Maza, X; Colò, G


    The outer crust structure and composition of a cold, non-accreting magnetar is studied. We model the outer crust to be made of fully equilibrated matter where ionized nuclei form a Coulomb crystal embedded in an electron gas. The main effects of the strong magnetic field are those of quantizing the electron motion in Landau levels and of modifying the nuclear single particle levels producing, on average, an increased binding of nucleons in nuclei present in the Coulomb lattice. The effect of an homogeneous and constant magnetic field on nuclear masses has been predicted by using a covariant density functional, in which induced currents and axial deformation due to the presence of a magnetic field that breaks time-reversal symmetry have been included self-consistently in the nucleon and meson equations of motion. Although not yet observed, for $B\\gtrsim 10^{16}$G both effects contribute to produce different compositions and to enlarge the range of pressures typically present in common neutron stars. Specifical...

  1. Magnetar activity mediated by plastic deformations of neutron star crust

    CERN Document Server

    Lyutikov, Maxim


    We advance a "Solar flare" model of magnetar activity, whereas a slow evolution of the magnetic field in the upper crust, driven by electron MHD (EMHD) flows, twists the external magnetic flux tubes, producing persistent emission, bursts and flares. At the same time the neutron star crust plastically relieves the imposed magnetic field stress, limiting the strain $ \\epsilon_t $ to values well below the critical strain $ \\epsilon_{crit}$ of a brittle fracture, $ \\epsilon_t \\sim 10^{-2}\\epsilon_{crit} $. Magnetar-like behavior, occurring near the magnetic equator, takes place in all neutron stars, but to a different extent. The persistent luminosity is proportional to cubic power of the magnetic field (at a given age), and hence is hardly observable in most rotationally powered neutron stars. Giant flares can occur only if the magnetic field exceeds some threshold value, while smaller bursts and flares may take place in relatively small magnetic fields. Bursts and flares are magnetospheric reconnection events t...

  2. Biological soil crusts as soil stabilizers: Chapter 16 (United States)

    Belnap, Jayne; Buedel, Burkhard; Weber, Bettina; Buedel, Burkhard; Belnap, Jayne


    Soil erosion is of particular concern in dryland regions, as the sparse cover of vascular plants results in large interspaces unprotected from the erosive forces of wind and water. Thus, most of these soil surfaces are stabilized by physical or biological soil crusts. However, as drylands are extensively used by humans and their animals, these crusts are often disturbed, compromising their stabilizing abilities. As a result, approximately 17.5% of the global terrestrial lands are currently being degraded by wind and water erosion. All components of biocrusts stabilize soils, including green algae, cyanobacteria, fungi, lichens, and bryophytes, and as the biomass of these organisms increases, so does soil stability. In addition, as lichens and bryophytes live atop the soil surface, they provide added protection from raindrop impact that cyanobacteria and fungi, living within the soil, cannot. Much research is still needed to determine the relative ability of individual species and suites of species to stabilize soils. We also need a better understanding of why some individuals or combination of species are better than others, especially as these organisms become more frequently used in restoration efforts.

  3. A Seafloor Microbial Biome Hosted within Incipient Ferromanganese Crusts

    Energy Technology Data Exchange (ETDEWEB)

    Templeton, Alexis S.; Knowles, A. S.; Eldridge, D. L.; Arey, Bruce W.; Dohnalkova, Alice; Webb, Samuel M.; Bailey, B. E.; Tebo, Bradley M.; Staudigel, Hubert


    Unsedimented volcanic rocks exposed on the seafloor at ridge systems and Seamounts host complex, abundant and diverse microbial communities that are relatively cosmopolitan in distribution (Lysnes, Thorseth et al. 2004; Mason, Stingl et al. 2007; Santelli, Orcutt et al. 2008). The most commonly held hypothesis is that the energy released by the hydration, dissolution and oxidative alteration of volcanic glasses in seawater drives the formation of an ocean crust biosphere (Thorseth, Furnes et al. 1992; Fisk, Giovannoni et al. 1998; Furnes and Staudigel 1999). The combined thermodynamically favorable weathering reactions could theoretically support anywhere from 105 to 109 cells/gram of rock depending upon the metabolisms utilized and cellular growth rates and turnover (Bach and Edwards 2003; Santelli, Orcutt et al. 2008). Yet microbially-mediated basalt alteration and energy conservation has not been directly demonstrated on the seafloor. By using synchrotron-based x-ray microprobe mapping, x-ray absorption spectroscopy and high-resolution scanning and transmission electron microscopy observations of young volcanic glasses recovered from the outer flanks of Loihi Seamount, we intended to identify the initial rates and mechanisms of microbial basalt colonization and bioalteration. Instead, here we show that microbial biofilms are intimately associated with ferromanganese crusts precipitating onto basalt surfaces from cold seawater. Thus we hypothesize that microbial communities colonizing seafloor rocks are established and sustained by external inputs of potential energy sources, such as dissolved and particulate Fe(II), Mn(II) and organic matter, rather than rock dissolution.

  4. Applicability of salt reduction strategies in pizza crust. (United States)

    Mueller, Eva; Koehler, Peter; Scherf, Katharina Anne


    In an effort to reduce population-wide sodium intake from processed foods, due to major health concerns, several different strategies for sodium reduction in pizza crust without any topping were evaluated by sensory analyses. It was possible to reduce sodium by 10% in one single step or to replace 30% of NaCl by KCl without a noticeable loss of salty taste. The late addition of coarse-grained NaCl (crystal size: 0.4-1.4 mm) to pizza dough led to an enhancement of saltiness through taste contrast and an accelerated sodium delivery measured in the mouth and in a model mastication simulator. Likewise, the application of an aqueous salt solution to one side of the pizza crust led to an enhancement of saltiness perception through faster sodium availability, leading to a greater contrast in sodium concentration. Each of these two strategies allowed a sodium reduction of up to 25% while maintaining taste quality. Copyright © 2015 Elsevier Ltd. All rights reserved.

  5. Tectonic escape in the evolution of the continental crust (United States)

    Burke, K.; Sengor, C.


    The continental crust originated by processes similar to those operating today and continents consist of material most of which originated long ago in arc-systems that have later been modified, especially at Andean margins and in continental collisions where crustal thickening is common. Collision-related strike-slip motion is a general process in continental evolution. Because buoyant continental (or arc) material generally moves during collision toward a nearby oceanic margin where less buoyant lithosphere crops out, the process of major strike-slip dominated motion toward a 'free-face' is called 'tectonic escape'. Tectonic escape is and has been an element in continental evolution throughout recorded earth-history. It promotes: (1) rifting and the formation of rift-basins with thinning of thickened crust; (2) pervasive strike-slip faulting late in orogenic history which breaks up mountain belts across strike and may juxtapose unrelated sectors in cross-section; (3) localized compressional mountains and related foreland-trough basins.

  6. Lake Erie Fish Community Data (United States)

    U.S. Geological Survey, Department of the Interior — Lake Erie Biological Station (LEBS), located in Sandusky, Ohio, is a field station of the USGS Great Lakes Science Center (GLSC). LEBS is the primary federal agency...

  7. Crescent Lake Wilderness Reference Sheet (United States)

    US Fish and Wildlife Service, Department of the Interior — Reference sheet includes information about Crescent Lake National Wildlife Refuge, and results of the public hearing for Crescent Lake Wilderness Proposal.

  8. Freshwater lake seabird surveys 2012 (United States)

    US Fish and Wildlife Service, Department of the Interior — The Alaska Peninsula/Becharof NWR complex hosts Becharof Lake, the largest lake within a National Wildlife Refuge system. In addition to this distinction, Becharof...

  9. Great Lakes Environmental Database (GLENDA) (United States)

    U.S. Environmental Protection Agency — The Great Lakes Environmental Database (GLENDA) houses environmental data on a wide variety of constituents in water, biota, sediment, and air in the Great Lakes area.

  10. Functional microbiology of soda lakes

    NARCIS (Netherlands)

    Sorokin, D.Y.; Banciu, H.L.; Muyzer, G.


    Soda lakes represent unique permanently haloalkaline system. Despite the harsh conditions, they are inhabited by abundant, mostly prokaryotic, microbial communities. This review summarizes results of studies of main functional groups of the soda lake prokaryotes responsible for carbon, nitrogen and

  11. Material Properties of Marine Hydrogenous Ferromanganese Crust and Its Performance in Desulfurization

    Institute of Scientific and Technical Information of China (English)


    Marine hydrogenous ferromanganese crust, an important metal resource in the future, has significant potential in various applications as a type of natural nano-structured material. By employing scanning electronic microscopy, nitrogen adsorption-desorption isotherm measurement, Xray fluorescence spectrometer and X-ray diffraction methods, the micro-structure, surface properties and chemical composition of several plate-like ferromanganese crusts sampled from the northwestern Pacific were investigated comprehensively. Although obvious differences were observed from different layers, the crust is a typical porous material with high specific surface area, unique pore structure and abundant transition elements. Furthermore, the performance of natural crust in desulfurization process was preliminarily tested in laboratory experiments. The sulfur capacities of the crust are 13.1%and 18.1% at room temperature and 350 ℃, respectively. The crust can be used not only as a metal resource, but also as an environmental material.

  12. Prilimary result of temperature distribution and associated thermal stress in crust in Tianshui, China

    Institute of Scientific and Technical Information of China (English)

    LIU Yao-wei; GAO An-tai; SHI Jin; SU He-jun


    The heat flow in crust and the thermal stress generated by the flow play a very important role in earthquake occurrence. Different crustal structure has different effect on heat distribution and associated thermal stress. In all of typical seismogenic crustal structure models, including the bulge of Moho surface, the deep-large fault in the mid-lower crust, low-velocity and high-conductive layer in the middle crust, and the typical crustal structure in mid-upper crust, the thermal stress produced by deep heat disturbance may move up to the mid-upper crust. This leads to upper brittle part of crust break and hence, strong earthquakes. This result is constructive in enhancing our understanding of the role of deep heat flow in curst in development of earthquake and its generation, as well as the generation mechanism of the shallow flowing fluid.

  13. Microplastic pollution in lakes and lake shoreline sediments - A case study on Lake Bolsena and Lake Chiusi (central Italy). (United States)

    Fischer, Elke Kerstin; Paglialonga, Lisa; Czech, Elisa; Tamminga, Matthias


    Rivers and effluents have been identified as major pathways for microplastics of terrestrial sources. Moreover, lakes of different dimensions and even in remote locations contain microplastics in striking abundances. This study investigates concentrations of microplastic particles at two lakes in central Italy (Lake Bolsena, Lake Chiusi). A total number of six Manta Trawls have been carried out, two of them one day after heavy winds occurred on Lake Bolsena showing effects on particle distribution of fragments and fibers of varying size categories. Additionally, 36 sediment samples from lakeshores were analyzed for microplastic content. In the surface waters 2.68 to 3.36 particles/m(3) (Lake Chiusi) and 0.82 to 4.42 particles/m(3) (Lake Bolsena) were detected, respectively. Main differences between the lakes are attributed to lake characteristics such as surface and catchment area, depth and the presence of local wind patterns and tide range at Lake Bolsena. An event of heavy winds and moderate rainfall prior to one sampling led to an increase of concentrations at Lake Bolsena which is most probable related to lateral land-based and sewage effluent inputs. The abundances of microplastic particles in sediments vary from mean values of 112 (Lake Bolsena) to 234 particles/kg dry weight (Lake Chiusi). Lake Chiusi results reveal elevated fiber concentrations compared to those of Lake Bolsena what might be a result of higher organic content and a shift in grain size distribution towards the silt and clay fraction at the shallow and highly eutrophic Lake Chiusi. The distribution of particles along different beach levels revealed no significant differences.

  14. Crusted Scabies: Presenting as erythroderma in a human immunodeficiency virus-seropositive patient

    Directory of Open Access Journals (Sweden)

    Shruti Kulkarni


    Full Text Available Crusted scabies is a rare manifestation of scabies characterized by uncontrolled proliferation of mites in the skin. It is common in patients with sensory neuropathy, mentally retarded persons and in patients who are immunosuppressed. Further, crusted scabies can rarely present as erythroderma (<0.5% cases necessitating a high index of suspicion for its diagnosis. Because of its rare occurrence, we are reporting a case of crusted scabies presenting as erythroderma, in a human immunodeficiency virus seropositive patient.

  15. Oxygen Distribution and Potential Ammonia Oxidation in Floating, Liquid Manure Crusts

    DEFF Research Database (Denmark)

    Nielsen, Daniel Aagren; Nielsen, Lars Peter; Schramm, Andreas;


    Floating, organic crusts on liquid manure, stored as a result of animal production, reduce emission of ammonia (NH3) and other volatile compounds during storage. The occurrence of NO2- and NO3- in the crusts indicate the presence of actively metabolizing NH3 oxidizing bacteria (AOB) which may...... microorganisms, including AOB. The microbial activity may thus contribute to a considerable reduction of ammonia emissions from slurry tanks with well-developed crusts....

  16. Impact of Crust Matter on Properties of Neutron Star with Supersoft Symmetry Energy

    Institute of Scientific and Technical Information of China (English)

    HUANG Qi-Zhi; WEN De-Hua


    By employing three typical equations of states (EOSs) of the crust matter, the effect of the crust on the structure and properties are investigated, where the core matter is described by the MDIxl model and the non-Newtonian gravity (described by the Yukawa contribution) is considered.It is shown that the EOSs of the crust matter have a notable effect on the mass-radius relation and the moment of inertia.

  17. Impact of neutron star crust on gravizational waves from the axial w-modes

    Institute of Scientific and Technical Information of China (English)

    Wen De-Hua; Fu Hong-Yang; Chen Wei


    The imprints of the neutron star crust on the gravitational waves emitted from the axial w-modes are investigated by adopting two typical equations of state (EOSs) of the crust matter and two representative EOSs of the core matter. It is shown that there is a significant effect of the crust EOSs on the gravitational waves from the axial w-mode oscillation for a stiff core EOS.

  18. Evidence for mechanical coupling and strong Indian lower crust beneath southern Tibet


    Copley, Alex; Avouac, Jean-Philippe; Wernicke, Brian P.


    How surface deformation within mountain ranges relates to tectonic processes at depth is not well understood. The upper crust of the Tibetan Plateau is generally thought to be poorly coupled to the underthrusting Indian crust because of an intervening low-viscosity channel. Here, however, we show that the contrast in tectonic regime between primarily strike-slip faulting in northern Tibet and dominantly normal faulting in southern Tibet requires mechanical coupling between the upper crust of ...

  19. Deep structure of the central Lesser Antilles Island Arc : relevance for the formation of continental crust


    H. Kopp; Weinzierl, W.; Becel, A.; Charvis, Philippe; Evain, M.; Flueh, E. R.; Gailler, A.; Galve, A.; Hirn, A.; Kandilarov, A.; D. Klaeschen; M. Laigle; Papenberg, C.; L. Planert; Roux, E.


    Oceanic island arcs are sites of high magma production and contribute to the formation of continental crust. Geophysical studies may provide information on the configuration and composition of island arc crust, however, to date only few seismic profiles exist across active island arcs, limiting our knowledge on the deep structure and processes related to the production of arc crust. We acquired active-source wide-angle seismic data crossing the central Lesser Antilles island arc north of Domi...

  20. Oxygen Distribution and Potential Ammonia Oxidation in Floating, Liquid Manure Crusts

    DEFF Research Database (Denmark)

    Nielsen, Daniel Aagren; Nielsen, Lars Peter; Schramm, Andreas


    Floating, organic crusts on liquid manure, stored as a result of animal production, reduce emission of ammonia (NH3) and other volatile compounds during storage. The occurrence of NO2- and NO3- in the crusts indicate the presence of actively metabolizing NH3 oxidizing bacteria (AOB) which may...... microorganisms, including AOB. The microbial activity may thus contribute to a considerable reduction of ammonia emissions from slurry tanks with well-developed crusts....

  1. A Lake Dream in Asia

    Institute of Scientific and Technical Information of China (English)

    Yang Wei


    @@ When William Wordsworth,representative of Lake Poets wrote his Ode to Night ingale nearby the Lake District of England at the turn of the nine-teenth century,he never imagined a century later,a similar romantic lake dream has been created in China,Asia.

  2. Interesting Ziandao Lake

    Institute of Scientific and Technical Information of China (English)


    LOCATED in Chun’an County, Zhejiang Province, Qiandao Lake (Lake of a Thousand Isles) is a state-level scenic spot and a bright pearl of the golden tourism line between Hangzhou’s West Lake and Anhui’s Huangshan Mountain. Last autumn, we went to Chun’an. It took only three to four hours by coach to travel from Hangzhou to Chun’an. Flanked by mountains on the west, the small county faces water on the east. A street goes across the county; it takes less than half an hour to walk from one end to the other. Small restaurants and shops line the western side of the road,

  3. Viruses in Antarctic lakes (United States)

    Kepner, R. L. Jr; Wharton, R. A. Jr; Suttle, C. A.; Wharton RA, J. r. (Principal Investigator)


    Water samples collected from four perennially ice-covered Antarctic lakes during the austral summer of 1996-1997 contained high densities of extracellular viruses. Many of these viruses were found to be morphologically similar to double-stranded DNA viruses that are known to infect algae and protozoa. These constitute the first observations of viruses in perennially ice-covered polar lakes. The abundance of planktonic viruses and data suggesting substantial production potential (relative to bacteria] secondary and photosynthetic primary production) indicate that viral lysis may be a major factor in the regulation of microbial populations in these extreme environments. Furthermore, we suggest that Antarctic lakes may be a reservoir of previously undescribed viruses that possess novel biological and biochemical characteristics.

  4. Lake Morphometry for NHD Lakes in Great Lakes Region 4 HUC (United States)

    U.S. Environmental Protection Agency — Lake morphometry metrics are known to influence productivity in lakes and are important for building various types of ecological and environmental models of lentic...

  5. Fractal characteristics of resource quantity of cobalt crusts and seamount topography, the West Pacific

    Institute of Scientific and Technical Information of China (English)

    ZHANG Weiyan; ZHANG Fuyuan; YANG Kehong; HU Guangdao; YANG Shengxiong; CHENG Yongshou; ZHAO Guojun


    This paper presents the fractal distribution of topography of seamounts from the West Pacific and the resource quantity of cobalt crust therein. The cobalt resource quantity has three to four variable fractal dimensions, corre- sponding to the distinct slopes and water depths of the sea- mount. The multiple fractal property of resource quantity may have resulted from various factors, such as types and components of cobalt crusts and ages of oceanic crusts host- ing the seamounts. Individual seamounts display complex topography and quantity of cobalt crust, both in the same and different regions.

  6. Ecological and environmental explanation of microbiotic crusts on sand dune scales in the Gurbantonggut Desert, Xinjiang

    Institute of Scientific and Technical Information of China (English)

    CHEN Yaning; LI Weihong; ZHOU Zhibing; LIU Jiazhen


    Results obtained from the field investigation and the analysis in laboratory show that many species of microbiotic crusts of lichens, mosses and algae develop extensively in the Gurbantonggut Desert, Xinjiang. The formation, species and distribution are closely related to the environmental conditions at the different positions of sand dunes. The animalcule crusts develop mainly on the mobile or semi-mobile sand surface of dune tops, the alga crusts develop mainly at the upper to middle parts of dune slopes, the lichen crusts develop at middle and lower parts of dune slopes, and the moss crusts are mainly distributed at the lower part of dune slopes and the interdune lowlands. The species, thickness and developing degree of microbiotic crusts increase from the upper part to the middle and lower parts of dune slopes and the interdune lowlands, and an obvious contrast between the microbiotic crusts and the different species of plant communities forms. The development and differentiation of microbiotic crusts at the different positions of dunes are the ecological appearance and the natural selection of synthetic adaptability of the different microbiotic crust species to the local environmental conditions, and are closely related to the ecological conditions, such as the physiochemical properties of soils and stability of topsoil texture.

  7. Influence of the symmetry energy on nuclear pasta in neutron star crusts

    CERN Document Server

    Bao, S S


    We investigate the effects of the symmetry energy on nuclear pasta phases and the crust-core transition in neutron stars. We employ the relativistic mean-field approach and the coexisting phases method to study the properties of pasta phases presented in the inner crust of neutron stars. It is found that the slope of the nuclear symmetry energy at saturation density plays an important role in the crust-core transition and pasta phase properties. The correlation between the symmetry energy slope and the crust-core transition density obtained in this study is consistent with those obtained by other methods.

  8. Cobalt- and platinum-rich ferromanganese crusts and associated substrate rocks from the Marshall Islands (United States)

    Hein, J.R.; Schwab, W.C.; Davis, A.


    Ferromanganese crusts cover most hard substrates on seafloor edifices in the central Pacific basin. Crust samples and their associated substrates from seven volcanic edifices of Cretaceous age along the Ratak chain of the Marshall Islands are discussed. The two most abundant substrate lithologies recovered were limestone, dominantly fore-reef slope deposits, and volcanic breccia composed primarily of differentiated alkalic basalt and hawaiite clasts in a phosphatized carbonate matrix. The degree of mass wasting on the slopes of these seamounts is inversely correlated with the thickness of crusts. Crusts are generally thin on limestone substrate. Away from areas of active mass-wasting processes, and large atolls, crusts may be as thick as 10 cm maximum. The dominant crystalline phase in the Marshall Islands crusts is ??-MnO2 (vernadite). High concentrations of cobalt, platinum and rhodium strongly suggest that the Marshall Islands crusts are a viable source for these important metals. Many metals and the rare earth elements vary significantly on a fine scale through most crusts, thus reflecting the abundances of different host mineral phases in the crusts and changes in seawater composition with time. High concentrations of cobalt, nickel, titanium, zinc, lead, cerium and platinum result from a combination of their substitution in the iron and manganese phases and their oxidation potential. ?? 1988.

  9. Methanotrophs, methanogens, and microbial community structure in livestock slurry surface crusts

    DEFF Research Database (Denmark)

    Duan, Yun-Feng (Kevin); Abu Al-Soud, Waleed; Brejnrod, Asker Daniel


    , dominated the MOB community, whereas Methanocorpusculum was the predominant methanogen. Higher numbers of OTUs representing Type I than Type II MOB were found in all crusts. Potential CH4 oxidation rates were determined by incubations of crusts with CH4, and CH4 oxidization was observed in cattle......, but not in swine slurry crusts. Conclusions: Slurry surface crusts harbor a diverse microbial community. Type I MOB are more diverse and abundant than Type II MOB in this environment. The distinct CH4 oxidation rates could be related to microbial compositions. Significance and Impact of Study: This study...

  10. The Significance of Crust Structure and Continental Dynamics Inferred from Receiver Functions in West Yunnan

    Institute of Scientific and Technical Information of China (English)

    HE Chuansong; ZHU Lupei; WANG Qingcai


    In our study we collected the teleseismic record of 31 broadband stations and 9 PASSCAL stations in West Yunnan, as well as extracted more than a million receiver functions. Using the waveform model and stacking techniques, we calculated the earth crust thicknesses and V_p/V_s ratios below the stations and obtained 35 valid data points. At the same time, we evenly stacked the receiver functions at the same station and superimposed the two profiles' cross sections of the main tectonic units. The results show a clear difference between the crust thicknesses of different tectonic units. Because of the magma underplatting and delimanition of the lower crust in the role of deep process, the West Yunnan's crust can be divided two kinds-mafic-uitramafic and feidspathic crusts. The research also shows that the mafic-ultramafic crust corresponds to a good background of mineralization. The delamination of the lower crust is one of the leading causes for moderate to strong earthquake prone in central Yunnan. The thinner crust and high velocity ratio as well as the muitimodal structure of P_s in the Tengchong volcanic area confirms existence of a deep process of the strong magma underplating. Due to the basic crust structure and nature, it is believed that the Honghe fault is a main suture of the Gondwana and Eurasia continents.

  11. Estimating ungauged catchment flows from Lake Tana floodplains, Ethiopia: an isotope hydrological approach. (United States)

    Kebede, Seifu; Admasu, Girum; Travi, Yves


    The isotope balance approach, which used (18)O content of waters, has been used as an independent tool to estimate inflow to Lake Tana of surface water flows from ungauged catchment of Lake Tana (50% of the total area) and evaporative water loss in the vast plains adjoining the lake. Sensitivity analysis has been conducted to investigate the effects of changes in the input parameters on the estimated flux. Surface water inflow from ungauged catchment is determined to be in the order of 1.698×10(9) m(3)a(-1). Unaccounted water loss from the lake has been estimated at 454×10(6) m(3)a(-1) (equivalent to 5% of the total via surface water). Since the lake is water tight to groundwater outflow, the major error introduced into the water balance computation is related to evaporative water loss in water from the flood plains. If drained, the water which is lost to evaporation can be used as an additional water resource for socio-economic development in the region (tourism, agriculture, hydropower, and navigation). Hydrological processes taking place in the vast flood plains of Lake Tana (origin of salinity, groundwater surface water interaction, origin of flood plain waters) have been investigated using isotopes of water and geochemistry as tracers. The salinity of shallow groundwaters in the flood plains is related to dissolution of salts accumulated in sediments covering former evaporation pools and migration of trace salt during recharge. The waters in the flood plains originate from local rainfall and river overflows and the effect of backwater flow from the lake is excluded. Minimum linkage exists between the surface waters in the flood plains and shallow groundwaters in alluvio lacustrine sediments suggesting the disappearance of flood waters following the rainy season, which is related to complete evaporation or drainage than seepage to the subsurface. There is no groundwater outflow from the lake. Inflow of groundwater cannot be ruled out. Discharge of groundwater

  12. Pollination Technique of Pitaya with Red Pericarp and Flesh in Rainy Season%红肉型火龙果雨季授粉技术研究

    Institute of Scientific and Technical Information of China (English)

    赵志平; 张阳梅


    为减少降雨对火龙果产量造成的损失,探索红肉型火龙果雨季授粉技术,比较了不同降雨类型气候条件下,套袋授粉和自然授粉对火龙果产量和品质的影响.结果表明,与自然授粉相比,红肉型火龙果雨季套袋授粉后,座果率提高18.89%~51.67%,平均单果重提高181.79~201.77 g,增产23006.55~27073.95 kg/hm2,为自然授粉处理的2.63~4.19倍;套袋授粉还促进了火龙果的果实发育,增加了一、二级商品果比率,每公顷比对照净增收18.92~20.62万元,增幅达240.7 %~433.2%,大幅提升了火龙果种植效益,同时对火龙果的内在品质无影响.雨季套袋授粉在生产上是简便、有效、经济、可操作性强的一项技术措施.%In order to reduce yield losses because of rainfall, pollination techniques of pitaya with red pericarp and flesh in rainy season was explored. The effects of different pollination treatments on the yield and quality of pitaya were clarified in different types of rainfall climatic conditions. Compared with natural pollination, pollination with bagging treatment increased fruit-set rate of 18.89%~51.67%, the average weight of 181.79~201.77 g and yield 23 006.55-27 073.95 kg/hm2. Pollination with bagging not only promoted pitaya development but also made higher percentage of commercial fruit and yield as well as economic benefits. The net income over the CK was 189 200-206 200 Yuan/hm2, an increase rate of 240.7%~433.2%. The bagging pollination technique of pitaya with red pericarp and flesh in rainy season is simple, high efficiency and operable.

  13. Evaluation of the efficiency of the photo Fenton disinfection of natural drinking water source during the rainy season in the Sahelian region. (United States)

    Ndounla, J; Pulgarin, C


    The photo-disinfection of water from two different wells (W1, pH: 4.6-5.1 ± 0.02) and (W2 pH: 5.6-5.7 ± 0.02) was carried out during the rainy season at Ouagadougou-Burkina Faso, West Africa. The weather variation during the rainy season significantly affects the photo-disinfection processes (solar disinfection and photo-Fenton). The dilution of the water by rainwater highly affected the chemical composition of the wells' water used in this study; very low iron contents Compared to the ones recorded during the dry season were recorded in all water samples. Both photo-disinfection processes were used to treat 25 L of water in a compound parabolic collector (CPC). None of them have shown the total inactivation of both wild enteric bacteria strains (total coliforms/E. coli and Salmonella spp.) involved in the treatment. However, the total coliforms/E. coli strains were totally inactivated during the exposure under most of the photo-Fenton treatment. Also, the remaining strains, especially those of Salmonella spp. were achieved during the subsequent 24h of dark storage under the action of the Fenton process. Under uniquely solar radiation, total inactivation was recorded only in the total coliforms/E. coli strains. The impact of the available irradiance on the efficiency of the photo-Fenton disinfection of natural water was highlighted during the exposure under high intermittent solar radiation. The impact of the HCO3(-) concentration of both wells' water on the evolution of the pH during the photo-disinfection was recorded. Drastic decrease was noticed after the initial fast increase in presence of low HCO3(-) concentration while a steady state was observed after the increase in presence of higher concentration. The redox activities of the nitrogen components of the water during both photo-disinfection processes have led to increased concentration of nitrite in all the cases and variations were noticed in that of nitrate and ammonia.

  14. The 2007 Nazko, British Columbia, earthquake sequence: Injection of magma deep in the crust beneath the Anahim volcanic belt (United States)

    Cassidy, J.F.; Balfour, N.; Hickson, C.; Kao, H.; White, Rickie; Caplan-Auerbach, J.; Mazzotti, S.; Rogers, Gary C.; Al-Khoubbi, I.; Bird, A.L.; Esteban, L.; Kelman, M.; Hutchinson, J.; McCormack, D.


    On 9 October 2007, an unusual sequence of earthquakes began in central British Columbia about 20 km west of the Nazko cone, the most recent (circa 7200 yr) volcanic center in the Anahim volcanic belt. Within 25 hr, eight earthquakes of magnitude 2.3-2.9 occurred in a region where no earthquakes had previously been recorded. During the next three weeks, more than 800 microearthquakes were located (and many more detected), most at a depth of 25-31 km and within a radius of about 5 km. After about two months, almost all activity ceased. The clear P- and S-wave arrivals indicated that these were high-frequency (volcanic-tectonic) earthquakes and the b value of 1.9 that we calculated is anomalous for crustal earthquakes but consistent with volcanic-related events. Analysis of receiver functions at a station immediately above the seismicity indicated a Moho near 30 km depth. Precise relocation of the seismicity using a double-difference method suggested a horizontal migration at the rate of about 0:5 km=d, with almost all events within the lowermost crust. Neither harmonic tremor nor long-period events were observed; however, some spasmodic bursts were recorded and determined to be colocated with the earthquake hypocenters. These observations are all very similar to a deep earthquake sequence recorded beneath Lake Tahoe, California, in 2003-2004. Based on these remarkable similarities, we interpret the Nazko sequence as an indication of an injection of magma into the lower crust beneath the Anahim volcanic belt. This magma injection fractures rock, producing high-frequency, volcanic-tectonic earthquakes and spasmodic bursts.

  15. Technologies for lake restoration

    Directory of Open Access Journals (Sweden)

    Helmut KLAPPER


    Full Text Available Lakes are suffering from different stress factors and need to be restored using different approaches. The eutrophication remains as the main water quality management problem for inland waters: both lakes and reservoirs. The way to curb the degradation is to stop the nutrient sources and to accelerate the restoration with help of in-lake technologies. Especially lakes with a long retention time need (eco- technological help to decrease the nutrient content in the free water. The microbial and other organic matter from sewage and other autochthonous biomasses, causes oxygen depletion, which has many adverse effects. In less developed countries big reservoirs function as sewage treatment plants. Natural aeration solves problems only partly and many pollutants tend to accumulate in the sediments. The acidification by acid rain and by pyrite oxidation has to be controlled by acid neutralizing technologies. Addition of alkaline chemicals is useful only for soft waters, and technologies for (microbial alkalinization of very acidic hardwater mining lakes are in development. The corrective measures differ from those in use for eutrophication control. The salinization and water shortage mostly occurs if more water is used than available. L. Aral, L. Tschad, the Dead Sea or L. Nasser belong to waters with most severe environmental problems on a global scale. Their hydrologic regime needs to be evaluated. The inflow of salt water at the bottom of some mining lakes adds to stability of stratification, and thus accumulation of hydrogen sulphide in the monimolimnion of the meromictic lakes. Destratification, which is the most used technology, is only restricted applicable because of the dangerous concentrations of the byproducts of biological degradation. The contamination of lakes with hazardous substances from industry and agriculture require different restoration technologies, including subhydric isolation and storage, addition of nutrients for better self

  16. Lakes on Mars

    CERN Document Server

    Cabrol, Nathalie A


    On Earth, lakes provide favorable environments for the development of life and its preservation as fossils. They are extremely sensitive to climate fluctuations and to conditions within their watersheds. As such, lakes are unique markers of the impact of environmental changes. Past and current missions have now demonstrated that water once flowed at the surface of Mars early in its history. Evidence of ancient ponding has been uncovered at scales ranging from a few kilometers to possibly that of the Arctic ocean. Whether life existed on Mars is still unknown; upcoming missions may find critic

  17. Reevaluation of lake trout and lake whitefish bioenergetics models (United States)

    Madenjian, Charles P.; Pothoven, Steve A.; Kao, Yu-Chun


    Using a corrected algorithm for balancing the energy budget, we reevaluated the Wisconsin bioenergetics model for lake trout (Salvelinus namaycush) in the laboratory and for lake whitefish (Coregonus clupeaformis) in the laboratory and in the field. For lake trout, results showed that the bioenergetics model slightly overestimated food consumption by the lake trout when they were fed low and intermediate rations, whereas the model predicted food consumption by lake trout fed ad libitum without any detectable bias. The slight bias in model predictions for lake trout on restricted rations may have been an artifact of the feeding schedule for these fish, and we would therefore recommend application of the Wisconsin lake trout bioenergetics model to lake trout populations in the field without any revisions to the model. Use of the Wisconsin bioenergetics model for coregonids resulted in overestimation of food consumption by lake whitefish both in the laboratory and in the field by between 20 and 30%, on average. This overestimation of food consumption was most likely due to overestimation of respiration rate. We therefore adjusted the respiration component of the bioenergetics model to obtain a good fit to the observed consumption in our laboratory tanks. The adjusted model predicted the consumption in the laboratory and the field without any detectable bias. Until a detailed lake whitefish respiration study can be conducted, we recommend application of our adjusted version of the Wisconsin generalized coregonid bioenergetics model to lake whitefish populations in the field.

  18. New Tracers of Gas Migration in the Continental Crust

    Energy Technology Data Exchange (ETDEWEB)

    Kurz, Mark D. [Woods Hole Oceanographic Inst., MA (United States)


    Noble gases are exceptional tracers in continental settings due to the remarkable isotopic variability between the mantle, crust, and atmosphere, and because they are inert. Due to systematic variability in physical properties, such as diffusion, solubility, and production rates, the combination of helium, neon, and argon provides unique but under-utilized indices of gas migration. Existing noble gas data sets are dominated by measurements of gas and fluid phases from gas wells, ground waters and hot springs. There are very few noble gas measurements from the solid continental crust itself, which means that this important reservoir is poorly characterized. The central goal of this project was to enhance understanding of gas distribution and migration in the continental crust using new measurements of noble gases in whole rocks and minerals from existing continental drill cores, with an emphasis on helium, neon, argon. We carried out whole-rock and mineral-separate noble gas measurements on Precambrian basement samples from the Texas Panhandle. The Texas Panhandle gas field is the southern limb of the giant Hugoton-Panhandle oil and gas field; it has high helium contents (up to ~ 2 %) and 3He/4He of 0.21 (± 0.03) Ra. Because the total amount of helium in the Panhandle gas field is relatively well known, crustal isotopic data and mass balance calculations can be used to constrain the ultimate source rocks, and hence the helium migration paths. The new 3He/4He data range from 0.03 to 0.11 Ra (total), all of which are lower than the gas field values. There is internal isotopic heterogeneity in helium, neon, and argon, within all the samples; crushing extractions yield less radiogenic values than melting, demonstrating that fluid inclusions preserve less radiogenic gases. The new data suggest that the Precambrian basement has lost significant amounts of helium, and shows the importance of measuring helium with neon and argon. The 4He/40Ar values are particularly useful

  19. Composition and origin of Archean lower crust, Northern Tanzania (United States)

    Mansur, A. T.; Manya, S.; Rudnick, R.


    Granulite-facies xenoliths from tuff cones erupted on the margin of the Tanzanian craton and within the adjacent Mozambique belt in northern Tanzania offer an opportunity to assess the role of lower crustal processes in the tectonic evolution of these two terranes. Both terranes are Archean, but record very different histories, starting in the Proterozoic and continuing today. Whereas the craton experienced little metamorphism or igneous activity following its stabilization around 2.8 Ga, Archean rocks of the Mozambique belt in the study area experienced at least one episode of high-grade metamorphism during the East African orogeny (ca. 640 Ma). Today, the East African rift exists at the contact between the Mozambique belt and the craton, implying a fundamental lithospheric weakness at this boundary. Granulite xenoliths come from Labait, on the craton margin, and Lashaine and Naibor Soito in the metamorphic belt. Most xenoliths are mafic and all are igneous in origin. Cratonic xenoliths (pl- opx±cpx±gt±hbl) are primarily anhydrous two-pyroxene granulites that likely originated as crystallized high-Ni, Archean basaltic melts. Xenoliths from the Mozambique belt are dominated by mafic granulites (pl-cpx-gt±opx) at Lashaine and banded, mafic to intermediate granulites at Naibor Soito. Positive Sr and Eu anomalies imply that the Lashaine granulites originated as plagioclase cumulates. The wide range in SiO2 (47-65 wt%) and correlation of Ni-MgO in the Naibor Soito xenoliths suggests they may have originated as igneous rocks that subsequently underwent partial melting to form the mafic (pl- opx±cpx±gt±hbl±bt) and felsic bands (pl-qtz-opx±kfs). U-Pb zircon ages for xenoliths from both terranes are Archean, as are most TDM ages, though younger TDM ages are seen in some Lashaine samples that were contaminated by rift magma. High pressures (up to 2.7GPa) are recorded by the Mozambique belt xenoliths, suggesting equilibration in thickened crust during the East

  20. Biotic Spectrum of Chando Lake in Context of Ecological Status and Zooplankton Diversity

    Directory of Open Access Journals (Sweden)

    Anuradha Shukla


    Full Text Available Covering an area of approximate 650 ha, Chando Lake is located in South East of Basti, (U.P.. No precise study regarding its hydrobiology has been conducted. Hence, present study has been undertaken to observe its ecological status and zooplankton diversity from June 2010 to May 2012. The early mean flow in this lake relied on rains and the mean annual rain fall was recorded to be 1094 cm with in 51 average rainy days. The average value of the temperature was recorded to be 28.46°C, pH 7.38, transparency 58.52 cm, DO 6024 mg/L, free CO2 3.70 mg/L, TDS 1 52.20 mg/L, total hardness 153.69 mg/L , total alkalinity 272.44 mg/L , Nitrate 7.11 mg/L, phosphate 0.83 mg/L and chloride 34.63 mg/L. In the present study 23 species of zooplankton were noticed out of which six species belong to cladocerans, six species of copepods, four species of protozoans and seven species of rotiferans. The study of zooplankton species diversity and abundance with respect to biotic factors may assist in future planning for the management of intensive fish culture in this vast lake.

  1. Lake whitefish diet, condition, and energy density in Lake Champlain and the lower four Great Lakes following dreissenid invasions (United States)

    Herbst, Seth J.; Marsden, J. Ellen; Lantry, Brian F.


    Lake Whitefish Coregonus clupeaformis support some of the most valuable commercial freshwater fisheries in North America. Recent growth and condition decreases in Lake Whitefish populations in the Great Lakes have been attributed to the invasion of the dreissenid mussels, zebra mussels Dreissena polymorpha and quagga mussels D. bugensis, and the subsequent collapse of the amphipod, Diporeia, a once-abundant high energy prey source. Since 1993, Lake Champlain has also experienced the invasion and proliferation of zebra mussels, but in contrast to the Great Lakes, Diporeia were not historically abundant. We compared the diet, condition, and energy density of Lake Whitefish from Lake Champlain after the dreissenid mussel invasion to values for those of Lake Whitefish from Lakes Michigan, Huron, Erie, and Ontario. Lake Whitefish were collected using gill nets and bottom trawls, and their diets were quantified seasonally. Condition was estimated using Fulton's condition factor (K) and by determining energy density. In contrast to Lake Whitefish from some of the Great Lakes, those from Lake Champlain Lake Whitefish did not show a dietary shift towards dreissenid mussels, but instead fed primarily on fish eggs in spring, Mysis diluviana in summer, and gastropods and sphaeriids in fall and winter. Along with these dietary differences, the condition and energy density of Lake Whitefish from Lake Champlain were high compared with those of Lake Whitefish from Lakes Michigan, Huron, and Ontario after the dreissenid invasion, and were similar to Lake Whitefish from Lake Erie; fish from Lakes Michigan, Huron, and Ontario consumed dreissenids, whereas fish from Lake Erie did not. Our comparisons of Lake Whitefish populations in Lake Champlain to those in the Great Lakes indicate that diet and condition of Lake Champlain Lake Whitefish were not negatively affected by the dreissenid mussel invasion.

  2. Biological soil crusts: Diminutive communities of potential global importance (United States)

    Ferrenberg, Scott; Tucker, Colin; Reed, Sasha C.


    Biological soil crusts (biocrusts) are widespread, diverse communities of cyanobacteria, fungi, lichens, and mosses living on soil surfaces, primarily in drylands. Biocrusts can locally govern primary production, soil fertility, hydrology, and surface energy balance, with considerable variation in these functions across alternate community states. Further, these communities have been implicated in Earth system functioning via potential influences on global biogeochemistry and climate. Biocrusts are easily destroyed by disturbances and appear to be exceptionally vulnerable to warming temperatures and altered precipitation inputs, signaling possible losses of dryland functions with global change. Despite these concerns, we lack sufficient spatiotemporal data on biocrust function, cover, and community structure to confidently assess their ecological roles across the extensive dryland biome. Here, we present the case for cross-scale research and restoration efforts coupled with remote-sensing and modeling approaches that improve our collective understanding of biocrust responses to global change and the ecological roles of these diminutive communities at global scales.

  3. Magnetic field decay with Hall drift in neutron star crusts

    CERN Document Server

    Kojima, Yasufumi


    The dynamics of magnetic field decay with Hall drift is investigated. Assuming that axisymmetric magnetic fields are located in a spherical crust with uniform conductivity and electron number density, long-term evolution is calculated up to Ohmic dissipation. The nonlinear coupling between poloidal and toroidal components is explored in terms of their energies and helicity. Nonlinear oscillation by the drift in strongly magnetized regimes is clear only around the equipartition between two components. Significant energy is transferred to the poloidal component when the toroidal component initially dominates. However, the reverse is not true. Once the toroidal field is less dominant, it quickly decouples due to a larger damping rate. The polar field at the surface is highly distorted from the initial dipole during the Hall drift timescale, but returns to the initial dipole in a longer dissipation timescale, since it is the least damped one.

  4. Dating low-temperature alteration of the upper oceanic crust (United States)

    Coogan, L. A.; Hinton, R. W.; Gillis, K. M.; Dosso, S. E.


    Off-axis hydrothermal systems lead to extensive chemical exchange between the oceans and upper oceanic crust but it is unclear when this exchange occurs. We address this using a new dating approach and via the re-evaluation of existing data that contain age information. We have developed a method to directly date adularia, a common alkali-rich phase in old oceanic crust, using the 40K to 40Ca radiogenic decay system. In situ analysis, using the Cameca 1270 ion microprobe at the University of Edinburgh, allows small, replacive, secondary mineral grains to be analyzed. In comparison to previous radiogenic dating of low-temperature secondary minerals, using Rb-Sr and K-Ar approaches on mineral separates, this approach has the advantages that: (i) analysis is not limited to large, void filling, grains; (ii) the initial isotopic ratio is well constrained; (iii) contamination and phase heterogeneity are minimized; and (iv) the daughter isotope is relatively immobile. However, the requirement to analyse doubly charged ions, to reduce molecular interferences and suppress the presence of 40K on 40Ca, leads to low count rates [1]; e.g. single spot ages have uncertainties of 10's of millions of years. Combining all analyses for a given sample gives best fitting instantaneous precipitation "ages" of 102 and 70 Myr for DSDP Holes 417A and 543A (versus crustal ages of 120 and 80 Myr). The scatter in the data are consistent with adularia precipitation over >30 Myr. The timing of carbonate precipitation in the upper oceanic crust can be constrained from comparison of their 87Sr/86Sr to the seawater Sr-isotope curve if the proportion of basaltic Sr in the fluid can be constrained. Modeling such data from 12 drill cores shows that they are best fit by a model in which >90% of carbonate precipitation occurs over ≤20 Myr after crustal formation [2]. Evaluation of published Rb-Sr "isochron" data [3,4] shows that these data can be explained in different ways. The "isochron

  5. Superfluid hydrodynamics in the inner crust of neutron stars

    CERN Document Server

    Martin, Noël


    The inner crust of neutron stars is supposed to be inhomogeneous and composed of dense structures (clusters) that are immersed in a dilute gas of unbound neutrons. Here we consider spherical clusters forming a BCC crystal and cylindrical rods arranged in a hexagonal lattice. We study the relative motion of these dense structures and the neutron gas using superfluid hydrodynamics. Within this approach, which relies on the assumption that Cooper pairs are small compared to the crystalline structures, we find that the entrainment of neutrons by the clusters is very weak since neutrons of the gas can flow through the clusters. Consequently, we obtain a low effective mass of the clusters and a superfluid density that is even higher than the density of unbound neutrons. Consequences for the constraints from glitch observations are discussed.

  6. Superfluid hydrodynamics in the inner crust of neutron stars (United States)

    Martin, Noël; Urban, Michael


    The inner crust of neutron stars is supposed to be inhomogeneous and composed of dense structures (clusters) that are immersed in a dilute gas of unbound neutrons. Here we consider spherical clusters forming a body-centered cubic (BCC) crystal and cylindrical rods arranged in a hexagonal lattice. We study the relative motion of these dense structures and the neutron gas using superfluid hydrodynamics. Within this approach, which relies on the assumption that Cooper pairs are small compared to the crystalline structures, we find that the entrainment of neutrons by the clusters is very weak since neutrons of the gas can flow through the clusters. Consequently, we obtain a low effective mass of the clusters and a superfluid density that is even higher than the density of unbound neutrons. Consequences for the constraints from glitch observations are discussed.

  7. Brane-world dark stars with solid crust

    CERN Document Server

    Ovalle, Jorge; Casadio, Roberto


    The minimal geometric deformation approach is employed to show the existence of brane-world stellar distributions with vacuum Schwarzschild exterior, thus without energy leaking from the exterior of the brane-world star into the extra dimension. The interior satisfies all elementary criteria of physical acceptability for a stellar solution, namely, it is regular at the origin, the pressure and density are positive and decrease monotonically with increasing radius, finally all energy conditions are fulfilled. A very thin solid crust with negative radial pressure separates the interior from the exterior, having a thickness $\\Delta $ inversely proportional to both the brane tension $\\sigma $ and the radius $R$ of the star, i.e. $\\Delta ^{-1}\\sim R\\,\\sigma $. This brane-world star with Schwarzschild exterior would appear dark to a distant observer and be fully compatible with the stringent constraints imposed on stellar parameters by observations of gravitational lensing, orbital evolutions or properties of accre...

  8. Hydromechanical Modeling of Fluid Flow in the Lower Crust (United States)

    Connolly, J.


    The lower crust lies within an ambiguous rheological regime between the brittle upper crust and ductile sub-lithospheric mantle. This ambiguity has allowed two schools of thought to develop concerning the nature of fluid flow in the lower crust. The classical school holds that lower crustal rocks are inviscid and that any fluid generated by metamorphic devolatilization is squeezed out of rocks as rapidly as it is produced. According to this school, permeability is a dynamic property and fluid flow is upward. In contrast, the modern school uses concepts from upper crustal hydrology that presume implicitly, if not explicitly, that rocks are rigid or, at most, brittle. For the modern school, the details of crustal permeability determine fluid flow and as these details are poorly known almost anything is possible. Reality, to the extent that it is reflected by inference from field studies, offers some support to both schools. In particular, evidence of significant lateral and channelized fluid flow are consistent with flow in rigid media, while evidence for short (104 - 105 y) grain-scale fluid-rock interaction during much longer metamorphic events, suggests that reaction-generated grain-scale permeability is sealed rapidly by compaction; a phenomenon that is also essential to prevent extensive retrograde metamorphism. These observations provide a compelling argument for recognizing in conceptual models of lower crustal fluid flow that rocks are neither inviscid nor rigid, but compact by viscous mechanisms on a finite time-scale. This presentation will review the principle consequences of, and obstacles to, incorporating compaction in such models. The role of viscous compaction in the lower crust is extraordinarily uncertain, but ignoring this uncertainty in models of lower crustal fluid flow does not make the models any more certain. Models inevitably invoke an initial steady state hydraulic regime. This initial steady state is critical to model outcomes because it

  9. Physical processes in the growth of the continental crust (United States)

    Schubert, G.


    Major mechanisms of crustal addition are volcanism and plutonism at plate boundaries and within plate interiors. One approach to deciding if island arc magmatism dominated ancient crustal growth is to assess the rate at which the process has operated in the recent past. The localized addition rates were found to be comparable to present day global rates. One physical observable that was used to constrain models of crustal growth is sea level. A simple physical model was developed to explore the consequences of constant freeboard (the height of the continents above sea level). Global geoid and sea floor topography data were used to identify and study oceanic plateaus and swells that have either continental crustal roots or anomalously thick ocean crusts.

  10. [Effects of simulated nitrogen deposition on the fine root characteristics and soil respiration in a Pleioblastus amarus plantation in rainy area of West China]. (United States)

    Tu, Li-hua; Hu, Ting-xing; Zhang, Jian; He, Yuan-yang; Tian, Xiang-yu; Xiao, Yin-long


    Fine root is critical in the belowground carbon (C) cycling in forest ecosystem. Aimed to understand the effects of nitrogen (N) deposition on the fine root characteristics and soil respiration in Pleioblastus amarus plantation, a two-year field experiment was conducted in the Rainy Area of West China. Four treatments with different levels of N deposition were installed, i. e., CK (0 g N x m(-2) x a(-1)), low N (5 g N x m(-2) x a(-1)), medium N (15 g N x m(-2) x a(-1)), and high N (30 g N x m(-2) x a(-1)). There were great differences in the biomass and element contents of Nitrogen deposition increased the biomass of deposition. The annual soil respiration rate in treatments CK, low N, medium N, and high N was (5.85 +/- 0.43), (6.48 +/- 0.71), (6.84 +/- 0.57), and (7.62 +/- 0.55) t C x hm(-2) x a(-1), respectively, indicating that N deposition had obvious promotion effects on soil respiration. There were significant linear relationships between the annual soil respiration rate and the biomass and N content of deposition increased the fine root biomass and promoted the root metabolism, and stimulated the rhizospheric soil respiration rate via promoting microbial activities.

  11. The Incidence Increasing of Sheep some Diseases Caused by Heavy Rainy Spring of 2010 in the West Part of the Country

    Directory of Open Access Journals (Sweden)

    Daniela Moţ


    Full Text Available As a result of heavy rains from spring of 2010 became to appear, after two months of animals maintaining in high humidity conditions, some health problems. Were been examined by clinical point of view 280 sheep from four herds of Timiş district particular breeders from Transilvanian Merinos and Ţurcană breeds, 2-5 years aged. In the same time were been taken samples from foot lesions of affected sheep and were been examined from morphopathological point of view the 29 sheep bodies slaughtered by necessity. After all examinations was been observed that 197 sheep (70.35%, more than half from examined animals had foot lesions and respiratory clinic signs caused by exceeded rains from last months. From the necessity slaughtered sheep bodies were been isolated larvae from Dictyocaulus filaria, Oestrus ovis and adults of Psoroptes ovis, parasites who had found optimum conditions of development and to produce infections in rainy springs, with water and mud remained long time on pastures. From foot samples was been isolated in Microbiology laboratory Fusobacterium necrophorum, a bacteria responsible of interdigitally dermatitis in sheep. All these problems caused by heavy rains had as results important economic damages through milk and wool decreased productions and high costs with antiinfectious and antiparasitical treatments.

  12. Baobab trees (Adansonia) in Madagascar use stored water to flush new leaves but not to support stomatal opening before the rainy season. (United States)

    Chapotin, Saharah Moon; Razanameharizaka, Juvet H; Holbrook, N Michele


    Baobab trees (Adansonia, Bombacaceae) are widely thought to store water in their stems for use when water availability is low. We tested this hypothesis by assessing the role of stored water during the dry season in three baobab species in Madagascar. In the dry season, leaves are present only during and after leaf flush. We quantified the relative contributions of stem and soil water during this period through measures of stem water content, sap flow and stomatal conductance. Rates of sap flow at the base of the trunk were near zero, indicating that leaf flushing was almost entirely dependent on stem water. Stem water content declined by up to 12% during this period, yet stomatal conductance and branch sap flow rates remained very low. Stem water reserves were used to support new leaf growth and cuticular transpiration, but not to support stomatal opening before the rainy season. Stomatal opening coincided with the onset of sap flow at the base of the trunk and occurred only after significant rainfall.

  13. Sink or swim? Geodynamic and petrological model constraints on the fate of Archaean primary crust (United States)

    Kaus, B.; Johnson, T.; Brown, M.; VanTongeren, J. A.


    Ambient mantle potential temperatures in the Archaean were significantly higher than 1500 °C, leading to a high percent of melting and generating thick MgO-rich primary crust underlain by highly residual mantle. However, the preserved volume of this crust is low suggesting much of it was recycled. Here we couple calculated phase equilibria for hydrated and anhydrous low to high MgO crust compositions and their complementary mantle residues with 2-D numerical geodynamic models to investigate lithosphere dynamics in the early Earth. We show that, with increasing ambient mantle potential temperature, the density of primary crust increases more dramatically than the density of residual mantle decreases and the base of MgO-rich primary crust becomes gravitationally unstable with respect to the underlying mantle even when fully hydrated. To study this process we use geodynamic models that include the effects of melt extraction, crust formation and depletion of the mantle in combination with laboratory-constrained dislocation and diffusion creep rheologies for the mantle. The models show that the base of the gravitationally unstable lithosphere delaminates through relatively small-scale Rayleigh-Taylor instabilities, but only if the viscosity of the mantle lithosphere is sufficiently low. Thickening of the crust above upwelling mantle and heating at the base of the crust are the main mechanisms that trigger the delamination process. Scaling laws were developed that are in good agreement with the numerical simulations and show that the key parameters that control the instability are the density contrast between crust and underlying mantle lithosphere, the thickness of the unstable layer and the effective viscosity of the upper mantle. Depending on uncertainties in the melting relations and rheology (hydrous or anhydrous) of the mantle, this process is shown to efficiently recycle the crust above potential temperatures of 1550-1600 °C. However, below these temperatures

  14. Geochemical characteristics and metal element enrichment in crusts from seamounts of the Western Pacific

    Institute of Scientific and Technical Information of China (English)

    Xiaoyu ZHANG; Kechao ZHU; Yong DU; Fuyuan ZHANG; Weiyan ZHANG; Xiangwen REN; Binbin JIANG


    Elemental geochemistry is an essential part of understanding mineralization mechanisms.In this paper,a data set of 544 cobalt crust samples from seamounts of the Western Pacific are used to study the enrichment characteristics of metal elements.REE normalization is utilized to reveal the origin of the crusts;effects of water depth on Co enrichment and impacts ofphosphatization on mineral quality are discussed to obtain the evolution of these marine mineral deposits,which gives support to further resource assessment.Conclusions are reached as follows:1) Elemental abundances,inter-element relationships,and shale-normalized REE patterns for phosphatepoor crusts from different locations reflect hydrogenetic origin of the crusts.EFs (enrichment coefficients) of REE exhibit exponential increase from surface sediments to phosphorite to polymetallic nodules to crusts,suggesting that the improved degree of hydrogeneous origin induces the enrichment of REE.2) The crusts in the Westem Pacific,formed through hotspot produced guyots trails,have relatively lower REE than those in the Mid-Pacific.The latter could be attributed to the peculiar submarine topography of seamounts formed by intraplate volcanism.3) The non-phosphatized younger crust layers have 40% higher Co than the phosphatized older layers.This indicates the modification of the elemental composition in these crusts by phosphatization.A general depletion of hydroxide-dominated elements such as Co,Ni,and Mn and enrichment of P,Ca,Ba,and Sr is evident in phosphatized crusts,whereas non-phosphatized younger generation crusts are rich in terrigenous aluminosilicate detrital matter.4) Co increases above the carbonate compensation depth (CCD) from less than 0.53% to over 0.65% in seamount regions with water depth of less than 2,500 m,suggesting the significance of the dissolution of carbonate in the sea water column to the growth and composition of crusts.

  15. Copper-nickel-rich, amalgamated ferromanganese crust-nodule deposits from Shatsky Rise, NW Pacific (United States)

    Hein, J.R.; Conrad, T.A.; Frank, M.; Christl, M.; Sager, W.W.


    A unique set of ferromanganese crusts and nodules collected from Shatsky Rise (SR), NW Pacific, were analyzed for mineralogical and chemical compositions, and dated using Be isotopes and cobalt chronometry. The composition of these midlatitude, deep-water deposits is markedly different from northwest-equatorial Pacific (PCZ) crusts, where most studies have been conducted. Crusts and nodules on SR formed in close proximity and some nodule deposits were cemented and overgrown by crusts, forming amalgamated deposits. The deep-water SR crusts are high in Cu, Li, and Th and low in Co, Te, and Tl concentrations compared to PCZ crusts. Thorium concentrations (ppm) are especially striking with a high of 152 (mean 56), compared to PCZ crusts (mean 11). The deep-water SR crusts show a diagenetic chemical signal, but not a diagenetic mineralogy, which together constrain the redox conditions to early oxic diagenesis. Diagenetic input to crusts is rare, but unequivocal in these deep-water crusts. Copper, Ni, and Li are strongly enriched in SR deep-water deposits, but only in layers older than about 3.4 Ma. Diagenetic reactions in the sediment and dissolution of biogenic calcite in the water column are the likely sources of these metals. The highest concentrations of Li are in crust layers that formed near the calcite compensation depth. The onset of Ni, Cu, and Li enrichment in the middle Miocene and cessation at about 3.4 Ma were accompanied by changes in the deep-water environment, especially composition and flow rates of water masses, and location of the carbonate compensation depth.

  16. Spatial and temporal distribution of cyanobacterial soil crusts in the Kalahari: Implications for soil surface properties (United States)

    Thomas, A. D.; Dougill, A. J.


    Localised patterns of erosion and deposition in vegetated semi-arid rangelands have been shown to influence ecological change and biogeochemical cycles. In the flat, vegetated Kalahari rangelands of Southern Africa the factors regulating erodibility of the fine sand soils and the erosivity of wind regimes require further investigation. This paper reports on the spatial and temporal patterns of cyanobacterial soil crust cover from ten sites at five sampling locations in the semi-arid Kalahari and discusses the likely impact on factors regulating surface erodibility and erosivity. Cyanobacterial soil crust cover on Kalahari Sand varied between 11% and 95% of the ground surface and was higher than previously reported. Cover was inversely related to grazing with the lowest crust cover found close to boreholes and the highest in the Game Reserve and Wildlife Management Zone. In grazed areas, crusts form under the protective canopies of the thorny shrub Acacia mellifera. Fenced plot data showed that crusts recover quickly from disturbance, with a near complete surface crust cover forming within 15 months of disturbance. Crust development is restricted by burial by wind blown sediment and by raindrop impact. Crusts had significantly greater organic matter and total nitrogen compared to unconsolidated surfaces. Crusts also significantly increased the compressive strength of the surface (and thus decreased erodibility) and changed the surface roughness. Establishing exactly how these changes affect aeolian erosion requires further process-based studies. The proportion of shear velocity acting on the surface in this complex mixed bush-grass-crust environment will be the key to understanding how crusts affect erodibility.

  17. Impact of land use changes on hydrology of Mt. Kilimanjaro. The case of Lake Jipe catchment (United States)

    Ngugi, Keziah; Ogindo, Harun; Ertsen, Maurits


    Mt. Kilimanjaro is an important water tower in Kenya and Tanzania. Land degradation and land use changes have contributed to dwindling surface water resources around Mt. Kilimanjaro. This study focuses on Lake Jipe catchment of about 451Km2 (Ndetei 2011) which is mainly drained by River Lumi, a tributary of river Pangani. River Lumi starts from Mt. Kilimanjaro and flows North east wards to cross the border from Tanzania to Kenya eventually flowing into Lake Jipe which is a trans-boundary lake. The main purpose of this study was to investigate historical land use changes and relate this to reduction in surface water resources. The study will propose measures that could restore the catchment thereby enhancing surface water resources feeding Lake Jipe. A survey was conducted to document community perspectives of historical land use changes. This information was corroborated using Landsat remote sensed images spanning the period 1985-2013 to determine changes in the land cover due to human activities on Lake Jipe Catchment. River Lumi flow data was obtained from Water Resources Management Authority and analyzed for flow trends. The dwindling extent of the Lake was obtained from the community's perspective survey and by Landsat images. Community survey and remote sensing indicated clearing of the forest on the mountain and conversion of the same to crop production fields; damming of river Lumi in Tanzania, conversion of bush land to crop production fields further downstream of river Lumi and irrigation. There is heavy infestation of the invasive species Prosopis juliflora which had aggressively colonized grazing land and blocked irrigation canals. Other land use changes include land fragmentation due to subdivision. Insecure land tenure was blamed for failure by farmers to develop soil and water conservation infrastructure. Available River gauging data showed a general decline in river flow. Heavy flooding occurred during rainy seasons. Towards Lake Jipe after the river

  18. Can Seismology Detect Ductile Deformation in the Deep Continental Crust? (United States)

    Lloyd, G. E.; Halliday, J. M.; Butler, R. W.; Casey, M.; Kendall, J.


    Various models exist to explain deformation in deep continental crust, broadly divisible into localized simple shear and distributed pure shear. Although seismic imaging is perhaps the most effective way to determine deformation at depth, the veracity of any interpretation depends critically upon knowledge of the seismic properties of the rocks. As a region of active crustal thickening and exhumation, the Nanga Parbat Massif (NPM), Pakistan Himalaya, offers insight into how localized thrust faults at the Earth's surface couple with distributed strain at depth. Gneissic, mylonitic and cataclastic rocks at the surface were sampled as proxies for lithologies and fabrics currently accommodating deformation at depth. The LPO of individual minerals were measured using SEM/EBSD, from which elastic constants, 3D seismic velocities and anisotropies were predicted. Micas contribute most to the bulk anisotropy; only when mica content is low and/or LPO is weak do other minerals contribute significantly. The anisotropy varies with deformation style: background gneiss samples have highest AVs anisotropy (9.5 percent) compared with highly strained gneiss samples (5.1-6.3 percent) and cataclasite (0.4 percent). This suggests that some shear zones are characterized by low anisotropy. Sample elastic constants were used to construct models, based on current ideas of NPM tectonics, through which P-, S- and converted waves were ray traced. Foliation orientation and intensity have dramatic impacts on seismic waves: rocks with 9.5 percent AVs and vertically aligned foliation persistent through 40km of crust induce ~1.5s AVs compared to horizontal alignment that induces only 0.2s AVs. Mode conversions and transverse component energy are also diagnostic of foliation intensity and orientation. The models indicate that it is possible to discriminate between different deformation processes active at depth using seismic measurements and we conclude that the dominant process in the NPM is

  19. Crust and subduction zone structure of Southwestern Mexico (United States)

    Suhardja, Sandy Kurniawan; Grand, Stephen P.; Wilson, David; Guzman-Speziale, Marco; Gomez-Gonzalez, Juan Martin; Dominguez-Reyes, Tonatiuh; Ni, James


    Southwestern Mexico is a region of complex active tectonics with subduction of the young Rivera and Cocos plates to the south and widespread magmatism and rifting in the continental interior. Here we use receiver function analysis on data recorded by a 50 station temporary deployment of seismometers known as the MARS (MApping the Rivera Subduction zone) array to investigate crustal structure as well as the nature of the subduction interface near the coast. The array was deployed in the Mexican states of Jalisco, Colima, and Michoacan. Crustal thickness varies from 20 km near the coast to 42 km in the continental interior. The Rivera plate has steeper dip than the Cocos plate and is also deeper along the coast than previous estimates have shown. Inland, there is not a correlation between the thickness of the crust and topography indicating that the high topography in northern Jalisco and Michoacan is likely supported by buoyant mantle. High crustal Vp/Vs ratios (greater than 1.82) are found beneath the trenchward edge of magmatism including below the Central Jalisco Volcanic Lineament and the Michoacan-Guanajuato Volcanic Field implying a new arc is forming closer to the trench than the Trans Mexican Volcanic Belt. Elsewhere in the region, crustal Vp/Vs ratios are normal. The subducting Rivera and Cocos plates are marked by a dipping shear wave low-velocity layer. We estimate the thickness of the low-velocity layer to be 3 to 4 km with an unusually high Vp/Vs ratio of 2.0 to 2.1 and a drop in S velocity of 25%. We postulate that the low-velocity zone is the upper oceanic crust with high pore pressures. The low-velocity zone ends from 45 to 50 km depth and likely marks the basalt to eclogite transition.

  20. Evidence for oceanic crust in the Herodotus Basin (United States)

    Granot, Roi


    Some of the fundamental tectonic problems of the Eastern Mediterranean remain unresolved due to the extremely thick sedimentary cover (10 to 15 km) and the lack of accurate magnetic anomaly data. I have collected 7,000 km of marine magnetic profiles (2012-2014) across the Herodotus and Levant Basins, Eastern Mediterranean, to study the nature and age of the underlying igneous crust. The towed magnetometer array consisted of two Overhauser sensors recording the total magnetic anomaly field in a longitudinal gradiometer mode, and a fully oriented vector magnetometer. The total field data from the Herodotus Basin reveal a newly detected short sequence of long-wavelength NE-SW lineated anomalies that straddle the entire basin suggesting a deep two-dimensional magnetic source layer. The three components of the magnetic vector data indicate that an abrupt transition from a 2D to 3D magnetic structure occurs east of the Herodotus Basin, along where a prominent NE-SW gravity feature is found. Altogether, these new findings confirm that the Herodotus Basin preserves remnants of oceanic crust that formed along the Neotethyan mid-ocean ridge system. The continuous northward and counterclockwise motion of the African Plate during the Paleozoic and Mesozoic allow predicting the evolution of remanent magnetization directions, which in-turn dictate that shape of the anomalies. The shape of the Herodotus anomalies best fit Late Carboniferous to Early Permian (300±20 Myr old) magnetization directions. Finally, I will discuss the implications of these results on the tectonic architecture of the region as well as on various geodynamic processes.

  1. Felsic Magmatism through Intracrustal Melting of Previously Formed Volcanic-Arc Crust: Implications for Differentiation and Secular Evolution of the Continental Crust (United States)

    G R, R. K.; C, S.


    The fundamental challenge in understanding the origin and evolution of the continental crust is to recognize how primary mantle source, and oceanic crust, which are essentially mafic to ultramafic in composition, could differentiate into a more or less felsic compositions. It is possible to understand growth and differentiation of the continental crust by constraining the interplay of magmatism, deformation, and high-grade metamorphism in the lower crust. Here, we apply this knowledge on the lower crustal granitoids of southern India and speculate on the variations in geochemistry as a consequence of differentiation and secular evolution of the continental crust.The major groups of granitoids of southern India are classified as metatonalites, comparable to typical Archaean TTGs with pronounced calc-alkaline affinity, and metagranites which are magmatic fractionation produced by reworking of early crust. Metatonalites are sodic-trondhjemites with slightly magnesian, moderate LREE (average LaN = 103) and low HREE (average YbN = 2) characerestics, where as metagranites are calc-alkaline ferroan types with enriched LREE (average LaN = 427) and HREE (average YbN = 23). Petrogenetic characteristics of granitoids illustrate continuous evolution of a primary crust into diverse magmatic units by multiple stages of intracrustal differentiation processes attributed to following tectonic scenarios: (1) formation of tonalitic magma by low- to moderate-degree partial melting of hydrated basaltic crust at pressures high enough to stabilize garnet-amphibole residue and (2) genesis of granite in a continental arc-accretion setting by an episode of crustal remelting of the tonalitic crust, within plagioclase stability field. The first-stage formed in a flat-subduction setting of an volcanic-arc, leading to the formation of tonalites. The heat budget required is ascribed to the upwelling of the mantle and/or basaltic underplating. Progressive decline in mantle potential temperature

  2. Poet Lake Crystal Approval (United States)

    This September 19, 2016 letter from EPA approves the petition from Poet Biorefining-Lake Crystal, regarding non-grandfathered ethanol produced through a dry mill process, qualifying under the Clean Air Act for renewable fuel (D-code 6) RINs under the RFS

  3. in lake chamo, ethiopia

    African Journals Online (AJOL)


    zooplankton until they move to the littoral regions and start feeding .... Fish collected during the spawning season (i.e.,. March-June .... females, but sampling in the estuary downstream ... same size could be first-time spawners in Lake. Chamo ...

  4. Reclaiming the lake

    DEFF Research Database (Denmark)

    Rasmussen, Mattias Borg


    of individual rights that move well beyond the site of conflict. It is therefore argued that the actions to reclaim Lake Conococha were not only a battle for natural resources and clean water, but more fundamentally an attempt to repossess a citizenship that may be constitutionally secured but all too oft en...

  5. Lake Ontario: Nearshore Variability (United States)

    We conducted a high-resolution survey with towed electronic instrumentation along the Lake Ontario nearshore (720 km) at a 20 meter contour. The survey was conducted September 6-10, 2008 with a shorter 300 km survey conducted August 14-15 for comparing of temporal variability. ...

  6. Depth profiles of 230Th excess, transition metals and mineralogy of ferromanganese crusts of the Central Indian Ocean basin and implications for palaeoceanographic influence on crust genesis

    Digital Repository Service at National Institute of Oceanography (India)

    Banakar, V.K.; Borole, D.V.

    . The interpolated age of these crusts is between 10 and I3 Ma which is comparable to the period of increased carbonate dissolution due to enhanced activity of AABW (Antarctic Bottom Water) currents during the middle Miocene. Probably the middle Miocene... which are controlled by both hydrogenetic and diagenetic processes (Halbach et al., 198 1). The metal composi- tion of the crusts are dependent on water depth, latitude and age (Halbach and Puteanus, 1984b). Hence the geochemical variation...

  7. Controls on ferromanganese crust composition and reconnaissance resource potential, Ninetyeast Ridge, Indian Ocean (United States)

    Hein, James R.; Conrad, Tracey; Mizell, Kira; Banakar, Virupaxa K.; Frey, Frederick A.; Sager, William W.


    A reconnaissance survey of Fe-Mn crusts from the 5000 km long (~31°S to 10°N) Ninetyeast Ridge (NER) in the Indian Ocean shows their widespread occurrence along the ridge as well as with water depth on the ridge flanks. The crusts are hydrogenetic based in growth rates and discrimination plots. Twenty samples from 12 crusts from 9 locations along the ridge were analyzed for chemical and mineralogical compositions, growth rates, and statistical relationships (Q-mode factor analysis, correlation coefficients) were calculated. The crusts collected are relatively thin (maximum 40 mm), and those analyzed varied from 4 mm to 32 mm. However, crusts as thick as 80 mm can be expected to occur based on the age of rocks that comprise the NER and the growth rates calculated here. Growth rates of the crusts increase to the north along the NER and with water depth. The increase to the north resulted from an increased supply of Mn from the oxygen minimum zone (OMZ) to depths below the OMZ combined with an increased supply of Fe at depth from the dissolution of biogenic carbonate and from deep-sourced hydrothermal Fe. These increased supplies of Fe increased growth rates of the deeper-water crusts along the entire NER. Because of the huge terrigenous (rivers, eolian, pyroclastic) and hydrothermal (three spreading centers) inputs to the Indian Ocean, and the history of primary productivity, Fe-Mn crust compositions vary from those analyzed from open-ocean locations in the Pacific. The sources of detrital material in the crusts change along the NER and reflect, from north to south, the decreasing influence of the Ganga River system and volcanic arcs located to the east, with increasing influence of sediment derived from Australia to the south. In addition, weathering of NER basalt likely contributed to the aluminosilicate fraction of the crusts. The southernmost sample has a relatively large detrital component compared to other southern NER crust samples, which was probably

  8. Microbiology of Lonar Lake and other soda lakes. (United States)

    Antony, Chakkiath Paul; Kumaresan, Deepak; Hunger, Sindy; Drake, Harold L; Murrell, J Colin; Shouche, Yogesh S


    Soda lakes are saline and alkaline ecosystems that are believed to have existed throughout the geological record of Earth. They are widely distributed across the globe, but are highly abundant in terrestrial biomes such as deserts and steppes and in geologically interesting regions such as the East African Rift valley. The unusual geochemistry of these lakes supports the growth of an impressive array of microorganisms that are of ecological and economic importance. Haloalkaliphilic Bacteria and Archaea belonging to all major trophic groups have been described from many soda lakes, including lakes with exceptionally high levels of heavy metals. Lonar Lake is a soda lake that is centered at an unusual meteorite impact structure in the Deccan basalts in India and its key physicochemical and microbiological characteristics are highlighted in this article. The occurrence of diverse functional groups of microbes, such as methanogens, methanotrophs, phototrophs, denitrifiers, sulfur oxidizers, sulfate reducers and syntrophs in soda lakes, suggests that these habitats harbor complex microbial food webs that (a) interconnect various biological cycles via redox coupling and (b) impact on the production and consumption of greenhouse gases. Soda lake microorganisms harbor several biotechnologically relevant enzymes and biomolecules (for example, cellulases, amylases, ectoine) and there is the need to augment bioprospecting efforts in soda lake environments with new integrated approaches. Importantly, some saline and alkaline lake ecosystems around the world need to be protected from anthropogenic pressures that threaten their long-term existence.

  9. Lake trout rehabilitation in Lake Erie: a case history (United States)

    Cornelius, Floyd C.; Muth, Kenneth M.; Kenyon, Roger


    Native lake trout (Salvelinus namaycush) once thrived in the deep waters of eastern Lake Erie. The impact of nearly 70 years of unregulated exploitation and over 100 years of progressively severe cultural eutrophication resulted in the elimination of lake trout stocks by 1950. Early attempts to restore lake trout by stocking were unsuccessful in establishing a self-sustaining population. In the early 1980s, New York's Department of Environmental Conservation, Pennsylvania's Fish and Boat Commission, and the U.S. Fish and Wildlife Service entered into a cooperative program to rehabilitate lake trout in the eastern basin of Lake Erie. After 11 years of stocking selected strains of lake trout in U.S. waters, followed by effective sea lamprey control, lake trout appear to be successfully recolonizing their native habitat. Adult stocks have built up significantly and are expanding their range in the lake. Preliminary investigations suggest that lake trout reproductive habitat is still adequate for natural reproduction, but natural recruitment has not been documented. Future assessments will be directed toward evaluation of spawning success and tracking age-class cohorts as they move through the fishery.

  10. Phytoplankton community of Reis lake in the Brazilian Amazon

    Directory of Open Access Journals (Sweden)



    Full Text Available Reis Lake is located in the municipality of Caracaraí, state of Roraima (Brazil and is subject to fluctuations in water level. The aim of this study was to analyze the structure of the phytoplankton community on the nictemeral and seasonal scales and determined the influence of limnological variables. Sampling was performed in the rainy season (June/2006 and dry season (November/2006, considering two nictemeral cycles. The phytoplankton community was assessed with regard to composition and density, abiotic variables were analyzed simultaneously. The lake had low concentrations of oxygen, clinograde profile and water stratified during the day and homogenous at night, with low concentrations of nutrients and waters ranging from slightly acidic to alkaline. The phytoplankton was represented by 43 taxa, 35 species in the dry season and 29 species in the rainy season. Low densities of phytoplankton occurred in both nictemeral cycles, with accentuated vertical gradient. The highest densities were recorded in the dry season. Reis Lake exhibits characteristics that classify it as a polymythic and oligotrophic environment. The variability in the data was more important seasonally than on the nictemeral scale, supporting the hypothesis of the influence of the hydrological cycle on the dynamics of phytoplankton communities in floodplain lakes.O lago dos Reis está localizado no município de Caracaraí, no estado de Roraima (Brasil e está sujeito a flutuações no nível da água. O objetivo do estudo foi analisar a estrutura da comunidade fitoplanctônica nas escalas nictemeral e sazonal e determinar a influência de variáveis limnológicas nesta comunidade. As amostragens foram realizadas nos periodos chuvoso e seco, considerando dois ciclos nictemeral. A comunidade fitoplanctônica foi avaliada no que diz respeito à composição e densidade, simultaneamente, variáveis abióticas foram analisadas. O lago apresentou baixas concentrações de oxig

  11. Microwave assisted digestion followed by ICP-MS for determination of trace metals in atmospheric and lake ecosystem. (United States)

    Ahmed, Manan; Chin, Ying Hui; Guo, Xinxin; Zhao, Xing-Min


    The study of trace metals in the atmosphere and lake water is important due to their critical effects on humans, aquatic animals and the geochemical balance of ecosystems. The objective of this study was to investigate the concentration of trace metals in atmospheric and lake water samples during the rainy season (before and after precipitation) between November and December 2015. Typical methods of sample preparation for trace metal determination such as cloud point extraction, solid phase extraction and dispersive liquid-liquid micro-extraction are time-consuming and difficult to perform; therefore, there is a crucial need for development of more effective sample preparation procedure. A convection microwave assisted digestion procedure for extraction of trace metals was developed for use prior to inductively couple plasma-mass spectrometric determination. The result showed that metals like zinc (133.50-419.30μg/m(3)) and aluminum (53.58-378.93μg/m(3)) had higher concentrations in atmospheric samples as compared to lake samples before precipitation. On the other hand, the concentrations of zinc, aluminum, chromium and arsenic were significantly higher in lake samples after precipitation and lower in atmospheric samples. The relationship between physicochemical parameters (pH and turbidity) and heavy metal concentrations was investigated as well. Furthermore, enrichment factor analysis indicated that anthropogenic sources such as soil dust, biomass burning and fuel combustion influenced the metal concentrations in the atmosphere. Copyright © 2016. Published by Elsevier B.V.

  12. Chlorophytes of biological soil crusts in Gurbantunggut Desert, Xinjiang Autonomous Region, China

    Institute of Scientific and Technical Information of China (English)


    In this paper, chlorophytes collected from 253 biological soil crust samples in Gurbantunggut Desert in Xinjiang Autonomous Region, China were studied by field investigation and microscopical observation in lab. The flora composition, ecological distribution of chlorophytes in the desert and dynamic changes of species composition of chlorophytes in different developing stages of biological soil crusts are preliminarily analyzed. Results showed that there were 26 species belonging to 14 genera and 10 families, in which unicellular chlorophytes were dominant. There existed some differences in distribution of varied sand dune positions. The taxa of chlorophytes in leeward of sand dunes are most abundant, but the taxa in windward, interdune and the top of sand dunes reduced gradually. Chlorophytes were mainly distributed within the crust and the taxa of chlorophytes decrease obviously under the crust. In the devel-oping stages of the biological soil crust, species diversity of chlorophytes changed a little, but species composition pre-sented some differences. Chlorococcum humicola, Chlorella vulgaris, Chlamydomonas ovalis and Chlamydomonas sp. nearly existed in all developing stages of biological crusts. In several former stages of the biological soil crust there were spherical chlorophytes and filamentous ones. When moss crust formed, filamentous chlorophytes disappeared, such as Microspora and Ulothrix.

  13. The growth of the continental crust: Constraints from radiogenic isotope geochemistry (United States)

    Taylor, Paul N.


    Most models for evolution of continental crust are expressed in the form of a diagram illustrating the cumulative crustal mass (normalized relative to the present crustal mass) as a function of time. Thus, geochronological data inevitably play a major role in either constructing or testing crustal growth models. For all models, determining the start-time for effective crustal accretion is of vital importance. To this end, the continuing search for, and reliable characterization of, the most ancient crustal rock-units remains a worthy enterprise. Another important role for geochronology and radiogenic isotope geochemistry is to assess the status of major geological events as period either of new crust generation or of reworking of earlier formed continental crust. For age characterization of major geological provinces, using the critieria outined, the mass (or volume) of crust surviving to the present day should be determinable as a function of crust formation age. More recent developments, however, appear to set severe limitations on recycling of crust, at least by the process of sediment subduction. In modeling crustal growth without recycling, valuable constaints on growth rate variations through time can be provided if variations in the average age of the continental crust can be monitored through geological history. The question of the average age of the exposed continental crust was addressed by determining Sm-Nd crustal residence model ages (T-CR) for fine-grained sediment loads of many of the world's major rivers.

  14. The role of the gluten network in the crispness of bread crust

    NARCIS (Netherlands)

    Primo-Martín, C.; Pijpekamp, A.v.d.; Vliet, T.v.; Jongh, H.H.J.d.; Plijter, J.J.; Hamer, R.J.


    Crispness features of baked products strongly determine consumer acceptability. For many baked products, such as bread, the outer crust gives the crispy sensation. Confocal scanning laser microscopy of the structure of bread crust revealed a continuous protein phase and a discontinuous

  15. Water content or water activity: What rules crispy behavior in bread crust?

    NARCIS (Netherlands)

    Nieuwenhuijzen, N.H. van; Primo-Martín, C.; Meinders, M.B.J.; Tromp, R.H.; Hamer, R.J.; Vliet, T. van


    A dry crust loses its crispness when water migrates into the crust. It is not clear if it is the amount of water absorbed or the water activity (a w) that leads to a loss of crispness. The hysteresis effect observed when recording a water sorption isotherm allowed us to study the effects of aw and m

  16. Water content or water activity: What rules crispy behavior in bread crust?

    NARCIS (Netherlands)

    Nieuwenhuijzen, N.H. van; Primo-Martín, C.; Meinders, M.B.J.; Tromp, R.H.; Hamer, R.J.; Vliet, T. van


    A dry crust loses its crispness when water migrates into the crust. It is not clear if it is the amount of water absorbed or the water activity (a w) that leads to a loss of crispness. The hysteresis effect observed when recording a water sorption isotherm allowed us to study the effects of aw and m

  17. Heterogeneity of Parent Rocks and Its Constraints on Geochemical Criteria in Weathering Crusts of Carbonate Rocks

    Institute of Scientific and Technical Information of China (English)

    WANG Shijie; FENG Zhigang


    Owing to the low contents of their acid-insoluble components, carbonate rocks tend to decrease sharply in volume in association with the formation of weathering crust. The formation of a 1 m-thick weathering crust would usually consume more than ten meters to several tens of meters of thickness of parent rocks. The knowledge of how to identify the homogeneity of parent rocks is essential to understand the formation mechanism of weathering crust in karst regions,especially that of thick-layered red weathering crust. In this work the grain-size analyses have demonstrated that the three profiles studied are the residual weathering crust of carbonate rocks and further showed that there objectively exists the heterogeneity of parent rocks in the three studied weathering crusts. The heterogeneity of parent rocks can also be reflected in geochemical parameters of major elements, just as the characteristics of frequency plot of grain-size distribution.Conservative trace element ratios Zr/Hf and Nb/Ta are proven to be unsuitable for tracing the heterogeneity of parent rocks of weathering crust, but its geochemical mechanism is unclear. The authors strongly suggest in this paper that the identification of the homogeneity of parent rocks of weathering crust in karst regions is of prime necessity.

  18. Crust morphology and crispness development during deep-fat frying of potato

    NARCIS (Netherlands)

    Koerten, van K.N.; Schutyser, M.A.I.; Somsen, D.; Boom, R.M.


    Crust formation is an important factor in determining the crispness of French fries. This study aimed at unravelling detailed structural and textural properties of the crust in relation to crispness during frying as a function of the process temperature and time. X-ray tomography showed a larger ove

  19. Physical characterization, spectral response and remotely sensed mapping of Mediterranean soil surface crusts

    NARCIS (Netherlands)

    Jong, S.M. de; Addink, E.A.; Duijsing, D.; Beek, L.P.H. van


    Soil surface crusting and sealing are frequent but unfavorable processes in Mediterranean areas. Soil crust and seals form on bare soil subject to high-intensity rainfall, resulting in a hard, impenetrable layer that impedes infiltration and hampers the germination and establishment of plants. The a

  20. The role of the gluten network in the crispness of bread crust

    NARCIS (Netherlands)

    Primo-Martín, C.; Pijpekamp, A.v.d.; Vliet, T.v.; Jongh, H.H.J.d.; Plijter, J.J.; Hamer, R.J.


    Crispness features of baked products strongly determine consumer acceptability. For many baked products, such as bread, the outer crust gives the crispy sensation. Confocal scanning laser microscopy of the structure of bread crust revealed a continuous protein phase and a discontinuous non-gelatiniz