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Sample records for estonian small lakes

  1. Online Estonian Language Learning

    ERIC Educational Resources Information Center

    Teral, Maarika; Rammo, Sirje

    2014-01-01

    This presentation focuses on computer-assisted learning of Estonian, one of the lesser taught European languages belonging to the Finno-Ugric language family. Impulses for this paper came from Estonian courses that started in the University of Tartu in 2010, 2011 and 2012. In all the courses the students gain introductory knowledge of Estonian and…

  2. INTRODUCTION TO ESTONIAN LINGUISTICS.

    ERIC Educational Resources Information Center

    RAUN, ALO; SAARESTE, ANDRUS

    THIS TEXT COMPRISES A SURVEY OF THE ESTONIAN LANGUAGE, WHICH IS GROUPED HERE WITH LIVONIAN, VOTIC, AND A PART OF WESTERN FINNISH, TO FORM THE SOUTHWESTERN BRANCH OF THE FINNIC (OR BALTO-FINNIC) LANGUAGES. THE AUTHORS' CLASSIFICATIONS AND A HISTORY OF THE STUDIES WHICH HAVE BEEN CARRIED OUT IN ESTONIAN ARE PRESENTED, FOLLOWED BY A PRESENTATION OF…

  3. Small lakes show muted climate change signal in deepwater temperatures

    USGS Publications Warehouse

    Winslow, Luke A.; Read, Jordan S.; Hansen, Gretchen J. A.; Hanson, Paul C.

    2015-01-01

    Water temperature observations were collected from 142 lakes across Wisconsin, USA, to examine variation in temperature of lakes exposed to similar regional climate. Whole lake water temperatures increased across the state from 1990 to 2012, with an average trend of 0.042°C yr−1 ± 0.01°C yr−1. In large (>0.5 km2) lakes, the positive temperature trend was similar across all depths. In small lakes (<0.5 km2), the warming trend was restricted to shallow waters, with no significant temperature trend observed in water >0.5 times the maximum lake depth. The differing response of small versus large lakes is potentially a result of wind-sheltering reducing turbulent mixing magnitude in small lakes. These results demonstrate that small lakes respond differently to climate change than large lakes, suggesting that current predictions of impacts to lakes from climate change may require modification.

  4. Hydrodynamic modelling of small upland lakes under strong wind forcing

    NASA Astrophysics Data System (ADS)

    Morales, L.; French, J.; Burningham, H.

    2012-04-01

    Small lakes (Area < 1 km2) represent 46.3% of the total lake surface globally and constitute an important source of water supply. Lakes also provide an important sedimentary archive of environmental and climate changes and ecosystem function. Hydrodynamic controls on the transport and distribution of lake sediments, and also seasonal variations in thermal structure due to solar radiation, precipitation, evaporation and mixing and the complex vertical and horizontal circulation patterns induced by the action of wind are not very well understood. The work presented here analyses hydrodynamic motions present in small upland lakes due to circulation and internal scale waves, and their linkages with the distribution of bottom sediment accumulation in the lake. For purpose, a 3D hydrodynamic is calibrated and implemented for Llyn Conwy, a small oligotrophic upland lake in North Wales, UK. The model, based around the FVCOM open source community model code, resolves the Navier-Stokes equations using a 3D unstructured mesh and a finite volume scheme. The model is forced by meteorological boundary conditions. Improvements made to the FVCOM code include a new graphical user interface to pre- and post process the model input and results respectively, and a JONSWAT wave model to include the effects of wind-wave induced bottom stresses on lake sediment dynamics. Modelled internal scale waves are validated against summer temperature measurements acquired from a thermistor chain deployed at the deepest part of the lake. Seiche motions were validated using data recorded by high-frequency level sensors around the lake margins, and the velocity field and the circulation patterns were validated using the data recorded by an ADCP and GPS drifters. The model is shown to reproduce the lake hydrodynamics and reveals well-developed seiches at different frequencies superimposed on wind-driven circulation patterns that appear to control the distribution of bottom sediments in this small

  5. Investigating aquatic ecosystems of small lakes in Khorezm, Uzbekistan

    USGS Publications Warehouse

    Saito, L.; Scott, J.; Rosen, M.; Nishonov, Bakhriddin; Chandra, S.; Lamers, John P.A.; Fayzieva, Dilorom; Shanafield, M.

    2009-01-01

    The Khorezm province of Uzbekistan, located in the Aral Sea Basin, suffers from severe environmental and human health problems due to decades of unsustainable land and water management. Agriculture is the dominant land use in Khorezm, and agricultural runoff water has impacted many small lakes. In this water-scarce region, these lakes may provide a water source for irrigation or fish production. Samples have been collected from 13 of these lakes since 2006 to assess water quality, the aquatic food web, and possible limits to aquatic production. Lake salinity varied from 1 to >10 g/L both between and within lakes. Although hydrophobic contaminants concentrations were low (82-241 pg toxic equivalents/mL in June 2006, October 2006, and June 2007), aquatic species diversity and relative density were low in most lakes. Ongoing work is focused on 4 lakes with pelagic food webs to estimate fish production and assess anthropogenic impacts on the food web. Lake sediment cores are also being examined for organic contaminants, and hydrology is being assessed with stable isotopes. ?? 2009 ASCE.

  6. The Estonian Deaf Community

    ERIC Educational Resources Information Center

    Hein, Kadri

    2010-01-01

    Interest in research on Estonian Sign Language, or eesti viipekeel (EVK), has been increasing. Studies have been conducted on different aspects of EVK, such as ways of expressing time (Trukmann 2006) and color terms (Hollman and Sutrop 2007, Hollman 2008). Moreover, EVK has lately received more attention in legislation. The language obtained an…

  7. Effect of DOC on evaporation from small Wisconsin lakes

    NASA Astrophysics Data System (ADS)

    Watras, C. J.; Morrison, K. A.; Rubsam, J. L.

    2016-09-01

    Evaporation (E) dominates the loss of water from many small lakes, and the balance between precipitation and evaporation (P-E) often governs water levels. In this study, evaporation rates were estimated for three small Wisconsin lakes over several years using 30-min data from floating evaporation pans (E-pans). Measured E was then compared to the output of mass transfer models driven by local conditions over daily time scales. The three lakes were chosen to span a range of dissolved organic carbon (DOC) concentrations (3-20 mg L-1), a solute that imparts a dark, tea-stain color which absorbs solar energy and limits light penetration. Since the lakes were otherwise similar, we hypothesized that a DOC-mediated increase in surface water temperature would translate directly to higher rates of evaporation thereby informing climate response models. Our results confirmed a DOC effect on surface water temperature, but that effect did not translate to enhanced evaporation. Instead the opposite was observed: evaporation rates decreased as DOC increased. Ancillary data and prior studies suggest two explanatory mechanisms: (1) disproportionately greater radiant energy outflux from high DOC lakes, and (2) the combined effect of wind speed (W) and the vapor pressure gradient (es - ez), whose product [W(es - ez)] was lowest on the high DOC lake, despite very low wind speeds (<1.5 m s-1) and steep forested uplands surrounding all three lakes. Agreement between measured (E-pan) and modeled evaporation rates was reasonably good, based on linear regression results (r2: 0.6-0.7; slope: 0.5-0.7, for the best model). Rankings based on E were similar whether determined by measured or modeled criteria (high DOC < low DOC). Across the 3 lakes and 4 years, E averaged ∼3 mm d-1 (C.V. 9%), but statistically significant differences between lakes resulted in substantial differences in cumulative E that were consistent from year to year. Daily water budgets for these lakes show that inputs

  8. Water color affects the stratification, surface temperature, heat content, and mean epilimnetic irradiance of small lakes

    USGS Publications Warehouse

    Houser, J.N.

    2006-01-01

    The effects of water color on lake stratification, mean epilimnetic irradiance, and lake temperature dynamics were examined in small, north-temperate lakes that differed widely in water color (1.5-19.8 m -1). Among these lakes, colored lakes differed from clear lakes in the following ways: (i) the epilimnia were shallower and colder, and mean epilimnetic irradiance was reduced; (ii) the diel temperature cycles were more pronounced; (iii) whole-lake heat accumulation during stratification was reduced. The depth of the epilimnion ranged from 2.5 m in the clearest lake to 0.75 m in the most colored lake, and 91% of the variation in epilimnetic depth was explained by water color. Summer mean morning epilimnetic temperature was ???2??C cooler in the most colored lake compared with the clearest lake. In clear lakes, the diel temperature range (1.4 ?? 0.7??C) was significantly (p = 0.01) less than that in the most colored lake (2.1 ?? 1.0??C). Change in whole-lake heat content was negatively correlated with water color. Increasing water color decreased light penetration more than thermocline depth, leading to reduced mean epilimnetic irradiance in the colored lakes. Thus, in these small lakes, water color significantly affected temperature, thermocline depth, and light climate. ?? 2006 NRC.

  9. Lake warming favours small-sized planktonic diatom species.

    PubMed

    Winder, Monika; Reuter, John E; Schladow, S Geoffrey

    2009-02-01

    Diatoms contribute to a substantial portion of primary production in the oceans and many lakes. Owing to their relatively heavy cell walls and high nutrient requirements, planktonic diatoms are expected to decrease with climate warming because of reduced nutrient redistribution and increasing sinking velocities. Using a historical dataset, this study shows that diatoms were able to maintain their biovolume with increasing stratification in Lake Tahoe over the last decades; however, the diatom community structure changed. Increased stratification and reduced nitrogen to phosphorus ratios selected for small-celled diatoms, particularly within the Cyclotella genus. An empirical model showed that a shift in phytoplankton species composition and cell size was consistent within different depth strata, indicating that altered nutrient concentrations were not responsible for the change. The increase in small-celled species was sufficient to decrease the average diatom size and thus sinking velocity, which strongly influences energy transfer through the food web and carbon cycling. Our results show that within the diverse group of diatoms, small-sized species with a high surface area to volume ratio were able to adapt to a decrease in mixing intensity, supporting the hypotheses that abiotic drivers affect the size structure of planktonic communities and that warmer climate favours small-sized diatom cells. PMID:18812287

  10. 33 CFR 334.830 - Lake Michigan; small-arms range adjacent to U.S. Naval Training Center, Great Lakes, Ill.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 3 2010-07-01 2010-07-01 false Lake Michigan; small-arms range adjacent to U.S. Naval Training Center, Great Lakes, Ill. 334.830 Section 334.830 Navigation and Navigable... REGULATIONS § 334.830 Lake Michigan; small-arms range adjacent to U.S. Naval Training Center, Great Lakes,...

  11. 33 CFR 334.830 - Lake Michigan; small-arms range adjacent to U.S. Naval Training Center, Great Lakes, Ill.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 33 Navigation and Navigable Waters 3 2013-07-01 2013-07-01 false Lake Michigan; small-arms range adjacent to U.S. Naval Training Center, Great Lakes, Ill. 334.830 Section 334.830 Navigation and Navigable... REGULATIONS § 334.830 Lake Michigan; small-arms range adjacent to U.S. Naval Training Center, Great Lakes,...

  12. 33 CFR 334.830 - Lake Michigan; small-arms range adjacent to U.S. Naval Training Center, Great Lakes, Ill.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 3 2014-07-01 2014-07-01 false Lake Michigan; small-arms range adjacent to U.S. Naval Training Center, Great Lakes, Ill. 334.830 Section 334.830 Navigation and Navigable... REGULATIONS § 334.830 Lake Michigan; small-arms range adjacent to U.S. Naval Training Center, Great Lakes,...

  13. 33 CFR 334.830 - Lake Michigan; small-arms range adjacent to U.S. Naval Training Center, Great Lakes, Ill.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 33 Navigation and Navigable Waters 3 2012-07-01 2012-07-01 false Lake Michigan; small-arms range adjacent to U.S. Naval Training Center, Great Lakes, Ill. 334.830 Section 334.830 Navigation and Navigable... REGULATIONS § 334.830 Lake Michigan; small-arms range adjacent to U.S. Naval Training Center, Great Lakes,...

  14. 33 CFR 334.830 - Lake Michigan; small-arms range adjacent to U.S. Naval Training Center, Great Lakes, Ill.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 3 2011-07-01 2011-07-01 false Lake Michigan; small-arms range adjacent to U.S. Naval Training Center, Great Lakes, Ill. 334.830 Section 334.830 Navigation and Navigable... REGULATIONS § 334.830 Lake Michigan; small-arms range adjacent to U.S. Naval Training Center, Great Lakes,...

  15. Eutrophication History of Small Shallow Lakes in Estonia: Evidence from Multiproxy Analysis of Lake Sediments

    NASA Astrophysics Data System (ADS)

    Koff, T.; Marzecova, A.; Vandel, E.; Mikomägi, A.; Avi, E.

    2015-12-01

    Human activities have impacted aquatic systems through the release of contaminants and the regulation of surface and groundwater. Although environmental monitoring has been essential in detecting eutrophication, biodiversity loss or water quality deterioration, monitoring activities are limited in time and are thus not sufficient in their scope to identify causality and thresholds. Paleolimnological studies increasingly show that the response of lakes to climatic and human influences is complex, multidimensional, and often indirectly mediated through watershed processes. In this study we examine the history of eutrophication processes in small lakes in Estonia using the multi-proxy analysis of sediment. Study sites represent lakes with different anthropogenic stressors: urbanisation and recreational use, run-off from an oil shale mine, and fish-kills and liming measures. We have used diverse analytical methods, such as elemental analysis, stable isotopes, fossil pigments, diatoms and Cladocera remains. The information derived from sedimentary indicators broadly agrees with the historical evidence of eutrophication and pollution. Moreover, the sediment records are indispensable for identifying additional issues such as: 1) earlier onset of cultural eutrophication; 2) the significant impact of catchment erosion on the deterioration of lake quality, particularly cyanobacterial blooms; and 3) changes in sedimentation processes with significance for internal biogeochemical cycling of nutrients. Importantly, the integration of several methods has significantly improved interpretation of sedimentary data and elucidated the different strengths of various indicator types. The project findings prove to be highly relevant for both the prediction of the ecological responses of lakes to different anthropogenic impacts and the establishment of reasonable reference target conditions in restoration schemes, as well as for methodological improvements of the sediment analysis.

  16. Seasonal habitat selection by lake trout (Salvelinus namaycush) in a small Canadian shield lake: Constraints imposed by winter conditions

    USGS Publications Warehouse

    Blanchfield, P.J.; Tate, L.S.; Plumb, J.M.; Acolas, M.-L.; Beaty, K.G.

    2009-01-01

    The need for cold, well-oxygenated waters significantly reduces the habitat available for lake trout (Salvelinus namaycush) during stratification of small temperate lakes. We examined the spatial and pelagic distribution of lake trout over two consecutive summers and winters and tested whether winter increased habitat availability and access to littoral regions in a boreal shield lake in which pelagic prey fish are absent. In winter, lake trout had a narrowly defined pelagic distribution that was skewed to the upper 3 m of the water column and spatially situated in the central region of the lake. Individual core areas of use (50% Kernel utilization distributions) in winter were much reduced (75%) and spatially non-overlapping compared to summer areas, but activity levels were similar between seasons. Winter habitat selection is in contrast to observations from the stratified season, when lake trout were consistently located in much deeper waters (>6 m) and widely distributed throughout the lake. Winter distribution of lake trout appeared to be strongly influenced by ambient light levels; snow depth and day length accounted for up to 69% of the variation in daily median fish depth. More restricted habitat use during winter than summer was in contrast to our original prediction and illustrates that a different suite of factors influence lake trout distribution between these seasons. ?? Springer Science+Business Media B.V. 2009.

  17. MANGANESE BIOGEOCHEMISTRY IN A SMALL ADIRONDACK FORESTED LAKE WATERSHED.

    USGS Publications Warehouse

    Shanley, James B.

    1986-01-01

    In September and October 1981, manganese (Mn) concentrations and pH were intensively monitored in a small forested lake watershed in the west-central Adirondack Mountains, New York, during two large acidic storms (each approximately 5 cm rainfall, pH 4. 61 and 4. 15). The data were evaluated to identify biogeochemical pathways of Mn and to assess how these pathways are altered by acidic atmospheric inputs. Concentrations of Mn averaged 1. 1 mu g/L in precipitation and increased to 107 mu g/L in canopy throughfall, the enrichment reflecting active biological cycling of Mn. Rain pH and throughfall Mn were negatively correlated, suggesting that foliar leaching of Mn was enhanced by rainfall acidity. The pulse-like input of Mn to the forest floor in the high initial concentrations in throughfall (approximately 1000 mu g/L) did not affect Mn concentrations in soil water ( less than 20 mu g/L) or groundwater (usually less than 40 mu g/L), which varied little with time. In the inlet stream, Mn concentrations remained constant at 48 mu g/L as discharge varied from 1. 1 to 96 L/s. Manganese was retained in the vegetative cycle and regulated in the stream by adsorption in the soil organic horizon. The higher Mn levels in the stream may be linked to its high acidity (pH 4. 2-4. 3). Mixing of Mn-rich stream water with neutral lake water (pH 7. 0) caused precipitation of Mn and deposition in lake sediment.

  18. Movement of road salt to a small New Hampshire lake

    USGS Publications Warehouse

    Rosenberry, D.O.; Bukaveckas, P.A.; Buso, D.C.; Likens, G.E.; Shapiro, A.M.; Winter, T.C.

    1999-01-01

    Runoff of road salt from an interstate highway in New Hampshire has led to contamination of a lake and a stream that flows into the lake, in spite of the construction of a diversion berm to divert road salt runoff out of the lake drainage basin. Chloride concentration in the stream has increased by over an order of magnitude during the 23 yr since the highway was opened, and chloride concentration in the lake has tripled. Road salt moves to the lake primarily via the contaminated stream, which provides 53% of all the chloride to the lake and only 3% of the total streamflow to the lake. The stream receives discharge of salty water froth leakage through the diversion berm. Uncontaminated ground water dilutes the stream downstream of the berm. However, reversals of gradient during summer months, likely caused by transpiration from deciduous trees, result in flow of contaminated stream water into the adjacent ground water along the lowest 40-m reach of the stream. This contaminated ground water then discharges into the lake along a 70-m-wide segment of lake shore. Road salt is pervasive in the bedrock between the highway and the lake, but was not detected at all of the wells in the glacial overburden. Of the 500 m of shoreline that could receive discharge of saly ground water directly from the highway, only a 50-m-long segment appears to be contaminated.

  19. Effects of nitrate fertilization on CO2 and CH4 concentrations in small boreal lakes

    NASA Astrophysics Data System (ADS)

    Klaus, Marcus; Bergström, Ann-Kristin; Karlsson, Jan

    2013-04-01

    Ecosystem functioning in boreal lakes is largely affected by atmospheric nitrogen loading enhanced by anthropogenic activities. Additional deposition of nitrate entering these systems affects pelagic metabolic processes and thus the production and consumption of aquatic greenhouse gases. This study assesses the effect of nitrate fertilization on concentrations of dissolved carbon dioxide (CO2) and methane (CH4) in six small lakes in northern Sweden (area: 1.0-4.8 ha, max. depth: 4.5-8.5 m) with three different levels of dissolved organic carbon (DOC) concentrations (clear lakes: 7 mg l-1, medium brown lakes: 13 mg l-1, dark brown lakes: 18 mg l-1). A whole lake fertilization experiment was carried out utilizing a Before-After-Control-Impact (BACI) design with one reference year (2011) and one impact year (2012); including one control lake and one impact lake for each DOC level. During 2012, the impact lakes were fertilized with potassium nitrate once in March and biweekly from June to September. Fertilization caused epilimnion total nitrogen concentration to increase by around 10% in the impact lakes relative to the reference year while it decreased by around 20% in the control lakes. From June to September, epilimnion water was sampled biweekly by grab sampling and analyzed in the field by an infrared gas analyzer or in the laboratory using a gas chromatographer. Three additional samples were taken along a depth profile on three occasions. In the reference year, concentrations of CO2 and CH4 did not differ significantly between control and impact lakes (p>0.05). In the impact year, epilimnion CO2 concentrations were significantly higher compared to the reference year in all medium and dark brown lakes. Fertilization mostly caused a slight reduction in CO2 and CH4 concentrations in the impact lakes relative to the control lakes. This effect was not significant but most pronounced and coherent across the whole water column in clear lakes. In clear lakes, CO2 and CH4

  20. Dissolved organic carbon export and internal cycling in small, headwater lakes

    USGS Publications Warehouse

    Stets, Edward G.; Striegl, Rob; Aiken, George R.

    2010-01-01

    Carbon (C) cycling in freshwater lakes is intense but poorly integrated into our current understanding of overall C transport from the land to the oceans. We quantified dissolved organic carbon export (DOCX) and compared it with modeled gross DOC mineralization (DOCR) to determine whether hydrologic or within-lake processes dominated DOC cycling in a small headwaters watershed in Minnesota, USA. We also used DOC optical properties to gather information about DOC sources. We then compared our results to a data set of approximately 1500 lakes in the Eastern USA (Eastern Lake Survey, ELS, data set) to place our results in context of lakes more broadly. In the open-basin lakes in our watershed (n = 5), DOCX ranged from 60 to 183 g C m−2 lake area yr−1, whereas DOCR ranged from 15 to 21 g C m−2 lake area yr−1, emphasizing that lateral DOC fluxes dominated. DOCX calculated in our study watershed clustered near the 75th percentile of open-basin lakes in the ELS data set, suggesting that these results were not unusual. In contrast, DOCX in closed-basin lakes (n = 2) was approximately 5 g C m−2 lake area yr−1, whereas DOCR was 37 to 42 g C m−2 lake area yr−1, suggesting that internal C cycling dominated. In the ELS data set, median DOCX was 32 and 12 g C m−2 yr−1 in open-basin and closed-basin lakes, respectively. Although not as high as what was observed in our study watershed, DOCX is an important component of lake C flux more generally, particularly in open-basin lakes.

  1. Suspended sediment and metals removal from urban runoff by a small lake

    USGS Publications Warehouse

    Striegl, R.G.

    1987-01-01

    A small lake in the Chicago Metropolitan Area was from 91 to 95 percent efficient in removing suspended sediment and from 76 to 94 percent efficient in removing copper, iron, lead, and zinc from urban runoff. Sediments accumulated in the lake in the form of an organic-rich mud at an average rate of 20 millimeters per year; this reduced lake storage and covered potential habitat for aquatic organisms. Copper, lead, and zinc concentrations were closely associated with suspended-sediment concentrations and with silt- and clay-sized fractions of lake sediment. Although concentrations of mercury and cadmium were near detection limits in runoff, measurable concentrations of these metals accumulated in the lake sediments.A small lake in the Chicago Metropolitan Area was from 91 to 95 percent efficient in removing suspended sediment and from 76 to 94 percent efficient in removing copper, iron, lead, and zinc from urban runoff. Sediments accumulated in the lake in the form of an organic-rich mud at an average rate of 20 millimeters per year; this reduced lake storage and covered potential habitat for aquatic organisms. Copper, lead, and zinc concentrations were closely associated with suspended sediment concentrations and with silt- and clay-sized fractions of lake sediment. Although concentrations of mercury and cadmium were near detection limits in runoff, measurable concentrations of these metals accumulated in the lake sediments.

  2. Angler effort and catch within a spatially complex system of small lakes.

    USGS Publications Warehouse

    Pope, Kevin L.; Chizinski, Christopher J.; Martin, Dustin R.; Barada, Tony J.; Schuckman, Jeffrey J.

    2014-01-01

    Spatial layout of waterbodies and waterbody size can affect a creel clerk’s ability to intercept anglers for interviews and to accurately count anglers, which will affect the accuracy and precision of estimates of effort and catch. This study aimed to quantify angling effort and catch across a spatially complex system of 19 small (<100 ha) lakes, the Fremont lakes. Total (±SE) angling effort (hours) on individual lakes ranged from 0 (0) to 7,137 (305). Bank anglers utilized 18 of the 19 lakes, and their mean (±SE) trip lengths (hours) ranged from 0.80 (0.31) to 7.75 (6.75), depending on the waterbody. In contrast, boat anglers utilized 14 of the 19 lakes, and their trip lengths ranged from 1.39 (0.24) to 4.25 (0.71), depending on the waterbody. The most sought fishes, as indexed by number of lakes on which effort was exerted, were anything (17 of 19 lakes), largemouth bassMicropterus salmoides (15 of 19 lakes), and channel catfish Ictalurus punctatus (13 of 19 lakes). Bluegill Lepomis machrochirus, crappie Pomoxis spp., and largemouth bass were caught most frequently across the lakes, but catch rates varied considerably by lake. Of the 1,138 parties interviewed, most parties (93%) visited a single lake but there were 77 (7%) parties that indicated that they had visited multiple lakes during a single day. The contingent of parties that visited more than one lake a day were primarily (87%) bank anglers.. The number of lake-to-lake connections made by anglers visiting more than one waterbody during a single day was related to catch rates and total angling effort. The greater resolution that was achieved with a lake specific creel survey at Fremont lakes revealed a system of lakes with a large degree of spatial variation in angler effort and catch that would be missed by a coarser, system-wide survey that did not differentiate individual lakes.

  3. ARSENIC CYCLING WITHIN THE WATER COLUMN OF A SMALL LAKE RECEIVING CONTAMINATED GROUND WATER DISCHARGE

    EPA Science Inventory

    The fate of arsenic discharged from contaminated ground water to a small, shallow lake at a hazardous waste site is controlled, in part, by the rate of ferrous iron oxidation-precipitation and arsenic sorption occurring near the lake chemocline. Laboratory experiments were condu...

  4. Morphometric analysis of Russian Plain's small lakes on the base of accurate digital bathymetric models

    NASA Astrophysics Data System (ADS)

    Naumenko, Mikhail; Guzivaty, Vadim; Sapelko, Tatiana

    2016-04-01

    Lake morphometry refers to physical factors (shape, size, structure, etc) that determine the lake depression. Morphology has a great influence on lake ecological characteristics especially on water thermal conditions and mixing depth. Depth analyses, including sediment measurement at various depths, volumes of strata and shoreline characteristics are often critical to the investigation of biological, chemical and physical properties of fresh waters as well as theoretical retention time. Management techniques such as loading capacity for effluents and selective removal of undesirable components of the biota are also dependent on detailed knowledge of the morphometry and flow characteristics. During the recent years a lake bathymetric surveys were carried out by using echo sounder with a high bottom depth resolution and GPS coordinate determination. Few digital bathymetric models have been created with 10*10 m spatial grid for some small lakes of Russian Plain which the areas not exceed 1-2 sq. km. The statistical characteristics of the depth and slopes distribution of these lakes calculated on an equidistant grid. It will provide the level-surface-volume variations of small lakes and reservoirs, calculated through combination of various satellite images. We discuss the methodological aspects of creating of morphometric models of depths and slopes of small lakes as well as the advantages of digital models over traditional methods.

  5. Seasonal changes in the spatial distribution of phytoplankton in small, temperate-zone lakes

    USGS Publications Warehouse

    Cloern, J.E.; Alpine, A.E.; Cole, B.E.; Heller, T.

    1992-01-01

    Sampling across two N Minnesota small lakes shows that phytoplankton patchiness is greatly enhanced during winter ice-cover relative to the open-water seasons of exposure to wind stress and rapid turbulent mixing. -Authors

  6. LANDSCAPE INFLUENCES ON LAKE CHEMISTRY OF SMALL DIMICTIC LAKES IN THE HUMAN DOMINATED SOUTHERN WISCONSIN LANDSCAPE

    EPA Science Inventory

    Changes in landscape heterogeneity, historic landcover change, and human disturbance regimes are governed by complex interrelated landscape processes that modify lake water quality through the addition of nutrients, sediment, anthropogenic chemicals, and changes in major ion conc...

  7. Groundwater-surface water interactions: the behavior of a small lake connected to groundwater

    NASA Astrophysics Data System (ADS)

    Arnoux, Marie; Barbecot, Florent; Gibert-Brunet, Elisabeth

    2016-04-01

    Interactions between lakes and groundwater have been under concern in recent years and are still not well understood. Exchange rates are both spatially and temporally highly variable and are generally underestimated. However these interactions are of utmost importance for water resource management and need to be better understood since (i) the hydrogeological and geochemical equilibria within the lake drive the evolution of lakes' ecology and quality, and (ii) groundwater inflow, even in low rate, can be a key element in both the lake nutrient balance (and therefore in lake's eutrophication) and vulnerability to pollution. In many studies two main geochemical tracers, i.e. water stable isotopes and radon-222, are used to determine these interactions. However there are still many uncertainties on their time and space variations and their reliability to determine the lake budget. Therefore, a lake connected to groundwater on a small catchment was chosen to quantify groundwater fluxes change over time and the related influences on the lake's water geochemistry. Through analyse in time and space of both tracers and a precise instrumentation of the lake, their variations linked to groundwater inflows are determined. The results show that each tracer provides additional information for the lake budget with the interest to well determine the information given by each measurement: the radon-222 gives information on the groundwater inflows at a point in space and time while water stable isotopes highlight the dominant parameters of the yearly lake budget. The variation in groundwater inflows allow us to discuss lake's evolution regarding climate and environmental changes.

  8. Land Use Affects Carbon Sources to the Pelagic Food Web in a Small Boreal Lake.

    PubMed

    Rinta, Päivi; van Hardenbroek, Maarten; Jones, Roger I; Kankaala, Paula; Rey, Fabian; Szidat, Sönke; Wooller, Matthew J; Heiri, Oliver

    2016-01-01

    Small humic forest lakes often have high contributions of methane-derived carbon in their food webs but little is known about the temporal stability of this carbon pathway and how it responds to environmental changes on longer time scales. We reconstructed past variations in the contribution of methanogenic carbon in the pelagic food web of a small boreal lake in Finland by analyzing the stable carbon isotopic composition (δ13C values) of chitinous fossils of planktivorous invertebrates in sediments from the lake. The δ13C values of zooplankton remains show several marked shifts (approx. 10 ‰), consistent with changes in the proportional contribution of carbon from methane-oxidizing bacteria in zooplankton diets. The results indicate that the lake only recently (1950s) obtained its present state with a high contribution of methanogenic carbon to the pelagic food web. A comparison with historical and palaeobotanical evidence indicates that this most recent shift coincided with agricultural land-use changes and forestation of the lake catchment and implies that earlier shifts may also have been related to changes in forest and land use. Our study demonstrates the sensitivity of the carbon cycle in small forest lakes to external forcing and that the effects of past changes in local land use on lacustrine carbon cycling have to be taken into account when defining environmental and ecological reference conditions in boreal headwater lakes. PMID:27487044

  9. Land Use Affects Carbon Sources to the Pelagic Food Web in a Small Boreal Lake

    PubMed Central

    Rinta, Päivi; van Hardenbroek, Maarten; Jones, Roger I.; Kankaala, Paula; Rey, Fabian; Szidat, Sönke; Wooller, Matthew J.; Heiri, Oliver

    2016-01-01

    Small humic forest lakes often have high contributions of methane-derived carbon in their food webs but little is known about the temporal stability of this carbon pathway and how it responds to environmental changes on longer time scales. We reconstructed past variations in the contribution of methanogenic carbon in the pelagic food web of a small boreal lake in Finland by analyzing the stable carbon isotopic composition (δ13C values) of chitinous fossils of planktivorous invertebrates in sediments from the lake. The δ13C values of zooplankton remains show several marked shifts (approx. 10 ‰), consistent with changes in the proportional contribution of carbon from methane-oxidizing bacteria in zooplankton diets. The results indicate that the lake only recently (1950s) obtained its present state with a high contribution of methanogenic carbon to the pelagic food web. A comparison with historical and palaeobotanical evidence indicates that this most recent shift coincided with agricultural land-use changes and forestation of the lake catchment and implies that earlier shifts may also have been related to changes in forest and land use. Our study demonstrates the sensitivity of the carbon cycle in small forest lakes to external forcing and that the effects of past changes in local land use on lacustrine carbon cycling have to be taken into account when defining environmental and ecological reference conditions in boreal headwater lakes. PMID:27487044

  10. VERTICAL DIFFUSION IN SMALL STRATIFIED LAKES: DATA AND ERROR ANALYSIS

    EPA Science Inventory

    Water temperature profiles were measured at 2-min intervals in a stratified temperate lake with a surface area of 0.06 km2 and a aximum depth of 10 m from May 7 to August 9, 1989. he data were used to calculate the vertical eddy diffusion coefficient K2 in the hypolimnion. he dep...

  11. Evaluation of groundwater discharge into small lakes based on the temporal distribution of radon-222

    USGS Publications Warehouse

    Dimova, N.T.; Burnett, W.C.

    2011-01-01

    In order to evaluate groundwater discharge into small lakes we constructed a model that is based on the budget of 222Rn (radon t1/2 5 3.8 d) as a tracer. The main assumptions in our model are that the lake's waters are wellmixed horizontally and vertically; the only significant 222Rn source is via groundwater discharge; and the only losses are due to decay and atmospheric evasion. In order to evaluate the groundwater-derived 222Rn flux, we monitored the 222Rn concentration in lake water over periods long enough (usually 1-3 d) to observe changes likely caused by variations in atmospheric exchange (primarily a function of wind speed and temperature). We then attempt to reproduce the observed record by accounting for decay and atmospheric losses and by estimating the total 222Rn input flux using an iterative approach. Our methodology was tested in two lakes in central Florida: one of which is thought to have significant groundwater inputs (Lake Haines) and another that is known not to have any groundwater inflows but requires daily groundwater augmentation from a deep aquifer (Round Lake). Model results were consistent with independent seepage meter data at both Lake Haines (positive seepage of ??? 1.6 ?? 104 m3 d-1 in Mar 2008) and at Round Lake (no net groundwater seepage). ?? 2011, by the American Society of Limnology and Oceanography, Inc.

  12. Combining high-resolution satellite images and altimetry to estimate the volume of small lakes

    NASA Astrophysics Data System (ADS)

    Baup, F.; Frappart, F.; Maubant, J.

    2014-05-01

    This study presents an approach to determining the volume of water in small lakes (<100 ha) by combining satellite altimetry data and high-resolution (HR) images. In spite of the strong interest in monitoring surface water resources on a small scale using radar altimetry and satellite imagery, no information is available about the limits of the remote-sensing technologies for small lakes mainly used for irrigation purposes. The lake being studied is located in the south-west of France and is only used for agricultural irrigation purposes. The altimetry satellite data are provided by an RA-2 sensor onboard Envisat, and the high-resolution images (<10 m) are obtained from optical (Formosat-2) and synthetic aperture radar (SAR) antenna (Terrasar-X and Radarsat-2) satellites. The altimetry data (data are obtained every 35 days) and the HR images (77) have been available since 2003 and 2010, respectively. In situ data (for the water levels and volumes) going back to 2003 have been provided by the manager of the lake. Three independent approaches are developed to estimate the lake volume and its temporal variability. The first two approaches (HRBV and ABV) are empirical and use synchronous ground measurements of the water volume and the satellite data. The results demonstrate that altimetry and imagery can be effectively and accurately used to monitor the temporal variations of the lake (R2ABV = 0.98, RMSEABV = 5%, R2HRBV = 0.90, and RMSEABV = 7.4%), assuming a time-varying triangular shape for the shore slope of the lake (this form is well adapted since it implies a difference inferior to 2% between the theoretical volume of the lake and the one estimated from bathymetry). The third method (AHRBVC) combines altimetry (to measure the lake level) and satellite images (of the lake surface) to estimate the volume changes of the lake and produces the best results (R2AHRBVC = 0.98) of the three methods, demonstrating the potential of future Sentinel and SWOT missions to

  13. Small lakes in big landscape: Multi-scale drivers of littoral ecosystem in alpine lakes.

    PubMed

    Zaharescu, Dragos G; Burghelea, Carmen I; Hooda, Peter S; Lester, Richard N; Palanca-Soler, Antonio

    2016-05-01

    In low nutrient alpine lakes, the littoral zone is the most productive part of the ecosystem, and it is a biodiversity hotspot. It is not entirely clear how the scale and physical heterogeneity of surrounding catchment, its ecological composition, and larger landscape gradients work together to sustain littoral communities. A total of 113 alpine lakes from the central Pyrenees were surveyed to evaluate the functional connectivity between littoral zoobenthos and landscape physical and ecological elements at geographical, catchment and local scales, and to ascertain how they affect the formation of littoral communities. At each lake, the zoobenthic composition was assessed together with geolocation, catchment hydrodynamics, geomorphology and topography, riparian vegetation composition, the presence of trout and frogs, water pH and conductivity. Multidimensional fuzzy set models integrating benthic biota and environmental variables revealed that at geographical scale, longitude unexpectedly surpassed altitude and latitude in its effect on littoral ecosystem. This reflects a sharp transition between Atlantic and Mediterranean climates and suggests a potentially high horizontal vulnerability to climate change. Topography (controlling catchment type, snow coverage and lakes connectivity) was the most influential catchment-scale driver, followed by hydrodynamics (waterbody size, type and volume of inflow/outflow). Locally, riparian plant composition significantly related to littoral community structure, richness and diversity. These variables, directly and indirectly, create habitats for aquatic and terrestrial stages of invertebrates, and control nutrient and water cycles. Three benthic associations characterised distinct lakes. Vertebrate predation, water conductivity and pH had no major influence on littoral taxa. This work provides exhaustive information from relatively pristine sites, and unveils a strong connection between littoral ecosystem and catchment

  14. Diatoms as food of larval sea lampreys in a small tributary of northern Lake Michigan

    USGS Publications Warehouse

    Manion, Patrick J.

    1967-01-01

    The food and food preferences of sea lamprey ammocoetes have not been investigated. The food of the larval American brook lamprey, Lampetra lamottei, in the Great Lakes region consisted mainly of diatoms and desmids according to Creaser and Hann. Schroll discussed the biology of feeding of ammocoetes of Lampetra planeri and Eudontomyzon danfordi in Europe. This report presents data on the availability and use of diatoms by sea lamprey, Petromyzon marinus Linnaeus, ammocoetes in a small tributary of northern Lake Michigan.

  15. Small ecosystem engineers as important regulators of lake's sediment respiration.

    NASA Astrophysics Data System (ADS)

    Baranov, Victor; Lewandowski, Joerg; Krause, Stefan; Romeijn, Paul

    2016-04-01

    Although shallow lakes are covering only about 1.5% of the land surface of the Earth, they are responsible for sequestration of carbon amounts similar or even larger than those sequestered in all marine sediments. One of the most important drivers of the carbon sequestration in lakes is sediment respiration. Especially in shallow lakes, bioturbation, i.e. the biogenic reworking of the sediment matrix and the transport of fluids within the sediment, severely impacts on sediment respiration. Widespread freshwater bioturbators such as chironomid larvae (Diptera, Chironomidae) are building tubes in the sediment and actively pump water through their burrows (ventilation). In the present work we study how different organism densities and temperatures (5-30°C) impact on respiration rates. In a microcosm experiment the bioreactive resazurin/resorufin smart tracer system was applied for quantifying the impacts of different densities of Chironomidae (Diptera) larvae (0, 1000, 2000 larvae/m2) on sediment respiration. Tracer transformation rates (and sediment respiration) were correlated with larval densities with highest transformation rates occurring in microcosms with highest larval densities. Respiration differences between defaunated sediment and sediment with 1000 and 2000 larvae per m2 was insignificant at 5 °C, and was progressively increasing with rising temperatures. At 30 °C respiration rates of sediment with 2000 larvae per m2 was 4.8 times higher than those of defaunated sediment. We interpret this as an effect of temperature on larval metabolic and locomotory activity. Furthermore, bacterial communities are benefiting from the combination of the high water temperatures and bioirrigation as bacterial community are able to maintain high metabolic rates due to oxygen supplied by bioirrigation. In the context of global climate change that means that chironomid ecosystem engineering activity will have a profound and increasing impact on lake sediment respiration

  16. LANDSCAPE INFLUENCES ON LAKE CHEMISTRY AND OSTRACOD COMMUNITY STRUCTURE OF SMALL DIMICTIC LAKES IN SOUTHERN WISCONSIN DIMICTIC LAKES

    EPA Science Inventory

    The natural land cover patterns that characterize the southern part of Wisconsin are legacies of a

    glaciated past. Land cover pattern and geomorphology control the hydrologic connections between water

    resources and the land by which ecosystems, including lakes are o...

  17. Combining high-resolution satellite images and altimetry to estimate the volume of small lakes

    NASA Astrophysics Data System (ADS)

    Baup, F.; Frappart, F.; Maubant, J.

    2013-12-01

    This study presents an approach to determine the volume of water in small lakes (<100 ha) by combining satellite altimetry data and high-resolution (HR) images. The lake being studied is located in the south-west of France and is only used for agricultural irrigation purposes. The altimetry satellite data are provided by RA-2 sensor on board Envisat, and the high-resolution images (<10 m) are obtained from optical (Formosat-2) and synthetic aperture radar (SAR) sensors (Terrasar-X and Radarsat-2) satellites. The altimetry data (data are obtained every 35 days) and the HR images (45) have been available since 2003 and 2010, respectively. In situ data (for the water levels and volumes) going back to 2003 have been provided by the manager of the lake. Three independent approaches are developed to estimate the lake volume and its temporal variability. The first two approaches are empirical and use synchronous ground measurements of the water volume and the satellite data. The results demonstrate that altimetry and imagery can be effectively and accurately used to monitor the temporal variations of the lake (R2altimetry = 0.97, RMSEaltimetry = 5.2%, R2imagery = 0.90, and RMSEimagery = 7.4%). The third method combines altimetry (to measure the lake level) and satellite images (of the lake surface) to estimate the volume changes of the lake and produces the best results (R2 = 0.99) of the three methods, demonstrating the potential of future Sentinel and SWOT missions to monitor small lakes and reservoirs for agricultural and irrigation applications.

  18. On the System of Person-Denoting Signs in Estonian Sign Language: Estonian Name Signs

    ERIC Educational Resources Information Center

    Paales, Liina

    2010-01-01

    This article discusses Estonian personal name signs. According to study there are four personal name sign categories in Estonian Sign Language: (1) arbitrary name signs; (2) descriptive name signs; (3) initialized-descriptive name signs; (4) loan/borrowed name signs. Mostly there are represented descriptive and borrowed personal name signs among…

  19. Comparison of 15 evaporation methods applied to a small mountain lake in the northeastern USA

    USGS Publications Warehouse

    Rosenberry, D.O.; Winter, T.C.; Buso, D.C.; Likens, G.E.

    2007-01-01

    Few detailed evaporation studies exist for small lakes or reservoirs in mountainous settings. A detailed evaporation study was conducted at Mirror Lake, a 0.15 km2 lake in New Hampshire, northeastern USA, as part of a long-term investigation of lake hydrology. Evaporation was determined using 14 alternate evaporation methods during six open-water seasons and compared with values from the Bowen-ratio energy-budget (BREB) method, considered the standard. Values from the Priestley-Taylor, deBruin-Keijman, and Penman methods compared most favorably with BREB-determined values. Differences from BREB values averaged 0.19, 0.27, and 0.20 mm d-1, respectively, and results were within 20% of BREB values during more than 90% of the 37 monthly comparison periods. All three methods require measurement of net radiation, air temperature, change in heat stored in the lake, and vapor pressure, making them relatively data intensive. Several of the methods had substantial bias when compared with BREB values and were subsequently modified to eliminate bias. Methods that rely only on measurement of air temperature, or air temperature and solar radiation, were relatively cost-effective options for measuring evaporation at this small New England lake, outperforming some methods that require measurement of a greater number of variables. It is likely that the atmosphere above Mirror Lake was affected by occasional formation of separation eddies on the lee side of nearby high terrain, although those influences do not appear to be significant to measured evaporation from the lake when averaged over monthly periods. ?? 2007 Elsevier B.V. All rights reserved.

  20. Small Changes in Climate Can Profoundly Alter the Dynamics and Ecosystem Services of Tropical Crater Lakes

    PubMed Central

    Saulnier-Talbot, Émilie; Gregory-Eaves, Irene; Simpson, Kyle G.; Efitre, Jackson; Nowlan, Tobias E.; Taranu, Zofia E.; Chapman, Lauren J.

    2014-01-01

    African tropical lakes provide vital ecosystem services including food and water to some of the fastest growing human populations, yet they are among the most understudied ecosystems in the world. The consequences of climate change and other stressors on the tropical lakes of Africa have been informed by long-term analyses, but these studies have largely focused on the massive Great Rift Valley lakes. Our objective was to evaluate how recent climate change has altered the functioning and services of smaller tropical lakes, which are far more abundant on the landscape. Based on a paired analysis of 20 years of high-resolution water column data and a paleolimnological record from a small crater lake in western Uganda, we present evidence that even a modest warming of the air (∼0.9°C increase over 20 years) and changes in the timing and intensity of rainfall can have significant consequences on the dynamics of this common tropical lake type. For example, we observed a significant nonlinear increase (R2adj = 0.23, e.d.f. = 7, p<0.0001) in thermal stability over the past 20 years. This resulted in the expansion of anoxic waters and consequent deterioration of fish habitat and appears to have abated primary production; processes that may impair ecosystem services for a vulnerable human population. This study on a system representative of small tropical crater lakes highlights the far-reaching effects of global climatic change on tropical waters. Increased research efforts into tropical aquatic ecosystem health and the development of sound management practices are necessary in order to strengthen adaptive capabilities in tropical regions. PMID:24497954

  1. Small changes in climate can profoundly alter the dynamics and ecosystem services of tropical crater lakes.

    PubMed

    Saulnier-Talbot, Émilie; Gregory-Eaves, Irene; Simpson, Kyle G; Efitre, Jackson; Nowlan, Tobias E; Taranu, Zofia E; Chapman, Lauren J

    2014-01-01

    African tropical lakes provide vital ecosystem services including food and water to some of the fastest growing human populations, yet they are among the most understudied ecosystems in the world. The consequences of climate change and other stressors on the tropical lakes of Africa have been informed by long-term analyses, but these studies have largely focused on the massive Great Rift Valley lakes. Our objective was to evaluate how recent climate change has altered the functioning and services of smaller tropical lakes, which are far more abundant on the landscape. Based on a paired analysis of 20 years of high-resolution water column data and a paleolimnological record from a small crater lake in western Uganda, we present evidence that even a modest warming of the air (∼0.9°C increase over 20 years) and changes in the timing and intensity of rainfall can have significant consequences on the dynamics of this common tropical lake type. For example, we observed a significant nonlinear increase (R(2) adj  = 0.23, e.d.f. = 7, p<0.0001) in thermal stability over the past 20 years. This resulted in the expansion of anoxic waters and consequent deterioration of fish habitat and appears to have abated primary production; processes that may impair ecosystem services for a vulnerable human population. This study on a system representative of small tropical crater lakes highlights the far-reaching effects of global climatic change on tropical waters. Increased research efforts into tropical aquatic ecosystem health and the development of sound management practices are necessary in order to strengthen adaptive capabilities in tropical regions. PMID:24497954

  2. Water quality parameters response to temperature change in small shallow lakes

    NASA Astrophysics Data System (ADS)

    Xu, Lei; Li, Hua; Liang, Xinqiang; Yao, Yuxin; Zhou, Li; Cui, Xinyi

    Effects of temperature (T) on water quality of three small shallow lakes in Taihu Lake region of China were investigated. The annual temperature was classified into three levels: low temperature (LT, 4 °C < T ⩽ 10 °C), middle temperature (MT, 10 °C < T ⩽ 20 °C), and high temperature (HT, 20 °C < T ⩽ 30 °C). Results showed that total nitrogen (TN) and total phosphorus (TP) concentrations might go to a fixed value (or range) in small shallow lakes receiving domestic sewage and farm drainage water. Nitrogen concentrations in the lakes were mainly in the form of nitrate (NO3-) at above concerned three temperature levels, and nitrogen concentrations in the forms of TN, TIN, and NO3- were increased with the increase of nutrient input. At the LT and MT levels, there was a series of good cubic curve relationships between temperatures and three N forms (TN, NO3- and NH4+). The temperatural inflexion change points in the curves were nearly at 7 °C and 14 °C, respectively. However, no significant relationship between temperature and any water quality parameter was observed at the HT level. The significant relationship of TIN to TN, NO3- to TN and NH4+ to dissolve oxygen (DO) was exist in three temperature portions, and TP to Chemical oxygen demand (COD, determined by potassium permanganate oxidation methods) in LT and MT, TP to pH or DO in HT also exist. COD were less than 6 mg L-1 at each temperature level, and pH values were the largest in HT than it in LT or MT. Thus, changes between temperature and water quality parameters (TN, NO3-, NH4+ and TP) obviously nearly in 7 °C or 14 °C in lakes show that water self-purification of natural small shallow lakes were obviously with temperature changed.

  3. Algal Diet of Small-Bodied Crustacean Zooplankton in a Cyanobacteria-Dominated Eutrophic Lake.

    PubMed

    Tõnno, Ilmar; Agasild, Helen; Kõiv, Toomas; Freiberg, Rene; Nõges, Peeter; Nõges, Tiina

    2016-01-01

    Small-bodied cladocerans and cyclopoid copepods are becoming increasingly dominant over large crustacean zooplankton in eutrophic waters where they often coexist with cyanobacterial blooms. However, relatively little is known about their algal diet preferences. We studied grazing selectivity of small crustaceans (the cyclopoid copepods Mesocyclops leuckarti, Thermocyclops oithonoides, Cyclops kolensis, and the cladocerans Daphnia cucullata, Chydorus sphaericus, Bosmina spp.) by liquid chromatographic analyses of phytoplankton marker pigments in the shallow, highly eutrophic Lake Võrtsjärv (Estonia) during a seasonal cycle. Copepods (mainly C. kolensis) preferably consumed cryptophytes (identified by the marker pigment alloxanthin in gut contents) during colder periods, while they preferred small non-filamentous diatoms and green algae (identified mainly by diatoxanthin and lutein, respectively) from May to September. All studied cladoceran species showed highest selectivity towards colonial cyanobacteria (identified by canthaxanthin). For small C. sphaericus, commonly occuring in the pelagic zone of eutrophic lakes, colonial cyanobacteria can be their major food source, supporting their coexistence with cyanobacterial blooms. Pigments characteristic of filamentous cyanobacteria and diatoms (zeaxanthin and fucoxanthin, respectively), algae dominating in Võrtsjärv, were also found in the grazers' diet but were generally avoided by the crustaceans commonly dominating the zooplankton assemblage. Together these results suggest that the co-occurring small-bodied cyclopoid and cladoceran species have markedly different algal diets and that the cladocera represent the main trophic link transferring cyanobacterial carbon to the food web in a highly eutrophic lake. PMID:27124652

  4. Algal Diet of Small-Bodied Crustacean Zooplankton in a Cyanobacteria-Dominated Eutrophic Lake

    PubMed Central

    Tõnno, Ilmar; Agasild, Helen; Kõiv, Toomas; Freiberg, Rene; Nõges, Peeter; Nõges, Tiina

    2016-01-01

    Small-bodied cladocerans and cyclopoid copepods are becoming increasingly dominant over large crustacean zooplankton in eutrophic waters where they often coexist with cyanobacterial blooms. However, relatively little is known about their algal diet preferences. We studied grazing selectivity of small crustaceans (the cyclopoid copepods Mesocyclops leuckarti, Thermocyclops oithonoides, Cyclops kolensis, and the cladocerans Daphnia cucullata, Chydorus sphaericus, Bosmina spp.) by liquid chromatographic analyses of phytoplankton marker pigments in the shallow, highly eutrophic Lake Võrtsjärv (Estonia) during a seasonal cycle. Copepods (mainly C. kolensis) preferably consumed cryptophytes (identified by the marker pigment alloxanthin in gut contents) during colder periods, while they preferred small non-filamentous diatoms and green algae (identified mainly by diatoxanthin and lutein, respectively) from May to September. All studied cladoceran species showed highest selectivity towards colonial cyanobacteria (identified by canthaxanthin). For small C. sphaericus, commonly occuring in the pelagic zone of eutrophic lakes, colonial cyanobacteria can be their major food source, supporting their coexistence with cyanobacterial blooms. Pigments characteristic of filamentous cyanobacteria and diatoms (zeaxanthin and fucoxanthin, respectively), algae dominating in Võrtsjärv, were also found in the grazers’ diet but were generally avoided by the crustaceans commonly dominating the zooplankton assemblage. Together these results suggest that the co-occurring small-bodied cyclopoid and cladoceran species have markedly different algal diets and that the cladocera represent the main trophic link transferring cyanobacterial carbon to the food web in a highly eutrophic lake. PMID:27124652

  5. Identification of nitrogen sources to four small lakes in the agricultural region of Khorezm, Uzbekistan

    USGS Publications Warehouse

    Shanafield, M.; Rosen, M.; Saito, L.; Chandra, S.; Lamers, J.; Nishonov, Bakhriddin

    2010-01-01

    Pollution of inland waters by agricultural land use is a concern in many areas of the world, and especially in arid regions, where water resources are inherently scarce. This study used physical and chemical water quality and stable nitrogen isotope (δ15N) measurements from zooplankton to examine nitrogen (N) sources and concentrations in four small lakes of Khorezm, Uzbekistan, an arid, highly agricultural region, which is part of the environmentally-impacted Aral Sea Basin. During the 2-year study period, ammonium concentrations were the highest dissolved inorganic N species in all lakes, with a maximum of 3.00 mg N l−1 and an average concentration of 0.62 mg N l−1. Nitrate levels were low, with a maximum concentration of 0.46 mg N l−1 and an average of 0.05 mg N l−1 for all four lakes. The limited zooplankton δ15N values did not correlate with the high loads of synthetic fertilizer applied to local croplands during summer months. These results suggest that the N cycles in these lakes may be more influenced by regional dynamics than agricultural activity in the immediate surroundings. The Amu-Darya River, which provides the main source of irrigation water to the region, was identified as a possible source of the primary N input to the lakes.

  6. Lake

    ERIC Educational Resources Information Center

    Wien, Carol Anne

    2008-01-01

    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…

  7. Estonian Literature in the Schools of the Estonian-Russian Population (Changes in Literacy).

    ERIC Educational Resources Information Center

    Ots, Loone

    1997-01-01

    Describes how Estonian language and literature have been taught at Russian-language schools in Estonia. Notes a lack of interesting reading materials, and describes how this instruction could be improved. (SR)

  8. Are small-scale irrigators water use efficient? Evidence from lake Naivasha basin, Kenya.

    PubMed

    Njiraini, Georgina W; Guthiga, Paul M

    2013-11-01

    With increasing water scarcity and competing uses and users, water use efficiency is becoming increasingly important in many parts of developing countries. The lake Naivasha basin has an array of different water users and uses ranging from large scale export market agriculture, urban domestic water users to small holder farmers. The small scale farmers are located in the upper catchment areas and form the bulk of the users in terms of area and population. This study used farm household data to explore the overall technical efficiency, irrigation water use efficiency and establish the factors influencing water use efficiency among small scale farmers in the Lake Naivasha basin in Kenya. Data envelopment analysis, general algebraic and modeling system, and Tobit regression methods were used in analyzing cross sectional data from a sample of 201 small scale irrigation farmers in the lake Naivasha basin. The results showed that on average, the farmers achieved only 63 % technical efficiency and 31 % water use efficiency. This revealed that substantial inefficiencies occurred in farming operations among the sampled farmers. To improve water use efficiency, the study recommends that more emphasis be put on orienting farmers toward appropriate choice of irrigation technologies, appropriate choice of crop combinations in their farms, and the attainment of desirable levels of farm fragmentation. PMID:23954914

  9. Are Small-Scale Irrigators Water Use Efficient? Evidence from Lake Naivasha Basin, Kenya

    NASA Astrophysics Data System (ADS)

    Njiraini, Georgina W.; Guthiga, Paul M.

    2013-11-01

    With increasing water scarcity and competing uses and users, water use efficiency is becoming increasingly important in many parts of developing countries. The lake Naivasha basin has an array of different water users and uses ranging from large scale export market agriculture, urban domestic water users to small holder farmers. The small scale farmers are located in the upper catchment areas and form the bulk of the users in terms of area and population. This study used farm household data to explore the overall technical efficiency, irrigation water use efficiency and establish the factors influencing water use efficiency among small scale farmers in the Lake Naivasha basin in Kenya. Data envelopment analysis, general algebraic and modeling system, and Tobit regression methods were used in analyzing cross sectional data from a sample of 201 small scale irrigation farmers in the lake Naivasha basin. The results showed that on average, the farmers achieved only 63 % technical efficiency and 31 % water use efficiency. This revealed that substantial inefficiencies occurred in farming operations among the sampled farmers. To improve water use efficiency, the study recommends that more emphasis be put on orienting farmers toward appropriate choice of irrigation technologies, appropriate choice of crop combinations in their farms, and the attainment of desirable levels of farm fragmentation.

  10. Changes to zooplankton community structure following colonization of a small lake by Leptodora kindti

    USGS Publications Warehouse

    McNaught, A.S.; Kiesling, R.L.; Ghadouani, A.

    2004-01-01

    The predaceous cladoceran Leptodora kindti (Focke) became established in Third Sister Lake, Michigan, after individuals escaped from experimental enclosures in 1987. By 1988, the Leptodora population exhibited seasonal dynamics characteristic of natural populations. The maximum seasonal abundance of Leptodora increased to 85 individuals m-3 3 yr following the introduction. After the appearance of Leptodora, small-bodied cladocerans (Ceriodaphnia and Bosmina) virtually disappeared from the lake. There were strong seasonal shifts in the dominance patterns of both cladocerans and copepods, and Daphnia species diversity increased. Results from this unplanned introduction suggest that invertebrate predators can have a rapid and lasting effect on prey populations, even in the presence of planktivorous fish. Small-scale (<20 km) geographic barriers might be as important as large-scale barriers to dispersal of planktonic animals.

  11. English in the Estonian Multicultural Society.

    ERIC Educational Resources Information Center

    Fonzari, Lorena

    1999-01-01

    Argues that the spread of English is not closely associated to a discourse of linguistic imperialism, basing the thesis on a case study in Estonia. Surveys of three generations of Estonians indicated that all welcomed English as a means of communications and technology in the modern world, reacting against the imposition of Russian language and…

  12. The Analysis of Low Accentuation in Estonian

    ERIC Educational Resources Information Center

    Asu, Eva Liina; Nolan, Francis

    2007-01-01

    In Estonian, as in a number of other languages, the nuclear pitch accent is often low and level. This paper presents two studies of this phenomenon. The first, a phonetic analysis of carefully structured read sentences shows that low accentuation can also spread to the prenuclear accents in an intonational phrase. The resulting sentence contours…

  13. Early Vocabulary and Gestures in Estonian Children

    ERIC Educational Resources Information Center

    Schults, Astra; Tulviste, Tiia; Konstabel, Kenn

    2012-01-01

    Parents of 592 children between the age of 0 ; 8 and 1 ; 4 completed the Estonian adaptation of the MacArthur-Bates Communicative Development Inventory (ECDI Infant Form). The relationships between comprehension and production of different categories of words and gestures were examined. According to the results of regression modelling the…

  14. Distributions, Sources, and Backward Trajectories of Atmospheric Polycyclic Aromatic Hydrocarbons at Lake Small Baiyangdian, Northern China

    PubMed Central

    Qin, Ning; Kong, Xiang-Zhen; Zhu, Ying; He, Wei; He, Qi-Shuang; Yang, Bin; Ou-Yang, Hui-Ling; Liu, Wen-Xiu; Wang, Qing-Mei; Xu, Fu-Liu

    2012-01-01

    Air samples were collected seasonally at Lake Small Baiyangdian, a shallow lake in northern China, between October 2007 and September 2008. Gas phase, particulate phase and dust fall concentrations of polycyclic aromatic hydrocarbons (PAHs) were measured using a gas chromatograph-mass spectrometer (GC-MS). The distribution and partitioning of atmospheric PAHs were studied, and the major sources were identified; the backward trajectories of air masses starting from the center of Lake Small Baiyangdian were calculated for the entire year. The following results were obtained: (1) The total concentration of 16 priority controlled PAHs (PAH16) in the gas phase was 417.2 ± 299.8 ng·m−3, in the particulate phase was 150.9 ± 99.2 ng·m−3, and in dust fall was 6930.2 ± 3206.5 ng·g−1. (2) Vehicle emission, coal combustion, and biomass combustion were the major sources in the Small Baiyangdian atmosphere and accounted for 28.9%, 45.1% and 26.0% of the total PAHs, respectively. (3) Winter was dominated by relatively greater PAHs polluted northwesterly air mass pathways. Summer showed a dominant relatively clean southern pathway, whereas the trajectories in autumn and spring might be associated with high pollution from Shanxi or Henan province. PMID:23118612

  15. The influence of irrigation water on the hydrology and lake water budgets of two small arid-climate lakes in Khorezm, Uzbekistan

    NASA Astrophysics Data System (ADS)

    Scott, Julian; Rosen, Michael R.; Saito, Laurel; Decker, David L.

    2011-11-01

    SummaryLittle is known regarding the origins and hydrology of hundreds of small lakes located in the western Uzbekistan province of Khorezm, Central Asia. Situated in the Aral Sea Basin, Khorezm is a productive agricultural region, growing mainly cotton, wheat, and rice. Irrigation is provided by an extensive canal network that conveys water from the Amu Darya River (AD) throughout the province. The region receives on average 10 cm/year of precipitation, yet potential evapotranspiration exceeds this amount by about 15 times. It was hypothesized that the perennial existence of the lakes of interest depends on periodic input of excess irrigation water. This hypothesis was investigated by studying two small lakes in the region, Tuyrek and Khodjababa. In June and July 2008, surface water and shallow groundwater samples were collected at these lake systems and surrounding communities and analyzed for δ 2H, δ 18O, and major ion hydrochemistry to determine water sources. Water table and lake surface elevations were monitored, and the local aquifer characteristics were determined through aquifer tests. These data and climate data from a Class A evaporation pan and meteorological stations were used to estimate water budgets for both lakes. Lake evaporation was found to be about 0.7 cm/day during the study period. Results confirm that the waters sampled at both lake systems and throughout central Khorezm were evaporated from AD water to varying degrees. Together, the water budgets and stable isotope and major ion hydrochemistry data suggest that without surface water input from some source (i.e. excess irrigation water), these and other Khorezm lakes with similar hydrology may decrease in volume dramatically, potentially to the point of complete desiccation.

  16. The influence of irrigation water on the hydrology and lake water budgets of two small arid-climate lakes in Khorezm, Uzbekistan

    USGS Publications Warehouse

    Scott, J.; Rosen, Michael R.; Saito, L.; Decker, D.L.

    2011-01-01

    Little is known regarding the origins and hydrology of hundreds of small lakes located in the western Uzbekistan province of Khorezm, Central Asia. Situated in the Aral Sea Basin, Khorezm is a productive agricultural region, growing mainly cotton, wheat, and rice. Irrigation is provided by an extensive canal network that conveys water from the Amu Darya River (AD) throughout the province. The region receives on average 10 cm/year of precipitation, yet potential evapotranspiration exceeds this amount by about 15 times. It was hypothesized that the perennial existence of the lakes of interest depends on periodic input of excess irrigation water. This hypothesis was investigated by studying two small lakes in the region, Tuyrek and Khodjababa. In June and July 2008, surface water and shallow groundwater samples were collected at these lake systems and surrounding communities and analyzed for δ2H, δ18O, and major ion hydrochemistry to determine water sources. Water table and lake surface elevations were monitored, and the local aquifer characteristics were determined through aquifer tests. These data and climate data from a Class A evaporation pan and meteorological stations were used to estimate water budgets for both lakes. Lake evaporation was found to be about 0.7 cm/day during the study period. Results confirm that the waters sampled at both lake systems and throughout central Khorezm were evaporated from AD water to varying degrees. Together, the water budgets and stable isotope and major ion hydrochemistry data suggest that without surface water input from some source (i.e. excess irrigation water), these and other Khorezm lakes with similar hydrology may decrease in volume dramatically, potentially to the point of complete desiccation.

  17. The relationship between fish assemblages and the helminth communities of a prey fish, in a group of small shallow lakes.

    PubMed

    Fernández, Maria V; Brugni, Norma L; Viozzi, Gustavo P; Semenas, Liliana

    2010-12-01

    Galaxias maculatus (small puyen) is an abundant native fish distributed in lakes and rivers of the Patagonia, and it is the frequent prey of other fishes, fish-eating birds, and mammals. Previous studies have shown that it is parasitized by 33 metazoan species and that the richness and composition of the parasite communities vary between lakes. The aim of the present work was to analyze the relationship between the composition of fish assemblages and the helminth component community structure of G. maculatus . Ten environmentally similar, small, shallow lakes, belonging to the Nahuel Huapi Lake basin, were chosen because of the differences in the native fish assemblages. Parasite community structure in G. maculatus varied according to the fish assemblage of each lake. The presence of the piscivorous fish Percichthys trucha regularly produced variations in the composition and richness at the component and infracommunity levels, as well as the percentage of autogenic parasite species in G. maculatus . PMID:21158611

  18. Carbon dioxide and energy fluxes over a small boreal lake in Southern Finland

    NASA Astrophysics Data System (ADS)

    Mammarella, Ivan; Nordbo, Annika; Rannik, Üllar; Haapanala, Sami; Levula, Janne; Laakso, Heikki; Ojala, Anne; Peltola, Olli; Heiskanen, Jouni; Pumpanen, Jukka; Vesala, Timo

    2015-07-01

    Dynamics of carbon dioxide and energy exchange over a small boreal lake were investigated. Flux measurements have been carried out by the eddy covariance technique during two open-water periods (June-October) at Lake Kuivajärvi in Finland. Sensible heat (H) flux peaked in the early morning, and upward sensible heat flux at night results in unstable stratification over the lake. Minimum H was measured in the late afternoon, often resulting in adiabatic conditions or slightly stable stratification over the lake. The latent heat flux (LE) showed a different pattern, peaking in the afternoon and having a minimum at night. High correlation (r2 = 0.75) between H and water-air temperature difference multiplied by wind speed (U) was found, while LE strongly correlated with the water vapor pressure deficit multiplied by U (r2 = 0.78). Monthly average values of energy balance closure ranged between 70 and 99%. The lake acted as net source of carbon dioxide, and the measured flux (FCO2) averaged over the two open-water periods (0.7 µmol m-2 s-1) was up to 3 times higher than those reported in other studies. Furthermore, it was found that during period of high wind speed (>3 m s-1) shear-induced water turbulence controls the water-air gas transfer efficiency. However, under calm nighttime conditions, FCO2 was poorly correlated with the difference between the water and the equilibrium CO2 concentrations multiplied by U. Nighttime cooling of surface water enhances the gas transfer efficiency through buoyancy-driven turbulent mixing, and simple wind speed-based transfer velocity models strongly underestimate FCO2.

  19. Small mammal community succession on the beach of Dongting Lake, China after the Three Gorges Project.

    PubMed

    Zhang, Meiwen; Wang, Yong; Li, Bo; Guo, Cong; Huang, Guoxian; Shen, Guo; Zhou, Xunjun

    2014-06-01

    Although the Three Gorges Project (TGP) may have affected the population structure and distribution of plant and animal communities, few studies have analyzed the effect of this project on small mammal communities. Therefore, the present paper compares the small mammal communities inhabiting the beaches of Dongting Lake using field investigations spanning a 20-year period, both before and after the TGP was implemented. Snap traps were used throughout the census. The results indicate that the TGP caused major changes to the structure of the small mammal community at a lake downstream of the dam. First, species abundance on the beaches increased after the project commenced. The striped field mouse (Apodemus agrarius) and the Norway rat (Rattus norvegicus), which rarely inhabited the beach before the TGP, became abundant (with marked population growth) once water was impounded by the Three Gorges Reservoir. Second, dominant species concentration indices exhibited a stepwise decline, indicating that the community structure changed from a single dominant species to a more diverse species mix after TGP implementation. Third, the regulation of water discharge release by the TGP might have caused an increase in the species diversity of the animal community on the beaches. A significant difference in diversity indices was obtained before and after the TGP operation. Similarity indices also indicate a gradual increase in species numbers. Hence, a long-term project should be established to monitor the population fluctuations of the Yangtze vole (Microtus fortis), the striped field mouse and the Norway rat to safeguard against population outbreaks (similar to the Yangtze vole outbreak in 2007), which could cause crop damage to adjacent farmland, in addition to documenting the succession process of the small mammal community inhabiting the beaches of Dongting Lake. PMID:24148252

  20. Holocene lake level fluctuations of a small alpine lake in the Qilian Mountains, NW China: a comparison of chironomid, ostracod, pollen and geochemistry data.

    NASA Astrophysics Data System (ADS)

    Mischke, S.; Herzschuh, U.

    2003-04-01

    A core of 14 m length was drilled in a small alpine lake in the Qilian Mountains, NW China. The lake Luanhaizi has a drainage area of about 30 km2 and is situated at an altitude of 3200 m which represents the altitude of the present regional upper timberline. Due to the small size of the open-basin lake (surface area about 1 km2) and the sharply outlined catchment area the lake is regarded as a very sensitively and rapidly responding ecosystem. Analyses of ostracod shells, head capsules of larval chironomids and pollen and spores were conducted and the organic and carbonate content (LOI), element concentrations and magnetic susceptibility of core samples determined. Ostracod taxa mainly comprise Candona candida, C. neglecta, C. rawsoni, Cyclocypris ovum, Cypridopsis vidua, Fabaeformiscandona caudata, F. danielopoli, F. hyalina, Herpetocypris chevreuxi, Heterocypris salina, Ilyocypris cf. bradyi, I. echinata, I. lacustris and Limnocythere inopinata. They may be used to distinguish periods of low lake levels corresponding to a dense cover of aquatic plants at the lake bottom from stages of higher lake levels and a corresponding decrease in macrophytes at the core site. Chironomid taxa belonging to Chironomus, Cladopelma, Glyptotendipes, Micropsectra, Paratanytarsus, Polypedilum, Psectrocladius and Tanytarsus further provide information on variations in benthic oxygen availability and lake level fluctuations. Several units of the core show high abundances of pollen and spores of higher aquatic and wetland plants and fungi (Cyperaceae, Hippuris, Myriophyllum and Glomus) indicating low lake levels. In contrast, algae such as Botryococcus, Pediastrum and Tetraedron were regarded to reflect higher water levels. Typha angustifolia-type, Typha latifolia, Alisma and Potamogeton were recorded in low abundances as well. The organic content of core samples averages 6 % displaying four alternating stages of distinct minima and maxima. Lowest values of about 1 % occur at the core

  1. Satellite radar altimetry for monitoring small rivers and lakes in Indonesia

    NASA Astrophysics Data System (ADS)

    Sulistioadi, Y. B.; Tseng, K.-H.; Shum, C. K.; Hidayat, H.; Sumaryono, M.; Suhardiman, A.; Setiawan, F.; Sunarso, S.

    2015-01-01

    Remote sensing and satellite geodetic observations are capable of hydrologic monitoring of freshwater resources. Although satellite radar altimetry has been used in monitoring water level or discharge, its use is often limited to monitoring large rivers (>1 km) with longer interval periods (>1 week) because of its low temporal and spatial resolutions (i.e., satellite revisit period). Several studies have reported successful retrieval of water levels for small rivers as narrow as 40 m. However, processing current satellite altimetry signals for such small water bodies to retrieve water levels accurately remains challenging. Physically, the radar signal returned by water bodies smaller than the satellite footprint is most likely contaminated by non-water surfaces, which may degrade the measurement quality. In order to address this scientific challenge, we carefully selected the waveform shapes corresponding to the range measurement resulting from standard retrackers for the European Space Agency's (ESA's) Envisat (Environmental Satellite) radar altimetry. We applied this approach to small (40-200 m in width) and medium-sized (200-800 m in width) rivers and small lakes (extent <1000 km2) in the humid tropics of Southeast Asia, specifically in Indonesia. This is the first study that explored the ability of satellite altimetry to monitor small water bodies in Indonesia. The major challenges in this study include the size of the water bodies that are much smaller than the nominal extent of the Envisat satellite footprint (e.g., ~250 m compared to ~1.7 km, respectively) and slightly smaller than the along-track distance (i.e., ~370 m). We addressed this challenge by optimally using geospatial information and optical remote sensing data to define the water bodies accurately, thus minimizing the probability of non-water contamination in the altimetry measurement. Considering that satellite altimetry processing may vary with different geographical regions, meteorological

  2. Varve deposition and the sediment yield record at three small lakes of the southern Canadian Cordillera

    SciTech Connect

    Desloges, J.R. )

    1994-05-01

    Lacustrine sediments deposited in three small glacier-fed lakes of the southern Canadian Cordillera are derived primarily from subglacial erosion and delivered via short proglacial streams or by direct melting and calving of cirque glaciers. Sediment transport and deposition during early summer is controlled by runoff-generated bottom currents and in the late summer through winter by settling from suspension. This forms distinct rhythmic laminations of silt and clay in distal lake areas. Cesium-137 content in all three lakes indicates that these are varve sediments. Time series of varve thickness covering the interval 1863 to present show distinct declines in sediment yield from 310 to less than 150 t km[sup [minus]2] a[sup [minus]1]. The decline is related to sediment exhaustion following glacier retreat from Little Ice Age maxima and the opening of intervening sediment storage sites. Annual varve thickness is significantly related to fluctuations in summer or late summer temperature highlighting the importance of ice ablation, melt-water runoff, and subglacial sediment sources in controlling deposition rates. Singular climate events, such as autumn storms provide distinctive sedimentary signatures in the varve record. Reconstructed sediment yield for the Little Ice Age is as much as 100% greater than the average Holocene rate. 39 refs., 8 figs., 2 tabs.

  3. Bio-mixing due to Diel Vertical Migration of Daphnia spp. in a Small Lake

    NASA Astrophysics Data System (ADS)

    Simoncelli, Stefano; Wain, Danielle; Thackeray, Stephen

    2016-04-01

    Bio-turbulence or bio-mixing refers to the contribution of living organisms towards the mixing of waters in oceans and lakes. Experimental measurements in an unstratified tank by Wilhelmus & Dabiri (2014) show that zooplankton can trigger fluid instabilities through collective motions and that energy is imparted to scales bigger than organism's size of few mm. Length scales analysis, for low-Reynolds-number organisms in stratified water by Leshansky & Pismen (2010) and Kunze (2011), estimate eddy diffusivity up two orders of magnitude larger than the molecular thermal diffusivity. Very recently, Wand & Ardekani (2015) showed a maximum diffusivity of 10‑5 m2/s for millimetre-sized organisms from numerical simulations in the intermediate Reynolds number regime. Here we focus our attention on turbulence generated by the vertical migration of zooplankton in a small lake, mostly populated by Daphnia spp. This very common species, belonging to Cladocera order, is engaged in a vertical migration (DVM) at sunset, with many organisms crossing the thermocline despite the density stratification. During the ascension they may create hydrodynamic disturbances in the lake interior where the stratification usually suppresses the vertical diffusion. We have conducted five turbulence experiments in Vobster Quay, a small (area ˜ 59,000 m2), deep (40m) man-made basin with small wind fetch and steep sides, located in the South West UK. Turbulence was measured with a temperature microstructure profiler. To asses the zooplankton vertical concentration we used a 100 μm mesh net, by collecting and analyzing samples in 8 layers of the lake. A bottom-mounted acoustic Doppler current profiler was also employed to track their concentration and migration with the measured backscatter strength. Measured dissipation rates ɛ during the day showed low turbulence level (<= 10‑8 W/Kg) in the thermocline and in the zooplankton layer. Turbulence, during the DVM in two different days, is highest

  4. ESTONIAN GENERAL READER. URALIC AND ALTAIC SERIES, VOLUME 34.

    ERIC Educational Resources Information Center

    OINAS, FELIX J.

    DESIGNED FOR STUDENTS WHO HAVE COMPLETED "BASIC ESTONIAN" (BY THE SAME AUTHOR), THIS READER CONTAINS SELECTIONS ON A VARIETY OF TOPICS--ESTONIAN FOLKLORE, GEOGRAPHY, ECONOMICS, HISTORY, LITERATURE AND LANGUAGE, ART, MUSIC, SPORTS, PUBLIC HEALTH, AND SCIENCE. THE LANGUAGE AND STYLE OF THE ORIGINAL WORKS HAVE BEEN SOMEWHAT SIMPLIFIED, AND THE…

  5. The importance of small urbanized watersheds to pollutant loading in a large oligotrophic subalpine lake of the western USA.

    PubMed

    Rios, David T; Chandra, Sudeep; Heyvaert, Alan C

    2014-11-01

    Urban land use has been implicated as a major contributor of nonpoint source pollution in aquatic systems. Through increased nonpoint delivery of pollutants, including constituents found in stormwater, Lake Tahoe is undergoing a marked decline in its transparency, primarily due to increasing production of algae from enhanced nutrient loading and delivery of fine particles to the lake from the watershed. In response to these findings, a regional restoration effort is underway to improve basin watersheds and the water quality in Lake Tahoe. In this study, stormwater autosamplers were used to collect flow-weighted composite samples that characterized event mean concentrations for event and nonevent conditions within a small, urbanized watershed in the Tahoe basin. An event-specified constant-concentration water quality model was then applied to the event mean concentration and continuous streamflow data to estimate pollutant loads for nitrate, nitrite, ammonia, orthophosphate, and suspended sediment. These data were compared with previously reported load estimates from 10 primary monitored streams in larger watersheds of the Tahoe basin. Results from a linear regression analysis demonstrate strong and significant relationships between watershed impervious area and pollutant loadings from Lake Tahoe watersheds. These small, urbanized watersheds and intervening zones, which only comprise 10 % of the total Lake Tahoe drainage area, include a significant portion of the total Lake Tahoe impervious area. The findings of this study suggest that small, urbanized watersheds and intervening zones are disproportionately important contributors of nonpoint source pollution, including nutrients and suspended particles. PMID:25106117

  6. Relationship Between Holocene Sediment Accumulation and Lake-Volume Change in a Small Coastal Lake in Southwestern Australia

    NASA Astrophysics Data System (ADS)

    Telles, F.; Pedone, V.; George, A.

    2004-12-01

    Change in lithology in a 180-cm-long lake-center core from Lake Thetis, Western Australia serves as a proxy for change in lake volume during the Holocene. Lake Thetis is located on the coastal plain 245 km north of Perth, 1.25 km inland from the Indian Ocean. It occupies a sinkhole in middle Holocene limestone. The 300-m-diameter, steep-sided, ~2-m-deep lake has a 5-m-wide marginal terrace covered by relict and living stromatolites and a bottom covered by a thick, red-purple microbial mat. Lake elevation is not monitored, but changes noted over a 25-year period of up to 0.5 m have alternately exposed and submerged the stromatolite terrace. No hydrological study has been done to determine if the lake has a subterranean connection to the sea. Limited measurements of salinity and pH are similar to or greater than those of seawater. The laminated sediment from the core is divided into three intervals based on texture. From 0 to 45 cm, the core consists of uncompacted, red-purple, organic-rich muddy sand. Very fine-grained carbonate sand forms 50% of the sediment. This interval also contains five, lighter-colored bands, where carbonate sand forms up to 90% of the sediment. From 45 to 130 cm, the core consists of laminated red-brown, muddy, very fine sand and light-red-brown, slightly muddy medium- to fine-grained sand. The frequency of medium- to fine-grained sand layers decreases, but the layer thickness increases, upward. Carbonate grains in the thickest layers are coated with iron-oxide minerals. From 130 to 180 cm, the core consists of alternating red-brown mud, light-gray-purple mud, sandy mud, and muddy very fine sand. The carbonate sand is mostly derived from erosion of the stromatolite terrace, with minor eolian contribution from coastal-plain dunes. Therefore, the mud-dominated basal unit accumulated during a time of high lake elevation, when stromatolites were submerged and actively forming. The middle sand-dominated interval accumulated during a time of low

  7. Phytoplankton uptake and excretion of assimilated nitrate in a small Canadian shield lake.

    PubMed

    Chan, H K; Campbell, N E

    1978-06-01

    Nitrate uptake in the epilemnetic waters of a small eutrophic Canadian Shield lake was studied by using a 15N method during summer stratification. Concurrent with inhibition of primary production, 3-(3,4-dichlorophenyl)-1,1-dimethylurea inhibited NO3- assimilation. Nitrate up to 1 mg of N/liter did not affect the rate of primary production during 3 h of incubation. The NO3- fertilizer added to the lake weekly was consumed through algal assimilation in about 3 days. Excretion of the photoassimilated NO3- as dissolved organic nitrogen represented a significant portion of the nutrient incorporated by the cells. Only 40% of the NO3- -15N which disappeared could be accounted for in the particulate fraction. Although the rest was presumably excreted, only 15% of the 15N label was accounted for as cationic dissolved organic nitrogen by isotope assays. These excreted organic forms were predominantly serine and glycine in the dissolved free amino acid fraction. Bacteria as well as algae might be expected to contribute to and modify the extracellular nitrogen pool. PMID:677872

  8. [Composition characteristics and source analysis of major ions in four small lake-watersheds on the Tibetan Plateau, China].

    PubMed

    Li, He; Li, Jun; Liu, Xiao-Long; Yang, Xi; Zhang, Wei; Wang, Jie; Niu, Ying-Quan

    2015-02-01

    To investigate the ionic compositions of small lake-watersheds on the Tibetan Plateau, water samples from the brackish lakes (Pung Co (lake), Angrenjin Co and Dajia Co), the freshwater lake (Daggyaima Co), their inflowing rivers and the hot spring (Dagejia Geothermal Field), were collected during July-August 2013. The results showed that the major anions and cations of the brackish lakes were HCO3-, SO4(2-) and Na+, respectively, and the hydrochemical types were HCO3-SO4-Na and HCO3-Na. The major anions and cations of the inflowing rivers and the freshwater lake were HCO3-, SO4(2-) and Ca2+, Mg2+, respectively, and the hydrochemical types were HCO3-Ca, HCO3-Ca-Mg, HCO3-Mg-Ca, HCO3-SO4-Ca and SO4-HCO3- Ca. The major anions and cations of the hot spring were HCO3- and Na+, respectively, and the hydrochemical type was HCO3-Na. Water chemistry in the brackish lakes was primarily dominated by evaporation-crystallization processes, while the inflowing rivers and the freshwater lake were mainly influenced by carbonate weathering, and the hot spring was mainly controlled by hot water-granite interaction. Ca2+ was preferentially removed over Mg2+ from the water when carbonate minerals precipitation occured, which resulted in the high Mg2+/Ca2+ molar ratios of the brackish lakes. In the contribution of cation compositions, the largest contribution was carbonate weathering (54% - 79%), followed by silicate weathering (13% -29%) and evaperite dissolution (4% -23%), and the smallest was atmospheric input (3% - 7%). PMID:26031067

  9. Estonian greenhouse gas emissions inventory report

    SciTech Connect

    Punning, J.M.; Ilomets, M.; Karindi, A.; Mandre, M.; Reisner, V.; Martins, A.; Pesur, A.; Roostalu, H.; Tullus, H.

    1996-07-01

    It is widely accepted that the increase of greenhouse gas concentrations in the atmosphere due to human activities would result in warming of the Earth`s surface. To examine this effect and better understand how the GHG increase in the atmosphere might change the climate in the future, how ecosystems and societies in different regions of the World should adapt to these changes, what must policymakers do for the mitigation of that effect, the worldwide project within the Framework Convention on Climate Change was generated by the initiative of United Nations. Estonia is one of more than 150 countries, which signed the Framework Convention on Climate Change at the United Nations Conference on Environment and Development held in Rio de Janeiro in June 1992. In 1994 a new project, Estonian Country Study was initiated within the US Country Studies Program. The project will help to compile the GHG inventory for Estonia, find contemporary trends to investigate the impact of climate change on the Estonian ecosystems and economy and to formulate national strategies for Estonia addressing to global climate change.

  10. POTENTIAL CLIMATE WARMING EFFECTS ON ICE COVERS OF SMALL LAKES IN THE CONTIGUOUS U.S. (R824801)

    EPA Science Inventory

    Abstract

    To simulate effects of projected climate change on ice covers of small lakes in the northern contiguous U.S., a process-based simulation model is applied. This winter ice/snow cover model is associated with a deterministic, one-dimensional year-round water tem...

  11. Degradation processes of hydrological resources by human and climate - example of small lakes in Northern Kazakhstan and Southern Siberia.

    NASA Astrophysics Data System (ADS)

    Meyer, Burghard; Schreiner, Vera

    2014-05-01

    The presentation discusses (on the basis of an actual application in the development of a curriculum for Integrated Water Cycle Management in Kazakhstan; TEMPUS I-WEB project) the diverse scientific approaches to explain the degradation of hydrological resources in West-Siberia and Nord-Kazakhstan by focussing on natural and anthropogenic causes by the example of the dry out of small lakes. Since Pleistocene in the region a diverse mosaic of large and small lakes of at total shrinking surface area was formed. On natural causes it includes (1) climatic cycling, (2) lake developments since the Pleistocene originate by the Northern glaciations by ice dammed lakes (without tectonics). The man made causes are (1) the sediment accumulation in lakes, (2) the (problematic) water management and water usage and (3) the land use changes in the watersheds. Climate change includes finally both natural and climatic causes of the change. The latter is explained using actual reports of (1) IPCC on extreme events and (2) gives a note about radiative forcing components as proxy to integrate.

  12. Height Connections and Land Uplift Rates in West-Estonian Archipelago

    NASA Astrophysics Data System (ADS)

    Jürgenson, H.; Liibusk, A.; Kall, T.

    2012-04-01

    Land uplift rates are largest in the western part of Estonia. The uplift is due to post-glacial rebound. In 2001-2011, the Estonian national high-precision levelling network was completely renewed and levelled. This was the third precise levelling campaign in the re-gion. The first one had taken place before the Second World War and the second one in the 1950s. The Estonian mainland was connected with the two largest islands (Saaremaa and Hiiumaa) in the west-Estonian archipelago using the water level monitoring (hydrody-namic levelling) method. Three pairs of automatic tide gauges were installed on opposite coasts of each waterway. The tide gauges were equipped with piezoresistive pressure sen-sors. This represented the first use of such kind of equipment in Estonia. The hydrodynamic levelling series span up to two calendar years. Nevertheless, the obtained hydrodynamic levelling results need to be additionally verified using alternative geodetic methods. The obtained results were compared with the previous high-precision levelling data from the 1960s and 1970s. As well, the new Estonian gravimetric geoid model and the GPS survey were used for GPS-levelling. All the three methods were analyzed, and the preliminary results coincided within a 1-2 cm margin. Additionally, the tide gauges on the mainland and on both islands were connected using high-precision levelling. In this manner, three hydrodynamic and three digital levelling height differences formed a closed loop with the length of 250 km. The closing error of the loop was less than 1 cm. Finally, the Fennoscandian post-glacial rebound was determined from repeated levelling as well as from repeated GPS survey. The time span between the two campaigns of the first-order GPS survey was almost 13 years. According to new calculations, the relative land uplift rates within the study area reached up to +2 mm/year. This is an area with a rela-tively small amount of input data for the Nordic models. In addition, a

  13. Spatiotemporal patterns in methane flux and gas transfer velocity at low wind speeds: Implications for upscaling studies on small lakes

    NASA Astrophysics Data System (ADS)

    Schilder, J.; Bastviken, D.; Hardenbroek, M.; Heiri, O.

    2016-06-01

    Lakes contribute significantly to the global natural emissions of methane (CH4) and carbon dioxide. However, to accurately incorporate them into the continental carbon balance more detailed surveys of lacustrine greenhouse gas emissions are needed, especially in respect to spatiotemporal variability and to how this affects the upscaling of results. We investigated CH4 flux from a small, wind-shielded lake during 10 field trips over a 14 month period. We show that floating chambers may be used to calibrate the relationship between gas transfer velocity (k) and wind speed at 10 m height (U10) to the local system, in order to obtain more accurate estimates of diffusive CH4 flux than by applying general models predicting k based on U10. We confirm earlier studies indicating strong within-lake spatial variation in this relationship and in ebullitive CH4 flux within the lake basin. However, in contrast to the pattern reported in other studies, ebullitive CH4 flux was highest in the central parts of the lake. Our results indicate positive relationships between k and U10 at very low U10 (0-3 m s-1), which disagrees with earlier suggestions that this relationship may be negligible at low U10 values. We estimate annually averaged open water CH4 emission from Lake Gerzensee to be 3.6-5.8 mmol m-2 d-1. Our data suggest that estimates of greenhouse gas emissions from aquatic systems to the atmosphere based on the upscaling of short-term and small-scale measurements can be improved if both spatial and temporal variabilities of emissions are taken into account.

  14. From "Duck Factory" to "Fish Factory": Climate induced changes in vertebrate communities of prairie pothole wetlands and small lakes

    USGS Publications Warehouse

    McLean, Kyle I.; Mushet, David M.; Stockwell, Craig A.

    2016-01-01

    The Prairie Pothole Region’s myriad wetlands and small lakes contribute to its stature as the “duck factory” of North America. The fishless nature of the region’s aquatic habitats, a result of frequent drying, freezing, and high salinity, influences its importance to waterfowl. Recent precipitation increases have resulted in higher water levels and wetland/lake freshening. In 2012–13, we sampled chemical characteristics and vertebrates (fish and salamanders) of 162 Prairie Pothole wetlands and small lakes. We used non-metric multidimensional scaling, principal component analysis, and bootstrapping techniques to reveal relationships. We found fish present in a majority of sites (84 %). Fish responses to water chemistry varied by species. Fathead minnows (Pimephales promelas) and brook sticklebacks (Culaea inconstans) occurred across the broadest range of conditions. Yellow perch (Perca flavescens) occurred in a smaller, chemically defined, subset. Iowa darters (Etheostoma exile) were restricted to the narrowest range of conditions. Tiger salamanders (Ambystoma mavortium) rarely occurred in lakes with fish. We also compared our chemical data to similar data collected in 1966–1976 to explore factors contributing to the expansion of fish into previously fishless sites. Our work contributes to a better understanding of relationships between aquatic biota and climate-induced changes in this ecologically important area.

  15. A new method of quantifying discharge of small rivers into lakes and inland seas

    NASA Astrophysics Data System (ADS)

    Osadchiev, Alexander; Zavialov, Peter

    2014-05-01

    Continental discharge is an important component of the global hydrological cycle, providing the majority of the input part of the ocean water balance. Buoyant inflow usually causes surface density stratification at the large shelf areas, and plays a significant role in physical, chemical, and biological processes there that is especially important for the lakes and inland seas. Although there is a lack of discharge data for most of rivers in a global scale. Regular direct measurements of discharge are performed only for a relatively small number of rivers, generally the biggest ones or ones that flow through densely populated areas. Within this problem an indirect method of assuming a volume of river discharge was developed. The general idea of the method is the following. Firstly, the spatial surface spread of the plume generated by the considered river discharge is identified using high resolution satellite imagery of the coastal zone adjacent to the river estuary. Secondly, a series of numerical simulations of the river runoff spread is performed under various prescribed external forcing conditions which include the discharge rate. Varying forcing conditions we iteratively improve the accordance between simulated and observed river plumes therefore consequentially specifying the value of river discharge. The developed method was applied and validated against in situ date for several rivers feeding the Black Sea. Practical importance of this work consists in the fact, that the suggested method is an alternative for the expensive and laborious direct measurements of the river discharge, which are used nowadays.

  16. Invasive floating macrophytes reduce greenhouse gas emissions from a small tropical lake

    PubMed Central

    Attermeyer, K.; Flury, S.; Jayakumar, R.; Fiener, P.; Steger, K.; Arya, V.; Wilken, F.; van Geldern, R.; Premke, K.

    2016-01-01

    Floating macrophytes, including water hyacinth (Eichhornia crassipes), are dominant invasive organisms in tropical aquatic systems, and they may play an important role in modifying the gas exchange between water and the atmosphere. However, these systems are underrepresented in global datasets of greenhouse gas (GHG) emissions. This study investigated the carbon (C) turnover and GHG emissions from a small (0.6 km2) water-harvesting lake in South India and analysed the effect of floating macrophytes on these emissions. We measured carbon dioxide (CO2) and methane (CH4) emissions with gas chambers in the field as well as water C mineralization rates and physicochemical variables in both the open water and in water within stands of water hyacinths. The CO2 and CH4 emissions from areas covered by water hyacinths were reduced by 57% compared with that of open water. However, the C mineralization rates were not significantly different in the water between the two areas. We conclude that the increased invasion of water hyacinths and other floating macrophytes has the potential to change GHG emissions, a process that might be relevant in regional C budgets. PMID:26846590

  17. Invasive floating macrophytes reduce greenhouse gas emissions from a small tropical lake.

    PubMed

    Attermeyer, K; Flury, S; Jayakumar, R; Fiener, P; Steger, K; Arya, V; Wilken, F; van Geldern, R; Premke, K

    2016-01-01

    Floating macrophytes, including water hyacinth (Eichhornia crassipes), are dominant invasive organisms in tropical aquatic systems, and they may play an important role in modifying the gas exchange between water and the atmosphere. However, these systems are underrepresented in global datasets of greenhouse gas (GHG) emissions. This study investigated the carbon (C) turnover and GHG emissions from a small (0.6 km(2)) water-harvesting lake in South India and analysed the effect of floating macrophytes on these emissions. We measured carbon dioxide (CO2) and methane (CH4) emissions with gas chambers in the field as well as water C mineralization rates and physicochemical variables in both the open water and in water within stands of water hyacinths. The CO2 and CH4 emissions from areas covered by water hyacinths were reduced by 57% compared with that of open water. However, the C mineralization rates were not significantly different in the water between the two areas. We conclude that the increased invasion of water hyacinths and other floating macrophytes has the potential to change GHG emissions, a process that might be relevant in regional C budgets. PMID:26846590

  18. Population size, growth and movements of Anguilla australis in a small lake.

    PubMed

    Jellyman, D J; Crow, S K

    2016-06-01

    To study growth rates, movements and estimate population size of shortfin eels Anguilla australis in a small lake (2·5 ha) near Christchurch, New Zealand, 617 A. australis were tagged with PIT tags. Tag retention was high (95%) and over the seven recapture events spread over 2 years, 55% of tagged A. australis were recaptured. Growth of recaptured A. australis averaged 13·1 mm year(-1) and declined slightly with increasing total length. Distance moved from original capture site increased with increasing time at large. Population estimates of A. australis > 400 mm (susceptible to capture by fyke net) from recaptures of individuals averaged 1451 A. australis, with a biomass of 170 kg ha(-1) . An average of 6·6% of the estimated total population matured as male silver A. australis each year. Results from radio-tracking of four A. australis gave an average nightly foraging area of 2780 m(2) , and there was no apparent preference for inshore movement (within 5-6 m of the shoreline) or offshore movement. Fyke-net efficiency (total catch relative to the estimated total population available to each net) measured over four consecutive nights fishing was 88%. The lack of precision of the shoreline triangulation system used, ±10 m, meant that the positional data were considered too coarse to be used in a proposed novel population estimation technique based on determining population size within foraging areas. PMID:27126719

  19. Remote analysis of changes in the number of small thermokarst lakes and their distribution with respect to their sizes in the cryolithozone of Western Siberia, 2015

    NASA Astrophysics Data System (ADS)

    Polishchuk, Y. M.; Bryksina, N. A.; Polishchuk, V. Y.

    2015-12-01

    Regularities of changes in the number of thermokarst lakes in the cryolithozone of Western Siberia have been studied using multitemporal satellite images. The studies were conducted on 33 test sites selected in different landscape zones of the study area with the use of 134 cloud-free Landsat images obtained during warm months in the period from 1973 to 2013. It is shown that the total number of new lakes is significantly (almost 20 times) higher than the number of disappeared lakes. The area of newly formed thermokarst lakes is, on average, 22 times smaller than the size of disappearing lakes. Therefore, one can assume that the rapid growth in the number of small thermokarst lakes that is observed under the conditions of global warming will lead to an increase in methane emissions into the atmosphere in permafrost zones in the Arctic territories. Results of remote sensing of statistical distribution of small thermokarst lakes with respect to their sizes are given. The studies were performed on eight test sites selected in different permafrost zones of Western Siberia. The size of small lakes was determined according to QuickBird super-high resolution satellite images. It is shown that histograms of distribution of lakes with respect to their sizes allow their approximation by power and exponential functions, which can be used for modeling and predicting the dynamics of thermokarst methane emission in permafrost zones.

  20. Spatially explicit exposure assessment for small streams in catchments of the orchard growing region `Lake Constance

    NASA Astrophysics Data System (ADS)

    Golla, B.; Bach, M.; Krumpe, J.

    2009-04-01

    1. Introduction Small streams differ greatly from the standardised water body used in the context of aquatic risk assessment for the regulation of plant protection products in Germany. The standard water body is static, with a depth of 0.3 m and a width of 1.0 m. No dilution or water replacement takes place. Spray drift happens always in direction to the water body. There is no variability in drift deposition rate (90th percentile spray drift deposition values [2]). There is no spray drift filtering by vegetation. The application takes place directly adjacent to the water body. In order to establish a more realistic risk assessment procedure the Federal Office for Consumer Protection and Food Safety (BVL) and the Federal Environment Agency (UBA) aggreed to replace deterministic assumptions with data distributions and spatially explicit data and introduce probabilistic methods [3, 4, 5]. To consider the spatial and temporal variability in the exposure situations of small streams the hydraulic and morphological characteristics of catchments need to be described as well as the spatial distribution of fields treated with pesticides. As small streams are the dominant type of water body in most German orchard regions, we use the growing region Lake Constance as pilot region. 2. Materials and methods During field surveys we derive basic morphological parameters for small streams in the Lake Constance region. The mean water width/depth ratio is 13 with a mean depth of 0.12 m. The average residence time is 5.6 s/m (n=87) [1]. Orchards are mostly located in the upper parts of the catchments. Based on an authoritative dataset on rivers and streams of Germany (ATKIS DLM25) we constructed a directed network topology for the Lake Constance region. The gradient of the riverbed is calculated for river stretches of > 500 m length. The network for the pilot region consists of 2000 km rivers and streams. 500 km stream length are located within a distance of 150 m to orchards. Within

  1. Quantified sensitivity of small lake sediments to record historic earthquakes: Implications for paleoseismology

    NASA Astrophysics Data System (ADS)

    Wilhelm, Bruno; Nomade, Jerome; Crouzet, Christian; Litty, Camille; Sabatier, Pierre; Belle, Simon; Rolland, Yann; Revel, Marie; Courboulex, Françoise; Arnaud, Fabien; Anselmetti, Flavio S.

    2016-01-01

    Seismic hazard assessment is a critical but challenging issue for modern societies. A key parameter to be estimated is the recurrence interval of damaging earthquakes. This requires the establishment of earthquake records long enough to be relevant, i.e., far longer than historical observations. We study how lake sediments can be used for this purpose and explore conditions that enable lake sediments to record earthquakes. This was achieved (i) through the compilation of eight lake-sediment sequences from the European Alps to reconstruct chronicles of mass movement deposits and (ii) through the comparison of these chronicles with the well-documented earthquake history. This allowed 24 occurrences of mass movements to be identified, of which 21 were most probably triggered by an earthquake. However, the number of earthquake-induced deposits varies between lakes of a same region, suggesting variable thresholds of the lake sequences to record earthquake shaking. These thresholds have been quantified by linking the mass movement occurrences in a single lake to both intensity and distance of the triggering earthquakes. This method offers a quantitative approach to estimate locations and intensities of past earthquake epicenters. Finally, we explored which lake characteristics could explain the various sensitivities. Our results suggest that sedimentation rate should be larger than 0.5 mm yr-1 so that a given lake records earthquakes in moderately active seismotectonic regions. We also postulate that an increasing sedimentation rate may imply an increasing sensitivity to earthquake shaking. Hence, further paleoseismological studies should control carefully that no significant change in sedimentation rates occurs within a record, which could falsify the assessment of earthquake recurrence intervals.

  2. Effects of acidification on metal accumulation by aquatic plants and invertebrates. 2. Wetlands, ponds and small lakes

    USGS Publications Warehouse

    Albers, P.H.; Camardese, M.B.

    1993-01-01

    High concentrations of trace metals in the water of low-pH lakes and streams could result in elevated amounts of metals within or adsorbed to aquatic plants and, possibly, invertebrates. Concentrations of Al, Cd, Ca, Cu, Fe, Pb, Mg, Mn, Hg, Ni, P, and Zn were compared in water, plants, and aquatic invertebrates of wetlands, ponds, and small lakes in Maryland and Maine. The accumulation of metals by aquatic plants and insects and the concentrations of metals in water were not greatly affected by pH. None of the metal concentrations significantly correlated with metals in insects. Plant metal concentrations poorly correlated with metal concentrations in water. Concentrations of metals exceeded acceptable dietary levels more frequently in plants than in invertebrates. Concerns about metal toxicity in birds that feed on invertebrates and plants from acidified waters seem to be unwarranted. Positive correlations among pH, Ca in water, Ca in insects, and Ca in plants imply that acidification can reduce the Ca content of aquatic biota. Aquatic insects were low in Ca, but crayfishes and snails, which are adversely affected by low pH, were very high. A concern for waterfowl is Ca deprivation from decreased Ca availability in low-pH wetlands, ponds, and small lakes.

  3. The Holocene environmental history of a small coastal lake on the north-eastern Kamchatka Peninsula

    NASA Astrophysics Data System (ADS)

    Solovieva, N.; Klimaschewski, A.; Self, A. E.; Jones, V. J.; Andrén, E.; Andreev, A. A.; Hammarlund., D.; Lepskaya, E. V.; Nazarova, L.

    2015-11-01

    A radiocarbon and tephra-dated sediment core from Lifebuoy Lake, located on the north-east coast of Kamchatka Peninsula, was analysed for pollen, spores, diatoms, chironomids and tephra in order to uncover regional environmental history. The 6500-year environmental history of Lifebuoy Lake correlates with the broad regional patterns of vegetation development and climate dynamics with both diatoms and chironomids showing near-synchronous changes. Between ca. 6300 and 3900 cal yr BP, the lake ecosystem was naturally enriched, with several Stephanodiscus species dominating the diatom plankton. This natural eutrophication state is likely to be due to a combination of the base-rich catchment geology, the fertilisation effect of several fires in the catchment, silica input from tephra layers and, possibly, nitrogen input from seabirds. The substantial tephra deposit at about 3850 cal yr BP might have stopped sedimentary phosphorus from entering the lake water thus decreasing the trophic state of the lake and facilitating the shift in diatom composition to a benthic Fragiliariaceae complex. Both diatoms and chironomids showed simultaneous compositional changes, which are also reflected by statistically significant changes in their rates of change 300-400 years after the arrival of Pinus pumila in the lake catchment. The rapid increase in both total diatom concentration and the percentage abundance of the large heavy species, Aulacoseira subarctica might be a response to the change in timing and intensity of lake spring turn-over due to the changes in the patterns of North Pacific atmospheric circulation, most notably westward shift of the Aleutian Low. The two highest peaks in A. subarctica abundance at Lifebouy Lake occurred during opposite summer temperature inferences: the earlier peak (3500-2900 cal yr BP) coincided with warm summers and the latter peak (300 cal yr BP-present) occurred during the cold summer period. These imply that A. subarctica shows no direct

  4. Upwelling of deep water during thermal stratification onset—A major mechanism of vertical transport in small temperate lakes in spring?

    NASA Astrophysics Data System (ADS)

    Pöschke, Franziska; Lewandowski, Jörg; Engelhardt, Christof; Preuß, Konrad; Oczipka, Martin; Ruhtz, Thomas; Kirillin, Georgiy

    2015-12-01

    Using airborne thermal infrared imaging and horizontally resolved in situ temperature monitoring at the lake surface, we estimated strength and duration of regular wind-driven upwelling of dense deep water to the lake surface in two small (in terms of Rossby radius) temperate lakes during the initial phase of summer thermal stratification. The onset and duration of the upwelling events correlated well with the balance between stratification (in terms of Schmidt stability) and wind forcing, as expressed by Lake and Wedderburn numbers. The period of regular upwelling appearances lasted 7-15 days, identified by Schmidt stabilities around 30 J m-2 and Lake numbers between 0 and 1, and resulted in persistent temperature gradients of up to 2°C across the lake surface. Our results suggest that spring upwelling should inevitably take place in all freshwater temperate lakes with mean temperatures crossing the maximum density value of freshwater on annual cycle, whereas duration and intensity of the upwelling would vary depending on lake morphometry and weather conditions. Our results suggest major contribution of upwelling in nutrient supply to the upper waters, oxygenation of the deep water column, and air-lake gas exchange, in particular, the release of the sediment-produced methane into the atmosphere.

  5. The Tturbulent Structure of the Atmospheric Boundary Layer over Small Northern Lakes

    NASA Astrophysics Data System (ADS)

    Repina, I.; Stepanenko, V.; Artamonov, A.; Barskov, K.; Polukhov, A.

    2015-12-01

    Wetland and freshwater ecosystems of the Northern Europe are an important natural source of atmospheric methane. Adequate calculation of gas emission from the northern territories requires calculation of balances of heat, moisture, and gases at the surface of water bodies on the sub-grid scale in the climate models. We carried out measurements in North Karelia on the lake Verkhneye (White Sea Biological Station of Moscow State University). The purpose of the study is evaluation of turbulent transport in the system "lake water- near-surface air - surrounding forest" in the winter season. We used an array of acoustic anemometers mounted at different distances from the lake shore. Measurements were taken at two heights in the center of the lake. It was revealed that the intensity of the turbulent transfer essentially depends on the height and location of sensors, and the wind direction. Stratification in the near-to-surface air probably does not play significant role. Besides, there is no constant-flux layer. The later makes Monin and Obukhov similarity theory (which is used in most of the parameterizations for calculating turbulent flows) inapplicable in this case. The work was sponsored by RFBR 14-05-91752, 14-05-91764, 15-35-20958.

  6. Business Use of Small Computers in the Salt Lake City, Utah Area.

    ERIC Educational Resources Information Center

    Homer, Michael M.

    In July 1981, Utah Technical College (UTC) conducted a survey of businesses in the Salt Lake City area to gather information for the development of a curriculum integrating computer applications with business course instruction. The survey sought to determine the status and usage of current micro/mini computer equipment, future data processing…

  7. Evaporation from a small prairie wetland in the Cottonwood Lake Area, North Dakota - An energy-budget study

    USGS Publications Warehouse

    Parkhurst, R.S.; Winter, T.C.; Rosenberry, D.O.; Sturrock, A.M.

    1998-01-01

    Evaporation from Wetland Pl in the Cottonwood Lake area of North Dakota, USA was determined by the energy-budget method for 1982-85 and 1987. Evaporation rates were as high as 0.672 cm day-1. Incoming solar radiation, incoming atmospheric radiation, and long-wave radiation emitted from the water body are the largest energy fluxes to and from the wetland. Because of the small heat storage of the water body, evaporation rates closely track solar radiation on short time scales. The effect of advected energy related to precipitation is small because the water quickly heats up by solar radiation following precipitation. Advected energy related to ground water is minimal because ground-water fluxes are small and groundwater temperature is only about 7 ??C. Energy flux related to sediment heating and thermal storage in the sediments, which might be expected to be large because the water is clear and shallow, affects evaporation rates by less than 5 percent.

  8. Equations for estimating synthetic unit-hydrograph parameter values for small watersheds in Lake County, Illinois

    USGS Publications Warehouse

    Melching, C.S.; Marquardt, J.S.

    1997-01-01

    Design hydrographs computed from design storms, simple models of abstractions (interception, depression storage, and infiltration), and synthetic unit hydrographs provide vital information for stormwater, flood-plain, and water-resources management throughout the United States. Rainfall and runoff data for small watersheds in Lake County collected between 1990 and 1995 were studied to develop equations for estimation of synthetic unit-hydrograph parameters on the basis of watershed and storm characteristics. The synthetic unit-hydrograph parameters of interest were the time of concentration (TC) and watershed-storage coefficient (R) for the Clark unit-hydrograph method, the unit-graph lag (UL) for the Soil Conservation Service (now known as the Natural Resources Conservation Service) dimensionless unit hydrograph, and the hydrograph-time lag (TL) for the linear-reservoir method for unit-hydrograph estimation. Data from 66 storms with effective-precipitation depths greater than 0.4 inches on 9 small watersheds (areas between 0.06 and 37 square miles (mi2)) were utilized to develop the estimation equations, and data from 11 storms on 8 of these watersheds were utilized to verify (test) the estimation equations. The synthetic unit-hydrograph parameters were determined by calibration using the U.S. Army Corps of Engineers Flood Hydrograph Package HEC-1 (TC, R, and UL) or by manual analysis of the rainfall and run-off data (TL). The relation between synthetic unit-hydrograph parameters, and watershed and storm characteristics was determined by multiple linear regression of the logarithms of the parameters and characteristics. Separate sets of equations were developed with watershed area and main channel length as the starting parameters. Percentage of impervious cover, main channel slope, and depth of effective precipitation also were identified as important characteristics for estimation of synthetic unit-hydrograph parameters. The estimation equations utilizing area

  9. Two-dimensional small-scale variability of pore water phosphate in freshwater lakes: results from a novel dialysis sampler.

    PubMed

    Lewandowski, Jorg; Rüter, Kristina; Hupfer, Michael

    2002-05-01

    Vertical concentration profiles of soluble reactive phosphorus (SRP) in the upper sedimentary zone of freshwater lakes are an important means for studying internal phosphorus (P) loading and to gain insight into early diagenetic processes. The interpretation of such pore water profiles generally neglects the occurrence of horizontal variability at a specific sampling site. To further examine this variability, we have designed a novel two-dimensional sampler (2D peeper) consisting of 2280 chambers at a spatial resolution of 9 mm providing a sampling area of 43 x 44 cm. This new device was deployed in three eutrophic lakes in north-eastern Germany. The resulting 2D images of the SRP concentrations, diffusive fluxes, and turnover rates revealed systematic vertical and horizontal structures with local niches of increased phosphorus release. Thus, the extrapolation of P flux calculations based on one-dimensional pore water profiles may lead to a considerable error. The observed small-scale horizontal heterogeneity, probably mainly caused by organisms, was larger in the biologically more active Lake Müllrose and Süsser See than in the deeper Arendsee where meio- and macrozoobenthos were missing. In all cases, the variability was highest at the sediment-water interface and diminished with sediment depth. PMID:12026990

  10. Strong evidence for terrestrial support of zooplankton in small lakes based on stable isotopes of carbon, nitrogen, and hydrogen

    PubMed Central

    Cole, Jonathan J.; Carpenter, Stephen R.; Kitchell, Jim; Pace, Michael L.; Solomon, Christopher T.; Weidel, Brian

    2011-01-01

    Cross-ecosystem subsidies to food webs can alter metabolic balances in the receiving (subsidized) system and free the food web, or particular consumers, from the energetic constraints of local primary production. Although cross-ecosystem subsidies between terrestrial and aquatic systems have been well recognized for benthic organisms in streams, rivers, and the littoral zones of lakes, terrestrial subsidies to pelagic consumers are more difficult to demonstrate and remain controversial. Here, we adopt a unique approach by using stable isotopes of H, C, and N to estimate terrestrial support to zooplankton in two contrasting lakes. Zooplankton (Holopedium, Daphnia, and Leptodiaptomus) are comprised of ≈20–40% of organic material of terrestrial origin. These estimates are as high as, or higher than, prior measures obtained by experimentally manipulating the inorganic 13C content of these lakes to augment the small, natural contrast in 13C between terrestrial and algal photosynthesis. Our study gives credence to a growing literature, which we review here, suggesting that significant terrestrial support of pelagic crustaceans (zooplankton) is widespread. PMID:21245299

  11. Gas exchange dependency on diffusion coefficient: direct /sup 222/Rn and /sup 3/He comparisons in a small lake

    SciTech Connect

    Torgersen, T.; Mathieu, G.; Hesslein, R.H.; Broecker, W.S.

    1982-01-20

    A direct field comparison was conducted to determine the dependency of gas exchange coefficient (k/sub x/) on the diffusion coefficient (D/sub x/). The study also sought to confirm the enhanced vertical exchange properties of limnocorrals and similar enclosures. Gas exchange coefficients for /sup 222/Rn and /sup 3/He were determined in a small northern Ontario lake, using a /sup 226/Ra and /sup 3/H spike to gain the necessary precision. The results indicate that the gas exchange coefficient is functionally dependent on the diffusion coefficient raised to the 1.22/sub -35//sup + > 12/ power (k/sub x/ = f(D/sub x//sup 1.22)), clearly supporting the stagnant film model of gas exchange. Limnocorrals were found to have gas exchange rates up to 1.7 times higher than the whole lake in spite of the observation of more calm surface conditions in the corral than in the open lake. 33 references, 6 figures, 8 tables.

  12. Strong evidence for terrestrial support of zooplankton in small lakes based on stable isotopes of carbon, nitrogen, and hydrogen

    USGS Publications Warehouse

    Cole, J.J.; Carpenter, S.R.; Kitchell, J.; Pace, M.L.; Solomon, C.T.; Weidel, B.

    2011-01-01

    Cross-ecosystem subsidies to food webs can alter metabolic balances in the receiving (subsidized) system and free the food web, or particular consumers, from the energetic constraints of local primary production. Although cross-ecosystem subsidies between terrestrial and aquatic systems have been well recognized for benthic organisms in streams, rivers, and the littoral zones of lakes, terrestrial subsidies to pelagic consumers are more difficult to demonstrate and remain controversial. Here, we adopt a unique approach by using stable isotopes of H, C, and N to estimate terrestrial support to zooplankton in two contrasting lakes. Zooplankton (Holopedium, Daphnia, and Leptodiaptomus) are comprised of ???20-40% of organic material of terrestrial origin. These estimates are as high as, or higher than, prior measures obtained by experimentally manipulating the inorganic 13C content of these lakes to augment the small, natural contrast in 13C between terrestrial and algal photosynthesis. Our study gives credence to a growing literature, which we review here, suggesting that significant terrestrial support of pelagic crustaceans (zooplankton) is widespread.

  13. Organizational Commitment in Estonian University Libraries: A Review and Survey

    ERIC Educational Resources Information Center

    Kont, Kate-Riin; Jantson, Signe

    2014-01-01

    The data used in this article is based on the reviewing of relevant literature to provide an overview of the concepts of organizational commitment, job security, and interpersonal relations, as well as on the results of the original online survey, conducted by the article's authors, held in 2012 in Estonian university libraries governed by public…

  14. Whole mitochondrial genome genetic diversity in an Estonian population sample.

    PubMed

    Stoljarova, Monika; King, Jonathan L; Takahashi, Maiko; Aaspõllu, Anu; Budowle, Bruce

    2016-01-01

    Mitochondrial DNA is a useful marker for population studies, human identification, and forensic analysis. Commonly used hypervariable regions I and II (HVI/HVII) were reported to contain as little as 25% of mitochondrial DNA variants and therefore the majority of power of discrimination of mitochondrial DNA resides in the coding region. Massively parallel sequencing technology enables entire mitochondrial genome sequencing. In this study, buccal swabs were collected from 114 unrelated Estonians and whole mitochondrial genome sequences were generated using the Illumina MiSeq system. The results are concordant with previous mtDNA control region reports of high haplogroup HV and U frequencies (47.4 and 23.7% in this study, respectively) in the Estonian population. One sample with the Northern Asian haplogroup D was detected. The genetic diversity of the Estonian population sample was estimated to be 99.67 and 95.85%, for mtGenome and HVI/HVII data, respectively. The random match probability for mtGenome data was 1.20 versus 4.99% for HVI/HVII. The nucleotide mean pairwise difference was 27 ± 11 for mtGenome and 7 ± 3 for HVI/HVII data. These data describe the genetic diversity of the Estonian population sample and emphasize the power of discrimination of the entire mitochondrial genome over the hypervariable regions. PMID:26289416

  15. Physical processes and landforms on beaches in short fetch environments in estuaries, small lakes and reservoirs: A review

    NASA Astrophysics Data System (ADS)

    Nordstrom, Karl F.; Jackson, Nancy L.

    2012-02-01

    This review is intended to identify differences between beaches in short-fetch environments and beaches on exposed coasts, while also distinguishing between the different subcategories of fetch-limited beaches. Subcategories are discussed largely in terms of estuaries, lakes and reservoirs. The term fetch-limited refers to basins that are small enough that distance rather than wind duration is always a limitation to wave generation. Attention is focused on basins where fetch distances are < 50 km. The dimensions of small basins provide a limit on the energy potential of the waves, causing geologic and biologic controls to be more significant and wind-induced currents, tidal currents and ice to be relatively more effective than on exposed beaches. Shoreline orientations differ greatly over short distances, causing great differences in exposure to dominant winds and isolating beach segments. Limited longshore sediment exchanges result in beach sediments that closely resemble local source materials. The absence of high-energy waves causes beaches and bar forms to be smaller, and the absence of swell waves following storms and the relatively calm conditions reduces the speed of recovery of post-storm profiles and the cyclic nature of beach response. The beaches are often fronted by flat shallow platforms that undergo little morphologic change and help dissipate waves at low water levels. The narrow beaches are poor sources of sediment for wind-blown sand and dunes are small or frequently absent. The narrow beaches and reduced wave energies allow upland vegetation and algae and seagrass to grow close to the active foreshore. This vegetation, the wrack deposited on the beach, and driftwood logs are better able to resist the low-energy waves and are more effective in resisting beach change. Erosion rates of 2-3 m yr- 1 are common in some estuaries and can be > 7 m yr- 1. Rates of up to 1.5 m yr- 1 can occur in small lakes and reservoirs. Shore parallel protection

  16. Transformation of the chemical composition of the waters of small lakes on Kola Peninsula owing to a decrease in technogenic air pollution and to climate warming

    NASA Astrophysics Data System (ADS)

    Moiseenko, T. I.; Bazova, M. M.; Efimova, L. E.

    2014-05-01

    The emission of sulfur dioxide and metals from copper-nickel melting plants on Kola Peninsula (Russia) decreased pronouncedly over the last two decades. The decrease in the sulfate content and increase in the acid-neutralizing capability of waters were proven on the basis of the data of surveys on 75 small lakes repeated once every five years from 1990 to 2010. The variations of other parameters of the chemical composition of the waters of small lakes depend on the geological and landscape conditions of the formation of waters. The alkalinity and pH values increased in 46% of the lakes; 24% of them showed a further decrease of these parameters; and no reliable changes were traced in 31% of the lakes. The concentrations of Cu and Ni in the lacustrine water decreased 5-to 10-fold over the last two decades.

  17. The relationship between the distribution of common carp and their environmental DNA in a small lake.

    PubMed

    Eichmiller, Jessica J; Bajer, Przemyslaw G; Sorensen, Peter W

    2014-01-01

    Although environmental DNA (eDNA) has been used to infer the presence of rare aquatic species, many facets of this technique remain unresolved. In particular, the relationship between eDNA and fish distribution is not known. We examined the relationship between the distribution of fish and their eDNA (detection rate and concentration) in a lake. A quantitative PCR (qPCR) assay for a region within the cytochrome b gene of the common carp (Cyprinus carpio or 'carp'), an ubiquitous invasive fish, was developed and used to measure eDNA in Lake Staring (MN, USA), in which both the density of carp and their distribution have been closely monitored for several years. Surface water, sub-surface water, and sediment were sampled from 22 locations in the lake, including areas frequently used by carp. In water, areas of high carp use had a higher rate of detection and concentration of eDNA, but there was no effect of fish use on sediment eDNA. The detection rate and concentration of eDNA in surface and sub-surface water were not significantly different (p≥0.5), indicating that eDNA did not accumulate in surface water. The detection rate followed the trend: high-use water > low-use water > sediment. The concentration of eDNA in sediment samples that were above the limit of detection were several orders of magnitude greater than water on a per mass basis, but a poor limit of detection led to low detection rates. The patchy distribution of eDNA in the water of our study lake suggests that the mechanisms that remove eDNA from the water column, such as decay and sedimentation, are rapid. Taken together, these results indicate that effective eDNA sampling methods should be informed by fish distribution, as eDNA concentration was shown to vary dramatically between samples taken less than 100 m apart. PMID:25383965

  18. Effects of acidification of metal accumulation by aquatic plants and invertebrates. 2. Wetlands, ponds and small lakes

    SciTech Connect

    Albers, P.H.; Camardese, M.B. . Patuxent Wildlife Research Center)

    1993-06-01

    Compared were concentrations of Al,Cd,Ca,Cu,Fe,Pb,Mg,Mn,Hg,Ni,P, and Zn in water, plants, and aquatic invertebrates of wetlands, ponds, and small lakes in Maryland and Maine. The accumulation of metals by aquatic plants and insects and the concentration of metals in water were not greatly affected by pH. None of the metal concentrations in water significantly correlated with metals in insects. Plant metal concentrations poorly correlated with metal concentrations in water. Concentrations of metals exceeded acceptable dietary levels more frequently in plants than in invertebrates. Concerns about metal toxicity in birds that feed on invertebrates and plants from acidified waters seems to be unwarranted. Positive correlations among pH, Ca in water, Ca in insects, and Ca in plants imply that acidification can reduce the Ca content of aquatic biota. Aquatic insects were low in Ca, but crayfishes and snails, which are adversely affected by low pH, were very high. A concern for waterfowl is Ca deprivation from decreased Ca availability in low-pH wetlands, ponds, and small lakes..

  19. Factors Predicting Suicide among Russians in Estonia in Comparison with Estonians: A Case-Control Study

    PubMed Central

    Kõlves, Kairi; Sisask, Merike; Anion, Liivia; Samm, Algi; Värnik, Airi

    2006-01-01

    Aim To explore differences between suicide victims among Russian immigrants in Estonia and native Estonians, according to socio-demographic background, substance use pattern, and recent life events to find out immigration-specific factors predicting suicide. Methods The psychological autopsy study included 427 people who committed suicide in 1999 and 427 randomly selected controls matched by region, gender, age, and nationality. Results The only variable that differed significantly between Russian and Estonian suicide cases was substance use pattern. Logistic regression models showed that factors associated with suicide for both nationalities were substance dependence and abuse (Russians: odds ratio [OR], 12.9; 95% confidence interval [95% CI], 4.2-39.2; Estonians: OR, 8.1; 95% CI, 3.9-16.4), economical inactivity Russians: OR 5.5; 95% CI, 1.3-22.9; Estonians: OR, 3.1; 95% CI, 1.3-7.1), and recent family discord (Russians: OR, 3.2; 95% CI, 1.1-9.9; Estonians: OR, 4.5; 95%, CI, 2.1-9.8). The variables that remained significant in the final model were having no partner (Estonians: OR, 3.0; 95% CI, 1.6-5.5), being unemployed (Estonians: OR, 5.5; 95% CI, 2.0-15.4), and being an abstainer (Estonians: OR, 6.7; 95% CI, 2.5-17.6) for Estonians, and somatic illness (Russians: OR, 4.1; 95% CI, 1.4-11.7), separation (Russians: OR, 32.3; 95% CI, 2.9-364.1), and death of a close person (Russians: OR, 0.2; 95% CI, 0.04-0.7) for Russians. Conclusion Although the predicting factors of suicide were similar among the Estonian Russians and Estonians, there were still some differences in the nature of recent life events. Higher suicide rate among Estonian Russians in 1999 could be at least partly attributable to their higher substance consumption. PMID:17171808

  20. The Relationship between the Distribution of Common Carp and Their Environmental DNA in a Small Lake

    PubMed Central

    Eichmiller, Jessica J.; Bajer, Przemyslaw G.; Sorensen, Peter W.

    2014-01-01

    Although environmental DNA (eDNA) has been used to infer the presence of rare aquatic species, many facets of this technique remain unresolved. In particular, the relationship between eDNA and fish distribution is not known. We examined the relationship between the distribution of fish and their eDNA (detection rate and concentration) in a lake. A quantitative PCR (qPCR) assay for a region within the cytochrome b gene of the common carp (Cyprinus carpio or ‘carp’), an ubiquitous invasive fish, was developed and used to measure eDNA in Lake Staring (MN, USA), in which both the density of carp and their distribution have been closely monitored for several years. Surface water, sub-surface water, and sediment were sampled from 22 locations in the lake, including areas frequently used by carp. In water, areas of high carp use had a higher rate of detection and concentration of eDNA, but there was no effect of fish use on sediment eDNA. The detection rate and concentration of eDNA in surface and sub-surface water were not significantly different (p≥0.5), indicating that eDNA did not accumulate in surface water. The detection rate followed the trend: high-use water > low-use water > sediment. The concentration of eDNA in sediment samples that were above the limit of detection were several orders of magnitude greater than water on a per mass basis, but a poor limit of detection led to low detection rates. The patchy distribution of eDNA in the water of our study lake suggests that the mechanisms that remove eDNA from the water column, such as decay and sedimentation, are rapid. Taken together, these results indicate that effective eDNA sampling methods should be informed by fish distribution, as eDNA concentration was shown to vary dramatically between samples taken less than 100 m apart. PMID:25383965

  1. A Multi-Parameter Approach to Assessing the Origin of Sediment-Magnetic Signatures in Small, Temperate-Climate Lakes

    NASA Astrophysics Data System (ADS)

    Lascu, I.; Plank, C.; Banerjee, S. K.; Ito, E.

    2008-12-01

    To assess the controls on sedimentary magnetic signatures in lakes, we analyzed the characteristics of core, surface, sediment trap, and catchment samples collected from small, temperate-climate lakes, which are commonly used in paleoenvironmental reconstructions. Magnetic properties of sediments were evaluated using room temperature measurements (susceptibility, IRM, ARM), hysteresis parameters, low temperature magnetization curves, and modeling of bulk coercivity spectra, obtained from IRM and ARM acquisition and demagnetization curves. The results highlight several characteristics of lacustrine sediments: 1) Magnetic- mineral assemblages are dominated by low-coercivity minerals (e.g. magnetite); 2) Saturation magnetization, rather than remanent magnetization, is a better overall indicator of concentration, due to differences in grain size; 3) Shoreline samples contain almost exclusively detrital multi-domain (MD) magnetite grains, while littoral and profundal sediments contain a mixture of MD and in-lake produced single-domain (SD) grains; 4) Profundal sediments, deposited in seasonally-anoxic waters, exhibit dissolution of finer-grained particles; 5) Calculated contributions of a biogenic source differ depending on method utilized. ARM/IRM ratios and delta/delta ratios are more conservative in this aspect, indicating a maximum of 50% contribution of biogenic magnetite. Hysteresis and coercivity analyses yield up to 75% contribution of biogenic particles; 6) There is a direct linear relation between percent mass organic matter (OM) and ARM/IRM, showing a dependence of magnetic grain size on organic carbon concentration. This correlation highlights the role OM has in the process of production and preservation of magnetosomes. Organic matter decomposition depletes the dissolved oxygen and leads to temporary or permanent anoxic conditions in the sediment. If conditions are suboxic (e.g. in the littoral zone, where oxygen can diffuse into the sediment from the

  2. Whole-genome sequencing reveals small genomic regions of introgression in an introduced crater lake population of threespine stickleback.

    PubMed

    Yoshida, Kohta; Miyagi, Ryutaro; Mori, Seiichi; Takahashi, Aya; Makino, Takashi; Toyoda, Atsushi; Fujiyama, Asao; Kitano, Jun

    2016-04-01

    Invasive species pose a major threat to biological diversity. Although introduced populations often experience population bottlenecks, some invasive species are thought to be originated from hybridization between multiple populations or species, which can contribute to the maintenance of high genetic diversity. Recent advances in genome sequencing enable us to trace the evolutionary history of invasive species even at whole-genome level and may help to identify the history of past hybridization that may be overlooked by traditional marker-based analysis. Here, we conducted whole-genome sequencing of eight threespine stickleback (Gasterosteus aculeatus) individuals, four from a recently introduced crater lake population and four of the putative source population. We found that both populations have several small genomic regions with high genetic diversity, which resulted from introgression from a closely related species (Gasterosteus nipponicus). The sizes of the regions were too small to be detected with traditional marker-based analysis or even some reduced-representation sequencing methods. Further amplicon sequencing revealed linkage disequilibrium around an introgression site, which suggests the possibility of selective sweep at the introgression site. Thus, interspecies introgression might predate introduction and increase genetic variation in the source population. Whole-genome sequencing of even a small number of individuals can therefore provide higher resolution inference of history of introduced populations. PMID:27069575

  3. Identification of temporal and small-scale spatial variations of phosphate concentration in the near-shore groundwater of an oligotrophic lake

    NASA Astrophysics Data System (ADS)

    Pöschke, Franziska; Schlichting, Hendrik; Lewandowski, Jörg

    2016-04-01

    Lake Stechlin is one of the last oligotrophic lakes in the German North-Eastern Lake District. In recent years there was some worry over a small but continuous increase of phosphate concentrations in the open water body. The reasons remain unclear. Since the lake obtains its water only from groundwater and precipitation there is the assumption that the former can be a significant source of phosphate inputs into the lake. In the present study, three different groundwater sampling settings on different scales in time and space were used to investigate the phosphate concentration in the near-shore groundwater. A multi-level sampling grid of twelve samplers and 60 sampling ports was installed to study the temporal small-scale fluctuations of P concentration in the groundwater and the interstitial water. Furthermore, a one-time sampling campaign of shallow near-shore groundwater was conducted every 500 m along the lake shore. Additionally, nests of permanent groundwater wells were sampled monthly for one year to identify concentration patterns in the deeper aquifer. The results indicate a large spatial and small temporal heterogeneity of P concentrations. The range of P concentration is < 0.01 mg/l up to 0.2 mg/l. There was no significant increase of P concentrations downstream of the small near-shore village Neuglobsow. Since the groundwater catchment belongs since 1938 to a natural protected area other anthropogenic impacts are quite unlikely. Hence, the main source for phosphate is probably the decomposition of naturally present organic material under anaerobic and warm conditions.

  4. Small-scale variability of chlorophyll, CDOM, and suspended matter in the Lake Balaton as obtained by shipborne UV fluorescent lidar

    NASA Astrophysics Data System (ADS)

    Pelevin, Vadim; Palmer, Stephanie; Khymchenko, Lisa

    2015-04-01

    Despite a long history in oceanography, few attempts have been made to use fluorescent lidars to evaluate water quality in lakes. We report lidar measurements taken on the Lake Balaton over the period of five days in August, 2012. Lake Balaton, the largest lake in Central Europe in area (597 km2), is very shallow (average depth of 3.5m). The lake is mesotrophic exhibiting a strong trophic gradient from SW to NE. The UV fluorescent lidar UFL-9 used in this study was developed at the Shirshov Institute of Oceanology. It can be used for CDOM, organic pollutants, chlorophyll, and suspended matter concentrations measurements at very high spatial resolution (up to ~1 m). The data were collected continuously during daytime while the boat was travelling. The entire area of the lake was covered by the measurement. The lidar data were calibrated against those obtained in situ through water sampling and then converted from the optical units into the mass concentrations of the above mentioned constituents. Based on this data set, we mapped and investigated in detail the small-scale spatial variability of CDOM, chlorophyll-a, and suspended matter concentrations. In particular, the characteristics of patchiness for the selected parameters were quantified and inter-compared, and their relations with the background forcing conditions were analyzed. We also discuss the applicability of lidar techniques for assessing the hydrological and ecological conditions in shallow inland water bodies. The study was partly supported by the Russian Science Foundation, Grant 14-50-00095.

  5. Population Density of the Crayfish, Orconectes limosus, in Relation to Fish and Macroinvertebrate Densities in a Small Mesotrophic Lake - Implications for the Lake's Food Web

    NASA Astrophysics Data System (ADS)

    Haertel-Borer, Susanne S.; Zak, Dominik; Eckmann, Reiner; Baade, Ulrich; Hölker, Franz

    2005-12-01

    The population density of Orconectes limosus in a mesotrophic lake was assessed in the context of fish and macroinvertebrate biomasses, and crayfish consumption by fish. The average O. limosus (6 cm total length) abundance and biomass in the littoral zone was 2200 ind ha-1 and 32.2 kg ha1, respectively. O. limosus biomass accounted for a large percentage (49%) of the lake's macroinvertebrate biomass. O. limosus was equal to 35% of the non-predatory fish biomass and to 81% of the predatory fish biomass. O. limosus comprised 15 and 48% of the annual consumption of pike and predatory perch, respectively. Altogether, O. limosus was identified as quantitatively important for the lake's littoral food web, and might also subsidize the pelagic food web. This strengthens the need for an integrated view on lake food webs.

  6. Macrostructure in the Narratives of Estonian Children with Typical Development and Language Impairment

    ERIC Educational Resources Information Center

    Soodla, Piret; Kikas, Eve

    2010-01-01

    Purpose: This study examined the macrostructure in Estonian children's narratives according to the story grammar (SG) model. The study's aims were to determine whether differences exist in narrative macrostructure between Estonian- and English-speaking children, among typically developed (TD) children, and between children with and without…

  7. Expressing Communicative Intents in Estonian, Finnish, and Swedish Mother-Adolescent Interactions

    ERIC Educational Resources Information Center

    Tulviste, Tiia; Mizera, Luule; De Geer, Boel

    2004-01-01

    The present article focused on two types of communicative intent (directing behaviour vs. eliciting talk) expressed by mothers and teenagers during everyday family interactions in Estonian, Finnish, and Swedish mono- and bicultural families. Three monocultural groups consisted of 17 Estonian, 19 Swedish, and 18 Finnish families living in their…

  8. Career Management in Transition: HRD Themes from the Estonian Civil Service

    ERIC Educational Resources Information Center

    Rees, Christopher J.; Jarvalt, Jane; Metcalfe, Beverley

    2005-01-01

    Purpose: To explore, through a case study, some of the key career-related HRD issues that senior managers are currently facing in the Estonian civil service. Design/methodology/approach: Presents primary empirical research into career management in the Estonian civil service since 1991, that is, in the post-Soviet era. The research involved…

  9. The Representation of the Cold War in Three Estonian History Textbooks

    ERIC Educational Resources Information Center

    Korbits, Keit

    2015-01-01

    The article looks at the discursive strategies different Estonian history textbooks employ to represent the Cold War period, and the "commonsense" ideologies instilled through these representations. The textbooks analysed include two history books dating back to the Estonian Soviet Socialist Republic and, for contrast, one written during…

  10. Water quality of Lake Austin and Town Lake, Austin, Texas

    SciTech Connect

    Andrews, F.L.; Wells, F.C.; Shelby, W.J.; McPherson, E.M.

    1988-01-01

    Lake Austin and Town Lake are impoundments on the Colorado River in Travis County, central Texas, and are a source of water for municipal industrial water supplies, electrical-power generation, and recreation for more than 500,000 people in the Austin metropolitan area. Small vertical temperature variations in both lakes were attributed to shallow depths in the lakes and short retention times of water in the lakes during the summer months. The largest areal variations in dissolved oxygen generally occur in Lake Austin during the summer as a result of releases of water from below the thermocline in Lake Travis. Except for iron, manganese, and mercury, dissolved concentrations of trace elements in water collected from Lake Austin and Town Lake did not exceed the primary or secondary drinking water standards set by the US Environmental Protection Agency. Little or no effect of stormwater runoff on temperature, dissolved oxygen, or minor elements could be detected in either Lake Austin or Town Lake. Little seasonal or areal variation was noted in nitrogen concentrations in Lake Austin or Town lake. Total phosphorus concentrations generally were small in both lakes. Increased concentrations of nitrogen and phosphorus were detected after storm runoff inflow in Town Lake, but not in Lake Austin; densities of fecal-coliform bacteria increased in Lake Austin and Town Lake, but were substantially greater in Town Lake than in Lake Austin. 18 refs., 38 figs., 59 tabs.

  11. Similarity scaling of turbulence in a small temperate lake: implications for gas flux

    NASA Astrophysics Data System (ADS)

    Tedford, E. W.; MacIntyre, S.; Vidal, J.; Miller, S. D.; Czikowsky, M.

    2012-12-01

    The rate of dissipation of turbulent kinetic energy (ɛ) can be used to estimate the gas transfer coefficient (k600) using the surface renewal model . To enable predictions of k600 from surface meteorology, we obtained 1400 temperature-gradient microstructure profiles in a 4 km2 lake during fall cooling concurrently with time series measurements of meteorology and CO2 fluxes using an eddy covariance system. Conditions were typical for the fall in the temperate zone. Winds typically varied from near calm to 5 m s-1 but reached 10 m s-1 during three storm events. Currents measured by acoustic Doppler current profiler averaged 2.5 cm s-1 and were as high as 10 cm s-1. Dissipation estimates were on the order of 10-8 to 10-7 m2 s-3 during periods of heating and cooling and reached 10-6 m2 s-3 during windy periods. During calm morning heating, dissipation was on the order of 10-9 m2s-3. We scaled our results using similarity scaling and obtained: ɛ = 0.6 u*3 / k z + 0.3 JB0 where u* is the water friction velocity computed from shear stress, k is von Karmon's constant, z is depth, and JB0 is buoyancy flux at the surface. Thus, ɛ at each depth is a function of the wind stress and buoyancy flux. The Monin-Obukhov length scale, LMO = -u*3/(0.4 JB0), is used to separate the upper-mixed layer into two regions: an upper region, dominated by wind shear; and a lower region, dominated by buoyancy flux.. When transitions between cooling and heating were gradual and winds were moderate, ɛ predicted with the similarity scaling matched the observed ɛ. In other words, during both heating and cooling and above a depth equal to |LMO|, turbulence was dominated by wind shear and dissipation followed law of the wall scaling although was slightly augmented by buoyancy flux during cooling. Below a depth equal to |LMO| during cooling, dissipation was uniform with depth. Below a depth equal to |LMO| during heating, dissipation was strongly suppressed. When winds and heat flux varied rapidly

  12. The Influences of Climate, Landcover, and In-lake Processes on Nitrogen Solutes and Dissolved Organic Carbon in Small Lake-Watersheds on the Southwestern Adirondack Region of New York

    NASA Astrophysics Data System (ADS)

    Ito, M.; Mitchell, M. J.; Driscoll, C. T.; Kretser, W.; Roy, K. M.

    2001-05-01

    In the Adirondack region of New York where soils and surface waters have been found to be highly sensitive to acidic deposition, precipitation concentrations of nitrate have not declined. In order to understand the responses of lake-watersheds to nitrogen deposition in the Adirondack region and to identify effective approaches to deal with potential problems associated with high N deposition, the factors regulating nitrogen solutes in discharge from lake-watersheds are being evaluated. In the present analysis, nitrogen solutes and dissolved organic carbon in two small lake-watersheds were examined from 1999 to 2000 to assess the influences of climate, land cover, and in-lake processes on these solutes in the southwestern part of the Adirondack region where wet deposition of nitrate and nitrate concentrations in surface waters were higher than in other parts of the Adirondacks. The interrelationships among nitrate, ammonium, dissolved organic nitrogen, and dissolved organic carbon were evaluated to assist in characterizing the influences of the above factors.

  13. Wild Estonian and Russian sea trout (Salmo trutta) in Finnish coastal sea trout catches: results of genetic mixed-stock analysis.

    PubMed

    Koljonen, Marja-Liisa; Gross, Riho; Koskiniemi, Jarmo

    2014-12-01

    For responsible fisheries management of threatened species, it is essential to know the composition of catches and the extent to which fisheries exploit weak wild populations. The threatened Estonian, Finnish and Russian sea trout populations in the Gulf of Finland are targets of mixed-stock fisheries. The fish may originate from rivers with varying production capacities, from different countries, and they may also have either a wild or hatchery origin. In order to resolve the composition of Finnish coastal sea trout catches, we created a standardized baseline dataset of 15 DNA microsatellite loci for 59 sea trout populations around the Gulf of Finland and tested its resolution for mixed-stock analysis of 1372 captured fish. The baseline dataset provided sufficient resolution for reliable mixture analysis at regional group level, and also for most of the individual rivers stocks. The majority (76-80%) of the total catch originated from Finnish sea trout populations, 6-9% came from Russian and 12-15% from Estonian populations. Nearly all Finnish trout in the catch were of hatchery origin, while the Russian and Estonian trout were mostly of wild origin. The proportion of fish in the Finnish catches that originated from rivers with natural production was at least one fifth (22%, 19-23%). Two different spotting patterns were observed among the captured trout, with a small and sparsely spotted form being markedly more common among individuals of Russian (28%) and Estonian origin (22%) than among fish assigned to a Finnish origin (0.7%). PMID:25588304

  14. Testicular measurements and daily sperm output of Tori and Estonian breed stallions.

    PubMed

    Kavak, A; Lundeheim, N; Aidnik, M; Einarsson, S

    2003-06-01

    Evaluation of testicular measurements and daily sperm output (DSO) yields valuable information for predicting the reproductive capacity of stallions. The present study evaluated testicular measurements (height, length, width and circumference) and DSO of eight Tori and eight Estonian breed stallions. One ejaculate of semen was collected daily for 10 subsequent days from each stallion. The gel-free volume of semen was measured with a graduated glass cylinder and the sperm concentration was assessed with a Chorjajev chamber. The volume of gel-free fraction was multiplied by the sperm concentration to give the total number of spermatozoa (TSN). The DSO was calculated as mean TSN of collection on days 8-10 in Tori breed stallions and on days 4-10 in Estonian breed stallions. The DSO of Tori breed stallions was 12.9 x 109 spermatozoa and of Estonian breed stallions 4.5 x 109 spermatozoa (p < 0.001). Testicular measurements (in cm) 1 day after the last semen collection were as follows: left testis- height 7.3, length 10.4 and width 7.3 in Tori breed stallions, and 5.9, 8.1 and 5.9, respectively, in Estonian breed stallions; right testis- height 7.4, length 10.6 and width 7.4 in Tori breed stallions, and 5.5, 7.4 and 5.3, respectively, in Estonian breed stallions. All these testicular measurements were significantly smaller in Estonian than in Tori breed stallions (p < 0.001). Testicular circumference was 45.4 and 35.4 cm in Tori and Estonian breed stallions, respectively (p < 0.001). The testicular circumference was correlated with DSO in both Estonian (p < 0.05) and Tori breed stallions (p = 0.071). The results give us valuable information on the reproductive capacity of Tori and Estonian breed stallions. PMID:12753547

  15. Small should be the New Big: High-resolution Models with Small Segments have Big Advantages when Modeling Eutrophication in the Great Lakes

    EPA Science Inventory

    Historical mathematical models, especially Great Lakes eutrophication models, traditionally used course segmentation schemes and relatively simple hydrodynamics to represent system behavior. Although many modelers have claimed success using such models, these representations can ...

  16. An Original Processing Method of Satellite Altimetry for Estimating Water Levels and Volume Fluctuations in a Series of Small Lakes of the Pantanal Wetland Complex in Brazil

    NASA Astrophysics Data System (ADS)

    Henrique Costa, Paulo; Oliveira Pereira, Eric; Maillard, Philippe

    2016-06-01

    Satellite altimetry is becoming a major tool for measuring water levels in rivers and lakes offering accuracies compatible with many hydrological applications, especially in uninhabited regions of difficult access. The Pantanal is considered the largest tropical wetland in the world and the sparsity of in situ gauging station make remote methods of water level measurements an attractive alternative. This article describes how satellites altimetry data from Envisat and Saral was used to determine water level in two small lakes in the Pantanal. By combining the water level with the water surface area extracted from satellite imagery, water volume fluctuations were also estimated for a few periods. The available algorithms (retrackers) that compute a range solution from the raw waveforms do not always produce reliable measurements in small lakes. This is because the return signal gets often "contaminated" by the surrounding land. To try to solve this, we created a "lake" retracker that rejects waveforms that cannot be attributed to "calm water" and convert them to altitude. Elevation data are stored in a database along with the water surface area to compute the volume fluctuations. Satellite water level time series were also produced and compared with the only nearby in situ gauging station. Although the "lake" retracker worked well with calm water, the presence of waves and other factors was such that the standard "ice1" retracker performed better on the overall. We estimate our water level accuracy to be around 75 cm. Although the return time of both satellites is only 35 days, the next few years promise to bring new altimetry satellite missions that will significantly increase this frequency.

  17. Can short-term and small-scale experiments reflect nutrient limitation on phytoplankton in natural lakes?

    NASA Astrophysics Data System (ADS)

    Wang, Haijun; Li, Yan; Feng, Weisong; Yu, Qing; Xiao, Xucheng; Liang, Xiaomin; Shao, Jianchun; Ma, Shuonan; Wang, Hongzhu

    2016-07-01

    Whether it is necessary to reduce nitrogen (N) and/or phosphorus (P) input to mitigate lake eutrophication is controversial. The controversy stems mainly from differences in time and space in previous studies that support the contrasting ideas. To test the response of phytoplankton to various combinations of nutrient control strategies in mesocosms and the possibility of reflecting the conditions in natural ecosystems with short-term experiments, a 9-month experiment was carried out in eight 800-L tanks with four nutrient level combinations (+N+P, -N+P, +N-P, and -N-P), with an 18-month whole-ecosystem experiment in eight ~800-m 2 ponds as the reference. Phytoplankton abundance was determined by P not N, regardless of the initial TN/TP level, which was in contrast to the nutrient limitation predicted by the N/P theory. Net natural N inputs were calculated to be 4.9, 6.8, 1.5, and 3.0 g in treatments +N+P, -N+P, +N-P, and -N-P, respectively, suggesting that N deficiency and P addition may promote natural N inputs to support phytoplankton development. However, the compensation process was slow, as suggested by an observed increase in TN after 3 weeks in -N+P and 2 months in -N-P in the tank experiment, and after 3 months in -N +P and ~3 months in -N-P in our pond experiment. Obviously, such a slow process cannot be simulated in short-term experiments. The natural N inputs cannot be explained by planktonic N-fixation because N-fixing cyanobacteria were scarce, which was probably because there was a limited pool of species in the tanks. Therefore, based on our results we argue that extrapolating short-term, small-scale experiments to large natural ecosystems does not give reliable, accurate results.

  18. Dramatic water-level fluctuations in lakes under intense human impact: modelling the effect of vegetation, climate and hydrogeology

    NASA Astrophysics Data System (ADS)

    Vainu, M.

    2012-04-01

    Lakes form a highly important ecosystem in the glacial terrain of northern Europe and America, but their hydrology remains understudied. When the water-level of a lake drops significantly and rises again in a time span of half a century and the widespread explanation of the fluctuations seems insufficient, then it raises a question: how do different anthropogenic and natural processes actually affect the formation of a lakes' water body. The abovementioned scenario applies to three small closed-basin Estonian lakes (L. Ahnejärv, L. Kuradijärv and L. Martiska) analysed in the current study. These lakes suffered a major water-level drop (up to 3.8 m) between 1946 and 1987 and a major rise between 1987 and 2010, from 1 m (L. Ahnejärv) to 2.5 m (L. Kuradijärv). Decreasing and increasing groundwater abstraction near the lakes has been widely considered to be the only reason for the fluctuations. It is true that the most severe drop in the lake levels did occur after 1972 when groundwater abstraction for drinking water started in the vicinity of the lakes. However, the lake levels started to fall before the groundwater abstraction began and for the time being the lake levels have risen to a higher level than in the 1970s when the quantity of annually abstracted groundwater was similar to nowadays. Therefore the processes affecting the formation of the lakes' water body prove to be more complex than purely the hydrogeological change caused by groundwater abstraction. A new deterministic water balance model (where the evaporation from the lake surface was calculated by Penman equation and the catchment runoff by Thornthwaite-Mather soil-moisture model), compiled for the study, coupled with LiDAR-based GIS-modelling of the catchments was used to identify the different factors influencing the lakes' water level. The modelling results reveal that the moderate drop in lake water levels before the beginning of groundwater abstraction was probably caused by the growth of a

  19. An epidemiological perspective of personalized medicine: the Estonian experience

    PubMed Central

    Milani, L; Leitsalu, L; Metspalu, A

    2015-01-01

    Milani L, Leitsalu L, Metspalu A (University of Tartu). An epidemiological perspective of personalized medicine: the Estonian experience (Review). J Intern Med 2015; 277: 188–200. The Estonian Biobank and several other biobanks established over a decade ago are now starting to yield valuable longitudinal follow-up data for large numbers of individuals. These samples have been used in hundreds of different genome-wide association studies, resulting in the identification of reliable disease-associated variants. The focus of genomic research has started to shift from identifying genetic and nongenetic risk factors associated with common complex diseases to understanding the underlying mechanisms of the diseases and suggesting novel targets for therapy. However, translation of findings from genomic research into medical practice is still lagging, mainly due to insufficient evidence of clinical validity and utility. In this review, we examine the different elements required for the implementation of personalized medicine based on genomic information. First, biobanks and genome centres are required and have been established for the high-throughput genomic screening of large numbers of samples. Secondly, the combination of susceptibility alleles into polygenic risk scores has improved risk prediction of cardiovascular disease, breast cancer and several other diseases. Finally, national health information systems are being developed internationally, to combine data from electronic medical records from different sources, and also to gradually incorporate genomic information. We focus on the experience in Estonia, one of several countries with national goals towards more personalized health care based on genomic information, where the unique combination of elements required to accomplish this goal are already in place. PMID:25339628

  20. Evaluation of 11 equations for determining evaporation for a small lake in the North Central United States

    USGS Publications Warehouse

    Winter, T.C.; Rosenberry, D.O.; Sturrock, A.M.

    1995-01-01

    Eleven equations for calculating evaporation were compared with evaporation determined by the energy budget method for Williams Lake, Minnesota. Data were obtained from instruments on a raft, on land near the lake, and at a weather station 60 km south of the lake. The comparisons were based on monthly values for the open-water periods of 5 years, a total of 22 months. A modified DeBruin-Keijman, Priestley-Taylor, and a modified Penman equation resulted in monthly evaporation values that agreed most closely with energy budget values. To use these equations, net radiation, air temperature, wind speed, and relative humidity need to be measured near the lake. In addition, thermal surveys need to be made to determine change in heat stored in the lake. If data from distant climate stations are the only data available, and they include solar radiation, the Jensen-Haise and Makkink equations resulted in monthly evaporation values that agreed reasonably well with energy budget values.

  1. How do groundwater-dependent lakes react if the aquifer they rely on is being pumped?

    NASA Astrophysics Data System (ADS)

    Vainu, Marko; Terasmaa, Jaanus

    2015-04-01

    Groundwater is a valuable source of drinking water, but at the same time it is the primary contributor to the existence of many surface water bodies. If the latter truth is overlooked in water resources management, and ground- and surface water are not considered as a single resource, then the sustainability of groundwater-dependent ecosystems will become under threat. The necessity for implementing an integrated management of ground- and surface water has also been stressed in the EU Water Framework Directive. This study aims to evaluate the effect of increased groundwater abstraction to groundwater and lake levels; and to evaluate the effect of increased groundwater abstraction to the seepage patterns in one example lake. The Kurtna Lake District in northeastern Estonia contains almost 40 small lakes which are situated in and around the Kurtna Kame Field and constitute an EU Special Area of Conservation. The sands that form the kame field contain a Quaternary groundwater aquifer. Water has been pumped from the aquifer for household use with varying rates since the 1970s, but starting from the summer of 2012 the average pumping rate was increased by 51% compared to the year before. During the current study the water levels of five lakes were monitored regularly from May 2012 to June 2013 - before and after the increase in the pumping rate. The water levels dropped 0.3 to 0.7 m during the year in three closed-basin lakes closest to the abstraction wells, but did not change neither in a flow-through lake nor in a closed-basin lake situated 1.6 km from the wells. Groundwater level in the aquifer (monitored by the Estonian Geological Survey) dropped up to 0.8 m near the abstraction wells in the course of the year, but did not change further from the wells. The estimates of average annual groundwater recharge were derived for the twelve months before both June 2012 and June 2013. Although the recharge rate was lower in the first year, the water-level drop was

  2. Assessing the potential of Medium-Resolution Imaging Spectrometer (MERIS) and Moderate-Resolution Imaging Spectroradiometer (MODIS) data for monitoring total suspended matter in small and intermediate sized lakes and reservoirs

    NASA Astrophysics Data System (ADS)

    Tarrant, P. E.; Amacher, J. A.; Neuer, S.

    2010-09-01

    Satellite remote sensing has been used extensively for many years to monitor the open oceans and coastal waters. These methods have been extended more recently to the study of inland waters. In this study we consider the potential application of data from two ocean color sensors, Moderate-Resolution Imaging Spectroradiometer (MODIS) and Medium-Resolution Imaging Spectrometer (MERIS), for monitoring the levels of suspended solids in small and intermediate sized lakes and reservoirs. We measured total suspended matter (TSM) in four southwestern United States lakes, Roosevelt Lake, Saguaro Lake, Bartlett Lake, and Lake Pleasant, and compared these field data with images obtained from these medium resolution satellite sensors. Our regression analysis of the complete data set identified a linear relationship between the field TSM values and both MODIS 250 m data (r2 = 0.461) and MERIS 290 m data (r2 = 0.521). This relationship improved substantially when data from the smallest lake in the study (Saguaro Lake) were excluded from the analysis (r2 = 0.819 and r2 = 0.888, respectively). The resultant linear models produced estimates with a root-mean-square error (RMSE) ranging from 3.14 mg/L (MODIS) and 2.04 mg/L (MERIS) for all four lakes combined, improving to 1.32 mg/L (MODIS) and 0.47 mg/L (MERIS) for a lake-specific regression. These results suggest that these satellite sensors have the potential to effectively monitor TSM in lakes and reservoirs, although a minimum practical lake size does appear to exist.

  3. Musical Practices and Methods in Music Lessons: A Comparative Study of Estonian and Finnish General Music Education

    ERIC Educational Resources Information Center

    Sepp, Anu; Ruokonen, Inkeri; Ruismäki, Heikki

    2015-01-01

    This article reveals the results of a comparative study of Estonian and Finnish general music education. The aim was to find out what music teaching practices and approaches/methods were mostly used, what music education perspectives supported those practices. The data were collected using questionnaires and the results of 107 Estonian and 50…

  4. Lake whitefish and lake herring population structure and niche in ten south-central Ontario lakes

    USGS Publications Warehouse

    Carl, Leon M.; McGuiness, Fiona

    2006-01-01

    This study compares simple fish communities of ten oligotrophic lakes in south-central Ontario. Species densities and population size structure vary significantly among these lake communities depending on fish species present beyond the littoral zone. Lake whitefish are fewer and larger in the presence of lake herring than in their absence. Diet analysis indicates that lake whitefish shift from feeding on both plankton and benthic prey when lake herring are absent to a primarily benthic feeding niche in the presence of lake herring. When benthic round whitefish are present, lake whitefish size and density decline and they move lower in the lake compared to round whitefish. Burbot are also fewer and larger in lakes with lake herring than in lakes without herring. Burbot, in turn, appear to influence the population structure of benthic coregonine species. Lower densities of benthic lake whitefish and round whitefish are found in lakes containing large benthic burbot than in lakes with either small burbot or where burbot are absent. Predation on the pelagic larvae of burbot and lake whitefish by planktivorous lake herring alters the size and age structure of these populations. As life history theory predicts, those species with poor larval survival appear to adopt a bet-hedging life history strategy of long-lived individuals as a reproductive reserve.

  5. Diversity and Dynamics of Active Small Microbial Eukaryotes in the Anoxic Zone of a Freshwater Meromictic Lake (Pavin, France)

    PubMed Central

    Lepère, Cécile; Domaizon, Isabelle; Hugoni, Mylène; Vellet, Agnès; Debroas, Didier

    2016-01-01

    Microbial eukaryotes play a crucial role in ecosystem functioning and oxygen is considered to be one of the strongest barriers against their local dispersal. However, diversity of microbial eukaryotes in freshwater habitats with oxygen gradients has previously received very little attention. We applied high-throughput sequencing (V4 region of the 18S rRNA gene) in conjunction with quantitative PCR (DNA and RNA) and fluorescent in situ hybridization (FISH) analyses, to provide an unique spatio-temporal analysis of microbial eukaryotes diversity and potential activity in a meromictic freshwater lake (lake Pavin). This study revealed a high genetic diversity of unicellular eukaryotes in the permanent anoxic zone of lake Pavin and allowed the discrimination of active vs. inactive components. Forty-two percent of the OTUs (Operational Taxonomic Units) are exclusively present in the monimolimnion, where Alveolata (Ciliophora and Dinophyceae) and Fungi (Dikarya and Chytrids) are the most active phyla and are probably represented by species capable of anaerobic metabolism. Pigmented eukaryotes (Haptophyceae and Chlorophyceae) are also present and active in this zone, which opens up questions regarding their metabolism. PMID:26904006

  6. The behavior of uranium and manganese under the diagenesis of carbonate sediments in small lakes of the Baikal region

    NASA Astrophysics Data System (ADS)

    Vosel, Yu. S.; Strakhovenko, V. D.; Makarova, I. V.; Vosel, S. V.

    2015-05-01

    This report considers the experimental studies of diagenetic processes involving uranium and manganese in lacustrine sediments, especially to prove the possibility of formation of UO2 + x reduced phases. Comparative research was performed for two lakes of different depths, hydrological conditions, mineralization, and chemical composition of waters. The layerwise successive leaching of sediments was carried out, with subsequent measurement of the contents of the uranium-238 and -234 isotopes in chemogenic fractions of the sediment. By means of ESR and successive leaching, the profiles of the manganese oxide and hydroxide content over the section were obtained. The performed studies confirmed the hypothesis of the formation of UO2 + x reduced phases in sediments. The sediments of the deeper freshwater Alyaty Lake are characterized by an increase in the content of the UO2 + x reduced phases and a decrease of manganese oxides and hydroxides downwards and upwards through the section, respectively. This conforms quite well to the behavior of these elements in oceanic sediments. The shallow saline Tsagan-Tyrm Lake is characterized by the reverse situation: the bulk of the UO2 + x reduced phase occurs in upper layers where, in turn, the oxide phases of manganese are simply absent. This is caused by different reductive conditions in the sediments.

  7. Lake Life.

    ERIC Educational Resources Information Center

    Ohrn, Deborah Gore, Ed.

    1993-01-01

    This quarterly publication of the State Historical Society of Iowa features articles and activities for elementary school students. This summer issue focuses on the topic of lake life. The issue includes the following features: (1) "Where the Lakes Are Map"; (2) "Letter from the Lake"; (3) "Lake People"; (4) "Spirit Lake"; (5) "Lake Manawa"; (6)…

  8. History of experimental psychology from an Estonian perspective.

    PubMed

    Allik, Jüri

    2007-11-01

    A short review of the development of experimental psychology from an Estonian perspective is presented. The first rector after the reopening of the University of Dorpat (Tartu) in 1802, Georg Friedrich Parrot (1767-1852) was interested in optical phenomena which he attempted to explain by introducing the concept of unconscious inferences, anticipating a similar theory proposed by Herman von Helmholtz 20 years later. One of the next rectors, Alfred Wilhelm Volkmann (1800-1878) was regarded by Edwin Boring as one of the founding fathers of the experimental psychology. Georg Wilhelm Struve (1793-1864) played an essential part in solving the problem of personal equations. Arthur Joachim von Oettingen (1836-1920) developed a theory of music harmony, which stimulated his student Wilhelm Friedrich Ostwald (1853-1932) to study colour harmony. Emil Kraepelin (1856-1926), the founder of modern psychiatry, is by far the most important experimental psychologist who has worked in Estonia. His successor Wladimir von Tchisch (1855-1922), another student of Wilhelm Wundt, continued Kraepelin's work in experimental psychology. The lives of Wolfgang Köhler (1887-1967), who was born in Reval (Tallinn), and Oswald Külpe (1862-1915), who graduated from the University of Dorpat, extended the link between the history of experimental psychology and Estonia. Karl Gustav Girgensohn (1875-1925), the founder of the Dorpat School of the psychology of religion, stretched the use of experimental methods to the study of religious experience. PMID:16639614

  9. Lake sturgeon population characteristics in Rainy Lake, Minnesota and Ontario

    USGS Publications Warehouse

    Adams, W.E., Jr.; Kallemeyn, L.W.; Willis, D.W.

    2006-01-01

    Rainy Lake contains a native population of lake sturgeon Acipenser fulvescens that has been largely unstudied. The aims of this study were to document the population characteristics of lake sturgeon in Rainy Lake and to relate environmental factors to year-class strength for this population. Gill-netting efforts throughout the study resulted in the capture of 322 lake sturgeon, including 50 recaptures. Lake sturgeon in Rainy Lake was relatively plump and fast growing compared with a 32-population summary. Population samples were dominated by lake sturgeon between 110 and 150 cm total length. Age–structure analysis of the samples indicated few younger (<10 years) lake sturgeon, but the smallest gill net mesh size used for sampling was 102 mm (bar measure) and would not retain small sturgeon. Few lake sturgeon older than age 50 years were captured, and maximum age of sampled fish was 59 years. Few correlations existed between lake sturgeon year-class indices and both annual and monthly climate variables, except that mean June air temperature was positively correlated with year-class strength. Analysis of Rainy Lake water elevation and resulting lake sturgeon year-class strength indices across years yielded consistent but weak negative correlations between late April and early June, when spawning of lake sturgeon occurs. The baseline data collected in this study should allow Rainy Lake biologists to establish more specific research questions in the future.

  10. The near extinction of lake trout in Lake Michigan

    USGS Publications Warehouse

    Eschmeyer, Paul H.

    1957-01-01

    Comparisons in 1949 and 1950 of numbers of legal-sized lake trout caught in large-mesh nets with numbers of small fish taken in chub nets showed that both large and small lake trout declined over the same period, and that by these years the decline may have been greater among small than among legal-sized fish.

  11. Venezuela: Lake Maracaibo

    Atmospheric Science Data Center

    2013-04-18

    article title:  Oil Slicks on Lake Maracaibo, Venezuela     View Larger Image Several oil slicks occurred on Lake Maracaibo in northwestern Venezuela between ... wave facets divert reflected rays into many directions. An oil film dampens the presence of small wind-driven "capillary" waves, resulting ...

  12. Spatial and Temporal Dynamics in the Relationship of Phytoplankton Biomass and Limnological Variables in a Small Artificial Lake

    NASA Astrophysics Data System (ADS)

    Li, Feipeng; Zhang, Haiping; Zhu, Yiping; Chen, Ling; Zhao, Jianfu

    2010-11-01

    Zhongxin Lake is an artificial freshwater lake located in Qianwei Village of Chongming Island, the third largest island in China. Besides its culture function and aesthetic value, it is also an ideal target, which can be regarded as an enclosed and simplified ecosystem with little external pollution. The objective of the study is to determine the spatial and temporal dynamics in the relationship between phytoplankton and main limnological variables. An intensive observation and monitoring program was performed more than one year at six sampling points along five locally connected watercourses. Nutrient levels and their seasonal variables might be the main factors which control the temporal development of phytoplankton. Chlorophyll-a (chl-a) levels peaked from late August to September and showed a significant positive correlation with water temperature, turbidity, total nitrogen (TN), total phosphorus (TP) and dissolved total phosphorus (DTP). Wind driven flow and geographical features appears to be the limiting factors for the spatial dynamics of phytoplankton. Higher average chl-a levels caused higher turbidity in the south and middle watercourses which are separated by dams and where shallow-circulation flow can be hardly maintained. Low average chl-a levels were recorded in the north watercourse in conditions of lower water levels, direct connection with the east watercourse and west watercourse and higher prevailing wind driven flow. The findings have strongly shown the influence of nutrients and hydro-meteorological variables as important factors of spatial and temporal dynamics of phytoplankton biomass.

  13. Use of coals for cocombustion with Estonian shale oil

    NASA Astrophysics Data System (ADS)

    Roslyakov, P. V.; Zaichenko, M. N.; Melnikov, D. A.; Vereshetin, V. A.; Attikas, Raivo

    2016-03-01

    The article reports the results of investigation into the possibility of using off-design coals as an additional fuel in connection with predicted reduction in the heat of combustion of shale oil and more stringent environmental regulations on harmful emissions. For this purpose, a mathematical model of a TP-101 boiler at the Estonian Power Plant has been constructed and verified; the model describes the boiler's current state. On the basis of the process flow chart, the experience of operating the boiler, the relevant regulations, and the environmental requirement criteria for evaluation of the equipment operation in terms of reliability, efficiency, and environmental safety have been developed. These criteria underlie the analysis of the calculated operating parameters of the boiler and the boiler plant as a whole upon combustion with various shale-oil-to-coal ratios. The computational study shows that, at the minimal load, the normal operation of the boiler is ensured almost within the entire range of the parts by the heat rate of coal. With the decreasing load on the boiler, the normal equipment operation region narrows. The basic limitation factors are the temperature of the steam in the superheater, the temperature of the combustion products at the furnace outlet and the flow rate of the combustion air and flue gases. As a result, the parts by heat rate of lignite and bituminous coal have been determined that ensure reliable and efficient operation of the equipment. The efficiency of the boiler with the recommended lignite-to-coal ratio is higher than that achieved when burning the design shale oil. Based on the evaluation of the environmental performance of the boiler, the necessary additional measures to reduce emissions of harmful substances into the atmosphere have been determined.

  14. Three-year survey of abundance, prevalence and genetic diversity of chlorovirus populations in a small urban lake.

    PubMed

    Quispe, Cristian F; Sonderman, Olivia; Seng, Anya; Rasmussen, Brenna; Weber, Garrett; Mueller, Claire; Dunigan, David D; Van Etten, James L

    2016-07-01

    Inland water environments cover about 2.5 percent of our planet and harbor huge numbers of known and still unknown microorganisms. In this report, we examined water samples for the abundance, prevalence, and genetic diversity of a group of infectious viruses (chloroviruses) that infect symbiotic chlorella-like green algae. Samples were collected on a weekly basis for a period of 24 to 36 months from a recreational freshwater lake in Lincoln, Nebraska, and assayed for infectious viruses by plaque assay. The numbers of infectious virus particles were both host- and site-dependent. The consistent fluctuations in numbers of viruses suggest their impact as key factors in shaping microbial community structures in the water surface. Even in low-viral-abundance months, infectious chlorovirus populations were maintained, suggesting either that the viruses are very stable or that there is ongoing viral production in natural hosts. PMID:27068168

  15. Growth and mortality of Cichla spp. (Perciformes, Cichlidae) introduced in Volta Grande Reservoir (Grande River) and in a small artificial lake in Southeastern Brazil.

    PubMed

    Gomiero, L M; Carmassi, A L; Rondineli, G R; Villares Junior, G A; Braga, F M S

    2010-11-01

    The growth and mortality parameters were estimated through the analysis of length frequency distribution for species of Cichla spp. introduced into a lake in Leme (SP), and in Volta Grande reservoir (SP-MG). In Leme, Cichla kelberi presented larger frequency in the inferior classes of lengths, larger instantaneous rate of natural mortality, and smaller number of cohorts than C. kelberi and C. piquiti in Volta Grande. The values of growth performance obtained for the species were similar, corroborating the validity of the estimated growth and mortality parameters. The increase of the growth rate in small and less diverse environments occurs due to predation. The genus Cichla adapts well in locations in which it is introduced, however this adaptation shows itself to be strongly adjusted to each particular location, determining great plasticity and establishment capacity. PMID:21180920

  16. Conceptions of Finnish and Estonian Pre-School Teachers' Goals in Their Pedagogical Work

    ERIC Educational Resources Information Center

    Niikko, Anneli; Ugaste, Aino

    2012-01-01

    The purpose of this study is to describe the conceptions of the Finnish and Estonian pre-school teachers' goals, and the achievement of these goals in their pedagogical work. The study consisted of 60 (30 from each country) interviews with pre-school teachers. The interview data was analyzed phenomenographically. The findings showed that children…

  17. Identifying the Problems That Finnish and Estonian Teachers Encounter in Preschool

    ERIC Educational Resources Information Center

    Ugaste, Aino; Niikko, Anneli

    2015-01-01

    The purpose of this study is to describe Finnish and Estonian preschool teachers' thoughts on the problems they encounter in their pedagogical work in the preschool context. The study involved interviews with 80 preschool teachers (40 in each country). The theoretical framework of the study is based on quality as a pedagogical phenomenon, whereby…

  18. Comprehension and Production of Noun Compounds by Estonian Children with Specific Language Impairment

    ERIC Educational Resources Information Center

    Padrik, Marika; Tamtik, Merli

    2009-01-01

    The authors examined how 12 Estonian-speaking children with specific language impairment (SLI) and 60 children with normal speech development (ND) comprehended compound nouns with differing sequence of the components (first task) and how they produced compound nouns to label genuine and accidental categories by using analogy (second task) and…

  19. Estonian Language Competencies for Peace Corps Volunteers in the Republic of Estonia.

    ERIC Educational Resources Information Center

    Ets, Tiina K.

    This guide is designed for Estonian language training of Peace Corps workers in Estonia, is intended for use in a competency-based language training program, and reflects daily communication needs in that context. It consists of 52 lessons, each addressing a specific language competency, organized in 14 topical units. An introductory section gives…

  20. Estonian Science and Non-Science Students' Attitudes towards Mathematics at University Level

    ERIC Educational Resources Information Center

    Kaldo, Indrek; Reiska, Priit

    2012-01-01

    This article investigates the attitudes and beliefs towards studying mathematics by university level students. A total of 970 randomly chosen, first year, Estonian bachelor students participated in the study (of which 498 were science students). Data were collected using a Likert-type scale questionnaire and analysed with a respect to field of…

  1. Consumer Socialisation and Value Orientations among Estonian and Chinese Young People

    ERIC Educational Resources Information Center

    Waerdahl, Randi; Kalmus, Veronika; Keller, Margit

    2011-01-01

    This paper asks if Estonian and Chinese tweens' access to pocket money influences their brand valuation, as well as value orientations in the context of perceived peer popularity and personal well-being. Surveys conducted in autumns 2006 (China n = 188) and 2007 (Estonia n = 111) show an inherent cultural resistance among tweens in both countries…

  2. Orthographic Depth and Spelling Acquisition in Estonian and English: A Comparison of Two Diverse Alphabetic Languages

    ERIC Educational Resources Information Center

    Viise, Neva M.; Richards, Herbert C.; Pandis, Meeli

    2011-01-01

    In this study, we investigated the link between the orthographic transparency of a language and the ease or difficulty of acquiring spelling proficiency in that language. The two languages compared are English, with a highly irregular sound-to-print correspondence, and Estonian, a Finno-Ugric language that has one of the most highly regular…

  3. Tiger in Focus--A National Survey of ICT in Estonian Schools

    ERIC Educational Resources Information Center

    Toots, Anu; Laanpere, Mart

    2004-01-01

    Estonia has not participated in international studies of ICT in education, nor have there been any similar studies at the national level up until the year 2000. The first survey of ICT in Estonian schools was conducted after completion of the national school computerization programme called Tiger Leap. This paper focuses on the targeted responses…

  4. Assessing Estonian Mothers' Involvement in Their Children's Education and Trust in Teachers

    ERIC Educational Resources Information Center

    Kikas, Eve; Peets, Katlin; Niilo, Airi

    2011-01-01

    Questionnaires assessing mothers' involvement in children's education and their trust in teachers were developed for the usage in Estonian kindergartens and elementary schools. The scales were adapted based on the questionnaires by Fantuzzo and colleagues (parental involvement) and Adams and Christenson (trust). Mothers of 454 kindergarten…

  5. Estonian Vocational Teachers' Attitudes towards Inclusive Education for Students with Special Educational Needs

    ERIC Educational Resources Information Center

    Rose, Richard; Kaikkonen, Leena; Koiv, Kristi

    2007-01-01

    This paper presents the findings from research conducted with two samples of teachers from Estonian Vocational Schools. The first sample comprised a group of teachers who had received professional development directly related to the management of students with special educational needs in vocational education settings. Their attitudes and…

  6. The contribution of the Estonian Soil Sciences Society to the science, society and education

    NASA Astrophysics Data System (ADS)

    Rossner, Helis; Reintam, Endla; Astover, Alar; Shanskiy, Merrit

    2015-04-01

    Predecessor of todays Estonian Soil Science Society was Estonian Branch of All-Union Soil Society of Soil Scientist which acted from 1957 to 1991. In 1957-1964 Estonian Branch was leaded by prof. Osvald Hallik and in 1964-1991 by prof. Loit Reintam. After re-independence of Estonia in 1991 the society acted in informal way and was leaded by prof. L. Reintam. Non-profit organization "Estonian Soil Science Society" was officially (re)established in 10.23.2009. Estonian Soil Science Society (ESSS) is aimed to: • coordinate collaboration between institutions and individuals intrested of soil science, conservation and sustainable use of soils; • promoting soil science education and research, raising awareness of publicity on topics relating to soils in Estonia; • cooperation between local and foreign unions and associations. In recent years the ESSS had managed to reunite the number of soil scientist from different research institutions of Estonia and of related institutions. Also, the ESSS had provided numerous of materials based on later scientific findings. One of most important activity leaded by ESSS is the organizing Soil Day in Estonia with relevant seminar, where the speakers are sharing latest information with target group (researchers, teachers, policy makers, farmers, students etc.). In a frames of Soil Day the Soil of the Year is selected for Estonia. In 2015, the soil of the year is Leptosol. For current, International Year of the Soil ESSS had planned numerous activities to introduce the importance of soils to wider audience. In current presentation we would like to share the soil science researchers experience through- out the decades of soil science research in Estonia, show our latest findings and designed activities for the International Year of SOIL.

  7. Somatotype in 6-11-year-old Italian and Estonian schoolchildren.

    PubMed

    Ventrella, A R; Semproli, S; Jürimäe, J; Toselli, S; Claessens, A L; Jürimäe, T; Brasili, P

    2008-01-01

    The study of somatotypes can contribute to the understanding of variability in human body build. The aim of this study was to compare the somatotypes of Italian and Estonian schoolchildren in order to evaluate factors that might lead to variability in somatotypes. The sample consisted of 762 Italian and 366 Estonian children aged 6-11 years. They were somatotyped by the Heath-Carter anthropometric method. Data on organised extra-curricular physical activity and hours of weekly training were also collected. One-way ANOVA was used to evaluate country-related variations of somatotype in each age/sex group, while factorial ANOVA was used to test the influence of country and organised physical activity on the variability of the anthropometric characteristics and somatotype components. There are significant differences in mean somatotypes between the Italian and Estonian children in many age classes and a different constitutional trend in children from the two different countries is observed. The Italian children are more endomorphic and less mesomorphic and ectomorphic than the Estonian children. On the other hand, it emerges from factorial ANOVA, that the somatotype components do not present significant variations related to organised physical activity and to the interaction between the country of origin and sport practice. Moreover, the results of the forward stepwise discriminant analyses show that mesomorphy is the best discriminator between the two countries, followed by ectomorphy. Our findings suggest that the observed differences between Italian and Estonian children could be related mainly to country rather than to the practice of organised physical activity in the two countries. PMID:18995850

  8. Fishing farmers or farming fishers? Fishing typology of inland small-scale fishing households and fisheries management in singkarak lake, west sumatra, indonesia.

    PubMed

    Yuerlita; Perret, Sylvain Roger; Shivakoti, Ganesh P

    2013-07-01

    Technical and socio-economic characteristics are known to determine different types of fishers and their livelihood strategies. Faced with declining fish and water resources, small-scale fisheries engage into transformations in livelihood and fishing practices. The paper is an attempt to understand these changes and their socio-economic patterns, in the case of Singkarak Lake in West Sumatra, Indonesia. Based upon the hypothesis that riparian communities have diverse, complex yet structured and dynamic livelihood systems, the paper's main objective is to study, document and model the actual diversity in livelihood, practices and performance of inland small-scale fisheries along the Singkarak Lake, to picture how households are adapted to the situation, and propose an updated, workable model (typology) of those for policy. Principal component analysis and cluster analysis were used to develop a typology of fishing households. The results show that small-scale fishers can be classified into different types characterized by distinct livelihood strategies. Three household types are identified, namely "farming fishers" households (type I, 30 %), "fishing farmers" households (type II, 30 %), and "mainly fishers" households (type III, 40 %). There are significant differences among these groups in the number of boats owned, annual fishing income, agriculture income and farming experience. Type I consists of farming fishers, well equipped, with high fishing costs and income, yet with the lowest return on fishing assets. They are also landowners with farming income, showing the lowest return on land capital. Type II includes poor fishing farmers, landowners with higher farming income; they show the highest return on land asset. They have less fishing equipment, costs and income. Type III (mainly fishers) consists of poorer, younger fishers, with highest return on fishing assets and on fishing costs. They have little land, low farming income, and diversified livelihood

  9. Fishing Farmers or Farming Fishers? Fishing Typology of Inland Small-Scale Fishing Households and Fisheries Management in Singkarak Lake, West Sumatra, Indonesia

    NASA Astrophysics Data System (ADS)

    Yuerlita; Perret, Sylvain Roger; Shivakoti, Ganesh P.

    2013-07-01

    Technical and socio-economic characteristics are known to determine different types of fishers and their livelihood strategies. Faced with declining fish and water resources, small-scale fisheries engage into transformations in livelihood and fishing practices. The paper is an attempt to understand these changes and their socio-economic patterns, in the case of Singkarak Lake in West Sumatra, Indonesia. Based upon the hypothesis that riparian communities have diverse, complex yet structured and dynamic livelihood systems, the paper's main objective is to study, document and model the actual diversity in livelihood, practices and performance of inland small-scale fisheries along the Singkarak Lake, to picture how households are adapted to the situation, and propose an updated, workable model (typology) of those for policy. Principal component analysis and cluster analysis were used to develop a typology of fishing households. The results show that small-scale fishers can be classified into different types characterized by distinct livelihood strategies. Three household types are identified, namely "farming fishers" households (type I, 30 %), "fishing farmers" households (type II, 30 %), and "mainly fishers" households (type III, 40 %). There are significant differences among these groups in the number of boats owned, annual fishing income, agriculture income and farming experience. Type I consists of farming fishers, well equipped, with high fishing costs and income, yet with the lowest return on fishing assets. They are also landowners with farming income, showing the lowest return on land capital. Type II includes poor fishing farmers, landowners with higher farming income; they show the highest return on land asset. They have less fishing equipment, costs and income. Type III (mainly fishers) consists of poorer, younger fishers, with highest return on fishing assets and on fishing costs. They have little land, low farming income, and diversified livelihood

  10. Availability of lake trout reproductive habitat in the Great Lakes

    USGS Publications Warehouse

    Edsall, Thomas A.; Kennedy, Gregory W.

    1995-01-01

    A decades-long program to reestablish self-sustaining stocks of lake trout (Salvelinus namaycush) in the four lower Great Lakes produced excellent fisheries supported by stocked fish. These fish spawned widely and small numbers of their offspring were collected intermittently from Lakes Michigan, Huron, and Ontario, but no self-sustaining stocks were established. Irt this paper we address habitat sufficiency as a factor in the failure of stocked lake trout to established self-sustaining populations in the four lower Great Lakes. We present the previously unpublished results of lake trout spawning habitat surveys conducted at seven sites in the Great Lakes since 1987 and we compare them with the published results of similar surveys conducted at 24 other sites in the four lower lakes since 1981. Our evaluation indicates all but two of these sites can support the production of viable fry from spawnings by the shallow-water strains of lake trout that are stocked in the Great Lakes. However, some of the best spawning, egg, and fry habitat in the lower Great Lakes seems to be at deeper offshore sites that may be unattractive to these shallow-water strains. Thus, we suggest also stocking the lower four lakes with strains from Lake Superior that might more fully exploit the best spawning habitat at these deeper, offshore sites.

  11. A comparison of turtle sampling methods in a small lake in Standing Stone State Park, Overton County, Tennessee

    USGS Publications Warehouse

    Weber, A.; Layzer, James B.

    2011-01-01

    We used basking traps and hoop nets to sample turtles in Standing Stone Lake at 2-week intervals from May to November 2006. In alternate weeks, we conducted visual basking surveys. We collected and observed four species of turtles: spiny softshell (Apalone spinifera), northern map turtle (Graptemys geographica), pond slider (Trachernys scripta), and snapping turtle (Chelydra serpentina). Relative abundances varied greatly among sampling methods. To varying degrees, all methods were species selective. Population estimates from mark and recaptures of three species, basking counts, and hoop net catches indicated that pond sliders were the most abundant species, but northern map turtles were 8× more abundant than pond sliders in basking trap catches. We saw relatively few snapping turtles basking even though population estimates indicated they were the second most abundant species. Populations of all species were dominated by adult individuals. Sex ratios of three species differed significantly from 1:1. Visual surveys were the most efficient method for determining the presence of species, but capture methods were necessary to obtain size and sex data.

  12. Sources and distribution of trace elements in Estonian peat

    NASA Astrophysics Data System (ADS)

    Orru, Hans; Orru, Mall

    2006-10-01

    This paper presents the results of the distribution of trace elements in Estonian mires. Sixty four mires, representative of the different landscape units, were analyzed for the content of 16 trace elements (Cr, Mn, Ni, Cu, Zn, and Pb using AAS; Cd by GF-AAS; Hg by the cold vapour method; and V, Co, As, Sr, Mo, Th, and U by XRF) as well as other peat characteristics (peat type, degree of humification, pH and ash content). The results of the research show that concentrations of trace elements in peat are generally low: V 3.8 ± 0.6, Cr 3.1 ± 0.2, Mn 35.1 ± 2.7, Co 0.50 ± 0.05, Ni 3.7 ± 0.2, Cu 4.4 ± 0.3, Zn 10.0 ± 0.7, As 2.4 ± 0.3, Sr 21.9 ± 0.9, Mo 1.2 ± 0.2, Cd 0.12 ± 0.01, Hg 0.05 ± 0.01, Pb 3.3 ± 0.2, Th 0.47 ± 0.05, U 1.3 ± 0.2 μg g - 1 and S 0.25 ± 0.02%. Statistical analyses on these large database showed that Co has the highest positive correlations with many elements and ash content. As, Ni, Mo, ash content and pH are also significantly correlated. The lowest abundance of most trace elements was recorded in mires fed only by precipitation (ombrotrophic), and the highest in mires fed by groundwater and springs (minerotrophic), which are situated in the flood plains of river valleys. Concentrations usually differ between the superficial, middle and bottom peat layers, but the significance decreases depending on the type of mire in the following order: transitional mires - raised bogs - fens. Differences among mire types are highest for the superficial but not significant for the basal peat layers. The use of peat with high concentrations of trace elements in agriculture, horticulture, as fuel, for water purification etc., may pose a risk for humans: via the food chain, through inhalation, drinking water etc.

  13. Lithology and late postglacial stratigraphy of bottom sediments in isolated basins of the White Sea coast exemplified by a small lake in the Chupa settlement area (Northern Karelia)

    NASA Astrophysics Data System (ADS)

    Korsakova, O. P.; Kolka, V. V.; Tolstobrova, A. N.; Lavrova, N. B.; Tolstobrov, D. S.; Shelekhova, T. S.

    2016-05-01

    The complex lithological, geochemical, geochronological, and micropaleontological (diatoms, spores, pollen) investigations of stratified bottom sediments that constitute facies-variable sedimentary sequences in a small isolated lake located near the upper limit of the sea on the White Sea coast made it possible to define lithostratigraphic units (LSU) forming the complete sedimentary succession in deep parts of isolated basins. It is shown that stratigraphy of heterogeneous sequences is determined by two regional transgressive-regressive cycles in relative sea level fluctuations: alternating late Glacial and Holocene transgressions and regressions. The lower part of a clastogenic clayey-sandy-silty sequence successively composed of freshwater (LSU 1) and brackish-water (LSU 2) sediments of the ice-marginal basins and marine postglacial facies (LSU 3) was formed during the late Glacial glacioeustatic marine transgression. Its upper part formed in different isolated basins at different stages of the Holocene is represented depending on its altimetric position on the coastal slope by costal marine sediments (LSU 4) and facies of the partly isolated inlet (LSU 5). The organogenic sapropelic sequence, which overlies sediments of the marine basin and partly isolated bay, corresponds to lithostratigraphic units represented by Holocene sediments accumulated in the meromictic lake (LSU 6), onshore freshwater basin (LSU 7), and freshwater basin with elevated water mineralization (LSU 8) deposited during maximum development of Holocene transgression and lacustrine sediments (LSU 9) formed in coastal environments during terminal phases of the Holocene. The defined lithostratigraphic units differ from each other in lithological, micropaleontological, and geochemical features reflected in structural and textural properties of their sediments, their composition, inclusions, and composition of paleophytocoenoses and diatom assemblages.

  14. Historical Changes in the Ecosystem Condition of a Small Mountain Lake over the Past 60 Years as Revealed by Plankton Remains and Daphnia Ephippial Carapaces Stored in Lake Sediments

    PubMed Central

    Ohtsuki, Hajime; Awano, Tamotsu; Tsugeki, Narumi K.; Ishida, Seiji; Oda, Hirotaka; Makino, Wataru; Urabe, Jotaro

    2015-01-01

    To examine if changes in species composition of a plankton community in the past due to anthropogenic activities can be clarified in lakes without any monitoring data, we analyzed genetically ephippial carapaces of Daphnia with plankton remains stored in the bottom sediments of Lake Hataya Ohunma in Japan. In the lake, abundance of most plankton remains in the sediments was limited and TP flux was at low levels (2–4 mg/m2/y) before 1970. However TP flux increased two-fold during the period from 1980s to 1990s. In parallel with this increase, abundance of most plankton remains increased although abundance of benthic testate amoebae’s remains decreased, indicating that the lake trophic condition had changed from oligo- to mesotrophic for the past 60 years. According to cluster analysis, the stratigraphic sediments were divided into two periods with different features of the phytoplankton composition. Chronological comparison with events in the watershed suggested that eutrophication occurred because of an increase in visitors to the watershed and deposition of atmospheric dust. In this lake more than 50% of resting eggs produced by Daphnia over the past 60 years hatched. However, genetic analysis of the ephippial carapaces (remains) showed that the Daphnia population was originally composed of D. dentifera but that D. galeata, or its hybrid with D. dentifera, invaded and increased the population density when the lake was eutrophied. Subsequently, large D. pulex established populations in the 1980s when largemouth bass were anonymously introduced. These results indicated that the Lake Hataya Ohunma plankton community underwent significant changes despite the fact that there were no notable changes in land cover or land use in the watershed. Since increases in atmospheric deposition and release of fish have occurred in many Japanese lakes, the changes in the plankton community described here may be widespread in these lakes. PMID:25757090

  15. The growth of IQ among Estonian schoolchildren from ages 7 to 19.

    PubMed

    Pullmann, Helle; Allik, Jüri; Lynn, Richard

    2004-11-01

    The Standard Progressive Matrices test was standardized in Estonia on a representative sample of 4874 schoolchildren aged from 7 to 19 years. When the IQ of Estonian children was expressed in relation to British and Icelandic norms, both demonstrated a similar sigmoid relationship. The youngest Estonian group scored higher than the British and Icelandic norms: after first grade, the score fell below 100 and remained lower until age 12, and after that age it increased above the mean level of these two comparison countries. The difference between the junior school children and the secondary school children may be due to schooling, sampling error or different trajectories of intellectual maturation in different populations. Systematic differences in the growth pattern suggest that the development of intellectual capacities proceeds at different rates and the maturation process can take longer in some populations than in others. PMID:15535461

  16. Temperature Trends in Montane Lakes

    NASA Astrophysics Data System (ADS)

    Melack, J. M.; Sadro, S.; Jellison, R.

    2014-12-01

    Long-term temperature trends in lakes integrate hydrological and meteorological factors. We examine temperature trends in a small montane lake with prolonged ice-cover and large seasonal snowfall and in a large saline lake. Emerald Lake, located in the Sierra Nevada (California), is representative of high-elevation lakes throughout the region. No significant trend in outflow temperature was apparent from 1991to 2012. Snowfall in the watershed accounted for 93% of the variability in average summer lake temperatures. Mono Lake (California) lies in a closed, montane basin and is hypersaline and monomictic or meromictic. Temperature profiles have been collected from 1982 to 2010. In the upper water column, the July-August-September water temperatures increased 0.8-1.0°C over the 29 years. This rate of warming is less than published estimates based on satellite-derived skin temperatures and will discussed in the context of general limnological interpretation of temperature trends.

  17. Evaluation of the AnnAGNPS Model for Predicting Runoff and Nutrient Export in a Typical Small Watershed in the Hilly Region of Taihu Lake

    PubMed Central

    Luo, Chuan; Li, Zhaofu; Li, Hengpeng; Chen, Xiaomin

    2015-01-01

    The application of hydrological and water quality models is an efficient approach to better understand the processes of environmental deterioration. This study evaluated the ability of the Annualized Agricultural Non-Point Source (AnnAGNPS) model to predict runoff, total nitrogen (TN) and total phosphorus (TP) loading in a typical small watershed of a hilly region near Taihu Lake, China. Runoff was calibrated and validated at both an annual and monthly scale, and parameter sensitivity analysis was performed for TN and TP before the two water quality components were calibrated. The results showed that the model satisfactorily simulated runoff at annual and monthly scales, both during calibration and validation processes. Additionally, results of parameter sensitivity analysis showed that the parameters Fertilizer rate, Fertilizer organic, Canopy cover and Fertilizer inorganic were more sensitive to TN output. In terms of TP, the parameters Residue mass ratio, Fertilizer rate, Fertilizer inorganic and Canopy cover were the most sensitive. Based on these sensitive parameters, calibration was performed. TN loading produced satisfactory results for both the calibration and validation processes, whereas the performance of TP loading was slightly poor. The simulation results showed that AnnAGNPS has the potential to be used as a valuable tool for the planning and management of watersheds. PMID:26364642

  18. By-products of a former phenol manufacturing site in a small lake adjacent to a Superfund site in the Aberjona watershed.

    PubMed Central

    Wick, L Y; Gschwend, P M

    1998-01-01

    Benzene, diphenyl sulfone (DPS), para-hydroxybiphenyl (PPP), ortho-hydroxybiphenyl (OPP), higher hydroxybiphenyls, and alkylated benzenes were found in a small lake receiving contaminated groundwater discharge from the Industri-Plex Superfund site (Woburn, MA) in the Aberjona watershed in eastern Massachusetts. All of these chemicals may derive from the former phenol manufacturing activities present at the Industri-Plex site during World War I. Concentrations up to 1660 microgram/l benzene, 450 micro/l DPS, 230 microgram/l PPP, and 100 microgram/l OPP were detected in the hypolimnion. Epilimnetic concentrations of the chemicals were significantly lower (normally < 5 microgram/l). DPS showed a distinct seasonal behavior: It was readily biodegradable during warm periods. No biodegradation was observed in the winter, leaving export to the Aberjona River as the major removal mechanism. Although benzene is known to be toxic and a human carcinogen, our results indicate that DPS, OPP, and PPP are not mutagenic in tests using human MCL-5 and h1A1v2 cell lines. Images Figure 1 PMID:9703495

  19. The size-distribution of Earth's lakes.

    PubMed

    Cael, B B; Seekell, D A

    2016-01-01

    Globally, there are millions of small lakes, but a small number of large lakes. Most key ecosystem patterns and processes scale with lake size, thus this asymmetry between area and abundance is a fundamental constraint on broad-scale patterns in lake ecology. Nonetheless, descriptions of lake size-distributions are scarce and empirical distributions are rarely evaluated relative to theoretical predictions. Here we develop expectations for Earth's lake area-distribution based on percolation theory and evaluate these expectations with data from a global lake census. Lake surface areas ≥8.5 km(2) are power-law distributed with a tail exponent (τ = 1.97) and fractal dimension (d = 1.38), similar to theoretical expectations (τ = 2.05; d = 4/3). Lakes <8.5 km(2) are not power-law distributed. An independently developed regional lake census exhibits a similar transition and consistency with theoretical predictions. Small lakes deviate from the power-law distribution because smaller lakes are more susceptible to dynamical change and topographic behavior at sub-kilometer scales is not self-similar. Our results provide a robust characterization and theoretical explanation for the lake size-abundance relationship, and form a fundamental basis for understanding and predicting patterns in lake ecology at broad scales. PMID:27388607

  20. First evidence of successful natural reproduction by planted lake trout in Lake Huron

    USGS Publications Warehouse

    Nester, Robert T.; Poe, Thomas P.

    1984-01-01

    Twenty-two lake trout (Salvelinus namaycush) swim-up fry, 24-27 mm long, were captured with emergent fry traps and a tow net in northwestern Lake Huron on a small nearshore reef off Alpena, Michigan, between May 10 and June 1, 1982. These catches represent the first evidence of successful production of swim-up fry by planted, hatchery-reared lake trout in Lake Huron since the lake trout rehabilitation program began in 1973.

  1. Energy density of lake whitefish Coregonus clupeaformis in Lakes Huron and Michigan

    USGS Publications Warehouse

    Pothoven, S.A.; Nalepa, T.F.; Madenjian, C.P.; Rediske, R.R.; Schneeberger, P.J.; He, J.X.

    2006-01-01

    We collected lake whitefish Coregonus clupeaformis off Alpena and Tawas City, Michigan, USA in Lake Huron and off Muskegon, Michigan USA in Lake Michigan during 2002–2004. We determined energy density and percent dry weight for lake whitefish from both lakes and lipid content for Lake Michigan fish. Energy density increased with increasing fish weight up to 800 g, and then remained relatively constant with further increases in fish weight. Energy density, adjusted for weight, was lower in Lake Huron than in Lake Michigan for both small (≤800 g) and large fish (>800 g). Energy density did not differ seasonally for small or large lake whitefish or between adult male and female fish. Energy density was strongly correlated with percent dry weight and percent lipid content. Based on data from commercially caught lake whitefish, body condition was lower in Lake Huron than Lake Michigan during 1981–2003, indicating that the dissimilarity in body condition between the lakes could be long standing. Energy density and lipid content in 2002–2004 in Lake Michigan were lower than data for comparable sized fish collected in 1969–1971. Differences in energy density between lakes were attributed to variation in diet and prey energy content as well as factors that affect feeding rates such as lake whitefish density and prey abundance.

  2. Competition between larval lake herring (Coregonus artedi) and lake whitefish (Coregonus clupeaformis) for zooplankton

    USGS Publications Warehouse

    Davis, Bruce M.; Todd, Thomas N.

    1998-01-01

    Diet and growth of larval lake herring (Coregonus artedi) and lake whitefish (Coregonus clupeaformis) were compared in mesocosm experiments in a small mesotrophic lake in southeastern Michigan. Fish were sampled from single-species and mixed assemblages in 2-m3 cages for 8 weeks during April and May. Both species initially ate mostly cyclopoid copepodites and small cladocerans (Bosmia spp.). Schoener's index of diet overlap showed considerable overlap (70-90%). Lake whitefish ate Daphnia spp. and adult copepods about 2 weeks earlier than did lake herring, perhaps related to their larger mean mouth gape. Lake whitefish were consistently larger than lake herring until the eighth week, especially in the sympatric treatments. Lake whitefish appeared to have a negative effect on the growth of lake herring, as lake herring in mixed-species treatments were smaller and weighed less than lake herring reared in single-species treatments. The diet similarities of lake whitefish and lake herring larvae could make them competitors for food in the Great Lakes. The greater initial size of lake whitefish could allow them to eat larger prey earlier and thereby limit availability of these prey to lake herring at a crucial period of development.

  3. Whiting in Lake Michigan

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Satellites provide a view from space of changes on the Earth's surface. This series of images from the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) aboard the Orbview-2 satellite shows the dramatic change in the color of Lake Michigan during the summer. The bright color that appears in late summer is probably caused by calcium carbonate-chalk-in the water. Lake Michigan always has a lot of calcium carbonate in it because the floor of the lake is limestone. During most of the year the calcium carbonate remains dissolved in the cold water, but at the end of summer the lake warms up, lowering the solubility of calcium carbonate. As a result, the calcium carbonate precipitates out of the water, forming clouds of very small solid particles that appear as bright swirls from above. The phenomenon is appropriately called a whiting event. A similar event occured in 1999, but appears to have started later and subsided earlier. It is also possible that a bloom of the algae Microcystis is responsible for the color change, but unlikely because of Lake Michigan's depth and size. Microcystis blooms have occured in other lakes in the region, however. On the shore of the lake it is possible to see the cities of Chicago, Illinois, and Milwaukee, Wisconsin. Both appear as clusters of gray-brown pixels. Image courtesy the SeaWiFS Project, NASA/Goddard Space Flight Center, and ORBIMAGE

  4. Yellowstone Lake Nanoarchaeota

    PubMed Central

    Clingenpeel, Scott; Kan, Jinjun; Macur, Richard E.; Woyke, Tanja; Lovalvo, Dave; Varley, John; Inskeep, William P.; Nealson, Kenneth; McDermott, Timothy R.

    2013-01-01

    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. PMID:24062731

  5. Lake Powell

    Atmospheric Science Data Center

    2014-05-15

    article title:  Lake Powell     View Larger Image ... (14.42 mb)   This true-color image over Lake Powell was acquired by Multi-angle Imaging SpectroRadiometer (MISR) in late March 2000. Lake Powell was formed with the construction of the Glen Canyon Dam in 1963, on the ...

  6. CONNECTICUT LAKES

    EPA Science Inventory

    This is a 1:24,000-scale datalayer of named lakes in Connecticut. It is a polygon Shapefile that includes all lakes that are named on the U.S. Geologicial Survey (USGS) 7½ minute topographic quadrangle maps that cover the State of Connecticut, plus other officially named lakes i...

  7. Lake Eyre

    Atmospheric Science Data Center

    2013-04-16

    ...   View Larger Image Lake Eyre is a large salt lake situated between two deserts in one of Australia's driest regions. ... the effect of sunglint at the nadir camera view angle. Dry, salt encrusted parts of the lake appear bright white or gray. Purple areas have ...

  8. Life history of lake herring in Lake Superior

    USGS Publications Warehouse

    Dryer, William R.; Beil, Joseph

    1964-01-01

    The average annual commercial catch of lake herring (Coregonus artedi) in U.S. waters of Lake Superior was nearly 12 million pounds in 1929-61. This production contributed 62.4 percent of the total U.S. take of lake herring for the Great Lakes. About 90 percent of the annual catch is taken from small-mesh gill nets during the November-December spawning season. The life-history studies were based on 12,187 fish collected in 1950-62; past growth was computed for 3,779 specimens collected from commercial landings at: Duluth, Minn.; Bayfield, Wis.; and Portage Entry and Marquette, Mich.

  9. An urban lake remediation experiment

    SciTech Connect

    Castelli, S.E.; Gardner, K.H.; Jennings, A.A.

    1998-07-01

    Circumstances provided the opportunity to study a small urban lake as the surrounding municipalities attempted to improve its aesthetic quality by dredging. This manuscript focuses primarily on the sediments in the system: accumulation rates, the expected dynamics of the lake bed drying process, and the influence of the sediments on water quality.

  10. Tapping rocks for Terror Lake hydro project

    SciTech Connect

    Sieber, O.V.

    1983-12-01

    The Terror Lake hydro project in Alaska is described. Terror Lake is a small alpine lake surrounded by barren glacier-scoured, rocky mountain tops and plateaus that do not retain moisture. The method for obtaining more water for the hydro project in Kodiak is unique. The basic program was to dam up the outlet of Terror Lake and raise the water level 170 ft. from approximately 1250 ft. above sea level to 1420 ft. Although the megawatt output of the project is small, the concept of the Terror Lake Project has an epic scale to it.

  11. Summer depth distribution profiles of dissolved CO2 and O2 in shallow temperate lakes reveal trophic state and lake type specific differences.

    PubMed

    Laas, Alo; Cremona, Fabien; Meinson, Pille; Rõõm, Eva-Ingrid; Nõges, Tiina; Nõges, Peeter

    2016-10-01

    Knowledge about dissolved oxygen (DO) and carbon dioxide (CO2) distribution in lakes has increased considerably over the last decades. However, studies about high resolution dynamics of dissolved CO2 in different types of lakes over daily or weekly time scales are still very scarce. We measured summertime vertical DO and CO2 profiles at sub-hourly intervals during one week in eight Estonian lakes representing different lake types according to European Water Framework Directive. The lakes showed considerable differences in thermal stratification and vertical distribution of dissolved oxygen and CO2 as well as different diurnal dynamics over the measurement period. We observed a continuous CO2 supersaturation in the upper mixed layer of the alkalitrophic (calcareous groundwater-fed) lake and the dark soft-water lake showing them as CO2 emitting "chimneys" although with different underlying mechanisms. In three lake types strong undersaturation with CO2 occurred in the surface layer characterising them as CO2 sinks for the measurement period while in another three types the surface layer CO2 was mostly in equilibrium with the atmosphere. Factor analysis showed that DO% in the surface layer and the strength of its relationship with CO2% were positively related to alkalinity and negatively to trophic state and DOC gradients, whereas deeper lakes were characterised by higher surface concentration but smaller spatial and temporal variability of CO2. Multiple regression analysis revealed lake area, maximum depth and the light attenuation coefficient as variables affecting the largest number of gas regime indicators. We conclude that the trophic status of lakes in combination with type specific features such as morphometry, alkalinity and colour (DOC) determines the distribution and dynamics of dissolved CO2 and DO, which therefore may indicate functional differences in carbon cycling among lakes. PMID:27213672

  12. Spatial patterns of soil organic carbon stocks in Estonian arable soils

    NASA Astrophysics Data System (ADS)

    Suuster, Elsa; Astover, Alar; Kõlli, Raimo; Roostalu, Hugo; Reintam, Endla; Penu, Priit

    2010-05-01

    Soil organic carbon (SOC) determines ecosystem functions, influencing soil fertility, soil physical, chemical and biological properties and crop productivity. Therefore the spatial pattern of SOC stocks and its appropriate management is important at various scales. Due to climate change and the contribution of carbon store in the soils, the national estimates of soil carbon stocks should be determined. Estonian soils have been well studied and mapped at a scale 1:10,000. Previous studies have estimated SOC stocks based on combinations of large groups of Estonian soils and the mean values of the soil profile database, but were not embedded into the geo-referenced databases. These studies have estimated SOC stocks of Estonian arable soils 122.3 Tg. Despite of available soil maps and databases, this information is still very poorly used for spatial soil modelling. The aim of current study is to assess and model spatial pattern of SOC stocks of arable soils on a pilot area Tartu County (area 3089 sq km). Estonian digital soil map and soil monitoring databases are providing a good opportunity to assess SOC stocks at various scales. The qualitative nature of the initial data from a soil map prohibits any straightforward use in modelling. Thus we have used several databases to construct models and linkages between soil properties that can be integrated into soil map. First step was to reorganize the soil map database (44,046 mapping units) so it can be used as an input to modelling. Arable areas were distinguished by a field layer of Agricultural Registers and Information Board, which provides precise information of current land use as it is the basis of paying CAP subsidies. The estimates of SOC content were found by using the arable land evaluation database of Tartu from the Estonian Land Board (comprising 950 sq km and 31,226 fields), where each soil type was assessed separately and average SOC content grouped by texture was derived. SOC content of epipedon varies in

  13. Assessment of Early Postpartum Reproductive Performance in Two High Producing Estonian Dairy Herds

    PubMed Central

    Kask, K; Kurykin, J; Lindjärv, R; Kask, A; Kindahl, H

    2003-01-01

    Early postpartum (6 weeks) ovarian activity, hormonal profiles, uterine involution, uterine infections, serum electrolytes, glucose, milk acetoacetate and blood urea nitrogen (BUN) levels were studied in 2 Estonian high producing dairy herd with annual milk production of 7688 (Farm A) and 9425 (Farm B). From each farm 10 cows, with normal calving performance were used. Blood samples for the hormonal (PGF2α-metabolite, progesterone) analyses were withdrawn. On day 25 PP blood serum samples were taken for the evaluation of metabolic/electrolyte status. On the same day estimation of milk acetoacetate values was done. The ultrasound (US) was started on day 7 PP and was performed every 3rd day until the end of experiment. Uterine content, follicular activity and sizes of the largest follicle and corpus luteum were monitored and measured. Vaginal discharge and uterine tone were recorded during the rectal palpation. Each animal in the study was sampled for bacteriological examination using endometrial biopsies once a week. Two types of PGF2α-metabolite patterns were detected: elevated levels during 14 days PP, then decline to the basal level and then a second small elevation at the time of final elimination of the bacteria from the uterus; or elevated levels during first 7 days PP, then decline to the basal level and a second small elevation before the final elimination of bacteria. Endometritis was diagnosed in 5 cows in farm A and in 3 cows in farm B respectively. In farm A, 5 cows out of 10 ovulated during experimental period and in 1 cow cystic ovaries were found. In farm B, 3 cows out of 10 ovulated. In 3 cows cystic ovaries were found. Altogether 40% of cows had their first ovulation during the experimental period. Three cows in farm A and 5 cows in farm B were totally bacteria negative during the experimental period. The most frequent bacteria found were A. pyogenes, Streptococcus spp., E. coli., F. necrophorum and Bacteroides spp. The highest incidence of

  14. Big Project, Small Leaders

    ERIC Educational Resources Information Center

    Schon, Jennifer A.; Eitel, Karla B.; Bingaman, Deirdre; Miller, Brant G.; Rittenburg, Rebecca A.

    2014-01-01

    Donnelly, Idaho, is a small town surrounded by private ranches and Forest Service property. Through the center of Donnelly runs Boulder Creek, a small tributary feeding into Cascade Lake Reservoir. Boulder Creek originates from a mountain lake north of Donnelly. Since 1994 it has been listed as "impaired" by the Environmental Protection…

  15. Field trial on glucose-induced insulin and metabolite responses in Estonian Holstein and Estonian Red dairy cows in two herds

    PubMed Central

    2010-01-01

    Background Insulin secretion and tissue sensitivity to insulin is considered to be one of the factors controlling lipid metabolism post partum. The objective of this study was to compare glucose-induced blood insulin and metabolite responses in Estonian Holstein (EH, n = 14) and Estonian Red (ER, n = 14) cows. Methods The study was carried out using the glucose tolerance test (GTT) performed at 31 ± 1.9 days post partum during negative energy balance. Blood samples were obtained at -15, -5, 5, 10, 20, 30, 40, 50 and 60 min relative to infusion of 0.15 g/kg BW glucose and analysed for glucose, insulin, triglycerides (TG), non-esterified fatty acids (NEFA), cholesterol and β-hydroxybutyrate (BHB). Applying the MIXED Procedure with the SAS System the basal concentration of cholesterol, and basal concentration and concentrations at post-infusion time points for other metabolites, area under the curve (AUC) for glucose and insulin, clearance rate (CR) for glucose, and maximum increase from basal concentration for glucose and insulin were compared between breeds. Results There was a breed effect on blood NEFA (P < 0.05) and a time effect on all metabolites concentration (P < 0.01). The following differences were observed in EH compared to ER: lower blood insulin concentration 5 min after glucose infusion (P < 0.05), higher glucose concentration 20 (P < 0.01) and 30 min (P < 0.05) after infusion, and higher NEFA concentration before (P < 0.01) and 5 min after infusion (P < 0.05). Blood TG concentration in ER remained stable, while in EH there was a decrease from the basal level to the 40th min nadir (P < 0.01), followed by an increase to the 60th min postinfusion (P < 0.01). Conclusion Our results imply that glucose-induced changes in insulin concentration and metabolite responses to insulin differ between EH and ER dairy cows. PMID:20089161

  16. A stochastic model for the sea level in the Estonian coastal area

    NASA Astrophysics Data System (ADS)

    Raudsepp, Urmas; Toompuu, Aleksander; Kõuts, Tarmo

    1999-09-01

    A stochastic model is suggested to perform the space-time optimal analysis of the sea level data recorded in 1978-1982 at 20 stations at the Estonian coast and along a part of the Latvian coast surrounding the Gulf of Riga. The original time series recorded with the time lag of 1, 6 or 12 h are divided into mean and fluctuation components. The mean field is modeled as the sum of the linear trend and annual harmonic. The mean sea level is generally higher at the stations located in the river mouth area. The estimated linear trend yielding the sea level rise of 1-3 cm/year is an approximation of the interannual variability over the selected 5-year period. The dominating annual harmonic with amplitude of 20 cm describes 40-45% of the total variability of the time series of the monthly mean sea level values. The temporal and spatial correlations of the sea level fluctuation field were estimated on the basis of the suggested stochastic model. The correlation functions were approximated by Gaussian functions yielding the temporal correlation radius (e-folding scale) of about 10 days and spatial correlation radius of 200-400 nm. According to the developed criterion, proceeding from the suggested stochastic model, at least 90% of the sea level data from the Estonian coastal area should be considered as meeting the quality requirements. There was no significant difference in the quality of data measured either continuously by mareographs or observed by reading the bench sticks. After removal of outliers, the approach was utilized to reconstruct the sea level field in the Estonian coastal area in 1978-1982 with an acceptable low reconstruction error.

  17. Reconstructing the ecological impacts of eight decades of mining, metallurgical, and municipal activities on a small boreal lake in northern Canada.

    PubMed

    Doig, Lorne E; Schiffer, Stephanie T; Liber, Karsten

    2015-07-01

    As a result of long-term metal mining and metallurgical activities, the sediment of Ross Lake (Flin Flon, MB, Canada) is highly contaminated with metals and other elements. Although the effluents likely were discharged into Ross Lake as early as the late 1920s, lake biophysical data were not collected until 1973, more than 4 decades after the onset of mining and municipal activities. The early influence of these activities on the ecology of Ross Lake is unknown, as are the effects of improvements to metallurgical effluent quality and discontinuation of municipal wastewater discharge into the lake's north basin. To address this knowledge gap, analyses typical of paleolimnological investigations were applied to cores of sediment collected in 2009 from the south basin of Ross Lake. Stratigraphic analyses of physicochemical sediment characteristics (e.g., the concentrations of metals and other elements, organic C, total N, and δ(13)C and δ(15)N values) and subfossil remains (diatoms, Chironomidae, Chaoborus, and Cladocera) were used to infer historical biological and chemical changes in Ross Lake. With the onset of mining activities, concentrations of various elements (e.g., As, Cr, Cu, Zn, and Se) increased dramatically in the sediment profile, eventually declining with improved tailings management. Nevertheless, concentrations of metals in recent sediments remain elevated compared with pre-industrial sediments. Constrained cluster analyses demonstrated distinct pre-industrial and postindustrial communities for both the diatoms and chironomids. The biodiversity of the postindustrial diatom assemblages were much reduced compared with the pre-industrial assemblages. The postindustrial chironomid assemblage was dominated by Chironomus and to a lesser extent by Procladius, suggesting that Ross Lake became a degraded environment. Abundances of Cladocera and Chaoborus were severely reduced in the postindustrial era, likely because of metals toxicity. Overall, improvements

  18. Factors Affecting Elevated Arsenic and Methyl Mercury Concentrations in Small Shield Lakes Surrounding Gold Mines near the Yellowknife, NT, (Canada) Region.

    PubMed

    Houben, Adam James; D'Onofrio, Rebecca; Kokelj, Steven V; Blais, Jules M

    2016-01-01

    Gold mines in the Yellowknife, NT, region--in particular, the Giant Mine--operated from 1949-99, releasing 237,000 tonnes of waste arsenic trioxide (As2O3) dust, among other compounds, from gold ore extraction and roasting processes. For the first time, we show the geospatial distribution of roaster-derived emissions of several chemical species beyond the mine property on otherwise undisturbed taiga shield lakes within a 25 km radius of the mine, 11 years after its closing. Additionally, we demonstrate that underlying bedrock is not a significant source for the elevated concentrations in overlying surface waters. Aquatic arsenic (As) concentrations are well above guidelines for drinking water (10 μg/L) and protection for aquatic life (5 μg/L), ranging up to 136 μg/L in lakes within 4 km from the mine, to 2.0 μg/L in lakes 24 km away. High conversion ratios of methyl mercury were shown in lakes near the roaster stack as well, with MeHg concentrations reaching 44% of total mercury. The risk of elevated exposures by these metals is significant, as many lakes used for recreation and fishing near the City of Yellowknife are within this radius of elevated As and methyl Hg concentrations. PMID:27050658

  19. Factors Affecting Elevated Arsenic and Methyl Mercury Concentrations in Small Shield Lakes Surrounding Gold Mines near the Yellowknife, NT, (Canada) Region

    PubMed Central

    Houben, Adam James; D’Onofrio, Rebecca; Kokelj, Steven V; Blais, Jules M

    2016-01-01

    Gold mines in the Yellowknife, NT, region—in particular, the Giant Mine—operated from 1949–99, releasing 237,000 tonnes of waste arsenic trioxide (As2O3) dust, among other compounds, from gold ore extraction and roasting processes. For the first time, we show the geospatial distribution of roaster-derived emissions of several chemical species beyond the mine property on otherwise undisturbed taiga shield lakes within a 25 km radius of the mine, 11 years after its closing. Additionally, we demonstrate that underlying bedrock is not a significant source for the elevated concentrations in overlying surface waters. Aquatic arsenic (As) concentrations are well above guidelines for drinking water (10 μg/L) and protection for aquatic life (5 μg/L), ranging up to 136 μg/L in lakes within 4 km from the mine, to 2.0 μg/L in lakes 24 km away. High conversion ratios of methyl mercury were shown in lakes near the roaster stack as well, with MeHg concentrations reaching 44% of total mercury. The risk of elevated exposures by these metals is significant, as many lakes used for recreation and fishing near the City of Yellowknife are within this radius of elevated As and methyl Hg concentrations. PMID:27050658

  20. Modernizing the Estonian farmhouse, redefining the family, 1880s-1930s.

    PubMed

    L'Heureux, Marie-Alice

    2010-01-01

    In the nineteenth century, the transition from a Baltic-German-controlled manor-and-serf economy to individually owned farmsteads transformed all aspects of life including the spatial organization and form of farmhouses in the western provinces of Tsarist Russia. Agricultural experts and social reformers discussed how to update the traditional threshing-room dwelling house (rehielamu) into a healthy dwelling for successful farmers and, after the Estonian War of Independence, for new settlers. Using material culture such as contemporary plans, I show that changing household relationships, in addition to economic and technological factors, helped to transform the ancient rehielamu into a modern dwelling. PMID:21280384

  1. Analyzing Sustainable Energy Opportunities for a Small Scale Off-Grid Facility: A Case Study at Experimental Lakes Area (ELA), Ontario

    NASA Astrophysics Data System (ADS)

    Duggirala, Bhanu

    This thesis explored the opportunities to reduce energy demand and renewable energy feasibility at an off-grid science "community" called the Experimental Lakes Area (ELA) in Ontario. Being off-grid, ELA is completely dependent on diesel and propane fuel supply for all its electrical and heating needs, which makes ELA vulnerable to fluctuating fuel prices. As a result ELA emits a large amount of greenhouse gases (GHG) for its size. Energy efficiency and renewable energy technologies can reduce energy consumption and consequently energy cost, as well as GHG. Energy efficiency was very important to ELA due to the elevated fuel costs at this remote location. Minor upgrades to lighting, equipment and building envelope were able to reduce energy costs and reduce load. Efficient energy saving measures were recommended that save on operating and maintenance costs, namely, changing to LED lights, replacing old equipment like refrigerators and downsizing of ice makers. This resulted in a 4.8% load reduction and subsequently reduced the initial capital cost for biomass by 27,000, by 49,500 for wind power and by 136,500 for solar power. Many alternative energies show promise as potential energy sources to reduce the diesel and propane consumption at ELA including wind energy, solar heating and biomass. A biomass based CHP system using the existing diesel generators as back-up has the shortest pay back period of the technologies modeled. The biomass based CHP system has a pay back period of 4.1 years at 0.80 per liter of diesel, as diesel price approaches $2.00 per liter the pay back period reduces to 0.9 years, 50% the generation cost compared to present generation costs. Biomass has been successfully tried and tested in many off-grid communities particularly in a small-scale off-grid setting in North America and internationally. Also, the site specific solar and wind data show that ELA has potential to harvest renewable resources and produce heat and power at competitive

  2. Energy and the environment in the Baltic Sea region: A study of cooperative action from the Estonian perspective

    NASA Astrophysics Data System (ADS)

    Brauer, Alex P.

    Due to their geographic proximity and shared natural resources, cooperation on energy-related and environmental issues is particularly important for the nine countries surrounding the Baltic Sea. Currently, two projects are underway that have placed the level of cooperation within the region under the microscope: the environmental management work undertaken by the Helsinki Commission for the Convention on the Protection of the Marine Environment of the Baltic Sea Area (HELCOM) and the Nord Stream pipeline project, which, when completed, will provide the direct transportation of natural gas from Russia to Germany via the Baltic seafloor. Although both have been declared inclusive and decidedly Baltic ventures by some regional actors, reception of the cooperative efforts amongst the littoral Baltic countries has been markedly different. This study addresses these varying reactions by examining Estonia's participation in and subsequent perspectives on the HELCOM and Nord Stream projects. A theoretical framework grounded in the discipline of international relations is utilized to analyze Estonia's role in the projects and its position as a small state in a regional context. The primary areas of focus are how historical experiences and current levels of cooperation in the two endeavors have shaped Estonia's responses and, ultimately, its 'realist' perception of global politics. The study concludes that Estonia appears to have more substantive participation in HELCOM than in the Nord Stream project because of the tendency of states to securitize and, thus, prioritize the energy policy area over the environmental. Estonian foreign policy behavior, however, perpetuates the state-centric and power-centered policy processes that dominate the international political system.

  3. LAKE RESTORATION: A FIVE-YEAR EVALUATION OF THE MIRROR AND SHADOW LAKES PROJECT WAUPACA, WISCONSIN

    EPA Science Inventory

    Mirror and Shadow Lakes, small seepage lakes in central Wisconsin, had experienced cultural eutrophication as a result of storm water drainage. Storm sewers were diverted from the lakes in 1976 and in 1978 aluminum sulfate was applied to enhance the recovery rate by reducing inte...

  4. Proficiency Assessment of Male Volleyball Teams of the 13-15-Year Age Group at Estonian Championships

    ERIC Educational Resources Information Center

    Stamm, Meelis; Stamm, Raini; Koskel, Sade

    2008-01-01

    Study aim: Assessment of feasibility of using own computer software "Game" at competitions. Material and methods: The data were collected during Estonian championships in 2006 for male volleyball teams of the 13-15-years age group (n = 8). In all games, the performance of both teams was recorded in parallel with two computers. A total of 19 games…

  5. The Anonymity of Catalan and the Authenticity of Estonian: Two Paths for the Development of Medium-Sized Languages

    ERIC Educational Resources Information Center

    Soler, Josep

    2013-01-01

    Catalan and Estonian can be considered "medium-sized" languages with some key common features that allow us to analyze the evolution of the two cases comparatively. Firstly, other formerly hegemonic languages (Spanish and Russian, respectively) have historically minoritized them. Secondly, the political equilibrium has now changed in such a way…

  6. University Language Policies and Language Choice among Ph.D. Graduates in Estonia: The (Unbalanced) Interplay between English and Estonian

    ERIC Educational Resources Information Center

    Soler-Carbonell, Josep

    2014-01-01

    The role of English as a global language and its consequences for the internationalization of higher education are matters that have increasingly drawn the attention of researchers from different fields of language and communication. In this paper, an overview of the situation in Estonia is presented. The Estonian context has not previously been…

  7. Exploring Constructivist Social Learning Practices in Aiding Russian-Speaking Teachers to Learn Estonian: An Action Research Approach

    ERIC Educational Resources Information Center

    Kiilo, Tatjana; Kutsar, Dagmar

    2012-01-01

    Based on appreciative inquiry and threshold concepts from an intercultural learning perspective, the article makes insights into the constructivist social learning practice of Estonian language learning amongst Russian-speaking teachers in Estonia. The application of educational action research methodology, more specifically that of Bridget…

  8. Normal Weight Estonian Prepubertal Boys Show a More Cardiovascular-Risk-Associated Adipose Tissue Distribution than Austrian Counterparts

    PubMed Central

    Wallner-Liebmann, Sandra J.; Moeller, Reinhard; Horejsi, Renate; Jürimäe, Toivo; Jürimäe, Jaak; Mäestu, Jarek; Purge, Priit; Saar, Meeli; Tafeit, Erwin; Kaimbacher, Petra; Kruschitz, Renate; Weghuber, Daniel; Schnedl, Wolfgang J.; Mangge, Harald

    2013-01-01

    Objective. Risk phenotypes for cardiovascular disease (CVD) differ markedly between countries, like the reported high difference in CVD mortality in Austria and Estonia. Hitherto, the goal of this study was to find out risk profiles in body fat distribution yet present in childhood, paving the way for later clinical end points. Methods. he subcutaneous adipose tissue (SAT) distribution patterns in 553 Austrian (A) and Estonian (E) clinically healthy normal weight boys aged 11.1 (±0.8) years were analysed. We applied the patented optical device Lipometer which determines the individual subcutaneous adipose tissue topography (SAT-Top). Results. Total body fat did not differ significantly between E and A boys. A discriminant analysis using all Lipometer data, BMI, and the total body fat (TBF) yielded 84.6% of the boys correctly classified in Estonians and Austrians by 9 body sites. A factor analysis identified the SAT distribution of E as critically similar to male adult patients with coronary heart disease (CHD). Conclusions. We show in normal weight Estonian boys a highly significant decreased fat accumulation on the lower body site compared to age matched Austrian males. This SAT-Top phenotype may play an important role for the increased cardiovascular risk seen in the Estonian population. PMID:24555148

  9. Eutrophication of the St. Lawrence Great Lakes

    USGS Publications Warehouse

    Beeton, Alfred M.

    1965-01-01

    Lakes Huron, Michigan, and Superior are classified as oligotrophic lakes on the basis of their biological, chemical, and physical characteristics. Lake Ontario, although rich in nutrients, is morphometrically oligotrophic or mesotrophic because of its large area of deep water. Lake Erie, the most productive of the lakes and the shallowest, is eutrophic. Several changes commonly associated with eutrophication in small lakes have been observed in the Great Lakes. These changes apparently reflect accelerated eutrophication in the Great Lakes due to man's activity. Chemical data compiled from a number of sources, dating as early as 1854, indicate a progressive increase in the concentrations of various major ions and total dissolved solids in all of the lakes except Lake Superior. The plankton has changed somewhat in Lake Michigan and the plankton, benthos, and fish populations of Lake Erie are greatly different today from those of the past. An extensive area of hypolimnetic water of Lake Erie has developed low dissolved oxygen concentrations in late summer within recent years.

  10. Lake Constance

    Atmospheric Science Data Center

    2013-04-17

    ... Swiss shores of Lake Constance at the town of Rorschach. Eutrophication, or the process of nutrient enrichment, is rapidly accelerated ... of the value of Lake Constance, efforts to mitigate eutrophication were initiated in the 1970's. MISR was built and is managed ...

  11. LAKE FORK

    EPA Science Inventory

    The Lake Fork of the Arkansas River Watershed has been adversely affected through mining, water diversion and storage projects, grazing, logging, and other human influences over the past 120 years. It is the goals of the LFWWG to improve the health of Lake fork by addressing th...

  12. Small-dam rehabs

    SciTech Connect

    Denning, J.

    1993-01-01

    This article examines the economics of maintenance, rehabilitation and improvement for small, aging, high-hazard dams. The topics of the article include raising the height of the spillway and repairing deteriorated concrete in the spillway of Fellows Lake Dam, emergency repair of the outlet conduit and replacement of riprap on the upstream slope of Storrie Lake Dam, and extensive rehabilitation of Reeves Lake Dam.

  13. The Ambrosia Lake project archaeological investigations of three small sites associated with the southern Chacoan outlier of Kin Nizhoni, McKinley County, New Mexico

    SciTech Connect

    Cullington, B.J.; Hammack, L.C.; Baugh, T.G.

    1990-03-15

    During the fall of 1987, Complete Archaeological Service Associates conducted mitigative excavations at three sites (LA50363, LA50364, and LA50371) in McKinley County, New Mexico. These sites are adjacent to the Phillips/United Nuclear Inactive Uranium Mill and Tailings site at Ambrosia Lake, New Mexico. The primary deposition at each of these sites appears to be related to a Pueblo II or Bonito Phase occupation. Temporal placement is based primarily on the cross dating of ceramics and archaeomagnetic determinations when possible. No tree-ring or radiocarbon samples are available from these sites. These Ambrosia Lake sites indicate that this area was occupied primarily by Pueblo II people who may have had close social, economic, and ceremonial ties with the people living at the nuclear community of Lower Nizhoni about 3 km south-southeast. The later component at LA50364 indicates a Pueblo III occupation by people who may have had similar ties to the people of the Kin Nizhoni nuclear community. The Ambrosia Lake sites, then, provide important information on the structure of subnuclear communities within the southern Chaco periphery.

  14. Heat-Wave Effects on Oxygen, Nutrients, and Phytoplankton Can Alter Global Warming Potential of Gases Emitted from a Small Shallow Lake.

    PubMed

    Bartosiewicz, Maciej; Laurion, Isabelle; Clayer, François; Maranger, Roxane

    2016-06-21

    Increasing air temperatures may result in stronger lake stratification, potentially altering nutrient and biogenic gas cycling. We assessed the impact of climate forcing by comparing the influence of stratification on oxygen, nutrients, and global-warming potential (GWP) of greenhouse gases (the sum of CH4, CO2, and N2O in CO2 equivalents) emitted from a shallow productive lake during an average versus a heat-wave year. Strong stratification during the heat wave was accompanied by an algal bloom and chemically enhanced carbon uptake. Solar energy trapped at the surface created a colder, isolated hypolimnion, resulting in lower ebullition and overall lower GWP during the hotter-than-average year. Furthermore, the dominant CH4 emission pathway shifted from ebullition to diffusion, with CH4 being produced at surprisingly high rates from sediments (1.2-4.1 mmol m(-2) d(-1)). Accumulated gases trapped in the hypolimnion during the heat wave resulted in a peak efflux to the atmosphere during fall overturn when 70% of total emissions were released, with littoral zones acting as a hot spot. The impact of climate warming on the GWP of shallow lakes is a more complex interplay of phytoplankton dynamics, emission pathways, thermal structure, and chemical conditions, as well as seasonal and spatial variability, than previously reported. PMID:27266257

  15. The size-distribution of Earth’s lakes

    NASA Astrophysics Data System (ADS)

    Cael, B. B.; Seekell, D. A.

    2016-07-01

    Globally, there are millions of small lakes, but a small number of large lakes. Most key ecosystem patterns and processes scale with lake size, thus this asymmetry between area and abundance is a fundamental constraint on broad-scale patterns in lake ecology. Nonetheless, descriptions of lake size-distributions are scarce and empirical distributions are rarely evaluated relative to theoretical predictions. Here we develop expectations for Earth’s lake area-distribution based on percolation theory and evaluate these expectations with data from a global lake census. Lake surface areas ≥8.5 km2 are power-law distributed with a tail exponent (τ = 1.97) and fractal dimension (d = 1.38), similar to theoretical expectations (τ = 2.05 d = 4/3). Lakes <8.5 km2 are not power-law distributed. An independently developed regional lake census exhibits a similar transition and consistency with theoretical predictions. Small lakes deviate from the power-law distribution because smaller lakes are more susceptible to dynamical change and topographic behavior at sub-kilometer scales is not self-similar. Our results provide a robust characterization and theoretical explanation for the lake size-abundance relationship, and form a fundamental basis for understanding and predicting patterns in lake ecology at broad scales.

  16. The size-distribution of Earth’s lakes

    PubMed Central

    Cael, B. B.; Seekell, D. A.

    2016-01-01

    Globally, there are millions of small lakes, but a small number of large lakes. Most key ecosystem patterns and processes scale with lake size, thus this asymmetry between area and abundance is a fundamental constraint on broad-scale patterns in lake ecology. Nonetheless, descriptions of lake size-distributions are scarce and empirical distributions are rarely evaluated relative to theoretical predictions. Here we develop expectations for Earth’s lake area-distribution based on percolation theory and evaluate these expectations with data from a global lake census. Lake surface areas ≥8.5 km2 are power-law distributed with a tail exponent (τ = 1.97) and fractal dimension (d = 1.38), similar to theoretical expectations (τ = 2.05; d = 4/3). Lakes <8.5 km2 are not power-law distributed. An independently developed regional lake census exhibits a similar transition and consistency with theoretical predictions. Small lakes deviate from the power-law distribution because smaller lakes are more susceptible to dynamical change and topographic behavior at sub-kilometer scales is not self-similar. Our results provide a robust characterization and theoretical explanation for the lake size-abundance relationship, and form a fundamental basis for understanding and predicting patterns in lake ecology at broad scales. PMID:27388607

  17. [The resistance status of gastrointestinal strongyles against anthelmintics in three Estonian sheep flocks].

    PubMed

    Anupöld, Ann Mari; Hinney, Barbara; Joachim, Anja

    2014-01-01

    Poor efficacy of anthelmintic drugs in sheep due to infections with resistant gastrointestinal strongyles is reported worldwide. The aim of this pilot study was to gain an insight into the current situation of anthelmintic efficacy in Estonian sheep flocks. From September to November 2012, faecal egg count reduction tests (FECRT) were carried out in three Estonian sheep farms, evaluating the efficacy of albendazole and ivermectin. Individual faecal samples were taken at the day of treatment and 10 to 14 days later and examined by a modified McMaster technique. Anthelmintic treatment was carried out with ivermectin (Bimectin 10 mg/ml, Bimeda Chemicals Export) subcutaneously with a dose rate of 0.2 mg/kg of body weight in the IVM group (n = 20 animals/farms 1 and 2; n = 5 for farm 3) or albendazol (Endospec 10%, Bimeda Chemicals Export) orally in the dose of 5 mg/kg of body weight in the ALB group (n = 20 animals/ farm); animals in the control group (n = 20 animals for farms 1 and 3, n = 18 for farm 2) were left untreated. The FECRT was carried out according to the WAAVP guidelines. On farm 1 the efficacy of albendazole and ivermectin was reduced with 66% and 65% FECR, respectively. With a FECR of 26% the results of farm 2 showed a pronounced albendazole resistance while ivermectin was still sufficiently efficient (99% reduction). Farm 3 showed nearly 100% efficacy of albendazole and ivermectin, but earlier problems with high endoparasite burden and mortality may indicate a possible developing albendazole resistance which could not be detected with the FECRT yet. The results of this study show that in Estonia resistance against benzimidazoles and macrocyclic lactones does occur, indicating that close countrywide monitoring is advisable. PMID:24490343

  18. Earthquake-dammed lakes in New Zealand

    SciTech Connect

    Adams, J.

    1981-05-01

    Eleven small lakes were formed by landslides caused by the 1929 Buller earthquake; four others were formed by other historic earthquakes in New Zealand. At least nine other New Zealand lakes are also dammed by landslides and were probably formed by prehistoric earthquakes. When recognized by morphology, synchronous age, and areal distribution, earthquake-dammed lakes could provide an estimate of paleoseismicity for the past few hundred or thousand years.

  19. Effects of storm-water runoff on an urban lake, Lake Ellyn at Glen Ellyn, Illinois

    USGS Publications Warehouse

    Striegl, R.G.

    1985-01-01

    Detention of urban runoff was observed to have physical, chemical, and biological effects on a small lake located near Chicago, Illinois. Accumulated bottom sediments reduce lake storage and have comparatively high concentrations of metals and organic compounds. Concentrations of many constituents dissolved in the lake water are seasonally cyclic, with annual concentration peaks occurring during the winter. Maintenance of desirable benthic invertebrate and fish communities, and development of undesirable phytoplankton blooms appear to be inhibited by sediments deposited on the lake bottom and suspended in the lake water. (USGS)

  20. Water quality of selected lakes in Mount Rainier National Park, Washington, with respect to lake acidification

    SciTech Connect

    Turney, G.L.; Dion, N.P.; Sumioka, S.S.

    1986-01-01

    Thirteen lakes in Mount Rainier National park were evaluated for general chemical characteristics, sensitivity to acidification by acidic precipitation, and degree of existing acidification. The lakes studies were Allen, one of the Chenuis group, Crescent, Crystal, Eleanor, Fan, one of the Golfen group, Marsh, Mowich, Mystic, Shriner, and two unnamed lakes. The lakes were sampled in August 1983. The major cations were calcium and sodium, and the major anion was bicarbonate. Alkalinity concentrations ranged from 2.1 to 9.0 mg/L in 12 of the lakes. Allen Lake was the exception, having an alkalinity concentration of 27 mg/L. The pH values for all of the lakes ranged from 5.8 to 6.5. In most of the lakes, vertical profiles of temperature, dissolved oxygen, pH, and specific conductance were relatively uniform. Exceptions to general water quality patterns were observed in three lakes. Allen Lake had a specific conductance value of 58 Microsiemens/cm. The lake of the Golfen group was anaerobic at the bottom and had relatively high concentrations of dissolved organic carbon and dissolved metals, and a lower light transmission than the other lakes studied. One of the unnamed lakes had relatively high concentrations of phytoplankton and dissolved organic carbon and relatively low levels of light transmission. Comparisons of lake data to acid-sensitivity thresholds for specific conductance and alkalinity indicated that all of the lakes except Allen would be sensitive to acidic precipitation. The small sizes of the lakes, and their locations in basins of high precipitation and weathering-resistant rock types, enhance their sensitivity. None of the lakes in this study appeared to be presently acidified.

  1. Lake trout demographics in relation to burbot and coregonine populations in the Algonquin Highlands, Ontario

    USGS Publications Warehouse

    Carl, L.M.

    2008-01-01

    The objective of the study was to test the hypothesis that lake trout populations change in relation to cisco, lake whitefish, round whitefish and burbot populations in lakes in the Algonquin Highlands region of Ontario. Lake trout population change is greatest where cisco and lake whitefish are present. Lake trout populations in lakes without either coregonine tend to have small adults and many juveniles. Where cisco or lake whitefish are present, adult lake trout are large, juvenile abundance is low, and the stock-recruit relationship appears to be uncoupled likely due to a larval bottleneck. Lake trout populations in these lakes may be sensitive to overfishing and recruitment failure. Lake trout populations do not appear to change in relation to round whitefish. There appears to be an indirect positive change on juvenile lake trout abundance through reductions in the density of benthic coregonines in the presence of large, hypolimnetic burbot. ?? 2007 Springer Science+Business Media B.V.

  2. Lake Powell

    NASA Technical Reports Server (NTRS)

    2007-01-01

    The white ring around Lake Powell tells the story. The surface is down 98 feet. This is critical, because Powell, Lake Mead, and other lakes along the Colorado River provide water for millions of people in five states. We are in the eighth year of a drought on the Colorado River. This year was the driest year ever reported in Southern California, and there is a severe drought in Northern California, down to less than 30-percent of snow pack. This ASTER image of part of Lake Powell was acquired in 2001. The gray area depicts the shrunken, reduced 2007 lake extent compared to the extended, larger black area in 2001.

    The image covers an area of 24 x 30 km, and is centered near 37.1 degrees north latitude, 111.3 degrees west longitude.

    The U.S. science team is located at NASA's Jet Propulsion Laboratory, Pasadena, Calif. The Terra mission is part of NASA's Science Mission Directorate.

  3. The Stability of Lava Lakes

    NASA Astrophysics Data System (ADS)

    Witham, F.; Llewellin, E. W.; Woods, A. W.; Gladstone, C.

    2007-12-01

    Lava lakes may exhibit complex cycles of filling and draining on time-scales of hours to weeks. Such activity is recorded at Pu`u `O`o, Hawai`i. Other examples, e.g. Erta Ale in Ethiopia, do not display these draining episodes; instead an 'equilibrium' system is observed in which the lake may persist for years. We present the results of a theoretical and experimental investigation of lava lakes and identify behavioural regimes distinguished by system geometry and gas content. Laboratory analogue modelling shows that even a simple conduit-lake system, driven by a constant gas flux, can display steady-state equilibrium or cyclic behaviour, depending on the rate of gas flux. A theoretical approach to the same system captures this range of behaviour. By testing the stability of an 'equilibrium' lake to small perturbations, we show that the degree of stability is controlled by the ratio of conduit to lake areas, and the gas volume fraction at the top of the conduit. Despite the simplicity of the modelled system, a rich spectrum of behaviour is found. The model predicts that a stable system must drain over time. This implies that lakes which exhibit ongoing degassing for years or decades (e.g. Erta Ale) either must have an exogenous supply of gas bubbles from depth, or an effective conduit convection mechanism must exist.

  4. Estonian waterworks treatment plants: clearance of residues, discharge of effluents and efficiency of removal of radium from drinking water.

    PubMed

    Trotti, F; Caldognetto, E; Forte, M; Nuccetelli, C; Risica, S; Rusconi, R

    2013-12-01

    Considerable levels of radium were detected in a certain fraction of the Estonian drinking water supply network. Some of these waterworks have treatment systems for the removal of (mainly) iron and manganese from drinking water. Three of these waterworks and another one equipped with a radium removal pilot plant were examined, and a specific study was conducted in order to assess the environmental compatibility of effluents and residues produced in the plants. (226)Ra and (228)Ra activity concentrations were analysed in both liquid (backwash water) and solid (sand filter and sediment) materials to evaluate their compliance, from the radiological point of view, with current Estonian legislation and international technical documents that propose reference levels for radium in effluents and residues. Also with regard to water treatment by-products, a preliminary analysis was done of possible consequences of the transposition of the European Basic Safety Standards Draft into Estonian law. Radium removal efficiency was also tested in the same plants. Iron and manganese treatment plants turned out to be scarcely effective, whilst the radium mitigation pilot plant showed a promising performance. PMID:24047590

  5. Levels of benzo(a)pyrene in oil shale industry wastes, some bodies of water in the Estonian S.S.R. and in water organisms.

    PubMed Central

    Veldre, I A; Itra, A R; Paalme, L P

    1979-01-01

    Data on the content of benzo(a)pyrene (BP) in oil shale industry wastewater, the effectiveness of various effluent treatment processes (evaporation, extraction with butyl acetate, trickling filters, aeration tanks) in reducing the level of BP in oil shale wastewater, the level of BP in various bodies of water of Estonia, and in fish and other water organisms are reviewed. The quantitative determination of BP in concentrated diethyl ether extracts of water samples was carried out by ultraviolet and spectroluminescence procedures by use of the quasi-linear spectra at -196 degrees C in solid paraffins. It has been found that oil shale industry wastewater contains large amounts of BP. The most efficient purification process for removing the BP in oil shale industry phenol water is extraction with butyl acetate. The level of BP in the rivers of the oil shale industry area is comparatively higher than in other bodies of water of the Republic. The concentration of BP in the lakes of the Estonian S.S.R. is on the whole insignificant. Even the maximum concentration found in our lakes is as a rule less than the safety limit for BP in bodies of water (0.005 microgram/l). During water is treated at the waterworks. The effectiveness of the water treatment in reducing the level of BP varies from 11 to 88%. Filtration was found to be the most effective treatment. About 20 samples of fish from nine bodies of water in Estonia have been analyzed for content of BP. The average content of BP in the muscular tissue of various species of fish is as a rule less than 1 microgram/kg. There is no significant difference in the concentration of BP in sea and freshwater fish. There is no important difference in the content of BP in the organs of various fish. Fat fish contain more BP than lean ones. The weight (age) of fish does not influence the content of BP in the muscular tissue of fish. PMID:571803

  6. ARE COASTAL WETLAND-LAKE LINKAGES IMPORTANT?

    EPA Science Inventory

    Because coastal werlands typically comprise only a small percentage of the overall surface area in large lakes, an assumption has often been made that functional links between wetlands and the lake proper are of little significance. Recent investigations of functional linkages be...

  7. Lake Eyre, Simpson Desert, South Australia, Australia

    NASA Technical Reports Server (NTRS)

    1990-01-01

    Lake Eyre, Simpson Desert, South Australia, Australia (27.0S, 136.0E) is normally a dry lakebed for years on end. However on rare occasions small amounts of rainfall are recorded and ponding can be seen in low parts of the lake, as in this image, where an algae bloom in the water is seen as a dark pink area on the lakebed. The Finke Riverbed intersects Lake Eyre but it is normally a dry wash and seldom contributes water to the lake.

  8. Estonian soil classification as a tool for recording information on soil cover and its matching with local site types, plant covers and humus forms classifications

    NASA Astrophysics Data System (ADS)

    Kõlli, Raimo; Tõnutare, Tõnu; Rannik, Kaire; Krebstein, Kadri

    2015-04-01

    Estonian soil classification (ESC) has been used successfully during more than half of century in soil survey, teaching of soil science, generalization of soil databases, arrangement of soils sustainable management and others. The Estonian normally developed (postlithogenic) mineral soils (form 72.4% from total area) are characterized by mean of genetic-functional schema, where the pedo-ecological position of soils (ie. location among other soils) is given by means of three scalars: (i) 8 stage lithic-genetic scalar (from rendzina to podzols) separates soils each from other by parent material, lithic properties, calcareousness, character of soil processes and others, (ii) 6 stage moisture and aeration conditions scalar (from aridic or well aerated to permanently wet or reductic conditions), and (iii) 2-3 stage soil development scalar, which characterizes the intensity of soil forming processes (accumulation of humus, podzolization). The organic soils pedo-ecological schema, which links with histic postlithogenic soils, is elaborated for characterizing of peatlands superficial mantle (form 23.7% from whole soil cover). The position each peat soil species among others on this organic (peat) soil matrix schema is determined by mean of 3 scalars: (i) peat thickness, (ii) type of paludification or peat forming peculiarities, and (iii) stage of peat decomposition or peat type. On the matrix of abnormally developed (synlithogenic) soils (all together 3.9%) the soil species are positioned (i) by proceeding in actual time geological processes as erosion, fluvial processes (at vicinity of rivers, lakes or sea) or transforming by anthropogenic and technological processes, and (ii) by 7 stage moisture conditions (from aridic to subaqual) of soils. The most important functions of soil cover are: (i) being a suitable environment for plant productivity; (ii) forming adequate conditions for decomposition, transformation and conversion of falling litter (characterized by humus

  9. It's all about water: from small scale hydrologic processes in ice wedge polygonal tundra and thermokarst lakes to larger scale river runoff (Lena River Delta, Siberia) (Invited)

    NASA Astrophysics Data System (ADS)

    Boike, J.; Langer, M.; Fedorova, I.; Muster, S.; Kutzbach, L.; Cresto Aleina, F.

    2013-12-01

    The Lena River Delta in Northern Yakutia forms one of the largest deltas in the Arctic and its catchment area (2 430 000 km2) is one of the largest in the whole of Eurasia. The Lena River distributes water and sediment in four main channels before discharging in total about 30 km3 of water through the delta into the Arctic Ocean every year and its discharge has been observed to be increasing. The goal of this presentation is to characterize the hydrologic processes that are strongly affected by a transient climate component- the permafrost. Permafrost plays a major role for storage and release of water to rivers and surface and subsurface water bodies. Conversely, the coupled water and heat fluxes in the atmosphere and below ground have a marked influence on the permafrost's thermal regime. Our study site, the Lena River Delta, is also one of the coldest and driest places on Earth, with mean annual air temperatures of about -13 °C, a large annual air temperature range of about 44 °C and summer precipitation usually less than 150 mm. Very cold continuous permafrost of about -8.6 °C (11 m depth) underlays the area between about 400 and 600 m below surface and since 2006 the permafrost has warmed than 1 °C at 10.7 m. Roughly half of the land surface is dominated by wet surfaces, such as polygons, ponds and thermokarst lakes. This contribution summarizes past and ongoing research on hydrologic processes across spatial scales, from microtopographic processes of polygonal tundra to regional scale deltaic processes to assess short and long term changes in water fluxes. We quantify unfrozen water in soils, streams and river discharges and water bodies' storage at larger scales. Water bodies were mapped using optical and radar satellite data with resolutions of 4 m or better, Landsat-5 TM at 30 m and the MODIS water mask at 250 m resolution. Ponds, i. e. water bodies with surface are smaller than 104 m, make over 95 % of the total number of water bodies and are not

  10. Characterization of Lake Michigan coastal lakes using zooplankton assemblages

    USGS Publications Warehouse

    Whitman, Richard L.; Nevers, Meredith B.; Goodrich, Maria L.; Murphy, Paul C.; Davis, Bruce M.

    2004-01-01

    Zooplankton assemblages and water quality were examined bi-weekly from 17 April to 19 October 1998 in 11 northeastern Lake Michigan coastal lakes of similar origin but varied in trophic status and limnological condition. All lakes were within or adjacent to Sleeping Bear Dunes National Lakeshore, Michigan. Zooplankton (principally microcrustaceans and rotifers) from triplicate Wisconsin net (80 I?m) vertical tows taken at each lake's deepest location were analyzed. Oxygen-temperature-pH-specific conductivity profiles and surface water quality were concurrently measured. Bray-Curtis similarity analysis showed small variations among sample replicates but large temporal differences. The potential use of zooplankton communities for environmental lake comparisons was evaluated by means of BIOENV (Primer 5.1) and principal component analyses. Zooplankton analyzed at the lowest identified taxonomic level yielded greatest sensitivity to limnological variation. Taxonomic and ecological aggregations of zooplankton data performed comparably, but less well than the finest taxonomic analysis. Secchi depth, chlorophyll a, and sulfate concentrations combined to give the best correlation with patterns of variation in the zooplankton data set. Principal component analysis of these variables revealed trophic status as the most influential major limnological gradient among the study lakes. Overall, zooplankton abundance was an excellent indicator of variation in trophic status.

  11. Metagenome sequencing of the prokaryotic microbiota of the hypersaline and meromictic soap lake, washington.

    PubMed

    Hawley, Erik R; Hess, Matthias

    2014-01-01

    Soap Lake is a small saline lake in central eastern Washington that is sharply stratified into two layers. In addition to being highly alkaline (~pH 10), Soap Lake also contains high concentrations of sulfide. Here, we report the community profile of the prokaryotic microbiota associated with Soap Lake surface water. PMID:24459273

  12. Meteorite Impact Lakes: Difficulties of the Evidence for Origin

    NASA Astrophysics Data System (ADS)

    Sapelko, Tatyana; Naumenko, Mikhail; Kuznetsov, Denis

    2014-05-01

    In addition to volcanic and tectonic activity on the border of the Late Pleistocene and Holocene occurred and other disastrous events that are reflected in the history of the lakes. The recognition of meteorite impact crater lakes is impeded by difficulties in finding evidence of an impact origin. Such lakes have been recognized (Hartung and Koeberl, 1994) by their circular shape, their occurrence outside of areas where other mechanisms for circular depression formation are readily apparent, and the preservation of meteorite or ejected glass fragments (Cohen. 2003). Meteorite impact Lake appeared not only in early periods (like Lake El'gygytgyn and Lake Yanisyarvi in Russia), but in the Late Pleistocene and Holocene as well. One of these lakes is located in the Nizhny Novgorod region of Russia. Svetloyar (56º49' N; 45º05'E; 109 m a.s.l.) - lake with a small area of 0.15 km2 and a great depth of the lake up to 35 m., a circular shape, surrounded on three sides by hills , reaching 15 m above the lake level. On the lake we have carried out paleolimnological and hydrological investigations.Interdisciplinary researches included sedimentological, geochemical, pollen, diatom, radiocarbon and other analyses of lake sediments. Based on field measurements, we created a digital morphometric model of the bottom depths and slopes of the lake. Using the all results we are reconstruct the Lake's history and climatic changes. We establish a long hiatus after the disappearance of large lake on the border of the late Pleistocene and Holocene. For comparison we were have studied three of the morphometric similar lakes in the Nizhny Novgorod region. According to preliminary data the history of any of these lakes is not similar the Lake Svetloyar history. We discuss our results and have compared with data on the meteorite Lake Kaali , Estonia (Rasmussen et al., 2000; Raukas et.al,1995; 2002; Veski et.al, 2001, 2002, 2004).

  13. Mitigation alternatives for L Lake

    SciTech Connect

    Moore, D.B.

    1988-11-03

    The current condition of L Lake/Steel Creek was summarized in a report to SCDHEC in June 1988 which reported that the L Lake and Steel Creek ecosystems were adequately developing towards balanced biological communities. If mitigation for L Lake inputs, specifically temperature and nutrients, are required, several viable alternatives are available. A report prepared by Spencer in 1986 discusses the various options available for cooling L-Reactor discharges. In effect, a small cooling tower is the only realistic solution to reducing effluent temperatures. Nutrient mitigation can take several approaches including upstream sewage treatment, hypolimnetic withdrawal, dilution of input water by Par Pond water, precipitation of nutrients, and sediment oxidation. None of these systems would influence the thermal regime, but would significantly reduce nutrient input into the system. One beneficial use of L-Lake thermal effluents is algaculture, the production of useful algae. A document prepared in 1988 concludes that algaculture is a technically and economically feasible mitigation alternative for L Lake and could allow L Lake to be handled under Section 318 of the Clean Water Act.

  14. Diversity of extremophilic purple phototrophic bacteria in Soap Lake, a Central Washington (USA) Soda Lake.

    PubMed

    Asao, Marie; Pinkart, Holly C; Madigan, Michael T

    2011-08-01

    Culture-based and culture-independent methods were used to explore the diversity of phototrophic purple bacteria in Soap Lake, a small meromictic soda lake in the western USA. Among soda lakes, Soap Lake is unusual because it consists of distinct upper and lower water bodies of vastly different salinities, and its deep waters contain up to 175 mM sulfide. From Soap Lake water new alkaliphilic purple sulfur bacteria of the families Chromatiaceae and Ectothiorhodospiraceae were cultured, and one purple non-sulfur bacterium was isolated. Comparative sequence analysis of pufM, a gene that encodes a key photosynthetic reaction centre protein universally found in purple bacteria, was used to measure the diversity of purple bacteria in Soap Lake. Denaturing gradient gel electrophoresis and subsequent phylogenetic analyses of pufMs amplified from Soap Lake water revealed that a significant diversity of purple bacteria inhabit this soda lake. Although close relatives of several of the pufM phylotypes obtained from cultured species could also be detected in Soap Lake water, several other more divergent pufM phylotypes were also detected. It is possible that Soap Lake purple bacteria are major contributors of organic matter into the ecosystem of this lake, especially in its extensive anoxic and sulfidic deep waters. PMID:21410624

  15. Deglacial and lake level fluctuation history recorded in cores, Beaver Lake, Upper Peninsula, Michigan

    USGS Publications Warehouse

    Fisher, Timothy G.; Whitman, Richard L.

    1999-01-01

    Sediment cores collected from the littoral and pelagic zones of Beaver Lake, Michigan record fluctuations in the water level of Lake Superior. Beaver Lake is a small 300 ha lake in Pictured Rocks National Lakeshore (PRNL) now separated from Lake Superior by a dune-capped barrier bar. Cores were collected using a vibracorer from a lake-ice platform in February 1997. A 2.85 m long core in 10 m of water contains well-sorted sand, rhythmites, peat, interbedded sand and gyttja, and is capped with 1 m of massive gyttja. A 9480 BP AMS age from the basal sand provides a minimum deglacial date for the area. Further analysis indicates a sand-dominated depositional environment from a low lake stand at approximately 8500 BP to present. An approximate 8800 BP red to gray sediment color transition records either the cessation of meltwater input from Lake Agassiz or receding ice, while a younger similarly colored transition, 6600 BP in age, likely records sediment reworking in the coastal zone. Four AMS ages on peat range from 8520 to 7340 BP and are indicative of the Houghton low phase. Burial of the peat by stratified sand and gyttja after 7340 BP indicates a rising lake level. Peat at a higher level in the lake basin, encountered in shallow littoral cores, ranges in age from 6800 to 6420 BP, which estimates a 0.91 m rise/century in lake level to the Nipissing level by 5000 BP.

  16. Reported contraceptive use, risk behaviours and STIs among military conscripts in Estonian defence forces.

    PubMed

    David Parker, R; Regier, Michael D; Widmeyer, Joseph; Honaker, John; Rüütel, Kristi

    2015-10-01

    Limited research exists on sexually transmitted infection (STI) and risk behaviour among military personnel. Published research on condom use and types of contraceptives used yield mixed results, yet, the perception that military members are at higher risk for STIs remains. The objectives of this cross-sectional study were to measure factors such as condom use, contraceptive methods, and risky behaviours (i.e. drug use and sex with commercial sex workers) and investigate differences between ethnic groups, where culture could influence behaviour. Data were collected from a recruited population of 584 male, military conscripts in northeastern Europe. Using multinomial logistic regression models, statistically significant findings include an interaction between the use of contraceptive methods of Russians with casual partners and ethnicity, with higher odds of effective methods used among Estonians with regular partners (OR = 8.13) or casual partners (OR = 11.58) and Russians with regular partners (OR = 4.98). Effective contraceptive methods used less frequently with casual partners by ethnic Russians is important in providing education and risk reduction services to young, male conscripts. These findings may be used as a baseline to inform health education and STI prevention programmes tailored to military members in Eastern Europe in the absence of other published studies. PMID:25324351

  17. Hereditary minisatellite mutations among the offspring of Estonian Chernobyl cleanup workers.

    PubMed

    Kiuru, Anne; Auvinen, Anssi; Luokkamäki, Mikko; Makkonen, Kaisa; Veidebaum, Toomas; Tekkel, Mare; Rahu, Mati; Hakulinen, Timo; Servomaa, Kristina; Rytömaa, Tapio; Mustonen, Riitta

    2003-05-01

    A single accidental event such as the fallout released from the Chernobyl reactor in 1986 can expose millions of people to non-natural environmental radiation. Ionizing radiation increases the frequency of germline mutations in experimental studies, but the genetic effects of radiation in humans remain largely undefined. To evaluate the hereditary effects of low radiation doses, we compared the minisatellite mutation rates of 155 children born to Estonian Chernobyl cleanup workers after the accident with those of their siblings born prior to it. All together, 94 de novo paternal minisatellite mutations were found at eight tested loci (52 and 42 mutants among children born after and before the accident, respectively). The minisatellite mutation rate was nonsignificantly increased among children born after the accident (0.042 compared to 0.036, OR 1.33, 95% CI 0.80-2.20). Furthermore, there was some indication of an increased mutation rate among offspring born after the accident to workers who had received doses of 20 cSv or above compared with their siblings born before the accident (OR 3.0, 95% CI 0.97-9.30). The mutation rate was not associated with the father's age (OR 1.04, 95% CI 0.94-1.15) or the sex of the child (OR 0.95, 95% CI 0.50-1.79). Our results are consistent with both no effect of radiation on minisatellite mutations and a slight increase at dose levels exceeding 20 cSv. PMID:12710876

  18. Symptoms of anxiety and depression in Estonian medical students with sleep problems.

    PubMed

    Eller, Triin; Aluoja, Anu; Vasar, Veiko; Veldi, Marlit

    2006-01-01

    High emotional stress in medical students has been observed in many studies. Our aim in this article was to assess the prevalence of symptoms of anxiety and depression among Estonian medical students and to find relationships between sleep complaints and emotional symptoms. The study group consisted of 413 medical students, ages 19-33 years, at the University of Tartu. Each was asked to complete two questionnaires: the Emotional State Questionnaire (EST-Q), containing 28 questions, and the Questionnaire on Sleep and Daytime Habits, with 25 questions. The anxiety and depression subscales from the EST-Q were applied. From the study group, 21.9% students had symptoms of anxiety, and 30.6% had symptoms of depression. The frequency of anxiety and depressive symptoms was higher in females. In regression and multiple regression analysis, we determined which sleep problems were related to emotional symptoms. The associations were different for men and women. In women, anxiety remained significantly related to waking up because of nightmares and feeling tired in the morning; depressive symptoms were related to difficulties in getting to sleep at night, waking up because of nightmares and nocturnal eating habits, daytime sleepiness, and sleepiness during school lessons. In men, significant relations were clear only for depression: difficulties in falling asleep at night before an exam and subjective sleep quality. The study demonstrated that a high percentage of medical students had emotional symptoms. We found that some sleep problems indicated underlying symptoms of anxiety and depression. PMID:16555263

  19. CO2 mineral sequestration in oil-shale wastes from Estonian power production.

    PubMed

    Uibu, Mai; Uus, Mati; Kuusik, Rein

    2009-02-01

    In the Republic of Estonia, local low-grade carbonaceous fossil fuel--Estonian oil-shale--is used as a primary energy source. Combustion of oil-shale is characterized by a high specific carbon emission factor (CEF). In Estonia, the power sector is the largest CO(2) emitter and is also a source of huge amounts of waste ash. Oil-shale has been burned by pulverized firing (PF) since 1959 and in circulating fluidized-bed combustors (CFBCs) since 2004-2005. Depending on the combustion technology, the ash contains a total of up to 30% free Ca-Mg oxides. In consequence, some amount of emitted CO(2) is bound by alkaline transportation water and by the ash during hydraulic transportation and open-air deposition. The goal of this study was to investigate the possibility of improving the extent of CO(2) capture using additional chemical and technological means, in particular the treatment of aqueous ash suspensions with model flue gases containing 10-15% CO(2). The results indicated that both types of ash (PF and CFBC) could be used as sorbents for CO(2) mineral sequestration. The amount of CO(2) captured averaged 60-65% of the carbonaceous CO(2) and 10-11% of the total CO(2) emissions. PMID:18793821

  20. Ensemble approach for projections of return periods of extreme water levels in Estonian waters

    NASA Astrophysics Data System (ADS)

    Eelsalu, Maris; Soomere, Tarmo; Pindsoo, Katri; Lagemaa, Priidik

    2014-12-01

    The contribution of various drivers to the water level in the eastern Baltic Sea and the presence of outliers in the time series of observed and hindcast water level lead to large spreading of projections of future extreme water levels. We explore the options for using an ensemble of projections to more reliably evaluate return periods of extreme water levels. An example of such an ensemble is constructed by means of fitting several sets of block maxima (annual maxima and stormy season maxima) with a Generalised Extreme Value, Gumbel and Weibull distribution. The ensemble involves projections based on two data sets (resolution of 6 h and 1 h) hindcast by the Rossby Centre Ocean model (RCO; Swedish Meteorological and Hydrological Institute) and observed data from four representative sites along the Estonian coast. The observed data are transferred into the grid cells of the RCO model using the HIROMB model and a linear regression. For coastal segments where the observations represent the offshore water level well, the overall appearance of the ensembles signals that the errors of single projections are randomly distributed and that the median of the ensemble provides a sensible projection. For locations where the observed water level involves local effects (e.g. wave set-up) the block maxima are split into clearly separated populations. The resulting ensemble consists of two distinct clusters, the difference between which can be interpreted as a measure of the impact of local features on the water level observations.

  1. Dinkey Lakes Roadless Area, California

    SciTech Connect

    Dodge, F.C.W.; Federspiel, F.E.

    1984-01-01

    The results of a mineral survey conducted in 1980, show that parts of the Dinkey Lakes Roadless Area have substantiated resource potential for tungsten and marble and probable resource potential for quartz crystal gemstones. A probable resource potential for geothermal energy exists in one small area. No potential for other metallic mineral or energy resources was identified in this study.

  2. Pesticides in lake water in the Beasley Lake Watershed, 1998-2005

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Oxbow lakes are remnants of meandering floodplain rivers, which have been cut off and physically isolated from their respective main river channels. They usually capture only small relic drainages. Beasley Lake Watershed, a Conservation Effects Assessment Project (CEAP) benchmark watershed, is one...

  3. Global patterns in lake surface temperature trends

    NASA Astrophysics Data System (ADS)

    O'Reilly, C.; Sharma, S.; Gray, D.; Hampton, S. E.; Read, J. S.; Rowley, R.; McIntyre, P. B.; Lenters, J. D.; Schneider, P.; Hook, S. J.

    2014-12-01

    Temperature profoundly affects dynamics in the water bodieson which human societies depend worldwide. Even relatively small water temperature changes can alter lake thermal structure with implications for water level, nutrient cycling, ecosystem productivity, and food web dynamics. As air temperature increases with climate change and human land use transforms watersheds, rising water temperatures have been reported for individual lakes or regions, but a global synthesis is lacking; such a synthesis is foundational for understanding the state of freshwater resources. We investigated global patterns in lake surface water temperatures between 1985 and 2009 using in-situ and satellite data from 236 lakes. We demonstrate that lakes are warming significantly around the globe, at an average rate of 0.34 °C per decade. The breadth of lakes in this study allowed examination of the diversity of drivers across global lakes, and highlighted the importance of ice cover in determining the suite of morphological and climate drivers for lake temperature dynamics. These empirical results are consistent with modeled predictions of climate change, taking into account the extent to which water warming can be modulated by local environmental conditions and thus defy simple correlations with air temperature. The water temperature changes we report have fundamental importance for thermal structure and ecosystem functioning in global water resources; recognition of the extent to which lakes are currently in transition should have broad implications for regional and global models as well as for management.

  4. Lake trout spawning habitat in the Six Fathom Bank-Yankee Reef lake trout sanctuary, Lake Huron

    USGS Publications Warehouse

    Edsall, Thomas A.; Brown, Charles L.; Kennedy, Gregory W.; Poe, Thomas P.

    1992-01-01

    Attempts to reestablish self-sustaining stocks of lake trout (Salvelinus namaycush) in the lower four Great Lakes, where the species was extinguished in the 1950s and 1960s, have been largely unsuccessful. To avoid many of the problems believed to be contributing to this failure, the fishery management community recently established several sanctuaries in the offshore waters of the Great Lakes where the development and protection of self-sustaining stocks of lake trout would be a primary management objective. One of these, the Six Fathom Bank-Yankee Reef sanctuary, was created in the south-central portion of Lake Huron. This sanctuary covers 168,000 ha and includes the shallower portions of the Six Fathom and Ipperwash scarps, which are major bathymetric features in the southern half of the lake. Historical accounts describe Six Fathom Bank as the most important lake trout spawning ground in the lake. Here we present the results of lake bed surveys conducted in the sanctuary with side-scan sonar, underwater videocamera systems, and a small research submarine. Our observations of the lake bed are consistent with what is known of the bedrock stratigraphy, glacial history, and karst geomorphology of the Lake Huron basin. Most of the loose rock we found seemed to be derived from local carbonate bedrock formations, although non-carbonate rock probably from Precambrian sources to the north was also present in some areas. Much of the bedrock and loose rock displayed karst solution features described for the Bruce Peninsula on the Ontario shoreline. Our surveys revealed substantial areas of lake bed at water depths of 20–36 m that resembled suitable spawning and fry production habitat for the shallow-water strains of lake trout that are the focus of the rehabilitation effort. Low mid-lake nutrient levels documented recently by others and the extremely high abundance of Mysis relicta (an important item in the diet of young lake trout) that we documented on Yankee Reef

  5. The Baltic Klint beneath the central Baltic Sea and its comparison with the North Estonian Klint

    NASA Astrophysics Data System (ADS)

    Tuuling, Igor; Flodén, Tom

    2016-06-01

    Along its contact with the Baltic Shield, the margin of the East European Platform reveals a well-developed, flooded terraced relief. The most striking and consistent set of escarpments at the contact of the Lower Palaeozoic calcareous and terrigenous rocks, known as the Baltic Klint (BK), extends from northwest of Russia to the Swedish island of Öland. Marine seismic reflection profiling in 1990-2004 revealed the central Baltic Sea Klint (BSK) section in detail and enabled comparison of its geology/geomorphology with a classical klint-section onshore, namely the North Estonian Klint (NEK). The conception of the BK onshore, which is based on the land-sea separating terraced relief in northern Estonia, is not fully applicable beneath the sea. Therefore, we consider that the BSK includes the entire terraced Cambrian outcrop. We suggest the term "Baltic Klint Complex" to include the well-terraced margin of the Ordovician limestone outcrop, which is weakly developed in Estonia. Because of a steady lithological framework of the bedrock layers across the southern slope of the Fennoscandian Shield, the central BSK in the western and the NEK in the eastern part of the Baltic Homocline have largely identical morphologies. The North Estonian Ordovician limestone plateau with the calcareous crest of the BK extends across the central Baltic Sea, whereas morphological changes/variations along the Klint base occur due to the east-westerly lithostratigraphic/thickness changes in the siliciclastic Cambrian sequence. The verge of the NEK, located some 30-50 m above sea level, starts to drop in altitude as its east-westerly course turns to northeast-southwest in western Estonia. Further westwards, the BK shifts gradually into southerly deepening (0.1-0.2°) layers as its crest drops to c. 150 m below sea level (b.s.l.) near Gotska Sandön. This course change is accompanied by a considerable decrease in thickness of the platform sedimentary cover, as below the central Baltic Sea the

  6. Effects of fish density and relative abundance on competition between larval lake herring and lake whitefish for zooplankton

    USGS Publications Warehouse

    Todd, Thomas N.; Davis, Bruce M.

    1995-01-01

    Competition for zooplankton between larval lake herring (Coregonus artedi) and lake whitefish (C. clupeaformis) was compared in mesocosm experiments in a small lake. Both species were combined in test enclosures at relative abundances of 1:1 or 1:4 lake herring to lake whitefish at densities of 500; 1, 000; and 2, 000 fish per cage, and were allowed to feed ad libitum on available zooplankton. After 60 days, at 500 fish per cage and a 1:1 ratio, lake whitfish were significantly larger than lake herring. At 1, 000 and 2, 000 fish per cage, lake herring and lake whitefish exhibited similar depressed growth rates. Survival was lower (30-50%) in the nets with 2, 000 fish than in the lower fish densities. We suspect that diet similarities of juvenile lake herring and lake whitefish in addition to the larger size and more aggressive behavior of larval lake whitefish resulted in the depressed growth and poorer survival for lake herring.

  7. Occurrence of clinical mastitis in primiparous Estonian dairy cows in different housing conditions

    PubMed Central

    Kalmus, Piret; Viltrop, Arvo; Aasmäe, Birgit; Kask, Kalle

    2006-01-01

    Background Objectives of the study were to document the impact of some management factors on the occurrence of clinical mastitis in primiparous dairy cows and to identify common udder pathogens of clinical mastitis in freshly calved heifers and multiparous cows on the day of calving. Methods A one-year study was conducted during 2004 and 2005 in 11 selected Estonian dairy herds. Data consisted of 68 heifers with clinical mastitis and 995 heifers without clinical mastitis on the day of calving. Multivariable logistic regression with a random herd effect was used to investigate any association between housing system or the time interval from movement of heifers to the calving facility and day of calving on occurrence of clinical mastitis. Milk samples for bacteriological analysis were collected from affected heifers and multiparous cows on the day of calving Results Clinical mastitis occurrence in the study population of freshly calved heifers equalled 6.1 %. Housing system was not a significant risk factor for clinical mastitis of freshly calved heifers. Moving heifers to the cowbarn less than two weeks before calving in tiestall farms increased risk (OR = 5.9 p = 0.001) for clinical mastitis at parturition. The most frequently isolated udder pathogens among heifers were Escherichia coli (22.1%), Streptococcus uberis (19.1%) and coagulase-negative staphylococci (8.8%). In comparison, the main pathogen in multiparous cows with clinical mastitis at parturition was Staphylococcus aureus (11.2%). Conclusion Moving heifers to the calving facilities too late in tiestall farms increased risk for clinical mastitis at parturition. The isolated udder pathogens did not differ significantly in tiestall farms compared to freestall farms in heifers, but differences were found between heifers and multiparous cows at parturition. PMID:17118174

  8. The Estonian study of Chernobyl cleanup workers: I. Design and questionnaire data

    SciTech Connect

    Tekkel, M.; Rahu, M.; Veidebaum, T.

    1997-05-01

    Nearly 2% of the male population of Estonia aged 20-39 years were sent to Chernobyl to assist in the cleanup activities after the reactor accident. A cohort of 4,833 cleanup workers was assembled based on multiple and independent sources of information. Information obtained from 3,704 responses to a detailed questionnaire indicated that 63% of the workers were sent to Chernobyl in 1986; 54% were of Estonian and 35% of Russian ethnicity; 72% were married, and 1,164 of their 5,392 children were conceived after the Chernobyl disaster. The workers were less educated than their counterparts than their counterparts in the general population of Estonia, and only 8.5% had attended university. Based on doses entered in workers records, the mean dose was 11 cGy, with only 1.4% over 25 cGy. Nearly 85% of the workers were sent as part of military training activities, and more than half spent in excess of 3 months in the Chernobyl area. Thirty-six percent of the workers reported having worked within the immediate vicinity of the accident site; 11.5% worked on the roofs near the damaged reactor, clearing the highly radioactive debris. The most commonly performed task was the removal and burial of topsoil (55% of the workers). Potassium iodide was given to over 18% of the men. The study design also incorporates biological indicators of exposure based on the glycophorin A mutational assay of red blood cells and chromosome translocation analyses of lymphocytes; record linkage with national cancer registry and mortality registry files to determine cancer incidence and cause-specific mortality; thyroid screening examinations with ultrasound and fine-needle biopsy; and cryopreserved white blood cells and plasma for future molecular studies. Comprehensive studies of Chernobyl cleanup workers have potential to provide a new information about cancer risks due to protracted exposures to ionizing radiation. 21 refs., 1 fig., 11 tabs.

  9. Prevalence of alcohol-related pathologies at autopsy: Estonian Forensic Study of Alcohol and Premature Death

    PubMed Central

    Tuusov, Jana; Lang, Katrin; Väli, Marika; Pärna, Kersti; Tõnisson, Mailis; Ringmets, Inge; McKee, Martin; Helander, Anders; Leon, David A

    2014-01-01

    Aims Alcohol can induce diverse serious pathologies, yet this complexity may be obscured when alcohol-related deaths are classified according to a single underlying cause. We sought to quantify this issue and its implications for analysing mortality data. Design, Setting and Participants Cross-sectional study included 554 men aged 25–54 in Estonia undergoing forensic autopsy in 2008–09. Measurements Potentially alcohol-related pathologies were identified following macroscopic and histological examination. Alcohol biomarkers levels were determined. For a subset (26%), drinking behaviour was provided by next-of-kin. The Estonian Statistics Office provided underlying cause of death. Findings Most deaths (75%) showed evidence of potentially alcohol-related pathologies, and 32% had pathologies in two or more organs. The liver was most commonly affected [60.5%, 95% confidence interval (CI) = 56.3–64.6] followed by the lungs (18.6%, 95% CI = 15.4–22.1), stomach (17.5%, 95% CI = 14.4–20.9), pancreas (14.1%, 95% CI = 11.3–17.3), heart (4.9%, 95% CI = 3.2–7.0) and oesophagus (1.4%, 95% CI = 0.6–2.8). Only a minority with liver pathology had a second pathology. The number of pathologies correlated with alcohol biomarkers (phosphatidylethanol, gamma-glytamyl transpeptidase in blood, ethylglucuronide, ethylsulphate in urine). Despite the high prevalence of liver pathology, few deaths had alcoholic liver disease specified as the underlying cause. Conclusion The majority of 554 men aged 25–54 undergoing forensic autopsy in Estonia in 2008–09 showed evidence of alcohol-related pathology. However, the recording of deaths by underlying cause failed to capture the scale and nature of alcohol-induced pathologies found. PMID:25066373

  10. Non-cancer morbidity among Estonian Chernobyl cleanup workers: a register-based cohort study

    PubMed Central

    Rahu, Kaja; Bromet, Evelyn J; Hakulinen, Timo; Auvinen, Anssi; Uusküla, Anneli; Rahu, Mati

    2014-01-01

    Objective To examine non-cancer morbidity in the Estonian Chernobyl cleanup workers cohort compared with the population sample with special attention to radiation-related diseases and mental health disorders. Design Register-based cohort study. Setting Estonia. Participants An exposed cohort of 3680 men (cleanup workers) and an unexposed cohort of 7631 men (population sample) were followed from 2004 to 2012 through the Population Registry and Health Insurance Fund database. Methods Morbidity in the exposed cohort compared with the unexposed controls was estimated in terms of rate ratio (RR) with 95% CIs using Poisson regression models. Results Elevated morbidity in the exposed cohort was found for diseases of the nervous system, digestive system, musculoskeletal system, ischaemic heart disease and for external causes. The most salient excess risk was observed for thyroid diseases (RR=1.69; 95% CI 1.38 to 2.07), intentional self-harm (RR=1.47; 95% CI 1.04 to 2.09) and selected alcohol-related diagnoses (RR=1.25; 95% CI 1.12 to 1.39). No increase in morbidity for stress reactions, depression, headaches or sleep disorders was detected. Conclusions No obvious excess morbidity consistent with biological effects of radiation was seen in the exposed cohort, with the possible exception of benign thyroid diseases. Increased alcohol-induced morbidity may reflect alcohol abuse, and could underlie some of the higher morbidity rates. Mental disorders in the exposed cohort were probably under-reported. The future challenge will be to study mental and physical comorbidities in the Chernobyl cleanup workers cohort. PMID:24833681

  11. Energy density of bloaters in the upper Great Lakes

    USGS Publications Warehouse

    Pothoven, Steven A.; Bunnell, David B.; Madenjian, Charles P.; Gorman, Owen T.; Roseman, Edward F.

    2012-01-01

    We evaluated the energy density of bloaters Coregonus hoyi as a function of fish size across Lakes Michigan, Huron, and Superior in 2008–2009 and assessed how differences in energy density are related to factors such as biomass density of bloaters and availability of prey. Additional objectives were to compare energy density between sexes and to compare energy densities of bloaters in Lake Michigan between two time periods (1998–2001 and 2008–2009). For the cross-lake comparisons in 2008, energy density increased with fish total length (TL) only in Lake Michigan. Mean energy density adjusted for fish size was 8% higher in bloaters from Lake Superior than in bloaters from Lake Huron. Relative to fish in these two lakes, small (175 mm TL) bloaters had higher energy density. In 2009, energy density increased with bloater size, and mean energy density adjusted for fish size was about 9% higher in Lake Michigan than in Lake Huron (Lake Superior was not sampled during 2009). Energy density of bloaters in Lake Huron was generally the lowest among lakes, reflecting the relatively low densities of opossum shrimp Mysis diluviana and the relatively high biomass of bloaters reported for that lake. Other factors, such as energy content of prey, growing season, or ontogenetic differences in energy use strategies, may also influence cross-lake variation in energy density. Mean energy density adjusted for length was 7% higher for female bloaters than for male bloaters in Lakes Michigan and Huron. In Lake Superior, energy density did not differ between males and females. Finally, energy density of bloaters in Lake Michigan was similar between the periods 2008–2009 and 1998–2001, possibly due to a low population abundance of bloaters, which could offset food availability changes linked to the loss of prey such as the amphipods Diporeia spp.

  12. Simulating Lake-Groundwater Interactions During Decadal Climate Cycles: Accounting For Variable Lake Area In The Watershed

    NASA Astrophysics Data System (ADS)

    Virdi, M. L.; Lee, T. M.

    2009-12-01

    The volume and extent of a lake within the topo-bathymetry of a watershed can change substantially during wetter and drier climate cycles, altering the interaction of the lake with the groundwater flow system. Lake Starr and other seepage lakes in the permeable sandhills of central Florida are vulnerable to climate changes as they rely exclusively on rainfall and groundwater for inflows in a setting where annual rainfall and recharge vary widely. The groundwater inflow typically arrives from a small catchment area bordering the lake. The sinkhole origin of these lakes combined with groundwater pumping from underlying aquifers further complicate groundwater interactions. Understanding the lake-groundwater interactions and their effects on lake stage over multi-decadal climate cycles is needed to manage groundwater pumping and public expectation about future lake levels. The interdependence between climate, recharge, changing lake area and the groundwater catchment pose unique challenges to simulating lake-groundwater interactions. During the 10-year study period, Lake Starr stage fluctuated more than 13 feet and the lake surface area receded and expanded from 96 acres to 148 acres over drier and wetter years that included hurricanes, two El Nino events and a La Nina event. The recently developed Unsaturated Zone Flow (UZF1) and Lake (LAK7) packages for MODFLOW-2005 were used to simulate the changing lake sizes and the extent of the groundwater catchment contributing flow to the lake. The lake area was discretized to occupy the largest surface area at the highest observed stage and then allowed to change size. Lake cells convert to land cells and receive infiltration as receding lake area exposes the underlying unsaturated zone to rainfall and recharge. The unique model conceptualization also made it possible to capture the dynamic size of the groundwater catchment contributing to lake inflows, as the surface area and volume of the lake changed during the study

  13. Effect of thermal discharges on the mass energy balance of Lake Michigan

    NASA Technical Reports Server (NTRS)

    Asbury, J. G.

    1972-01-01

    Effects of electric utility generating stations and steel mills on physical quality of Lake Michigan are considered. Study is based on extension of heat exchange model developed by Edinger and Geyer for small lakes and cooling ponds.

  14. Water quality of selected lakes in Mount Rainier National Park, Washington with respect to lake acidification

    USGS Publications Warehouse

    Turney, G.L.; Dion, N.P.; Sumioka, S.S.

    1986-01-01

    Thirteen lakes in Mount Rainier National Park were evaluated for general chemical characteristics, sensitivity to acidification by acidic precipitation, and degree of existing acidification. The lakes studies were Allen, one of the Chenuis group, Crescent , Crystal, Eleanor, Fan, one of the Golden group, Marsh, Mowich, Mystic, Shriner, and two unnamed lakes. The lakes were sampled in August 1983. Specific conductance values were generally 21 microsiemens/cm at 25 C or less, and dissolved solids concentrations were generally 20 mg/L or less. The major cations were calcium and sodium, and the major anion was bicarbonate. Alkalinity concentrations ranged from 2.1 to 9.0 mg/L in 12 of the lakes. Allen Lake was the exception, having an alkalinity concentration of 27 mg/L. The pH values for all of the lakes ranged from 5.8 to 6.5. In most of the lakes, vertical profiles of temperature, dissolved oxygen, pH, and specific conductance were relatively uniform. In the deeper lakes, temperature decreased with depth and dissolved-oxygen concentrations increased to about 20 feet, remained constant to 80 ft, then decreased with increasing depth. Exceptions to general water quality patterns were observed in three lakes. Allen Lake had a specific conductance value of 58 Microsiemens/cm. The lake of the Golden group was anaerobic at the bottom and had relatively high concentrations of dissolved organic carbon and dissolved metals, and a lower light transmission than the other lakes studied. One of the unnamed lakes had relatively high concentrations of phytoplankton and dissolved organic carbon and relatively low levels of light transmission. Comparisons of lake data to acid-sensitivity thresholds for specific conductance and alkalinity indicated that all of the lakes except Allen would be sensitive to acidic precipitation. The small sizes of the lakes, and their locations in basins of high precipitation and weathering-resistant rock types, enhance their sensitivity. None of the

  15. Longevity of Lake Superior lake trout

    USGS Publications Warehouse

    Schram, Stephen T.; Fabrizio, Mary C.

    1998-01-01

    The age structure of mature lake trout Salvelinus namaycush from the Wisconsin waters of Lake Superior increased following a population recovery that has taken place since the 1960s. As the population aged, it became apparent that scales were unreliable aging structures. Beginning in 1986, we examined both scale and sagittal otolith ages from tagged fish with a known period at liberty. We found large discrepancies in scale and sagittal otolith ages of mature fish, such that scale ages were biased low. We estimated lake trout living up to 42 years, which is greater than previously reported from Lake Superior. Investigators studying lake trout population dynamics in the Great Lakes should be aware that lake trout can live longer than previously thought.

  16. Lake Volta, Ghana

    NASA Technical Reports Server (NTRS)

    2002-01-01

    This true-color image of Lake Volta in Ghana was acquired March 31, 2002 by the Moderate Resolution Imaging Spectroradiometer (MODIS). Lake Volta is one of the world's largest artificially created lakes. Lake Volta is actually a reservoir formed from the damming of the Volta River, and extends 250 miles north of the Akosombo Dam. The lake covers an area of 8,482 square km. Credit: Jacques Descloitres, MODIS Land Rapid Response Team, NASA/GSFC

  17. A Pan-Arctic Assessment of High-Latitude Lake Change ~25 Years Apart

    NASA Astrophysics Data System (ADS)

    Sheng, Y.; Smith, L. C.; Li, J.; Lyons, E. A.; Wang, J.

    2011-12-01

    The Arctic and Sub-Arctic regions are the home to the world's largest quantity of terrestrial lakes. These lakes play a preeminent role in the global water cycle and balance, are sensitive to global warming, and are vital for human and animal water supply. However, they are poorly observed, and a uniform lake inventory is unavailable at the pan-Arctic scale. Though there have been studies of Arctic lake dynamics at local scales, the general picture of Arctic lake change stays unclear. A systematic regional-scale assessment of Arctic lake change in the past ~30 years is crucial for us to address "How have Arctic lakes responded to global warming?" The presentation reports a systematic effort of high-latitude (45N and north) lake inventory using recently available high-resolution satellite imagery. Since Arctic lakes are abundant in small-size classes and their seasonality varies from region to region, pan-Arctic lake mapping requires the use of thousands of cloud-free Landsat images acquired in lake-stable seasons. Nearly eight million lakes have been mapped in various landscapes of the pan-Arctic using automated lake identification algorithms with high replicability. Lake-abundant regions are selected using a systematic sampling strategy to detect decadal lake change using the mid-1970s and circa-2000 Landsat imagery. Spatial patterns of the observed lake dynamics are analyzed at regional scales and the relationship between lake abundance and size distribution is investigated.

  18. Index for hazard of Glacier Lake Outburst flood of Lake Merzbacher by satellite-based monitoring of lake area and ice cover

    NASA Astrophysics Data System (ADS)

    Xie, Zunyi; ShangGuan, Donghui; Zhang, Shiqiang; Ding, Yongjian; Liu, Shiyin

    2013-08-01

    Previous studies show that the area of a moraine-dammed lake can provide a good indicator of the significance of its outburst. For a glacier-dammed lake however, because its area and depth fluctuates with the melting of its ice dam, it is difficult to predict the outburst of the glacier-dammed lake by using its area alone.A characteristic of the surface of Lake Merzbacher is a large amount of floating ice therefore, a method is proposed in this article to extract the area of floating ice on the lake and the area of ice free water in the lake by using Environment and Disaster Monitoring Small Satellite images respectively. Furthermore, based on the area of floating ice extracted through the image information of Lake Merzbacher in 2009 and 2010, we determined the relationship between the ice area and the outburst of the lake, then formulated the Index for hazard of Glacier Lake Outburst Flood (IGLOF) of Lake Merzbacher, which cannot only predict the flood outburst, but also determine the specific outburst period after the lake drainage had occurred. This can be shown in a recalculation of the lake drainages in the years 2009 and 2010. Research results indicate that when IGLOF is less than 0.5 and the lake area is larger than 3 km2, the outburst process is in early-warning period and GLOF will occur in the next 5-8 days. Also, the successful outburst prediction of Lake Merzbacher in 2011 showed that the index described in this paper provides a quick methodology for forecasting and warning against Lake Merzbacher outburst floods. However,as our research was based on a short observation period (2009-2011) and also cannot be supplemented by other images, it will still be needed to be checked and validated by continuous observation and improvement in future.

  19. Deflation and Meteorite Exposure on Playa Lakes in the Southwestern United States: Unpaired Meteorites at Lucerne Dry Lake, California

    NASA Astrophysics Data System (ADS)

    Verish, Robert S.; Rubin, Alan E.; Moore, Carleton B.; Oriti, Ronald A.

    2000-01-01

    Numerous dry lakes (playas) dot the Mojave Desert in Southern California and adjacent desert regions in Nevada and Arizona. Most have been significantly affected by deflation processes aided by the lack of protective vegetation and occurrence of fine-grained sediments. Meteorites have been found on several playas including Lucerne Dry Lake,Rogers (formerly Muroc) Dry Lake, Rosamond Dry Lake, Roach Dry Lake, Alkali Dry Lake, and an unnamed dry lake near the town of Bonnie Claire in Nye County, Nevada. Unpaired meteorites have been found near one another on the same playa. Since 1963, 17 meteorite specimens (1.2-37.4 g), collectively called Lucerne Valley, have been found on Lucerne Dry Lake. Most appear to be completely covered with fusion crust, suggesting that their small size is due to fragmentation in the atmosphere and not to terrestrial weathering. The collection of meteorites on Lucerne Dry Lake is aided by the paucity of terrestrial rocks coarser than small pebbles; this is unusual for dry lakes in the region. Sixteen of the meteorite specimens from Lucerne Dy Lake were available for analysis.

  20. A coupled lake-atmosphere model (CLAM) and its application to Lake Kinneret

    NASA Astrophysics Data System (ADS)

    Pan, Hai

    1999-08-01

    Kinneret is a 166-km2 lake located in Northern Israel, in the central part of the Jordan Valley, a corridor running from north to south, between the Galilee hills in the west and the Golan Heights in the east. Both the Galilee hills and the Golan Heights reach an elevation of about 400 m above mean sea level (MSL), and the lake is about -210 m (MSL). North of the lake is the mountainous area of the Hermon, culminating at about 2800 m (MSL). About 120 km south of it is the Dead Sea, which is about -410 m (MSL), and about 45 km west of it is the Mediterranean Sea. The complexity of the terrain, combined with relatively arid soil and various ground covers surrounding the lake, results in a very complicated system of atmospheric and lake processes. To understand this system, especially the processes affecting the atmosphere and lake dynamics and thermodynamics, and their effects on Lake Kinneret evaporation, a coupled lake-atmosphere model (CLAM) was developed and applied to the lake region. The CLAM is based on the Regional Atmospheric Modeling System (RAMS) and the oceanic S-coordinate Rutgers University Model (SCRUM). Energy, mass, and momentum are conserved at the interface between the atmosphere and the lake, and appropriate balance equations are applied there. In the atmospheric module, two nested grids are employed to simulate Northern Israel at a resolution of 4 x 4 km2, and the near-lake region at a resolution of 1 x 1 km 2. Synoptic conditions obtained from the National Meteorological Center (NMC) reanalysis are assimilated by the model. Soil moisture, which appears to have a significant impact on atmospheric circulation in this region, was transformed from the normalized difference vegetation index (NDVI). Observations collected during two summers above and inside the lake emphasize the good capability of CLAM to simulate surface fluxes and other microclimatic conditions, as well as lake temperature and currents. Although the lake is small (about 12-km wide

  1. Effects of Land Management Practices on Water Quality in Mississippi Delta Oxbow Lakes: Biochemical and Microbiological Aspects

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Mississippi Delta Management Systems Evaluation Area (MSEA) project was designed to assess the effects of land management practices on water quality in three small oxbow lake watersheds; Thighman (1497 ha, 9 ha lake); Beasley (850 ha, 25 ha lake); and Deep Hollow (202 ha, 8 ha lake). Results fr...

  2. Effects of land management practices on water quality in Mississippi Delta Oxbow Lakes: biochemical and microbiological aspects

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Mississippi Delta Management Systems Evaluation Area (MSEA) project assessed the effects of land management practices on water quality in three small oxbow lake watersheds; Thighman (1497 ha, 9 ha lake); Beasley (850 ha, 25 ha lake); and Deep Hollow (202 ha, 8 ha lake). During 2000-2003 monthly...

  3. Hydrological and solute budgets of Lake Qinghai, the largest lake on the Tibetan Plateau

    SciTech Connect

    Jin, Zhangdong; You, Chen-Feng; Wang, Yi; Shi, Yuewei

    2009-12-04

    Water level and chemistry of Lake Qinghai are sensitive to climate changes and are important for paleoclimatic implications. An accurate understanding of hydrological and chemical budgets is crucial for quantifying geochemical proxies and carbon cycle. Published results of water budget are firstly reviewed in this paper. Chemical budget and residence time of major dissolved constituents in the lake are estimated using reliable water budget and newly obtained data for seasonal water chemistry. The results indicate that carbonate weathering is the most important riverine process, resulting in dominance of Ca 2+ and DIC for river waters and groundwater. Groundwater contribution to major dissolved constituents is relatively small (4.2 ± 0.5%). Wet atmospheric deposition contributes annually 7.4–44.0% soluble flux to the lake, resulting from eolian dust throughout the seasons. Estimates of chemical budget further suggest that (1) the Buha-type water dominates the chemical components of the lake water, (2) Na+, Cl-, Mg 2+ , and K+ in lake water are enriched owing to their conservative behaviors, and (3) precipitation of authigenic carbonates (low-Mg calcite, aragonite, and dolomite) transits quickly dissolved Ca 2+ into the bottom sediments of the lake, resulting in very low Ca 2+ in the lake water. Therefore, authigenic carbonates in the sediments hold potential information on the relative contribution of different solute inputs to the lake and the lake chemistry in the past.

  4. Use of egg traps to investigate lake trout spawning in the Great Lakes

    USGS Publications Warehouse

    Schreiner, Donald R.; Bronte, Charles R.; Payne, N. Robert; Fitzsimons, John D.; Casselman, John M.

    1995-01-01

    Disk-shaped traps were used to examine egg deposition by lake trout (Salvelinus namaycush) at 29 sites in the Great Lakes. The main objectives were to; first, evaluate the disk trap as a device for sampling lake trout eggs in the Great Lakes, and second, summarize what has been learned about lake trout spawning through the use of disk traps. Of the 5,085 traps set, 60% were classified as functional when retrieved. Evidence of lake trout egg deposition was documented in each of the lakes studied at 14 of 29 sites. A total of 1,147 eggs were trapped. The percentage of traps functioning and catch per effort were compared among sites based on depth, timing of egg deposition, distance from shore, size of reef, and type of reef (artificial or natural). Most eggs were caught on small, shallow, protected reefs that were close to shore. Use of disk traps on large, shallow, unprotected offshore reefs or along unprotected shorelines was generally unsuccessful due to the effects of heavy wind and wave action. Making multiple lifts at short intervals, and retrieval before and re-deployment after storms are recommended for use in exposed areas. On large reefs, preliminary surveys to identify preferred lake trout spawning habitat may be required to deploy disk traps most effectively. Egg deposition by hatchery-reared fish was widespread throughout the Great Lakes, and the use of artificial structures by these fish was extensive.

  5. Using a Hydrodynamic Lake Model to Predict the Impact of Avalanche Events at Lake Palcacocha, Peru

    NASA Astrophysics Data System (ADS)

    Chisolm, R. E.; Somos-Valenzuela, M. A.; McKinney, D. C.; Hodges, B. R.

    2013-12-01

    Accelerated retreat of Andean glaciers in recent decades due to a warming climate has caused the emergence and growth of glacial lakes. As these lakes continue to grow, they pose an increasing risk of glacial lake outburst floods (GLOFs). GLOFs can be triggered by moraine failures or by avalanches, rockslides, or ice calving into glacial lakes. Many of the processes influencing GLOF risk are still poorly understood. For many decades Lake Palcacocha in the Cordillera Blanca, Peru has posed a threat to citizens living in the watershed below, including the city of Huaraz which was devastated by a GLOF in 1941. A safety system for Lake Palcacocha was put in place in the 1970's to control the lake level with a tunnel and reinforced dyke, but the lake has since grown to the point where the lake is once again dangerous. Overhanging ice from the Palcaraju glacier and a relatively low freeboard level make the lake vulnerable to avalanches and landslides. A siphon system has been put in place to lower the lake below the level of the tunnel, but this system is temporary and the potential reduction in the water level is limited. Lake Palcacocha is used as a case study to investigate the impact of an avalanche event on the lake dynamics and the ensuing flood hydrograph. Empirical equations are used to determine the initial wave characteristics of an impulse wave created by three different avalanche scenarios that represent small, medium and large events. The characteristics of the initial impulse wave are used as inputs to a three-dimensional hydrodynamic model to predict the wave propagation across the lake and the moraine overtopping volume. The results from this model will be used as inputs to a downstream GLOF model to predict the impact from an outburst flood event. Additionally several scenarios are considered to evaluate the downstream impact from avalanche events with a reduction in the lake level. Use of a robust three-dimensional hydrodynamic lake model enables more

  6. Diel Surface Temperature Range Scales with Lake Size.

    PubMed

    Woolway, R Iestyn; Jones, Ian D; Maberly, Stephen C; French, Jon R; Livingstone, David M; Monteith, Donald T; Simpson, Gavin L; Thackeray, Stephen J; Andersen, Mikkel R; Battarbee, Richard W; DeGasperi, Curtis L; Evans, Christopher D; de Eyto, Elvira; Feuchtmayr, Heidrun; Hamilton, David P; Kernan, Martin; Krokowski, Jan; Rimmer, Alon; Rose, Kevin C; Rusak, James A; Ryves, David B; Scott, Daniel R; Shilland, Ewan M; Smyth, Robyn L; Staehr, Peter A; Thomas, Rhian; Waldron, Susan; Weyhenmeyer, Gesa A

    2016-01-01

    Ecological and biogeochemical processes in lakes are strongly dependent upon water temperature. Long-term surface warming of many lakes is unequivocal, but little is known about the comparative magnitude of temperature variation at diel timescales, due to a lack of appropriately resolved data. Here we quantify the pattern and magnitude of diel temperature variability of surface waters using high-frequency data from 100 lakes. We show that the near-surface diel temperature range can be substantial in summer relative to long-term change and, for lakes smaller than 3 km2, increases sharply and predictably with decreasing lake area. Most small lakes included in this study experience average summer diel ranges in their near-surface temperatures of between 4 and 7°C. Large diel temperature fluctuations in the majority of lakes undoubtedly influence their structure, function and role in biogeochemical cycles, but the full implications remain largely unexplored. PMID:27023200

  7. Diel Surface Temperature Range Scales with Lake Size

    PubMed Central

    Woolway, R. Iestyn; Jones, Ian D.; Maberly, Stephen C.; French, Jon R.; Livingstone, David M.; Monteith, Donald T.; Simpson, Gavin L.; Thackeray, Stephen J.; Andersen, Mikkel R.; Battarbee, Richard W.; DeGasperi, Curtis L.; Evans, Christopher D.; de Eyto, Elvira; Feuchtmayr, Heidrun; Hamilton, David P.; Kernan, Martin; Krokowski, Jan; Rimmer, Alon; Rose, Kevin C.; Rusak, James A.; Ryves, David B.; Scott, Daniel R.; Shilland, Ewan M.; Smyth, Robyn L.; Staehr, Peter A.; Thomas, Rhian; Waldron, Susan; Weyhenmeyer, Gesa A.

    2016-01-01

    Ecological and biogeochemical processes in lakes are strongly dependent upon water temperature. Long-term surface warming of many lakes is unequivocal, but little is known about the comparative magnitude of temperature variation at diel timescales, due to a lack of appropriately resolved data. Here we quantify the pattern and magnitude of diel temperature variability of surface waters using high-frequency data from 100 lakes. We show that the near-surface diel temperature range can be substantial in summer relative to long-term change and, for lakes smaller than 3 km2, increases sharply and predictably with decreasing lake area. Most small lakes included in this study experience average summer diel ranges in their near-surface temperatures of between 4 and 7°C. Large diel temperature fluctuations in the majority of lakes undoubtedly influence their structure, function and role in biogeochemical cycles, but the full implications remain largely unexplored. PMID:27023200

  8. Dynamics of organic carbon stock of Estonian arable and grassland peat soils

    NASA Astrophysics Data System (ADS)

    Kauer, Karin; Tammik, Kerttu; Penu, Priit

    2016-04-01

    Peat soils represent globally a major reserve of soil organic carbon (SOC). Estimation of changes in SOC stocks is important for understanding soil carbon sequestration and dynamics of greenhouse gas emissions. The aim of this study was to estimate the SOC stock of Estonian agricultural peat soils and SOC stock change depending on land use type (arable land and long-term grasslands (over 5 years)). The soils were classified as Histosols according to WRB classification. Generally the arable land was used for growing cereals, oilseed rape, legumes and used as ley in crop rotation. The main technique of soil cultivation was ploughing. During 2002-2015 the soil samples of 0-20 cm soil layer (one average soil sample per 1-5 ha) were collected. The SOC content was measured by NIRS method. The SOC stock was calculated by assuming that soil mean bulk density is 0.3 g cm-3. The SOC stock change in arable land was estimated during 3-13 years (N=91) and in grassland 4-13 year (N=163). The average SOC content of peat soils varied from 150.6 to 549.0 mg g-1. The initial SOC stock of arable land was 271.3 t ha-1 and of grassland 269.3 t ha-1. The SOC stock declined in arable peat soils faster (-2.57 t ha-1 y-1) compared to the changes in grassland peat soils (-0.67 t ha-1 y-1). According to the length of the study period the SOC stock change per year varied from -5.14 to 6.64 t ha-1 y-1 in grasslands and from -14.78 to 0.83 t ha-1 y-1 in arable land, although there was no clear relationship between the SOC stock change and the length of the study period. More detailed information about the properties of agricultural land and land use history is needed to analyse the causes of the SOC stock changes in agricultural peat soils. However, from the current research we can conclude that the SOC stock of arable and grassland peat soils is declining during the cultivation. These decreases are important to specify when considering the role of peat soils in atmospheric greenhouse gas

  9. Significant fraction of CO2 emissions from boreal lakes derived from hydrologic inorganic carbon inputs

    NASA Astrophysics Data System (ADS)

    Weyhenmeyer, Gesa A.; Kosten, Sarian; Wallin, Marcus B.; Tranvik, Lars J.; Jeppesen, Erik; Roland, Fabio

    2015-12-01

    Annual CO2 emissions from lakes and other inland waters into the atmosphere are estimated to almost entirely compensate the total annual carbon uptake by oceans. CO2 supersaturation in lakes, which results in CO2 emissions, is frequently attributed to CO2 produced within the lake. However, lateral inorganic carbon flux through watersheds can also be sizeable. Here we calculated lake surface water CO2 concentrations and emissions using lake pH, alkalinity and temperature from a compilation of data from 5,118 boreal lakes. Autumn surface water CO2 concentrations and CO2 emissions from the 5,118 lakes co-varied with lake internal autumn CO2 production. However, using a mass balance approach we found that CO2 emission in the majority of lakes was sustained by inorganic carbon loading from the catchment rather than by internal CO2 production. Small lakes with high dissolved organic carbon and phosphorus concentrations, shorter retention times and longer ice-free seasons had the highest CO2 concentrations. CO2 emissions from these small lakes was twice that of comparable lakes in colder regions, and similar to emissions from subtropical and tropical lakes. We conclude that changes in land use and climate that increase dissolved inorganic carbon may cause emission levels from boreal lakes to approach those of lakes in warmer regions.

  10. Estimating lake-atmosphere CO2 exchange

    USGS Publications Warehouse

    Anderson, D.E.; Striegl, R.G.; Stannard, D.I.; Michmerhuizen, C.M.; McConnaughey, T.A.; LaBaugh, J.W.

    1999-01-01

    Lake-atmosphere CO2 flux was directly measured above a small, woodland lake using the eddy covariance technique and compared with fluxes deduced from changes in measured lake-water CO2 storage and with flux predictions from boundary-layer and surface-renewal models. Over a 3-yr period, lake-atmosphere exchanges of CO2 were measured over 5 weeks in spring, summer, and fall. Observed springtime CO2 efflux was large (2.3-2.7 ??mol m-2 s-1) immediately after lake-thaw. That efflux decreased exponentially with time to less than 0.2 ??mol m-2 s-1 within 2 weeks. Substantial interannual variability was found in the magnitudes of springtime efflux, surface water CO2 concentrations, lake CO2 storage, and meteorological conditions. Summertime measurements show a weak diurnal trend with a small average downward flux (-0.17 ??mol m-2 s-1) to the lake's surface, while late fall flux was trendless and smaller (-0.0021 ??mol m-2 s-1). Large springtime efflux afforded an opportunity to make direct measurement of lake-atmosphere fluxes well above the detection limits of eddy covariance instruments, facilitating the testing of different gas flux methodologies and air-water gas-transfer models. Although there was an overall agreement in fluxes determined by eddy covariance and those calculated from lake-water storage change in CO2, agreement was inconsistent between eddy covariance flux measurements and fluxes predicted by boundary-layer and surface-renewal models. Comparison of measured and modeled transfer velocities for CO2, along with measured and modeled cumulative CO2 flux, indicates that in most instances the surface-renewal model underpredicts actual flux. Greater underestimates were found with comparisons involving homogeneous boundary-layer models. No physical mechanism responsible for the inconsistencies was identified by analyzing coincidentally measured environmental variables.

  11. Earthquake-triggered landslides form lakes in New Zealand

    USGS Publications Warehouse

    1981-01-01

    Eleven small lakes were formed by landslides caused by the 1929 Buller earthquake in New Zealand; four others were formed by other historic earthquakes in this country.  At least nine other New Zealand lakes are dammed by landslides and were probably formed by prehistoric earthquakes.  Earthquake-dammed lakes could provide an estimate of paleoseimicity for the past few hundred or thousand years.

  12. Lake Nasser and Toshka Lakes, Egypt

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Lake Nasser (center) and the Toshka Lakes (center left) glow emerald green and black in this MODIS true-color image acquired March 8, 2002. Located on and near the border of Egypt and Norther Sudan, these lakes are an oasis of water in between the Nubian (lower right) and Libyan Deserts (upper left). Also visible are the Red Sea (in the upper right) and the Nile River (running north from Lake Nasser). Credit: Jacques Descloitres, MODIS Land Rapid Response Team, NASA/GSFC

  13. Hydrologic reconnaissance of Tsala Apopka Lake, Citrus County, Florida

    USGS Publications Warehouse

    Rutledge, A.T.

    1977-01-01

    The swamps, marshes, and open waters of Tsala Apopka Lake, Florida, were mapped and the hydrologic connection between the lake and the Floridan limestone aquifer was studied from October 1975 to September 1976. Tsala Apopka Lake is a series of shallow , interconnected lakes, ponds, and marshes whose water surface slopes northward at 0.5 foot per mile. According to aerial photographs of December 1972, only 6 percent of the 103 square miles of study area is covered by open water. Open water is abundant along the western side of the lake, dense and sparse marshes occupy most of the lake area, and swamps occupy a thick zone around the Withlacoochee River which borders the lake to the east. Only a small fraction of the total surface flow occurs through the lake. The average lake outflow through S-351 canal is 23.6 cfs; while the average river flow at Holder is 714 cfs. Tsala Apopka Lake is hydraulically connected to the Floridan aquifer. At low flow, the major source of water in the river is ground water from the Floridan aquifer. The specific conductance of water in the Floridan aquifer averages 250-350 umho/cm (micromhos per centimeter) at 25C in this area. The specific conductance of water in the Withlacoochee River near Holder averages 268 umho/cm at 25C, while water in Tsala Apopka Lake at Hernando averages 139 umho/cm at 25C. (Woodard-USGS)

  14. Lava Lakes in Io's Paterae

    NASA Astrophysics Data System (ADS)

    Radebaugh, J.; McEwen, A. S.; Milazzo, M.; Davies, A. G.; Keszthelyi, L. P.; Geissler, P.

    2002-05-01

    New Galileo images and Galileo and Cassini temperature data lend credence to previous proposals that some of the paterae on Io contain lava lakes, similar in some ways to those observed on Earth. Galileo's October 2001 I32 flyby produced spectacular new high resolution observations of Io's paterae, their margins, and floors. Images reveal where lavas have filled Emakong Patera and overtopped its margins. Landslides from the peaks of Tohil Mons are not present on the adjacent floor of a dark patera, perhaps because they have slumped into a molten lava pit. Dark lavas have filled and drained back from colorful Tupan Patera, leaving a ring of material on its walls. This patera also shows evidence of interaction between molten sulfur and silicate lavas, a relationship observed at the terrestrial Poas Volcano (Francis et al., 1980, Nature 283, 754-756; Oppenheimer and Stevenson, 1990, La Recherche 21,1088-1090). The extremely uniformly dark materials in many other paterae could also be lava lakes. Pele Volcano on Io, in particular, has previously been considered a lava lake based on several characteristics (Davies et al., 2001, JGR 106,33,079-33,103). Recent analyses of eclipse images of Pele from Cassini reveal average temperatures of 1375 K, with variations on short (~10 minute) timescales, consistent with active fountaining in a lava lake. Similar oscillations around high temperatures over these time scales are seen in terrestrial lava lakes, such as at Kupaianaha (Flynn et al., GRL, 19,6461-6476, 1993) and Erta Ale (Bessard, Caillet and others, in progress). Nightside high resolution (60 m/pixel) images from Galileo I32 reveal a region of overturning and convection, with some areas reaching in excess of 1800 K, verifying very high-temperature components identified in high-resolution NIMS data (Lopes et al., 2001, JGR, 106, 33,053-33,078). This region is ringed with small hotspots, comparable to locations of breakup and fountaining at the margins of many terrestrial

  15. Morphology and biology of Cyclops scutifer Sars, 1863 in high mountain lakes of East Siberia (including Lake Amut)

    NASA Astrophysics Data System (ADS)

    Sheveleva, Natalya G.; Itigilova, Mydygma Ts.; Chananbaator, Ayushcuren

    2016-04-01

    Data on zooplankton from 13 high-mountain lakes of East Siberia have shown that the Holarctic copepod Cyclops scutifer Sars, 1863 dominates among crustaceans. In July, its abundance comprised 64%-98% of the total plankton fauna in the pelagial of these lakes, approximately 30% in the littoral zone and 10% in small northern thermokarst lakes. Biometric measurements and morphological descriptions based on scanning microscope images are supplemented by the data on its geographic distribution and phenology.

  16. Comparing Effects of Lake- and Watershed-Scale Influences on Communities of Aquatic Invertebrates in Shallow Lakes

    PubMed Central

    Hanson, Mark A.; Herwig, Brian R.; Zimmer, Kyle D.; Fieberg, John; Vaughn, Sean R.; Wright, Robert G.; Younk, Jerry A.

    2012-01-01

    Constraints on lake communities are complex and are usually studied by using limited combinations of variables derived from measurements within or adjacent to study waters. While informative, results often provide limited insight about magnitude of simultaneous influences operating at multiple scales, such as lake- vs. watershed-scale. To formulate comparisons of such contrasting influences, we explored factors controlling the abundance of predominant aquatic invertebrates in 75 shallow lakes in western Minnesota, USA. Using robust regression techniques, we modeled relative abundance of Amphipoda, small and large cladocera, Corixidae, aquatic Diptera, and an aggregate taxon that combined Ephemeroptera-Trichoptera-Odonata (ETO) in response to lake- and watershed-scale characteristics. Predictor variables included fish and submerged plant abundance, linear distance to the nearest wetland or lake, watershed size, and proportion of the watershed in agricultural production. Among-lake variability in invertebrate abundance was more often explained by lake-scale predictors than by variables based on watershed characteristics. For example, we identified significant associations between fish presence and community type and abundance of small and large cladocera, Amphipoda, Diptera, and ETO. Abundance of Amphipoda, Diptera, and Corixidae were also positively correlated with submerged plant abundance. We observed no associations between lake-watershed variables and abundance of our invertebrate taxa. Broadly, our results seem to indicate preeminence of lake-level influences on aquatic invertebrates in shallow lakes, but historical land-use legacies may mask important relationships. PMID:22970275

  17. Lakes Ecosystem Services Online

    EPA Science Inventory

    Northeastern lakes provide valuable ecosystem services that benefit residents and visitors and are increasingly important for provisioning of recreational opportunities and amenities. Concurrently, however, population growth threatens lakes by, for instance, increasing nutrient ...

  18. Utah: Salt Lake Region

    Atmospheric Science Data Center

    2014-05-15

    article title:  Winter and Summer Views of the Salt Lake Region     View Larger Image Magnificent views of the region surrounding Salt Lake City, Utah are captured in these winter and summer images from the ...

  19. Lake trout rehabilitation in Lake Ontario

    USGS Publications Warehouse

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

    1995-01-01

    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.

  20. Lake salinity variations resulting from wind direction, Gobi Desert, China

    NASA Astrophysics Data System (ADS)

    Bradley, D. C.; Cartwright, I.; Currell, M.

    2010-12-01

    The southern reaches of the Gobi desert, central China, host a large number (~50) of shallow (<3m depth), narrow, north-south trending through-flow lakes. The size of the sand dunes (many over 150m) in this area means that the valleys between the largest dunes can intersect with the water table. The resultant lakes are of particular interest, not only because they are host to a number of unique ecosystems, including several rare species, but also because they are very susceptible to environmental disturbances. Physical development of the lakes is a clear threat, but also small scale withdrawal of groundwater in proximity to the lakes can cause a drop in the water table, forcing it below the lake floor, and consequently causing many lakes to dry up. Due to their inaccessibility, many of these lakes have remained relatively untouched by development, and only those lakes closest to the eastern edge of the desert have been utilized directly for either salt harvesting or tourism. This paper reports on research from both pristine and developed lakes, and reveals a higher TDS (20-50mS/cm compared to 0.5-5mS/cm) in the northern end relative to the southern end for undisturbed lakes. Water entering the southern end of the lakes is chemically identical to the local groundwater (TDS ~0.5mS/cm). This geographic difference in lake properties is remarkable, not only in terms of chemical variation, but also in terms of plant variety and abundance. Stable isotopes show a clear evaporation trend for these lakes, increasing from the southern tip, to the northern tip of individual lakes (-3 to -1‰ in the south, compared with 2-8‰ in the north, and -6 to -3‰ in the groundwater for δ2H). TDS likewise increases with increasing isotopic fractionation. The primary wind direction fluctuates from the southeast to the east, causing the movement of water from the southern end of the lake to the northern, and aiding in the evaporation. Once at the northern end of the lake, the water

  1. A survey of parentally reported sleep health disorders in estonian 8–9 year old children

    PubMed Central

    2013-01-01

    Background Pediatric sleep research is rather new in Estonia. There has not been a comprehensive study of age specific sleep disorders in Estonian children. The aim of this study was to investigate sleep disorders in a sample of Estonian second grade children. We hypothesized that: • Children with low BMI are as susceptible to SDB as are children with high BMI. • Under weight children are susceptible to residual SDB after adenotonsillectomy. • Parasomnias present with SDB in children. • Excessive day time sleepiness is a significant symptom which leads parents to suspect sleep disorders in their child. Methods A retrospective questionnaire based survey was used to analyze factors influencing sleep, parasomnias, daytime sleepiness, and sleep disordered breathing (SDB). 1065 Pediatric Sleep Questionnaire (PSQ) packets were distributed by post to randomly selected parents of second grade students; 703 (66%) subjects were included in the study group; each parent/guardian participant had one second grade child. Descriptive statistics were used to compare characteristics of SDB symptomatic and healthy children. We used logistic regression to analyze factors influencing sleep and parasomnias in relation to SDB severity. Odds ratios (OR) and 95% CI were used to estimate relative risk. Results Parents of children with SDB complaints seem to pay attention to sleep disorders especially when a child is suffering from excessive day time sleepiness. Parasomnias are present simultaneously with SDB and tend to worsen in relation to more severe SDB complaints. Many underweight children have SDB symptoms after adenotonsillectomy. Conclusion SDB symptoms are found in both overweight and underweight children. Both groups should be observed, especially in terms of the current focus on overweight children. Careful follow up after SDB treatment is necessary in case of under and overweight children. Parental suspicions regarding SDB are noticeably higher in cases of

  2. Linkage between Three Gorges Dam impacts and the dramatic recessions in China’s largest freshwater lake, Poyang Lake

    NASA Astrophysics Data System (ADS)

    Mei, Xuefei; Dai, Zhijun; Du, Jinzhou; Chen, Jiyu

    2015-12-01

    Despite comprising a small portion of the earth’s surface, lakes are vitally important for global ecosystem cycling. However, lake systems worldwide are extremely fragile, and many are shrinking due to changing climate and anthropogenic activities. Here, we show that Poyang Lake, the largest freshwater lake in China, has experienced a dramatic and prolonged recession, which began in late September of 2003. We further demonstrate that abnormally low levels appear during October, 28 days ahead of the normal initiation of the dry season, which greatly imperiled the lake’s wetland areas and function as an ecosystem for wintering waterbirds. An increase in the river-lake water level gradient induced by the Three Gorges Dam (TGD) altered the lake balance by inducing greater discharge into the Changjiang River, which is probably responsible for the current lake shrinkage. Occasional episodes of arid climate, as well as local sand mining, will aggravate the lake recession crisis. Although impacts of TGD on the Poyang Lake recession can be overruled by episodic extreme droughts, we argue that the average contributions of precipitation variation, human activities in the Poyang Lake catchment and TGD regulation to the Poyang Lake recession can be quantified as 39.1%, 4.6% and 56.3%, respectively.

  3. Linkage between Three Gorges Dam impacts and the dramatic recessions in China’s largest freshwater lake, Poyang Lake

    PubMed Central

    Mei, Xuefei; Dai, Zhijun; Du, Jinzhou; Chen, Jiyu

    2015-01-01

    Despite comprising a small portion of the earth’s surface, lakes are vitally important for global ecosystem cycling. However, lake systems worldwide are extremely fragile, and many are shrinking due to changing climate and anthropogenic activities. Here, we show that Poyang Lake, the largest freshwater lake in China, has experienced a dramatic and prolonged recession, which began in late September of 2003. We further demonstrate that abnormally low levels appear during October, 28 days ahead of the normal initiation of the dry season, which greatly imperiled the lake’s wetland areas and function as an ecosystem for wintering waterbirds. An increase in the river-lake water level gradient induced by the Three Gorges Dam (TGD) altered the lake balance by inducing greater discharge into the Changjiang River, which is probably responsible for the current lake shrinkage. Occasional episodes of arid climate, as well as local sand mining, will aggravate the lake recession crisis. Although impacts of TGD on the Poyang Lake recession can be overruled by episodic extreme droughts, we argue that the average contributions of precipitation variation, human activities in the Poyang Lake catchment and TGD regulation to the Poyang Lake recession can be quantified as 39.1%, 4.6% and 56.3%, respectively. PMID:26657816

  4. Satellite monitoring of dramatic changes at Hawai'i's only alpine lake: Lake Waiau on Mauna Kea volcano

    USGS Publications Warehouse

    Patrick, Matthew R.; Kauahikaua, James P.

    2015-01-01

    Lake Waiau is a small, typically 100-meter-long lake, located near the summit of Mauna Kea volcano, on the Island of Hawaiʻi. It is Hawaiʻi’s only alpine lake and is considered sacred in Hawaiian cultural tradition. Over the past few years, the lake has diminished in size, and, by October 2013, surface water had almost completely disappeared from the lake. In this study, we use high-resolution satellite images and aerial photographs to document recent changes at the lake. Based on our reconstructions covering the past 200 years, the historical lake surface area has typically ranged from 5,000 to 7,000 square meters, but in 2010 a dramatic plunge in lake area ensued. The lake area rebounded significantly in early 2014, following heavy winter storms. This near disappearance of the lake, judging from analysis of visitor photographs and field reports, appears to be highly unusual, if not unprecedented, in the historical record. The unusually low water levels in the lake are consistent with a recent severe drought in Hawaiʻi.

  5. Egg thiamine status of Lake Ontario salmonines 1995-2004 with emphasis on lake trout

    USGS Publications Warehouse

    Fitzsimons, J.D.; Williston, B.; Williston, G.; Brown, L.; El-Shaarawi, A.; Vandenbyllaardt, L.; Honeyfeld, D.; Tillitt, D.; Wolgamood, M.; Brown, S.B.

    2007-01-01

    Alewives (Alosa pseudoharengus), the major prey fish for Lake Ontario, contain thiaminase. They are associated with development of a thiamine deficiency in salmonines which greatly increases the potential for developing an early mortality syndrome (EMS). To assess the possible effects of thiamine deficiency on salmonine reproduction we measured egg thiamine concentrations for five species of Lake Ontario salmonines. From this we estimated the proportion of families susceptible to EMS based on whether they were below the ED20, the egg thiamine concentration associated with 20% mortality due to EMS. The ED20s were 1.52, 2.63, and 2.99 nmol/g egg for Chinook salmon (Oncorhynchus tshawytscha), lake trout (Salvelinus namaycush), and coho salmon (Oncorhynchus kisutch), respectively. Based on the proportion of fish having egg thiamine concentrations falling below the ED20, the risk of developing EMS in Lake Ontario was highest for lake trout, followed by coho (O. kisutch), and Chinook salmon, with the least risk for rainbow trout (O. mykiss). For lake trout from western Lake Ontario, mean egg thiamine concentration showed significant annual variability during 1994 to 2003, when the proportion of lake trout at risk of developing EMS based on ED20 ranged between 77 and 100%. Variation in the annual mean egg thiamine concentration for western Lake Ontario lake trout was positively related (p < 0.001, r2 = 0.94) with indices of annual adult alewife biomass. While suggesting the possible involvement of density-dependent changes in alewives, the changes are small relative to egg thiamine concentrations when alewife are not part of the diet and are of insufficient magnitude to allow for natural reproduction by lake trout.

  6. Effects of the 1980 eruption of Mount St Helens on the limnological characteristics of selected lakes in western Washington

    USGS Publications Warehouse

    Embrey, S.S.; Dion, N.P.

    1988-01-01

    The 1980 eruption of Mount St. Helens provided the opportunity to study its effect on the physical, chemical, and biological characteristics of lakes near the volcano, and to describe two newly created lakes. Concentrations of dissolved solids and organic carbon, measured in June 1980, had increased from 2 to 30 times those observed in the 1970 's in Spirit, St. Helens, and Venus Lakes. Water in the lakes was altered from preeruption calcium-bicarbonate types to calcium-sulfate, calcium sulfate-chloride, or lake surface, as in St. Helens Lake; transparency in Venus Lake had improved to a depth of 24 ft by 1982. Spirit Lake was anoxic into fall 1980, but had reaerated to 5.2 mg/L of dissolved oxygen by May 1981. Phytoplankton communities in existing lakes in the blast zone in 1980 were primarily green and bluegreen algae; diatoms were sparse until summer 1982. Small numbers of zooplankton in Spirit, St. Helens, and Venus Lakes, compared to numbers in Walupt and Fawn Lakes, may indicate some post-eruption mortality. Rotifers were absent from lakes in the blast zone, but by 1981 were observed in all the lakes. The recovery of the physical, chemical, and biological characteristics of the lakes will depend on stabilization of the surrounding environment and biological processes within each lake. Excluding Spirit Lake, it is estimated that St. Helens Lake would be the slowest to recover and Venus Lake the fastest. (USGS)

  7. Plasma steroid concentrations and male phallus size in juvenile alligators from seven Florida lakes

    USGS Publications Warehouse

    Guillette, L.J., Jr.; Woodward, A.R.; Crain, D.A.; Pickford, D.B.; Rooney, A.A.; Percival, H.F.

    1999-01-01

    Neonatal and juvenile alligators from contaminated Lake Apopka in central Florida exhibit abnormal plasma sex steroid concentrations as well as morphological abnormalities of the gonad and phallus. This study addresses whether similar abnormalities occur in juvenile alligators inhabiting six other lakes in Florida. For analysis, animals were partitioned into two subsets, animals 40-79 cm total length (1-3 years old) and juveniles 80-130 cm total length (3-7 years old). Plasma testosterone (T) concentrations were lower in small males from lakes Apopka, Griffin, and Jessup than from Lake Woodruff National Wildlife Refuge (NWR). Similar differences were observed in the larger juveniles, with males from lakes Jessup, Apopka, and Okeechobee having lower plasma T concentrations than Lake Woodruff males. Plasma estradiol-17?? (E2) concentrations were significantly elevated in larger juvenile males from Lake Apopka compared to Lake Woodruff NWR. When compared to small juvenile females from Lake Woodruff NWR, females from lakes Griffin, Apopka, Orange, and Okeechobee had elevated plasma E2 concentrations. Phallus size was significantly smaller in males from lakes Griffin and Apopka when compared to males from Lake Woodruff NWR. An association existed between body size and phallus size on all lakes except Lake Apopka and between phallus size and plasma T concentration on all lakes except lakes Apopka and Orange. Multiple regression analysis, with body size and plasma T concentration as independent covariables, explained the majority of the variation in phallus size on all lakes. These data suggest that the differences in sex steroids and phallus size observed in alligators from Lake Apopka are not limited to that lake, nor to one with a history of a major pesticide spill. Further work examining the relationship of sex steroids and phallus size with specific biotic and abiotic factors, such as antiandrogenic or estrogenic contaminants, is needed.

  8. Lake Layers: Stratification.

    ERIC Educational Resources Information Center

    Brothers, Chris; And Others

    This teacher guide and student workbook set contains two learning activities, designed for fifth through ninth grade students, that concentrate on lake stratification and water quality. In the activities students model the seasonal temperature changes that occur in temperate lakes and observe the resulting stratification of lake waters. Students…

  9. Great Lakes: Chemical Monitoring

    ERIC Educational Resources Information Center

    Delfino, Joseph J.

    1976-01-01

    The Tenth Great Lakes Regional Meeting of the American Chemical Society met to assess current Chemical Research activity in the Great Lakes Basin, and addressed to the various aspects of the theme, Chemistry of the Great Lakes. Research areas reviewed included watershed studies, atmospheric and aquatic studies, and sediment studies. (BT)

  10. Great Minds? Great Lakes!

    ERIC Educational Resources Information Center

    Environmental Protection Agency, Chicago, IL. Great Lakes National Program Office.

    This book contains lesson plans that provide an integrated approach to incorporating Great Lakes environmental issues into elementary subjects. The book is divided into three subject areas: (1) History, which includes the origins of the Great Lakes, Great Lakes people, and shipwrecks; (2) Social Studies, which covers government, acid rain as a…

  11. A Killer Lake

    ERIC Educational Resources Information Center

    Horvath, Thomas

    2005-01-01

    In 1986, Lake Nyos, a volcanic lake in Cameroon, released a huge amount of carbon dioxide gas, killing over 1,700 people in the surrounding area. This case study, developed for use in a limnology or aquatic biology course, explores that event, introducing students to concepts relating to lake formation, thermal stratification, and dissolved gases.…

  12. Lake Effects: The Lake Superior Curriculum Guide.

    ERIC Educational Resources Information Center

    Beery, Tom; And Others

    This curriculum guide was launched in response to a need for Lake Superior-specific educational materials and contains lessons and activities that can be used to teach about Lake Superior. The lessons in this book are divided into four sections. Each of the first three sections has a background section that provides basic information about Lake…

  13. The Lakes and Seas of Titan

    NASA Astrophysics Data System (ADS)

    Hayes, Alexander G.

    2016-06-01

    Analogous to Earth's water cycle, Titan's methane-based hydrologic cycle supports standing bodies of liquid and drives processes that result in common morphologic features including dunes, channels, lakes, and seas. Like lakes on Earth and early Mars, Titan's lakes and seas preserve a record of its climate and surface evolution. Unlike on Earth, the volume of liquid exposed on Titan's surface is only a small fraction of the atmospheric reservoir. The volume and bulk composition of the seas can constrain the age and nature of atmospheric methane, as well as its interaction with surface reservoirs. Similarly, the morphology of lacustrine basins chronicles the history of the polar landscape over multiple temporal and spatial scales. The distribution of trace species, such as noble gases and higher-order hydrocarbons and nitriles, can address Titan's origin and the potential for both prebiotic and biotic processes. Accordingly, Titan's lakes and seas represent a compelling target for exploration.

  14. Evaluation of offshore stocking of Lake Trout in Lake Ontario

    USGS Publications Warehouse

    Lantry, B.F.; O'Gorman, R.; Strang, T.G.; Lantry, J.R.; Connerton, M.J.; Schanger, T.

    2011-01-01

    Restoration stocking of hatchery-reared lake trout Salvelinus namaycush has occurred in Lake Ontario since 1973. In U.S. waters, fish stocked through 1990 survived well and built a large adult population. Survival of yearlings stocked from shore declined during 1990–1995, and adult numbers fell during 1998–2005. Offshore stocking of lake trout was initiated in the late 1990s in response to its successful mitigation of predation losses to double-crested cormorants Phalacrocorax auritus and the results of earlier studies that suggested it would enhance survival in some cases. The current study was designed to test the relative effectiveness of three stocking methods at a time when poststocking survival for lake trout was quite low and losses due to fish predators was a suspected factor. The stocking methods tested during 2000–2002 included May offshore, May onshore, and June onshore. Visual observations during nearshore stockings and hydroacoustic observations of offshore stockings indicated that release methods were not a direct cause of fish mortality. Experimental stockings were replicated for 3 years at one site in the southwest and for 2 years at one site in the southeast. Offshore releases used a landing craft to transport hatchery trucks from 3 to 6 km offshore out to 55–60-m-deep water. For the southwest site, offshore stocking significantly enhanced poststocking survival. Among the three methods, survival ratios were 1.74 : 1.00 : 1.02 (May offshore : May onshore : June onshore). Although not statistically significant owing to the small samples, the trends were similar for the southeast site, with survival ratios of 1.67 : 1.00 : 0.72. Consistent trends across years and sites indicated that offshore stocking of yearling lake trout during 2000–2002 provided nearly a twofold enhancement in survival; however, this increase does not appear to be great enough to achieve the 12-fold enhancement necessary to return population abundance to restoration

  15. Modeling of subsurface geology in Medicine Lake, California

    SciTech Connect

    Rial, J.A.; Saltzman, N.

    1988-07-26

    In this document we present the results of our analysis of data from 16 three-component seismometers and 8 dynamite explosions around the Medicine Lake volcano's Glass Mountain in northern California. The Medicine Lake volcano is located just northeast of the southeastward-trending Cascade Range of shield and small composite volcanoes. 2 refs., 6 figs.

  16. SIMULATION OF DISSOLVED OXYGEN PROFILES IN A TRANSPARENT, DIMICTIC LAKE

    EPA Science Inventory

    Thrush Lake is a small, highly transparent lake in northeastern Minnesota. rom 1986 to 1991, vertical profiles of water temperature, dissolved oxygen, chlorophyll a concentration, underwater light irradiance, and Secchi depths were measured at monthly intervals during the ice-fre...

  17. KEITH LAKE HABITAT IMPROVEMENT STRUCTURES AND SALINITY GRADIENT MODEL MX964017

    EPA Science Inventory

    The Keith Lake / Salt Bayou system of wetlands is an important site for over-wintering waterfowl and for the protection of other fauna and flora in the region. Hydraulically-connected shallow lakes such as Keith Lake, along with small bayous, form a large wetland complex. Histor...

  18. 77 FR 63311 - Lake Clementine Hydro, LLC; Notice of Successive Preliminary Permit Application Accepted for...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-10-16

    ....2001(a)(1)(iii) and the instructions on the Commission's Web site http://www.ferc.gov/docs-filing... October 2, 2012, Lake Clementine Hydro, LLC (Lake Clementine Hydro) filed an application for a successive... study the feasibility of the Lake Clementine Small Hydroelectric Project to be located at the U.S....

  19. Limnological structure of Titan's hydrocarbon lakes and its astrobiological implication.

    PubMed

    Tokano, Tetsuya

    2009-03-01

    Cassini radar recently detected several putative liquid hydrocarbon lakes in the polar region of Saturn's moon Titan. Such lakes may contain organic sediments deposited from the atmosphere that would promote prebiotic-type chemistry driven by cosmic rays, the result of which could be the production of more complex molecules such as nitrogen-bearing organic polymer or azides. The physical properties of the lake and their temporal evolution under Titan's present climatic setting were investigated by means of a one-dimensional lake thermal stratification model. Lakes can undergo various evolutions, depending on the initial composition and depth of the lake and hydrocarbon abundance in the near-surface atmosphere. Pure methane ponds, which may occasionally form when heavy methane hailstones reach the surface, would be transitory in that they would evaporate, freeze up, and eventually dry up. On the other hand, lakes filled with a mixture of methane, ethane, and nitrogen would be more stable; and freezing or drying would not necessarily occur in most cases. Such lakes undergo a seasonal cycle of thermal stratification in spring and early summer and convective overturning in other seasons. The summer thermal stratification near the lake surface could be destabilized by bottom heating as a result of an enhanced geothermal heat flux, e.g., in the vicinity of cryovolcanoes. Most likely the composition of the lake and atmosphere would come to equilibrium by way of a small amount of evaporation, but the lake-atmosphere system could be repeatedly brought out of equilibrium by irregular precipitation. The viability of prebiotic-like chemistry in the lake may depend on many lake parameters, such as temperature, liquid or frozen state, and convective mixing. Moreover, convective mixing may drive suspension of solid acetylene and other sediments on the lake bottom and redistribution of dissolved gases, which might be relevant for putative life-forms that consume hydrogen and solid

  20. Exogenously produced CO2 doubles the CO2 efflux from three north temperate lakes

    NASA Astrophysics Data System (ADS)

    Wilkinson, Grace M.; Buelo, Cal D.; Cole, Jonathan J.; Pace, Michael L.

    2016-03-01

    It is well established that lakes are typically sources of CO2 to the atmosphere. However, it remains unclear what portion of CO2 efflux is from endogenously processed organic carbon or from exogenously produced CO2 transported into lakes. We estimated high-frequency CO2 and O2 efflux from three north temperate lakes in summer to determine the proportion of the total CO2 efflux that was exogenously produced. Two of the lakes were amended with nutrients to experimentally enhance endogenous CO2 uptake. In the unfertilized lake, 50% of CO2 efflux was from exogenous sources and hydrology had a large influence on efflux. In the fertilized lakes, endogenous CO2 efflux was negative (into the lake) yet exogenous CO2 made the lakes net sources of CO2 to the atmosphere. Shifts in hydrologic regimes and nutrient loading have the potential to change whether small lakes act primarily as reactors or vents in the watershed.

  1. Food of lake trout in Lake Superior

    USGS Publications Warehouse

    Dryer, William R.; Erkkila, Leo F.; Tetzloff, Clifford L.

    1965-01-01

    Stomachs were examined from 1,492 lake trout and 83 siscowets collected from Lake Superior. Data are given on the food of lake trout of legal size (17 inches or longer) by year, season, and depth of water, and on the relation between food and size among smaller lake trout. Fish contributed 96.7 to 99.9 per cent of the total volume of food in the annual samples. Ciscoes (Coregonus spp.) were most common (52.2 to 87.5 per cent of the volume) in 1950 to 1953 and American smelt ranked first (65.6 per cent of the volume) in 1963. Cottids were in 8.9 to 12.3 per cent of the stomachs in 1950 to 1953 but in only 4.3 per cent in 1963. Insects ranked second to fish in occurrence (9.6 per cent for the combined samples) and crustaceans followed at 3.9 per cent. The greatest seasonal changes in the food of lake trout were among fish caught at 35 fathoms and shallower. The occurrence of Coregonus increased from 34.6 per cent in February-March to 71.1 per cent in October-December. Smelt were in 76.9 per cent of the stomachs in February-March but in only 2.2 per cent in October-December. Cottids, Mysis relicta, and insects were most common in the July-September collections. Lake trout taken at depths greater than 35 fathoms had eaten a higher percentage of Cottidae and Coregonus than had those captured in shallower water. Smelt, ninespine sticklebacks, Mysis, and insects were more frequent in stomachs of lake trout from less than 35 fathoms. Crustaceans comprised more than 70 per cent of the total volume of food for 4.0- to 7.9-inch lake trout but their importance decreased as the lake trout grew larger. Pontoporeia affinis was the most common in the stomachs of 4.0- to 6.9-inch lake trout and Mysis held first rank at 7.0 to 12.9 inches. Ostracods were important only to 4.0- to 4.9-inch lake trout. As the lake trout became larger, the importance of fish grew from 4.4-per cent occurrence at 5.0 to 5.9 inches to 93.9 per cent at 16.0 to 16.9 inches. Smelt were most commonly eaten by

  2. Evaporation variability of Nam Co Lake in the Tibetan Plateau and its role in recent rapid lake expansion

    NASA Astrophysics Data System (ADS)

    Ma, Ning; Szilagyi, Jozsef; Niu, Guo-Yue; Zhang, Yinsheng; Zhang, Teng; Wang, Binbin; Wu, Yanhong

    2016-06-01

    Previous studies have shown that the majority of the lakes in the Tibetan Plateau (TP) started to expand rapidly since the late 1990s. However, the causes are still not well known. For Nam Co, being a closed lake with no outflow, evaporation (EL) over the lake surface is the only way water may leave the lake. Therefore, quantifying EL is key for investigating the mechanism of lake expansion in the TP. EL can be quantified by Penman- and/or bulk-transfer-type models, requiring only net radiation, temperature, humidity and wind speed for inputs. However, interpolation of wind speed data may be laden with great uncertainty due to extremely sparse ground meteorological observations, the highly heterogeneous landscape and lake-land breeze effects. Here, evaporation of Nam Co Lake was investigated within the 1979-2012 period at a monthly time-scale using the complementary relationship lake evaporation (CRLE) model which does not require wind speed data. Validations by in-situ observations of E601B pan evaporation rates at the shore of Nam Co Lake as well as measured EL over an adjacent small lake using eddy covariance technique suggest that CRLE is capable of simulating EL well since it implicitly considers wind effects on evaporation via its vapor transfer coefficient. The multi-year average of annual evaporation of Nam Co Lake is 635 mm. From 1979 to 2012, annual evaporation of Nam Co Lake expressed a very slight decreasing trend. However, a more significant decrease in EL occurred during 1998-2008 at a rate of -12 mm yr-1. Based on water-level readings, this significant decrease in lake evaporation was found to be responsible for approximately 4% of the reported rapid water level increase and areal expansion of Nam Co Lake during the same period.

  3. Statistical analysis of interaction between lake seepage rates and groundwater and lake levels

    NASA Astrophysics Data System (ADS)

    Ala-aho, P.; Rossi, P. M.; Klöve, B.

    2012-04-01

    In Finland, the main sources of groundwater are the esker deposits from the last ice age. Small lakes imbedded in the aquifer with no outlets or inlets are typically found in eskers. Some lakes at Rokua esker, in Northern Finland, have been suffering from changes in water stage and quality. A possible permanent decline of water level has raised considerable concern as the area is also used for recreation and tourism. Rare biotypes supported by the oligotrophic lakes can also be endangered by the level decline. Drainage of peatlands located in the discharge zone of the aquifer is a possible threat for the lakes and the whole aquifer. Drainage can potentially lower the aquifer water table which can have an effect on the groundwater-lake interaction. The aim of this study was to understand in more detail the interaction of the aquifer and the lake systems so potential causes for the lake level variations could be better understood and managed. In-depth understanding of hydrogeological system provides foundation to study the nutrient input to lakes affecting lake ecosystems. A small lake imbedded the Rokua esker aquifer was studied in detail. Direct measurements of seepage rate between the lake and the aquifer were carried out using seepage meters. Seepage was measured from six locations for eight times during May 2010 - November 2010. Precipitation was recorded with a tipping bucket rain gauge adjacent to the lake. Lake stage and groundwater levels from three piezometers were registered on an hourly interval using pressure probes. Statistical methods were applied to examine relationship between seepage measurements and levels of lake and groundwater and amount of precipitation. Distinct areas of inseepage and outseepage of the lake were distinguished with seepage meter measurements. Seepage rates showed only little variation within individual measurement locations. Nevertheless analysis revealed statistically significant correlation of seepage rate variation in four

  4. Habitat, not resource availability, limits consumer production in lake ecosystems

    USGS Publications Warehouse

    Craig, Nicola; Jones, Stuart E.; Weidel, Brian C.; Solomon, Christopher T.

    2015-01-01

    Food web productivity in lakes can be limited by dissolved organic carbon (DOC), which reduces fish production by limiting the abundance of their zoobenthic prey. We demonstrate that in a set of 10 small, north temperate lakes spanning a wide DOC gradient, these negative effects of high DOC concentrations on zoobenthos production are driven primarily by availability of warm, well-oxygenated habitat, rather than by light limitation of benthic primary production as previously proposed. There was no significant effect of benthic primary production on zoobenthos production after controlling for oxygen, even though stable isotope analysis indicated that zoobenthos do use this resource. Mean whole-lake zoobenthos production was lower in high-DOC lakes with reduced availability of oxygenated habitat, as was fish biomass. These insights improve understanding of lake food webs and inform management in the face of spatial variability and ongoing temporal change in lake DOC concentrations.

  5. Modern lacustrine stromatolites, Walker Lake, Nevada

    NASA Astrophysics Data System (ADS)

    Osborne, Robert H.; Licari, Gerald R.; Link, Martin H.

    1982-05-01

    The Walker River drainage basin occupies about 10,000 km 2 in western Nevada and parts of California and is essentially a closed hydrologic system which drains from the crest of the Sierra Nevada in California and terminates in Walker Lake, Nevada. Walker Lake trends north and is about 27.4 km long and 8 km wide with water depths exceeding 30.5 m. The lake is situated in an asymmetric basin with steep alluvial fans flanking the western shoreline (Wassuk Range) and more gentle but areally more extensive alluvial fans flanking the eastern shoreline (Gillis Range). Exposed lake terraces and the present shoreline of Walker Lake record a sequence of Pleistocene and Holocene stromatolitic and tufaceous carbonate deposits. Small generalized and columnar stromatolites, frequently encrusted on exposed coarse-grained clasts or bedrock, are present along parts of the nearshore margin of Walker Lake and at elevated lake stands. Columnar stromatolites as much as 4 cm high are subcylindrical to club shaped discrete, and laterally linked at the base with local branching. These digitate stromatolites start as wavy, generalized stromatolites which are vertically transitional to small, laterally linked cabbage heads with laminae which thicken over the crests. Although algal structures are not well preserved in the older stromatolites, recent precipitation of low magnesium calcite occurs as smooth encrustations and as tiny mounds which are consistently associated with a diverse, seasonally variable, green and blue-green algal community including Cladophora glomerata, Ulothrix (cf. aequalis), Gongrosira, Schizothrix, Amphithrix janthina, Calothrix, Homeothrix, Spirulina, Anabaena, Lyngbya, and Entophysalis. Cladophora glomerata and a species of Ulothrix, which are the two most abundant algae within the Walker Lake stromatolite community, are known to condition semi-alkaline lake water by the removal of CO 2 from bicarbonate during photosynthesis. Such conditioning results in the

  6. Lake trout rehabilitation in Lake Huron

    USGS Publications Warehouse

    Eshenroder, Randy L.; Payne, N. Robert; Johnson, James E.; Bowen, Charles, II; Ebener, Mark P.

    1995-01-01

    Efforts to restore lake trout (Salvelinus namaycush) in Lake Huron after their collapse in the 1940s were underway in the early 1970s with completion of the first round of lampricide applications in tributary streams and the stocking of several genotypes. We assess results of rehabilitation and establish a historical basis for comparison by quantifying the catch of spawning lake trout from Michigan waters in 1929-1932. Sixty-eight percent of this catch occurred in northern waters (MH-1) and most of the rest (15%) was from remote reefs in the middle of the main basin. Sea lampreys (Petromyzon marinus) increased in the early 1980s in the main basin and depressed spawning populations of lake trout. This increase was especially severe in northern waters and appeared to be associated with untreated populations in the St. Marys River. Excessive commercial fishing stemming from unresolved treaty rights also contributed to loss of spawning fish in northern Michigan waters. Seneca-strain lake trout did not appear to be attacked by sea lampreys until they reached a size > 532 mm. At sizes > 632 mm, Seneca trout were 40-fold more abundant than the Marquette strain in matched-planting experiments. Natural reproduction past the fry stage has occurred in Thunder Bay and South Bay, but prospects for self-sustaining populations of lake trout in the main basin are poor because sea lampreys are too abundant, only one side of the basin is stocked, and stocking is deferred to allow commercial gillnetting in areas where most of the spawning occurred historically. Backcross lake trout, a lake trout x splake (s. Fontinalis x s. Namaycush) hybrid, did not reproduce in Georgian Bay, but this genotype is being replaced with pure-strain lake trout, whose early performance appears promising.

  7. Beach-ridge development and lake-level variation in southern Lake Michigan

    USGS Publications Warehouse

    Thompson, T.A.

    1992-01-01

    The most accurate source of information on lake-level fluctuations in the Great Lakes is the historical record from lake-level gauges. Although it can be semiquantitatively extended back into the late 1700's, the historical record is too short to recognize long-term patterns of lake-level behavior. To extend the historical record, information must be obtained from the Great Lakes geologic record. Such information includes the elevation and age of geomorphic features and stratigraphic sequences. One of the longest geologic records of late Holocene lake-level variation is preserved in a beach-ridge complex along the southern shore of Lake Michigan called the Toleston Beach. This strandplain contains over 150 beach ridges that arc across northwestern Indiana and fan out into northeastern Illinois. Each ridge was formed during the fall from a high lake level, and the elevation of the foreshore deposits in each ridge provides information on the upper physical limit of lake level over the past 4000 years. Three scales of quasi-periodic lake-level variation were determined by radiocarbon-dating basal peats of wetlands between the ridges and by measuring the elevation of foreshore (swash) deposits within ridges. These three scales are: (1) a short-term and small-scale fluctuation of 25 to 35 years with a range of about 0.5 to 0.6 m; (2) an intermediate-term and meso-scale fluctuation of 140 to 160 years and a range of about 0.8 to 0.9 m; and (3) a long-term and large-scale fluctuation of 500 to 600 years and a range of 1.8 to 3.7 m. The short-term and intermediate-term fluctuations are reflected in the historical record. An increase in the rate of shoreline progradation from east to west across Indiana's shoreline causes differential preservation of the lake-level fluctuations. That is, groups of four to six ridges in the western part of the strandplain that formed in response to the small-scale fluctuations combine eastward into single ridges and groups of ridges

  8. Lake-level variability and water availability in the Great Lakes

    USGS Publications Warehouse

    Wilcox, Douglas A.; Thompson, Todd A.; Booth, Robert K.; Nicholas, J.R.

    2007-01-01

    years ago. Within that record is a quasi-periodic rise and fall of about 160 ? 40 years in duration and a shorter fluctuation of 32 ? 6 years that is superimposed on the 160-year fluctuation. Recorded lake-level history from 1860 to the present falls within the longer-term pattern and appears to be a single 160-year quasi-periodic fluctuation. Independent investigations of past climate change in the basin over the long-term period of record confirm that most of these changes in lake level were responses to climatically driven changes in water balance, including lake-level highstands commonly associated with cooler climatic conditions and lows with warm climate periods. The mechanisms underlying these large hydroclimatic anomalies are not clear, but they may be related to internal dynamics of the ocean-atmosphere system or dynamical responses of the ocean-atmosphere system to variability in solar radiation or volcanic activity. The large capacities of the Great Lakes allow them to store great volumes of water. As calculated at chart datum, Lake Superior stores more water (2,900 mi3) than all the other lakes combined (2,539 mi3). Lake Michigan's storage is 1,180 mi3; Lake Huron's, 850 mi3; Lake Ontario's, 393 mi3; and Lake Erie's, 116 mi3. Seasonal lake-level changes alter storage by as much as 6 mi3 in Lake Superior and as little as 2.1 mi3 in Lake Erie. The extreme high and low lake levels measured in recorded lake-level history have altered storage by as much as 31 mi3 in Lake Michigan-Huron and as little as 9 mi3 in Lake Ontario. Diversions of water into and out of the lakes are very small compared to the total volume of water stored in the lakes. The water level of Lake Superior has been regulated since about 1914 and levels of Lake Ontario since about 1960. The range of Lake Superior water-level fluctuations and storage has not been altered greatly by regulation. However, fluctuations on Lake Ontario have been reduced from 6.6 ft preregulation

  9. Does pH affect fish species richness when lake area is considered?

    USGS Publications Warehouse

    Rago, P.J.; Wiener, J.G.

    1986-01-01

    Numerous surveys have shown that fish species richness (number of species) is positively correlated with lake pH. However, species richness of fish communities is also correlated with lake size, and low-pH lakes are often small. Thus, conclusions drawn from examination of fish community structure relative to spatial (among- lake) variation in pH have been limited by uncertainties regarding the confounded effects of lake area. The authors used two statistical methods, analysis of covariance and a nonparametric blocked comparison test, to remove effects of lake area and compare fish species richness in low-pH and high-pH lakes. Data from six previous surveys of water chemistry and fish communities in lakes of Ontario and northern Wisconsin were examined. Lakes with low pH ( less than or equal to 6.0) contained significantly fewer fish species than lakes with high pH (> 6.0) when the effect of lake area was considered. A simple probabilistic model showed that the ability to detect differences in species richness is low when lake areas and the pool of potential colonizing species are small. The authors recommend the blocked comparison test for separating the effects of lake area and pH on species richness.

  10. Thermokarst Lake Carbon Storage and Transport near Cherskiy, Northeast Siberia

    NASA Astrophysics Data System (ADS)

    Berman, S. L.; Frey, K. E.; Griffin, C. G.; Zimov, N.

    2013-12-01

    Thermokarst lakes are prevalent features across the pan-Arctic landscape. As the Arctic climate warms further, thermokarst lakes currently situated in continuous permafrost will likely increase in size and number. Shifting lake distributions may have significant impacts on the land-atmosphere exchange of carbon, as these lakes act as reservoirs and conduits that store and transport carbon and other organic material across the landscape. Using field data collected in the Kolyma River basin in the continuous permafrost region near Cherskiy, Northeast Siberia, we investigate the carbon dynamics of four thermokarst lakes in the Y4 watershed, a small, upland drainage area. Through bathymetric mapping of these four lakes, total lake volume was calculated. Depth profiles of temperature, specific conductivity, pH, and dissolved oxygen were collected across horizontal transects and subsequently integrated with these total volume measurements to determine physical characteristics of the lakes. Additionally, water samples were collected at various stations and depths for analyses of dissolved organic carbon (DOC) and chromophoric dissolved organic matter (CDOM). With these physical and biogeochemical measurements in concert, we investigated the ability for these lakes to store and transport carbon through the Y4 watershed. Furthermore, detailed knowledge of CDOM concentrations in these lakes provides an understanding of the lability and molecular weight of the organic matter as well as potential light transmittance through the water column. This watershed area provides a representative example of the potential for thermokarst lakes in yedoma regions to process and move carbon across the landscape and ultimately to larger systems such as the Kolyma River basin. This baseline characterization of regional lakes will lead to a better understanding of how further warming and permafrost instability may impact the carbon dynamics of thermokarst lakes and ultimately how they function

  11. Surficial deposits in the Bear Lake Basin

    USGS Publications Warehouse

    Reheis, Marith C.; Laabs, Benjamin J.C.; Forester, Richard M.; McGeehin, John P.; Kaufman, Darrell S.; Bright, Jordon

    2005-01-01

    Mapping and dating of surficial deposits in the Bear Lake drainage basin were undertaken to provide a geologic context for interpretation of cores taken from deposits beneath Bear Lake, which sometimes receives water and sediment from the glaciated Bear River and sometimes only from the small drainage basin of Bear Lake itself. Analyses of core sediments by others are directed at (1) constructing a high-resolution climate record for the Bear Lake area during the late Pleistocene and Holocene, and (2) investigating the sources and weathering history of sediments in the drainage basin. Surficial deposits in the upper Bear River and Bear Lake drainage basins are different in their overall compositions, although they do overlap. In the upper Bear River drainage, Quaternary deposits derived from glaciation of the Uinta Range contain abundant detritus weathered from Precambrian quartzite, whereas unglaciated tributaries downstream mainly contribute finer sediment weathered from much younger, more friable sedimentary rocks. In contrast, carbonate rocks capped by a carapace of Tertiary sediments dominate the Bear Lake drainage basin.

  12. Ice cover, landscape setting, and geological framework of Lake Vostok, East Antarctica

    USGS Publications Warehouse

    Studinger, M.; Bell, R.E.; Karner, G.D.; Tikku, A.A.; Holt, J.W.; Morse, D.L.; David, L.; Richter, T.G.; Kempf, S.D.; Peters, M.E.; Blankenship, D.D.; Sweeney, R.E.; Rystrom, V.L.

    2003-01-01

    Lake Vostok, located beneath more than 4 km of ice in the middle of East Antarctica, is a unique subglacial habitat and may contain microorganisms with distinct adaptations to such an extreme environment. Melting and freezing at the base of the ice sheet, which slowly flows across the lake, controls the flux of water, biota and sediment particles through the lake. The influx of thermal energy, however, is limited to contributions from below. Thus the geological origin of Lake Vostok is a critical boundary condition for the subglacial ecosystem. We present the first comprehensive maps of ice surface, ice thickness and subglacial topography around Lake Vostok. The ice flow across the lake and the landscape setting are closely linked to the geological origin of Lake Vostok. Our data show that Lake Vostok is located along a major geological boundary. Magnetic and gravity data are distinct east and west of the lake, as is the roughness of the subglacial topography. The physiographic setting of the lake has important consequences for the ice flow and thus the melting and freezing pattern and the lake's circulation. Lake Vostok is a tectonically controlled subglacial lake. The tectonic processes provided the space for a unique habitat and recent minor tectonic activity could have the potential to introduce small, but significant amounts of thermal energy into the lake. ?? 2002 Elsevier Science B.V. All rights reserved.

  13. Plankton secondary productivity and biomass: Their relation to lake trophic state

    USGS Publications Warehouse

    Pederson, G.L.; Welch, E.B.; Litt, A.H.

    1976-01-01

    The biomass and production of the most important zooplankton species were followed for two years in three lakes of varying trophic status in the Lake Washington watershed. Cladocerans and copepods were of equal importance in the biomass of lakes Findley and Chester Morse (both oligotrophic), whereas, copepods were the main biomass component in Lake Sammamish (mesotrophic). Cladocerans dominated production in lakes Sammamish and Chester Morse, while in Findley Lake their productive role, like that of biomass, was equal to that of the copepods. Rotifers contributed a relatively small biomass and production. Data from this study supported Hillbricht-Ilkowska's postulate that the energy transfer efficiency between the primary and secondary trophic levels decreases with increasing trophic state. Energy transfer efficiencies for the lakes of this study expressed as a two year mean of the ratio-secondary: primary production, were as follows: Findley Lake-0.13; Chester Morse Lake-0.08; and Lake Sammanish-0.04. On the other hand, the hypothesis of Patalas that the secondary productivity: biomass ratio (P/B) tended to increase in proportion to the productivity of a lake, could not be supported. Lake Sammamish, the most productive of the lakes studied, had a P/B ratio of 0.03 while lakes Findley and Chester Morse had P/B ratios of 0.04. ?? 1976 Dr. W. Junk b. v. Publishers.

  14. View of Lake Sabrina Dam and Lake Sabrina from east ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    View of Lake Sabrina Dam and Lake Sabrina from east ridge showing spillway at photo center, view southwest - Bishop Creek Hydroelectric System, Plant 2, Lake Sabrina Dam, Bishop Creek, Bishop, Inyo County, CA

  15. Supraglacial lakes on Himalayan debris-covered glacier (Invited)

    NASA Astrophysics Data System (ADS)

    Sakai, A.; Fujita, K.

    2013-12-01

    Debris-covered glaciers are common in many of the world's mountain ranges, including in the Himalayas. Himalayan debris-covered glacier also contain abundant glacial lakes, including both proglacial and supraglacial types. We have revealed that heat absorption through supraglacial lakes was about 7 times greater than that averaged over the whole debris-covered zone. The heat budget analysis elucidated that at least half of the heat absorbed through the water surface was released with water outflow from the lakes, indicating that the warm water enlarge englacial conduits and produce internal ablation. We observed some portions at debris-covered area has caved at the end of melting season, and ice cliff has exposed at the side of depression. Those depression has suggested that roof of expanded water channels has collapsed, leading to the formation of ice cliffs and new lakes, which would accelerate the ablation of debris-covered glaciers. Almost glacial lakes on the debris-covered glacier are partially surrounded by ice cliffs. We observed that relatively small lakes had non-calving, whereas, calving has occurred at supraglacial lakes with fetch larger than 80 m, and those lakes expand rapidly. In the Himalayas, thick sediments at the lake bottom insulates glacier ice and lake water, then the lake water tends to have higher temperature (2-4 degrees C). Therefore, thermal undercutting at ice cliff is important for calving processes in the glacial lake expansion. We estimated and subaqueous ice melt rates during the melt and freeze seasons under simple geomorphologic conditions. In particular, we focused on valley wind-driven water currents in various fetches during the melt season. Our results demonstrate that the subaqueous ice melt rate exceeds the ice-cliff melt rate above the water surface when the fetch is larger than 20 m with the water temperature of 2-4 degrees C. Calculations suggest that onset of calving due to thermal undercutting is controlled by water

  16. Comparison of catch and lake trout bycatch in commercial trap nets and gill nets targeting lake whitefish in northern Lake Huron

    USGS Publications Warehouse

    Johnson, James E.; Ebener, Mark P.; Gebhardt, Kenneth; Bergstedt, Roger

    2004-01-01

    We compared seasonal lake whitefish catch rates, lake trout bycatch, and gearinduced lake trout mortality between commercial trap nets and gill nets in north-central Lake Huron. Onboard monitors recorded catches from 260 gill net and 96 trap net lifts from October 1998 through December 1999. Catch rates for lake whitefish were highest in fall for both gear types, reflecting proximity of spawning sites to the study area. Lake whitefish catch rates were also relatively high in spring but low in both gear types in summer. Lake trout were the principal bycatch species in both gears. The lake trout bycatch was lowest in both gear types in fall, highest in gill nets in spring, and highest in trap nets in summer. The ratio of lake trout to legal whitefish (the target species) was highest in summer and lowest in fall in both gear types. The high lake trout ratio in summer was due principally to low catch rates of lake whitefish. All but 3 of 186 live lake trout removed from trap net pots survived for at least two days of observation in laboratory tanks. Therefore, we estimated that post-release survival of trap netted lake trout that had not been entangled in the mesh was 98.4%. In addition, we accounted for stress-induced mortality for lake trout that were live at capture but entangled in the mesh of either gear type. Resulting estimates of lake trout survival were higher in trap nets (87.8%) than in gill nets (39.6%). The number of lake trout killed per lift was highest during summer in trap nets and during spring in gill nets. In trap nets, 85% of dead lake trout were observed to be entangled in the mesh of the pot or tunnels. Survival rates of lake trout in gill nets were higher in our study than reported by others, probably because our nets were hand lifted in a small boat. Our trap net-induced mortality estimates on lake trout were higher than those reported by others because we adjusted our estimates to account for post-release mortality caused by handling and

  17. Biogeochemical cycling of manganese in Oneida Lake, New York: whole lake studies of manganese

    NASA Technical Reports Server (NTRS)

    Aguilar, C.; Nealson, K. H.

    1998-01-01

    Oneida Lake, New York is a eutrophic freshwater lake known for its abundant manganese nodules and a dynamic manganese cycle. Temporal and spatial distribution of soluble and particulate manganese in the water column of the lake were analyzed over a 3-year period and correlated with other variables such as oxygen, pH, and temperature. Only data from 1988 are shown. Manganese is removed from the water column in the spring via conversion to particulate form and deposited in the bottom sediments. This removal is due to biological factors, as the lake Eh/pH conditions alone can not account for the oxidation of the soluble manganese Mn(II). During the summer months the manganese from microbial reduction moves from the sediments to the water column. In periods of stratification the soluble Mn(II) builds up to concentrations of 20 micromoles or more in the bottom waters. When mixing occurs, the soluble Mn(II) is rapidly removed via oxidation. This cycle occurs more than once during the summer, with each manganese atom probably being used several times for the oxidation of organic carbon. At the end of the fall, whole lake concentrations of manganese stabilize, and remain at about 1 micromole until the following summer, when the cycle begins again. Inputs and outflows from the lake indicate that the active Mn cycle is primarily internal, with a small accumulation each year into ferromanganese nodules located in the oxic zones of the lake.

  18. Origins of rainbow smelt in Lake Ontario

    USGS Publications Warehouse

    Bergstedt, Roger A.

    1983-01-01

    The first rainbow smelt (Osmerus mordax) to enter Lake Ontario were probably migrants from an anadromous strain introduced into New York's Finger Lakes. Since the upper Great Lakes were originally stocked with a landlocked strain from Green Lake, Maine, subsequent migration to Lake Ontario from Lake Erie makes Lake Ontario unique among the Great Lakes in probably having received introductions from two distinct populations.

  19. Experiences of a long-term randomized controlled prevention trial in a maiden environment: Estonian Postmenopausal Hormone Therapy trial

    PubMed Central

    Hovi, Sirpa-Liisa; Veerus, Piret; Rahu, Mati; Hemminki, Elina

    2008-01-01

    Background Preventive drugs require long-term trials to show their effectiveness or harms and often a lot of changes occur during post-marketing studies. The purpose of this article is to describe the research process in a long-term randomized controlled trial and discuss the impact and consequences of changes in the research environment. Methods The Estonian Postmenopausal Hormone Therapy trial (EPHT), originally planned to continue for five years, was planned in co-operation with the Women's International Study of Long-Duration Oestrogen after Menopause (WISDOM) in the UK. In addition to health outcomes, EPHT was specifically designed to study the impact of postmenopausal hormone therapy (HT) on health services utilization. Results After EPHT recruited in 1999–2001 the Women's Health Initiative (WHI) in the USA decided to stop the estrogen-progestin trial after a mean of 5.2 years in July 2002 because of increased risk of breast cancer and later in 2004 the estrogen-only trial because HT increased the risk of stroke, decreased the risk of hip fracture, and did not affect coronary heart disease incidence. WISDOM was halted in autumn 2002. These decisions had a major influence on EPHT. Conclusion Changes in Estonian society challenged EPHT to find a balance between the needs of achieving responses to the trial aims with a limited budget and simultaneously maintaining the safety of trial participants. Flexibility was the main key for success. Rapid changes are not limited only to transiting societies but are true also in developed countries and the risk must be included in planning all long-term trials. The role of ethical and data monitoring committees in situations with emerging new data from other studies needs specification. Longer funding for preventive trials and more flexibility in budgeting are mandatory. Who should prove the effectiveness of an (old) drug for a new preventive indication? In preventive drug trials companies may donate drugs but they take a

  20. Ups and Downs of Burbot and their predator Lake Trout in Lake Superior, 1953-2011

    USGS Publications Warehouse

    Gorman, Owen T.; Sitar, Shawn P.

    2013-01-01

    The fish community of Lake Superior has undergone a spectacular cycle of decline and recovery over the past 60 years. A combination of Sea Lamprey Petromyzon marinus depredation and commercial overfishing resulted in severe declines in Lake Trout Salvelinus namaycush, which served as the primary top predator of the community. Burbot Lota lota populations also declined as a result of Sea Lamprey depredation, largely owing to the loss of adult fish. After Sea Lamprey control measures were instituted in the early 1960s, Burbot populations rebounded rapidly but Lake Trout populations recovered more slowly and recovery was not fully evident until the mid-1980s. As Lake Trout populations recovered, Burbot populations began to decline, and predation on small Burbot was identified as the most likely cause. By 2000, Burbot densities had dropped below their nadir in the early 1960s and have continued to decline, with the densities of juveniles and small adults falling below that of large adults. Although Burbot populations are at record lows in Lake Superior, the density of large reproductive adults remains stable and a large reserve of adult Burbot is present in deep offshore waters. The combination of the Burbot's early maturation, long life span, and high fecundity provides the species with the resiliency to remain a viable member of the Lake Superior fish community into the foreseeable future.

  1. David Morrison on Lake Vostok

    NASA Video Gallery

    Dr. David Morrison discusses the implications of research possibilities at Lake Vostok, one of the largest subglacial lakes located over two miles beneath the ice in Antarctica. The lake has been c...

  2. Lake Mead, NV

    NASA Technical Reports Server (NTRS)

    1982-01-01

    Lake Mead, Nevada, (36.0N, 114.5E) where the water from the Colorado River empties after it's 273 mile journey through the Grand Canyon of Arizona is the subject of this photo. Other features of interest are Hoover Dam on the south shore of Lake Mead where cheap hydroelectric power is secondary to the water resources made available in this northern desert region and the resort city of Las Vegas, just to the west of Lake Mead.

  3. Pleistocene lake level changes in Western Mongolia

    NASA Astrophysics Data System (ADS)

    Borodavko, P. S.

    2009-04-01

    lake is 75 km long and 31 km wide. Its mean depth is 47 m, with the deepest point reaching 80 m, and its total water volume is 66,034 km3 and drainage basin 115,500 km2. The only water flowing into it is Galbiyn Hooloi. Hara-Us Nur Lake is a fresh-water (mineralization ca 107-348 mg/l, pH -7.8) basin situated in the Mongolian Great Lakes Depression [2]. Hara-Us Nur is fed by the Kobdo and Buyant rivers, which start in the Mongolian Altay, and outflows via the Chano-Hairkhan River into Hara-Us Nur Lake. Hara-Us Nur is divided by the Ak-Bashi Island into two subbasins. It has a water area of 1857 km2 with a length of 72.2 km and a maximum width of 27 km [4]. The maximum depth is 4 m and the average depth is ca 2 m [5,6]. The terraced lake shores are covered by steppe and desert vegetation. Pharagmites is abundant in the river deltas and close to the shore-line and the shallow-water littoral is covered by rich aquatic vegetation, including Myriophyllum verticulatum, Zannichelia pedunculata, Utricularia vulgaris [3]. Hara-Nur Lake is situated in the desert steppe subzone of the Mongolian Great Lakes Depression. The fresh-water Hara-Nur Lake receives inflow from Hara-Us Nur Lake via the Chano-Hairkhan River. There are two outflows from the lake one outflow is via a 10 km-long channel which flows to the Dzabhan River, which in turn flows into the closed Hyargas Lake. The other outflow is a small semi-permanent stream with flows southward into the closed brackish-water Dorgon Lake. Hara-Nur has a water area of 57,500 ha, with a length of 37 km and a maximum width of ca 24 km. The maximum depth is 7 m and the average depth is ca 4 m. The mean water mineralization is 260 mg/l and the pH is 8.0 [5]. The catchment area is ca 7,200,000 ha. Lake Ureg located in the Mongolian Altay at an altitude of 1425 m.a.s.1., this lake has an area 237.6 km2 and maximum depth of 48 m. Secchi disk transparency is to 8 m. Macrophyte beds cover up to 20 per cent of the lake area, with the common

  4. Visual observations of historical lake trout spawning grounds in western Lake Huron

    USGS Publications Warehouse

    Nester, Robert T.; Poe, Thomas P.

    1987-01-01

    Direct underwater video observations were made of the bottom substrates at 12 spawning grounds formerly used by lake trout Salvelinus namaycush in western Lake Huron to evaluate their present suitability for successful reproduction by lake trout. Nine locations examined north of Saginaw Bay in the northwestern end of the lake are thought to provide the best spawning habitat. The substrate at these sites consisted of angular rough cobble and rubble with relatively deep interstitial spaces (a?Y 0.5 m), small amounts of fine sediments, and little or no periphytic growth. Conditions at the three other sampling locations south of Saginaw Bay seemed much less suitable for successful reproduction based on the reduced area of high-quality substrate, shallow interstitial spaces, high infiltration of fine sediments, and greater periphytic growth.

  5. Great Lakes Literacy Principles

    NASA Astrophysics Data System (ADS)

    Fortner, Rosanne W.; Manzo, Lyndsey

    2011-03-01

    Lakes Superior, Huron, Michigan, Ontario, and Erie together form North America's Great Lakes, a region that contains 20% of the world's fresh surface water and is home to roughly one quarter of the U.S. population (Figure 1). Supporting a $4 billion sport fishing industry, plus $16 billion annually in boating, 1.5 million U.S. jobs, and $62 billion in annual wages directly, the Great Lakes form the backbone of a regional economy that is vital to the United States as a whole (see http://www.miseagrant.umich.edu/downloads/economy/11-708-Great-Lakes-Jobs.pdf). Yet the grandeur and importance of this freshwater resource are little understood, not only by people in the rest of the country but also by many in the region itself. To help address this lack of knowledge, the Centers for Ocean Sciences Education Excellence (COSEE) Great Lakes, supported by the U.S. National Science Foundation and the National Oceanic and Atmospheric Administration, developed literacy principles for the Great Lakes to serve as a guide for education of students and the public. These “Great Lakes Literacy Principles” represent an understanding of the Great Lakes' influences on society and society's influences on the Great Lakes.

  6. Validation of CryoSat-2 derived lake levels

    NASA Astrophysics Data System (ADS)

    Nielsen, Karina; Stenseng, Lars; Andersen, Ole; Villadsen, Heidi; Knudsen, Per

    2015-04-01

    The SIRAL altimeter on-board the ESA satellite CryoSat-2 is the first radar altimeter that is capable of operating in synthetic aperture radar (SAR) mode. The SAR technology provides a much higher along-track resolution compared to conventional altimetry. The higher resolution makes it possible to accurately monitor much smaller water bodies than previously. In this study, which is part of the FP7 project Land and Ocean take up from Sentinel-3 (LOTUS), we examine and validate Cryosat-2 derived lake levels and as a reference we compare our results with lake levels based on Envisat data. As a test case we consider 5 lakes; Vänern (Sweden), Okeechobee (Florida, US), Arresø, Mossø, and Skanderborgsø (Denmark), which are ranging from approximately 9 km2 to 5655 km2. We estimate the along-track precision and the accuracy by validating the estimated lake levels with gauge data from Okeechobee and Vänern. We find that the precision based on CryoSat-2 increase significantly for small lakes compared to Envisat. Despite the spatially varying lake crossings, Cryosat-2 is able to provide lake level time series of a quality that is comparable to or better than Envisat. Hence, these results demonstrate the promising possibilities of the upcoming mission Sentinel-3, which potentially will be able to provide accurate time series for small lakes.

  7. A novel heat flux study of a geothermally active lake - Lake Rotomahana, New Zealand

    NASA Astrophysics Data System (ADS)

    Tivey, Maurice A.; de Ronde, Cornel E. J.; Tontini, Fabio Caratori; Walker, Sharon L.; Fornari, Daniel J.

    2016-03-01

    A new technique for measuring conductive heat flux in a lake was adapted from the marine environment to allow for multiple measurements to be made in areas where bottom sediment cover is sparse, or even absent. This thermal blanket technique, pioneered in the deep ocean for use in volcanic mid-ocean rift environments, was recently used in the geothermally active Lake Rotomahana, New Zealand. Heat flow from the lake floor propagates into the 0.5 m diameter blanket and establishes a thermal gradient across the known blanket thickness and thereby provides an estimate of the conductive heat flux of the underlying terrain. This approach allows conductive heat flux to be measured over a spatially dense set of stations in a relatively short period of time. We used 10 blankets and deployed them for 1 day each to complete 110 stations over an 11-day program in the 6 × 3 km lake. Results show that Lake Rotomahana has a total conductive heat flux of about 47 MW averaging 6 W/m2 over the geothermally active lake. The western half of the lake has two main areas of high heat flux; 1) a high heat flux area averaging 21.3 W/m2 along the western shoreline, which is likely the location of the pre-existing geothermal system that fed the famous Pink Terraces, mostly destroyed during the 1886 eruption 2) a region southwest of Patiti Island with a heat flux averaging 13.1 W/m2 that appears to be related to the explosive rift that formed the lake in the 1886 Tarawera eruption. A small rise in bottom water temperature over the survey period of 0.01 °C/day suggests the total thermal output of the lake is ~ 112-132 MW and when compared to the conductive heat output suggests that 18-42% of the total thermal energy is by conductive heat transfer.

  8. The Ambrosia Lake project archaeological investigations of three small sites associated with the southern Chacoan outlier of Kin Nizhoni, McKinley County, New Mexico. [Uranium Mill Tailings Remedial Action (UMTRA) Project

    SciTech Connect

    Cullington, B.J.; Hammack, L.C.; Baugh, T.G. )

    1990-03-15

    During the fall of 1987, Complete Archaeological Service Associates conducted mitigative excavations at three sites (LA50363, LA50364, and LA50371) in McKinley County, New Mexico. These sites are adjacent to the Phillips/United Nuclear Inactive Uranium Mill and Tailings site at Ambrosia Lake, New Mexico. The primary deposition at each of these sites appears to be related to a Pueblo II or Bonito Phase occupation. Temporal placement is based primarily on the cross dating of ceramics and archaeomagnetic determinations when possible. No tree-ring or radiocarbon samples are available from these sites. These Ambrosia Lake sites indicate that this area was occupied primarily by Pueblo II people who may have had close social, economic, and ceremonial ties with the people living at the nuclear community of Lower Nizhoni about 3 km south-southeast. The later component at LA50364 indicates a Pueblo III occupation by people who may have had similar ties to the people of the Kin Nizhoni nuclear community. The Ambrosia Lake sites, then, provide important information on the structure of subnuclear communities within the southern Chaco periphery.

  9. Species succession and fishery exploitation in the Great Lakes

    USGS Publications Warehouse

    Smith, Stanford H.

    1968-01-01

    The species composition of fish in the Great Lakes has undergone continual change since the earliest records. Some changes were caused by enrichment of the environment, but others primarily by an intensive and selective fishery for certain species. Major changes related to the fishery were less frequent before the late 1930's than in recent years and involved few species. Lake sturgeon (Acipenser fulvescens) were overexploited knowingly during the late 1800's because they interfered with fishing for preferred species; sturgeon were greatly reduced in all lakes by the early 1900's. Heavy exploitation accompanied sharp declines of lake herring (Leucichthys artedi) in Lake Erie during the 1920's and lake whitefish (Coregonus clupeaformis) in Lake Huron during the 1930's. A rapid succession of fish species in Lakes Huron, Michigan, and Superior that started about 1940 has been caused by selective predation by the sea lamprey (Petromyzon marinus) on native predatory species, and the resultant shifting emphasis of the fishery and species interaction as various species declined. Lake trout (Salvelinus namaycush) and burbot (Lota lota), the deepwater predators, were depleted first; this favored their prey, the chubs (Leucichthys spp.). The seven species of chubs were influenced differently according to differences in size. Fishing emphasis and predation by sea lampreys were selective for the largest species of chubs as lake trout and burbot declined. A single slow-growing chub, the bloater, was favored and increased, but as the large chubs declined the bloater was exploited by a new trawl fishery. The growth rate and size of the bloater increased, making it more vulnerable to conventional gillnet fishery and lamprey predation. This situation in Lakes Michigan and Huron favored the small alewife (Alosa pseudoharengus) which had recently become established in the upper Great Lakes, and the alewife increased rapidly and dominated the fish stocks of the lakes. The successive

  10. Lakes, Lagerstaetten, and Evolution

    NASA Astrophysics Data System (ADS)

    Kordesch, E. G.; Park, L. E.

    2001-12-01

    The diversity of terrestrial systems is estimated to be greater than in the marine realm. However no hard data yet exists to substantiate this claim. Ancient lacustrine deposits may preserve an exceptionally diverse fossil fauna and aid in determining continental faunal diversities. Fossils preserved in lake deposits, especially those with exceptional preservation (i.e. Konservat Lagerstaetten), may represent a dependable method for determining species diversity changes in the terrestrial environment because of their faunal completeness. Important Konservat Lagerstaetten, such as the Green River Formation (US) and Messel (Germany), both Eocene in age, are found in lake sediments and show a remarkable faunal diversity for both vertebrates and invertebrates. To date information from nearly 25 lake lagerstaetten derived from different types of lake basins from the Carboniferous to the Miocene have been collected and described. Carboniferous sites derive from the cyclothems of Midcontinent of the US while many Cenozoic sites have been described from North and South America as well as Europe and Australia. Asian sites contain fossils from the Mesozoic and Cenozoic. With this data, insight into the evolutionary processes associated with lake systems can be examined. Do lakes act as unique evolutionary crucibles in contrast to marine systems? The speciation of cichlid fishes in present-day African lakes appears to be very high and is attributed to the diversity of environments found in large rift lakes. Is this true of all ancient lakes or just large rift lakes? The longevity of a lake system may be an important factor in allowing speciation and evolutionary processes to occur; marine systems are limited only in the existence of environments as controlled by tectonics and sea level changes, on the order of tens of millions of years. Rift lakes are normally the longest lived in the millions of years. Perhaps there are only certain types of lakes in which speciation of

  11. Lake Vostok: An earthly analogue for the geomicrobiology on Europa

    NASA Astrophysics Data System (ADS)

    Priscu, J. C.; Christner, B. C.

    2007-12-01

    The recent discovery of more than 150 subglacial lakes beneath the Antarctic ice sheet has important implications in our search for liquid water and associated life on other icy worlds. The largest of these lakes is Lake Vostok, which has a surface area of 14000 square km and a depth of 1000 m, making it one of the largest lakes on Earth. Although we have yet to sample directly the liquid water from any of the Antarctic subglacial lakes, refrozen lakewater (accretion ice) has been sampled just above the surface of Lake Vostok. Genomic and geochemical analysis of this ice reveals that the surface lake water supports a microbial assemblage with a density approaching 1000 cells per milliliter. Sequencing and phylogenetic analysis of the 900 to 1000 base pair small subunit rRNA gene sequences obtained revealed a low diversity of clones that classify within the beta, gamma and delta subdivisions of the phylum Proteobacteria. Nearest phylogenetic neighbor analysis of these gene sequences imply that the lake contains an aerobic and anaerobic consortium of bacteria with metabolisms dedicated to iron and sulfur respiration or oxidation indicating that these metals play a role in the bioenergetics of microorganisms that occur in Lake Vostok. Sequence analysis further revealed that heterotrophic life in the lake can be sustained by chemolithotrophic production of new carbon supplemented by dissolved organic carbon released from the overlying ice sheet. Data obtained from orbiters have revealed that a deep ocean of liquid water lies under a thick chaotic ice cover on Europa where organic matter derived from comets and oxidants provided by radiation from Jupiter's magnetosphere may provide a habitat for life and a reservoir of endogenous and exogenous substances much like we observe in Lake Vostok. Future studies of Antarctic subglacial lake environments will play a crucial role in our understanding of life on Europa and other frozen worlds.

  12. The professional structure of Soviet medical care: the relationship between personal characteristics, medical education, and occupational setting for Estonian physicians.

    PubMed Central

    Barr, D A

    1995-01-01

    OBJECTIVES. Using the Estonian example, this study provides data to describe the ways in which personal, educational, and occupational factors interacted to determine the professional structure of the Soviet health care system. METHODS. The study analyzes data gathered from a survey of 20% of the physicians in Estonia. It measures the frequencies of pertinent personal and occupational factors, and uses multivariate analysis to explore relationships between these factors. RESULTS. Most physicians in Estonia are women and work in urban settings. About half of the physicians work in hospitals, and one third work in large outpatient clinics called polyclinics. About one third work in primary care. Gender affects education, specialty, type of workplace, and administrative duties; nationality affects education and administrative duties. CONCLUSIONS. The Soviet system of health care derived its professional structure from a combination of personal and occupational factors. Those considering options for reform of the health care systems of the newly independent states that once constituted the Soviet Union should appreciate the nature of these structural forces. PMID:7892922

  13. Seismic investigation of Lake Issyk-Kul, Kyrgyzstan

    NASA Astrophysics Data System (ADS)

    Gebhardt, C.; Naudts, L.; De Mol, L.; De Batist, M.

    2012-04-01

    intercalated with pelagic background sedimentation. Sediments are slightly inclined towards south with increasing angles with depth, suggesting a halfgraben structure of the lake basin. Mass transport deposits such as debris flows are a common feature close to the steeper flanks around the central plain. The southern flank is characterized by many small terraces and several canyons that are related to the small inlets at the southern shore. The northern flank, however, shows a small, shallow shelf area of 25 to 30 m water depth. This area is characterized by glacial outwash sediments brought to the lake by small rivers that drain the large terminal moraines which are located north of the lake.

  14. Lake water quality: Chapter 4 in A synthesis of aquatic science for management of Lakes Mead and Mohave

    USGS Publications Warehouse

    Tietjen, Todd; Holdren, G. Chris; Rosen, Michael R.; Veley, Ronald J.; Moran, Michael J.; Vanderford, Brett; Wong, Wai Hing; Drury, Douglas D.

    2012-01-01

    Given the importance of the availability and quality of water in Lake Mead, it has become one of the most intensely sampled and studied bodies of water in the United States. As a result, data are available from sampling stations across the lake (fig. 4-1 and see U.S. Geological Survey Automated Water-Quality Platforms) to provide information on past and current (2012) water-quality conditions and on invasive species that influence—and are affected by—water quality. Water quality in Lakes Mead and Mohave generally exceeds standards set by the State of Nevada to protect water supplies for public uses: drinking water, aquatic ecosystem health, recreation, or agricultural irrigation. In comparison to other reservoirs studied by the U.S. Environmental Protection Agency (USEPA) for a national lake assessment (U.S. Environmental Protection Agency, 2010), Lake Mead is well within the highest or ‘good’ category for recreation and aquatic health (see U.S. Environmental Protection Agency National Lakes Assessment and Lake Mead for more details). While a small part of the lake, particularly Las Vegas Bay, is locally influenced by runoff from urbanized tributaries such as Las Vegas Wash, contaminant loading in the lake as a whole is low compared to other reservoirs in the nation, which are influenced by runoff from more heavily urbanized watersheds (Rosen and Van Metre, 2010).

  15. Potential methane emission from north-temperate lakes following ice melt

    USGS Publications Warehouse

    Michmerhuizen, C.M.; Striegl, R.G.; McDonald, M.E.

    1996-01-01

    Methane, a radiatively active 'greenhouse' gas, is emitted from lakes to the atmosphere throughout the open-water season. However, annual lake CH4 emissions calculated solely from open-water measurements that exclude the time of spring ice melt may substantially underestimate the lake CH4 source strength. We estimated potential spring CH4 emission at the time of ice melt for 19 lakes in northern Minnesota and Wisconsin. Lakes ranged in area from 2.7 to 57,300 ha and varied in littoral zone sediment type. Regression analyses indicated that lake area explained 38% of the variance in potential CH4 emission for relatively undisturbed lakes; as lake area increases potential CH4 emission per unit area decreases. Inclusion of a second term accounting for the presence or absence of soft organic-rich littoral-zone sediments explained 83% of the variance in potential spring CH4 emission. Total estimated spring CH4 emission for 1993 for all Minnesota lakes north of 45?? with areas ???4 ha was 1.5 x 108 mol CH4 assuming a 1 : 1 ratio of soft littoral sediment to hard littoral sediment lakes. Emission estimates ranged from 5.3 x 107 tool assuming no lakes have soft organic-rich littoral sediments to 4.5 x 108 mol assuming all lakes have soft organic-rich littoral sediments. This spring CH4 pulse may make up as much as 40% of the CH4 annually emitted to the atmosphere by small lakes.

  16. Temporal evolution of organic carbon concentrations in Swiss lakes: trends of allochthonous and autochthonous organic carbon.

    PubMed

    Rodríguez-Murillo, J C; Filella, M

    2015-07-01

    Evaluation of time series of organic carbon (OC) concentrations in lakes is useful for monitoring some of the effects of global change on lakes and their catchments. Isolating the evolution of autochthonous and allochthonous lake OC might be a useful way to differentiate between drivers of soil and photosynthetic OC related changes. However, there are no temporal series for autochthonous and allochthonous lake OC. In this study, a new approach has been developed to construct time series of these two categories of OC from existing dissolved organic carbon (DOC) data. First, temporal series (longer than ten years) of OC have been compiled for seven big Swiss lakes and another 27 smaller ones and evaluated by using appropriate non-parametric statistical methods. Subsequently, the new approach has been applied to construct time series of autochthonous and allochthonous lake OC in the seven big lakes. Doing this was possible because long term series of DOC concentrations at different depths are available for these lakes. Organic carbon concentrations generally increase in big lakes and decrease in smaller ones, although only in some cases are these trends statistically significant. The magnitude of the observed changes is generally small in big lakes (<1% annual change) and larger in smaller lakes. Autochthonous DOC concentrations in big lakes increase or decrease depending on the lake and the station but allochthonous DOC concentrations generally increase. This pattern is consistent with an increase in the OC input from the lakes' catchments and/or an increase in the refractoriness of the OC in question, and with a temporal evolution of autochthonous DOC depending on the degree of recovery from past eutrophication of each particular lake. In small lakes, OC dynamics are mainly driven by decreasing biological productivity, which in many, but not all cases, outweighs the probable increase of allochthonous OC. PMID:25782080

  17. Non-deposit system option for waste management on small islands.

    PubMed

    Vilms, Monica; Voronova, Viktoria

    2016-08-01

    This paper analyses waste management on small islands (on a global scale these are micro-islands). In the context of the paper, small islands are islands that have an area less than 50 km(2) The study presents an overview of the problems connected with waste transport from islands to the mainland. Waste generation on islands is very much related to tourists. If tourists do not handle waste properly, it will cause problems. Four small Estonian islands in the range of 3-19 km(2) are studied in detail. For these and other small islands, the main problem is the waste produced by tourists, or related to tourists and waste transport to the mainland. Currently, the local municipality has to arrange and finance waste transport. In fact, and based on the polluter-pays principle, the tourists should bear the cost of waste management. There are different tax options available in order to collect the money from tourists - waste tax, harbour tax, tourist tax, donations, environmental tax and others. The study results revealed that the best possible solution for Estonian islands may be a non-deposit system - including an additional charge on ferry ticket prices. The extra money should cover the costs of waste management and waste shipping. The tourists arriving in their own boats should pay a harbour tax, which includes a waste tax to compensate for the cost of waste management. PMID:27344037

  18. Lessons from a Lake.

    ERIC Educational Resources Information Center

    Goethals, Susan

    1997-01-01

    Describes a study that included classroom lessons on hydroelectric power, the history and construction of a nearby lake, data recording, the use of field guides, and methods of counting natural populations. The study culminated in a field trip to the lake. (JRH)

  19. Great Lakes: Great Gardening.

    ERIC Educational Resources Information Center

    New York Sea Grant Inst., Albany, NY.

    This folder contains 12 fact sheets designed to improve the quality of gardens near the Great Lakes. The titles are: (1) "Your Garden and the Great Lakes"; (2) "Organic Gardening"; (3) "Fruit and Vegetable Gardening"; (4) "Composting Yard Wastes"; (5) "Herbicides and Water Quality"; (6) "Watering"; (7) "Soil Erosion by Water"; (8) "Soil…

  20. Lake Effect Clouds

    NASA Technical Reports Server (NTRS)

    2002-01-01

    The lake effect is particularly clear in this Sea-viewing Wide field-of-view Sensor (SeaWiFS) true-color image of the North American Great Lakes region, acquired December 5, 2000. Lakes Nipigon, Superior, and Michigan show striking contrasts between clear and cloudy air as the wind blows from the northwest across the lakes. As it flows across the relatively warm lakes, the cold dry air gathers heat and moisture from the surface. The warm moist air rises into the atmosphere and mixes vigorously with the cold dry air above. The layer of warm moist air deepens as it travels across the lake. Some of the evaporated water from the lake condenses into streamers of fog rising from the surface, while much of the moisture condenses to form a stratocumulus cloud in the upper half of the mixed layer. The cloud-forming water droplets may freeze into ice crystals and, due to accumulated water deposition over time, grow into snowflakes. This process can generate snowstorms that produce significant amounts of snowfall downwind. It is not uncommon for lake effect snowstorms to produce as much as two feet of snow within a 24-hour period in northwestern parts of New York and Pennsylvania. Image provided by the SeaWiFS Project, NASA/Goddard Space Flight Center, and ORBIMAGE

  1. GREAT LAKES LIMNOLOGY MONITORING

    EPA Science Inventory

    The Great Lakes National Program Office (GLNPO) of the United States Environmental Protection Agency (USEPA) has primary responsibility within the U.S. for conducting surveillance monitoring of the offshore waters of the Great Lakes. This monitoring is intended to fulfill provis...

  2. The Great Lakes.

    ERIC Educational Resources Information Center

    Seasons, 1987

    1987-01-01

    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…

  3. The lakes of Titan

    USGS Publications Warehouse

    Stofan, E.R.; Elachi, C.; Lunine, J.I.; Lorenz, R.D.; Stiles, B.; Mitchell, K.L.; Ostro, S.; Soderblom, L.; Wood, C.; Zebker, H.; Wall, S.; Janssen, M.; Kirk, R.; Lopes, R.; Paganelli, F.; Radebaugh, J.; Wye, L.; Anderson, Y.; Allison, M.; Boehmer, R.; Callahan, P.; Encrenaz, P.; Flamini, E.; Francescetti, G.; Gim, Y.; Hamilton, G.; Hensley, S.; Johnson, W.T.K.; Kelleher, K.; Muhleman, D.; Paillou, P.; Picardi, G.; Posa, F.; Roth, L.; Seu, R.; Shaffer, S.; Vetrella, S.; West, R.

    2007-01-01

    The surface of Saturn's haze-shrouded moon Titan has long been proposed to have oceans or lakes, on the basis of the stability of liquid methane at the surface. Initial visible and radar imaging failed to find any evidence of an ocean, although abundant evidence was found that flowing liquids have existed on the surface. Here we provide definitive evidence for the presence of lakes on the surface of Titan, obtained during the Cassini Radar flyby of Titan on 22 July 2006 (T16). The radar imaging polewards of 70?? north shows more than 75 circular to irregular radar-dark patches, in a region where liquid methane and ethane are expected to be abundant and stable on the surface. The radar-dark patches are interpreted as lakes on the basis of their very low radar reflectivity and morphological similarities to lakes, including associated channels and location in topographic depressions. Some of the lakes do not completely fill the depressions in which they lie, and apparently dry depressions are present. We interpret this to indicate that lakes are present in a number of states, including partly dry and liquid-filled. These northern-hemisphere lakes constitute the strongest evidence yet that a condensable-liquid hydrological cycle is active in Titan's surface and atmosphere, in which the lakes are filled through rainfall and/or intersection with the subsurface 'liquid methane' table. ??2007 Nature Publishing Group.

  4. Great Lakes Teacher's Guide.

    ERIC Educational Resources Information Center

    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…

  5. Lake trophic applications: Wisconsin

    NASA Technical Reports Server (NTRS)

    Scarpace, F.

    1981-01-01

    Efforts to classify the water quality characteristics of lakes using LANDSAT imagery are reported. Image processing and registration techniques are described. A lake classification scheme which involves the assignment of a trophic class number was used in the data analysis. The resulting values were compared to the corresponding rank assignment derived from field measurements.

  6. Lake Wobegon Dice

    ERIC Educational Resources Information Center

    Moraleda, Jorge; Stork, David G.

    2012-01-01

    We introduce Lake Wobegon dice, where each die is "better than the set average." Specifically, these dice have the paradoxical property that on every roll, each die is more likely to roll greater than the set average on the roll, than less than this set average. We also show how to construct minimal optimal Lake Wobegon sets for all "n" [greater…

  7. Lake Roosevelt Fisheries Evaluation Program; Meadow Creek vs. Lake Whatcom Stock Kokanee Salmon Investigations in Lake Roosevelt, 2001 Annual Report.

    SciTech Connect

    McLellan, Holly; Scholz, Allan

    2002-03-01

    Lake Roosevelt has been stocked with Lake Whatcom stock kokanee since 1989 with the primary objective of creating a self-sustaining recreational fishery. Due to low return numbers, it was hypothesized a stock of kokanee, native to the upper Columbia River, might perform better than the coastal Lake Whatcom strain. Kokanee from Meadow Creek, a tributary of Kootenay Lake, British Columbia were selected as an alternative stock. Matched pair releases of Lake Whatcom and Meadow Creek kokanee were made from Sherman Creek Hatchery in late June 2000 and repeated in 2001. Stock performance between Lake Whatcom and Meadow Creek kokanee was evaluated using three performance measures; (1) the number of returns to Sherman Creek, the primary egg collection facility, (2) the number of returns to other tributaries and (3) the number of returns to the creel. Kokanee were collected during five passes through the reservoir via electrofishing, which included 87 tributary mouths during the fall of 2000 and 2001. Chi-square analysis indicated age two Meadow Creek kokanee returned to Sherman Creek in significantly higher numbers when compared to the Whatcom stock in 2000 ({chi}{sup 2} = 736.6; d.f. = 1; P < 0.01) and 2001 ({chi}{sup 2} = 156.2; d.f. = 1; P < 0.01). Reservoir wide recoveries of age two kokanee had similar results in 2000 ({chi}{sup 2} = 735.3; d.f. = 1; P < 0.01) and 2001 ({chi}{sup 2} = 150.1; d.f. = 1; P < 0.01). Six Lake Whatcom and seven Meadow Creek three year olds were collected in 2001. The sample size of three year olds was too small for statistical analysis. No kokanee were collected during creel surveys in 2000, and two (age three kokanee) were collected in 2001. Neither of the hatchery kokanee collected were coded wire tagged, therefore stock could not be distinguished. After two years of monitoring, neither Meadow Creek or Lake Whatcom kokanee appear to be capable of providing a run of three-year-old spawners to sustain stocking efforts. The small number of

  8. Assessment of heavy metal enrichment and its human impact in lacustrine sediments from four lakes in the mid-low reaches of the Yangtze River, China.

    PubMed

    Bing, Haijian; Wu, Yanhong; Liu, Enfeng; Yang, Xiangdong

    2013-07-01

    Sediments from four lakes in the mid-low reaches of the Yangtze River, Taibai Lake, Longgan Lake, Chaohu Lake and Xijiu Lake, were chosen to evaluate their enrichment state and history. The state of heavy metal enrichment was at a low level in the sediment of Taibai Lake and Longgan Lake. The enrichment state of Co, Cr and Ni was also low in the sediment of Chaohu Lake and Xijiu Lake, while Cu, Pb and Zn enrichment reached a higher level. Mass accumulation fluxes were calculated to quantitatively evaluate the anthropogenic contribution to heavy metals in the sediment. The anthropogenic accumulation fluxes were lower in the sediment of Taibai Lake and Longgan Lake compared with the other two lakes, where heavy metals, especially Cu, Pb and Zn, were mainly from anthropogenic sources. Heavy metal accumulation did not vary greatly in the sediment of Taibai Lake and Longgan Lake, while that in Chaohu Lake and Xijiu Lake increased since the 1950s and substantially increased since the 1980s, although a decrease occurred since 2000 AD in Xijiu Lake. Heavy metal enrichment was strongly related to human activities in the catchment. The development of urbanization and industrialization was much more rapid in the catchments of Chaohu Lake and Xijiu Lake than of the other two lakes, and thus large amounts of anthropogenically sourced heavy metals were discharged into the lakes, which resulted in a higher contamination risk. However, human activities in the Longgan Lake and Taibai Lake catchments mainly involved agriculture, which contributed a relatively small portion of heavy metals to the lakes. PMID:24218840

  9. Lakes and reservoirs

    SciTech Connect

    Taub, F.B.

    1984-01-01

    This volume in the Ecosystems of the World series studies lakes and reservoirs. The book opens with a discussion of the ecosystem processes that are common to all lakes and reservoirs and then proceeds to a description of mathematical models of these processes. The chapters concentrate on lakes and reservoirs in different parts of the world, ranging from polar to tropical lakes, and in many of the chapters the effects of human activities such as dam construction, increased nutrient inputs, toxic contaminants and fish introduction, are also considered. The book concludes with a summary of the efforts at lake restoration that are being undertaken in many communities in an attempt to undo the damage that has resulted from some of these activities.

  10. Lake trout in northern Lake Huron spawn on submerged drumlins

    USGS Publications Warehouse

    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.

    2014-01-01

    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.

  11. Spatial patterns in PCB concentrations of Lake Michigan lake trout

    USGS Publications Warehouse

    Madenjian, Charles P.; DeSorcie, Timothy J.; Stedman, Ralph M.; Brown, Edward H., Jr.; Eck, Gary W.; Schmidt, Larry J.; Hesselberg, Robert J.; Chernyak, Sergei M.; Passino-Reader, Dora R.

    1999-01-01

    Most of the PCB body burden in lake trout (Salvelinus namaycush) of the Great Lakes is from their food. PCB concentrations were determined in lake trout from three different locations in Lake Michigan during 1994–1995, and lake trout diets were analyzed at all three locations. The PCB concentrations were also determined in alewife (Alosa pseudoharengus), rainbow smelt (Osmerus mordax), bloater (Coregonus hoyi), slimy sculpin (Cottus cognatus), and deepwater sculpin (Myoxocephalus thompsoni), five species of prey fish eaten by lake trout in Lake Michigan, at three nearshore sites in the lake. Despite the lack of significant differences in the PCB concentrations of alewife, rainbow smelt, bloater, slimy sculpin, and deepwater sculpin from the southeastern nearshore site near Saugatuck (Michigan) compared with the corresponding PCB concentrations from the northwestern nearshore site near Sturgeon Bay (Wisconsin), PCB concentrations in lake trout at Saugatuck were significantly higher than those at Sturgeon Bay. The difference in the lake trout PCB concentrations between Saugatuck and Sturgeon Bay could be explained by diet differences. The diet of lake trout at Saugatuck was more concentrated in PCBs than the diet of Sturgeon Bay lake trout, and therefore lake trout at Saugatuck were more contaminated in PCBs than Sturgeon Bay lake trout. These findings were useful in interpreting the long-term monitoring series for contaminants in lake trout at both Saugatuck and the Wisconsin side of the lake.

  12. Fish Lake, Utah - shallow seismic investigation of a lake-filled high-altitude graben

    NASA Astrophysics Data System (ADS)

    Harris, M. S.; Oliviera-Manna, M.; Bailey, C.; Marchetti, D. W.; Brunelle, A.; Abbott, M. B.; Larsen, D. J.; Stoner, J. S.; Grimm, E. C.; Donovan, J.; Anderson, L.; Power, M. J.; Chavez, V.; Carter, V.; Hart, I.

    2015-12-01

    Fish Lake formed in a portion of the 20-km x 2.5-km wide NE-SW trending graben within the High Plateaus of Utah, on the border between the Basin and Range to the west and the Canyon Lands east. This presentation focuses on the shallow seismic stratigraphic architecture of the lake. Marchetti et al. (this meeting) focuses details of a shallow core collected in 2014. With a lake surface at 2700m, avg. depth of 27m (max 37m), the lake is flanked NW by a 15° slope up to a formerly glaciated Hightop plateau (3545m) and is bound to the SE by a 30° NW facing slope off the Mytoge crest (3050m). The drainage basin is 74 km2 with ~75% of the catchment draining the Hightop from four distinct streams. Pelican Canyon (glaciated) and Doctor Canyon (unglaciated) provide most drainage into the basin, with Bowery and Twin creeks draining only the slope. These streams flow through organic-rich meadows at the edge of the lake. Only one small stream drains NW into the lake from the small Crater Lakes graben (2850m) off the Mytoge. Bathymetric surveys in the lake highlight a submerged moraine to the NE, a gently sloping bottom that reaches maximum depth off the steep wall to the SE, and small delta-form features off each of the creeks on the NW edge. Chirp seismic surveys (2-16 kHz) consistently penetrate the upper 40-m (up to ~55m). The oldest visible reflectors rise into the submerged moraine to the NE, ending in a complex set of truncated and discontinuous beds eluding to soft sediment push at the front of the glacier. Along the edge near the creeks to the NW, multiple sets of downlapping reflectors, gas pockets, and chaotic beds with lobate tops define what we interpret as deltaic deposition, possible lower lake levels with marsh systems, and slope failures. The majority of the lake is underlain by flat-lying reflectors that bound sedimentary packages spanning the entirety of the basin interior. The uppermost layers have recently been cored where seismic reflectors are continuous

  13. Seismic activity noted at Medicine Lake Highlands

    SciTech Connect

    Blum, D.

    1988-12-01

    The sudden rumble of earthquakes beneath Medicine Lake Highlands this fall gave geologists an early warning that one of Northern California's volcanoes may be stirring back to life. Researchers stressed that an eruption of the volcano is not expected soon. But the flurry of underground shocks in late September, combined with new evidence of a pool of molten rock beneath the big volcano, has led them to monitor Medicine Lake with new wariness. The volcano has been dormant since 1910, when it ejected a brief flurry of ash - worrying no one. A federal team plans to take measurements of Medicine Lake, testing for changes in its shape caused by underground pressures. The work is scheduled for spring because snows have made the volcano inaccessible. But the new seismic network is an effective lookout, sensitive to very small increases in activity.

  14. Energy and water in the Great Lakes.

    SciTech Connect

    Tidwell, Vincent Carroll

    2011-11-01

    The nexus between thermoelectric power production and water use is not uniform across the U.S., but rather differs according to regional physiography, demography, power plant fleet composition, and the transmission network. That is, in some regions water demand for thermoelectric production is relatively small while in other regions it represents the dominate use. The later is the case for the Great Lakes region, which has important implications for the water resources and aquatic ecology of the Great Lakes watershed. This is today, but what about the future? Projected demographic trends, shifting lifestyles, and economic growth coupled with the threat of global climate change and mounting pressure for greater U.S. energy security could have profound effects on the region's energy future. Planning for such an uncertain future is further complicated by the fact that energy and environmental planning and regulatory decisionmaking is largely bifurcated in the region, with environmental and water resource concerns generally taken into account after new energy facilities and technologies have been proposed, or practices are already in place. Based on these confounding needs, the objective of this effort is to develop Great Lakes-specific methods and tools to integrate energy and water resource planning and thereby support the dual goals of smarter energy planning and development, and protection of Great Lakes water resources. Guiding policies for this planning are the Great Lakes and St. Lawrence River Basin Water Resources Compact and the Great Lakes Water Quality Agreement. The desired outcome of integrated energy-water-aquatic resource planning is a more sustainable regional energy mix for the Great Lakes basin ecosystem.

  15. Initial Results from the Circumarctic Lakes Observation Network (CALON) Project

    NASA Astrophysics Data System (ADS)

    Hinkel, K. M.; Lenters, J. D.; Grosse, G.; Arp, C. D.; Jones, B.; Beck, R. A.; Eisner, W. R.; Frey, K. E.; Liu, H.; Kim, C.; Townsend-Small, A.

    2011-12-01

    on lakes near the Arctic coast, reflecting the marine influence. Rapid warming follows ice-cover decay, with water temperature responding synchronously to daily and synoptic weather variations across the area. Inland lakes are significantly (6°C) warmer in mid-summer than those near the coast, which is also in accordance with the regional climatic gradient. All lakes are well-mixed and largely isothermal, with minimal thermal stratification (< 2°C) occurring only during calm, sunny periods in deeper lakes (> 2m). During the last several years lake water temperature, water level, and ice thickness measurements have also been collected from in a number of lakes located near a coastal hub site in the vicinity of Teshekpuk Lake. This dataset also reveals variability in the thermal regime over small geographic areas both within and between years with respect to differences in lake depth, lake size, and local environmental conditions.

  16. Evidence of offshore lake trout reproduction in Lake Huron

    USGS Publications Warehouse

    DeSorcie, Timothy J.; Bowen, Charles A., II

    2003-01-01

    Six Fathom Bank-Yankee Reef, an offshore reef complex, was an historically important spawning area believed to represent some of the best habitat for the rehabilitation of lake trout Salvelinus namaycush in Lake Huron. Since 1986, lake trout have been stocked on these offshore reefs to reestablish self-sustaining populations. We sampled with beam trawls to determine the abundance of naturally reproduced age-0 lake trout on these offshore reefs during May-July in 1994-1998 and 2000-2002. In total, 123 naturally reproduced lake trout fry were caught at Six Fathom Bank, and 2 naturally reproduced lake trout fry were caught at nearby Yankee Reef. Our findings suggest that this region of Lake Huron contains suitable habitat for lake trout spawning and offers hope that lake trout rehabilitation can be achieved in the main basin of Lake Huron.

  17. Iron oxide from a seasonally anoxic lake

    NASA Astrophysics Data System (ADS)

    Tipping, E.; Woof, C.; Cooke, D.

    1981-09-01

    The ferric oxide formed by oxidation of Fe(II) in Esthwaite Water, U.K., during the lake's seasonal thermal stratification and deep-water anoxia consists of amorphous particles which are approximately spherical or ellipsoidal, with diameters in the range 0.05-0.5 μm. Concentrations in the lake are 1011-1012 particles per litre, corresponding to 3 mg l-1 Fe. Unlike iron oxides of similar chemical composition formed by oxidative mechanisms in soil-borne waters, the particles do not appear to be composed of small primary particles. This is possibly because in the lake they form slowly, at low supersaturation. The particles contain 30-40% by weight Fe. The carbon content is uncertain because of contamination but is in the range 4-18%. Humic carbon contributes at least 4-7% of the total weight. Other major elements present are P, N, Mn, Si, S. Ca and Mg, comprising between them up to 8% of the total weight. The particles are negatively charged probably because of adsorbed humic substances, and also phosphate and silicate. Their electrophoretic mobility-pH dependence is similar to those of synthetic iron oxides added to samples of surface Esthwaite Water. The calculated zeta potential is - 27 mV, which is sufficiently high to make flocculation slow under lake conditions. The low flocculation rate partially accounts for the formation of a well-defined peak of particulate iron in the water column of the lake.

  18. Numerical model of crater lake eruptions

    NASA Astrophysics Data System (ADS)

    Morrissey, M.; Gisler, G.; Weaver, R.; Gittings, M.

    2010-12-01

    We present results from a numerical investigation of subaqueous eruptions involving superheated steam released through a lake mimicking the volcanic setting at Mt. Ruapehu. The simulations were conducted using an adaptive mesh, multi-material, hydrodynamics code with thermal conduction SAGE, (Simple Adaptive Grid Eulerian). Parameters investigated include eruption pressure, lake level and mass of superheated vapor. The simulations produced a spectrum of eruption styles from vapor cavities to radial jets that resulted in hazards that ranged from small-scale waves to high amplitude surges that reached and cascaded over the edge of the crater rim. There was an overall tendency for lake surface activity to increase (including wave amplitude) with increasing mass of superheated vapor and eruption pressure. Surface waves were induced by the formation and collapse of a gas cavity. The collapse of the cavity is considered to play a major role in the characteristic features observed during a subaqueous eruption. The additional mass of superheated vapor produced a larger cavity that displaced a larger area of the lake surface resulting in fast moving surges upon the collapse of the cavity. High lake levels (>90 m) appear to suppress the development of explosive jetting activity when eruption pressures are <10 MPa. At very large eruption pressures (>10 MPa), vertical jets and radial ejections of steam and water can occur in water depths >90 m. Less explosive eruption styles can produce hazardous events such as lahars by the outward movement of surface waves over the crater rim.

  19. A review of lake trout (Salvelinus namaycush) restoration in Lake Ontario from an early life history perspective

    USGS Publications Warehouse

    Fitzsimons, John; Lantry, Brian F.; O'Gorman, Robert

    2003-01-01

    The authors conclude that small numbers of lake trout spawned successfully each year during 1992-97 in Lake Ontario, although this has yet to result in a trend of increasing natural reproduction. Juxtaposed with the high abundance of mature fish (Selgeby et al., 1995), the situation in Lake Ontario suggests a reduction in reproductive efficiency. This could result from mortality factors that may to a certain extent be density independent because recruitment has remained flat in the face of increasing spawner abundance. According to RESTORE, such factors are likely acting during the first year of life. Accordingly, the authors herin review the evidence that former barriers to lake trout reproduction in Lake Ontario that act as early-life-stage bottlenecks have been removed. In addition, the authors review other potential new barriers for which there has only recently been enough information to judge their relative importance.

  20. Unusual bacterioplankton community structure in ultra-oligotrophic Crater Lake

    USGS Publications Warehouse

    Urbach, Ena; Vergin, Kevin L.; Morse, Ariel

    2001-01-01

    The bacterioplankton assemblage in Crater Lake, Oregon (U.S.A.), is different from communities found in other oxygenated lakes, as demonstrated by four small subunit ribosomal ribonucleic acid (SSU rRNA) gene clone libraries and oligonucleotide probe hybridization to RNA from lake water. Populations in the euphotic zone of this deep (589 m), oligotrophic caldera lake are dominated by two phylogenetic clusters of currently uncultivated bacteria: CL120-10, a newly identified cluster in the verrucomicrobiales, and ACK4 actinomycetes, known as a minor constituent of bacterioplankton in other lakes. Deep-water populations at 300 and 500 m are dominated by a different pair of uncultivated taxa: CL500-11, a novel cluster in the green nonsulfur bacteria, and group I marine crenarchaeota. b-Proteobacteria, dominant in most other freshwater environments, are relatively rare in Crater Lake (<=16% of nonchloroplast bacterial rRNA at all depths). Other taxa identified in Crater Lake libraries include a newly identified candidate bacterial division, ABY1, and a newly identified subcluster, CL0-1, within candidate division OP10. Probe analyses confirmed vertical stratification of several microbial groups, similar to patterns observed in open-ocean systems. Additional similarities between Crater Lake and ocean microbial populations include aphotic zone dominance of group I marine crenarchaeota and green nonsulfur bacteria. Comparison of Crater Lake to other lakes studied by rRNA methods suggests that selective factors structuring Crater Lake bacterioplankton populations may include low concentrations of available trace metals and dissolved organic matter, chemistry of infiltrating hydrothermal waters, and irradiation by high levels of ultraviolet light.

  1. Multi-year wind dynamics around Lake Tanganyika

    NASA Astrophysics Data System (ADS)

    Docquier, D.; Thiery, W.; Lhermitte, S.; van Lipzig, N.

    2016-02-01

    Lake Tanganyika is the second largest freshwater lake in the world by volume and is of prime importance for the regional economy in East Africa. Although the lake is recognized as a key component of the regional climate system, little is known about atmospheric dynamics in its surroundings. To understand this role, we analyze winds around Lake Tanganyika as modeled by a high resolution (7 km) regional climate model (Consortium for Small-scale Modeling in Climate Mode) over the period 1999-2008. Modeled surface wind speed and direction are in very good agreement with high resolution (12.5 km) Quick Scatterometer (QuikSCAT) satellite wind observations during the dry season. Comparison of a control run with a model simulation where all lake pixels are replaced by representative land pixels indicates that mean surface wind speed over Lake Tanganyika almost doubles due to lake presence. Furthermore, a region of higher surface wind speed in the central part of the lake is identified and confirmed by QuikSCAT observations. A combination of wind channeling along valley mountains and wind confluence on the upwind side of the lake is responsible for this speed-up. The lower wind speeds in the rest of the lake result from blocked conditions due to more pronounced orography. Finally, the model captures a zone of higher wind speed at around 2 km height, associated with the low-level Somali jet. These results demonstrate that high resolution climate modeling allows a detailed understanding of wind dynamics in the vicinity of Lake Tanganyika.

  2. Estimating seasonal and annual lake level changes of groundwater-fed lakes in northeastern Germany using RapidEye archive data

    NASA Astrophysics Data System (ADS)

    Heine, Iris; Oeser, Julian; Itzerott, Sibylle; Kleinschmit, Birgit

    2015-04-01

    Groundwater-fed lakes in northeastern Germany revealed massive fluctuations in their lake levels during the last decades. However, precise in situ lake level measurements were only recorded for a small numbers of lakes. In this study we evaluate the potential of multi-spectral images (RapidEye) to extract the evolution of former water-land-boundaries and estimate the variation in lake levels. The main test area is lake Fürstenseer See near Neustrelitz in northeastern Germany. Lake Fürstenseer See is characterized by a significant increase of its lake level since 2010. This increase is observed by 37 RapidEye images recorded between 2009 and 2015. After the preprocessing of the RapidEye time series, we extracted the water-land-boundaries automatically using the NIR band and the normalized difference water index (NDWI). The corresponding lake levels were estimated by merging the water-land-boundary with a high-resolution digital elevation model (DEM) showing the terrain and the underwater topography of the lake. As the shore of lake Fürstenseer See is heterogeneous in topography and vegetation, we selected different subsets for the level reconstruction and evaluation. The evaluation of the method based on in situ gauged lake levels, DEM analyses and DGPS measurements in 2014. RapidEye images enable the monitoring of seasonal and annual variations of lake level changes of lake Fürstenseer See, but the accuracy of the estimated levels strongly depends on the precision of the extracted water-land-boundary. In the RapidEye images the water-land-boundary is often covered by overhanging trees and dense reed. Thus, a shoreline subset with little or no vegetation as well as shallow topography are required for precise reconstruction of lake levels.

  3. LAKE RESTORATION BY DILUTION: MOSES LAKE, WASHINGTON

    EPA Science Inventory

    Dilution water, low in macronutrients, was added to Moses Lake on three occasions in 1977 and once in 1978 during the spring-summer period. The addition resulted in reducing the annual average inflow concentration of phosphorus from about 130-140 micrograms/l to 100 micrograms/l....

  4. A comparison of shoreline seines with fyke nets for sampling littoral fish communities in floodplain lakes

    USGS Publications Warehouse

    Clark, S.J.; Jackson, J.R.; Lochmann, S.E.

    2007-01-01

    We compared shoreline seines with fyke nets in terms of their ability to sample fish species in the littoral zone of 22 floodplain lakes of the White River, Arkansas. Lakes ranged in size from less than 0.5 to 51.0 ha. Most contained large amounts of coarse woody debris within the littoral zone, thus making seining in shallow areas difficult. We sampled large lakes (>2 ha) using three fyke nets; small lakes (<2 ha) were sampled using two fyke nets. Fyke nets were set for 24 h. Large lakes were sampled with an average of 11 seine hauls/ lake and small lakes were sampled with an average of 3 seine hauls/lake, but exact shoreline seining effort varied among lakes depending on the amount of open shoreline. Fyke nets collected more fish and produced greater species richness and diversity measures than did seining. Species evenness was similar for the two gear types. Two species were unique to seine samples, whereas 13 species and 3 families were unique to fyke-net samples. Although fyke nets collected more fish and more species than did shoreline seines, neither gear collected all the species present in the littoral zone of floodplain lakes. These results confirm the need for a multiple-gear approach to fully characterize the littoral fish assemblages in floodplain lakes. ?? Copyright by the American Fisheries Society 2007.

  5. Lake Roosevelt Fisheries Evaluation Program; Meadow Creek vs. Lake Whatcom Stock Kokanee Salmon Investigations in Lake Roosevelt, Annual Report 2002.

    SciTech Connect

    McLellan, Holly

    2003-03-01

    Lake Whatcom, Washington kokanee have been stocked in Lake Roosevelt since 1987 with the primary objective of creating a self-sustaining fishery. Success has been limited by low recruitment to the fishery, low adult returns to hatcheries, and a skewed sex ratio. It was hypothesized that a stock native to the upper Columbia River might perform better than the coastal Lake Whatcom stock. Kokanee from Meadow Creek, a tributary of Kootenay Lake, British Columbia were selected as an alternative stock. Post smolts from each stock were released from Sherman Creek Hatchery in late June 2000 and repeated in 2001. Stock performance was evaluated using three measures; (1) number of returns to Sherman Creek, the primary egg collection facility, (2) the number of returns to 86 tributaries sampled and, (3) the number of returns to the creel. In two repeated experiments, neither Meadow Creek or Lake Whatcom kokanee appeared to be capable of providing a run of three-year old spawners to sustain stocking efforts. Less than 10 three-years olds from either stock were collected during the study period. Chi-square analysis indicated age two Meadow Creek kokanee returned to Sherman Creek and to other tributaries in significantly higher numbers when compared to the Lake Whatcom stock in both 2000 and 2001. However, preliminary data from the Spokane Tribe of Indians indicated that a large number of both stocks were precocial before they were stocked. The small number of hatchery three-year olds collected indicated that the current hatchery rearing and stocking methods will continue to produce a limited jacking run largely composed of precocious males and a small number of three-year olds. No kokanee from the study were collected during standard lake wide creel surveys. Supplemental creel data, including fishing derbies, test fisheries, and angler diaries, indicated anglers harvested two-year-old hatchery kokanee a month after release. The majority of the two-year old kokanee harvested

  6. Modeling Prairie Pothole Lakes: Linking Satellite Observation and Calibration (Invited)

    NASA Astrophysics Data System (ADS)

    Schwartz, F. W.; Liu, G.; Zhang, B.; Yu, Z.

    2009-12-01

    behavior of a complex of closed lakes vary in scale from the footprint of a small house to that of a small city.

  7. Clay mineralogy of Pleistocene Lake Tecopa, Inyo County, California

    USGS Publications Warehouse

    Starkey, Harry C.; Blackmon, Paul D.

    1979-01-01

    Pleistocene Lake Tecopa in southeastern Inyo County, Calif., was formed when the Amargosa River was blocked at the southern end of its valley. The lake acted as a settling basin for detrital material being transported by the river. This detritus consisted of clays, quartz, feldspars, and micas which became mudstones and siltstones. These mudstones and siltstones, much eroded and dissected after the draining of the lake, extend over the entire basin and are interbedded with tuffs formed by the intermittent deposition of volcanic ashfalls in the former lake waters. These lightcolored mudstones and siltstones are tough and well indurated and break with a conchoidal fracture. The predominant clay mineral in these detrital beds is a lithiumbearing saponite, which is found not only in the lake beds but also in the area beyond the boundaries of the lake, especially in fluvial deposits in the drainage basin of the Amargosa River to the north. This saponite does not contain enough lithium to be classified as a hectorite, and we have observed no indications that this clay consists of a mixture of two phases, such as hectorite and a diluent. Some authigenic dioctahedral montmorillonite, found only in small quantities close to the tuffs, was formed by alteration of the volcanic glass of the tuffs and was then admixed with the overlying or underlying detrital clays. The only authigenic clay-type mineral found in any significant quantity is sepiolite, found near the edges of the lake basin and stratigraphically located mainly within a meter of the two uppermost tuffs. This sepiolite probably was precipitated when silica became available to the magnesium-bearing lake water through dissolution of the volcanic ash. Precipitation of sepiolite probably did not occur within the tuffs owing to the presence of alumina in solution. Zeolites were produced there and sepiolite formed outside the margins of the tuffs. Also formed by the high-pH lake waters were water-soluble minerals, which

  8. The comparative limnology of Lakes Nyos and Monoun, Cameroon

    USGS Publications Warehouse

    Kling, George; Evans, William C; Tanyileke, Gregory

    2015-01-01

    Lakes Nyos and Monoun are known for the dangerous accumulation of CO2 dissolved in stagnant bottom water, but the shallow waters that conceal this hazard are dilute and undergo seasonal changes similar to other deep crater lakes in the tropics. Here we discuss these changes with reference to climatic and water-column data collected at both lakes during the years following the gas release disasters in the mid-1980s. The small annual range in mean daily air temperatures leads to an equally small annual range of surface water temperatures (ΔT ~6–7 °C), reducing deep convective mixing of the water column. Weak mixing aids the establishment of meromixis, a requisite condition for the gradual buildup of CO2 in bottom waters and perhaps the unusual condition that most explains the rarity of such lakes. Within the mixolimnion, a seasonal thermocline forms each spring and shallow diel thermoclines may be sufficiently strong to isolate surface water and allow primary production to reduce PCO2 below 300 μatm, inducing a net influx of CO2 from the atmosphere. Surface water O2 and pH typically reach maxima at this time, with occasional O2 oversaturation. Mixing to the chemocline occurs in both lakes during the winter dry season, primarily due to low humidity and cool night time air temperature. An additional period of variable mixing, occasionally reaching the chemocline in Lake Monoun, occurs during the summer monsoon season in response to increased frequency of major storms. The mixolimnion encompassed the upper ~40–50 m of Lake Nyos and upper ~15–20 m of Lake Monoun prior to the installation of degassing pipes in 2001 and 2003, respectively. Degassing caused chemoclines to deepen rapidly. Piping of anoxic, high-TDS bottom water to the lake surface has had a complex effect on the mixolimnion. Algal growth stimulated by increased nutrients (N and P) initially stimulated photosynthesis and raised surface water O2 in Lake Nyos, but O2 removal through oxidation of iron

  9. Geohydrologic setting of Mirror Lake, West Thornton, New Hampshire

    USGS Publications Warehouse

    Winter, T.C.

    1984-01-01

    The drainage basin of Mirror Lake, New Hampshire is characterized by high knobs and ridges and steep land slopes. The lake is situated in the lower part of the basin, largely within glacial drift. Drift in most of the Mirror Lake drainage basin is till, which is as much as 50 meters thick, Crystalline bedrock underlying the drift is composed of schist, slate, and quartz monzonite of earliest Devonian age. These rocks are intensely folded and contain numerous fractures. Three small streams flow into Mirror Lake. Streamflow discharge into Mirror Lake differs between the two largest subbasins. Basin NW, which has a more round shape and thicker glacial drift than basin W, has greater stream discharge as well as greater sustained base flow. Ground water moves into most parts of Mirror Lake, and losses to ground water occur principally on the southeast side. Water-level data from piezometers and bedrock wells indicate dynamic ground-water movement within the fractured bedrock underlying Mirror Lake. These data also indicate very active interchange of ground water between bedrock and the overlying glacial drift. There are particularly strong hydraulic head gradients from the bedrock into the drift in the area between Mirror Lake and Hubbard Brook. (USGS)

  10. Comparisons of observed and modelled lake δ18O variability

    NASA Astrophysics Data System (ADS)

    Jones, Matthew D.; Cuthbert, Mark O.; Leng, Melanie J.; McGowan, Suzanne; Mariethoz, Gregoire; Arrowsmith, Carol; Sloane, Hilary J.; Humphrey, Kerenza K.; Cross, Iain

    2016-01-01

    With the substantial number of lake sediment δ18O records published in recent decades, a quantitative, process-based understanding of these systems can increase our understanding of past climate change. We test mass balance models of lake water δ18O variability against five years of monthly monitoring data from lakes with different hydrological characteristics, in the East-Midlands region of the UK, and the local isotope composition of precipitation. These mass balance models can explain up to 74% of the measured lake water isotope variability. We investigate the sensitivity of the model to differing calculations of evaporation amount, the amount of groundwater, and to different climatic variables. We show there is only a small range of values for groundwater exchange flux that can produce suitable lake water isotope compositions and that variations in evaporation and precipitation are both required to produce recorded isotope variability in lakes with substantial evaporative water losses. We then discuss the potential for this model to be used in a long-term, palaeo-scenario. This study demonstrates how long term monitoring of a lake system can lead to the development of robust models of lake water isotope compositions. Such systematics-based explanations allow us to move from conceptual, to more quantified reconstructions of past climates and environments.

  11. Lake Mead, NV

    NASA Technical Reports Server (NTRS)

    1973-01-01

    Lake Mead, Nevada, (36.0N, 114.5E) where the water from the Colorado River empties after it's 273 mile journey through the Grand Canyon of Arizona is the subject of this photo. Other features of interest are Hoover Dam on the south shore of Lake Mead where cheap hydroelectric power is secondary to the water resources made available in this northern desert region and the resort city of Las Vegas, just to the west of Lake Mead. In this harsh desert environment, color infrared photography readily penetrates haze, detects and portrays vegetation as shades of red.

  12. Reforms and Innovations in Estonian Education. Baltische Studien zur Erziehungs- und Sozialwissenschaft. Volume 16

    ERIC Educational Resources Information Center

    Mikk, Jaan, Ed.; Veisson, Marika, Ed.; Luik, Piret, Ed.

    2008-01-01

    This collection of papers provides a small overview of educational research in Estonia. The papers in the collection treat school reforms since the renewal of independence in 1991, new approaches to teacher training, the implementation of a child-centred approach in school, the achieving of educational aims and other actual topics in education.…

  13. Dynamics of Playa lakes in the Texas High Plains

    NASA Technical Reports Server (NTRS)

    Reeves, C. C., Jr.

    1974-01-01

    Three small playa lake basins on the Texas High Plains were originally selected as ERTS-1 test sites to attempt correlation of ERTS-1 imagery with the water balance ecosystem and geology/morphology of the lake basins. The 5-mile long large Double Lakes playa complex was also instrumented as an alternate test site. Analysis of bands 6 and 7 of ERTS-1 MSS imagery shows that lake basins as small as 200 m in diameter (+ or - 10 acres) can be reliably classified as being wet or dry, thus supplying the methodology for a rapid, periodic census of surface water. A cost/benefit analysis reveals that the use of MSS imagery for such a census results in a 66 to 200-fold cost reduction when compared to the costs of using other conventional methods.

  14. Simulating 2,368 temperate lakes reveals weak coherence in stratification phenology

    USGS Publications Warehouse

    Read, Jordan S.; Winslow, Luke A.; Hansen, Gretchen J. A.; Van Den Hoek, Jamon; Hanson, Paul C.; Bruce, Louise C; Markfort, Corey D

    2014-01-01

    Changes in water temperatures resulting from climate warming can alter the structure and function of aquatic ecosystems. Lake-specific physical characteristics may play a role in mediating individual lake responses to climate. Past mechanistic studies of lake-climate interactions have simulated generic lake classes at large spatial scales or performed detailed analyses of small numbers of real lakes. Understanding the diversity of lake responses to climate change across landscapes requires a hybrid approach that couples site-specific lake characteristics with broad-scale environmental drivers. This study provides a substantial advancement in lake ecosystem modeling by combining open-source tools with freely available continental-scale data to mechanistically model daily temperatures for 2,368 Wisconsin lakes over three decades (1979-2011). The model accurately predicted observed surface layer temperatures (RMSE: 1.74°C) and the presence/absence of stratification (81.1% agreement). Among-lake coherence was strong for surface temperatures and weak for the timing of stratification, suggesting individual lake characteristics mediate some - but not all - ecologically relevant lake responses to climate.

  15. Biological studies of atmospheric deposition impact on biota in Kola North Mountain Lakes, Russia

    SciTech Connect

    Yakovlev, V.; Sharov, A.; Vandysh, O.

    1996-12-31

    In the framework of the AL:PE projects, biological studies of phyto-, zooplankton and zoobenthos communities of a small lakes situated in Chuna tundra and Chibiny mountains in Murmansk region were performed in 1993-1995. The lakes are the typical oligotrophic mountain lakes. In the Chibiny lake phytoplankton were presented mostly by species from rock catchment area. Summer phytoplankton state in the lakes showed no acidification in 1993-1995. However, the great number dead cells of acid tolerance diatoms, such as Tabellaria flocculosa found in the Chuna lake in summer period, may indicate a presence of acid episodes. Zooplankton of the lakes is typical for high oligotrophic mountain lakes. However, lack of the acid sensitive daphniidae cladocerans seems to be a result of acidification effects. There were no significant relationships between benthic invertebrates species composition and present water acidity of the lakes. The typical for mountain lakes taxa (Prodiamesinae chironomids, stone flies and mayflies) were found in lake shore and streams. Despite the only little evidence of damage in biota, the further biological studies would be useful for long-term monitoring of the mountain lakes.

  16. Assessing risk of non-compliance of phosphorus standards for lakes in England and Wales

    NASA Astrophysics Data System (ADS)

    Duethmann, D.; Anthony, S.; Carvalho, L.; Spears, B.

    2009-04-01

    High population densities, use of inorganic fertilizer and intensive livestock agriculture have increased phosphorus loads to lakes, and accelerated eutrophication is a major pressure for many lakes. The EC Water Framework Directive (WFD) requires that good chemical and ecological quality is restored in all surface water bodies by 2015. Total phosphorus (TP) standards for lakes in England and Wales have been agreed recently, and our aim was to estimate what percentage of lakes in England and Wales is at risk of failing these standards. With measured lake phosphorus concentrations only being available for a small number of lakes, such an assessment had to be model based. The study also makes a source apportionment of phosphorus inputs into lakes. Phosphorus loads were estimated from a range of sources including agricultural loads, sewage effluents, septic tanks, diffuse urban sources, atmospheric deposition, groundwater and bank erosion. Lake phosphorus concentrations were predicted using the Vollenweider model, and the model framework was satisfactorily tested against available observed lake concentration data. Even though predictions for individual lakes remain uncertain, results for a population of lakes are considered as sufficiently robust. A scenario analysis was carried out to investigate to what extent reductions in phosphorus loads would increase the number of lakes achieving good ecological status in terms of TP standards. Applying the model to all lakes in England and Wales greater than 1 ha, it was calculated that under current conditions roughly two thirds of the lakes would fail the good ecological status with respect to phosphorus. According to our estimates, agricultural phosphorus loads represent the most frequent dominant source for the majority of catchments, but diffuse urban runoff also is important in many lakes. Sewage effluents are the most frequent dominant source for large lake catchments greater than 100 km². The evaluation in terms of

  17. Climate impacts on water balance of a shallow steppe lake in Eastern Austria (Lake Neusiedl)

    NASA Astrophysics Data System (ADS)

    Soja, Gerhard; Züger, Johann; Knoflacher, Markus; Kinner, Paul; Soja, Anna-Maria

    2013-02-01

    SummaryLake Neusiedl, the largest lake in Austria, is especially sensitive to climate variations due to its extreme shallowness and a small catchment area. Historical records indicate that large variations of the lake area have occurred naturally (0% to >150% of present) but contemporary touristic uses of the lake require a largely constant water level. This dependence increases the regional economic vulnerability. Water balance of the lake as influenced by weather conditions was studied in detail. 79% of water input was due to precipitation, whereas more than 90% of water output was caused by evapotranspiration. Long-term observation of annual and seasonal precipitation sums, starting in 1865, revealed a slow downward trend of 15 years moving averages by 6 ± 1 mm/decade, masked by large interannual variations of the original data (s.d.: ±120 mm). Multidecadal oscillation indices (AMO, NAO, MOI) were tested against patterns of precipitation, air temperature and hydrological parameters of Lake Neusiedl. The clearest relation was observed between air temperature and North Atlantic oscillation index (p < 0.0001). Water level and volume of Lake Neusiedl are very sensitive to precipitation changes with after effects of individual years lasting up to 2 years. Summer precipitation is more important for lake water amount than the other seasons. The major surface water input to Lake Neusiedl is coming from River Wulka. Its annual discharge (15 years moving averages) showed a variable, moderately decreasing trend for the period 1961-2010 by -1.2 ± 0.6 × 106 m3/decade. Waste water treatment plants contributed up to 68% of monthly flow of River Wulka into the lake. Precipitation of the current and the previous year, and in some months also temperature influenced Wulka's flow significantly. Evaporative losses from the lake and its reed belt were shown to increase over the last 33 years (+48 ± 11 mm/decade); as main drivers decreasing relative air humidity and increasing

  18. Studying the possibility of separate and joint combustion of Estonian shales and oil shale retort gas at thermal power plants

    NASA Astrophysics Data System (ADS)

    Roslyakov, P. V.; Attikas, Raivo; Zaichenko, M. N.; Pleshanov, K. A.; Ionkin, I. L.

    2015-10-01

    Results from investigations of joint and separate combustion of shale with a low heating value and oil shale retort gas (OSRG) are presented. The question about the possibility of further using shale as basic fuel is presently placed on the agenda. This matter is connected with the fact that the environmental regulations are imposing increasingly more stringent limits on emissions of harmful substances and that a decrease in the shale heating value is predicted. An adequate mathematical model of one of the TP-101 boilers installed at the Estonian power plant was developed and verified for carrying out investigations. Criteria for determining the reliability, efficiency, and environmental safety of equipment operation were formulated based on the operating chart, regulatory documents, and environmental requirements. Assessment of the possibility of boiler operation and the boiler unit as a whole in firing shale with a low calorific value has shown that despite fulfilling the required superheated steam parameters, quite a number of limitations relating to reliable operation of the boiler are not complied with. In addition, normal operation of forced-draft equipment and mills is possible only at low loads. For operation with joint combustion of shale and OSRG, the fractions of degraded-quality shale and OSRG (by heat) at which reliable and efficient operation of the boiler and boiler unit is ensured in the entire working range of loads with fulfilling the environmental standards are determined. Proposals on modifying the equipment for joint combustion of shale and OSRG are formulated. Boiler operation with firing OSRG as main fuel was modeled for three versions of furnace waterwall thermal efficiency with a view to estimate possible changes of boiler operation in carrying out waterwall cleaning operations. Calculation results have shown that operation of the boiler and boiler unit meeting the elaborated criteria is possible in the entire working range of loads with

  19. Can lake sensitivity to desiccation be predicted from lake geometry?

    NASA Astrophysics Data System (ADS)

    Torabi Haghighi, Ali; Menberu, Meseret Walle; Aminnezhad, Mousa; Marttila, Hannu; Kløve, Bjørn

    2016-08-01

    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.

  20. Holocene Lake Records on Kamchatka

    NASA Astrophysics Data System (ADS)

    Diekmann, Bernhard; Biskaborn, Boris; Chapligin, Bernhard; Dirksen, Oleg; Dirksen, Veronika; Hoff, Ulrike; Meyer, Hanno; Nazarova, Larisa

    2014-05-01

    The availibility of terrestrial records of Holocene palaeoenvironmental changes in eastern Siberia still is quite limited, compared to other regions on the northern hemisphere. In particular, the Kamchatka Peninsula as an important climate-sensitive region is very underrepresented. Situated at the border of northeastern Eurasia, the maritime-influenced terrestrial setting of Kamchatka offers the potential to pinpoint connections of environmental changes between the periglacial and highly continental landmasses of eastern Siberia and the sub-Arctic Pacific Ocean and Sea of Okhotsk. The study region lies at the eastern end-loop of the global thermohaline ocean conveyor belt and is strongly affected by atmospheric teleconnections. Volcanic, tectonic, and glacial processes overprint palaeoenvironmental changes in addition to primary climate forcing. In order to widen our understanding of plaeoclimate dynamics on Kamchatka, sediment cores from different lake systems and peat sections were recovered and analysed by a multi-proxy approach, using sedimentological and geochemical data as well as fossil bioindicators, such as diatoms, pollen, and chironomids. Chronostratigraphy of the studied records was achieved through radiocarbon dating and tephrostratigraphy. Sediment cores with complete Holocene sedimentary sequences were retrieved from Lake Sokoch, an up to six metre deep lake of proglacial origin, situated at the treeline in the Ganalsky Ridge of southern central Kamchatka (53°15,13'N, 157°45.49' E, 495 m a.s.l.). Lacustrine sediment records of mid- to late Holocene age were also recovered from the up to 30 m deep Two-Yurts Lake, which occupies a former proglacial basin at the eastern flank of the Central Kamchatka Mountain Chain, the Sredinny Ridge (56°49.6'N, 160°06.9'E, 275 m a.s.l.). In addition to sediment coring in the open and deep Two-Yurts Lake, sediment records were also recovered from peat sections and small isolated forest lakes to compare

  1. Spatial and temporal trends of mercury and other metals in landlocked char from lakes in the Canadian Arctic archipelago.

    PubMed

    Muir, Derek; Wang, Xiaowa; Bright, Doug; Lockhart, Lyle; Köck, Günter

    2005-12-01

    Spatial and temporal trends of mercury (Hg) and 22 other elements were examined in landlocked Arctic char (Salvelinus alpinus) from six lakes in the Canadian Arctic (Char, Resolute and North Lakes, and Amituk Lake on Cornwallis Island, Sapphire Lake on Devon Island and Boomerang Lake on Somerset Island). The objectives of the study were to compare recent concentrations of Hg and other metals in char with older data from Amituk, Resolute and Char Lakes, in order to examine temporal trends as well as to investigate factors influencing spatial trends in contaminant levels such as lake characteristics, trophic position, size and age of the fish. Geometric mean Hg concentrations in dorsal muscle ranged from 0.147 microg/g wet weight (ww) in Resolute Lake to 1.52 microg/g ww in Amituk Lake for samples collected over the period 1999-2003. Char from Amituk Lake also had significantly higher selenium (Se). Mercury in char from Resolute Lake was strongly correlated with fish length, weight, and age, as well as with thallium, lead and Se. In 5 of 6 lakes, Hg concentrations were correlated with stable nitrogen isotope ratios (delta15N) and larger char were feeding at a higher trophic level presumably due to feeding on smaller char. Weight adjusted mean Hg concentrations in char from Amituk Lake, and unadjusted geometric means in Char Lake and Resolute Lakes, did not show any statistically significant increase from the early 1990s to 2003. However, small sample sizes from 1999-2003 for fish <1000 g limited the power of this comparison in Char and Amituk Lakes. In Resolute Lake char, manganese, strontium and zinc showed consistent decreases from 1997 or 1999 to 2003 while nickel generally increased over the 6 year period. Differences in char trophic level inferred from delta15N values best explained the higher concentrations of Hg in Amituk Lake compared to the other lakes. PMID:16165187

  2. Exploring the long-term balance between net precipitation and net groundwater exchange in Florida seepage lakes

    USGS Publications Warehouse

    Lee, Terrie M.; Sacks, Laura A.; Swancar, Amy

    2014-01-01

    The long-term balance between net precipitation and net groundwater exchange that maintains thousands of seepage lakes in Florida’s karst terrain is explored at a representative lake basin and then regionally for the State’s peninsular lake district. The 15-year water budget of Lake Starr includes El Niño Southern Oscillation (ENSO)-related extremes in rainfall, and provides the longest record of Bowen ratio energy-budget (BREB) lake evaporation and lake-groundwater exchanges in the southeastern United States. Negative net precipitation averaging -25 cm/yr at Lake Starr overturns the previously-held conclusion that lakes in this region receive surplus net precipitation. Net groundwater exchange with the lake was positive on average but too small to balance the net precipitation deficit. Groundwater pumping effects and surface-water withdrawals from the lake widened the imbalance. Satellite-based regional estimates of potential evapotranspiration at five large lakes in peninsular Florida compared well with basin-scale evaporation measurements from seven open-water sites that used BREB methods. The regional average lake evaporation estimated for Lake Starr during 1996-2011 was within 5 percent of its measured average, and regional net precipitation agreed within 10 percent. Regional net precipitation to lakes was negative throughout central peninsular Florida and the net precipitation deficit increased by about 20 cm from north to south. Results indicate that seepage lakes farther south on the peninsula receive greater net groundwater inflow than northern lakes and imply that northern lakes are in comparatively leakier hydrogeologic settings. Findings reveal the peninsular lake district to be more vulnerable than was previously realized to drier climate, surface-water withdrawals from lakes, and groundwater pumping effects.

  3. Exploring the long-term balance between net precipitation and net groundwater exchange in Florida seepage lakes

    NASA Astrophysics Data System (ADS)

    Lee, Terrie M.; Sacks, Laura A.; Swancar, Amy

    2014-11-01

    The long-term balance between net precipitation and net groundwater exchange that maintains thousands of seepage lakes in Florida's karst terrain is explored at a representative lake basin and then regionally for the State's peninsular lake district. The 15-year water budget of Lake Starr includes El Niño Southern Oscillation (ENSO)-related extremes in rainfall, and provides the longest record of Bowen ratio energy-budget (BREB) lake evaporation and lake-groundwater exchanges in the southeastern United States. Negative net precipitation averaging -25 cm/yr at Lake Starr overturns the previously-held conclusion that lakes in this region receive surplus net precipitation. Net groundwater exchange with the lake was positive on average but too small to balance the net precipitation deficit. Groundwater pumping effects and surface-water withdrawals from the lake widened the imbalance. Satellite-based regional estimates of potential evapotranspiration at five large lakes in peninsular Florida compared well with basin-scale evaporation measurements from seven open-water sites that used BREB methods. The regional average lake evaporation estimated for Lake Starr during 1996-2011 was within 5% of its measured average, and regional net precipitation agreed within 10%. Regional net precipitation to lakes was negative throughout central peninsular Florida and the net precipitation deficit increased by about 20 cm from north to south. Results indicate that seepage lakes farther south on the peninsula receive greater net groundwater inflow than northern lakes and imply that northern lakes are in comparatively leakier hydrogeologic settings. Findings reveal the peninsular lake district to be more vulnerable than was previously realized to drier climate, surface-water withdrawals from lakes, and groundwater pumping effects.

  4. GREAT LAKES PLANKTON PROGRAM

    EPA Science Inventory

    Phytoplankton, which have short carbon turnover rates, are sensitive to water quality conditions and grazing by zooplankton, and thus respond rapidly to perturbations of the lake ecosystem. The determination of phytoplankton abundance and species composition is one method to tra...

  5. Is Lake Tahoe Terminal?

    NASA Astrophysics Data System (ADS)

    Coats, R. N.; Reuter, J.; Heyvaert, A.; Lewis, J.; Sahoo, G. B.; Schladow, G.; Thorne, J. H.

    2014-12-01

    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

  6. Lake Superior, Duluth, MN

    NASA Technical Reports Server (NTRS)

    1973-01-01

    This view shows the west end of Lake Superior and Duluth, MN (47.0N, 91.0W). Portions of Minnesota, Michigan and Ontario, Canada are in the scene. The Duluth metropolitan area is at the west end of the lake. The discoloration plume in the water at Duluth is the result of tailings from the iron ore smelters that process the iron ore from the nearby open pit mines seen near the upper left corner of the photo.

  7. Lake Chad, Chad, Africa

    NASA Technical Reports Server (NTRS)

    1988-01-01

    The fluctuating water levels of Lake Chad, (13.0N, 15.0E) at the intersection of the borders of Chad, Niger and Cameroon in the Sahara Desert, is an index of the drought in Africa. The lake level continues to decrease as indicated by the growing number and extent of emerging islands as previously submerged ancient sand dunes become visible. The water impounded between the dunes is probably because of local rainfall rather than a reversal of desertification.

  8. WHISKER LAKE WILDERNESS, WISCONSIN.

    USGS Publications Warehouse

    Schulz, Klaus J.

    1984-01-01

    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.

  9. Dragon Lake, Siberia

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Nicknamed 'Dragon Lake,' this body of water is formed by the Bratskove Reservoir, built along the Angara river in southern Siberia, near the city of Bratsk. This image was acquired in winter, when the lake is frozen. This image was acquired by Landsat 7's Enhanced Thematic Mapper plus (ETM+) sensor on December 19, 1999. This is a natural color composite image made using blue, green, and red wavelengths. Image provided by the USGS EROS Data Center Satellite Systems Branch

  10. Thermal and trophic stability of deeper Maine lakes in granite waterhsheds implacted by acid deposition

    SciTech Connect

    Stauffer, R.E.; Wittchen, B.D. )

    1990-09-01

    Acid deposition can lead to lake and watershed acidification, increases in lake transparency, and reduction in thermal stability and hypolimnetic oxygen deficits. On the basis of lake surveys during August-September 1985, we determined to what extent the deeper (maximum depth z{sub m}{gt}17 m) Maine lakes in acid-sensitive granitic watersheds have registered changes in temperature and oxygen stratification, as compared to 1938-1942, when G.P. Cooper performed the earliest scientific surveys of the state's lakes. After correcting for small but geographically consistent interannual differences in summer hypolimnetic temperatures related to spring turnover, and weather-dependent differences in mixed layer depth, there has been no significant change in thermal stratification in these Maine lakes over approximately 43 years. On the basis of specific historical contrasts in the late summer metalimnetic, hypolimnetic, and bathylimnetic oxygen concentrations there has been no significant change in lake trophic state or transparency.

  11. Salt Lake City, Utah

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Salt Lake City, Utah, will host the 2002 Winter Olympic Games. The city is located on the southeastern shore of the Great Salt Lake and sits to the west of the Wasatch Mountains, which rise more than 3,500 meters (10,000 feet) above sea level. The city was first settled in 1847 by pioneers seeking relief from religious persecution. Today Salt Lake City, the capital of Utah, is home to more than 170,000 residents. This true-color image of Salt Lake City was acquired by the Enhanced Thematic Mapper Plus (ETM+), flying aboard Landsat 7, on May 26, 2000. The southeastern tip of the Great Salt Lake is visible in the upper left of the image. The furrowed green and brown landscape running north-south is a portion of the Wasatch Mountains, some of which are snow-capped (white pixels). The greyish pixels in the center of the image show the developed areas of the city. A number of water reservoirs can be seen east of the mountain range. Salt Lake City International Airport is visible on the northwestern edge of the city. About 20 miles south of the airport is the Bingham Canyon Copper Mine (tan pixels), the world's largest open pit excavation. See also this MODIS image of Utah. Image courtesy NASA Landsat7 Science Team and USGS Eros Data Center

  12. Is Lake Chabot Eutrophic?

    NASA Astrophysics Data System (ADS)

    Pellegrini, K.; Logan, J.; Esterlis, P.; Lew, A.; Nguyen, M.

    2013-12-01

    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

  13. Glacial Lake Outburst Flood on Lemon Creek, Southeastern Alaska

    NASA Astrophysics Data System (ADS)

    Seifert, S. L.; Schwarz, T. C.; Walter, M. T.

    2001-12-01

    A system of small glacial lakes on Lemon Glacier near Juneau, AK was studied to better understand its annual jokulhlaup cycle. Although jokulhlaup behaviors of many supraglacial and glacially-dammed lakes around the world have been studied, some observed relationships among the governing parameters remain mysterious. An associated two-lake system, Lakes Linda and Lynn, which are uniquely small among similar research, provide an opportunity to investigate the applicability of previously developed relationships between discharge magnitude and lake volume to a different spatial scale. The system proved to be interesting in that its behavior does not fit well with established jokulhlaup taxonomy. Additionally, this glacier discharges into Lemon Creek, an important development corridor for Juneau, AK and a productive salmon stream. Understanding how the yearly Lemon Glacier jokulhlaup event impacts this stream is essential to monitoring and meaningfully interpreting water quality data. Historical USGS Lemon Creek streamflow data and icefield observations from the Juneau Icefield Research Program (JIRP) were used to characterize the Lemon Glacier Jokulhlaup and identify changes in system since its discovery in 1962. A detailed field study was carried out from 6/15/01 to 8/2/01 to improve our understanding of the mechanics and thermodynamics of this system. Monitored during this period were lake-levels, lake-temperature profiles, air temperature, surface temperature, relative humidity, precipitation, wind speed/direction, solar radiation, and Lemon Creek streamflow and water-quality. This system has undergone substantial historical changes including the relatively recent development of Lake Lynn, which is now the larger of the two lakes. Continued enlargement of this system is increasing its contribution to peak streamflows in Lemon Creek and thus its impact on stream water quality, especially with respect to sediment loading.

  14. Cyclopoid and harpacticoid copepods of the Laurentian Great Lakes

    USGS Publications Warehouse

    Hudson, Patrick L.; Reid, Janet W.; Lesko, Lynn T.; Selgeby, James H.

    1998-01-01

    Historical collections of cyclopoid and harpacticoid copepod crustaceans in the Great Lakes have mainly been based on samples taken with plankton nets in deeper waters (>5 m). Of the non-calanoid copepod species known from the Great Lakes, 58 or 64 live primarily on or in the sediments and rarely are collected in plankton samples. Because of their small size, they are rarely retained in the coarse sieves used to concentrate samples of benthic invertebrates. Thus, the abundance and distribution of most species of these two groups of copepods have never been adequately documented in the Great Lakes. We examined the stomach contents of small, bottom-feeding fishes such as slimy sculpin which feed on benthic copepods that live in deep, inaccessible rocky areas of the Great Lakes to collect some of the material. We also collected in shallow nearshore habitats, including wetlands. We present an annotated checklist of cyclopoid and harpacticoid copepods based on published records and our recent collections in the Great Lakes. We have added 14 species of cyclopoid copepods to the Great Lakes record, increasing the total to 30. Because we probably have accounted for most of the cyclopoid species, we provide a key to the identification of this group. We have added 19 species of harpacticoid copepods to the 15 previously known to the Great Lakes, and suspect that additional species remain to be discovered. In individual lakes, there were approximately as many species of cyclopoids as harpacticoids; the total number of species per lake ranged from 35 to 57. The most speciose genera were Bryocamptus (7), Canthocamptus (5), and Moraria (5) in the Harpacticoida, and Diacyclops (6) and Acanthocyclops (5) in the Cyclopoida. The origin of introduced species, our ability to classify copepod habitat, and the ecological significance of copepods are discussed.

  15. Hydrogeologic comparison of an acidic-lake basin with a neutral-lake basin in the West-Central Adirondack Mountains, New York

    USGS Publications Warehouse

    Peters, N.E.; Murdoch, Peter S.

    1985-01-01

    Two small headwater lake basins that receive similar amounts of acidic atmospheric deposition have significantly different lake outflow pH values; pH at Panther Lake (neutral) ranges from about 4.7 to 7; that at Woods Lake (acidic) ranges from about 4.3 to 5. A hydrologic analysis, which included monthly water budgets, hydrograph analysis, examination of flow duration and runoff recession curves, calculation of ground-water storage, and an analysis of lateral flow capacity of the soil, indicates that differences in lakewater pH can be attributed to differences in the ground-water contribution to the lakes. A larger percentage of the water discharged from the neutral lake is derived from ground water than that from the acidic lake. Ground water has a higher pH resulting from a sufficiently long residence time for neutralizing chemical reactions to occur with the till. The difference in ground-water contribution is attributed to a more extensive distribution of thick till (<3m) in the neutral-lake basin than in the acidic-lake basin; average thickness of till in the neutral-lake basin is 24m whereas that in the other is 2.3m. During the snowmelt period, as much as three months of accumulated precipitation may be released within two weeks causing the lateral flow capacity of the deeper mineral soil to be exceeded in the neutral-lake basin. This excess water moves over and through the shallow acidic soil horizons and causes the lakewater pH to decrease during snowmelt.Two small headwater lake basins that receive similar amounts of acidic atmospheric deposition have significantly different lake outflow pH values; pH at Panther Lake (neutral) ranges from about 4. 7 to 7; that at Woods Lake (acidic) ranges from about 4. 3 to 5. A hydrologic analysis, which included monthly water budgets, hydrograph analysis, examination of flow duration and runoff recession curves, calculation of ground-water storage, and an analysis of lateral flow capacity of the soil, indicates that

  16. Watershed Management and Mercury Biogeochemical Cycling in Lake Zapotlan, Mexico

    NASA Astrophysics Data System (ADS)

    Malczyk, E. A.; Branfireun, B. A.

    2009-05-01

    Lake Zapotlan is an endorheic subtropical eutrophic lake located in Jalisco State, Mexico. The lake supports a small but important local fishery for carp (Cyprinus sp.) and tilapia (Oreochromis sp.) and is an internationally recognized RAMSAR site. Very little research exists in these regions regarding mercury biogeochemical cycling. The lake receives considerable untreated municipal wastewater discharge that is elevated in inorganic total mercury (250-800 ng Hg/L) and organic methylmercury (3-10 ng CH3Hg+/L). The lake is also located on an active fault zone near an active volcano which may cause natural mercury enrichment. To assess a mercury risk to the commercial fishery we investigated the distribution of total inorganic mercury and organic methylmercury in waters, sediments, and fish tissues of the lake, surrounding wetlands, and incoming waters. Although there were high concentrations of inorganic mercury entering the lake in wastewater and seasonal tributary stream flow inputs, average concentrations in lake surface waters (3 ng Hg/L) and sediments (50 ng Hg/gdw) were relatively low. Average concentrations of total inorganic mercury were an order of magnitude higher in water (70 ng Hg/L) and sediment (245 ng Hg/gdw) in wetlands receiving the wastewater discharges. Mercury loading to the main body of the lake is likely reduced by these wetland buffer zones which allow mercury bound to particulate matter to settle out. A similar pattern was seen with respect to methylmercury concentrations. Average concentrations of methylmercury in lake surface water (below detect) and sediment (0.1 ng/gdw) were lower than in impounded wetlands (1 ng CH3Hg+/L, 0.7 ng CH3Hg+/gdw). Mercury concentrations in tilapia (3.5 ng/g) and carp (8 ng/g) from the commercial catch were found to be low in mercury; likely due to a combination of physiological, biogeochemical, and ecological factors.

  17. Lake Buchannan, Great Dividing Range, Queensland, Australia

    NASA Technical Reports Server (NTRS)

    1991-01-01

    Lake Buchannan, a small but blue and prominent in the center of the view, lies in the Great Dividing of Queensland, Australia (22.0S, 146.0E). The mountain range in this case is a low plateau of no more than 2,000 to 3,000 ft altitude. The interior is dry, mostly in pasture but the coastal zone in contrast, is wet tropical country where bananas and sugarcane are grown.

  18. Contaminants in American alligator eggs from Lake Apopka, Lake Griffin, and Lake Okeechobee, Florida

    USGS Publications Warehouse

    Heinz, G.H.; Percival, H.F.; Jennings, Michael L.

    1991-01-01

    Residues of organochlorine pesticides, polychlorinated biphenyls (PCBs), and 16 elements were measured in American alligator (Alligator mississippiensis) eggs collected in 1984 from Lakes Apopka, Griffin, and Okeechobee in central and south Florida. Organochlorine pesticides were highest in eggs from Lake Apopka. None of the elements appeared to be present at harmful concentrations in eggs from any of the lakes. A larger sample of eggs was collected in 1985, but only from Lakes Griffin, a lake where eggs were relatively clean, and Apopka, where eggs were most contaminated. In 1985, hatching success of artificially incubated eggs was lower for Lake Apopka, and several organochlorine pesticides were higher than in eggs from Lake Griffin. However, within Lake Apopka, higher levels of pesticides in chemically analyzed eggs were not associated with reduced hatching success of the remaining eggs in the clutch. Therefore, it did not appear that any of the pesticides we measured were responsible for the reduced hatching of Lake Apopka eggs.

  19. Big lake records preserved in a little lake's sediment: An example from Silver Lake, Michigan, USA

    USGS Publications Warehouse

    Fisher, T.G.; Loope, W.L.; Pierce, W.; Jol, H.M.

    2007-01-01

    We reconstruct postglacial lake-level history within the Lake Michigan basin using soil stratigraphy, ground-penetrating radar (GPR), sedimentology and 14C data from the Silver Lake basin, which lies adjacent to Lake Michigan. Stratigraphy in nine vibracores recovered from the floor of Silver Lake appears to reflect fluctuation of water levels in the Lake Michigan basin. Aeolian activity within the study area from 3,000 years (cal yr. B.P.) to the present was inferred from analysis of buried soils, an aerial photograph sequence, and GPR. Sediments in and around Silver Lake appear to contain a paleoenvironmental record that spans the entire post-glacial history of the Lake Michigan basin. We suggest that (1) a pre-Nipissing rather than a Nipissing barrier separated Silver Lake basin from the Lake Michigan basin, (2) that the Nipissing transgression elevated the water table in the Silver Lake basin about 6,500 cal yr. B.P., resulting in reestablishment of a lake within the basin, and (3) that recent dune migration into Silver Lake is associated with levels of Lake Michigan.

  20. Evidence of Lake Trout reproduction at Lake Michigan's mid-lake reef complex

    USGS Publications Warehouse

    Janssen, J.; Jude, D.J.; Edsall, T.A.; Paddock, R.W.; Wattrus, N.; Toneys, M.; McKee, P.

    2006-01-01

    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.

  1. Monitoring drying up of Urmia lake with satellite altimetry

    NASA Astrophysics Data System (ADS)

    Roohi, Shirzad; Sneeuw, Nico

    2013-04-01

    Urmia lake is a UNESCO protected area with more than a hundred small rocky islands. It is home to several species of birds and animals. Located in northwestern Iran, it is the largest lake in the Middle East and the third largest salty water lake on earth. It has a surface area of approximately 5200 km², and an average depth of 16 m. Unfortunately during the recently years Urmia lake has been shrinking. If the drought process continues at the current rate it would be disappear in the near future. The main factors that speeds up the drought rate of the lake, are dam construction on the main rivers which feeds the lake, evaporation and lack of precipitation during recent years as well as irrigation. The construction of a causeway in the middle of the lake also affects the natural ecosystem of the lake. The case of Urmia lake and similar cases in other parts of the word emphasize the role of new technology such as satellite altimetry in better management of water resource and monitoring such critical situations. In this research we show the current situation and recent past of the lake from processing 10 years of Envisat satellite radar altimetry data. For internal validation of the result, water level time series were built from ascending and descending tracks separately and for external validation in-situ gauge measurements were used. Internal and external comparisons indicates the result are consistent, i.e there is no bias and systematic error in Envisat data. The RMSE between ascending and descending tracks is several centimeters and between satellite and gauge data is 1m. Water level time series analysis shows that there is a declining rate of 0.3 m/year in the water level but after 2005 it seems to have accelerated. This rate increases the salinity of lake and expands receding shoreline rapidly so the lake bed will reveal fast because the lake is shallow especially in the south part. Following this research we are investigating to find the best re-tracker in

  2. Winter Lake Breezes near the Great Salt Lake

    NASA Astrophysics Data System (ADS)

    Crosman, Erik T.; Horel, John D.

    2016-05-01

    Case studies of lake breezes during wintertime cold air pools in Utah's Salt Lake Valley are examined. While summer breezes originating from the Great Salt Lake are typically deeper, of longer duration, and have higher wind speeds than winter breezes, the rate of inland penetration and cross-frontal temperature differences can be higher during the winter. The characteristics of winter breezes and the forcing mechanisms controlling them (e.g., snow cover, background flow, vertical stability profile, clouds, lake temperature, lake sheltering, and drainage pooling) are more complex and variable than those evident in summer. During the afternoon in the Salt Lake Valley, these lake breezes can lead to elevated pollution levels due to the transport of fine particle pollutants from over the Great Salt Lake, decreased vertical mixing depth, and increased vertical stability.

  3. Crater Lake revealed

    USGS Publications Warehouse

    Ramsey, David W.; Dartnell, Peter; Bacon, Charles R.; Robinson, Joel E.; Gardner, James V.

    2003-01-01

    Around 500,000 people each year visit Crater Lake National Park in the Cascade Range of southern Oregon. Volcanic peaks, evergreen forests, and Crater Lake’s incredibly blue water are the park’s main attractions. Crater Lake partially fills the caldera that formed approximately 7,700 years ago by the eruption and subsequent collapse of a 12,000-foot volcano called Mount Mazama. The caldera-forming or climactic eruption of Mount Mazama drastically changed the landscape all around the volcano and spread a blanket of volcanic ash at least as far away as southern Canada. Prior to the climactic event, Mount Mazama had a 400,000 year history of cone building activity like that of other Cascade volcanoes such as Mount Shasta. Since the climactic eruption, there have been several less violent, smaller postcaldera eruptions within the caldera itself. However, relatively little was known about the specifics of these eruptions because their products were obscured beneath Crater Lake’s surface. As the Crater Lake region is still potentially volcanically active, understanding past eruptive events is important to understanding future eruptions, which could threaten facilities and people at Crater Lake National Park and the major transportation corridor east of the Cascades. Recently, the lake bottom was mapped with a high-resolution multibeam echo sounder. The new bathymetric survey provides a 2m/pixel view of the lake floor from its deepest basins virtually to the shoreline. Using Geographic Information Systems (GIS) applications, the bathymetry data can be visualized and analyzed to shed light on the geology, geomorphology, and geologic history of Crater Lake.

  4. The Wandering Lake

    NASA Technical Reports Server (NTRS)

    2002-01-01

    In the area at the very far eastern corner of China's Taklimakan Desert, Lop Nor Lake was located up until some years ago. Lop Nor, also called the 'the heart of the heart' of Asia, was the place where the waters of the largest inner basin (i.e., not flowing into the sea) of the world-including the Tarim and Kum-daria Rivers-were collected. Depending on the balance between rainfall water yield and evaporation, both position and size of the lake were strongly variable, thus giving rise to the legend of the Wandering Lake. 'Lop City' was the place where Marco Polo took his last rest before facing the one-year long crossing of the Gobi Desert. Starting from the end of the 19th century, several explorers tried to find the legendary place. One such explorer was Sven Hedin, who was commissioned by the Governor of Nanjing to lead an expedition to find the lake. In 1937, the Swedish explorer published his book entitled The Wandering Lake. Comparing this very precise map from Sven Hedin's book with the above Moderate-resolution Imaging Spectroradiometer (MODIS) false-color image (acquired on October 28, 2001), one can find a faint sign on the soil where the Lop Nor was located. This image, derived using a combination of MODIS' near-infrared and red channels (vegetation in red), shows where the Tarim River waters currently end their flow. The Wandering Lake does not exist anymore. The combination of climate change and human exploitation of water resources for agriculture caused the disappearance of the lake. This image was processed by Telespazio, Earth Observation division, new products development facility in Rome, Italy. The MODIS sensor flies aboard NASA's Terra spacecraft, launched in December 1999. Caption and image courtesy Luca Pietranera, Telespazio, Rome, Italy, based on data from the MODIS Science Team

  5. Lake Sarez, Tajikistan

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Lake Sarez (top), deep in the Pamir mountains of Tajikistan, was created 90 years ago when a strong earthquake triggered a massive landslide that, in turn, became a huge dam along the Murghob River, now called the Usoi Dam. The resulting lake is perched above surrounding drainages at an elevation greater than 3000m, and is part of the watershed that drains the towering Akademi Nauk Range (see the regional image, lower). The lake is 61 km long and as deep as 500 m, and holds an estimated 17 cubic km of water. The area experiences considerable seismic activity, and scientists fear that part of the right bank may slump into the lake, creating a huge wave that will top over and possibly breach the natural dam. Such a wave would create a catastrophic flood downstream along the Bartang, Panj and Amu Darya Rivers, perhaps reaching all the way to the Aral Sea. Currently, central Asian governments, as well as the World Bank and the UN are monitoring the dam closely, and have proposed gradually lowering the lake level as a preventive measure. More information about the lake is available at the following web sites: Lake Sarez Study group, UN Report, Reliefweb Digital photograph numbers ISS002-E-7771 and ISS002-E-7479 were taken in the spring of 2001 from Space Station Alpha and are provided by the Earth Sciences and Image Analysis Laboratory at Johnson Space Center. Additional images taken by astronauts and cosmonauts can be viewed at the NASA-JSC Gateway to Astronaut Photography of Earth.

  6. Examining indirect effects of lake trout recovery

    EPA Science Inventory

    With the recovery of lake trout populations in Lake Superior, there are indications of decreased forage fish abundance and density-dependence in lake trout. In Lake Superior, lean lake trout historically occupied depths < 60 m, and siscowet lake trout occupied depths > 60 m...

  7. Chronology of expansion and contraction of four great Basin lake systems during the past 35,000 years

    USGS Publications Warehouse

    Benson, L.V.; Currey, D.R.; Dorn, R.I.; Lajoie, K.R.; Oviatt, Charles G.; Robinson, S.W.; Smith, G.I.; Stine, S.

    1990-01-01

    During the past 35,000 years, Lake Bonneville, Lake Russell, and Lake Searles underwent a major period of lake-level change. The lakes were at moderate levels or dry at the beginning of the period and seem to have achieved highstands between about 15,000 and 13,500 yr B.P. The rise of Lake Lahontan was gradual but not continuous, in part because of topographic constraints (intrabasin spill). Lake Lahontan also had an oscillation in lake level at 15,500 yr B.P. Radiocarbon-age estimations for materials that were deposited in the lake basins indicate that Lake Bonneville rose more or less gradually from 32,000 yr B.P., and had major oscillations in level between 23,000 and 21,000 yr B.P. and between 15,250 and 14,500 yr B.P. Lake Russell and Lake Searles had several major oscillations in lake level between 35,000 and 14,000 yr B.P. The timing and exact magnitude of the oscillations are difficult to decipher but both lakes may have achieved multiple highstand states. All four lakes may have had nearly synchronous recessions between about 14,000 and 13,500 yr B.P. After the recessions, the lakes seem to have temporarily stabilized or experienced a minor increase in size between about 11,500 and 10,000 yr B.P. These data provide circumstantial evidence that the Younger Dryas Event affected climate on at least a hemispheric scale. During the Holocene, the four lakes remained at low levels, and small oscillations in lake level occurred. An important aspect of the lake-level data is the accompanying expansion of lake-surface area at the time of the last highstand. Lake Bonneville and Lake Lahontan had surface areas about 10 times larger than their mean-historical reconstructed areas whereas Lake Russell and Lake Searles had surface areas about 5 times larger than their mean-historical reconstructed areas. Differences in the records of effective wetness may have been due to the locations of the basins relative to the position of the jetstream, or they may have resulted from

  8. Stratigraphic analysis of lake level fluctuations in Lake Ohrid: an integration of high resolution hydro-acoustic data and sediment cores

    NASA Astrophysics Data System (ADS)

    Lindhorst, K.; Vogel, H.; Krastel, S.; Wagner, B.; Hilgers, A.; Zander, A.; Schwenk, T.; Wessels, M.; Daut, G.

    2010-05-01

    Ancient Lake Ohrid is a steep sided, oligotrophic, karst lake of likely Pliocene age and often referred to as a hotspot of endemic biodiversity. This study aims on tracing significant lake level fluctuations at Lake Ohrid using high-resolution acoustic data in combination with lithological, geochemical, and chronological information from two sediment cores recovered from sub-aquatic terrace levels at ca. 32 and 55 m. According to our data, significant lake level fluctuations with prominent lowstands of ca. 60 and 35 m below the present water level occurred during MIS 6 and MIS 5, respectively. The effect of these lowstands on biodiversity in most coastal parts of the lake is negligible, due to only small changes in lake surface area, coastline, and habitat. In contrast, biodiversity in shallower areas was more severely affected due to disconnection of today sub-lacustrine springs from the main water body. Multichannel seismic data from deeper parts of the lake clearly imaged several clinoform structures stacked on top of each other. These stacked clinoforms indicate significantly lower lake levels prior to MIS 6 and a stepwise rise of water level with intermittent stillstands since its existence as water filled body, which might have caused enhanced expansion of endemic species within Lake Ohrid.

  9. Stratigraphic analysis of lake level fluctuations in Lake Ohrid: an integration of high resolution hydro-acoustic data and sediment cores

    NASA Astrophysics Data System (ADS)

    Lindhorst, K.; Vogel, H.; Krastel, S.; Wagner, B.; Hilgers, A.; Zander, A.; Schwenk, T.; Wessels, M.; Daut, G.

    2010-11-01

    Ancient Lake Ohrid is a steep-sided, oligotrophic, karst lake that was tectonically formed most likely within the Pliocene and often referred to as a hotspot of endemic biodiversity. This study aims on tracing significant lake level fluctuations at Lake Ohrid using high-resolution acoustic data in combination with lithological, geochemical, and chronological information from two sediment cores recovered from sub-aquatic terrace levels at ca. 32 and 60 m water depth. According to our data, significant lake level fluctuations with prominent lowstands of ca. 60 and 35 m below the present water level occurred during Marine Isotope Stage (MIS) 6 and MIS 5, respectively. The effect of these lowstands on biodiversity in most coastal parts of the lake is negligible, due to only small changes in lake surface area, coastline, and habitat. In contrast, biodiversity in shallower areas was more severely affected due to disconnection of today sub-lacustrine springs from the main water body. Multichannel seismic data from deeper parts of the lake clearly image several clinoform structures stacked on top of each other. These stacked clinoforms indicate significantly lower lake levels prior to MIS 6 and a stepwise rise of water level with intermittent stillstands since its existence as water-filled body, which might have caused enhanced expansion of endemic species within Lake Ohrid.

  10. Facies distributions within contrasting structural components of a rift lake: Lake Tanganyika, Africa

    SciTech Connect

    Soreghan, M.J.; Cohen, A.S. )

    1991-03-01

    Lake Tanganyika is the most widely cited modern analog for interpreting ancient rift lakes; thus, understanding controls on its facies distribution is critical for refining stratigraphic models for rifts. Four recurrent margin types occur along the alternating half-graben structure of the lake: rift axes, platforms, escarpments, and accommodation zones. Data from study sites in the northern part of the lake suggest that predictable facies differences exist between these structural margin types. The rift axis site comprises a low-gradient, clastic (wave/current)-dominated deltaic system, with strong facies asymmetry and minor carbonate accumulations on raised benches. The platform margin site comprises a series of structurally controlled benches over which long, continuous facies tracts occur. Carbonate sands, muds, and shell gravel dominate; clastics are limited to moderate-sized silty deltas and long, narrow shoreface sands. The escarpment margin site is a steep-gradient system along which small ({lt}1 km{sup 2}) fan deltas alternate with cemented talus. The accommodation zone margin sites are also dominated by rugged structural relief, generally small fan deltas, and semicontinuous shoreface sand belts ({gt}5 km) onshore and poorly sorted silts offshore. TOC from fine-grained samples reflects the contrast in margin types. TOC values for the platform and rift axis range from 0.4 - 2.1 wt. % (avg. 1.3%), whereas accommodation zone and escarpment margin values range from 0.5-5.5% (avg. 3.0%). Acid insoluble sulfur shows a similar trend. Although all data are significantly correlated with depth, the relative area of the lake margin above and below the oxicline is directly controlled by the structural style of the lake margin.

  11. Sedimentary Response of AN Ephemeral Lake during Deglacial and Holocene Climate Evolution, Swan Lake, Southeast Idaho.

    NASA Astrophysics Data System (ADS)

    Rosario, J. J.; Miller, D. M.; Wahl, D.; Anderson, L.; Tripati, A.; Presnetsova, L.; Oviatt, C. G.; McGeehin, J. P.; Bright, J. E.

    2014-12-01

    Perennial water systems are important ecological resources in the arid western US and provide many ecosystem services. Lakes can record fluctuations in climate (such as temperature and effective moisture) and can offer insight into regional variations in climate patterns. We studied a 7.65-m core from Swan Lake, which is a small lake and wetland complex that seasonally overflows, to examine small scale climate changes in its continuous sedimentary record. Our core is similar to that studied by Bright (1966), which exhibits two primary sedimentary facies, mud and peat, with a time span of 13.5 cal ka. The methodology includes radiocarbon dating, particle size analyses, sediment mineralogy, stable isotopes and clumped isotopes on calcium carbonate. Mud in the lower half of the core is primarily composed of clay and silt-size quartz-feldspar, but it transitions to calcium carbonate mud. Clays change from 660 to 585 cm and 350 to 220 cm in the core with an increase in kaolinite and illite upward. Ostracods in the carbonate muds are fairly uniform, indicating a mixture of wetland and lake environments from the last 5.8 ka. Similarly, summer temperatures obtained using Δ47 measurements show fluctuations in the range of 18.1 to 23.4 oC with carbonate muds generally corresponding to lower temperatures and peats to higher temperatures. We interpret muds as open water, shallow lake conditions and peats as wetlands across the floor of the ephemeral lake. If our interpretations are correct, the time from onset of the Younger Dryas to the end of the early Holocene was effectively dry, with low groundwater discharge. Similar events occurred from 4.7 to 1.0 ka and briefly at ~400 cal yr BP. Warmer climate may lead to effective moisture increase in this part of the eastern Great Basin.

  12. [Pollution Status and Migration of Mercury in the Sediments of Nansi Lake in Shandong Province].

    PubMed

    Cao, Fei-fei; Yang, Li-yuan; Pang, Xu-gui; Wang, Bing-hua; Wang, Yun-qian

    2015-05-01

    The content of mercury and fractions were determined, in order to discuss the pollution situation and migration ability of mercury in inflow rivers and surface sediments of Nansi Lake. The average content of mercury in the sediments of the Nansi Lake was 0.046 mg · kg(-1), significantly higher than the environmental background values, which showed that Nansi Lake suffered from mercury pollution. Mercury in sediments existed mainly in the residual fraction, accounting for 65. 15%. The proportion of non-residual fractions was relatively small, in the order of organic bound fraction (30.61%), extractable fraction (2.93%), and Fe/Mn oxide (1.31%). The spatial change of non-residual fractions was that Weishan Lake and Nanyang Lake had higher non-residual mercury content than Zhaoyang Lake and Dushan Lake, and the non-residual mercury had a certain potential ecological harm on Weishan Lake and Nanyang Lake. From the horizontal view, the mercury content in the surface sediments of Nansi Lake had visible difference and the pollution degree was different among sub-lakes, so horizontal migration of mercury was obvious. Vertically, the mercury content showed a trend of increasing from the bottom to the top in core sediments, which might be associated with social and economic conditions in different periods. PMID:26314107

  13. View of Lake Sabrina Dam and dry Lake Sabrina Basin ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    View of Lake Sabrina Dam and dry Lake Sabrina Basin with the upstream side of the outlet structure visible at photo center, view to north-northwest - Bishop Creek Hydroelectric System, Plant 2, Lake Sabrina Dam, Bishop Creek, Bishop, Inyo County, CA

  14. 42. Peaks of Otter, Abbott Lake. View across lake to ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    42. Peaks of Otter, Abbott Lake. View across lake to peaks of Outter Lodge, completed in 1964. Construction of the lake got underway in 1964. Looking east-northeast. - Blue Ridge Parkway, Between Shenandoah National Park & Great Smoky Mountains, Asheville, Buncombe County, NC

  15. Lake Michigan lake trout PCB model forecast post audit

    EPA Science Inventory

    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...

  16. Mono Lake Excursion Reviewed

    NASA Astrophysics Data System (ADS)

    Liddicoat, J. C.; Coe, R. S.

    2007-05-01

    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

  17. Polar lakes may act as ecological islands to aquatic protists

    PubMed Central

    RENGEFORS, K; LOGARES, R; LAYBOURN-PARRY, J

    2012-01-01

    A fundamental question in ecology is whether microorganisms follow the same patterns as multicellular organisms when it comes to population structure and levels of genetic diversity. Enormous population sizes, predominately asexual reproduction and presumably high dispersal because of small body size could have profound implications on their genetic diversity and population structure. Here, we have analysed the population genetic structure in a lake-dwelling microbial eukaryote (dinoflagellate) and tested the hypothesis that there is population genetic differentiation among nearby lake subpopulations. This dinoflagellate occurs in the marine-derived saline lakes of the Vestfold Hills, Antarctica, which are ice-covered most of the year. Clonal strains were isolated from four different lakes and were genotyped using amplified fragment length polymorphism (AFLP). Our results show high genetic differentiation among lake populations despite their close geographic proximity (<9 km). Moreover, genotype diversity was high within populations. Gene flow in this system is clearly limited, either because of physical or biological barriers. Our results discard the null hypothesis that there is free gene flow among protist lake populations. Instead, limnetic protist populations may differentiate genetically, and lakes act as ecological islands even on the microbial scale. PMID:22564188

  18. Microplastic pollution in lakes and lake shoreline sediments - A case study on Lake Bolsena and Lake Chiusi (central Italy).

    PubMed

    Fischer, Elke Kerstin; Paglialonga, Lisa; Czech, Elisa; Tamminga, Matthias

    2016-06-01

    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. PMID:27104923

  19. Lake Enriquillo Water Level History and Implications for future flooding in the Southwestern Dominican Republic

    NASA Astrophysics Data System (ADS)

    Wright, V. D.; Hornbach, M. J.; McHugh, C. M.; Asilis, Y.; Montes, M.

    2013-12-01

    Lake Enriquillo is currently located -41m below sea-level, and is the largest lake (~350 km2) in the Caribbean. Lake levels during the past eight years have risen to anomalous highs (from -51m BSL to -41m BSL), flooding villages and displacing their inhabitants. Both the cause of lake level rise and the anticipated future change in lake level remain unclear. Seismic images revealing erosional and depositional sedimentary boundaries in the lake, however, provide insight into historic lake level trends. Here, we integrate seismic images with sediment core samples, and historical photographs to constrain lake level history with time. We used ASTER global digital elevation models combined with single beam data to determine the lake's bathymetry, drainage and surrounding geomorphology. Additionally, we used NOAA and local weather station data to assess the potential role that weather and climate patterns play in lake levels. Although yearly weather conditions play a major role in lake levels, analysis of regional seismic data indicates that tectonics may also play an important role in longer term (century-scale) lake levels. The lake's areal extent and lake level elevation depend not only on the water supply, but also the lake's bathymetry and regional topography that is defined by the Enriquillo-Plantain Garden Fault--a strike-slip fault system that extends throughout the lake. The shallow bathymetry of much of the lake (~ 20%) implies that relatively small changes in the rain pattern cause significant (10 m) changes to lake depth. Over the past thirty years, variations in the lake's areal extent (between 160 km2 to 350km2) and elevation (between -52m BSL to -41m BSL) can be attributed to changes in weather patterns. Preliminary analysis of both core and seismic data confirm that the lake water levels generally mimic wet and dry periods in the region, consistent with recent observations, however, the longer term maximum and minimum extent of Lake Enriquillo water

  20. Development of a Fish Based Lake Typology for Natural Austrian Lakes >50 ha Based on the Reconstructed Historical Fish Communities

    NASA Astrophysics Data System (ADS)

    Gassner, Hubert; Wanzenböck, Josef; Zick, Daniela; Tischler, Gerhard; Pamminger-Lahnsteiner, Barbara

    2005-08-01

    Based on the reconstructed native fish communities all natural Austrian lakes >50 ha (n = 43) were classified into four groups using cluster analysis methods. Sentinel species (i.e. species with highest discriminating value for lake types and characteristic for a specific lake group) and type specific fish species (accompanying species with additional value for characterising lake groups) were defined by a newly developed index and by similarity analysis. The first group included 16 lakes of high altitude, small surface area and low fish species number with arctic char as a sentinel species. The second group (n = 10) was characterized by intermediate altitude, large surface area and high maximum water depth with the minnow as sentinel species. The third group contained 14 lakes with low maximum water depths and a long retention time. For this group the bleak was found as a sentinel species. The lakes of the eastern part of Austria represented the last group (n = 3) and were characterized by low altitude and very shallow water depth with pike-perch as a sentinel species.

  1. Michigan: The Great Lakes State

    ERIC Educational Resources Information Center

    McKay, Sandra Lee; La Luzerne-Oi, Sally

    2009-01-01

    Although Michigan is often called the "Wolverine State," its more common nickname is the "Great Lakes State." This name comes from the fact that Michigan is the only state in the United States that borders four of the five Great Lakes. Also referred to as the "Water Wonderland," Michigan has 11,000 additional lakes, 36,000 miles of streams, and…

  2. Viruses in Antarctic lakes

    NASA Technical Reports Server (NTRS)

    Kepner, R. L. Jr; Wharton, R. A. Jr; Suttle, C. A.; Wharton RA, J. r. (Principal Investigator)

    1998-01-01

    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.

  3. Analysis of the hydrological response of a tropical terminal lake, Lake Abiyata (Main Ethiopian Rift Valley) to changes in climate and human activities

    NASA Astrophysics Data System (ADS)

    Legesse, Dagnachew; Vallet-Coulomb, Christine; Gasse, Françoise

    2004-02-01

    Integrated dynamic water and chloride balance models with a catchment-scale hydrological model (PRMS) are used to investigate the response of a terminal tropical lake, Lake Abiyata, to climate variability and water use practices in its catchment. The hydrological model is used to investigate the response of the catchment to different climate and land-use change scenarios that are incorporated into the lake model. Lake depth-area-volume relationships were established from lake bathymetries. Missing data in the time series were filled using statistical regression techniques. Based on mean monthly data, the lake water balance model produced a good agreement between the simulated and observed levels of Lake Abiyata for the period 1968-83. From 1984 onwards the simulated lake level is overestimated with respect to the observed one, while the chloride concentration is largely underestimated. This discrepancy is attributed to human use of water from the influent rivers or directly from the lake. The simulated lake level and chloride concentration are in better agreement with observed values (r2 = 0.96) when human water use for irrigation and salt exploitation are included in the model. A comparison of the simulation with and without human consumption indicates that climate variability controls the interannual fluctuations and that the human water use affects the equilibrium of the system by strongly reducing the lake level. Sensitivity analysis based on a mean climatic year showed that, after prolonged mean climatic conditions, Lake Abiyata reacts more rapidly to an abrupt shift to wetter conditions than to dry conditions. This study shows the significant sensitivity of the level and salinity of the terminal Lake Abiyata to small changes in climate or land use, making it a very good recorder of environmental changes that may occur in the catchment at different time scales.

  4. Preliminary Study of the Effect of the Proposed Long Lake Valley Project Operation on the Transport of Larval Suckers in Upper Klamath Lake, Oregon

    USGS Publications Warehouse

    Wood, Tamara M.

    2009-01-01

    A hydrodynamic model of Upper Klamath and Agency Lakes, Oregon, was used to explore the effects of the operation of proposed offstream storage at Long Lake Valley on transport of larval suckers through the Upper Klamath and Agency Lakes system during May and June, when larval fish leave spawning sites in the Williamson River and springs along the eastern shoreline and become entrained in lake currents. A range in hydrologic conditions was considered, including historically high and low outflows and inflows, lake elevations, and the operation of pumps between Upper Klamath Lake and storage in Long Lake Valley. Two wind-forcing scenarios were considered: one dominated by moderate prevailing winds and another dominated by a strong reversal of winds from the prevailing direction. On the basis of 24 model simulations that used all combinations of hydrology and wind forcing, as well as With Project and No Action scenarios, it was determined that the biggest effect of project operations on larval transport was the result of alterations in project management of the elevation in Upper Klamath Lake and the outflow at the Link River and A Canal, rather than the result of pumping operations. This was because, during the spring time period of interest, the amount of water pumped between Upper Klamath Lake and Long Lake Valley was generally small. The dominant effect was that an increase in lake elevation would result in more larvae in the Williamson River delta and in Agency Lake, an effect that was enhanced under conditions of wind reversal. A decrease in lake elevation accompanied by an increase in the outflow at the Link River had the opposite effect on larval concentration and residence time.

  5. Modeling lava lake heat loss, rheology, and convection

    NASA Astrophysics Data System (ADS)

    Harris, Andrew J. L.

    2008-04-01

    Measurements at Erta Ale's lava lake and theoretical equations for lake rheology, density driven convection and thermally-driven plume ascent allow the constraint of lake dynamics. Cooling and crystallization expected from surface heat losses imply a viscosity increase from 150 Pa s to 300-1800 Pa s for cooled surface layers. Convection is expected to proceed vigorously under low viscosity conditions driving rapid (0.1-0.4 m s-1) surface motions and sluggishly under moderate-to-high viscosity conditions to drive slower motions (<0.08 m s-1). Convection is likely driven by small (~6 kg m-3) density differences, where surface cooling can influence lake rheology and explain variable rates of surface convective motion.

  6. Managing A Lake/Aquifer System-Science, Policy, and the Public Interest

    NASA Astrophysics Data System (ADS)

    Shaver, R. B.

    2009-12-01

    Lake Isabel is a small (312 ha) natural lake located in central North Dakota in the glaciated Missouri Coteau. The average lake depth is about 1.8 m with a maximum depth of about 3.6 to 4.6 m. The lake overlies the Central Dakota aquifer complex which is comprised of three sand and gravel aquifer units that are either directly or indirectly (through leakage) hydraulically connected to the lake. The aquifer is a major water source for center pivot irrigation. During the 2001-2008 drought, lower lake levels reduced lake recreation, including leaving many boat docks unusable. Lake homeowners attribute lake level decline to irrigation pumping and believe that irrigation should be curtailed. There is no water right associated with Lake Isabel because there are no constructed works associated with the lake. Therefore, under North Dakota statute the lake cannot be protected as a prior (senior) appropriator. The lake does have standing under the public interest as defined by North Dakota statute. Evaluation of the public interest involves the integration of both science and policy. Is it in the best interest of the people of the state to prohibit ground water withdrawals for irrigation to protect the lake? This is a policy decision, not a scientific decision. The basis of the policy decision should include an economic analysis of the irrigated crops, fish, wildlife, recreation, and lake property. In addition, priority of use and lake level history should be considered. The issue can likely be resolved without scientific controversy arising from hydrologic system uncertainty. If the decision is to protect the lake at some level, the issue becomes “scientized” and the following questions need to be answered: 1) Does irrigation pumping effect changes in lake levels? 2) Is our level of scientific understanding sufficient to determine what volume of irrigation pumping will cause what amount of lake level change? 3) Given aquifer lag time response to changes in pumping and

  7. Thermal, chemical, and optical properties of Crater Lake, Oregon

    USGS Publications Warehouse

    Larson, G.L.; Hoffman, R.L.; McIntire, D.C.; Buktenica, M.W.; Girdner, S.F.

    2007-01-01

    Crater Lake covers the floor of the Mount Mazama caldera that formed 7700 years ago. The lake has a surface area of 53 km2 and a maximum depth of 594 m. There is no outlet stream and surface inflow is limited to small streams and springs. Owing to its great volume and heat, the lake is not covered by snow and ice in winter unlike other lakes in the Cascade Range. The lake is isothermal in winter except for a slight increase in temperature in the deep lake from hyperadiabatic processes and inflow of hydrothermal fluids. During winter and spring the water column mixes to a depth of about 200-250 m from wind energy and convection. Circulation of the deep lake occurs periodically in winter and spring when cold, near-surface waters sink to the lake bottom; a process that results in the upwelling of nutrients, especially nitrate-N, into the upper strata of the lake. Thermal stratification occurs in late summer and fall. The maximum thickness of the epilimnion is about 20 m and the metalimnion extends to a depth of about 100 m. Thus, most of the lake volume is a cold hypolimnion. The year-round near-bottom temperature is about 3.5??C. Overall, hydrothermal fluids define and temporally maintain the basic water quality characteristics of the lake (e.g., pH, alkalinity and conductivity). Total phosphorus and orthophosphate-P concentrations are fairly uniform throughout the water column, where as total Kjeldahl-N and ammonia-N are highest in concentration in the upper lake. Concentrations of nitrate-N increase with depth below 200 m. No long-term changes in water quality have been detected. Secchi disk (20-cm) clarity varied seasonally and annually, but was typically highest in June and lowest in August. During the current study, August Secchi disk clarity readings averaged about 30 m. The maximum individual clarity reading was 41.5 m in June 1997. The lowest reading was 18.1 m in July 1995. From 1896 (white-dinner plate) to 2003, the average August Secchi disk reading was

  8. 78 FR 77594 - Safety Zone; Barge Launches; Gulfport Lake; Gulfport, MS

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-12-24

    ...The Coast Guard is establishing a safety zone for Gulfport Lake, Gulfport, MS. This action is necessary for the protection of persons and vessels on navigable waters during the launching of barges in Gulfport Lake, Gulfport, MS, particularly small craft in the area that risk being swamped. Entry into, transiting or anchoring in the zone during the launching of barges is prohibited for all......

  9. Patterns of lake occupancy by fish indicate different adaptations to life in a harsh Arctic environment

    USGS Publications Warehouse

    Haynes, Trevor B.; Rosenberger, Amanda E.; Lindberg, Mark S.; Whitman, Matthew; Schmutz, Joel A.

    2014-01-01

    Based on these patterns, we propose an overall model of primary controls on the distribution of fish on the Arctic Coastal Plain of Alaska. Harsh conditions, including lake freezing, limit occupancy in winter through extinction events while lake occupancy in spring and summer is driven by directional migration (large-bodied species) and undirected dispersal (small-bodied species).

  10. Monitoring infiltration and recharge of playa lakes in the Texas Southern High Plains

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Preliminary results from playa lakes monitored by the Texas Water Development Board (TWDB) suggest that a small volume of deep infiltration and recharge to the Ogallala aquifer occurs along the margins of the lake beds, while the majority of infiltration associated with a typical inundation remains ...

  11. Porcine proliferative enteropathy in Estonian pig herds: histopathology and detection of Lawsonia intracellularis by PCR.

    PubMed

    Järveots, Tönu; Saar, Tiiu; Lepp, Elbi; Suuroja, Toivo; Lindjärv, Raivo; Nathues, Heiko; Sütt, Silva; Põdersoo, Diivi

    2011-01-01

    Lawsonia intracellularis is the causative agent of proliferative enteritis in pigs (PPE). This bacterium is difficult to culture from clinical samples and antemortem demonstration is therefore usually performed by PCR on faecal samples. The aim of this study was to elucidate the frequency of L. intracellularis infection in pig herds in Estonia using PCR, histopathological methods and electronmicroscopical studies. The frequency of demonstration of L. intracellularis was highest in 9-12 weeks old pigs (68.1%). It was more frequent in growing pigs with enteritis on small farms where the system of "all-in all-out" was not practiced and where standards of hygiene were poor. Gross and histopathological studies demonstrated that characteristic macroscopic changes associated with PPE were localised to the distal jejunum and ileum.Thickened longitudinal and circumferential folds occurred in the mucosa of the affected regions of the bowel. Samples from pigs aged 4 to 20 weeks exhibited the most intensive inflammatory changes. The distal part of the jejunum, ileum and the upper third of proximal colon and cecum wall were visibly thickened with reduced luminal diameter. Hyperplasia of lymphoid tissue and, in many cases, pseudomembranous or fibrinous inflammation was found. L. intracellularis was detected in 56 young pigs using histopathological methods. Additionally, in 8 of these pigs intracellular bacteria were demonstrated in ilial epithelial cells by transmission electronmicroscopical (TEM) investigation. On the basis of these TEM investigations it was concluded that L. intracellularis causes disturbances of normal growth, differentiation and apoptosis of the epithelial cells of ileum. PMID:21306056

  12. Regional patterns and local variability of dry and occult deposition strongly influence sulfate concentrations in Maine lakes

    SciTech Connect

    Norton, S.A.; Kahl, J.S.; Brakke, D.F.; Brewer, G.F.; Haines, T.A.

    1988-01-01

    There is great uncertainty and large cost in making dry deposition measurements. The authors present evidence based on wet deposition, evapotranspiration, S storage in lake sediments, and sulfate concentrations in lakes and streams in Maine that the dry deposition flux of sulfur to drainage basins of lakes in Maine ranges from nearly 0% to more than 100% of wet deposition, even in small areas. The regional pattern of sulfate concentrations in Maine lakes is due to gradients in both wet and dry deposition and variation in evapotranspiration. Patterns are modified locally by lakes hydrologic type, elevation, vegetation, and terrestrial drainage basin aspect. (Copyright (c) 1988 Elsevier Science Publishers B.V.)

  13. Transient Tsunamis in Lakes

    NASA Astrophysics Data System (ADS)

    Couston, L.; Mei, C.; Alam, M.

    2013-12-01

    A large number of lakes are surrounded by steep and unstable mountains with slopes prone to failure. As a result, landslides are likely to occur and impact water sitting in closed reservoirs. These rare geological phenomena pose serious threats to dam reservoirs and nearshore facilities because they can generate unexpectedly large tsunami waves. In fact, the tallest wave experienced by contemporary humans occurred because of a landslide in the narrow bay of Lituya in 1958, and five years later, a deadly landslide tsunami overtopped Lake Vajont's dam, flooding and damaging villages along the lakefront and in the Piave valley. If unstable slopes and potential slides are detected ahead of time, inundation maps can be drawn to help people know the risks, and mitigate the destructive power of the ensuing waves. These maps give the maximum wave runup height along the lake's vertical and sloping boundaries, and can be obtained by numerical simulations. Keeping track of the moving shorelines along beaches is challenging in classical Eulerian formulations because the horizontal extent of the fluid domain can change over time. As a result, assuming a solid slide and nonbreaking waves, here we develop a nonlinear shallow-water model equation in the Lagrangian framework to address the problem of transient landslide-tsunamis. In this manner, the shorelines' three-dimensional motion is part of the solution. The model equation is hyperbolic and can be solved numerically by finite differences. Here, a 4th order Runge-Kutta method and a compact finite-difference scheme are implemented to integrate in time and spatially discretize the forced shallow-water equation in Lagrangian coordinates. The formulation is applied to different lake and slide geometries to better understand the effects of the lake's finite lengths and slide's forcing mechanism on the generated wavefield. Specifically, for a slide moving down a plane beach, we show that edge-waves trapped by the shoreline and free

  14. Reevaluation of lake trout and lake whitefish bioenergetics models

    USGS Publications Warehouse

    Madenjian, Charles P.; Pothoven, Steve A.; Kao, Yu-Chun

    2013-01-01

    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.

  15. Maturity schedules of lake trout in Lake Michigan

    USGS Publications Warehouse

    Madenjian, Charles P.; DeSorcie, Timothy J.; Stedman, Ralph M.

    1998-01-01

    We determined maturity schedules of male and female lake trout (Salvelinus namaycush) in Lake Michigan from nearshore populations and from an offshore population on Sheboygan Reef, which is located in midlake. Gill nets and bottom trawls were used to catch lake trout in fall 1994 and 1995 from two nearshore sites and Sheboygan Reef. Each lake trout was judged immature or mature, based on visual examination of gonads. Probit analysis, coupled with relative potency testing, revealed that age-at-maturity and length-at-maturity were similar at the two nearshore sites, but that lake trout from the nearshore sites matured at a significantly earlier age than lake trout from Sheboygan Reef. However, length at maturity for the nearshore populations was nearly identical to that for the offshore population, suggesting that rate of lake trout maturation in Lake Michigan was governed by growth rather than age. Half of the lake trout males reached maturity at a total length of 580 mm, whereas half of the females were mature at a length of 640 mm. Over half of nearshore males were mature by age 5, and over half the nearshore females matured by age 6. Due to a slower growth rate, maturity was delayed by 2 years on Sheboygan Reef compared with the nearshore populations. Documentation of this delay in maturation may be useful in deciding stocking allocations for lake trout rehabilitation in Lake Michigan.

  16. Gas exchange on Mono Lake and Crowley Lake, California

    NASA Technical Reports Server (NTRS)

    Wanninkhof, Rik; Ledwell, James R.; Broecker, Wallace S.

    1987-01-01

    Gas exchange coefficients (k) have been determined for freshwater Crowley Lake and saline Mono Lake through the use of a man-made purposefully injected gas, SF6. The concentration decreased from an initial value of 40 to 4 pmol/L for Mono Lake and from 20 to 1 pmol/L for Crowley lake over a period of 6 wks. Wind-speed (u) records from anemometers on the shore of each lake made it possible to determine the relationship between k and u. The average u and k values for the experiment were identical for the two lakes, despite the large chemical differences. It is estimated that, for the u values observed over Mono Lake from July to December 1984, the exchange of CO2 occurred 2.5 times faster than without chemical enhancement. This is a factor of 4 lower than needed to explain the high invasion rate of C-14 produced by nuclear bomb tests.

  17. Allogenic sedimentary components of Bear Lake, Utah and Idaho

    USGS Publications Warehouse

    Rosenbaum, J.G.; Dean, W.E.; Reynolds, R.L.; Reheis, M.C.

    2009-01-01

    Bear Lake is a long-lived lake filling a tectonic depression between the Bear River Range to the west and the Bear River Plateau to the east, and straddling the border between Utah and Idaho. Mineralogy, elemental geochemistry, and magnetic properties provide information about variations in provenance of allogenic lithic material in last-glacial-age, quartz-rich sediment in Bear Lake. Grain-size data from the siliciclastic fraction of late-glacial to Holocene carbonate-rich sediments provide information about variations in lake level. For the quartz-rich lower unit, which was deposited while the Bear River fl owed into and out of the lake, four source areas are recognized on the basis of modern fluvial samples with contrasting properties that reflect differences in bedrock geology and in magnetite content from dust. One of these areas is underlain by hematite-rich Uinta Mountain Group rocks in the headwaters of the Bear River. Although Uinta Mountain Group rocks make up a small fraction of the catchment, hematite-rich material from this area is an important component of the lower unit. This material is interpreted to be glacial fl our. Variations in the input of glacial flour are interpreted as having caused quasi-cyclical variations in mineralogical and elemental concentrations, and in magnetic properties within the lower unit. The carbonate-rich younger unit was deposited under conditions similar to those of the modern lake, with the Bear River largely bypassing the lake. For two cores taken in more than 30 m of water, median grain sizes in this unit range from ???6 ??m to more than 30 ??m, with the coarsest grain sizes associated with beach or shallow-water deposits. Similar grain-size variations are observed as a function of water depth in the modern lake and provide the basis for interpreting the core grain-size data in terms of lake level. Copyright ?? 2009 The Geological Society of America.

  18. Diatom data from Bradley Lake, Oregon: downcore analyses

    USGS Publications Warehouse

    Hemphill-Haley, Eileen; Lewis, Roger C.

    2003-01-01

    Displaced marine diatoms provide biostratigraphic evidence for tsunami inundation at Bradley Lake, a small freshwater lake on the south-central Oregon coast. During the past 7,200 years, fine-grained lacustrine deposits in the deep axis of the lake were disturbed 17 times by the erosion and emplacement of coarse-grained gyttja and, in some cases, sand. By identifying diatoms in closely spaced core samples, we determined that 13 of the 17 events (termed idisturbance eventsi) record prehistoric tsunamis in Bradley Lake. We consider the evidence strong for 11 events, based on numbers and diversity of marine taxa: De1, De2, De4, De5, De6, De7, De8, De11, De12, De13, and De17. The evidence is less compelling for an additional 2 events (De9 and De10), although tsunami inundation is likely. Finally, we identified 4 events (De3, De14, De15 and De16) in which there were no marine diatoms to support tsunami inundation, although stratigraphic data shows that the lake bottom was disturbed. Freshwater diatoms dominate throughout the Bradley Lake record, showing that the lake has remained a freshwater habitat throughout its existence. However, anomalous occurrences of three species of brackish diatoms (Thalassiosira bramaputrae, Cyclotella meneghiniana, and Mastogloia smithii) may be evidence for short-lived periods of slightly elevated salinities in the lake following De16, De13, De12, De11, De9, De8, and De5. With the exception of De12, increased abundances of one or more of the brackish species is coincident with decreased numbers of freshwater diatoms. A temporary rise in salinity, as evidenced by short-lived increases in abundances of brackish species and decreases in abundances of freshwater species, is consistent with tsunami inundation into the lake.

  19. The Tunguska event and Cheko lake origin: dendrochronological analysis

    NASA Astrophysics Data System (ADS)

    Rosanna, Fantucci; Romano, Serra; Gunther, Kletetschka; Mario, Di Martino

    2015-07-01

    Dendrochronological research was carried out on 23 trees samples (Larix sibirica and Picea obovata) sampled during the 1999 expedition in two locations, close to the epicentre zone and near Cheko lake (N 60°57', E 101°51'). Basal Area Increment (BAI) analysis has shown a general long growth suppression before 1908, the year of Tunguska event (TE), followed by a sudden growth increase due to diminished competition of trees that died due to the event. In one group of the trees, we detected growth decrease for several years (due to damage to the trunk, branches and crown), followed by growth increase during the following 4-14 years. We show that trees that germinated after the TE, and living in close proximity of Cheko lake (Cheko lake trees) had different behaviour patterns when compared to those trees living further from Cheko lake, inside the forest (Forest trees). Cheko lake trees have shown a vigorous continuous growth increase. Forest trees have shown a vigorous growth during the first 10-30 years of age, followed by a period of suppressed growth. We interpret the suppressed growth by the re-established competition with the surroundings trees. Cheko lake pattern, however, is consistent with the formation of the lake at the time of TE. This observation supports the hypothesis that Cheko lake formation is due to a fragment originating during TE, creating a small impact crater into the permafrost and soft alluvial deposits of Kimku River plain. This is further supported by the fact that Cheko lake has an elliptical shape elongated towards the epicentre of TE.

  20. Depth as an organizer of fish assemblages in floodplain lakes

    USGS Publications Warehouse

    Miranda, L.E.

    2011-01-01

    Depth reduction is a natural process in floodplain lakes, but in many basins has been accelerated by anthropogenic disturbances. A diverse set of 42 floodplain lakes in the Yazoo River Basin (Mississippi, USA) was examined to test the hypothesis of whether depth reduction was a key determinant of water quality and fish assemblage structure. Single and multiple variable analyses were applied to 10 commonly monitored water variables and 54 fish species. Results showed strong associations between depth and water characteristics, and between depth and fish assemblages. Deep lakes provided less variable environments, clearer water, and a wider range of microhabitats than shallow lakes. The greater environmental stability was reflected by the dominant species in the assemblages, which included a broader representation of large-body species, species less tolerant of extreme water quality, and more predators. Stability in deep lakes was further reflected by reduced among-lake variability in taxa representation. Fish assemblages in shallow lakes were more variable than deep lakes, and commonly dominated by opportunistic species that have early maturity, extended breeding seasons, small adult size, and short lifespan. Depth is a causal factor that drives many physical and chemical variables that contribute to organizing fish assemblages in floodplain lakes. Thus, correlations between fish and water transparency, temperature, oxygen, trophic state, habitat structure, and other environmental descriptors may ultimately be totally or partly regulated by depth. In basins undergoing rapid anthropogenic modifications, local changes forced by depth reductions may be expected to eliminate species available from the regional pool and could have considerable ecological implications. ?? 2010 Springer Basel AG (outside the USA).

  1. Decadal oscillation of lakes and aquifers in the upper Great Lakes region of North America: Hydroclimatic implications

    NASA Astrophysics Data System (ADS)

    Watras, C. J.; Read, J. S.; Holman, K. D.; Liu, Z.; Song, Y.-Y.; Watras, A. J.; Morgan, S.; Stanley, E. H.

    2014-01-01

    We report a unique hydrologic time series which indicates that water levels in lakes and aquifers across the upper Great Lakes region of North America have been dominated by a climatically driven, near-decadal oscillation for at least 70 years. The historical oscillation (~13 years) is remarkably consistent among small seepage lakes, groundwater tables, and the two largest Laurentian Great Lakes despite substantial differences in hydrology. Hydrologic analyses indicate that the oscillation has been governed primarily by changes in the net atmospheric flux of water (P - E) and stage-dependent outflow. The oscillation is hypothetically connected to large-scale atmospheric circulation patterns originating in the midlatitude North Pacific that support the flux of moisture into the region from the Gulf of Mexico. Recent data indicate an apparent change in the historical oscillation characterized by an ~12 years downward trend beginning in 1998. Record low water levels region wide may mark the onset of a new hydroclimatic regime.

  2. Systematic High-Resolution (30 meter) Inventory of Global Lakes: Pan-Arctic and Beyond

    NASA Astrophysics Data System (ADS)

    Sheng, Y.; Wang, J.; Smith, L. C.; Lyons, E. A.; Te, G.; Woods, J.; Garibay, D.; Knox, B.

    2014-12-01

    [Abstract] Lakes play a crucial role in the global water cycle and balance, are sensitive to global warming, and are vital for human water supply. There clearly is a pressing need to understand temporal and spatial variations in lake water storage globally, especially in the lake-rich Arctic/Sub-Arctic regions. An accurate systematic lake inventory, however, is unavailable at global scales. Owing to its broad spatial coverage and repeat-pass monitoring capability, satellite remote sensing is the only feasible approach to inventory global lake dynamics. Global lake mapping at high resolutions is a rather challenging task. Since lakes are abundant in small-size classes and their seasonality varies from region to region, a huge number of high-resolution satellite images need to be acquired in "appropriate" seasons. The appropriate seasons refer to the period in a typical year when lakes are relatively stable, and are determined spatially using precipitation and temperature datasets. Thousands of cloud-free Landsat images at 30 m resolution have been acquired during lake-stable seasons. Satellite lake mapping succeeds at different levels from place to place and from season to season. A set of highly replicable automated lake mapping methods and tools have been developed to tackle various situations across the entire Earth and to handle such a large volume of satellite data. The current goal is to produce a circa 2000 high-resolution global lake database in a systematic way. Millions of lakes larger than 0.5 ha have been inventoried. The product is currently examined in an intensive quality control and quality assurance process. Over six million lakes in pan-Arctic (45 deg N and above) are captured in the database and have been validated for release.

  3. Discontinuities in stream nutrient uptake below lakes in mountain drainage networks

    USGS Publications Warehouse

    Arp, C.D.; Baker, M.A.

    2007-01-01

    In many watersheds, lakes and streams are hydrologically linked in spatial patterns that influence material transport and retention. We hypothesized that lakes affect stream nutrient cycling via modifications to stream hydrogeomorphology, source-waters, and biological communities. We tested this hypothesis in a lake district of the Sawtooth Mountains, Idaho. Uptake of NO3- and PO4-3 was compared among 25 reaches representing the following landscape positions: lake inlets and outlets, reaches >1-km downstream from lakes, and reference reaches with no nearby lakes. We quantified landscape-scale hydrographic and reach-scale hydrogeomorphic, source-water, and biological variables to characterize these landscape positions and analyze relationships to nutrient uptake. Nitrate uptake was undetectable at most lake outlets, whereas PO4-3 uptake was higher at outlets as compared to reference and lake inlet reaches. Patterns in nutrient demand farther downstream were similar to lake outlets with a gradual shift toward reference-reach functionality. Nitrate uptake was most correlated to sediment mobility and channel morphology, whereas PO 4-3 uptake was most correlated to source-water characteristics. The best integrated predictor of these patterns in nutrient demand was % contributing area (the proportion of watershed area not routing through a lake). We estimate that NO3- and PO 4-3 demand returned to 50% of pre-lake conditions within 1-4-km downstream of a small headwater lake and resetting of nutrient demand was slower downstream of a larger lake set lower in a watershed. Full resetting of these nutrient cycling processes was not reached within 20-km downstream, indicating that lakes can alter stream ecosystem functioning at large spatial scales throughout mountain watersheds. ?? 2007, by the American Society of Limnology and Oceanography, Inc.

  4. Does road salting confound the recovery of the microcrustacean community in an acidified lake?

    PubMed

    Jensen, Thomas Correll; Meland, Sondre; Schartau, Ann Kristin; Walseng, Bjørn

    2014-04-15

    Numerous boreal lakes across the Northern Hemisphere recovering from acidification are experiencing a simultaneous increase in chloride (Cl) concentrations from road salting. Increasing Cl may have profound effects on the lake ecosystem. We examine if an increase in Cl from road salting has modified the recovery of the microcrustacean community in an acidified boreal lake undergoing chemical recovery (study lake). Results from the study lake were compared with an acidified "reference lake". The community changed during the study period in the study lake mainly driven by the reduction in acidification pressure. Despite the community changes and an increase in species richness, the absence of several acid sensitive species, previously occurring in the lake, indicates a delayed biological recovery relative to the chemical recovery. Moreover, changes in occurrence of acid sensitive and acid tolerant species indicated that the biological recovery was slower in the study lake compared to the "reference". Although recurrent episodes of high aluminum and low pH and decreasing Ca are likely important factors for the delay, these do not explain, for instance, the shift from Cyclops scutifer to Bosmina longispina in the study lake. Although the contribution of Cl was not significant, the correlation between Cl and the variation in microcrustacean community was twice as high in the study lake compared to the "reference". We argue that small, sheltered forest lakes may be especially sensitive to increased Cl levels, through changes in pattern of stratification, thus providing a mechanism for the shift from C. scutifer to B. longispina. The reduction of the acidification pressure seems to override the Cl effects on microcrustaceans at low Cl levels in salt-affected lakes recovering from acidification. However, prognoses for growing traffic and increasing road salting raise concern for many recovering lakes located in proximity to roads and urbanized areas. PMID:24530583

  5. Origin and Distribution Of Glacial Lakes: A Case Study In Tista Basin, India

    NASA Astrophysics Data System (ADS)

    Kulkarni, A. V.

    2015-12-01

    Himalayan glaciers are experiencing retreat due to changes in the temperature and precipitation pattern. Retreating glaciers depending upon the underlying bed topography can cause lake formation near terminus. Therefore formation and draining of lakes in the glaciated terrain of Himalaya is commonly observed. However, few lakes became stable under suitable geomorphologic conditions and grow sufficiently large to threaten population and infrastructure in downstream. In this investigation changes in glacial lakes in Tista basin were studied using satellite images for a period between 1989 and 2010. The Tista basin in Sikkim covers approximately 7096 sq km area and the total glaciated area is 501± 29 sq km. During the period of investigation the lake area is increased from 6.6 ± 0.8 km2 to 9.6 ± 1.1 km2 due to formation of new lakes and also due to expansion of existing lake. Out of 23 lakes, 16 showed variable increase in area. We have also observed formation of stable proglacial lake due to coalescence of small supra glacial lakes on Changsang and South Lhonak Glacier. The size of lake near South Lhonak Glacier was increased from 18 to 126 ha from 1978 to 2014 (Figure). Therefore detail field investigations were carried out to understand volume and extent of ice in end moraine. The water volume was estimated as 53 million m3 using bathymetric survey and ice at the core of terminal moraines was mapped using resistivity survey. These investigations suggests a possibility of catastrophic outburst flood, if moraine dam breached under extreme weather conditions. Therefore, mitigation strategy is needed to improve safety of people living in the region. In addition, numerous remote sensing based investigations have mapped more than 300 lakes in the glaciated terrain in India, therefore, a national program to monitor glacier lakes and strategy to mitigate possible disaster is needed. Figure: Expansion of the lake near South Lhonak glacier from year 1990 to 2014.

  6. Holocene climate on the Modoc Plateau, northern California, USA: The view from Medicine Lake

    USGS Publications Warehouse

    Starratt, S.W.

    2009-01-01

    Medicine Lake is a small (165 ha), relatively shallow (average 7.3 m), intermediate elevation (2,036 m) lake located within the summit caldera of Medicine Lake volcano, Siskiyou County, California, USA. Sediment cores and high-resolution bathymetric and seismic reflection data were collected from the lake during the fall of 1999 and 2000. Sediments were analyzed for diatoms, pollen, density, grain size (sand/mud ratio), total organic carbon (TOC), and micro-scale fabric analysis. Using both 14C (AMS) dating and tephrochronology, the basal sediments were estimated to have been deposited about 11,400 cal year BP, thus yielding an estimated average sedimentation rate of about 20.66 cm/1,000 year. The lowermost part of the core (11,400-10,300 cal year BP) contains the transition from glacial to interglacial conditions. From about 11,000-5,500 cal year BP, Medicine Lake consisted of two small, steep-sided lakes or one lake with two steep-sided basins connected by a shallow shelf. During this time, both the pollen (Abies/Artemisia ratio) and the diatom (Cyclotella/Navicula ratio) evidences indicate that the effective moisture increased, leading to a deeper lake. Over the past 5,500 years, the pollen record shows that effective moisture continued to increase, and the diatom record indicates fluctuations in the lake level. The change in the lake level pattern from one of the increasing depths prior to about 6,000 cal year BP to one of the variable depths may be related to changes in the morphology of the Medicine Lake caldera associated with the movement of magma and the eruption of the Medicine Lake Glass Flow about 5,120 cal year BP. These changes in basin morphology caused Medicine Lake to flood the shallow shelf which surrounds the deeper part of the lake. During this period, the Cyclotella/Navicula ratio and the percent abundance of Isoetes vary, suggesting that the level of the lake fluctuated, resulting in changes in the shelf area available for colonization by

  7. QuickBird satellite imagery as a tool for restoration and rehabilitation of Lake Sevan, Armenia

    USGS Publications Warehouse

    Stapanian, Martin A.

    2011-01-01

    Lake Sevan in Armenia is the largest freshwater lake in the Transcaucasus region and is one of the largest high-altitude freshwater lakes in Eurasia (Babayan et al., 2006). Armenia is a small (29,743 km2), land- locked country that is comparatively poor in natural resources and nearly surrounded by borders that are blockaded by its neighbors (Babayan et al., 2006; Rhoades, 2008 and references therein; CIA, 2010). Despite these obstacles, ecological research and environmental restoration efforts continue. For the most part, ecological research in Lake Sevan during the twentieth century was restricted to Soviet-era journals, or was otherwise unavailable to western scientists. 

  8. Lake whitefish diet, condition, and energy density in Lake Champlain and the lower four Great Lakes following dreissenid invasions

    USGS Publications Warehouse

    Herbst, Seth J.; Marsden, J. Ellen; Lantry, Brian F.

    2013-01-01

    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.

  9. Institutional aspects of lake management

    NASA Astrophysics Data System (ADS)

    Born, Stephen M.; Rumery, Carolyn

    1989-01-01

    The major barriers to successful lake management are institutional. However, in contrast to the technical and limnological dimensions of lake management, the institutional aspects of managing lakes have received little attention. The institutional factors that are important for successful lake management outcomes are: overlapping areal jurisdiction among governmental units, fragmented functional program responsibilities, ineffective coordination, limited authority, financial constraints, private sector roles, and inadequate public awareness and consensus. The range of typical institutional problems confronting lake management are well illustrated through experiences from the state of Wisconsin, USA. Because lake management programs with institutional shortcomings rarely realize their goals, it is critical to assimilate, evaluate, and apply our experience to date with the institutional arrangements necessary to effectively manage lake resources.

  10. Juliana Lake: A Benghazi Wetland In Distress!

    NASA Astrophysics Data System (ADS)

    Abdulsamad, Esam O.; Elbabour, Mansour M.

    2013-04-01

    Of all the remaining natural habitats of Benghazi's urban area (NE Libya), perhaps the most threatened are its karst lakes and coastal salt marshes (locally known as Sebkhas). Juliana Lake stands out as one example of a fragile ecosystem that is steadily shrinking and exposed to dredging and, consequently, possible damage to its aquatic organisms, and the inevitable loss of its renowned biodiversity. Several 19th & 20th-century traveler's sketches and maps, soil maps, photographs and satellite images provide the bases for change in the size and magnitude of the lake and its adjacent areas over time. The study also includes an assessment of the sediment composition and texture of material accumulating at the bottom of the lake. These sediments are composed essentiality of mixtures of Sebkha sediments such as salty clay, silt, and clayey sand. The sediments at the surface and around the Juliana Lake, however, are represented by quite soft whitish to yellowish and scattered patchy limestones of unknown affinity. Terra-rossa (reddish soil) and Quaternary caliche are present also but calcarenites (clastic limestone) cover considerable part of the studied area. The bio-micro components of these sediments are described and a number of small-sized benthic foraminifera have been identified. Macrofauna, which are primarily presented by recent benthic seashells belonging to phylum mollusca, have also been investigated and several species have been identified to the species level wherever possible. Other calcareous biotic components are predominantly shell fragments of molluscs, bryozoans, echinoderms and calcareous coralline red algae. It is concluded that the distribution, diversity and abundance of the total benthic organisms recovered in this survey reflect that the local habitat of the Juliana Lake were rich in nutrients and consequently providing an important food source for fishes, birds, and mammals. In fact, without these benthic organisms, these larger animals would

  11. CONTOURITES IN LAKE SUPERIOR

    EPA Science Inventory

    Contour currents influence sedimentation in an area 15 km wide and 65 km long at the base of the slope off the Keweenaw Peninsula in Lake Superior, northwestern Michigan. Seismic-reflection profiles (3.5 kHz) from this area show distinct wavy reflectors in a scoured trough at a d...

  12. Utah: Salt Lake City

    Atmospheric Science Data Center

    2014-05-15

    ... mountains surrounding Salt Lake City are renowned for the dry, powdery snow that results from the arid climate and location at the ... should be used with the red filter placed over your left eye. The canyons and peaks of the Uinta and Wasatch Mountains are ...

  13. Quebec: Lake Manicouagan

    Atmospheric Science Data Center

    2013-04-17

    ... and other erosional processes have reduced the extent of the crater, with the original diameter estimated at about 100 kilometers. This ... metamorphic effects are abundant in the target rocks of the crater floor. Today Lake Manicouagan serves as a reservoir and is one of ...

  14. The People's Lake

    ERIC Educational Resources Information Center

    Carlson, Karen Townsend

    1975-01-01

    Citizen action to stop the disposal of taconite tailings into Lake Superior was unsuccessful when the courts settled in the favor of industry. Although citizen research revealed a form of asbestos, as well as other toxic chemicals in the discharged wastes, company representatives stated that there were no health hazards. (MA)

  15. Great Minds? Great Lakes!

    ERIC Educational Resources Information Center

    Environmental Protection Agency, Chicago, IL. Great Lakes National Program Office.

    This booklet introduces an environmental curriculum for use in a variety of elementary subjects. The lesson plans provide an integrated approach to incorporating Great Lakes environmental issues into the subjects of history, social studies, and environmental sciences. Each of these sections contains background information, discussion points, and a…

  16. Echoes of Bark Lake.

    ERIC Educational Resources Information Center

    Duenkel, Nicky; Hemstreet, Jeff

    1997-01-01

    Two former staff members reflect on their feelings about the August 1995 closing of Bark Lake Leadership Centre (Ontario, Canada), which for 49 years had offered outdoor adventure and environmental education courses to youth and adults. They discuss their experiences as both students and teachers at the center, which helped shape their careers in…

  17. Upwellings in Lake Baikal

    NASA Astrophysics Data System (ADS)

    Shimaraev, M. N.; Troitskaya, E. S.; Blinov, V. V.; Ivanov, V. G.; Gnatovskii, R. Yu.

    2012-02-01

    Based on shipboard and satellite observations, the characteristics of upwelling in Lake Baikal in the period of direct temperature stratification have been determined for the first time. Coastal upwellings appear annually under the effect of run-down and alongshore winds and are traced along the coast to a distance of up to 60-100 km and up to 250 km in North Baikal. Analogous to the way it occurs in seas, water rises from the depths of 100-200 m (350 m as a maximum) at the velocity of 0.1 × 10-2-6.5 × 10-2 cm/s. Divergence in the field of intràbasin cyclonic macrovortices produces upwelling in the Baikal pelagic zone and downwelling in the vicinity of shores; this lasts from 7 to 88 days and covers the depth interval of 80-300 m in August and up to 400-800 m in early-mid November. The area of upwellings occupies up to 20-60% of the separate basins of the lake. Vertical circulation of water in the field of pelagic upwellings leads to intensification of coastal currents and to formation of the thermobar with a heat inert zone in the central part of the lake in November, and this thermobar is not observed in other lakes, at that.

  18. LAKE TAHOE VISIBILITY STUDY

    EPA Science Inventory

    Visibility monitoring and airborne particulate sampling in the Lake Tahoe Basin were used to document visual air quality levels and to assess the relative impacts of major contributing emission source categories. Visibility data were obtained by long path contrast and particle sc...

  19. Lake Ontario: Nearshore Variability

    EPA Science Inventory

    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. ...

  20. Lake Michigan: Nearshore Variability

    EPA Science Inventory

    We conducted a high-resolution survey in the nearshore of Lake Michigan at a 20 meter contour using towed electronic instrumentation. The nearly 1200 km survey was conducted Sep 8-15, 2010. We also conducted six cross-contour tows. Along the survey tracks we sampled fixed stat...

  1. Surface heat flux variability of a large lake: Lake Geneva, Switzerland

    NASA Astrophysics Data System (ADS)

    Irani Rahaghi, A.; Lemmin, U.; Bouffard, D.; Riffler, M.; Wunderle, S.; Barry, D. A.

    2014-12-01

    The heat budget of a lake is a fundamental component of physical limnology, and is strongly dependent on the surface heat flux. However, the surface energy exchange depends on several factors, making it difficult to estimate. In this study we employed several bulk formulas to estimate Lake Geneva's surface heat flux. Combination of different surface heat flux terms leads to a surface heat exchange model which requires various data. Different data sources were used in the heat flux estimates. Meteorological data were taken from an operational numerical weather prediction model, namely COSMO-2 (run by the Swiss meteorological service), while satellite imagery was used for the lake surface water temperature (LSWT). In order to find the best combination of the bulk formulas and to calibrate the model, the temporal evolution of the heat budget was estimated using long-term time series of vertical temperature profiles. Vertical temperature profiles at two points (one in the Lake Geneva's large basin and one in its small basin) were used. A sensitivity analysis was performed to find the key parameters, and more significantly the optimal combination of different heat flux terms. Finally, the spatio-temporal surface heat flux variation was calculated according to the proposed model. In addition, the relationship between variability of the surface heat flux and meteorological forcing was assessed. The different models, which are of differing complexity, gave reasonably consistent results, with differences attributed to simplifications inherent in them. The modeling results revealed that the LSWT and wind forcing are dominant factors underlying Lake Geneva surface heat flux spatial variation, while its temporal variability is mainly due to the global radiation and air temperature changes. In conclusion, the bulk heat balance approach is a useful tool to estimate various heat flux terms as well as their monthly or seasonally contributions. But, in large lakes where the LSWT is

  2. The role of depth in regulating water quality and fish assemblages in oxbow lakes

    USGS Publications Warehouse

    Goetz, Daniel B.; Miranda, Leandro E.; Kroger, Robert; Andrews, Caroline S.

    2015-01-01

    We evaluated water quality and fish assemblages in deep (> 3.0 m; N = 7) and shallow (< 1.5 m; N = 6) floodplain lakes in the intensively cultivated Yazoo River Basin (Mississippi, USA) using indirect gradient multivariate procedures. Shallow lakes displayed wide diel oxygen fluctuations, some reaching hypoxic/anoxic conditions for extended periods of time, high suspended solids, and extreme water temperatures. Conversely, deeper lakes were represented by higher visibility, stable oxygen levels, and cooler water temperatures. Fish assemblages in shallow lakes were dominated by tolerant, small-bodied fishes and those able to breathe atmospheric oxygen. Deeper lakes had a greater representation of predators and other large-bodied fishes. Our evaluation suggests fish assemblages are reflective of oxbow lakes water quality, which is shaped by depth. Understanding the interactions between depth, water quality, and fish assemblages may facilitate development of effective management plans for improving conditions necessary to sustain diverse fish assemblages in agriculturally dominated basins.

  3. Spatial and temporal variation in mercury bioaccumulation by zooplankton in Lake Champlain (North America)

    PubMed Central

    Kamman, Neil; Williams, Jason; Bugge, Deenie; Taylor, Vivien; Jackson, Brian; Miller, Eric

    2012-01-01

    Trophic transfer of Hg across lakes within a region has been related to multiple environmental factors, but the nature of these relationships across distinct basins within individual large lakes is unknown. We investigated Hg bioaccumulation in zooplankton in basins of differing trophic status in Lake Champlain (Vermont, USA) to determine the strongest predictors of Hg bioaccumulation. Zooplankton were sampled in Malletts Bay (oligotrophic) and Missisquoi Bay (eutrophic) in 2005–2008. Zooplankton in the eutrophic basin had lower concentrations of total Hg and MeHg than those in the oligotrophic basin in all years but 2007, when no bloom occurred in Missisquoi. In addition, Hg concentrations in seston and small zooplankton, sampled during 2009 at 12 sites spanning the lake, decreased with increasing phytoplankton and zooplankton biomass. Thus, Hg bioaccumulation in zooplankton across basins in Lake Champlain is related to trophic status, as observed previously in multiple lake studies. PMID:21995871

  4. Role of a productive lake in carbon sequestration within a calcareous catchment.

    PubMed

    Nõges, Peeter; Cremona, Fabien; Laas, Alo; Martma, Tõnu; Rõõm, Eva-Ingrid; Toming, Kaire; Viik, Malle; Vilbaste, Sirje; Nõges, Tiina

    2016-04-15

    For a long time, lakes were considered unimportant in the global carbon (C) cycle because of their small total area compared to the ocean. Over the last two decades, a number of studies have highlighted the important role of lakes in both sequestering atmospheric C and modifying the C flux from the catchment by degassing CO2 and methane and burying calcite and organic matter in the sediment. Based on a full C mass balance, high frequency measurements of lake metabolism and stable isotope analysis of a large shallow eutrophic lake in Estonia, we assess the role alkaline lakes play in augmenting the strength of terrestrial carbonate weathering as a temporary CO2 sink. We show that a large part of organic C buried in the sediments in this type of lakes originates from the catchment although a direct uptake from the atmosphere during periods of intensive phytoplankton growth in eutrophic conditions contributes to the carbon sink. PMID:26815299

  5. Fremont Lake, Wyoming--some aspects of the inflow of water and sediment

    USGS Publications Warehouse

    Emmett, W.W.; Averett, R.C.

    1989-01-01

    Fremont Lake is a large (20.6 sq km), deep lake (185 m) in western Wyoming. Average annual inflow of water is about 5.1 cu meters/sec, and this discharge is equaled or exceeded about 23% of the time. Annual instantaneous peak flows of Pine Creek usually exceed 30 cu m/sec and the 100-year flood is about 80 cu m/sec. About 800 tons of sediment are delivered to the lake annually; annual deposition of sediment in the northern lake area throughout the last 10,000 years about equals contemporary values of sediment inflow. Only small quantities of fine-gradient sediment are transported beyond the delta at the northern end of the lake. Current rates of deposition in the delta are about 1 to 3 mm/yr. Sediment in the delta generally is sand size; elsewhere in the lake, sediment generally is clay and silt size. (USGS)

  6. Lake level variability in Silver Lake, Michigan: a response to fluctuations in lake levels of Lake Michigan

    USGS Publications Warehouse

    Fisher, Timothy G.; Loope, Walter L.

    2004-01-01

    Sediment from Silver Lake, Michigan, can be used to constrain the timing and elevation of Lake Michigan during the Nipissing transgression. Silver Lake is separated from Lake Michigan by a barrier/dune complex and the Nipissing, Calumet, and Glenwood shorelines of Lake Michigan are expressed landward of this barrier. Two Vibracores were taken from the lake in February 2000 and contain pebbly sand, sand, buried soils, marl, peat, and sandy muck. It is suggested here that fluctuations in the level of Lake Michigan are reflected in Silver Lake since the Chippewa low phase, and possibly at the end of the Algonquin phase. An age of 12,490 B.P. (10,460±50 14C yrs B.P.) on wood from a buried Entisol may record the falling Algonquin phase as the North Bay outlet opened. A local perched water table is indicated by marl deposited before 7,800 B.P. and peat between 7,760-7,000 B.P. when Lake Michigan was at the low elevation Chippewa phase. Continued deepening of the lake is recorded by the transition from peat to sandy muck at 7,000 B.P. in the deeper core, and with the drowning of an Inceptisol nearly 3 m higher at 6,410 B.P. in the shallower core. A rising groundwater table responding to a rising Lake Michigan base level during the Nipissing transgression, rather than a response to mid-Holocene climate change, explains deepening of Silver Lake. Sandy muck was deposited continually in Silver Lake between Nipissing and modern time. Sand lenses within the muck are presumed to be eolian in origin, derived from sand dunes advancing into the lake on the western side of the basin.

  7. Temperate Lakes Discovered on Titan

    NASA Astrophysics Data System (ADS)

    Vixie, Graham; Barnes, Jason W.; Jackson, Brian; Wilson, Paul

    2012-04-01

    We have discovered two temperate lakes on Titan using Cassini's Visual and Infrared Mapping Spectrometer (VIMS). Three key features help to identify these surface features as lakes: morphology, albedo, and specular reflection. The presence of lakes at the mid-latitudes mean liquid can accumulate and remain stable outside of the poles. We first identify a lake surface by looking for possible shorelines with a lacustrine morphology. Then, we apply a simple atmospheric correction that produces an approximate surface albedo. Next, we prepare cylindrical projection maps of the brightness of the sky as seen from any points on the surface to identify specular reflections. Our techniques can then be applied to other areas, such as Arrakis Planitia, to test for liquid. Currently, all the known lakes on Titan are concentrated at the poles. Lakes have been suggested in the tropic zone by Griffith et al. Our discovery of non-transient, temperate lakes has important implications for Titan's hydrologic cycle. Clouds have been recorded accumulating in the mid-latitudes and areas have been darkened by rainfall but later brightened after evaporation (Turtle et al. 2011). Stable temperate lakes would affect total rainfall, liquid accumulation, evaporation rates, and infiltration. Polaznik Macula (Figure 1) is a great candidate for lake filling, evaporation rates, and stability. References: Griffith, C., et al.: "Evidence for Lakes on Titan's Tropical Surface". AAS/Division for Planetary Sciences Meeting Abstracts #42, Vol. 42, pp. 1077, 2010. Turtle, E. P., et al.: "Rapid and Extensive Surface Changes Near Titan's Equator: Evidence of April Showers". Science, Vol. 331, pp. 1414-, 2011. Figure 1: Polaznik Macula is the large, dark area central to the figure. The encircled dark blue areas represent positively identified lake regions in the T66 flyby. The light blue areas represent lake candidates still under analysis. The green circle marks a non-lake surface feature enclosed by a

  8. Evidence of recent changes in the ice regime of lakes in the Canadian High Arctic from spaceborne satellite observations

    NASA Astrophysics Data System (ADS)

    Surdu, Cristina M.; Duguay, Claude R.; Fernández Prieto, Diego

    2016-05-01

    Arctic lakes, through their ice cover phenology, are a key indicator of climatic changes that the high-latitude environment is experiencing. In the case of lakes in the Canadian Arctic Archipelago (CAA), many of which are ice covered more than 10 months per year, warmer temperatures could result in ice regime shifts. Within the dominant polar-desert environment, small local warmer areas have been identified. These relatively small regions - polar oases - with longer growing seasons and greater biological productivity and diversity are secluded from the surrounding barren polar desert. The ice regimes of 11 lakes located in both polar-desert and polar-oasis environments, with surface areas between 4 and 542 km2, many of unknown bathymetry, were documented. In order to investigate the response of ice cover of lakes in the CAA to climate conditions during recent years, a 15-year time series (1997-2011) of RADARSAT-1/2 ScanSAR Wide Swath, ASAR Wide Swath, and Landsat acquisitions were analyzed. Results show that melt onset occurred earlier for all observed lakes. With the exception of Lower Murray Lake, all lakes experienced earlier summer ice minimum and water-clear-of-ice (WCI) dates, with greater changes being observed for polar-oasis lakes (9-24 days earlier WCI dates for lakes located in polar oases and 2-20 days earlier WCI dates for polar-desert lakes). Additionally, results suggest that some lakes may be transitioning from a perennial/multiyear to a seasonal ice regime, with only a few lakes maintaining a multiyear ice cover on occasional years. Aside Lake Hazen and Murray Lakes, which preserved their ice cover during the summer of 2009, no residual ice was observed on any of the other lakes from 2007 to 2011.

  9. Evidence of recent changes in the ice regime of lakes in the Canadian High Arctic from spaceborne satellite observations

    NASA Astrophysics Data System (ADS)

    Surdu, C. M.; Duguay, C. R.; Fernández Prieto, D.

    2015-11-01

    Arctic lakes, through their ice cover phenology, are a key indicator of climatic changes that the high-latitude environment is experiencing. In the case of lakes in the Canadian Arctic Archipelago (CAA), many of which are ice covered more than ten months per year, warmer temperatures could result in ice regime shifts. Within the dominant polar-desert environment, small local warmer areas have been identified. These relatively small regions - polar oases - with longer growing seasons, greater biological production and diversity, are confined from the surrounding barren polar desert. The ice regimes of 11 lakes located in both polar-desert and polar-oasis environments, with surface areas between 4 and 542 km2, many of unknown bathymetry, were documented. In order to investigate the response of ice cover of lakes in the CAA to climate conditions during recent years, a 15-year time series (1997-2011) of RADARSAT-1/2 ScanSAR Wide Swath, ASAR Wide Swath and Landsat acquisitions were analysed. Results show that melt onset (MO) occurred earlier for all observed lakes. With the exception of Lower Murray Lake, all lakes experienced earlier summer-ice minimum and water-clear-of-ice dates (WCI), with greater changes being observed for polar-oasis lakes (9-24 days earlier WCI dates for lakes located in polar oases and 2-20 days earlier WCI dates for polar-desert lakes). Additionally, results suggest that some lakes may be transitioning from a perennial/multiyear to a seasonal ice regime, with only a few lakes maintaining a multiyear ice cover on occasional years. Aside Lake Hazen and Murray Lakes that preserved their ice cover during the summer of 2009, no residual ice was observed on any of the other lakes from 2007 to 2011.

  10. How much acidification has occurred in Adirondack region lakes (New York, USA) since preindustrial times

    SciTech Connect

    Cumming, B.F.; Smol, J.P.; Kingston, J.C.; Charles, D.F.; Birks, H.J.B.

    1992-01-01

    Preindustrial and present-day lake water pH, acid neutralizing capacity (ANC), total monomeric aluminum Al(sub m), and dissolved organic carbon (DOC) were inferred from the species composition of diatom and chrysophyte microfossils in the tops (present-day inferences) and bottoms (pre-1850 inferences) of sediment cores collected from a statistically selected set of Adirondack lakes. Results from the study lakes were extrapolated to a predefined target population of 675 low-alkalinity Adirondack region lakes. Estimates of preindustrial to present-day changes in lake water chemistry show that approximately 25-35% of the target population has acidified. The magnitude of acidification was greatest in the low-alkalinity lakes of the southwestern Adirondacks, an area with little geological ability to neutralize acidic deposition and receives the highest annual average rainfall in the region. The authors estimate that approximately 80% of the target population lakes with present-day measured pH = or < 5.2 and 30-45% of lakes with pH between 5.2 and 6.0 have undergone large declines in pH and ANC, and concomitant increases in Al(sub m). Estimated changes in (DOC) were small and show no consistent pattern in the acidified lakes. The study provides the first statistically based regional evaluation of the extent of lake acidification in the Adirondacks.

  11. ASTER measurement of supraglacial lakes in the Mount Everest region of the Himalaya

    USGS Publications Warehouse

    Wessels, R.L.; Kargel, J.S.; Kieffer, H.H.

    2002-01-01

    We demonstrate an application of Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) images to detect and monitor supraglacial lakes on glaciers in the Mount Everest region in Tibet (Xizang) and Nepal. ASTER offers powerful capabilities to monitor supraglacial lakes in terms of (1) surface area, growth and disappearance (spatial resolution = 15 m), (2) turbidity (15 m resolution), and (3) temperature (90 m resolution). Preliminary results show an overall similarity of supraglacial lakes on three glaciers. Lakes have widely varying turbidity as indicated by color in visible/near-infrared bands 1-3, the largest lakes being bright blue (highly turbid), cold (near 0??C) and hydrautically connected with other lakes and supraglacial streams, while small lakes are mostly dark blue (relatively clear water), warmer (>4??C), and appear hydrautically isolated. High levels of turbidity in supraglacial lakes indicate high rates of meltwater input from streams or erosion of ice cliffs, and thus are an indirect measure relating to the activity and hydraulic integration of the lake with respect to other lakes and streams in the glacier.

  12. Interaction of a fresh water lake and a karstic spring via a syncline fold.

    PubMed

    Rezaei, Abolfazl; Zare, Mohammad; Raeisi, Ezzatollah; Ghanbari, Reza Namdar

    2013-03-01

    Kaftar Lake is a high-altitude fresh water lake located in High Zagros, south of Iran. Despite the high annual evaporation to precipitation ratio in the area, lake water electrical conductivity is usually lower than 1000 µS/cm, this may be due to high seepage from the floor of the lake. Therefore, the hypothesis of possible underground connections between Namdan Basin, where the lake is located, and the surrounding basins with lower elevation (Aspas and Dehbid Basins) was investigated. Hydrogeology, hydrochemistry, and stable isotopes data of the lake and surrounding basins along with the lake water balance study were applied to test the hypothesis. Results indicate that Kaftar Lake has no connection with Aspas Basin in south, but it is hydraulically connected to Dehbid Basin. In Dehbid Basin, "Ghasr_e_Yaghoob spring" (average discharge ≅1200 L/s) emerges from a small outcrop (about 0.8 km(2) ) of Daryan limestone Formation, where this outcrop is much smaller than the required recharge area for such average discharge rate. The study shows that this spring is recharged by Kaftar Lake and Namdan Basin aquifer, through Daryan Formation of Gandboee Syncline located to the northern part of the lake. PMID:22880946

  13. Habitat suitability for brook trout (Salvelinus fontinalis) reproduction in Adirondack Lakes

    NASA Astrophysics Data System (ADS)

    Schofield, Carl L.

    1993-04-01

    The relationships between habitat characteristics and reproductive status of Adirondack brook trout populations were examined utilizing the Adirondack Lake Survey Corporation data base, which includes physical, chemical, and biological data for 1469 lakes. The only variables strongly related to brook trout natural reproduction were indices of groundwater influence on surface water chemistry, specifically silica and sodium concentrations. This finding supports the hypothesis that lake spawning populations of brook trout are strongly dependent on groundwater seepage for successful reproduction. Spawning habitat in small headwater lakes impounded by beaver activity may be degraded as a result of siltation of nearshore zones and diminished groundwater seepage. Adirondack lakes situated in thick-till basins receive proportionally greater groundwater input than thin-till lake types and thick-till lakes also had the highest proportion of self-sustaining brook trout populations. Acidification is most pronounced in thin-till basins, which also exhibited a low frequency of self-sustaining brook trout populations. Although brook trout fisheries may be maintained in acidic lakes by liming and stocking, the establishment of self-sustaining brook trout populations is not a likely outcome of these management practices. Additionally, there appears to be limited potential for restoration of lake spawning brook trout populations in currently acidic, fishless lakes should acidic inputs decline as a result of reductions in acid-forming emissions.

  14. Zooplankton Successions in Neighboring Lakes with Contrasting Impacts of Amphibian and Fish Predators

    NASA Astrophysics Data System (ADS)

    Schabetsberger, Robert; Grill, Susanne; Hauser, Gabriele; Wukits, Petra

    2006-06-01

    Two pairs of neighboring subalpine lakes located in the Northern Calcareous Alps of Austria were investigated. Each pair comprised a deeper lake containing European minnows (Phoxinus phoxinus ), and a corresponding shallower lake harboring Alpine newts (Triturus alpestris ) as top predators. Plankton successions within fish and amphibian lakes differed markedly from each other. Throughout the year rotifers numerically dominated within the minnow lakes, while pigmented copepods (Genera Heterocope, Acanthodiaptomus , Arctodiaptomus , Mixodiaptomus ) and Daphnia were prominent in the amphibian lakes, at least early during the ice-free period. We argue that size-selective predation by minnows was the ultimate reason for this predominance of smaller zooplankton. While one of the minnow lakes was characterized by a succession of spatially and temporally segregated rotifer species, the other minnow lake permitted the development of populations of small-sized Bosmina and Ceriodaphnia during summer, probably due to the existence of a strong oxycline allowing zooplankton crustaceans to avoid predation from shore-based shoals of minnows. Once trout were introduced into this lake, minnows were visibly reduced in abundance. Bosmina and Ceriodaphnia disappeared and Daphnia together with a predacious copepod (Heterocope ) emerged either from egg banks or arrived from nearby source populations. We argue that the crustacean communities within the fishless lakes were adapted to the comparatively weak predation rates of Alpine newts.

  15. Microbiology of Lonar Lake and other soda lakes

    PubMed Central

    Paul Antony, Chakkiath; Kumaresan, Deepak; Hunger, Sindy; Drake, Harold L; Murrell, J Colin; Shouche, Yogesh S

    2013-01-01

    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. PMID:23178675

  16. Lake trout rehabilitation in Lake Erie: a case history

    USGS Publications Warehouse

    Cornelius, Floyd C.; Muth, Kenneth M.; Kenyon, Roger

    1995-01-01

    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.

  17. 3D mapping and simulation of Geneva Lake environmental data

    NASA Astrophysics Data System (ADS)

    Villard, Roch; Maignan, Michel; Kanevski, Mikhail; Rapin, Francois; Klein, Audrey

    2010-05-01

    several depths. Applying all data comprehensive analysis both in space and in time was performed. The evolution of the distribution of environmental parameters and their difference in space between two periods and also several times series were studied. Furthermore with the analysis of temporal measurements depending on spatial coordinates (x, y, z) the trends, periodicity, and seasonal variation or cycles were evaluated. First results demonstrate no global warming in such environment. However certain currents and their evolution in the lake were identified. Then, we can see the movement of cold and hot waters in the lake during time and in space. A main question posed by ecologists is: is there any global warming of the lake? According to the results based on date 1954-1980, no global warming either of the "Small Lake" (Geneva) or the whole lake was put into evidence. However the temperatures of the different parts of the lake vary from one year to another year with significant differences of warming, respectively cooling of different areas and at different depths. The graphical representations of time series of temperature at one location for different depths show clearly the annual rhythm and also other frequencies (11 years). The historical well known "cold years" are well identified. At some years, one can observe an inversion of temperature when the cold water in the depth comes upwards to the surface. Spatial patterns are also found for the nitrate content in water. The future developments deal with multivariate analysis and simulations of environmental and pollution data in the lake.

  18. Comparison of surface water chemistry and weathering effects of two lake basins in the Changtang Nature Reserve, China.

    PubMed

    Wang, Rui; Liu, Zhaofei; Jiang, Liguang; Yao, Zhijun; Wang, Junbo; Ju, Jianting

    2016-03-01

    The geochemistry of natural waters in the Changtang Nature Reserve, northern Tibet, can help us understand the geology of catchments, and provide additional insight in surface processes that influence water chemistry such as rock weathering on the Qinghai-Tibet Plateau. However, severe natural conditions are responsible for a lack of scientific data for this area. This study represents the first investigation of the chemical composition of surface waters and weathering effects in two lake basins in the reserve (Lake Dogaicoring Qiangco and Lake Longwei Co). The results indicate that total dissolved solids (TDS) in the two lakes are significantly higher than in other gauged lakes on the Qinghai-Tibet Plateau, reaching 20-40g/L, and that TDS of the tectonic lake (Lake Dogaicoring Qiangco) is significantly higher than that of the barrier lake (Lake Longwei Co). Na(+) and Cl(-) are the dominant ions in the lake waters as well as in the glacier-fed lake inflows, with chemical compositions mainly affected by halite weathering. In contrast, ion contents of inflowing rivers fed by nearby runoff are lower and concentrations of dominant ions are not significant. Evaporite, silicate, and carbonate weathering has relatively equal effects on these rivers. Due to their limited scope, small streams near the lakes are less affected by carbonate than by silicate weathering. PMID:26969064

  19. Quantifying groundwater dependence of a sub-polar lake cluster in Finland using an isotope mass balance approach

    NASA Astrophysics Data System (ADS)

    Isokangas, E.; Rozanski, K.; Rossi, P. M.; Ronkanen, A.-K.; Kløve, B.

    2015-03-01

    A stable isotope study of 67 kettle lakes and ponds situated on an esker aquifer (90 km2) in northern Finland was carried out to determine the role and extent of groundwater inflow in groundwater-dependent lakes. Distinct seasonal fluctuations in the δ18O and δ2H values of lakes are the result of seasonal ice cover prohibiting evaporation during the winter. An iterative isotope mass balance approach was used to calculate the inflow-to-evaporation ratios (ITOT/E) of all 67 lakes during the summer of 2013 when the isotopic compositions of the lakes were approaching a steady-state. The balance calculations were carried out independently for 2H and 18O data. Since evaporation rates were derived independently of any mass balance considerations, it was possible to determine the total inflow (ITOT) and mean turnover time (MTT) of the lakes. Furthermore, the groundwater seepage rates to all studied lakes were calculated. A quantitative measure was introduced for the dependence of a lake on groundwater (G index) that is defined as the percentage contribution of groundwater inflow to the total inflow of water to the given lake. The G index values of the lakes studied ranged from ca. 39 to 98%, revealing generally large groundwater dependency among the studied lakes. This study shows the effectiveness of applying an isotope mass balance approach to quantify the groundwater reliance of lakes situated in a relatively small area with similar climatic conditions.

  20. High resolution paleoenvironment reconstruction for Lake Khanka since the last glacial maximum

    NASA Astrophysics Data System (ADS)

    Liu, Yanguang; Chen, Jiaojie; Ge, Shulan; Li, Chaoxin

    2014-05-01

    A novel sedimentary sequence is presented based on sediment core in the Khanka Lake (XKH1, collected form the small Khanka Lake) by using of paleomagnetic stratigraphy, grain size and organic geochemical data. The sedimentary history of XKH1 is distinctly retrieved to 24 ka BP by comparing with the geomagnetic inclination lows recorded in XKH1 and Lake Biwa. Multi-proxies paleoenvironmental reconstruction for Lake Khanka since the last glacial maximum (LGM) by grain size, total organic carbon (TOC), magnetic susceptibility (MS), and color reflectance. During 24 and 19.5 ka BP, Lake Khanka experienced low lake level and cooling-wet climate approved by the decreasing mean grain size, high sediment brightness and MS values, and low TOC value. The relatively high sand fraction and slightly variation also indicate a low lake condition between 19.5 and 15 ka BP. High TOC content and marked variation in others proxies represent a peat swamp deposition environment during 19 and 16 ka BP, which may associated with lower precipitation and probably modulated by the restrained Asian summer monsoon. From 16 to 15 ka BP, the lake condition change to cold-dry and the sediment has lower content of TOC and coarser grain size. During the deglaciation, together with global temperature rising, the effective precipitation increase around Lake Khanka, result in rising of lake level. The fluctuating characteristics of the environment sensitive grain content are corresponding well to the Oldest Dryas/Bolling-Allerod/Younger Dryas periods. Since 10.6 ka BP, the lake level slightly declining under warm climate because a successive sand bar developed between the small Khanka Lake and the main water area.

  1. Simulation of the effects of time and size at stocking on PCB accumulation in lake trout

    USGS Publications Warehouse

    Madenjian, Charles P.; Carpenter, Stephen R.

    1993-01-01

    Manipulations of size at stocking and timing of stocking have already been used to improve survival of stocked salmonines in the Great Lakes. It should be possible to stock salmonines into the Great Lakes in a way that reduces the rate of polychlorinated biphenyl (PCB) accumulation in these fishes. An individual-based model (IBM) was used to investigate the effects of size at stocking and timing of stocking on PCB accumulation by lake trout Salvelinus namaycush in Lake Michigan. The individual-based feature of the model allowed lake trout individuals to encounter prey fish individuals and then consume sufficiently small prey fish. The IBM accurately accounted for the variation in PCB concentrations observed within the Lake Michigan lake trout population. Results of the IBM simulations revealed that increasing the average size at stocking from 110 to 160 mm total length led to an increase in the average PCB concentration in the stocked cohort at age 5, after the fish had spent 4 years in the lake, from 2.33 to 2.65 mg/kg; the percentage of lake trout in the cohort at the end of the simulated time period with PCB concentration of 2 mg/kg or more increased from 62% to 79%. Thus, PCB contamination was reduced when the simulated size at stocking was smallest. An overall stocking strategy for lake trout into Lake Michigan should weigh this advantage regarding PCB contamination against the poor survival of lake trout that may occur if the trout are stocked at too small a size.

  2. Potential strategies for recovery of lake whitefish and lake herring stocks in eastern Lake Erie

    USGS Publications Warehouse

    Oldenburg, K.; Stapanian, M.A.; Ryan, P.A.; Holm, E.

    2007-01-01

    Lake Erie sustained large populations of ciscoes (Salmonidae: Coregoninae) 120 years ago. By the end of the 19th century, abundance of lake whitefish (Coregonus clupeaformis) had declined drastically. By 1925, the lake herring (a cisco) population (Coregonus artedii) had collapsed, although a limited lake herring fishery persisted in the eastern basin until the 1950s. In the latter part of the 20th century, the composition of the fish community changed as oligotrophication proceeded. Since 1984, a limited recovery of lake whitefish has occurred, however no recovery was evident for lake herring. Current ecological conditions in Lake Erie probably will not inhibit recovery of the coregonine species. Recovery of walleye (Sander vitreus) and efforts to rehabilitate the native lake trout (Salvelinus namaycush) in Lake Erie will probably assist recovery because these piscivores reduce populations of alewife (Alosa psuedoharengus) and rainbow smelt (Osmerus mordax), which inhibit reproductive success of coregonines. Although there are considerable spawning substrates available to coregonine species in eastern Lake Erie, eggs and fry would probably be displaced by storm surge from most shoals. Site selection for stocking or seeding of eggs should consider the reproductive life cycle of the stocked fish and suitable protection from storm events. Two potential sites in the eastern basin have been identified. Recommended management procedures, including commercial fisheries, are suggested to assist in recovery. Stocking in the eastern basin of Lake Erie is recommended for both species, as conditions are adequate and the native spawning population in the eastern basin is low. For lake herring, consideration should be given to match ecophenotypes as much as possible. Egg seeding is recommended. Egg seeding of lake whitefish should be considered initially, with fingerling or yearling stocking suggested if unsuccessful. Spawning stocks of whitefish in the western basin of Lake

  3. Predicting Maximum Lake Depth from Surrounding Topography

    EPA Science Inventory

    Lake volume aids understanding of the physical and ecological dynamics of lakes, yet is often not readily available. The data needed to calculate lake volume (i.e. bathymetry) are usually only collected on a lake by lake basis and are difficult to obtain across broad regions. ...

  4. Lake Mead--clear and vital

    USGS Publications Warehouse

    Wessells, Stephen M.; Rosen, Michael

    2013-01-01

    Lake Mead – Clear and Vital” is a 13 minute documentary relating the crucial role of science in maintaining high water quality in Lake Mead. The program was produced coincident with release of the Lakes Mead and Mohave Circular a USGS publication covering past and on-going research in the lakes and tributaries of the Lake Mead National Recreation Area.

  5. Lake Erie...Take a Bow.

    ERIC Educational Resources Information Center

    Canning, Maureen; Dunlevy, Margie

    This elementary school teaching unit was developed as a part of a series of teaching units that deal with Lake Erie. This unit was developed to enable children to: (1) identify the Great Lakes and pick out Lake Erie on a map; (2) demonstrate knowledge of Lake Erie's origin and geography; (3) list some uses of Lake Erie; and (4) give examples of…

  6. Fecundity of hatchery lake trout in Lake Ontario

    USGS Publications Warehouse

    Fitzsimons, John D.; O'Gorman, Robert

    1996-01-01

    Fecundity (egg number) was determined from 26 stocked (617-800 mm, total length) lake trout (Salvelinus namaycush) collected in western Lake Ontario during September 1992. Previous to this study, fecundity was evaluated only once in Lake Ontario using native stocks in 1927. The following relationships between fecundity and total length (TL) and weight (W) were obtained. Fecundity = -12,492 + 25.87 TL(mm) and Fecundity = -1,010 + 1,307 W(kg). Relative fecundity (number of eggs per kg of body weight) was unrelated to body weight and averaged 1,592 eggs kg-1. Fecundity of contemporary lake trout based on length was significantly lower than that of historic native stocks, but was similar to contemporary stocked lake trout in Lake Superior.

  7. Climate-driven changes in riverine inputs affecting the stoichiometry of Earth's largest lake

    NASA Astrophysics Data System (ADS)

    Sterner, R.; Small, G. E.

    2014-12-01

    Lake Superior, Earth's largest lake by area, has seen a steady increase in nitrate levels over the past century, while phosphorus remains exceedingly low, resulting in an increasingly imbalanced stoichiometry. Although its ratio of watershed area:lake area is relatively small, rivers emptying into Lake Superior could be important drivers of long-term changes in lake stoichiometry. To better assess how the Lake Superior watershed affects its stoichiometry, we examined the chemistry of two of its largest tributaries, the Saint Louis River and the Nipigon River, at their confluences with Lake Superior. Both of these rivers have high dissolved organic carbon (DOC) but low nitrate (NO3) concentrations relative to the lake. Using simple mixing models, we found these nearshore confluences to create sinks of lake NO3 as a result of relatively high rates of denitrification. Climate change is altering the amounts and patterns of delivery of materials from land to lakes and we also examined the plume from a June, 2012 100-year flood in the Saint Louis River. Three days after this historic rain event, we found elevated chlorophyll levels throughout the plume, up to 5-fold higher than in the open lake. Combining our samples with satellite imagery, we conservatively estimate that this plume contained 598,000 kg of phosphorus in dissolved and particulate form, or 40% of the average annual P input to the lake. If storm events such as this occur with increasing frequency as predicted in climate change scenarios, the lake's productivity may increase and stoichiometry could become more balanced, through greater P input and increased N retention due to sedimentation and denitrification.

  8. Developing inorganic carbon-based radiocarbon chronologies for Holocene lake sediments in arid NW China

    NASA Astrophysics Data System (ADS)

    Zhang, Jiawu; Ma, Xueyang; Qiang, Mingrui; Huang, Xiaozhong; Li, Shuang; Guo, Xiaoyan; Henderson, Andrew C. G.; Holmes, Jonathan A.; Chen, Fahu

    2016-07-01

    Inorganic carbonates are often used to establish radiocarbon (14C) chronologies for lake sediments when terrestrial plant remains (TPR) are rare or when bulk organic matter is insufficient for dating, a problem that is common for many lakes in arid regions. However, the reservoir effect (RE), as well as old carbon contributed from the lakes catchment make it difficult to establish reliable chronologies. Here we present a systematic study of inorganic 14C ages of two lake-sediment sequences, one from a small-enclosed saline lake - Lake Gahai in Qaidam Basin, and the other from a large freshwater lake - Lake Bosten in Xinjiang. Modern dissolved inorganic carbon (DIC) of the lakes, paleo-lake sediments exposed in the catchment, and mollusk shells in core sediments from Lake Gahai were dated to assess the RE and the contribution of pre-aged carbon to the old ages in the cores. We propose a statistical regression to assess more than one RE for the 14C carbonate ages within our sedimentary sequences. Old radiocarbon ages contributed by detrital carbonates were assessed by comparing the ages of mollusk shells with those of carbonates at the same sediment depths. We established the RE of the authigenic component and assessed detrital old carbon contributions to our two sites, and this was used to correct the 14C ages. Based on this approach, we developed age models for both cores, and tested them using 210Pb ages in both cores and TPR-based 14C-ages recovered from Lake Bosten. We further tested our age models by comparing carbonate-based oxygen isotope (δ18O) records from both lakes to an independently-dated regional speleothem δ18O record. Our results suggest if sedimentary sequences are densely dated and the RE and the contribution of old carbon from detrital carbonates can be ascertained, robust chronological frameworks based on carbonate-based 14C determinations can be established.

  9. Association between winter precipitation and water level fluctuations in the Great Lakes and atmospheric circulation patterns

    SciTech Connect

    Rodionov, S.N.

    1994-11-01

    Atmospheric precipitation in the Great Lakes basin, as a major mediating variable between atmospheric circulation and lake levels, is analyzed relative to both. The effect of cumulative winter precipitation on lake levels varies from lake to lake and depends on both the state of the lake level itself and air temperature. For periods with a quasi-stable temperature regime, the correlation coefficient between winter precipitation and changes in lake levels from November to spring months reaches 0.8. An analysis of composite maps of mean winter 700-mb heights and sea level pressure for the years with well-above and well-below normal precipitation in the lower Great Lakes basin (Lakes Michigan-Huron, St. Clair, Erie, and Ontario) has shown that changes in precipitation are associated with the wave train structure in the lower and midtroposphere that is similar to the Pacific/North American (PNA) teleconnection pattern. During the positive phase of the PNA-like pattern, when the upper-atmospheric ridge/trough system is amplified, cyclones passing over the Great Lakes basin are frequently of Alberta (Canada) origin and carry relatively small amounts of precipitation. As a result, lake levels tend to decline. On the contrary, during the negative phase of the pattern when the atmospheric circulation is more zonal, the main storm track is oriented from the southwest to the northeast and cyclones bring enough precipitation to induce a rise in lake levels. The effect of the position of the upper-atmospheric trough over the east coast of North America on the precipitation regime in the Great Lakes basin is also demonstrated. 42 refs., 11 figs., 4 tabs.

  10. Hydrological and landscape controls on the chemical response of lakes in northern Wisconsin to environmental pressures

    NASA Astrophysics Data System (ADS)

    Casson, N. J.; Sebestyen, S. D.; Kolka, R. K.; Stanley, E. H.

    2014-12-01

    The response of lake chemistry to environmental stressors such as climate change or acid deposition is mediated by the landscape setting of the lake and the surrounding catchment. Hydrological delivery of solutes through surface runoff or groundwater can buffer against the impacts of anthropogenic change. Since there is often variability in these processes across a region, lakes will not react uniformly to these regional scale pressures. Understanding the landscape-level controls on lake chemistry will help determine lake sensitivity to future environmental change. Our objective is to classify seepage lakes in terms of their hydrology and landscape characteristics to explain variability in lake chemistry in northern Wisconsin. We present data from synoptic surveys of more than 90 seepage lakes across the Chequamegon-Nicolet National Forest of northern Wisconsin that ranged in size from 1.6 to 75 ha, conducted in the summers of 2013 and 2014. Seasonal groundwater sampling and precipitation chemistry are used to construct mixing models to quantify hydrological inputs to the lakes. The catchments of these lakes are difficult to delineate, as they are relatively small and at times have significant groundwater input, so we calculate landscape characteristics for fixed buffer zones around the lake. The chemical composition of the lakes varies widely across the landscape; for instance, dissolved organic carbon concentrations range from 2.9 to 39 mg/L, and calcium concentrations range from 0.4 to 5.3 mg/L. To explain this variability, we explore interactions between landscape features and hydrology and suggest a framework by which to classify the chemical composition of these lakes.

  11. Miniature Cryogenic Valves for a Titan Lake Sampling System

    NASA Technical Reports Server (NTRS)

    Sherrit, Stewart; Zimmerman, Wayne; Takano, Nobuyuki; Avellar, Louisa

    2014-01-01

    The Cassini mission has revealed Titan to be one of the most Earthlike worlds in the Solar System complete with many of the same surface features including lakes, river channels, basins, and dunes. But unlike Earth, the materials and fluids on Titan are composed of cryogenic organic compounds with lakes of liquid methane and ethane. One of the potential mission concepts to explore Titan is to land a floating platform on one of the Titan Lakes and determine the local lake chemistry. In order to accomplish this within the expected mass volume and power budgets there is a need to pursue the development for a low power lightweight cryogenic valves which can be used along with vacuum lines to sample lake liquid and to distribute to various instruments aboard the Lander. To meet this need we have initiated the development of low power cryogenic valves and actuators based on a single crystal piezoelectric flextensional stacks produced by TRS Ceramics Inc. Since the origin of such high electromechanical properties of Relaxor-PT single crystals is due to the polarization rotation effect, (i.e., intrinsic contributions), the strain per volt decrease at cryogenic temperatures is much lower than in standard Lead Zirconate Titanate (PZT) ceramics. This makes them promising candidates for cryogenic actuators with regards to the stroke for a given voltage. This paper will present our Titan Lake Sampling and Sample Handling system design and the development of small cryogenic piezoelectric valves developed to meet the system specifications.

  12. Change Detection of Lake Aba Samuel in Ethiopia

    NASA Astrophysics Data System (ADS)

    Kaczynski, R.; Rylko, A.

    2016-06-01

    Old topographic map published in 1975 elaborated from aerial photographs taken in 1972, Landsat TM data acquired in May 1986 and Landsat ETM+ from June 2002 have been used to assess the changes of the lake Aba Samuel in Ethiopia. First map of the lake has been done in the framework of UNDP project running in 1988-90 in the Ethiopian Mapping Authority. The second classification map has been done as M.Sc. thesis in the MUT in 2015. Supervised classification methods with the use of ground truth data have been used for elaboration of the Landsat TM data. From the year 1972 up to 1986 the area of the lake has decreased by 23%. From 1986 up to 2002 the area of the lake has decreased by 20%. Therefore, after 30 years the lake was smaller by 43%. This have had very bad influence on the lives of the local population. From other recent data in the period from 2002-2015 the lake has practically disappeared and now it is only a small part of the river Akaki. ENVI 5.2 and ERDAS IMAGINE 9.2 have been used for Radiometric Calibration, Quick Atmospheric Correction (QUAC) and supervised classification of Landsat ETM+ data. The Optimum Index Factor shows the best combination of Landsat TM and ETM+ bands for color composite as 1,4,5 in the color filters: B, G, R for the signature development. Methodology and final maps are enclosed in the paper.

  13. Water quality of Somerville Lake, south-central Texas

    USGS Publications Warehouse

    McPherson, Emma; Mendieta, H.B.

    1983-01-01

    Lake Somerville in south-central Texas has excellent water for municipal, industrial, and agricultural use. The total dissolved solids of the water averaged 220 milligrams per liter during a study from 1975-80. This shallow lake has a mean depth of 14 feet. The average annual inflow and discharge is greater than the volume of the lake. These two factors, along with wind action and the cooling of surface water during both summer and winter keep the lake well mixed and aerated. Even in summer the dissolved oxygen concentrations at the bottom of the lake usually were in excess of 50 percent of saturation. Dissolved iron concentrations are less than 50 micrograms per liter and dissolved manganese concentrations are under 40 micrograms per liter. These small concentrations are largely attributable to year-round oxygenated water. Homogeneous or near homogeneous concentrations of total phosphorus and inorganic nitrogen can occur at any time of the year throughout the lake. Dissolved chloride concentrations averaged 43 milligrams per liter and dissolved sulfate concentrations averaged 63 milligrams per liter. The total hardness of the water averaged about 110 milligrams per liter, placing it in the moderately hard classfication. (USGS)

  14. Federal Great Lakes fishery research objectives, priorities, and projects

    USGS Publications Warehouse

    Tait, Howard D.

    1973-01-01

    Fishery productivity of the Great Lakes has declined drastically since settlement of the area. Premium quality fishes of the Great Lakes such as whitefish, lake trout, and walleyes have been replaced by less desired species. This change is attributed to selective overfishing, pollution, and the extreme instability of fish populations. Sea lamprey predation is still a vexing problem but progress is being made in controlling this parasite. The federal fishery research program with headquarters in Ann Arbor, Michigan, has the objective of providing baseline information, needed in resource use decisions, about the fishes of the Great Lakes. Studies of the habitat requirements of fish are high priority. The program includes fish population assessments, studies of the effects of mercury and other contaminants on fish, thermal effects studies, and general investigation of the impact of engineering projects on Great Lakes fisheries. The work is closely coordinated with state and Canadian agencies through the Great Lakes Fishery Commission. Four small research vessels and four field stations are utilized with a staff of 90 and an annual budget of about $1.5 million.

  15. The geomorphological map of Lake Tana basin (Ethiopia)

    NASA Astrophysics Data System (ADS)

    Poppe, Ludwin; Nyssen, Jan; Poesen, Jean; Admasu, Teshager; Dessie, Mekete; Adgo, Enyew; Deckers, Jozef; Frankl, Amaury

    2013-04-01

    The geomorphological map of Lake Tana basin (15 077 km², Nile basin, Ethiopia) was prepared from fieldwork data, maps and satellite data that were processed in a GIS system. It contains four major components: (i) hydrography, (ii) morphology and -metry, (iii) materials and (iv) processes. The scale is 1:500 000. The geomorphological setting of the basin consists of lavas that erupted from fissures or (shield) volcanoes during the Tertiary and Quaternary eras, were uplifted and ultimately sculpted by (mainly water) erosion. Lake Tana emerged by the combination of a lava barrier blocking the Blue Nile to the south and by epirogenetic subsidence. Since the time that the lake reached its maximum extent, extensive floodplains were created, river valleys have been filled with sediment and higher laying topography has been eroded. Today, the lake plays a lesser role in landscape formation because of a decreased lake extent (3041 km² now) as compared to the ancient maximum (6602 km²). Dominant processes today are merely fluvial and denudative. Recent (1886-2010) changes in lake coast are small with exception of the delta of the major feeding river, Gilgel Abay, which increased disproportionally the last 15 years. This indicates a large input of sediment which is mainly due to rivers flowing through Quaternary lavas. The recent sediment input increase is most probably related to human induced land-use changes.

  16. Inferred effects of lake acidification on Daphnia galeata mendotae

    SciTech Connect

    Keller, W. ); Yan, N.D.; Holtze, K.E. ); Pitblado, J.R. )

    1990-08-01

    Large numbers of Canadian Shield lakes have been acidified by the atmospheric deposition of anthropogenic sulfur. Biological damage attributable to acidification occurs at all levels of aquatic food webs; however, documentation of this damage has largely been confined to areas near large point sources of air pollutants, to small numbers of study lakes, or to experimentally acidified lakes. Demonstrations of widespread biological effects of acidification have been greatly hampered by the general absence of observations of the occurrence or abundance of important, ubiquitous species in large numbers of lakes ranging widely in acidity, coupled with laboratory determinations of lethal acid thresholds for these species. In consequence, it has been necessary to estimate rather than to document the regional extent of biological damage in North America. In this report the authors couple determination of the lethal acid threshold of Daphnia galeata mendotae Birge, a large, ubiquitous, planktonic crustacean, with results of extensive lake surveys, to examine if the acidification of lakes in Ontario has resulted in widespread losses of this important member of the zooplankton.

  17. Lake Garda, Italy

    NASA Technical Reports Server (NTRS)

    2000-01-01

    This ASTER image was acquired on July 29, 2000 and covers an area of 30 by 57 km in northern Italy. Lake Garda was formed by glaciers during the last Ice Age, and is Italy's largest lake. Lago di Garda lies in the provinces of Verona, Brescia, and Trento, and is 51 kilometers (32 miles) long and from 3 to 18 kilometers (2 to 11 miles) wide. The Sarca is its chief affluent, and the lake is drained southward by the Mincio, which discharges into the Po River. Many villas are situated on its shores. On the peninsula of Sirmione, at the southern end of the lake, are the ruins of a Roman villa and a castle of the Scaligers, an Italian family of the 16th century. The RIGHT image has the land area masked out, and a harsh stretch was applied to the lake values to display variations in sediment load. Also visible are hundreds of boats and their wakes, criss-crossing the lake.

    The image is centered at 45.6 degrees north latitude, 10.6 degrees east longitude.

    Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) is one of five Earth-observing instruments launched December 18, 1999, on NASA's Terra satellite. The instrument was built by Japan's Ministry of International Trade and Industry. A joint U.S./Japan science team is responsible for validation and calibration of the instrument and the data products. Dr. Anne Kahle at NASA's Jet Propulsion Laboratory, Pasadena, Calif., is the U.S. Science team leader; Moshe Pniel of JPL is the project manager. ASTER is the only high resolution imaging sensor on Terra. The primary goal of the ASTER mission is to obtain high-resolution image data in 14 channels over the entire land surface, as well as black and white stereo images. With revisit time of between 4 and 16 days, ASTER will provide the capability for repeat coverage of changing areas on Earth's surface.

    The broad spectral coverage and high spectral resolution of ASTER will provide scientists in numerous disciplines with critical information for

  18. Future volcanic lake research: revealing secrets from poorly studied lakes

    NASA Astrophysics Data System (ADS)

    Rouwet, D.; Tassi, F.; Mora-Amador, R. A.

    2012-04-01

    Volcanic lake research boosted after the 1986 Lake Nyos lethal gas burst, a limnic rather than volcanic event. This led to the formation of the IAVCEI-Commission on Volcanic Lakes, which grew out into a multi-disciplinary scientific community since the 1990's. At Lake Nyos, a degassing pipe is functional since 2001, and two additional pipes were added in 2011, aimed to prevent further limnic eruption events. There are between 150 and 200 volcanic lakes on Earth. Some acidic crater lakes topping active magmatic-hydrothermal systems are monitored continuously or discontinuously. Such detailed studies have shown their usefulness in volcanic surveillance (e.g. Ruapehu, Yugama-Kusatsu-Shiran, Poás). Others are "Nyos-type" lakes, with possible gas accumulation in bottom waters and thus potentially hazardous. "Nyos-type" lakes tend to remain stably stratified in tropical and sub-tropical climates (meromictic), leading to long-term gas build-up and thus higher potential risk. In temperate climates, such lakes tend to turn over in winter (monomictic), and thus liberating its gas charge yearly. We line out research strategies for the different types of lakes. We believe a complementary, multi-disciplinary approach (geochemistry, geophysics, limnology, biology, statistics, etc.) will lead to new insights and ideas, which can be the base for future following-up and monitoring. After 25 years of pioneering studies on rather few lakes, the scientific community should be challenged to study the many poorly studied volcanic lakes, in order to better constrain the related hazard, based on probabilistic approaches.

  19. Genetic diversity of Diporeia in the Great Lakes: comparison of Lake Superior to the other Great Lakes

    EPA Science Inventory

    Abundances of Diporeia have dropped drastically in the Great Lakes, except in Lake Superior, where data suggest that population counts actually have risen. Various ecological, environmental, or geographic hypotheses have been proposed to explain the greater abundance of Lake Supe...

  20. 12. POWERHOUSE INTERIOR SHOWING EXCITER No. 2 SMALL PELTONDOBLE IMPULSE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    12. POWERHOUSE INTERIOR SHOWING EXCITER No. 2 SMALL PELTON-DOBLE IMPULSE WHEEL, HAND-CONTROLLED GATE VALVE, AND NOZZLE. VIEW TO SOUTHWEST. - Rush Creek Hydroelectric System, Powerhouse Exciters, Rush Creek, June Lake, Mono County, CA