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At least 19 recordsLinked to original sources
PubMed2001

Floodplain lakes as sinks for sediment-associated contaminants--a new source of proxy hydrological data?

Lake and reservoir sediments often contain valuable records of sediment yield history and sediment-associated nutrient and contaminant transport spanning timescales from decades to millennia. Nevertheless, there have been few attempts to evaluate floodplain lakes as a source of proxy hydrological data for reconstructing short-term trends in sediment-associated nutrient and contaminant transport. Results from an analysis of floodplain lake sediment cores suggested good preservation of the 137Cs record, which provided an absolute dating control. Changes in the concentration of sediment-associated heavy metals and phosphorus were observed downcore and the analysis of mineral magnetic properties and particle size were used to identify the influx of sediment associated with high magnitude, low frequency flood events. Although floodplain lake-sediments only preserve a partial record, they may provide a valuable source of proxy hydrological data for reconstructing trends in sediment and sediment-associated contaminant transport where long-term sediment monitoring programmes are not available.

Cesium Radioisotopes↗
PubMed2004

Spatial and temporal trends in surface water and sediment contamination in the Laurentian Great Lakes.

Data from recent sediment and surface water surveys have been collated and mapped to illustrate the spatial distribution of contaminants across the entire Great Lakes basin. Information from historical surveys, together with data from surface water monitoring programs in three major connecting channels, has also been collated in order to evaluate temporal trends. In general, Lakes Superior and Michigan exhibited the lowest levels of sediment contamination while Lake Ontario had the highest. Contaminants such as gamma-HCH (lindane) and dieldrin were ubiquitous in surface waters across the entire basin, which was indicative of atmospheric sources. The distribution of other compounds including hexachlorobenzene, octachlorostyrene and mirex indicated the presence of local sources within the watersheds of the connecting channels. Surficial sediment contamination was found to have decreased markedly since the late 1960s and 1970s. Similarly, surface water contamination decreased over the period 1986-1997 with concentrations of dieldrin, hexachlorobenzene, octachlorostyrene and mirex reduced by over 50%. However, the spatial distributions of both sediment and surface water contamination indicate that further effort is warranted in reducing local sources of contaminants, particularly in Lake Ontario.

Air Pollutants↗
PubMed2002

A mass balance model describing multiyear fate of organochlorine compounds in a high Arctic lake.

Data collected over a 3-year study of a high arctic watershed and lake are used to understand the fate of organochlorine compounds (OCs) and form the basis of a mass balance contaminant fate model. The model uses the fugacity/aquivalence approach to describe OC dynamics between air, stream inflows and outflow, the water column, and surficial sediments. The steady-state model results indicate that stream inflows contributed from 96 to >99% of total chemical loadings, but 57-98% of total loadings were lost from the lake via the outlet, the percentage of which is controlled by the hydrologic regime of the high arctic lake. Conversely, only 0.4-3.4% of loadings were retained within the sediments due to the high export rate, minimal scavenging from the water column and low organic carbon fraction of the sediments. Using the unsteady-state model, which includes year-round processes, degradation was estimated to account for losses of 7-32% for the more persistent OCs and 42-50% for the less persistent OCs (alpha-HCH, gamma-HCH, and endosulfan I). If loadings were eliminated, water column concentrations would decline with half-lives <1 year for less persistent OCs and 1-2 years for the more persistent OCs, whereas the half-lives for OCs in sediment are 8-25 years.

Arctic Regions↗
PubMed2004

Spatial and temporal patterns in mercury contamination in sediments of the Laurentian Great Lakes.

Data from recent sediment surveys have been collated and mapped in order to determine the spatial distribution of mercury in sediments across the entire Great Lakes basin. Information from historical surveys has also been collated in order to evaluate temporal trends. Lake Huron (2002) exhibited the lowest mercury concentrations (lakewide average concentration, 0.043 microg/g); Lakes Michigan (1994-1996) and Superior (2000) also exhibited relatively low levels (lakewide averages of 0.088 and 0.078 microg/g, respectively). The western basin of Lake Erie (1997-1998, 0.402 microg/g) and Lake Ontario (0.586 microg/g) exhibited the highest levels. Sources of mercury contamination in Lakes Erie and Ontario are primarily attributed to loadings from historical sources, including chlor-alkali production in the Detroit, St. Clair, and Niagara Rivers. The spatial distributions of mercury in sediments of Lakes Huron and Superior suggest that natural geochemical factors are an influence. Surficial sediment mercury contamination was found to have decreased markedly since the late 1960s and 1970s. Decreases in lakewide average sediment concentrations of mercury over this time period ranged from approximately 25% for Lake Ontario to 80% for Lake Huron.

Data Collection↗
PubMed2004

Causes of variability in pesticide and PCB concentrations in air near the Great Lakes.

Data through 2001 from the Integrated Atmospheric Deposition Network (IADN) were used to investigate the causes of variability in gas-phase polychlorinated biphenyl (PCB) and pesticide concentrations measured near Lakes Michigan, Erie, and Superior. A multiple linear regression model that incorporates temperature and time was used explain the variability in the concentrations. Our approach used autocorrelation analyses of the residuals to help us determine the effectiveness of the regression. Autocorrelation plots forthe in-use pesticide lindane indicated that an agricultural application cycle was also present in the regression residual data at all sites. The addition of parameters for this effect to the regression equation accounted for, on average, 16% more of the variability in the data. Similar analyses forthe in-use pesticide endosulfan did not show an agricultural application effect. The banned compounds DDT and chlordane showed that temperature and time correctly accounted for the variability in the atmospheric concentrations of these compounds at all sites. In contrast to the other compounds, PCBs and hexachlorobenzene showed strong residual autocorrelation patterns near Lake Michigan of an unknown origin.

Agriculture↗
PubMedDate not supplied

[Seasonal dynamics of the population structure of Sphaerostomum globiporum (Trematoda: Opecoelidae) maritae in Ladoga Lake].

Data on the seasonal dynamics of population structure is obtained for the first time for the Trematode species Sphaerostomum globiporum from roach Rutilus rutilus (L) in Ladoga Lake, which situates in the northern limit of the distribution range of this species. The parasites infest the host in October and leave it from the end of July to the beginning of August. The maximum of the magnitude of the Trematode population falls on spring, and the minimum is observed in summer. In August and September roach is free of the parasites. It is established that the period of maturing occupies 10 months for S. globiporum from roach in Ladoga Lake. The prereproductive period takes 5 months and comes to the end in February. The reproductive period occupies 5 months too. Although these two periods of the parasite's life cycle do not separated from each other clearly, an overlapping of two generations was not observed, unlike the case of more southern water bodies.

Animals↗
PubMed2001

Statistical analysis of hyperspectral data from two Swedish lakes.

CASI data has been collected from two lakes in Sweden. In this paper, some statistical properties of CASI spectral data have been discussed. Principal component analysis is used for assessing the dimensionality of the data and the principal components were used for making chlorophyll maps. The quality of the reconstruction of the spectra from the principal components was demonstrated. Examples of the accuracy of the radiative transfer code 6S in atmospheric correction applications have been given. Furthermore, the widths and positions of the spectral bands based on the studied dataset were proposed for chlorophyll mapping. Robustness aspects of regression models have been discussed. Algorithms derived from one lake have been used to map water quality parameters in another lake. Algorithms based on principal components, as well as algorithms based on image bands, have been used.

Algorithms↗
PubMed2005

Development of an integrated analysis procedure for three-ways layout field surveys data in lakes.

Lake water quality systems are extremely complex and every lake is characterized by many complicated interactions between biological, chemical and physical variables. One of the most important tasks of lake mechanism analysis is to examine the relations among important water quality variables and to describe such complicated relationships quantitatively, simply and practically. Lake Biwa was chosen as a target lake, where a periodic water quality investigation was conducted every month from 1979 at 50 sampling sites. The objective of this study is to establish an application procedure of three-ways layout data and to present a vision including its practical result, expecting that this vision may also provide a direction for further research. The results showed that (1) cluster analysis following the three-ways layout ANOVA method is very effective in presenting water quality variation, (2) correlation analysis of water quality indices in each effect of parameters and their interaction between two items verifies that their relationships in parameters are different due to different mechanisms. (3) An integrated analysis procedure was derived, potentially describing those data in forms which convey their important characteristics and reveal their significant relationship. The same approach of this analysis procedure could be possibly applied for other water quality indices in other lakes.

Data Collection↗
PubMed1992

Critical loads for Finnish lakes: comparison of three steady-state models.

Three simple steady-state water-chemistry models are used to calculate critical loads of sulfur for lakes in Finland. Because of the high concentrations of organic matter in Finnish lakes, the influence of organic anions on the calculation of critical loads has been given special attention. The first two methods are well known ion-balance methods which have been used in many previous lake-acidification studies. The third method, developed for this study, includes the numerical solution of equilibrium equations for organic anions, inorganic carbon species and inorganic monomeric aluminum. The original pH and aluminum concentration of the lakes are estimated with this model, and a method to estimate the original acid neutralizing capacity (ANC) by simulating a Gran-titration is also tested on the lake data. Uncertainty in the predictions is estimated by varying the most critical model parameters.

Journal Article↗
PubMed2005

History of Inuit community exposure to lead, cadmium, and mercury in sewage lake sediments.

Exposure to lead, cadmium, and mercury is known to be high in many arctic Inuit communities. These metals are emitted from industrial and urban sources, are distributed by long-range atmospheric transport to remote regions, and are found in Inuit country foods. Current community exposure to these metals can be measured in food, but feces and urine are also excellent indicators of total exposure from ingestion and inhalation because a high percentage of each metal is excreted. Bulk domestic sewage or its residue in a waste treatment system is a good substitute measure. Domestic waste treatment systems that accumulate metals in sediment provide an accurate historical record of changes in ingestion or inhalation. We collected sediment cores from an arctic lake used for facultative domestic sewage treatment to identify the history of community exposure to Pb, Cd, and Hg. Cores were dated and fluxes were measured for each metal. A nearby lake was sampled to measure combined background and atmospheric inputs, which were subtracted from sewage lake data. Pb, Cd, and Hg inputs from sewage grew rapidly after the onset of waste disposal in the late 1960s and exceeded the rate of population growth in the contributing community from 1970 to 1990. The daily per-person Pb input in 1990 (720,000 ng/person per day) exceeded the tolerable daily intake level. The Cd input (48,000 ng/person per day) and Hg input (19,000 ng/person per day) were below the respective TDI levels at the time.

Cadmium↗
PubMed2001

A hyperspectral model for interpretation of passive optical remote sensing data from turbid lakes.

A hyperspectral model was developed for the interpretation of remote sensing data collected above inland waters. Specific absorption and scattering coefficients proposed by other authors were not suitable for modelling of the irradiance reflectance in 12 studied lakes. Therefore, special studies were carried out to estimate absorption and scattering coefficients as well as backscattering probability of suspended matter in turbid waters. AC-9 and Li-1800UW results were used for these purposes. The algorithms obtained were used to improve the model, which was then tested in forward and inverse modes.

Absorption↗
PubMed2001

[Cluster analysis study on the marshland of Schistosoma Japonicum using satellite TM image data in Peng Lake, Jiangxi province].

OBJECTIVE: To create a category land cover map of the marshland region of Schistosoma Japonicum using satellite TM data. METHODS: TM satellite images from Peng Lake of Jiangxi province were applied to the Cluster analysis. Then the resulting clusters were identified and reclassified by undertaking site visits. RESULTS: Eight land cover classes were generated, including Carexspp Zone that was the snail habitat place. CONCLUSION: Cluster analysis, which is a technique for the interpretation of remotely sensed imagery, could contribute to the study on the distribution of snail habitats and become a new tool for the epidemiological ecology study.

Animals↗
PubMed2002

A general approach to transform a lake model for one radionuclide (radiocesium) to another (radiostrontium) and critical model tests using data for four Ural lakes contaminated by the fallout from the Kyshtym accident in 1957.

This paper presents results of a model test carried out within the framework of the COMETES project (EU). The aim of the work was to change the structure of the MOIRA lake model for radiocesium so that it can be applied more generally for, in principle, all types of radionuclides and heavy metals. This general lake model is used within the MOIRA decision support system (DSS; MOIRA and COMETES are acronyms for EU-projects). The model is based on a set of differential equations and a specific modelling structure. It incorporates all important fluxes to, from and within lakes in a general manner. Yet the model is driven by a minimum of variables accessible from standard maps and monitoring programs. The model can be separated into two parts, a general part with equations applicable for all types of water pollutants and a substance-specific part. This model has previously been validated for 137Cs from many lakes covering a wide domain and yielded excellent predictive power. The alterations discussed in this work are meant to be general and radiostrontium is used as a typical element. Radiostrontium is known to be more mobile than radiocesium and all abiotic parts of the model handling fixation and mobility have been altered. The new model for 90Sr has been critically tested using data from four lakes heavily contaminated with 90Sr from the Kyshtym accident in the Southern Urals, Russia, using empirical data from a period from 1958 to 1995 for 90Sr in fish (here goldfish), water and sediments.

Cesium Radioisotopes↗