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Woods Hole Coastal and Marine Science Center > USGS Studies in Long Island Sound >Research Topics> Contaminants

U.S. Geological Survey Studies in Long Island Sound:
Geology, Contaminants, and Environmental Issues

Contaminants: Distribution, History, Fate, and Effects of Contaminated Sediments

Contaminants are introduced into the Sound from sewage effluent, disposal of dredged material, industrial discharge, urban and agricultural runoff, atmospheric deposition, and combined input from major rivers. In the ocean, many contaminants stick to sediment particles and are deposited on the sea floor. The sediments, and the contaminants associated with them, accumulate on the sea floor over time and provide a record of past events. In addition, contaminant distributions can be used to identify rates and patterns of modern sediment movement. Knowledge of the magnitude of contaminant concentration in sediments is important for regulation of contaminant discharges as well as management of the natural resources throughout the Long Island Sound watershed.

Sediments are composed of small particles of soil, clays, and sand that are carried to the ocean by rivers and wind, or are eroded from rocks. These materials sink to the sea floor and become part of the sedimentary record along with the remains of marine plants and animals that have died. The sediment particles may be composed of many different minerals and organic substances. Some particles, such as clays, iron-oxide minerals, and complex carbon molecules interact chemically with pollutants and hold them in the sediments. Tiny shells from marine organisms can remain intact for thousands of years and can be used to identify past environmental conditions.

Sediment mud, Clostridium perfringens bacteria
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Scanning electron microscopy image that shows Clostridium perfringens bacteria in a matrix of fine sediment particles found in a sediment core sample collected in Long Island Sound.

Contaminants and Population Growth
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Contaminants have entered the Sound from three hundred years of population growth and industrial activity.

Clostridium perfringens

Link to Clostridium perfringens results in USGS Open-File Report 00-304 and in the Journal of Coastal Research.

 

Map of Clostridium concentrations
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Concentration map of the distribution of Clostridium perfringens in Long Island Sound sediments.

Surficial Metal Contamination

Link to Surficial Metal Contamination results in USGS Open-File Report 00-304 and the Journal of Coastal Research.

 

Map of lead concentrations
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The distribution of lead (Pb) concentrations in the surface sediments (0-2cm) of Long Island Sound.

Mercury Enrichment

Link to Mercury results in USGS Open-File Report 00-304 and in the Journal of Coastal Research.

Mercury concentrations in sediment cores
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Mercury concentrations in sediment cores record a history of contamination from population and industrial centers.

Total Organic Carbon

Link to Total Organic Carbon results in USGS Open-File Report 00-304 and the Journal of Coastal Research.

Map of total organic carbon
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Distribution of total organic carbon in the sediments of Long Island Sound. Contours are in weight percent. Block diagrams explain map units.

On-Going and Future Work Link to Publications on Contaminants

 

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Page Last Modified: Tuesday, 09-Dec-2014 14:15:22 EST (GW)