Photos of the Long Island Sound

Research & Monitoring

Status and Trends: LISS Environmental Indicators

WQ Historical/Legacy


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No Discharge Area

Areas designated as "no discharge zones" prohibit the release of sewage from any vessels. Sewage can damage habitats and be a major source of pathogens to the coastal environment. This map shows the areas in Long Island Sound designated as No Discharge Zones. View Indicator


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Lead Concentrations in Sediment by Basin

This map shows the concentration of the heavy metal lead within the seafloor sediments throughout Long Island Sound. View Indicator


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Heavy Metals in Sediment

Sediment cores were sampled near Norwalk Harbor to determine the historic trends of toxic contamination in the seafloor sediment of the Sound. The cores give a record of metal contamination from the pre-colonial period to the post-industrial era. View Indicator


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Sediment Delta 13C

δ13C is an isotope of carbon used as a proxy for hypoxia in this indicator, enabling the creation of a 1000-year historical record of bottom water conditions in Long Island Sound. View Indicator


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Sediment Organic Carbon Concentration Chart

Sediment Organic Carbon Concentration

Measurements of organic carbon concentration in sediment cores can be used to reconstruct a historical record of organic carbon in Long Island Sound. View Indicator


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Increases in Population and Sewage

Clostridium perfringens, a bacterial spore found in sediments, is an indicator of sewage inputs and can be used to create a historical record of the magnitude of sewage input to the Sound. View Indicator


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Sediment Delta 15N

Delta 15N is a nitrogen isotope whose relative abundance in benthic sediment is used to determine the contribution of wastewater and sewage to total nitrogen. View Indicator

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