Sediment cores let us look back in time at the contaminant history of a watershed. Learn about what lake and reservoir sediment cores tell us about trends in metals, organochlorine pesticides, polycyclic aromatic hydrocarbons, and other sediment-related contaminants.
Water-quality trends can provide an assessment of the effectiveness of regulatory actions aimed at improving water quality, a warning of water-quality degradation, and an improved understanding of how human activities affect water quality.
Sediment cores—long tubes of mud—are collected from a lake or reservoir and sliced into thin intervals. Each slice represents an interval of time. By analyzing the sediments in each slice for the contaminants of interest, changes in the occurrence of contaminants and their use in the watershed can be reconstructed. The approximate date corresponding to deposition of the sediment in each slice is determined by analysis of radionuclides (cesium-137 and lead-210).
USGS studies of reconstructed trends in metals and hydrophobic organic contaminants have shed light on the effectiveness of restrictions on the use of leaded gasoline, DDT, and PCBs, and the effectiveness of the Clean Air Act in reducing concentrations of some heavy metals. The studies also have identified some contaminants, like polycyclic aromatic hydrocarbons (PAHs), whose concentrations are increasing in urban areas, spurring efforts to identify the source or sources of these upward trends.
Find out more about coal-tar-based sealcoat, a potent source of PAHs to lake and streambed sediment, and related environmental health issues.
NATIONAL SUMMARIES
- Increased mercury fallout near major U.S. cities (Environ. Pollution, 2012)
- Coal-tar sealcoat largest PAH source to U.S. lakes (Sci. Total Env., 2010)
- PAH in coal tar sealcoat a national problem (Env. Sci. & Tech., 2009)
- National-scale trends in organics (Env. Sci. & Tech., 2005)
- National-scale trends in metals (Env. Tox. & Chem., 2006) associated Data Report
- Methods and age dating of cores (USGS SIR 2004-5184)
- Urban trends in PAHs (Env. Sci. & Tech., 2000)
- Rates of decrease in DDT and PCBs (Env. Sci. & Tech., 1998)
- Trends in organochlorine compounds (Env. Sci. & Tech., 1997)
TOPICAL FINDINGS
- Evaluating mercury and 210Pb atmospheric fallout and focusing to lakes (Env. Sci. & Tech., 2009)
- Effects of Hurricanes Katrina and Rita on Lake Pontchartrain sediments (Env. Sci. & Tech., 2006)
- Parking lot sealcoat: an urban source of PAHs (Env. Sci. & Tech., 2005) associated fact sheet, data report
- Chemical response to urbanization, New England, USA (Chalmers et al. 2007)
- Contaminant trends in the Mississippi River Basin (Van Metre and Horowitz 2013)
- Reservoir cores versus stream suspended sediments (Env. Sci. & Tech., 2004)
- Monitoring suspended sediment chemistry (Arch. Env. Contam. & Tox., 2003)
- Metal diagenesis in reservoir cores (J. Paleolimnology, 2000)
LOCAL RESULTS
- PAHs decline after ban on coal-tar sealcoat, Austin, TX (Env. Sci. Technol., 2014)
- Chemical response of particle-associated contaminants in aquatic sediments to urbanization in New England (Contam. Hydro., 2007)
- Lead and zinc in greater Atlanta, Georgia (Env. Sci. & Tech., 2000)
- Trends in White Rock Lake, Texas (J. Paleolimnology, 1997)
Read about additional science related to sediment-associated contaminants and water-quality trends by following the links to web pages below.
Learn more about water quality trends as recorded in sediment cores at the publications below.
Trends in hydrophobic organic contaminants in urban and reference lake sediments across the United States, 1970-2001
Occurrence, trends, and sources in particle-associated contaminants in selected streams and lakes in Fort Worth, Texas
A chronicle of organochlorine contamination in Clear Creek, Galveston and Harris Counties, Texas, 1960-2002, as recorded in sediment cores
Effects of urbanization and long-term rainfall on the occurrence of organic compounds and trace elements in reservoir sediment cores, streambed sediment, and fish tissue from the Santa Ana River basin, California, 1998
Llano Grande Lake bottom sediments; a chronicle of water-quality changes in the Arroyo Colorado, South Texas, 1989-2001
Occurrence of Polychlorinated Biphenyls (PCBs) on Suspended Sediment in the Donna Canal, Hidalgo County, Texas, 1999-2001
Identification of water-quality trends using sediment cores from Dillon Reservoir, Summit County, Colorado
The urban environmental gradient: Anthropogenic influences on the spatial and temporal distributions of lead and zinc in sediments
Urban sprawl leaves its PAH signature
Reconstructing historical changes in the environmental health of watersheds by using sediment cores from lakes and reservoirs in Salt Lake Valley, Utah
Geochemical effects of rapid sedimentation in aquatic systems: Minimal diagenesis and the preservation of historical metal signatures
Bottom sediments of Lorence Creek Lake, San Antonio, Texas, reflect contaminant trends in an urbanizing watershed
Town Lake bottom sediments : a chronicle of water quality changes in Austin, Texas, 1960-98
Sediment cores let us look back in time at the contaminant history of a watershed. Learn about what lake and reservoir sediment cores tell us about trends in metals, organochlorine pesticides, polycyclic aromatic hydrocarbons, and other sediment-related contaminants.
Water-quality trends can provide an assessment of the effectiveness of regulatory actions aimed at improving water quality, a warning of water-quality degradation, and an improved understanding of how human activities affect water quality.
Sediment cores—long tubes of mud—are collected from a lake or reservoir and sliced into thin intervals. Each slice represents an interval of time. By analyzing the sediments in each slice for the contaminants of interest, changes in the occurrence of contaminants and their use in the watershed can be reconstructed. The approximate date corresponding to deposition of the sediment in each slice is determined by analysis of radionuclides (cesium-137 and lead-210).
USGS studies of reconstructed trends in metals and hydrophobic organic contaminants have shed light on the effectiveness of restrictions on the use of leaded gasoline, DDT, and PCBs, and the effectiveness of the Clean Air Act in reducing concentrations of some heavy metals. The studies also have identified some contaminants, like polycyclic aromatic hydrocarbons (PAHs), whose concentrations are increasing in urban areas, spurring efforts to identify the source or sources of these upward trends.
Find out more about coal-tar-based sealcoat, a potent source of PAHs to lake and streambed sediment, and related environmental health issues.
NATIONAL SUMMARIES
- Increased mercury fallout near major U.S. cities (Environ. Pollution, 2012)
- Coal-tar sealcoat largest PAH source to U.S. lakes (Sci. Total Env., 2010)
- PAH in coal tar sealcoat a national problem (Env. Sci. & Tech., 2009)
- National-scale trends in organics (Env. Sci. & Tech., 2005)
- National-scale trends in metals (Env. Tox. & Chem., 2006) associated Data Report
- Methods and age dating of cores (USGS SIR 2004-5184)
- Urban trends in PAHs (Env. Sci. & Tech., 2000)
- Rates of decrease in DDT and PCBs (Env. Sci. & Tech., 1998)
- Trends in organochlorine compounds (Env. Sci. & Tech., 1997)
TOPICAL FINDINGS
- Evaluating mercury and 210Pb atmospheric fallout and focusing to lakes (Env. Sci. & Tech., 2009)
- Effects of Hurricanes Katrina and Rita on Lake Pontchartrain sediments (Env. Sci. & Tech., 2006)
- Parking lot sealcoat: an urban source of PAHs (Env. Sci. & Tech., 2005) associated fact sheet, data report
- Chemical response to urbanization, New England, USA (Chalmers et al. 2007)
- Contaminant trends in the Mississippi River Basin (Van Metre and Horowitz 2013)
- Reservoir cores versus stream suspended sediments (Env. Sci. & Tech., 2004)
- Monitoring suspended sediment chemistry (Arch. Env. Contam. & Tox., 2003)
- Metal diagenesis in reservoir cores (J. Paleolimnology, 2000)
LOCAL RESULTS
- PAHs decline after ban on coal-tar sealcoat, Austin, TX (Env. Sci. Technol., 2014)
- Chemical response of particle-associated contaminants in aquatic sediments to urbanization in New England (Contam. Hydro., 2007)
- Lead and zinc in greater Atlanta, Georgia (Env. Sci. & Tech., 2000)
- Trends in White Rock Lake, Texas (J. Paleolimnology, 1997)
Read about additional science related to sediment-associated contaminants and water-quality trends by following the links to web pages below.
Learn more about water quality trends as recorded in sediment cores at the publications below.