title: Spatial and temporal trends in surface water and sediment contamination in the Laurentian Great Lakes.
abstract: 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.
authors.affiliation: Environment Canada, 867 Lakeshore Road, Burlington, Ontario, Canada L7R 4A6. chris.marvin@ec.gc.ca
authors.forename: Chris
authors.initials: C
authors.lastname: Marvin
authors.forename: Scott
authors.initials: S
authors.lastname: Painter
authors.forename: Donald
authors.initials: D
authors.lastname: Williams
authors.forename: Violeta
authors.initials: V
authors.lastname: Richardson
authors.forename: Ronald
authors.initials: R
authors.lastname: Rossmann
authors.forename: Patricia
authors.initials: P
authors.lastname: Van Hoof
mesh_terms: D000393:Air Pollutants / Q000032:analysis; D004026:Dieldrin / Q000032:analysis; D004784:Environmental Monitoring / Q000379:methods*; D019015:Geologic Sediments / Q000032:analysis*; D006114:Great Lakes Region; D006581:Hexachlorobenzene / Q000032:analysis; D001556:Hexachlorocyclohexane / Q000032:analysis; D008628:Mercury / Q000032:analysis; D019216:Metals, Heavy / Q000032:analysis; D008917:Mirex / Q000032:analysis; D011078:Polychlorinated Biphenyls / Q000032:analysis; D013343:Styrenes / Q000032:analysis; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D000393:Air Pollutants; D019216:Metals, Heavy; D013343:Styrenes; D014874:Water Pollutants, Chemical; C014138:octachlorostyrene; D006581:Hexachlorobenzene; D001556:Hexachlorocyclohexane; D011078:Polychlorinated Biphenyls; D008628:Mercury; D004026:Dieldrin; D008917:Mirex