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USE OF SEDIMENT CORES TO ESTABLISH REFERENCE CONDITIONS
Citation:
Boothman, W S. AND J S. Latimer. USE OF SEDIMENT CORES TO ESTABLISH REFERENCE CONDITIONS. Presented at Society of Environmental Toxicology and Chemistry, Salt Lake City, UT, November 16-20, 2002.
Description:
In order to assess the degree to which integrity of waterbodies have been degraded, comparisons are made to "reference" conditions. Finding systems with similar ecological components, but absent the specific stressors of concern, may often be difficult or even impossible. An alternative to designation of reference sites is to establish reference conditions by analysis of sediment cores that are sufficiently long to predate anthropogenic impacts. Statistical analyses of chemical data (e.g., metals, PAHs, organic carbon) from a number of cores from the harbor in New Bedford, MA (USA) were used to determine the depth at which anthropogenic contamination increased significantly above reference concentrations and to characterize the conditions existent prior to the onset of contamination. Similar analysis was applied to an apparently unimpacted reference site nearby (Apponagansett Bay, MA, USA). Comparison of the reference conditions determined in each system and the current conditions at the reference site show that even the reference site has undergone modern alteration, albeit much smaller in magnitude than has occurred in New Bedford, but that historical background conditions in the two estuaries are quite similar. Using lead-210 and pollen dating techniques, the onset of contamination can be related to the historical development of the estuaries. Examples of other applications of the self-referencing approach are given, including assessment of sediments in the navigation channel of the Providence River (Providence, RI, USA) to determine appropriate depths of dredging to reach background.