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PECONIC ESTUARY PROGRAM: CHEMICAL CONTAMINANT DISTRIBUTIONS IN PECONIC ESTUARY SEDIMENTS
Citation:
LeBlanc, L. PECONIC ESTUARY PROGRAM: CHEMICAL CONTAMINANT DISTRIBUTIONS IN PECONIC ESTUARY SEDIMENTS. U.S. Environmental Protection Agency, Washington, D.C.
Description:
The study design uses sediment quality as an indicator of overall ecosystem health. The utility of using sediment quality as an integrative indicator of ecosystem health underlies the application of the Sediment Quality Triad method and similar assessment approaches. Toxic contaminants were analyzed in field-collected sediments, providing data for comparison with contaminant concentrations that have been shown to adversely affect benthic organisms. These data were supplemented with a review of some historical data that were relevant to these study objectives. In order to provide some measurement of sediment biological conditions, a Sediment Profile Imaging (SIP) survey was conducted in the Spring following the Fall 1994 sediment chemistry survey. Twelve stations were sampled for surface sediments; one of the stations could not be accessed for the SPI survey. The 12 sediment chemistry stations were selected from among the 16 stations established for the Peconic Estuary Program's Sediment Flux and Toxics Monitoring Programs. Target contaminants and analytical methods for the sediment characterization followed the analytical strategy developed by the National Oceanic and Atmospheric Administration for its National Status and Trends Program. The success of this analytical approach, which was also adopted by the EPA for its Environmental Monitoring and Assessment Program, has been demonstrated through the achievements of the Status and Trends Program and in NEP studies for the Delaware Estuary Program and Massachusetts Bays Program. The following organic contaminants were targeted at ultra-trace (parts per billion) detection limits: priority pollutant and alkylated polynuclear aromatic hydrocarbons (PAHs), polychloronated biphenyls (PCBs) targeted as congeners, and organochlorine pesticides. Priority pollutant metals were also targeted at detection limits lower than those achievable using conventional methods. Sediment grain size and total organic carbon content were measured as auxiliary measurements to examine their influence on contaminant distributions. Specific data quality objectives and assessments were established in a Quality Assurance/Project Plan developed for this study, providing measures of data quality based on accuracy, precision, and traceability. The results of this study lead us to conclude that toxic chemical contaminants do not pose considerable risk to biological resources on an estuary-wide basis. Although difficult to quantify terms such as "considerable risk", we can conservatively conclude that toxic contaminants do not pose as great a risk to resources as the stress resulting from excessive nutrient and organic carbon loading. We must, however, note that one of the problems associated with high organic carbon concentrations found in this study is the favorable accumulation of predominantly background contaminants to concentrations that could adversely affect biological resources on a local basis. The key distinction in these statements are the aspect of spatial scales implied by "estuary-wide" versus "local." The factors that will determine the extent to which resources may be affected by localized accumulations of contaminations include the response of potentially affected biological communities to the stresses of the organic carbon loading. Based on the suite of assessment tools employed in this study, there did not appear to be any stations for which poor habitat quality could be attributed to toxic chemical contamination. However, there remains the potential for localized problems associated with toxic chemicals that may accumulate in fine-grained, organic-rich muds that are found in many of the sheltered embayments, particularly in the western portion of the estuary.