Temporal trends of trace element and organic contaminants in the conterminous coastal and estuarine United States, 1965-1993

Organic pesticides first found wide usage after 1942 when DDT was patented as a pesticide. Both organic and trace element contaminant discharges increased with time until the 1970s when comprehensive environmental legislation was enacted. Data from four large scale monitoring programs were assembled and then evaluated to determine whether or not chemical environmental contamination was decreasing in the U.S. coastal and estuarine waters. The monitoring programs whose data were used were a national Environmental Protection Agency (EPA) monitoring project (1965-1972), the EPA funded "Mussel Watch" Program (1976-1978), the National Oceanic and Atmospheric Administration's Mussel Watch Project (1986-1993 data used), and the State of California's Mussel Watch Program (1977-1992 data used).; It was possible to search for long-term trends in environmental concentrations of six trace elements (silver, cadmium, copper, nickel, lead, and zinc) and for trends in six organic contaminants (PCBs, DDT and its metabolites, and dieldrin). Chlordane and tributyltin were also evaluated across the NOAA and the second EPA program, by using archived EPA samples. Initially, trends were sought by preparing plots of contaminant concentrations over time. Data across the monitoring programs were evaluated using the Kendall-{dollar}tau{dollar} statistic. Data were also grouped into two time periods: all data predating the current national Mussel Watch Project of NOAA and all data resulting since the initiation of NOAA's program in 1986. Trends were then sought with the use of the Wilcoxon ranked sum statistic.; Decreasing trends were found for PAHs, PCBs, DDT, chlordane, and TBT when data from the NOAA-MWP and the EPA2-MWP archived samples were reviewed. When organic contaminant data from the four large scale monitoring projects were evaluated, decreasing contaminant trends were found for PAHs (pyrene and phenanthrene), PCBs, DDT and its metabolites, and dieldrin.; When the four large scale monitoring projects' data were evaluated for trace elements, decreasing trends were found for lead, cadmium, and silver. For copper, decreasing and increasing trends, on a site by site basis, were approximately equal except for California where at eight sites increasing trends are indicated. No trends were found for nickel and zinc concentrations.