Water-quality assessment of the Albemarle-Pamlico Basin, North Carolina and Virginia; chemical analyses of organic compounds and inorganic constituents in streambed sediment, 1992-93

Abstract

In 1991, the U.S. Geological Survey began fullscale implementation of the National Water-Quality Assessment (NAWQA) program. Long-term goals of the NAWQA program are to describe the status and trends in the quality of a large, representative part of the Nation's surface-water and ground-water resources and to describe the primary natural and human factors that affect these resources. One of the first assessment phases of the NAWQA program is to examine the occurrence and distribution of organic and inorganic constituents in streambed sediment. Streambed sediment was collected at 22 stations in the Albemarle-Pamlico drainage basin that drains into the Albemarle and Pamlico Sounds, the second largest estuarine system in the United States. Streambed-sediment samples were analyzed for 35 organochlorine and 63 semi volatile compounds; 44 major, minor, and trace elements; and forms of organic carbon. INTRODUCTION In 1991, the U.S. Geological Survey (USGS) began full-scale implementation of the National Water-Quality Assessment (NAWQA) program. Longterm goals of the NAWQA program are to describe the status and trends in the quality of a large, representative part of the Nation's surface-water and groundwater resources and to describe the primary natural and human factors that affect these resources. In order to meet these goals, the program will collect data on surface-water and ground-water quality and ecological information that will be useful to water-resource managers at the National, State, and local levels (Leahy and others, 1990). When fully implemented, the NAWQA program will total 60 study units incorporating about 60 to 70 percent of the Nation's water use and population served by public water supply. The AlbemarlePamlico drainage basin was among the first 20 NAWQA study units selected for study. The initial phase of the Albemarle-Pamlico NAWQA study began in 1991 and is expected to continue through 1996. The surface-water component of the NAWQA program combines organic and inorganic analyses of water, sediment, and biota to describe the sources, transport, and fate of these constituents. The chemistry of streambed sediment is important because many inorganic and organic constituents can be sorbed to streambed sediments, thereby serving as a reservoir or sink. Concentrations of many inorganic and organic constituents can be several orders of magnitude higher in streambed sediment than in the overlying streamwater (Horowitz, 1985). Inorganic and organic constituents sorbed to streambed sediment also can be transported downstream during high streamflows. Purpose and Scope This report includes descriptions of the sampling design, sample collection and preparation, chemical analysis, and analytical data for streambed sediment collected in the Albemarle-Pamlico study unit at 15 stations from October through December 1992 and at