The occurrence and distribution of trace elements and of wood-pulp-related compounds in the sediments of Lake Roosevelt and the upstream reach sampler of the Columbia River were studied in 1992. In addition, an analysis of benthic invertebrate community structure and tests of sediment toxicity were conducted. Concentrations of trace elements were elevated, relative to background reference sites, in samples of bed sediment. Copper, lead, and zinc most often exceeded the sediment-quality guidelines for benthic organisms. In whole-water samples, trace-element concentrations did not exceed criteria for freshwater organisms. These concentrations were relatively small, reflecting the small suspended-sediment concentrations and the large water-diluting capacity of the Columbia River. Elevated concentrations of trace elements in sediments are attributable to the transport of metallurgical waste from a smelter discharging to the Columbia River in Canada. Dioxins and furans were found in Columbia River water, but only a few isomers were detected. A furan isomer common in effluent from pulp and paper mills was found in suspended sediment. Dioxins and furans in the water phase were isolated using solid-phase extraction to concentrate these compounds from large volumes of water. Few of the many other organic compounds associated with wood-pulp waste were detected in the bed sediments of Lake Roosevelt. Benthic invertebrate communities in the Columbia River showed effects from trace elements in bed sediments or from loss of physical habitat. Lethal and sublethal effects were observed in toxicity tests of selected aquatic organisms exposed to bed sediments from the Columbia River near the international boundary.
