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A REGIONAL SCALE TOXICITY ASSESSMENT OF SEDIMENT IN THE MID-ATLANTIC AND SOUTHERN ROCKIES, USA
Citation:
Lazorchak, J M., M. Smith, A. T. Herlihy, AND L. E. Herrin. A REGIONAL SCALE TOXICITY ASSESSMENT OF SEDIMENT IN THE MID-ATLANTIC AND SOUTHERN ROCKIES, USA. Presented at Society of Environmental Toxicology and Chemistry, Philadelphia, PA, November 12-14, 1999.
Description:
As part of the Environmental Monitoring and Assessment Program (EMAP), sediment samples were collected to assess toxicity on a regional scale in streams and rivers in the Mid-Atlantic U.S. in 1994, 1997 and 1998, and in the Colorado Rocky Mountains in 1994 and 1995. Sample sites were selected randomly using a probability design so that the results could be inferred for the entire region. Sediments were collected from each site by scooping 11 small samples of surficial sediments within a 150-800 m long sample reach (reach length was proportional to stream width) and composited in a bucket. Samples were then placed in a plastic bag and shipped on ice to Cincinnati and stored at 4-6oC. A 7-day Hyalella azteca (amphipod) lethality and growth method was used to assess the toxicity of all sedment samples. During the spring of 1994 in Mid-Atlantic streams, an estimated 10,700 km of stream length (5.7% of the 188,700 km in the target population) were found to have toxic sediment (survival or growth significantly less than the control). During the summers of 1997 and 1998 in Mid-Atlantic streams and river sediments, an estimated 21,830 km (8.7%) of the 250,500 km of target length were found to be toxic. In the Southern Colorado Rockies, an estimated 422 km (6.4%) of the 6,600 km of target stream length had toxic sediments. These results demonstrate the utility of synoptic probability based surveys to assess regional extent of sediment toxicity/contamination.