Is arsenic in streambed sediments harmful to aquatic life?
Elevated arsenic concentrations in streambed sediments may have adverse effects on organisms that live in the sediments or on the fish and wildlife that may feed on such organisms. A regulatory guideline for arsenic in streambed sediments currently does not exist for the United States. However, a guideline from the Canadian Council of Ministers of the Environment (1999) can be used for discussion. This guideline, called the Probable Effect Level (PEL), is the concentration above which adverse effects are expected to occur frequently. The PEL for arsenic is 17 micrograms per gram (µg/g), dry weight, for bulk (unsieved) sediments. Streambed-sediment samples have been collected in the Cook Inlet Basin as part of the National Uranium Resource Evaluation (NURE) Hydrogeochemical and Streambed Sediment Reconnaissance program as well as for the NAWQA program and studies with the National Park Service (Fig. 4). Samples collected are sieved to fine-grained fractions prior to analysis (Fig. 5). F
