Water Quality, and Metal and Metalloid Concentrations in Water, Sediment, and Fish Tissues from Innoko National Wildlife Refuge, Alaska, 1995-1997

摘要

This study was conducted by U.S. Fish and Wildlife Service biologists from 1995-1997. The study goals were to determine selected metal and metalloid concentrations in water, sediment, and fish tissues at sites within and upstream of Innoko National Wildlife Refuge; determine the uniqueness of chum and coho salmon populations of Illinois and California creeks by comparison of their genetic characteristics with those from other locations; and determine the histologic baseline conditions of juvenile silver salmon in Illinois Creek. This report focuses on the first objective, determinations of water quality variables, and metals concentrations in water, sediment, and fish. Stream water, sediment, and fish samples were collected from 26 sites: 20 sites on Innoko National Wildlife Refuge and 6 in the upper Little Mud River drainage, in areas associated with the Illinois Creek heap-leach gold mine. Mineral deposits of many types have been located around the Refuge and placer mining for gold has occurred in many of the major and minor drainages that enter the Refuge. Extraction of mineral resources may affect fish and wildlife resources and their habitats within the Refuge. The circumneutral pH values measured at Innoko Refuge and the upper Little Mud River drainage are typical of interior Alaska streams. Measures of dissolved solids in water, conductivity, hardness and alkalinity show that stream water in Innoko Refuge and the upper Little Mud River are within the range typical of surface waters in interior Alaska. Rain had obvious effects on discharge and water quality in Refuge streams. Turbidity was significantly greater at sites sampled after a rain event in 1996, and values for pH, conductivity, hardness and alkalinity were greater at sites sampled before the rain event. Water quality is not a consistent predictor of metals concentrations, as demonstrated by the changing relationships between metal concentrations and water quality variables associated with the rain event of 1996. Surface waters in Innoko Refuge and the upper Little Mud River were relatively uncontaminated by metals. For example, no dissolved metals concentrations exceeded the Environmental Protection Agency s Water Quality Criteria (WQC). Most metals concentrations were within the ranges of metals measured at Kanuti, Koyukuk, Nowitna, and Selawik National Wildlife Refuges from various dates within the 1980's and 1990's. Although no samples exceeded the EPA chronic WQC for arsenic (0.15 mg/L), mean total arsenic at the Iditarod River for 1997 and at both sample sites on Illinois Creek (1996 only) (0.0057 mg/L, 0.014 mg/L, and 0.017 mg/L, respectively) exceeded the drinking water standard for the State of Alaska of 0.005 mg/L.Mean dissolved iron concentrations exceeded the chronic WQC of 1.0 mg/L and the Canadian guideline for the protection of freshwater aquatic life of 0.3 mg/L total iron in all Innoko River drainage waters measured except Tolstoi, Illinois, and California creeks. Concentrations of total iron frequently exceeded those that cause mortality in rainbow trout eggs.