Showing papers by "Christer Hogstrand published in 2004"

Aquatic Health and Exposure Pathways of Trace Elements

Abstract: Historical mine adits, mill tailings, and waste-rock dumps in the Boulder River watershed, Montana, are sources of trace elements to streams. Biological studies were undertaken to characterize the aquatic health of fisheries and the exposure pathway of these trace elements in watershed streams. Aquatic health was assessed by measuring the survivability of hatchery fish, measuring the biomass and density of resident fish, and documenting the physiology of fish exposed to trace elements. Pathways of exposure were assessed by determining trace-element concentrations in water, sediment, biofilm, invertebrates, and fish tissues and by defining relations among these components. Instream survivability experiments at sites that had no resident trout and were downstream from inactive mines indicated that elevated concentrations of filtered cadmium, copper, and zinc were associated with increased mortality as well as hypertrophy (swelling), degeneration (dying), and necrosis of epithelial cells in gills of hatchery trout. In lower Cataract Creek, a site farther downstream, the health of resident trout was impaired. A decrease in the number of trout per acre indicated population-level effects; and increased metallothionein, increased products of lipid peroxidation, and elevated concentrations of trace elements in fish tissues indicated individual-level effects. The concentrations of cadmium, copper, and zinc in water and those of arsenic, cadmium, copper, lead, and zinc in sediment in some watershed streams were sufficient to affect aquatic life. Concentrations of arsenic, copper, cadmium, lead, and zinc in invertebrates from lower Cataract Creek (63 339, 59, 34, and 2,410 μg/g (dry weight, respectively)) were greater than concentrations in invertebrates from the Clark Fork River watershed, Montana (19, 174, 2.3, 15, and 648, respectively), where these trace elements were associated with reduced survival, growth, and health of cutthroat trout fed diets composed of the Clark Fork River invertebrates. The concentrations of all trace elements, except cadmium, in colloids and biofilm were significantly correlated, which suggests that transfer of trace elements associated with colloids to biological portions of biofilm is an important pathway in which trace elements associated with abiotic components are first presented to biotic components. The interrelationship of trace elements accumulating in the abiotic and biotic components sampled suggests that copper, cadmium, and zinc concentrations increased in fish tissues as a result of direct exposure from water and sediment contact and indirect exposure through the food chain. Apparently, trace elements have made contact with biota through these two pathways and have thereby compromised the overall aquatic health of the Boulder River watershed.