Metal exposure in a benthic macroinvertebrate, Hydropsyche californica, related to mine drainage in the Sacramento River

A biomonitoring technique was employed to complement studies of metal trans port in the upper Sacramento River affected by acid mine drainage. Metals ( Al, Cd, Cu, Fe, Hg, Pb, and Zn) were determined in a resident invertebrate, Hydropsyche californica (Insecta: Trichoptera), and streambed sediments (< 62 mu m) to assess metal contamination within a 111-km section of the rive r downstream of the mining area. Metals in H. californica also were interpr eted to be broadly indicative of metal exposure in fish. Total Hg was deter mined in the whole body of the insect, whereas Al, Cd, Cu, Fe, Pb, and Zn w ere additionally separated into operationally defined cytosolic (used as an indicator of exposure to bioavailable metal) and particulate fractions. To tal concentrations of Cd, Cu, Hg, Pb, and Zn in sediments were consistent w ith documented upstream sources of acid mine drainage. Metal distribution p atterns in H. californica and sediments were generally consistent for Cd, C u, and Pb but inconsistent for Hg and Zn. Concentrations in H. californica indicated that bioavailable Cd, Cu, Pb, and Zn was transported at least 120 km downstream of the mine sources. Zinc in H. californica was elevated, bu t unlike sediments, did not decrease downstream. Mercury in H. californica was not elevated.