Geochemical data for water, streambed sediment, and fish tissue from the Sierra Nevada Mercury Impairment Project, 2011–12

This report presents geochemical data for surface water, streambed sediment, and fish tissue samples collected during low-flow conditions in 20 to 24 Sierra Nevada streams during 2011 and 2012. The dataset is part of a larger study designed to assess the factors that control mercury concentrations in fish tissue and to develop a model that predicts mercury concentration in the tissue of selected fish species in Sierra Nevada streams. The ranges of total mercury concentration observed in different matrices of water and sediment from 24 locations were as follows: below detection to 0.86 nanograms per liter in filtered water, below detection to 4.06 nanograms per liter in suspended particulates (greater than 0.3 micrometer in diameter), 1.1 to 381 nanograms per gram in bed sediment less than 2 millimeters, and 28.1 to 1,410 nanograms per gram in bed sediment less than 0.063 millimeters. The ratio of monomethyl mercury to total mercury ranged as follows: below detection to 19.2 percent in filtered water, below detection to 51.7 percent in suspended particles (greater than 0.3 micrometer), and below detection to 7.6 percent in streambed sediment less than 2 millimeters. Fish from 3 species collected at 20 locations had the following range in total mercury concentration (all concentrations wet weight): 10 to 292 nanograms per gram in rainbow trout (293 fish, 19 locations), 13 to 386 nanograms per gram in brown trout (33 fish, 10 locations), and 159 nanograms per gram in hardhead (1 fish). Concentrations of selenium in fish (wet weight) ranged from 60 to 420 nanograms per gram in rainbow trout (66 fish, 19 locations) and from 180 to 240 nanograms per gram in brown trout (6 fish, 2 locations).