Metals concentrations in insect tissues and water from the Panther Creek watershed, Idaho, September 2015

Abstract The purpose of this sampling was to collect matched aquatic insect and water samples to support metals mixture toxicity modeling. This is part of a larger study that included exposing naturally colonized insect communities to metals mixtures in long-term laboratory toxicity tests, field surveys, and modeling (Schmidt and others, 2019). The Panther Creek sampling was conducted to give a field comparison to laboratory exposures of aquatic insect communities to cobalt (Co) plus copper (Cu) mixtures, the results of which were presented as part 4 of Schmidt and others (2019). The water samples from the Panther Creek area were collected to interpret metals concentrations in the tissues of mayflies and caddisflies relative to experimental exposures and to compare to community composition. Samples were collected from sites expected to give a gradient of metals concentrations, ranging from natural background reference sites to concentrations expected to be high enough to produce substantial bioaccumulation of metals. Results The results are presented in a workbook consisting of 6 datasheets which respectively include data on: 1. Summary: includes sampling locations and summarized matched water and tissue samples 2. Water-detailed: Field measurements and analytical results of water sampling 3. Tissue-detailed: Analytical results of insect tissue analyses 4. Benthic macroinvertebrates: Counts of benthic macroinvertebrate samples that coincided with the water and tissue samples 5. Water-QC: Results of quality control analyses associated with the water samples 6. Tissue-QC: Results of quality control analyses associated with the tissue samples For the 12 environmental stream samples from the Panther Creek watershed, Co values ranged from <0.01 to 329 µg/L and Cu values ranged from 0.2 to 24 µg/L. Dissolved organic carbon ranged from 0.72 to 2.2 mg/L, pH ranged from 7.1 to 8.8 units, alkalinity ranged from 8 to 50 mg/L as CaCO3, and hardness ranged from 17 to 167 mg/L as CaCO3. Approximate diel swings in pH for Panther Creek, measured at the Deep Creek campground prior to sunrise and in late afternoon were 0.4 units, and in Big Deer Creek at the mouth measured in early morning and late afternoon, the changes were less than 0.1 units. Cobalt and copper tissue concentrations ranged widely in the insects. Cobalt values ranged from 0.4 to 634 mg/kg dry weight in insect tissues and copper values ranged from 12 to 1080 mg/kg. Funding was from USGS Mineral Resources Program, and the Panther Creek sampling was conducted in cooperation with the Blackbird Mine Site Group. References Schmidt, T.S., Mebane, C.A., Miller, J.L., and Balistrieri, L.S., 2019, Effects of metal mixtures on aquatic insect communities in experimental streams: cadmium (Cd), cobalt (Co), copper (Cu), nickel (Ni), and zinc (Zn): US Geological Survey Data Release, also available at http://dx.doi.org/10.5066/P9XXBSAK