USGS Grant Number: G15AS00019
Year Established: 2015 Start Date: 2015-09-01 End Date: 2018-08-31
Total Federal Funds: $249,329 Total Non-Federal Funds: $250,978
Principal Investigators: Michael Lydy, Amanda Harwood, Kara Huff Hartz, Samuel Nutile
Abstract: Pyrethroid insecticides are often the most toxic contaminant detected in sediments, especially in urbanized watersheds where concentrations of pyrethroid insecticides frequently exceed lethal levels for aquatic invertebrates. In the summer of 2016, the U.S. Geological Survey National Water-Quality Assessment Program will evaluate the extent, distribution, and toxicity of contaminants in urban streams in the Northeastern United States, collecting sediments and water samples from approximately 70 sites in drainages with varying degrees of urbanization. Given the widespread use of pyrethroid insecticides in the United States, and the toxicity of these compounds to aquatic biota, we expect that pyrethroids will be the most toxic component of the sediments in this study, especially those samples collected in urban areas. The USGS survey will involve chemically analyzing the water and sediment samples, and evaluating the toxicity of whole sediment in standard 28-d Hyalella azteca (amphipod), 10-d Chironomus dilutus (midge), and 28-d Lampsilis siliquoidea (mussel) toxicity tests. However, estimating pyrethroid bioavailability is complicated by a number of factors (i.e., hydrophobicity and binding characteristics of pyrethroids in sediment). We believe that the USGS datasets could be strengthened by incorporation of additional bioavailability data, which we will generate using novel techniques that mitigate confounding factors not readily addressed by traditional toxicological approaches. In this collaborative proposal, we aim to complement the USGS’s efforts by assessing the bioavailability of pyrethroids in the same urban sediments using desorption-based single-point 24-h Tenax extractions and conducting 10-d H. azteca toxicity tests to complement the toxicity tests conducted by the USGS. Our previous work has demonstrated that Tenax extractable concentrations of hydrophobic organic contaminants in sediment, including pyrethroids, correlated well to bioaccumulation in aquatic invertebrates and it is expected that these concentrations will also correlate to toxicity. The proposed project will demonstrate that Tenax extractable concentrations of pyrethroid contaminated sediment correlate to the toxicity of our three test species (e.g. H. azteca, C. dilutus, and L. siliquoidea) allowing for development of a bioavailability-based toxicity model linking toxicity to Tenax extractable pyrethroid concentrations. The addition of 10-d H. azteca toxicity tests will also allow for inclusion of short-term and long-term toxicity endpoints into the model. In sediments with high toxicity, but low pyrethroid contamination, targeted toxicity identification evaluations will be conducted on the sediment to determine the source of toxicity. This, in conjunction with the USGS’s chemical characterization of the sediments, will help determine when toxicity is due to contaminants other than pyrethroids, helping to remove outliers from the bioavailability-based toxicity model, thereby strengthening this tool. Furthermore, H. azteca will be collected from field sites with elevated pyrethroid concentrations to determine if the pyrethroid resistance observed in other areas of the United States is present in the Northeast. The results of the proposed project will not only be useful to NAWQA and other water resource managers in helping explain sediment-associated toxicity results in the Northeastern United States, but after the bioavailability-based toxicity model is developed, it will provide managers with a tool to predict pyrethroid toxicity at any urban location in the future. The newly developed model will be especially useful as urbanization and subsequent pyrethroid contamination increases.