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Sediment Bioaccumulation Test with Lumbriculus variegatus: Effects of Organism Loading
Citation:
Burkhard, L., D. Hubin-Barrows, N. Billa, T. Highland, R. Hockett, Dave Mount, AND T. Norberg-King. Sediment Bioaccumulation Test with Lumbriculus variegatus: Effects of Organism Loading. ARCHIVES OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY. Springer, New York, NY, 71(7):70-77, (2016).
Impact/Purpose:
Sediment bioaccumulation test methodology of US-EPA, released in 2000, specifies that the loading of Lumbriculus variegatus (dwt) to the sediments be no greater that 2% of the total organic carbon in the sediments. In the methods, the loading is expressed as the ratio of TOC to L. variegatus (dwt) with the recommendation of no less than 50:1. When examining testing results from Superfund sites, we often observe tests performed at ratios less than the 50:1 TOC to L. variegatus (dwt). The motivation for this work was to evaluate the effects of performing tests at less than the 50:1 recommendation. Overall, the differences in residues among loading ratios across all sediments were small, i.e., ±50% from those measured at the recommended ratio of 50:1 TOC to L. variegatus, and residues were not significantly different between loadings of 50:1 TOC to L. variegatus and those with loadings in the mid-20s:1. The incentive for this work arises from on-going efforts within EPA to update its freshwater sediment testing guidance document (US-EPA 2000). This study allows examination of the recommendation of no less than 50:1 TOC to L. variegatus ratio. The data suggests that the recommended no less than 50:1 TOC to L. variegatus ratio could be relaxed (lower ratio) without substantively affecting the results, and could be considerably lowered if differences of ±50% are not of concern.
Description:
Sediment bioaccumulation tests with Lumbriculus variegatus were performed on seven sediments with a series of ratios of total organic carbon in sediment to L. variegatus (dry weight) (TOC/Lv) that spanned the recommendation of no less than 50:1. With increasing loading of organisms, growth of the organisms decreased in six of the seven sediments test. Residues of polychlorinated biphenyls (PCB) in the L. variegatus were measured in six of the seven sediments tested. With two sediments, PCB residues increased with increasing loading of the organism while in the remaining four sediments analyzed, PCB residues were not significantly across the different loadings of the organism. Overall, the differences in residues among the loading rates across all sediments were small, i.e., 50% from the 50:1 TOC/Lv recommendation. As reported previously, we observed no significant differences between loadings of 50:1 TOC/Lv and those with loadings in the mid-20s:1.
