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The World of Protozoa, Rotifera, Nematoda and Oligochaeta

Ref ID : 7136

Joseph N. Mwangi, Ning Wang, Andrew Ritts, James L. Kunz, Christopher G. Ingersoll, Hao Li, and Baolin Deng; Toxicity of Silicon Carbide Nanowires to Sediment-dwelling Invetebrates in Water or Sediment Exposures. Environmental Toxicology & Chemistry 30(4):981-987, 2011

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Silicon carbide nanowires (SiCNW) are insoluble in water. When released into an aquatic environment, SiCNW would likely accumulate in sediment. The objective of this study was to assess the toxicity of SiCNW to four freshwater sediment-dwelling organisms: amphipods (Hyalella azteca), midges (Chironomus dilutus), oligochaetes (Lumbriculus variegatus), and mussels (Lampsilis siliquoidea). Amphipods were exposed to either sonicated or nonsonicated SiCNW in water (1.0 g/L) for 48 hr. Midges, mussels and oligochaetes were exposed only to sonicated SiCNW in water for 96 hr. In addition, amphipods were exposed to sonicated SiCNW in whole sediment for 10 days (44% SiCNW on dry wt basis). Mean 48-hr survival of amphipods exposed to nonsonicated SiCNW in water was not significantly different from the control, whereas mean survival of amphipods exposed to sonicated SiCNW in two 48-hr exposures (0 or 15% survival) was significantly different from the control (90 or 98% survival). In contrast, no effect of sonicated SiCNW was observed on survival of midges, mussels, or oligochaetes. Survival of amphipods was not significantly reduced in 10-day exposures to sonicated SiCNW either mixed in the sediment or layered on the sediment surface. However, significant reduction in amphipod biomass was observed with the SiCNW either mixed in sediment or layered on the sediment surface, and the reduction was more pronounced for SiCNW layered on the sediment. These results indicated that, under the experimental conditions, nonsonicated SiCNW in water were not acutely toxic to amphipods sonicated SiCNW in water are acutely toxic to the amphipods, but not to other organisms tested, and sonicated SiCNW in sediment affected the growth but not the survival of amphipods.