The effect of dissolved organic matter on mercury bioaccumulation in Simulium spp (Diptera, Simuliidae).

摘要

This thesis examines the effects of dissolved organic matter (DOM) on the bioaccumulation of Hg in Simulium spp (Diptera, Simuliidae) in soft water from Ontario, Canada, both in the field and in laboratory microcosms. The concentration of Hg in larval Simulium spp in streams in the District of Muskoka and Haliburton County was high compared to literature values, ranging from 0.07--0.64 mug/g DW. Larval Hg concentrations were significantly correlated with stream DOC concentration, pH, and %wetland in the stream catchment. The effect of DOM size on Hg bioaccumulation was investigated in microcosms. There was no difference in uptake between larvae exposed to small DOM size fractions (0.45mum, 100kDa, and 10kDa). Increasing pH leads to increasing Hg bioaccumulation in the microcosms. In conclusion, Hg binding to DOM does not inhibit bioaccumulation of Hg. Fish consume great quantities of black fly larvae, which could be a significant source of dietary Hg.