Potential Coal Slurry Toxicity to Laboratory and Field Test Organisms in the Clinch River Watershed and the Ecotoxicological Recovery of Two Remediated Acid Mine Drainage Streams in the Powell River Watershed, Virginia
Chanov, Michael Kiprian
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The Clinch and Powell Rivers located in Southwestern Virginia contain some of the most diverse freshwater mussel assemblages found throughout North America. However, in recent decades mussel species decline has been documented by researchers. The presence of coal mining activity in the watersheds has been hypothesized to be linked to the decline of numerous species and the extirpation of others. The effects of various discharges from an active coal preparation plant facility located in Honaker, Virginia were evaluated for acute and chronic toxicity using field and laboratory tests. The results of the study suggested that the primary effluent from the coal preparation facility had acute and chronic toxicity; however, the settling pond system utilized at this plant mitigated the impacts of the plant from reaching the Clinch River. Along with active mine discharges, acid mine drainage (AMD) has been documented as another potential stressor. Ecotoxicological recovery was evaluated in two acid mine drainage impacted subwatersheds (Black Creek and Ely Creek) in the Powell River watershed following remediation. The results in Ely Creek suggested that successive alkalinity producing systems were effective in mitigating the harmful impacts of AMD as previously impacted sites had decreased water column aluminum and iron levels in conjunction with increased survival in laboratory toxicity tests conducted with Ceriodaphnia dubia and Daphnia magna. Corbicula fluminea (Asian clam) in-situ tests confirmed the results in the laboratory tests as all sites located below the remediated areas had improved survival. However, active AMD influences and loss of quality habitat seemed to be hindering the recovery of the benthic macroinvertebrate community located in Ely Creek. In Black Creek, re-mining and outlet control pond construction have not resulted in a successful remediation in the lower subwatershed. A decrease in Ecotoxicological Ratings at some of the lowest mainstem sites compared to pre-remediation data was observed. Furthermore, decreased survival in sediment associated toxicity tests with D. magna in 2007-08 was supported by 100% Asian clam mortality at the LBC-5 and LBC-6 sites in 2007, while growth impairment in 2008 was observed at the LBC-6 site.
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