Ecotoxicological Evaluation of Hollow Fill Drainages in Low Order Streams in the Appalachian Mountains of Virginia and West Virginia
Merricks, Timothy Chad
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Hollow fills are composed of excess spoil and debris produced from surface coal mining that is not returned to the original mined site. Hollow fills are often constructed in the head of hollows nearby or adjacent to the mined land area, which may be the origins of headwater streams or drain into low order systems. Eleven hollow fills were utilized in evaluating the influence fill drainages had on low order streams in Virginia and West Virginia. The study was conducted in six watersheds including; Five Mile Creek in Mingo County, West Virginia, Trace Fork in Mingo County, West Virginia, Lavender Fork in Boone County, West Virginia, Middle Creek in Tazewell County, Virginia, South Fork of the Pound River in Wise County, Virginia, and Powell River in Wise County, Virginia. Bioassessment procedures used in the evaluation of hollow fill drainages included water/sediment chemistry, acute water column toxicity testing using Ceriodaphnia dubia, chronic sediment toxicity testing using Daphnia magna, benthic macroinvertebrate surveys, and in situ Asian clam (Corbicula fluminea) toxicity testing. Common significant differences in water quality between reference and fill influenced sites, among all watersheds, were elevated conductivity and water column metal concentrations, particularly aluminum and copper. Water column and sediment toxicity testing reported limited significant mortality or reproductive impairment associated with hollow fill drainages. The West Virginia watersheds used in the study consisted of headwater streams originating directly from the settling ponds, placed at the base of the hollow fills, receiving drainages from the fills. Benthic macroinvertebrate analysis reported no significant alteration in total taxa or EPT richness downstream of the ponds. Yet, collector filterer populations, including benthic macroinvertebrates and in situ Asian clams, were enhanced directly downstream of the ponds due to organic enrichment originating from the ponds. A decrease in collector filterer populations and lowered clam growth suggested the organic enrichment dissipated downstream from the ponds. Chlorophyll a analysis of the phytoplankton community was not significantly related to the enhance collector filterer populations in the streams, however the high concentrations in the settling ponds suggest abundant algal communities. The hollow fills evaluated in Virginia drained into receiving systems, whose headwater origins were not directly related to hollow fill drainages. Low taxa richness was associated with the hollow fill and settling pond drainages, however receiving system sites were minimally influenced. Yet, as reported in the West Virginia watersheds, the settling ponds input organic enrichment that enhanced collector filterer populations, including benthic macroinvertebrates and in situ test clams. An analysis of the hollow fillsâ age, or maturity, reported no significant difference between young and old fills. In general, a common feature of among the various aged fill drainages was elevated conductivity, compared to reference sites of the watersheds.
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