Laboratory to field validation in an integrative assessment of an acid mine drainage-impacted watershed

An integrative assessment was conducted in the Puckett's Creek watershed of southwestern Virginia, USA, to investigate the environmental impacts of acid mine drainage (AMD) inputs. Twenty-one sampling stations were categorized into groups based on five degrees of AMD input: (1) none, (2) intermittent acidic/circum-neutral AMD, (3) continuous acidic AMD, (4) continuous circum-neutral AMD, and (5) receiving system stations with at least two levels of dilution. Bioassessment techniques included water/sediment chemistry, benthic macroinvertebrate sampling, laboratory acute water column toxicity testing, laboratory chronic sediment toxicity testing, and in situ toxicity testing with Asian clams (Corbicula fluminea [Muller]). Group 3 stations had significantly altered water chemistry (low pH, high conductivity, and high water column metals) relative to the other groups and significantly higher sediment iron concentrations. Both group 3 and group 4 stations had significantly decreased ephemeroptera-plecoptera- trichoptera richness and percent ephemeroptera abundance relative to unimpacted stations. Group 3 stations also had decreased total taxon richness. Water column toxicity testing was sensitive to AMD impacts, with samples from group 3 stations being significantly more toxic than those from groups 2 and 4, which in turn were more toxic than those from groups 1 and 5. Similar results were observed for in situ toxicity testing. No differences in sediment toxicity test survival and impairment results were observed among the station groups. Stepwise multiple linear regression and simple bivariate correlation analyses were used to select parameters for use in an ecotoxicologic rating system, which was successful in differentiating between two levels of environmental impact relative to stations receiving no AMD input.