Development and Implementation of Integrative Bioassessment Techniques to Delineate Small Order Acid Mine Drainage Impacted Streams of the North Fork Powell River, Southwestern Virginia
Abstract
Acid mine drainage (AMD) results from the oxidation of pyretic mineralogy, exposed by
mining operations to oxygen and water. This reaction produces sulfuric acid and
liberates heavy metals from the surrounding mineralogy and impairs water quality and
freshwater communities. The U.S. Army Corps of Engineers has begun an ecosystem
restoration project to remediate the abandoned mine land (AML) impacts to the North
Fork Powell River (NFP) and is utilizing the ecotoxicological rating (ETR) system to
delineate these affects to focus restoration efforts. The ETR was developed to summarize
the integrative data into a single number ranging from 0 to 100, which is descriptive of
the environmental integrity of a sampling station. The ETR is conceptualized to work as
an academic grading scale (0 through 100), rating reference stations with A's (90-100)
and B's (80-89) and impacted stations with C's (70-80), D's (60-70) and failures (F =
60). Two rounds of ETR investigations have evaluated seven headwater tributaries to
the NFP including investigations of Ely and Puckett's Creek from 1997 and 1998. This
thesis contains the results of the second series of ETR investigations at 41 stations in Cox
Creek, Jone's Creek, Reed's Creek, Summers Fork, Straight Creek, and areas in the NFP.
Eight stations were recommended for reclamation; CC 03, JCRF2 02, JCRF2 01, RCPS
09B, RCPS 11B, SULF 01, SU 02, and SU 01. Summers Fork was the most severely
impacted watershed of the second round of ETR investigations. An effort to streamline
the ETR to the most ecologically predictive parameters was successful in creating a
system more time and cost efficient then the initial ETRs and exclusive of benthic
macroinvertebrate surveys. The Modified ETR streamlined the ETR to just 5 parameters
including; mean conductivity, mean Asian clam survival, mean aluminum (Al) and
manganese (Mn) in the water column, and mean habitat score to describe the AMD
impacts to small headwater streams. Also, an investigation was conducted to determine
the mode of toxicity, (i.e., exposures to metal contaminated surface waters or sediments)
by which Al and iron (Fe) dominated AMD impairs benthic macroinvertebrate
communities. It was found that water column exposures both within and beyond the zone
of pH depression are the most likely mode by which AMD impairs the benthic
macroinvertebrate communities of the NFP.
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- Masters Theses [19413]