Ecosystem functions within a mine drainage passive treatment system

The impacts of acid mine drainage (AMD) on receiving water bodies have been extensively studied. Water quality improvement provided by constructed wetlands is well known, but little is known about the ecological function of these treatment systems. A passive treatment system was constructed in eastern Oklahoma to treat AMD from an abandoned coal mine. Multiple water quality parameters were monitored. Chlorophyll a concentrations were determined throughout the system to estimate productivity. Multi-plate artificial substrate samplers were deployed to quantify and evaluate the macroinvertebrate assemblage within each cell. Productivity between treatment cells varied significantly. The cells receiving effluent from anoxic organic substrate had elevated nutrient levels, which led to elevated productivity. Chlorophyll a levels reached hypereutrophic conditions into final treatment cells. Macroinvertebrate community structure was significantly different among treatment cells. Primary cells produced more diverse and evenly distributed taxa, including the presence of moderately intolerant taxa. The treatment system exhibited early successional stage ecosystem functions and trends toward destructive oscillations.