A column evaluation of Appalachian coal mine spoils' temporal leaching behavior

Spatial and temporal relationships among watershed mining, water quality, and freshwater mussel status in an eastern USA river

“…2) as a crude approximation of what likely occurs in nature, we interpret this correspondence as a reflection of fundamental geochemical processes governing major ion release from freshly exposed and non-pyritic mine spoils. Typically, peak releases occur in response to initial water exposures, and release concentrations decline with continued leaching (Sena et al, 2014;Orndorff et al, 2015). The greatest divergence of in-stream DS concentrations from the decay-weighted indicator's temporal pattern occurs early in the study period, when the decay-weighted indicator does not reflect pre-1980 mining.…”

“…Both laboratory (Orndorff et al, 2015) and field studies (Sena et al, 2014;Ross, 2015) demonstrate that TDS release by Appalachian mine spoils occurs most rapidly during the initial water exposures and declines with subsequent exposures until reaching a relatively constant concentration described as "stabilized" (Orndorff et al, 2015). Peak and stabilized concentrations vary widely among spoil types (Orndorff et al, 2015). Evans et al (2014) analyzed SC over time for water outflows from 137 Virginia valley fills.…”

“…Mining-related variables recorded with sufficient frequency to enable analysis (pH, SC, and TDS) were emphasized. Sulfate (SO 4 2 − ), bicarbonate (HCO 3 − ), calcium (Ca 2+ ), and magnesium (Mg 2+ ) are generally recognized as the predominant ions in nonacidic waters draining Appalachian surface mines (Pond et al, 2008;Pond et al, 2014;Orndorff et al, 2015;Timpano et al, 2015); hence, SO 4 2− , hardness and alkalinity were also included. Two additional variables (total nitrogen, total N; and chloride, Cl − ) that represent anthropogenic impacts more generally were also obtained and analyzed.…”

“…Evans et al (2014) analyzed SC over time for water outflows from 137 Virginia valley fills. The average peak concentration (1706 μS/cm), times required to reach that peak (9 years) and for decline to~500 μS/cm (~20 years), and an assumed 500 μS/cm stabilization level (Orndorff et al, 2015) were used to construct a temporal decay model for use in assessing water-quality impacts by mining-disturbed geologic materials (Fig. 2).…”

Effects of environmentally relevant mixtures of major ions on a freshwater mussel

“…Mining operations move unweathered geologic materials into the ambient environment, where exposure to O 2 and H 2 O enables accelerated weathering and major ion release (Orndorff et al, 2015). Mining-origin elevated stream salinity and associated alterations of aquatic communities have been documented throughout Appalachian USA (Bernhardt et al, 2012;Cormier et al, 2013;Evans et al, 2014;Griffith et al, 2012;Hitt and Chambers, 2014;Pond et al, 2008;Timpano et al, 2015).…”