Geochemical modeling of coal mine drainage, Summit County, Ohio

Geochemical modeling was used to investigate downstream changes in coal mine drainage at Silver Creek Metro-park, Summit County, Ohio. A simple mixing model identified the components that are undergoing conservative transport (Cl-, PO43-, Ca2+, K+, Mg2+ and Na+) and those undergoing reactive transport (DO, HCO3-, SO42-, Fe2+, Mn2+ and Si). Fe2+ is removed by precipitation of amorphous iron-hydroxide. Mn2+ are removed along with Fe2+ by adsorption onto surfaces of iron-hydroxides. DO increases downstream due to absorption from the atmosphere. The HCO3- concentration increases downstream as a result of oxidation of organic material. The rate of Fe2+ removal from the mine drainage was estimated from the linear relationship between Fe+2 concentration and downstream distance to be 0.126 mg/s. Results of this study can be used to improve the design of aerobic wetlands used to treat acid mine drainage.