DETAILED PHOSPHORUS GEOCHEMISTRY IN SURFACE SOILS FROM THE ABANDONED FRIAR TUCK MINING COMPLEX, SULLIVAN COUNTY, INDIANA

The abandoned Friar Tuck Mining Complex (FTMC) in Sullivan County, Indiana, ceased operations in 1952. However, the area continues to be impaired by acidic drainage, which contributes to poor water quality in Mud Creek, adjacent to the site. In addition, acidic seeps create unpredictable areas with sparse vegetation already characterized by thin, poorly developed soils commonly with pH <4. In spring 2010, ~250 soil samples were collected in order to evaluate the levels of metals and phosphorus (P) in the surface soils, from an area of the complex that requires further remediation. In spring 2011, ~100 samples were collected from areas that have been designated as successfully reclaimed. A subset of these samples has been treated with a sequential extraction technique to evaluate how P is bound within the soil (mineral P, organic P, or bound to oxides). The coal seam mined at the FTMC is Pennsylvanian in age, and the distribution of P found in the soils from FTMC was also compared to other Pennsylvanian black shale deposits (Excello Shale). Total P concentrations for the site are generally low (<25 µmol/g). These P concentrations are considerably lower than those found in other organic-rich deposits (up to 280 µmol/g), which are usually dominated by mineral P. Iron oxides are prevalent in the surface soils, and the dominate P fraction is associated with these iron oxides. Organic P also comprises a significant portion of the total P concentrations at FTMC relative to the other phases, but the concentrations are similar to those found in the Excello Shale (5-10 µmol/g). The dominance of oxide-associated P at FTMC is presumed to be related to coal mining activities, the formations of acid mine drainage and reclamation efforts. In particular, these activities have converted mineral P to oxide-associated P and resulted in a net loss of P from FTMC significantly changing the productivity of these soils. These results suggest that the mining and reclamation process strips P from soils and impacts the soil’s biogeochemical cycling and P reservoirs.