PILOT STUDY OF HEAVY METAL CHEMISTRY OF CAVE SEDIMENTS IN THE SPRINGFIELD (MO) PLATEAU

Cave ecosystems are highly sensitive to physical or chemical disturbances. The caves of the Springfield (MO) Plateau are of particular interest because they house the endangered Ozark Blind Cavefish and numerous other cave species, including crayfish, salamanders, and isopods. Runoff from urban areas and effluent from animal production may introduce heavy metals into the subsurface, where they can accumulate in cave sediments. Cave isopods, which spend the majority of their life cycle in sediments, are a primary food source for the Ozarks Cavefish. Heavy metal accumulation in cave sediments may negatively impact the isopod population, thereby placing stress on the Ozarks Cavefish. This study compares the metal chemistry of cave sediments impacted by urban and animal production activities to a control cave, with a robust troglobitic fauna, whose surface watershed is contained primarily in protected lands. We used x-ray fluorescence to determine the relative concentrations of Zn, Pb, Cu, Ni, Co, Cd, Cr, and Hg as well as P and S present in sediments collected from each cave. Preliminary results show that the cave impacted by urban activities exhibits enrichment in Zn, Pb, Ni, Cu, +/- Hg. Potential metal sources include sewage, automobile exhaust, and local industry. The cave impacted by farming activities exhibits elevated levels of Zn, Cu, Ni, +/- Pb, however these levels are lower than those of urban areas. Potential metal sources include animal waste, exhaust from farm equipment, and illegal dumping. Alternatively, Pb, Zn, and Cu may occur naturally due to the presence of sulfides associated with the Tri-States MVT district. However, no sulfides are present in the host rock, nor are any known to be present in rocks in the immediate vicinity. Concentrations of P and S appear to be dependent only on the presence of bats in each cave system; where bat colonies were currently or historically present, P and S concentrations were elevated. These data indicate that urban and farming activities can significantly alter the chemistry of sediments in cave systems, by introducing heavy metals into the subsurface. In addition, the apparent relationship between low metal contents and biodiversity indicates that further study of cave sediment chemistry in Springfield Plateau cave systems is warranted.