THE EFFECT OF ACID MINE DRAINAGE ON TRACE ELEMENT COMPOSITION OF FRESHWATER MOLLUSCS: SHAMOKIN CREEK (SUNBURY), PA

Preliminary data suggests that the trace element composition of two different types of freshwater mollusks: Asiatic clam Corbicula and high spired gastropod Goniobasis may be attributed to acid mine drainage from Shamokin Creek into the Susquehanna River near Sunbury, Pennsylvania. Samples of mollusks were collected from meter2 plots in up to 35 cm water and along the banks of the Susquehanna River, north and south of where Shamokin Creek drains into the Susquehanna River. This creek drains rocks of Devonian and Carboniferous ages, including the Llewellyn Formation (Pennsylvanian age), where it is greatly influenced by acid mine drainage. Whole and powdered samples of these shells were analyzed using x-ray fluorescence (XRF). Samples collected north of the Shamokin Creek tributary appear to have less Fe, Cu, Ni, Sn, and Zr relative to samples examined south of the creek. In addition to this, the soft tissue collected from the living bivalve, Andonta, just south of Shamokin Creek were also enriched in concentrations of Fe, Cu, and Zr. Though many of the shells may have experienced some transport, 27% of the shells were characterized as very little weathered, in which 0 to 25% of the peristricum had been removed, and 40% were considered little weathered (25 to 50 % of peristricum removed). Also, 20% were articulated where collected. Most of the shells are thought to have experienced little transport. The elevated concentrations of certain metals does not appear to be a great environmental threat, however this study suggests that certain aquatic organisms may be affected by areas of acid mine drainage, especially associated with Carboniferous age rocks.