HEAVY METAL CONCENTRATIONS IN CORBICULA FLUMINEA: AN INVESTIGATION INTO ACCUMULATION FACTORS AND THE EFFECTS OF URBANIZATION ON WATERWAYS IN SOUTHEASTERN PENNSYLVANIA

In the past decade, clams have gained popularity as bioindicators of heavy metal contamination in waterways that have been polluted due to the biogeochemical impacts of urbanization. However, there is limited research assessing precisely the effects of different environmental agents upon the accumulation of heavy metals in the organic tissue and shells of bivalves. This experiment sets to establish whether filtration or feeding has the greater effect upon the accumulation of lead in an invasive species of clam, Corbicula fluminea, and also compares heavy metal concentrations in clams collected from various point sources of pollution in Southeastern Pennsylvania: quarries, dams, concrete production sites, wastewater treatment plants, and agricultural plots. The experiment began with sixty acclimatized clams, split evenly into six test groups: two filtration groups, two feeding groups, and two control groups. Every three days, twenty clams were exposed to lead nitrate at a concentration of .1mg/L, and another twenty clams to a 40ml suspension of phytoplankton inoculated with lead at a concentration of 1mg/L. After thirty days, half of the clams were collected and frozen at -80°C while the rest were collected ten days later to determine depuration of lead. Using inductively coupled mass spectrometry (ICP-MS), we determined average lead concentrations in each test group as well as Cr, Mn, Fe, Co, Ni, Cu, Zn, Ba, As, Se, Mo, Ag, Cd, Al in clams collected in situ. Lead concentrations were statistically compared between treatment type and length of depuration while clams collected from point sources were statistically compared to other locations, water concentrations, and sediment concentrations.