Files
Abstract
Trace elements occur naturally within the Earths crust but human activity can introduce them into aquatic environments, resulting in elevated concentrations, potentially leading to toxicity. The purpose of this dissertation was to evaluate a biomonitor approach for assessing trace elements in the Altamaha River system. First, bioaccumulation of trace elements in the Asian clam, Corbicula fluminea, was compared to that of the co-occurring native mussel, Elliptio hopetonensis. Corbicula was shown to accumulate higher concentrations of several potentially toxic trace elements (As, Cd, Cu and Hg) than E. hopetonensis. When compared across sites, concentrations of As, Cd, Cu, Hg and Pb were correlated between the two species, supporting Corbiculas suitability as an indicator of concentrations in E. hopetonensis. A wider survey of bioaccumulation using only Corbicula found significant sources of Cd, Cr, Cu, Hg and Zn within the Altamaha system. Controlling for natural variation in environmental and individual parameters eliminated some statistical significance in this survey. Site location in the watershed, dissolved oxygen, sediment composition, concentrations of elements in the sediment and organism length and condition were factors that influenced trace element bioaccumulation. Finally, E. hopetonensis shells were sectioned and the trace element profiles of annuli were analyzed using laser ablation inductively coupled plasma-mass spectrometry (LA ICP-MS). Mn was found to accumulate in the shell in a seasonal manner. Using Mn profiles to compare shells from the same site aligned peaks in Pb concentration were between shells. This indicates that freshwater bivalve shells could serve as archives of the local environment. Overall, these findings elucidate some of the aspects needed for a successful and informative biomonitoring program for trace metals using freshwater bivalves, as well as suggesting some future methods of biomonitoring