The release and leaching of metal pollutants into coastal and estuarine environments has been greatly curtailed, but capped deposits can still reenter the ecosystem by natural perturbation or human activity. The potential use of hard clam, Mercenaria mercenaria, exterior shells as a heavy metal biosorbent that contain the polymorphs of CaCO3 (aragonite and calcite) was investigated in conjunction with the development of an in-field X-ray fluorescence (XRF) analysis protocol. The cation exchange capacity of Pb2+, Cd2+, and Zn2+ ions between sediment, pore water, and shell at varying habitat potential pHs (2.5, 4, 5, and 8) reflect the sedentary borrowing of the quahog through sediment strata (1 m depth). The adsorption of the whole shell’s outer surface in various buffered solutions of either distilled or ocean water was assessed by XRF and the released solubilized ions determined by inductively coupled plasma (ICP). Metal (Cu2+, Pb2+, and Cd2+ ions) charged shells were exposed to buffered (pHs: 2.5, 4, 5, and 8) distilled and sea water solutions, buffered washed sediment slurries, and non-treated sediments from the harvest location to assess the potential re-release of metal to its surroundings. Shell and environmental solid metal ion exchanges were analyzed by XRF, while solubilized ions were analyzed by ICP.

In-situ assessment of shell surface cation exchange capacity of heavy metals Cd2+, Pb2+, and Zn2+ by XRF

2019 Spring National Meeting

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