Method for the estimation of organic-bound and crystal-bound metal concentrations in bivalve shells

The construction of bivalve shells is described and details are given of a procedure developed for separating and determining adsorbed heavy metals in the nacreous layer of the shell of the bivalve Elliptio complanata (frequently used as a biological monitor) for isomorphically-substituted metals. The concentrations of adsorbed and crystal cadmium and lead in shell nacre and soft tissues of the animals are tabulated. Bivalve shell nacre was a suitable monitor of trace metal contamination. However, species with a high organic matrix component of the shell should be avoided until the role of this matrix in the post-depositional mobility of metals is better understood.