Selective extraction chemistry of toxic metal sulfides from sediments

Experimental evidence suggests that formation of metal sulfides in anoxic s ediments limits the bioavailability of several toxic elements. Our ability to quantify the processes by which these metal sulfides form is dependent u pon our ability to determine the speciation of solid phase metals in sedime nts. Our work indicates that an entire suite of Cu-Fe and Ni-Fe sulfide min erals can form upon the exposure of mackinawite to aqueous Cu and Ni. Furth ermore, we have demonstrated that the solubility of pure metal sulfide mine rals and their iron-metal derivatives in HCl directly correlates with the o bserved trends in the "Degree of Trace Metal Pyritization" in natural sedim ents. Current extraction schemes cannot distinguish discrete trace metal su lfides from trace metals associated with pyrite.