Selective Extraction Chemistry of Toxic Metal Sulfides from Sediments

Experimental evidence suggests that formation of metal sulfides in anoxic sediments limits the bioavailability of several toxic elements. Our ability to quantify the processes by which these metal sulfides form is dependent upon our ability to determine the speciation of solid phase metals in sediments. Our work indicates that an entire suite of Cu-Fe and Ni-Fe sulfide minerals can form upon the exposure of mackinawite to aqueous Cu and Ni. Furthermore, we have demonstrated that the solubility of pure metal sulfide minerals and their iron-metal derivatives in HCl directly correlates with the observed trends in the 'Degree of Trace Metal Pyritization' in natural sediments. Current extraction schemes cannot distinguish discrete trace metal sulfides from trace metals associated with pyrite.