IN SITU MEASUREMENT OF SULFIDE IN NATURAL WATERS

Abstract

Dissimilative sulfate reduction is a major source of sulfide in sediments and the water column of lakes and estuaries. Resulting dissolved sulfide can be incorporated into organic or inorganic sulfur complexes. When present in aquatic systems, sulfide is the dominant ligand for many trace metals and may control metal bioavailability to organisms. Laboratory tests were performed to validate the coupling of the diffusive gradient in thin films technique to a solid-state ion selective electrode to quantify in situ sulfide concentrations. Diffusive gradient in thin films probes were deployed in three lakes and estuary pore water and compared with parallel sulfide measurements using the Cline method and potentiometry. Differences between the recently validated method and the other methods were found with the former resulting in lower concentrations. Laboratory experiments examined these differences, and the experimental results identified measurement artifacts associated with sulfide antioxidant buffer usage.