You are here:
INTERACTION OF METALS AND ORGAINIC CARBON COLLOIDS IN ANOXIC INTERSTITIAL WATERS OF MARINE SEDIMENTS
Citation:
Cantwell, M G. AND R M. Burgess. INTERACTION OF METALS AND ORGAINIC CARBON COLLOIDS IN ANOXIC INTERSTITIAL WATERS OF MARINE SEDIMENTS. Presented at Society of Environmental Toxicology and Chemistry Annual Meeting, Philadelphia, PA, November 14-18, 1999.
Description:
Marine colloids are an important component of natural water geochemistry critical to the cycling, speciation and bioavailability of metals in marine sediments. In sediment, metals exist in three phases: particulate, colloidal and dissolved. Dissolved metal concentrations have been shown to be better predictors ofbioavailability than the total sediment metal. In order to better predict dissolved concentrations, it is essential to understand metal speciation. In sediment, interstitial water is a primary route of metal exposure to many benthic organisms. Colloidal organic carbon is ubiquitous in marine interstitial water and readily forms complexes with numerous dissolved metals greatly reducing their bioavailability. Weare currently validating a methodology for isolating dissolved and colloidal cadmium, copper, nickel, lead and zinc from anoxic interstitial waters in order to better understand factors controlling metal speciation and bioavailability. Interstitial waters are separated from sediments by centrifugation followed by colloidal and dissolved metal isolation by stirred cell ultrafiltration. Sediment core samples were collected from metal contaminated sites in Narragansett Bay, (RI). As expected, results indicate copper and lead are highly associated with organic colloids while zinc is to a lesser degree. Nickel and cadmium however, remain largely in the dissolved phase of the interstitial water. This study demonstrates that interstitial water variables such as pH, salinity as well as colloidal organic carbon concentration have important influences on the speciation of metals in sediment interstitial waters. Understanding the speciation of individual toxic metals should improve our ability to predict metal bioavailability in marine sediments.