Salt Marsh Sediment Metal Concentrations: An Approximation of Metal Bioavailability

Caitlyn P. Nichols (1, 2), William G. Wallace (1, 3, 4), Pradyot Patnaik (2), Evelyn Powers (2)

Angela Ward (4)

(1) Earth and Environmental Science Program, City University of New York Graduate Center, Department of Earth and Environmental Sciences, The Graduate Center, 365 Fifth Avenue, New York, NY 10016 (212) 817-8240, http://web.gc.cuny.edu/Ees/home.html

(2) Interstate Environmental Commission, 311 W. 43^rd St, New York, NY 10036 (212) 582-0380,  
(212) 581-5719, http://www.iec-nynjct.org

(3) Center for Environmental Science, City University of New York College of Staten Island, Building 6S Room 310, College of Staten Island/CUNY, 2800 Victory Blvd., Staten Island, NY 10314
(718) 982-3876, (718) 982-3852, http://www.library.csi.cuny.edu/dept/as/ces/ces.htm

(4) Biology Department, City University of New York College of Staten Island, Building 6S Room 143 College of Staten Island/CUNY, 2800 Victory Blvd., Staten Island, NY 10314 (718) 982-3850, (718) 982-3852, http://ww.library.csi.cuny.edu/dept/biology

Effects of heavy metals on estuarine biota are related to the concentration of pollutants that are biologically available in exposure media (water or sediment).  In estuarine environments bioavailable metals are correlated with easily extractable fractions, rather than with total metal contents.  Previous studies have demonstrated that metal extracted from sediments using partial extraction techniques (weak HCl) releases biologically relevant fractions of elements.  The focus of our study was to quantify bioavailable metals (Cd, Cu, Zn)   in sediments of salt marshes adjoining the Arthur Kill, in Staten Island, New York.  Results show that sites within the Arthur Kill proper contain high levels of bioavailable Cd, Cu and Zn.  We found concentrations of extracted metals at the least contaminated site, Lemon Creek, to be slightly higher than (at the surface) or comparable (at depth) to background levels.  Surface and subsurface sediments at sites near the Fresh Kills landfill were found to contain metals notably elevated above regional background concentrations.   Metal concentrations in sediments near a former smelting facility contained the highest Cd, Cu, and Zn levels in the area.  Obvious subsurface peaks are indicative of past pollutant activities and consequent metal loadings.  In general, subsurface concentrations (2-20cm) were found to be higher than surface concentrations (0-2cm) suggesting 1) a decrease in metal loadings to the region and 2) greater vulnerability of metal exposure to subsurface deposit feeders compared to surface deposit feeders.  Future studies will assess the toxicity of these metal-contaminated sediments to organisms inhabiting these areas.