METALS IN THE MUD: CHANGES IN SURFACE SEDIMENT CONTAMINATION IN LONG ISLAND SOUND

Long Island Sound is an elongate estuary of the Atlantic Ocean between Connecticut to the north and Long Island, NY to the south. It is characterized by a general sedimentary trend of fine-grained material in the west with a gradual transition to coarse-grained material in the east. The surface sediment distribution of the Sound greatly impacts the concentrations of metal contaminants, both natural and anthropogenic. Areas of particular concern include the western and central regions. The predominance of deposition, heavily populated cities, and a high volume of industry along the shore contribute to the presence of metal contaminants in the sediment, which pose risks to human and environmental health. The study area for this research was between Port Jefferson, NY, and Bridgeport, CT, in the western center of the Sound. A series of metal contaminants (Ca, Cr, Cu, Fe, Mn, Pb, Ti, Zn, Zr) was evaluated in surface sediment samples from the study area. Expeditions were carried out by a team from Lamont-Doherty Earth Observatory (LDEO) in June of 2013 on the R/V Seawolf and R/V Pritchard of Stony Brook University. Grab samples were collected using a modified Van Veen grab. University of Connecticut samples were also used as part of the analysis. These samples were collected in 2012 using the Seabed Observation and Sampling System (SEABOSS) of the Woods Hole Science Center. 217 samples from 2012-13 were processed and analyzed at LDEO. X-Ray Fluorescence (XRF) Spectroscopy was used to determine light and heavy metal concentrations. 2012-13 sediment data was compared with data collected by the U.S. Geological Survey (USGS) in 1996 and 1997. Contaminant distribution maps were created using interpolation on ArcGis version 10.1 for 1996-97 samples and 2012-13 samples. The majority of our samples contained Cr, Cu, Pb, and Zn concentrations below “Effects Range-Low” (ERL) guideline values, which are indicative of concentrations below which adverse effects rarely occur. Based on results from the 217 samples, concentrations of several metals of concern appear to have decreased in the study area compared to the 1996-97 surveys. This may be due to changes in deposition or erosion, sources of sediment, or success in stricter environmental regulations.