Mapping Heavy Metal Contamination in Eastern Long Island Sound and Analyzing Transport Mechanisms

Mapping Heavy Metal Contamination in Eastern Long Island Sound and Analyzing Transport Mechanisms

Sufyan Khalid¹, Frank O. Nitsche², Tim C. Kenna², Clara Chang²

¹Columbia University, ²Lamont-Doherty Earth Observatory

Long Island Sound has a long-standing history of anthropogenic pollution dating from 1800s to early 1900s due to a strong presence of chemical, aircraft and weapon manufacturing industries in the eastern Long Island region especially in the Connecticut region. The result has been decades of metal contamination in the watershed of Long Island Sound. Previous studies have found the median metal concentrations (Cd, Cr, Cu, Mn, Hg, Ni, Pb, Ag, and Zn) to exceed the New York State Department of Environmental Conservation (NYSDEC) Low Effects Level (LEL). Studies characterized certain regions as hotspots for heavy metal contamination. In this study, we map the distribution of heavy metal concentrations in the Eastern Long Island region in order to identify sources, hotspots, and overall transport of the contaminants. Using petrophysical measurements such as grain size, density and total organic carbon we will characterize the processes responsible for transport of contaminants. Around 350 surface sediment samples were collected as part of an overall Long Island Sound Mapping Project during 2017-2018. Samples were analyzed using handheld X-ray fluorescence (XRF) to determine elemental composition and a Penta-Pycnometer to measure density. Our results confirmed the presence of high concentration spot of metals closer to the coast and a non-uniform spread overall. We observed that contamination metals (Pb, Cu, Co, Ni) are stored in the sediment fine fraction, further supported by a strong inverse correlation between Zr and Pb concentrations among the sediment. We noted a high correlation between certain heavy metals (Pb, Ba, Co) which will help to trace contamination sources.