Contaminant distribution and accumulation in the surface sediments of LongIsland Sound

The distribution of contaminants in surface sediments has been measured and mapped as part of a U.S. Geological Survey study of the sediment quality a nd dynamics of Long Island Sound. Surface samples from 219 stations were an alyzed for trace (Ag, Ba, Cd, Cr, Cu, Hg, Ni, Pb, V, Zn and Zr) and major ( Al, Fe, Mn, Ca, and Ti) elements, grain size, and Clostridium perfringens s pores. Principal Components Analysis was used to identify metals that may c ovary as a function of common sources or geochemistry. The metallic element s generally have higher concentrations in fine-grained deposits, and their transport and depositional patterns mimic those of small particles. Fine-gr ained particles are remobilized and transported from areas of high bottom e nergy and deposited in less dynamic regions of the Sound. Metal concentrati ons in bottom sediments are high in the western part of the Sound and low i n the bottom-scoured regions of the eastern Sound. The sediment chemistry w as compared to model results (SIGNELL et al., 1998) and maps of sedimentary environments (KNEBEL et al., 1999) to better understand the processes resp onsible for contaminant distribution across the Sound. Metal concentrations were normalized to grain-size and the resulting ratios are uniform in the depositional basins of the Sound and show residual signals in the eastern e nd as well as in some local areas. The preferential transport of fine-grain ed material from regions of high bottom stress is probably the dominant fac tor controlling the metal concentrations in different regions of Long Islan d Sound. This physical redistribution has implications for environmental ma nagement in the region.