Effects of Super Strom Sandy on Depositional Environments Offshore Long Island, New York

Hurricane Sandy's landfall affected the coastlines over a broad swath of mid-Atlantic including New York, New Jersey, Delaware, Maryland, Virginia, and North Carolina. The effects included breaching, overwash and erosion of barrier islands, some of which are heavily populated and sustained extensive damage. The peak storm-tide elevation produced by Hurricane Sandy measured by USGS stations in Jamaica Bay was about 3.5 m, 1.4 m more than the historical peak-water level elevations in the same area. As part of a National Science Foundation RAPID response we sampled the sediment in West Bay, Middle Bay, East Bay, Jones Inlet and Reynolds Channel of Long Island, New York from the R/V Pritchard. The sediment sampling took place 4 months after the storm and prior to any similar large storms. The sampling strategy was designed to characterize the post-storm sedimentation in distinct depositional environments. In this survey 156 grab samples were recovered from areas, many of which had been sampled prior to the storm. The samples were analyzed for grain size variability, short-lived radioisotopes and x-ray fluorescence elemental analyses. Google Earth images from before and after the storm reveal moderate to severe erosion and overwash of the dunes in Jones inlet, and Middle and East Bays. The Long Beach barrier island tidal marshes were submerged for several days post Sandy and underwent severe erosion. The storm surge brought from offshore a layer of coarse sand that was deposited over mussel beds. Most of the mussels were dead indicative of the strength of the waves. Be-7 concentrations allowed tracking the path of the storm from the bays and inlets, to the offshore. Some of the highest Be-7 concentrations ever detected in the local estuaries: 5,329, 4,955 and 4,553 pCi/kg were measured in West Bay and Middle Bay Channels. Additionally, unusually high Be-7 concentrations of 2,130 pCi/kg were recorded ~5.24 km offshore from Long Beach barrier island four months after the storm. Si and Ca weight percentages range up to 33.9 and 2.47 respectively and correlate with the amount of sand in the samples. Previous studies have shown that Al is an indication of fine grain sediments. We found higher Al concentrations in the Bays and offshore but not in Jones inlet suggestive of rapid transport of fine grains offshore. The heavy elements Cu and Pb have very high concentrations up to 247.6 ppm and 185.8 ppm, respectively. The highest are near the Bay Park Sewage Treatment Plant and offshore. These very high concentrations may have resulted from sewage overflow. The Bay Park Sewage Treatment Plant was down for about 44 days after Sandy Storm. In addition, Zn up to 314.9 ppm measured in the Middle Bay and Jones inlet, could have resulted from urban-runoff caused by the storm. Sandy was catastrophic and resulted in significant erosion and beach overwash. The storm surge brought coarse sediment inland modifying channel and inlet depth. But most damaging was the seaward surge that brought contaminants offshore. The storm lasted a couple of days but its damaging effects to depositional environments persisted for at least four months after the event.