LEAD, ZINC, AND COPPER METAL DISTRIBUTION IN SEDIMENT INVENTORIES IN THE HUDSON RIVER ESTUARY

Extending just over 315 miles, the Hudson River is a dynamic estuarine ecosystem, which has played a pivotal role in the historical development and industrialization of North America. Better understanding of the overall sediment budget and the pattern of deposition and erosion is crucial for managing future development, restoration, and preservation as well as contaminants. Here we test the use of metal inventories as proxies for identifying sediment deposition in the Hudson River Estuary. We analyzed 38 sediment cores from the middle reaches of the estuary using X-ray Fluorescence spectrometry to determine the presence of heavy metal inventories including lead (Pb), zinc (Zn), and copper (Cu). The measurements were performed on wet cores and corrected for water content. Elevated metal inventories, specifically lead, are expected in sediments deposited within the industrialized 20th century, and thus provide evidence for deposition or erosion at a particular site. We combined this new data with previous results from other parts of the estuary to identify larger depositional trends and areas of increased metal content. We find large variations in the metal inventories along the estuary including several areas with very high inventories. Most likely this reflects the depositional pattern in the estuary, but it might also indicate sources of increased metal input. The results also show that the inventories of the three analyzed metals correlate well, indicating that they are practical proxies for 20th century deposition.