Near surface (< 10 cm) sediment distributions of 234Th sampled multiple times at five locations along the axis of the Hudson Estuary from the Upper Bay of New York to Haverstraw Bay are compared with 210Pb data from longer cores at the same locations. The comparison indicates that while there is little net sediment accumulation anywhere except at one location in the Upper Bay, near surface sediment in this reach of the estuary is mobile on short (months) time scales. The sediment appears to be physically mixed rather than bioturbated. Comparison of the sediment inventories of 234Th with calculated water column production indicates short time scale (months) variability in 234Th deposition. Some parts of the bottom have 234Th inventories in excess of local production but these appear to be balanced by 234Th deficient area, resulting in a general equilibrium. Sediment inventories of Pb, Cu, and Zn normalized to 210Pb show no evidence of a uniquely urban source of these metals to the lower estuary. Silver distributions in sediment indicate a possible source of silver from New York City, probably related to sewage inputs.
|Number of pages||19|
|State||Published - Dec 1996|