THE IMPACT OF POULTRY LITTER APPLICATION ON TRACE ELEMENT CHEMISTRY OF WATER AND SEDIMENTS IN THE BROADKILL RIVER, DELAWARE

The use of trace elements (As, Cu, Zn) as poultry feed additives has increased as the industry has grown. Because poultry litter is rich in nutrients, more than 90% is applied as fertilizer in the U.S. Due to the use of feed additives, on the Delmarva Peninsula, a region with intense poultry production, up to 26,000 kg As may be released through litter application (Garbarino et al., 2003). At a field site on the Delmarva, we have addressed field-scale mobilization of trace elements added to poultry feed from litter application. Our results thus far have shown that As, Cu, Zn and other litter-derived species are highly soluble from litter but their mobility is controlled by physical and biogeochemical reactions within the subsurface. The objective of this project is to examine if long-term litter application impacts chemical signatures of As, Cu and Zn in river sediments within the larger Broadkill River system. To address this objective, we have sampled sediment and water at 23 surface water sites within the Broadkill River watershed. Using GIS maps with overlays of hydrology and land use activity, we relate concentrations of As, Cu, Zn and P to land use within the watershed. Preliminary results suggest that higher As, Cu and Zn in sediment are correlated with areas of high agricultural activity, although trace elements in water samples meet regulatory standards. These data will be used to provide a watershed-scale evaluation of how poultry litter application impacts trace element concentrations in the estuary.