ARS | Publication request: Spatial and Temporal Variability of Nutrient, Metal, and Pesticide Concentrations in the Choptank River Watershed

Submitted to: Soil and Water Conservation Society Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: March 1, 2007
Publication Date: July 25, 2007
Citation: Hapeman, C.J., Rice, C., McConnell, L.L., Codling, E.E., Fisher, T., Hively, W.D., Lang, M.W., Whitall, D., McCarty, G.W., Sadeghi, A.M. 2007. Spatial and Temporal Variability of Nutrient, Metal, and Pesticide Concentrations in the Choptank River Watershed [abstract]. 2007 Annual Soil and Water Conservation Conference, July 21-25, 2007, Tampa, Florida. 2007 CDROM.

Technical Abstract: The Choptank River, a Chesapeake Bay tributary on the Delmarva Peninsula, consists of 1,756 km2 of land surrounding 280 km2 of estuarine waters. Land use is dominated by agriculture, croplands and animal (poultry and dairy) feeding operations, followed by forested areas and small towns. Parts of the Choptank River have been identified as impaired waters due to excessive nutrients and sediments under the Federal Clean Water Act. Seven river sites and fifteen subwatersheds in the northern portion of the watershed were intensively sampled for several years. Land use, agricultural management practices, and remote sensed data were collected for much of the watershed over the same period. Water quality parameters, dissolved oxygen, pH, salinity, and temperature were measured when samples were collected for nutrient, metal, and current-use pesticide analyses. Water samples were collected monthly for most analytes; for metals and some pesticide degradation products, samples were collected quarterly. In addition, several watersheds were selected for storm event sampling and more-intense, land use comparisons. Nutrient concentrations appear to correlate with agricultural land use. Arsenic compounds are commonly added to animal feed to control parasites and increase animal growth rates; preliminary results suggest that arsenic concentrations correlate with certain nutrients. Correlations between pesticide concentrations are somewhat more complicated and no single factor is responsible for their appearance in surface waters. However, nitrate is associated more closely with some pesticide degradation products than with others. These data are being utilized in modeling efforts for evaluating the conservation practices in the Choptank River Watershed.