1. National Exposure Research Laboratory, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina 27711, National Risk Management Research Laboratory, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina 27711, Nicholas School of the Environment, Duke University, Durham, North Carolina 27708-0328, Centre for Ecology and Hydrology (CEH) Edinburgh, Bush Estate, Penicuik, EH26 0QB, United Kingdom, and Department of Soil Science, North Carolina State University,...