1. National Exposure Research Laboratory, U.S. Environmental Protection Agency, 960 College Station Rd., Athens, Georgia 30605, United States
2. Water Chemistry Department, Federal Institute of Hydrology (BfG), Am Mainzer Tor 1, D-56068, Koblenz, Germany
3. College of Agricultural, Consumer, and Environmental Sciences, Department of Crop Sciences, and the NSF WaterCAMPWS Center, University of Illinois at Urbana−Champaign, Urbana, Illinois 61801, United States