1. Department of Land, Air and Water Resources, University of California, Davis, California 95616, United States
2. Department of Geosciences and The Earth & Environmental Systems Institute, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
3. Geophysical Laboratory, Carnegie Institution of Washington, 5251 Broad Branch Road, Washington, D.C. 20008, United States
4. Department of Earth and Planetary Sciences, Johns Hopkins University, Baltimore, Maryland 21218, United States
5. Department of Plant and Soil Sciences and Center for Critical Zone Research, The University of Delaware, Newark, Delaware 19716, United States