1. Department of Geological Sciences, The University of Texas at El Paso, El Paso, Texas 79968, United States
2. Geomicrobiology, Center for Applied Geosciences, University of Tuebingen, 72076 Tuebingen, Germany
3. Department of Chemistry, Colorado School of Mines, Golden, Colorado 80401, United States
4. Department of Environmental Sciences, Western Washington University, Bellingham, Washington 98225, United States