John Christensen graduated from UC Berkeley with a BA in geology, and received his Masters and Ph.D. in geology from the University of California, Los Angeles. He did post-doctoral work at the University of Michigan’s Dept. of Geological Sciences and stayed on as research scientist before joining the LBNL Earth Sciences Division in 1999. In 2006 he became a staff scientist. John is an isotopic geochemist who uses MC-ICPMS and TIMS to develop techniques he uses in a wide variety of research, including basic science as well as problems in environmental science and environmental remediation.