1. Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543-1543, Department of Biochemistry, Cambridge University, Building O Downing Site, Cambridge CB3 9EU, United Kingdom, Department of Earth and Planetary Sciences, Massachusetts Institute of Technology, E34-209, Cambridge, Massachusetts 02139, Department of Chemistry, Pennsylvania State University, University Park, Pennsylvania 16802, and Marine Life Research Group, Scripps Institution of...