This analytical facility is housed at the Lamont-Doherty Earth Observatory of Columbia University. The Biogeochemistry Core primarily supports two biomedical projects and three non-biomedical projects, with additional support for the Community Engagement Core and the Research Translation Core. This support includes the analysis of ~24,000 groundwater samples by high-resolution inductively-couples mass spectrometry not only for As and Mn, on behalf of biomedical Projects 1 and 2, but also analysis of groundwater and sediment leaches for Na, Mg, Al, Si, P, S, K, Ca, Cr, Fe, Ni, Co, Cu, Zn, Mo, Cd, Sb, Ba, Pb and U on behalf of non-biomedical Projects 4, 5, 6, as well as the Community Engagement Core and the Research Translation Core. Core C also supports the analysis of exhaled breath condensate samples by liquid chromatography mass spectrometry for biomarkers collected for Project 2 and the determination of As speciation in a subset of groundwater and laboratory samples for the non-biomedical projects. For the analysis of the bulk chemistry of sediments from US Superfund sites and Bangladesh, the application of the latest generation of hand-held X-ray fluorescence analyzers will be systematically evaluated. Bulk organic carbon measurements in groundwater and sediment will also be supported under Core C.