The US Geological Survey is offering a funding opportunity to a CESU partner for research on applications of isotopic and elemental geochemistry to ecologic as well as surface and groundwater hydrologic problems. Essential components of the funding opportunity are: 1) student, faculty, and laboratory support for application, refinement, and development of geochemical methods, that 2) address solute and water sources and transport pathways, through 3) application of a wide range of stable and radioisotopic systems (ranging from hydrogen, helium, and lithium through uranium and lead), by 4) analysis of the isotopic and elemental composition of diverse sample media (including plant and animal tissue, sediment, rock, and aqueous phases, especially high salinity brine).