[1] A seasonal analysis assesing variations in the oxygen isotopic composition of dissolved inorganic phosphate (DIP) was conducted in the San Francisco Bay estuarine system, California. Isotopic fractionation of oxygen in DIP (exchange of oxygen between phosphate and environmental water) at surface water temperatures occurs only as a result of enzyme-mediated, biological reactions. Accordingly...

[1] We present a global model to infer past biosphere productivity using the record of triple isotopic composition of atmospheric oxygen. Our model incorporates recent determinations of the mass-dependent relationships between dO and dO associated with leaf transpiration and various O2 uptake processes. It also considers the spatial and seasonal variations of vegetation distribution, climatic c...

Carbonates of the Ojo Huelos Member of the San Pedro Arroyo Formation include ostracodal limestones, brecciated micritic limestones, vuggy, mottled limestones, peloidal graistones/packstones, pisolitic rudstones and nodular limestones. These lithofacies record deposition in lacustrine, palustrine and alluvial environments. Lacustrine (ostracodal) limestones are isotopically heaviest, with nodul...

Time resolved data on the carbon isotopic composition of carbonate minerals and the sulfur isotopic composition or sulfate minerals show a strong negative correlation during the Cretaceous. Carbonate minerals are isotopically heavy during this period while sulfate minerals are isotopically light. The implication is that carbon is being transferred from the oxidized, carbonate reservoir to the r...

A procedure was developed that allows precise determination of molybdenum isotope abundances in natural samples. Purification of molybdenum was first achieved by solvent extraction using di(2-ethylhexyl) phosphate. Further separation of molybdenum from isobar nuclides was obtained by ion chromatography using AG1-X8 strongly basic anion exchanger. Finally, molybdenum isotopic composition was mea...

This contribution presents the hydrochemical and isotopic characterisation of the phreatic aquifer located in the Partido de la Costa, province of Buenos Aires, Argentina. In the sand-dune barrier geomorphological environment, groundwater is mainly a low-salinity Ca-HCO3 and Na-HCO3-type, being in general suitable for drinking, whereas in the continental plain (silty clay sediments), groundwate...

We use a newly developed method, based on the original Brownian shape motion (BSM) model, to calculate fission-fragment isotopic yields Y(Z,N). Recent measurements of post-neutron distributions with better than 1 u resolution make it possible, for first time, test in detail this model. here report comparison between measured and calculated average neutron number as function proton number, w...