The Mars Global Surveyor, Mars Exploration Rover, and Mars Express missions have stimulated considerable thinking about the surficial geochemical evolution of Mars. Among the major recent mission findings are the presence of jarosite (a ferric sulfate salt), which requires formation from an acid-sulfate brine, and the occurrence of hematite and goethite on Mars. Recent ferric iron models have l...

Although iron is an essential mineral in the homeostasis and functioning of multiple organ systems, its use as a therapeutic entity should be reserved for people with bona fide irondeficiency anemia. Especially when it is added onto preexisting polypharmacy in older adults, iron can subject patients to a plethora of dose-related side effects and drug interactions. Judicious use of laboratory st...

Injection of organic carbon into the subsurface as an electron donor for bioremediation of redox-sensitive contaminants like uranium often leads to mineral transformation and biomass accumulation, both of which can alter the flow field and potentially bioremediation efficacy. This work combines reactive transport modeling with a column experiment and field measurements to understand the biogeoc...

[1] Iron-hydroxysulfate minerals can be important hosts for metals such as lead, mercury, copper, zinc, silver, chromium, arsenic, and selenium and for radionuclides such as Ra. These mineral-bound contaminants are considered immobilized under oxic conditions. However, when anoxic conditions develop, the activities of sulfateor iron-reducing bacteria could result in mineral dissolution, releasi...

Lead (Pb) solubility is commonly limited by dissolution–precipitation reactions of secondary mineral phases in contaminated soils and water. In the research described here, Pb free Pb2+ ion activities were measured following precipitation minerals from aqueous solutions containing sulfate or carbonate a 1:5 mole ratio absence presence phosphate over pH range 4.0–9.0. Using X-ray diffraction Fou...

Two hundred and sixteen weanling gilts (6.65+/-0.08 kg) were used to determine the effects of decreasing supplemental concentrations of Zn, Cu, Fe, and Mn, and trace mineral source (inorganic vs. chelated) on growth performance, mineral status, and fecal mineral concentrations from weaning through development. The study was conducted over three trials with 72 pigs in each trial. Gilts were bloc...

The possibility that sulfate-reducing microorganisms contribute to U(VI) reduction in sedimentary environments was investigated. U(VI) was reduced to U(IV) when washed cells of sulfate-grown Desulfovibrio desulfuricans were suspended in a bicarbonate buffer with lactate or H2 as the electron donor. There was no U(VI) reduction in the absence of an electron donor or when the cells were killed by...

A diffusive gradient in thin films (DGT) technique, based on a strongly basic anion exchange resin (Amberlite IRA-400), was successfully tested for 34S/32S analysis in labile soil sulfate. Separation of matrix elements (Na, K, and Ca) that potentially cause non-spectral interferences in 34S/32S analysis by MC ICP-MS (multi-collector inductively coupled plasma-mass spectrometry) during sampling ...

This proposal outlines a program of scientific research and educational development focused on mineral dust aerosol, atmospheric chemistry, and curricular use of satellite data. Mineral dust impacts the chemical composition of the atmosphere by providing a surface for heterogeneous chemistry, and for light scattering and absorption at photolytic wavelengths. We propose to assess the current and...