Effect of fulvic acid on neodymium uptake by goethite.

Experimental studies of the interaction of aqueous neodymium (Nd), Suwannee River fulvic acid (FA), and solid phase goethite were conducted. Results from blank systems (individual Nd and FA), binary systems (Nd-goethite, FA-goethite, and Nd-FA), and ternary systems (Nd-FA-goethite) at 0.1 mol/kg and 25°C are reported.

Ecophysiology and geochemistry of microbial arsenic oxidation within a high arsenic, circumneutral hot spring system of the Alvord Desert.

Microbial metabolism of arsenic has gained considerable interest, due to the potential of microorganisms to drive arsenic cycling and significantly influence the geochemistry of naturally arsenic-rich or anthropogenically arsenic-polluted environments. Alvord Hot Spring in southeastern Oregon is a circumneutral hot spring with an average arsenic concentration of 4.5 mg L(-1) (60 microM).

Mineral-fluid interaction in the lungs: insights from reaction-path modeling.

Thermodynamic modeling, in conjunction with available kinetic information, has been employed to investigate the fate of chrysotile and tremolite in the human lung. In particular, we focus on mineral-fluid reactions using techniques borrowed from geochemistry, including calculation of saturation indices, activity-ratio phase diagrams, and reaction-path modeling. Saturation index calculations show that fresh lung fluid is undersaturated with respect to both tremolite and chrysotile and these minerals should dissolve, in accordance with conclusions from previous work described in the literature.

A Raman spectroscopic study of arsenite and thioarsenite species in aqueous solution at 25°C.

The Raman spectra of thioarsenite and arsenite species in aqueous solution were obtained at room temperature. Solutions at constant ΣAs + ΣS of 0.1 and 0.

Experimental determination of the hydrothermal solubility of ReS and the Re-ReO buffer assemblage and transport of rhenium under supercritical conditions.

To understand the aqueous species important for transport of rhenium under supercritical conditions, we conducted a series of solubility experiments on the Re-ReO buffer assemblage and ReS. In these experiments, pH was buffered by the K-feldspar-muscovite-quartz assemblage; in sulfur-free systems was buffered by the Re-ReO assemblage; and and in sulfur-containing systems were buffered by the magnetite-pyrite-pyrrhotite assemblage. Our experimental studies indicate that the species ReCl is dominant at 400°C in slightly acidic to near-neutral, and chloride-rich (total chloride concentrations ranging from 0.