Peggy A. O'Day

TL;DR: Spectroscopic evidence shows that arsenic does not substitute for iron or sulfur in iron sulfide minerals at the molecular scale, and a general geochemical model derived from field and spectroscopic observations shows that the ratio of reactive iron to sulfur in the system controls the distribution of solid phases capable of removing arsenic from solution when conditions change from oxidized to reduced.

TL;DR: Arsenian pyrite, formed during Cretaceous gold mineralization, is the primary source of As along the Melones fault zone in the southern Mother Lode Gold District of California.

TL;DR: In this paper, the authors test the accuracy of experimental and theoretical EXAFS standard functions in determining the number of backscattering atoms (N) at a distance (R) beyond the ligating shell of the central absorber atom where effects from disorder, multiple-scattering, and overlapping shells of atoms may significantly influence the X-ray spectra.

TL;DR: Results from this study show that under conditions applicable to drinking water treatment, arsenate removal by zero-valent iron media involves surface complexation only and does not involve reduction to metallic arsenic.

TL;DR: In this paper, a suite of 27 common, Fe-bearing reference compounds, including sulfides, carbonates, phosphates, oxides, oxyhydroxides, and phyllosilicates, was analyzed to empirically assess the utility of X-ray absorption near-edge structure (XANES) and extended Xray absorption fine structure (EXAFS) for identifying a particular Fe mineral (or class of minerals) in a soil or sediment mixture.