Arsenic in Ground Water Geochemistry and Occurrence by Alan H. Welch, Kenneth G. Stollenwerk

By Alan H. Welch, Kenneth G. Stollenwerk

Presents an outline of the elemental strategies that have an effect on arsenic prevalence and shipping via delivering adequate history details on arsenic geochemistry and outlines of high-arsenic flooring water. Of curiosity to scientists operating within the box of arsenic, wellbeing and fitness pros attracted to arsenic publicity, and water-resource managers and regulators.

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An example of indiscriminate averaging of equilibrium constants for the generation of tabulated thermodynamic properties was given previously by one of the authors (Archer, 1998). Such a problem arises with respect to the first dissociation constant of arsenious acid, Table 4 gives some of the equilibrium constant values found in the literature for the first deprotonation step. 15 K and all are standard-state values; this means that adjustments were made to some of the values given in the literature.

The absorption and/or emission of energy results from changes in quantized magnetic, rotational, vibrational, or electronic energy levels of atoms or molecules in the system. The external perturbation usually (but not always) takes the form of electromagnetic radiation. The widely used spectroscopic techniques of x-ray fluorescence and atomic absorptionspectrometry provide quantitative information about the elemental composition of a sample; other techniques, such as infrared, x-ray photoelectron, and x-ray absorption spectroscopy, provide quantitative or semi-quantitative elemental speciation of a sample.

The studies indicate that arsenic sorption on these minerals primarily occurs by two mechanisms: (1) Substitution for other oxoanions (such as carbonate or sulfate) during coprecipitation, and (2) Bonding through exchange with surface hydroxyl groups to structural metal ions during chemisorption. At least one study by Myneni (1995) suggests that mechanism (1) predominates when As is present during mineral formation, whereas mechanism (2) predominates when minerals are exposed to As-bearing solutions after their formation.

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