http://netedu.xauat.edu.cn/jpkc/netedu/jpkc2009/szylyybh/content/wlzy/1/Review%20of%20Arsenic%20in%20natural%20water%20-%20Smedly.pdf

A review of the source, behaviour and distribution of arsenic in natural waters

Biogeochemistry of landfill leachate plumes

: Geochemical reaction path modeling is useful for rapidly assessing the extent of water-aqueous-gas interactions both in natural systems and in industrial processes. Modeling of some systems, such as those at low temperature with relatively high hydrologic flow rates, or those perturbed by the subsurface injection of industrial waste such as CO2 or H2S, must account for the relatively slow kinetics of mineral-gas-water interactions. We have therefore compiled parameters conforming to a general Arrhenius-type rate equation, for over 70 minerals, including phases from all the major classes of silicates, most carbonates, and many other non-silicates. These data have been added to a computer code that simulates an infinitely well-stirred batch reactor, allowing computation of mass transfer as a function of time. Actual equilibration rates are expected to be much slower than those predicted by the selected computer code, primarily because actual geochemical processes commonly involve flow through porous or fractured media, wherein the development of concentration gradients in the aqueous phase near mineral surfaces, which results in decreased absolute chemical affinity and slower reaction rates. Further differences between observed and computed reaction rates may occur because of variables beyond the scope of most geochemical simulators, such as variation in grain size, aquifer heterogeneity, preferred fluid flow paths, primary and secondary mineral coatings, and secondary minerals that may lead to decreased porosity and clogged pore throats.

/pdf/a-compilation-of-rate-parameters-of-water-mineral-1o9qltikkk.pdf

A Compilation of Rate Parameters of Water-Mineral Interaction Kinetics for Application to Geochemical Modeling

Concentrations of naturally occurring arsenic in ground water vary regionally due to a combination of climate and geology Although slightly less than half of 30,000 arsenic analyses of ground water in the United States were 1 μg/L, about 10% exceeded 10 μg/L At a broad regional scale, arsenic concentrations exceeding 10 μg/L appear to be more frequently observed in the western United States than in the eastern half Arsenic concentrations in ground water of the Appalachian Highlands and the Atlantic Plain generally are very low ( 1 μg/L) Concentrations are somewhat greater in the Interior Plains and the Rocky Mountain System Investigations of ground water in New England, Michigan, Minnesota, South Dakota, Oklahoma, and Wisconsin within the last decade suggest that arsenic concentrations exceeding 10 μg/L are more widespread and common than previously recognized

Arsenic release from iron oxide appears to be the most common cause of widespread arsenic concentrations exceeding 10 μg/L in ground water This can occur in response to different geochemical conditions, including release of arsenic to ground water through reaction of iron oxide with either natural or anthropogenic (ie, petroleum products) organic carbon Iron oxide also can release arsenic to alkaline ground water, such as that found in some felsic volcanic rocks and alkaline aquifers of the western United States Sulfide minerals are both a source and sink for arsenic Geothermal water and high evaporation rates also are associated with arsenic concentrations 10g/L in ground and surface water, particularly in the west

Arsenic in Ground Water of the United States: Occurrence and Geochemistry

Arsenic toxicity, health hazards and removal techniques from water : an overview

Pyrite oxidation in carbonate-buffered solution: 1. Experimental kinetics

Arsenic species as an indicator of redox conditions in groundwater

Acid production in sulphidic tailings can cause severe degradation of water quality in both subsurface and surface systems. The availability of gaseous oxygen and the rate of diffusion of oxygen th...

Ronald V. Nicholson

Papers

Pyrite oxidation in carbonate-buffered solution: 1. Experimental kinetics

Arsenic species as an indicator of redox conditions in groundwater

Reduction of acid generation in mine tailings through the use of moisture-retaining cover layers as oxygen barriers

Pyrite oxidation in carbonate-buffered solution: 2. Rate control by oxide coatings

Pyrrhotite reaction kinetics: Reaction rates for oxidation by oxygen, ferric iron, and for nonoxidative dissolution