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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Soil Science Society of America journal 63 (1999), S. 1149-1156 
    ISSN: 1435-0661
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: 2 HAsO4 and Na2HPO4 and incubated under a N2 atmosphere for 41 d, and then reaerated for 7 d. Subsamples were collected intermittently and dissolved As, Fe, Mn, Ca, S, P, and H3AsO3 concentrations were determined. Arsenic speciation in the soil solids was determined after 14 and 41 d of flooding and then after 13 h of aeration by X-ray absorption near edge structure (XANES) spectroscopy. Arsenic sorption was small under anaerobic conditions, and H2PO− 4 additions enhanced As(V) reduction rate in both soils and slightly suppressed As sorption in one soil. Arsenopyrite (FeAsS) was identified in the soil solids. Rapid and simultaneous As sorption and Fe precipitation occurred during the first 0.25 d of aeration, suggesting that As was retained on freshly precipitated Fe (hydr)oxides. Manganese precipitation and concomitant As sorption occurred after 1 d of aeration. Arsenopyrite was largely destroyed upon aeration but As(III) persisted. Thus, As is partitioned into the solid phase under both aerobic and anaerobic conditions, although more appreciably under the aerobic conditions of this study, and P has little influence on dissolved As during soil flooding–aeration cycles.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Soil Science Society of America journal 62 (1998), S. 1530-1537 
    ISSN: 1435-0661
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Mining activities and arsenical pesticide applications can introduce arsenate compounds into soils and sediments. Under water-saturated (flooded) soil conditions, arsenate solids are subjected to biotically generated reducing conditions and may undergo reductive dissolution. While thermodynamic calculations have been used to predict the conditions under which mineral-associated As undergoes reduction, there is relatively little data from systems in which well-characterized arsenate solids have been subjected to reducing conditions, and a limited amount of information about the reduction of mineral-bound arsenate. In this study, the behavior of five arsenates was observed under reducing conditions generated by flooded soils. The apparent solubility of the arsenates decreased in the order CaHAsO4 = Na2HasO4\cdot2H2O 〉 AlAsO4\cdot2H2O 〉 MnHAsO4 〉 FeAsO4\cdot2H2O under oxic conditions; under anoxic conditions (redox potential 〈0 m V) the apparent solubility was FeAsO4\cdot2H2O ≥CaHAsO4 = Na2HasO4\cdot7H2O 〉 AlAsO4\cdot2H2O 〉 MnHAsO4. Calcium and sodium arsenates completely dissolved under the initial oxidizing conditions. X-ray absorption near-edge structure (XANES) spectroscopy indicated that As in AlAsO4\cdot2H2O rapidly transformed to solid-phase As(III). Manganese arsenate yielded the least solution and solid-phase As(III) of all of the minerals. Iron arsenate underwent reductive dissolution, releasing As(III) to solution and solid phases, and thus may yield solution or solid-phase As(III) if prolonged anoxic conditions prevail.
    Type of Medium: Electronic Resource
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