Ascar Loreto, Ahumada Inés, Richter Pablo
Departamento de Química Inorgánica y Analítica, Facultad de Cs. Químicas y Farmacéuticas, Universidad de Chile, Casilla 233, Santiago, Chile.
Departamento de Química Inorgánica y Analítica, Facultad de Cs. Químicas y Farmacéuticas, Universidad de Chile, Casilla 233, Santiago, Chile.
Chemosphere. 2008 Aug;72(10):1548-1552. doi: 10.1016/j.chemosphere.2008.04.056. Epub 2008 Jun 12.
A study was done on the influence of redox potential on the mobility and availability of the various arsenic chemical forms in a Mollisol soil from central Chile amended with biosolid. Arsenic availability was strongly dependent on the applied redox potential. As expected, under reducing conditions (-200 mV vs Hg/Hg(2)Cl(2)) arsenic availability increased significantly, and arsenic was found mainly as arsenite. On the contrary under oxidizing conditions (200 mV vs Hg/Hg(2)Cl(2)) arsenic solubility decreased markedly and was governed by the presence of arsenate. The greatest concentration of organic arsenic species was found under reducing conditions, which would indicate that methylated species may participate in the transformation of arsenate to arsenite. In biosolid-amended soils the concentrations of methylated species increased as a function of time under reducing conditions, which can be attributed to the greater microbial activity resulting from the organic matter supply from the biosolid to soil. In all the systems, a high concentration of As(V) was found under reducing conditions, indicating that the chemical kinetics for the conversion of arsenate to arsenite is slow. Along time, the content of As(V) increased in the control soils, which may be attributed to the possible dissolution of iron oxides and hydroxides under reducing conditions.
开展了一项研究，探究氧化还原电位对智利中部一种添加了生物固体的软土中各种砷化学形态的迁移性和有效性的影响。砷的有效性强烈依赖于施加的氧化还原电位。正如预期的那样，在还原条件下（相对于Hg/Hg₂Cl₂为 -200 mV），砷的有效性显著增加，并且砷主要以亚砷酸盐的形式存在。相反，在氧化条件下（相对于Hg/Hg₂Cl₂为200 mV），砷的溶解度显著降低，并且受砷酸盐的存在控制。在还原条件下发现了最高浓度的有机砷形态，这表明甲基化形态可能参与了砷酸盐向亚砷酸盐的转化。在添加了生物固体的土壤中，在还原条件下，甲基化形态的浓度随时间增加，这可归因于生物固体向土壤提供的有机物质导致微生物活性增强。在所有系统中，在还原条件下都发现了高浓度的As(V)，这表明砷酸盐向亚砷酸盐转化的化学动力学较慢。随着时间推移，对照土壤中As(V)的含量增加，这可能归因于还原条件下铁氧化物和氢氧化物可能的溶解。
