Influence of redox potential (Eh) on the availability of arsenic species in soils and soils amended with biosolid

• Published in: Chemosphere (Oxford) 2008-08, Vol.72 (10), p.1548-1552
• Main Authors: Ascar, Loreto, Ahumada, Inés, Richter, Pablo
• Format: Article
• Language: English
• Subjects: Agronomy. Soil science and plant productions; Applied sciences; arsenic; Arsenic - chemistry; Arsenic species; Biological and medical sciences; Biological and physicochemical properties of pollutants. Interaction in the soil; biosolids; Central Chile; Chile; Earth sciences; Earth, ocean, space; Engineering and environment geology. Geothermics; Exact sciences and technology; Fundamental and applied biological sciences. Psychology; General agronomy. Plant production; microbial activity; Mobility; Mollisols; Other industrial wastes. Sewage sludge; Other nutrients. Amendments. Solid and liquid wastes. Sludges and slurries; Oxidation-Reduction; Pollution; Pollution, environment geology; redox potential; Sewage sludge; soil; Soil - analysis; soil amendments; Soil and sediments pollution; Soil Pollutants - chemistry; Soil-plant relationships. Soil fertility. Fertilization. Amendments; Wastes
• ISSN: 0045-6535; 1879-1298
• DOI: 10.1016/j.chemosphere.2008.04.056

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 (−200mV vs Hg/Hg2Cl2) arsenic availability increased significantly, and arsenic was found mainly as arsenite. On the contrary under oxidizing conditions (200mV vs Hg/Hg2Cl2) 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.