Zhang Zhennan, Yin Naiyi, Du Huili, Cai Xiaolin, Cui Yanshan
College of Resources and Environment, University of Chinese Academy of Sciences, Huaibei Village 380, Huaibei Town, Huairou District, Beijing, 101408, People's Republic of China; Research Center for Eco-environmental Sciences, Chinese Academy of Sciences, Shuangqing Road 18, Haidian District, Beijing, 100085, People's Republic of China.
College of Resources and Environment, University of Chinese Academy of Sciences, Huaibei Village 380, Huaibei Town, Huairou District, Beijing, 101408, People's Republic of China; Research Center for Eco-environmental Sciences, Chinese Academy of Sciences, Shuangqing Road 18, Haidian District, Beijing, 100085, People's Republic of China.
Chemosphere. 2016 May;151:108-15. doi: 10.1016/j.chemosphere.2016.02.065. Epub 2016 Mar 15.
Arsenic (As) is a redox-active metalloid whose toxicity and mobility in soil depend on its oxidation state. Arsenite [As(III)] can be oxidized by microbes and adsorbed by minerals in the soil. However, the combined effects of these abiotic and biotic processes are not well understood. In this study, the fate of arsenic in the presence of an isolated As(III)-oxidizing bacterium (Pseudomonas sp. HN-1, 10(9) colony-forming units (CFUs)·ml(-1)) and three iron oxides (goethite, hematite, and magnetite at 1.6 g L(-1)) was determined using batch experiments. The total As adsorption by iron oxides was lower with bacteria present and was higher with iron oxides alone. The total As adsorption decreased by 78.6%, 36.0% and 79.7% for goethite, hematite and magnetite, respectively, due to the presence of bacteria. As(III) adsorbed on iron oxides could also be oxidized by Pseudomonas sp. HN-1, but the oxidation rate (1.3 μmol h(-1)) was much slower than the rate in the aqueous phase (96.2 μmol h(-1)). Therefore, the results of other studies with minerals only might overestimate the adsorptive capacity of solids in natural systems; the presence of minerals might hinder As(III) oxidation by microbes. Under aerobic conditions, in the presence of iron oxides and As(III)-oxidizing bacteria, arsenic is adsorbed onto iron oxides within the adsorption capacity, and As(V) is the primary form in the solid and aqueous phases.
砷（As）是一种具有氧化还原活性的类金属，其在土壤中的毒性和迁移性取决于其氧化态。亚砷酸盐[As(III)]可被微生物氧化并被土壤中的矿物质吸附。然而，这些非生物和生物过程的综合影响尚未得到充分理解。在本研究中，通过批次实验确定了在分离出的As(III)氧化细菌（假单胞菌属HN-1，10⁹ 菌落形成单位（CFU）·ml⁻¹）和三种氧化铁（针铁矿、赤铁矿和磁铁矿，浓度为1.6 g L⁻¹）存在的情况下砷的归宿。存在细菌时，氧化铁对总砷的吸附较低，而单独使用氧化铁时吸附较高。由于细菌的存在，针铁矿、赤铁矿和磁铁矿对总砷的吸附分别降低了78.6%、36.0%和79.7%。吸附在氧化铁上的As(III)也可被假单胞菌属HN-1氧化，但氧化速率（1.3 μmol h⁻¹）远低于水相中的速率（96.2 μmol h⁻¹）。因此，仅涉及矿物质的其他研究结果可能高估了自然系统中固体的吸附能力；矿物质的存在可能会阻碍微生物对As(III)的氧化。在有氧条件下，在氧化铁和As(III)氧化细菌存在的情况下，砷在吸附容量范围内被吸附到氧化铁上，并且As(V)是固相和水相中的主要形态。
