Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, PR China; University of Chinese Academy of Sciences, Beijing 100049, PR China.
Department of Chemical, Biochemical and Environmental Engineering, University of Maryland Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250, USA.
Sci Total Environ. 2017 Dec 31;607-608:132-140. doi: 10.1016/j.scitotenv.2017.07.015. Epub 2017 Jul 27.
Roxarsone (ROX) is transformed to more toxic arsenicals after land application of ROX-containing poultry litter to agricultural soils. To date, no reports have compared ROX degradation in soils with contrasting properties. In this study, the impact of different incubation conditions on ROX degradation was investigated in red (C-Soil) and yellow-brown (H-Soil) soils. The degradation half-lives of extractable ROX in C-Soil and H-Soil were found to be 130-394d and 4-94d, respectively, indicating that the extractable ROX degraded faster in H-Soil. This result stems from the higher organic matter content, more abundant soil microbes, and lower ROX sorption capacity of H-Soil compared to C-Soil. Degradation of extractable ROX in both C-Soil and H-Soil was significantly promoted by soil moisture and exogenous glucose. Exogenous P(V) facilitated degradation of extractable ROX in C-Soil, but limited effects were observed for H-Soil. HPLC-ICP-MS analysis confirmed that ROX and dimethylarsinic acid were the predominant As species in soil extracts from 119-day incubated C-Soil and H-Soil, respectively. Ultimately, minimal transformation of extractable ROX was observed in C-Soil, but the majority of extractable ROX in H-Soil was biologically transformed. The differences in degradation of extractable ROX in C-Soil and H-Soil highlight the key roles of soil properties on the environmental fate of ROX and associated arsenicals. Results from this study inform the need for comprehensive evaluation of the ecological risks in organoarsenical-contaminated soils.
罗沙砷（ROX）在含 ROX 的家禽粪便施用于农业土壤后会转化为更具毒性的砷化物。迄今为止，尚无报告比较过具有不同性质的土壤中 ROX 的降解情况。在这项研究中，研究了不同的孵育条件对红土（C-土壤）和黄棕壤（H-土壤）中 ROX 降解的影响。发现 C-土壤和 H-土壤中可提取 ROX 的降解半衰期分别为 130-394d 和 4-94d，这表明可提取 ROX 在 H-土壤中降解得更快。这一结果源于 H-土壤中较高的有机质含量、更丰富的土壤微生物和较低的 ROX 吸附能力。土壤水分和外源葡萄糖显著促进了 C-土壤和 H-土壤中可提取 ROX 的降解。外源 P(V)促进了 C-土壤中可提取 ROX 的降解，但对 H-土壤的影响有限。HPLC-ICP-MS 分析证实，ROX 和二甲基砷酸分别是 119 天孵育的 C-土壤和 H-土壤土壤提取物中的主要砷化物。最终，C-土壤中可提取 ROX 的转化很少，但 H-土壤中大部分可提取 ROX 被生物转化。C-土壤和 H-土壤中可提取 ROX 降解的差异突出了土壤性质对 ROX 和相关砷化物环境归宿的关键作用。这项研究的结果表明，需要对含有机砷污染土壤的生态风险进行全面评估。
