Wen Mengtuo, Liu Yaci, Zhang Qiulan, Liu Changli, Li Yasong, Yang Yuqi
Institute of Hydrogeology and Environmental Geology, Chinese Academy of Geological Sciences, Shijiazhuang, 050061, PR China; Fujian Provincial Key Laboratory of Water Cycling and Eco-Geological Processes, Xiamen, 361000, PR China; School of Water Resources and Environment, China University of Geosciences (Beijing), Beijing 100083, PR China.
Institute of Hydrogeology and Environmental Geology, Chinese Academy of Geological Sciences, Shijiazhuang, 050061, PR China; Fujian Provincial Key Laboratory of Water Cycling and Eco-Geological Processes, Xiamen, 361000, PR China.
Chemosphere. 2023 Jan;311(Pt 2):137118. doi: 10.1016/j.chemosphere.2022.137118. Epub 2022 Nov 3.
Roxarsone (3-nitro-4-hydroxyphenylarsonic acid, ROX), widely used as a livestock feed additive, is excreted untransformed in large concentrations. Accumulation of this manure in the open environment increases dissolved organic matter (DOM) and ROX in soil within the aeration zone. And microbial action plays a dominant role in the transformation of ROX. However, the specific effect of DOM on the biotransformation of ROX is not known. In this paper, we investigated the transformation rate, metabolite content, and microbial community response of ROX in soils with different DOM concentrations (71.61, 100, 200, 500, and 800 mg L). The transformation of ROX was consistent with first-order transformation kinetics. DOM promoted the transformation of ROX, and with high DOM (DOM ≥200 mg L), ROX was transformed almost completely within two days. In this case, DOM provided nutrients to microorganisms and promoted their growth, accelerating the transformation of ROX. Also, the solubility of ROX was enhanced by DOM to increase its bioavailability. The microbial diversity was negatively correlated with DOM concentration and ROX transformation time; during the transformation of ROX, Bacillus, Arthrobacter, Enterococcus, Acinetobacter, and Pseudomonas became dominant in the soil with anomalously high levels of DOM. This study demonstrates the transformation process of ROX under actual environmental conditions where organic matter coexists with ROX, and this understanding is important for the prevention and control of arsenic pollution in soil within the aeration zone with anomalously high levels of DOM.
洛克沙胂（3-硝基-4-羟基苯胂酸，ROX）作为一种广泛使用的家畜饲料添加剂，会以未转化的形式大量排泄出来。这种粪便在露天环境中的积累增加了通气区内土壤中的溶解有机物（DOM）和ROX含量。微生物作用在ROX的转化过程中起主导作用。然而，DOM对ROX生物转化的具体影响尚不清楚。在本文中，我们研究了不同DOM浓度（71.61、100、200、500和800mg/L）土壤中ROX的转化率、代谢物含量和微生物群落响应。ROX的转化符合一级转化动力学。DOM促进了ROX的转化，在高DOM（DOM≥200mg/L）条件下，ROX在两天内几乎完全转化。在这种情况下，DOM为微生物提供营养并促进其生长，加速了ROX的转化。此外，DOM提高了ROX的溶解度，增加了其生物利用度。微生物多样性与DOM浓度和ROX转化时间呈负相关；在ROX转化过程中，芽孢杆菌属、节杆菌属、肠球菌属、不动杆菌属和假单胞菌属在DOM含量异常高的土壤中成为优势菌属。本研究揭示了在实际环境条件下，当有机物与ROX共存时ROX的转化过程，这一认识对于防控通气区内DOM含量异常高的土壤中的砷污染具有重要意义。
