作者：XiaofengZhang,TongxuLiu,FangbaiLi,XiaominLi,YanhongDu,HuanyunYu,XiangqinWang,ChuanpinLiu,MiFeng,BingLiao 单位：GuangzhouInstituteofGeochemistry,ChineseAcademyofSciences；GuangdongKeyLaboratoryofIntegratedAgro-environmentalPollutionControlandManagement,GuangdongInstituteofEco-environmentalScience&Technology；UniversityofChineseAcademyofSciences；National-RegionalJoint 本文刊于： 《Journal of Environmental Sciences》 2021年第02期
关键词:
Antimony Nitrate MicrobialSb(Ⅲ)oxidationKeywords
Antimony, Nitrate, Microbial Sb(Ⅲ) oxidation, Rice, Paddy soil
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摘要
Nitrate（NO3-） is known to be actively involved in the processes of mineralization and heavy metal transformation; however, it is unclear whether and how it affects the bioavailability of antimony（Sb） in paddy soils and subsequent Sb accumulation in rice. Here, the effects of NO3-on Sb transformation in soil-rice system were investigated with pot experiments over the entire growth period. Results demonstrated that NO3-reduced Sb accumulation in brown rice by 15.6% compared to that in the control. After amendment with NO3-, the Sb content in rice plants increased initially and then gradually decreased（in roots by 46.1%）. During the first 15 days, the soil p H increased, the oxidation of Sb（Ⅲ） and sulfides was promoted, but the reduction of iron oxide minerals was inhibited, resulting in the release of adsorbed and organic-bound Sb from soil. The microbial arsenite-oxidizing marker gene aox B played an important role in Sb（Ⅲ） oxidation. From days 15 to 45, after NO3-was partially consumed, the soil p H decreased, and the reductive dissolution of Fe（Ⅲ）-bearing minerals was enhanced; consequently, iron oxide-bound Sb was transformed into adsorbed and dissolved Sb species. After day 45, NO3-was completely reduced, Sb（V） was evidently reduced to Sb（Ⅲ）, and green rust was generated gradually. Thus, the available Sb decreased due to its enhanced affinity for iron oxides. Moreover, NO3-inhibited the reductive dissolution of iron minerals, which ultimately caused low Sb availability. Therefore, NO3-can chemically and biologically reduce the Sb availability in paddy soils and alleviate Sb accumulation inrice. This study provides a potential strategy for decreasing Sb accumulation in rice in the Sb-contaminated sites.
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