Microbial driven iron reduction affects arsenic transformation and transportation in soil-rice system
Microbial driven iron reduction affects arsenic transformation and transportation in soil-rice system
复制标题
微生物驱动的铁还原影响土壤-水稻系统中砷的转化和运输
DOI：
10.1016/j.envpol.2020.114010
复制
发表时间：
2020
影响因子：
8.9
通讯作者：
Li Waichin
中科院分区：
文献类型：
--
作者：
Xue Shengguo;Jiang Xingxing;Wu Chuan;Hartley William;Qian Ziyan;Luo Xinghua;Li Waichin
微生物驱动的铁循环在土壤-水稻系统中砷的形态转化和迁移过程中起着重要作用。采用盆栽试验研究了土壤细菌铁还原过程对土壤-水稻系统中砷形态和迁移的影响。在水稻生长期间，土壤溶液pH值和电导率（EC）先升高后降低，变化范围分别为7.4-8.8和116.3-820 mS cm−1。根际和非根际土壤溶液中Fe、总As和As（III）的含量均随时间的增加而呈增加趋势。土壤溶液中Fe浓度与总As和As（III）浓度呈显著正相关（*p < 0.001）。根际土壤中砷还原酶基因（arsC）和As（III）S-腺苷甲硫氨酸甲基转移酶基因（arsM）的丰度高于非根际土壤，而铁还原菌（Geo）的丰度则表现出相反的趋势。此外，geo丰度分别与arsC（*p < 0.001）和arsM（**p < 0.01）基因的geo丰度呈显著正相关。Geo、ars、Candars、M基因丰度与土壤溶液中Fe、总As和As（III）浓度呈显著正相关（*p < 0.05）。此外，As、Candars、M基因丰度与水稻籽粒中总As和As（III）含量呈显著负相关（*P < 0.05）。这些结果表明，细菌铁还原过程与根系径向氧损失的相互作用促进了As的还原和甲基化，从而降低了水稻对As的吸收，为缓解水稻土As污染提供了理论依据。
The microbe-driven iron cycle plays an important role in speciation transformation and migration of arsenic (As) in soil-rice systems. In this study, pot experiments were used to investigate the effect of bacterial iron (Fe) reduction processes in soils on As speciation and migration, as well as on As uptake in soil-rice system. During the rice growth period, pH and electrical conductivity (EC) in soil solutions initially increased and then decreased, with the ranges of 7.4–8.8 and 116.3–820 mS cm−1, respectively. The concentrations of Fe, total As and As(III) showed an increasing trend in the rhizosphere and non-rhizosphere soil solutions with the increasing time. Fe concentrations were significantly positively correlated with total As and As(III) concentrations (***p < 0.001) in the soil solutions. The abundances of the arsenate reductase gene (arsC) and the As(III) S-adenosylmethionine methyltransferase gene (arsM) in rhizosphere soils were higher than those in non-rhizosphere soils, while the abundance of the Fe-reducing bacteria (Geo) showed an opposite trend. Moreover, it showed that theGeoabundance was significantly positively correlated with that of thearsC(***p < 0.001) andarsM(**p < 0.01) genes, respectively. The abundances ofGeo,arsCandarsMgenes were significantly positively correlated with the concentrations of Fe, total As and As(III) in the soil solutions (*p < 0.05). Moreover, the abundances ofarsCandarsMgenes were significantly negatively correlated with total As and As(III) in rice grains (*P < 0.05). These results showed that the interaction of bacterial Fe reduction process and radial oxygen loss from roots promoted the reduction and methylation of As, and then decreased As uptake by rice, which provided a theoretical basis for alleviating As pollution in paddy soils.