State Key Lab of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, People's Republic of China; University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China.
Jiaxing Academy of Agricultural Sciences, Xiuzhou District, Jiaxing 314016, People's Republic of China.
Environ Pollut. 2018 May;236:598-608. doi: 10.1016/j.envpol.2018.01.099.
Arsenic (As) contamination is a global problem. Straw incorporation is widely performed in As contaminated paddy fields. To understand how straw and straw biochar incorporation affect As transformation and translocation in the soil-microbe-rice system, a pot experiment was carried out with different dosages of rice straw and straw biochar application. Results showed that both straw biochar and straw application significantly increased As mobility. Straw biochar mobilized As mainly through increasing soil pH and DOM content. Straw incorporation mainly through enhancing As release from iron (Fe) minerals and arsenate (As(V)) reduction to arsenite (As(III)). Straw biochar didn't significantly affect As methylation, while straw incorporation significantly enhanced As methylation, elevated dimethylarsenate (DMA) concentration in soil porewater and increased As volatilization. Straw biochar didn't significantly change total As accumulation in rice grains, but decreased As(III) accumulation by silicon (Si) inhibition. Straw incorporation significantly increased DMA, but decreased As(III) concentration in rice grains. After biochar application, dissolved As was significantly positively correlated with the abundance of Bacillus, indicating that Bacillus might be involved in As release, and As(III) concentration in polished grains was negatively correlated with Si concentration. The significant positive correlation between dissolved As with Fe and the abundance of iron-reducing bacteria suggested the coupling of As and Fe reduction mediated by iron-reducing bacteria. The significant positive correlation between DMA in rice grains and the abundance of methanogenic bacteria indicated that methanogenic bacteria could be involved in As methylation after straw application. The results of this study would advance the understanding how rice straw incorporation affects As fate in soil-microbe-rice system, and provide some guidance to straw incorporation in As contaminated paddy soil. This study also revealed a wealth of microorganisms in the soil environment that dominate As mobility and transformation after straw incorporation.
砷（As）污染是一个全球性问题。稻草的掺入在受砷污染的稻田中被广泛应用。为了了解稻草和稻草生物炭的掺入如何影响土壤-微生物-水稻系统中的砷转化和迁移，进行了一项不同稻草和稻草生物炭用量的盆栽实验。结果表明，稻草生物炭和稻草的施用均显著增加了砷的迁移性。稻草生物炭通过增加土壤 pH 值和 DOM 含量来活化砷。稻草的掺入主要通过增强铁（Fe）矿物的砷释放和砷酸盐（As(V)）还原为亚砷酸盐（As(III)）来实现。稻草生物炭对砷的甲基化没有显著影响，而稻草的掺入显著增强了砷的甲基化，提高了土壤孔隙水中的二甲砷酸盐（DMA）浓度，并增加了砷的挥发。稻草生物炭对稻米中总砷的积累没有显著影响，但通过硅（Si）抑制降低了 As(III)的积累。稻草的掺入显著增加了 DMA，但降低了稻米中 As(III)的浓度。生物炭施用后，溶解态砷与芽孢杆菌的丰度呈显著正相关，表明芽孢杆菌可能参与了砷的释放，而精米中 As(III)的浓度与 Si 浓度呈负相关。溶解态砷与 Fe 的显著正相关以及铁还原菌的丰度表明，铁还原菌介导的 As 和 Fe 还原过程存在耦合。稻米中 DMA 与产甲烷菌的丰度呈显著正相关，表明稻草施用后产甲烷菌可能参与了 As 甲基化。本研究将有助于深入了解稻草的掺入如何影响土壤-微生物-水稻系统中的砷命运，并为受砷污染稻田中的稻草掺入提供一些指导。本研究还揭示了土壤环境中丰富的微生物，这些微生物在稻草掺入后主导着砷的迁移和转化。
