Institute of Soil and Water Resources and Environmental Science, Zhejiang Provincial Key Laboratory of Agricultural Resources and Environment, Zhejiang University, 866 Yuhangtang Road, Hangzhou, 310058, China.
School of Metallurgy and Environment, Central South University, Changsha, 410083, China.
Environ Pollut. 2020 Sep;264:114679. doi: 10.1016/j.envpol.2020.114679. Epub 2020 Apr 27.
Arsenic (As) has been recognized as one of the most toxic metalloids present in the surface soil contaminating food chain and posing threat to human life. Sulfur (S) fertilizer is often supplied in paddy soil for rice growth, but its impact on As mobility and related bacteria remains poorly understood. In this study, a pot experiment was set up with two different types of sulfur treatments (element sulfur and NaSO) to evaluate the effect of sulfur fertilizers on As speciation in porewater, As fractions in soil, As accumulation in rice plants. Besides, rhizosphere bacterial composition and functional genes that might influence As mobility were also studied. The results revealed that the addition of 150 mg/kg NaSO decreased As(III) and As(V) concentrations in soil porewater at maturation stage by 77% and 64%, respectively. With the same sulfur content, NaSO was more effective than element sulfur. The addition of sulfur fertilizers promoted rice growth and reduced As accumulation in shoots, further reduced As translocation from root to above-ground parts by 39-59%. The addition of sulfur fertilizers had little effect on genes involved in As metabolism. However, the relative abundance of Fe(III) and sulfate reduction related genera increased with the addition of 150 mg/kg NaSO, consistent with the increase of Fe(III) reducing bacteria Geobacteraceae and sulfate reducing gene dsrA. The phenomenon likely influenced the decrease of As concentrations in soil porewater and rice uptake. The outcomes indicate that promoting Fe- and S- reducing bacteria in the rhizosphere by sulfur fertilizers may be one way to reduce As risk in the soil-rice system.
砷（As）已被认为是污染食物链并对人类生命构成威胁的最有毒的金属元素之一。硫（S）肥常用于稻田供水稻生长，但人们对其对 As 迁移性及相关细菌的影响知之甚少。本研究采用两种不同类型的硫处理（单质硫和 NaSO）进行盆栽实验，以评估硫肥对土壤孔隙水中 As 形态、土壤中 As 形态、水稻植株中 As 积累的影响。此外，还研究了影响 As 迁移性的根际细菌组成和功能基因。结果表明，添加 150mg/kg NaSO 在成熟阶段分别将土壤孔隙水中 As(III)和 As(V)浓度降低了 77%和 64%。相同硫含量下，NaSO 比单质硫更有效。硫肥的添加促进了水稻的生长，降低了地上部分的 As 积累，进一步减少了 As 从根部向地上部分的转运，降幅为 39-59%。硫肥的添加对参与 As 代谢的基因几乎没有影响。然而，随着 150mg/kg NaSO 的添加，Fe(III)和硫酸盐还原相关属的相对丰度增加，与 Fe(III)还原菌 Geobacteraceae 和硫酸盐还原基因 dsrA 的增加一致。这种现象可能影响了土壤孔隙水中 As 浓度和水稻吸收量的降低。结果表明，通过硫肥促进根际中 Fe 和 S 还原菌可能是降低土壤-水稻系统中 As 风险的一种方法。
