Institute of Soil and Water Resources and Environmental Science, College of Environmental and Resource Sciences, Zhejiang Provincial Key Laboratory of Agricultural Resources and Environment, Zhejiang University, Hangzhou, China.
Zhejiang Institute of Landscape Plants and Flowers, Zhejiang Academy of Agricultural Sciences, Hangzhou, China.
Ecotoxicol Environ Saf. 2024 Sep 1;282:116716. doi: 10.1016/j.ecoenv.2024.116716. Epub 2024 Jul 16.
Anaerobic methane oxidation (AOM) can drive soil arsenate reduction, a process known as methane-dependent arsenate reduction (M-AsR), which is a critical driver of arsenic (As) release in soil. Low molecular weight organic acids (LMWOAs), an important component of rice root exudates, have an unclear influence and mechanism on the M-AsR process. To narrow this knowledge gap, three typical LMWOAs-citric acid, oxalic acid, and acetic acid-were selected and added to As-contaminated paddy soils, followed by the injection of CH and incubation under anaerobic conditions. The results showed that LMWOAs inhibited the M-AsR process and reduced the As(III) concentration in soil porewater by 35.1-65.7 % after 14 days of incubation. Among the LMWOAs, acetic acid exhibited the strongest inhibition, followed by oxalic and citric acid. Moreover, LMWOAs significantly altered the concentrations of ferrous iron and dissolved organic carbon in the soil porewater, consequently impacting the release of As in the soil. The results of qPCR and sequencing analysis indicated that LMWOAs inhibited the M-AsR process by simultaneously suppressing microbes associated with ANME-2d and arrA. Our findings provide a theoretical basis for modulating the M-AsR process and enhance our understanding of the biogeochemical cycling of As in paddy soils under rhizosphere conditions.
厌氧甲烷氧化（AOM）可以驱动土壤砷酸盐还原，这一过程被称为甲烷依赖型砷酸盐还原（M-AsR），它是土壤中砷释放的关键驱动因素。低分子量有机酸（LMWOAs）是水稻根系分泌物的重要组成部分，但其对 M-AsR 过程的影响和机制尚不清楚。为了缩小这一知识差距，选择了三种典型的 LMWOAs-柠檬酸、草酸和乙酸，并将其添加到受砷污染的稻田土壤中，然后注入 CH4 并在厌氧条件下进行培养。结果表明，在 14 天的培养后，LMWOAs 抑制了 M-AsR 过程，使土壤孔隙水中的 As(III)浓度降低了 35.1-65.7%。在 LMWOAs 中，乙酸的抑制作用最强，其次是草酸和柠檬酸。此外，LMWOAs 还显著改变了土壤孔隙水中亚铁和溶解有机碳的浓度，从而影响了土壤中砷的释放。qPCR 和测序分析的结果表明，LMWOAs 通过同时抑制与 ANME-2d 和 arrA 相关的微生物来抑制 M-AsR 过程。我们的研究结果为调节 M-AsR 过程提供了理论依据，并增强了我们对根际条件下稻田土壤中砷生物地球化学循环的理解。
