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.
Department of Health and Environmental Sciences, Xi'an Jiaotong-Liverpool University, Suzhou, 215123, People's Republic of China.
J Hazard Mater. 2019 Jul 5;373:591-599. doi: 10.1016/j.jhazmat.2019.03.113. Epub 2019 Mar 27.
Humic acid (HA) and fulvic acid (FA) are dominating humic substances (HS) in soil. In this study, the effects of HA and FA addition (0.2%-1.5%) on arsenic (As) mobility and microbial community composition in paddy soil were investigated. FA significantly increased the concentrations of As (12-fold), iron (Fe; 20-fold), manganese (Mn; 3-fold) and acetic acid (3-fold) in soil porewater, and also caused significant enrichment of Desulfitobacterium (41-fold). Furthermore, the FA addition significantly increased the relative abundance of Bathyarchaeota (4-fold), a microorganism that is suggested to be important for FA degradation. In contrast, HA slightly increased As (1.2-fold) in porewater, had little effect on Fe, Mn and acetic acid, and 1.5% HA addition significantly decreased As in porewater at day 14 (45%). Both HA and FA addition promoted As methylation. HA increased dimethylarsenate concentration and FA increased monomethylarsenate concentration in porewater. These results highlight the contrasting effects of different (HA vs. FA) organic substances on As fate in paddy soil and advance our understanding of the associations among As, Fe and organic substances through microorganisms in paddy soil.
腐殖酸（HA）和富里酸（FA）是土壤中主要的腐殖物质（HS）。本研究探讨了 HA 和 FA （0.2%-1.5%）添加对稻田土壤中砷（As）迁移性和微生物群落组成的影响。FA 显著增加了土壤孔隙水中 As（12 倍）、铁（Fe；20 倍）、锰（Mn；3 倍）和乙酸（3 倍）的浓度，并使脱硫菌（Desulfitobacterium；41 倍）显著富集。此外，FA 还显著增加了 Bathyarchaeota（4 倍）的相对丰度，该微生物被认为对 FA 降解很重要。相比之下，HA 略微增加了孔隙水中的 As（1.2 倍），对 Fe、Mn 和乙酸影响不大，而 1.5%HA 的添加在第 14 天显著降低了孔隙水中的 As（45%）。HA 和 FA 的添加都促进了 As 的甲基化。HA 增加了二甲基砷酸盐的浓度，FA 增加了一甲基砷酸盐的浓度。这些结果突出了不同有机物质（HA 与 FA）对稻田土壤中 As 命运的相反影响，并通过稻田土壤中的微生物，增进了我们对 As、Fe 和有机物质之间关联的理解。
