Biochar Engineering Technology Research Center of Guangdong Province, School of Environmental and Chemical Engineering, Foshan University, Foshan, Guangdong 528000, China; University of Wuppertal, School of Architecture and Civil Engineering, Institute of Foundation Engineering, Water, and Waste-Management, Laboratory of Soil, and Groundwater-Management, Pauluskirchstraße 7, 42285 Wuppertal, Germany.
University of Wuppertal, School of Architecture and Civil Engineering, Institute of Foundation Engineering, Water, and Waste-Management, Laboratory of Soil, and Groundwater-Management, Pauluskirchstraße 7, 42285 Wuppertal, Germany.
J Hazard Mater. 2022 Jan 5;421:126647. doi: 10.1016/j.jhazmat.2021.126647. Epub 2021 Jul 20.
Contamination of paddy soils by arsenic (As) is of great concern for human health and the environment. The impact of animal-derived biochar on As mobilization under fluctuating redox conditions in paddy soils has not been studied. Consequently, we investigated the effects of pig carcass-derived biochar (PB) on As (im)mobilization in a contaminated paddy soil under controlled redox potential (Eh) using a biogeochemical microcosm-setup. The addition of PB decreased the concentration of dissolved As at Eh = +100 and +200 mV by 38.7% and 35.4%, respectively (compared to the control), because of the co-precipitation of As with Fe-Mn oxides and the complexation between As and aromatic organic molecules. However, under reducing conditions (Eh = -300 mV), PB increased the dissolved As by 13.5% through promoting reduction and decomposition of As-bearing Fe minerals (e.g., ferrihydrite-As, Fe-humic-As). Under oxidizing conditions (Eh = +250 mV), PB increased the dissolved As by 317.6%, due to the associated increase of pH. We conclude that As mobilization in PB-treated paddy soils is highly affected by Eh. PB can be used to reduce the environmental risk of As under moderately reducing conditions, but it may increase the risk under highly reducing and oxidizing conditions in paddy soils.
砷（As）污染稻田对人类健康和环境构成了极大的威胁。目前尚未研究动物源生物炭在稻田中波动氧化还原条件下对 As 迁移的影响。因此，我们采用生物地球化学微宇宙装置，研究了猪尸源生物炭（PB）对受污染稻田中氧化还原电位（Eh）控制下 As（固/解）迁移的影响。与对照相比，在 Eh = +100 和 +200 mV 时，PB 的添加分别使溶解态 As 的浓度降低了 38.7%和 35.4%，这是由于 As 与 Fe-Mn 氧化物共沉淀和 As 与芳族有机分子络合。然而，在还原条件（Eh = -300 mV）下，PB 通过促进含 As 的 Fe 矿物（例如，水铁矿-As、Fe-腐殖酸-As）的还原和分解，使溶解态 As 增加了 13.5%。在氧化条件（Eh = +250 mV）下，由于 pH 值的升高，PB 使溶解态 As 增加了 317.6%。综上所述，Eh 对 PB 处理稻田中 As 的迁移有很大的影响。在中等还原条件下，PB 可用于降低 As 的环境风险，但在稻田高度还原和氧化条件下，可能会增加风险。
