Yang, XingXingYangShaheen, Sabry M.Sabry M.ShaheenWang, JianxuJianxuWangHou, DeyiDeyiHouOk, Yong SikYong SikOkSHAN-LI WANGWang, HailongHailongWangRinklebe, JörgJörgRinklebe2022-04-252022-04-252022-01-1503043894https://www.scopus.com/pages/publications/85112268028?inwardhttps://scholars.lib.ntu.edu.tw/handle/123456789/606039Iron (Fe)-modified biochar, a renewable amendment that synthetizes the functions of biochar and Fe materials, demonstrates a potential to remediate arsenic (As)-contaminated soils. However, the effectiveness of Fe-based biochar to immobilize As in paddy soils under varying redox conditions (Eh) has not been quantified. We tested the capability of the raw (RBC) and Fe-impregnated (FeBC) biochars to immobilize As in a paddy soil under various Eh conditions (from -400 to +300 mV) using a biogeochemical microcosm system. In the control, As was mobilized (686.2–1535.8 μg L-1) under reducing conditions and immobilized (61.6–71.1 μg L-1) under oxidizing conditions. Application of FeBC immobilized As at Eh < 0 mV by 32.6%–81.1%, compared to the control, because of the transformation of As-bound Fe (hydro)oxides (e.g., ferrihydrite) and the formation of complexes (e.g., ternary As-Fe-DOC). Application of RBC immobilized As at Eh < -100 mV by 16.0%–41.3%, compared to the control, due to its porous structure and oxygen-containing functional groups. Mobilized As at Eh > +200 mV was caused by the increase of pH after RBC application. Amendment of the Fe-modified biochar can be a suitable approach for alleviating the environmental risk of As under reducing conditions in paddy soils.Fe-based biocharImmobilization mechanismsRedox conditionsSoil remediationToxic metal(loid)s[SDGs]SDG2[SDGs]SDG6[SDGs]SDG12[SDGs]SDG13[SDGs]SDG15journal article10.1016/j.jhazmat.2021.126808343992212-s2.0-85112268028