MOE Key Laboratory of Pollution Processes and Environmental Criteria, Tianjin Key Laboratory of Environmental Remediation and Pollution Control, Nankai University, No. 38 Tongyan Road, Jinnan District, Tianjin 300350, China.
School of Environmental Science and Engineering, Tianjin University, No. 135 Yaguan Road, Jinnan District, Tianjin 300350, China.
Sci Total Environ. 2023 Feb 1;858(Pt 2):159794. doi: 10.1016/j.scitotenv.2022.159794. Epub 2022 Oct 28.
Fe(III) oxides are ubiquitous electron acceptors for anaerobic bioremediation, although their bioavailability was limited due to the passivation of secondary mineralization products. Here we found the solid S can be added to improve their bioavailability. Using lepidocrocite (γ-FeOOH), acetate and Geobacter sulfurreducens PCA as representatives of Fe(III) oxides, intermediate of pollutant degradation and microbes, a 6 times higher amount of FeOOH reduction in the presence of S was observed with a time needed for S reduction shortened by half. The bioreduction of S activated the reduction of FeOOH, while the product (conductive FeS) may have bridged electron transfer across the cell membrane and periplasm. The proportion of excessive Fe(II) produced from Fe(III) was quantified as a direct bioreduction (26 %), with an abiotic FeOOH reduction to FeS (20 %) and an FeS-conducted FeOOH bioreduction (54 %), which highlight the key role of gradually formed FeS from S in the bioreduction of FeOOH. Our results showed that S can be an effective additive for the bioremediation of environments with abundant Fe(III) oxides, which has broader implications for elemental biogeochemical cycling.
三价铁氧化物是厌氧生物修复中普遍存在的电子受体，但由于次生矿物化产物的钝化，其生物利用度有限。在这里，我们发现可以添加固体硫来提高其生物利用度。使用纤铁矿 (γ-FeOOH)、醋酸盐和脱硫弧菌 PCA 作为三价铁氧化物、污染物降解中间产物和微生物的代表，在硫存在的情况下观察到 FeOOH 的还原量增加了 6 倍，而硫还原所需的时间缩短了一半。硫的生物还原激活了 FeOOH 的还原，而产物（导电的 FeS）可能在细胞膜和周质之间桥接了电子转移。从 Fe(III) 产生的过量 Fe(II)的比例被量化为直接生物还原 (26%)，还有非生物 FeOOH 还原为 FeS (20%) 和 FeS 介导的 FeOOH 生物还原 (54%)，这突出了 S 逐渐形成的 FeS 在 FeOOH 生物还原中的关键作用。我们的结果表明，硫可以作为一种有效的添加剂，用于富含三价铁氧化物的环境的生物修复，这对元素生物地球化学循环具有更广泛的意义。
