生物炭对土壤中铁生物还原作用和重金属分布的影响

构建厌氧精瓶培养实验体系,探讨生物炭对土壤中铁的生物还原和其他重金属形态转化的影响。结果表明:生物炭会影响铁还原菌希瓦氏菌(Shewanella oneidensis MR-1)对土壤中铁矿物的还原溶出,降低亚铁离子浓度。培养70d后,土壤-希瓦氏菌(SR)处理组亚铁离子摩尔浓度为(291.0±58.0)μmol/L,土壤-希瓦氏菌-生物炭(SRB)处理组亚铁离子摩尔浓度降为(94.7±32.4)μmol/L。同时,生物炭改变了铁生物还原作用对土壤中重金属迁移性的影响。SRB处理组土壤中可交换态锌、钴和镍含量低于土壤-生物炭(CB)处理组,而铁锰氧化物结合态含量增加;与SR处理组相比,SRB处理组可交换态和铁锰氧化物结合态锌、钴、镍含量均有所增加。因此,在稻田等厌氧环境下应用生物炭修复重金属污染土壤时,生物炭对铁矿物生物还原、重金属形态转化的影响需要引起关注。

Effects of biochar on biological iron reduction and metal distribution in soils

The anaerobic incubation experiment was conducted to explore the influence of biochar on the biological iron reduction and metal distribution in soils.The results showed that the typical iron reducing bacteria Shewanella oneidensis MR-1(S.MR-1)could induced reduction and digestion of iron mineral in soil,while the existence of biochar could influence the bioreduction process and decrease the concentration of ferrous ion.After incubated for 70 days,the concentration of ferrous ion in the treatment with S.MR-1(SR)reached(291.0±58.0)μmol/L,while the concentration in the treatment with S.MR-1 and biochar together(SRB)was(94.7±32.4)μmol/L.Meanwhile,biochar could change the influence of biological iron reduction on mobility of heavy metal in soil.In the SRB treatment,the contents of exchangeable phases of Zn,Co and Ni were decreased compared to the treatment with single biochar(CB),while the contents of Fe-Mn oxides bonding phase of Zn,Co and Ni were increased.However,compared to the speciation in the SR treatment,the contents of exchangeable and Fe-Mn oxides bonding phases of Zn,Co and Ni were increased.Therefore,during the utilization of biochar for the remediation of soil heavy metal pollution in the anaerobic circumstance like paddy soils,the influence of biochar on the bioreduction of Fe bearing mineral and the redistribution of heavy metals should be concerned.