蒽醌类有机质对针铁矿异化还原解离特征影响

基于希瓦氏金属还原菌(Shewanella decolorationis S12)和针铁矿相互作用,讨论了蒽醌类有机质(AQS)对该针铁矿异化还原过程的调控机制.结果表明:AQS作为电子运移载体,使得还原解离态铁总量(Fetot)和可溶态铁含量(Fedis)均快速增加;不同含量的AQS加入前后,针铁矿还原平均速率得到显著上升,速率比在2.4~4.0之间,且该比值和AQS含量呈显著的线性关系,可决系数为0.9947.Fedis/Fetot比值随AQS含量升高而降低,当AQS含量由0.05 mmol·L-1增加至0.3 mmol·L-1时,Fedis/Fetot比值由0.935减小至0.705.Feads含量随AQS含量增加而增加,当体系中无AQS时,Feads含量维持在较低的水平(0.05 mmol·L-1).AQS参与下的铁异化还原过程实际上是由两个独立的子过程组成,即微生物呼吸作用驱动了AQS和还原态蒽二酚(AH2QS)的循环转变过程以及AH2QS进一步还原解离针铁矿的非生物过程.

Influence of quinone organic matter on the characteristics of the microbial dissimilatory reduction of goethite

This study discussed the influence of anthraquinone-2-sulfonate (AQS) on the reduction of goethite mediated by strain S12. The results showed that the presence of AQS could enhance the degree and extent of goethite reduction. The concentrations of total reductively produced iron (Fe_tot) and dissolved iron (Fe_dis) were elevated compared with those in reaction systems without AQS addition. The ratios of average goethite reduction rate after AQS addition to those before AQS addition were in the range from 2.0 to 4.0, and a significant linear relationship was found between the ratio values and AQS contents (R²=0.9947). AQS contents also influenced values of Fe_dis/Fe_tot and adsorbed iron (Fe_ads) contents. When AQS contents increase from 0.05 mmol·L^-1 to 0.3 mmol·L^-1, the values of Fe_dis/Fe_tot decreased from 0.935 to 0.705. On the contrary, the concentrations of Fe_ads increased with the increasing AQS contents. With the mediation of AQS, the goethite reduction comprised two interactive processes: electronic transportation and pure chemical reaction. The former was driven by cell metabolism to redox mediator, while the latter was catalyzed by the reduced form of redox mediator.