典型富氧化铁土壤基质中铁异化还原的特性

Characteristics of dissimilatory Fe(Ⅲ) reduction in latosol rich with iron

选取华南地区常见的富铁土壤:砖红壤作为研究对象,采用序批实验,破坏性取样系统,研究了葡萄糖、乙酸钠和淀粉分别作电子供体时,砖红壤中Fe(Ⅲ)的异化还原特性及促进剂蒽醌二磺酸钠(AQS)和温度的影响.结果表明,砖红壤在葡萄糖、乙酸钠和淀粉厌氧体系中,均可以通过铁异化还原反应产生较高浓度的亚铁,同时伴随体系中有机物(COD)减少,但是相同有机碳(COD)和砖红壤含量情况下,亚铁产生量在3个系统间具有显著差异,淀粉体系最高,为479.28 mg·L^(-1),乙酸钠体系最低,只有(369.50±13.00)mg·L^(-1);典型的铁异化还原促进剂蒽醌二磺酸钠(AQS)对淀粉体系中砖红壤异化还原过程具有明显的促进效果,除了可以促使更多三价铁还原为亚铁外,也可以提高铁异化还原的速率,并且较高浓度促进剂效果更好,投加与砖红壤质量比1∶20000的AQS情况下,亚铁产量最高可达1101.36 mg·L^(-1);温度对砖红壤铁异化还原速率也具有明显影响,25℃和30℃差别较小,但温度降到20℃之后反应明显缓慢.

In this study,sequence batch experiments and destructive sampling system were conducted to characterize the dissimilatory Fe（ Ⅲ） reduction in latosol,a common and typical red soil with high Fe concentration in South China. Glucose,sodium acetate and starch were used as the electron donors,respectively. In addition,effects of the accelerator anthraquinonesulphonate（ AQS） and temperature on the dissimilatory Fe（ Ⅲ） reduction was explored.Results found that high Fe（ Ⅱ） concentration was detected and COD decreased greatly in all these three anaerobic latosol systems when glucose,sodium acetate or starch was supplied as the electron donors individually,due to the dissimilatory Fe（ Ⅲ） reduction. However,Fe（ Ⅱ） concentrations significantly differed among three systems when same amount of organic carbon was provided,with the highest Fe（ Ⅱ） concentration（ 479.28 mg·L^-1）detected in starch system and the lowest Fe（ Ⅱ） concentration（（ 369.50±13.00） mg·L^-1） in sodium acetate system. The addition of AQS accelerator significantly promoted the dissimilatory Fe（ Ⅲ） reduction in latosol system with starch as the electron donor,resulting in higher reaction rate and final Fe（ Ⅱ） concentration of 1101.36 mg·L^-1. At the same time,temperature had significant influence on the dissimilatory reduction rate. Reaction rate had no significant difference between 25 ℃ and 30 ℃,but significantly decreased below 20 ℃.