硫酸盐还原菌对汞的甲基化作用及其影响因子

MICROBIAL METHYLATION OF MERCURY AND THEIR AFFECTING FACTORS IN AQUATIC ENVIRONMENT

从受氯碱化工废水严重污染的湖北鸭儿湖 1号氧化塘底泥中分离获得了硫酸盐还原菌 ,研究了其生理特性和环境因子对其生长的影响。并在实验室条件下建立了模拟厌氧水环境 ,通过正交实验获得汞甲基化的最佳条件 ,研究了该条件下硫酸盐还原菌在好氧和厌氧状况下对汞的甲基化作用 ,以及非生物甲基化作用。同时又分别作了单因素实验 ,并用高效液相色谱法测定了水样中不同形态的汞。结果显示 ,该硫酸盐还原菌营厌氧生活 ,在35℃、pH7 0、0 7%的盐度、0 5g/LFe2 + 和不含硫化物等条件下 ,可达到最佳生长状态。水环境中汞的甲基化作用主要发生在有微生物为媒介的厌氧环境下 ,汞的非生物甲基化作用和好氧环境下的甲基化作用均可忽略不计。厌氧环境下 ,水体温度、pH值、硫化物和盐度等诸多环境因素对汞的微生物甲基化作用的影响也进行了研究与讨论。

Sulfate reducing bacteria(SRB)was isolated from the sediments of the oxidation pond of Ya Er Lake hubei,a heavily polluted lake by direct discharge of chloralkali effluent,and incubated in the laboratory.Its physiology characteristics and the effects of environmental factors were studied.The results show that temperature,pH,salinity,ferrous iron and sulfide greatly affect their characteristics.The effects on bivalent mercury methylation of SRB in the simulative anaerobic aquatic system were investigated.The methylation conditions were optimized by the orthogonal experiment.The mercury methylations of SRB under anaerobic and aerobic environment were studied,as well as its abiotic methylation.And we also studied the effects on methylation of the single environmental factor.The mercury compounds were detected by HPLC.In this paper,we developed a simple and rapid method for in situ preconcentration of inorganic and organic mercury compounds in water samples.At the same time,this developed mothod was indicated to be applicable for detecting Hg 2+ and MeHg in environmental water samples in this test.The results indicated that this SRB grows best under the optimum conditions,such as 35℃,pH5 0,0 7% salinity,0 5g/L ferrous iron,and without sulfide.Mercury methylation in aquatic environment mostly occurs under anaerobic condition,and is mediated by SRB.And the abiotic and aerobic mercury methylations are negligible.It has been found that microbial methylation in anaerobic aquatic environment is influenced by a wide variety of environmental factors.The temperature(35℃),pH(5 0)and salinity(0 7%)are the most important affecting factors for mercury methylation. In aquatic environment,Mercury may be one of the most hazardous contaminants.Its ecological and toxicological effects strongly dependent on its chemical species present.Species distribution and transformation processes in natural aquatic systems are controlled by various physical,chemical,and biological factors.Under the environmental conditions,inorganic mercury species may be converted to many times more toxic methylated forms such as methylmercury.So it is of great necessity and importance for us to study the microbial methylation process and their affecting factors in aquatic environment.