BTEX污染模拟含水层的生物地球化学作用

Anaerobic biogeochemical process in BTEX contaminated aquifer

通过98 cm砂柱实验模拟BTEX污染含水层的过程,分析含水层中总有机碳、硫酸盐、铁、无机氮和可溶性碳酸盐含量的变化,揭示其厌氧生物地球化学作用。研究结果表明:以BTEX为电子供体,以环境中NO3-,Fe3+及SO42-为电子受体的微生物降解过程为主要作用,NO3-,Fe3+及SO42-电子受体的还原分别发生在距砂柱入水口70-89,55-70及34-55 cm处;有机氮矿化作用和CO2对碳酸盐的溶蚀作用发生在整个受污染区域;硫化亚铁沉淀生成主要发生在0-55 cm处,使该区域总铁量较55-70 cm处有所升高;可溶性碳酸盐含量变化由H+的溶解作用,0-70 cm处发生的碳酸亚铁沉淀生成及70-89 cm处CO2对碳酸盐的溶蚀作用共同决定;BTEX污染源附近污染晕中形成了高浓度有机碳的典型特征。

A lab-scale column was constructed to investigate the pollution process of aquifer by BTEX to analyze the variations of mass fraction of total organic carbon, sulfate, iron, inorganic nitrogen and soluble carbonate, and to clarify biogeochemical process of the pollution process. Experimental results indicate the dominating process is that microbes degrade electron donors-BTEX by using NO3 , Fe3＋, SO42- and CO2 as electron acceptors; reduction reactions of NO3 , Fe3＋ and SO42- take place in regions away from the inlet 70-89, 55-70 and 34-55 cm respectively; mineralization of organic nitrogen and corrosion that CO2 does on carbonate appear in whole contaminated region; generation of Iron（II） sulfide mainly happens in 0-55 cm, which makes total iron content here higher than the content in 55-70 cm; variation of soluble carbonate content was determined by the content of H＋ which can dissolve it together with the generation of ferrous carbonate in 0-70 cm and corrosion effect which CO2 does no it in 70-89 cm. That high concentration of organic carbon generate in pollution plume near pollutants becomes typical characteristic.