天津某化工厂有机污染场地地下水中1,2,3-三氯丙烷和苯监控自然衰减与环境修复建议

Natural attenuation monitoring of 1,2,3-trichloropropane and benzene in the groundwater of organic pollution sites,Tianjin chemical plant and its environmental restoration suggestions

【研究目的】氯代烃、苯系物等有机污染物对中国地下水环境造成重要威胁,监控自然衰减技术在场地污染修复中发挥着重要作用,研究监控自然衰减技术,有利于推动地下水有机污染控制与环境修复技术发展。【研究方法】本文通过对某化工污染场地地下水中1,2,3-三氯丙烷(TCP)和苯3年的长期监测,对地下水污染物浓度、氧化还原电位(ORP)、硝酸盐浓度的变化及微生物多样性进行分析,研究了场地不同含水层TCP和苯的自然衰减特征,并采用一级衰减动力学方程,计算了污染源区TCP和苯自然衰减能力。【研究结果】结果表明:研究区地下水存在不同程度的TCP和苯的自然衰减;潜水及承压含水层地下水ORP值分别为-225~-57 mV和-182~-3 mV,为中—强还原环境,具备有机污染物厌氧生物降解基础环境条件;与非污染源区、承压含水层相比,污染源区、潜水含水层地下水微生物自然衰减作用更强,其中,污染源区MMW02监测井潜水含水层地下水TCP和苯的降解率分别为80.00%和77.88%;潜水含水层TCP和苯的衰减速率分别为0.0018 d^(-1)和0.0016 d^(-1),承压含水层TCP和苯的衰减速率分别为0.001 d^(-1)和0.0015 d^(-1)。【结论】针对地下水污染程度的不同,将监控自然衰减技术单独使用或与其他方法、技术联合使用,是低成本、高效率修复该类工业污染场地地下水有机污染的有效方法。

This paper is the result of environmental geological survey engineering.[Objective]Organic pollutants,such as chlorinated hydrocarbons and BTEX,have an important threat to groundwater environment in China.Natural attenuation monitoring plays an important role in contaminated sites remediation.Researches on natural attenuation monitoring will be conductive to promoting the development of groundwater organic pollution control and environmental remediation technologies.[Methods]In order to study the natural attenuation of 1,2,3-trichloropropane(TCP)and benzene in different aquifers groundwater,the 3-year monitoring data of TCP,benzene,oxidation reduction potential(ORP),nitrate(NO3-)and biodiversity in an organic contaminated site has been collected and analyzed.Natural attenuation capacity of the pollution source area of the site was calculated using first order attenuation kinetic equation.[Results]The results show that the natural attenuation of TCP and benzene occurred in the aquifer for different degrees,and ORP values of the groundwater in phreatic and confined aquifer were-225~-57 mV and^(-1)82~-3 mV,respectively,which were medium-high reducing environment with basic environmental conditions for anaerobic biodegradation of organic pollutants.Moreover,the effect of microbial degradation was stronger in the pollution source area and phreatic aquifer than that in non-pollution source area and confined aquifer,and the degradation rates of TCP and benzene in the phreatic aquifer of MMW02 monitoring well were 80.00%and 77.88%,respectively.The attenuation rate of TCP and benzene were 0.0018 d^(-1)and 0.0016 d^(-1)in phreatic aquifer,and 0.001 d^(-1)and 0.0015 d^(-1)in confined aquifer.[Conclusions]According to the different degree of groundwater pollution,the natural attenuation monitoring technology can be used alone or combined with other remediation methods and technologies,which is a low cost and high efficiency method to reduce groundwater organic pollution for this kind of industrial contaminated sites.