岩溶断层区含油废水溢流地下水污染风险评价

岩溶地下水是西南岩溶地区重要的生活和生产用水来源，由于其赋存地质环境复杂，受到污染后极难治理。以某含油废水溢流区为研究对象，通过调查污染区域的地质结构、溶洞通道及断层情况，评估污染物的来源、分布范围及主要迁移通道，构建基于地下水自净能力的地下水污染风险评价模型。结果表明：研究区石油烃 (C10~C40) 、氰化物和甲苯污染严重，三者检出率分别为98.7%，75.3%和59.7%，包气带内仍存在大量的石油类污染物，其质量为14.07 t；岩溶断层区地下水系统存在2条岩溶通道，且石油类污染物主要通过第一条通道迁移；地下水中石油类污染物的自然衰减过程符合指数型衰减特征；人工冲洗情景下，污染物和示踪剂浓度下降速度加快，地下水自净能力显著提高；岩溶断层区地下水污染风险指数与泉流量之间呈现负相关关系。该研究成果可为岩溶断层区含油废水溢流地下水污染的自然衰减式治理和风险防控提供参考。

Assessing the risk of petroleum polluted groundwater from oily wastewater overflow in karst fault area.

Karst groundwater is an important source of water for living and production in karst areas of southwest China. Karst area has complex geological structure, so that once the groundwater in karst area is polluted, it will bring great challenges to the treatment work. Taking an oil-bearing wastewater overflow area as the research object, this study investigated the geological structure, cave channels and faults of the polluted area, analyzed the source, distribution range and main migration channels of pollutants, and assessed the self-purification capacity (SPC) of groundwater and its pollution risk. The results show that petroleum hydrocarbon (C10-C40), cyanide and toluene are seriously polluted in this area, and the detection rates of the three pollutants are as high as 98.7%, 75.3% and 59.7%, respectively. There are still a lot of petroleum pollutants in the vadose zone, and the content is as high as 14.07 tons. There are two karst channels in the groundwater system in the karst fault area, and the oil pollutants mainly migrate through the first channel, that is, the leakage area-CK4-CK3-S001 spring point. The monitoring results show that the natural attenuation process of oil pollutants in groundwater conforms to exponential attenuation characteristics. The tracer experiment showed that the concentration of pollutants and tracers decreased rapidly and the self-purification ability of groundwater was significantly improved under the artificial flushing situation. In addition, there is a negative correlation between groundwater pollution risk index and spring discharge in karst fault areas. The greater the spring discharge, the lower the concentration of oil pollutants in spring water, and the lower the pollution risk of groundwater. The research results can provide technical support for natural attenuation treatment and risk prevention and control of groundwater pollution from oil-bearing wastewater overflow in karst fault area.