武汉金口垃圾填埋场对地下水环境的影响分析

The influence analysis of Jinkou landfill on the groundwater quality in Wuhan City

分析了武汉金口垃圾填埋场中不同填埋时间的垃圾渗滤液特性和周边地下水水质,并结合场地条件分析垃圾渗滤液对地下水环境的影响机制。结果表明:(1)所有垃圾渗滤液(均超过7年)中COD、氨氮、Cl-均分别低于500、1 000、1 000mg/L;重金属含量较低。垃圾渗滤液中COD、氨氮和Cl-均随填埋时间延长而降低。(2)填埋场周围50m内的上层滞水均受到垃圾渗滤液水平渗透的影响,主要表现为高锰酸盐指数和氨氮均不能满足《地下水质量标准》(GB/T 14848—93)中Ⅲ类标准,其中氨氮超标严重,平均超标89.3倍,高锰酸盐指数平均超标1.0倍。相比场区地下水的下游方向,上游方向的上层滞水受污染程度较轻。(3)由于厚层黏土的阻隔,距地表约25m的上更新统承压水的水质相对较好,除武汉市上更新统承压水普遍存在的超标组分(氨氮和Mn)外,其他指标基本满足GB/T 14848—93中Ⅲ类标准,其受垃圾填埋场渗滤液垂直渗透影响较小。这为简易填埋场关闭后的场地维护和开发利用以及新建填埋场的选址提供借鉴。

The characteristics of leachate with different ages and groundwater around the landfill were analyzed, and the influence mechanism of the leachate on the groundwater was analyzed combined with site condition in Jinkou landfill of Wuhan City. The results showed： （1）the COD content of all leachate （2〉7 years old） was below 500 mg/L,and ammonia nitrogen content was below 1 000 mg/L and C1 content Was below 1 000 mg/L. The content of other heavy metals were very low. The content of COD,ammonia nitrogen and C1 of leachate decreased with buried ages. （2）The perched groundwater within a range of 50 m to the site was polluted by leachate for horizontal permea bility,mainly showing permanganate index and ammonia nitrogen content couldn＇t meet the requirements of the Grade Ⅲ of ＂Quality standard for groundwater＂ （GB/T 14848-93）. Among them,the contents o{ ammonia nitrogen and permanganate index were 89.3 and 1.0 times more than the requirement of the Grade Ⅲ. Compared to the down- stream direction of the groundwater,the perched groundwater of the upstream direction was less polluted. （3）Due to the burier of thick cohesive soil for leachate, the quality of artesian water of upper pleistocene about 25 m under the surface was relatively good. Except for ammonia nitrogen and Mn,which were the common parameters exceeding the standards as in the artesian water of upper pleistocene in Wuhan City,the other parameters met the requirements of the Grade Ⅲ of GB/T 14848 93, which was less polluted by leachate leakage. It provides reference for the site maintenance and utilization of closed landfill and the site selection of the new landfill.