赤峰垃圾填埋场地下水污染状况研究及成因解析

RESEARCH ON GROUNDWATER POLLUTION SITUATION IN CHIFENG LANDFILL AND CAUSE ANALYSIS

近年来,我国地下水污染问题日益突出,填埋场已成为我国公认的地下水重点污染源之一。通过对赤峰垃圾填埋场及其周边地下水环境的系统检测分析,采用单因子指数法及综合评价法对现状地下水进行质量评价,通过主成分分析及Pearson相关性分析开展地下水污染成因解析。基于地下水历史检测数据,对照GB/T 14848—2017《地下水质量标准》中Ⅲ类水体指标限值,2018年12月—2020年8月研究区地下水历史超标指标有氨氮、硫化物、氟化物、总大肠菌群及部分感官性状指标,超标频次11%~90%,超标倍数1.01~120。除氨氮及氟化物,超标物浓度整体呈降低趋势。2020年9月超标物质仅氟化物和总大肠菌群,超标倍数在1.03~1.37。根据Pearson相关性及主成分分析结果,结合大肠菌群的特点,判断填埋场内总大肠菌群超标主要由监测井洗井不充分及周边人类活动影响导致。由该地区地层岩性、地下水化学类型等,结合文献调研,判断氟化物超标主要由水文地质条件决定。氨氮浓度水平波动性较大,各点位均出现历史超标现象。根据背景点与各监测点氨氮浓度的正相关性(P<0.01,R≥0.655),以及渗滤液对场内地下水氨氮浓度贡献率为30.37%等,判断其超标成因主要包括垃圾渗滤液及上游地区农业、农村面源污染。

In recent years,groundwater pollution is becoming more and more serious in China.Domestic waste landfill has become one of the most important sources of groundwater pollution in China.In this paper,the groundwater environment of Chifeng landfill site and its surroundings were systematically tested.Single factor index method and comprehensive evaluation method were used to evaluate the quality of present groundwater.The causes of groundwater pollution were analyzed by factor analysis and Pearson correlation analysis.Based on the historical detection data,the substances exceeding the standard including ammonia nitrogen,sulfide,fluoride,total coliform and part of the sensory traits in contrast to the limit value ofⅢwater body in China’s national standard Groundwater Quality Standard(GB/T 14848—2017).The exceedance frequency was between 11%and 90%.The exceedance multiple ranged from 1.01 to 120.In addition to ammonia nitrogen and fluoride,the concentration of superstandard substances showed a decreasing trend.The main excess substances were fluoride and total coliformsat at present.The overshoot multiple was between 1.03 and 1.37.According to factor analysis and Pearson correlation analysis,combined with the characteristics of total coliforms,the excessive total coliform population was mainly caused by inadequate well cleaning and human activities around the site.Combined with literature research and formation lithology,superstandard fluoride was mainly determined by hydrogeological condition.The concentration of ammonia nitrogen fluctuated greatly,and all points exceeded the historical standard.For the concentration of ammonia nitrogen,there was a positive correlation between the background point and other monitoring points(P<0.01,R≥0.655).The contribution rate of leachate to the nitrogen in groundwater was 30.37%.The non-point source pollution in the upstream area and the influence of landfill leachate were the main reasons.