【作者】 周鹏；

【导师】 旦增；

【作者基本信息】 西藏大学 ， 生态学， 2020， 硕士

【摘要】 尽管随着我国经济社会的发展以及人们对垃圾填埋处理处置弊端的认识,我国城市生活垃圾处理处置方式逐渐趋向于以焚烧处理为主。然而,青藏高原地区作为我国最后一片净土和重要的国家生态安全屏障,据自治区住建厅统计资料显示:西藏生活垃圾处理处置几乎以填埋处理为主。垃圾渗滤液作为垃圾填埋过程中产生的一种成分复杂的高浓度有机废水,一旦发生渗漏进入地下水含水层,将对地下水水质造成一定程度的污染,并且这种污染将延续数十年甚至更长,污染的地下水将对人民群众健康造成较高的污染风险。因此,本文在资料收集、现场环境调研、样品采集和分析的基础上,对填埋场源污染风险、地下水脆弱性、区域地下水水质以及居民健康风险大小进行分析评价,以期为填埋场管理、污染防控和保障地下水用水安全提供科学依据。取得的主要研究成果如下:（1）垃圾填埋场源污染风险评价结果表明:日喀则市垃圾填埋场一期场地综合潜在污染风险评价结果为5.5,为中等污染;由于二期工程即将投入运行,较新的垃圾由于具有较高的含水率,再加上日喀则市垃圾填埋场生活垃圾收运效率提高,填埋量增加,其存在的潜在污染风险较高（Ii=6.1）,此后,其潜在污染风险逐渐减低,呈现中等污染。（2）采用DRASTIC模型对研究区地下水脆弱性进行分析评价,结果表明:研究区地下水含水层脆弱性较弱,污染物防污性能较强。（3）选取pH值、总硬度、硫酸盐、高锰酸盐指数、硝酸盐（以N计）、亚硝酸盐（以N计）、氨氮、铬（六价）、氟化物、氯化物、镉、铅、砷、锌、硒、氰化物、汞、铁、溶解性总固体共计19项常规指标进行检测分析,结果表明:研究区地下水主要超标指标为氨氮、六价铬、铁。2014年日喀则市垃圾填埋场地下水水质相对较差,其中:氨氮超标率为100%,最大超标倍数1.88倍;六价铬超标率为33.3%,最大超标倍数1.08倍;铁超标率为66.6%,最大超标倍数1.07倍。2015、2017和2018年水质相对较好,仅铁元素呈现不同程度的污染,超标率和最大超标倍数依次是100%、33.3%、100%和2.33、2.22、1.4倍,其他元素均满足地下水质量Ⅲ类标准（GB/T14848-2017）;2016年日喀则市垃圾填埋场地下水各检测指标均满足地下水质量Ⅲ类标准（GB/T14848-2017）。（4）研究区地下水水质现状为较好—良好,各监测井水质变化相对稳定,大体呈现为本底井>扩散井>监视井。区域地下水水质在各水期相对较好,各监测井水质变化相对稳定,综合水质为良好;不同水期综合水质现状依次为枯水期>平水期>丰水期。以地下水质量（GB/T14848-2017）Ⅰ类标准为背景值,对各年度各监测井水质污染程度进行分析评价,结果表明:2014年、2015年和2018年区域地下水水质综合污染现状呈轻污染;2016年和2017年区域地下水水质综合污染现状为无污染。各监测井污染程度为扩散井>本底井>监视井>多林变电站监视井;各水期地下水综合水质污染程度呈现丰水期>平水期>枯水期。（5）居民健康风险评估结果表明:女性遭受的致癌风险和非致癌危害商明显高于男性所遭受的健康风险;致癌物质经所有暴露途径导致的致癌风险依次为CRcgw>CRiov3>CRdgw,各致癌因子经所有途径导致的综合致癌风险大小依次为:Cd（1.645E-06）>Cr⁶⁺（6.679E-07）>As（4.041E-07）。非致癌物质经所有暴露途径导致的非致癌风险依次为HQcgw>HQiov3>HQdgw,各非致癌因子经所有途径导致的非致癌危害商大小依次为:CN-（0.0241）>F^-（0.0165）>As（0.0129）>Cr⁶⁺（0.0063）>Cd（0.0038）>NO₃-N（0.0022）>Hg（0.0012）>NO₂-N（0.0004）>Zn（0.00017）。致癌因子Cr⁶⁺、Cd、As元素的致癌风险控制值取0.05mg/L、0.004mg/L和0.01mg/L;为保证填埋场区域地下水饮用安全,降低周边居民健康危害风险,非致癌因中NO3-N经所有途径导致的地下水非致癌健康风险控制值取17.96mg/L。综上可知,日喀则市垃圾填埋场一期场地对地下水影响较小,由于一期场地即将封场,二期场地即将投入运行,并且随着日喀则市垃圾收运效率的提高和垃圾成分日益复杂,为保证填埋场运行安全,降低填埋场对周边地下水环境污染风险,仍应对填埋场污染源及区域地下水环境状况给予特别关注,就填埋场污染源及区域地下水环境污染现状,积极采取有效的方法和手段,加强垃圾填埋场管理、强化污染源控制,防止污染扩散,必要时对污染的地下水及时进行修复。更多还原

【Abstract】 The way of municipal solid waste treatment and disposal is gradually changed to incineration,with the development of our country’s economy and society,and the awareness of the disadvantages of landfill disposal in China.However,as the last pure land of our country and an important national ecological security barrier,according to the relevant investigation:landfill is the main way of disposal of municipal solid waste in the qinghai-tibet plateau.Landfill leachateLandfill leachate is a kind of organic wastewater with complex composition and high concentration formed,if it leaks into the groundwater aquifer and will pollute the groundwater quality,and the pollution will last for decades or more.Contaminated groundwater will also pose a higher risk to the health of the population.Therefore,this paper analyzes and evaluates the source pollution risk of landfill site,groundwater vulnerability,groundwater quality and residents’health risk on the basis of data collection,field investigation,sample collection and analysis,so as to provide scientific basis for landfill site management,pollution prevention and control and ensure the safety of groundwater.The assessment result of source pollution risk shows that the comprehensive pollution risk of the first pHase of Shigatse landfill is 5.5,which is medium pollution.The second pHase of the landfill is about to be put into operation,the comprehensive pollution risk is high（Ii=6.1）due to the higher water content of the fresh garbage,and the landfill volume increases（the improved collection and transportation efficiency of municipal solid waste in the landfill site of Shigatse city）.Several years later,the comprehensive pollution risk is gradually reduced,presenting moderate pollution.The groundwater vulnerability was analyzed and evaluated with DRASTIC model,the results show that:The groundwater aquifer in the study area has strong antifouling property,groundwater is less likely to be contaminated.A total of 19 conventional indicators including pH,total hardness,sulpHate,permanganate index,nitrate（N）,nitrite（N）,ammonia nitrogen,chromium（hexavalent）,fluoride,chloride,cadmium,lead,arsenic,zinc,selenium,cyanide,mercury,iron and total dissolved solids were selected for detection and analysis,the results showed that the main pollution factors of groundwater are ammonia nitrogen,hexavalent chromium and iron in the study area.In 2014,the groundwater quality of Shigatse landfill was relatively poor.Among them,the exceeding rate of ammonia nitrogen was 100%,and the maximum exceeding rate was 1.88 times.The hexavalent chromium exceeding rate was 33.3%,the maximum exceeding multiple was 1.08times;The iron excess rate was 66.6%,and the maximum excess multiple was 1.07times.In 2015,2017 and 2018,the water quality was relatively good,and only iron showed varying degrees of contamination.The exceeding rate and the maximum exceeding multiple were 100%,33.3%,100%,2.33,2.22 and 1.4 times respectively,other elements meet the groundwater qualityⅢclass standard（GB/T14848-2017）.In2016,every test indexes meet the groundwater quality of groundwaterⅢclass standard（GB/T14848-2017）.The groundwater quality in the study area is good,the water quality of each monitoring well is relatively stable,and it is generally shown as Background well>diffusion well>monitoring well.The groundwater quality of the region is relatively good in each water period,the water quality of each monitoring well is relatively stable,and the comprehensive water quality is good.The comprehensive water quality status in different water periods was dry season>level period>wet season.The pollution degree of water quality in each monitoring well was analyzed and evaluated for each year based on groundwater qualityⅠclass standard（GB/T14848-2017）as the background value,the results show that the comprehensive pollution of groundwater quality in 2014,2015 and 2018 was light pollution.In 2016and 2017,the comprehensive pollution status of regional groundwater quality was non-pollution.The pollution status of each monitoring well is background well>diffusion well>monitoring well>monitoring well in duolin substation,and the comprehensive water quality status in different water periods was wet season>level period>dry season.Health risk assessment results show that the carcinogenic and non-carcinogenic risks to women are significantly higher than the health risks to men.The carcinogenic risk caused by all exposure pathways is ranked as CR_cgw>CR_iov3>CR_dgw,the comprehensive carcinogenic risk of each carcinogenic factor by all exposure pathways is shown as Cd（1.645E-06）>Cr⁶⁺（6.679E-07）>As（4.041E-07）.The Non-carcinogenic risk caused by all exposure pathways is ranked as HQ_cgw>HQ_iov3>HQ_dgw,the comprehensive carcinogenic risk of each Non-carcinogenic factor by all exposure pathways is shown as CN^-（0.02418）>F^-（0.01657）>As（0.01295）>Cr⁶⁺（0.00633）>Cd（0.00388）>NO₃-N（0.00224）>Hg（0.00129）>NO₂-N（0.00037）>Zn（0.00017）.The risk control values of carcinogenic factors(Cr⁶⁺,Cd and As)were 0.05 mg/L,0.004mg/L and 0.01 mg/L.In order to ensure the safe drinking of groundwater in the landfill area and reduce the health hazard risk of surrounding residents,the risk control value of non-carcinogenic factors（NO₃-N）by all exposure pathways was 17.96 mg/L.In summary,The first p Hase of Shigatse landfill has little effect on groundwater.Because the first pHase of the site will be closed and the second pHase of the site is about to be put into operation.In order to ensure the safe operation of landfill and reduce the risk of groundwater pollution with the improvement of waste collection and transportation efficiency and the complexity of waste composition in Shigatse city,special attention should still be paid to landfill pollution sources and regional groundwater condition.According to the current situation of landfill pollution sources and regional groundwater pollution,effective methods and means will be actively adopted to strengthen landfill management,strengthen pollution source control,prevent pollution from spreading,and repair contaminated groundwater timely if necessary.更多还原