【作者】 马文；

【导师】 戴九兰；

【作者基本信息】 山东大学 ， 分析化学， 2016， 硕士

【副题名】以多环芳烃和重金属为例

【摘要】 随着工农业的快速发展,土壤污染越来越引起人们的关注。污染物进入土壤,导致土壤生态环境的逐步恶化,一旦超过土壤本身的自净能力,就会通过植物的根系进入植物体内,不仅会影响其自身的生长发育,降低农产品的产量和质量,而且还会在作物中累积,通过食物链进入人体,危害人体健康。因此,研究土壤污染物的污染状况和分布特征对了解污染物对环境的潜在生态危害程度和对人类健康威胁大小具有十分重要的意义。常见的土壤污染物包括多环芳烃(PAHs)和重金属(Cd、Cr、Pb、Hg、As)。所以,本研究的主要集中对南四湖地区水稻土中PAHs的含量及某工矿区农田土壤中五种重金属的含量进行分析,研究PAHs及重金属在土壤中的分布特征,并对其进行来源分析和生态风险评估及人体健康风险评价,而且还对该工矿区农田土壤中重金属的形态(弱酸提取态、可还原态、可氧化态和残渣态)进行了研究。主要研究结果如下:1、南四湖地区农田土壤中多环芳烃(PAHs)来源解析与风险评价依据欧洲国家标准和内梅洛指数评价标准,发现WS地区土壤存在重度污染。主成分分析和Pearson相关分析结果显示该地区PAHs主要受土壤粒径的影响,其中砂粒易对高环数的PAHs产生较强的吸附作用,粘粒与PAHs之间存在显著地负相关性。通过源解析发现其主要污染来源为周围煤矿和发电站等燃烧煤炭,含有石油类污染物灌溉水也是来源之一。污染场地暴露CLEA模型结果显示,南四湖地区土壤中PAHs不会对儿童和成人的身体健康产生威胁,但是对儿童造成的危害要大于成人,其中三种途径引起的风险大小:经口摄入>皮肤接触>呼吸吸入,不同采样点引起的致癌风险大小:WS>TF>JX>XZ>QH>SZ。2、某工矿区周围农田土壤中重金属来源解析与风险评价某工矿区周围农田土壤中Cd、Cr、Pb、As、Hg五种重金属含量分别是山东省背景值的5.6、1.05、2.03、1.42、7.86倍,而且重金属Cd超过国家二级标准的限量值,通过主成分分析和Pearson相关性分析发现pH和阳离子交换量对重金属的影响最小;另外,重金属Cd、As、Hg受土壤环境变化影响小;Cr与游离氧化铁铝、砂粒和粘粒成显著正相关,且与砂粒的相关系数(0.274)小于与粘粒的相关系数(0.345);Cr含量与粉粒呈显著负相关;重金属Pb与有机质和砂粒呈显著正相关。潜在生态风险危害系数Ei显示重金属Cr的污染最轻,As和Pb轻微污染,Cd和Hg的污染最为严重,另外,潜在生态危害指数IR、内梅洛指数P和地积累指数Igeo如结果显示重金属综合污染严重。导致该工矿区周围农田土壤重金属污染的主要原因是工业“三废”的排放和附近的采矿活动,农田施磷肥、喷洒含重金属的农药、杀虫剂也是其来源之一。健康评价结果说明该工矿区周围农田土壤中重金属不会对人体的身体健康产生明显的致癌和非致癌影响。3、某工矿区周围农田土壤中重金属赋存形态的研究重金属Cr、As和Hg的残渣态占主要成分,分别占总含量的62.39%、72.26%和89.84%,且难利用态(K3)>中等利用态(K2)>可利用态(K1),易利用态含量最少,分别占总含量的5.6%、13.41%和2.22%,不易被外界生物利用;Cd和Pb的可利用态含量最高,分别占总含量的47.76%和48.84%,K1>K3>K2,易对生物造成影响。相关性研究显示,重金属Cd、Pb和As不同形态与总量之间的相关程度较高;重金属各赋存形态受土壤环境因素的影响规律与重金属总量受土壤环境因素的影响规律相同,Cd四种赋存形态含量受土壤环境影响程度小,Cr可还原态与土壤有机质呈显著负相关,Hg可氧化态与阳离子交换量呈显著负相关,Pb和As赋存形态与土壤性质之间存在显著的相关性。通过对重金属形态进行RAC和RSP风险评价,发现五种重金属风险大小:Cd>As>Cr>Hg>Pb,污染水平大小:Pb>Cd>Cr>As>Hg。本研究结果为该研究地区农田土壤中污染物的控制和环境管理奠定了基础,还为该地区的健康评估结构提供了科学依据,具有环境和健康双重意义。更多还原

【Abstract】 Soil pollution aroused people’s concern increasingly,as the rapid development of industry and agriculture.Pollutants are into the soil,resulting in progressive deterioration of soil ecological environment.Once the content is over soil self-purification capacity,the pollutants will be into the plant through the roots.It can not only affect its own growth and development,leading to the production and quality of agricultural products reduced,but also accumulate in the crops,further endanger human health through food chain.Therefore,research on the soil pollutants status and distribution is of great significance to understand the pollutants potential risk to ecological environment and human health.Polycyclic aromatic hydrocarbons(PAHs)and heavy metals like cadmium(Cd),chromium(Cr),plumbum(Pb),mercury(Hg)and arsenic(As)are common contaminants in soil.Thus,this study mainly focused on the PAHs in paddy soils in Nansi lake area and five heavy metals in farmland soils around mining areas.The distribution characteristics of these pollutants were analyzed,and further conducted the source analysis and ecological and human health risk assessment.In addition,four fractions(acid-soluble,reducible,oxidizable and residual fractions)of five heavy metals in farmland soil around mining areas were determined.The results showed:1 Source analysis and risk assessment of PAHs in paddy soil in Nansi lake areaBased on the pollution levels of Western Europe and on the nemerow composite index,only the WS region was highly contaminated.Using principal component analysis and Pearson correlation analysis,this study revealed that soil PAHs in this area was mainly affected by soil particle size distribution,of which sand particles had strong adsorption on the high-rings PAHs and clay has significantly negative correlations with PAHs.The dominant source was the coal combustion of coal mining and power plants.Irrigation with petroleum-polluted water was also one of source.Contaminated land exposure assessment(CLEA)model showed PAHs in soil in Nansi lake area cannot threat the health to children and adults,but the risk for children was higher than that for adults.The distribution of exposure ways decreased in the order of oral intake>skin contact>inhalation,and the distribution of sampling sites decreased in the order of:WS>TF>JX>XZ>QH>SZ.2 Source analysis and risk assessment of heavy metals in farmland soil around mining areasFive heavy metals(Cd,Cr,Pb,As,Hg)contents in farmland soil around mining areas were 5.6,1.05,2.03,1.42 and 7.86 times higher than background value of Shandong province respectively.And Cd cotent was over the limited value of national secondary standard.Based on principal component analysis and Pearson correlation analysis,heavy metals were slight influenced by pH and soil cation exchange capacity(CEC).In addition,soil environment affected Cd,As and Hg contents slightly.Correlation between Cr content and free Al and Fe oxide,sand,clay was positive significantly,while correlation between Cr content and silt was negative significantly.Correlation between Pb content and soil organic matter,sand was positive significantly.The result of ecological risk assessment showed that Cr pollution was light,As and Pb were slightly polluted,and Cd and Hg pollution was high.The comprehensive pollution of heavy metals was serious.The dominant source was three industrial wastes emissions and mining activities.Phosphorus fertilizer and pesticides containing heavy metals application was also one of the source.Five heavy metals did not produce cancer and non-cancer risk for human health.3 Chemical Speciation of heavy metals around mining areasThe reducible fraction was the main proportion of Cr,As and Hg in soils,accounted for 62.39%,72.26%and 89.84%respectively.Hard used fraction(K3)was dominated,followed by moderate used fraction(K2)and available fraction(Ki).The content of available fraction was least,accounted for 5.6%,13.41%and 2.22%respectively,so that they can hard to be used by outsiders.Cd and Pb were dominated in K1,accounted for 47.76%and 48.84%respectively,followed by K3 and K2,which indicated they can be easily into the environment and affect creatures.Correlation analysis declared that Cd,Pb and As fractions content had significant correlation with their total content.The influence of soil basic properties to different heavy metal fractions content was same as that to total heavy metals content.The effect of soil environment to Cd fractions content was small.Reducible fraction of Cr was significantly influenced by soil organic matter.Oxidizable fraction of Hg was influenced by cation exchange capacity significantly.Correlation between soil properties and Pb and As fractions was significant.The results of the RAC and RSP risk assessment found that the risk caused by five heavy metal was decreased in the order of Cd>As>Cr>Hg>Pb,and pollution level was decreased in the order of Pb>Cd>Cr>As>Hg.This study established a foundation for the control of pollutants in farmland soil and environmental management.It also provides a scientific basis for the health assessment in this region.So it has double significance of environment and health.更多还原