常州市道路两侧户外灰尘重金属分布、形态及环境风险

在常州市城区、城郊和农村20个道路断面50 m范围内采集140个户外灰尘样品,测定Cu、Zn、Pb、Cd、Ni、Cr和Mn等重金属的含量,分析其区域差异、垂直分布和化学形态特征,进行富集系数和污染系数分析,并构建了涵盖灰尘重金属含量、形态和毒性的环境风险指数.结果表明,以上各重金属含量平均值分别为173.51、952.66、444.50、3.16、115.64、132.44、801.59 mg·kg-1.随着楼层的升高,城区灰尘中Pb、Mn和Cr的含量呈递减趋势,Cd、Cu和Zn含量没有显著变化,Ni含量呈上升趋势.Cu和Cr主要为残渣态,Zn、Pb和Cd主要为可还原态,Ni主要为酸可提取态.Cd的环境风险等级为严重,Pb为重或严重,Cu和Zn为较低或中,Ni为中,Cr和Mn为低.     

洞庭湖湘江入湖口至出湖口水域表层沉积物中重金属时空分布特征与生态风险

基于2007—2012年连续对洞庭湖湘江入湖口至出湖口水域5个采样点的表层沉积物中Cd、Hg、As、Cu、Pb、Cr和Zn等7种重金属含量分析,对该水域表层沉积物中重金属的时空分布特征进行了探讨,并采用沉积物质量基准法对其生态风险进行了评价.结果表明,Cd、Hg、As、Cu、Pb、Cr和Zn的含量分别为0.54—79.90 mg·kg-1、0.046—0.712 mg·kg-1、15.2—289.0 mg·kg-1、29.0—217.0 mg·kg-1、6.0—246.0 mg·kg-1、65.4—269.0 mg·kg-1和41.4—632.0 mg·kg-1,其大小顺序为ZnCrPbCuAsCdHg;Cd、Hg、As、Cu、Pb和Zn含量沿程总体呈"V"形变化趋势,Cr含量沿程变化较小,重金属含量年际变化较为稳定;As具有较高生态风险,其余污染物具有较低生态风险,不同污染物生态风险的大小顺序为AsCdCrCuPbZnHg,S1和S3具有较高生态风险,其余点位具有较低生态风险,不同点位生态风险的大小顺序为S1S3S5S2S4.     

大型垃圾焚烧厂周边土壤重金属含量水平、空间分布、来源及潜在生态风险评价

通过采集珠三角东部某市大型垃圾焚烧厂周边表层土壤样品,分析了各样品中Cd、Pb、Hg、As、Cr、Cu、Ni、Zn和Co等9种重金属含量,研究了重金属的含量水平、空间分布、来源及潜在生态风险。结果表明,研究范围内表层土壤重金属含量分别为Cd(0.183±0.07)mg·kg-1、Pb(34.8±18.7)mg·kg-1、Hg(0.081±0.028)mg·kg-1、As(11.5±9.1)mg·kg-1、Cr(31.5±19.1)mg·kg-1、Cu(17.6±12.3)mg·kg-1、Ni(7.13±4.20)mg·kg-1、Zn(82.4±44.2)mg·kg-1、Co(3.37±3.08)mg·kg-1。其中,Hg和Zn的含量分别超出广东省土壤历史背景值1倍和2倍,其余重金属含量与背景值相差不大。综合空间分布特征分析、相关性分析、聚类分析和主成分分析的结果,可以将9种重金属分为4类。Cr、Ni、Cu、Co的分布特征极为相似,且相互之间有极显著相关性,结合聚类分析和主成分分析结果,其来源主要为土壤母质。As、Zn、Pb的空间分布特征具有一定相似性,但相关性分析和聚类分析显示元素间联系不紧密,结合主成分分析结果,其来源与土壤母质和多种人类活动污染有关。Cd和Hg的空间分布特征均显示这两种重金属与垃圾焚烧厂存在联系,Cd与垃圾焚烧厂存在一定联系,而Hg与垃圾焚烧厂存在较强联系。潜在生态风险评价结果显示,该研究区域土壤重金属生态风险不高,多种重金属的综合潜在生态风险指数(RI)的范围为51~269.79,Hg和Cd对RI的贡献率相对较大,分别为52.33%和18.30%。研究表明,垃圾焚烧厂周边表层土壤Hg具有独特的环境污染特征,在垃圾焚烧厂周边的土壤重金属污染调查中,Hg污染应受到重点关注。     

中国沿海水生生物污染数据集及食用水产品的健康危害评估

沿海区域是污染物的汇集区域,污染物的生态风险和健康危害广受关注.亟需开展污染物的监测,评估污染的生态风险.已有研究提供了不同水域不同水生生物中各类污染物的含量数据,但尚缺乏系统的沿海区域生物体污染物含量的数据集,无法为沿海区域生态风险及其人体健康危害评估提供数据支撑.本研究通过CNKI、Web of Science和PubMed数据库,搜集了2000—2019年间沿海区域物种-污染物含量相关文献的数据,建立了中国沿海水生生物污染数据集.进一步提取了常见软体动物和鱼类的重金属含量数据,运用靶标危害系数(target hazard quotients,THQ)模型进行了食用危害评估.结果显示,中国沿海区域软体动物中的8种重金属平均浓度从高到低依次为锌(317.939 mg·kg-1)、铜(87.792 mg·kg-1)、铅(14.428 mg·kg-1)、铬(11.459 mg·kg-1)、锰(5.384 mg·kg-1)、砷(1.332 mg·kg-1)、镍(1.011 mg·kg-1)和汞(0.384 mg·kg-1).而鱼类中这8种重金属的平均浓度梯度为锌(172.025 mg·kg-1)、铜(11.637 mg·kg-1)、铅(9.604 mg·kg-1)、锰(1.808 mg·kg-1)、镍(1.573 mg·kg-1)、砷(0.802 mg·kg-1)、铬(0.546 mg·kg-1)和汞(0.023 mg·kg-1).THQ模型预测结果表明,重金属并不会对成人产生健康影响,唯一例外的是,砷元素污染可能会对儿童产生潜在的健康危害.综上,本数据集提供了中国沿海区域物种的污染物含量数据,为污染物引起的人体健康危害评价提供了数据支撑.     

准好氧填埋场垃圾中重金属化学形态分布特征

通过模拟准好氧填埋场中试试验,对垃圾原样和经准好氧填埋消化8个月后不同空间位置固体样中重金属含量、化学形态分布和迁移性进行研究.结果表明,垃圾原样中Pb,Ni,Cr,Cu和Fe的含量分别为88 mg·kg-1,52 mg·kg-1,304.667 mg·kg-1,29 mg·kg-1 和1632.67 mg·kg-1.垃圾原样中Ni和Cu以残渣态所占比例最高,分别为60.26%和60.92%,Pb以有机物结合态所占比例最高,为54.92%,Cr以铁锰氧化物结合态所占比例最高,为57.44%,而Fe以铁锰氧化物结合态、有机物结合态、残渣态为主,所占比例相近,为31%-34%左右.垃圾经准好氧填埋消化8个月后,Pb,Ni的有机物结合态所占比例降低,可交换态、碳酸盐结合态或铁锰氧化物结合态所占比例增加;Cu,Fe残渣态所占比例降低,可交换态、碳酸盐结合态或有机物结合态所占比例增加;Cr铁锰氧化物结合态所占比例降低,碳酸盐态或残渣态所占比例增加,金属活性增大.垃圾中Fe,Ni,Pb的迁移能力较强,迁移能力依次为Fe＞Ni＞Pb＞Cr＞Cu.     

金昌市郊农田土壤Cu,Zn,Ni形态分布特征与生物有效性评价

通过野外调查和室内测试分析,研究了金昌市郊农田土壤重金属Cu,Zn和Ni的形态特征,并以麦粒中重金属含量为重点进行了Cu,Zn和Ni的生物有效性评价.结果表明,研究区域土壤重金属Cu和Ni污染严重;Cu的主要存在形态为有机结合态,Zn的主要存在形态为残渣态,而Ni的主要存在形态为潜在可利用态;三种元素的生物有效性大小顺序为NiZnCu.对麦粒中重金属健康风险进行评价反映出麦粒中Ni含量对人体健康风险较大,而Cu和Zn对人体健康风险较小.逐步回归分析结果表明,农田土壤中Cu可交换态和碳酸盐结合态对麦粒中Cu含量贡献最大,而对麦粒吸收Zn和Ni贡献最大的形态分别为Zn的碳酸盐结合态和Ni的可交换态、碳酸盐结合态、铁锰氧化态和有机结合态.土壤重金属Cu,Zn和Ni各形态分配系数较总量和各形态含量更适合表征本研究区域土壤重金属的生物有效性.     

天津公园土壤重金属污染评价及其空间分析

随着城市化和工业化进程的加快,我国城市及其周边目前已遭受到明显的重金属污染,本文着重研究了天津17个主要公园土壤重金属的污染特征。2007年10月采集公园土壤样品,利用ICP-MS分析土壤重金属的含量。研究结果表明：Cu、Zn、Ni、Cr、Cd和Pb的平均质量分数分别为36.57mg·kg-1,116.56mg·kg-1,30.15mg·kg-1,51.04mg·kg-1,0.25mg·kg-1和31.62mg·kg-1。以天津市土壤背景值为评价标准,天津公园土壤重金属污染属于中度污染和轻微生态风险。重金属主要污染因子为Cd,其次是Pb、Zn和Cu。天津中环线以内区域公园土壤重金属污染较中外环线之间相比较重。不同行政区划区域公园土壤重金属污染从综合污染指数来看,由重到轻的顺序为：红桥区〉河北区〉河东区〉南开区〉河西区〉和平区〉北辰区;从潜在生态指数评价来看,由重到轻的顺序为：红桥区〉河北区〉河东区〉南开区〉河西区〉北辰区〉和平区。     

小清河污灌区农田土壤重金属形态分析及风险评价

选取小清河污灌区农田为研究区域,采集31个表层土壤样品,测定了土壤重金属(Cd、Cr、Cu、Zn、Ni、As和Pb)含量,采用改进的BCR顺序提取法对土壤重金属的形态进行分析,并基于潜在生态风险指数法和风险编码法(RAC)对土壤中重金属的生态风险进行评估.结果表明,小清河污灌区土壤中Cd、Cr、Cu、Zn、Ni、As、Pb平均含量分别是0.37、51.61、32.62、68.49、34.12、40.77、32.26 mg·kg~(-1).土壤中Cr、Zn、Ni、As以残渣态占绝对优势,Cu以残渣态和可氧化态为主,Pb则以可还原态为主,而Cd表现出了形态多样的分布特征;重金属生物活性大小排序为:Cd Pb Cu Zn As Ni Cr;潜在生态风险指数法的评价结果表明,Cd处于中度-很强风险水平,As处于轻微-中度风险水平,其他重金属为轻微风险水平.综合潜在生态风险指数RI值在51.23—199.33,处于轻微-中等风险水平,Cd、As是土壤重金属的主要风险源,其对综合潜在生态风险指数的贡献率分别为57%、31%;RAC评价结果表明,土壤Cd处于中度-高风险水平,Zn处于低-中度风险水平,其他重金属为低风险水平.     

复合添加剂对污泥堆肥化重金属形态及生物有效性的影响

通过添加不同比例粉煤灰(0%、5%、15%、25%、35%)和生石灰(0%、1%)进行污泥堆肥试验,并将堆肥产品应用于玉米幼苗盆栽试验,研究不同处理对污泥堆肥产品重金属(Zn、Cu、Cd、Ni)形态分布和生物有效性的影响。研究结果可为粉煤灰和生石灰复合添加剂在城市污泥堆肥中的应用提供基础资料和科学依据。结果表明,(1)污泥堆肥过程中,p H值整体呈现上升-稳定下降-稳定的变化规律,重金属Zn、Cu、Cd、Ni含量因稀释效应呈现轻微下降;添加35%粉煤灰和1%生石灰处理,重金属Zn、Cu、Cd、Ni含量达到最小值,分别为611.20、226.18、1.49、68.74 mg?kg~(-1)。(2)Zn、Cd、Ni主要以残渣态形式存在,Cu主要以有机结合态形式存在。随着粉煤灰添加量增加,残渣态、有机结合态、铁锰氧化态Zn、Cd和残渣态、有机结合态Ni含量逐渐增大,交换态、碳酸盐态Zn、Cd、Ni含量逐渐减小,重金属生物有效性下降。(3)施用添加25%粉煤灰和1%生石灰的污泥肥料后,玉米地上部分干重最大为21.2 g,玉米重金属Zn、Cu、Ni、Cd含量均达到最小值19.44、13.73、0.08、0.45 mg?kg~(-1),基质重金属Zn、Ni分别达到最小值79.44、0.75 mg?kg~(-1)。以上结果说明,添加粉煤灰和生石灰进行污泥堆肥化对重金属总量影响不大,但能有效改变重金属形态,降低重金属生物有效性。其中,添加25%粉煤灰与1%生石灰污泥堆肥产品,有利于重金属由不稳定态转变成稳定态,也最有利于玉米幼苗生长。     

成都平原表层水稻土重金属污染健康风险分析

采样分析了成都平原表层水稻土(0—20 cm)中As、Cd、Cr、Hg、Pb、Cu、Zn含量,参照国家土壤环境质量标准和土壤背景值,并利用健康风险评价模型对土壤重金属环境质量状况和人体健康风险进行了评价.结果表明,成都平原水稻土表层7种重金属平均含量分别为As:9.69 mg·kg-1、Cd:0.12 mg·kg-1、Cr:79.5 mg·kg-1、Hg:0.04 mg·kg-1、Pb:47.5 mg·kg-1、Cu:29.3 mg·kg-1、Zn:81.7 mg·kg-1.与成都地区土壤背景值相比,As、Cr、Pb、Cu、Zn在表层水稻土中有明显积累,部分样区土壤重金属超过《土壤环境质量标准》(GB15618—1995)标准值的二级标准,存在外源污染输入,但污染程度较轻.人体健康风险分析结果表明,经土壤-口接触行为摄入是该区域人体重金属暴露风险的主要途径,重金属致癌风险AsCd,非致癌总风险CrCuHgPbZn,无论儿童还是成人,重金属致癌风险值和非致癌风险值均低于风险阈值,风险值均在可接受水平内,但儿童健康风险值高于成人,应加强监管.     

宝鸡城市街尘、土壤及河流沉积物重金属形态迁移特征

在宝鸡城市街尘、土壤及河流沉积物基本理化性质和重金属元素含量分析的基础上,重点研究了重金属元素在街尘、土壤及河流沉积物中的赋存形态和迁移特征.结果表明:在街尘中Cu主要以可氧化态和残余态形式存在,Pb主要以可还原态和可氧化态形式存在,Zn和Cd主要以乙酸可提取态形式存在,Mn、Fe、Co、Ni和Cr主要以残余态形式存在...     

Selective recovery of Cu, Zn, and Ni from acid mine drainage

In Korea, the heavy metal pollution from about 1,000 abandoned mines has been a serious environmental issue. Especially, the surface waters, groundwaters, and soils around mines have been contaminated by heavy metals originating from acid mine drainage (AMD) and mine tailings. So far, AMD was considered as a waste stream to be treated to prevent environmental pollutions; however, the stream contains mainly Fe and Al and valuable metals such as Ni, Zn, and Cu. In this study, Visual MINTEQ simulation was carried out to investigate the speciation of heavy metals as functions of pH and neutralizing agents. Based on the simulation, selective pH values were determined to form hydroxide or carbonate precipitates of Cu, Zn, and Ni. Experiments based on the simulation results show that the recovery yield of Zn and Cu were 91 and 94 %, respectively, in a binary mixture of Cu and Zn, while 95 % of Cu and 94 % of Ni were recovered in a binary mixture of Cu and Ni. However, the recovery yield and purity of Zn and Ni were very low because of similar characteristics of Zn and Ni. Therefore, the mixture of Cu and Zn or Cu and Ni could be recovered by selective precipitation via pH adjustment; however, it is impossible to recover selectively Zn and Ni in the mixture of them.     

典型城市污染水体底泥中重金属形态分布和相关性

采用Tessier五步连续提取法,研究了南京市莫愁湖、玄武湖、秦淮河13个底泥样品中的重金属的形态分布情况,分析了重金属浸出量与各形态间的相关性及有机质与有机结合态的相关性,并通过红外谱图分析了有机质与重金属结合的机理.结果表明:底泥中Pb,cu,zh,Ni,Cr主要以有机结合态和残渣态俘在,两种形态的含量占总量70%以上,Zn和Cd的可交换态和碳酸盐结合态含量相列较高,Zn约占20%,Cd约占30%;Zn,Cu,Cd,Ni,Cr的浸出量均与可交换离子态呈现显著的相关性,因此可通过减小可交换离子态含量控制底泥重金属污染的风险性;研究还表明,有机质与有机结合态呈现显著的正相关,因此增加底泥中有机质含量有助于重金属向有_棚结合态转化,有机质与重金属的结合主要是由于其中-些官能团和重金属形成稳定的络合物.     

Characteristics,sources and health risk assessment of toxic heavy metals in PM<Subscript>2.5</Subscript> at a megacity of southwest China

Twenty trace elements in fine particulate matters (i.e., PM_2.5) at urban Chengdu, a southwest megacity of China, were determined to study the characteristics, sources and human health risk of particulate toxic heavy metals. This work mainly focused on eight toxic heavy metal elements (As, Cd, Cr, Cu, Mn, Ni, Pb and Zn). The average concentration of PM_2.5 was 165.1 ± 84.7 µg m^?3 during the study period, significantly exceeding the National Ambient Air Quality Standard (35 µg m^?3 in annual average). The particulate heavy metal pollution was very serious in which Cd and As concentrations in PM_2.5 significantly surpassed the WHO standard. The enrichment factor values of heavy metals were typically higher than 10, suggesting that they were mainly influenced by anthropogenic sources. More specifically, the Cr, Mn and Ni were slightly enriched, Cu was highly enriched, while As, Cd, Pb and Zn were severely enriched. The results of correlation analysis showed that Cd may come from metallurgy and mechanical manufacturing emissions, and the other metals were predominately influenced by traffic emissions and coal combustion. The results of health risk assessment indicated that As, Mn and Cd would pose a significant non-carcinogenic health risk to both children and adults, while Cr would cause carcinogenic risk. Other toxic heavy metals were within a safe level.     

Fractionation of Heavy Metals in Surface Sediments of Taihu Lake, East China

The BCR (European Communities Bureau of Reference) three-step sequential extraction procedure was applied to fractionate heavy metals in the sediment of Taihu Lake. For the determination of total metal concentration of the sediments, sample digestion was achieved by using HF/H₂O₂/HNO₃(2/1/1) acid mixture in a microwave-irradiated closed vessel system. The concentrations of Cd, Ni, Cr, Zn, Cu and Pb in various extracts solutions were analyzed by Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-AES). The results obtained from the BCR three-step sequential extraction indicated relatively high mobility of Zn, Cu, Pb and Ni in the sediments while Cd and Cr were poorly mobile. Enrichment of heavy metals was found in the sediments collected in the northern parts of Taihu Lake. In the sediments collected in the southern and western sides of the Lake, heavy metal concentrations were relatively low. The relationship between total organic carbon (TOC) and heavy metals concentrations in the sediments is discussed.     

电镀厂污染土壤重金属形态及淋洗去除效果

以某电镀厂污染场地重污染区域土壤为研究对象,对土壤中重金属全量和各形态含量进行分析,并研究筛选高效土壤淋洗剂,比较其淋洗去除效果。结果表明,该土壤以铬和镍污染最为严重,土壤铬和镍含量分别达1 564.00和679.00 mg.kg-1,土壤铜、锌和铅含量分别为297.00、276.00和51.40 mg.kg-1,铜、铬、镍、锌和铅的有效态比例分别为41.77%、13.16%、28.08%、21.50%和31.18%。去离子水、盐酸、乙酸、草酸、柠檬酸和EDTA 6种淋洗剂中,去离子水对5种重金属提取量均较少;草酸对铜、铬、镍和锌去除效果较好,去除率分别为55.1%、24.8%、47.5%和29.3%;柠檬酸对铜、铬、镍和锌去除效果较好,去除率分别为26.3%、25.7%、33.0%和21.6%;EDTA对铜、镍、锌和铅去除效果较好,去除率分别为31.5%、28.9%、21.4%和30.6%。综合考虑淋洗剂的提取效果、水溶性以及操作难度和成本,建议采用柠檬酸作为淋洗剂,最佳液土比〔V（液）∶m（土）〕为10∶1,最佳淋洗时间为6 h。     

粤西三座重要供水水库沉积物营养盐负荷与重金属污染特征

为揭示粤西3座供水水库（高州水库、鹤地水库、大水桥水库）沉积物营养盐负荷及重金属污染特征,于2008年6月在各水库大坝前湖泊区采集柱状沉积物,运用SMT法、碱性过硫酸钾消解法、烧失法和ICP-MS法分别测定其柱状沉积物中氮磷营养盐、有机质和7种重金属（Cu、Pb、Zn、Cd、Ni、Cr与Hg）的含量,并采用潜在生态风险指数法对表层重金属污染的潜在生态风险进行评价,同时通过相关性分析重金属的可能来源。结果表明：3座水库沉积物总氮质量分数为1.13~3.37 mg·g-1,有机质为11.83~20.37 mg·g-1,其表层总氮、有机质的质量分数大小顺序为高州水库〉大水桥水库〉鹤地水库,总磷的质量浓度在0.22~0.77 mg·g-1之间,其表层总磷质量分数大小顺序为高州水库〉鹤地水库〉大水桥水库,在垂直剖面上,总氮、总磷与有机质的质量分数在16 cm至表层沉积物垂直断面显著高于其他断面,表明近些年来水库内源营养盐负荷逐渐加重。重金属质量分数平均值均高于广东省土壤环境背景值,总体呈现随深度增加而降低的趋势,但3座水库间重金属质量分数差异较大,其中鹤地和高州水库的Zn和Pb污染相对严重（质量分数分别为Zn：353.15、693.35 mg·kg-1;Pb：74.51、127.91 mg·kg-1）,大水桥水库的Cr和Ni污染相对严重（质量分数分别为Cr：238.69 mg·kg-1;Ni：251.06 mg·kg-1）。潜在生态风险评价表明,3座水库Cd和Hg具有高的生态危害,应引起重视,其他重金属则处于轻微的生态危害等级。同时沉积物高有机质的质量浓度经矿化分解可能加剧水体重金属生态危害。根据相关性分析和其他相关资料可知,粤西农业区大量化肥农药面源污染汇入造成水库初级生产力提高并最终沉降可能是沉积物营养盐、有机质与重金属的主要来源。     

Heavy metals and organic carbon in sediments from the Tuy River basin,Venezuela

The Tuy River basin, located in north-central Venezuela with an annual average temperature of 27°C and precipitation of 140 cm, was selected to conduct a geochemical study of bottom sediments, with the object of establishing the natural and human influences in the abundance and distribution of Fe, Mn, Cr, Co, Cu, Ni, Pb, Zn and organic carbon. The basin is lithologically divided into two sub-basins, north and south. The north sub-basin drains a iow-grade metasedimentary terrain with a population density of 800 persons km^–2 and approximateiy 600 industrial sites, while the south sub-basin in underlain by metavolcanic and ultramafic rocks, with a population density of less than 10 persons km^–2.Stream bottom sediment samples (150) were collected during the years of 1979–1986 in 16 unpolluted sites and 13 polluted sites. The sediments were air dried at room temperature and sieved through a 120 stainless steel mesh (125 m). Samples of grain size smaller than 125 m were analysed, the heavy metals being determined by atomic absorption spectrometry and the organic carbon (Corg) by dry combustion.The higher concentrations of heavy metals and organic carbon found in the pristine areas were in the south sub-basin, especially in those areas with higher annual precipitation and tropical forest. This indicated that the metavolcanic and ultramafic rocks yield higher concentrations of heavy metals than the metasedimentary rocks. It was also noted that the higher concentrations of Cr and Ni are associated with the ultramafic rocks. The results obtained from the sediment samples collected in the polluted sites showed that the elements Pb, Zn and Corg are enriched up to 4 times as a result of ail the human activities taking place in the basin. Organic carbon is an excellent indicator of domestic wastewater, Pb and Zn are good indicators of the automotive traffic and industrial effluents. The concentrations of each heavy metal did not show any significant correlation with grain size fractions; however, the concentration of organic carbon did show a negative correlation with grain size. The lithological, climatic and vegetation influence in the abundance of heavy metals and organic carbon in stream sediments clearly indicates the necessity of establishing background levels for the area under study when carrying out studies in environmental geochemistry.     

粤北星子河水生生物体内重金属污染特征及健康风险

本文分析了粤北星子河12种水生生物样品中Cd、Cr、Cu、Pb、Ni和Zn等6种金属元素的含量水平。利用综合污染指数法和目标危害系数法对水生生物中重金属的污染特征及其健康风险进行评价。结果表明:不同水生生物对重金属的富集程度存在明显差异,重金属的含量水平从低到高顺序依次为:CdNiPbCrCuZn;鱼类富集重金属明显低于贝类。在贝类样品中,Cr、Pb和Zn的含量均出现超标现象。鱼类重金属综合污染指数低于1,属于微污染;而田螺重金属综合污染指数大于1,属于轻度污染水平。不同鱼类中重金属的复合健康危害系数(TTHQ)均小于1,且每周评估摄入量(EDI)均远低于暂定每周允许摄入量(PTWI),居民通过鱼类摄入重金属的健康风险较低;田螺中重金属对人的复合健康危害系数大于1,长期食用田螺存在较高的健康风险,风险较高的重金属元素为Cr、Pb和Zn。     

Effect of acid rain on the fractionation of heavy metals and major elements in contaminated soils

Acid rain is a serious environmental problem worldwide. In the present study, we investigated the effect of acid rain (1:1 equivalent basis H₂SO₄:HNO₃) at pH values of 2.0, 4.0 and 7.0 on the fractionation of heavy metals (Cd, Cu, Fe, Mn, Ni, Pb and Zn) and major elements (K, Na, Ca, and Mg) in contaminated calcareous soils over a 2084 h period. Heavy metals and major elements in soil samples were fractionated before and after 2084 h kinetic release using a sequential extraction procedure. Before kinetic studies the predominant fractions of K, Na, Ca, Mg, Cd and Ni were mainly associated with carbonate fraction (CARB), whereas Fe, Mn and Zn were associated with the Fe–Mn oxide fraction (Fe–Mn oxide). The highest percentage of Pb and Cu were found in the exchangeable (EXC) and organic matter (OM) fractions, respectively. After kinetic study using different simulated acid rain solutions, the major fractions of heavy metals (expect of Cu) and Na was the same as before release. Upon the application of different acid rain solutions, K and Mg were found dominantly in Fe–Mn oxide fraction, whereas Ca was in the EXC fraction. The results provide valuable information regarding metal mobility and indicated that speciation of metals (Cu and Zn) and major elements in contaminated calcareous soils can be affected by acid rain.