夏季青岛大气粗细粒子中微量元素的浓度、溶解度及干沉降通量

利用2016年6~7月在青岛采集的PM_(2.5)和总悬浮颗粒物(TSP)样品,分析其中12种微量元素总态和溶解态浓度,讨论了微量元素在粗、细粒子中的浓度及溶解度的分布特征,并估算了微量元素的沉降通量.结果表明,青岛气溶胶中地壳元素Al、Fe、Sr、Mn、Ba总态浓度的55%~60%集中在粗粒子中,人为元素Cr、Ni、V、Zn、Pb、As、Cd的65%~85%集中在细粒子中.但无论是地壳元素还是人为元素其溶解态浓度均主要分布在细粒子中,Al、Fe、Mn、Ba在细粒子中的占比为50%~80%,Cr、Ni、V、Zn、Pb、As、Cd的为70%~90%.微量元素溶解度在细粒子中的高于粗粒子中的,细粒子中微量元素的溶解态浓度与酸组分呈显著正相关,溶解度与p H呈显著负相关,表明酸化作用可能是影响细粒子中微量元素溶解度的主控因子.不同微量元素的总沉降通量中溶解态部分的贡献不同,Al和Fe溶解态部分的贡献仅为1%~2%,Sr、Ba、Cr、Pb的约为30%~40%,Mn、Ni、V、Zn、As、Cd的约为50%~60%.大气沉降的溶解态Fe可支持(194±150)mg·(m2·d)-1浮游植物碳的生产,对黄海初级生产力的贡献约为10%.     

Atmospheric dry deposition flux of metallic species to the North Sea

Air sampling on a series of 10 research cruises on the North Sea (south of 56°N) has yielded detailed spatial distributions of atmospheric metal concentrations, Al, Ca, Cd, Cu, Fe, Mg, Na, Pb and Zn which closely parallel the results of earlier published models. Air mass back trajectory analysis demonstrates the strong influence which source region may have upon the elemental composition of the North Sea atmosphere. A cascade impactor designed to collect efficiently large as well as small aerosol has produced detailed size distributions from which mass weighted deposition velocity estimates have been produced (Al, 0.33; Cd, 0.24; Cu, 0.44; Fe, 0.30; Pb, 0.13; Zn, 0.30 cm s⁻¹) enabling estimates for the dry deposition flux to the study area to be made. Extrapolation of these data to the whole of the North Sea yields dry deposition flux estimates (Cd, 33; Cu, 350; Pb, 370; Zn, 2640 tonnes yr⁻¹) which are in some instances substantially lower than those previously reported, but nevertheless represent a significant pathway for metallic species to enter this marine environment. The size distributions show the clear dominance that large aerosol has upon the overall dry deposition flux. Flux estimates are thus highly sensitive to the sampling of this large aerosol component, and to assumptions made regarding the sea surface as a source of giant trace metal-enriched particles which act only as a means of recycling marine metals.     

Metal release/accumulation during the decomposition of Potamogeton crispus in a shallow macrophytic lake

Changes in metal concentrations in the litter of Potamogeton crispus were monitored during a consecutive 40-day in situ decomposition experiment using the litterbag method.The accumulation index was calculated and used to indicate the changes in the metals in litter.The results showed that the concentrations of Al,Cd,Cr,Fe,Mn,and Pb in litter increased significantly during the decomposition,while Cu and Zn concentrations decreased dramatically.Significant positive correlations were found between the concentrations of Al,Cr,Fe,and Mn and between Cu and Zn.Moreover,Cu and Zn both negatively correlated with Al and Fe.The remaining dry mass was negatively correlated with Al and Fe concentrations but positively correlated with Cu and Zn concentrations.Generally the accumulation index values of metals other than Al were less than one,indicating that the litter of P.crispus acted as a source of metals to the surrounding water body.Al was the only metal that showed continuous net accumulation in litter.The net accumulation of Fe and Mn in litter during the last 10 days of the experiment may indicate the precipitation of Feand Mn-oxides.It was estimated that 160 g/m~2(dry weight)P.crispus was decomposed in40 days.This was equivalent to releasing the following amounts of metals:0.01 mg Cd,0.03 mg Cr,0.71 mg Cu,0.55 mg Mn,0.02 mg Pb and 13.8 mg Zn into surrounding water,and accumulating 149 mg Al and 11 mg Fe,in a 1 m~2 area.     

Historical trends of heavy metal contamination and their sources in lacustrine sediment from Xijiu Lake, Taihu Lake Catchment, China

Concentrations of Cd, Cr, Cu, Pb, Zn and Hg in Xijiu Lake sediment from the Taihu Lake catchment, China, were analyzed. Their contamination state was investigated based on the geoaccumulation index and enrichment factors. Statistical analysis was used to differentiate the anthropogenic versus natural sources of heavy metals (HMs), and the anthropogenic accumulation fluxes were calculated to quantify anthropogenic contribution to HMs. The results indicated that the lake sediment had been heavily contaminated by Cd, enrichment of Zn and Hg was at a relatively high level, while that of Cu and Pb was in the lower-to-moderate level and Cr was in the low enrichment level. Sources of Cr in the sediment were mainly from natural inputs, while other metals, especially Cd, were predominantly derived from anthropogenic sources. In the past century, anthropogenic accumulation fluxes of Pb, Zn and Hg increased by 0.1-47.3 mg/(cm².yr), 2.4-398.1 mg/(cm².yr), and 3.7-110.3 ng/(m².yr), respectively, accounting for most inputs of HMs entering the sediment. The contamination state of HMs varied with industrial development of the catchment, which demonstrated that contamination started in the early 20th century, reached the maximal level between the mid-1970s and mid-1990s, and decreased a little after the implementation of constraints on high contamination industries, although the contamination of some HMs, such as Cd, Zn and Hg, is still at high levels.     

珠海市郊区大气PM2.5中元素特征及重金属健康风险评价

为探讨珠海市郊区大气环境PM_2.5中主要元素尤其是重金属的污染特征及其健康风险,于2014~2015年选取春、夏、秋、冬季4个典型月采集了PM_2.5样品.利用X射线荧光光谱法分析得到15种元素的含量,进一步利用富集因子和主成分分析方法分析其来源,并采用US EPA环境健康风险评价模型评估痕量重金属的健康风险.结果表明：大气PM_2.5中地壳元素（Al、Si、Ca、Fe、Ti）总质量浓度在春、夏、秋、冬季典型月分别为（708±213）、（645±269）、（1155±503）和（1466±492）ng·m^-3,痕量重金属元素（Ba、Co、Cr、Cu、Mn、Ni、Pb、Sb、V、Zn）总质量浓度在春、夏、秋、冬典型月分别为（271±124）、（163±87.6）、（424±192）和（546±183）ng·m^-3.富集因子分析显示Sb、Zn、Pb、Cu、Ni、Ba、Ca、Co等元素富集显著,其富集因子均值范围为172~2426.主成分分析显示,区域性输送污染源、船舶源、燃煤和电子工业是PM_2.5中重金属的主要来源,其贡献率分别为53.4%、13.0%、7.6%和6.8%.健康风险评价结果表明,Mn元素对儿童存在一定的非致癌风险,Cr、Pb和Co存在一定的致癌风险.     

海州湾潮滩重金属污染的历史记录

近岸海域是区域源汇过程的汇,记载了区域环境演变的重要信息.2010年在海州湾潮滩采集得到4个沉积物柱样,对沉积物柱样进行了重金属元素测定,结合核素210Pb测年结果,研究了海州湾潮滩重金属污染历史及人类活动对其影响.运用Al元素作为粒度的代用指标对重金属进行标准化,并获取了重金属富集系数和人为污染的重金属通量.研究表明,粒度控制效应并不是影响海州湾潮滩地区重金属分布的最主要因素,并且各重金属元素之间具有良好的相关性,说明该区域重金属元素具有来源一致性;海州湾潮滩沉积物中除重金属Cr和Cu表现为弱富集外,其他重金属元素Cd、Cr、Cu、Mn、Pb和Zn均表现为强富集,并且表层沉积物中重金属含量均高于该区域的背景值,这表明近50年以来,海州湾潮滩已明显受到人类污染源的影响,从而造成沉积物中重金属不断富集累积;自20世纪50年代至2000年初海州湾潮滩沉积物中人为污染活动输入的重金属通量呈现出波动增加的趋势,这种变化特征与区域社会、经济发展阶段相吻合;而从2005年以来随着区域产业结构优化调整,环境监管力度加强,潮滩沉积物中人为来源的重金属通量呈现出减少的趋势.     

厦门市大气PM_(2.5)中重金属污染特征及健康风险评价

用ICP-MS对厦门市夏冬两季城区和郊区PM_(2.5)(当量直径≤2.5 μm的颗粒物)及其中10种重金属(V、Cr、Mn、Co、Ni、Zn、As、Cd、Pb和Cu)含量进行测定,分析其污染特征,并对重金属的健康风险进行评价。结果表明,采样期间厦门市PM_(2.5)中重金属含量水平表现为ZnPbCuMnVAsNiCrCdCo,其中Zn、Pb、As、Cd和Cu富集因子远远大于10,受人为影响较严重。健康风险评价结果表明,PM_(2.5)中重金属的非致癌健康风险可以忽略;几乎所有重金属的致癌健康风险都高于最大可接受风险值10~(-6)。     

Size distribution of chemical elements and their source apportionment in ambient coarse, fine, and ultrafine particles in Shanghai urban summer atmosphere

Ambient coarse particles (diameter 1.8-10 μm), fine particles (diameter 0.1-1.8 μm), and ultrafine particles (diameter < 0.1 μm) in the atmosphere of the city of Shanghai were sampled during the summer of 2008 (from Aug 27 to Sep 08). Microscopic characterization of the particles was investigated by scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM/EDX). Mass concentrations of Si, P, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, As, Se, Br, Rb, Sr, and Pb in the size-resolved particles were quantified by using synchrotron radiation X-ray fluorescence (SRXRF). Source apportionment of the chemical elements was analyzed by means of an enrichment factor method. Our results showed that the average mass concentrations of coarse particles, fine particles and ultrafine particles in the summer air were 9.38 ± 2.18, 8.82 ± 3.52, and 2.02 ± 0.41 μg/m³, respectively. The mass percentage of the fine particles accounted for 51.47% in the total mass of PM10, indicating that fine particles are the major component in the Shanghai ambient particles. SEM/EDX results showed that the coarse particles were dominated by minerals, fine particles by soot aggregates and fly ashes, and ultrafine particles by soot particles and unidentified particles. SRXRF results demonstrated that crustal elements were mainly distributed in the coarse particles, while heavy metals were in higher proportions in the fine particles. Source apportionment revealed that Si, K, Ca, Fe, Mn, Rb, and Sr were from crustal sources, and S, Cl, Cu, Zn, As, Se, Br, and Pb from anthropogenic sources. Levels of P, V, Cr, and Ni in particles might be contributed from multi-sources, and need further investigation.     

株洲市大气降尘中元素特征及来源分析

为研究湖南省株洲市大气降尘中多种元素的分布特征以及来源,于2012年1~12月对株洲市12个点的大气降尘样品进行采集并对其中28种元素的含量进行分析.结果表明,株洲市城区各采样点大气降尘年沉降量为23.14~114.67 g·m~(-2),其中工业区和商住混合区年均值分别为89.46 g·m~(-2)和33.20 g·m~(-2),低于其它工业城市;工业区和商住混合区降尘中分别有10种元素(Na、Mg、Al、K、Ca、Ti、Mn、Fe、Zn、Pb)和8种元素(Na、Mg、Al、K、Ca、Ti、Fe、Zn)含量大于1 000 mg·kg~(-1),其中工业区2种重金属元素(Zn、Pb)含量超过10 000 mg·kg~(-1),远高于地壳中的含量.株洲市大气降尘主要来源为金属冶炼、地表扬尘、汽车尾气、建筑粉尘和与Mo、Ba元素相关的工业生产.相关性分析、主因子分析和迁移特征分析表明降尘中Mn、Fe、Co、Cu、Zn、As、Se、Ag、Cd、Sn、Sb、Tl、Pb等13种元素主要来自株洲市工业区废气排放,其中Cu、Zn、As、Ag、Cd、Se和Pb等7种元素污染严重,工业区重金属元素含量是土壤背景值中含量的7.4~4 079.4倍,商住混合区是土壤背景值的3.6~1 413.4倍,背景比值最高的为Cd元素.工业区的污染程度明显高于商住混合区.     

广州市秋季PM2.5中重金属的污染水平与化学形态分析

采用消解法和连续提取法分析了广州市秋季PM_2.5样品中10种重金属元素的总量和化学形态,对广州市PM_2.5中重金属的污染水平和生物有效性进行了评价.结果表明,广州市PM_2.5和重金属污染非常严重,其中PM_2.5日浓度高达0.083 3～0.190 0 mg·m^-3,为1997年美国EPA相应标准的1.3～2.9倍.PM_2.5中Cd、Pb、Zn、Cu和Mo的富集因子K>10,是典型的污染元素;而Ni、Mn、Co和Fe的K值为1～10,除部分来自人为活动外,主要还是自然作用来源.化学形态分析结果显示,超过80％的Al和Fe分布在有机质、氧化物与硫化物结合态和残渣态,而大部分Zn、Pb、Cd 和Cu分布在可溶态、可交换态、碳酸盐态、可氧化态和可还原态.生物有效性系数(K)分析结果说明,PM_2.5中重金属的生物有效性相对强弱顺序为：Cd>Zn>Pb>Cu>Mn>Mo>Co>Ni>Fe>Al.其中Cd、Zn和Pb的K>0.8,为生物可利用性元素;Cu、Mn、Mo、Co和Ni的K值在0.5左右,为潜在生物可利用性元素;Fe和Al的K<0.2,为生物不可利用性元素.     

Trace metals in atmospheric fine particles in one industrial urban city: Spatial variations, sources, and health implications

Trace metals in PM2.5were measured at one industrial site and one urban site during September, 2010 in Ji'nan, eastern China. Individual aerosol particles and PM2.5samples were collected concurrently at both sites. Mass concentrations of eleven trace metals(i.e., Al, Ti, Cr, Mn, Fe, Ni, Cu, Zn, Sr, Ba, and Pb) and one metalloid(i.e., As) were measured by inductively coupled plasma atomic emission spectroscopy(ICP-AES). The result shows that mass concentrations of PM2.5(130 μg/m3) and trace metals(4.03 μg/m3) at the industrial site were 1.3 times and 1.7 times higher than those at the urban site, respectively, indicating that industrial activities nearby the city can emit trace metals into the surrounding atmosphere. Fe concentrations were the highest among all the measured trace metals at both sites, with concentrations of 1.04 μg/m3at the urban site and 2.41 μg/m3at the industrial site, respectively. In addition, Pb showed the highest enrichment factors at both sites, suggesting the emissions from anthropogenic activities existed around the city. Correlation coefcient analysis and principal component analysis revealed that Cu, Fe, Mn, Pb, and Zn were originated from vehicular trafc and industrial emissions at both sites; As, Cr, and part of Pb from coal-fired power plant; Ba and Ti from natural soil. Based on the transmission electron microscopy analysis, we found that most of the trace metals were internally mixed with secondary sulfate/organic particles. These internally mixed trace metals in the urban air may have diferent toxic abilities compared with externally mixed trace metals.     

隧道大气细颗粒物及其元素的粒径分布特征

对比研究了隧道和大气环境中不同粒径细颗粒物 (切割粒径分别为0.03,0.06,0.108,0.17,0.26,0.40,0.65,1.0,1.6和2.5 μm) 中S,K,Ca,Ti,Mn,Fe,Zn,Pb,Al,Si,Cu和V等12种痕量元素的浓度. 结果表明:隧道中不同粒径细颗粒物的数浓度和质量浓度在上下班高峰时段出现明显峰值,且隧道细颗粒物在0.108 μm粒径处的数浓度和在2.5 μm粒径处的质量浓度分别是大气环境对照值的15.2和40.0倍;在隧道传输过程中质量浓度增加的痕量元素有 Si,Ca,Fe,Al,Ti,Zn,Mn,Cu和V,减小的有S,Pb,Zn和K;地壳元素(Si,Ca,Fe,Al和Ti)的质量浓度总和占隧道细颗粒物中痕量元素质量浓度总和的87%,表明土壤扬尘仍是隧道大气细颗粒物的主要来源.      

南黄海南部海域表层沉积物重金属来源解析及风险评价

基于2012年夏季对南黄海南部海域的调查资料,分析了表层沉积物中7种重金属元素的含量分布特征;采用多元统计分析,揭示了研究区表层沉积物重金属污染的主要来源及各元素之间的相关性;应用地质累积指数法和Hakanson潜在生态风险指数法对重金属元素进行了污染及风险分析.结果表明:Cd、Pb的含量均符合国标规定的一类沉积物标准,Zn、Cu、Cr在绝大部分站位也都低于国标规定的一类沉积物的最高标准,仅在个别站位处达到二类或三类沉积物标准;除Cr、Cd、Mn外,其余各重金属与Al2O3、平均粒径之间有显著的相关性,表明它们均以自然来源为主,并受到沉积物粒度的控制,遵循"元素的粒度控制律";Cr、Cd、Mn与Al2O3的相关系数较小,表明其可能受到人为污染源的影响.通过主成分分析和聚类分析可将7种重金属元素辨识为2个主成分,PC1(Zn、Cu、Pb、Fe、Mn)为自然源因子,PC2(Cr、Cd)为工农业源因子;其中,Cr、Cd在PC1和PC2上均具有一定的正载荷,受自然地质背景和人类活动的共同控制.地质累积指数法评价结果表明,Zn、Cu、Cd、Pb整体均处于清洁级别,而Cr则处于轻微污染水平,污染程度排序依次为CrPbCdZnCu;潜在生态风险评价结果表明,各元素潜在生态危害等级排序依次为CdPbCuCrZn,Cr、Zn、Cu和Pb均为低生态危害等级,Cd以低中等生态危害等级为主,局部出现较重生态危害等级,综合潜在生态风险评价为低度.     

Size distribution, characteristics and sources of heavy metals in haze episod in Beijing

Size segragated samples were collected during high polluted winter haze days in 2006 in Beijing, China. Twenty nine elements and 9 water soluble ions were determined. Heavy metals of Zn, Pb, Mn, Cu, As, Cr, Ni, V and Cd were deeply studied considering their toxic effect on human being. Among these heavy metals, the levels of Mn, As and Cd exceeded the reference values of National Ambient Air Quality Standard （GB3095-2012） and guidelines of World Health Organization. By estimation, high percentage of atmospheric heavy metals in PM2.5 indicates it is an effective way to control atmospheric heavy metals by PM2.5 controlling. Pb, Cd, and Zn show mostly in accumulation mode, V, Mn and Cu exist mostly in both coarse and accumulation modes, and Ni and Cr exist in all of the three modes. Considering the health effect, the breakthrough rates of atmospheric heavy metals into pulmonary alveoli are： Pb （62.1%） 〉 As （58.1%） 〉 Cd （57.9%） 〉 Zn （57.7%） 〉 Cu （55.8%） 〉 Ni （53.5%） 〉 Cr （52.2%） 〉 Mn （49.2%） 〉 V （43.5%）. Positive matrix factorization method was applied for source apportionment of studied heavy metals combined with some marker elements and ions such as K, As, SO42- etc., and four factors （dust, vehicle, aged and transportation, unknown） are identified and the size distribution contribution of them to atmospheric heavy metals are discussed.     

北京冬季PM2.5中金属元素浓度特征和来源分析

为了解北京冬季细颗粒物中金属元素的浓度水平及其来源,于2014年12月至2015年1月使用中流量PM_(2.5)采样器在北京城区开展了为期30 d的连续采样,采用滤膜称重法检测PM_(2.5)浓度,电感耦合等离子体质谱法(ICP-MS)分析PM_(2.5)中16种元素总量,并采用富集因子法和因子分析法分析元素污染特征及其来源.结果表明,观测期间PM_(2.5)中主要金属元素为K、Ca、Fe、Al和Mg,占16种元素总量的90.7%.与白天相比,地壳元素如Mg和Al等在夜间的浓度下降30%以上,而人为源金属元素如Cu和Pb等的浓度则上升40%以上.从优良天到重污染天气,上述16种金属元素的总浓度上升1倍,但其在PM_(2.5)中的比例却逐渐降低,说明金属元素的富集不是PM_(2.5)上升的主要原因.随着污染程度的加剧,Cu、Zn、As、Se、Ag和Cd等主要来自人为源的金属元素浓度上升较快,重度污染天与优良天的浓度比值范围为2.9~5.3;而Al、Mg、Ca、Mn和Fe等地壳元素浓度上升则较缓,重度污染天与优良天的浓度比值范围为1.2~1.8.北京冬季PM_(2.5)中金属元素主要来源于燃煤和生物质燃烧、交通和工业排放以及地面扬尘,贡献率分别为34.2%、25.5%和17.1%.     

连环湖牙门气泡沉积物重金属演化和污染研究

2010年8月在牙门气泡的湖心位置采集了柱状沉积岩心.采用HNO3-HClO4-HF联合消解并运用ICP-MS测试了柱状沉积岩心中金属元素Cr、Cu、Mn、Ni、Fe、Pb、Zn、Cd、Al、Ba、Ca、K、Li、Mg、Na和Sr的含量,结合沉积岩心年代测定,研究了该湖区沉积物重金属元素演化特征及污染历史.应用富集系数法探讨了湖泊重金属的污染特征.结果表明,1950年以前各元素含量变化趋势平稳,1950～1990年间波动较大,1990年以后金属元素Mn、Zn、Cd、Pb、Fe、Ni、Cr、Cu、Ca、Li和Sr浓度明显增加.牙门气泡重金属元素Mn、Zn、Cd、Pb存在轻微污染,而Ni、Cr和Cu无污染.     

有色冶炼园区道路扬尘中重金属污染特征及健康风险评价

为研究有色冶炼工业园区周边道路扬尘中重金属污染特征及其健康风险,在云南省蒙自地区采集了城市道路、有色冶炼工业园区道路以及隧道尘样品,通过再悬浮设备将尘样悬浮至Teflon滤膜上获得PM_(2.5)和PM_(10)样品,并利用ICP-MS分析了Cr、Mn、Ni、Cu、Zn、As、Cd和Pb这8种重金属的含量.结果表明,在PM_(2.5)中重金属的平均含量高于PM_(10).Pb、Cd、As和Zn在3种道路扬尘中平均含量最高,且在不同道路扬尘中平均含量差异表现为:隧道工业园区道路城市道路.隧道扬尘中Pb和As的平均含量高于其它重金属,在PM_(2.5)中达到92 338.3 mg·kg~(-1)和12 457.7 mg·kg~(-1);工业园区道路扬尘中Pb和Zn的平均含量最高,在PM_(2.5)中分别是4 381.7 mg·kg~(-1)和4 685.0 mg·kg~(-1);城市道路平均含量最高的重金属是Zn和Pb,在PM_(2.5)中为1 952.6 mg·kg~(-1)和1 944.8 mg·kg~(-1), 3种道路扬尘中Cu、Zn、As、Cd和Pb平均含量均高于云南省土壤背景值.富集因子分析和主成分分析结果显示:Cu、Zn、As、Cd和Pb在3种道路上均有明显富集,受到有色冶炼工业和交通源的显著影响;而Cr、Mn和Ni在3种道路上富集不明显,未受到明显的人为源影响.健康风险评价结果表明,摄食是主要的暴露途径;儿童的非致癌风险高于成人.在PM_(2.5)道路扬尘中所含有的As、Cd和Pb都会对成人和儿童造成非致癌风险,在PM_(10)工业园区道路和隧道扬尘中的As、Cd和Pb对人体有非致癌风险,城市道路中的As仅对儿童有非致癌风险.此外,隧道中的As具有致癌风险.     

2017—2018年秋冬季唐山市PM2.5中元素组成特征及来源解析

为研究唐山市大气PM_2.5中元素组成特征及其来源,于2017年10月19日—2018年1月31日（秋冬季）在唐山市的超级站（典型城市站点）、开平站（工业站点）和古冶站（工业站点）开展了PM_2.5的手工连续采样,定量分析测定了PM_2.5中23种无机元素.结果表明:Si、Al、Ca和Na等地壳元素的质量浓度均在10月最高,在1月最低.10月,ρ（Cr）在开平站最高（0.020 0 μg/m3）,随后逐月略微降低,其主要受钢铁冶炼工业的减产和限产影响.多数重金属元素质量浓度在11月或12月最高,包括Zn、Pb、Mn、Cu、Ni、Se、V、Cd和Co,其可能受燃煤取暖影响.Cd、Zn、Pb和Cu四种元素的富集因子值分别为2 677、616、422和77,均达到极强富集,且均受人为排放源影响最大.基于因子分析法得出,唐山市大气PM_2.5中元素的主要来源有燃煤源、钢铁工业源与扬尘源的混合源、交通源以及土壤扬尘源,其方差贡献率分别为56.3%、21.6%、7.1%、5.4%.研究显示,秋冬季唐山市大气颗粒物PM_2.5中元素最主要的污染来源为工业源、燃煤源和扬尘源.      

苏州古城区域河道底泥的重金属污染分布及生态风险评价

本文分析了苏州古城区域20个代表性断面中8种重金属（Cd、Cu、Cr、As、Mn、Ni、Pb和Zn）的含量,评价了重金属的污染程度和潜在生态风险并甄别了污染来源.结果表明,苏州古城区域河道底泥中Cd、Cu、Cr、As、Mn、Ni、Pb和Zn的平均含量分别为1.1、142.6、90.2、17.2、800.1、63.3、199.1和384.2 mg·kg^-1,超过江苏省土壤背景值的采样点比例分别为100%、100%、65%、95%、70%、100%、95%和100%.利用地累积指数评价发现,8种重金属元素污染程度依次为Pb > Cd > Cu > Zn > Cr > Ni > As > Mn,总体上Pb处于强度污染水平,Cd、Cu、Zn和Cr处于中强度污染水平,Ni和As处于轻度污染水平,Mn处于无污染水平.潜在生态风险指数评价显示,8种重元素的潜在生态风险依次为Cd > Pb > Cu > As > Ni > Zn > Cr > Mn,总体上Cd、Pb和Cu处于中风险水平,其余5种重金属处于低风险水平.古城区域内北部河道和南部河道底泥重金属的平均含量、地累积指数值和潜在生态风险指数值均大于干将河和环城河,水环境重金属治理应重点关注古城区域内部.相关性分析和主成分分析表明,Cd、Cu、Cr、As、Ni、Pb和Zn元素可能源于化肥、路面老化、轮胎磨损和尾气排放等人为因素,Mn则主要源于自然因素.     

Health risks associated with heavy metals in the drinking water of Swat, northern Pakistan

The concentrations of heavy metals such as Cd, Cr, Cu, Mn, Ni, Pb and Zn were investigated in drinking water sources （surface and groundwater） collected from Swat valley, Khyber Pakhtunkhwa, Pakistan. The potential health risks of heavy metals to the local population and their possible source apportionment were also studied. Heavy metal concentrations were analysed using atomic absorption spectrometer and compared with permissible limits set by Pakistan Environmental Protection Agency and World Health Organization. The concentrations of Cd, Cr, Ni and Pb were higher than their respective permissible limits, while Cu, Mn and Zn concentrations were observed within their respective limits. Health risk indicators such as chronic daily intake （CDI） and health risk index （HRI） were calculated for adults and children separately. CDIs and HRIs of heavy metals were found in the order of Cr 〉 Mn 〉 Ni 〉 Zn 〉 Cd 〉 Cu 〉 Pb and Cd 〉 Ni 〉 Mn 〉 Cr 〉 Cu 〉 Pb 〉 Zn, respectively. HRIs of selected heavy metals in the drinking water were less than 1, indicating no health risk to the local people. Multivariate and univariate statistical analyses showed that geologic and anthropogenic activities were the possible sources of water contamination with heavy metals in the study area.