The spatial distribution,contamination, and ecological risk assessment of heavy metals of farmland soils in Karashahar–Baghrash oasis,northwest China

The issue of heavy metal pollution is of high concern due to its potential health risks and detrimental effects on human beings, animals, and plants. In this study, farmland soil samples from 79 sampling sites were collected in Karashahar–Baghrash oasis, northwest China, and the contents of eight heavy metal elements (As, Cd, Cr, Cu, Mn, Ni, Pb, and Zn) were determined by standard methods. The spatial distribution, pollution, and ecological risks of heavy metals were analyzed based on Geographical Information System (GIS) technology, contamination factor (CF), pollution load index (PLI), and potential ecological risk index (RI). Results indicated that: (1) The average contents of Cd, Cr, Ni, Pb, and Zn exceeded the background values of irrigation soils of Xinjiang by 54.0, 1.34, 1.39, 3.44, and 5.01 times, respectively. The average contents of Cd exceeded the national standard of China by 10.80 times; (2) The pollution order of CF was ranked as Cd > Zn > Pb > Ni > Cr > Cu > As > Mn, and the ecological risk order of E_rⁱ was ranked as Cd > Ni > As > Cu > Ni > Pb > Cr > Zn. The average PLI of the study area showed heavy pollution level, and the average RI of the study area fell into considerable risk; (3) The moderately polluted areas with moderate potential ecological risks distributed in the northern parts, whereas heavily polluted areas with considerable potential ecological risks distributed in the southern parts of the study area; (4) Cr, Cu, and Mn of farmland soils were mainly originated from natural factors. Cd, Ni, and Pb were mainly originated from anthropogenic factors. As and Zn may be associated with both natural and anthropogenic factors. Cd contributed most to the PLI and RI of the farmland soils in the study area.     

深圳市不同功能区土壤表层重金属污染及其综合生态风险评价

在综合考虑深圳市城市功能区分异特征的基础上,进行全市表层土壤系统采样,全面监测土壤表层8种重金属元素污染状况,分析不同重金属元素含量的统计学特征,探讨不同城市功能区对土壤表层重金属污染的影响,采用内梅罗指数和潜在生态危害指数评估不同重金属元素和不同城市功能区的生态风险水平,分别进行基于两种方法的全市重金属污染生态风险分区。结果表明: 1)深圳市土壤表层的Mn、Ni、Cr和Pb 4种元素受人为活动的影响程度较低,Cd、Zn、Cu和As 4类元素受人为活动影响较大。地表环境约束因素背景下的高强度城市化和工业化过程,是各种重金属污染区域分异和功能区分异的决定性因素。2)深圳市土壤重金属污染风险较高的重金属元素为Cd、Zn、Cu和Pb,特别是Pb污染问题尤为突出,必须加强管控工作。深圳市总体土壤表层重金属污染风险水平高于国内相关城市,需要引起足够重视。3)内梅罗指数法和潜在生态危害指数法的侧重点不同,在单一重金属元素风险判断、不同城市功能区生态风险的总体评价,以及市域土壤重金属污染生态风险分级评价方面结果差异较大,组合使用效果更好。     

Assessment of Heavy Metal Pollution in Urban Agricultural Soils of Jilin City,China

Due to rapid industrialization and urbanization during the last two decades, contamination of urban agricultural soils by heavy metals is on an increase all over China. In this study, fifty soil samples were collected from urban vegetable fields in a chemical industrial area and non chemical industrial area in Jilin City to investigate the heavy metal pollution level. The mean Pb, Cr, Cu, Ni, Zn, and Cd contents (30.84, 65.65, 26.41, 23.07, 135.14, and 0.1434 mg kg^?1 dry weight, respectively) in the urban vegetable soils were higher than their corresponding natural background values. The principal component analysis (PCA) was performed to identify the possible sources of metal contamination in the study area. The results indicated that Cu and Zn were mainly from industrial activities, while Pb and Cd were derived from traffic activities and agricultural activities, and Cr and Ni tended to be from parent material. The distribution of comprehensive pollution index values showed that Pb, Cr, Cu, Ni, Zn, and Cd concentrations in most of the agricultural fields did not exceed the baseline values affecting the safety of agricultural production and human health according to the soil environmental quality standard of China, indicating an insignificant contamination of these metals in Jilin City.     

武汉市蔬菜重金属污染现状的调查与评价

通过对武汉市6种蔬菜的供食部位及所对应的土壤中重金属Hg(汞)、Cu(铜)、Pb(铅)、Cd(镉)、Cr(铬)、Zn(锌)、As(砷)含量及分布特征进行了检测,结果表明:Pb、Cr是武汉市蔬菜中主要的污染元素;Hg、Cd只在个别叶菜类上超标;Zn、Cu、As无超标样。在所时应的土样中,普遍存在污染的是Cd,其它6种重金属元素均未超标。     

新疆焉耆盆地辣椒地土壤重金属污染及生态风险预警

从新疆加工辣椒主产地(焉耆盆地)采集105个辣椒地典型土壤样品,测定其中As、Cd、Cr、Cu、Mn、Ni、Pb和Zn等8种重金属元素的含量。采用污染负荷指数(Pollution load index,PLI)、潜在生态风险指数(Potential ecological risk index,RI)和生态风险预警指数(Ecological risk warning index,I_(ER))对辣椒地土壤重金属污染及生态风险进行评价。结果表明:(1)焉耆盆地辣椒地土壤Cd、Cr、Ni、Pb和Zn含量的平均值分别超出新疆灌耕土背景值的1.65、1.40、1.32、3.21、6.42倍。辣椒地土壤Pb和Zn呈现重度污染,Cd、Cr和Ni轻度污染,As、Mn和Cu无污染。(2)土壤PLI平均值为1.40,呈现轻度污染。各重金属元素单项生态风险指数从大到小依次为:Cd、Ni、As、Cu、Pb、Cr、Zn。土壤RI平均值为18.40,属于轻微生态风险态势,IER平均值为-4.78,属于无警态势;博湖县辣椒地污染水平、潜在生态风险程度与生态风险预警等级最高,焉耆县污染水平、潜在生态风险程度与生态风险预警等级最低。(3)辣椒地土壤As、Cd、Pb与Zn主要受到人类活动的影响,Cr、Cu、Mn和Ni主要受到土壤地球化学作用的控制。Cd是焉耆盆地辣椒地生态风险等级最高的重金属元素,研究区农业生产过程中要防范Cd的污染风险。     

贵州兴仁煤矿区农田土壤重金属化学形态及风险评估

为了解煤矿区周边农田土壤重金属污染状况,采集了贵州省兴仁县某典型煤矿区农田土壤样品64份,测定了土样中重金属(As、Cr、Pb、Zn、Cd、Hg、Cu、Ni)总量及各形态含量,采用单因子指数法、潜在生态风险指数法(Hkanson法)和风险评估编码法(RAC)对研究区主要土壤利用类型(水稻土、薏米地、植烟土和菜园土)中重金属进行潜在生态风险评估和环境风险评价.结果表明： 不同利用类型土壤中重金属含量除Zn外,其他元素均明显超过贵州省背景值.单因子指数法评价结果表明,As、Pb、Hg和Cu污染较为严重,均属重度污染.形态分析表明,土壤中重金属形态构成差异明显,酸可提取态As、酸可提取态Cd所占比例较高;Cr、Zn、Cu、Ni主要以残渣态为主;Pb主要以可还原态和残渣态为主;而Hg的酸可提取态、可还原态、可氧化态均占有相当比例,三者之和大于55%.重金属可利用度大小顺序为:As(63.6%)>Hg(57.3%)>Cd(56.4%)>Pb(52.5%)>Cu(45.7%)>Zn(32.8%)>Ni(26.2%)>Cr(13.2%).潜在生态风险指数表明,各类型土壤潜在生态风险(RI)〖JP2〗为:菜园土(505.19)>薏米地(486.06)>植烟土(475.33)>水稻土(446.86),均处于较高风险.风险评估编码法结果显示,As在水稻土、薏米地及植烟土中均处于高风险,在菜园土中处于中等风险;Cd、Hg均处于中等风险,Cr、Pb、Zn、Cu和Ni均处于低风险.因此,对该区域农田土壤进行管控时应重点考虑As、Cd和Hg污染.     

Heavy metals in wetland soils along a wetland-forming chronosequence in the Yellow River Delta of China: Levels,sources and toxic risks

Surface soil (0–20 cm) samples were collected from four chronological sequences of wetlands (i.e., >50-yr-old wetlands, 40-yr-old wetlands, 30-yr-old wetlands and 10-yr-old wetlands) in the Yellow River Delta of China in May and June of 2007. Total contents of Al, As, Cd, Cr, Cu, Ni, Pb and Zn were determined using inductively coupled plasma atomic absorption spectrometry (ICP-AAS) to investigate the levels, sources and toxic risks of heavy metals in these wetlands. Our results showed an increasing trend for Pb, Cu and Zn along the wetland-forming chronosequence although their pollution levels were low. Both As and Cd exhibited significant enrichment due to their high enrichment factor (EF) values (EF > 5), especially in older wetlands (i.e., >50-yr-old and 40-yr-old wetlands), whereas other heavy metals were minimally or moderately enriched in this region. The results of principal component analysis showed that 83.09% of total variance based on eigenvalues (eigenvalue > 1) could be explained by three principal components (PCs) in four wetlands. The source of Al, Cu, Pb and Zn was different from Cd, Cr and Ni. According to the sediment quality guidelines (SQGs) of China, soil samples in the younger wetlands, especially the 10-yr-old wetlands, were moderately polluted by As, Cd and Ni. According to the SQGs of US EPA, all soil samples were heavily polluted by As and moderately polluted by Ni and soil samples in the older wetlands were moderately polluted by Cr. However, with the exception of As and Ni, the contents of other heavy metals in the four wetlands did not exceed the probable effect level (PEL) values. As, Cd and Ni were identified as heavy metals of primary concerns in four wetlands, Cr were of moderate concern in older wetlands, and Pb, Cu and Zn should be paid more attention in younger wetland (i.e., 10-yr-old and 30-yr-old wetlands). A new and sensitive toxic risk index (TRI) is developed for the accurate assessment of toxic risk for heavy metals in wetland soils compared with the sum of the toxic units (∑TUs), and As, Cr, Ni and Cd showed higher contributions to TRI.     

广州市花都城区绿地土壤肥力与重金属污染分析

在对广州市花都城区绿地土壤取样调查的基础上,采用全国第二次土壤普查养分分级标准和内梅罗污染指数法等对其土壤肥力和重金属污染情况进行分析评价,揭示花都城区绿地土壤存在的问题。结果表明,花都城区绿地土壤容重变幅在1.25～1.75 g·cm–3之间,孔隙度变幅在30.81%～47.42%之间,pH在6.16～7.68之间,有机质含量在四级及以下标准,严重缺乏氮素和磷素。不同绿地类型中,厂区路旁绿地土壤重金属污染最严重,其次为主干道两侧绿地;研究区As污染最严重,Pb次之,未受Zn污染,存在不同程度的Cu、Cd、Cr、Ni、Hg污染。相关性分析表明,土壤pH与全钾、碱解氮含量极显著相关,有机质与全氮极显著相关,全氮、全磷分别与碱解氮、有效磷显著正相关,全钾与碱解氮显著负相关;重金属元素中,Cu与Zn、Cr、Ni极显著相关,Zn与Cu、Pb、Cd、Cr、Ni极显著相关,Pb与Zn、Cd极显著相关,Cr与Cu、Zn、Ni极显著相关,As和Hg与其他重金属元素均无显著相关性。     

Distribution and risk assessment of heavy metals in river surface sediments of middle reach of Xijiang River basin,China

Xijiang River is the main surface water source in Guangxi province, South China. This study was carried out to investigate the distribution and potential ecological risks of seven heavy metals (Cu, Pb, Zn, As, Cd, Ni, and Cr) in surface sediments in Xijiang River basin. The results illustrated that the average concentrations of Zn, Pb, Cd, Cu, As, Ni, and Cr were 483.9, 207.5, 13.35, 23.50, 312.1, 28.75, and 50.62 mg/kg, respectively. Among them, Zn, Pb, Cd, and As were the major heave metals with concentration exceeding Class 3 threshold value of Chinese national standard. The result also showed samples with high ecological risk were mainly located in the upstream of Xijiang River basin as Diaojiang River, Hongshui River, Jincheng River, and Dahuan River. Based on the pollution risk assessment, the area manifested composite pollution of heavy metals in the sediments, signifying As, Pb, and Cd as the dominant heavy metals, and there were high ecological risk in sediments for these metals. According to correlation matrix and factor analysis (FA), the seven heavy metals were divided into three types/classes, Cd, as and Zn attributed by anthropogenic sources, natural sources corresponds for Ni and Cr while both natural and anthropogenic sources were attributed to Cu.     

浙江油茶产地土壤和果实金属元素含量特征

为探讨油茶(Camellia oleifera)产地土壤和油茶果实中金属元素分布和富集特征,在油茶果实成熟期,对浙江5个油茶产地土壤及油茶果实中金属元素进行污染分析和富集能力评价。结果表明,浙江油茶产地土壤中Pb、Cr、Cd、As、Hg、Ni、Cu和Zn含量低于农用地土壤污染风险筛选值,综合污染等级为安全。个别产区常山县土壤中As、Ni、Cu和江山县土壤中Pb、Cr、Fe含量显著高于其他产地;常山和建德土壤中Cd单因子污染指数分别为0.93和0.81,处于污染警戒线。Cr、Ni、Cu、Zn主要分布在油茶籽中,Hg主要分布在壳中,Pb、Cd、As、Fe和Mn主要分布在青皮中。油茶籽中Cu、Fe、Mn的富集系数大于0.4,吸收能力强,Ni、Zn的富集系数小于0.4,具有一定吸收能力,Pb、Cr、Cd、As和Hg的富集系数小于0.1,吸收能力低;壳中Cu、Mn的富集系数大于0.4,吸收能力强,Fe的富集系数小于0.4,具有一定吸收能力,Pb、Cr、Cd、As、Hg、Ni、Zn的富集系数小于0.1,吸收能力低;青皮中Cu、Fe、Mn的富集系数大于0.4,吸收能力强,Pb、Cr、Cd、As、Hg、Ni、Zn的富集系数小于0.1,吸收能力低。浙江油茶主产区土壤质量安全,适合油茶种植。油茶果实对Cu、Fe、Mn有一定富集能力,对Pb、Cr、Cd、As和Hg无富集能力。     

A human health risk assessment of heavy metals in agricultural soils of Yanqi Basin,Silk Road Economic Belt,China

A total of 195 farmland soil samples were collected in Yanqi Basin, Xinjiang, northwest China, and the concentrations of As, Cd, Cr, Cu, Ni, Pb, and Zn were analyzed for their concentrations and pollution levels using the Nemerow comprehensive index. The health risk assessment model introduced by USEPA was utilized to evaluate the human health risks of heavy metals. Results indicated that the average concentrations of these seven metals were lower than the allowed soil environmental quality standards of China, while the average concentrations of Cd, Cr, Ni, Pb and Zn exceeded the background values of irrigation soils in Xinjiang. The average contamination factor (CF) for Pb indicated the heavy pollution, whereas the CF for Cd, Zn, Ni, Cu and Cr indicated the moderate pollution. The average PLI of heavy metals indicated the low pollution. The non-carcinogenic hazard index were below the threshold values, and the total carcinogenic risks due to As and Cr were within the acceptable range for both children and adults. As and Pb were the main non-carcinogenic factors, while As was the main carcinogenic factor in the study area. Special attentions should be paid to these priority control metals in order to target the lowest threats to human health.     

Analysis of Spatial Variations and Sources of Heavy Metals in Farmland Soils of Beijing Suburbs

To understand the effect of intense human activities in suburbs on environmental quality, we obtained 758 measurements of the heavy metals in certain farmland soils of the Beijing suburbs. Multivariate statistical analysis and geostatistical analysis were used to conduct a basic analysis of the heavy metal concentrations, the distribution characteristics and the sources of pollution of the farmland soils in these suburbs. The results showed the presence of eight heavy metals in the agricultural soils at levels exceeding the background values for As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn. In particular, all the measured Cr concentrations exceeded the background value, while As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn were present at 1.13, 1.68, 1.95, 1.43, 1.63, 0.79, 0.92 and 1.36 times their background values, respectively. The results of correlation, factor and spatial structure analyses showed that Cd, Cu, Pb and Zn were strongly homologous, whereas Cr and Hg showed a degree of heterogeneity. The analysis further indicated that in addition to natural factors, Cd, Cu, Pb and Zn in the soil were mainly associated with distribution from road traffic and land use status. Different agricultural production measures in the various areas were also important factors that affected the spatial distribution of the soil Cr concentration. The major sources of Hg pollution were landfills for industrial waste and urban domestic garbage, while the spatial distribution of As was more likely to be a result of composite pollution. The regional distribution of the heavy metals indicated that except for Cr and Hg, the high heavy metal levels occurred in districts and counties with higher organic matter concentrations, such as the northwestern and southeastern suburbs of Beijing. There was no significant Ni pollution in the agricultural soils of the Beijing suburbs.     

Geochemical baseline establishment and ecological risk evaluation of heavy metals in greenhouse soils from Dongtai,China

Currently, heavy metal (HM) contamination in greenhouse soils is a significant concern due to the rapid expansion of greenhouse agriculture. However, it is difficult to accurately assess HM pollution in greenhouse soils in China due to the lack of local geochemical baseline concentrations (GBCs) or corresponding background values. In the present study, the GBCs of HMs in Dongtai, a representative greenhouse area of China, were established from subsoils using cumulative frequency distribution (CFD) curves. The pollution levels of HMs and potential ecological risks were investigated using different quantitative indices, such as geo-accumulation index (I_geo), pollution index (PI), pollution load index (PLI) and ecological risk index (RI), based on these regional GBCs. The total concentrations of six metals (Cd, Cr, Cu, Ni, Pb and Zn) in surface soils were determined and shown to be lower than the concentrations reported in other greenhouse regions of China. The GBCs of Cd, Cr, Cu, Ni, Pb and Zn were 0.059–0.092, 39.20–54.50, 12.52–15.57, 20.63–23.26, 13.43–16.62 and 43.02–52.65 mg kg⁻¹, respectively. Based on this baseline criterion, Cd, Pb and Zn accumulated in the surface soils because they were present at concentrations higher than their baseline values. The soils were moderately polluted by Cd according to the I_geo values, and the PI results indicated that moderate Cd contamination was present in this area. The large variation of I_geo value of Cd revealed that Cd in this area was likely influenced by agricultural activities. The PLI showed that most of the study area was moderately polluted. However, an analysis of the RI showed that the investigated HMs had low ecological risks. Correlation analysis and principle component analysis suggested that the Cd, Pb and Zn in the greenhouse soils mainly originated from anthropogenic sources (agricultural activities, atmospheric deposition etc.), while Cr, Cu, and Ni originated from natural sources. The findings of this study illustrated the necessity of GBC establishment at the local scale to facilitate more accurate HM evaluation of greenhouse soils. It is advisable to pay more attention to Cd, which could cause environmental problems in the greenhouse system.     

华南地区典型燃煤电厂周边土壤重金属分布、风险评估及来源分析

为了解华南地区典型燃煤电厂周边表层土壤重金属空间分布特征,对韶关市燃煤电厂周边20处农田表层土壤中7种重金属(镍(Ni)、铜(Cu)、锌(Zn)、镉(Cd)、铅(Pb)、铬(Cr)及砷(As))的总量进行检测,并分析了其相应的空间分布规律,同时评估了周边土壤重金属的生态风险并分析其来源。结果表明:该燃煤电厂周边土壤中重金属Ni、Cu、Zn、Cd、Pb、Cr及As的平均含量分别是17.79、19.59、159.08、3.14、111.01、96.61 mg/kg和21.48 mg/kg,Cd、Pb污染情况突出,重金属Zn、Cd、Pb、Cr的分布与盛行风向密切相关。综合污染指数法表明,Cd、Pb及Zn处于重污染状态;潜在生态风险指数法表明,Cd处于严重潜在生态风险状态;地累积指数法表明,Ni、Cu整体处于无污染状态,Cd整体处于高污染状态。多种统计方法表明,Zn、Cd、Pb及Cr受燃煤电厂影响明显,Cu、As的来源不仅受燃煤电厂等工业的影响,还与该地区农业灌溉用水密切相关,Ni的分布最为均匀,受自然因素影响明显。     

Impact of Land-Use Patterns on Chemical Properties of Trace Elements in Soils of Rural,Semi-Urban,and Urban Zones of the Niger Delta,Nigeria

The study of the concentrations of Cr, Zn, Cd, Pb, Ni, and Cu in soils under different land uses in rural, semi-urban, and urban zones in the Niger Delta was carried out with a view to providing information on the effects of the different land uses on the concentrations of trace elements in soils. Our results indicate significant variability in concentrations of these metals in soils under different land uses in rural, semi-urban, and urban zones. The maximum concentrations of metals in the examined soil samples were 707.5 mg.kg^?1, 161.0 mg.kg^?1, 2.6 mg.kg^?1, 59.6 mg.kg^?1, 1061.3 mg.kg^?1, and 189.2 mg.kg^?1 for Cr, Zn, Cd, Pb, Ni, and Cu, respectively. In the rural zone, the cassava processing mill is a potent source of Ni, Cr, Cu, and Zn while agricultural activities are a source of Cd, and automobile emissions and the use of lead oxide batteries constitute the major sources of Pb. In the urban zone, soils around the wood processing mill showed elevated concentrations of Cu, Cr, Zn, and Ni, while soils around automobile mechanic works and motor parks showed elevated levels of Pb. Elevated Cd concentrations were observed in soils under the following land uses: urban motor park, playground, welding and fabrication sheds, and metallic scrap dump. The contamination/pollution index of metals in the soil follows the order: Ni > Cd > Cr > Zn > Cu > Pb. The multiple pollution index of metals at different sites were greater than 1, indicating that these soils fit into “slight pollution” to “excessive pollution” ranges with significant contributions from Cr, Zn, Cd, Ni, and Cu.     

Heavy metal contamination in vegetables grown around peri-urban and urban-industrial clusters in Ghaziabad,India

Heavy metal contamination of agricultural soils resulting from rapid industrialization and urbanization is of great concern because of potential health risk due to dietary intake of contaminated vegetables. The present study aims to evaluate the status of heavy metals contamination of agricultural soils and food crops around an urban-industrial region in India. Transfer factor values of Cu, Cr, Pb, Cd, Zn, and Ni from soil to vegetable was estimated. The mean heavy metal concentrations (mg/kg) in agricultural soils (Cu: 17.8, Cr: 27.3, Pb: 29.8, Cd: 0.43, Zn: 87, Mn: 306.6, Fe: 16984, and Ni: 53.8) were within allowable concentrations for Indian agricultural soil. The concentrations of Pb, Cd, Zn, and Ni in crops/vegetables exceeded the World Health Organization/Food and Agriculture Organization safe limits. Relative orders of transfer of metals from soil to edible parts of the crops/vegetables were Cd > Pb > Ni > Zn > Cu > Cr. The enrichment factors of heavy metals in soil indicated minor to moderately severe enrichment for Pb, Cd, and Ni; minor to moderate enrichment for Zn; no enrichment to minor enrichment for Mn; and no enrichment to moderate enrichment for Cu at different sites. Ecological risk index of soil showed considerable contamination in one of the wastewater irrigated sites.     

Heavy metals contamination and human health risk assessment in soils of an industrial area,Bandar Abbas – South Central Iran

The purpose of this study was to determine the contamination level, distribution, health risk and potential sources of Cr, Cd, Pb, Zn, Cu, Ni and As in 66 topsoil samples from industrial areas in Bandar Abbas County. The geoaccumulation index, pollution index and pollution load index were calculated to assess the pollution level in the industrial soils. The hazard index and carcinogenic risk were used to assess human health risk of heavy metals. Results showed that the contamination levels of heavy metals were in the descending order of Cu> Cd> Pb> Zn> As> Ni> Cr. Moreover, based on principal component analysis, Cd, Zn, Cu, and Pb originated mainly from anthropogenic sources, including power plants, oil and gas refinery, steel and zinc production factories and municipal waste landfills. For non-carcinogenic effects, hazard index of studied metals decreased in the order of Cr> As> Cd> Pb> Ni > Cu> Zn. Arsenic, chromium and cadmium were regarded as the priority pollutants. Carcinogenic risks due to Cd and As in suburban soils were within tolerable risk to human health; however, children faced more health risk in their daily life than adults via their unconscious ingestion and dermal contact pathway.     

某农药工业园区周边土壤重金属含量与风险评价

以苏南某农药工业园区周边30km2区域为研究区,采用同心圆法采集土壤样品183个,分析了农药工业园区周边土壤Cd、Cr、Cu、Ni、Pb、Zn、Hg和As8种重金属含量、空间变异性、来源及潜在风险.结果表明:以自然背景值为评价标准,研究区表层土壤Hg、Cu、Cd和Pb平均含量超过自然背景值,其中Hg和Cu含量最高;以国标二级标准为评价标准,土壤Cd、Cr、Ni、Pb、Zn、As6种重金属的单项污染指数平均值均小于1,Hg和Cu分别为1.59和1.05.在农药工业园区周边土壤重金属污染较重的东南方向和西北方向,随着与园区距离的增加,土壤Cd、Ni、Pb、Cr、As、Hg、Zn和Cu含量先上升、后下降、再趋于平稳.通过分析农药工业园区周边土壤重金属综合污染指数发现,距离园区约200～1000m周边土壤污染的风险较大,而1000m以外逐渐达到安全范围.利用地统计学和GIS相结合进行分析发现,8种重金属污染指数有明显的空间变异.依据相关分析与主成分分析结果推测,Zn、Ni、Cr、Pb和As主要来源于成土母质,而Hg、Cu和Cd主要与人类活动有关.     

Spatial distribution,contamination levels,sources, and potential health risk assessment of trace elements in street dusts of Urumqi city,NW China

Abstract

A total of 83 dust samples were collected from the streets of Urumqi city in NW China and analyzed for the concentrations of As, Cd, Cr, Cu, Hg, Mn, Ni, Pb, and Zn elements. The spatial distribution, contamination levels, main sources, and potential health risks of these trace elements were determined based on geostatistical analysis, geo-accumulation index, multivariate analysis, and the health risk assessment model introduced by the USEPA, respectively. The obtained results indicate that the average concentrations of Cd, Cr, Cu, Hg, Ni, Pb, and Zn exceed the corresponding background values determined in Xinjiang soils by factors of 2.0, 1.35, 1.38, 8.24, 1.28, 2.09, and 3.26, respectively. The spatial distribution patterns of the nine trace elements in street dust were found to be substantially heterogeneous, and the contamination level decreased in the following order: Hg?>?Zn?>?Pb?>?Cd?>?Cr?>?Cu?>?As?>?Ni?>?Mn. Based on the identified concentrations, the collected dust samples were found to be moderately polluted by Hg, and not polluted by As, Cr, Cu, Mn, and Ni. The remaining elements, Cd, Pb, and Zn lie on the borderline between non-pollution and moderate pollution levels. Furthermore, it was shown that Mn and Zn in street dusts originate from both, natural and anthropogenic sources, while As, Cd, Cr, Cu, Hg, Ni, and Pb are mainly produced by anthropogenic sources. Overall, the carcinogenic and non-carcinogenic health risks of the analyzed elements, instigated primarily by oral ingestion of street dusts, were found to be within the acceptable range for both, children and adults. As and Cr are the main non-carcinogenic elements, whereas Cr is the major carcinogenic element among the investigated dust-bound metals in the study area.     

南京城市土壤重金属含量及其影响因素

研究了南京城市土壤重金属含量、来源及其与土壤性质的关系。结果表明,南京城市土壤中,Fe、Ni、Co、V污染不明显,但受到了不同程度的Mn、Cr、Cu、Zn、Pb污染,其中：Pb污染非常严重;重金属在土壤剖面分布没有规律性;Fe、Ni、Co、V元素主要来源于原土壤物质,Cu、Zn、Pb、Cr元素主要来源于人为输入,Mn可能在不同的土壤中来源不同;Fe、Cr、Ni、Co、V元素含量之间均呈极显著正相关,Cu、Zn、Pb、Cr元素含量之间均呈极显著正相关。Fe、Co、V、Ni含量与粘粒含量、CEC呈极显著正相关;Cu、Zn、Pb含量与粘粒含量呈极显著负相关;Cu、Zn、Pb、Cr含量与有机碳呈极显著正相关,Pb含量与pH呈极显著正相关。