Human and ecological risks of metals in soils under different land-use types in an urban environment of Bangladesh

Trace metal contamination in soil is of great concern owing to its long persistence in the environment and toxicity to humans and other organisms.Concentrations of six potentially toxic trace metals,Cr,Ni,Cu,As,Cd,and Pb,in urban soils were measured in Dhaka City,Bangladesh.Soils from different land-use types,namely,agricultural field,park,playground,petrol station,metal workshop,brick field,burning sites,disposal sites of household waste,garment waste,electronic waste,and tannery wast,and construction waste demolishing sites,were investigated.The concentration ranges of Cr,Ni,Cu,As,Pb,and Cd in soils were 2.4–1258,8.3–1044,9.7–823,8.7–277,1.8–80,and 13–842 mg kg^-1,respectively.The concentrations of metals were subsequently used to establish hazard quotients(HQs)for the adult population.The metal HQs decreased in the order of As>Cr>Pb>Cd>Ni>Cu.Ingestion was the most vital exposure pathway of studied metals from soils followed by dermal contact and inhalation.The range of pollution load index(PLI)was 0.96–17,indicating severe contamination of soil by trace metals.Considering the comprehensive potential ecological risk(PER),soils from all land-use types showed considerable to very high ecological risks.The findings of this study revealed that in the urban area studied,soils of some land-use types were severely contaminated with trace metals.Thus,it is suggested that more attention should be paid to the potential health risks to the local inhabitants and ecological risk to the surrounding ecosystems.     

汉江上游汉中段河流表层沉积物重金属污染风险评价

通过监测汉江上游汉中段河流表层沉积物重金属Pb,Cu,Zn,Cd,Cr的浓度,分析了各元素的含量分布特征,并选用Hakanson生态风险指数法对研究区进行了环境风险评价。结果表明,汉江上游汉中段各监测点重金属富集顺序为:Cd >Zn >Pb >Cr >Cu。单个重金属的污染指数C_fⁱ显示,汉江上游汉中段监测点仅有Cu的含量均值为0.83,小于1,为轻微污染;Pb,Zn,Cd,Cr的均值分别为1.06,1.25,1.33,1.02,略大于等于1,处于轻微污染以上水平,达到中度污染水平。综合分析多项重金属污染系数C_d,单项重金属的潜在生态风险系数E_rⁱ和多种重金属的生态系统的潜在生态风险指数I_R可知,汉江上游汉中段各监测点沉积物重金属污染属于轻微生态危害。     

博斯腾湖湿地边缘带农田土壤重金属的污染风险评价

对新疆博斯腾湖湿地边缘带农田土壤中8种重金属元素(As、Cd、Cr、Cu、Mn、Ni、Pb和Zn)地球化学特征进行分析。采用污染负荷指数(PLI)、潜在生态风险指数(RI)和生态风险预警指数(IER)对农田土壤重金属污染与环境风险进行评价。结果表明:(1)湿地边缘带农田土壤Pb和Zn呈现重度污染,As、Cd、Cr和Ni轻度污染,Cu轻微污染,Mn无污染。土壤As、Cd、Cr、Cu、Ni、Pb和Zn平均含量处于轻微风险水平。Cd是污染程度与生态风险等级最高的重金属元素;(2)湿地边缘带农田土壤PLI平均值为1.43,呈现轻度污染,RI平均值为20.62,呈现轻微生态风险状态,IER的平均值为–4.53,呈现无警态势。湿地边缘带PLI、RI与IER空间分布格局基本一致;(3)湿地边缘带农田土壤Pb与Zn来源主要受到人类活动的影响,Cr、Cu、Mn与Ni来源主要受到土壤地球化学作用的控制,As与Cd受自然因素和人为因素共同影响。     

Accumulation and potential sources of heavy metals in soils of the Hetao area,Inner Mongolia,China

Soil contamination by heavy metals is a problem in agricultural irrigation systems.To assess the accumulation and sources of heavy metals in the Yongji irrigation district of the Hetao area,Inner Mongolia,China,195 soil samples from 39 sites(0–100 cm)were collected,and Zn,Cu,Pb,Cr,and Cd concentrations were analyzed.The mean concentrations were 107.17,32.48,12.31,53.53,and 0.22 mg kg-1,respectively,with no significant differences between soil depths(P>0.05).Concentrations of Zn,Cu,and Cd were higher than the background levels,with moderate accumulation;the contamination factor(CF)values were 1.9,1.7,and 1.9,respectively,and the geoaccumulation index(Igeo)was>0.Concentrations of Pb and Cr were lower than,or close to,the background levels(CF<1,Igeo<0),indicating that they originated from a natural source.The monomial potential ecological risk index(Eri)for Zn,Cu,Pb,and Cr was low;Eri for Cd was 55.73,implying a moderate risk.The grade of potential ecological risk index of the five heavy metals(RI)was low,declining from south to north.The studied soils were contaminated with Zn,Cu,and Cd;principal component(PC)analysis implicated the enrichment of Cd and partial Cu(high loading in PC 2)was related to agricultural activities;Zn and partial Cu,closely associated with PC 3,may have originated from irrigation water from the Yellow River.Future agricultural development should focus on fertilizer and pesticide application and the quality of irrigation water.     

Pollution and Ecological Risk Assessment of Heavy Metals in Farmland Soils in Yanqi County,Xinjiang, Northwest China

A total of 50 farmland soil samples were collected from the Yanqi County, Xinjiang, China, and the concentrations of eight heavy metal elements (As, Cd, Cr, Cu, Mn, Ni, Pb and Zn) were determined by standard methods. The spatial distribution, pollution level and ecological risk status of heavy metals were analyzed based on GIS technology, the Geo-accumulation Index (Igeo), the Pollution Load Index (PLI) and the Potential Ecological Risk Index (RI). Results indicated that: (1) The average contents of Cd, Cr, Ni, Pb, and Zn of farmland soils exceeded the background values of irrigation soils in Xinjiang by 1.5, 1.40, 1.33, 2.63, and 4.92 times, respectively. Cd showed a no-pollution level, Zn showed a partially moderate pollution level, Pb showed a slight pollution level, and Cr, Cu, As, Mn, and Ni showed no-pollution level, compared to the classification standard. The PLI values of heavy metal elements of farmland soils varied from 0.83 to 1.89, with an average value of 1.29, at the moderate pollution level. (2) The Individual Potential Ecological Risk Index for heavy metals in the study area was ranked in the order of: As > Ni > Cu > Cd > Pb > Cr> Zn. The RI values of heavy metals of farmland soils varied from 3.45 to 11.34, with an average value of 6.13, at the low ecological risk level. (3) Cu and Mn of farmland soils were mainly originated from the soil parent material and topography of the study area. As, Cd, Ni and Pb were mainly originated from human activities, and Cr and Zn may originated from both natural and anthropogenic factors in the study area.     

Trace metals in sediments and aquatic plants from the Xiangjiang River, China

Purpose

The metal concentrations and Pb isotopic composition in sediments and plants from the Xiangjiang River, China, were investigated to understand the contamination and potential toxicity of metals in sediments; to determine the accumulation and distribution of metals in plant tissues; and to trace the possible pollution source of Pb in sediments and plants.

Materials and methods

Sediments and plants were collected from 43 sampling sites in the study region. After sediments were air-dried and passed through a 63-??m sieve, they were acid-digested and DTPA-extracted for determination of total and bioavailable metals. The plants were separated into roots, leaves, and stems; dried; cut into pieces; and digested with HNO₃?CH₂O₂. Metals (As, Cd, Cr, Cu, Ni, Pb, and Zn) and Pb isotopic composition were analyzed by inductively coupled plasma-mass spectrometry.

Results and discussion

Maximum As, Cd, Cr, Cu, Ni, Pb, and Zn concentrations in sediments were 47.18, 55.81, 129.5, 161.6, 160.4, 430.7, and 1,098.8?mg?kg^?1, respectively. The bioavailable fractions of As, Cd, Cu, Pb, and Zn had significant linear relationship with their corresponding total contents in sediments while no significant relationship was observed between bioavailable and total contents of Cr and Ni. In general, plant tissues showed higher As, Cd, Cu, Pb, and Zn concentrations and lower Cr and Ni concentrations compared with sediments. The ²⁰⁶Pb/²⁰⁷Pb ratios decreased in the order of total > bioavailable > stems ?? leaves > roots. A strong linear correlation was observed between the ²⁰⁸Pb/²⁰⁶Pb and ²⁰⁶Pb/²⁰⁷Pb ratios of the plant tissues, sediments, and the possible pollution sources of Pb in the Xiangjiang River.

Conclusions

As, Cd, Cu, Pb, and Zn demonstrated higher contamination levels in sediments and plants compared with Cr and Ni. Cd had highest potential ecological risk. The Pb from anthropogenic sources with low ²⁰⁶Pb/²⁰⁷Pb ratios was preferentially associated with the bioavailable fractions in sediments and accumulated in roots. The Pb in plant tissues is mainly derived from the Pb in sediment and is taken up through the sediment-to-root pathway.     

贵阳市城区土壤重金属分布特征及污染评价

调查了贵阳市不同功能区表层土壤中重金属含量及其分布特征,以基线为参比值,采用Hakanson潜在生态危害指数法对重金属的潜在生态风险进行了评价。结果表明,贵阳市城区土壤重金属(Hg、Cd、As、Pb、Cr、Cu、Ni、Zn)主要来源于工业、交通以及燃煤等活动,其平均含量分别为0.108、0.320、20.53、22.17、35.71、64.87、48.65、217.90mg/kg,除Cr外,均显著高于相应基线。工矿区土壤中Pb、Zn含量显著高于其他功能区(p0.05)。Hg和Cd是主要的生态危害因子,其污染已达强生态危害水平,其余均显示为轻微生态危害水平;不同功能区土壤重金属污染均已达强生态危害水平,且污染程度依次是:商务区工矿区文教区居民区城市绿地交通区。     

新疆奎屯垦区土壤重金属风险评价

采用网格法采样,对新疆奎屯垦区3个团场土壤中As、Pb、Cu、Cd、Cr和Ni含量进行了测定,系统分析了该地区土壤重金属的含量水平、潜在生态风险程度、主要污染因子和污染来源。结果表明:奎屯垦区土壤重金属As、Pb、Cd、Cu、Cr、Ni的平均值分别为20.21 mg kg-1、35.91 mg kg-1、0.40 mg kg-1、27.18 mg kg-1、77.02 mg kg-1、39.31 mg kg-1,均没有超过国家土壤环境质量二级标准,但As、Cd有个别样点超标。各元素平均含量值均超过新疆土壤背景值,其中Cd、As、Pb最为显著,呈现出累积趋势。各重金属潜在生态风险由高至低顺序为Cd>As>Pb>Ni>Cu>Cr,其中Cd为主要潜在生态风险因子。进一步相关分析和因子分析结果显示,各元素的来源可分为两类,Cd、Pb和As为一类,来源主要受各种人为活动影响,Cu、Cr、Ni为一类,来源主要与成土母质有关。     

长期污灌农田土壤重金属污染及潜在环境风险评价

以西安市某典型污灌区农田土壤为研究对象,分析长期污水灌溉对表层土壤重金属含量及富集状况的影响,采用内梅罗指数法和Hakanson潜在生态危害指数法对其污染现状及潜在环境风险进行评价。结果表明：长期污灌已导致农田土壤Cd、Cr、Cu、Hg、Ni、Pb和Zn7种重金属相对自然背景有不同程度累积,其富集比例依次为100%、82.69%、100%、100%、80.77%、98.08%和100%,仅有土壤As平均含量低于其背景水平;以国家土壤环境质量标准二级限量值作为污染评价阈值,其中Cd和Hg污染表现突出,按其污染指数平均值排序为Cd〉Hg〉Ni〉Cu〉Zn〉As〉Cr〉Pb;土壤重金属综合潜在环境风险为＂强＂等级,Hg、Cd的环境影响占据主导;随污灌年限增长,离灌渠越近,农田土壤重金属的污染水平和环境风险越高。鉴于该区土壤重金属已呈现较强生态危害性,应及时采取必要防治措施,调整土地利用结构,确保农田环境及农产品安全生产。     

辽宁省污灌区土壤重金属污染特征与生态风险评价

针对当前污灌区土壤污染研究中存在的问题,提出了一种模糊识别模型评价土壤综合环境质量,并对潜在生态风险指数法进行改进,用以计量重金属潜在生态风险。采用建立的方法对辽宁省污灌区土壤环境质量和重金属潜在生态风险进行了评价,结果显示:Cd是辽宁省污灌区首要重金属污染物,而Hg、Pb、Ni污染较为普遍;重金属的来源主要是灌溉污水和农田施肥;以工业废水为灌溉用水的灌区污染情况比以河水为灌溉用水的灌区污染严重;污灌区重金属元素污染程度大小依次为:Cd>Pb>Ni>Hg>Cu>Cr>As,而重金属潜在生态风险从大到小则依次为:Cd>Hg>Pb>Cu>Ni>As>Cr。总体来看,辽宁省污灌区存在一定程度的重金属污染,且具有较为明显的复合型污染特点,其潜在生态风险超出警戒水平,各灌区应根据各自污染特点和风险等级制定相应的污染防治对策。     

新乡市大棚菜田土壤重金属积累特征及污染评价

采用微波消解-ICP-AES技术,测定不同种植年限大棚菜田土壤样品中As、Pb、Zn、Cd、Cr、Mn、Ni、Cu等重金属的含量,研究不同种植年限与大棚菜田土壤重金属累积的相关性以及大棚菜田土壤重金属累积特征,并利用地积累指数法进行污染评价。结果表明:大棚菜田土壤重金属Zn、Pb、Ni、Mn和Cu的含量与种植年限具有极显著相关性;大棚菜田土壤中重金属Cd和Cr的含量与种植年限不相关。重金属元素间相关性分析表明,Zn与Pb、Cd、Ni、Mn、Cr、Cu,Pb与Cd、Ni、Mn、Cr、Cu,Cd与Ni、Mn、Cr,Ni与Mn、Cr、Cu,Mn与Cr、Cu具有污染同源性,Cu与Cd、Cr不具有污染同源性。地积累指数法污染评价结果显示Cd的污染等级达到了6级,已构成了极严重污染;Zn和Cu的污染等级达到2级,已构成了中度污染;Pb、Mn的污染等级达到1级,已经构成了轻~中度污染;As、Ni、Cr均未构成污染。     

Copper,Chromium, Nickel,Lead and Zinc Levels and Pollution Degree in Firing Range Soils

Small‐arms firing ranges are an important source of metal contaminants in the ecosystems located near these facilities, owing to the constant fall and alteration of the ammunition remnants on the soil, particularly in nearby berms. The objectives of this study were to analyse the pollution of chromium (Cr), copper (Cu), nickel (Ni), lead (Pb) and zinc (Zn) in rifle/pistol shooting range soils, to estimate their availability and to evaluate the influence of the ammunition used. The concentrations of Pb, Zn, Cu, Cr and Ni range from 55 to 6·309, 34 to 264, 19 to 98, 40 to 79 and 11 to 33 mg kg⁻¹, respectively. The moderate acidity and organic matter content favour the availability of Pb, followed by Cu > Zn > Ni > Cr. The values of different contamination indexes (I_geo, pollution index and integrated pollution index) suggest that Pb soil contamination is moderate to heavy, especially in the berm area and moderate for Cu and Zn. Lead ammunition is the main source of pollution, but another one was identified owing to the concentrations of Fe, Cr and Ni detected. Further studies are needed to verify their long‐term potential adverse effects. Copyright © 2016 John Wiley & Sons, Ltd.     

龙游硫铁矿区农田土壤重金属污染的空间 变异及在水稻中的积累

为了解浙江龙游硫铁矿区农田重金属污染状况,采集矿区265件农田土壤样品,分析8种重金属Cu、As、Hg、Zn、Cd、Ni、Pb、Cr元素全量,利用地统计学软件GS+9.0对研究区土壤各元素指标进行半变异函数拟合,并利用普通克里格法进行插值并绘制空间分布图。采集30件水稻籽粒样品,分析重金属在研究区中水稻籽粒的累积特征,并进行了健康风险评价。结果表明:矿区土壤中8种重金属元素的变异系数从0.72到1.76,离散程度较高。8种重金属的土壤空间半变异函数Cu、As、Hg元素符合指数模型,Zn、Cd、Ni、Pb符合球状模型,Cr符合高斯模型。元素Cu、Pb、Zn、Cr、Ni的块金值与基台值的比值C0/C0+C都小于0.25,说明空间变化主要受地质背景等因素影响;元素Cd、Hg和As的块金值与基台值的比值C0/C0+C在0.25~0.75之间,说明除了地质背景因素,人为活动等随机因素也有影响。矿区水稻籽粒中重金属Ni和Cd的变异系数最高,分别为0.95和0.87,说明Ni和Cd元素可能存在异常积累。矿区水稻籽粒对重金属的富集能力由大到小依次为Cd、Zn、Cu、Ni、As、Hg、Cr、Pb。健康风险评价结果表明矿区农田水稻籽粒中元素As、Cd的风险商大于1,存在潜在健康风险;而其他6种重金属Cu、Hg、Zn、Ni、Pb和Cr基本属于安全范围。     

Pollution assessment and spatial variation of soil heavy metals in Lixia River Region of Eastern China

Purpose

The effect of soil heavy metals on crops and human health is an important research topic in some fields (Agriculture, Ecology et al.). In this paper, the objective is to understand the pollution status and spatial variability of soil heavy metals in this study area. These results can help decision-makers apportion possible soil heavy metal sources and formulate pollution control policies, effective soil remediation, and management strategies.

Materials and methods

A total of 212 topsoil samples (0–20 cm) were collected and analyzed for eight heavy metals (Cd, Hg, As, Cu, Pb, Cr, Zn, and Ni) from agricultural areas of Yingbao County in Lixia River Region of Eastern China, by using four indices (pollution index (PI), Nemerow pollution index (PI_N), index of geo-accumulation (I _geo), E _i /risk index (RI)) and cluster analysis to assess pollution level and ecological risk level of soil heavy metals and combining with geostatistics to analyze the concentration change of heavy metals in soils. GS+ software was used to analyze the spatial variation of soil heavy metals, and the semi-variogram model is the main tool to calculate the spatial variability and provide the input parameters for the spatial interpolation of kriging. Arcgis software was used to draw the spatial distribution of soil heavy metals.

Results and discussion

The result indicated that the eight heavy metals in soils of this area had moderate variations, with CVs ranging from 23.51 to 64.37 %. Single pollution index and Nemerow pollution index showed that about 2.7 and 1.36 % of soil sampling sites were moderately polluted by Cd and Zn, respectively. The pollution level of soil heavy metals decreased in the order of Cd?>?Zn?>?Pb?>?As?>?Cu?>?Cr?>?Ni?>?Hg. The I _geo values of heavy metals in this area decreased in the order of Zn?>?Cd?>?As?>?Pb?>?Cu?>?Cr?>?Hg?>?Ni. According to the E _i index, except Cd that was in the moderate ecological risk status, other heavy metals in soils were in the light ecological risk status, and the level of potential ecological risk (RI) of soil sampling sites of the whole area was light.

Conclusions

The results of four indices and the analysis of spatial variation indicated that the contents of Cd and Zn were contributed mainly by anthropogenic activities and located in the south-east of this study area. However, the contents of Hg, As, Cu, Pb, Cr, and Ni in soils were primarily influenced by soil parent materials.

     

太原市污灌区土壤重金属污染现状评价

对太原市污灌区土壤重金属分布特征进行了分析评价,结果表明重金属Pb、Zn、Cu、Ni、Mn、Cr、As、Hg、Cd含量均值均未超过土壤环境质量标准（GB15618—1995）,但其平均值均显著高于太原市土壤背景值。各重金属间的相关分析表明,Pb、Zn、Cu、Ni、Mn、Cr、As、Cd之间呈极显著相关,说明这8种元素污染源可能相同。Hg是本区表层土壤重金属污染的主要因子,重金属元素的污染程度依次为Hg〉Cd〉Pb〉As〉Cu〉Zn〉Cr〉Mn〉Ni。土壤重金属单项污染指数均值均大于1,综合污染指数为2.81,总体上,污染水平为中度及其以上。各种重金属单因子污染指数和综合指数在研究区有相似的空间分布格局,总体分布趋势为东南部小店地区和中南部晋源区相对较高,南部清徐县相对较小;通过因子分析并结合污灌区污染源调查,表明Hg除受污水灌溉的影响外,燃煤释放的Hg可能是重要来源之一,Cd、Zn、Pb和Cu可能来自污水灌溉和大气沉降,以污水灌溉的贡献为主,Ni、Mn、As、Cr来自污水灌溉。Hg、Cd是太原市污灌区土壤中需要优先控制的重金属。     

黔西煤矿区周边土壤重金属形态特征、污染评价及富集植物筛选

[目的]研究黔西某煤矿区周边土壤重金属污染情况、重金属形态潜在风险及其周边重金属富集植物,为当地的重金属污染防治提供科学依据。[方法]采用潜在生态风险评价及模糊数学法的两种评价方法(单因素决定模型和加权平均模型)对煤矿区及非煤矿区土壤进行重金属生态风险评价,对影响土壤肥力的土壤理化指标进行检测,利用风险评估编码法对重金属形态进行分析,并采用生物富集系数法对煤矿区周边富集重金属植物进行筛选。[结果]煤矿区Hg,Cd,As,Zn,Cr及Ni平均值含量分别是背景值的2.47,3.65,2.00,1.23,1.74,1.69倍。煤矿区潜在生态危害趋势为:CdHgAsNiCrPbZn。模糊数学法单因素决定模型评价显示,非煤矿区污染大于煤矿区,加权平均模型则反之。煤矿区Cd,Cr,Cu,Mn,Ni,Pb及Zn潜在风险指数分别为69.17%,7.97%,8.24%,40.10%,45.29%,53.70%及29.90%。蜈蚣草对As富集系数大于1.00,火棘、构树、盐肤木、马桑、凤尾蕨及金丝梅等对Cd富集系数大于1.00,马桑及白蒿对Pb富集系数大于1.00。[结论]煤矿区存在重金属污染,以Cd,As,Hg较为严重。煤矿区周边土壤中重金属对环境构成的潜在风险顺序为:CdPbNiMnZnCuCr。对当地而言,蜈蚣草可作为煤矿区周边修复As污染的先行植物,凤尾蕨可作为修复Cd污染的先行植物,马桑可作为修复Pb污染的先行植物。     

Identifying the Sources and Contamination Status of Potentially Toxic Trace Elements in Agricultural Soils

Elevated concentrations of potentially toxic trace elements in agricultural soils contribute to soil pollution affecting food quality and safety. We assessed pollution levels in agricultural systems, lowland rice (LL) and highland cash crops (HL), by comparing with non-agricultural soils (NA). Correlation analysis and principal component analysis (PCA) were performed, and geo-accumulation index (I_geo) and pollution loading index (PLI) were calculated. Zinc in LL, and Cd in LL and HL, were significantly higher than in NA. The I_geo values of cooper (Cu), lead (Pb), nickel (Ni), zinc (Zn), and cadmium (Cd) ranged from uncontaminated to moderately contaminated (Class 0 to 2) for LL, HL, and NA. Overall, trace element levels were categorized as unpolluted based on PLI. Soil properties significantly correlated with Cu, Pb, Ni, and Zn concentrations but not with Cd. Based on PCA, sources of origin for Cu, Pb, Ni, and Zn were lithogenic, while the sources for Cd was anthropogenic in the studied agricultural soils.     

Risk assessment,spatial distribution,and source identification of heavy metal(loid)s in paddy soils along the Zijiang River basin,in Hunan Province,China

Purpose

This study aimed to reveal spatial distribution of As, Cd, Cr, Cu, Mn, Ni, Pb, Sb, V, and Zn in paddy soils in the Zijiang River basin and to evaluate its pollution status and potential ecological risks, and thus to provide basic information for rational utilization of paddy soils in the study area.

Materials and methods

The heavy metal(loid) concentrations in one hundred and thirty-five paddy soil samples (these samples were collected from the top 0–20 cm layer) were measured by inductively coupled plasma-optical emission spectrometry. The spatial distribution characteristics of the heavy metal(loid)s were depicted by the Ordinary Kriging interpolation analysis. The contamination degree and potential ecological risks of the heavy metal(loid)s in paddy soils were assessed by Nemerow’s comprehensive index, geoaccumulation index, potential ecological risk factor, and potential ecological risk index. The potential sources of the heavy metal(loid)s were deduced by Pearson’s correlation analysis, hierarchical cluster analysis, and principal component analysis.

Results and discussion

The mean concentrations of the heavy metal(loid)s decreased in the order of Mn?>?V?≈?Zn?>?Cr?>?Ni?≈?Pb?>?Cu?≈?Sb?>?As?>?Cd. Except for Cd and Sb, the mean concentrations of As, Cr, Cu, Mn, Ni, Pb, V, and Zn were close to the background reference values. The concentration of Cd in 94.8% of samples exceeded the soil quality standard value (grade II, 5.5?<?pH?<?6.5, GB 15618–1995). According to the assessments of pollution and potential ecological risks for the heavy metal(loid)s, 45.2% and 46.7% of samples were severely polluted and moderately polluted, respectively. The potential sources analysis indicated that Cd, Sb, and Zn mainly originated from agricultural, mining, and smelting activities; As, Cu, and Pb mainly originated from agricultural activities, while coal combustion by-products was another major source of these heavy metal(loid)s in paddy soils near the thermal power plant in the southwest corner of the study area; Cr, V, Mn, and Ni mainly originated from natural source.

Conclusions

Cadmium and Sb are the main contaminants in paddy soils in the study area, and there are hot-spot pollution areas.

     

Heavy Metal Contamination in Peach Trees Irrigated with Water from a Heavily Polluted Creek

This study was conducted to characterize the heavy metal contamination in the soils of peach orchards irrigated with water from Nilüfer creek, which is heavily polluted by industrial and municipal wastes. Twenty-one peach orchards with 3 different cultivars in 7 orchards each located along Nilüfer creek were monitored in the experiment. To determine levels of pollution, soils and aboveground parts of the trees were sampled and analyzed for iron (Fe), manganese (Mn), zinc (Zn), copper (Cu), cobalt (Co), nickel (Ni), chromium (Cr), lead (Pb), and cadmium (Cd). Total amounts of Ni and Cr were found to be at the excessive levels in soils. Extractable Ni concentration decreased with increasing pH and CaCO₃ content in soils. Leaf metal contents were generally at tolerable levels, but Ni and Pb accumulated to toxic levels in different parts of the fruit (flesh and peel). Except for Fe and Ni, plant concentrations of the metals did not correlate with their total and DTPA-extractable concentrations in the soils. There was no significant difference among the cultivars in accumulation of heavy metals.     

黄山景区土壤重金属分布特征及其潜在生态风险评价

选取黄山风景区6条主要游览步道,采集70个土壤样品,用等离子发射光谱法测定其Zn、Cu、Pb、Cr、As和Ni的含量并分析其分布特征,应用潜在生态风险指数法对黄山风景区土壤重金属污染进行分析和评价。结果表明,黄山风景区土壤Zn、Cu、Pb、Cr、As、Ni的平均含量分别为157.02,19.73,46.44,41.46,29.47,10.26mg/kg,除Ni外,所有元素均超出土壤背景值。结合土壤重金属在不同景区的分布和样带上的横向分布规律以及相关性分析,得出Cu、Pb主要来源于汽车尾气排放物的沉降,在云谷景区和玉屏景区相对较高;Ni、Cr来源于地壳源,在样带的横向分布上呈逐渐增加的趋势;Zn在北海景区含量最高,受游客的旅游活动干扰最大;As可能由于农药的喷洒导致整个景区均存在一定程度的污染。黄山风景区土壤重金属整体处于轻微生态风险,各种重金属的潜在生态危害由强至弱依次为:As>Pb>Cu>Zn>Cr>Ni,其中,As是黄山景区土壤最主要的潜在生态风险因子。