宝鸡市某工业园区灰尘重金属含量、形态及生态风险分析

利用X射线荧光光谱法(XRF)和原子荧光分光光度法(AFS)分析了宝鸡市某工业园区灰尘中重金属的含量。结果表明,宝鸡市某工业园区灰尘中As,Co,Cr,Cu,Hg,Mn,Ni,Pb和Zn的平均含量分别为23.3,16.4,1 591.8,178.2,0.243,346.5,40.2,1 586.2和1 918.8mg/kg,其中,Cr,Cu,Hg,Pb和Zn累积比较明显;铅锌冶炼厂周边灰尘中As,Cu,Hg,Pb和Zn的含量高于电厂。采用修正BCR法(欧洲共同体标准物质局)和原子吸收分光光度法(AAS)研究了灰尘中重金属的形态特征。结果表明,灰尘中Cu主要以残渣态和可氧化态的形式存在,Pb主要以可还原态的形式存在,Zn主要以乙酸可提取态的形式存在,Mn和Co主要以乙酸可提取态和残渣态存在,Ni和Cr主要以残渣态存在。灰尘中Pb,Zn,Co,Mn和Cu有55%~85%可以发生移动,易被生物利用,危害较大。潜在生态风险评价表明,灰尘中重金属的污染及潜在生态风险达到严重水平,铅锌冶炼厂周边灰尘中重金属的污染和潜在生态风险高于电厂。     

Extractability and plant uptake of heavy metals in alum shale soils

Abstract

Fifty soil samples (0–20 cm) with corresponding numbers of grain, potatoes, cabbage, and cauliflower crops were collected from soils developed on alum shale materials in Southeastern Norway to investigate the availability of [cadmium (Cd), copper (Cu), zinc (Zn), lead (Pb), nickel (Ni), and manganese (Mn)] in the soil and the uptake of the metals by these crops. Both total (aqua regia soluble) and extractable [ammonium nitrate (NH₄NO₃) and DTPA] concentrations of metals in the soils were studied. The total concentration of all the heavy metals in the soils were higher compared to other soils found in this region. Forty‐four percent of the soil samples had higher Cd concentration than the limit for application of sewage sludge, whereas the corresponding values for Ni, Cu, and Zn were 60%, 38%, and 16%, respectively. About 70% the soil samples had a too high concentration of one or more of the heavy metals in relation to the limit for application of sewage sludge. Cadmium was the most soluble of the heavy metals, implying that it is more bioavailable than the other non‐essential metals, Pb and Ni. The total (aqua regia soluble) concentrations of Cd, Cu, Zn, and Ni and the concentrations of DTPA‐extractable Cd and Ni were significantly higher in the loam soils than in the sandy loam soils. The amount of NH₄NCyextractable metals did not differ between the texture classes. The concentrations of DTPA‐extractable metals were positively and significantly correlated with the total concentrations of the same metals. Ammonium nitrate‐extractable metals, on the other hand, were not related to their total concentrations, but they were negatively and significantly correlated to soil pH. The average concentration of Cd (0.1 mg kg^‐1 d.w.) in the plants was relatively high compared to the concentration previously found in plants grown on the other soils. The concentrations of the other heavy metals Cu, Zn, Mn, Ni, and Pb in the plants were considered to be within the normal range, except for some samples with relatively high concentrations of Ni and Mn (0–11.1 and 3.5 to 167 mg kg‘¹ d.w., respectively). The concentrations of Cd, Cu, Zn, Ni, and Mn in grain were positively correlated to the concentrations of these respective metals in the soil extracted by NH₄NO₃. The plant concentrations were negatively correlated to pH. The DTPA‐extractable levels were not correlated with plant concentration and hence DTPA would not be a good extractant for determining plant availability in these soils.     

包头市铜厂周边土壤中重金属垂直分布特征与形态分析

为了解包头市铜厂周边地区土壤剖面中重金属污染状况,采用火焰原子吸收分光光度法和Tessier连续提取法,对土壤中6种重金属（Cu,Zn,Mn,Ni,Pb和Cd）的垂直分布特征、形态及潜在生物可利用性进行了分析。结果表明:研究区土壤剖面各层土壤中6种重金属含量均超过内蒙古土壤背景值,Cu,Pb和Cd为主要污染物。随采样深度的增加,Cu,Zn,Pb和Mn的含量呈现下降趋势,且由相关性系数可知重金属Cu,Zn和Pb可能有相同人为或自然污染源;土壤剖面中6种重金属均主要以残渣态存在,含量均在50%以上,对生物危害较小;潜在生物可利用性分析结果为:Cu（32.61%） > Mn（31.85%） > Ni（24.90%） > Zn（16.60%） > Cd（15.23%） > Pb（14.87%）,Cu和Mn的潜在生物可利用性较大,其次为Ni,Zn,Cd和Pb潜在生物可利用性较小。     

Cadmium,Lead, Copper,Zinc, and Nickel in Lettuce and Dry Beans as Related to Mehlich-3 Extraction in Three Brazilian Latossols

Lettuce (Lactuca sativa L.) and dry beans (Phaseolus vulgaris L.) were grown in three Brazilian Red-Yellow Latossols (Oxisols) in greenhouse conditions with cadmium (Cd), lead (Pb), copper (Cu), zinc (Zn), and nickel (Ni) applied to soils in treatments arranged as a randomized complete block design. Plant metals were analyzed in lettuce shoots and dry beans roots, stems, leaves, and seeds. After plant growth, soil samples from the pots were extracted with Mehlich-3 (M-3) for metal availability evaluation. The release of Ni in the M-3 extraction was dependent on the soil exchangeable aluminum (Al^{3 +}). Mehlich-3 was efficient for determination of availability of Cd, Pb, Cu, Zn, and Ni for dry beans and availability of Cd and Ni for lettuce. The dry bean leaves Cd, Pb, Cu, Zn, and Ni were highly correlated with their recovering from soils with M-3. The same was observed for Cd and Ni in lettuce shoots and the M-3 recovered metals from soils.     

Comparison of routine soil tests and EPA method 3050 as extractants for heavy metals in Delaware soils

Abstract

Agricultural use of sewage sludges can be limited by heavy metal accumulations in soils and crops. Information on background levels of total heavy metals in soils and changes in soil metal content due to sludge application are; therefore, critical aspects of long‐term sludge monitoring programs. As soil testing laboratories routinely, and rapidly, determine, in a wide variety of agricultural soils, the levels of some heavy metals and soil properties related to plant availability of these metals (e.g. Cu, Fe, Mn, Zn, pH, organic matter, texture), these labs could participate actively in the development and monitoring of environmentally sound sludge application programs. Consequently, the objective of this study was to compare three soil tests (Mehlich 1, Mehlich 3, and DTP A) and an USEPA approved method for measuring heavy metals in soils (EPA Method 3050), as extractants for Cd, Cu, Ni, Pb and Zn in representative agricultural soils of Delaware and in soils from five sites involved in a state‐monitored sludge application program.

Soil tests extracted less than 30% of total (EPA 3050) metals from most soils, with average percentages of total metal extracted (across all soils and metals) of 15%, 32%, and 11% for the Mehlich 1, Mehlich 3, and DTPA, respectively. Statistically significant correlations between total and soil test extractable metal content were obtained with all extractants for Cu, Pb, and Zn, but not Cd and Ni. The Mehlich 1 soil test was best correlated with total Cu and Zn (r=0.78***, 0.60***, respectively), while the chelate‐based extractants (DTPA and Mehlich 3) were better correlated with total Pb (r=0.85***, 0.63***). Multiple regression equations for the prediction of total Cu, Ni, Pb, and Zn, from soil test extractable metal in combination with easily measured soil properties (pH, organic matter by loss on ignition, soil volume weight) had R² values ranging from 0.41*** to 0.85***, suggesting that it may be possible to monitor, with reasonable success, heavy metal accumulations in soils using the results of a routine soil test.     

Chemical and Mineralogical Properties of Norwegian Alum Shale Soils,with Special Emphasis on Heavy Metal Content and Availability

Abstract

Alum shale and till soils overlying alum shale bedrock were analysed for aqua regia and NH₄OAc/EDTA extractable Pb, Cu, Zn, Ni, Mn and Cd. The means of these determinations were compared with those of Norwegian, Finnish and Swedish non-alum shale soils. Alum shale soils seemed to contain higher amounts of both total and easily extractable Cu, Zn, Ni and Cd. Total Pb content also seemed to be higher in the alum shale soils. The relative availability of Cd, Ni and Mn, expressed as the ratio of NH₄OAc/EDTA to aqua regia extractable, was found to be greater than that of Pb, Cu and Zn in the alum shale and till soils.     

在法国前铅和锌冶炼厂附近的城市土壤重金属的污染、分离和利用

smelters in Northern France were studied by analysing the chemical forms of these metals and evaluating their phytoavailability. These metals were determined using flame or electrothermal absorption atomic spectrometry （FAAS or ETAAS）, depending on their concentration levels. After optimisation of the ETAAS method, characteristic mass of In in water and aqua regia were 9.9 and 18 pg, respectively, showing the high sensitivity of the analytical Soil contamination by metals from anthropogenic activities （e.g., mining and smelting） is a major concern for the environment and human health. Environmental availability of cadmium （Cd）, lead （Pb）, zinc （Zn）, copper （Cu）, and indium （In） in 27 urban soils located around two former Pb and Zn smelters in Northern France were studied by analysing the chemical forms of these metals and evaluating their phytoavailability. These metals were determined using flame or electrothermal absorption atomic spectrometry （FAAS or ETAAS）, depending on their concentration levels. After optimisation of the ETAAS method, characteristic mass of In in water and aqua regia were 9.9 and 18 pg, respectively, showing the high sensitivity of the analytical procedure. Metal partitioning was conducted using a four-step sequential extraction procedure. The results showed that Cd and Zn were mainly in the acid-extractable and reducible forms in the urban soils studied. In contrast, Pb and In were largely in the reducible fraction. However, in some samples, the amount of In extracted in the residual or exchangeable fraction was higher than that in the reducible fraction. Copper was mainly found in the reducible and residual fractions. A pot experiment was conducted in a glasshouse with seven soils （six contaminated and one uncontaminated） and two plant species, ryegrass and lettuce. The results showed transfer of metals from the contaminated soils to the shoots of ryegrass and the edible part of lettuce. The metal bioconcentration factor was in the order of Cd Cu > In > Zn Pb for lettuce leaves, whereas for ryegrass shoots, three orders were found, Cd > Zn > Cu In > Pb, Cd ≥ In > Zn > Cu Pb, and Zn > Cd > Cu > In > Pb, depending on the physico-chemical properties of the soils, such as pH, cation exchange capacity, carbonates, and organic matter. It was established that the metal toxicity was related to the contamination levels and the physico-chemical properties, including pH, organic matter, and in a lesser extent, Ca, Mg, and phosphorus contents, of the soils. However, it was shown that lettuce could grow on soils having high Cd and CaCO₃ contents. Cadmium was one of the most available metals while Pb was always the least available in the soils studied.     

Metal Status of Soils and Plants Irrigated with Water from Lake İznik,Turkey

Lake ?znik, located in the southeast part of the Marmara region in Turkey, is considered the largest lake in the region. Soil pollution from irrigation with lake water has become an important concern for arable lands surrounding the lake. Therefore, a study was conducted to investigate trace element contamination of soils and plants irrigated with water from the lake, which has been polluted with industrial and municipal wastes. Eleven different crops grown in 30 different horticultural fields, consistently irrigated with lake water, were studied. To determine pollutant concentrations, soils, plants, and water were sampled and analyzed for both total and extractable iron (Fe), manganese (Mn), zinc (Zn), copper (Cu), cobalt (Co), nickel (Ni), chromium (Cr), lead (Pb), and cadmium (Cd). Iron, Cu, and Ni in destructively sampled soils were found to be excessive in soils. The results were subjected to statistical analysis using simple correlations and t‐test. There were no statistically significant relationships among the total and extractable metals in soils and extractable plant metals. Because of lack of standard concentrations indicating excessive concentration of extractable elements, statuses of extractable elements in the soils were not evaluated. Cobalt, Pb, Cr, and Cu concentrations were greater than the normal range in leaves. The accumulation of metals differed greatly among the various plant species, but irrigation with lake water did not increase metals in soils. The appearance of metals in soils might be due to agricultural activities and parent material. Continuous monitoring and future studies of the area are recommended to ascertain long‐term impacts of pollution on plants.     

Prediction of available heavy metals by six chemical extractants in a sewage sludge‐amended soil

Abstract

In a field experiment conducted during three years in a sandy‐loam, calcareous soil, one aerobically digested sewage sludge (ASL) and another anaerobically digested sewage sludge (ANSL) were applied at rates of 400, 800, and 1,200 kg N/ha/year, and compared with mineral nitrogen fertilizer at rates of 0, 200, 400, and 600 kg N/ha/year in a cropping sequence of potato‐corn, potato‐lettuce, and potato, the first, second, and third year, respectively. Results showed that the highest values of soil extractable metals were obtained with aqua regia, whereas the lowest levels with DTPA. All metal (Zn, Cu, Cd, Ni, Pb, and Cr) gave significant correlations between metal extracted with the different extractants and metal loading applied with the sludges. The metal extractable ion increased over the control for Zn, Cu, Cd, Ni, Pb, and Cr extracted with DTPA, EDTA (pH 8.6) and 0.1 N HC1, for Zn, Cd, Ni, Pb, and Cr extracted with EDTA (pH 4.65) and AB‐DTPA, and for Zn, Cd, Ni, and Cr extracted with aqua regia. The level of metal‐DTPA extractable resulted highly correlated with that obtained by the other methods, except the Ni‐aqua regia extractable. The soil extractable elements which showed significant correlations with metals in plant were: Zn, Cu, Cd, and Ni in potato leaves, Cd, Ni, and Pb in corn grain, and Zn and Cd for lettuce wrapper leaves. In general, all the chelate based extractants (DTPA, EDTA pH 4.6, EDTA pH 8.6, AB‐DTPA) were equally useful as indicator of plant available metals in the soil amended with sludge.     

长江三角洲地区土壤盐酸可提取态重金属含量的空间变异特征

以江苏昆山市为典型区,对长三角地区土壤盐酸可提取态重金属含量的结构特征进行分析,得出该区盐酸可提取态重金属的空间分布格局并揭示了引起这种分布格局的成因和污染来源,结果表明：昆山市盐酸可提取态Cd、Cr、Cu、Pb、Zn、Hg属强变异,Ni和Co为中等变异。半方差函数模型拟合表明所有盐酸可提取态重金属元素均符合球状模型,8种重金属元素在一定范围内均存在空间相关性。采用Kriging最优内插法得到了盐酸可提取态重金属含量的空间分布格局,表明土壤盐酸可提取态重金属含量与工业活动、污水灌溉和大气降尘密切相关。通过主成分分析与地统计学相结合的方法,得出该区盐酸可提取态重金属由4个主成分构成,第一主成分为Cd、Cu、Pb、Cr和Zn,决定这一成分的主要因素为工业污水灌溉、大气降尘和元素地球化学特征;第二主成分为Ni,决定这一成分的主要因素为土壤内部因子;第三主成分为Hg,该成分主要受工业点源污染的影响;第四主成分为Co,该成分可能主要受地形影响。     

北京市密云水库上游金矿区土壤重金属含量、来源及污染评价

运用多变量分析、富集因子及地累积指数法对北京市密云水库上游金矿区土壤重金属的来源、污染评价进行了研究。利用电感耦合等离子体质谱法（ICP—MS）测定土壤中Be、V、co、Ni、cu、cd、Pb的含量,用原子荧光光谱法（AFS）测定As、Hg含量,用X射线衍射（xRD）测定土壤所含矿物质成分。结果表明,除As外各重金属平均含量均高于北京市土壤元素背景值。XRD分析结果显示,土壤的矿物质成分相似,主要包括石英、长石、伊利石、高岭石、蒙脱石、方解石。多变量分析（主成分、聚类、相关性分析）表明,cu、cd、Pb和Hg为人为源,主要来源于矿产的开采或运输过程;Be、V、Ni和co来自混合源,即矿产开采过程和土壤背景;As为自然源,来自于岩石矿物的风化、侵蚀及土壤母质。富集因子法及地累积指数法评价结果表明,cu、Cd、Pb、Hg污染较严重,受人为活动的显著影响,而Be、V、co、Ni轻微污染,As无污染。该结果进一步验证了多变量分析的结果。     

Increasing the Knowledge of Heavy Metal Contents and Sources in Agricultural Soils of the European Mediterranean Region

This paper contributes to increase the knowledge of the contents and sources of heavy metals (Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn) to agricultural soils in Castellón province (Spain), a representative area of the European Mediterranean region. The surface horizons of 77 agricultural soils under vegetable crops were sampled and heavy metals were analysed by atomic absorption spectroscopy (AAS) after microwave extraction using the USEPA 3051A method. Mean heavy metal contents were similar to those obtained in other areas of this region. However, heavy metal contents (e.g. Cr, Pb) in some soils were above the maximum limit set in the 86/278/CEE Directive. Multivariate analysis (correlation analysis and principal component analysis – PCA) was performed so as to identify the sources of heavy metals to soils. Co, Fe and Ni were highly correlated amongst them (r?>?0.800; p?<?0.01), whereas Cr and Mn were less correlated with Co, Fe and Ni (r?>?0.500; p?<?0.01). Other relationships among heavy metals (i.e. Cu, Pb and Zn) were also identified, although correlation coefficients were not so high as those among Co, Fe and Ni (r?<?0.500; p?<?0.01). Contents of Co, Fe, Mn and Ni were interpreted to be mainly associated with parent rocks corresponding to the first principal component (PC1). On the other hand, Cd, Cu, Pb and Zn were interpreted to be mainly related to anthropogenic activities and comprised the second (Pb and Zn) and the third (Cd and Cu) principal components (PC2 and PC3, respectively), designated as anthropogenic components. Remarkably, Cr appears to be related in the study area to both the lithogenic and the anthropogenic components. Lithogenic elements were highly correlated with soil properties. Positive relationships with CEC (r?>?0.200; p?<?0.05) and clay (r?>?0.400; p?<?0.01), and negative relationships with carbonates (r?>??0.400; p?<?0.01) and sand (r?>??0.300; p?<?0.01) were observed. Anthropogenic elements were less correlated with soils properties, since these elements are generally more mobile because they form more soluble chemical species associated to anthropogenic sources. Particularly, no correlation was found between Cd and Zn and soil properties. These findings extend results achieved in other parts of the region, highlighting the need to set soil quality standards in order to declare soils affected by anthropogenic pollution, particularly in the case of anthropogenic metals such as Cd, Cu and Pb, and also Cr and Zn in some areas. Further knowledge from other areas in this region would improve the basis for proposing such standards at regional level, which is a priority objective in Europe according to the European Thematic Strategy for Soil Protection.     

Leaching Behavior of Heavy Metals In Biosolids Amended Sandy Soils

Use of biosolids in agriculture to improve crop production and soil quality have created concerns due to content of heavy metals that may affect surface or ground water quality. A column leaching study was conducted to evaluate the leaching potential of copper (Cu), lead (Pb), zinc (Zn), cdmium (Cd), cobalt (Co), chromium (Cr), and nickel (Ni) from two typical agricultural sandy soils in South Florida (Spodosol and Alfisol) with increasing application of pelletized biosolids (called PB) at the rates of 0, 1.25, 5.0, 10.0 g kg^?1, respectively together with chemical fertilizer (CF). Elevated PB rate resulted in reduced leaching loss of Cu, Pb, Zn, Cd, Co, Ni from Spodosol, but resulted in increased loss of Pb, Zn, Cd, and Co from Alfisol. Significant reduction in Cu loss occurred in both soils, which can be attributed to the strong binding of Cu with organic matter from the applied PB. Percentage of Cd loss as of total Cd was 13% – 41%, the highest in all the heavy metals, whereas loss of Pb as of total Pb was less than 6.6%, though the concentrations of Pb, Cd, Co, and Ni in leachate were mostly above the limits of U.S. EPA drinking water standards or the national secondary drinking water standards. These results indicate that soil properties, PB application rates, and chemical behavior of elements jointly influence the leachate total loads of heavy metals in sandy soils applied with biosolids. Application of CF together with BP at a rate higher than 10.0 g kg^?1 for sandy soils may pose potential threats to water quality due to enhanced leachate loads of Cr and Ni in Spodosol and Pb, Zn, Cd, Co and Ni in Alfisol.     

Metal Extractability in Binary and Multi-metals Spiked Calcareous Soils

In the present study, a laboratory experiment was designed to compare the 0.01 M calcium chloride (CaCl₂) and diethylenetriaminepentaacetic acid (DTPA) extraction methods for their ability to predict cadmium (Cd), copper (Cu), iron (Fe), Manganese (Mn), nickel (Ni), and zinc (Zn) availability and mobility in five calcareous soils. The soils were spiked with different amounts of metals (0, 50, 100, 200, and 400 mg kg^?1) both in binary (Cu and Zn; Ni and Cd; Fe and Mn) and in multi-systems (Cd, Cu, Fe, Mn, Ni, and Zn) and incubated for 1 months at field capacity. In metal-spiked soils, both extraction methods showed a linear relationship of extractable to total metals for all soils. The fraction of total metals extracted by DTPA was much higher than the fraction extracted by CaCl₂, which was attributed to the formation of soluble metal-complexes in the complexing extracts calculated by the Visual Minteq program. DTPA extraction method showed higher selectivity for Cu over other metals both in binary and in multi-systems. Different order of metals extractability was found in binary and multi-systems for both extraction methods. Solid/solution distribution coefficient (K_d) was calculated by the ratio of the solid phase to soil solution concentration of metals extracted by CaCl₂ or DTPA extraction methods. Both in binary and in multi-systems, the average K_d (l kg^?1) of metals by soils were in the order of Mn (5398) > Fe (4413) > Zn (3376) > Cu (2520) > Ni (969) > Cd (350) in the CaCl₂-extractable metals and Fe (35) ≥ Ni (34) > Zn (18) > Mn (11.2) > Cu (6.3) > Cd (4) in the DTPA-extractable metals. Results showed that among the six studied metals, Cd had the lowest K_d, implying a relative higher mobility in these calcareous soils. The Visual Minteq indicated that in the CaCl₂-extraction method and in both binary and multi-systems the dominant species for Cu, Mn, Ni, and Zn were Cu²⁺, Mn²⁺, Ni²⁺ and Zn²⁺, respectively, while for Cd and Fe, the dominant species were CdCl⁺ and Fe(OH)²⁺, respectively.     

Modelling trace metal extractability and solubility in French forest soils by using soil properties

Soil/solution partitioning of trace metals (TM: Cd, Co, Cr, Cu, Ni, Sb, Pb and Zn) has been investigated in six French forest sites that have been subjected to TM atmospheric inputs. Soil profiles have been sampled and analysed for major soil properties, and CaCl₂‐extractable and total metal content. Metal concentrations (expressed on a molar basis) in soil (total), in CaCl₂ extracts and soil solution collected monthly from fresh soil by centrifugation, were in the order: Cr > Zn > Ni > Cu > Pb > Co > Sb > Cd , Zn > Cu > Pb = Ni > Co > Cd > Cr and Zn > Ni > Cu > Pb > Co > Cr > Cd > Sb , respectively. Metal extractability and solubility were predicted by using soil properties. Soil pH was the most significant property in predicting metal partitioning, but TM behaviour differed between acid and non‐acid soils. TM extractability was predicted significantly by soil pH for pH < 6, and by soil pH and Fe content for all soil conditions. Total metal concentration in soil solution was predicted well by soil pH and organic carbon content for Cd, Co, Cr, Ni and Zn, by Fe content for Cu, Cr, Ni, Pb and Sb and total soil metal content for Cu, Cr, Ni, Pb and Sb, with a better prediction for acidic conditions (pH < 6). At more alkaline pH conditions, solute concentrations of Cu, Cr, Sb and Pb were larger than predicted by the pH relationship, as a consequence of association with Fe colloids and complexing with dissolved organic carbon. Metal speciation in soil solutions determined by WHAM‐VI indicated that free metal ion (FMI) concentration was significantly related to soil pH for all pH conditions. The FMI concentrations of Cu and Zn were well predicted by pH alone, Pb by pH and Fe content and Cd, Co and Ni by soil pH and organic carbon content. Differences between soluble total metal and FMI concentrations were particularly large for pH < 6. This should be taken into account for risk and critical load assessment in the case of terrestrial ecosystems.     

杭州市城市土壤中重金属、磷和其它元素的特征

Health implications of inhaling and/or ingesting dust particles with high concentrations of heavy metals from urban soils are a subject of intense concern. Understanding the geochemistry of these metals is key to their effective management. Total concentrations of heavy metals, phosphorus (P) and 8 other elements from topsoil samples collected at 82 locations in Hangzhou City were measured to: a) assess their distribution in urban environments; and b) understand their differentiation as related to land use. Metal mobility was also studied using a three-step sequential chemical fractionation procedure. About 8.5%, 1.2%, 3.6%, 11.0% and 30.3% of the soil samples had Cd, Cr, Cu, Pb, and Zn concentrations, respectively, above their allowable limits for public and private green areas and residential use. However, in commercial and industrial areas, most samples had metal concentrations below their allowable limits. Statistical analyses revealed that the 16 measured elements in urban soils could be divided into four groups based on natural or anthropic sources using a hierarchical cluster analysis. Additionally, Cu, Pb, and P showed similar spatial distributions with significant pollution in commercial zones, suggesting vehicle traffic or commercial activities as dominant pollutant sources. Also, Cd, Co, Cr, Ni, Zn, Mn and Fe had the highest concentrations in industrial locations, signifying that industrial activities were the main sources of these seven metals. Moreover, the data highlighted land-use as a major influence on heavy metal concentrations and forms found in topsoils with large proportions of soil Cd, Co, Cr, and Ni found in residual fractions and soil Cu, Pb and Zn mainly as extractable fractions.     

Heavy Metals in Freshly Deposited Stream Sediments of Rivers Associated with Urbanisation of the Ganga Plain,India

Freshly deposited stream sediments from six urban centres of the Ganga Plain were collected and analysed for heavy metals to obtain a general scenery of sediment quality. The concentrations of heavy metals varied within a wide range for Cr (115–817), Mn (440–1 750), Fe (28 700–61 100), Co (11.7–29.0), Ni (35–538), Cu (33–1 204), Zn (90–1 974), Pb (14–856) and Cd (0.14–114.8) in mg kg^-1. Metal enrichment factors for the stream sediments were <1.5 for Mn, Fe and Co; 1.5–4.1 for Cr, Ni, Cu, Zn and Pb; and 34 for Cd. The anthropogenic source in metals concentrations contributes to 59% Cr, 49% Cu, 52% Zn, 51% Pb and 77% Cd. High positive correlation between concentrations of Cr/Ni, Cr/Cu, Cr/Zn, Ni/Zn, Ni/Cu, Cu/Zn, Cu/Cd, Cu/Pb, Fe/Co, Mn/Co, Zn/Cd, Zn/Pb and Cd/Pb indicate either their common urban origin or their common sink in the stream sediments. The binding capacity of selected metals to sediment carbon and sulphur decreases in order of Zn > Cu > Cr > Ni and Cu > Zn > Cr > Ni, respectively. Stream sediments from Lucknow, Kanpur, Delhi and Agra urban centres have been classified by the proposed Sediment Pollution Index as highly polluted to dangerous sediments. Heavy metal analysis in the <20-μm-fraction of stream sediments appears to be an adequate method for the environmental assessment of urbanisation activities on alluvial rivers. The present study reveals that urban centres act as sources of Cr, Ni, Cu, Zn, Pb and Cd and cause metallic sediment pollution in rivers of the Ganga Plain.     

Heavy Metal Fractionation and Extractability in Dredged Sediment Derived Surface Soils

The objective of this study was to characterise pollution with heavy metals in surface soils sampled at various dredged sediment disposal sites in the Flemish region (Belgium). The sites selected varied in the period since sediment disposal ceased and in current vegetation and land use. Total metal contents (Cd, Co, Cu, Fe, Mn, Ni, Pb, and Zn) in the surface soils varied widely. For some disposal sites Cd and Zn concentrations greatly exceeded reference values for clean soil. The distribution of the metals as determined by sequential extraction differed between elements, but was simular for all the soils. This suggested that metals in these sediment derived surface soils were accumulated and transformed in a similar way. Residual fractions were low compared to total contents (2 – 4% for Cd, 25% – 35% for Co, 7 – 18% for Mn, 4 – 22% for Zn, 12 – 41% for Ni, 11 – 42% for Pb, 20 – 45% for Cu, < 10% for Zn). High metal concentrations in the acid-extractable and reducible fractions may indicate pollution from anthropogenic sources. DTPA-extractable metals, which may be considered indicative of plant-available contents, were relatively high compared to the total contents. The relative extractability, expressed as the ratio of DTPA-extractable to total contents, decreased in the order Cd (38%) > Cu (28%) = Zn (26%) > Pb (13%) > Ni (10%) > Co (3%). Most of the sites studied would be of concern if they were used for agricultural activities. No trends in metal availability in the period following disposal were apparent from the data.     

贵州万山汞矿区某农田土壤重金属污染特征及来源解析

研究采集万山汞矿区典型农田土壤样品,分析测试其Hg、As、Cd、Cr、Pb、Cu、Zn、Ni含量,利用综合污染指数法、地累积指数法和潜在生态危害指数法评估农田土壤的污染状况及生态风险,结合相关分析和主成分分析解析农田土壤中重金属的来源。结果表明,该农田土壤Hg、As、Cd、Cr、Pb、Cu、Zn、Ni的平均含量分别为4.29、117.6、0.43、59.06、48.99、43.77、29.13、18.80 mg kg~(-1)。土壤重金属综合污染指数为7.16,表明该农田土壤重金属重度污染,其中100%的位点Hg、As重度污染,66.7%的位点Pb轻度污染,25%的位点Cd轻度污染。土壤重金属的综合潜在生态危害指数为469.0,生态风险强,Hg对综合潜在生态危害指数的贡献率为78.30%,是该农田土壤生态风险的主要来源。该农田中重金属的来源包括:交通运输源、矿业污染源、农业污染源和自然活动源,主要污染物Hg来源于矿业活动,As来源于交通运输和矿业活动,Cd来源于农业活动,Pb来源于交通运输。     

铁路交通对铁路旁土壤重金属污染的影响——以陇海铁路郑州—圃田段为例

以陇海铁路郑州-圃田段为例,在野外调查、采样和实验室分析的基础上,探讨了铁路交通对周围土壤N i、Pb、Cr、Zn、Cu和Cd六种重金属含量与分布的影响。结果表明,铁路南侧农田土壤六种重金属元素都出现不同程度的富集,最大含量均分布在距铁路路基30m的范围内,随着距离的增加,各重金属元素含量表现出不同的下降趋势。土壤各重金属污染程度的次序为:Zn>Pb>Cd>Cu>Cr>N i。土壤Pb和Zn污染最为严重,近路基处为重度污染,随着距路基距离的增加,由中度污染逐渐变为轻度污染。土壤N i和Cr虽不构成污染,但仍具有明显的铁路影响特征。在距路基10 m范围内为土壤重金属重度污染带,10~100 m范围内为中度污染带,100~500 m范围内为轻度污染带。