Heavy metals contents in agricultural topsoils in the Ebro basin (Spain). Application of the multivariate geoestatistical methods to study spatial variations

In this work the content of seven heavy metals (Cd, Cr, Cu, Hg, Ni, Pb and Zn) and other parameters (the pH, organic matter, carbonates and granulometric fraction) in agricultural topsoil in the Ebro basin are quantified, based on 624 samples collected according to an 8 by 8 km square mesh. The average concentrations (mg/kg) obtained were: Cd 0.415+/-0.163, Cr 20.27+/-13.21, Cu 17.33+/-14.97, Ni 20.50+/-22.71, Pb 17.54+/-10.41, Zn 17.53+/-24.19 and Hg 35.6+/-42.05 microg/kg. The concentration levels are relatively low in areas of high pH and low organic matter content concentration. The results of factor analysis group Cd, Cu, Hg, Pb and Zn in F1 and Cr y Ni in F2. The spatial heavy metals component maps based on geostatistical analysis, show definite association of these factors with the soil parent material. The local anomalies (found in Cu, Zn and Pb) are attributed to anthropogenic influence.     

Metals and arsenic in soils and corresponding vegetation at Central Elbe river floodplains (Germany)

Floodplain soils at the Elbe river are frequently polluted with metals and arsenic. High contents of these pollutants were detected down to subsoil layers. NH4NO3-extractable (phytoavailable) Cd, Ni, and Zn were elevated in horizons with high acidity. Among five common floodplain plant species, Artemisia vulgaris showed highest concentrations of Cd, Cu, and Hg, Alopecurus pratensis of As and Phalaris arundinacea of Ni, Pb, and Zn. Relationships were weak between metal concentrations in plants and phytoavailable stocks in soil. As and Hg uptake seems to be enhanced on long submerged soils. Enrichments of Cd and Hg are linked to a special plant community composition. Grassland herbage sampled in July/August revealed higher concentrations of As (+122%), Hg (+124%), and Pb (+3723%) than in May. To limit harmful transfers into the food chain, low-lying terraces and flood channels revealing highest contaminations or phytoavailabilities should be excluded from mowing and grazing.     

雷州半岛土壤重金属分布特征及其污染评价

在雷州半岛采集了106个土壤表层样品,分析了其中8种重金属元素(Cu、Pb、Zn、Cr、Ni、Cd、Hg和As)的全量.结果表明,雷州半岛土壤重金属污染由高到低排序为Ni＞Cr＞Hg＞Cu＞Zn＞Cd＞As＞Pb,Zn、Cd、As和Pb质量浓度均没有超标,Hg和Cu质量浓度超标率亦不高,但Ni和Cr平均质量浓度达49.81、87.13 mg/kg,高于国内外其他对照区域,超标率分别为25.47%和24.53%;重金属元素在雷州半岛各土壤利用类型中分布规律不明显,按4种主要土壤利用类型受重金属污染程度大小排序为甘蔗地＞果园土＞水田＞菜地;雷州半岛土壤综合污染指数总平均为0.970,土壤总体上尚清洁,重金属污染处于警戒水平;雷州半岛各区域中,徐闻、雷州两地土壤重金属质量浓度明显高于其他地区,其主要原因是徐闻、雷州两地成土母质主要为玄武岩,造成土壤Cr、Ni及其他重金属背景值较高.     

Relationship between heavy metals concentrations in egret species,their environment and food chain differences from two Headworks of Pakistan

Concentration of ten metals (Cd, Cr, Co, Cu, Fe, Li, Mn, Ni, Pb and Zn) were analyzed in the egg contents, prey and soil samples of little egret (Egretta garzetta) and cattle egret (Bubulcus ibis) from two Headworks to determine habitat and species-specific differences; to assess the importance of prey and habitat contamination as an exposure source for heavy metals. Concentration of Cu, Mn, Cr and Pb in egg contents, Fe, Co, Cu, Mn, Zn in prey and Fe, Co, Cu, Ni, Li in surface soils were significantly different (P < 0.05). Mean metal concentrations of Cr, Pb and Cd were relatively higher in little egret whereas Cu and Mn were higher in the egg contents of cattle egret. The mean concentrations of Cu, Mn and Zn were higher in prey samples of cattle egrets and Cr, Cd and Pb in prey samples of little egrets. In soil samples collected from little egret heronries metal concentrations were higher except Cu and Ni. Correlation Analysis and Hierarchical Agglomerative Cluster Analysis (HACA) identified relatively similar associations of metals and their source identification. Metals such as Fe, Cu, Mn, and Li were related with geochemical origin from parent rock material as well as anthropogenic input whereas Cr, Cd, Pb, Ni, Co and Zn were associated mostly with anthropogenic activities. The study suggested that eggs are useful bio-monitor of local heavy metal contamination.     

Evaluation of the anthropogenic influx of metal and metalloid contaminants into the Moulay Bousselham lagoon, Morocco, using chemometric methods coupled to geographical information systems

Superficial and cored sediment samples from the Moulay Bousselham lagoon and sub-watershed were analyzed for Al, Fe, Cu, Zn, Pb, Mn, Ni, Cr, As, Hg, and Cd. The temporal and spatial distributions of the main contamination sources of heavy metals were identified and described using chemometric and geographic information system (GIS) methods. Sediments from coastal lagoons near urban and agricultural areas are commonly contaminated with heavy metals, and the concentrations found in surface sediments are significantly higher than those from 50–100 years ago. The concentrations of these elements decrease sharply with depth in the sediment column, and the elements are preferentially enriched in the <2-μm-sized fraction of the sediment. The zones of enhanced risk of heavy metals were detected by means of GIS-based geostatistical modeling. According to sediment pollution indices and statistical analysis, heavy metals (Pb, Cu, Ni, Zn, Cr, and Hg) that pose a risk have become largely enriched in the lagoon sediments during the recent period of agricultural intensification.     

Health risk assessment of heavy metals in soil-plant system amended with biogas slurry in Taihu basin,China

Biogas slurry is a product of anaerobic digestion of manure that has been widely used as a soil fertilizer. Although the use for soil fertilizer is a cost-effective solution, it has been found that repeated use of biogas slurry that contains high heavy metal contents can cause pollution to the soil-plant system and risk to human health. The objective of this study was to investigate effects of biogas slurry on the soil-plant system and the human health. We analyzed the heavy metal concentrations (including As, Pb, Cu, Zn, Cr and Cd) in 106 soil samples and 58 plant samples in a farmland amended with biogas slurry in Taihu basin, China. Based on the test results, we assessed the potential human health risk when biogas slurry containing heavy metals was used as a soil fertilizer. The test results indicated that the Cd and Pb concentrations in soils exceeded the contamination limits and Cd exhibited the highest soil-to-root migration potential. Among the 11 plants analyzed, Kalimeris indica had the highest heavy metal absorption capacity. The leafy vegetables showed higher uptake of heavy metals than non-leafy vegetables. The non-carcinogenic risks mainly resulted from As, Pb, Cd, Cu and Zn through plant ingestion exposure. The integrated carcinogenic risks were associated with Cr, As and Cd in which Cr showed the highest risk while Cd showed the lowest risk. Among all the heavy metals analyzed, As and Cd appeared to have a lifetime health threat, which thus should be attenuated during production of biogas slurry to mitigate the heavy metal contamination.     

Comprehensive assessment of toxic metals in urban and suburban street deposited sediments (SDSs) in the biggest metropolitan area of China

A set of toxic metals, i.e. As, Hg, Pb, Cd, Cu, Zn, Ni and Cr, in urban and suburban SDSs were investigated comparatively in the biggest metropolitan area of China, Shanghai. Results showed that all of the metals except As were accumulated greatly, much higher than background values. Geo-accumulation index indicated that metal contamination in urban SDSs was generally heavier than that in suburban SDSs. Potential ecological risk index demonstrated that overall risks caused by metals were considerable. Cd contributed 52% to the overall risk. Multivariate statistical analysis revealed that in urban SDSs, Zn, Ni, Cd, Pb, Cu and Cr were related to traffic and industry; coal combustion led to elevated levels of Hg; soil parent materials controlled As contents. In suburban SDSs, Pb, Cu, As and Cd largely originated from traffic pollution; Zn, Ni and Cr were associated with industrial contaminants; Hg was mainly from domestic solid waste.     

Assessing heavy metal sources in agricultural soils of an European Mediterranean area by multivariate analysis

According to the European Thematic Strategy for Soil Protection, the characterization of the content and source of heavy metals in soils are necessary to establish quality standards on a regional level that allow the detection of sampling sites affected by pollution. In relation to this, the surface horizons of 54 agricultural soils under vegetable crops in the Alicante province (Spain), a representative area of the European Mediterranean region, were sampled to determine the content of Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn. Analytical determinations were performed by atomic absorption spectroscopy after microwave sample digestion in acid solution. Results indicated that heavy metal levels were similar to those reported by authors working on agricultural soils from other parts of the Mediterranean region, with the exception of Cu and Pb in some samples. Multivariate analysis (principal component analysis and cluster analysis) was performed to identify a common source for heavy metals. Moreover, soil properties were determined in order to characterize agricultural soils and to analyze relationships between heavy metal contents and soil properties. The content of Co, Cr, Fe, Mn, Ni and Zn were associated with parent rocks and corresponded to the first principal component called the lithogenic component. A significant correlation was found between lithogenic metals and some soil properties such as soil organic matter, clay content, and carbonates, indicating an important interaction among them. On the other hand, elements such as Cd, Cu and Pb were related to anthropic activities and comprised the second (Cu and Pb) and third principal components (Cd), designated the anthropogenic components. Generally, Cd, Cu and Pb showed a lower correlation with soil properties due to the fact that they remain in available forms in these agricultural soils. Taking into account these results and other achieved in other parts of the European Mediterranean region, it can be concluded that soil quality standards are highly needed to declare soils affected by human induced pollution. This is particularly relevant for anthropogenic metals (Cd, Cu and Pb, and in some areas also Zn). Further research in other agricultural areas of the region would improve the basis for proposing such soil quality standards.     

Assessing heavy metal pollution in the surface soils of a region that had undergone three decades of intense industrialization and urbanization

Heavy metals in the surface soils from lands of six different use types in one of the world’s most densely populated regions, which is also a major global manufacturing base, were analyzed to assess the impact of urbanization and industrialization on soil pollution. A total of 227 surface soil samples were collected and analyzed for major heavy metals (As, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb, and Zn) by using microwave-assisted acid digestion and inductively coupled plasma–mass spectrometry (ICP-MS). Multivariate analysis combined with enrichment factors showed that surface soils from the region (>7.2?×?10⁴ km²) had mean Cd, Cu, Zn, and As concentrations that were over two times higher than the background values, with Cd, Cu, and Zn clearly contributed by anthropogenic sources. Soil pollution by Pb was more widespread than the other heavy metals, which was contributed mostly by anthropogenic sources. The results also indicate that Mn, Co, Fe, Cr, and Ni in the surface soils were primarily derived from lithogenic sources, while Hg and As contents in the surface soils were controlled by both natural and anthropogenic sources. The pollution level and potential ecological risk of the surface soils both decreased in the order of: urban areas?>?waste disposal/treatment sites?～?industrial areas?>?agricultural lands?～?forest lands?>?water source protection areas. These results indicate the significant need for the development of pollution prevention and reduction strategies to reduce heavy metal pollution for regions undergoing fast industrialization and urbanization.     

Heavy Metals in Urban Soils of East St. Louis,IL, Part I: Total Concentration of Heavy Metals in Soils

ABSTRACT

The city of East St. Louis, IL, has a history of abundant industrial activities including smelters of ferrous and non-ferrous metals, a coal-fired power plant, companies that produce organic and inorganic chemicals, and petroleum refineries. A protocol for soil analysis was developed to produce sufficient information on the extent of heavy metal contamination in East St. Louis soils. Soil cores representing every borough of East St. Louis were analyzed for heavy metals—As, Cd, Cu, Cr, Hg, Ni, Pb, Sb, Sn, and Zn. The topsoil contained heavy metal concentrations as high as 12.5 ppm Cd, 14,400 ppm Cu, ppm quantities of Hg, 1860 ppm Pb, 40 ppm Sb, 1130 ppm Sn, and 10,360 ppm Zn. Concentrations of Sb, Cu, and Cd were well correlated with Zn concentrations, suggesting a similar primary industrial source. In a sandy loam soil from a vacated rail depot near the bank of the Mississippi River, the metals were evenly distributed down to a 38-cm depth. The clay soils within a half-mile downwind of the Zn smelter and Cu products company contained elevated Cd (81 ppm), Cu (340 ppm), Pb (700 ppm), and Zn (6000 ppm) and displayed a systematic drop in concentration of these metals with depth. This study demonstrates the often high concentration of heavy metals heterogeneously distributed in the soil and provides baseline data for continuing studies of heavy metal soil leachability.     

Use of sequential extraction to assess metal partitioning in soils

The state of heavy metal pollution and the mobility of Cd, Cu, Ni, Cr, Pb and Zn were studied in three texturally different agricultural soil profiles near a Cu-Ni smelter in Harjavalta, Finland. The pseudo-total concentrations were determined by an aqua regia procedure. Metals were also determined after division into four fractions by sequential extraction with (1) acetic acid (exchangeable and specifically adsorbed metals), (2) a reducing agent (bound to Fe/Mn hydroxides), (3) an oxidizing agent (bound to soil organic matter) and (4) aqua regia (bound to mineral structures). Fallout from the smelter has increased the concentrations of Cd, Cu and Ni in the topsoil, where 75-90% of Cd, 49-72% of Cu and 22-52% of Ni occurred in the first two fractions. Slight Pb and Zn pollution was evident as well. High proportions of mobile Cd, Cu and Ni also deeper in the sandy soil, closest to the smelter, indicated some downward movement of metals. The hydroxide-bound fraction of Pb dominated in almost all soils and horizons, while Ni, Cr and Zn mostly occurred in mineral structures. Aqua regia extraction is usefully supplemented with sequential extraction, particularly in less polluted soils and in soils that exhibit substantial textural differences within the profiles.     

Landscape ecology of the Guanting Reservoir, Beijing, China: multivariate and geostatistical analyses of metals in soils

Surface soil samples were collected from 52 sites around Guanting Reservoir in Beijing, China, and contents of 'total' metals (Cu, Zn, Pb, Cd, As, Ni and Cr) were determined. The results indicate that the degree of heavy metal pollution in the soils declines in the order of Cd>Cr>Zn>As>Cu>Ni>Pb. Based on the results of a combination of multivariate statistics and geostatiscal analyses, it was concluded that land application of phosphate fertilizer, wastewater and sludge were the primary sources of Cd and Zn in soils. Whereas As, Cu, Cr and Ni in some soils were due to natural rock weathering. The sources of Pb in soils only partially originated from land application of phosphate fertilizer, but mainly from vehicle exhaust. The greatest concentrations of all metals, except for Pb, were found in Huailai County and the towns of Yanghedaqiao and Guanting.     

Heavy metals incidence in the application of inorganic fertilizers and pesticides to rice farming soils

The concentrations of Cd, Co, Cu, Ni, Pb, Zn, Fe and Mn in different inorganic fertilizers (urea, calcium superphosphate, iron sulphate and copper sulphate) and in pesticides (two herbicides and one fungicide) are evaluated together with the contribution of these metals in soils from their use. The study was made in rice farming areas to the north of Albufera Natural Park (Valencia, Spain). The results obtained show that superphosphate is the fertilizer that contains the highest concentrations of Cd, Co, Cu and Zn as impurities. Copper sulphate and iron sulphate have the most significant concentrations of Pb, and are the only fertilizers in which Ni was detected. The three pesticides analysed show similar Cd contents and the highest levels of Fe, Mn, Zn, Pb and Ni are found in the herbicides. The most significant additions of heavy metals as impurities that soil receives from agricultural practices, are Mn, Zn, Co and Pb. Three contamination indexes have been applied to provide a basis for comparison of potential heavy metal toxicity. These results denote the potential toxicity of heavy metals in the studied soils.     

Heavy metals in urban soils of East St. Louis, IL, Part I: Total concentration of heavy metals in soils

The city of East St. Louis, IL, has a history of abundant industrial activities including smelters of ferrous and non-ferrous metals, a coal-fired power plant, companies that produce organic and inorganic chemicals, and petroleum refineries. A protocol for soil analysis was developed to produce sufficient information on the extent of heavy metal contamination in East St. Louis soils. Soil cores representing every borough of East St. Louis were analyzed for heavy metals--As, Cd, Cu, Cr, Hg, Ni, Pb, Sb, Sn, and Zn. The topsoil contained heavy metal concentrations as high as 12.5 ppm Cd, 14,400 ppm Cu, ppm quantities of Hg, 1860 ppm Pb, 40 ppm Sb, 1130 ppm Sn, and 10,360 ppm Zn. Concentrations of Sb, Cu, and Cd were well correlated with Zn concentrations, suggesting a similar primary industrial source. In a sandy loam soil from a vacated rail depot near the bank of the Mississippi River, the metals were evenly distributed down to a 38-cm depth. The clay soils within a half-mile downwind of the Zn smelter and Cu products company contained elevated Cd (81 ppm), Cu (340 ppm), Pb (700 ppm), and Zn (6000 ppm) and displayed a systematic drop in concentration of these metals with depth. This study demonstrates the often high concentration of heavy metals heterogeneously distributed in the soil and provides baseline data for continuing studies of heavy metal soil leachability.     

Geostatistical Assessment of the Impact of World War I on the Spatial Occurrence of Soil Heavy Metals

Previous research showed a regional Cu enrichment of 6 mg kg⁻¹ in the top soil of the Ypres war zone (Belgium), caused by corrosion of WWI shell fragments. Further research was required since in addition to Cu, also As, Pb, and Zn were used during the manufacturing of ammunition. Therefore, an additional data collection was conducted in which the initial Cu data set was tripled to 731 data points and extended to eight heavy metals (As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn) which permitted (1) to evaluate the environmental impact of the heavy metals at a regional scale and (2) to assess their regional spatial occurrence by performing an optimized geostatistical modeling. The results showed no pollution at a regional scale, but sometimes locally concentrations exceeded the soil sanitation threshold, especially for Cu, Pb, and Zn. The spatial patterns of Ni and Cr were related to variations in soil texture whereas the occurrences of Cu and Pb were clearly linked to WWI activities. This difference in spatial behavior was confirmed by an analysis of coregionalization.     

焦化废水处理过程外排污泥中重金属形态特征及其潜在环境风险

焦化废水处理过程所排放污泥中重金属的含量及化学形态是否构成环境风险将直接影响污泥处置方法的选择,为此,实验采用BCR顺序提取法分析了焦化废水处理站外排污泥中重金属(Cd、Hg、Pb、Cr、As、Ni、Zn、Cu和Mn)的形态特征,并采用地累积指数(Igeo)和潜在生态危害指数(RI)评价了重金属对土壤的潜在环境风险。研究结果表明:除Ni主要以可氧化态存在外,焦化废水外排污泥中其他几种重金属元素主要存在于残渣态,重金属元素的含量低于《城镇污水处理厂污染物排放标准(GB18918—2002)》中的控制限值;与城市污泥相比,焦化废水外排污泥具有低Pb、Cr、Zn、Cu含量,而高Cd、Hg、Mn含量的特点;基于Igeo和RI的评价结果,Cd和Hg是外排污泥中具有一定环境风险的元素,需要考虑其下游去向。焦化废水处理外排污泥中主要存在残渣态重金属成分,不表现为很高的环境风险,其处置应重点考虑其中有机污染物特别是POPs。     

Ecological risks and potential sources of heavy metals in agricultural soils from Huanghuai Plain, China

A total of 224 agricultural soil samples from Huanghuai Plain in China were investigated for the concentrations of seven heavy metals (As, Cd, Cr, Hg, Ni, Pb, and Zn). The mean concentrations of the metals were 12, 0.17, 79, 0.04, 35, 25, and 74 mg/kg, respectively. These values are similar or slightly higher than background values in this region, except for Cd with a mean nearly twice the background value. The estimated ecological risks based on contamination factors and potential ecological risk indexes are also mostly low, but considerable for Cd and Hg. Multivariate analysis (including Pearson's correlation analysis, hierarchical cluster analysis, and principal component analysis) clearly revealed three distinct metal groups, i.e., Cr/Ni/Zn, As/Cd/Pb, and Hg, whose concentrations were closely associated with the distribution and pollution characteristics of industries in and around the plain. The main anthropogenic sources for the three metal groups were identified as atmospheric deposition, sewage irrigation/fertilizers usage, and atmospheric deposition/irrigation water, respectively. The present results are well suited for planning, risk assessment, and decision making by environmental managers of this region.     

Heavy metal pollution in China: Origin,pattern and control

GOAL, SCOPE AND BACKGROUND: Heavy metal is among one of the pollutants, which cause severe threats to humans and the environment in China. The aim of the present review is to make information on the source of heavy metal pollution, distribution of heavy metals in the environment, and measures of pollution control accessible internationally, which are mostly published in Chinese. METHODS: Information from scientific journals, university journals and governmental releases are compiled focusing mainly on Cd, Cu, Pb and Zn. Partly Al, As, Cr, Fe, Hg, Mn and Ni a included also in part as well. RESULTS AND DISCUSSION: In soil, the average contents of Cd, Cu, Pb and Zn are 0.097, 22.6, 26.0 and 74.2 mg/kg, respectively. In the water of the Yangtze River Basin, the concentrations of Cd, Cu, Pb and Zn are 0.080, 7.91, 15.7 and 18.7 microg/L, respectively. In reference to human activities, the heavy metal pollution comes from three sources: industrial emission, wastewater and solid waste. The environment such as soil, water and air were polluted by heavy metals in some cases. The contents of Cd, Cu, Pb and Zn even reach 3.16, 99.3, 84.1 and 147 mg/kg, respectively, in the soils of a wastewater irrigation zone. These contaminants pollute drinking water and food, and threaten human health. Some diseases resulting from pollution of geological and environmental origin, were observed with long-term and non-reversible effects. CONCLUSIONS: In China, the geological background level of heavy metal is low, but with the activity of humans, soil, water, air, and plants are polluted by heavy metals in some cases and even affect human health through the food chain. RECOMMENDATIONS AND OUTLOOK: To remediate and improve environmental quality is a long strategy for the polluted area to keep humans and animals healthy. Phytoremediation would be an effective technique to remediate the heavy metal pollutions.     

Annual input fluxes of heavy metals in agricultural soil of Hainan Island,China

The accumulation of heavy metals in farmland has become an important issue related to food security and environmental risk. The annual inputs of heavy metals (As, Cd, Hg, Pb, Cr, Cu, and Zn) to agricultural soil for a full year in Hainan Island have been studied. Three fluxes through the cultivated horizon were considered: (1) atmospheric depositions, (2) fertilization, and (3) irrigation water. The corresponding samples were collected and analyzed on a large regional scale. The total input fluxes show obvious spatial variability among different regions. The inventory of heavy metal inputs to agricultural land demonstrates that agricultural soil is potentially at risk of heavy metal accumulation from irrigation water. The potential at risk of heavy metal accumulation from atmospheric deposition and fertilizer is relatively low compared to irrigation. The results indicate that Hg is the element of prior concern for agricultural soil, followed by Cd and As, and other heavy metal elements represent little threat to the environment in the study area. This work provides baseline information to develop policies to control and reduce toxic elements accumulated in agricultural soil.