Survey of heavy metal pollution and assessment of agricultural soil in Yangzhong district, Jiangsu Province, China

We investigated concentrations of Hg, Cd, Pb, Zn, Cu, As, Ni, and Cr in samples of soil, cereal, and vegetables from Yangzhong district, China. Compared to subsoils, the sampled topsoils are enriched in Hg, Cd, Cu, Pb, Zn, and As. High levels of Cd and Hg are observed in most agricultural soils. Concentrations of Cr and Ni show little spatial variation, and high Cu, Pb, and Zn contents correspond well to areas of urban development. High As contents are primarily recorded at the two ends of the sampled alluvion. The contents of Cd, Hg, and total organic carbon (TOC) increase gradually to maximum values in the upper parts of soil profiles, while Cr and Ni occur in low concentrations within sampled profiles. As, Pb, Cu, and Zn show patterns of slight enrichment within the surface layer. Compared to data obtained in 1990, Cd and Hg show increased concentrations in 2005; this is attributed to the long-term use of agrochemicals. Cr and Ni contents remained steady over this interval because they are derived from the weathering of parent material and subsequent pedogenesis. The measured As, Cu, Pb, and Zn contents show slight increases over time due to atmospheric deposition of material sourced from urban anthropogenic activity. Low concentrations of heavy metals are recorded in vegetables and cereals because the subalkaline environment of the soil limits their mobility. Although the heavy metal concentrations measured in this study do not pose a serious health risk, they do affect the quality of agricultural products.     

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。     

巢湖表层沉积物中重金属的分布特征及其污染评价

以巢湖表层沉积物为研究对象,利用BCR连续提取法研究了沉积物中Cr、Co、Ni、Cu、Cd、Zn、V和Pb等8种重金属元素的分布特征,同时运用潜在风险指数法和地累积指数法综合评价了巢湖沉积物中重金属的生态风险。结果表明,巢湖沉积物中的重金属含量在空间上表现出东西高、中间低的分布特征。巢湖表层沉积物中Cr、Co、Ni、V和Cu 5种重金属都主要以残渣态为主,Zn和Cd主要以弱酸提取态为主,Pb以可还原态为主,同时,Co和Cu 2种元素的可交换态及可还原态含量占有较高比例,具有潜在危害性。相关性分析显示,Cr、Cu、Pb、Ni、Zn和Cd 6种重金属元素的来源和分布可能具有相似性,Co和V 2种重金属元素具有相似的地球化学行为且其主要来源可能与其他几种重金属不同。潜在生态风险指数评价结果表明,巢湖表层沉积物中8种重金属元素构成的生态危害顺序为:Cd>Pb>Co>Cu>Ni>Zn>V>Cr,Cd具有高的生态危害等级,其他7种重金属元素均为低生态危害等级。地累积指数法评价结果表明:巢湖沉积物重金属元素的富集程度为Cd>Zn>Pb>Co>Cu>V>Ni>Cr,Cr属于清洁级别,Co、Cu、V和Ni处于轻度污染水平,Zn和Pb处于偏中度污染,Cd达到了重污染水平。     

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.     

Assessment and potential sources of metals in the surface sediments of the Yellow River Delta,Eastern China

The Yellow River Delta is the most intact estuary wetland in China and suffers from great pressure of metals. Seventy-seven surface sediment samples were collected in the delta, and contents of Cu, Pb, Cd, Cr, Zn, Ni, and Mn were analyzed by inductively coupled plasma spectrometry and those of Hg and As by atomic fluorescence spectrometry. The results showed that means of metal contents (ppm, dry weight) were as follows: Hg, 0.04; Cr, 61.72; Cu, 20.97; Zn, 60.73; As, 9.47; Pb, 21.91; Cd, 0.12; Ni, 27.24; and Mn, 540.48. 43.8% of Hg and 14.3% of Cd were from the allogenic source while others from the authigenic source. The results of the geoaccumulation indexes appeared that 6.5% of sites from the estuarine and the Gudao areas were moderately polluted by Hg. All ecological risk index values of Hg and 37.7% of Cd were more than 40, which were the main factors of strongly and moderately potential ecological risks of 37.7% of sites in the delta. High Cd contents may be due to the alkaline conditions of the delta and the unreasonable management of the farmland, while the abnormal distribution of Hg to the wet or dry deposition and the erosion of the seawater. It was suggested to monitor Hg content in the atmosphere of the Yellow River Delta. The results were expected to update the pollution status of metals in the delta and created awareness of preserving the sound condition of the Yellow River Delta.     

Heavy metals in sediments,soils, and aquatic plants from a secondary anabranch of the three gorges reservoir region,China

We investigated the occurrence of cadmium (Cd), copper (Cu), chromium (Cr), nickel (Ni), lead (Pb), Znic (Zn), iron (Fe), manganese (Mn), and magnesium (Mg) in sediments, as well as in related soils and aquatic plants in the Liangtan River, a typical secondary anabranch of the Yangtze River in the Three Gorges Reservoir Region (TGRR) of China. We found that sediments accumulated more metals than soils and aquatic plants. Concentrations of the nine metals in sediments and soils followed the same sequence, while their concentrations in aquatic plants followed a different sequence. Potential adverse effects of contaminated sediments on benthic fauna were evaluated, and the results showed that the toxic effect on benthic organisms followed the sequence Zn?>?Ni?>?Cr?>?Cu?>?Cd?>?Pb. The potential ecological risk index analysis indicated that Cd in sediments had considerable ecological risk, whereas Cr, Cu, Zn, Ni, and Pb had low ecological risk. The potential ecological risk index (RI) of the heavy metals in sediments of the Liangtan River was 174.9, indicating moderate ecological risk. The transfer factor trend of metals for aquatic plants showed that Cd and Ni had the most and least accumulation, respectively. For Cu, Cd, Mg, Pb, and Cr, a significant positive correlation of the metal concentrations was observed between sediments and soils, but no correlations (excluding Cr) were detected between sediments and aquatic plants. Our study indicated that anthropogenic input may be the primary source of metal contamination in the Liangtan River, and that Zn and Cd pollution in the Liangtan River should be further explored.     

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.     

Source identification and risk assessment of heavy metal contaminations in urban soils of Changsha,a mine-impacted city in Southern China

The urban soils suffered seriously from heavy metal pollutions with rapid industrialization and urbanization in China. In this study, 54 urban soil samples were collected from Changsha, a mine-impacted city located in Southern China. The concentrations of heavy metals (As, Cd, Co, Cu, Mn, Ni, Pb, and Zn) were determined by ICP-MS. The pollution sources of heavy metals were discriminated and identified by the combination of multivariate statistical and geostatistical methods. Four main sources were identified according to the results of hierarchical cluster analysis (HCA), principal component analysis (PCA), and spatial distribution patterns. Co and Mn were primarily derived from soil parent material. Cu, Pb, and Zn with significant positive relationships were associated with mining activities and traffic emissions. Cd and Ni might be affected by commercial activities and industrial discharges. As isolated into a single group was considered to have correlation with coal combustion and waste incineration. Risk assessment of heavy metals in urban soils indicated an overall moderate potential ecological risk in the urban region of Changsha.     

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.     

Highway increases concentrations of toxic metals in giant panda habitat

The Qinling panda subspecies (Ailuropoda melanoleuca qinlingensis) is highly endangered with fewer than 350 individuals inhabiting the Qinling Mountains. Previous studies have indicated that giant pandas are exposed to heavy metals, and a possible source is vehicle emission. The concentrations of Cu, Zn, Mn, Pb, Cr, Ni, Cd, Hg, and As in soil samples collected from sites along a major highway bisecting the panda’s habitat were analyzed to investigate whether the highway was an important source of metal contamination. There were 11 sites along a 30-km stretch of the 108th National Highway, and at each site, soil samples were taken at four distances from the highway (0, 50, 100, and 300 m) and at three soil depths (0, 5, 10 cm). Concentrations of all metals except As exceeded background levels, and concentrations of Cu, Zn, Mn, Pb, and Cd decreased significantly with increasing distance from the highway. Geo-accumulation index indicated that topsoil next to the highway was moderately contaminated with Pb and Zn, whereas topsoil up to 300 m away from the highway was extremely contaminated with Cd. The potential ecological risk index demonstrated that this area was in a high degree of ecological hazards, which were also due to serious Cd contamination. And, the hazard quotient indicated that Cd, Pb, and Mn especially Cd could pose the health risk to giant pandas. Multivariate analyses demonstrated that the highway was the main source of Cd, Pb, and Zn and also put some influence on Mn. The study has confirmed that traffic does contaminate roadside soils and poses a potential threat to the health of pandas. This should not be ignored when the conservation and management of pandas is considered.     

Potentially toxic metal contamination of urban soils and roadside dust in Shanghai, China

A detailed investigation was conducted to understand the contamination characteristics of a selected set of potentially toxic metals in Shanghai. The amount of Pb, Zn, Cu, Cr, Cd and Ni were determined from 273 soil/dust samples collected within urban area. The results indicated that concentration of all metals except Ni in soils was significant, and metal pollution was even severer in roadside dust. A series of metal spatial distribution maps were created through geostatistical analysis, and the pollution hotspots tended to associate with city core area, major road junctions, and the regions close to industrial zones. In attempt of identifying the source of metals through geostatistical and multivariate statistical analyses, it was concluded as follows: Pb, Zn and Cu mainly originated from traffic contaminants; soil Ni was associated with natural concentration; Cd largely came from point-sourced industrial pollution; and Cr, Ni in dust were mainly related to atmospheric deposition.     

中国商品有机肥重金属分析

测定了来自10个地区不同生产原料的118个商品有机肥样品的重金属含量.结果表明:(1)商品有机肥样品中的Cd、Hg、Pb、Cr、As、Zn、Cu、Ni的平均值分别为0.600、0.120、7.34、84.30、9.45、202.91、91.06、11.01 mg/kg.(2)河南、湖北、上海的商品有机肥中8种重金属平均值均较高;内蒙古的商品有机肥中Cr平均值为20.32 mg/kg,广西的商品有机肥中Zn平均值为51.36mg/kg,远低于所有样品中Cr和Zn平均值.(3)以猪粪为主要生产原料的商品有机肥中重金属平均值最高.(4)Cr超过中国商品有机肥重金属限量标准、欧盟生态标志法的重金属限量标准、加拿大堆肥重金属限量标准(A级)和加拿大堆肥重金属限量标准(B级);As、Cd超过中国商品有机肥重金属限量标准、欧盟生态标志法的重金属限量标准和加拿大堆肥重金属限量标准(A级);Cu、Zn超过欧盟生态标志法的重金属限量标准和加拿大堆肥重金属限量标准(A级);Hg超过加拿大堆肥重金属限量标准(A级);Pb超过中国商品有机肥重金属限量标准;Ni均未超标.     

Bioaccessibility and health risk of arsenic, mercury and other metals in urban street dusts from a mega-city, Nanjing, China

The oral bioaccessibility and the human health risks of As, Hg and other metals (Cu, Pb, Zn, Ni, Co, Cd, Cr, Mn, V and Fe) in urban street dusts from different land use districts in Nanjing (a mega-city), China were investigated. Both the total contents and the oral bioaccessibility estimated by the Simple Bioaccessibility Extraction Test (SBET) of the studied elements varied with street dusts from different land use districts. Cd, Zn, Mn, Pb, Hg and As showed high bioaccessibility. SBET-extractable contents of elements were significantly correlated with their total contents and the dust properties (pH, organic matter contents). The carcinogenic risk probability for As and Cr to children and adults were under the acceptable level (<1 × 10⁻⁴). Hazard Quotient values for single elements and Hazard Index values for all studied elements suggested potential non-carcinogenic health risk to children, but not to adults.     

Metal contamination and solid phase partitioning of metals in urban roadside sediments

This study was undertaken to assess the anthropogenic impact on metal concentrations of urban roadside sediments (N = 633) in Seoul city, Korea and to estimate the potential mobility of selected metals (Zn, Cu, Pb, Cr, Ni, and Cd) using sequential extraction. Comparison of metal concentrations in roadside sediments with mean background values in sediments collected from first- or second-order streams in Korea shows that Zn, Cu and Pb are most affected by anthropogenic inputs. The 206Pb/207Pb ratios of roadside sediments (range = 1.1419-1.1681; mean 1.1576 +/- 0.0068) suggest that Pb is mainly derived from industrial sources rather than from leaded gasoline. A five-step sequential extraction of roadside sediments showed that Zn, Cd and to a lesser degree Ni occur predominantly in the carbonate bound fraction, while Pb is highest in the reducible fraction, Cu in the organic fraction, and Cr in the residual fraction. It was found that the concentrations in the readily available exchangeable fraction were generally low for most metals examined, except for Ni whose exchangeable fraction was appreciable (average 15.2%). Considering the proportion of metals bound to the exchangeable and carbonate fractions, the comparative mobility of metals probably decreases in the order of Zn > Ni > Cd > Pb > Cu > Cr. As potential changes of redox state and pH may remobilize the metals bound to carbonates, reducible, and/or organic matter, and may release and flush them through drain networks into streams, careful monitoring of environmental conditions appears to be very important. With respect to ecotoxicity, it is apparent the Zn and Cu pollution is of particular concern in Seoul city.     

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.     

Occurrence,speciation, and risks of trace metals in soils of greenhouse vegetable production from the vicinity of industrial areas in the Yangtze River Delta,China

The effect of industrial activities on trace metals in farmland of rapidly industrializing regions in developing countries has increasingly been a concern to the public. Here, soils were collected from 13 greenhouse vegetable production (GVP) farms or bases near industrial areas in the Yangtze River Delta of China to investigate the occurrence, speciation, and risks of Cr, Cu, Zn, Cd, Ni, and Pb in GVP soil. The results revealed that the main metal elements causing GVP soil pollution were Cd, Zn, Ni, and Cu, of which contamination levels were generally unpolluted to moderately polluted. Zinc pollution was mainly attributed to heavy fertilization, while Cd, Ni, and Cu pollution may be greatly ascribed to industrial effluents and coal combustion. Metal speciation studies showed that most of Cr, Ni, Cu, and Zn was present in residual fraction while more than half of Cd and Pb was present in non-residual fractions. Additionally, pollution of Cd, Cu, Ni, and Zn in GVP soil increased their corresponding mobile fractions. Risk assessment using potential ecological risk index and risk assessment code showed that Cd was the major risk contributor. Specifically, Cd generally posed moderate or considerable ecological risk as well as displayed medium or high mobility risk in GVP soil. Thus, great attention should be paid to the contribution of both industrial discharges and intensive farming to soil pollution by trace metals, especially Cd, because of its high mobility risk.

     

Ecological risk assessment of heavy metals in sediment and human health risk assessment of heavy metals in fishes in the middle and lower reaches of the Yangtze River basin

The concentrations of heavy metals (Cr, Cd, Hg, Cu, Zn, Pb and As) in the water, sediment, and fish were investigated in the middle and lower reaches of the Yangtze River, China. Potential ecological risk analysis of sediment heavy metal concentrations indicated that six sites in the middle reach, half of the sites in the lower reach, and two sites in lakes, posed moderate or considerable ecological risk. Health risk analysis of individual heavy metals in fish tissue indicated safe levels for the general population and for fisherman but, in combination, there was a possible risk in terms of total target hazard quotients. Correlation analysis and PCA found that heavy metals (Hg, Cd, Pb, Cr, Cu, and Zn) may be mainly derived from metal processing, electroplating industries, industrial wastewater, and domestic sewage. Hg may also originate from coal combustion. Significant positive correlations between TN and As were observed.     

Accumulation of potentially toxic elements in plants and their transfer to human food chain

Abstract

Contaminated soils can be a source for crop plants of such elements like As, Cd, Cr, Cu, Ni, Pb, and Zn. The excessive transfer of As, Cu, Ni, and Zn to the food chain is controlled by a “soil‐plant barrier”; however, for some elements, including Cd, the soil‐plant barrier fails. The level of Cd ingested by average person in USA is about 12 μg/day, which is relatively low comparing to Risk Reference Dose (70 μg Cd/day) established by USEPA. Food of plant origin is a main source of Cd intake by modern society. Fish and shellfish may be a dominant dietary sources of Hg for some human populations. About half of human Pb intake is through food, of which more than half originates from plants. Dietary intake of Cd and Pb may be increased by application of sludges on cropland with already high levels of these metals. Soils amended with sludges in the USA will be permitted (by USEPA‐503 regulations) to accumulate Cr, Cd, Cu, Pb, Hg, Ni, and Se, and Zn to levels from 10 to 100 times the present baseline concentrations. These levels are very permissive by international standards. Because of the limited supply of toxicity data obtained from metals applied in sewage sludge, predictions as to the new regulations will protect crop plants from metal toxicities, and food chain from contamination, are difficult to make.     

Temporal and spatial variation in C, N, S and trace element contents in the leaves of Quercus ilex within the urban area of Naples

This paper presents a comparative analysis of the concentrations of C, N and S and several trace elements (Fe, Mn, Na, Zn, Cu, V, Pb, Ni, Cr, Cd) in leaves of Quercus ilex, an evergreen oak, collected in the urban area of Naples in 1989 and 1996. The samplings were carried out from 25 urban sites (roads with different traffic flows as well as urban and suburban parks) and from two remote areas as controls. Relative to 1989, the values measured in 1996 denote a strong decrement of S, Fe, Na, Pb, and Cr, with the exception of S in control sites. By contrast, C, N and Cd contents were higher in 1996 than in 1989. Cu and Ni showed a conspicuous increment in control sites as well as in urban sites facing the sea and in the parks, while in all the other urban sites these elements decreased remarkably. No significant difference was found in the leaf contents of Mn, Zn and V measured in 1989 relative to 1996. Both in 1989 and 1996 the contents of N, S, Fe, Na, Cu, Pb, V, Ni, Cr and Cd were significantly higher in leaves from urban sites than in the controls, reflecting the high degree of contamination of the urban area. Concentration factors expressed as the ratio of road/control values for most of the elements were still very high in leaves collected in 1996, though remarkably lower than in 1989.