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1.
Soils of loamy sand on weathered, sandy dolomite were cored from six holes up to 70 ft beneath a municipal waste landfill in central Pennsylvania. Mn, Fe, Ni, Co, Cu, Zn, Cd, Pb, and Ag were determined in exchangeable and non-exchangeable forms in total and < 15 μm soil samples. Most of these metals were bound in Mn oxides, non-exchangeable with 0.5 M CaCl2. The Mn oxides (often X-ray amorphous) identified when crystalline as todorokite occurred chiefly as coatings on quartz grains.Somewhat higher amounts of acid leachable trace metals were found in the < 15 μm size fraction than in the total soil samples; however, trace metal/Mn ratios were similar in both. In general, the initial mild soil leaching, which dissolved chiefly Mn oxides, gave MnFeX>Co>Ni>Pb>Zn> Cu>Cd>Ag. The final leaching, which dissolved chiefly ferric oxides, gave Fe>Mn>Ni>Zn>Co> Cu>Pb>Cd>Ag. Samples taken from an unpolluted site and from the same soils affected for seven years by leachate from the refuse had similar metal contents.Soil extractable Co, Ni, Cu, and Zn could be predicted from the Mn extracted. Based in part on factor analysis of the data, Mn-rich oxides had at least tenfold higher heavy metal percentages than Fe-rich oxides (crystalline component goethite), reflecting their greater coprecipitation potential. Because of this potential and because of the generally higher solubility of Mn than Fe oxides, more heavy metals may be released from Mn-rich than from Fe-rich soils by disposal of organic-bearing wastes. However, leaching of the moisture-unsaturated soils in situ is rarely severe enough to completely dissolve both Mn and Fe oxides. Based on the Mn content, Cd, Cu, and Pb were depleted in soil moisture beneath the landfill relative to their amounts in the soil. This depletion may reflect factors including heterogeneity in metal content of the soil oxides; preferential resorption of these metals; and removal of the Cd, Cu, and Pb as organic precipitates or as inorganic precipitates such as carbonates.  相似文献   

2.
In the present study we examined the Ba, Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn contamination levels of the soils of Berehove, a small city in West-Ukraine. As a first step we determined the spatial distribution of the heavy metal contents of the urban soils; then, by studying the land use structure of the city and by statistical analysis we identified the major sources of contamination; we established a matrix of correlations between the heavy metal contents of the soils and the different types of land use; and finally, we drew a conclusion regarding the possible origin(s) of these heavy metals. By means of multivariate statistical analysis we established that of the investigated metals, Ba, Cd, Cu, Pb and Zn accumulated in the city’s soils primarily as a result of anthropogenic activity. In the most polluted urban areas (i.e. in the industrial zones and along the roads and highways with heavy traffic), in the case of several metals (Ba, Cd, Cu, Pb, Zn) we measured concentration levels even two or three times higher than the threshold limit values. Furthermore, Cr, Fe and Ni are primarily of lithogenic origin; therefore, the soil concentrations of these heavy metals depend mainly on the chemical composition of the soil-forming rocks.  相似文献   

3.
浙北地区土壤元素有效量及其影响因素研究   总被引：7，自引：0，他引：7       下载免费PDF全文
浙江省北部地区调查研究表明,受成土母质来源、土壤类型及其理化性质等因素的影响,土壤元素全量、有效量及其有效度表现为:1)低山丘陵岗地土壤中As,Cd,Mo,Pb和Se全量较高,As,Cd,Fe,Pb,Se和Zn有效量较高;而山前平原区土壤中Hg,Pb和Zn元素全量较高,由地表向深部的下降递度较小,显示为原始沉积成因特点。2)中酸性、富含有机质的红壤和水稻土中As,Cd,Cu,Fe,Mn,Pb,Se,Zn等元素有效度较高,水稻土Hg有效度最低;弱碱性或碱性、贫有机质的潮土和滨海盐砂土中As,Cd,Cu,Fe,Mn,Pb,Se,Zn等元素有效量较低,但B有效量及有效度均较高。3)统计分析表明,土壤中Mn,Cu,Zn,Mo,Cd,Pb,Se等元素全量与有效量间具显著正相关性,表明全量是有效量的重要影响控制因素;有机质含量与Fe,Cu,Zn,Cd,As和Pb有效度间为显著正相关,说明有机质较高有利于土壤元素活化;Fe,Cu,Zn,Cd,As,Pb和Se有效度与pH值为显著负相关,表明土壤酸性增强(酸化)会增加这类元素的生物有效性。  相似文献   

4.
In the old mining area of Rodalquilar, mine wastes, soil and sediments were characterized and the results revealed high concentration of Au, Ag, As, Bi, Cu, Fe, Mn, Pb, Se, Sb and Zn in tailings and sediments. The contaminant of greatest environmental concern is As. The mean concentration in the tailings was 679.9, and 345 mg/kg in the sediments of Playazo creek. The groundwater samples from the alluvial aquifer showed high concentration of Al, As, Cd, Fe, Hg, Mn, Ni, Pb, Se, Sb and Zn and very high concentration of chloride and sulfate, which were above the concentration defined in the European standards for drinking water. The presence of As in groundwater may be caused by the oxidation of arsenian pyrite, the possible As desorption from goethite and ferrihydrite and the jarosite dissolution. Groundwater concentrations of Cd, Fe, Mn, and possibly Cu, were associated with low values of Eh, indicating the possible dissolution of oxy-hydroxides of Fe and Mn. The mobility of metals in the column experiments show the release of Al, Fe, Mn, Cr, Cu, Ni, V and Zn in significant concentrations but below the detected values in groundwater. However, As, Cd, Sb, Se Pb and Au, are generally mobilized in concentrations above the detected values in groundwater. The possible mass transfer processes that could explain the presence of the contaminants in the aquifer and the leachates was simulated with the PHREEQC numerical code and revealed the possible dissolution of the following mineral phases: jarosite, natrojarosite, arsenian pyrite, alunite, chlorite, kaolinite and calcite.  相似文献   

5.
Selenium and heavy metals content in some Mediterranean soils   总被引：1，自引：0，他引：1  
The study of metal contents in industrial, agricultural or/and polluted soils compared with natural or unpolluted soils is currently necessary to obtain reference values and to assess soil contamination. Nonetheless, very few works published appear in international journals on elements like Se, Li and Sr in Spanish soils. This study determines the total levels of Se, Li, Sr, As, Cd, Co, Cr, Cu, Ni, Pb, V, Zn, Fe, Mn and Ba in 14 natural (unpolluted) soils (Gypsisols, Leptosols, Arenosols and Acrisols), 14 agricultural soils (Anthrosols, Fluvisols and Luvisols), and 4 industrial–urban affected-surface soil horizons (Anthrosols and Fluvisols) of Eastern Spain. The geochemical baseline concentrations (GBC) and reference values (RV) have been established, and the relationships among elements and also between soil properties and elemental concentrations have been analysed. The RV obtained in this study were (mg kg−1): Se 2.68, Li 115, Sr 298, Cd 0.97, Co 35, Cr 217, Cu 46, Ni 50, Pb 137, V 120, Zn 246, Fe 124,472, Mn 2691, and Ba 743. The RV for Se and Li were used as a preliminary approach to assess soil contamination in Spanish soils. The results confirm human impact on Sr, As, Cd, Cr, Cu, Ni, Pb and Zn soil concentrations, but evidence no deviation from natural Se, Li, Co, V, Fe, Mn and Ba concentrations. The results obtained from the statistical analysis reveal significant correlations between some elements and clay and soil organic matter (SOM) contents, indicating that metal concentrations are controlled by soil composition. One particularly interesting finding is the high correlation coefficients obtained between SOM and Se, Cd, Cr, V, Fe, and Mn, and between clay and Cd, Zn, V, Fe and Mn. Once again, these facts confirm the role of SOM and clay minerals in soil functions and that soil is an ecosystem element responsible for maintaining environmental quality.  相似文献   

6.
The contamination of soils by metals from various sources is a subject of increasing concern in recent times. Twenty-eight elements (Fe, Ti, Cr, Al, Ga, Pb, Sc, Ba, Li, Cd, Be, Co, Cu, Mn, Ni, V, Zn, Mo, Pt, Pd, Au, As, Sb, Se, Hg, Bi, Ag and Sn) have been analyzed from urban topsoil from the city of Xuzhou. The concentrations of these analyzed elements have been correlated to some soil parameters such as organic matter, pH, cation exchange capacity, carbonate content, and granulometric fractions (clay, silt and sand). Results of the statistical analysis show a large variety and complexity in these relationships. The spatial distributions of these metal concentrations were also constructed using geographical information system. The spatial distribution patterns of the elements analyzed show that traffic and industrial activities are the principal anthropogenic pollutant sources.  相似文献   

7.
通过采集南宁市郊农田中玉米、蔬菜、水稻可食部分及其根系土150组,研究重金属元素在不同土壤-农作物系统中迁移特征及其影响因素,结果表明:根系土中Hg、Cd、Cr、Cu、Ni、Pb、Zn平均含量分别为0.116、0.202、56.76、22.12、14.49、25.18和56.28 mg·kg-1。农作物对应平均含量分别为0.001 1、0.037、0.054、1.153、0.205、0.011和9.37 mg·kg-1。根系土富集因子表明Cd受到不同程度人为活动影响,Cr和Ni主要受地质背景控制;不同作物系统元素富集因子表明Pb在土壤-农作物系统中迁移能力最低,Zn迁移能力最强。Cd、Cr、Cu、Ni、Pb和Zn在土壤-水稻系统重迁移能力显著高于蔬菜和玉米。根系土中pH、CaO、有机质、Fe2O3、K2O、MgO与重金生物富集系数呈显著性负相关,但在土壤-叶类蔬菜系统中根系土中K2O、MgO与Hg生物富集系数呈显著正相关。   相似文献   

8.
Total concentrations of chemical elements in soils may not be enough to understand the mobility and bioavailability of the elements. It is important to characterise the degree of association of chemical elements in different physical and chemical phases of soil. Another geochemical characterisation methodology is to apply sequential selective chemical extraction techniques. A seven-step sequential extraction procedure was used to investigate the mobility and retention behaviour of Al, Fe, Mn, Cu, Zn, Pb, Cr, Co, Ni, Mo, Cd, Bi, Sn, W, Ag, As and U in specific physical–chemical and mineral phases in mine tailings and soils in the surroundings of the abandoned Ervedosa mine. The soil geochemical data show anomalies associated with mineralised veins or influenced by mining. Beyond the tailings, the highest recorded concentrations for most elements are in soils situated in mineralised areas or under the influence of tailings. The application of principal components analysis allowed recognition of (a) element associations according to their geochemical behaviour and (b) distinction between samples representing local geochemical background and samples representing contamination. Some metal cations (Mn, Cd, Cu, Zn, Co, Cr, Ni) showed important enrichment in the most mobilisable and bioavailable (i.e., water-soluble and exchangeable) fractions due likely to the acidic conditions in the area. In contrast, oxy-anions such as Mo and As showed lower mobility because of adsorption to Fe oxy-hydroxides. The residual fraction comprised largest proportions of Sn and Al and to a lesser extent Zn, Pb, Ni, Cr, Bi, W, and Ag, which are also present at low concentrations in the bioavailable fractions. The elements in secondary mineral phases (mainly Fe, Mn, Cu, Zn, Cd, Pb, W, Bi, Mo, Cr, Ni, Co, As and U) as well as in organic matter and sulphides are temporarily withheld, suggesting that they may be released to the environment by changes in physico-chemical conditions.  相似文献   

9.
固体聚合膜电解浓集法是浓缩氚含量较低(1 Bq/m~3)的天然水样的常用方法,但因水样自身含有杂质离子或电解装置聚合膜带入杂质进入浓集液,使浓集液偏酸性,在测量过程中易产生化学淬灭效应,导致氚的测量值偏低。本文研究了水样自身存在的杂质离子和聚合膜上残留的杂质离子、样品溶液的pH值及其电导率所产生的化学淬灭效应的影响,实验表明,为减少化学淬灭效应,提高测量低含量氚的准确性,需保证水样溶液呈中性,电导率≤1μS/cm,同时避免杂质沉积在聚合膜上。如果水样溶液的pH值偏酸性、电导率大于1μS/cm,可采用酸碱混合型离子交换树脂去除水样中自身的杂质;对于聚合膜引入的杂质,可在电解后的水样中加入微量氨水将其pH值调节至中性。  相似文献   

10.
为了解包头市典型工业企业对其所在地土壤中重金属含量的影响及污染现状,利用相关性系数对其表层土壤中7种重金属(Cu、Zn、Pb、Cr、Cd、Mn、Ni)来源进行研究,并采用内梅罗综合污染指数法和潜在生态危害指数对其污染状况进行评价。结果表明,7种重金属含量平均值均高于内蒙古土壤背景值,其中Cd、Mn、Ni超标率已达100%,而Cu、Pb、Zn的超标率分别为97%、93%和93%,只有Cr超标率较低(53%),污染程度依次为CdPbCuNiZnMnCr,其中Pb和Cd为重度污染,Cu、Zn、Ni为中度污染,Cr、Mn为轻度污染;Cu、Zn、Cr、Mn、Ni可能同时来自工业生产和交通运输两个源,而Pb和Cd除上述来源外,燃煤烟气的排放有较大贡献。潜在生态危害依次为CdPbCuNiCrZnMn,其中Cd的潜在生态风险最大,应予以高度重视,其他金属的风险均为轻微。  相似文献   

11.
The concentrations of metals (Cd, Pb, Ni, Cr, Cu, Fe, Mn and Zn) were determined in soils under different land use types in an urban environment in order to study the impact of land uses on the concentrations of metals in the soils. The mean concentration range of metals for all land use types were 42.1 to 410, 11.2 to 118.2, 4388.2 to 31891.1, 9.7 to 65.4, 0.1 to 1.8, 4.7 to 35.2, 2.0 to 16.8 and 77.9 to 881.7 mg/kg, for Mn, Pb, Fe, Cu, Cd, Cr, Ni and Zn, respectively. The computed multiple pollution index (MPI) indicated that 67 % of the examined sites had MPI values between 1 and 20 i.e. at the pollution range, while 33 % of sites had MPI values of zero which indicated that these sites were not polluted with the studied metals. Zinc had the highest impact on the multiple pollution index values. Three main principal components were identified from the principal component analysis which include (i) Cu, Zn, Pb, Cr and Ni originating from both industrial and agricultural sources, and as well as automobile exhausts; (ii) Fe and Mn which originated from both natural and anthropogenic sources; (iii) Cd which its anthropogenic origin is different from components I and II. This study provided information on the sources of metals in the urban environment and extent of contamination associated with each land use, which are useful in the ranking of contaminated sites, environmental quality management, environmental forensic studies and guidance for remediation/redevelopment of contaminated land.  相似文献   

12.
研究雄安地区土壤重金属和砷元素空间分布特征及其来源,对于支撑新区土地资源和环境管理具有重要意义。基于雄安新区土壤环境调查,运用地统计学方法和ArcGIS 技术分析模拟了土壤中As、Hg、Cd、Cu、Pb、Zn、Ni、Cr等8种元素空间分布特征,综合运用空间分析、多元统计学方法和正定因子矩阵模型解析这些元素的主要来源。结果表明:（1）区内土壤质量总体良好,4.35 %的土壤样品Cd和Cu含量超过农用地土壤污染风险筛选值,但均低于农用地土壤污染风险管控值;与河北省背景值相比,Cd、Cu、Pb、Zn和Hg存在不同程度中度和显著富集。（2）As、Cd、Cu、Pb、Zn、Ni、Cr含量呈现出由北部向南部逐渐增高的趋势,高值区主要分布在新区西南部;Hg元素分布分散,高值区主要分布在城镇及工业企业周边。（3）不同土地利用类型土壤剖面重金属和砷元素垂向分布受pH值、有机碳和铁铝氧化物等理化性质影响显著。（4）研究区土壤重金属和砷元素富集受人类活动影响明显,人为来源贡献率达67.12 %,Hg元素主要来源于人为排放的大气沉降富集,As元素富集受到废渣堆放和利用的影响,Cd、Cu、Pb和Zn元素富集受工业生产、污水灌溉以及尾气排放等活动影响。研究成果可为雄安新区合理制定土地资源开发利用和生态保护措施提供技术支撑。  相似文献   

13.
This study analyzed the concentrations and chemical forms of Zn,Cu,Pb,Sb,Cd and Mn in airborne particles,road dusts and soils collected along three expressways in Jiangxi Province,China,with different traffic densities,and identified the levels and sources of heavy metal contamination.The concentrations of Zn,Cu,Pb,Sb,and Cd except Mn in airborne particles,road dusts and soils were all in direct proportion to traffic volume.Cd concentrations were low compared with other metals.For instance,the concentrations of Zn,Cu,Pb,Sb,Mn and Cd were 6.6,0.7,2.2,0.1,0.1 and 0.1μg·m-3in PM10along the Changjiu Expressway,792.8,241.4,248.3,9.6,340.5and 8.0 mg·kg-1in road dusts,and 201.1,143.2,59.5,9.5,338.9 and 2.3 mg·kg-1in soils,respectively,but in the case of the ratio of concentration to the environmental background value,most serious contamination was caused by Cd.The sources of the heavy metals were judged by comparisons of the chemical forms of the heavy metals in different environmental media.Pb and Mn in airborne particles were both derived from traffic;Pb in road dusts and soils resulted mainly from the use of leaded gasoline in the past;and Mn in road dusts and soils was derived from parent rocks.Zn,Cu,Sb and Cd in airborne particles,road dusts and soils were derived primarily from traffic,and differences in chemical forms of the heavy metals in different media were due to the interaction between heavy metals in airborne particles and organic matter and other surfaces in road dusts and soils.We also discussed the change of chemical forms of heavy metals in particles of different sizes and under different weather conditions.Bioavailability of heavy metals in airborne particles was much higher than that in road dusts and soils,especially Pb(0.676 in airborne particles,0.159 in road dusts and 0.095 in soils).  相似文献   

14.
The behaviour of trace elements (Al, As, Cd, Co, Cr,Cu, Fe, Mn, Ni, V, Zn) was studied in five humus-richstreams (dissolved organic carbon = 14–40 mg/L)impacted by acid sulphate soils developed in marinesulphide-bearing fine-grained sediments. During heavyrainfalls in autumn, on which the study focusses, themetals Al, Cd, Co, Cu, Mn, Ni and Zn are extensivelyleached from these acidic soils (pH = 2.5–4.5), whileAs, Cr, Fe and V are not leached more strongly fromthis soil type than from areas of till and peat. Aspeciation experiment, based on anion and cationexchange of the stream waters in the field, showedthat (1) the metals Al, Cd, Co, Mn, Ni and Zn aretransported in the streams mainly as inorganiccations, (2) Cu exists mainly in cationic form but isalso to a significant extent associated with dissolvedhumic substances, (3) Fe occurs mainly in the anionicfraction explained by organic coating on colloidal Feoxyhydoxides and (4) the hydrochemistry of As, Cr andV is complex as these elements may exist in severalunquantified anionic fractions and to a minor extentin cationic species/forms. Whereas the proportion ofacid sulphate soils in the catchments had a largeimpact on concentrations levels of several elements inthe stream waters, these soils did not have a largeaffect on the speciation of elements in water.  相似文献   

15.
首钢地区表层土壤重金属的分布特征及污染评价   总被引：2，自引：0，他引：2  
韩鹏  孙天河  袁国礼  黄勇 《现代地质》2012,26(5):963-971
利用多元统计分析和空间分析相结合的方法,分析了首钢地区表层土壤中Fe、Cr、Ni、V、As、Cd、Pb、Cu、Zn、Hg 10种重金属元素的地球化学特征。研究结果表明,10种元素可以归结为4类:第一类Ni、V、As的含量低于自然背景值,主要受成土母质等自然因素的影响;第二类Cd、Cu、Pb、Zn的含量已经超出自然背景值,其中Cu、Pb、Zn属于轻度污染,Cd属于中度污染,这一类元素主要受到交通和冶炼等人为因素的影响,高值区主要分布于居民区;第三类为Fe、Cr,同时受到自然因素和人为因素的共同影响,高值区集中分布在厂区和部分居民区;第四类为Hg,Hg因其是一种非点源污染的元素而单独聚为一类,主要受到人为因素的影响且高值样点位于河流区。总体而言,首钢地区表层土壤已经受到部分污染,需密切关注其对环境的危害及人群的潜在健康风险。本研究对该区域土壤污染风险评价和土地利用规划等具有一定的借鉴意义。  相似文献   

16.
Fine sludges were collected from five filtration plants, and the partitioning of ten metals (Ag, Cd, Mn, Zn, Pb, Cu, Sn, Co, Ni, and Fe) in them was determined by selective leaching techniques. (1) The available amounts, which shows the total of each metal leached between 1 M CH3COONH4 and 30 percent H2O2, for Ag, Cd and Mn, ranged from 51 to 98 percent for five sludges. (2) The available amounts for Zn, Pb, Cu, and Sn were 47–92 percent for five sludges. (3) The most important fraction for Co, Ni, and Fe, except the Inagawa sludge, which is markedly polluted by organic matter, was the crystalline particle. Therefore, the above metals, except Co, Ni, and Fe, are thought to be enriched on ion-exchangeable sites, organic matter, hydrous Fe/Mn oxides, and sulfides in fine sludges.  相似文献   

17.
A good understanding of roadside soil contamination and the location of pollution sources is important for addressing many environmental problems. The results are reported here of an analysis of the content of metals in roadside dust samples of four major highways in the Greater Toronto area (GTA) in Ontario, Canada. The metals analyzed are Pb, Zn, Cd, Ni, Cr, Cu, Mn, and Fe. Multivariate geostatistical analysis [correlation analysis (CA), principal component analysis (PCA), and hierarchical cluster analysis (HCA)] were used to estimate soil chemical content variability. The correlation coefficient shows a positive correlation between Cr–Cd, Mn–Fe, and Fe–Cu, while negatively between Zn–Cd, Mn–Cd, Zn-Cr, Pb–Zn, and Ni–Zn. PCA shows that the three eigenvalues are less than one, and suggests that the contamination sources are processing industries and traffic. HCA classifies heavy metals in two major groups. The cluster has two larger subgroups: the first contains only the variables Fe, Mn, Cu, Cr, Ni, and Pb, and the second includes Cd and Zn. The geostatistical analysis allows geological and anthropogenic causes of variations in the contents of roadside dust heavy metals to be separated and common pollution sources to be identified. The study shows that the high concentration of traffic flows, the parent material mineralogical and chemical composition, and land use are the main sources for the heavy metal concentration in the analyzed samples.  相似文献   

18.
The Pliocene aquifer receives inflow of Miocene and Pleistocene aquifer waters in Wadi El Natrun depression. The aquifer also receives inflow from the agricultural activity and septic tanks. Nine sediment samples were collected from the Pliocene aquifer in Wadi E1 Natrun. Heavy metal (Cu, Sr, Zn, Mn, Fe, Al, Ba, Cr, Ni, V, Cd, Co, Mo, and Pb) concentrations of Pliocene aquifer sediments were investigated in bulk, sand, and mud fractions. The determination of extractable trace metals (Cu, Zn, Fe, Mn, and Pb) in Pliocene aquifer sediments using sequential extraction procedure (four steps) has been performed in order to study environmental pathways (e.g., mobility of metals, bounding states). These employ a series of successively stronger chemical leaching reagents which nominally target the different compositional fractions. By analyzing the liquid leachates and the residual solid components, it is possible to determine not only the type and concentration of metals retained in each phase but also their potential ecological significance. Cu, Sr, Zn, Mn, Fe, and Al concentrations are higher in finer sediments than in coarser sediments, while Ba, Cr, Ni, V, Cd, Co, Mo, and Pb are enriched in the coarser fraction. The differences in relative concentrations are attributed to intense anthropogenic inputs from different sources. Heavy metal concentrations are higher than global average concentrations in sandstone, USEPA guidelines, and other local and international aquifer sediments. The order of trace elements in the bulk Pliocene aquifer sediments, from high to low concentrations, is Fe?>?Al?>?Mn?>?Cr?>?Zn?>?Cu?>?Ni?>?V?>?Sr?>?Ba?>?Pb?>?Mo?>?Cd?>?Co. The Pliocene aquifer sediments are highly contaminated for most toxic metals, except Pb and Co which have moderate contamination. The active soluble (F0) and exchangeable (F1) phases are represented by high concentrations of Cu, Zn, Fe, and Mn and relatively higher concentrations of Pb and Cd. This may be due to the increase of silt and clay fractions (mud) in sediments, which act as an adsorbent, retaining metals through ion exchange and other processes. The order of mobility of heavy metals in this phase is found to be Pb?>?Cd?>?Zn?>?Cu?>?Fe?>?Mn. The values of the active phase of most heavy metals are relatively high, indicating that Pliocene sediments are potentially a major sink for heavy metals characterized by high mobility and bioavailability. Fe–Mn oxyhydroxide phase is the most important fraction among labile fractions and represents 22% for Cd, 20% for Fe, 11% for Zn, 8% for Cu, 5% for Pb, and 3% for Mn. The organic matter-bound fraction contains 80% of Mn, 72% of Cu, 68% of Zn, 60% of Fe, 35% of Pb, and 30% of Cd (as mean). Summarizing the sequential extraction, a very good immobilization of the heavy metals by the organic matter-bound fraction is followed by the carbonate-exchangeable-bound fraction. The mobility of the Cd metal in the active and Fe–Mn oxyhydroxide phases is the highest, while the Mn metal had the lowest mobility.  相似文献   

19.
Industrialization, urbanization, and agricultural practices are 3 of the most important sources of metal accumulations in soils. Concentrations of Cr, Mn, Ni, Cu, Pb, Zn and Cd were determined in surface soils collected under different land uses, including urban (UR), industrial (IN-1 and IN-2), agricultural (AG), abandoned unused (AB), and natural (NA) sites to examine the influence of anthropogenic activities on metals in soils formed in a typical Mediterranean environment. The highest concentrations of Cr, Cd, and Pb observed in the NW industrial area (IN-2) were 63.7, 3.34 and 2330 mg metal kg−1 soil, for each metal, respectively. The SW industrial area (IN-1) contained the highest Zn content at 135 mg kg−1. However, soils with the highest concentrations of Ni and Cu were located in AG sites at 30.9 and 64.9 mg kg−1 soil, respectively. Sampling locations with the highest concentrations of Mn were identified in AB sites. Using the concentrations of metals at the NA sites as the baseline levels, soils collected from all other land uses in the study area exhibited significantly higher total contents of Zn, Mn, Cr and Ni. Metal enrichment was attributed to fertilizer and pesticide applications, industrial activities, and metal deposition from a high volume of vehicular traffic (for Pb and Cd). High concentrations of Mn in some samples were attributed to parent materials. The study demonstrated that anthropogenic activities associated with various land uses contribute to metal accumulation in soils and indicated a need to closely monitor land management practices to reduce human and ecological risks from environmental pollution.  相似文献   

20.
Due to the rapid urbanization and industrialization that has occurred in China over the last few decades, metals have been continuously emitted into the urban environment and now pose a serious threat to human health. Indeed, there is a growing concern over the potential for pollution of urban soils with heavy metals. Therefore, an extensive soil survey was conducted in urban areas of Changchun, China, to evaluate the current status of heavy metal contamination in soils and to evaluate its potential sources. A total of 352 samples of urban soils were collected from urban areas of Changchun using a systematic sampling strategy in which one sample per km2 was taken (0 ~ 20 cm). The levels of Cu, Pb, Zn and the major elements (Mn, Al2O3, CaO, Fe2O3, MgO, SiO2, K2O and NaO) were then determined by X-Ray fluorescence spectrometry (XRF), while the level of Cd was determined by graphite furnace atomic absorption spectrometry (GF-AAS), and the Hg and As concentrations were determined by atomic fluorescence spectroscopy (AFS). The results indicated that, when compared with the background values of topsoil in the Changchun region, the topsoil in urban areas were enriched with metals, particularly Cu, Cd, Zn, Pb and Hg. The results of correlation coefficient analysis showed that Hg, As, Cd, Cu, Pb and Zn were significantly positive correlated with each other, while Cr and Mn formed another group. Moreover, significantly positive correlations were observed between pH and Zn, Pb, Cu, Cd, As and Hg, indicating that pH influences the distributions of these metals in urban soils in Changchun. Principal component analysis (PCA) was conducted to identify sources of heavy metals and the results revealed distinctly different associations among the trace metals and the major elements in the urban soils. The concentration of Cr appeared to be controlled by the parent material (natural sources), while Cu, Pb and Zn were mainly from vehicle emissions, with Zn primarily coming from vehicle tires. Additionally, Hg and As primarily originated from coal combustion, while Cd was mainly associated with industrial sources. According to the pollution index (PI) of each metal, the overall levels of metal pollution were not especially high, but there were clearly contaminated sites concentrated in the central and northeast portion of the studied region. The Nemerow integrated pollution index (NIPI) of the seven metals also indicated that urban soils in Changchun city were classified as having low level of pollution.  相似文献   

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