Multivariate geostatistical analysis of soil contaminations

Soil is one of the most endangered compartments of our environment. The input of pollutants into the soil caused by industrial production, agriculture, and other human activities is a problem of high relevance. A contour analysis of soil contamination is the first step to characterize the size and magnitude of pollution and to detect emission sources of heavy metals. The evaluation and assessment of the large number of measured samples and pollutants require the use of efficient statistical methods which are able to discover both spatial and multivariate relationships. The evaluation of the presented case study – soil contamination by heavy metals – is carried out by means of multivariate geostatistical methods, also described as theory of linear coregionalization. Multivariate geostatistics connects the advantages of common geostatistical methods (spatial correlation) and multivariate data analysis (multivariate relationships). In the given case study of soil pollution by heavy metal emissions it is excellently possible to detect multivariate spatial correlations between different heavy metals in the soil and to determine their common emission sources. These emission sources are located in the area under investigation. Received: 2 October 1997 / Revised: 22 January 1998 / Accepted: 27 January 1998     

西南山地煤矿区耕地土壤-农作物重金属富集及健康风险评价

为了解西南某典型山地煤矿区周边农田土壤、农作物重金属的富集情况及对当地人群健康的影响程度,采集矿区周边农田土壤样品和对应的农作物样品,测定重金属Cr、Mn、Zn、As、Pb的含量。运用Nemero指数法、潜在风险指数法对土壤重金属的污染程度进行评价;采用靶标危害系数法(THQ)评价农作物重金属对人体的健康风险。结果显示,Cr、Mn、Zn、As、Pb分别是背景值的1.81、1.90、2.89、1.30、0.86倍,处于轻度污染级别,轻微危害程度。农作物重金属Cr、Pb和As含量的超标情况较严重,Zn的含量超标相对较小。各农作物富集的重金属对人体的健康风险大小为：高粱>玉米>白菜>葱>辣椒。农作物重金属对儿童健康的危害均达到了慢性中毒;对成人健康的影响,高粱处于慢性中毒,其它农作物重金属处于产生较大影响的危害程度。农作物重金属与土壤重金属的相关性分析表明,农作物重金属的含量与土壤重金属全量并无线性关系;各重金属在农作物中的转移能力不同;Pb,As在农作物中的转移能力较大,而Cr相对较小。鉴于矿区重金属的富集情况,应尽快采取修复治理措施,为保证当地人群健康,建议当地居民不再食用和种植富集重金属严重的高粱、玉米农作物。     

Analytical investigations and chemometrical characterization of polluted soils

Summary Soil samples were taken in the surroundings of an industrial plant with heavy metal emission. A convenient digestion method for the determination of the mobile anthropogenic part of the heavy metal contents of soils was selected. This heavy metal contents were determined by atomic absorption spectrometry. The application of different multivariate statistical methods such as cluster analysis, multi-dimensional variance and discriminant analysis and factor analysis enables the objective characterization of polluted areas and of the degree of pollution as well as the identification of emission sources.     

Evaluation of Platanus occidentalis and Pinus sylvestris as bioindicators for lead and cadmium by slurry sampling-electrothermal atomic absorption spectrometry

Two higher plants (Platanus occidentalis and Pinus sylvestris) were used as bioindicators for assessment of contamination by Pb and Cd in an urban and industrialized area. Both toxic metals in plant tissue were determined by transverse-heated electrothermal atomic absorption spectrometry-longitudinal Zeeman background correction combined with automated ultrasonic slurry sampling. Twenty sampling points were established to observe a relationship between metal concentration in plant and traffic density. Screening optimization of variables influencing slurry preparations (sonication time, sonication power, and surfactant concentration) followed a fractional factorial design at 2 levels. No significant effects were observed in the interval of variables studied. Limits of detection of Pb and Cd in the plants were 0.28 and 0.025 microg/g (dry weight), respectively. Metal concentrations in the plants were in the range of 5-51 and 0.05-0.7 microg/g for Pb and Cd, respectively. Factor analysis to data of metal concentration in both plants, extractable metal content in soil, distance to traffic, and traffic density, showed a significant association between features such as concentration of Pb and Cd in leaves of P. occidentalis and traffic density, which accounted for the largest variance. Other features such as extractable metal contents in soil accounted for lesser variance, meaning that soils in the area investigated were less suitable than plants for monitoring metal pollution caused by vehicular traffic.     

Multivariate statistical assessment of polluted soils

This study deals with the application of several multivariate statistical methods (cluster analysis, principal components analysis, multiple regression on absolute principal components scores) for assessment of soil pollution by heavy metals. The sampling was performed in a heavily polluted region and the chemometric analysis revealed four latent factors, which describe 84.5 % of the total variance of the system, responsible for the data structure. These factors, whose identity was proved also by cluster analysis, were conditionally named “ore specific”, “metal industrial”, “cement industrial”, and “steel production” factors. Further, the contribution of each identified factor to the total pollution of the soil by each metal pollutant in consideration was determined.     

Diagnosis of lung cancer based on metal contents in serum and hair using multivariate statistical methods

The classification of normal and cancer groups with four multivariate methods according to metal contents in serum and hair samples has been discussed in the present paper. Results show that the four multivariate methods, stepwise discrimination analysis, principal components analysis, hierarchical cluster analysis, and stepwise cluster analysis can distinguish the two groups correctly. The independent samples of both normal and cancer groups were tested and can be distinguished correctly by the four methods. Therefore, these methods can be used as an aid for diagnosis of lung cancer according to the metal contents in serum and hair samples.     

土壤重金属污染来源及其解析研究进展

土壤重金属污染问题是环境和土壤科学研究者关注的热点问题。对土壤重金属污染物来源的鉴别是准确、有效控制和治理污染源的前提。根据近年来国内外对土壤重金属污染的相关研究报道,综述了土壤中污染物的工业、农业和交通因子三大主要来源,重点阐述了目前解析土壤重金属污染来源所运用的化学形态研究、剖面分布、同位素示踪、空间分析和多元统计等方法,并就存在的问题和今后的研究重点进行了总结。     

某冶炼厂周边土壤重金属污染评价分析及源解析研究

有色金属矿产资源采选冶活动造成的土壤重金属污染已成为严重的环境问题。采用电感耦合等离子体质谱法和光谱法测定某冶炼厂周边不同区域内土壤中重金属Cu、Pb、Zn、As、Ni、Cr、Cd、Hg元素含量,采用Kriging空间插值方法对重金属空间分布特征进行分析,采用内梅罗指数法对其污染状况进行评价,采用多元统计分析对重金属元素的污染源进行分析。结果表明,研究区土壤采样点80%处于污染状态,且以重度污染为主,污染比较严重的区域受风向影响在冶炼厂的西部和南部方向,污染严重的重金属元素为Cu、Pb、Cd、Zn和As,土壤中各重金属元素的污染源除来自于冶炼厂外,Zn-Cd-PbCu-As、Ni-Cr、Hg分别还受到机动车辆排放、自然因素、燃煤及农药使用的影响。     

Nuclear and related analytical methods applied to the determination of Cr, Ni, Cu, Zn, Cd and Pb in a red ferralitic soil and Sorghum samples

Several studies on the influence of heavy metals to the growth of vegetables have been carried out in Cuba by the Ministry of Agriculture in order to evaluate the effects resulting of the continuous application of fertilizers and other materials to the soils. The analysis of metal contents in soil and vegetable samples is often troublesome due to the low concentration levels to be determined. In the the present work EDXRF, AAS and ASV methods were applied and compared for the evaluation of Cr, Ni, Cu, Zn, Cd and Pb contents in red ferralitic soil and Sorghum samples. Several certified reference materials (CRM) (inorganic and organic matrixes) were analyzed in order to evaluate the performance of the analytical procedures and the bias and precision of the results. A study was performed with growing Sorghum in several series of pots where different quantities of metals were added to the soil substrate. The observed correlation between the metal contents in soil and plants as well as the influence of different additions of each metal on the plant growth is also presented.     

青海达坂山地区高山植物中重金属元素分布特征

分析了青海达坂山地区16种高山植物重金属元素含量。结果表明，9种重金属元素中Cr、Ni、CO3种含量高于陆生植物的正常含量值；Hg含量极少，在检测限以下；其余5种含量正常；同种元素含量种间差异不大，不同植物对于同种元素的累积比较均一，各种植物对As、Se、Sb3种元素的富集能力高于其它元素；植物中CO与Cr、Sb；Pb与Cd之间有很好的协同作用，而Se与Co、Cd、Sb有明显的拈抗作用。相关分析的结果表明，植物对重金属元素的吸收受土壤元素含量的影响。     

Heavy metals in river sediments — A chemometrical evaluation

First results are presented to support decisions within projects of recultivation in the Merseburg region. From two places of the river Luppe eight sediment samples were taken at four different days. The total concentrations of Cd, Cr, Cu, Fe, Mn, Ni, Pb, and Zn were determined by ICP-AES after digestion with aqua regia both in the gross samples and in four particle size fractions obtained by wet sieving. Subsequently each fraction was split into six classes by a sequential extraction to characterise the pattern of heavy metal binding form. Questions about the difference of the regions, the importance of the particle size fractions, the mobility of the metals, and the influence of the seasonal factor were tried to answer by the help of chemometrical methods. It was possible to show that the two sampling places situated only about 7 km from each other have different total metal concentrations as well as different binding form patterns. The trend of the heavy metal enrichment in the smallest particle size fraction can easily be seen in two-dimensional diagrams, but could in general not be confirmed statistically for all metals. The consideration of all four factors together (region, particle size fraction, mobilisation class, and time) shows the significant influence caused by all factors and all interactions. Multivariate covariance analysis is used to include also the influence of sampling conditions.Dedicated on the occasion of his 70th birthday to Professor Dr. Klaus Doerffel, who has spent much of his life in teaching and introducing statistical and other chemometrical techniques in Analytical Chemistry     

Changes in the heavy metal contents of soil from the Park Grass Experiment at Rothamsted Experimental Station

The classical Rothamsted Experiments allow to contribute to current research. The heavy metal content of soil and hay samples have been measured with ICP-AES from a control and a fertilized plot of the Park Grass Experiment. Today a difference of 1.2 can be observed in the pH levels of the control and fertilized plots; the pH level of the control plot has decreased about 1.0, that of the fertilized plot about 2.2 as a result of 150 years of acid deposition and fertilization. The changes in the pH levels has caused many changes in the heavy metal content of the top layer of the soil. Using different extraction methods (e.g., ammonium acetate, EDTA, and sequential analysis), the heavy metal content of different fractions have been estimated. In the control plot, the Zn, Cd and Pb content increased. In the fertilized plot, the Pb and Cd contents have also increased because of atmospheric deposition and small amounts of lead in the fertilizer. The available form of Cd and Pb increased in both the control and the fertilized plots.     

Changes in the heavy metal contents of soil from the Park Grass Experiment at Rothamsted Experimental Station

The classical Rothamsted Experiments allow to contribute to current research. The heavy metal content of soil and hay samples have been measured with ICP-AES from a control and a fertilized plot of the Park Grass Experiment. Today a difference of 1.2 can be observed in the pH levels of the control and fertilized plots; the pH level of the control plot has decreased about 1.0, that of the fertilized plot about 2.2 as a result of 150 years of acid deposition and fertilization. The changes in the pH levels has caused many changes in the heavy metal content of the top layer of the soil. Using different extraction methods (e.g., ammonium acetate, EDTA, and sequential analysis), the heavy metal content of different fractions have been estimated. In the control plot, the Zn, Cd and Pb content increased. In the fertilized plot, the Pb and Cd contents have also increased because of atmospheric deposition and small amounts of lead in the fertilizer. The available form of Cd and Pb increased in both the control and the fertilized plots.     

泰安市城区土壤重金属污染特征及风险评价

为了解泰安市城区土壤重金属污染特征,对采集的30件土壤样品中6种重金属含量进行测定,利用单因子污染指数法、内梅罗综合污染指数法、地累积指数法和潜在生态风险指数法开展污染状况评价。结果表明：土壤中As、Cd、Cu、Pb、Hg、Ni的平均含量分别为6.72、0.066、20.33、18.19、0.031和19.92 mg.kg^-1,其中As、Cd、Cu、Pb、Ni的平均含量均低于泰安市和山东省土壤背景值,Hg的平均含量略高于泰安市土壤背景值,变异系数大于0.6,其含量受人类活动影响较大,空间分布差异性较大;除Hg的单因子污染指数为1.03,严重污染、中度污染、轻微污染和无污染采样点数量占比分别为3%、7%、23%和67%,其他重金属单因子污染指数平均值小于1,为无污染状态;重金属内梅罗综合污染指数平均为1.58～1.64,整体属于轻污染水平;土壤重金属累积较轻,多数为无污染状态,Hg的最大地累积指数为1.29,达中等-强污染(3级);综合生态风险指数RI的范围为39.96～191.81,平均值为77.60,综合生态风险等级为轻微,为低生态风险区,Hg为引起风险的主要因子;Cu、Ni含量较低,富集主要受土壤母质和自然过程的控制;Pb、Cd、As主要来源于自然背景因素,部分受人类活动影响;Hg的污染来源于化肥、塑料地膜和含重金属的无机农药使用,受农业活动和居民生活影响较大。     

Determination of Heavy Metals in Soil Extracts and Plant Tissues at Around of a Zinc Smelter

Abstract

Extractable contents of heavy metals such as Cr, Mn, Fe, Co, Ni, Cu, Zn, Cd, Pb and Bi in soil and plant tissue samples (fruit, leaf, twig and root) collected, along a distance of 1100 m to the West, from the surroundings of a metallurgical factory producing mainly zinc, cadmium and lead were determined by flame atomic absorption spectrometry (FAAS). In addition, the determinations of Ca and Mg, macro nutrient elements for plants, were also performed. Three extractant solutions were used for dissolution of soil samples, namely aqua regia (1 HNO₃₊ 3 HCl) for total metal analysis, 1 mol L^?1 ammonium acetate for exchangeable metal contents, and a dilute acid mixture (0.1 M HCl in 0.025 M H₂SO₄) for acid soluble metal contents. A mixture of HNO₃ and HClO₄ was used to analyze the fruit samples. The analyses of the leaf, the twig, and the root tissue samples were made by dry ashing method. The detection limits of the metals were in the range of 0.04 to 0.45 μg/mL for all soil extracts and 0.01 to 1.50 μg/mL for the fruit samples. The recovery values for all the determinations were higher than 95%. The results obtained from the analyses of plant tissue and soil samples were evaluated using linear correlation analysis and concentration factors to identify the effect of the factory near the grape-vine area.     

Relationship between vegetable metal and soil-extractable metal contents by the BCR sequential extraction procedure: chemometrical interpretation of the data

The contents of heavy metals in soil and vegetable samples collected from an urban garden in Kayseri, Turkey, were investigated. Both wet- and dry-ashing methods were used for dissolving vegetable samples. A sequential extraction procedure proposed by the Commission of the European Communities, Community Bureau of Reference (now superseded by the Standards, Measurement and Testing Programme, SM&T) was applied to the soil samples to extract the metals which are present in exchangeable and acid soluble (i.e. bound to carbonates), reducible (bound to Fe/Mn oxides), and oxidisable forms (bound to organic matter and sulphides) in the soil samples. Trace metals in the soil and vegetable samples were determined using flame atomic absorption spectrometry (FAAS). The total metal contents acquired by summing of metal levels in all the sequential extraction steps were compared with pseudo-total metal levels obtained with aqua regia for all the soil samples. The recovery values obtained by proportioning the results obtained by the BCR procedure to those of the pseudo-total digestion were found to be satisfactory. The limits of detection for the elements investigated were in the range of 0.04 to 0.59?µg?mL^?1 for all the extraction stages of the BCR procedure. Similarities among the variables were identified by correlation analysis, principal component analysis and hierarchical cluster analysis. The relationship between the vegetable metal and soil-extractable metal concentrations was examined in order to evaluate the bioavailability of metals.     

矿区重金属污染土壤修复技术的研究现状和展望

矿区土壤重金属污染是当今世界面临的主要环境问题之一,其污染修复一直是环境科学领域研究的重要领域之一。对矿区土壤重金属污染的修复方法,包括物理化学技术、植物修复技术、动物修复技术的机理、优缺点以及实用性进行了综述,并对矿区土壤修复的研究进行了展望。     

Bioaccumulative and conchological assessment of heavy metal transfer in a soil-plant-snail food chain

ABSTRACT: BACKGROUND: Copper (Cu), zinc (Zn), cadmium (Cd), and lead (Pb) can pose serious threats to environmental health because they tend to bioaccumulate in terrestrial ecosystems. We investigated under field conditions the transfer of these heavy metals in a soil-plant-snail food chain in Banat area, Romania. The main goal of this paper was to assess the Roman snail (Helix pomatia) usefulness in environmental monitoring as bioindicator of heavy metal accumulation. Eight sampling sites, selected by different history of heavy metal (HM) exposure, were chosen to be sampled for soil, nettle leaves, and newly matured snails. This study also aimed to identify the putative effects of HM accumulation in the environment on phenotypic variability in selected shell features, which included shell height (SH), relative shell height (RSH), and whorl number (WN). RESULTS: Significantly higher amounts of HMs were accumulated in snail hepatopancreas and not in foot. Cu, Zn, and Cd have biomagnified in the snail body, particularly in the hepatopancreas. In contrast, Pb decreased when going up into the food chain. Zn, Cd, and Pb correlated highly with each other at all levels of the investigated food chain. Zn and Pb exhibited an effective soil-plant transfer, whereas in the snail body only foot Cu concentration was correlated with that in soil. There were significant differences among sampling sites for WN, SH, and RSH when compared with reference snails. WN was strongly correlated with Cd and Pb concentrations in nettle leaves but not with Cu and Zn. SH was independent of HM concentrations in soil, snail hepatopancreas, and foot. However, SH correlated negatively with nettle leaves concentrations for each HM except Cu. In contrast, RSH correlated significantly only with Pb concentration in hepatopancreas. CONCLUSIONS: The snail hepatopancreas accumulates high amounts of HMs, and therefore, this organ can function as a reliable biomarker for tracking HM bioavailability in soil. Long-term exposure to HMs via contaminated food might influence the variability of shell traits in snail populations. Therefore, our results highlight the Roman snail (Helix pomatia) potential to be used in environmental monitoring studies as bioindicator of HM pollution.