Pollution, fractionation, and mobility of Pb, Cd, Cu, and Zn in garden and paddy soils from a Pb/Zn mining area

This study was conducted to investigate the pollution load index, fraction distributions, and mobility of Pb, Cd, Cu, and Zn in garden and paddy soils collected from a Pb/Zn mine in Chenzhou City, China. The samples were analyzed using Leleyter and Probst’s sequential extraction procedures. Total metal concentrations including Pb, Cd, Cu, and Zn exceeded the maximum permissible limits for soils set by the Ministry of Environmental Protection of China, and the order of the pollution index was Cd > Zn > Pb > Cu, indicating that the soils from both sites seriously suffered from heavy metal pollution, especially Cd. The sums of metal fractions were in agreement with the total contents of heavy metals. However, there were significant differences in fraction distributions of heavy metals in garden and paddy soils. The residual fractions of heavy metals were the predominant form with 43.0% for Pb, 32.3% for Cd, 33.5% for Cu, and 44.2% for Zn in garden soil, while 51.6% for Pb, 40.4% for Cd, 40.3% for Cu, and 40.9% for Zn in paddy soil. Furthermore, the proportions of water-soluble and exchangeable fractions extracted by the selected analytical methods were the lowest among all fractions. On the basis of the speciation of heavy metals, the mobility factor values of heavy metals have the following order: Cd (25.2–19.8%) > Cu (22.6–6.3%) > Zn (9.6–6.0%) > Pb (6.7–2.5%) in both contaminated soils.     

Certification of the extractable contents of Cd, Cr, Cu, Ni, Pb and Zn in a freshwater sediment following a collaboratively tested and optimised three-step sequential extraction procedure

Sequential extraction procedures have been used during the last decades to study and determine trace element mobility in aquatic sediments. However, the results obtained are operationally defined and, therefore, the significance of the analytical results is related to the extraction scheme used. So, there is a need for suitable reference materials for this type of study to enable the validation of the methodologies and to control the quality of the measurements. This paper describes the preparation of a sediment reference material, BCR-701, the homogeneity and stability studies and the analytical work performed for the certification of the extractable contents of some trace elements, following a collaboratively tested and optimised sequential (three-step) extraction procedure. The paper contains all the results and gives the methods used to certify the extractable contents (mass fractions expressed as mg kg-1 on a dry matter basis) of Cd, Cr, Cu, Ni, Pb and Zn in all steps. Moreover, indicative values are given for the aqua regia extractable contents of the six elements in the sediment and the residue obtained after sequential extraction.     

Competitive sorption of Cd, Cu, Mn, Ni, Pb and Zn in polluted and unpolluted calcareous soils

The objectives of this study were to investigate competitive sorption behaviour of heavy metals (Cd, Cu, Mn, Ni, Pb and Zn) under different management practices and identify soil characteristics that can be correlated with the retention and mobility of heavy metals using 65 calcareous soil samples. The lowest sorption was found for Mn and Ni in competition with the other metals, indicating the high mobility of these two cations. The Freundlich equation adequately described heavy metals adsorption. On the basis of Freundlich distribution coefficient, the selectivity sequence of the metal adsorption was Cu?>?Pb?>?Cd?>?Zn?>?Ni?>?Mn. The mean value of the joint distribution coefficient (K _dΣsp) was 182.1, 364.1, 414.7, 250.1, 277.7, 459.9 and 344.8 l kg^?1 for garden, garlic, pasture, potato, vegetables, wheat and polluted soils, respectively. The lowest observed K _dΣsp in garden soil samples was due to the lower cation exchange capacity and lower carbonate content. The results of the geochemical modelling under low and high metal addition indicated that Cd, Ni, Mn and Zn were mainly retained via adsorption, while Pb and Cu were retained via adsorption and precipitation. Stepwise forward regression analysis showed that clay, organic matter and CaCO₃ were the most important soil properties influencing competitive adsorption of Cd, Mn, Ni and Zn. The results in this study point to a relatively easy way to estimate distribution coefficient values.     

Concentration of Cd, Cu, Pb, Zn, Al, and Fe in soils of Manresa, NE Spain

The aims of this study were to determine the contents of cadmium (Cd), copper (Cu), lead (Pb), zinc (Zn), aluminium (Al), and iron (Fe) (aqua regia-extractable) in 27 soil plots (54 samples) from Manresa, NE Spain, and to establish relationships between heavy metals and some soil properties. The main soil types were surveyed and the median concentrations (mg kg(-1)) obtained were Cd 0.28, Cu 20.3, Pb 18.6, Zn 67.4, Al 22,572, and Fe 21,551. Element concentrations for these soils were lower than the published values for the Valencia region (Spain) and Torrelles and Sant Climent municipal districts (Catalonia, Spain). In terms of soil properties, the results of this study suggest that, in Manresa soils, both trace element adsorption and retention are influenced by several properties such as clay minerals, carbonates, organic matter, and pH. All element contents were positively correlated with clay content. Pb and Zn were negatively correlated with pH and CaCO(3).     

Determination of heavy metals (Cd, Cr, Cu, Fe, Ni, Pb, Zn) by ICP-OES and their speciation in Algerian Mediterranean Sea sediments after a five-stage sequential extraction procedure

Surface sediment samples (n = 18) were collected from the Algerian Mediterranean coasts and analyzed for seven metals using inductively coupled plasma-optical emission spectrometry in order to asses the distribution and bioavailability of metals and to study the anthropogenic factors affecting their concentrations. Sediment samples were size-fractionated into three sizes: 1,080–500 (coarse), 500–250 (medium), and <250 mm (fine). Bulk sediments were subjected to both sequential extraction and total digestion to evaluate the reliability of the sequential extraction procedure (SEP), while the fractions have been only sequentially extracted for metals speciation. The metals were sequentially extracted into five phases namely exchangeable (P1), carbonates (P2), Fe–Mn oxides (P3), organic (P4) and residual (P5). Metal recoveries in sequential extractions were ±20% of the independently measured total metal concentrations; the high recovery rates indicate the good reliability of the SEP used in this study. Correlation coefficients indicated that the grain size has an effect on the distribution of metals in the investigated samples. The order of metal levels in the fractions was medium > fine > coarse for all the metals. The average total extractable metal concentrations for Cd, Cr, Cu, Fe, Ni, Pb, and Zn were 1.1, 8.8, 4.7, 1,291.3, 13.9, 5.7 and 20.4 μg/g, respectively. The northeastern shelf had the lowest metal levels while the highest were in northwestern part mainly due to the significant tourism activities in the northwestern part. Comparison of our results to Earth’s crust values and to previous studies points out that our samples were relatively unpolluted with respect to the heavy metals investigated; most of the metals are not from anthropogenic sources. Enrichment factors as the criteria for examining the impact of the anthropogenic sources of heavy metals were calculated, and it was observed that the investigated samples were not contaminated with Cr, Cu, and Fe, moderately contaminated with Ni, Pb, and Cd, and contaminated with Cd in some sites. The P5 phase had the highest percents of Cr, Cu, Fe, Ni, and Zn. Cadmium and lead were predominant in the P4 phase, while Cu, Fe and Zn were distributed in the order P5 > P3 > P4 > P2 > P1. The following order of bioavailability was found with the heavy metals Pb > Cr > Cd > Ni > Zn > Cu > Fe.     

Prediction of PAH biodegradation in field contaminated soils using a cyclodextrin extraction technique

Biodegradation has been identified as a major loss process for organic contaminants in soils and, as a result, microbial strategies have been developed for the remediation of contaminated land. Prediction of the biodegradable fraction would be important for determining bioremediation end-points in the clean-up of contaminated land. The aim of this study was to investigate the ability of a cyclodextrin extraction to predict the extent to which polycyclic aromatic hydrocarbons (PAHs) would be degraded microbiologically in field contaminated soils; further testing the robustness and reproducibility of this extraction in chemically complex systems. Dichloromethane and hydroxypropyl-beta-cyclodextrin (HPCD) extractable fractions were measured together with the PAH biodegradable fraction in each of the six field contaminated soils. The amounts of PAHs degraded by the catabolic activity of the indigenous microflora in each of the soils were correlated with HPCD-extractable PAH concentrations. The regressions showed that the amounts of lower molecular weight PAHs extracted by the HPCD were not significantly (P > 0.05) different to the amounts that were degraded. However, higher molecular weight PAHs that were extracted by HPCD did differ significantly (P < 0.05) from the amounts degraded. Although the HPCD extraction did overestimate the microbially degradable fraction of the higher molecular weight PAHs, overall the correlations between the HPCD extractable fraction and the microbially degradable fraction were very close, with mean values of the slope of line for the six soils equalling 1. This study further describes the robust and reproducible nature of the aqueous-based soil extraction technique reliably measuring the extent to which PAHs will be microbially degraded in soil.     

Solid phase extraction of Cd,Pb, Ni,Cu, and Zn in environmental samples on multiwalled carbon nanotubes

A simple and sensitive solid phase extraction (SPE) method on multiwalled carbon nanotubes (MWCNTs) is presented for the determination of cadmium, lead, nickel, copper, and zinc at trace levels combined with flame atomic absorption spectrometry. The effects of parameters like pH, sample volume, sample and eluent flow rates, eluent concentration, and volume and type of eluent on the recovery of trace elements was examined. The metals retained on the nanotube at pH 6.5 as α-benzoin oxime complexes were eluted by 10 mL 2 M HNO₃ in acetone. The influence of matrix ions on the developed method was also evaluated. The preconcentration factor of the method was found to be 50. The detection limits for Cd(II), Pb(II), Ni(II), Cu(II), and Zn(II) were found as 1.7, 5.5, 6.0, 2.3, and 2.4 μg L^?1, respectively. To test the accuracy of the method, the method was applied to TMDA-70 fortified lake water and Spinach 1570A standard reference materials. Addition recovery studies were applied to tap water and cracked wheat samples, and determination of the analyte elements was carried out in some food samples with good results.     

Accumulation of Cu, Cd, Cr, Mn and Pb from artificially contaminated soil by Bacopa Monnieri

The metal accumulation potential of Bacopa monnieri L. was assessed under simulated laboratory conditions. This study was carried out in mixed metals (Cu, Cd, Pb, Cr, Mn) condition and repeated exposures in artificial contaminated soil. The growing shoots were planted in garden subsoil containing 3, 16, 32, 64, 160 M each of the above metals. After 8 weeks, plants were refeeded to three times higher concentrations of each metal than initially used to assess the maximum accumulating potential of the metals. The accumulation of the metals by the root and shoot was concentration and duration dependent. The metal accumulation was considerably higher in the fine root than in the shoot and showed the following order : Mn > Cr > Cu > Cd > Pb. The plants showed high tolerance to the metals as no visible phytotoxic symptom was produced after 8 weeks. However, as a result of combined metal toxicity, chlorophyll content was reduced by 62% after 12 weeks. The highest metal concentration was lethal to the plant at 16 weeks. In view of their high tolerance, the plants of B. monnieri may be considered for the amelioration of industrially-polluted wetlands experiencing regular flushing of wastewaters.     

Trace Level Determination of U, Zn, Cd, Pb and Cu in Drinking Water Samples

The concentration of uranium has been assessed in drinking water samples collected from different locations in Bathinda district, Punjab, India. The water samples are taken from hand pumps and tube wells. Uranium is determined using fission track technique. Uranium concentration in the water samples varies from 2.23± 0.05 to 87.05± 0.29 μg/L. These values are compared with safe limit values recommended for drinking water. The uranium concentration in almost all drinking water samples is found to be more than the safe limit. Analysis of some heavy metals viz. Zn, Cd, Pb and Cu in water is made. The concentration of sodium, potassium, calcium, magnesium, chlorine and total hardness along with the pH value and conductivity of the water samples are measured. Some of the samples show stunningly high values of these parameters.     

Evaluation of Pb, Cu, Zn, Cd, Ni and Fe levels in Rosmarinus officinalis labaiatae (Rosemary) medicinal plant and soils in selected zones in Jordan

The concentration of heavy metals including Pb, Cu, Zn, Cd, Ni and Fe in different parts of Rosmarinus officinalis medicinal plant grown in Jordan were evaluated. Medicinal plant samples and soil samples were collected from three different zones in Jordan (Irbid, Al-Mafraq and Ma’an). Samples were analyzed by atomic absorption spectrometry (AAS) after chemical treatments using acid digestion procedures. Heavy metal levels in washed and unwashed in each part of R. officinalis were analyzed and compared statistically. Results show that concentrations of investigated heavy metals were varied from plant part to another part of R. officinalis. For example, Pb, Zn, Cu and Cd in most parts of R. officinalis in the three zones were concentrated in the following order: flowers, leaves, stems, whereas Pb, Ni and Fe were concentrated in order as follows: leaves, flowers and stems. Heavy metal concentrations in soil samples was evaluated and correlated with their levels in R. officinalis. Two standard reference materials of plant (SRM 1790a; spinach leaves and CRM 281; rye grass) and one standard reference materials of soil (GBW 07406) were examined to validate the method used. Results show that high recoveries were obtained.     

ISS-2锌渣标准样品中Zn、Pb、Cd全量浸取研究及与纯水浸提比较

锌渣标准样品２００目,已经过多家实验室协作定值,通过二种方法可提取样品中的全量Ｐｂ、Ｚｎ、Ｃｄ：（１）１＋９ＨＣｌ,密封,０１２～０１４ＭＰａ,１２１℃,６０ｍｉｎ;（２）１＋９ＨＣｌ,超声波处理,６０ｍｉｎ。     

Atmospheric deposition of heavy metals (Cu, Zn, Cd and Pb) in Varanasi City, India

Rapid growth in urbanization and industrialization in developing countries may significantly contribute in heavy metal contamination of vegetables through atmospheric depositions. In the present study, an assessment was made to investigate the spatial and seasonal variations in deposition rates of heavy metals and its contribution to contamination of palak (Beta vulgaris). Samples of bulk atmospheric deposits and Beta vulgaris for analysis of Cu, Zn, Cd and Pb were collected from different sampling locations differing in traffic density and land use patterns. The results showed that the sampling locations situated in industrial or commercial areas with heavy traffic load showed significantly elevated levels of Cu, Zn and Cd deposition rate as compared to those situated in residential areas with low traffic load. The deposition rates of Cu, Zn and Cd were significantly higher in summer and winter as compared to rainy season, however, Pb deposition rate was significantly higher in rainy and summer seasons as compared to winter season. Atmospheric depositions have significantly elevated the levels of heavy metals in B. vulgaris collected during evening as compared to those collected in morning hours. The study further showed that local population has maximum exposure to Cd contamination through consumption of B. vulgaris. The present study clearly points out the urban and industrial activities of a city have potential to elevate the levels of heavy metals in the atmospheric deposits, which may consequently contaminate the food chain and thus posing health risk to the local population.     

Monitoring of Cr, Cu, Pb, V and Zn in polluted soils by laser induced breakdown spectroscopy (LIBS)

Laser Induced Breakdown Spectroscopy (LIBS) is a fast and multi-elemental analytical technique particularly suitable for the qualitative and quantitative analysis of heavy metals in solid samples, including environmental ones. Although LIBS is often recognised in the literature as a well-established analytical technique, results about quantitative analysis of elements in chemically complex matrices such as soils are quite contrasting. In this work, soil samples of various origins have been analyzed by LIBS and data compared to those obtained by Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES). The emission intensities of one selected line for each of the five analytes (i.e., Cr, Cu, Pb, V, and Zn) were normalized to the background signal, and plotted as a function of the concentration values previously determined by ICP-OES. Data showed a good linearity for all calibration lines drawn, and the correlation between ICP-OES and LIBS was confirmed by the satisfactory agreement obtained between the corresponding values. Consequently, LIBS method can be used at least for metal monitoring in soils. In this respect, a simple method for the estimation of the soil pollution degree by heavy metals, based on the determination of an anthropogenic index, was proposed and determined for Cr and Zn.     

Soil Contamination by Pb, Zn and Cn from a Lead Smeltery

In the environment of a lead smeltery contamination with lead, zinc and cadmium was measured over a 15-year period. Efficient bag filters were installed in order to remove dust from the flue gases. This measure of improvement resulted in a drastic reduction of lead, zinc and cadmium content in suspended particles (by 92, 94 and 89%), to a lesser extent in depositions (by 79, 75 and 68%), whereas in household dust the reduction was considerably lower (by 53, 55 and 70%). It can be assumed that household dust contains also redispersed soil particles on which the dust from the smeltery flue gases has deposited over years. To determine to what extent contaminated soil continues to cause increased population exposure directly or through plants or pastures, in the period 1981–1985 the content of metallic ions in the soil was measured at three depths. Selective solubility of soil metallic compounds was analysed in water, in 1 mol ammoniumacetate solution and in 0.05 mol ethylenediaminetetra-acetic acid (EDTA) solution in relation to their solubility in suspended particles, depositions and household dust. A considerably low portion of soluble metallic compounds was found in the soil and physico-chemical characteristics of the soil and portion of metallic ions bound to fulvice and humic acids were determined. The behaviour of metallic ions in contact with soil samples was studied in laboratory and it was found that approximately 50% of lead, 70% of zinc and 7% of cadmium ions change into non-soluble or poorly soluble compounds. By qualitative phase analysis in the non-soluble fraction PbO₂, Pb₃P₄O₁₃, Zn(OH)₂, ZnO, Fe₂O₃ and Cd(OH)₂ were identified.     

Determination of Cu, Pb, Zn, Ni, Co, Cd, and Mn in road dusts of Samsun City

The dust samples from 52 different locations in central roads of Samsun City were collected in a study area of 40 km long for the purpose of determining total metal concentrations of dust samples by flame atomic absorption spectrometry. The concentrations of Cu, Pb, Co, Zn, Ni, Mn, and Cd were found in the ranges of 11.92–352.43, 5.47–223.57, 4.52–41.69, 40.85–173.10, 18.71–131.29, 133.19–179.13, and 0.02–6.16 mg/kg, respectively. The results showed that metal levels were higher around the industrial area than other locations. Principal component analysis was also carried out to ascertain the possible contributing factors towards the metal concentrations. Validation of the analytical results was tested by analysis of the BCR 032 Moroccan phosphate rock certified reference material.     

Uncertainty assessment of mapping mercury contaminated soils of a rapidly industrializing city in the Yangtze River Delta of China using sequential indicator co-simulation

Accurate characterization of heavy-metal contaminated areas and quantification of the uncertainties inherent in spatial prediction are crucial for risk assessment, soil remediation, and effective management recommendations. Topsoil samples (0–15 cm) (n = 547) were collected from the Zhangjiagang suburbs of China. The sequential indicator co-simulation (SIcS) method was applied for incorporating the soft data derived from soil organic matter (SOM) to simulate Hg concentrations, map Hg contaminated areas, and evaluate the associated uncertainties. High variability of Hg concentrations was observed in the study area. Total Hg concentrations varied from 0.004 to 1.510 mg kg⁻¹ and the coefficient of variation (CV) accounts for 70%. Distribution patterns of Hg were identified as higher Hg concentrations occurred mainly at the southern part of the study area and relatively lower concentrations were found in north. The Hg contaminated areas, identified using the Chinese Environmental Quality Standard for Soils critical values through SIcS, were limited and distributed in the south where the SOM concentration is high, soil pH is low, and paddy soils are the dominant soil types. The spatial correlations between Hg and SOM can be preserved by co-simulation and the realizations generated by SIcS represent the possible spatial patterns of Hg concentrations without a smoothing effect. Once the Hg concentration critical limit is given, SIcS can be used to map Hg contaminated areas and quantitatively assess the uncertainties inherent in the spatial prediction by setting a given critical probability and calculating the joint probability of the obtained areas.     

The effect of humic acids on the sequential extraction of metals in soils and sediments using ICP-AES and chemometric analysis

The effect of humic acids on the sequential extraction of metals from various soils and sediments has been studied. A new multi-element extraction method optimised via experimental design has been employed. The method uses centrifugation to pass the extractant solution, at varying pH, through the sediment sample. The sequential leaches were collected and analysed by ICP-AES. Chemometric data processing was utilised to identify the composition of the physico-chemical components in order to characterise the sample. A sediment sample collected from Carnon River (Cornwall, UK) and a reference material (NIST 2711 agricultural soil) were spiked with humic acids and the sequential extraction scheme was used to monitor the changes in metal distribution. The method has proved a quick and reliable way to evaluate different sediment samples, and has potential as a new tool for environmental geochemistry analysis.     

Geochemical position of Pb,Zn and Cd in soils near the Olkusz mine/smelter,South Poland: effects of land use,type of contamination and distance from pollution source

The soils adjacent to an area of historical mining, ore processing and smelting activities reflects the historical background and a mixing of recent contamination sources. The main anthropogenic sources of metals can be connected with historical and recent mine wastes, direct atmospheric deposition from mining and smelting processes and dust particles originating from open tailings ponds. Contaminated agriculture and forest soil samples with mining and smelting related pollutants were collected at different distances from the source of emission in the Pb–Zn–Ag mining area near Olkusz, Upper Silesia to (a) compare the chemical speciation of metals in agriculture and forest soils situated at the same distance from the point source of pollution (paired sampling design), (b) to evaluate the relationship between the distance from the polluter and the retention of the metals in the soil, (c) to describe mineralogy transformation of anthropogenic soil particles in the soils, and (d) to assess the effect of deposited fly ash vs. dumped mining/smelting waste on the mobility and bioavailability of metals in the soil. Forest soils are much more affected with smelting processes than agriculture soils. However, agriculture soils suffer from the downward metal migration more than the forest soils. The maximum concentrations of Pb, Zn, and Cd were detected in a forest soil profile near the smelter and reached about 25 g kg^− 1, 20 g kg^− 1 and 200 mg kg^− 1 for Pb, Zn and Cd, respectively. The metal pollutants from smelting processes are less stable under slightly alkaline soil pH then acidic due to the metal carbonates precipitation. Metal mobility ranges in the studied forest soils are as follows: Pb > Zn ≈ Cd for relatively circum-neutral soil pH (near the smelter), Cd > Zn > Pb for acidic soils (further from the smelter). Under relatively comparable pH conditions, the main soil properties influencing metal migration are total organic carbon and cation exchange capacity. The mobilization of Pb, Zn and Cd in soils depends on the persistence of the metal-containing particles in the atmosphere; the longer the time, the more abundant the stable forms. The dumped mining/smelting waste is less risk of easily mobilizable metal forms, however, downward metal migration especially due to the periodical leaching of the waste was observed.     

A survey of Pb,Cu, Zn,Cd, Cr,As, and Se in earthworms and soil from diverse sites

Earthworms and soils were collected from 20 diverse sites in Maryland, Pennsylvania, and Virginia, and were analyzed for Pb, Cu, Zn, Cd, Cr, As, and Se. Correlation coefficients relating concentrations of the elements in earthworms to concentrations in soil were low (–0.20<r<+0.57). Species differences and ecological variables contributed to the variability in concentrations of these elements in earthworms. The maximum concentrations of Pb (2100 ppm), Zn (1600 ppm), Cd (23 ppm) and Se (7.6 ppm) detected in earthworms were in the range reported to be toxic to animals fed diets containing these elements; however, even in the absence of any environmental contamination, some species of earthworms may contain high concentrations of Pb, Zn, and Se. Earthworms of the genus Eisenoides, for example, were exceptional in their ability to concentrate Pb. When earthworms are used as indicators of environmental contamination, it is important to identify the species, to report the soil characteristics, and to collect similar earthworms from very similar but uncontaminated soil.     

Investigation of trace elements in agricultural soils by BCR sequential extraction method and its transfer to wheat plants

In this study, soil samples were collected from Edirne, Turkey in both summer and winter seasons and subjected to the modified Community Bureau of Reference (BCR) sequential extraction procedure in order to investigate the chemical partitioning of metals in soils and to predict heavy metals uptake by wheat grains which grown at the same soils. The samples were subjected to a three stage extraction procedure proposed by the BCR. The three phases that were separated out in the following order: (1) carbonate, exchangeable, (2) Fe?CMn oxides, and (3) organic matter. Metal concentrations of soil fractions and grain samples were determined by inductively coupled plasma atomic emission spectroscopy. The wheat samples were prepared to analysis using microwave acid digestion procedure. The pseudo-total concentrations of metals were determined after aqua regia digestion. The analytical accuracy of the method was evaluated by using the Standard Reference Materials (BCR 142R Light Sandy Soil, NIST 2711 Montana Soil, and NIST 2704 Buffalo River Sediment). The sum of the metal contents obtained from the modified BCR sequential extraction procedure and pseudo-total metal contents for soil samples were used to calculate recovery values. In order to evaluate the bioavailability of metals, the relationships between the wheat-metal and soil-extractable metal concentrations were compared.