Application of Leaching Tests for the Assessment of Available Heavy Metals from Domestic and Industrial Sludges

Various sludge samples from different domestic and industrial wastewater treatment plants were analyzed by Flame Atomic Absorption Spectrometry to evaluate their total and available contents of heavy metals (Cu, Cr, Ni, Pb, Zn and Fe). The EDTA and acetic acid single extraction procedures were applied to these samples with the aim to study the leaching behaviour of the metals in the different sludges and also to predict their possible mobility when these wastes are disposed on the environment and landfills. In acidic medium, a higher extraction efficiency was observed for the major part of the elements studied in the industrial sludges, except for Ni and Zn, which were also considerably released from domestic sludges. In contrast, in the presence of the EDTA complexing ligand, a more elevated mobility of metals was found in the domestic sludges and little or no metals were released from the industrial sludges. Moreover, the results of the microwave total digestions were compared, for all metals, with those obtained using a more simplified pseudototal digestion procedure (based on the EPA Method 3051, named microwave assisted acid digestion of sediments, sludges, soils and oils) and a good agreement was found between them, except for Cr and Ni in some particular samples. The between-batch precision (expressed as RSD) of both compared digestion methods was very similar and values lower than 7.7% were obtained in both cases. A certified domestic sludge material (SRM 2781) was employed to validate the two digestion procedures and no significant differences were found between the certified and experimental values for all the elements studied.     

Metal fractionation in olive oil and urban sewage sludges using the three-stage BCR sequential extraction method and microwave single extractions

The conventional three-stage BCR sequential extraction method was employed for the fractionation of heavy metals in sewage sludge samples from an urban wastewater treatment plant and from an olive oil factory. The results obtained for Cu, Cr, Ni, Pb and Zn in these samples were compared with those attained by a simplified extraction procedure based on microwave single extractions and using the same reagents as employed in each individual BCR fraction. The microwave operating conditions in the single extractions (heating time and power) were optimized for all the metals studied in order to achieve an extraction efficiency similar to that of the conventional BCR procedure. The measurement of metals in the extracts was carried out by flame atomic absorption spectrometry. The results obtained in the first and third fractions by the proposed procedure were, for all metals, in good agreement with those obtained using the BCR sequential method. Although in the reducible fraction the extraction efficiency of the accelerated procedure was inferior to that of the conventional method, the overall metals leached by both microwave single and sequential extractions were basically the same (recoveries between 90.09 and 103.7%), except for Zn in urban sewage sludges where an extraction efficiency of 87% was achieved. Chemometric analysis showed a good correlation between the results given by the two extraction methodologies compared. The application of the proposed approach to a certified reference material (CRM-601) also provided satisfactory results in the first and third fractions, as it was observed for the sludge samples analysed.     

Microwave extraction of heavy metals from wet rhizosphere soils and its application to evaluation of bioavailability

Single microwave extraction of heavy metals Cr, Ni, Zn, Cu, Cd, and Pb by the extractants CaCl(2), EDTA, CH(3)COOH and HCl has been established. The experimental conditions were optimized. A microwave power of 60% and an extraction time of 25 min were adopted. Comparison of microwave extraction and conventional extraction methods revealed that results obtained by microwave techniques were generally in a good agreement with those obtained by use of extraction methods; use of the former resulted in substantial time saving and a better precision, however. Microwave extraction was used to evaluate the bioavailability of heavy metals in soils. Single correlation analysis was performed to establish the relationship between the concentrations of the extractable heavy metals in wet rhizosphere soils and their concentrations in wheat ( Troticum aestivum L.) grown on the soils under greenhouse conditions. The correlation coefficients between the extractable metals in soils and their concentrations in wheat roots were found to be 0.5398-0.7819, 0.6425-0.8073, 0.5568-0.8276, 0.5851-0.6087 for the extractants CaCl(2), EDTA, CH(3)COOH, and HCl, respectively.     

Assessment of trace metals contamination in estuarine sediments using a sequential extraction technique and principal component analysis

Fractionation of the metals Cd, Cr, Cu, Ni, Pb and Zn in sediments was performed for samples collected from eight locations in the Poxim river estuary of Sergipe State, northeast Brazil, using the 3-stage sequential extraction procedure proposed by the European Community Bureau of Reference (BCR). The extraction method was found to be satisfactory for analysis of certified reference material BCR-701, with recovery values ranging from 85% (Cu) to 117% (Cr). The detection limits obtained were 0.001 to 0.305 µg g^− 1. Zn exhibited greatest mobility and bioavailability, indicative of anthropogenic sources, while Cr was mainly found in the residual fraction and could be used as an indicator for the contribution from natural sources. Cd, Cu, Ni and Pb were associated with the oxidizable fraction, and Pb, Cr and Ni with the reducible fraction. Principal component analysis (PCA) clearly separated the metals into three groups: I (Zn); II (Pb); III (Cd, Cu, Cr and Ni). These groupings were mainly due to different distributions of the metals in the various fractions, in sediments from the different locations. Risk assessment code (RAC) analysis indicated that although the metals presented a moderate overall risk to the aquatic environment, nickel showed a low risk (RAC < 10%) at three sites, while zinc presented a high risk (RAC > 30%) at four other sites.     

Distribution of Minor and Trace Metals in Carezza Lake (ANTARCTICA) Ecosystem

Abstract

This paper reports the distribution of a series of metals in natural samples collected at Carezza Lake in Antarctica, during the Italian Expedition in the austral summer 1989/90. The considered elements are: water, sediments and soil sampled from the surroundings of the lake and algae. The determination of the total concentration of the following metals was performed: Al, As, Ca, Cd, Co, Cr, Cu, Fe, Mg, Mn, Na, Ni, Pb, Zn. In addition, for sediment and soil samples, a speciation study was performed for some metals, namely Cd, Co, Cr, Cu, Fe, Mn, Ni, Zn, using the Tessier procedure.     

Comparison of single extraction procedures,using either conventional shaking or microwave heating,and the Tessier sequential extraction method for the fractionation of heavy metals from environmental samples

The conventional four-step sequential extraction method and the EDTA and acetic acid single extraction procedures were applied to sewage sludge and sediment samples. The results obtained with these samples for Cu, Cr, Ni, Pb and Zn using the Tessier method were compared with those supplied by the two single extraction procedures employed. In addition, the Tessier method was also applied to a reference material, CRM 483, and these results were also compared with the certified EDTA and acetic acid values for this sample. As a result, good agreement was found between the metal contents released in the first three fractions of the Tessier method and those leached by the simpler single extraction procedures for the most of the elements studied. Subsequently, the conventional EDTA and acetic acid extraction methods were accelerated by means of microwave energy, in order to reduce the operating time. The extraction efficiency of the first three fractions of the Tessier method was compared with that obtained using the optimised microwave single extraction procedures and only in sewage sludge and CRM 483 samples were satisfactory results found for all the elements studied, except Cr and Pb. This means that the microwave single extraction procedures optimised in this work could be employed as screening methods to evaluate rapidly the easiest mobilizable heavy metals in these samples, although more samples should be analysed to determine their general applicability. The application of the accelerated single extraction procedures to a reference material, CRM 483, provided satisfactory results for all the elements studied, except for Cr in both methods and for Pb in the acetic acid extracts.     

Experimental Designs in the Optimization of a Microwave Acid Digestion Procedure for the Determination of Metals in Paper and Board Samples by Atomic Absorption Spectrometry

Abstract

A Plackett-Burman design was carried out in order to find the significant experimental parameters affecting Cd, Co, Cr, Cu, Mn, Pb, and Zn extraction by microwave energy in paper samples. Eight variables were studied and optimized by means of a factorial design. The design showed that HCl and HNO₃ concentrations were the significant parameters in the microwave extraction procedure. The trace elements were determined by FAAS and ETAAS under optimum conditions. The levels of metals present in commercial samples, representing different types of paper and board and manufacturers are lower than those provided by the legislation.     

Comparison of Two Sequential Extraction Procedures for Trace Metal Partitioning in Sediments

Abstract

Two sequential extraction schemes (a modified Tessier procedure with five steps and a three steps protocol designed by BCR) are applied to four sediment samples with different heavy metal contents. The results obtained for Cd, Cr, Cu, Ni, Pb and Zn partitioning show that the metal distribution obtained with both procedures are significantly different. With the second procedure amounts of all the heavy metals are extracted with the oxidizing reagent (third fraction) whereas with the first one the non residual metals are distributed among the second, third and fourth fractions (acetic acid-acetate buffer (pH=5), reducing and oxidizing reagents respectively). The residual fraction obtained applying the three steps procedure is in general higher than that obtained using the five steps procedure, except for cadmium.     

Selectivity assessment of a sequential extraction procedure for metal mobility characterization using model phases

This study considers the selectivity of the extractants used in a sequential extraction scheme for metals mobility assessment by analyzing individual mineral phases previously coprecipitated or sorbed with trace metals. The scheme evaluated was a modification of the Tessier et al. [A. Tessier, P.G.C. Campbell, M. Bisson, Anal. Chem. 51 (1979) 844] sequential procedure proposed by the authors. The phases studied were calcite, amorphous iron oxide, hausmannite, humic acid, kaolinite and illite. Selective extractions were obtained for As, Cr, Cu, Ni, Pb and Zn in metal-coprecipitated phases whereas NH(2)OH-HCl was not selective for the extraction of Hg and Cd coprecipitated in hausmannite and amorphous iron oxide, respectively. Otherwise, Cd, Hg, Ni and Zn sorbed on the different phases were released with MgCl(2) and NaOAc/HOAc, but stronger reagents were needed to release As, Cr, Cu and Pb.     

Determination of heavy metals in air conditioner dust using FAAS and INAA

The elements Cd, Cr, Cu, Mn, Ni, Pb and Zn were determined in dust samples collected from air conditioner (AC) filters from 15 commercial sites of Lahore using flame atomic absorption spectroscopy (FAAS). The elements Cr, Mn and Zn were also determined using instrumental neutron activation analysis (INAA). The results obtained showed that higher amounts of these metals were measured in these dust samples than normally found in soil. This was especially true for Cd, Cu, Pb and Zn. Generally the amounts of Cd, Cr and Mn did not vary throughout the city of Lahore but the amounts of the traffic related Cu, Pb and Zn elements had the more variable ranges of 30–140, 30–230 and 74–2810 mg/kg respectively. The concentrations obtained for Cr, Mn and Zn by INAA were found to be higher than those obtained using FAAS. Analysis of the data obtained showed the digestion procedure employed to be the possible cause for this occurrence. It was also found that Mn was being over-estimated by INAA due to the interference from the Mg peak.     

Ultrasound-Assisted Extraction for the Evaluation of Element Mobility in Bottom Sediment Collected at Mining and Smelting Pb–Zn Ores Area in Poland

The current BCR procedure for metal fractionation recommended by the Standard Measurement and Testing Programme requires rather time-consuming sample pretreatment. Ultrasonic energy seems to be an attractive alternative for leaching metal from solid samples into a liquid extractant phase. This study aims at optimizing ultrasonic extraction in order to replace the BCR method of leaching using acetic acid and to apply the procedure of assessing element mobility in bottom sediment rich in moderately soluble carbonate minerals. The application of ICP-MS allowed the determination of As, Cd, Cr, Cu, Pb, Ni, Tl and Zn in extracts, in a wide range of concentration without any special treatment. Finally, 40’min extraction in an ultrasonic bath was proposed for evaluation of the mobile fraction of As, Cd, Cr, Cu, Pb and Zn as an assessment of environmental risk. The recovery of the ultrasound-assisted extraction in comparison to the shake-filter method, as applied in the common BCR procedure, was slightly higher than 100% for As, Cr and Pb, reasonably high (about 70%) for Cd, Zn and Cd, but did not exceed 21% for Tl. Also, the mobility and extractability (relative mobility) of the studied elements from sediment collected over one year were compares. According to the results obtained after 40’min of ultrasound-assisted extraction it can be concluded that mobility did not change over one year for Cr, Cu, As, Cd, Ni and Tl, but noticeable differences for Zn and Pb were observed. The total content of all studied elements was almost the same in samples taken in the years 2003 and 2004, respectively.     

Three-stage sequential extraction procedure for metal partitioning in polluted soils and sediments

The sequential extraction procedure proposed by the Standard, Measurements and Testing program "SM&T" of the European Union has been applied to evaluate the amounts of Cr, Cu, Mn, Ni, Pb and Zn, extracted at each stage and indirectly their mobility and bioavailability in soil and sediment samples from a polluted area. Analysis of the extracts was carried out by flame atomic absorption spectrometry (FAAS). No significant matrix interferences were found except for Cr in the acetic acid and hydroxylammonium chloride extracts, which required determination by the standard additions method. Both of soils and sediments studied show similar partitioning of Mn, Ni, Cu and Cr. Mn and Ni can be considered to have significant component bound to the acido-soluble fraction, whereas, Cr and Cu occur largely in the organic and residual phases. The partitioning of Pb and Zn was different between soil and sediment. In terms of mobility and bioavailability, in soils, Ni and Mn can be regarded as moderately available followed by a lower availability of Pb while Cu, Zn and Cr have a very limited availability. In sediments, a higher availability (short-medium term) of Mn and Zn was presumed followed by a lower availability of Ni and Pb, whereas, Cu and Cr, occurring largely in the organic and residual phases, were of very limited availability.     

Chemical Aspects of Heavy Metal Solubility with Reference to Sewage Sludge Amended Soils

Abstract

The long term benefits of applications of sewage sludges to land as an alternative source for plant nutrients are frequently limited by potentially toxic contents of heavy metals. While upper limits for metal contents in amended soils have been defined in both North America and Europe, there has been little attention paid to the fate of the metals if soil management practices are changed and the solubility and hence the mobility of the metals increased. This study investigated the role of changes in pH and additions of chloride ions to the content of soluble Cd, Co, Cr, Cu, Pb, Ni, V and Zn in soils to which sewage sludge had been applied. The contents of soluble metals ranged from less than 1 μmol L^?1 for V to 500 μmol L^?1 for Zn. For all the metals, contents were greater in the presence of Cl^? ions and increased markedly as the pH decreased below about pH 5. Contents of V, Cr, Cu and Pb increased at pH's above 7. As all metal contents were undersaturated with respect to hydroxide or carbonate precipitates, the changes in their contents were probably related to desorption from variable charge sites on mineral and/or humic surfaces.     

New Sediment and Soil CRMs for Extractable Trace Metal Content

Abstract

The lack of uniformity in leaching procedures used to measure broadly defined forms of heavy metals does not allow the results to be compared world-wide nor the methods to be validated since the results obtained are “operationally defined”. An attempt was made to certify several mineral soils CRMs for single extraction by using acetic acid, EDTA and DTPA for Cd, Cr, Cu, Ni, Pb and Zn. Recently, to complete the series of soil CRMs, an organically enriched soil was prepared SO25. For sediments a CRM 601 was produced and certified for metals extractable by using the BCR three step sequential extraction. Not all the trace elements were certified and only indicative values were given for some of them due to poor reproducibility. We performed a systematic study of the effect of the variables identified as potential sources of uncertainty in the use of this scheme. With this study the sources of uncertainty were revealed and an optimised version of the protocol was proposed. With this new version it was possible to certify all the trace elements studied. New sediment material S33 is now proposed for certification and additional data are given for the sediment CRM 601. This modified procedure was also applied to a soil CRM 483 and good results were obtained. This procedure may thus be applied to polluted soils.     

Availability of metals and radionuclides present in phosphogypsum and phosphate fertilizers used in Brazil

Phosphogypsum (PG) is a by-product of the phosphate fertilizer industry. In Brazil, three main phosphate industries are responsible for the production of 5.5 × 10⁶ metric tons of PG per year, which is stored in stacks. Part of this by-product can be reused to improve fertility of agricultural soils. For its safe application, it is necessary to characterize the impurities (metals and radionuclides) present in PG and to evaluate their availability to the environment. The main objectives of this paper are: to determine the total concentration of radionuclides (²²⁶Ra, ²²⁸Ra and ²¹⁰Pb) and metals (As, Cd, Cr, Co, Cu, Hg, Ni, Pb, Se, Zn) in the Brazilian PG samples using different methodologies, to evaluate the available fraction of these elements in the PG samples using a methodology with mild leaching with EDTA, to compare the results obtained for PG samples with those obtained for the most used phosphate fertilizers. The total concentration obtained for the metals using methodologies with different initial digestion (strong attack with acids and HF and mild attack with nitric acid) are slightly different. The results obtained using the methodology with mild leaching showed that the metals and radionuclides are not available to the environment, giving evidence that the application of PG in agriculture is safe as far as contamination by such elements. PG presented metals concentration lower than the phosphate fertilizers. The results obtained for the PG samples, for As, Cd, Cr, Hg, Ni, Pb and Se, are below the limits established by the Brazilian Regulatory Agency.     

Different Lubricating Oil Treatments for the Determination of Cu,Cr, Fe,Ni, Sb,Pb, and Zn by HR-CS FAAS

Abstract

Microwave-assisted acid decomposition, direct dilution in kerosene, and oil-in-water emulsion were evaluated as lubricating oil pretreatment procedures for Cu, Cr, Fe, Ni, Pb, Sb, and Zn determination by High-Resolution Continuum Source Flame Atomic Absorption Spectrometry (HR-CS FAAS). For wet digestion, results were compared with those obtained by Flame Atomic Absorption Spectrometry (FAAS). The ultrasound probe used in emulsions sonication contaminated samples with Cr, although better results have been observed for the other six elements in this condition. In general, recovery percentages ranging from 81–106% (Cu), 80–107% (Cr), 85–114% (Fe), 82–116% (Ni), 86–117% (Pb), 85–115% (Sb), and 81–114% (Zn) were obtained. The HR-CS FAAS showed to be faster and more sensitive than FAAS.     

Evaluation of serum metal profile in relation to biri smoking using ICP-MS

The metals intake through tobacco smoking is associated with adverse effects for human health. The present study was aimed to understand the effects of biri smoking on smoker’s serum metal profile. Seven metals, cadmium (Cd), nickel (Ni), lead (Pb), chromium (Cr), copper (Cu), iron (Fe) and zinc (Zn), were analysed in serum samples of 20 biri smokers and 20 non-smokers from North India. The Cd, Ni, Pb, Cr and Cu concentrations were higher while Fe and Zn concentrations were lower in smokers compared to non-smokers. The Fe concentrations, the highest among all metals, seemed to be unassociated with the smoking activity. This study indicated that biri smoking is a contributor to the body burden of Cd, Ni, Cu and Cr in the smoker’s body. The Cd, Ni, Cu and Fe concentrations are non-significantly associated with the age of smokers at p < 0.01 significance level, whereas Pb and Cr concentrations increase and Zn concentrations decrease with the increase in the age of smokers. Serum metal concentrations in the smoker subjects of North India are higher compared to the results of other similar studies. This could be linked to the poor quality of tobacco used in biri. We recommend conducting more detailed and controlled studies in this regard as a smoker is also subjected to other sources of exposure to metals.     

Fractionation of heavy metals in sediment by using microwave assisted sequential extraction procedure and determination by inductively coupled plasma mass spectrometry

In this work, a fast microwave assisted extraction procedure was developed and optimized for the heavy metals (Cu, Ni, Cr, Pb and Cd) partitioning in the three-stage sequential extraction procedure proposed by the European Standards, Measurements and Testing (SM&;T) Program, formerly the Community Bureau of Reference (BCR). The microwave oven procedure was optimized to obtain extraction efficiencies similar to the conventional BCR procedure, in less time, while using smaller volumes of reagents. In the optimization process, three variables (extraction time, ramping time and microwave power) were considered as factors and as a response the concentration of different metal ions in each individual BCR fraction. Interactions between analytical factors and their optimized levels were investigated using a central composite design. Extractable metals obtained by both comparable methodologies were measured by inductively coupled plasma mass spectrometry. With the use of optimal microwave conditions, steps 1–3 of the sequential extraction (including the hydrogen peroxide digestion in step 3) could be completed between 21 and 22 min. Detection limits were between 1 and 18 ng l^{− 1}. The accuracy of the proposed method was checked with a certified reference material (CRM) of Lake Sediment BCR 701. Values obtained were in accordance with those reported for the certified material with only a few exceptions. Different origin sediments (river and marine) were analyzed by both BCR and MW procedures, and the results obtained were comparable according to the t-paired-test for a 95% confidence level.     

黔产市售绿茶重金属的含量特征及健康风险评估

为研究黔产市售绿茶中重金属的含量分布特征及健康风险,以五个生产加工地的黔产市售绿茶为研究对象,分析其9种重金属(Pb、Cr、Cd、Hg、Cu、Zn、Mn、Ni和As)含量,利用美国环境保护署(USEPA)推荐的健康风险评价模型进行人体重金属的健康风险评价。结果表明,五种茶叶中Cr、Cd、Pb、Hg、Cu和As含量均低于国家限量标准。黔产市售绿茶的重金属浸出率大小次序为Zn>Mn>Hg>As>Cd>Pb>Cr>Cu>Ni。健康风险评价结果表明,五个产地的绿茶中重金属通过饮茶途径所产生的健康危害个人年风险大小次序为Cd>As>Mn>Ni>Cr>Hg>Pb>Zn>Cu,茶叶中重金属通过饮茶途径所产生的个人健康危害年风险总和为4.33×10-6~5.73×10-6 a-1,均低于USEPA和ICRP推荐的最大可接受风险水平,表明重金属引起的健康危害极小,其对暴露人群造成的健康危害可忽略不计,绿茶中重金属均处于安全范围内。     

Inductively Coupled Plasma Mass Spectrometry for Sequential Determination of Trace Metals in Rain and River Waters Using Electrothermal Vaporization

Abstract

The sequential determination of 14 trace metals, Al, V, Cr, Mn, Fe, Ni, Cu, Zn, As, Se, Mo, Cd, Sb and Pb, in rain and river water samples has been investigated using an inductively coupled plasma mass spectrometry (ICP-MS) with a graphite rod electrothermal vaporizer (ETV) in the presence of the mixed modifier of palladium nitrate and magnesium nitrate. The sensitivity enhancements due to the presence of the modifier were observed for all analyte elements. Detection limits as high as 0.52, 0.13, 0.89, 0.35, 1.76, 0.5, 0.9, 0.5, 0.04, 1.03, 0.28, 0.07, 0.1 and 3.78 pg, respectively, for Al, V, Cr, Mn, Fe, Ni, Cu, Zn, As, Se, Mo, Cd, Sb and Pb have been achieved. For the determination of trace metals in both rain and river water samples by this method, the repeatibility of sample solution were very good, i.e. from 1% to 7% (as a coefficient variation) and the recoveries of elements were good enough, i.e. from 81% to 106%, by using a standard addition method. There was no difference between the results obtained by nebulizer ICP-MS and those obtained by this method, except for zinc and arsenic.