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.     

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.     

Assessment of heavy metals leachability from metallo-organic sorbent-iron humate-with the aid of sequential extraction test

The sequential extraction test, known as a BCR procedure, was used to assess a leachability of heavy metals (Zn, Cd, Pb, Cu) from the metallo-organic sorbent—iron humate—loaded with these metals. The sequential test allowed to discriminate between various fractions of heavy metals, namely the acid-extractable fraction, the fraction bound to Fe oxides, and the fraction bound to organic matter. It was proven that the heavy metals are bound mainly to Fe oxides and organic matter, and thus they may be relatively hardly liberated into the environment. The BCR sequential extraction test exhibited a very good repeatability, when it was applied to the loaded sorbent—relative standard deviations were typically lower than 10%.     

Kinetic speciation of BCR reference materials

The accurate study of heavy metal speciation is important in environmental monitoring. There has been much work developing various operationally defined speciation methods for soil and sediment, but there is a need to compare the different approaches by evaluating them for the same sample. In this article, a kinetic method was applied for the heavy metal speciation of the two BCR reference materials, CRM601 and BCR701, which have been specifically developed as materials to evaluate the validated BCR three-step sequential extraction method. When EDTA was used as an extractant, 81.0% of Cd, 68.0% of Cu, 21.5% of Ni, 80.3% of Pb and 71.9% of Zn was extracted from CRM601. For BCR701, the removal ratios were 92.0, 52.3, 18.7, 50.6 and 67.5% with EDTA and 95.7, 25.2, 20.0, 52.4 and 68.5% with hydroxylamine hydrochloride as an extractant, for Cd, Cu, Ni, Pb and Zn respectively. A two-component kinetic model was applied to the extraction curve and the extractable metals were readily classified into two categories, namely, labile fraction and non-labile fractions. The rate constants obtained from the regression model were found to be useful in quantifying the lability of an element. The rate constants obtained from the labile fractions in BCR701 were higher than that of obtained from CRM601, which indicated the high lability of metals in BCR701. When compared with the sequential extraction data, it seemed that the lability of an element was positively correlated to the first step extraction fraction.     

A comparison of an optimised sequential extraction procedure and dilute acid leaching of elements in anoxic sediments, including the effects of oxidation on sediment metal partitioning

The effect of oxidation of anoxic sediment upon the extraction of 13 elements (Cd, Sn, Sb, Pb, Al, Cr, Mn, Fe, Co, Ni, Cu, Zn, As) using the optimised Community Bureau of Reference of the European Commission (BCR) sequential extraction procedure and a dilute acid partial extraction procedure (4 h, 1 mol L⁻¹ HCl) was investigated. Elements commonly associated with the sulfidic phase, Cd, Cu, Pb, Zn and Fe exhibited the most significant changes under the BCR sequential extraction procedure. Cd, Cu, Zn, and to a lesser extent Pb, were redistributed into the weak acid extractable fraction upon oxidation of the anoxic sediment and Fe was redistributed into the reducible fraction as expected, but an increase was also observed in the residual Fe. For the HCl partial extraction, sediments with moderate acid volatile sulfide (AVS) levels (1-100 μmol g⁻¹) showed no significant difference in element partitioning following oxidation, whilst sediments containing high AVS levels (>100 μmol g⁻¹) were significantly different with elevated concentrations of Cu and Sn noted in the partial extract following oxidation of the sediment. Comparison of the labile metals released using the BCR sequential extraction procedure (ΣSteps 1-3) to labile metals extracted using the dilute HCl partial extraction showed that no method was consistently more aggressive than the other, with the HCl partial extraction extracting more Sn and Sb from the anoxic sediment than the BCR procedure, whilst the BCR procedure extracted more Cr, Co, Cu and As than the HCl extraction.     

氧化与还原条件下伊通河长春区段沉积物重金属形态特征的对比研究

利用改进的Tessier连续萃取法研究了伊通河长春市自由大桥处不同深度沉积物样品在氧化及还原条件下Cu,Pb,Zn和Ni的形态变化规律,同时分析了沉积物样品中酸可挥发性硫(Acid volatile sulfide,AVS)和同时提取重金属(Simultaneous extract metals,SEM)的含量. 实验结果表明，样品经干燥、研磨处理后,Cu有机/硫化物结合态比例减少40%,锰氧化物结合态的比例显著增加; Pb,Zn和Ni 3种元素有机/硫化物结合态比例均略有下降,变化幅度小于Cu,并重新分配到不同的化学相中. 通过SEM中各金属含量与有机/硫化物结合态中金属含量的对比可知,还原性沉积物中Cu除了与硫化物结合外,很大一部分是以有机物形态存在的,Pb,Zn,Ni,Fe和Mn则主要以硫化物形态存在,各元素形态分析均不同程度地受到萃取剂的影响.     

Effect of ultrasound agitation on the release of heavy elements in Certified Reference Material of human hair (CRM BCR 397)

An ultrasonic-assisted leaching procedure was developed for the determination of heavy elements (As, Cu, Cd, Pb, and Zn) in Certified Reference Material of human hair (CRM 397) provided from the Community Bureau of Reference (BCR) of the Commission of the European Community. Concentrated nitric acid-30% hydrogen peroxide (2 + 1) was used for the leaching method. The effects of different factors on acid leaching of elements, such as presonication time (without ultrasonic stirring), sonication or exposure time to ultrasound, and temperature of the ultrasonic bath have been investigated. Optimum values of these parameters were selected for the maximum extraction of heavy metals from CRM BCR 397 and human scalp hair samples of normal healthy males. To check the validity of the proposed method, a wet acid digestion method was used to obtain the total elemental concentration in CRM BCR 397 and scalp hair samples. Cu and Zn in leachate and digests were measured by flame atomic absorption spectrometry using a conventional air/acetylene flame, while As, Cd, and Pd were determined by electrothermal atomic absorption spectrometry. Under optimized conditions, the recovery for Zn, Cd, Pd, As, and Cu was 98, 98.5, 97.5, 98.2, and 95%, respectively, of those obtained with the wet acid digestion method.     

A study of trace element contamination in river sediments in Serbia using microwave-assisted aqua regia digestion and multivariate statistical analysis

The aim of this study was the evaluation of the trace element contamination level in sediments of the most important rivers in Serbia and their tributaries. The determination of the aqua regia soluble contents of 12 micro- and macro-elements (Ca, Cd, Co, Cr, Cu, Fe, Mn, Pb, Ni, Zn, Be and V) in sediments was developed by the microwave digestion technique combined with inductively coupled plasma atomic emission spectrometry. Correlation analysis and principal component analysis distinguishes factors of lithogenic and anthropogenic origins. The Fe, Mn, Be and V contents are controlled by a regional lithogenic high background factor, while Cd, Cr, Pb, Ni, Zn and Cu are recognized as tracer of pollution. For Co, mixed sources from both lithogenic and anthropogenic inputs were evidenced.The investigated sediment of the major rivers and their tributaries in Serbia showed high concentrations of metals, especially of Cd, Pb, Cu and Zn, which may cause serious environmental impacts. Rivers which flow into the Danube from its entrance into Serbia significantly influence the chemical load of the water and sediments.The experimental study was conducted using two BCR standard reference materials. The calculated accuracy and precision confirmed the good performance of the adopted procedures.     

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。     

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.     

Microwave digestion of sediment, soils and urban particulate matter for trace metal analysis

A microwave digestion technique was developed to determine the content of nine heavy metals in sediments and soils. The digests were subsequently analysed by inductively coupled plasma-atomic emission spectroscopy (ICP-AES). The metals determined were Ca, Mg, Fe, Mn, Zn, Cr, Cd, Cu, Pb and V. The digestion was achieved by using an acid mixture of HNO₃, HF and distilled H₂O. The experimental study was conducted using four standard reference materials (SRMs): sewage sludge (LGC6136), marine sediment (PACS-1), urban particulate matter (NIST 1648) and coal carbonisation site soil (LGC6138). Two different programs were examined to determine which was optimal for the digestion of real environmental samples. The accuracy and precision of the two digestion programs for the analysis of the SRMs were compared. From the results obtained, the microwave program providing a maximum of power of 650 W and a cycle time of 51 min resulted in the best analytical performance. The experimental results obtained were in good agreement with the certified values and demonstrated that the proposed method is precise and accurate.     

Comparison of different digestion methods for total decomposition of siliceous and organic environmental samples.

A comparison was made of different digestion methods for the total decomposition of siliceous and organically environmental samples prior to their analysis by inductively coupled plasma optical emission spectrometry (ICP-OES). In the present study, three different digestion methods, including microwave-assisted, hot plate heating and pressurized digestion (pressure bomb), were employed for the determination of nine heavy metals, i.e. Ag, Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn in sediment, soil, sludge and oil. The investigation of different combinations of acids through their analytical performance demonstrated that HCl plays a vital role in the determination of silver. The combination of HNO3 and HCl possesses more reactive ability in oxidizing organic matter. The recoveries of all elements of interest in sediment (NIST 2704) obtained by different digestion methods were found to be 86% to 113%, while microwave assisted digestion with various combinations of HNO3-HCl-HF and HNO3-HClO4-HF was considered to be a viable alternative to the conventional digestion systems because of its more intensive reaction conditions. The analytical results of four certified reference materials with different matrices, including sediment (GBW 07305), soil (GBW 07411), sludge (BCR R-143) and oil (NIST 1085a), by the microwave-assisted acid digestion method indicated that the recoveries of all elements of interest were more than 85% and the throughput of applied analytical method could be elevated significantly.     

Utilization of optimized BCR three-step sequential and dilute HCl single extraction procedures for soil-plant metal transfer predictions in contaminated lands

The prediction of soil metal phytoavailability using the chemical extractions is a conventional approach routinely used in soil testing. The adequacy of such soil tests for this purpose is commonly assessed through a comparison of extraction results with metal contents in relevant plants. In this work, the fractions of selected risk metals (Al, As, Cd, Cu, Fe, Mn, Ni, Pb, Zn) that can be taken up by various plants were obtained by optimized BCR (Community Bureau of Reference) three-step sequential extraction procedure (SEP) and by single 0.5 mol L(-1) HCl extraction. These procedures were validated using five soil and sediment reference materials (SRM 2710, SRM 2711, CRM 483, CRM 701, SRM RTH 912) and applied to significantly different acidified soils for the fractionation of studied metals. The new indicative values of Al, Cd, Cu, Fe, Mn, P, Pb and Zn fractional concentrations for these reference materials were obtained by the dilute HCl single extraction. The influence of various soil genesis, content of essential elements (Ca, Mg, K, P) and different anthropogenic sources of acidification on extraction yields of individual risk metal fractions was investigated. The concentrations of studied elements were determined by atomic spectrometry methods (flame, graphite furnace and hydride generation atomic absorption spectrometry and inductively coupled plasma optical emission spectrometry). It can be concluded that the data of extraction yields from first BCR SEP acid extractable step and soil-plant transfer coefficients can be applied to the prediction of qualitative mobility of selected risk metals in different soil systems.     

煎煮对几种特色南药中重金属元素含量和形态影响

考察了几种特色南药中重金属(Cd,Cr,Cu,Fe,Mn,Ni,Pb,Sr,Zn)的含量状况,并采用形态连续萃取法分析重金属在药材中的形态分布,研究了药材煎煮时药材中重金属的释放及煎煮过程对药材中重金属形态分布的影响。结果表明,几种南药中Cr,Pb,Zn的含量较高,且巴戟天中的重金属总量高于限量标准;原药材中Cr,Cu,Mn,Ni,Pb和Zn主要存在于有机态和残留态,Fe和Sr主要存在于残留态。煎煮使南药中大量重金属迁移到药汤中;药汤中Cu,Mn,Cr,Pb和Zn主要来自于其在药材中的可交换态、碳酸盐结合态和有机态,而药汤中Sr,Ni和Fe不仅包含其非残留态,更多来自于它们的残留态。为减少药汤中重金属,对于Cu,Mn,Cr,Pb和Zn既要控制在药材中的总量,且需降低它们在药材中的非残留态含量;对于Fe,Ni和Sr则主要是控制其在药材中的总量。     

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.     

芝罘湾表层沉积物中重金属的分布特征及潜在生态危害评价

为了解芝罘湾沉积物中重金属的污染状况,于2009年7月采集了黄海芝罘湾16个站位的表层沉积物并测定了其中的重金属含量.芝罘湾的重金属污染程度较低,所有测定值均低于国家海洋沉积物Ⅰ类质量标准.Hg、Cu、Pb、Cd、Zn、Ni、Co、Mn 8种重金属的平均含量分别为0.02、12.3、8.67、0.13、32.8、11....     

A Sequential Extraction Method Measures the Toxic Metal Content in Fly Ash from a Municipal Solid Waste Incinerator

The purpose of this research was to develop an optimized pretreatment procedure for toxic metals (Pb, Cd, Zn and Cu) content in fly ash from a municipal waste incinerator. In addition, modified sequential extraction procedures were used to characterize the chemical composition of the fly ash samples. The sequential extraction resolved the fly ash elements into the following chemical forms: soluble, exchangeable, carbonate, oxide, organic, and silicate compounds. Certified reference city waste incineration ash (BCR.176) was used as target ash samples. A H₂O₂+HNO₃+HF mixed acid digestion solution with a low temperature evaporation procedure was selected as optimal for the fly ash digestion. The digested solution was analyzed by inductively coupled plasma mass spectrometry (ICP‐MS), which effectively determined the concentrations of the toxic metal elements in BCR.176. Except for Cd, the recovery of Pb, Zn, and Cu under H₂O₂+HNO₃+HF digestion and their sequential extraction procedures were higher than 95%. The relative standard deviations (RSD) for recoveries of the four elements were within 10%. Furthermore, the sequential extraction procedure's results provided information on the potential mobility of the studied elements. Most of the Cd was bound to water‐soluble and carbonate material in the fly ash samples. Most of the Pb, Zn, and Cu was released to carbonates and bound to organic matter in the fly ash samples.     

固体添加剂对垃圾掺烧污泥焚烧飞灰高温过程中重金属挥发特性的影响

在研究垃圾与污泥掺烧后焚烧飞灰中重金属浸出特征的基础上,重点研究了飞灰在1 000 ℃条件下高温处置过程中重金属(Cu、Zn 、Pb、Cd)随不同停留时间的挥发特性及添加剂(CaO、Al₂O₃、SiO₂、高岭土、粉煤灰)对重金属转化与挥发特性的影响。研究结果表明,飞灰中重金属Zn、Pb、Mn含量较高,Ni的含量较低,而毒性较大的Cd达到29.4 mg/kg。浸出液中七种金属都满足危险废物鉴别标准(GB5085.3-1996),并且重金属的浸出浓度受浸取时间及浸取液pH值影响较大。在同样的高温处置条件下,焚烧飞灰中不同重金属的挥发特性有较大的差别。其中,Pb表现出易挥发的特性,其挥发率超过80%,而Cu挥发性较小,其挥发率小于30%。综合来看,飞灰中重金属的挥发性大小依次为Pb>Cd>Zn>Cu。飞灰中添加Al₂O₃和高岭土可以抑制Cd的挥发,添加Al₂O₃后Pb的挥发率有所减少,添加SiO₂、CaO、高岭土、粉煤灰均使Zn的挥发率降低,而对Cu的挥发率没有抑制作用,这与飞灰中高Cl含量及各痕量元素化合物对固体添加剂活性位选择性的竞争吸附有关。     

梅州农村饮用水重金属元素监测与分析

对梅州农村饮用水中的重金属元素进行了监测和分析，选择Fe，Mn，Zn，Cu，Ag，Pb，Cd七种元素为检测指标。从实验结果来看，Cu，Ag，Cd含量低，未超标；Fe，Mn，Zn，Pb有超标现象：按其危害程度，Pb，Mn的超标是急需解决的问题。     

Heavy metal contamination in street dusts of Istanbul (Pendik to Levent) E-5 highway

Street dust composition is an important environmental parameter that should be considered in investigations of environmental pollution originating from traffic. In this study, fifty-six samples of street dusts were collected during the period December 2003-April 2004 from Pendik to Levent on E-5 highway in Istanbul, Turkey. Analyses were determined by graphite furnace atomic absorption spectrometry after digestion using USEPA, 1996 (Method 3050B). The mean concentration levels of Pb, Mn, Zn, Ni, Cd and Cu were found to be 368.3, 747.8, 431.2, 27.1, 0.3 and 191.1 microg/g respectively. Pb, Cu, Zn and Mn mean concentrations in studied areas were higher than levels of these heavy metals according to USEPA (1992) and Republic of Turkey Ministry of Environment and Foresty (2003). Highly significant correlations except for Mn were found between the number of vehicles and heavy metal concentrations.