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It is believed that knowing the speciation of metals is advantageous in understanding and managing the geochemical behavior of mine tailings with respect to potential metal pollution. Accordingly, a three-step sequential extraction was carried out by modified European Community Bureau of Reference (BCR) approach for fractionation of metals in Balya Pb/Zn tailing. Acetic acid leaching, hydroxylamine hydrochloride + nitric acid leaching, hydrogen peroxide + acid ammonium acetate leaching, and orthophosphoric + nitric acid digestion in microwave were performed to determine ion exchangeable (F1), reducible (F2), oxidizable (F3), and residual (F4) fractions of metals, respectively. As a result, the highest readily soluble fractions were obtained for Ca, Cd, Zn, Pb, Mn and Cu, respectively; while reducible fraction were determined as Pb, Cu, Ag, Zn, Mg and Mn. Almost all K, Ti, and Al metals were detected in the residual fraction. Multivariate analyses were carried out and the fractional distribution similarity of metals was statistically determined as three different clusters. In one of the clusters, Co and Ni, which are mainly found in the oxidizable fraction, were placed, while toxic metals of Pb, Cd, and Cu were found to be statistically grouped in a different cluster. [ABSTRACT FROM AUTHOR]

The metal profiles in sediments of the Daya Bay (DYB) in China were established using sequential extraction protocols proposed by the European Community Bureau of Reference (BCR). The surface sediment samples from 23 representative stations were collected in 2011 and were analysed to evaluate the mobility and bioavailability of a suite of potentially toxic metals (Cr, Cu, Ni, Zn, Pb and Cd) and metalloid (As). The obtained ranking order of migration and transformation, and the degree of pollution was Pb > Cd > Cu > Zn > Ni > Cr > As. Among these elements, Pb is considered to pose a serious threat to human health and ecological environment due to its significant percentage in non-residual form. The ratios of secondary and primary phases showed that studied sediments are moderately to heavily polluted with Cu and Zn, and Cd and Pb respectively. The levels of association between the variables (metal-metalloid) at each step of sequential extractions were evaluated with multivariate statistical analysis, including correlation analysis and principal components analysis. With these analyses, the possible sources of potential pollution were deduced. The correlation analysis revealed that Total Organic Carbon content is the most important influencing factor affecting the distribution of potentially toxic elements in Daya Bay. The principal components analysis (PCA) suggested that the studied elements in DYB area originate primarily from natural weathering and secondly from industrial wastewater and aquaculture waste water.

Insights in the knowledge of the Antarctic atmospheric composition of Cd, Pb, and Cu are obtained by chemical fractionation of metals in the aerosol to obtain water-soluble (soluble), dilute HCl-extractable (extractable), and inert fractions. The aim is to correlate chemical fractions to metal sources. A three-step sequential extraction and square wave anodic stripping voltammetry were applied to analyze aerosol samples (PM10) collected during summer near the 'M. Zucchelli' Italian Station (Victoria Land). Metal mass fractions varied as follows (min-max, average, in μg g): Cd 1.4-38 (11), Pb 26-83 (47), and Cu 150-840 (490). In terms of atmospheric concentrations, the values were as follows (pg m): Cd 0.93-39 (9.5), Pb 17-60 (33), and Cu 88-480 (340). The soluble fraction relates to the marine contribution. The extractable fraction refers mainly to local human activity. The inert fraction is associated with the crustal dust. Soluble, extractable, and inert metal fractions changed very much during the Austral summer according to changes of source types and strengths. The observations on the temporal trends, the relationships with wind direction and speed, and the correlations between the same fractions of different metals, together with results of principal component analysis, agreed with the stated associations between chemical fractions and major sources. Fractionated data are among the first even published in Antarctic research. [ABSTRACT FROM AUTHOR]

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Abstract: A sequential extraction procedure was applied to acid sulfate soil materials from a soil profile to investigate the effect of sample pretreatment on the geochemical fractionation of selected metals. The samples were prepared for analysis by oven-drying, sieving and grinding the soil, or were examined as collected in field condition. The soil profile encompassed oxidising conditions near the surface, through to reducing conditions at depth. Six metals (Fe, Cr, Ni, Mn, Cu, and Zn) were measured during the sequential extraction procedure, and their fractionation determined in the oxidised and in the reduced zone. Although cumulative totals (the sum of all steps in the sequential extraction procedure) for the metals extracted from both the field condition and dried/ground samples were similar, some significant differences in fractionation within individual extraction steps were observed. Of particular interest was the redistribution of metals from the sulfide-bearing (pyrite-bound) fraction to the more readily available fractions (i.e. labile and acid-soluble), as a result of oven-drying and grinding. The results indicate that when assessing metal fractionation in acid sulfate soil materials, samples should be analysed in field condition in order to avoid the considerable metal fractionation artifacts that are induced by drying and grinding. [ABSTRACT FROM AUTHOR]

Abstract: Chromated copper arsenate (CCA)-treated wood was liquefied with polyethylene glycol/glycerin and sulfuric acid. After liquefaction, most CCA metals (98% As, 92% Cr, and 83% Cu) were removed from liquefied CCA-treated wood by precipitation with calcium hydroxide. The original CCA-treated wood and liquefied CCA-treated wood sludge were fractionated by a modified Community Bureau of Reference (BCR) sequential extraction procedure. The purpose of the BCR-sequential extraction used in this study was to examine the availability of CCA metals in treated wood for reuse. Both As and Cr had a slightly higher concentration in the sludge sample than in original CCA-treated wood. The sequential extraction showed that As and Cr were principally existed in an oxidizable fraction (As, 67%; Cr, 88%) in original CCA-treated wood. Only 1% of both As and Cr were extracted by hot nitric acid with the last extraction step. The distribution of As and Cr changed markedly in liquefied CCA-treated wood sludge. The amount of As in the exchangeable/acid extractable fraction increased from 16% to 85% while the amount of Cr increased from 3% to 54%. Only about 3% of As was present in the oxidizable fraction. However, there was still about 34% of Cr in the same fraction. Based on these results from sequential extraction procedures, it can be concluded that the accessibilities of CCA metals increase markedly by the liquefaction–precipitation process. [Copyright &y& Elsevier]

The Odiel salt marshes (Marismas del Odiel) are an important nature area declared a Biosphere Reserve, but they are greatly affected by pollution from the Odiel River. Surface sediments from this area were analysed using the latest version of the BCR sequential extraction procedure to determine the fractionation of As, Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn among four geochemical phases (acid-soluble, reducible, oxidisable and residual). The total content of each of the metals and As was also determined. The results showed high concentrations of As, Cd, Cu, Pb and Zn, with maximums of 791 mg kg−1 of As, 8.5 mg kg−1 of Cd, 2,740 mg kg−1 of Cu, 1,580 mg kg−1 of Pb and 3,920 mg kg−1 of Zn. The concentrations of Cr, Mn and Ni were low since there are no sources of pollution by them in the area. A comparison of the metal and As levels with the sediment quality guidelines showed that the pollution is sufficient to produce noxious effects in aquatic organisms in most of the Odiel salt marshes. Based on the chemical distribution of the elements, it was found that Cd and Zn were the most mobile (i.e., elements that can pass easily into the water under changing environmental conditions). However, Cr, Fe, Ni and As were present in the greatest percentages in the residual fraction, which implies that these elements are strongly linked to the sediments. [ABSTRACT FROM AUTHOR]

Abstract: Recently a novel approach to perform sequential extractions (SE) of elements in solid samples was developed by this group, based upon the use of a sequential injection (SI) system incorporating a specially designed extraction microcolumn. Entailing a number of distinct advantages as compared to conventional batch methods, this fully automated approach furthermore offers the potentials of a variety of operational extraction protocols. Employing the three-step sequential extraction BCR scheme to a certified homogeneous soil reference material (NIST, SRM 2710), this communication investigates four operating modes, namely uni-, bi- and multi-bi-directional flow and stopped-flow, allowing comparison of the metal fractionation profiles. Apart from demonstrating the versatility of the novel approach, the data obtained on the metal distribution in the various soil phases might offer valuable information as to the kinetics of the leaching processes and chemical associations in different soil geological phases. Special attention is also paid to the potentials of the microcolumn flowing technique for automatic processing of solid materials with variable homogeneity, as demonstrated with the sewage amended CRM483 soil which exhibits inhomogeneity in the particle size distribution. [Copyright &y& Elsevier]