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This work aimed to detect changes in trace element chemical speciation in sewage sludge (SS) after the ozonation process. The modified Community Bureau of Reference (BCR) sequential extraction procedure was performed to determine the chemical speciation of trace elements in SS after the ozonation process. To assess potential soil contamination with trace elements from sewage sludge after the ozonation process, the risk assessment code (RAC) coefficient was used. The bioaccumulation factor (BAF) and translocation factor (TF) values were also calculated to characterize the efficiency of trace element accumulation in the studied plant species from soil fertilized with sludges after the ozonation process. Generally, the mean concentration of total trace elements in the SS after the ozonation process was higher, but the differences were statistically significant only in the case of Mn, Cu, Pb, and Cd. The dominant fraction of Fe, Cr, Pb, and Cd was the residual fraction F4, while the extractable/exchangeable fraction F1 was present in the smallest amount. Therefore, in the case of Mn, Zn, and Ni, the ozonation process had a significant impact on the increase in the content of these elements in the F1 fraction. The application of the SS stabilized by ozonation process for maize and wheat fertilization did not significantly affect the bioaccumulation of most of the analyzed metals in aboveground biomass. Higher values of BAF coefficients after the application of ozonated SS were found only in the case of Cu and Ni. In turn, the determined TF coefficients were lower than 1 in most cases. The obtained results showed that the slight change in the concentration of Zn, Mn, and Ni in fraction F1 causes a specific risk of their mobility in the soil environment. It should be noted that due to the variable composition of sewage sludge, an analysis of the content of individual trace elements in chemical fractions should be carried out to assess its actual impact on the environment. This can help to indicate further actions that should be undertaken to limit their negative impact on the environment. [ABSTRACT FROM AUTHOR]

This work aimed to detect changes in trace element chemical speciation in sewage sludge (SS) after the ozonation process. The modified Community Bureau of Reference (BCR) sequential extraction procedure was performed to determine the chemical speciation of trace elements in SS after the ozonation process. To assess potential soil contamination with trace elements from sewage sludge after the ozonation process, the risk assessment code (RAC) coefficient was used. The bioaccumulation factor (BAF) and translocation factor (TF) values were also calculated to characterize the efficiency of trace element accumulation in the studied plant species from soil fertilized with sludges after the ozonation process. Generally, the mean concentration of total trace elements in the SS after the ozonation process was higher, but the differences were statistically significant only in the case of Mn, Cu, Pb, and Cd. The dominant fraction of Fe, Cr, Pb, and Cd was the residual fraction F4, while the extractable/exchangeable fraction F1 was present in the smallest amount. Therefore, in the case of Mn, Zn, and Ni, the ozonation process had a significant impact on the increase in the content of these elements in the F1 fraction. The application of the SS stabilized by ozonation process for maize and wheat fertilization did not significantly affect the bioaccumulation of most of the analyzed metals in aboveground biomass. Higher values of BAF coefficients after the application of ozonated SS were found only in the case of Cu and Ni. In turn, the determined TF coefficients were lower than 1 in most cases. The obtained results showed that the slight change in the concentration of Zn, Mn, and Ni in fraction F1 causes a specific risk of their mobility in the soil environment. It should be noted that due to the variable composition of sewage sludge, an analysis of the content of individual trace elements in chemical fractions should be carried out to assess its actual impact on the environment. This can help to indicate further actions that should be undertaken to limit their negative impact on the environment.

The effect of industrial activities on trace metals in farmland of rapidly industrializing regions in developing countries has increasingly been a concern to the public. Here, soils were collected from 13 greenhouse vegetable production (GVP) farms or bases near industrial areas in the Yangtze River Delta of China to investigate the occurrence, speciation, and risks of Cr, Cu, Zn, Cd, Ni, and Pb in GVP soil. The results revealed that the main metal elements causing GVP soil pollution were Cd, Zn, Ni, and Cu, of which contamination levels were generally unpolluted to moderately polluted. Zinc pollution was mainly attributed to heavy fertilization, while Cd, Ni, and Cu pollution may be greatly ascribed to industrial effluents and coal combustion. Metal speciation studies showed that most of Cr, Ni, Cu, and Zn was present in residual fraction while more than half of Cd and Pb was present in non-residual fractions. Additionally, pollution of Cd, Cu, Ni, and Zn in GVP soil increased their corresponding mobile fractions. Risk assessment using potential ecological risk index and risk assessment code showed that Cd was the major risk contributor. Specifically, Cd generally posed moderate or considerable ecological risk as well as displayed medium or high mobility risk in GVP soil. Thus, great attention should be paid to the contribution of both industrial discharges and intensive farming to soil pollution by trace metals, especially Cd, because of its high mobility risk. [ABSTRACT FROM AUTHOR]

Abstract Several sequential extraction procedures are widely applied for metals chemical fractionation in the literature. However, their limitations to be used in different soils and metals have not been discussed in detail. This study compares two of the most commonly used extraction methods for metals chemical fractionation: Tessier and BCR. The objectives were to i) assess the differences between concentrations of metals extracted in each fraction by both Tessier and BCR procedures; ii) elucidate if soil properties affected the extraction ability of each fraction from both procedures; and iii) evaluate how land use contributes to different chemical metal distribution. Results indicated that both methods provide similar results when were applied to the same soil, since non-significant differences were found in metal concentrations between both methods at each fraction. Conversely, when we compared among land uses, significant differences were found in the metal concentration between both methods, especially between agricultural/urban/industrial against forest soil. Redundancy analysis showed that in carbonate-rich soils, BCR extraction method could cover up the real concentration of exchangeable metals with those bound to the carbonate phase, being the Tessier method the most suitable one for this kind of soils. Therefore, although sequential extraction is a useful tool to understand the distribution of metals in soil, the method used must be selected according to the land use and specific soil characteristics, taking into account at least, soil carbonate content. Highlights • Sequential extraction is an useful tool to stablish differences in metal distribution among land uses. • Metal fractionation among land uses depends on the metal concentration. • BCR method can cover up the real behaviour of the exchangeable fraction in calcareous soils. [ABSTRACT FROM AUTHOR]

Wastewater irrigation reduces the pressure on freshwater usage but leads to the accumulation of heavy metal(loid)s in soils. This study investigated heavy metal(loid)s (As, Cr, Cu, Ni, Pb, and Zn) in the acid-soluble (F1), reducible (F2), oxidizable (F3), and residual (F4) fractions of soils from greenhouses and fields in Baiyin City, Gansu, China, which had been irrigated with treated industrial and municipal wastewater. Risk assessment (RAC) and modified risk assessment (mRAC) codes were used to estimate the environmental risks based on metal mobility. Results showed that more than half of each studied heavy metal(loid) (72.6%–97.4%) was present in the residual fraction (F4), which is non-bioavailable. Both the concentrations and percentages of metals in the bio-accessible fractions (F1, F2, and F3) showed no significant differences (p > 0.05) between rhizosphere and bulk soils. The greenhouse soils had higher concentrations and percentages of metals (except Pb) in bio-accessible fractions compared with field soils. Similarly, compared with irrigation using treated municipal wastewater, irrigation with treated industrial wastewater resulted in higher concentrations and percentages of all the studied metals in the bio-accessible fractions of soils. The average RAC value of each heavy metal(loid) in soils suggested medium risks from Zn, low risks from As, Cu, Ni, and Pb, and no risks from Cr. According to the mRAC values for 120 soil samples, there were only 13.3% of soils with no potential adverse effect, but 83.3% of soils with a low potential adverse effect and 3.3% of soils with a medium potential adverse effect. [ABSTRACT FROM AUTHOR]

The European Community Bureau of Reference method (BCR) was used for evaluating the effects of pine bark amendment (0, 24 and 48 g kg −1 ) and ageing (1 and 30 days) on Cd, Cu, Ni, Pb and Zn fractionation, on samples from an acid mine soil. In addition, the stirred flow chamber technique was applied for analyzing heavy metals desorption from the unamended and pine bark amended mine soil. When the unamended soil were not subjected to ageing, the added heavy metals were mainly accumulated as soluble fraction (>90% for Cd, Ni and Zn; 71% for Cu; and 45% for Pb). Pine bark amendment and ageing had little effect on Cd, Ni and Zn fractionation, whereas important changes were detected for Cu and Pb in response to both pine bark amendment and ageing (decrease in the soluble fractions, and increase in less mobile fractions). Desorption experiments showed that both pine bark amendment and ageing decreased heavy metals release from the mine soil. The results of this study indicate that pine bark amendment could be used to increase heavy metals retention (especially in the case of Cu and Pb) in acid mine soils, thus reducing the risks of metal transfer to uncontaminated environmental zones. [ABSTRACT FROM AUTHOR]

The Bureau Commun de Référence (BCR) sequential extraction scheme and micro-synchrotron-based X-ray fluorescence (μ-SXRF) analysis were used to determine the Cu fractionation in a calcareous vineyard soil and a synthetic soil (mixture of seven constituents: calcite, birnessite, ferrihydrite, goethite, lignocellulosic residue, kaolinite, and quartz) at different Cu contamination rates (190, 1270, and 6350 mg kg of Cu) and aging times (1, 30, 92, and 181 days). The Cu distribution in the spiked vineyard and synthetic soils was different from the original vineyard one and was influenced by the loading level. The newly added Cu was preferentially present in the acid soluble fraction. Aging of the contaminated vineyard and synthetic soils during 6 months led to the redistribution of Cu from the weakly bound acid soluble fraction to the strongly bound reducible one. The evolution with time could satisfactorily be simulated by the Elovich diffusion model for the synthetic soils. It was less significant as less marked in the contaminated vineyard soil than in the synthetic one, even though the trends observed in both were similar. This study supported the hypothesis that 'simple' synthetic models could be used to approach the Cu fractionation and its evolution with time in vineyard soils. [ABSTRACT FROM AUTHOR]

Content of 226Ra, 228Ra and uranium isotopes in waters from subsurface aquifers was studied. The sampling points were chosen for having the elevated natural content of iron and manganese. Measurements of radium were made by LSC, while uranium was measured by alpha spectrometry. Waste sludge was measured by gamma spectrometry and three-stage BCR sequential extraction was performed. Radon activity concentration in the air at water treatment plants was determined and dose adsorbed by staff was calculated. [ABSTRACT FROM AUTHOR]

Abstract: The presence of heavy metals in the sludges produced in wastewater treatment plants restricts their use for agricultural purposes. This study looks at different types of sludge (aerobic, anaerobic, unstabilised, sludge from a waste stabilisation pond, sludge from an extended aeration plant and heat treated sludge) and compares the distribution of heavy metals with the treatment that they have undergone. In addition, the total quantity of metals (Cd, Cr, Cu, Ca, K, Fe, Mg, Ni, Na, Pb and Zn) and some agronomic parameters necessary for characterising a sludge as suitable for use as amendment were determined. The BCR method for heavy metal speciation was followed. Principal component analysis (PCA) was applied in order to obtain more information about metal speciation in the sewage sludges. It was confirmed that the concentration of heavy metals did not exceed the limits set out by European legislation and that the stabilisation treatment undergone by the sludges strongly influenced the heavy metal distribution and the phases to which they were associated. The waste stabilisation pond sludge, which has undergone a higher degree of mineralisation than the others, shows a lower metal bioavailability index since practically all the heavy metals in it are associated to the oxidisable and residual fraction. On the other hand the unstabilised sludge, which, along with that exposed to extended aeration, contains the highest accumulations of heavy metals in the most easily assimilable fractions. [Copyright &y& Elsevier]