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The huge volume of tannery solid waste (TSW) can be reduced through conversion into tannery solid waste biochar (TSWB). Here, it was used as soil amendment at seven levels and the total metals and their soil bound or exchangeable fractions were determined through sequential extraction. The fate of metals was observed using sunflower as a test plant in a greenhouse trial using field soil amended with six concentrations (0.45–2.7%) of TSWB. The amendment rate of 1.8% proved to be the best for the growth of sunflower. Sequential extraction of metals indicated that 40% or more Cd, Cr and Pb remained in the exchangeable fraction, compared to less than 20% of Cu, Fe and Ni. Copper was mainly bound in the Fe-Mn and organic fractions, while Fe and Ni were mainly bound in the residual fraction. Copper, Fe and Ni were therefore immobilized in TSWB, while Cd, Cr, Pb, Mg and Zn were available as indicated by differential uptake in sunflower. All metals, except Cd, remained within the permissible limit in tissues of sunflower, while all were in permissible limits in the seeds. As a result, TSWB can be used as amendment below 1.8% to grow energy crops like sunflower. [ABSTRACT FROM AUTHOR]

A three-step sequential extraction was carried out by modified BCR approach for fractionation of metals, including rare earths in red mud. 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. Accordingly, the highest readily soluble phases were obtained for Ca, Na, and K, while the reducible were Al, Zn, Cu, and Li. Rare earth elements (REEs) except for Eu were mostly identified in residual fraction. Most of Eu (88.7%) was detected in the reducible fraction, while the negligible part in residual. Chondrite normalization was implemented for obtaining REE anomalies. The remarkable Eu and Gd negative anomaly differences were determined between the red mud and its origin, Mortaş bauxite. The LREE to HREE ratio and LaN/YbN scores of 8.42 and 7.82, respectively indicated the LREE enrichment to HREE. By performing multivariate analysis, six and five-group clusters were obtained for REEs and non-REE metals in terms of fractional distribution, proving the easier release potential of Eu, La, Gd, K, Na, and Ca. [ABSTRACT FROM AUTHOR]

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]

Surabaya is one of the big coastal cities in Indonesia with rapid municipal development. Thus, the investigation on the metal's geochemical speciation in the coastal sediment is required to assess the environmental quality by studying their mobility, bioavailability, and toxicity. This study is aimed at evaluating the condition of the Surabaya coast by assessing copper and nickel fractionations and total concentrations of both metals in sediments. Environmental assessments were performed by using geo-accumulation index (Igeo), contamination factor (CF), and pollution load index (PLI) for existing total heavy metal data and by using individual contamination factor (ICF) and risk assessment code (RAC) for metal fractionations. Copper speciation was observed geochemically in the fraction order of residual (9.21 – 40.08 mg/kg) > reducible (2.33 – 11.98 mg/kg) > oxidizable (0.75 – 22.71 mg/kg) > exchangeable (0.40 – 2.06 mg/kg), while the detected fraction order of nickel was residual (5.16 – 13.88 mg/kg) > exchangeable (2.33 – 5.95 mg/kg) > reducible (1.42 – 4.74 mg/kg) > oxidizable (1.62 – 3.88 mg/kg). Different fraction levels were found for nickel speciation wherein its exchangeable fraction was higher than copper, even though the residual fraction was dominant for both copper and nickel. The total metal concentrations of copper and nickel were found in the range of 13.5 – 66.1 mg/kg dry weight and 12.7 – 24.7 mg/kg dry weight, respectively. Despite the fact that almost all index values are detected low through total metal assessment, the port area is indicated to be in the moderate contamination category for copper. Through the assessment of metal fractionation, copper is classified into the low contamination and low-risk category, while nickel is categorized into the moderate contamination level and medium risk to the aquatic environment. Although the coast of Surabaya generally remains in the safe category for living habitat, certain sites had relatively high metal concentrations estimated to have originated from anthropogenic activities. [ABSTRACT FROM AUTHOR]

Colloids of natural river water is a key intermediate carrier of lead (Pb). It is important to monitor the transport–transformation behavior of Pb in the colloidal phase of seaward water because this behavior is related to the levels of pollution input and environmental risks posed to the sea, especially in coastal delta areas. In this study, the fractionation behavior and distribution of toxic Pb from the truly dissolved phase and the different colloidal phases in seven seaward rivers in the Yellow River Delta were investigated. The concentrations of total dissolved Pb, truly dissolved Pb, and colloidal Pb were 0.99–40.09 μg L–1, 0.40–8.10 μg L–1, and 0.60–35.88 μg L–1, respectively. In freshwater rivers, the main component of total dissolved Pb (about > 50%) is truly dissolved Pb but the main component of total dissolved Pb in the seawater environment is colloidal Pb (> 80%). A dramatic increase in salinity causes the deposition (about ≈94%) of all forms of Pb to sediment from estuarine water in winter. However, this sedimentation behavior of colloidal Pb gradually decreases (in the Shenxiangou River) when the river salinity approaches seawater salinity (S = ≈29). In the industrial port (Xiaoqinghe River) and mariculture (Yongfenghe River) estuarine areas, which have extensive seawater, the deposition behavior of colloidal Pb (

Stormwater ponds are widely used for controlling runoff quality through the sedimentation of particles and associated pollutants. Their maintenance requires regular removal and disposal of accumulated material. This necessitates an assessment of material hazardousness, including potential hazard due to its contamination by metals. Here we analyze 32 stormwater pond sediment samples from 17 facilities using several chemical analysis methods (total extraction, sequential extraction, diffusive gradients in thin-films DGT, and pore water extraction) in order to consider the complementarity and comparability of the different approaches. No clear relationship was found between analyses that have the potential to measure similar metal fractions (DGT and either fraction 1 of the sequential extraction (adsorbed and exchangeable metals and carbonates) or pore water concentrations). Loss on ignition (LOI) had a significant positive correlation with an indicator of the environmental risk developed in this paper (∑ranks) that incorporates different metals, speciations, and environmental endpoints. Large variations in metal levels were observed between ponds. As clustering was limited between the different analyses, a comprehensive analysis of different parameters is still needed to fully understand metal speciation and bioavailability. [ABSTRACT FROM AUTHOR]

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The aims of the study were 1) to assess the suitability of selected amendments for reducing the mobility of metals in sediments by evaluating their effects on metal sorption capacity, and 2) to assess the ecotoxicity of sediment/amendment mixtures. Three different amendments were tested: cellulose waste, biochar, and dolomite. The efficiency of metal immobilization in mixtures was dependent on pH, which increased with concentrations of amendment. The higher negative charge observed for dolomite and cellulose waste corresponded with greater attraction of cations and enhanced metal sorption. For cellulose waste, the highest values of the Q parameter were attributed to the presence of OH groups, which corresponded with the highest immobilization of metals. Biochar reduced the negative surface charge, which highlights the importance of additional factors such as high specific surface area and volume of pores in metal immobilization. All amendments increased the SSA and V N2 , indicating a higher number of sorption sites for metal immobilization. Most bioassays established a reduction of the ecotoxicity for amendments. Mixtures with dolomite (25%, 45% doses) and biochar (45% dose) were low toxic. Mixtures with cellulose waste were toxic or highly toxic. The mobility of metals from contaminated sediments can be limited by reused industry side products, which could contribute to further closing the circular economy loop. • Cellulose waste, biochar, dolomite were used for immobilization of metals in sediment. • Amendments increased a number of sorption sites for metal immobilization. • OH groups in cellulose waste was corresponded with the highest immobilization of metals. • Mixtures with dolomite (25%, 45% doses) and biochar (45% dose) were low toxic. • All mixtures with cellulose waste were toxic or highly toxic. [ABSTRACT FROM AUTHOR]

Swine farming produces large quantities of nutrient-rich wastewater, which often contains metals such as Cu and Zn, used as feed additives for pigs. These metals must be removed from the wastewater before discharge but their retention in the biomass can limit its subsequent utilization. Photobioreactors are a very promising alternative for swine wastewater treatment, as the consortium of microalgae and bacteria growing symbiotically in these reactors allows high nutrient and metal removal efficiency at moderate costs. This work studies the mechanisms of removal of Cu(II) and Zn(II) by the two types of microorganisms growing in these photobioreactors. A microalga commonly used in wastewater treatment (Scenedesmus almeriensis) and an activated sludge were kept in contact with synthetic wastewater containing 100 mg/L of Cu and Zn. After 72 h, Scenedesmus almeriensis removed 43% of Cu and 45% of Zn, while activated sludge removed 78% of Cu and 96% of Zn. Single and sequential extractions of the biomasses using different extracting reagents revealed that biosorption on protonable groups is the dominant removal mechanisms. Mild reagents solubilized 69% of Cu and 94% of Zn from the microalgae and 76% of Cu and 93% of Zn from the activated sludge. Low metal concentrations in the oxidizable and residual fractions evidenced minimal bioaccumulation inside the cells. FTIR and ESEM-EDX analysis confirmed biosorption by ion exchange and complexation as the main metal remediation mechanisms. The weak bonds of the biosorbed Cu and Zn ions are beneficial for the valorization of biomass and the obtaining of safe bioproducts. [Display omitted] • Sewage sludge more effective than microalga S. almeriensis to remove Cu and Zn from wastewater. • Cu is more strongly biosorbed than Zn by both sewage sludge and microalgae. • Metal biosorption on protonable electron donor groups is the main bioremoval mechanism. • Cu and Zn are biosorbed on groups –COOH, –OH, –NH contained in proteins and carbohydrates of the cell membrane. • Most metal accumulated by the biomasses is acid soluble/exchangeable and readily available. [ABSTRACT FROM AUTHOR]

Surficial sediment samples along the coastal area of the province Thai Binh in Vietnam have been collected and analysed by modified Tessier method for the mercury content. The mercury levels in these samples were found in the range between 0.12–3.79 mg/kg. Elevated concentrations were observed in some locations close to tidal marshes, large aquaculture productions or low-lying areas. The highest level of mercury was detected in a low-lying terrain near large aquaculture productions. The majority of the mercury species in all samples were witnessed in the fraction bound to organic matters. The predominance of this fraction is possibly associated with some misuses of mercurial fungicides by aqua farmers. These mercury species remain quite resistant in the sediments, thus posing a quite low risk for the surrounding ecological environment. Nevertheless, it is necessary to undertake further studies to evaluate the effect of this contamination on the food chain.

Ooty lake, in the southern part of India, has raised huge concern about the role of metals in a lake due to increasing anthropogenic activities. Present study is aimed at understanding fate of trace metals in a lake's sediment. Sixteen sediment samples collected from bottom of the lake at various locations during March 2017 were analysed for trace metals cobalt, chromium, copper, iron, lead, manganese, nickel and zinc. Fe and Mn dominate total metal concentration followed by Ni and Cr. A high concentration of Cr, Cu, Ni and Zn in residual fraction indicates weathering as the source for these metals. A significant concentration of metals in exchangeable, reducible and oxidisable fraction indicates adsorbtion/chelation of these metals with oxides and organic matter due to change in oxic state. Geo-accumulation index for metals show unpolluted to moderate nature of sediments at all sampling locations. Moderate to significant enrichment factor of Cr, Ni and Zn indicates influence of anthropogenic sources. Co, Pb and Zn show a high amount of bioavailability for aquatic life. Other metals (Cr, Ni, Fe and Mn) show scarce to moderate bioavailability. On the other hand, a global contamination factor denotes moderate to high metal contamination of sediments in the entire lake. Statistical analysis of metals shows good inter-element correlation among metals Fe, Cr, Ni, Co, Cu and Zn indicating natural source. Influence of domestic sewage and recreational activities as the main/additional source is revealed by negative loading of Pb and Zn in principal component analysis. The present study, in essence, has identified rock weathering, as a major source of trace meals in the sediments of Ooty lake entering through stream and surface runoff from an adjacent forest area. The study has also identified high bioavailability of Pb and Zn, which is derived through the recreational activities (boating) causing permanent adverse impact. [ABSTRACT FROM AUTHOR]

Surficial sediment samples along the coastal area of the province Thai Binh in Vietnam have been collected and analysed by modified Tessier method for the mercury content. The mercury levels in these samples were found in the range between 0.12–3.79 mg/kg. Elevated concentrations were observed in some locations close to tidal marshes, large aquaculture productions or low-lying areas. The highest level of mercury was detected in a low-lying terrain near large aquaculture productions. The majority of the mercury species in all samples were witnessed in the fraction bound to organic matters. The predominance of this fraction is possibly associated with some misuses of mercurial fungicides by aqua farmers. These mercury species remain quite resistant in the sediments, thus posing a quite low risk for the surrounding ecological environment. Nevertheless, it is necessary to undertake further studies to evaluate the effect of this contamination on the food chain. [ABSTRACT FROM AUTHOR]

Bioremediation of hazardous bauxite residues, red mud (RM), through vermicomposting has yet to be attempted. Therefore, the valorization potential of Eisenia fetida in various RM and cow dung (CD) mixtures was compared to aerobic composting. Earthworm fecundity and biomass growth were hindered in RM + CD (1:1) feedstock but enhanced in RM + CD (1:3). The pH of highly alkaline RM-feedstocks sharply reduced (>17%) due to vermicomposting. N, P, and K availability increased dramatically with Ca and Na reduction under vermicomposting. Additionally, ∼40–60% bioavailable metal fractions were transformed to obstinate (organic matter and residual bound) forms upon vermicomposting. Consequently, the total metal concentrations were significantly reduced with considerably high earthworm bioaccumulation. Microbial growth and enzyme activity were more significant under vermicomposting than composting. Correlation statistics revealed that microbial augmentation significantly facilitated a metal reduction in RM-vermibeds. Eventually, RM-vermicompost stimulated sesame growth and improved soil health with the least heavy metal contamination to soil and crop. • E. fetida fecundity was satisfactory in red mud (RM)-based vermibeds. • Alkalinity reduced by ∼17% and NPK increased by ∼30% in RM-based vermibeds. • Microbe and enzyme diversity was more in vermibeds than composting beds. • Enzyme-microbe-mediated regulation of toxic metals were promoted in vermibeds. • Vermicomposted RM induced soil-crop quality & reduced metal mobility. [ABSTRACT FROM AUTHOR]

Five metals in sediment samples at seven sites from the Ambon Bay were analyzed with BCR sequential extraction procedure to determine chemical fractionation of metals and to assess bioavailability of metals with Risk Assessment Code (RAC). The result showed that the percentages of cadmium (100%), lead (82.6-97.08%) and zinc (41.68-76.33%) were mostly accumulated in the non-residual (F1+F2+F3) fraction of the total concentrations. While the copper percentages (44.74-78.91%) and nickel (59.71-74.16%) were mostly accumulated in residual (F4) fraction of the total concentrations. The Risk Assessment Code (RAC) reveals that cadmium, copper, nickel and zinc at locations exist in acid soluble (exchangeable) fraction and therefore, they are in low until very high risk category meanwhile there is no Pb at locations exist in acid soluble (exchangeable) fraction.

The Huaihe River has suffered increasing pressure from pollutants including metals from anthropogenic activities. In this study, enrichment and fractionation behavior of trace metals were analyzed in sediment samples obtained from fish spawning area of the Huaihe River (Anhui Section) to evaluate the potential ecological risk of trace metals to aquatic organisms. Geochemical indices including enrichment factor and geo-accumulation index as well as mean probable effect concentration quotient and risk assessment code were adopted to assess the contamination degree and potential ecological toxicity. Results showed that the total contents of Cu, Pb, Zn, Cr, Cd, As, and Hg in sediment were 23.1 ± 6.4, 32.3 ± 11.1, 76.8 ± 14.2, 84.6 ± 17.2, 0.2 ± 0.1, 9.0 ± 3.0, and 0.031 ± 0.010 mg/kg, respectively. The indexes EF and Igeo revealed slight accumulation for Pb, Zn, Cr, Cd, and As in some sampling sites. The result of Qm-PEC demonstrated that trace metals in sediment were not toxic to aquatic organisms. Most trace metals appeared to mainly associate with the residual form suggesting lower mobility whereas Cd presented a relative higher exchangeable fraction indicating a great degree of bioavailability. The result of risk assessment code (RAC) evaluation revealed that Cd poses a medium ecological risk for aquatic organisms whereas most of the other trace metals pose low risks. [ABSTRACT FROM AUTHOR]

This paper characterizes stormwater runoff in a coastal cold climate urban area regarding metal fractionation and particle size distribution to understand the implications for sustainable urban drainage system (SuDS) design. Strong temporal and spatial variations were found for all studied parameters. Suspended and dissolved solids showed up to 10-fold and 44-fold increase, respectively, during salting periods (air temperature <0 °C). Metals were nearly solely associated with the suspended fraction (>1.2 µm), which increased during the salting periods (>97%). Use of snow-tyres and de-icers (gritting sand and NaCl) are more likely to explain the temporal fluctuations, rather than contributions from nearby snow piles. Residential streets might serve as a source of pollutants during the winter months when street sweeping is minimal. These results imply that protection against clogging from excessive sediment loads and use of salts during winter should be the primary focus for SuDS design. [ABSTRACT FROM AUTHOR]

Purpose: Canal dredging and shaping produce considerable amounts of sediments whose reuse on- and off-site depends on their pollution level. This study explores the potential of a calcium chloride washing to remove potentially toxic elements (PTEs) from a freshly dredged calcareous sediment and to affect the aggregate stability of the washed sediment. Materials and methods: The ability of 0.5-M CaCl2 washing to restore the sediment samples polluted with Cu and Zn dredged from a freshwater canal was assessed. The distribution of the two metals among the sediment geochemical phases, the potential availability to plants (DTPA), and the water aggregate stability of particles were evaluated on the washed samples and compared to control. Results and discussion: In the most polluted sample (~200 and 500 mg kg−1 of Cu and Zn, respectively), the washing decreased the amount of Cu by 26%, mainly in the sulfide/organic fraction, and of Zn by 10%, mainly in carbonates. A decrease in the dispersivity of clay fraction was observed due to the well-known effect of Ca2+ ions on flocculation of colloidal clay particles. At large scale, the aggregates formed by the interaction between large particles and flocculated clay showed lower water stability with respect to the control, thus suggesting the need to improve the physical properties of the treated material. Noteworthy, after 1 year of dry storage from washing, the average percentage of potentially bioavailable (DTPA) Cu and Zn (23 and 13% of pseudo-total amount, respectively) dropped with respect to the control (40 and 19%) and a concomitant carbonate increase (+33%) was observed. Conclusions: The CaCl2 washing is a promising method to reduce Cu and, to a minor extent, Zn in wet calcareous sediments dredged from freshwater canals. However, there is still room for improvement. The PTE fractions remaining in carbonates and organic component of washed sediment clearly indicate the potential of combining mild acidic pH values with calcium chloride in the washing to enhance the PTE removal. [ABSTRACT FROM AUTHOR]

Concentrations of total suspended solids (TSS), trace metals (Cu, Cd, Cr, Zn, Cd, Pb), Na and 16 US EPA priority PAHs in urban snow were studied in the City of Luleå in Northern Sweden. Snow was sampled at six central urban and suburban sites with various traffic intensities, in three sampling surveys (1994–95, 2002–03, 2020–21), repeated for three ages of the urban snow cover of 40, 80, and 120 days, respectively. The older data, from the 1994–95 and 2002–03 surveys, were obtained from the existing literature. The concentrations and mass loads of TSS and most trace metals studied (Zn, Cu, Pb, and Cd) varied with time. TSS, Zn, and Cu showed slightly higher concentrations and mass loads in the 2003 (TSS avg = 2300 μg/L, Zn avg = 620 μg/L and Cu avg = 250 μg/L) and 2021 (TSS avg = 1500 μg/L, Zn avg = 530 μg/L and Cu avg = 220 μg/L) sampling surveys, compared to the 1995 survey (TSS avg = 620 μg/L, Zn avg = 240 μg/L and Cu avg = 97 μg/L). However, no evident trend was observed between the 2003 and 2021 sampling surveys. The highest concentrations of Pb and Cd were observed in snow samples from the 1994–95 sampling survey (Pb max = 570 μg/L, Cd max = 4.6 μg/L). Results indicated higher concentrations of the pollutants studied in the city centre, compared to the residential suburbs, and in areas with heavier traffic, where concentrations of metals correlated well with traffic intensity. Fractionation analysis of trace metals indicated that Zn, Cu and Pb occurred mostly in the particulate-bound phase (>0.45 μm) containing the most of Zn, Cu, and Pb mass, at 80, 84 and 94% of the total, respectively. Over 50% of the dissolved phase of Zn and Cu was in the truly dissolved fraction (<3000 MWCO). Concentrations of PAHs also increased with traffic intensity, with pyrene being the most frequently detected PAH, likely because of the strength of sources and various physical processes influencing the snowbanks development and causing spatial and temporal variations in pollutant concentrations. [Display omitted] • Weather and snow management practices, affected pollution stored in urban snow cover • Pb and Cd concentrations in urban snow have declined since the first survey in 1995 • No temporal patterns in loads of TSS, Cu and Zn were detected • Dissolved fraction of Zn, Cu, and Pb were higher in residential suburbs than in the city • Over 50% of dissolved (<0.45 μm) Zn and Cu was in the truly dissolved phase (<3000MWCO) [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.

This work presents and discusses experimental results on the characterisation and metal leaching potential of a biogenic, metal-rich sulphidic sludge, generated in a sulphate-reducing bioreactor, operated to treat acidic synthetic solutions bearing Fe, Zn, Ni and Cu. The sustainability of the metal removal bioprocess strongly depends on the fate of the sludge. To propose appropriate management practices, a detailed characterisation of the sludge is necessary. The granulometry, chemical composition and mineralogy of the sludge were initially determined. The mobility of the metals was assessed via a modified Tessier experimental procedure. The leachability of the sludge metal content was determined via a standard compliance method (EN 12457-2) and experiments designed to evaluate the effect of pH and time on metal leaching from the sludge. The sludge metal content sums up to 69.5% dw, namely iron (14.8%), zinc (18.7%), nickel (17.7%) and copper (18.2%) and, based on the criteria set by European Union, the sludge is characterised as hazardous and inappropriate for landfilling without any pretreatment. The sludge consists mainly of very fine poorly crystalline aggregates of Fe, Zn, Cu and Ni sulphides. The fine grain size, the poorly crystalline structure and the oxidation of sulphide upon exposure to water/air render the high metal content of the sludge recoverable. [ABSTRACT FROM AUTHOR]

Abstract Electrodialytic remediation was applied to a shooting range soil to investigate the influence of electrode placement on the removal and binding of metals during the treatment. The set-up was based on a 2-compartment cell, in which the cathode was separated from the soil by a cation exchange membrane and the anode was placed directly in the soil, thereby introducing protons and oxygen directly in the soil. Mobilisation of metals from less available fractions (oxidisable and residual) in the soil occurred, due to oxidation/dissolution of insoluble/soluble organic matter and possibly metal oxides in the residual fraction. The transport via electromigration out of the soil and/or re-precipitation in other fractions of the soil (oxidisable, reducible, exchangeable) depended on the metal. More than 30% of the initial content of Mn, Cd, Cu, Pb and Zn and less than 20% of the initial content of Al, Fe, K, Mg, As, Cr and Ni was transported out of the soil. By decreasing the distance between the electrodes from 3.0 to 1.5 cm, the removal of the targeted metal for remediation, Pb, was improved by more than 200%, from 14 to 31%. A similar removal could be achieved in experiments with long distance between electrodes (3.0 cm) by increasing the current intensity from 4 to 10 mA and/or the remediation time from 7 to 35 d. The experiments showed that the design and optimisation of electrodialytic remediation depends on the targeted metal and metal partitioning. Highlights • Electrodialysis was applied to mobilise and remove metals from a shooting range soil. • The anode placement in the soil ensured introduction of protons and oxygen. • Oxidation and dissolution of organic matter and metal oxides, mobilised metals. • Electromigration and re-precipitation in other soil fractions depended on the metal. • Optimisation depends on the targeted metal, metal speciation and soil characteristics. [ABSTRACT FROM AUTHOR]

The leaching and uptake of Cd, Cu, Pb, and Zn by maize (Zea mays L.) in mudflat saline-alkali soils amended by sewage sludge was examined using a greenhouse leaching column experiment. Application of sewage sludge caused decreased pH, increased DOC, and increased Cd, Cu, Pb, and Zn concentrations in leachates. The similar temporal dynamics of DOC and the metal concentrations in leachates suggested complexation of the metals with DOC. There was downward movement of metals as evidenced by the metal enrichment in the bottom layer (20-40-cm depth) of leaching columns (p < 0.05). The enrichment of metals was contributed by the acid-soluble/exchangeable fraction (EX), reducible fraction (RG), oxidizable fraction (OXI), and residual fraction (RES), indicating redistribution of leached metals from the top 20-cm layer. The sewage sludge application also enhanced plant uptake of metals. However, even under the greatest sludge application rate (150 g kg−1), very small proportions, averagely 0.65% and 0.35%, of the applied metals were leached and taken up by maize, respectively, over the experimental period. Long-term field-scale research is warranted for further investigation of the effects of sewage sludge amendment on heavy metal fractionation and distribution in mudflat soil-plant-water system. [ABSTRACT FROM AUTHOR]

The high nutrients and organic matter (OM) content of sewage sludge make it an excellent fertilizer to enhance soil fertility and crop production. However, the presence of adsorbed and precipitated forms of heavy metals, especially cadmium (Cd), can be a major problem for such a utilization of sludge. This pot study aims at producing safe food with minimal Cd concentrations from sewage sludge amended soils. Two wheat cultivars (NARC-11 and Shafaq-06) were sown in soil amended with sewage sludge with rates 0, 15 and 30 g kg−1 soil. Application of sewage sludge resulted in enhancement of wheat grain yield while Cd concentrations in wheat grains of both cultivars remained within permissible limits (24.1 to 58.6 μg kg−1 dry weight). Fourier transform infrared (FTIR) spectroscopic analysis revealed more spectral changes in fulvic acids than in humic acids, which showed a higher humification degree, making them chemically and biologically more stable for Cd retention. Sequential extraction data of Cd after NARC-11 harvest exhibited a significant decrease in mobile fractions (exchangeable and reducible fractions were reduced by 3.6 and 5.2%, respectively) and increase in immobile fraction (the oxidizable and residual fractions increased by 7 and 1.8%, respectively). It is concluded that sewage sludge application could be useful for the improvement of wheat production due to formation of stable humate complexes and decrease in Cd availability. [ABSTRACT FROM AUTHOR]

Mercury adsorption characteristics of Mississippi River deltaic plain (MRDP) freshwater marsh soil in the Louisiana Gulf coast were evaluated under various conditions. Mercury adsorption was well described by pseudo-second order and Langmuir isotherm models with maximum adsorption capacity of 39.8 mg g −1 . Additional fitting of intraparticle model showed that mercury in the MRDP freshwater marsh soil was controlled by both external surface adsorption and intraparticle diffusion. The partition of adsorbed mercury (mg g −1 ) revealed that mercury was primarily adsorbed into organic-bond fraction (12.09) and soluble/exchangeable fraction (10.85), which accounted for 63.5% of the total adsorption, followed by manganese oxide-bound (7.50), easily mobilizable carbonate-bound (4.53), amorphous iron oxide-bound (0.55), crystalline Fe oxide-bound (0.41), and residual fraction (0.16). Mercury adsorption capacity was generally elevated along with increasing solution pH even though dominant species of mercury were non-ionic HgCl 2 , HgClOH and Hg(OH) 2  at between pH 3 and 9. In addition, increasing background NaCl concentration and the presence of humic acid decreased mercury adsorption, whereas the presence of phosphate, sulfate and nitrate enhanced mercury adsorption. Mercury adsorption in the MRDP freshwater marsh soil was reduced by the presence of Pb, Cu, Cd and Zn with Pb showing the greatest competitive adsorption. Overall the adsorption capacity of mercury in the MRDP freshwater marsh soil was found to be significantly influenced by potential environmental changes, and such factors should be considered in order to manage the risks associated with mercury in this MRDP wetland for responding to future climate change scenarios. [ABSTRACT FROM AUTHOR]

Creation of Technosols with the use of different materials is a sustainable strategy to reclaim mine tailings and reduce metal mobility. For this purpose, a short-term incubation experiment was designed with biochars derived from pig manure, crop residues and municipal solid waste added to tailings alone or in combination with marble waste. We aimed to assess the efficiency of the different amendments to decrease Cd, Pb and Zn availability in the Technosols and the fractions where metals were retained. Results showed that all amendments reduced metal mobility, directly related to increases in pH. Those materials with higher content of carbonates were more effective to immobilize metals (~99%). Municipal solid waste was highly effective to decrease metal mobility owing to the higher carbonate content, but addition of marble waste was needed to enhance metal immobilization with pig manure and crop residue. Decreases in Cd mobility were related to retention by the carbonate, Mn/Fe oxides and oxidizable (organic compounds) fractions. Decreases in Pb mobility were related to retention in the Mn/Fe oxides and residual fractions, while decreases in Zn mobility were related to retention in Mn/Fe oxides and oxidizable fractions. Association of Zn and Pb with the oxidizable fraction was also related to the recalcitrance of the organic compounds and so dependent on biochar type. Scanning electron microscopy coupled with energy dispersive X-ray showed that biochar showed great affinity to interact with iron oxides, calcium sulfates and phyllosilicates. Copyright © 2017 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

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]

This study investigated the distribution and fractionation of metals (Mn, Ni, Pb, Cr, Cu, Zn, As, Cd, Hg and Sn) in surface sediments of Tema Harbour (Greater Accra, Ghana) as well as its ecological implications. Significant differences in sediment concentrations of Mn, Ni, Cr, Cu, Zn, As and Sn were observed across the Tema Harbour. Geochemical indices indicate that Cd, Hg, Pb, Cu, Zn, As and Sn in the Tema Harbour sediments derived mainly from anthropogenic sources, while Mn, Ni and Cr were mainly of lithogenic origin. Metal fractionation revealed a predominance of Al, Mn, Ni, Pb, Cr, Cu, As and Sn in the residual phase. In contrast, Cd and Hg were mainly present in the exchangeable phase, while Zn was mainly associated with the reducible phase. Based on the metal fractionation in the Tema Harbour sediments, the potential risks of metal bioavailability were high for Cd and Hg, low-medium for Mn, Ni, Zn, As and Sn and low for Pb, Cr and Cu. A screening-level ecotoxicological assessment revealed high potential toxicity of Hg and moderate potential toxicities of Pb, Cu, Zn, As and Cd in the Tema Harbour sediments. The potential influence of the buffer intensity, silt-clay, total organic carbon and carbonate content on the metal distribution in the Tema Harbour sediments was also inferred from their correlations. Comparison with previous studies did not reveal a progressive increase in metal contamination at the Tema Harbour since the year 2000. [ABSTRACT FROM AUTHOR]

This study evaluates the trace metal composition and fractionation in sludge samples from anaerobic sewage treatment plants from six cities in Brazil. Ten metals were evaluated: Ni, Mn, Se, Co, Fe, Zn, K, Cu, Pb and Cr. Specific methanogenic activity of the sludge was also evaluated using acetic acid as the substrate. Among the essential trace metals for anaerobic digestion, Se, Zn, Ni and Fe were found at a high percentage in the organic matter/sulfide fraction in all sludge samples analyzed. These metals are less available for microorganisms than other metals, i.e., Co and K, which were present in significant amounts in the exchangeable and carbonate fractions. Cu is not typically reported as an essential metal but as a possible inhibitor. One of the samples showed a total Cu concentration close to the maximal amount allowed for reuse as fertilizer. Among the non-essential trace metals, Pb was present in all sludge samples at similar low concentrations and was primarily present in the residual fraction, demonstrating very low availability. Cr was found at low concentrations in all sludge samples, except for the sludge from STP5; interestingly, this sludge presented the lowest specific methanogenic activity, indicating possible Cr toxicity. [ABSTRACT FROM AUTHOR]

To assess the risk of release and percentage of heavy metals in river sediment, nine stations were set up to sample surface sediments from three important rivers situated southwest of the Caspian Sea (the Shafaroud, Karaganroud, and Choubar Rivers). Chemical analyses were conducted on sediment with particle sizes of >38, 63-38, 63-125, 125-250, 250-500 and 500-1000 µm using metal fractionation to determine the degree of risk release and the heavy metal pollution. Common risk indices were used including the cumulative indices of pollution intensity assessment and risk release standards (the modified pollution degree and ecological risk). Generally, when sediment sizes are decreased, the concentration of heavy metals is both larger and greater than the mean concentration of global sediments and earth crust. However, in this research, the concentration of all the metals did not necessarily increase with a decrease in the size of particles. In fact, concentration of cobalt, vanadium, cadmium, and chromium was greater in sediment particle sizes over 63 μm. The results of chemical fractionation analyses indicated that the release risk of metals has two initial phases for: (1) exchangeable bond (F1) and (2) carbonated bond (F2). When compared with other metals, nickel had the greatest tendency to bond within the loose exchangeable phase (F1) across all the stations. Furthermore, with changes in the size of particles, the percentage of heavy metal changes across different bond phases, but will be the greatest in the loose exchangeable phase (F1). This was observed with cobalt, nickel, and chromium at particle sizes larger than 63 μm. The results of ecological risk and modified pollution degree indices indicated that the highest level of pollution was related to sediments with sizes between 63 and 250 μm. Eventually, in order to assess the risk extent of metals present in sediment, a cumulative index referred to as the modified risk assessment code was utilized. It suggested that the greatest risk of toxicity in some stations has been related to particles larger than 63 μm. [ABSTRACT FROM AUTHOR]

Comprehensive studies that examine the transfer of metals across soil-river bed sediment systems at the basin scale are scarce. An understanding of the distribution of metals among various fractions of soils and sediments within a basin is fundamental to understand their environmental behavior and, thus, to define watershed management plans. This study aims to determine the distribution of metals (Fe, Mn, Cu, and Zn) in topsoils under different land uses (cultivation, pastures, and forests) and river surface sediments in the upper Mero River basin (NW Spain) and to assess these metals' mobility and bioavailability in both environmental compartments to detect potential threats to crops and the water quality. Sequential extraction is used to fractionate the four metals into six fractions: soluble/exchangeable/specifically adsorbed, metals that are bound to Mn oxides, amorphous compounds, metals that are bound to organic matter, crystalline Al and Fe oxides, and residual metals (metals within the crystal lattices of minerals). The fractionation results for both soils and sediment indicate an abundance of metals in the residual fraction (except for Mn in soils) followed by relatively high percentages of oxide-bound fractions (mostly crystalline Fe oxides for both Fe and Zn, amorphous for Cu, and Mn oxides for Mn). On average, the Mn residual fraction in soils (30.2%) is only slightly exceeded by the Mn oxide fraction (34.7%). The land uses do not affect the sequence of metal-binding phases in soils, except for Mn, which is only slightly altered. The results also suggest that Fe, Mn, Cu and Zn in both soils and sediments are not readily mobile under current environmental condition and hence pose no threat to crops or the water quality. In overall terms, the mobility and bioavailability of the four metals (considering the sum of the three least mobile fractions, namely, organic matter, crystalline Al and Fe oxides, and residual) in the soils decrease in the following order: Mn > Cu > Fe > Zn. The same sequence occurs in the sediments, but the order between Fe and Zn is reversed. The soils and sediments that are studied cannot be considered polluted in terms of these metals because of their low levels and prevalence in the residual fraction, which is typical of contributions from natural sources and indicates the pedogenic/lithologic origin of these metals. [ABSTRACT FROM AUTHOR]

The Weilasituo and Bairendaba Zn–Pb–Ag–Cu–(Sn–W) sulphide deposits are located in the southern part of Great Xing'an Range of Inner Mongolia in China. The deposits are located at shallow depths in the newly discovered Weilasituo porphyry hosting Sn–W–Rb mineralization. The mineralization at Weilasituo and Bairendaba consist of zoned massive sulphide veins within fractures cutting the Xilinhot Metamorphic Complex and quartz diorite. The Weilasituo deposit gradually zones from the Cu-rich Zn–Cu sulphide mineralization in the west to Zn-rich Zn–Cu sulphide mineralization in the east. The Bairendaba deposit has a Cu-bearing and Zn-rich core through a transitional zone devoid of copper to an outer zone of Zn–Pb–Ag mineralization. Three main veins contain more than 50 wt.% of the contained metal in the two deposits with their metal ratios displaying a systematic and gradual increase in Zn/Cu, Pb/Zn and Ag/Zn ratios from the western part of Weilasituo to the eastern part of Bairendaba. Three stages of vein-type mineralization are recognized. Early, sub-economic mineralization consists of a variable proportion of euhedral arsenopyrite, pyrite, quartz, and rare wolframite, scheelite, cassiterite, magnetite and cobaltite. This was succeeded by main stage mineralization with economic concentration of zoned Cu, Zn, Pb and Ag sulphide minerals along strike within the veins. The zones consist of the assemblages: (1) pyrrhotite–Fe-rich sphalerite–chalcopyrite(–quartz–fluorite) at west Weilasituo; (2) pyrrhotite–Fe-rich sphalerite–chalcopyrite(–galena–tetrahedrite–quartz–fluorite) at east Weilasituo; (3) pyrrhotite–Fe-rich sphalerite–chalcopyrite(–galena–tetrahedrite–quartz–fluorite) in the centre of Bairendaba; (4) pyrrhotite–Fe-rich sphalerite–galena(–chalcopyrite–tetrahedrite–quartz–fluorite) in the transition zone of Bairendaba; and (5) pyrrhotite–Fe-rich sphalerite–galena–tetrahedrite(–chalcopyrite–falkmanite–argentite–pyrargyrite–quartz–fluorite) in the outer zone at Bairendaba. Post-main ore stage is devoid of sulphides and characterized overprinting of fluorite, sericite, chlorite, illite, kaolinite and calcite. Zircon SHRIMP U–Pb dating, Zircon LA–ICP–MS U–Pb dating, molybdenite Re–Os isochron dating, and muscovite Ar–Ar dating indicate the Beidashan granitic batholith was intruded at 140 ± 3 Ma (MSWD = 3.3), the porphyritic monzogranite from marginal facies of the Beidashan batholith was intruded at 139 ± 2 Ma (MSWD = 0.75), the mineralized quartz porphyry was intruded at 135 ± 2 Ma (MSWD = 0.91), the greisen mineralization occurred at 135 ± 11 Ma (MSWD = 7.2), and the post-main ore stage muscovite deposited at 129.5 ± 0.9 Ma. The new geochronology data show the porphyry Sn–W–Rb and vein-type sulphide mineralization are contemporaneous with granitic magmatism in the region. The metal zonation at the Weilasituo and Bairendaba deposits is a result of progressive metal deposition. This was during the evolution of a metal-bearing fluid along the strike of the veins and during the main stage of ore formation at the upper part of the deep-seated porphyry Sn–W–Rb system. This progressive zonation indicates that the deposits represent end-numbers formed from one ore-forming fluid, which moved from west to east from the porphyry. The metal zonation patterns of the major veins are consistent with metal-bearing fluid entering the system with the precipitation of chalcopyrite proximally and sphalerite, galena and Ag-bearing minerals more distally. We show that the mechanism of metal deposition is therefore controlled by thermodynamic conditions resulting in the progressive separation of sulphides from the metal-bearing fluid. The temperature gradient between the inflow zone and the outflow zone appears to be one of the key parameters controlling the formation of the metal zonation pattern. The sulphide precipitation sequence is consistent with a low f S 2 and low f O 2 state of the acidic metal-bearing fluid. The metal zonation pattern provides helpful clues from which it is possible to establish the nature of fluid migration and metal deposition models to locate a possible porphyry mineralization at depth in the Great Xing'an Range, which is consistent with the geology of the newly discovered porphyry Sn–W–Rb system. [ABSTRACT FROM AUTHOR]

Mining activities are related to relevant environmental pollution issues that should be controlled. We used sequential extractions to fractionate Cd, Cu, Ni, Pb and Zn retained on unamended or mussel shell-amended mine soil samples, all of them treated with a mixture of the five heavy metals (total metal concentration of 1·57 mmol L−1), after 1, 7 and 30 days of incubation. In addition, we used the stirred flow chamber technique to study the release of each of the five heavy metals from these different unamended and shell-amended soil samples. The results indicate that the shell amendment caused a decrease in the most soluble fraction, while increasing the most recalcitrant (least mobile) fraction. With equivalent implications, the stirred flow chamber experiments showed that mussel shell amendment was associated to a decrease in heavy metal release and increased retention. The highest mussel shell dose and incubation time caused the most relevant changes in pH values and thus in metal retention, also indicating the importance of pH modifications in the mechanism of retention acting in the amended samples. In view of these results, the use of mussel shell amendment can be encouraged to increase heavy metal retention in acid mine soils, in order to minimise risks of environmental pollution. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Various mineral processing operations to produce pure metals from mineral ores generate sludges, residues, and other unwanted by-products/wastes. As a general practice, these wastes are either stored in a reservoir or disposed in the surrounding of mining/smelting areas, which might cause adverse environmental impacts. Therefore, it is important to understand the various characteristics like heavy metal leaching features and potential toxicity of these metallurgical wastes. In this study, zinc plant leach residues (ZLRs) were collected from a currently operating Zn metallurgical industry located in Minas Gerais (Brazil) and investigated for their potential toxicity, fractionation, and leachability. Three different ZLR samples (ZLR1, ZLR2, and ZLR3) were collected, based on their age of production and deposition. They mainly consisted of Fe (6-11.5 %), Zn (2.5 to 5.0 %), and Pb (1.5 to 2.5 %) and minor concentrations of Al, Cd, Cu, and Mn, depending on the sample age. Toxicity Characteristic Leaching Procedure (TCLP) results revealed that these wastes are hazardous for the environment. Accelerated Community Bureau of Reference (BCR) sequential extraction clearly showed that potentially toxic heavy metals such as Cd, Cu, Pb, and Zn can be released into the environment in high quantities under mild acidic conditions. The results of the liquid-solid partitioning as a function of pH showed that pH plays an important role in the leachability of metals from these residues. At low pH (pH 2.5), high concentrations of metals can be leached: 67, 25, and 7 % of Zn can be leached from leach residues ZLR1, ZLR2, and ZLR3, respectively. The release of metals decreased with increasing pH. Geochemical modeling of the pH-dependent leaching was also performed to determine which geochemical process controls the leachability/solubility of the heavy metals. This study showed that the studied ZLRs contain significant concentrations of non-residual extractable fractions of Zn and can be seen as a potential secondary resource for Zn. [ABSTRACT FROM AUTHOR]

To determine the effect of soil aging (1,12, or 24 months) and compost maturation time on metal redistribution and mobility, soil artificially contaminated with Zn and Cu was stabilized with compost for 35, 24, or 12 months. The compost was produced from municipal sewage sludge, wood chips, rape straw, and grass, matured for 3 or 12 months, then used as a soil amendment at a dosage of 20% (w/w). The total time in each series, including aging of spiked soil and its stabilization with compost, was 36 months. The results showed that soil aging reduced CaCl2 extractable Zn fraction and increased Zn stability (as reduced partition index, IR) more than compost addition, which only reduced Zn mobility in soils that had been aged for 1 and 12 months. However, after soil that had been previously aged 1 month was incubated with compost for one year, Zn mobility started to increase. Composts did not influence the changes in the IR of Zn over time. In contrast, compost addition increased Cu stability more than soil aging did, whereas soil aging and compost addition had a negligible effect on Cu mobility. The IR of Cu in all amended soils averaged 0.51, and reached a maximum of 0.57 12 months after addition of compost to soil previously aged for 12 months. Importantly, the maturation time of compost did not affect the mobility or stability of either metal. [ABSTRACT FROM AUTHOR]

Purpose: Soil metal pollution is a widespread problem around the world and remediation of these soils is difficult. The objective of this study was to investigate the effect of two different strategies on the chemical fractions of metals in a soil of a depleted copper mine: (1) amending with a mixture of a technosol made of wastes and biochar and (2) amending combined with planting vegetation ( Brassica juncea). Materials and methods: A 3-month greenhouse experiment was carried out to evaluate the effects of organic amendments and vegetation on the metal fractionation of Cu, Ni, Pb and Zn in a mine soil of the depleted copper mine at Touro (Spain). We compared the influence of organic amendments alone (technosol + biochar) and combined with mustard plants ( Brassica juncea L.). Results and discussion: The results showed that amending with a technosol made of wastes promoted plant growth (from 0.7 to 2.9 g of biomass produced) and reduced the CaCl-extractable metal concentration in soil, reduced the mobility factor of Cu from 18.3 to 1.6, Ni from 47.5 to 2.3 and Pb from 17.9 to 2.1, and also reduced the concentration of metals in the mobile soil fractions. It was not possible to grow up Brassica juncea plants in the untreated settling pond soil due to the extremely degraded conditions of that soil. However, the application of the used technosol increased the Pb and Zn pseudototal concentrations in the amended soils. Conclusions: We conclude that the combination of amending with wastes and planting B. juncea provides little additional benefit for remediating a metal-polluted soil compared with incorporation of wastes alone. [ABSTRACT FROM AUTHOR]

The quality of bottom sediments is a key factor for many functions of dam reservoirs, which include water supply, flood control and recreation. The aim of the study was to combine different pollution indices in a critical generic risk assessment of metal contamination of bottom sediments. Both geochemical and ecological indices reflected that sediment contamination was dominated by Zn, Pb and Cd. The ecological risk indices suggested a high riks for all three metals, whereas human health risks were high for Pb and Cd. An occasional local contamination of sediments with Cr and Ni was revealed, although at levels not expected to cause concerns about potential ecological or health risk. Sediments from the Rybnik reservoir for Cu only revealed a high potential ecological risk. EF turned to be as being the most useful, whereas TRI (∑TRI) was the most important ecological index. All multi-element indices suggested similar trends, indicating that Zn, Pb and Cd taken altogether had the greatest impact on the level of sediment contamination and posed the greatest potential ecological and health risks to organisms. The use of sequential BCR extraction and ecotoxicity analyses allowed for a multi-facetted generic risk assessment of metals in sediments of dam reservoirs. [Display omitted] • The quality of sediments is a key factor for water ecosystem and public health. • Geochemical, ecological, chemical, and ecotoxicological indices were used. • Enrichment Factor and TRI (∑TRI) were the most useful indices. • Cd, Zn, Pb have the greatest impact on sediment contamination and risks to organisms. • Mobile fractions of metal and ecotoxicity tests are indispensable for risk assessment. [ABSTRACT FROM AUTHOR]

A greenhouse experiment was performed to evaluate the effects of organic amendments (compost and biochar) and vegetation ( Brassica juncea L.) on the metal fractionation of Cu, Ni, Pb and Zn in a soil of a depleted copper mine. The influence of organic amendments alone (compost + biochar) and combined with mustard plants ( B. juncea L.) was assessed. The addition of increasing doses (20, 40, 80 and 100%) of compost and biochar to the soil allowed plants both to survive and grow, as mustard plants were not capable of surviving in the untreated mine soil. These materials improved the soil conditions by increasing the soil pH values from 2.7 to 8.7, soil C from values below the detection limit to 149 g kg − 1 , soil N from values below the detection limit to 11.1 g kg − 1 , generally reduced the CaCl 2 -extractable concentration of metals in the soil, reduced the mobility factor of Cu (from 19.4 to 2.4), Ni (from 52.7 to 7.3) and Pb (from 29.9 to 4.6) and they also reduced metal concentrations in the mobile soil fractions. However, the used compost increased the Zn pseudototal concentration in the amended soils from 73.6 mg kg − 1 to 330 mg kg − 1 . It was concluded that the combined use of compost and biochar with B. juncea provides scarce additional benefits for remediating a Cu-contaminated mine soil compared with only the addition of the organic amendments. [ABSTRACT FROM AUTHOR]

Paradigm change in the demographic distribution in the Indian subcontinent has positioned urban services, including solid waste disposal, under immense pressure. The present study was an attempt to understand the fate of different metals from municipal solid waste (MSW) in the land disposal environment. Accordingly, the characteristics and ecotoxicity potential of MSW of two cities of the region namely, Guwahati and Tezpur were determined. Concentration of bioavailable metals was lower in Tezpur MSW (TMSW) as compared to Guwahati MSW (GMSW). Significant occurrence of various functional groups (O–H, C O, C–C etc.) in the MSW samples indicated predominance of aromatic hydrocarbons. Human risk assessment reveals high possibility of metal contamination from the GMSW. Saturation indices of water solubility data modeled in Visual MINTEQ predict that Calcite (CaCO 3 ) and Zn based minerals could potentially precipitate from both MSWs. Visual MINTEQ is a useful geochemical data analysis tool that computes the mass distribution between the dissolved, adsorbed, and various solid phases of different elements. Furthermore, the mobility dynamics of various fractions of toxic metals or potentially toxic elements (PTEs) such as Fe, Cr, Cu, Ni, Pb, and Zn, revealed that most of these elements were bound to organic and residual fractions. [ABSTRACT FROM AUTHOR]

Due to their toxicity, persistence, and bioaccumulation, metals are important marine environment pollutants, especially in low renewal rate water such as the Mediterranean Sea, receiving a lot of untreated industrial waste. The impact of a phosphate fertilizer plant on the marine biota metal contamination was studied. Several types of organisms: crabs, mussels, patella and fish were collected from two areas of the Lebanese coast, one subjected to the impact of the plant and another away from it; samples were analyzed for Zn, U, Cr, V, Mn, Ni, Co, Cu, As, Cd and Pb by ICP-MS. Higher accumulation was in crabs, patella, and mussels. Fish accumulated principally Zn, Cu, and Cd; a difference was observed between species and tissues. Cytosol metal fractionation using size-exclusion LC-ICP-MS showed principally Pb, As, Co, and Mn in the low molecular weight fraction (<1.8 Da); Cd, Zn, and Cu in the metallothionein fraction (1.8--18 k Da), and Ni in high molecular weight fraction (>20 kDa). [ABSTRACT FROM AUTHOR]

The continuous stream of polluted sediments, dredged from harbors and water bodies in order to maintain the navigation, is a common practice, but the fate of these sediments is an issue recognized worldwide. This pilot case study evaluated the application of phytoremediation as sustainable management strategy for the decontamination of polluted dredged marine sediments. The treatments were based on the use of different plant species ( Paspalum vaginatum Sw.; P. vaginatum Sw. + Spartium junceum L.; and P. vaginatum Sw. + Tamarix gallica L.) and organic matter (compost). The synergic action of plants and compost in removing both heavy metals (Cd, Ni, Zn, Pb, and Cu) and total petroleum hydrocarbons, and in recovering the nutritive and biological sediment properties were evaluated. In addition to the detection of total metal removal efficiency, the chemical distribution of metals in the sediment phases (exchangeable, manganese and iron oxides, organic matter, and residual minerals) was also measured in order to make a more realistic estimation of the phytoremediation efficiency for the sediment decontamination. Finally, a complete picture of the metal flux was obtained by investigating the metal mass-balance in the treated sediments. The results of metal content in the sediment phases showed that metal distribution was not uniform and each metal predominated in different fractions; the bioavailability of metals in the initial and treated sediments at 0–20 cm in the decreasing order was: Cd > Zn > Cu > Pb > Ni. The higher proportion of Ni and Pb in the residual phase can be the reason of the lower translocation of these metals in the plant tissues. On the other hand, Cd, Zn, and Cu were the metals most easily translocated in plant tissues, both aboveground and roots, confirming their higher bioavailability for the plants. The results of mass balance indicated that, at the end of the experimentation, a high content of metals were still found in the sediment. The greatest contribution in metal containment was attributed to a phytostabilization process at rhizosphere level followed by gravel and sand absorption. The capacity of rhizophere to precipitate heavy metals, could be considered as an alternative option for reducing the metal availability and, consequently, the toxicity in contaminated sediments. [ABSTRACT FROM AUTHOR]

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In this study, step-wise extraction using various extracting agents was carried out in order to enhance the removal of metals from contaminated dredged marine sediment. Five-times repeated extraction using HCl could extract approximately 23% of the As from the sediment, while NaOH extracted 14% of the As with a single extraction. An alternate application of EDTA and HCl extracted 17%, 34%, 9%, 87%, and 41% of the Cd, Cu, Ni, Pb, and Zn, respectively. Step-wise extraction reduced the risk index (RI) of heavy metals to 49% compared with untreated sediments, which were caused mainly from the decrease in the Cd concentration after chemical extraction in sediment. [ABSTRACT FROM AUTHOR]

Toxicity and uptake of heavy metals of sewage sludge by beans (Phaseolus vulgaris L.) were evaluated in green house experiments. Treatments consisted of 1,0 ; 2,0 and 5,0% (m/m) of dry sewage sludge, collected from Londrina (Bom Retiro and ETE-Sul) and Curitiba (ETE-Belém and RALF). Bean ( variety IAPAR 57) was sown three times at 0, 120 and 240 days after the treatments have been applied. Contents of Cd, Cr, Co, Cu, Ni, and Pb in bean tissues cultivated with 5,0% (m/m) of all sewage sludge were similar to the control and Ba contents were reduced by increasing the quantity of sewage sludge in the soil. The Zn content in tissue bean incresed from 86 mg kg-1 of control to 462 mg kg-1 by applying 5% (m/m) of sewage sludge in soil, but plant beans did not show toxicity symptons. The addition of 5% (m/m) of sewage sludge increased Mn content in plants, from 193 mg kg-1 of control to 1.960 mg kg-1, showing toxity in bean leaves when the contents were more than 500 mg kg-1. The addition of sewage sludges in soils increased only available Zn carbonate and Cu organic species.

Overload of coal ash (CA) generated from several coal fired plants poses acute problems of disposal and contamination of soil and water resources. Since CA generated from tea factories has not yet been characterized from environmental viewpoints, we attempted to critically characterize the agro-ecological compatibility of CA samples (CA1, CA2, CA3, and CA4) collected from four distantly located tea factories. Among these samples, we found CA3 and CA4 to have low pH and high metal content. Accordingly, we restricted our study to predict the solubility pattern of non-metal and metal ions in CAs by adopting a geochemical model (Visual MINTEQ). Various fractions of metals like Fe, Mn, Cu, Zn, Cr, Ni, and Pb were studied to figure out the mobility pattern of metals in the environment. The results clearly indicate that tea industry derived CA substantially differs from thermal power plant CA as regards several physico-chemical properties, for example, sandy texture, low pH and high nutrient content. Risk evaluation of human exposure to trace elements and the metal fractionation study led us to conclude that CA1 and CA2 are highly compatible with agricultural use. [ABSTRACT FROM AUTHOR]

Zinc (Zn) deficiency is widespread in alkaline and calcareous soils. Limited information is available on the effect of preceding crops on the distribution of Zn in soil solid phase. This field study was conducted to investigate the changes in Zn chemical forms in soil solid phase as affected by four preceding crops [Sunflower (Heilianthus annuusL. cv. Allstar), Sorghum (Sorghum bicolorL. cv. Speed Feed), Clover (Trifolium pratenseL.) and Safflower (Carthamus tinctoriusL. cv. Koseh-e-Isfahan)] in a calcareous soil. A control treatment with no preceding crop (fallow) was also used. Our results showed that the preceding crops increased Zn concentration in exchangeable fraction (EXCH-Zn), the organically bound zinc form (ORG-Zn) and zinc bound to iron and manganese oxides (FeMnOX-Zn) while decreased carbonates bound-zinc (CAR-Zn) and residual zinc forms (RES-Zn). However, the changes in Zn fractions were dependent on the preceding crop type. The EXCH-Zn and ORG-Zn pools can be considered labile pools that play significant roles in supplying Zn for plants. Among the preceding crops used in this experiment, clover (Clo) had the highest effect on transforming CAR-Zn form to EXCH-Zn and ORG-Zn labile forms and thus resulted in the highest Zn accumulation in tissues of the target wheat (TriticumaestivumL. cv. Back Cross). Although the changes in chemical forms of Zn in the soil solid phase are complex and dependent on various factors, our findings showed that the preceding crops significantly increased the concentration of Zn in exchangeable and organic matter pools and in turn resulted in higher uptake of Zn by the target wheat. [ABSTRACT FROM PUBLISHER]

BACKGROUND Metals can be present in tea infusion as ions or as complexes with endogenous bioligands naturally occurring in tea, especially with polyphenols. Their chemical form, i.e. free or metal complexes, can affect their actual bioavailability, gastrointestinal absorption and possible toxicity. RESULTS The total amount of Al, Cu, Fe, Mn, Ni and Zn in black tea infusions was determined by inductively coupled plasma-atomic emission spectroscopy after mineralization and compared with their fractions occurring as polyphenol complexes, extracted using two different polymeric resins: Amberlite XAD-2 and Amberlite XAD-7. CONCLUSION The obtained results demonstrated the suitability of Amberlite resins for the extraction of Al, Cu, Fe, Mn, Ni and Zn-polyphenol complexes from black tea infusions and for the evaluation of the actual distribution of the considered metals among different chemical species, i.e. as free metals and as polyphenol complexes. © 2013 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Purpose: Frequent mining activities and higher background values in soil have led to the contamination of the sediments of some rivers in southwest China by several metals and arsenic (As). This study combined multivariate analysis with geochemical approaches to differentiate mining activity from other sources, which may aid to evaluate the effectiveness of reducing mining release. Materials and methods: Sixteen sediment samples were collected along the Yuan River, China. The total concentrations of lead (Pb), zinc (Zn), copper (Cu), cadmium (Cd), chromium (Cr), mercury (Hg), and As were measured by inductively coupled plasma-atomic emission spectrometer (ICP-AES). The Pb isotopic composition was measured using a thermal ionization mass spectrometer (TIMES). Both geochemical approaches and multivariate statistical analysis were used to identify the sources of these metals. The fractionation of Pb was determined through a Community Bureau of Reference (BCR) sequential extraction procedure to aid the identification of the sources. Results and discussion: The concentrations and enrichment factors (EFs) of Pb, Zn, Cu, Cd, and As in the middle reach of the river were higher than those at the other sites, indicating anthropogenic sources. The factor analysis (FA) extracted 'mining and smelting,' 'mixture of anthropogenic and natural,' and 'natural' factors. The Pb isotope composition of metal ores was similar (Pb/Pb < 1.190 and Pb/Pb > 2.023) to that found in the sediments in the middle reach, indicating anthropogenic sources of mining activities. Compared with the narrow ranges of the δS ratios in the bedrock (+8.5 to +9.3 ‰) and the metal ores (−1.4 to +1.9 ‰), the sediment samples presented a relatively wide range of δS ratios from −2.6 to +9.2 ‰ with a mean of +2.6 ‰, which suggests a mixed composition. The BCR sequential extraction procedure revealed that the proportion of the extractable fraction in the sediments in the middle reach was higher than that in other sites, suggesting anthropogenic sources as the cause of contamination in the study area. Conclusions: Lead, Zn, Cu, Cd, Cr, Hg, and As are mainly derived from natural materials in the upstream region. In the middle reach, these elements are the result of anthropogenic activities, particularly activities associated with the mining industry. In the downstream region, the origin of these elements is considered to be a mixture of anthropogenic and natural sources. In addition to geochemical approaches and multivariate statistical analysis, the BCR sequential extraction method is an effective procedure for the identification of the anthropogenic sources of sediment-associated metals. [ABSTRACT FROM AUTHOR]

Highlights: [•] Two sequential schemes discriminating different oxide phases were used. [•] Tucker4 model made possible to visualize and explain the data set information. [•] Although different, the 2 sequential procedures used give similar information. [•] Metal mobility/availability was assessed for estuarine sediment samples. [ABSTRACT FROM AUTHOR]