Chemical Partitioning Of Heavy Metals Research Articles

Lead and zinc chemical fraction alterations in multi-metal contaminated soil with pomelo peel biochar and biochar/apatite incubation

The issue of heavy metal soil contamination is widespread, and the negative effects of heavy metals on the ecosystem depend on their chemical speciation in contaminated soil. Pomelo peel-derived biochar produced at 300 °C (PPB300) and 500 °C (PPB500) and its combination with apatite ore (AP) was applied to immobilize lead (Pb) and zinc (Zn) in agricultural multi-metal polluted soil. Soil amendments including biochar (PPB300 and PPB500) at concentrations of 3%, 5%, and 10%, as well as a mixture of biochar and apatite (AP) at 3:3% and 5:5% weight ratios, were introduced into the soil matrix. The chemical forms of Pb and Zn in incubated soil samples and control soil (CS) were studied utilizing the Tessier’s sequential extraction procedure. The chemical partitioning of heavy metals was carried out using Tessier’s extraction protocol, yielding fractions representing exchangeable (F1), carbonate (F2), Fe/Mn oxide (F3), organic matter (F4), and residual (F5) forms. Quantification of Pb and Zn concentrations was accomplished via inductively coupled plasma mass spectrometry (ICP-MS). Observations revealed notable elevations in pH, organic carbon (OC), and electrical conductivity (EC) levels within the treated soil relative to the control soil (p < 0.05). After incubating PPB300, PPB500, and AP for 30 days, there was a reduction in the exchangeable fraction of Pb and Zn by approximately 64% and 58% respectively. This reduction was achieved by transforming heavy metals from mobile fractions to immobile fractions using five primary mechanisms: chemical and physical adsorption, electrostatic attraction, the formation of complexes via interactions with active groups, cation exchange processes, and precipitation events mediated by phosphate, carbonate ions, or hydroxyl ions within an alkaline environment. Therefore, pomelo peel-derived biochar and the blend of biochar/apatite show promise as materials for mitigating heavy metal pollution in soil.

Comprehensive assessment of heavy metal pollution and ecological risk in lake sediment by combining total concentration and chemical partitioning.

Total concentration and chemical partitioning of heavy metals are commonly used in environmental quality assessment; however, their comparability and comprehensive application are far less discussed. Herein, bioavailability, pollution and eco-risk of As, Cd, Cr, Cu, Ni, Pb and Zn in surface sediments of Erhai Lake were evaluated referring to multiple indices following the experimental methods of complete digestion, optimized Community Bureau of Reference (BCR) and 1.0M HCl extractions. Results of bioavailability for most metals were similar and comparable from BCR and HCl extractions. While bioavailable concentrations of Cd and Pb from HCl extraction were significantly (p<0.01) lower than those from BCR extraction, indicating BCR extraction is more efficient. Results of enrichment factor (EF) and concentration enrichment ratio (CER) suggested that Cd was the highest polluted element followed by As, Pb and Zn, whereas Cr, Cu and Ni were mainly natural in origin. Similar concentrations of anthropogenic As from EF and CER assessments indicated anthropogenic As mainly existed in bioavailable form. However, anthropogenic Cd, Pb and Zn existed in both bioavailable and residue forms, resulting in the underestimation of anthropogenic metals by the CER assessment. The sediment quality guidelines (SQGs), potential ecological risk index (Er) and risk assessment code (RAC) showed inconsistent eco-risks for each of the metals except Cd. Combining pollution level and chemical partitioning with SQGs, Er and RAC assessments, high eco-risk of Cd, moderate eco-risk of As and Pb, and low eco-risk of Cr, Cu, Ni and Zn were graded. Our study highlights the limitation of single index and the necessity of integrating multiple indices following total concentration and chemical partitioning in metal pollution and eco-risk assessments.

Anthropogenic contamination and risk assessment of heavy metals in stream sediments influenced by acid mine drainage from a northeast coalfield, India

The total concentrations and chemical partitioning of heavy metals in streambed sediments, collected around the Jaintia Hills coal deposit of northeast India, were studied using pollution indices and multivariate techniques to evaluate the risk and contamination levels from heavy metals and their possible origins. Results show that sediments close to mining sites have low pH (<4), high organic carbon, and contain significant amounts of Fe-oxyhydroxide phases (mainly, goethite and schwertmannite), which implies direct impact of coal mine drainage. The average concentrations of Fe, Cu, Co, Cd, Cr, and Zn exceeded the World average, and in some cases, Cd, Cu, Ni, and Cr concentrations exceeded the threshold effects level, which suggests they will be toxic to aquatic biota. Contamination factors (CF) show that the sediments are low to highly contaminated with Cd, Cu, Mn, Pb, Fe, and Zn and low to moderately contaminated with Co, Cr and Ni. The pollution load index (PLI), degree of contamination index (C deg) and Nemerow integrated pollution index (NIPI) show that the sediments are moderately to highly contaminated, with the extent of pollution greatest nearest to the collieries. The potential ecological risk index (RI) shows low to considerable ecological risk from heavy metals in the sediments, with Cd having the high potential of risk, which also agrees with the risk assessment code (RAC). Multivariate statistical analysis suggests that the concentrations of the heavy metals in stream sediments are strongly influenced by Fe-oxyhydroxide phases and organic carbon derived from anthropogenic sources, mainly coal mining activities. Although a significant proportion of the Cd, Mn, and Ni in the sediments are partitioned into exchangeable and organic fractions, a sizable amount of metals are also found in the Fe–Mn fraction, suggesting that Fe-oxyhydroxides play a dominant role in controlling metal mobility in these stream sediments.

Heavy metal partitioning in sediments and bioaccumulation in commercial fish species of three major reservoirs of river Cauvery delta region, India

Chemical partitioning of heavy metals (Fe, Mn, Cu, Cr, Pb, Zn, Ni) were determined in surface sediments of three reservoirs at the Delta region of Cauvery River, India. The abundance of metals in sediments varied in the following descending order: Fe, Mn, Cr, Zn, Cu, Ni, and Pb. Higher concentrations of Zn, Pb, Fe, Mn and Cu in exchangeable and carbonate fraction indicated toxicity risk to the biota. Therefore, to understand the extent of bioaccumulation, six commercial fish species were collected from the same sites and analyzed for heavy metals distribution in different organs. Among the metals found in fish samples, iron was observed in the highest concentration, followed by Zn, Pb, Cr, Mn, Cu, and Ni. Concentrations of Pb, Cr and Zn in many fish samples exceeded the permissible limits of Food and Agriculture Organization. The concentrations of Pb (17.7–31.7%), Cr (6.2–15.1%), Cu (15.2-30.5%) and Zn (30–40%) associated with exchangeable and carbonate fractions had significant positive correlation with the respective metal concentrations in fish. Among the fish species, Catla catla and Etroplus suratensis showed the highest accumulation of metals suggesting risk for human consumption.

Distribution and chemical partitioning of heavy metals in marine near-shore sediment cores: a case study from the Xugou, Lianyungang, China

The concentrations and chemical partitioning of heavy metals (Co, Cr, Ni, Zn, Cu, and Pb) in the marine near-shore sediment cores were investigated. Typically, the mean concentrations from Core B sediment samples were 98.6, 21.1, 47.0, 46.4, 107.6, and 31.9 mg kg( - 1) for Cr, Co, Ni, Cu, Zn, and Pb, respectively. The heavy metal concentrations were normalized to commonly used reference elements Al, Li, Sc, and total organic carbon. Based on Pearson coefficients, Li was found to be a good normalizer for Co (r = 0.974), Cr (r = 0.967), Ni (r = 0.898), and Zn (r = 0.929) in 80 sediment samples from three sampling sites. However, the correlation coefficients between Li and Cu, and Li and Pb were relatively low. Multivariate statistic approaches (Principal Component Analysis and Cluster Analysis) were adopted for data treatment, allowing the identification of two main factors controlling the heavy metal variability in the sediments. Heavy metals in the enrichment sections were evaluated by a sequential extraction method for possible chemical forms in sediments. The results showed that the residual, Fe/Mn oxides and Organic/sulfide fractions were dominant geochemical phases in the enriched sections, indicating low bioavailability of heavy metals in sediments.

Effects of earthworms on metal uptake of heavy metals from polluted mine soils by different crop plants

A pot experiment was conducted in order to assess the effect of the earthworm Eisenia fetida on the uptake of Pb, Zn, Cd and Cu from soils polluted by mining activities using maize ( Zea mays) and barley ( Hordeum vulgare). Results from single and sequential extractions showed that the soil chemical partitioning of heavy metals was significantly changed by E. fetida, leading to a higher concentration of metals in the non-residual fractions of the soil. Earthworm activities significantly increased shoot biomass (65% for maize and 73% for barley) and root metal concentration for all the metals under study in both maize and barley. The total accumulation rate values for Cd, Cu, Pb and Zn were significantly higher in the presence of E. fetida for both crop plants. Those latter effects led to an increase in Zn extraction yields of up to 3.7-fold and 2.3-fold for barley and maize, respectively.

달천광산 주변 토양 내 비소의 존재형태 및 토양세척법에 의한 제거

This study has been carried out to examine the feasibility of soil washing process for reducing arsenic contamination level of soil around Mine. The results of physicochemical tests of the target soil showed that pH was weak alkalic (), soil texture was coarse sand, and organic contents (5.7%) and CEC (Cation exchange capacity; 21.5 meq/100 g) were similar with those of soils generally found in Korea. Contamination levels of arsenic were found to over 201 mg/kg which exceed the Korea standard levels of countermeasure and concern. To investigate chemical partitioning of heavy metals, sequential extraction procedures were adopted and it was found that arsenic was predominantly associated with the residual fraction among five fractional forms as much as over 85%, which is demonstrating that only less than 15% of all might be vulnerable to a selected washing agents. Among 6 kinds of washing agents applied on the screening for arsenic-contaminated soil, HCl and solution were selected as promising washing agents. In comparison with HCl and solutions for arsenic washing by kinetic experiment in the change of pH, soil-solution ratio, temperature, and washing solution concentration, solution was determined to best one of agents tested, which showed faster washing rate than HCl to accomplish regulatory goal.

Origin and chemical partitioning of heavy metals in riverbed sediments

In the present investigation, bulk and chemical partitioning of elements in the Shefa-Rud riverbed sediments are studies. Higher concentrations of elemental concentrations have been observed in estuarine zone when compared with riverine sediments (except for AI, Fe, Pb and Mn). Manganese is mobilized under anoxic conditions prevailing in the Caspian Sea. Lithogenous materials are greatly diluted in the estuarine zone by various pollutants present in the Caspian Sea. Organic metallic bonds are not significantly present in the area of study. Geological units of the area of study have resulted in the lower concentrations of elemental concentrations of riverbed sediments when compared with published values for mean crust and world sediments ones. Though, cluster analysis has clearly shown the importance of alumina-silicates in controlling the distribution of Fe and Mn in riverbed sediments but it could not depict controlling mechanism for other studied elements. Geochemical Index (Igeo) and Enrichment Factor (EF) values are indicative of a clean environment throughout the river course. These values are in a well agreement with results of chemical partitioning data. Quantification of EF values is not logically possible and therefore Igeo values can be used more effectively.

Determination of pollution trends in an abandoned mining site by application of a multivariate statistical analysis to heavy metals fractionation using SM&amp;T-SES

The mobility, availability and persistence of Heavy Metals (HMs), As, Cd, Cu, Ni, Pb and Zn, in contaminated soils of a former abandoned mining area were evaluated by means of a sequential extraction scheme (SES) and applying a multivariate statistical analysis to the obtained data. Chemical partitioning of HMs in each sample was determined in four fractions (acid-soluble, reducible, oxidable and residual) following the Standard Measurements and Testing (SM&T) SES, formerly BCR-SES. Statistical evaluation of results by pattern recognition techniques allowed identification of groups of samples with similar characteristics and observations of correlations between variables, determining the pollution trends and distribution of HMs within the studied area. Typical metal-fraction association and metal availability characteristics of heavy metals have been depicted. The obtained results indicate an urgent need to attenuate the hazard in that area posed by high concentrations of toxic metals, which exceed the limits specified by different European legislations on soil reclamation.

Distribution of Forms of Heavy Metals in Soils Contaminated by Metallurgical Smelter Emissions

The objective of this study was to investigate the chemical partitioning of heavy metals occur in soils polluted with metallurgical smelters as well as to estimate potential mobility of these metals. Six soil profiles situated at different distances from metallurgical smelters were chosen and soil samples were taken from top- and sub-surface layers. Total contents of metals were much higher in top-soil than in sub-surface soil and varied in the following ranges (mg kg−1): Cu, 1–298; Zn, 2.4–322; Pb, 2.8–196; Cd, 0.34–2.04; Cr, 1.89–6.68; Ni, 2.59–10.15. The speciation of metals (Cu, Zn, and Pb) originating from metallurgical smelters showed considerably higher percentages of exchangeable and carbonate fractions which were likely to be leached from surface layer of sandy soils. The distribution of forms of metals were found to depend strongly both on soil properties and metal origin.

Multivariate statistical study of heavy metal enrichment in sediments of the Pearl River Estuary

The concentrations and chemical partitioning of heavy metals in the sediment cores of the Pearl River Estuary were studied. Based on Pearson correlation coefficients and principal component analysis results, Al was selected as the concentration normalizer for Pb, while Fe was used as the normalizing element for Co, Cu, Ni and Zn. In each profile, sections with metal concentrations exceeding the upper 95% prediction interval of the linear regression model were regarded as metal enrichment layers. The heavy metal accumulation mainly occurred at sites in the western shallow water areas and east channel, which reflected the hydraulic conditions and influence from riparian anthropogenic activities. Heavy metals in the enrichment sections were evaluated by a sequential extraction method for possible chemical forms in sediments. Since the residual, Fe/Mn oxides and organic/sulfide fractions were dominant geochemical phases in the enriched sections, the bioavailability of heavy metals in sediments was generally low. The 206Pb/ 207Pb ratios in the metal-enriched sediment sections also revealed the influence of anthropogenic sources. The spatial distribution of cumulative heavy metals in the sediments suggested that the Zn and Cu mainly originated from point sources, while the Pb probably came from non-point sources in the estuary.

Sorption Isotherm‐Sequential Extraction Analysis of Heavy Metal Retention in Landfill Liners

AbstractThe chemical partitioning of heavy metals in soil materials is of great importance in risk assessment, landfill bottom liner design, and remedial investigation. The sorption characteristics of clayey calcareous sediments used to construct landfill bottom liners at four sites in southeastern Michigan were studied using a new method: combined sequential extraction‐sorption isotherm analysis (CSSA). After spiking to simulate high levels of contamination, the sediments sorbed large quantities of Pb (∼1480–145 000 mg kg‐1), Ni (∼750–8100 mg kg‐1), and Cd (∼980–5070 mg kg‐1). Sequential extraction data indicated that Pb and Ni were principally in a carbonate‐occluded form, whereas Cd was mainly in an exchangeable form at high levels (&gt;1000 mg kg‐1) of contamination. these results suggest that Pb and Ni will be immobilized by the liner materials but Cd will probably be highly mobile. By applying sequential extraction analysis after spiking, Langmuir sorption isotherms were constructed successfully for most of the individually targeted phases. Thus, CSSA appears to be a promising method for predicting the attenuation capabilities of soils and sediments because it allows the sorption capacities of individual phases to be determined while together in a natural system.

Chemical partitioning and remobilization of heavy metals from sewage sludge dumped in Dublin Bay

During the disposal of sewage sludge to the marine environment, chemical changes may alter the mobility of trace elements, thus affecting their potential toxicity and availability to marine organisms. Primary sludge from the Ringsend treatment plant in Dublin receives both domestic waste and trade wastes which contain heavy metals, and approx. 250,000 tons per annum is periodically dumped in Dublin Bay. The purpose of this study was to determine changes which may occur in the chemical partitioning of heavy metals in the sludge during disposal. Samples of sludge were collected from the treatment plant in July 1987. Sequential chemical extraction of heavy metals (Cu, Pb, Cd, Zn, Fe, Mn) was carried out in a nitrogen-filled glove box using 1 M ammonium acetate, 1 M sodium acetate, 0.1 M hydroxylamine HCl (pH 2), 0.2 M ammonium oxalate (pH 3), 30% hydrogen peroxide and concentrated HNO 3. Seawater-extractable metal was determined by mixing subsamples of sludge with filtered seawater from Dublin Bay for 2 h. Chemical partitioning of heavy metals among solid phases in the sludge residue was redetermined by sequential chemical extraction. Both sludge and dumpsite sediments were analysed for total heavy metal content and organic content. The sludge was found to be only slightly anaerobic with a water content of 88% and significant concentrations of some metals, notably copper and zinc. Most of the non-residual copper, lead and cadmium was found in the organic/sulphidic fraction of the sludge (hydrogen peroxide extract), while the dominant phase for zinc was the moderately reducible fraction (ammonium oxalate extract) and only iron and manganese had substantial proportions of metal in more labile phases. Agitation with seawater mobilized cadmium and manganese to a significant extent (56 and 43%, respectively) but negligible amounts of copper or lead (0 and 2%, respectively). However, significant changes in solid-phase partitioning of lead and zinc occurred resulting in mobilization from stronglybound to more labile fractions. No deleterious effects were found at the dumpsite but localized effects are possibly due to the increased mobility of zinc, lead and particularly cadmium.