Modified BCR Sequential Extraction Method Research Articles

Heavy-Metal Speciation Distribution and Adsorption Characteristics of Cr (VI) in the Soil within Sewage Irrigation Areas.

While sewage irrigation relieves water shortages in Northern China, its excessive application triggers a series of environmental problems, such as heavy-metal pollution. Soil profile and river sediment profile samples from the sewage irrigation area (SIA) were collected by selecting the farmlands in which sewage irrigation activity has been reported since the 1960s, around Huiji River (HJR) and Huafei River (HFR) in Kaifeng, Henan Province, China, as research areas. In this study, the total amount of heavy metals (Cr, Cd, Pb, Mn, Zn, and Ni) and the heavy-metal speciation analysis using the modified BCR sequential extraction method were used to evaluate the impacts of wastewater on agricultural soils and the potential risk. Furthermore, the least contaminated Cr (VI) was selected for the study of adsorption characteristics to determine the environmental capacity of soils for heavy metals when the composition of wastewater changes under long-term effluent irrigation conditions. The results show that: (1) the concentrations of heavy metals in soil continuously decreased with depth, while the opposite was observed in sediment, reflecting the continuous improvement in water quality over the historical period; (2) In the topsoil, the mean concentrations (mg·kg−1) in rank order are as follows: Mn (588.68) > Zn (284.21) > Pb (99.76) > Cr (76.84) > Ni (34.71) > Cd (3.25), where Cd exceeded the control value by 3.15 times around HFR, and sediment samples also showed higher heavy metal concentrations in HFR than in HJR; (3) Speciation distribution and risk assessment code (RAC) indicate that Mn and Cd were at medium risk and that Cd warrants attention due to its being a non-essential toxic element in humans; (4) The adsorption rates of soil in various layers in different profiles within SIAs for Cr (VI) gradually increased with the increasing initial content of Cr (VI). Among the three isothermal adsorption models, the fit result obtained by the Langmuir equation was superior to those obtained by the Freundlich equation and the linear equation.

Geochemical fractions of trace metals in surface and core sections of aggregates in agricultural soils

Agrochemicals containing trace metals such as pesticides and fertilizer are intensively used in apple production systems in many countries. There is a risk of accumulation of trace metals, particularly in the sensitive root rhizosphere area. In this study, the trace metal concentrations of soils were determined in macroaggregates at the “mm scale” sampled from apple orchards. Soil samples were taken from five different locations at 0–20 cm soil depths in an apple orchard. Pseudo-total trace metal (Cd, Cr, Cu, Ni, Pb, and Zn) concentrations of soil samples separated from the surface and core sections of the soil aggregate were determined by digestion with Aqua regia. The modified BCR sequential extraction method was used to determine four operationally defined geochemical trace metal fractions in soil samples. The pseudo-total concentrations of Cd and Cu were significantly higher, and Zn was lower at the surface than in the core sections (paired-t test, p < 0.05) of soil aggregates. The concentrations of all trace metals in the acid-soluble fraction and reducible fractions were significantly higher at the surface of soil aggregates than those in the core section. The same was true for the sum of trace metal concentrations in the extracts of the three fractions considered potentially mobilizable, except for Cr. Our results demonstrated that Cd and Cu originated probably from agrochemicals accumulating significantly on aggregate surfaces, where they were in close contact with plant roots. The generally higher extractability of all trace metals on the surface of aggregates can be attributed to the preferential accumulation of newly-added trace metals in comparatively weakly bound chemical forms.

Heavy metal mobility and valuable contents of processed municipal solid waste incineration residues from Southwestern Germany

As conventional end-of-life disposal, municipal solid waste (MSW) incineration residues can be problematic due to potential release of toxic compounds into the environment. Using municipal solid waste incineration residues as urban-mine of valuable metals (e.g. precious metals) could provide a trash-to-treasure possibility. The objectives of the study are to (i) determine the contents of different contaminant metallic elements (Zn, Cu, Ba, Pb, Cr and Ni) in four size fractions of MSW incineration residues and discuss their mobility potential by using the modified BCR sequential extraction method; (ii) investigate the level of valuable critical contents (precious metals, rare earth elements, etc.) in these wastes. We also characterized mineralogy and elemental composition of four different grain size fractions (0–0.5, 0.5–2.0, 2.0–4.0 and 4.0–16.0 mm) of processed municipal solid waste incineration residue (PIR) from the Southwestern region of Germany, using X-ray fluorescence, X-ray powder diffraction and different spectroscopic techniques. Among all studied size fractions, grains smaller than 2 mm contained higher amounts of total extractable heavy metals in most cases. The most important finding of the study is that the total contents of Cu, Au and Pt in the incineration residues reached economically profitable levels (5.1 g/kg, 21.69 mg/kg and 17.45 mg/kg, respectively).

Speciation of nickel and enzyme activities in fluvo-aquic soil under organic amendments treatment

To investigate the efficacy of humic acid and cow dung for nickel (Ni) immobilisation and detoxification in fluvo-aquic soil, the Ni-polluted soil was mixed with amendments of humic acid and cow dung. The Ni speciation (modified BCR sequential extraction method) and enzyme activities were scrutinised. As the humic acid concentration increased (0 to 12 g kg–1), the amount of Ni in the acetic acid-soluble fraction (the bioavailable fraction with high environmental risk) first decreased and then increased. In contrast, the amount of Ni in this fraction continued to decrease as the cow dung concentration increased (P &lt; 0.05). The Ni in the acetic acid-soluble and residual fractions transformed to the oxidisable fraction, leading to lower environmental risk. The fluorescein diacetate hydrolysis and alkaline phosphatase activity were negatively correlated with the amount of Ni in the acetic acid-soluble fraction (r = –0.695 and –0.773, respectively, P &lt; 0.01), indicating that Ni in the acetic acid-soluble fraction was toxic and led to enzyme activity inhibition, and the amendments could reduce subsequent damage. When humic acid concentration ranged from 5.01 to 6.47 g kg–1, the acetic acid-soluble Ni level reached the minimum, while the fluorescein diacetate hydrolysis and the alkaline phosphatase activity reached their maxima. In conclusion, humic acid and cow dung are effective amendments for Ni immobilisation and reduce devastation of soil enzymes. The humic acid concentration should be between 5.01 and 6.47 g kg–1 to achieve the optimum efficacy.

Fractionation And Environmental Risk Of Trace Metals In Surface Sediment Of The East China Sea By Modified BCR Sequential Extraction Method

Geochemical fractionation of Cadmium (Cd), Lead (Pb), Cobalt (Co), Zink (Zn), Iron (Fe) and Manganese (Mn) in sediment of the East China Sea were determined using four-stages of modified BCR sequential extraction method combination with ICP-MS. The total concentration of trace metals in sediment samples were in the following order: Fe &gt;Mn&gt;Pb&gt; Zn &gt; Co &gt; Cd. Cd is present mainly in acid soluble fraction. Pb and Mn are in the group with presenting of easy reducible fraction and acid soluble fraction. Fe and Co were found in a group with mainly in residual fraction, while Zn was distributed in all four fractions. The highest contamination factors were found for Cd and Mn while the lowest were found for Fe and Co in almost station. The result showed low risk for Fe and Co in all station, Pb (except S2 and S3), Zn at S3,S6 and S7, and Mn at S1. A medium risk is indicated for Pb at S2 and S3, Zn at S1 and S5, and Mn at S2 and S6. A high risk showed for Zn at S2 and S4, and Mn at S4 and S5, while Cd at almost station (except S4) was very high risk.

Fractionation of trace elements in agricultural soils using ultrasound assisted sequential extraction prior to inductively coupled plasma mass spectrometric determination

The main objectives of this study were to determine the concentration of fourteen trace elements and to investigate their distribution as well as a contamination levels in selected agricultural soils. An ultrasonic assisted sequential extraction procedure derived from three-step BCR method was used for fractionation of trace elements. The total concentration of trace elements in soil samples was obtained by total digestion method in soil samples with aqua regia. The results of the extractable fractions revealed that most of the target trace elements can be transferred to the human being through the food chain, thus leading to serious human health. Enrichment factor (EF), geo-accumulation index (Igeo), contamination factor (CF), risk assessment code (RAC) and individual contamination factors (ICF) were used to assess the environmental impacts of trace metals in soil samples. The EF revealed that Cd was enriched by 3.1–7.2 (except in Soil 1). The Igeo results showed that the soils in the study area was moderately contaminated with Fe, and heavily to extremely polluted with Cd. The soil samples from the unplanted field was found to have highest contamination factor for Cd and lowest for Pb. Soil 3 showed a high risk for Tl and Cd with RAC values of greater than or equal to 50%. In addition, Fe, Ni, Cu, V, As, Mo (except Soil 2), Sb and Pb posed low environmental risk. The modified BCR sequential extraction method provided more information about mobility and environmental implication of studied trace elements in the study area.

Assessment of metal bioavailability in the vineyard soil-grapevine system using different extraction methods

This study was focused on the assessment of single and sequential extraction methods to predict the bioavailability of metals in the vineyard soil-grapevine system. The modified BCR sequential extraction method and two single-step extraction methods based on the use of EDTA and acetic acid were applied to differently amended vineyard soils. The variety effect was studied on the uptake of metals by leaves and grapes. Most of the elements studied (Ca, Mg, Cu, Fe, Mn, Zn and Pb) were weakly mobilized from vineyard soils, with the exception of Cu and Mn. The determination of total metal content in leaves and grapes showed a different accumulation pattern in the two parts of the vine. A significant relationship was observed, for all the elements studied except for Fe, between the content bioavailable in the soil and the accumulated in both leaves and grapes (R=0.602–0.775, p<0.01).

New process for copper migration by bioelectricity generation in soil microbial fuel cells.

The soil microbial fuel cell (MFC) is a promising biotechnology for the bioelectricity recovery as well as the remediation soil. Moreover, there were no studies on the heavy metal pollution in a soil MFC yet. A soil MFC was constructed to remediate the contaminated soil, and the electric field was generated from the oxidation of the acetate at the anode. We demonstrated the copper migration, the power generation, and the pH variation in the soil and the electrodes. The maximal voltage and the power density of 539mV and 65.77mW/m(2) were obtained in the soil MFC. The chemical fractionation of copper (Cu) was analyzed with a modified BCR sequential extraction method. The soluble Cu form and the total Cu contents from the anode to the cathode increased, and the difference between them kept growing over time. The Cu fractions in the soil and the electrodes were converted with the change of the dramatic pH from the anode to the cathode. There was a focusing effect leading to the change of the Cu forms, and the extractable acid form content increased in the three fifths where the acid and the alkali fronts met.

Research on the ecological risk of heavy metals in the soil around a Pb–Zn mine in the Huize County, China

The soil pollution by heavy metals was characterized in the mine tailings and surrounding soils of an old Pb–Zn mine in Huize County. Three hundred and ninety-six samples of agricultural and non-agricultural soil were analyzed for the total metal concentration by acid digestion and sixty-eight selected soil samples were used to determine the chemical fractionation of heavy metals with the modified BCR sequential extraction method. The pollution index of the heavy metals indices for As, Cd, Cr, Cu, Hg, Pb and Zn of non-agricultural soil and agricultural soils in the study area indicated the spreading of heavy metal pollution. Sequential extraction showed that most of Cd existed in an exchangeable form (31.2 %). The available content of Pb, Cu and Zn was mainly distributed in acid extractable fractions and Fe/Mn oxide fractions (27.9, 30 and 27.2 %), and Hg, As and Cr were mainly associated with residual fractions (90.4, 72.9 and 76.8 %). The risks of heavy metals were also evaluated by the risk assessment code (RAC) and potential ecological risk index, respectively. The results of RAC showed a medium and high risk of Cd (45.6 and 54.4 %), medium risk of Zn (100 %), low and medium risk of Cu (41.2 and 58.8 %), largely no risk of Hg (97.1 %), and mainly low risk of As and Pb (92.6 and 91.8 %). The range of the potential ecological risk of soil was 58.2–1839.3, revealing a considerably high ecological risk in the study area, most likely related to acid mine drainage and the mining complexes located in the area. The results can be used during the ecological risk screening stage, in conjunction with the total concentrations and metal fractionation values, to better estimate ecological risk.

Distribution, bioavailability, and potential ecological risk of Cu, Pb, and Zn in soil in a potential groundwater source area.

In this study, we examined three horizontal and vertical soil profiles along a sewage drainage ditch in order to determine the spatial distribution of Cu, Pb, and Zn in soils and to assess the bioavailability and potential ecological risks associated with these metals in a potential groundwater source area. Results showed that the concentrations of Cu, Pb, and Zn were approximately at background level, suggesting that human activities (industrial and agricultural pollution) had a negligible influence on these metals in soil, and that the concentrations reflected the natural background levels in the study area. Cu, Pb, and Zn concentrations were slightly higher in topsoil (0-20cm) than deeper in the soil profile. Using a modified BCR sequential extraction method to evaluate the mobility and bioavailability of metals showed that the potential bioavailability sequence of Cu, Pb, and Zn at three depths in the soil profile was in the order Cu ≈ Pb < Zn. The potential ecological risk from the metals was evaluated using risk assessment code, and the results suggest that Cu and Zn pose no or low risk, while there is a low or medium risk from Pb. Results from groundwater monitoring showed that the groundwater was not polluted by leaching from soil.

Fractionation and mobility of cadmium and lead in soils of Amol area in Iran, using the modified BCR sequential extraction method

This study was conducted to investigate the total concentration of cadmium and lead as well as their compartmentalisation by the modified BCR sequential extraction method. Also the mobility and contamination factor potential of cadmium and lead was evaluated in soils in Amol area, Iran. Total metals concentrations in Cd and Pb were 0.096±0.036 and 24.97±0.83 (μg g-1), respectively. The sum of the fractions was consistent with the total content of each metal. Cadmium was mainly associated with the reducible, exchangeable-acid soluble and oxidisable fractions. Lead was mainly associated with the residual, reducible and oxidisable fractions. Cadmium had a higher mobility potential in all soil samples than lead. Cadmium had a lower retention time than lead.

Application of Modified BCR Sequential Extraction Method for the Fractionation and ICP-OES Determination of Copper in Asphaltite Combustion Waste

Application of Modified BCR Sequential Extraction Method for the Fractionation and ICP-OES Determination of Copper in Asphaltite Combustion Waste

Land use changes and metal mobility: Multi-approach study on tidal marsh restoration in a contaminated estuary

Inundation of formerly embanked areas in order to combine flood control and tidal marsh restoration will be applied increasingly. However, areas suitable for the implementation are often found to be contaminated. Re-inundation of metal contaminated soils can have consequences on total metal concentrations as well as metal mobility. In this study, metal mobility in a tidal marsh restoration project was evaluated based on the modified BCR sequential extraction method, concentrations of acid volatile sulfides (AVS) and simultaneously extracted metals (SEM) and metal concentrations in plants. The results obtained from the sequential extraction suggest an increase in metal mobility following inundation due to the reduction of Fe and Mn oxides and the subsequent release of associated metals. However, the differences in results between sequential extraction and [SEM–AVS] may indicate that redistribution of the metals to the mobile fraction can be caused by sample processing. High AVS concentrations in newly deposited sediments in the restored marsh may indicate that the formation of insoluble metal–sulfide complexes will reduce metal mobility on the longer term. Processes following inundation of metal contaminated land are complex and different conditions prevailing in other sites or estuaries can result in different behavior of the trace metals. More in situ research is needed to get a better insight in the risks involved.

Heavy Metals in Soil and Salad in the Proximity of Historical Ferroalloy Emission.

Emissions of manganese (Mn), lead (Pb), iron (Fe), zinc (Zn), copper (Cu) from ferro-alloy operations has taken place in Valcamonica, a pre-Alp valley in the province of Brescia, Italy, for about a century until 2001. Metal concentrations were measured in the soil of local home gardens and in the cultivated vegetables. Soil analysis was carried out using a portable X-Ray Fluorescence (XRF) spectrometer in both surface soil and at 10 cm depth. A subset of soil samples (n = 23) additionally was analysed using the modified BCR sequential extraction method and ICP-OES for intercalibration with XRF (XRF Mn = 1.33 * total OES Mn - 71.8; R = 0.830, p < 0.0001). Samples of salads (Lactuca sativa and Chichorium spp.) were analyzed with a Total Reflection X-Ray Fluorescence (TXRF) technique. Vegetable and soil metal measurements were performed in 59 home gardens of Valcamonica, and compared with 23 gardens from the Garda Lake reference area. Results indicate significantly higher levels of soil Mn (median 986 ppm vs 416 ppm), Pb (median 46.1 ppm vs 30.2 ppm), Fe (median 19,800 ppm vs 13,100 ppm) in the Valcamonica compared to the reference area. Surface soil levels of all metals were significantly higher in surface soil compared to deeper soil, consistent with atmospheric deposition. Significantly higher levels of metals were shown also in lettuce from Valcamonica for Mn (median 53.6 ppm vs 30.2) and Fe (median 153 vs 118). Metals in Chichorium spp. did not differ between the two areas. Surface soil metal levels declined with increasing distance from the closest ferroalloy plant, consistent with plant emissions as the source of elevated soil metal levels. A correlation between Mn concentrations in soil and lettuce was also observed. These data show that historic ferroalloy plant activity, which ended nearly a decade before this study, has contributed to the persistence of increased Mn levels in locally grown vegetables. Further research is needed to assess whether this increase can lead to adverse effects in humans and plants especially for Mn, an essential element that can be toxic in humans when exceeding the homeostatic ranges.

An investigation of the biogeochemistry of the uranium radionuclide in the munitions testing contaminated soil of Kirkcudbright, New Galloway, SW Scotland

The understanding of the bio-geochemical behavior of the uranium radionuclides in the environmental matrices is crucial for the health safety point of view. The research was carried out in munitions testing sites New Golloway (SW) of Scotland at the Dunderann firing range which is contaminated with depleted uranium and site is particularly important because it provides a controlled environment for the investigation of post depositional association of Depleted Uranium (DU) in contaminated soils. This study used the modified BCR sequential extraction method to investigates the association of DU in at the different sampling location and in a control soil and were followed by elemental analysis using inductively coupled-optical Emission spectroscopy (ICP-OES).The Certified Reference Material (CRM) were used for the validation of the concentration. The concentrations of (Bureau of Reference) BCR-extracted Uranium (U) were in the range of 4-40 (±13.2) mg kg -1 for the DU-contami- nated sites whilst U was barely detectable in the soil from the control site (Rebury Gun) RGW. With the exception of RGH and RGW, the values for BCR-extracted U compared well with those obtained using Aqaua-regia. The obtained result showed that the maximum Uranium deposition is at RGE and it is 20 mg kg -1 before hitting the target, the 6m g kg -1 at RGH and minimum is at RGG and RGW

Metal contents and fractionation in contaminated soil after column leaching using [S, S]-EDDS

Column leaching using [S, S]-ethylene diamine disuccinate ([S, S]-EDDS) on copper tailing soils was carried out to investigate metal content and fractionation after leaching. The soil column was divided into four layers after leaching. Fractionation of Cu, Pb, Zn, and Mn in soil was analyzed using a modified BCR sequential extraction method. Metal contents (Cu, Pb, Ca, Mn) in soil layers increased with the depth of the soil column after leaching in the [S, S]-EDDS treatment. The cumulative extraction efficiency was approximately 43.1% for Cu, 26.8% for Zn, 19.5% for Pb, 10.5% for Ca, 2.07% for Mg, 58.5% for Mn, and 7.92% for Fe. The removal of the reducible fractions of Cu and Mn and the exchangeable fraction of Zn was the most significant in the treatment with [S, S]-EDDS. The exchangeable fraction of Pb was the main fraction that was affected by leaching using [S, S]-EDDS. Distribution of Cu and Mn were severely modified by leaching with [S, S]-EDDS. Percentages of residual fractions of the tested heavy metals in the treatment with [S, S]-EDDS after leaching were much higher than that in the control. Although column leaching using [S, S]-EDDS could remove target metals effectively and impaired their availability, it also dissolved large amounts of major elements and modified the distribution of Mn appreciably.

Heavy metal distribution and chemical speciation in tailings and soils around a Pb–Zn mine in Spain

Soil pollution by lead, zinc, cadmium and copper was characterized in the mine tailings and surrounding soils (arable and pasture lands) of an old Spanish Pb–Zn mine. Sixty soil samples were analyzed, determining the total metal concentration by acid digestion and the chemical fractionation of Pb and Zn by the modified BCR sequential extraction method. Samples belonging to mine waste areas showed the highest values, with mean concentrations of 28,453.50 mg kg −1 for Pb, 7000.44 mg kg −1 for Zn, 20.57 mg kg −1 for Cd and 308.48 mg kg −1 for Cu. High concentrations of Pb, Zn and Cd were found in many of the samples taken from surrounding arable and pasture lands, indicating a certain extent of spreading of heavy metal pollution. Acidic drainage and wind transport of dust were proposed as the main effects causing the dispersion of pollution. Sequential extraction showed that most of the Pb was associated with non-residual fractions, mainly in reducible form, in all the collected samples. Zn appeared mainly associated with the acid-extractable form in mine tailing samples, while the residual form was the predominant one in samples belonging to surrounding areas. Comparison of our results with several criteria reported in the literature for risk assessment in soils polluted by heavy metals showed the need to treat the mine tailings dumped in the mine area.

Distribution of heavy metals of agricultural soils of central Greece using the modified BCR sequential extraction method

The state of heavy metal (Cd, Cu, Ni, Zn, Pb, and Cr) pollution was studied, in 440 texturally different soil profiles in Thessaly, an intensely cultivated region in Central Greece. The study was carried out in 2004 and 2005 on 220 soil samples for each year. Soil samples were classified in three soil orders: Endisols, Alfisols, and Vertisols according to the Soil Taxonomy System. The pseudo-total concentrations of heavy metals were determined by the aqua regia procedure. Heavy metals were also determined after division into four fractions by sequential extraction with (a) acetic acid (exchangeable and specifically adsorbed metals), (b) a reducing agent (bound to Fe/Mn hydroxides), (c) an oxidizing agent (bound to soil organic matter), and (d) aqua regia (bound to mineral structures, residual). The concentrations of all the metals studied were higher in the topsoil (0–30 cm) and lower in the second soil layer (30–60 cm). Concentrations of 70–82% of Cd, 39–64% of Cu, 41–69% of Ni, 29–51% of Zn, 75–89% of Pb, and 52–87% of Cr were found in the first two fractions. Cd appeared to be the most mobile of the metals studied, while Cu and Zn were found in forms associated with soil organic matter. The chemical partitioning patterns of Pb and Cr indicated that these metals are largely associated with the Fe–Mn hydroxides, while Cr was also found in the residual fractions. Significant correlations between heavy metals fractions and soil physicochemical parameters were obtained and discussed.

Investigation of heavy-metal uptake by vegetables growing in contaminated soils using the modified BCR sequential extraction method

The heavy metal (Cu, Fe, Co, Ni, Cd, Cr, Pb, Zn, and Mn) concentrations in soils and in vegetable samples, i.e. lettuce (Lactuca sativa L.), parsley (Petroselinum crispum), dill (Anethum graveolens), and onion (Allium cepa L.), taken from three urban vegetable gardens in Kayseri, Turkey, were determined by FAAS. The modified three-step sequential extraction procedure proposed by the European Bureau of References (BCR), now the Standards, Measurements and Testing Programme, was used in order to evaluate trace elements mobility in soil samples, and heavy-metal uptake by vegetables. Three operationally defined fractions were isolated using the BCR procedure: acid extractable (i.e. bound to carbonates), reducible (bound to Fe/Mn oxides), and oxidizable (bound to organic matter and sulphides). The vegetable samples were prepared to analysis using the wet-ashing procedure. To estimate the accuracy of the method used in analysis of the vegetable samples, the standard reference material (NIST SRM 1573a, Tomato leaves) was used. The results of recovery for all the elements were relatively satisfactory (87.7–108%). For the soil samples, the recovery values were calculated by proportioning the sum of the steps of the BCR procedure to those of the pseudototal digestion (i.e. aqua regia). In soils, the mobility of heavy metals followed the order Mn>Cd>Cu>Pb>Zn>Cr>Ni>Co>Fe. The relationship between the vegetable–metal and soil–extractable metal concentrations was examined in order to evaluate the bioavailability of metals, and the positive correlation, especially for the first (i.e. water, acid-soluble and exchangeable fraction) and for the third (i.e. oxidizable fraction) extraction steps, was obtained.