Sequential Extraction Of Heavy Metals Research Articles

The effect of an acidic environment during the hydrothermal carbonization of sewage sludge on solid and liquid products: The fate of heavy metals, phosphorus and other compounds

The pH of sewage sludge is a crucial factor during the hydrothermal carbonization process that influences the characteristics of the resulting products and migration of certain compounds from the solid to liquid phase. Accordingly, this work is focused on examining the pH impact during the HTC process, in particular, pH equals 2, 3, 4, 5 and 6 on the individual hydrothermally carbonized products generated at 200 °C and 2 h residence time. For this reason, the chemical and physical indicators describing the post-processing liquid and hydrochar were determined. For instance, it was observed that the phosphorus content detected in the liquid, derived at pH2, rose significantly by 80%. Furthermore, decreasing the pH of sewage sludge had a significant impact on the ash content and the calorific value of the hydrochar. Additionally, changes in the specific surface area of hydrochar were noticed: pH = 5 and pH = 6 showed an increase of 20–30%, while for lower pH values a decrease of c.a. 26% was achieved. The distribution of heavy metals between the obtained fractions in the HTC process (solid and liquid) indicated that 92 to almost 100% of the tested heavy metals were transferred to the hydrochar. A significant effect of pH on the distribution between these fractions was observed only for Zn and Ni. For instance, for pH = 2, Zn and Ni in post-processing liquid were 34% and 29%, respectively. In addition, the sequential extraction of heavy metals from hydrochar was also performed in order to identify mobile and non-mobile phases. It was noticed that the acidic environment favours a higher amount of mobile heavy metals in hydrochar. The largest effect was observed for Cd, Pb, Cr and Cu, for which, at pH = 2, their respective amounts in the mobile fraction were 2.7; 3.6; 1.8; 6.2 times higher, compared to the hydrochar without pH correction.

Geochemical Assessment of the Modern Sediments of a Lake in the North of Russia

Core sediment (sapropel) samples were collected from Lake Okunozero, the Republic of Karelia, Russia, to assess the distribution of heavy metals and their main fractions, probable sources of pollution, and potential ecological and toxicological risks for the water body. Heavy metal concentrations were measured by the mass spectrometry method using an XSeries-2 ICP-MS. The sequential extraction of heavy metals from sapropel samples was performed using the scheme of Tessier. According to the Russian Interstate Standard (GOST), the sapropel of Lake Okunozero is suitable for use in agriculture. The exceedances of the regional background levels were detected only for Pb and Cd. In accordance with Pollution Load Index (PLI) and Potential Ecological Risk (RI), no ecotoxicological risk in researched sediments was found. A significant correlation between some investigated heavy metals was established. Most heavy metals were in the insoluble mineral phase (Mn et al.) or were associated with organic matter (Cu, Zn, Mo, Ni). Only Mn, Zn, Cd, and Pb were found in the available fraction from 13 to 24% of the total metal content in the sediments. Other metals were less associated with the available fraction.

Removal of mixed contaminants from landfill leachate-contaminated soil by flushing with bio-surfactant: laboratory column tests.

Landfill leachate-contaminated soil is widespread all over the world. In order to study the removal of mixed contaminants from landfill leachate-contaminated soil by flushing with bio-surfactant, soil column test was conducted to select an optimum concentration of bio-surfactant saponin (SAP) at first. Then, the removal efficiencies of organic contaminants, ammonia nitrogen, and heavy metals from landfill leachate-contaminated soil by flushing with SAP were studied. At last, the toxicity of contaminated soil before and after flushing was estimated by sequential extraction of heavy metals and plant growth test. The test results showed that the SAP solution with the concentration of 2.5 CMC could effectively remove the mixed contaminants from soil and would not introduce excessive pollutants of SAP in soil. Specifically, the removal efficiencies of organic contaminant and ammonia nitrogen were 47.01% and 90.42%, respectively. And the removal efficiencies of Cu, Zn, and Cd were 29.42%, 22.55%, and 17.68%, respectively. During flushing, hydrophobic organic compounds as well as physisorption and ion-exchange ammonia nitrogen in soil were removed by the solubilization effect of SAP, and heavy metals were removed by the chelation of SAP. After flushing with SAP, the reduced partition index (IR) value of Cu and Cd increased, and the mobility index (MF) value of Cu decreased. In addition, flushing with SAP reduced the plant toxicity of contaminated soil, and the residual SAP in soil promoted the plant growth. Therefore, flushing with SAP offered great potentials in remediating the landfill leachate-contaminated soil.

EFFECT OF ULTRASOUND ON EXTRACTION OF HEAVY METALS FROM SEWAGE SLUDGE IN THE CONTEXT OF A POTENTIAL ECOLOGICAL RISK ASSESSMENT

The aim of the research was to investigate the effect of ultrasound waves on the recovery of heavy metals (HMs) from sewage sludge. For this purpose, we conducted a three-step sequential extraction process proposed by the Community Bureau of Reference (BCR; presently the Standards, Measurements and Testing Programme). In the experiment use was made of certified reference material ERM-CC144 SEWAGE SLUDGE (Joint Research Centre; JRC). The content of heavy metals (Cd, Cr, Cu, Ni, Pb, and Zn) in certified material was determined by atomic absorption spectrometry using the Avio 200 ICP-OES apparatus (PerkinElmer Inc.). To reduce the sequential extraction time, ultrasound treatment was used instead of long hours of shaking. Sonication was conducted in an ultrasonic bath (Sonic-5; Polsonic). The sonication time was set at 20, 40 and 70 minutes. The frequency, power and temperature during the ultrasound treatment were kept constant. The recovery values of heavy metals obtained by the modified sequential extraction method were at similar levels to those achieved by the conventional one. Moreover, it has also been shown that after only 20 minutes of sonication, the recovery values can be obtained similarly as for the conventional method. In order to check whether the ultrasound waves have a significant impact on the distribution of heavy metals in the chemical fractions of sewage sludge, the percentage share for each element was calculated and the potential ecological risk analysis was conducted. This was possible thanks to the fact that the material used for production of ERM-CC144 (JRC) is sewage sludge of domestic origin. The obtained results revealed that ultrasound treatment does not significantly influence the distribution of analysed heavy metals in the chemical fractions of sewage sludge, with one exception, i.e., Zn. The assessment of the ecological risk was performed using Risk Assessment Code (RAC) index, which includes the content of metals in the most mobile fraction, i.e., bound to carbonates. The calculated values of RAC indicated that Zn posed the highest ecological risk. However, it can be also confirmed that the application of ultrasound treatment in the sequential extraction procedure does not have a significant impact on the interpretation of results of the ecological risk assessment. What is more, it confirms the legitimacy of using the discussed modification in the sequential extraction of heavy metals from sewage sludge.

Technosols Development in an Abandoned Mining Area and Environmental Risk Assessment

The study of Technosols development, spatial distribution and physicochemical characteristics is becoming more and more important in the Anthropocene Era. The aim of the present study was to assess soil features and potential heavy metal release risk of soils developed on different mine tailing types after the waste disposal derived from mining activity in Central Italy. Soils were analyzed for their morphological, physical and chemical properties, and a chemical sequential extraction of heavy metals was performed. The investigated soils were classified as Technosols toxic having in some layer within 50 cm of the soil surface inorganic materials with high concentrations of toxic elements. Our findings showed that the bioavailability of potentially toxic element concentrations in the soil changed according to the origin of the mine tailing. However, because of the acidic pH, there is a serious risk of metals leaching which was reduced where the soil organic matter content was higher.

Sequential extraction of heavy metals from sorptive filter media and sediments trapped in stormwater quality improvement devices for road runoff

The performance of stormwater quality improvement devices (SQIDs), commonly based on sedimentation and media filtration, is generally examined either at lab scale or in field tests. However, there has so far been only little investigation into the remobilization of heavy metals retained in sediments and sorptive filter media. It is, moreover, unknown whether current lab-scale experiments are able to replicate the conditions of full-scale operation. To assess the potential impact of differences in conditions between lab-scale and field tests on the strength of association of heavy metals, filter media taken from three SQIDs were subjected to analysis by sequential extraction after prestressing both on a lab scale and in field tests. Sediments and filter cake trapped in the SQIDs were additionally analyzed. These displayed significantly higher heavy metal content than filter media that had been prestressed in the field. The zinc in the sediments and filter media displayed particularly high mobility. This study reveals a discrepancy between field and lab-scale conditions that creates differences in the content and strength of association of heavy metals. It is hence possible to show that previous lab-scale experiments potentially overestimated the risk of heavy-metal leaching, due to their predominant occurrence in more mobile fractions.

Soil geochemistry as a tool for the origin investigation and environmental evaluation of urban parks in Mashhad city, NE of Iran

The total concentration of major oxides and trace elements, sequential extraction of heavy metals, and Pb isotope signatures of park soils were investigated in Mashhad, the largest city in northeastern Iran. The geochemical characteristics of park soils show two different trends: high silica soils (HSS) and low silica soils (LSS). The elements such as Mg, Fe, As, Co, Cr, Cu, Mn, Ni, Pb, Sn, and Zn were concentrated in LSS, while HSS samples were enriched of Si, Ga, Li, Nb, Ta, Th, U, Y, Z, and rare-earth elements (REE). The REE composition and chondrite—normalized patterns of LSS [low ∑REE (20–68 mg kg−1) and low LaN/YbN (1.9–7.4)]—are compatible with ultramafic-derived soils. The HSS samples display distinct REE composition with high ∑REE (102–336 mg kg−1) and LaN/YbN (13–51) which would be originated from granitoid, metamorphic, and sedimentary derived soils. The available percentage of heavy metals in the park soils is much higher than natural samples. The Pb characteristics of park soils are distinct from natural soils. These samples are less radiogenic than natural soils with lower 206Pb/204Pb, 207Pb/204Pb, 208Pb/204Pb, 206Pb/207Pb, and higher 208Pb/206Pb ratios. The calculated contributions of possible sources in Mashhad park soils release 6.6 and 93.4% for natural and anthropogenic (industrial and leaded petrol) sources, respectively. The central parks exhibit the highest pollution of heavy metals in Mashhad indicating high traffic intensity in this area. The concentration of potentially toxic elements in the surface soils of Mashhad parks is lower than the national maximum permissible concentration, but many of them such as Cd, Cu, Mo, Pb, Sn, Se, and Zn are highly enriched relative to non-urban soils.

Ekstrakcja sekwencyjna metali ciężkich w kompozycie mineralno-organicznym

Ekstrakcja sekwencyjna metali ciężkich w kompozycie mineralno-organicznym

Assessment of metal contamination in estuarine surface sediments from Dongying City, China: Use of a modified ecological risk index

Surface sediments and clam Meretrix meretrix were collected from a northern estuarine region in Dongying City, China. Sediments were analysed for heavy metals (Hg, As, Cd, Cr, Cu, Pb, and Zn) and the clams were tested for metallothioneins (MTs) and lysosomal membrane stability (LMS). The heavy metal total concentrations decreased in the order of Cr>Zn>Cu>Pb>As>Cd>Hg. The results of Bureau Communautaire de Référence (BCR) sequential extraction of heavy metals showed that the geochemical speciation of all heavy metals was dominated by residual fraction. According to the responses of biomarkers in M. meretrix, the modified potential ecological risk index (PERI-B) can more accurately reflect heavy metals pollution. PERI-B showed all sediment samples have low or moderate risk, except at site S10 (considerable risk), and the main contribution of ecological risk heavy metals were Cd and Hg.

Examining Total Concentration and Sequential Extraction of Heavy Metals in Agricultural Soil and Wheat

Examining Total Concentration and Sequential Extraction of Heavy Metals in Agricultural Soil and Wheat

Assessment of heavy metal availability (Pb, Cu, Cr, Cd, Zn) and speciation in contaminated soils and sediment of discharge by sequential extraction

The accumulation of the heavy metals in the soil received a particular interest because of their toxicity and retention time in the soil which is slower than in other compartments of the biosphere. Knowledge of the total concentration of metals in soils and sediments is frequently insufficient to ascertain environmental risk. Simple and sequential extractions are useful tools for estimating the mobility of metals. In this study we were interested in highly toxic metals such as cadmium, lead, chromium, copper, and zinc in the soil of a controlled dump and the witness soil as well as the sediment of this dump in order to assess the mobility of these metals and their toxicity. The physicochemical parameters pH, organic matter, total calcium, cation exchange capacity, and total nitrogen were determined on the samples. Results show that average contents of heavy metals exceed the threshold recommended by the AFNOR NF U 44-041 standard. The results of the sequential extraction of heavy metals in the composite samples of soil and sediment according to the Community Bureau of Reference method show that cadmium is mainly associated with the exchangeable fraction (for sediment 77.7 % and for soil 40 %). Cadmium is therefore mainly associated with the mobile fraction and the risk of its transfer is high. Zinc is mainly bound to the metallic oxyhydroxides and carbonates, while Cu and Pb are mostly bound to organic matter and metallic oxyhydroxides in the proportions of 96.12 % (Cu) and 84.38 % (Pb), respectively.

Sequential Extraction of Heavy Metals from Soil Samples Collected from Selected Cocoa Farmland in Erijiyan, Ekiti State, Nigeria

Heavy metal pollution is of great concern due to their potential harmful effects on man and the environment, as soil and sediment are their primary repositories. Anthropogenic activities such as agricultural practices, industrial activities, and waste disposal have contributed to increases in heavy metal concentrations in soil. It is important to determine the effect of agricultural input on the heavy metal concentrations, mobility and bioavailability on cocoa farms by analyzing soil samples collected from selected locations to determine pH, content of organic matter, presence of water-soluble heavy metals and sequential extraction of heavy metals using standard analytical procedures. Results indicate random variation in the pH and organic matter content of soil with average values of 6.49 ± 0.12 and 2.30 ± 0.11%, respectively. The acid digestion of heavy metals was relatively higher than water-soluble heavy metals with the following mean values: Zn (33.70 > 11.30), Fe (111.71 > 4.58), Mn (1.84 > 1.24), Cd (2.16 > 0.95) and Co (1.66 > 1.01). However, sequential extraction revealed that the heavy metals were distributed in all extractive steps, with the non-residual phase dominating and resulting in possible mobility and bioavailability of those heavy metals. Eight soil samples were randomly collected for analysis of source and mobility of heavy metals at a cocoa farm using a calibrated soil auger, and were immediately placed in sealed polythene bags. The samples were collected at depths from 0 - 15 cm, from eight points at 40 m intervals from the first sample location. The samples were air-dried, ground up and sieved with 4 mm mesh. Each sample was immediately placed in a leached polythene bag and tightly sealed. The pH and organic matter content of soil samples were immediately determined using standard analytical procedures as prescribed by AOAC (12).

Environmentally Benign Sequential Extraction of Heavy Metals from Marine Sediments

An environmentally friendly heavy metals remediation process from polluted marine sediments is proposed. The efficiency of three organic and inorganic salts (ammonium acetate, ammonium nitrate, and sodium potassium tartrate) to salt out these pollutants was ascertained in sediment washing waters containing nonionic surfactants. The immiscibility regions were correlated by means of three known models, and the experimental data were interpreted in the light of thermodynamic parameters such as Gibbs free energy of hydration and molar entropy of hydration. The proposed process was applied to model aqueous solutions containing two representative heavy metals (zinc and copper). The viability of the suggested strategy was checked in real contaminated marine sediments by including a sequential treatment: marine sediment washing–contaminant extraction, which led to total remediation values higher than 80% for copper and 90% for zinc.

Sequential extraction of heavy metals in soils from a copper mine: Distribution in geochemical fractions

We evaluated heavy metal contamination (Cr, Cu, Mn, Ni, Pb, and Zn) in soils from the copper mine in Touro, NW Spain. Their total content and geochemical phase distribution were determined using sequential chemical extraction. Representative soils from the area were selected and the objectives were to analyse the total content of heavy metals and their distribution in the different geochemical soil phases, and to determine their association with the soil components using XRD, FE-SEM/EDS and TOF-SIMS. Results show that the Cu total contents (104–2924mgkg−1) exceed the intervention limits. Most of the heavy metal content is in the residual fraction, Cr (82–95%), Cu (30–70%), Mn (60–96%), Ni (77–95%), Pb (47–68%) and Zn (85–97%). Fe-oxides play an important role in the fixation of metals, especially Cu. The amounts associated with soil organic matter and in the exchangeable form are very low (>10%). TOF-SIMS and FE-SEM/EDS techniques confirm the fractionation results, showing that only a very small part of the studied metals are sorbed, mainly in the iron oxides and interacting with several soil mineral components. FE-SEM/EDS combined with TOF-SIMS, sequential extraction assays and statistical analyses are an effective tool to check the affinity of the soil components for heavy metal cations.

Chemical characterisation of biosludge from a wastewater treatment plant in a neutral sulphite semi-chemical pulp mill by single and sequential extraction of heavy metals and micro-/macronutrients — a case study

AbstractThe main impetus for utilising the biosludge from the neutral sulphite semi-chemical pulping process is the Finnish legislation which from 1st January 2016 prohibits the deposition of this residue in landfills in Finland. The dry matter content of the biosludge in this case study was low (12.1 mass %), meaning that incineration of this residue is uneconomical. The biosludge was rich in P (6260 mg kg−1). This, together with the high total organic carbon value of 459 g kg−1 and the metal concentrations (As, Cd, Cr, Cu, Ni, Pb, Zn and Hg) lower than the Finnish permissible limits for land application, supports wide and various end-uses for this residue. Except for S (27600 mg kg−1) and Cd (1.4 mg kg−1), the other heavy metal concentrations in the biosludge were lower than the maximum values for heavy metal concentrations in a non-contaminated soil referred to the literature. From the utilisation perspective, and in view of the high levels of S and Na, this residue could efficiently be used, for example, to landscape landfills.

Utilization of Continuous-Flow System for Sequential Extraction of Heavy Metals in Soil and Sediment Samples

Utilization of Continuous-Flow System for Sequential Extraction of Heavy Metals in Soil and Sediment Samples

Heavy Metal Accumulation in Soil Amended with Roadside Pond Sediment and Uptake by Rice (Oryza sativa L.)

The effect of addition of roadside pond sediments on heavy metal contents of flooded rice paddies was studied to investigate the yield of rice and uptake of heavy metal by rice straw and grain. Sequential extraction of heavy metals on sediments shows that the percentage contribution of metals in the labile fraction follows the order lead (Pb, 48%) > copper (Cu, 42%) > zinc (Zn, 31%) > cadmium (Cd, 16%) > chromium (Cr, 9%) > nickel (Ni, 6%). The risk assessment code (RAC) for pond sediment revealed that Cr and Ni were found in the low-risk zone, Zn and Cd in the medium-risk zone, and Cu and Pb in the high-risk zone. However, though the heavy metal concentration in rice grain does not exceed the range acceptable for human consumption, it still represents a significant additional source of heavy metals in the diet. The addition of pond sediment significantly increased the rice yield over control. Therefore, pond sediment would be a valuable resource for agriculture if it is properly used.

Plant-induced changes in the bioavailability of heavy metals in soil and biosolids assessed by DGT measurements

This study investigated the effects of plants on the available pools of heavy metals and their re-supply potential in contaminated substrates in a short-term experiment using five metal-accumulating willow and poplar species/cultivars and in a longer-term experiment for Salix x reichardtii. Five species of willow and poplar were grown in either soil or biosolids for short-term experiment (4 months). Further investigations of longer-term effects of plant on metal availability were conducted with S. x reichardtii grown in biosolids in a column (100 cm height and 37.5 cm diameter) experiment over a period of 12 months. Samples collected before and after experiments were determined for pH and bioavailability of metals using diffusive gradients in thin films (DGT). Various pools of metals in biosolids were determined by sequential extraction. Concentrations of heavy metals in plant material were determined. The concentration of metals determined by DGT (C DGT) and concentration of metals in pore water (C SOL) of Ni, Cu, Zn, and Cd in soil and biosolids generally decreased significantly compared to the initial measurements and were usually lower than those of the controls. However, C DGT and C SOL were higher in planted soil compared to those in the controls. There was a negative correlation between Ni, Zn, and Cd in plant shoots and C DGT in both soil and biosolids. The R values, the ratio of C DGT/C SOL calculated for Ni, Cd and Zn of planted substrates, were significantly higher than the corresponding R values of initial substrates. By contrast, R values for Cu showed little change. R values for Ni, Zn, and Cd were higher in planted biosolids compared to the unplanted biosolids. While S. x reichardtii leaf Cd, Ni, and Zn concentrations increased significantly over time, leaf Cu concentration declined. The patterns of plant uptake for the metals reflected the patterns observed by DGT and soil solution measurements of R. Sequential extraction of heavy metals from biosolids after 12 month’s experimentation confirmed that Cu was predominantly in the organic fraction. The short-term effects of plants on the bioavailability of metals in soils and biosolids were different. The R values of cultivated treatments varied between species but were not significantly different from the control in most of the cases. The longer-term experiment indicated that both C DGT and C SOL of Ni, Zn, and Cd decreased significantly over time in both planted and unplanted treatments. The results of this study demonstrated that R values measured by DGT may be useful in assessing the potential bioavailability of heavy metals in soil and biosolids.

A green approach for sequential extraction of heavy metals from Li irradiated Au target

An aqueous biphasic extraction system was designed using different molecular weights of polyethylene glycol and concentrated salt solutions of sodium sulphate to separate the heavy metals, Hg, Tl and Pb from Li irradiated Au matrix. All the four elements could be separated from one another by this extraction process by simply optimizing the salt rich phase, the pH of the salt rich phase and the molecular weight of the polymer rich phase.

Time-saving application for sequential extraction of heavy metals by optimized BCR method and lixiviation from untreated sewage sludge

This article describes an improvement in the modified BCR three-step sequential extraction procedure employed for heavy metals (Cd, Cr, Cu, Ni, Pb and Zn) in untreated domestic waste-water sewage sludge collected from different cities in Pakistan.The BCR sequential extraction protocol requires 16 h for each step, whereas in the present work optimum recoveries of all heavy metals were attained in 10 h/step. The validity of the proposed BCR sequential extraction procedure was checked using certified reference material (BCR 483). Various parameters such as time interval (2–16 h) and sample mass (0.2–1.0 g) were studied to achieve optimum recovery of the heavy metals studied. The extracted analytes were determined by atomic absorption spectrometry. The optimum recovery of heavy metals from the certified reference material and from experimental samples was achieved at a sample mass of 0.4 g, while the time required for extraction on a mechanical shaker at 30 rpm was found to be 26–32 h. The sequence of easily available (acid-exchangeable) heavy metals was determined as Cd<Zn<Ni<Cr<Pb<Cu. With the exception of Cd the dominant fractions of the heavy metals were associated with organic matter, while 31.0 and 47.8% of Cd was present in acid-soluble and reducible forms, respectively. A lixiviation test (DIN 38414-S4) was used to evaluate the leaching of heavy metals from the domestic waste-water sewage sludge used for agricultural purposes.