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Mining activities provide a pathway for the entry and accumulation of various heavy metals in soil, which ultimately leads to severe environmental pollution. Utilization of various immobilizing agents could restore such contaminated soils. Therefore, in this study, date palm-derived biochars (BCs: produced at 300 °C, 500 °C and 700 °C) and magnetized biochars (MBCs) were employed to stabilize heavy metals (Cd, Pb, Cu and Zn) in mining polluted soil. Metal polluted soil was amended with BCs and MBCs at w/w ratio of 2% and cultivated with wheat (Triticum aestivum L.) in a greenhouse. After harvesting, dry and fresh biomass of plants were recorded. The soil and plant samples were collected, and the concentrations of heavy metals were measured after extracting with water, DTPA (diethylenetriaminepentaacetic acid), EDTA (ethylenediaminetetraacetic acid), and acetic acid. BCs and MBCs resulted in reduced metal availability and uptake, with higher fresh and dry biomass (>36%). MBCs showed maximum decrease (>70%) in uptake and shoot concentration of metals, as these reductions for Cd and Pb reached below the detection limits. Among all single-step extractions, the DTPA-extractable metals showed a significant positive correlation with shoot concentrations of tested metals. Thus, the synthesized BCs and MBCs could effectively be used for stabilizing heavy metals and improve plant productivity in multi-contaminated soils. However, future studies should focus on long term field trials to restore contaminated mining soils using modified biochars. This study has demonstrated the performance of magnetized biochars for in-situ stabilization of toxic metals (Cd, Pb, Cu and Zn) in mining polluted soil by single extraction method. All the produced BCs and magnetized BCs showed great potential in immobilizing the metals and reducing their availability in soil, consequently decreasing their shoot concentration and plant uptake. Significant negative correlations were observed between soil pH and metal extraction from applied extraction methods such as water soluble, DTPA, and EDTA extractions. We found DTPA as a suitable extractant for investigating metal uptake in plant in multi-contaminated soils. Treatments with MBCs showed maximum decrease in plant uptake and concentration of studied metals. Thus, application of MBCs could efficiently immobilize soil heavy metals. [ABSTRACT FROM AUTHOR]

Microbiologically induced calcite precipitation (MICP), as a newly developing bioremediation technology, could redeem heavy metal contamination in diverse scenarios. In this study, MICP bacterium Sporosarcina ureilytica ML-2 was employed to suppress the pollution of Pb, Cd and Zn in municipal sludge nutrient soil. After MICP remediation, the exchangeable Cd and Zn in sludge nutrient soil were correspondingly reduced by 31.02 % and 6.09 %, while the carbonate-bound Pb, Cd and Zn as well as the residual fractions were increased by 16.12 %, 6.63 %, 13.09 % and 6.10 %, 45.70 %, 3.86 %, respectively. In addition, the extractable Pb, Cd and Zn either by diethylenetriaminepentaacetic acid (DTPA) or toxicity characteristic leaching procedure (TCLP) in sludge nutrient soil were significantly reduced. These results demonstrated that the bio-calcite generated via MICP helped to immobilize heavy metals. Furthermore, MICP treatment improved the abundance of functional microorganisms related to urea cycle, while reduced the overall abundance of metal resistance genes (MRGs) and antibiotic resistance genes (ARGs). This work confirmed the feasibility of MICP in remediation of heavy metal in sludge nutrient soil, which expanded the application field of MICP and provided a promising way for heavy metal pollution management. [Display omitted] • MICP tech could improve the stability of Pb, Cd and Zn in sludge nutrient soil. • The exchangeable Cd reduced by maximum 31.2 % contents after MICP remediated. • The carbonated and residual contents of Pb, Cd and Zn increased after remediated. • The extracted contents of DTPA & TCLP-Pb, Cd and Zn were reduced after remediated. • MICP improved the abundance of functional microbes and reduced resistance genes. [ABSTRACT FROM AUTHOR]

Backgrounds: Due to the unexpected side effects of the iodinated contrast agents, novel contrast agents for X-ray computed tomography (CT) imaging are urgently needed. Nanoparticles made by heavy metal elements are often employed, such as gold and bismuth. These nanoparticles have the advantages of long in vivo circulation time and tumor targeted ability. However, due to the long residence time in vivo, these nanoparticles may bring unexpected toxicity and, the preparation methods of these nanoparticles are complicated and time—consuming. Methods: In this investigation, a small molecular bismuth chelate using diethylenetriaminepentaacetic acid (DPTA) as the chelating agent was proposed to be an ideal CT contrast agent. Results: The preparation method is easy and cost—effective. Moreover, the bismuth agent show better CT imaging for kidney than iohexol in the aspect of improved CT values. Up to 500 µM, the bismuth agent show negligible toxicity to L02 cells and negligible hemolysis. And, the bismuth agent did not induce detectable morphology changes to the main organs of the mice after intravenously repeated administration at a high dose of 250 mg/kg. The pharmacokinetics of the bismuth agent follows the first—order elimination kinetics and, it has a short half—life time of 0.602 h. The rapid clearance from the body promised its excellent biocompatibility. Conclusions: This bismuth agent may serve as a potential candidate for developing novel contrast agent for CT imaging in clinical applications. [ABSTRACT FROM AUTHOR]

Abstract The control of thallium (Tl) pollution in wastewater is much less studied than that of other heavy metals (Cd, Hg, Pb) and metalloids (As), with even less research on the simultaneous treatment of Tl and organics. In this study, the simultaneous removal of thallium and organics from aqueous solutions using a zero-valent-iron (Fe0)-based Fenton-like technique was investigated. Diethylenetriaminepentaacetic acid (DTPA) was selected as the complexing agent with Tl. A response surface methodology (RSM) was employed to evaluate the influencing factors and optimize Tl and organic removal. The results reveal that the coagulation pH and Fe0 dosage are crucial factors for simultaneous Tl and organic removal. Quadratic models were shown to be adequate for the optimization and prediction of treatment performance. Under optimized conditions of Fe0 dosage of 3.8 g/L, [H 2 O 2 ]/Fe0 molar ratio of 1.5, initial pH of 2.9, and coagulation pH of 10.5, Tl and TOC removal reached 99% and 80%, respectively. Fourier transform infrared (FT-IR) and X-ray photoelectron spectroscopy (XPS) analyses indicate that oxidation, precipitation, and adsorption contribute to Tl removal. The DTPA was degraded into small molecules that can be strongly adsorbed by the iron hydroxides under alkaline conditions. Five consecutive cyclic tests reusing Fe0 as a catalyst maintained stable and efficient treatment performance. This Fe0-H 2 O 2 Fenton-like technique is a promising approach for the simultaneous removal of Tl and organics from wastewater. Highlights • The Fe0-H 2 O 2 Fenton-like technique is effective for simultaneous removal of Tl and DTPA. • The coagulation pH is the most important factor for maximum Tl and DTPA removal. • Oxidation, precipitation and adsorption are the main mechanisms for Tl removal. • DTPA is degraded to small intermediates that can be adsorbed onto the iron hydroxide colloids. • Fe0 can be continuously reused for constant Fenton-like reaction. [ABSTRACT FROM AUTHOR]

Abstract: To assess the impact of Ni toxicity in soils after long‐term field aging, a coarse‐textured soil was spiked with Ni salt at 100, 200, and 400 mg kg−1 Ni concentrations. These soils were aged in the field along with an unspiked (control) soil under natural conditions for 12 yr, after which total soil Ni was measured and tests of Ni extractability by 0.01 M CaCl2 and diethylenetriaminepentaacetic acid (DTPA) were done. Soybean assays and soil respiration tests were performed to determine residual Ni toxicity of the aged contaminated soils. The greatest loss of Ni after 12 yr of aging occurred from the soil spiked with the highest Ni level, but substantial loss of Ni occurred from the lower Ni levels as well. Loss was attributable to leaching as the fraction of readily extractable (by 0.01 M CaCl2) Ni diminished with long‐term aging. Readily extractable and DTPA‐extractable Ni increased with increasing soil spiking levels, but only the latter was linearly proportional to total Ni. Phytotoxicity to soybeans (Glycine max L.) in the field was initially high at all levels of added Ni but diminished over the 12 yr of aging. A greenhouse soybean assay with the 12‐yr aged soils confirmed toxicity to be statistically significant at all Ni addition levels and dose‐dependent, with 0.01 M CaCl2‐extractable Ni >5 mg kg−1 shown to be measurably phytotoxic to soybeans. Phytotoxicity may have been caused at least in part by the observed inhibition of Mn, Fe, Cu, and Zn uptake by soil Ni. Soil respiration was increasingly inhibited as levels of added Ni increased from 100 to 400 mg kg−1. Environ Toxicol Chem 2018;37:1933–1939. © 2018 SETAC [ABSTRACT FROM AUTHOR]

In the present study, a laboratory experiment was designed to compare the 0.01 M calcium chloride (CaCl2) and diethylenetriaminepentaacetic acid (DTPA) extraction methods for their ability to predict cadmium (Cd), copper (Cu), iron (Fe), Manganese (Mn), nickel (Ni), and zinc (Zn) availability and mobility in five calcareous soils. The soils were spiked with different amounts of metals (0, 50, 100, 200, and 400 mg kg−1) both in binary (Cu and Zn; Ni and Cd; Fe and Mn) and in multi-systems (Cd, Cu, Fe, Mn, Ni, and Zn) and incubated for 1 months at field capacity. In metal-spiked soils, both extraction methods showed a linear relationship of extractable to total metals for all soils. The fraction of total metals extracted by DTPA was much higher than the fraction extracted by CaCl2, which was attributed to the formation of soluble metal-complexes in the complexing extracts calculated by the Visual Minteq program. DTPA extraction method showed higher selectivity for Cu over other metals both in binary and in multi-systems. Different order of metals extractability was found in binary and multi-systems for both extraction methods. Solid/solution distribution coefficient (Kd) was calculated by the ratio of the solid phase to soil solution concentration of metals extracted by CaCl2or DTPA extraction methods. Both in binary and in multi-systems, the average Kd(l kg−1) of metals by soils were in the order of Mn (5398) > Fe (4413) > Zn (3376) > Cu (2520) > Ni (969) > Cd (350) in the CaCl2-extractable metals and Fe (35) ≥ Ni (34) > Zn (18) > Mn (11.2) > Cu (6.3) > Cd (4) in the DTPA-extractable metals. Results showed that among the six studied metals, Cd had the lowest Kd, implying a relative higher mobility in these calcareous soils. The Visual Minteq indicated that in the CaCl2-extraction method and in both binary and multi-systems the dominant species for Cu, Mn, Ni, and Zn were Cu2+, Mn2+, Ni2+and Zn2+, respectively, while for Cd and Fe, the dominant species were CdCl+and Fe(OH)2+, respectively. [ABSTRACT FROM PUBLISHER]

In present study, geostatistical techniques were applied to assess the spatial variability of DTPA-extractable micronutrients which are named heavy metals as chemistry such as; iron (Fe), copper (Cu), manganese (Mn) and zinc (Zn) in the non-tillaged layer in Ordu province-Altınordu district, Black sea region, Eastern part of Turkey. Study area was approximately 40095.8 ha where was divided into grids with 2500 × 2500 m spacing with including 66 sampling points from 0-0.2 m in depth. Soil reaction (pH) was the least variable property while electrical conductivity (EC) was the most variable. While the highest nugget effect occurred for Ext-Cu with moderate spatial dependence, the lowest for Ext-Mn with strong spatial dependence. The greatest range of influence (17424 m) occurred for Ext-Cu and the least range (692 m) for Ext-Zn. [ABSTRACT FROM AUTHOR]

An incubation experiment was conducted to evaluate the effects that three types of biomass ash, each applied at two doses, exert on the nutrient availability in a calcareous soil. The application of the ash from dry olive cake or greenhouse vegetable wastes significantly increased soil ammonium bicarbonate-diethylenetriaminepentaacetic acid (AB-DTPA)-extractable phosphorus (P), potassium (K), sodium (Na), copper (Cu) and zinc (Zn) as well as exchangeable and non-exchangeable K and Na. Wood ash was effective only for increasing soil ABDTPA-extractable Zn and Cu. By contrast, the three types of biomass ash hardly increased soil ABDTPA-extractable Fe or Mn. The high content in carbonate of the soil appears to minimize the potential of the ash to increase the micronutrients availability, which shortened with longer incubation time. Soil ABDTPA-extractable heavy metals were not detected in the different treatments tested. Other parameters of the soil, as pH and organic carbon, were scarcely affected by the ash, while conductivity and dehydrogenase activity increased. [ABSTRACT FROM AUTHOR]

The study was conducted to elucidate the effect of three levels of compost amended soils (0, 3, and 6%, w/w) on Cd, Cu, and Zn extractability and uptake by radish plant (Raphanus sativus) grown in calcareous and sandy soils contaminated with 0, 40, 80 or 160 mg metal kg-1 soil. DTPA extraction and greenhouse experiments were designed. The study revealed that the addition of compost treatments improved the plant biomass in both uncontaminated/contaminated two soils since the dry weight of shoots and roots for the two compost treatments was higher than that of the control (0 compost addition) even in high contamination level. Also, For Cu and Zn, the plants cultivated in metals levels (40-160 mg kg-1) showed a significant increase in the dry weight in both radish shoots and roots grown in the both soils; whereas increase Cd levels from 40 to 160 mg kg-1 decreased the dry weight of both radish shoots and roots. DTPA extractable Cd and Cu in addition to their concentrations in radish shoots/roots grown in the soils were decreased as a result of compost amendments with more pronounced at high compost level; whereas the opposite results were obtained for Zn. Good correlations were obtained in most cases between DTPA extractable metals and absorbed by radish plant indicated by correlation coefficients. These findings highlight the applicable of compost to ameliorate Cd and Cu risks in high contaminated soils. [ABSTRACT FROM AUTHOR]

The coastal plain of Cixi City, China, has experienced over 1000 years of reclamation. With the rapid development of agriculture and industry after reclamation, successive inputs into agricultural soils have drastically modified the soil environment. To determine the spatial distribution of heavy metals and to evaluate the influence of anthropogenic activities, a total of 329 top soil samples were taken along a transect on the coastal plain. The samples collected across 11 sea dikes, were selected by a nested sampling methodology. Total Cu, Fe, Mn, Ni, Pb, and Zn concentrations, as well as their diethylenetriamine penta-acetic acid (DTPA) extractable (available) concentrations were determined. Results indicated that except for Zn concentrations, there was neither heavy metals pollution nor mineral deficiency in the soils. Heavy metals exhibited considerable spatial variability, obvious spatial dependence, and close relationships on the reclaimed land. For most metals, the reclamation history was the main influencing factor. Metals concentrations generally showed discontinuities around the position of sea dikes, and the longer reclamation histories tended to have higher metals concentrations than the recently reclaimed sectors. As for Cu and Zn total concentrations, stochastic factors, like industrial waste discharge, fertilization and pesticide application, probably led to the high nugget effect and altered this relationship. The 6th and 10th zones generally had the highest total metals concentrations, due to the concentration of household appliance manufacturers in these reclaimed areas. The first two zones were characterized by high available metals concentrations, probably due to the alternant flooding and emergence, low pH values and high organic matter contents in these paddy field soils. From the 3rd to 7th zones with the same land use history and soil type, metals concentrations, especially available concentrations, showed homogeneity. The nested sampling method adopted demonstrated that the 500-m interval was enough to capture the spatial variation of the metals. These results were useful in evaluating the variation in the environment quality of the soils under long-term reclamation and to formulate plans for future reclamation projects. [ABSTRACT FROM AUTHOR]

The knowledge on the relationships of protein and micronutrient concentration in wheat grain with edaphic characteristics could provide valuable information for site-specific fertilization of crops for producing grains denser in micronutrients such as iron (Fe) and zinc (Zn) in rain-fed agriculture. In this study, we used soil properties and topographic parameters in the artificial neural network (ANN) methodology as a power tool for improving models for predicting wheat grain micronutrient and protein contents in the hilly regions of western Iran. Soil and grain samples were collected from 1 m2plots using the stratified random method, whereas the slope positions were considered as the basis of soil sampling, at 100 selected points. The mean grain Zn, Fe, Cu (copper) and Mn (manganese) concentrations were 37.02, 65.86, 14.79 and 44.93 mg–1kg–1, respectively, and mean grain protein was 13.76%. Application of the ANN models for predicting Zn, Fe, Cu, Mn and protein contents in grains improved prediction by 96.77%, 95.45%, 124.13%, 125% and 109.75%, respectively, over the multiple linear regression (MLR) models.The topographic parameters wetness index, plan curvature and shaded relief, selected soil properties total nitrogen (TN), soil organic matter, available phosphorus and DTPA-extractable micronutrients were identified as the most important parameters for explaining the variability in wheat grain quality at the study area. [ABSTRACT FROM AUTHOR]

Conspicuous vegetation entities of pedogenic soils rich in cadmium and their diethylene triamine pentaacetic acid (DTPA)-extractable Cd content (DCd) under the temperate continental and Mediterranean climatic conditions of western Anatolia were determined. Foliage of herbaceous plants and nearby soil samples was collected from 51 zinc mining areas. DCd content was found to reach 11.6%-16.2% of the total Cd content, indicating more extractability than in many other heavy metals. Growth chamber and nursery experiments were conducted with the seeds collected. Dactylis glomerata and Galium tenuissimum subsp. tenuissimum, both common in grazing lands, were found to be accumulating 23.5 mg Cd kg-1 and 22.3 mg Cd kg-1 dry matter, respectively, which are highly phytotoxic levels. Thlaspi praecox, known as a Cd-hyperaccumulating plant species, could not be successfully introduced into the Cd-rich mining soils under controlled conditions, suggesting genetic variation or inability to adapt. Volunteer species under controlled conditions included Poa bulbosa and Plantago lanceolata, both of which were potential Cd-hyperaccumulating candidates. Silene aegyptiaca and Silene vulgaris were other species commonly found around zinc mines and they were grown under controlled conditions without difficulty. However, Cd concentrations in the above-ground tissues of all species mentioned above were not over the 100 mg kg-1 dry matter threshold value for hyperaccumulating cadmium. [ABSTRACT FROM AUTHOR]

High concentrations of heavy metals and organic pollutants in municipal sewage sludge are key factors limiting its use in agriculture. The objectives of this study were to decrease the heavy metal and polycyclic aromatic hydrocarbon concentrations in sewage sludge by phytotreatment and to determine, in a field experiment, whether co-planting is more effective than using a mono-crop ofSedum alfredii. Four treatments were used in the plot experiment: no sludge, no plants,S. alfrediiand co-plantingS. alfrediiandAlocasia marorrhiza. The results showed that co-planting produced tubers and shoots ofA. marorrhizathat were suitable as a safe animal feed and good organic K fertilizer, respectively. Co-planting was more effective than mono-planting at reducing concentrations of total Zn and diethylenetriaminepentaacetic acid (DTPA)-extractable Zn, Cd, and Cu in the sludge. Co-planting decreased the concentrations of DTPA-extractable heavy metals and benzo[a]pyrene (B[a]P) in the sludge significantly compared with the unplanted sludge. Decreases of 87, 75, 85, 31, and 64% were obtained for B[a]P and DTPA-extractable Zn, Cd, Cu, and Pb, respectively, compared with the fresh sludge. These results indicate that co-planting can reduce significantly the environmental risks associated with heavy metals and B[a]P in sewage sludge for further disposal. [ABSTRACT FROM AUTHOR]

Understanding soil responses to the application of urban or industrial residues is necessary. In the current experiment, both sources of residues were applied to the soil surface of a Hapludox soil for 8 years. The four residues studied were biodigested and centrifuged sewage sludge (LB and LC, respectively), steel slag from the metallurgic industry (E), and limed mud from the pulp and cellulose industry (LCal). The residues were applied at 0, 2, 4, and 8 Mg ha−1four times from 2002 to 2010 when soybean was cultivated in the summer and lopsided oat and sorghum were cultivated during the winter. The contents of heavy metals were evaluated with diethylenetriaminepentaacetic acid (DTPA) and organic acids. The LB was the residue that increased the contents of soil micronutrients and heavy metals to their greatest levels, although within limits that impair the risks of environmental contamination. [ABSTRACT FROM AUTHOR]

In this study, the different fractions of Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn in the soil samples have been determined by means of BCR sequential extraction method which was developed by the European Bureau of Reference. The amounts of heavy metals which are taken by plants have been determined through DTPA (diethylene triamine pentaacetic acid) extraction method and the relationship between sequential extraction method and amounts of heavy metal taken by plants have been statistically analyzed. Flame atomic absorption spectrometry (FAAS) has been employed to find out heavy metals extracted through BCR sequential extraction and DTPA method. In this study, it has been statistically found out that there is a strong relationship between heavy metals (Cd, Cr, Cu, Fe, Mn, Pb and Zn) except for Ni and Co which can be extracted through DTPA and F1 fraction (exchangeable and carbonateObound). It has also been seen that this relationship can provide significant information while interpreting heavy metal behaviors and available amounts. Besides, it has been observed that there is a statistical relationship between metal amount bound in F2 (FeOMn oxides bound) and F3 (organic matter and sulphure bound) fractions and metal amounts extractable through DTPA. It has also been seen that these relationships can provide information for heavy metals about their bioavailability in the long term. [ABSTRACT FROM AUTHOR]

In-situ rehabilitation of fly ash at dumping sites has rarely been addressed for crop production due to growth-related constraints, largely of heavy metal (HM) contamination in soils and crops. Current communication deals with a novel approach to identify a suitable management option for rejuvenating the contaminated soils. In this background, a 60-days incubation experiment was conducted with different fly ash-soil mixtures (50 + 50%, A1; 75 + 25%, A2; 100 + 0%, A3) along with four ameliorants, namely, lime (T1), sodium sulphide (T2), di-ammonium phosphate (T3), and humic acid (T4) at 30 ± 2 °C to assess the ability of different fly ash-soil-ameliorant mixtures in reducing bio-availability of HMs. Diethylenetriaminepentaacetic acid (DTPA)-extractable bio-available HM contents for lead (Pb), cadmium (Cd), nickel (Ni), and chromium (Cr) and their respective ratios to total HM contents under the influence of different treatments were estimated at 0, 15, 30, 45, and 60 days of incubation. Further, the eco-toxicological impact of different treatments on soil microbial properties was studied after 60 days of experimentation. A1T1 significantly recorded the lowest bio-availability of HMs (~49–233% lower) followed by A2T1 (~35–133%) among the treatments. The principal component analysis also confirmed the superiority of A1T1 and A2T1 in this regard. Further, A1T1 achieved low contamination factor and ecological risk with substantial microbial biomass carbon load and dehydrogenase activity. Thus, liming to fly ash-soil mixture at 50:50 may be considered as the best management option for ameliorating metal toxicity. This technology may guide thermal power plants to provide the necessary package of practices for the stakeholders to revive their contaminated lands for better environmental sustainability. [ABSTRACT FROM AUTHOR]

Bioenergy production combined with phytoremediation has been suggested to help in solving two critical world problems: the gradual reduction of fossil fuels and soil contamination. The aim of this research was to investigate the potential for the use of Ricinus communis L. (castor oil plant) as an energy crop and plant species to remediate metal-polluted sites. This study was performed in mine tailings containing high concentrations of Cu, Zn, Mn, Pb and Cd. Physico-chemical characterization, total, DTPA-extractable and water-soluble metals in rhizospheric tailings heap samples were carried. Metal concentrations in plant tissues and translocation factors (TFs) were also determined. The Ricinus seed-oil content was high between 41 and 64%, seeds from San Francisco site 6 had the highest oil content, while these from site 7 had the lowest. No trend between oil yield vs seed origin site was observed. Seed-oil content was negatively correlated with root concentration of Cu, Zn, Pb and Cd, but no correlation was observed with the extractable-metals. According to its shoot metal concentrations and TFs, castor bean is not a metal accumulator plant. This primary colonizing plant is well suited to cope with the local toxic conditions and can be useful for the stabilization of these residues, and for then decreasing metal bioavailability, dispersion and human health risks on these barren tailings heaps and in the surrounding area. Our work is the first report regarding combined oil production and a phytostabilization role for Ricinus plants in metal mine tailings and may give a new value to suitable metal-polluted areas. [Copyright &y& Elsevier]

Abstract: Ten batches (75kg each) of garden soil with >50% of silt and clay and average 1935mgkg−1 Pb, 800mgkg−1 Zn, 10mgkg−1 Cd and 120mgkg−1 As were remediated in a pilot-scale chemical extraction plant. Washing with 60mmol ethylenediaminetetraacetic acid (EDTA) per kg of soil on average removed 79, 38, 70, and 80% of Pb, Zn, Cd and As, respectively, and significantly reduced the leachability, phyto-accessibility and oral-availability of residual toxic metals, as assessed using deionised water, toxicity characteristic leaching procedure (TCLP), diethylenetriamine pentaacetic acid extraction (DTPA) and physiologically based extraction test (PBET) tests. The used soil washing solution was treated before discharge using an electrochemical advanced oxidation process with graphite anode: EDTA was removed by degradation and toxic metals were electro-precipitated onto a stainless steel cathode. The novelty of the remediation technique is separation of the soil from the washing solution and soil rinsing (removal of mobilized contaminants) carried out in the same process step. Another novelty is the reuse of the soil rinsing solution from the previous batch for cleansing the soil sand, soil rinsing and for preparation of the washing solution in subsequent batches. The cost of energy and material expenses and disposal of waste products amounted to approximately 75€ton−1 of soil. [Copyright &y& Elsevier]

This greenhouse study evaluated the use of drinking-water-treatment residuals (WTRs) to reduce the bioavailability of metals in the biosolid-amended agricultural alkaline soils. Results showed that increasing the application rate of biosolids increased the accumulation of lead (Pb), nickel (Ni), copper (Cu), and cadmium (Cd) in corn (Zea mays cv. single hybride 10), with greater metal concentrations in roots than in shoots. However, the addition of WTRs (1–4%, w/w) to the soil amended with 3% biosolids significantly (P < 0.05) decreased the concentrations of soil diethylenetriaminepentaacetic acid (DTPA)–extractable metals. The accumulation of Pb, Ni, Cu, and Cd in corn significantly correlated with the DTPA-extractable metal concentrations in the soils. Plant metal concentrations were significantly affected by the soil type, application rates of biosolids and WTRs, and the ratio of WTRs to biosolids in the soils. The 1:1 application ratio of WTRs to biosolids at the 3% application rate effectively reduced the accumulation of metals in corn tissues. [ABSTRACT FROM AUTHOR]

Given the relationship between the contents of heavy metals extracted from contaminated soil samples and dilution of these samples in diethylenetriaminepentacetic acid (DTPA) solution, the goal of this work was to test three soil–extractant solution ratios, namely 1:5, 1:10, and 1:15. The extracted contents from each solution were compared to those extracted by bean plants (Phaseolus vulgaris) cultivated in a greenhouse in two different soils: dystrophic red latosol (RLd) and humic red-yellow latosol (RYLh). Contents of cadmium (Cd) and lead (Pb) were greater in RYLh (lower amount of clay) for all soil–extractant ratios; 1:5 and 1:10 ratios differed negligibly from the plant result for the Cd extraction, while for Pb, the 1:15 soil–extractant ratio was the one that better correlated with the extractive behavior of sensitive indicator plants. [ABSTRACT FROM PUBLISHER]

Abstract: Melamine-diethylenetriamine pentaacetic acid (MA-DTPA) chelating resin was synthesized via the amide bond reaction between DTPA carboxyl groups and melamine amine groups. The adsorption performance of MA-DTPA resin towards Ni(II) and Cu(II) was investigated. FTIR and NMR measurements were carried out for characterization of the pristine resin and metal loaded resin. Chelating mechanism of MA-DTPA towards Ni(II) and Cu(II) has been studied using density functional theory together with a continuum solvation model. The geometrical parameters, energetic characteristic and charge population were also discussed, and then the complexation energies and complexation Gibbs free energies were calculated. The results indicate that the resin shows high affinity for heavy metal cations, and its adsorption performance of Cu(II) is better than that of Ni(II). FTIR and NMR spectra evidence the formation of amide groups and suggest that the carboxylic oxygen atoms may dominate in the coordination reaction. DFT calculations confirm that the coordination between carboxylic oxygen atom and metal cations is more favorable than that of amide nitrogen. MA-DTPA resin exhibits stronger binding capability for Cu(II) as compared to Ni(II). [ABSTRACT FROM AUTHOR]

A glasshouse study was undertaken to evaluate the effect of lime-treated (0, 0.5, and 1%) industrial sludge amendments (10 and 20%) on wheat (Triticum aestivum L.) seedling growth and heavy metal accumulation in soils as well as in wheat seedlings. Industrial sludge-amended soil samples were filled in earthen pots (2 kg pot-1) one week before planting and 7-day-old seedlings were transplanted in pots (3/pot) and were kept in a glasshouse. Diethylenetriamine pentaacetic acid (DTPA)-extractable metals and metals in seedlings increase with increasing doses of industrial sludge. Biomass and growth have been found to increase with increasing rates of sludge. It also enhanced heavy metal concentrations in wheat seedlings and followed the trend zinc (Zn) > lead (Pb) > copper (Cu) > cadmium (Cd). Lime enhanced the biomass and reduced the heavy metal concentrations in wheat seedlings. Although 20% treatments in both soils showed a significant enhancement in shoot length, metals like Pb reached beyond permissible limits. [ABSTRACT FROM AUTHOR]

Human exposure to toxic heavy metals via dietary intake is of increasing concern. Heavy-metal pollution of a rice production system can pose a threat to human health. Thus, it was necessary to develop a suitable extraction procedure that would represent the content of metal available to rice plants (Oryza sativa L.). The aim of this study was to predict, on the basis of single extraction procedures of soil heavy metals, the accumulation of heavy metals (cadium, lead, copper, and zinc) in rice plants. Six extracting agents [Mehlich 1, Mehlich 3, EDTA (ethylenediaminetetraacetic acid), DTPA-TEA (diethylenetriaminepentaacetic acid-triethanolamine), ammonium acetate (NH4OAc), and calcium chloride (CaCl2)] were tested to evaluate the bioavailability of heavy metals from paddy soils contaminated with lead-zinc mine tailings to rice. The extraction capacity of the metals was found to be of the order EDTA > Mehlich 3 > Mehlich 1 > DTPA-TEA > NH4OAc > CaCl2. The correlation analysis between metals extracted with different extractants and concentrations of the metals in the grain and stalk of the plant showed positive correlations with all metals. The greatest values of correlation coefficients were determined between the NH4OAc- and CaCl2-soluble fractions of soil and contents in plants in all four metals studied. Therefore, NH4OAc and CaCl2 were the most suitable extractants for predicting bioavailability of heavy metals in the polluted soils to rice. The results suggested that uptake of heavy metals by rice was mostly from exchangeable and water-soluble fractions of the metals in the soils. Soil-extractable metals were more significantly correlated with metal accumulation in the stalk than in the grain. The pH had more significant influence on availability of heavy metals in the soils than total content of metals and other soil properties. The bioavailability of metals for rice plants would be high in acidic soils. [ABSTRACT FROM AUTHOR]

Available micronutrient status of zinc, copper, manganese, and iron (Zn, Cu, Mn, and Fe) in surface soil samples under a rice-wheat system collected from farmers' fields in 40 districts representing different agroclimatic zones of the Indo-Gangetic Plain (IGP) were determined. The selection of farmers, villages, blocks, and districts within an agroclimatic zone was made on the basis of a multistage statistical approach. In Trans-Gangetic Plains, the diethylenetriaminepentaacetic acid (DTPA)-extractable Zn ranged from 0.11 to 5.08, Cu ranged from 0.22 to 4.72, Mn ranged from 2.9 to 101.2, and Fe ranged from 1.05 to 97.9 mg kg-1. In the Upper Gangetic Plains, the DTPA-extractable Zn ranged from 0.04 to 2.53, Cu ranged from 0.06 to 4.32, Mn ranged from 11.1 to 421.0, and Fe ranged from 3.48 to 90.2 mg kg-1. In the Middle Gangetic Plains, the DTPA-extractable Zn ranged from 0.17 to 8.60, Cu ranged from 0.09 to 7.80, Mn ranged from 3.0 to 155.1, and Fe ranged from 9.22 to 256.7 mg kg-1. In the Lower Gangetic Plains, the DTPA-extractable Zn ranged from 0.04 to 3.46, Cu ranged from 0.21 to 4.38, Mn ranged from 9.54 to 252.2, and Fe ranged from 3.60 to 182.5 mg kg-1. The intensively cultivated Trans-Gangetic transect representing the midplain and Siwalik had more available micronutrients than the arid plain. Midplain and arid plain showed 17 to 20% of soil samples were low to medium in Zn and 5 and 8% were low in Fe. In the Upper Gangetic Plains, only 25% samples were deficient in Zn, especially in central and southwest plains. In the Middle Gangetic Plains, 20 to 30% of samples were deficient in Zn, and very few samples were deficient in other micronutrients. In the Lower Gangetic Plains, a majority of the samples were medium to high in micronutrients except in Barind and Rarh Plains where 30% of samples were deficient in Zn. In the Lower Gangetic Plains, the available micronutrients were plentiful. Available micronutrients increased with increase in organic C content and decreased with increase in sand content, pH, and calcium carbonate. These soils are alluvial in nature, and there was no definite pattern of micronutrient distribution with depth in the profile. However, there was more accumulation in the Ap horizon than in the B horizon. [ABSTRACT FROM AUTHOR]

Abstract: Traditionally, three threshold levels have been accepted for heavy metal concentrations in agricultural soils, depending on soil pH. The aim of this work was to ascertain how the three threshold values proposed for Cd (3, 6.5, and 12.5 mg kg−1) and Zn (300, 650, and 1300 mg kg−1) really affect soil microbial activity. Two soils, a scrubland soil and a forest soil, differing widely in their organic C content, were used in this study. Despite the different soil characteristics, the fractions of Cd and Zn extracted with a solution of diethylenetriaminepentaacetic acid (DTPA) showed little difference between soils. Parameters, such as microbial biomass C (Cmic), soil basal respiration (BR), adenosine triphosphate (ATP) content, dehydrogenase activity (DHA), urease activity (UA), alkaline phosphatase activity (APA), and β-glucosidase (β-GA), were less affected by heavy metals in the forest soil than in the scrubland soil. In general, the simultaneous addition of both metals had a synergistic effect on microbial activity, and this treatment produced a significant decrease of microbial activity of both soils with respect to control. The highest level (L3) of Cd, Zn and Cd + Zn treatments produced significant decrease of microbial and biochemical parameters in both soils. [Copyright &y& Elsevier]

Efforts have been made in this study to stabilize the sewage sludge mixed with sugarcane trash in four different proportions: 20% (T1); 40% (T2); 60% (T3) and 80% (T4), under laboratory conditions using epigeic earthworm (Oligochaeta) Eisenia fetida. The composting potential of worm was also evaluated in 100% sewage sludge treatment (T5). The changes in chemical properties of substrate was measured at the end. The vermicomposted material showed decrease in organic C (4.8–12.7%) and exchangeable K (3.2–15.3%) content, whereas increase in total N (5.9–25.1%) and available P (1.2–10.9%), exchangeable Ca (2.3–10.9%) and exchangeable Mg (4.5–14.0%) contents. Vermicomposting process caused considerable reduction in concentration of diethylene-triaminepentaacetic acid (DTPA) extractable metals: Cu (4.98–30.5%), Fe (5.08–12.64%), Mn (3.31–18.0%), Zn (2.52–15.90%) and Pb (2.38–20.0%). E. fetida showed the better growth performances in first three treatments (T1–T3) possibly due to higher content of organic matter (supplied by bulking agent, i.e. sugarcane trash). The earthworm mortality was higher in vermibeds those contained more sludge proportions. Study revealed that vermicomposting might be an efficient technology to convert negligible municipal sewage sludge into value-added products. The feasibility of earthworms to mitigate the metal toxicity and to enhance the nutrient profile might be useful to convert noxious sludge into useful products, at low-input basis. [Copyright &y& Elsevier]

Tobacco (Nicotiana tabacum) is one of the most important agricultural products in Greece. The accumulation of heavy metals in tobacco leaves in accordance with a possible risk of transferring them to people by smoke is well known. To monitoring heavy-metal contents in soils, as well as in tobacco leaves, a 6-year survey was conducted in the Thessaly region (central Greece). The concentration of zinc (Zn), copper (Cu), nickel (Ni), cadmium (Cd), iron (Fe), and manganese (Mn) was measured both in soils and in air-cured (Burley), flue-cured (Virginia), and sun-cured (Oriental-filling) tobacco leaves in lower and upper leaves (primings). Regression analysis was conducted between soil and tobacco heavy-metal content to examine the possibility of predicting tobacco heavy-metal levels based on the results of soil analysis [diethylenetriaminepentaacetic acid (DTPA)-extractable levels]. The results showed a high correlation between Oriental tobacco heavy-metal content and DTPA-extracted heavy-metal level in soils. Although regressions based on the pooled data from the three tobacco types adequately predicted tobacco heavy-metal levels, better fits were obtained when regression models were used for Oriental tobacco separately. Statistically significant negative correlations were recorded between heavy-metal concentrations in Oriental tobacco leaves and soil pH, in all primings. Therefore, low soil pH value leads to an increased availability of heavy metals in tobacco leaves. [ABSTRACT FROM AUTHOR]

In southern China revegetation and ecological restoration of many abandoned Mn tailings has become a major concern. To determine the major constraints for plant establishment and evaluate the feasibility of remediation, a comparative study was conducted on Mn tailings and rhizosphere soils at the boundary of the tailings pond. Both tailings and rhizosphere soils had neutral to slightly alkaline pH and normal electrical conductivity. They were both enriched with organic matter (6.8–9.2%), total N (1.77–5.94gkg−1), available P (41.78–73.83mgkg−1) and K (146.7–906.9mgkg−1), suggesting the tailings were a nutrient rich substrate for revegetation. Mn tailings were clay textured, while rhizosphere soils were silty loam or clay loam. The compaction and anoxic nature of Mn tailings were considered to be the major constraints for plant establishment. Total Mn (31903mgkg−1), Cd (119mgkg−1), Cu (126mgkg−1) and Zn (2490mgkg−1) in tailings were all at phytotoxic levels, but did not differ significantly from those in rhizosphere soils. In both tailings and rhizosphere soils, percentages of water- and DTPA-extractable metals were less than 1% and 2% of the total metal pools, respectively. Sequential extraction revealed that the majority of Mn, Cu and Zn were associated with the residual fraction, while the majority of Cd occurred as Fe–Mn oxides. The natural succession of plants around Mn tailings formed a distinctive metal-tolerant plant community, mainly comprising nine species such as Cynodon dactylon and Humulus scandens and so on. All species studied could be good candidates for revegetation of Mn tailings. [Copyright &y& Elsevier]

Abstract: In this field experiment, sewage sludge was applied at 0, 5, 10, and 50tha−1, and the availability of Cd, Ni, Pb, and Zn was assessed both by ryegrass uptake and by DTPA extractions. The aim was to investigate the role of important soil parameters, particularly pH, on heavy metal availability. It was found that metal uptake and extractability increased significantly in the 50tha−1 treatment. In the 16th week of the experiment there was a significant, although temporary, increase in DTPA-extractable Cd, Ni, and Zn concentrations. Metal concentrations in ryegrass were also significantly elevated in week 20 compared to the subsequent cuttings. These fluctuations in both DTPA and ryegrass uptake occurred only at 50tha−1 and were probably induced by a sudden pH decrease measured in the same treatment in week 16. This suggests that soils which have received high applications of sewage sludge may be prone to fluctuations in metal availability. [Copyright &y& Elsevier]

This study compares the effect of synthetic aminopolycarboxylic acids ethylenediamine tetraacetate (EDTA) and diethylenetriamine pentaacetate (DTPA) with natural low-molecular-weight organic acids (LMWOAs) oxalic acid and citric acid as chelators for enhancing phytoextraction of Cr and Ni by Brassica juncea on serpentine-mine tailings. Chelator treatments were applied at doses of 0.05 and 0.10mmolkg−1 dry soils after seedlings were grown in pots for 56 days. Experimental results indicate that EDTA and DTPA were the most efficient chelators of increasing the levels of Cr and Ni in the soil solutions over time. Additionally, the reduction of plant shoot biomass caused by the two synthetic chelators exceeds that caused by the LMWOAs. The total uptake (mass removal from soil) of metals by plants was enhanced via the chelators. Experimental results supported the use of B. juncea for Cr and Ni phytoremediation: B. juncea improved the removal of Cr and Ni from serpentine-mine tailings. However, low plant biomass did not assist phytoextraction by using EDTA and DTPA, both of which carry environmental risk. Therefore, adding LMWOAs during phytoremediation can provide an environmentally compatible alternative, which may decrease the use of synthetic chelators. [Copyright &y& Elsevier]

Chelating agents are thought to be useful for the remediation of metal-polluted soils with adequate organic matter, but the effects of these substances on the plants or seed bank of plant communities that occur in the soils are relatively unknown. In this work, the effects of two chelating substances (EDTA and DTPA) on a wet grassland plant community affected by the presence of the abandoned copper mine “Fernandito” (Garganta de los Montes, Madrid) were compared. A microcosm bioassay (6 months) was designed using the soil''s top layer containing the grassland''s seed bank. This soil showed a high Cu pollution level, significant contents of Zn and Cd (1120, 190, and 15 ppm, respectively), a pH of 5 and an OM content of 6. 2%. The soil was subjected to three different treatments: a) untreated soil (control), b) the addition of 1 g/kg EDTA, or of c) 1 g/kg DTPA. The results presented here are those related to the plant cover, species richness, aboveground and subterranean biomass and chemical composition of the most abundant plants. Neither EDTA nor DTPA caused intense negative effects on the plants rather they significantly increased the amount of copper accumulated in aboveground parts and roots. In particular, Agrostis castellana and Corrigiola telephiifolia extracted high amounts of copper when grown in the soil with added EDTA, although they showed some nutritional imbalances (lower P contents). In contrast, lower metal concentrations were detected in plants grown in the DTPA amended soil. [Copyright &y& Elsevier]

Abstract: The total and DTPA-extractable concentrations of Pb, Ni, Zn, Cu, Cr and Cd were measured in a calcareous soil amended with different doses of sewage sludge under field conditions. The same metals were also measured in the roots and leaves of Dactylis glomerata at the end of the first vegetative period after the sludge was added. The root concentrations of all the metals were unrelated to their concentrations in the soil. Leaf concentrations of Zn and Cr correlated with total (Zn) and DTPA-extractable (Zn and Cr) concentrations in the soil. DTPA extraction did not appear to be very useful for evaluating the bioavailability of metals in this kind of soil as it gave very low correlation coefficients with leaf content (r =0.684, P =0.0049 for Zn and r =0.557, P =0.0249 for Cr). Concentrations of Pb, Ni, Cu, and Cd in roots and leaves of Dactylis glomerata were unrelated to the total or DTPA-extractable concentrations in the sludge-amended soil. [Copyright &y& Elsevier]

Long-term irrigation with untreated industrial sewage effluents causes accumulation of high concentrations of chromium (Cr) and other heavy metals in soil and subsequently in crop plants (especially leafy vegetables), which can be phytotoxic to plants and/or a health hazard to animals and humans. Greenhouse experiments were conducted to determine the effects of Cr application on the growth of spinach ( Spinacia oleracia L.) and to develop critical toxic ranges of Cr in plants and in soil. The study involved growing of spinach variety ‘Punjab Green’ in a greenhouse on silty clay loam and sandy soils equilibrated with different levels of applied Cr (0, 1.25, 2.5, 5, 10, 20, 40, 80, 160, and 320 mg Cr kg - 1 soil). Plants were harvested at: three growth stages 45, 60, and 90 days after sowing (DAS). Critical toxic ranges were estimated by regressing and plotting data on ammoniumbicarbonate-diethylenetriaminepenta-acetic acid (AB-DTPA) extractable Cr in soil or Cr concentration in plants versus dry-matter yield (DMY) of spinach at the three growth stages. Toxic ranges, i.e., slightly toxic (80%–90%), moderately toxic (70%–80%), and extremely toxic ( [ABSTRACT FROM AUTHOR]

The presence of heavy metals in the sludges produced in waste-water treatment plants restricts their use for agricultural purposes. This study looks at different types of sludges (aerobic, anaerobic, unstabilised and sludge from a waste stabilisation pond) and compares the distribution of the heavy metals they contain according to the treatment that they have undergone. Some agronomic parameters necessary for characterising a sludge as suitable for use as amendment were determined. The aim of this study is to compare the availability and the localisation of heavy metals in different sewage sludges using simple (water and DTPA) extraction and the BCR (Community Bureau of Reference) sequential extraction procedure. It was confirmed that the total concentration of heavy metals did not exceed the limits set out by European legislation and that the stabilisation treatment undergone by the sludges strongly influenced the heavy metal distribution and the phases to which they were associated and their bioavailability level. The DTPA extraction procedure is cheap and easy to perform and the obtained results are similar to those obtained with the sequential procedure. [Copyright &y& Elsevier]

Different fractions of Ni, Zn, Cu and Pb were determined in metal-spiked forest soils derived from four parent materials using three extractants (H2O, CaCl2 and diethylenetriaminepentaacetic acid (DTPA)). It is important to determine how parent materials and soil properties affect the retention of these metals in order to predict their behavior and act accordingly in the event of accidental spillage, for example. The extraction of fractions was not sequential (before carrying out the extractions, the soil samples were divided into three parts), so the CaCl2 fraction also included the H2O one, and the DTPA fraction contained the other two. With the results, we developed models to predict the extraction of each fraction employing the physicochemical characteristics of the soil (e.g., pH, organic matter content and texture values) and the amount of metal added. The objective of this work was to determine how the properties of the soil would influence the fractioning of the metals considered, and through these characteristics create models to predict the behavior of each metal fraction. We found correlations between the different fractions of Ni and Zn, suggesting that there are soil properties that condition the retention of both metals. Pb and Cu showed different behavior than Zn or Ni, since the proportions extracted by H2O and CaCl2 were much lower. Regarding the DTPA fraction, unlike the case of Ni or Zn, the extraction of Cu and Pb was more homogeneous; they did not show great variation in different soils, even when considering the results of extraction in limestone soils. This may be due to the fact that the soil properties do not exert an important effect on their availability, or these two metals are considerably sensitive to the effect of pH, and no differences were observed because the extraction of the DTPA fraction was conducted with a buffered solution. For each fraction of metal used, we obtained a model with R2 always greater than 0.65. Considering these results, we can conclude that it is possible to predict Zn, Ni, Cu and Pb availability in soils developed on different parent materials. This can be achieved by identifying some basic soil characteristics and applying the developed equations. [ABSTRACT FROM AUTHOR]

• A cellulose-based amphoteric adsorbent was obtained by crosslinking. • The simultaneous complete removal of low-concentration heavy metal was achieved. • The specialization and cooperation mechanism were proposed. • The remaining concentrations still met the US EPA standards after 5 regenerations. A novel cellulose-based amphoteric adsorbent (MCC/DTPA-PEIA) with a high density of amino and carboxyl groups for the simultaneous complete removal of anionic and cationic heavy metal ions was designed and prepared by using cross-linking with microcrystalline cellulose (MCC) and DTPA-PEI, which was synthesized by the modification of diethylenetriaminepentaacetic acid (DTPA) with polyethylenimine (PEI). The MCC/DTPA-PEIA could completely remove Cr(VI), Cd(II), Cu(II), Zn(II) and Pb(II), and the remaining concentrations of low-level heavy metal ions after adsorption (2000 ppb) could reach the safe drinking level standards (US EPA). In addition, the cellulose-based amphoteric adsorbent exhibited good regeneration. It is interesting to note that the MCC provided by the MCC/DTPA-PEIA skeleton improved the adsorption rate of heavy metal ions. The competitive adsorption behaviors for anionic and cationic heavy metal ions on cellulose-based amphoteric adsorbents depend on the affinities of heavy metal ions for the amino and carboxyl groups of the adsorbents, and the simultaneous complete removal of MCC/DTPA-PEIA for low-level Cr(VI), Cd(II), Cu(II), Zn(II) and Pb(II) was attributed to the specialization and cooperation mechanism between amino and carboxyl groups of MCC/DTPA-PEIA. [ABSTRACT FROM AUTHOR]