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Abstract An analysis of the Cd and mineral nutrients accumulation of upland rice was performed in an experimental field with hard-ridged plots containing three soils with exogenous Cd addition at rates of 0, 0.25, 0.5, 1, 2, 4, 8, 16 mg kg−1 five years prior to commence this experiment. Aims of this investigation were to study uptake, translocation, and accumulation of Cd by an upland rice (Huyou2) and effects of Cd addition on the accumulation of Fe, Zn, Ni, Ca, and Mg. The results demonstrate the mean Cd content in the plant parts, from highest to lowest, were as follows: root, stem, leaf, and brown rice. The Cd content in the brown rice of the upland rice was below the limit of Cd in rice (0.2 mg kg−1) from China (GB 2762-2017) when the amount of Cd added was ≤ 1 mg kg−1. This observation can be attributed to lower TF soil-grain of Cd in upland rice. Significant differences were observed between Cd concentrations present in brown rice from the three soils which can be mainly attributed to the differences in DTPA-extractable soil Cd because of different soil pH. Addition of high concentrations of Cd to soil was found to reduce Fe, Zn, Mg, and increased Ni uptake by the roots and their accumulation in brown rice. Altogether, results of this study suggest that it may be possible to cultivate upland rice in slightly Cd-polluted soils and Cd toxicity and accumulation in upland rice can be minimized by optimizing the macro and micronutrient composition of the soil. Graphical abstract Image 1 Highlights • Cd in the grains of the upland rice were below 0.2 mg kg−1 when the Cd added was ≤ 1 mg kg−1. • TFs within the rice plant declined with increasing soil Cd with a turning point at 0.25 mg Cd kg−1. • Higher Cd inhibited the accumulation of Fe, Zn, Ca, and Mg in the brown rice. [ABSTRACT FROM AUTHOR]

There is significant current interest in the application of magnetic (magnetite or maghemite) nanoparticles functionalised with chelating agents for the environmental remediation of metal contaminated waters and solutions. Whilst there is a body of knowledge about the potential remediation efficacy of such engineered nanoparticles from studies involving synthetic solutions of single metals, there is relatively little data involving mixed-metal solutions and virtually no studies about nanoparticle performance in chemically complex environmental solutions representing those to which a scaled-up nanoremediation process might eventually be applied. Therefore, we investigated the ability of diethylenetriaminepentaacetic acid (DTPA)-functionalised, silica-coated maghemite nanoparticles to extract potentially toxic (Cd, Co, Cu) and “non-toxic” (Ca, Mg) metals from solution (initial [metal] = 10 mg L −1 ; pH range: 2–8) and to extract a wider range of elements (As, Ca, Cd, Co, Cr, Cu, Mg, Na, Pb, Zn) from leachate obtained from 10 different contaminated soils with variable initial pH, (semi-)metal and dissolved organic carbon (DOC) concentrations. The functionalised nanoparticles could extract the potentially toxic metals with high efficiency (in general >70%) from single metal solutions and with efficiencies that were either unaffected or reduced from the soil leachates. K d values remained high (>500 L kg −1 ), even for the soil leachate extractions. Our findings show that DOC and relatively high concentrations of non-toxic elements do not necessarily reduce the efficiency of metal contaminant removal by DTPA-functionalised magnetic nanoparticles and thus demonstrate the remediation potential of such particles when added to chemically complex soil-derived contaminated solutions. [ABSTRACT FROM AUTHOR]

Mine tailings have adverse chemical and physical conditions, including high concentrations of metals and salts, low organic matter content, and unbalanced rates of nutrients which limit the development of vegetation. A large scale field experiment was conducted to reclaim a tailing pond by triggering the growth of native species by spontaneous colonization by tilling (TL) the tailing pond surface and using marble waste (CaCO 3 ; MW), pig slurry (PS) and their combination (MW + PS) as soil amendments. Soil physicochemical properties and water and DTPA extractable metal concentrations of bulk and rhizosphere soils were analyzed after five year from the application of the treatments. In addition, plants of Atriplex halimus from each treatment were collected and metals in roots, leaves and stems analyzed. Before amendments application, the studied pond showed a neutral pH, high salinity and a moderate organic carbon content. After five years, the pH value was significantly increased only in MW plot. The results showed significant increases of DTPA-extractable Zn in MW and MW + PS plots, Pb in all treatments except MW plot, Cd only in PS plot, and Cu only in MW + PS plot. A. halimus was the most dominant species, growing spontaneously in all plots, with lower vegetation cover in CT and MW plots, 6% and 2% respectively. Application of MW increased leaf Pb accumulation by 2.5-fold and Cd by 55%, when compared to the CT. The high initial salinity and probable substitution of metals by Ca 2+ on exchangeable surfaces of soil particles may be the reasons for higher uptake of metals in MW plot when compared to the other plots. Although this plant is widely utilized in contaminated sites for phytostabilization purposes, it may absorb and translocate high concentrations of metals to the aboveground tissues in saline contaminated sites. [ABSTRACT FROM AUTHOR]

The electrochemical incineration of diethylenetriaminepentaacetic acid (DTPA) with boron-doped diamond (BDD) anode had been initially performed under galvanostatic conditions. The main and interaction effects of four operating parameters (flow rate, applied current density, sulfate concentration and initial DTPA concentration) on mineralization performance were investigated. Under similar experimental conditions, Doehlert matrix (DM) and central composite rotatable design (CCRD) were used as statistical multivariate methods in the optimization of the anodic oxidation processes. A comparison between DM model and CCRD model revealed that the former was more accurate, possibly due to its higher operating level numbers employed (7 levels for two variables). Despite this, these two models resulted in quite similar optimum operating conditions. The maximum TOC removal percentages at 180 min were 76.2% and 73.8% for case of DM and CCRD, respectively. In addition, with the aid of quantum chemistry calculation and LC/MS analysis, a plausible degradation sequence of DTPA on BDD anode was also proposed. [ABSTRACT FROM AUTHOR]

Biochar may affect the mineralization rate of labile organic C sources such as manures via microbial community shifts, and subsequently affect nutrient release. In order to ascertain the positive or negative priming effect of biochar on manure, dairy manure (2% by wt.) and a hardwood-based, fast pyrolysis biochar were applied (0%, 1%, 2%, and 10% by wt.) to a calcareous soil. Destructive sampling occurred at 1, 2, 3, 4, 6 and 12 months to monitor for changes in soil chemistry, water content, microbial respiration, bacterial populations, and microbial community structure. Overall results showed that increasing biochar application rate improved the soil water content, which may be beneficial in limited irrigation or rainfall areas. Biochar application increased soil organic C content and plant-available Fe and Mn, while a synergistic biochar–manure effect increased plant-available Zn. Compared to the other rates, the 10% biochar application lowered concentrations of NO 3 -N; effects appeared masked at lower biochar rates due to manure application. Over time, soil NO 3 -N increased likely due to manure N mineralization, yet soil NO 3 -N in the 10% biochar rate remained lower as compared to other treatments. In the presence of manure, only the 10% biochar application caused subtle microbial community structure shifts by increasing the relative amounts of two fatty acids associated with Gram-negative bacteria and decreasing Gram-positive bacterial fatty acids, each by ∼1%. Our previous findings with biochar alone suggested an overall negative priming effect with increasing biochar application rates, yet when co-applied with manure the negative priming effect was eliminated. [ABSTRACT FROM AUTHOR]

To promote the colonization of Phragmites in Cd polluted, nutrient deprived and structural damaged soil, the combined remediation using chemical and microbial modifiers were carried out in potting experiments. The co-application of Diversispora versiformis and sodium bentonite significantly improved the soil structure and phosphorus utilization of the plant, while decreasing the content of cadmium bound by diethylenetriaminepentaacetic acid by 77.72%. As a result, the Phragmites height, tillers, and photosynthetic capacity were increased by 71.60%, 38.37%, and 17.54%, respectively. Further analysis suggested the co-application increased the abundance of phosphorus-releasing microbial communities like Pseudomonas sp. and Gemmatimonadetes. Results of rhizosphere metabolites also proved that the signal molecule of lysophosphatidylcholine regulated the phosphorus fixation and utilization by the plant. This work finds composite modifiers are effective in the colonization of Phragmites in Cd contaminated soil by decreasing the bioavailable Cd, increasing the abundance of functional microbial communities and regulating the phosphorus fixation. [Display omitted] • Mycorrhizal fungi and bentonite promoted Phragmites colonization in polluted soil. • Bentonite modified the morphological distribution of soil Cd. • Mycorrhizal fungi immobilized Cd by secreting glomalin-related soil protein. • Molecule metabolism indicated the improvement of phosphate fixation. [ABSTRACT FROM AUTHOR]

Highlights: [•] Fe(III) and Cu(II) are able to strongly dissociate Gd-DTPA, leading to the release of free gadolinium in water. [•] The replacement of free Gd in Gd-DTPA by Zn(II) remained very low independent from the conditions applied in this study. [•] In coagulation–flocculation simulation with Fe(III), the dissociation of Gd-DTPA was significant (about 27%). [ABSTRACT FROM AUTHOR]

Abstract: In a controlled environment experiment, using Cd spiked soil, lettuce plants were grown under a range of DTPA levels and were subsequently harvested to determine levels of phytoaccumulation. Cadmium phytoaccumulation significantly increased with increasing soil Cd level (P <0.05) but unexpectedly decreased with increasing DTPA levels, despite the fact that solubility of Cd was increased in the soil. Cadmium translocation (from root to shoot) increased after DTPA application. Lettuce growth was inhibited by both Cd and DTPA (at and above 10 and 500mgkg−1 respectively), as a result of higher Cd mobility and subsequent toxicity which was caused by DTPA higher dosages. Metal solubility in the soil (ranged between 2.8 and 26.5mgkg−1) was found to be significantly higher (P <0.01) as compared to control with increasing DTPA levels even after 3months of DTPA application. Cadmium tissue concentration in all DTPA treatments was less than in the corresponding control treatment, indicating a negative effect of DTPA application on Cd uptake. In conclusion, lettuce was an unsuitable plant species for Cd accumulation, at least when associated with a DTPA chelator. [Copyright &y& Elsevier]

Abstract: Chelating sorbents with diethylenetriaminepenta(methylene-phosphonic acid) (DTPMPA) and ethylenediaminetetraacetic acid ligands immobilized on zirconia matrix were prepared and subsequently saturated with Cu(II). All the Cu chelates catalyzed decomposition of H2O2 yielding highly reactive hydroxyl radicals. All of them were also able to catalyze degradation of polycyclic aromatic hydrocarbons (anthracene, benzo[a]pyrene and benzo[b]fluoranthene). The most effective DTPMPA-based catalysts G-32 and G-35 (10mgml−1 with 100mmol H2O2) caused almost complete decomposition of 15ppm anthracene and benzo[a]pyrene during a five day catalytic cycle at 30°C. Anthracene-1,4-dione was the main product of anthracene oxidation by all catalysts. The catalysts were active in several cycles without regeneration. [Copyright &y& Elsevier]

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]

Abstract: The concentrations of different forms of Zn, Cu, Mn, Ni, Cd, Cr, Pb and Fe metals were determined for the roadside sludge collected from pickling-rolling and electroplating industrial area. In sludge the relative abundance of total heavy metals were Fe>Mn>Cr>Ni>Cu>Pb>Zn>Cd and DTPA-extractable metals were in the order -- Fe>Ni>Mn>Cr>Cu>Zn>Pb>Cd. Pot-culture experiment was conducted in soils amended with sludge (0%, 10%, 20%, 30%), pretreated with lime (0%, 0.5% and 1%). The soils were alkaline in nature (pH>8.3) with organic carbon contents were 0.34% and 0.72%. The most abundant total and bio-available metal was Fe. Two wheat seedlings were grown in each pot containing 3kg sludge-amended or control soil and the experiment was conducted till harvesting. Application of sludge increased both total and bio-available forms of metals in the soils, while lime application decreased the bioavailability of heavy metals in sludge-amended soils. The content of organic carbon showed positive correlation with all metals except Zn, Cr and Pb. CEC also showed a strong positive correlation (R 2 >0.7) with Fe, Mn, Cu, Ni and Cd. Though wheat plants are not accumulators, the translocation efficiency was appreciably high. The translocation factor from shoot to grain was found smaller than that of root to shoot of wheat plants. This makes an implication that the heavy metal accumulation was proportionally lesser in grain than in shoot. In, 10% sludge with 0.5% lime-amended soils; each of these toxic heavy metals was found to be within permissible range (USEPA). Hence, on the basis of present study, the best possible treatment may be recommended. [Copyright &y& Elsevier]

Forest/tilled soils and stream sediments from the highly polluted mining and smelting district of Příbram, Czech Republic, were subjected to single extraction procedures in order to determine the available contents of Sb and As. The results obtained from five widely-used 2-h single extraction tests were compared: deionised water, 0. 01M CaCl2, 1M NH4NO3, 0. 005M diethylentriaminpentaacetic acid (DTPA) and 0. 1M Na2HPO4. The ICP-MS determinations of Sb and As in the extracts were coupled with measurements of pH and Eh and geochemical modelling (PHREEQC-2) to determine their speciation in extracts and possible solubility-controlling phases. According to the speciation calculations, Sb in extracts was present mainly as Sb(V) with the exception of the DTPA extracts from highly organic and acidic forest soils, where Sb(III) species accounted for up to 34% of total Sb speciation. The highest extractabilities were observed for the 0. 1M Na2HPO4 solution (up to 9% of the total Sb and up to 34% of the total As concentration). The other extracting media yielded statistically the same results (p <0. 05) with Sb extractabilities below 2% and As extractabilities below 8%. Thus, simple deionised water and 0. 1M Na2HPO4 extractions are preferred for quick estimates of easily-exchangeable and specifically-sorbed Sb, respectively. [Copyright &y& Elsevier]

Brassica juncea, or Indian mustard, was grown in soil artificially contaminated with either a soluble salt, CdCl2, at 186mg Cdkg−1, or alternately an insoluble, basic salt, CdCO3, at 90mg Cdkg−1. These experiments study the range of Cd uptake by Indian mustard from conditions of very high Cd concentration in a soluble form to the other extreme with an insoluble Cd salt. After plants were established, four different chelating agents were applied. Chelating agents increased plant uptake of Cd from the CdCl2 soil but did not significantly increase plant uptake of Cd from the CdCO3 contaminated soil. Addition of ethylenediaminetetraacetic acid (EDTA) increased the plant concentration of Cd by almost 10-fold in soils contaminated with CdCl2, with a concentration of 1283mg Cdkg−1 in the dried EDTA-treated plants over a concentration of 131mg Cdkg−1 in plants without added chelate. However, EDTA increased the aqueous solubility of Cd by 36 times over the soil matrix without added chelator, and thereby, increased the possibility of leaching. Other chelators used in both experiments were ethylenebis(oxyethylenenitrilo)tetraacetic acid, trans-1,2-diaminocyclohexane-N,N,N′,N′-tetraacetic acid, and diethylenetriaminepentaacetic acid (DTPA) increasing Cd in plants to 1240, 962, and 437mg Cdkg−1, respectively. The other chelating agents increased the solubility of Cd in the leachate but not to the extent of EDTA. Comparing all chelating agents studied, DTPA increased plant uptake in terms of Cd in dried plant concentration most relative to the solubility of complexed Cd in runoff water. [Copyright &y& Elsevier]

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]

Here, the bio-nanocomposite (n-HFP + n-HFS)@ An was developed to simultaneously immobilize Pb, Cd and As in the severely contaminated soil. The immobilization rates of diethylenetriaminepentaacetic acid (DTPA)/decarbonate-extracted bioavailable Pb, Cd and As were 59.87%, 31.28% and 62.30%, and the immobilization rates of their water-soluble forms were 63.12%, 60.02% and 89.39%, respectively. Moreover, the ten-year acid rain simulated leaching assay showed that the maximum cumulative release contents of Pb, Cd and As in the treated soil samples were decreased by 2.94, 2.46 and 40.60 times, comparing to the un-treated ones. Additionally, the results of SBRC (Solubility Bioaccessibility Research Consortium) revealed that the bioaccessible rates of the three metals in intestinal phase were lower than in gastric phase, and both of them decreased with increasing the immobilization time. The gastric bioaccessibility of Pb, Cd and As had a higher correlation with the contents of water-soluble forms, while the intestinal bioaccessibility was more strongly positively associated with the bioavailable forms. • A novel bio-nanocomposites simultaneously immobilize Pb, Cd and As in soil. • Bioavailable and water-soluble Pb, Cd and As were significantly immobilized. • Immobilized metals were stable in the ten-year acid rain simulated leaching assay. • Gastric bioaccessibility had a higher correlation with water-soluble metals. • Intestinal bioaccessibility was more strongly associated with bioavailable metals. [ABSTRACT FROM AUTHOR]