Diethylenetriaminepentaacetic Acid Extraction Research Articles

Effect of DOM derived from composting on the changes of Pb bioactivity in black soil

Exogenous dissolved organic matter (DOM) plays an important role in the migration and transformation of heavy metals in soil. This study investigated the effect of composting-DOM with different maturity on changes of Pb bioactivity in soil, and evaluated the soil environmental factors driving these changes. The results showed that the activating ability of DOM to Pb in chernozem and dark brown soil increased by 4.11%−22.42% and 13.22%−30.15%, respectively. And the order followed: fresh manure (FDOM) > immature compost (IDOM) > mature compost (MDOM). The pH and dissolved organic carbon (DOC) were the main factors driving the changes in diethylenetriaminepentaacetic acid extraction (DTPA) -Pb in chernozem and dark brown soil, respectively. In chernozem, the input of MDOM can reduce the proportion of easily mobile fractions of Pb. While, DOM promotes the transformation of Pb from organic bound and residual fractions to exchangeable and carbonate bound fractions under other conditions. Moreover, the input of DOM can also drive the transformation of Pb species by regulating soil pH, electrical conductivity (EC), organic matter (SOM), DOC, and enzyme activity.

Non-equilibrium kinetic separation of thulium, yttrium and erbium on the surface of freely rising oil droplets

It is difficult to achieve selective separation and enrichment of different rare earths from high abundance yttrium ores efficiently only dependent on their discrepancy in thermodynamic properties. The present work suggests a new strategy based on non-equilibrium kinetic separation of Er and Tm on the surface of freely rising oil droplets to control the separation order of Y. It is revealed that the mutual separation of Er/Tm is significantly promoted with the separation coefficient of 2.89 during the non-equilibrium extraction with the addition of diethylenetriaminepentaacetic acid (DTPA). The extraction sequence of Tm, Er and Y can be controlled as Tm > Y > Er, thus Y can be selectively enriched during the process of separation of Er and Tm. Such a sequence is subject to the controllable dissociation rates of RE(III)–DTPA complexes and extraction abilities of P507 with the three RE(III) ions. The dissociation rate is dependent on the stabilities of RE(III)–DTPA complexes and follows the sequence of Y(III)–DTPA < Tm(III)–DTPA < Er(III)–DTPA. However, the extraction abilities of the three RE(III) ions follow the sequence of Y(III)–P507<Er(III)–P507<Tm(III)–P507. The competition complexation of DTPA and P507 at the interface of oil droplets results in an obvious change in the separation order of Y from Tm > Er > Y to Tm > Y > Er.

Prediction of the cadmium content in grains of low-accumulating wheat cultivars and soil cadmium threshold for safe production

Wheat cultivars with low cadmium (Cd) accumulation (WCCA-Cd) are widely used on Cd-contaminated farmland and can effectively reduce the grains Cd content to achieve the clean production in agriculture. However, there is a lack of soil Cd content thresholds specifically for the WCCA-Cd. To achieve safer production of wheat grains, a prediction model for WCCA-Cd was developed based on total Cd content in wheat grains (Grain-Cd) and soil factors using 379 soil‒wheat datasets from 10 field experiments in this research. The adaptability of the prediction model was tested using 312 pairs of data. Descriptive statistics (N = 379) showed that soil pH ranged from 4.28 to 8.76, the total Cd content in soil (Soil-Cd) ranged from 0.09 to 10.25 mg kg−1, and Grain-Cd ranged from 0.002 to 1.35 mg kg−1. Correlation analysis showed that Grain-Cd had a highly significant negative correlation with soil organic matter (SOM), soil pH, and soil conductivity (EC) and a highly significant positive correlation with Soil-Cd and Cd content in the diethylenetriaminepentaacetic acid extraction state (DTPA-Cd) (P < 0.001). The bioconcentration factor (BCF) decreased with increaseing soil pH. Both random forest and stepwise regression equations indicated that the most important factors affecting Cd bioeffectiveness were Soil-Cd and soil pH, explaining 80% of the variation in Grain-Cd. The prediction model indicated a soil Cd threshold (0.23–1.25 mg kg−1) for the safe production of WCCA-Cd at soil pH (4–9), which has a wider range of applicability compared with the Chinese Soil Safety Standards. Therefore, these results can quantify the grain Cd content of WCCA-Cd and guide the safe and clean production of WCCA-Cd on different Cd contaminated farmlands.

Performance comparison of phosphorus recovery from different sludges in sewage treatment plants through pyrolysis

Recycling of phosphorus (P) from pyrolysis sewage sludge is a good methodology to deal with the deficit of P resources and safely dispose the sewage sludge. However, it is essential to determine the type of sludge in sewage treatment plants (STPs) along with the most appropriate pyrolysis temperature. These factors affect the form and bioavailability of recoverable P. Thus, four kinds of sludge in a typical STP were selected, and three pyrolysis temperatures including 300, 500, and 700 °C were set to find a suitable strategy for P recovery. The results indicated that with increasing pyrolysis temperature, more organic phosphorus (OP) was transformed into inorganic phosphorus (IP) and more non-apatite inorganic phosphorus (NAIP) was converted to apatite phosphorus (AP, mainly Ca3(PO4)2, Ca(H2PO4)2, Mg3(PO4)2, Ca3Mg3(PO4)4, and Ca5(PO4)3OH). Compared to other sludges, dewatered cake sludge (CS) pyrolyzed at 700 °C had the highest AP content, about 1.1–3.6 times that in other pyrolysis products, and the highest Ca5(PO4)3OH content containing 35.8% of total phosphorus (TP). The contents of P-2% citric acid (CA) and neutral ammonium citrate (NAC) in CS obtained by pyrolysis at 500 °C reached 45.6 and 49.6 mg/g, respectively, which were 1.1–3.0 and 1.1–2.8 times that of P-CA and P-NAC in other sludges and their biochars, respectively. Moreover, the diethylenetriaminepentaacetic acid extraction analysis indicated that the good stability of heavy metals in CS-derived biochar was better than that in the feedstock. Hence, to ensure the efficiency and safety of P, CS is used as raw material in STPs to recover P resources. CS-500 can be used as the direct P source of land owing to the highest concentration of bioavailable P (P-CA and P-NAC), while CS-700 can be used to represent a slow-release P fertilizer because it contains the highest concentration of AP.

Comparison of ashing and pyrolysis treatment on cadmium/zinc hyperaccumulator plant: Effects on bioavailability and metal speciation in solid residues and risk assessment.

Phytoremediation of metal(loid)s contaminated sites is widely used, while there is scarce of investigation on the metal-enriched biomass waste safely disposal which resulted in risks of causing secondary pollution to the soil and water bodies and even to human health. Thus, this study compared the effects of ashing and pyrolysis treatments on cadmium (Cd) and zinc (Zn) hyperaccumulation plant Sedum plumbizincicola. Chemical speciation, the Toxicity Characteristic Leaching Procedure (TCLP), and diethylenetriamine pentaacetic acid (DTPA) extraction were employed to characterize the bioavailability and leachability of Cd and Zn in the solid residues after pyrolysis and ashing. The risk assessment code (RAC) and potential ecological risk index (RI) were subsequently used to evaluate the risk of the solid residues to the environment. The results showed that both ashing and pyrolysis treatments could transform the bioavailable Cd and Zn in S.plumbizincicola into a more stable form, and the higher the temperature the greater the stablility. Pyrolysis converted a maximum of 80.0% of Cd and 70.3% of Zn in S.plumbizincicola to the oxidisable and residual fractions, compared with ashing which achieved only a ∼42% reduction. The pyrolysis process minimised the risk level of Cd and Zn to the environment based on the RAC and RI assessments. The results of the TCLP test, and DTPA extraction confirmed that the leaching rate and the bioavailable portion of Cd and Zn in the biochars produced by pyrolysis were invariably significantly (p<0.05) lower than the solid residues produced by ashing, and reached the lowest at 650°C. In other words, pyrolysis was better than ashing for thermal treatment of the metal-enriched hyperaccumulator plant, in view of minimising the bioavailability and leachability of Cd and Zn from the solid residues to the environment. This study provides fundamental data on the choice of treatments for the disposal of metal-enriched plant biomass.

Immobilization of Lead and Cadmium in Soil Using Biochars Derived from Pig Manure and Suaeda glauca.

Biochar was for the first time produced from Suaeda glauca. The immobilization of Pb and Cd by this biochar and pig manure biochar was examined in two types of soils by diethylene triamine pentaacetic acid (DTPA) extraction. Addition of biochars decreased DTPA extractable Pb and Cd in Fluvo-aquic soil with reduction rates being 11.3%-48.4% and 0.74%-64.9% compared with the control treatment. The pig manure biochar favored the immobilization of Pb and S. glauca biochar favored the immobilization of Cd. Biochars can effectively immobilize heavy metals in Fluvo-aquic soil. However, the addition of biochars increased extractable Pb and Cd in red soil, with pig manure biochars showing greater rates. This is ascribed to that the competition effects of ions released from biochar enhanced the moving of heavy metals from iron and manganese oxides bound form to organic matter bound form, and hence enhanced the mobility and bioavailability of heavy metals.

Efficacy of copper foliar spray in preventing copper deficiency of rainfed wheat (Triticum aestivum L.) grown in a calcareous soil

Field experiments were conducted to evaluate the response of rainfed wheat (Triticum aestivum L.) to foliar copper (Cu) application in correcting Cu deficiency in calcareous soils. Two native soil Cu contents were tested in successive growing seasons. The soil “1” contained 0.35 mg kg−1 of Cu (Diethylenetriamine Pentaacetic Acid extraction). It was evaluated during the 2016-17 season. The soil “2” contained 0.61 mg kg−1. It was studied during the 2017-18 season. The rainfall amount was around 289 mm and 429 mm, respectively, for 2016-17 and 2017-18 seasons. For the soil “1”, the Cu treatments were: control, 0.2%, 0.4%, 0.6%, 0.8%, and 1%. For the soil “2”, the Cu tested levels were: control, 0.01%, 0.03%, 0.05%, 0.1%, and 0.2%. Cu was applied at the early boot growth stage in the sulfate form. The results showed that the response of grain yield to Cu foliar feeding was not related to the tested native soil Cu content. A significant grain yield increase, due to Cu spray, was revealed during the rainfall season (429 mm) in soil “2”. This increase was around 8% at 0.018% of Cu compared to control. However, Cu foliar application higher than 0.03% induced leaf damage. The Cu content of flag leaf and kernels showed a linear response to Cu supply. Flag leaf Cu content was around 5 mg kg−1 in control and exceeded 30 mg kg−1 at Cu application over than 0.03%.

Effects of wheat straw derived biochar on cadmium availability in a paddy soil and its accumulation in rice

This study was carried out to investigate the effect of biochar amendment on cadmium (Cd) availability in a paddy soil with biochar amendment and its effect on the accumulation in rice. Biochar was applied once at rates of 0 (A0), 10 (A10), 20 (A20), 30 (A30), and 40 (A40) t ha−1 on the soil surface layer (0–17 cm). Results showed that the soil organic matter (SOM) content and pH in 0–17 cm soil layer increased as biochar application rate increased, whereas the content of dissolved organic carbon (DOC), and available iron (Fe), manganese (Mn), aluminum (Al) in diethylenetriamine pentaacetic acid (DTPA) extracts declined with biochar added. Available Cd in DTPA extracts in the 0–17 and 17–29 cm soil layer of A40 treatments was significantly lower (p < 0.05) by 49.4 and 51.7% than that in A0. Compared with A0, the distribution factor (DF) of DTPA extracted Cd in the 0.053–0.25 mm and <0.053 mm aggregates of A40 treatments increased by 136 and 269%, respectively, and the DF values in these micro-aggregates of A40 treatments were greater than 1.0. Based on European Community Bureau of Reference (BCR) sequential extraction results, 40 t ha−1 rate of applied biochar reduced the proportion of acid extractable Cd fractions in both 0–17 and 17–29 cm soil layers, but increased the Cd in the oxidizable and residual fractions. The Cd concentration in the rice plants of different biochar treatments was in the order of A0>A10 > A20 > A30 > A40. DTPA extractable Cd concentration in soil was the key factor affecting the Cd uptake by rice roots. In conclusion, biochar application at 40 t ha−1 can effectively reduce the availability of Cd in soil profile, enhance the available Cd enrichment in micro-aggregates, and thus limit the Cd uptake by rice.

Visualization of Long-Term Quantitative Changes of Microelements in Soils Amended with Sewage Sludge Compost Evaluated with Two Extraction Solutions

ABSTRACTThis research deals with the effects of soil amendment with sewage sludge compost (SSC) on long–term quantitative changes of available microelements [iron (Fe), zinc (Zn), manganese (Mn), copper (Cu)] in two types of soils using various extraction solutions [diethylenetriaminepentaacetic acid (DTPA) and hydrochloric acid (HCl)]. These changes were visualized using principal component analysis (PCA) and hierarchical cluster analysis. A 3-year pot experiment was conducted in a randomized, factorial design with two soils (light vs. medium) and a treatment with SSC at the rate of 6 Mg ha−1. The application of SSC to the light soil increased the HCl-extractable Cu, Zn, Mn, and Fe. The effect of SSC application on the microelement quantitative changes was lower in the medium soil, as shown primarily by DTPA extraction. The results of the PCA highlighted that one can correctly conclude on the basis of the limited collection of data without loss of information, which is incorporated by individual microelements.

Estimation of Cadmium uptake by tobacco plants from laboratory leaching tests

ABSTRACTThe objective of the present study was to determine the impact of cadmium (Cd) concentration in the soil on its uptake by tobacco plants, and to compare the ability of diverse extraction procedures for determining Cd bioavailability and predicting soil-to-plant transfer and Cd plant concentrations. The pseudo-total digestion procedure, modified Tessier sequential extraction and six standard single-extraction tests for estimation of metal mobility and bioavailability were used for the leaching of Cd from a native soil, as well as samples artificially contaminated over a wide range of Cd concentrations. The results of various leaching tests were compared between each other, as well as with the amounts of Cd taken up by tobacco plants in pot experiments. In the native soil sample, most of the Cd was found in fractions not readily available under natural conditions, but with increasing pollution level, Cd amounts in readily available forms increased. With increasing concentrations of Cd in the soil, the quantity of pollutant taken up in tobacco also increased, while the transfer factor (TF) decreased. Linear and non-linear empirical models were developed for predicting the uptake of Cd by tobacco plants based on the results of selected leaching tests. The non-linear equations for ISO 14870 (diethylenetriaminepentaacetic acid extraction – DTPA), ISO/TS 21268-2 (CaCl2 leaching procedure), US EPA 1311 (toxicity characteristic leaching procedure – TCLP) single step extractions, and the sum of the first two fractions of the sequential extraction, exhibited the best correlation with the experimentally determined concentrations of Cd in plants over the entire range of pollutant concentrations. This approach can improve and facilitate the assessment of human exposure to Cd by tobacco smoking, but may also have wider applicability in predicting soil-to-plant transfer.

Metal Extractability in Binary and Multi-metals Spiked Calcareous Soils

ABSTRACTIn 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 CaCl2 or 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.

Nutrient dynamics in pistachios (Pistacia vera L.): The effect of mode of nutrient supply on agronomic performance and alternate-bearing in dry temperate ecosystem

The present research was accomplished on 8-year-old ‘Kerman’ pistachio nut (Pistacia vera L.) to study the nutrient dynamics in the dry temperate ecosystem of north-west Himalaya. We investigated the agronomic performance, alternate bearing behavior, soil fertility indicators and leaf nutrients usually to get higher nut yield and quality mainly as the blooming non-contemporaries during the first (2011) and third (2013) as ‘on’ years; second (2012) and fourth (2014) as ‘off’ years. This study has designed with the objective to determine the effect of different levels of NPK fertilizers and foliar Boron (B) fertilization on vegetative growth attributes, fruit set, nut yield and quality of pistachios. At each harvest season, yield per tree, nut attributes and buds abscission (alternate bearing) were recorded. Lightly cropping trees (‘off’ year) yielded 25.3% less, as heavily cropping trees (‘on’ year). N, P and K fertilizers applied as compounds at the rate of 600 (N1), 800 (N2) and 1000 (N3) gtree−1; P at 400 (P1) and 600 (P2) gtree−1 and K at 600 (K1), 800 (K2) and 1000 (K3) gtree−1 and B as boric acid (0.5%) were evaluated in 19 treatment combinations. N1P2K2 along with foliar B significantly improved vegetative growth measurements, fruit set, reduced buds abscission, reduced nut emptiness improved nut quality (fruit dimensions and sphericity) during ‘on’ and ‘off’ years of pistachios. Available macronutrient contents of soil (viz., N, P, K) increased by 23.6, 54.3, 29.4%, respectively. Diethylenetriaminepentaacetic acid–extractable (DTPA) micronutrients (Fe, Cu, Zn, and Mn) increased by 36.2, 78.9, 41.9 and 24.2%, respectively. Furthermore, lightly cropping trees (‘off’ year) have more leaf N, P, K and B concentration, as heavily cropping trees (‘on’ year). Correlation analysis of different attributes representing the physical-chemical attributes of soil parameters, nut yield and nut filling characteristics also resulted in a significant association at alpha=0.05 attribute pairs. Principal component analysis (PCA) of yield, nut filling characteristics and soil physico-chemical attributes was also worked out to evaluate the differences induced among treatment combinations applied. The results inferred that Principal Component-4 (PC-4) accounted for 77.1% of the total variance. Additionally, a great influence of NPK and foliar B fertilization is also showed for all the agronomic parameters studied in this work.

Effect of compost and manure amendments on zinc soil speciation, plant content, and translocation in an artificially contaminated soil

The addition of organic matter in soil can modify the bioavailability of heavy metals. A greenhouse pot experiment was carried out using an edible plant species Eruca vesicaria L. Cavalieri grown on an artificially contaminated soil with Zn (665 mg kg(-1)). In this study, the effect of compost at 20 t ha(-1) (C20) and at 60 t ha(-1) (C60), manure at 10 t ha(-1) (M10) and at 30 t ha(-1) (M30), and chemical fertilizers (NPK) on Zn fate in a soil-plant system was evaluated. At the end of the experiment, the main growth parameters and Zn content in plants were determined. In addition, Zn speciation in the soil was assessed using the original Community Bureau of Reference sequential extraction and diethylene triamine pentaacetic acid extraction. Zinc, though an essential element for plant growth, caused toxicity effects in plants grown on control and manure treatments, while in the compost treatments, plants showed no visual toxicity symptoms. The concentrations of Zn in roots were similar for all treatments, while significant differences were observed for shoots. In fact, in the compost treatments, plants showed the lowest Zn concentration in shoots. Zinc speciation seems not to be affected by the applied treatments. Indeed, Zn plant content and translocation to shoots seems to be affected. Compost amendments significantly reduced Zn content and translocation in comparison to other treatments.

DISTRIBUTION AND PHYTOAVAILABILITY PREDICTION OF ZINC IN AGRICULTURAL CALCAREOUS SOILS

The extractability and distributions of zinc (Zn) were evaluated in calcareous agricultural soils from South-West Iran. Both single [diethylenetriaminepentaacetic acid (DTPA)] and sequential extraction procedures (Singh scheme) were applied to 20 representative soils. The DTPA extractable zinc levels were low (on average 3.34%). The sequential extraction procedures were also utilized for the study of zinc phytoavailability in maize plants (Zea mays L.) in a greenhouse experiment. The Singh scheme was significantly better than DTPA plus soil properties in phytoavailability prediction of zinc in soils. Significant correlations were found between the amounts of DTPA extractable zinc and the iron (Fe) oxides-bound (AFe and CFe) and residual fractions extracted by the Singh procedure. Zinc concentrations in plant samples (mean value of 27.49 mg kg−1) were poorly correlated with the different extracted soil fractions (single and sequential). The Singh procedure provided better predictions of zinc uptake by plants than DTPA extraction method.

Pilot-scale washing of metal contaminated garden soil using EDTA

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.

Relative Efficiency of Different Extractants for Available Boron Estimation in Alkaline Calcareous Soils

Seven extractants widely used to determine plant-available boron (B) from either acidic or alkaline soils were tested for 20 alkaline and calcareous soil series from cotton belt of Punjab, Pakistan. The hot-water-soluble boron (HWS-B) extraction procedure was used as a benchmark to see any relative variation in available B in comparison with alternate extractants [0.05 M hydrochloric acid (HCl), 0.018 M calcium chloride (CaCl2), 1 M ammonium acetate (NH4OAc), 0.25 M sorbitol–diethylenetriaminepentaacetic acid (DTPA), 0.05 M mannitol prepared in 0.01 M CaCl2, 0.005 M ammonium bicarbonate (AB)–DTPA]. The soil series used in this study belonged to four soil orders (Aridisols, Entisols, Alfisols, and Inceptisols). The greatest mean B concentration (0.32 ± 0.11 mg kg−1) was obtained by hot water extraction followed by 0.05 M HCl extraction (0.31 ± 0.12 mg kg−1), whereas the lowest was obtained by 0.25 M sorbitol–DTPA (0.24 ± 0.06 mg kg−1) extraction. The comparison between soil series showed that the greatest HWS B and 0.05 M HCl B were 0.53 and 0.56 mg kg−1, respectively, in the Rustam series while the lowest were 0.11 and 0.12 mg kg−1, respectively, in the Thal series. Rasulpur, Rangpur, Sultanpur, Thal, and Kasur series had the lowest (<0.20 mg B kg−1) HWS-B concentrations. Although there was significant correlation for available B among all the extractants tested, the strongest correlation (r = 0.99** at P < 0.01) was observed between HWS B and 0.05 M HCl–extractable B. This study revealed that the 0.05 M HCl extraction method may substitute the hot water extraction method for plant-available B in alkaline and calcareous but modest fertile soils.

Immobilization of potentially toxic metals using different soil amendments

The in situ stabilization of potentially toxic metals (PTMs), using various easily available amendments, is a cost-effective remediation method for contaminated soils. In the present study, we investigated the effectiveness of apatite and a commercial mixture of dolomite, diatomite, smectite basaltic tuff, bentonite, alginite and zeolite (Slovakite) on Pb, Zn, Cu and Cd stabilization by means of decreasing their bioavailability in contaminated soil from an old lead and zinc smelter site in Arnoldstein, Austria. We also investigated the impact of 5% (w/w) apatite and Slovakite applications on soil functionality and quality, as assessed by glucose-induced soil respiration, dehydrogenase, acid and alkaline phosphatase and β-glucosidase activity. Both amendments resulted in increased soil pH and decreased PTM potential bioavailability assessed by diethylenetriamine pentaacetic acid extraction and by sequential extractions in the water-soluble and exchangeable fractions. The efficiency of stabilization was reflected in the soil respiration rate and in enzymatic activity. The β-glucosidase activity assay was the most responsive of them.

Evaluation of Different Extraction Methods for the Assessment of Heavy Metal Bioavailability in Various Soils

The main objective of this study was to compare the effectiveness of different methods (heavy metals in pore water (PW), diffusive gradients in thin films (DGT), diethylene triamine pentaacetic acid (DTPA) extraction, and total heavy metals (THM) in soil) for the assessment of heavy metal bioavailability from soils having various properties and heavy metal contents. The effect of soil heavy metal pollution on shoot yield and sulfatase enzyme activity was also studied. Wheat (Triticum aestivum) was grown in different soils from Spain (n = 10) and New Zealand (n = 20) in a constant environment room for 25 days. The bioavailabilities of Cd, Cr, Cu, Ni, Pb, and Zn were assessed by comparing the metal contents extracted by the different methods with those found in the roots. The most widely applicable method was DGT, as satisfactory Cu, Ni, Pb, and Zn root concentrations were obtained, and it was able to distinguish between low and high Cr values. The analysis of the metal concentrations in PW was effective for the determination of Cr, Ni, and Zn content in root. Copper and Pb root concentrations were satisfactorily assessed by DTPA extraction, but the method was less successful with determining the Ni and Cr contents and suitable just to distinguish between high and low concentrations of Zn. The THM in soil method satisfactorily predicted Cu and Pb root concentrations but could only be used to distinguish between low and high Cr and Zn values. The Cd root concentration was not successfully predicted for any of the used methods. Neither shoot yield nor sulfatase enzyme activity was affected by the metal concentrations.

Kinetics of DTPA extraction of zinc from calcareous soils

Abstract The kinetics of Zn extraction by diethylenetriaminepentaacetic acid (DTPA) from the ≤ 2 mm fraction of 12 calcareous soils was investigated using surface soil (0–30 cm) samples. Soils were equilibrated with 0.005 M, DTPA solution for 0.25 to 192 h. Zero-, first-, second-, third-order, parabolic diffusion and simple Elovich equations did not adequately describe Zn extraction kinetics. The best model for describing extraction data for all soils was the exponential rate equation ( q = a t b ). q is the amount of Zn desorption (mg Zn kg − 1 ), a is the Zn desorption magnitude constant (mg Zn kg − 1 h − 1 ) and b is the desorption rate constant. Constant a ranged from 21 to 79.8 with a mean of 41.4 and b from 0.19 to 0.33 with a mean of 0.25. The differences in a value presumably reflect the quite different properties and constituents of these soil types. The magnitude constant a , was positively correlated ( r = 0.76⁎⁎) to organic carbon content and negatively to pH ( r = − 0.67⁎). The rate constant b was not related to any of the measured soil properties such as pH, cation exchange capacity, carbonate calcium equivalent, active calcium carbonate equivalent, clay content, organic carbon and specific surface area or to any combination of these properties.

Characterisation of soil quality and mobility of Cd, Cu, Pb and Zn in the Baia Mare area Northwest Romania following the historical pollution

The paper presents a characterisation of the soil quality and mobility of Cd, Cu, Pb and Zn in the Baia Mare city, northwest Romania, historically polluted with airborne particulate matter resulted from non-ferrous ores processing. Although the impact of the ores smelters on the environment is relatively limited today, Baia Mare is still a highly polluted site with Cd, Pb, Cu and Zn. The concentration ranges of metals in soil were (mg kg−1): 1.9-25.4 Cd, 87.7-9880 Pb, 78.3-962 Cu, 109-11500 Zn, of which in (%): 1.3-80; 2.2-40; 2.0-34 and 0.3-21 as mobile species in 0.005 mol L−1 diethylenetriaminepentaacetic acid (DTPA). Baia Mare is more polluted with Cu, Pb and Zn than Copsa Mica and Cu, Pb than Zlatna, other smelter centres in Romania. Also, pollution is higher compared to similar centres in Europe. Cd, Pb and Cu are the most severe contaminants as available species for plants and should be considered in the soil remediation strategy. The PCA on metal contents following aqua regia mineralisation and DTPA extraction allowed the identification of anthropogenic origin from three sources associated with the Flotation Station (residual species), Cuprom plant (Cu, Cd and Zn mobile species) and Romplumb plant (Pb mobile species). The car traffic as anthropogenic source does not modify the pollution pattern caused by industrial activity since no association between Pb and Zn was found. On the other hand, an affinity between Cd and Zn as well as between Cu and Pb were also identified. A particular case is that of Cu, for which the PCA revealed an interference of polluters. Statistics are in agreement with the distribution maps of contaminants.