Arsenic In Soils Research Articles

The effect of the synergistic thermal treatment and stabilization on the transformation and transportation of arsenic, chromium, and cadmium in soil

Thermal treatments commonly used to remedy organic-contaminated soils can inadvertently impact the behavior of non-targeted pollutants, notably heavy metal(loid)s in soil. This study introduces an integrated calcination-stabilization remediation strategy employing steel slag as a stabilizing agent, with a focus on elucidating the transformations and remobilization tendencies of As, Cr, and Cd. Thermal treatment alters the mobility of these elements by modifying soil properties, with pH and redox conditions playing pivotal roles. After anaerobic calcination, the leaching concentrations of As reached 163 μg L−1, far surpassed 7.57 μg L−1 after the aerobic calcination. Although Cr and As share oxygen-containing anion forms, they display opposing leaching tendencies after thermal treatment. At 400 °C, Cr leaching from aerobically treated soil reaches 64.5 mg L−1, dropping to 6.63 mg L−1 after anaerobic heating due to pH-induced Cr(OH)3 formation. Thermal treatment significantly amplifies the leaching of Cd cations. In contrast to the leaching concentration of 122 μg L−1 in the untreated soil, aerobic and anaerobic heating (400 °C) resulted in leaching concentrations of 896 μg L−1 and 132 μg L−1, respectively. Noteworthy, the integrated treatment (400 °C anaerobically) decreases leached As and Cd concentrations to 68.3 μg L−1 and 15.4 μg L−1, attributed to stabilizer alkalinity and porosity. Column leaching shows initial rapid release followed by continuous behavior for As and Cd, with the average leaching concentrations of the remediated soil decreasing to 60.5 μg L−1 and 1.32 μg L−1, ensuring safe backfilling. In conclusion, this study contributes to the understanding of the mobility and stabilization of heavy metal(loid)s subsequent to the integrated calcination-stabilization process.

Mixed effects and co-transfer of CeO2 NPs and arsenic in the pakchoi-snail food chain

Nanomaterial application in agriculture offers novel solutions for soil arsenic (As) pollution control, yet safety along the food chain is of concern. We comprehensively assessed CeO2 nanoparticles (NPs) foliar application effects on As uptake by pakchoi and their presence in the pakchoi-snail food chain. CeO2 NPs reduced As transfer from pakchoi roots to shoots by 37.9%, lowered As in snail foot by 39%, and halved human As exposure risk. The NPs alleviated pakchoi shoot As toxicity by regulating antioxidants, enhancing water use efficiency, and photosynthesis. CeO2 +As treatment raised GSH/GSSG ratios by 38.92%− 167.54%, leading to an increased AsIII/AsV ratio and inorganic As detoxification compared to As alone. Metabolomics revealed CeO2's rapid As response via phosphatidylinositol signaling. The enzyme-like activity of CeO2 NPs may drive these effects. While CeO2 foliar application accumulated Ce on pakchoi leaves, > 99% of Ce was excreted following snail consumption. Ce transfer from pakchoi leaves to snail foot was minimal (trophic transfer factor ∼0.00007) due to limited bioavailability. The target hazard quotient of Ce in pakchoi shoot (1.21 ± 0.18) and snails (0.0016 ± 0.0004) indicated low exposure risk, suggesting a ‘risk filter’ effect for CeO2. Our results contribute to the safe and sustainable application of CeO2 NPs in the future implication.

Assessment of the Suitability of Extractants for Predicting Plant Available Arsenic in Some Tropical Rice Growing Inceptisols of Eastern India

ABSTRACT The complex behavior of arsenic (As) in soil in conjunction to crop mediated transfer through the food chain necessitates a thorough evaluation of its phyto-availability. In this pretext, the present experiment has been conducted to determine the best chemical extractant for plant available As under the As-prone, rice-dominant agro-ecosystems of Gangetic West Bengal, India. Based on the tube-well arsenic data (JPOA, UNICEF), surface soil samples from high, medium, low and uncontaminated As sites have been collected. A pot study with rice cv. IR-36, exposed to varying levels of As (0, 0.1, 0.2, 0.3 and 0.4 mg L−1) was conducted. Ten chemical extractants were used in this study. The As extraction pattern followed the pattern of (HCl+H2SO4)>; (NH4-oxalate+Ascorbic acid)>; (Malic+Citric)> NaOH> KH2PO4> NaHCO3>; (H2O2+HNO3)> NH4F> NH4Cl> NH4OAc. On the 85th day after sowing, the rice plants were harvested keeping in mind that the maximum uptakes of heavy metals like As occurs during the peak vegetative growth (panicle initiation) stage. The soil As correlated with rice dry matter As accumulation as: NH4-oxalate+ascorbic acid (r = 0.729**)> NH4Cl (r = 0.698**)> H2O2+HNO3 (r = 0.697**)> NH4F (r = 0.693**)>Malic+Citric (r = 0.666**)> KH2PO4 (r = 0.615**)> HCl+H2SO4 (r = 0.608**)> NaOH (r = 0.589**)> NaHCO3 (r = 0.571**)> NH4OAc (r = 0.533*). Statistical analyses through correlation sum and stepwise multiple regression modeling revealed that NH4-oxalate+ascorbic acid had the best relationship with all other extractants, As fractions and soil physicochemical characters and therefore emerged as the best suited extractant of As for the wide-scale experimental locations under rice cultivation system.

Migration of spent grain-modified colloidal ferrihydrite: Implications for the in situ stabilization of arsenic, lead, and cadmium in co-contaminated soil

The increase of metal mining, processing, and smelting activities has precipitated a substantial escalation in the contamination of soil by heavy metals. Ferrihydrite (FH) has been commonly used as an amendment for the immobilization of heavy metals in contaminated soil. However, FH suffers from drawbacks such as agglomeration and nonmigratory characteristics, which limit its practical application in soil remediation. Herein, a novel spent grain-modified ferrihydrite (FH-SG) colloidal system was developed, and the FH-SG transport mechanisms in the soil medium were fully studied, focusing in particular on the simultaneous in situ stabilization of arsenic (As), lead (Pb), and cadmium (Cd) in co-contaminated soil. The results showed that the stabilization rates of the FH-SG material reached 94.66%, 96.12%, and 95.52% for water-soluble As, Pb, and Cd, respectively, and 72.22%, 49.39%, and 25.30% for bioavailable As, Pb, and Cd, respectively. The FH-SG material demonstrates notable migration properties in porous media. Theoretical calculation results of a single collector show that the migration deposition of FH-SG material in media is primarily governed by its inherent diffusion characteristics with minimal influence by gravitational forces and media interception. It is noteworthy that the maximum migration distance in quartz sand and soil media with different particle sizes can reach 2.07–2.92 m and 0.78–1.08 m, respectively. Altogether, our findings clearly demonstrate that FH-SG exhibits better stabilization and migration than those of FH alone and most proposed FH colloidal systems. The FH-SG colloidal system holds significant promise for the remediation of various kinds of complex polluted soil.

Immobilization of arsenic in soil using modified bentonite and red mud to reduce its bio-availability in Brassica juncea

The influence of modified clay mineral and red mud on biological yield and arsenic bioavailability to mustard were investigated. The total biomass of the mustard was increased by application of clay mineral and red mud products. At higher doses (5.00 g/kg), Fe-bentonite treated soil recorded the highest total plant biomass (11.2 g/pot). DMSO-bentonite (1.23 mg/kg) and Fe-bentonite (1.28 mg/kg) were proved to be most effective in reducing the extractable arsenic concentration in soil at the rate of 5.00 g/kg doses. These products also help in lowering the hazard quotient (0.20–0.08) values for human consumption of arsenic through mustard leaf. This means that modified types of bentonites and red mud boost mustard productivity by reducing arsenic concentration.

Trans-Global Biogeochemistry of Soil to Grain Transport of Arsenic and Cadmium

Previous studies have shown that arsenic and cadmium can accumulate in rice grain to levels that cause health concerns. Furthermore, geographical survey has shown that there is considerable variation (~ 100-fold) in accumulation of these carcinogens in rice grain. This variance must be due to heterogeneity in soil biogeochemistry and contrasting rice management regimens. Here we present the first systematic global study to investigate the impact of soil biogeochemistry on accumulation of these elements in rice grain. Matched grain, shoot, root and soil samples were collected across a latitudinal gradient from East Africa to Europe and soil, shoot, grain chemistry and soil microbial community (prokaryotes and fungi) assessed within the context of arsenic and cadmium biogeochemistry. European and Vietnamese grain sum of arsenic species (inorganic arsenic plus dimethylarsonic acid) concentration medians, ~ 0.1 mg/kg, were found to be around ten-fold higher compared to those in East Africa and Sri Lanka. Arsenic concentrations were linked to higher levels of soil arsenic, and to higher abundance of soil sulphur-oxidising and sulphate reducing bacteria and methanogenic archaea. For cadmium, Sri Lanka showed highest (median 0.0156 mg/kg) and Europe lowest (median of 0.001 mg/kg) levels in grain, with the other regions showing intermediate values. Interestingly, grain cadmium was unrelated to soil cadmium concentrations, with Europe having the highest levels of cadmium in soil. Instead, grain cadmium correlated with higher oxidation/reduction potential, lower -log[hydrogen ion], lower soil calcium, and to a higher abundance of aerobic bacteria and fungi (lowest abundance of these organisms in European soils).

Unraveling the aging dynamics in the simultaneous immobilization of soil metal(loid)s using oxides

Immobilization represents the most extensively utilized technique for the remediation of soils contaminated by heavy metals and metalloids. However, it is crucial to acknowledge that contaminants are not removed during this process, thereby leaving room for potential mobilization over time. Currently, our comprehension of the temporal variations in immobilization efficacy, specifically in relation to amendments suitable for industrial sites, remains very limited. To address this knowledge gap, our research delved into the aging characteristics of diverse oxides, hydroxides, and hydroxy-oxides (collectively referred to as oxides) for the simultaneous immobilization of arsenic (As), cadmium (Cd), and antimony (Sb) in soils procured from 16 contaminated industrial sites. Our findings unveiled that Ca-oxides initially showed excellent immobilization performance for As and Sb within 7 days but experienced substantial mobilization by up to 71 and 13 times within 1 year, respectively. In contrast, the efficacy of Cd immobilization by Ca-oxides was enhanced with the passage of time. Fe- and Mg-oxides, which primarily operate through encapsulation or surface complexation, exhibited steady immobilization performances over time. This reliable and commendable immobilization effect was observed across distinct soils characterized by varying physicochemical properties, including pH, texture, CEC, TOC, and EC, underscoring the suitability of such amendments for immobilizing metal(loid)s in diverse soil types. MgO, in particular, displayed even superior immobilization performance over time, owing primarily to gradual hydration and physical entrapment effects. Remarkably, Mg-Al LDHs emerged as the most effective candidate for the simultaneous immobilization of As, Cd, and Sb. The results obtained from this study furnish valuable data for future investigations on the immobilization of metals and metalloids in industrial soils. They enable the projection of immobilization performance and offer practical guidance in selecting suitable amendments for the immobilization of metal(loid)s.

Simultaneous mitigating the bioavailability of cadmium and arsenic in paddy soil by two carbon-iron composites: A field-scale evaluation

Cadmium and arsenic have become the difficulty of soil inorganic pollution control due to their opposite chemical properties. Field experiments were performed to evaluate the performance and mechanism of the carbon-iron composites in mitigating the bioavailability of soil Cd and As. The mitigating performance for Cd bioavailability decreased as follows: ZVI-biochar > ZVI-peat > biochar > wood peat > ZVI, and the mitigating performance for As bioavailability was in the order of ZVI-peat > ZVI-biochar > ZVI; Biochar and wood peat enhanced the bioavailability of soil As. Both ZVI-biochar and ZVI-peat composites showed superior immobilization performance due to its higher soil pH, formation of soil amorphous Fe oxyhydroxides and roots iron plaque. The increased Fe nutrition inhibited the transportation of Cd and As from roots to grains. Both ZVI-biochar and ZVI-peat resulted in a more than 42 % reduction for grain Cd and 33.8 % reduction for grain As.

Key process for reducing grains arsenic by applying sulfate varies with irrigation mode: Dual effects of microbe-mediated arsenic transformation and iron plaque

Sulfate affects the transformation of arsenic (As) in soil and its absorption by plant roots. However, the influence of sulfate and irrigation interactions on the mobility of As in the soil-rice system remains poorly understood. To address this gap, we conducted a pot experiment with varying sulfate levels and irrigation modes to examine their effects on rice As translocation, soil As forms, iron plaque formation, and microorganisms involved in As transformation. The addition of exogenous sulfate significantly reduced grain As levels by a maximum of 60.1%, 46.7%, and 70.5% under flooding (F), flooding-moist alternate (FM), moist (M) conditions, respectively. However, the changes in soil available As did not fully correspond to grains As content. Soil available As was only reduced by sulfate under the FM treatment, which limited grains As accumulation under this condition. The reduction in grains As content under F and M conditions was mainly attributed to sulfate-induced increases in soil pH, which in turn inhibited As translocation and promoted iron plaque formation. Additionally, both irrigation mode and sulfate fertilization independently or interactively influenced the abundance of Sulfuritalea, Koribacter, Geobacter, and Sulfuriferula, thereby affecting the As forms in soil through the Fe/S redox process. Specifically, under F and FM conditions, SO42–-S inhibited Geobacter but stimulated Fe-oxidizing bacteria, possibly resulting in increased As bound to Fe/Mn oxides (As–F3). Under M condition, SO42–-S levels regulated As adsorption and release through the participation of Fe/S cycle bacteria, specifically influencing the adsorbed As fraction (As–F2). Therefore, the addition of SO42–-S hindered As translocation to grains by promoting As sequestration in the iron plaque and facilitating microbe-mediated As immobilization through the Fe/S cycle, which was dependent on soil moisture. These results can be used as a guide for sulfur fertilizer application under different soil moisture with the goal of minimizing rice grain As.

Enhancing rice quality and productivity: Multifunctional biochar for arsenic, cadmium, and bacterial control in paddy soil

The perilousness of arsenic and cadmium (As–Cd) toxicity in water and soil presents a substantial hazard to the ecosystem and human well-being. Additionally, this metal (loids) (MLs) can have a deleterious effect on rice quality and yield, owing to the existence of toxic stress. In response to the pressing concern of reducing the MLs accumulation in rice grain, this study has prepared magnesium-manganese-modified corn-stover biochar (MMCB), magnesium-manganese-modified eggshell char (MMEB), and a combination of both (MMCEB). To test the effectiveness of these amendments, several pot trials were conducted, utilizing 1% and 2% application rates. The research discovered that the MMEB followed by MMCEB treatment at a 2% rate yielded the most significant paddy and rice quality, compared to the untreated control (CON) and MMCB. MMEB and MMCEB also extensively decreased the MLs content in the grain than CON, thereby demonstrating the potential to enrich food security and human healthiness. In addition, MMEB and MMCEB augmented the microbial community configuration in the paddy soil, including As–Cd detoxifying bacteria, and decreased bioavailable form of the MLs in the soil compared to the CON. The amendments also augmented Fe/Mn-plaque which captured a considerable quantity of As–Cd in comparison to the CON. In conclusion, the utilization of multifunctional biochar, such as MMEB and MMCEB, is an encouraging approach to diminish MLs aggregation in rice grain and increase rice yield for the reparation of paddy soils via transforming microbiota especially enhancing As–Cd detoxifying taxa, thereby improving agroecology, food security, and human and animal health.

Arsenic fractionation and speciation in different textured soils supplied with farmyard manure and accumulation by sunflower under alkaline calcareous conditions.

Arsenic (As) is a naturally occurring element that is found in soil, water, and rocks. However, it can also be released into the environment through human activities. Arsenic is considered an environmental hazard because it is toxic to humans and animals and can cause serious health problems. Additionally, As-contaminated soil can limit plant growth and reduce crop yields, leading to economic losses for farmers. So, decreasing metal/metalloid solubility in soil by synthetic and organic amendments leads to better crop productivity on contaminated soils. The current study aimed to evaluate farmyard manure (FYM)-mediated changes in soil arsenic (As) behavior, and subsequent effects on achene yield of sunflower. Treatment plan comprised of two As levels, i.e., As-60 (60 mg kg-1) and As-120 (120 mg kg-1), four FYM levels (0, 20, 35, and 50 g kg-1), three textural types (sandy, loamy and clayey), and replicated thrice. Seven As fractions including water soluble-As (WS-As), labile-As (L-As), calcium-bound As (Ca-As), aluminum-bound As (Al-As), iron-bound As (Fe-As), organic-matter-bound As (OM-As), and residual-As (R-As) were determined which differed significantly (P ≤ 0.05) with FYM and soil texture. FYM supplementation decreased WS-As, L-As, Ca-As, and Al-As while increased Fe-As, OM-As, and R-As. The immobilizing effect of FYM increased with increasing its rate of application, and maximum effect was found in clayey soil. As speciation in soil also significantly (P ≤ 0.05) affected by FYM and soil texture, with a reduction in arsenate while increase in arsenite, mono-methyl arsenate, and di-methyl arsenate with increasing the rate of FYM supplementation. Bioaccumulation factor reduced with FYM addition, and highest reduction of 38.65 and 42.13% in sandy, 34.24 and 36.26% in loamy while 29.16 and 35.10% in clayey soils at As-60 and As-120, respectively, by 50 g kg-1 FYM compared with respective As treatments without FYM. As accumulation in plant parts was significantly (P ≤ 0.05) reduced by FYM with the subsequent improvement in achene yield.

Growth responses of genetically diverse rice (<em>Oryza sativa</em> L.) cultivars to Arsenic stress

Although arsenic (As) is a toxic element for plant growth, it can accumulate in rice plants to higher levels. A case-control experiment was carried out to investigate the impact of As in soil on rice plant growth. Nine (9) different native and improved rice cultivars were grown in soils with 10 mg/kg As. Total As content in grains was quantified using an ICP-MS. The mean As content in control samples was 15.8 µg/kg while As treatment samples showed 122 µg/kg. Grains of improved rice variety of Bg 300 showed the highest As accumulation. The chlorophyll content declined by 28% under As stress and 56% tiller losses were also observed. The significant reduction of plant growth has given an impaired grain yield under As-treated conditions. Soil arsenic also showed a significant impact on Ni, Rb, and Ba uptake and accumulation. This study showed that As accumulation in rice is cultivar-dependent and also indicated a drastic reduction of the yield under elevated As levels. The native cultivar, Kahawanu was shown the lowest As-accumulation (90.1 mg/kg) under elevated As within the nine rice cultivars. So it can be identified as the best resistance cultivar for the As stress. The results can be utilized for developing high-tolerance rice varieties using new breeding technologies.

Risk assessment of potentially toxic elements in agricultural soils and bioconcentration in rice grains from Faridkot District, India

Potentially toxic elements (PTEs) in soil pose significant risks to both ecology and human health. Therefore, to understand the effect of PTEs in agricultural soils of Faridkot District, Punjab, India, 36 soil samples were analyzed for physicochemical properties, contents of PTEs (aluminum, arsenic, nickel, boron, uranium, barium, chromium, cadmium, copper, iron, lead, cobalt, manganese, selenium, and zinc), possible ecological and human health risks and bioconcentration in rice grains. Soils showed high mean contents (mg/kg) of potassium (906.65), sodium (760.78), and chlorides (247.13) with cadmium, copper, zinc, arsenic, and selenium contents (mg/kg) in 55.56%, 33.33%, 25.00%, 16.67%, and 13.89% of samples exceeding their safe limits (0.06, 20.00, 50.00, 20.00, and 0.20, respectively). Individual and multi-element indices suggested extremely high-soil enrichment of arsenic, cadmium, and selenium and low to moderate ecological risk. Multivariate analyses revealed the contribution of both geogenic and anthropogenic activities to soil contamination. Mean bioconcentration factors of chromium (4.48), boron (1.24), and copper (2.69) were >1.00 in rice. Residents had higher cancer risk (TCR) due to arsenic (3.64E-05) and chromium (4.04E-06) in soil, mainly through ingestion and dermal contact. This work could serve as baseline database for further research and designing the strategy to alleviate soil contamination.

Evaluation of soil arsenic pollution and phytoaccumulation capabilities of 24 indigenous plant species in Barak Valley, South Assam, India

AbstractThis study investigated the concentrations of arsenic (As) in soil and plant biomass from the Barak Valley in South Assam, India. Soil samples showed concentrations ranging from 6.06 ± 0.84 mg/kg to 18.61 ± 1.52 mg/kg, with an average of 10.60 ± 3.15 mg/kg, 41.67% of the sample exceeding uncontaminated ranges (0.1–10 mg/kg). Ecological risk assessments such as contamination factors, pollutant load index, geo‐accumulation index, and anthropogenicity identified varying contamination levels across sampling points. A total of 24 plant species were collected, ferns (two species), shrubs (five species), grass (six species), and herb (11 species). The concentration of As in different plants types decreased in the order of fern (393.45 ± 159.63 mg/kg) > shrub (20.48 ± 7.25 mg/kg) > herb (17.92 ± 13.75 mg/kg) > grass (14.98 ± 13.80 mg/kg). Plant species, namely Pityrogramma calomelanos, Christella dentata, Mimosa pudica, Chromolaena odorata, Leucas aspera, Persicaria decipiens, Melastoma malabathricum, and Clerodendrum infortunatum, accumulated higher concentrations of As in their above‐ground parts compared to roots and were categorized as tolerant accumulators (TF > 1). By incorporating these plant species into phytoextraction strategies, the region can benefit from their unique properties and abilities to effectively remediate arsenic‐contaminated sites, ultimately improving the affected areas' environmental and human health conditions.

Comparative Studies on Spectrophotometric Determination of Selected Heavy Metals in Environmental and Biological Samples with Synthetic Phenylhydrazones as Chromogenic Reagents

This work involves a comparative study on a simple, sensitive, selective and non-extractive Uv- Vis spectrophotometric method for the determination of cadmium, lead, chromium and arsenic in biological, soil and water samples using synthesized and characterized phenylhydrazones; [glutaraldehyde phenylhydrazone (GPH) and acetylpyridine-2,4-dinitrophenylhydrazone (APDH)] as the chromogenic reagents was developed. GPH and APDH were synthesized as new chromogenic analytical reagents for the direct UV-Vis spectrophotometric determination of the selected metals of interest in a slightly acidic pH of 6.5-7.5 and 20% dimethylformamide (DMF) solution to give stable coloured metal-ligand complexes. The reactions were instantaneous; the wavelengths of maximum absorptions were followed spctrophometrically and noted. The analytical properties of the reagent APGH on the metals (Cd, As, Pb, and Cr) revealed the wavelength of maximum absorption ranged between 385.0 (Cr) to 440.0nm for (Pb). The reagent APDH had molar absorptivities (L mol -1 cm -1 ) ranging from 2.006 x 10 4 (Pb) to 2.407 x 10 4 (Cd), a mole ratio of metal to ligand of 1:1, a detection limit (µg/g) ranging from 0.3272 (As) to 0.4456 (Cd) and the metal-ligand complex was stable for 0-36 hours. The reagent GPH revealed a wavelength of maximum absorption between 360.0 (Cr) to 395.0 nm for (Pb and As) at a working pH of 6.5 to 7.5 room temperature (37°C). The reagent GPH had a molar absorptivities (L mol -1 cm -1 ) ranging from 2.213 x 10 4 (Pb) to 2.460 x 10 4 (As), a mole ratio of metal to ligand of 2:1, the detection limit (µg/g) ranging from 0.3432 (As) to 0.5250 (Pb) and the metal-ligand complex was stable for 0-48 hours. Both reagents had a Beer’s law validity range (mgL -1 ) of 0.001 to 100. The Sandell’s sensitivities (µg/cm 2 ) ranged from 0000409 (As) to 0.00499 (Pb) for APDH and 0.00406 (As) to 0.00452 (Pb) respectively. Large excess of cations and anions as possible interferences up to 1

A Study on the Soil Passivation of Nano-Manganese Dioxide-Modified Biochar under High-Arsenic Water Irrigation

[Objective] The irrigation area in northern Henan is an important grain producing area in China. Native high arsenic groundwater exists in the area and has long been used for agricultural irrigation. Increased soil arsenic (As) content under long-term irrigation threatens the quality and safety of crop products. Soil passivation is the use of adding passivators to the soil to fix pollutants to achieve the purpose of limiting their migration. Therefore, the preparation of an efficient and clean passivator and its arsenic fixation effect in soil are important research areas to reduce the risk of high arsenic groundwater. [Method] Firstly, nano-manganese dioxide (MnO2)-modified biochar was prepared via the pyrolysis of sawdust biochar, potassium permanganate and manganese sulfate monohydrate at a mass ratio of 1:0.18:0.29. Secondly, the adsorption characteristics were explored using adsorption kinetics and adsorption isothermal experiments. Scanning electron microscopy (SEM), X-ray powder diffraction (XRD) feature mapping and other characterization methods were used to study its physical properties and adsorption mechanism. Finally, a potting experiment was designed to explore the changes in arsenic content in soil when the passivator dosages were 0%, 1% and 5%. [Results] (1) The nano-MnO2 modified biochar could reach the adsorption dynamic equilibrium after 180 min, and its maximum adsorption capacity was 58.12 μg/g. (2) When the dosing ratio was 1%, the fixed efficiency of soil effective As content in potted crops of unplanted crops and planted crops was 4.18–5.51% and 1.99–3.83%. When the dosing ratio was 5%, it was 7.48–8.75% and 5.58–9.58%. [Conclusions] The results show that when the addition ratio is 0–5%, the passivation effect of soil effective As is positively correlated with the passivator dosage.

Application of Fe3[KG-*2/5]O4/Mulberry Stem Biochar Effects on Soil Arsenic Species and Rice Arsenic Content

The passivation effect of Fe3O4/mulberry pole biochar (Fe-MBC) prepared at different carbonization temperatures on soil available arsenic content was studied through soil culture experiments, and Fe-MBC-800 (prepared by carbonization at 800℃) with good passivation effect was selected and characterized. The effects of 1%-7% (mass fraction of biochar to soil) Fe-MBC-800, MBC-800, and Fe3O4 on soil pH value, soil electrical conductivity, soil arsenic form, rice biomass, and total arsenic (As) content in rice were studied using a pot experiment. The results showed that:①Fe-MBC-800 successfully loaded Fe3O4, and its main functional groups were C=O double bond, O-H bond, C-O bond, and Fe-O bond. The specific surface areas of Fe-MBC-800, MBC-800, and Fe3O4 were 209.659 m2·g-1, 517.714 m2·g-1, and 68.025 m2·g-1, respectively. ②The addition of Fe-MBC-800 could increase the soil pH value, decrease the soil EC value, increase the content of residual arsenic in soil, and reduce the content of water-soluble arsenic and available arsenic in the soil. Under the treatment using 7% Fe-MBC-800 (ω) amendments, the content of water-soluble arsenic and available arsenic in the soil decreased by 81.6% and 56.33%, respectively. ③When the addition ratio of Fe-MBC-800 in the soil was 5%-7%, it could promote the growth of rice plants, increase rice biomass, and reduce the bioaccumulation of arsenic by between 62.5% and 68.75%.

Environmental bioavailability of arsenic, nickel and chromium in soils impacted by high geogenic and anthropogenic background contents

High arsenic, chromium and nickel in soils can pose a hazard to the ecosystem and/or human health. Large areas can be affected by elevated potentially toxic elements (PTE) background contents, entailing a significant effort for managing the potential risk. Assessing the environmental hazard associated to PTE-contaminated soils requires the determination of soil PTE environmental bioavailability, which reflects the capacity of these elements to be transferred to living organisms. Here we assess the environmental bioavailability of As, Cr and Ni in topsoils from the Liège basin and Belgian Lorraine, two areas in Wallonia, Belgium, affected by elevated As, Cr and Ni background contents. The source of soil As, Cr and Ni differs in Liège and Lorraine: anthropogenic in the former location and geogenic in the latter. The environmental bioavailability of PTE was determined using two complementary approaches: (1) by chemical fractionation with the Community Bureau of Reference (BCR) three-step sequential extraction protocol and (2) by estimating the phytoavailability using a plant-based biotest (Lolium multiflorum as plant model). The results show that total As (6–130 mg·kg−1), Cr (15–268 mg·kg−1), and Ni (8–140 mg·kg−1) contents in the Liège and Lorraine soils frequently exceed the soil clean-up standards. However, no positive correlation was found between the total contents and BCR extraction results or rye-grass contents, except for As in Liège soils. Total As, Cr or Ni contents surpassing soil standards do not necessarily result in elevated mobile, potentially mobilizable and phytoavailable contents. In general, environmental bioavailability of As, Cr and Ni is higher in soils from Liège basin compared to those sampled in Belgian Lorraine. The mobile and potentially mobilizable fractions of As, Cr and Ni account for <30 % of their total contents following the BCR extractions. Our study provides valuable information for sustainable management at the regional scale of soils containing high PTE contents.

Inoculation with Glomus mosseae: An Efficient Biological Management Strategy for Arsenic Mitigation in Wheat (Triticum Aestivum L.) Under Arsenic-Contaminated Soil

ABSTRACT A pot experiment was conducted to evaluate the effects of Arbuscular Mycorrhizal (AM) fungi on mitigation of arsenic (As) in As-contaminated soils with wheat (variety – HD 2967) as the test crop. Soil inbulk was collected from Bihar Agricultural University, Sabour, Bihar,India farm with physicochemicalproperties to conduct a pot experiment using three doses of As (5, 10, 20 mg L−1) and application of Glomus mossaea inoculation (no inoculated, 5 g/pot, and 10 g/pot). Result indicated that the treatment spiked with As 5 ppm and Glomus mossaea @1 g kg−1 showedthe lowest available As (21.80 µg kg−1 soil) and lowest total As (2.533 mg kg−1soil) as compared to all othertreatments. The As content in different parts of plants are found in the orderof roots > shoots> leaves > grain parts in wheat crop. As uptake in grain was found to be positively correlated with available (r = 0.883, p < .001) and total As content in soil (r = 0.869, p < .001) as well. The application of AM fungi @10.0 g kg−1 soil significantly (p < .005) reduced the As content in grain under all the applied treatments. As content ingrain was found to be negatively correlated with total glomalin content of soil(r = –0.430, p < .005), colonization by AM fungi (r = –0.261) and available phosphorus (P) content of soil (r = –0.864, p < .001). The study noticeably indicated that the mycorrhizal inoculation can reduce the As content in the various parts of the wheat in As-contaminated soils.

Arsenic Levels in Soil and Rice and Health Risk Assessment via Rice Consumption in Industrial Areas of East Java, Indonesia

Industrial use of arsenic can potentially cause environmental problems in water, soil, and air. Arsenic is one of heavy metals that is highly toxic and carcinogenic. Arsenic contamination in the environment is harmful to human health because it can enter the body through the food chain. This study determined the concentration of arsenic in soil and rice and its impact on human health risks. Sampling was carried out in several East Java industrial cities or districts, for instance, Gresik, Mojokerto, Sidoarjo, Nganjuk, Ponorogo, and Surabaya. The measurement of arsenic in soil was done using Energy Dispersive X-Ray fluorescence (EDXRF), while the measurement of arsenic in rice was done by Total X-Ray Fluorescence (TXRF). The results showed that arsenic concentration in several areas of East Java has varying levels. The concentration of arsenic in soil was highest in Gresik (13,786 mg/kg). The highest arsenic concentration in rice was found in Mojokerto (0.154 mg/kg). The results of risk assessment in this study showed that the Hazard Quotient (HQ) value was &gt;1 and the Excess Cancer Risk (ECR) was &gt;10-4 in all areas at the age of children &lt;2 years. Health risk assessment of adults showed HQ&gt;1 and ECR&gt;10-4 in several areas of East Java. This indicates that consumption of rice contaminated with arsenic has the potential to pose non-carcinogenic and carcinogenic health risks.