Arsenic-phosphorus interactions in the soil-plant-microbe system: Dynamics of uptake, suppression and toxicity to plants

γ-aminobutyric acid (GABA) supplementation modulates phosphorus retention, production of carbon metabolites and defense metabolism under arsenic toxicity in wheat

Arsenic (As) stress has been incessantly degrading crop productivity, and thereafter leading to the increasing grave conditions pertaining to the unsustainable food production. In plants, As stress has been considered as one of the serious phytotoxins persisting in the environment, endangering crop shelf life through competing with phosphorus availability. The withholding of As in the staple crop, wheat (Triticum aestivum), is the major concern. It has been advocated the significance of plant signaling molecules, γ-aminobutyric acid (GABA), in mediating plant health response to environmental stresses, but their impacts on As contamination in wheat plants from the perspective of growth and physiological tolerance still remain ambiguous at present. The present study investigated the significance of GABA supplementation in wheat plants on phosphorus and carbon metabolisms, adenosine triphosphatase (ATPase) activity, As accumulation, defense systems, and growth responses under As stress. In this study, GABA supplementation aided in the retention of phosphorus and carbon metabolites, sustained photosynthetic traits, and considerably modulated both chloroplastic and mitochondrial ATPase activity under As stress. Further, As-induced oxidative stress injuries were recovered through the activation of defense metabolites, and suppressed oxidative stress markers and As accumulation, which was found concomitant with the improved As tolerance index. Thus, this investigation offers insightful information that might be useful in future investigations to develop wheat tolerance to withstand under As-contaminated environments.

Arsenic contamination in rice: a DPSIR analysis with a focus on top rice producers

Arsenic contamination in rice poses significant risks to public health and food security. While previous reviews have examined specific aspects of this issue, they often lack a comprehensive analysis linking human activities to arsenic contamination and its broader consequences. This review applies the DPSIR (Driving Forces-Pressures-States-Impacts-Responses) framework to elucidate the cause-and-effect relationships of arsenic contamination in rice, with a focus on top rice producers. It also synthesizes current knowledge on the environmental sources, fate, and transport of arsenic across different environmental compartments, illustrating its movement from emission sources to accumulation in rice while highlighting the complex interplay between environmental conditions, rice varieties, and contamination levels. The DPSIR analysis revealed that socioeconomic factors, including population growth and industrialization, were the primary driving forces behind arsenic contamination in rice. These factors increased pressures such as reliance on arsenic-contaminated irrigation water, historical pesticide use, and industrial pollution, which contributed to arsenic accumulation in rice-growing environments. Consequently, the soil, water, and rice were contaminated with arsenic at various levels, posing serious risks to human health. The impacts extend beyond health concerns to disruptions in global rice trade and threats to food security. In response, various mitigation strategies have been implemented, including regulation, sustainable agricultural practices, water and soil remediation, and public guidance. However, challenges persist, requiring an integrated approach that incorporates scientific advancements, policy interventions, and improved agricultural techniques. Key research priorities include developing arsenic-resistant rice varieties, assessing health risks for vulnerable populations, quantifying economic losses, and determining arsenic-related foodborne diseases burden.

Co-occurrence of arsenic and sewage pollutants in surface and groundwater and its implications for water treatment using membrane technology

Arsenic (As) enrichment in groundwater stems from natural and hydrogeochemical factors, leading to geological contamination. Groundwater and surface water are interconnected, allowing As migration and surface water contamination. The As contamination poses health risks through contaminated water consumption. Sewage discharge in rich-As water bodies alters environmental conditions, increasing the concentration of organic matter, carbonate and bicarbonate, nitrite, sulfate, and phosphate in water. These changes could enhance As solubilization and release to water. This review investigates the interactions between these contaminants, and their implications for membrane-based water treatment processes. Organic pollutants in surface water promote microbial growth, depleting oxygen and altering redox conditions, which enhances As solubilization and concentration in the water. The interaction between organic pollutants and As primarily occurs through adsorption and complexation, influenced by the pollutants' functional groups and the water's pH. Bicarbonates and pH play critical roles in determining As speciation (As(V) or As(III)), while oxidants like nitrate increase As mobility by promoting its oxidation. When arsenic is primarily present as As(V), membrane-based removal processes tend to be more efficient. Sulfur also affects As dynamics through microbial processes and adsorption onto sulfide minerals. When nitrate and sulfate are present, Donnan exclusion becomes a critical mechanism that affects arsenic removal by NF and RO membranes. Although membrane technologies maintain high As rejection rates (97-99 %), even in the presence of sewage pollutants, this advantage is offset by the challenges of fouling and the generation of highly concentrated waste streams. So, it is urgent to avoid raw or not adequately treated sewage in As-rich environments.

Utilizing NPKS fertilizer for the enhancement of Pennisetum purpureum growth and phytoremediation of arsenic in treatment wetland

Phytoremediation of arsenic in constructed wetlands (CWs) is becoming the most efficient, eco-friendly, and sustainable technology worldwide. This research aimed to explore the impact of utilizing NPKS fertilizer on the enrichment of Pennisetum purpureum growth and phytoremediation of arsenic in CWs. The study comprised control and 2 phytoremediation treatments with P. purpureum plants: 39 mg kg-1 As alone and the application of 0.04% NPKS fertilizer with 39 mg kg-1 As. This experiment was carried out in CWs for 42 days. Bioavailable and total As were determined by ICP-OES. P. purpureum developed effectively in the phytoremediation treatment with 0.04% NPKS fertilizer application till the end of the experiment. The arsenic phytoremediation treatment with 0.04% NPKS fertilizer removed 72.54% bioavailable arsenic, 72.52% total arsenic, and 0.05% arsenic in the leachate of CWs. The fresh weight of P. purpureum rose considerably when treated with 0.04% NPKS fertilizer in comparison to the arsenic-alone treatment. The maximum efficiency of arsenic absorption at 42 days attained 5041.7 ± 120.4 mg kg-1 DW in the phytoremediation treatment with 0.04% NPKS fertilizer application. These results suggest that phytoremediation treatments with 0.04% NPKS fertilizer can be used in As phytoremediation in anthropogenically polluted environments due to its high capability to uptake As.

Arsenic, cadmium, and chromium concentrations in contrasting phosphate fertilizers and their bioaccumulation by crops: Towards a green label?

Potentially toxic elements such as arsenic (As), cadmium (Cd), and chromium (Cr) are severely regulated in fertilizers and deserve continuous investigation. Phosphate-derived Cd has been a stepping-stone toward achieving sustainable and safe worldwide food production, especially after a new regulation aiming for reduced limits of Cd in P fertilizers (EU, 2019/1009). Three pot experiments were conducted to assess the variability of As, Cd, and Cr concentrations - with a particular focus on Cd - from monoammonium phosphates (MAP 1, MAP 2, and MAP 3 from different geographic origins) and their accumulation in limed and unlimed soils, and contrasting crops, representing staple food and significant sources of these elements for humans (i.e., potato, tobacco, and rice). A diverse array of sensitive techniques for trace elements determination were used to reveal the highest level of Cd of MAP 3 (20.71 mg kg-1 MAP), which loaded the highest amounts of this element to the soil matrix and solution, plant shoots, and xylem sap, contrasting with results for MAP 1 (0.87 mg kg-1 MAP), which has almost ten times less Cd than that required for low-Cd labeling of P fertilizers (≤20 mg Cd kg-1 P2O5). MAP 3 also had the highest Cr concentration (139.3 mg kg-1 MAP). Among crops, rice accumulated 16-fold less Cd than potato plants. Liming decreased Cd in tobacco and potato shoots up to 35%. Moreover, reductions of about 20% were also observed for Cd accumulation in tubers and sap. Conversely, Cd from MAP 3 was always much more accumulated in soil solution, achieving up to 20 μg L-1, while values < 5 μg L-1 (i.e., a groundwater limit) were obtained from MAP 1. Our findings may be used as a reference in developing green labels for fertilizers in scenarios where Cd accumulation represents a potential risk for soil and human health.

Impact of two arbuscular mycorrhizal fungi species on arsenic tolerance and accumulation in safflower (Carthamus tinctorius L.)

BACKGROUND

Arbuscular mycorrhizal fungi (AMF) can regulate metal(loid) tolerance in plants and their capacity for phytoremediation. These effects can vary depending on the host plant and the AMF species. The impact of different AMF species on the ability of safflower (Carthamus tinctorius L.) for arsenic (As) phytoremediation is still largely unknown. Therefore, this study aimed to assess the effect of two AMF species, Rhizophagus irregularis, and Funneliformis mosseae, on the tolerance and accumulation of As in safflower in soils spiked with varying arsenate concentrations (0, 25, 50, and 100 mg kg-1).

RESULTS

The results indicated that both AMF species established effective symbiotic relationships with safflower. However, plants inoculated with R. irregularis exhibited higher mycorrhizal dependency and root colonization, especially under 100 mg kg-1 As. Both AMF species significantly improved plant growth parameters, chlorophyll content, and phosphorus (P) nutrition, which resulted in increased P/As ratio and enhanced tolerance index in safflower plants. In addition, AMF inoculation reduced As-induced lipid peroxidation by enhancing catalase and peroxidase activity in leaves and roots. While the mycorrhizal symbiosis didn't affect As availability in soils, it significantly reduced shoot As concentration and the translocation factor under all As levels. Furthermore, mycorrhizal inoculation, especially with R. irregularis, increased As concentration and modified-bioconcentration factor in the roots and enhanced total As uptake per plant.

CONCLUSIONS

Based on the results and multivariate analyses, both AMF species, particularly R. irregularis, enhanced safflower's As tolerance by retaining As in roots, improving phosphorus nutrition, and increasing antioxidant enzyme activity, showcasing their potential to enhance phytostabilization in safflower plants.

Differential response of catalase to As (III) and As (V): Potential molecular mechanism under valence effect

Arsenic (As) is the most prolific contaminant in food, triggering arseniasis primarily via contaminated rice and drinking contaminated water. However, toxicological data for arsenite (As (III)) and arsenate (As (V)) on antioxidant enzyme catalase (CAT) at molecular level is shortage. The interaction mechanism of As (III) and As (V) with CAT was investigated using enzyme activity detection, multi-spectroscopic techniques, isothermal titration calorimetry and computational simulations. Results indicated As (III) and As (V) induced protein skeleton relaxation, secondary structure transformation, fluorescence sensitization and particle alteration of CAT, particularly As (III). Moreover, As (III)/As (V) bound to CAT through hydrogen bonding and hydrophobic. As (III) and As (V) contacted with core residues His 74, Asn 147 and His A74, Trp A357, respectively, thereby inhibiting CAT activity. Overall, As (III) is more aggressive against the structure and physiological function of CAT than As (V). Our findings enhance the understanding of health risk related to dietary As exposure.

Quantifying the impact of factors on soil available arsenic using machine learning

Arsenic (As) can accumulate in edible plant parts and thus pose a serious threat to human health. Identifying the contributions of various factors to soil available As is crucial for evaluating environmental risks. However, research quantitatively assessing the importance of soil properties on available As is scarce. In this study, we utilized 442 datasets covering total As, available As, and properties of farmland soils. The five machine learning models were employed to predict soil available As content, and the model with the best predictive performance was selected to calculate the importance of soil properties on available As and interpret the model results. The Random Forest model exhibited the best predictive performance, with R2 for the test set of dryland and paddy fields being 0.83 and 0.82 respectively, while also outperforming other machine learning models in terms of accuracy. Concurrently, evaluating the contribution of soil properties to soil available As revealed that increases in soil total arsenic, pH, organic matter (OM), and cation exchange capacity (CEC) led to higher soil available As content. Among these factors, soil total As had the greatest impact, followed by CEC. The influence of pH on soil available As was greater in dryland compared to OM, while in paddy fields, it was smaller than OM (p < 0.01). Sensitivity analysis results indicated that reducing soil total As content had the greatest effect on available As. In both dryland and paddy field soils, reducing soil total As had the most pronounced effect on available As, leading to reductions of 10.09% and 8.48%, respectively. Therefore, prioritizing the regulation of soil total As and CEC is crucial in As contamination management practices to alter As availability in farmland soils.

Impact of abiotic stressors on nutrient removal and rhizomicrobiome composition in floating treatment wetland with Equisetum hyemale

Floating treatment wetlands (FTW) are receiving growing interest as a phyto-technology. However, there are significant research gaps regarding the actual role of plant species and plant-microbiome interactions. In this study, the nutrient uptake of Equisetum hyemale was examined in FTW microcosms under the influence of abiotic stressors: As (3 mg/L) and Pb (3 mg/L) as well as Cl- (300 and 800 mg/L) in reference to a control during a short screening experiment. High removal efficiency of nutrients in water solutions, up to 88 % for TN and 93 % for PO4-P, was observed. However, PO4-P removal was inhibited in the As reactor, with a maximum efficiency of only 11 %. Lead and As were removed with high efficiency, reaching 98 % and 79 % respectively. At the same time only Pb was effectively bound to root biomass, reaching up to 51 %. Limited As accumulation of 0.5 % in plant roots suggests that microbial processes play a major role in its reduction. The development and structure of microbiome in the microcosms was analysed by means of 16S rRNA gene amplicon sequencing, proving that Pb was the most influential factor in terms of selection pressure on specified bacterial groups. In the As treatment, the emergence of a Serratia subpopulation was observed, while the Cl- treatment preserved a rhizobiome composition most closely resembling the control. This study indicates that E. hyemale is a suitable species for use in FTWs treating Pb polluted water that at the same time is capable to withstand periodic increases in salinity. E. hyemale exhibits low As binding in biomass; however, extended exposure might amplify this effect because of the slow-acting, but beneficial, mechanism of As uptake by roots and shoots. Microbiome analysis complements insights into mechanisms of FTW performance and impact of stress factors on bacterial structure and functions.

Is Pyrolysis Treatment a Viable Solution to Detoxify Metal(loid)s in Sewage Sludge toward Land Application? Case Studies of Chromium and Zinc

Metal(loid)s in sewage sludge (SS) are effectively immobilized after pyrolysis. However, the bioavailability and fate of the immobilized metal(loid)s in SS-derived biochar (SSB) following land application remain largely unknown. Here, the speciation and bioavailability evolution of SSB-borne Cr and Zn in soil were systematically investigated by combining pot and field trials and X-ray absorption spectroscopy. Results showed that approximately 58% of Cr existing as Cr(III)-humic complex in SS were transformed into Fe (hydr)oxide-bound Cr(III), while nano-ZnS in SS was transformed into stable ZnS and ferrihydrite-bound species (accounting for over 90% of Zn in SSB) during pyrolysis. All immobilized metal(loid)s, including Cr and Zn, in SSB tended to be slowly remobilized during aging in soil. This study highlighted that SSB acted as a dual role of source and sink of metal(loid)s in soil and posed potential risks by serving a greater role of a metal(loid) source than a sink when applied to uncontaminated soils. Nevertheless, SSB could impede the translocation of metal(loid)s from soil to crop compared to SS, where coexisting elements, including Fe, P, and Zn, played critical roles. These findings provide new insights for understanding the fate of SSB-borne metal(loid)s in soil and assessing the viability of pyrolyzing SS for land application.

Dominant role of soil iron and organic matters in arsenic transfer from soil to plant in a mine area in Hunan Province, Central China

The transfer of arsenic (As) from soil to plant could be significantly influenced by soil parameters through regulating soil As bioavailability. To distinguish the bioavailable As provided by soil and the As uptaken by plants, herein two different soil bioavailable were defined, namely potential soil bioavailable As (evaluated through the bioavailable fraction of As) and actual soil bioavailable As (assessed through plant bioaccumulation factor, BF, and BFavailable). To identify the dominant soil parameters for the two soil bioavailable As forms, soil and plant samples were collected from a former As mine site. The results showed that the potential bioavailable As only accounted for 1.77 to 11.43% in the sampled soils, while the BF and BFavailable in the sampled vegetables ranged from 0.00 to 1.01 and 0.01 to 17.87, respectively. Despite a similar proportion of As in the residual fraction, soil with higher pH and organic matter (OM) content and lower iron (Fe) content showed a higher potential soil bioavailable As. Correlation analysis indicated a relationship between the soil pH and potential soil bioavailable As (r = 0.543, p < 0.01) and between the soil Fe and actual soil bioavailable As (r =  - 0.644, p < 0.05, r =  - 0.594, p < 0.05). Stepwise multiple linear regression (SMLR) analysis was employed to identify the dominant soil parameters and showed that soil pH and phosphorus (P) content could be used to predict the potential soil bioavailable As (R2 = 0.69, p < 0.001). On the other hand, soil Fe and OM could be used to predict the actual soil bioavailable As (R2 = 0.18-0.86, p < 0.001-0.015, in different vegetables). These results suggest that different soil parameters affect potential and actual soil bioavailable As. Hence, soil Fe and OM are the most important parameters controlling As transfer from soil to plant in the investigated area.

Effectiveness of nanomaterials and their counterparts in improving rice growth and yield under arsenic contamination

Arsenic (As) pollution in rice (Oryza sativa L.), a staple food for over 3.5 billion people, is a global problem. Mixed effects of Zn, Cu, and Si amendments on plant growth and yield, including in the presence of As pollution have been reported in previous studies. To better investigate the effectiveness of these amendments on rice growth, yield, and As accumulation, we conducted a rice greenhouse experiment with 11 treatments, including control pots with and without As contamination and pots with amendments of ZnO, CuO, and SiO2 nanoparticles (ZnO NPs, CuO NPs, and SiO2 NPs), their ionic counterparts (ZnSO4, CuSO4, and Na2SiO3), and bulk particles (ZnO BPs, CuO BPs, and SiO2 BPs). Compared with the background soil, the treatment of adding As decreased rice plant height, panicle number, and grain yield by 16.5%, 50%, and 85.7%, respectively, but significantly increased the As accumulation in milled rice grains by 3.2 times. Under As contamination, the application of Zn amendments increased rice grain yield by 4.6-7.3 times; among the three Zn amendments, ZnSO4 performed best by fully recovering grain yield to the background level and significantly reducing grain AsIII/total As ratio by 46.9%. Under As contamination, the application of Cu amendments increased grain yield by 3.8-5.6 times; all three Cu amendments significantly reduced grain AsIII/total As ratio by 20.2-65.6%. The results reveal that Zn and Cu amendments could promote rice yield and prevent As accumulation in rice grains under As contamination. Despite the observed reduction in As toxicity by the tested NPs, they do not offer more advantages over their ionic counterparts and bulk particles in promoting rice growth under As contamination. Future field research using a broader range of rice varieties, investigating various As concentrations, and encompassing diverse climate conditions will be necessary to validate our findings in achieving more extensive understanding of effective management of arsenic contaminated rice field.

Alendronate-Functionalized Graphene Quantum Dots as an Effective Fluorescent Sensing Platform for Arsenic Ion Detection

Alendronate-functionalized graphene quantum dots (ALEN-GQDs) with a quantum yield of 57% were synthesized via a two-step route: preparation of graphene quantum dots (GQDs) by pyrolysis method using citric acid as the carbon source and post functionalization of GQDs via a hydrothermal method with alendronate sodium. After careful characterization of the obtained ALEN-GQDs, they were successfully employed as sensing materials with superior selectivity and sensitivity for the detection of nanomolar levels of arsenic ions (As(III)). According to the mechanistic investigation, arsenic ions can quench the fluorescence intensity of ALEN-GQDs through metal-ligand interaction between the As(III) ions and the surface functional groups of the fluorescent probe. This probe provided a rapid method to monitor As(III) with a wide detection range (44 nM-1.30 µM) and a low detection limit of 13 nM. Finally, to validate the applicability, this novel fluorescent probe was successfully applied for the quantitative determination of As(III) in rice and water samples.

Effects of arbuscular mycorrhizal fungi on the reduction of arsenic accumulation in plants: a meta-analysis

Arsenic (As) accumulation in plants is a global concern. Although the application of arbuscular mycorrhizal fungi (AMF) has been suggested as a potential solution to decrease As concentration in plants, there is currently a gap in a comprehensive, quantitative assessment of the abiotic and biotic factors influencing As accumulation. A meta-analysis was performed to quantitatively investigate the findings of 76 publications on the impacts of AMF, plant properties, and soil on As accumulation in plants. Results showed a significant dose-dependent As reduction with higher mycorrhizal infection rates, leading to a 19.3% decrease in As concentration. AMF reduced As(V) by 19.4% but increased dimethylarsenic acid (DMA) by 50.8%. AMF significantly decreased grain As concentration by 34.1%. AMF also improved plant P concentration and dry biomass by 33.0% and 62.0%, respectively. The most significant reducing effects of As on AMF properties were seen in single inoculation and experiments with intermediate durations. Additionally, the benefits of AMF were significantly enhanced when soil texture, soil organic carbon (SOC), pH level, Olsen-P, and DTPA-As were sandy soil, 0.8%-1.5%, ≥7.5, ≥9.1 mg/kg, and 30-60 mg/kg, respectively. AMF increased easily extractable glomalin-related soil protein (EE-GRSP) and total glomalin-related soil protein (T-GRSP) by 23.0% and 28.0%, respectively. Overall, the investigated factors had significant implications in developing AMF-based methods for alleviating the negative effects of As stress on plants.

Sustainable water management in rice cultivation reduces arsenic contamination, increases productivity, microbial molecular response, and profitability

Arsenic (As) and silicon (Si) are two structurally competitive natural elements where Si minimises As accumulation in rice plants, and based on this two-year field trial, the study proposes adopting alternating wetting and drying (AWD) irrigation as a sustainable water management strategy allowing greater Si availability. This field-based project is the first report on AWD's impact on As-Si distribution in fluvio-alluvial soils of the entire Ganga valley (24 study sites, six divisions), seasonal variance (pre-monsoon and monsoon), rice plant anatomy and productivity, soil microbial diversity, microbial gene ontology profiling and associated metabolic pathways. Under AWD to flooded and pre-monsoon to monsoon cultivations, respectively, greater Si availability was achieved and As-bioavailability was reduced by 8.7 ± 0.01-9.2 ± 0.02% and 25.7 ± 0.09-26.1 ± 0.01%. In the pre-monsoon and monsoon seasons, the physiological betterment of rice plants led to the high rice grain yield under AWD improved by 8.4 ± 0.07% and 10.0 ± 0.07%, proving the economic profitability. Compared to waterlogging, AWD evidences as an optimal soil condition for supporting soil microbial communities in rice fields, allowing diverse metabolic activities, including As-resistance, and active expression of As-responsive genes and gene products. Greater expressions of gene ontological terms and complex biochemical networking related to As metabolism under AWD proved better cellular, genetic and environmental responsiveness in microbial communities. Finally, by implementing AWD, groundwater usage can be reduced, lowering the cost of pumping and field management and generating an economic profit for farmers. These combined assessments prove the acceptability of AWD for the establishment of multiple sustainable development goals (SDGs).

Influence of biochar on the arsenic phytoextraction potential of Pteris vittata in soils from an abandoned arsenic mining site

Biochar (BC) has a strong potential for activating arsenic (As) in soil; thus, the phytoremediation efficiency of As-polluted soils is enhanced with Pteris vittata L. A pot experiment was conducted to investigate the potential of BC to assist in phytoremediation with P. vittata. The effects of BC on physicochemical properties, available As, enzyme activities, and the bacterial community in the rhizosphere soil were investigated, and the biomass, physiology, and As uptake of P. vittata were analyzed. The results indicated that applying BC facilitated available As in the P. vittata rhizosphere soil, and the phytoremediation efficiency percentage increased in the As-polluted soils, such as 3.80% and 8.01% under the 2% and 5% BC treatments compared to the control, respectively. Phytoremediation with P. vittata and BC significantly improved soil organic matter content, available N, P, and K, enzyme activities, and the bacterial community. BC promoted Streptomyces (26.6-54.2%) and Sphingomonas (12.3-30.8%) abundance which regulated the growth and As uptake by P. vittata. Moreover, applying BC increased the biomass, and As uptake by P. vittata. Overall, BC strengthened the phytoremediation of As-polluted soils by improving soil pH, nutrient concentrations, enzyme activities, bacterial community structure, and soil arsenic activation, growth, and absorption by P. vittata.

Synergistic effects of vermicompost and mycorrhizal inoculation on arsenic tolerance and phytostabilization in safflower (Carthamus tinctorius L.)

Arsenic (As) is a hazardous metalloid, and mycorrhizal inoculation and vermicompost amendment can influence As bioremediation. However, the studies concerning the sole and joint effects of arbuscular mycorrhizal fungi (AMF) and vermicompost on the phytoremediation efficacy are limited. In the present study at first, the impact of various levels of vermicompost (0, 2, 4, and 8% w/w) was investigated on As mobility in soil and safflower (Carthamus tinctorius L.) plants grown in soils of spiked with 0, 40, and 80 mg kg-1 As. Results revealed that with increasing dose of vermicompost, bioavailable As in soil decreased which resulted in a lower bioaccumulation factor and translocation factor (TF) and led to a significant increase of tolerance index (TI) and total chlorophyll content in plants. The highest effect on TI and total As accumulation per plant was obtained in the dosage of 8% vermicompost. Therefore, in the second experiment, the sole and joint effects of 8% vermicompost and inoculation with Rhizophagus intraradices were assessed on the tolerance and accumulation of As in safflower. The addition of vermicompost aggravated mycorrhizal colonization but did not significantly influence mycorrhizal dependency under As stress. The joint effects of AMF and vermicompost improved the dry weight of roots and shoots, increased P concentration and P:As ratio in shoots, reduced malondialdehyde content, and moderated ascorbate peroxidase activity in leaves of As-stressed plants. Interestingly, co-application of AMF and vermicompost more than their sole usage decreased As concentration in shoots and TF and more strongly increased total As accumulation per plant. These findings suggest that mycorrhizal inoculation and vermicompost have a synergistic effect on As tolerance and phytostabilization efficacy of safflower plants, and their combined application may be a new option to remediate As-contaminated soils.

Arbuscular mycorrhizal symbiosis alleviates arsenic phytotoxicity in flooded Iris tectorum Maxim. dependent on arsenic exposure levels

Arsenic (As) pollution in wetlands has emerged as a serious global concern, posing potential threat to the growth of wetland plants. Arbuscular mycorrhizal fungi (AMF) can alleviate As phytotoxicity to host plants, but their ecological functions in wetland plants under flooding conditions remain largely unknown. Thus, a pot experiment was conducted using Rhizophagus irregularis and Iris tectorum Maxim. exposed to light (15 and 30 mg/kg As) and high (75 and 100 mg/kg As) levels of As, to investigate the intrinsic mechanisms underlying the effects of mycorrhizal inoculation on plant As tolerance under flooding conditions. The mycorrhizal colonization rates ranged from 31.47 ± 3.92 % to 60.69 ± 5.58 %, which were higher than the colonization rate (29.55 ± 13.60%) before flooding. AMF significantly increased biomass of I. tectorum under light As levels, together with increased phosphorus (P) and As uptake. Moreover, expression of arsenate reductase gene RiarsC and a trace of dimethylarsenic (1.87 mg/kg in shoots) were detected in mycorrhizal plants, suggesting As transformation and detoxification by AMF exposed to light levels of As. However, under high As levels, AMF inhibited As translocation from roots to shoots, and facilitated the formation of iron plaque. The immobilized As concentrations in iron plaque of mycorrhizal plants were respectively 1133.68 ± 179.17 mg/kg and 869.11 ± 248.90 mg/kg at 75 and 100 mg/kg As addition level, both significantly higher than that in non-inoculated plants. Irrespective of As exposure levels, mycorrhizal symbiosis decreased soil As bioavailability. Overall, the study provides insights into the alleviation of As phytotoxicity in natural wetland plants through mycorrhizal symbiosis, and potentially indicates function diversity of AMF under flooding conditions and As stress, supporting the subsequent phytoremediation and restoration of As-contaminated wetlands.

Phosphate-solubilizing bacteria: Their agroecological function and optimistic application for enhancing agro-productivity

Phosphorus (P) is a limiting nutrient in the soil-plant nutrient cycling. Although the exogenous application of chemical P fertilizers can satisfy crop P requirements during critical growth phases. While excessive P fertilizers use results in low phosphorus acquisition efficiency (PAE), it has serious environmental consequences and hastens the depletion of P mineral reserves. Phosphate-solubilizing bacteria (PSB) have the potential to make insoluble phosphate available to plants through solubilization and mineralization, increasing crop yields while maintaining environmental sustainability. Existing reviews mainly focus on the beneficial effects of PSB on crop performance and related mechanisms, while few of them elucidate the action mechanisms of PSB in soil-microbe-plant interactions for crop cultivation with high yield efficiency. Hence, this study provides a comprehensive review of the physicochemical and molecular mechanisms (e.g., root exudates, extracellular polysaccharides, organic acids, phosphatases, and phosphate-specific transport systems) of PSB to facilitate the P cycle in the soil-plant systems. Further, the potential of commercial applications of PSB (e.g., genetic engineering, seed priming and coating) are also discussed in order to highlight their contribution to sustainable agriculture. Finally, existing challenges and future prospects in agricultural applications are proposed. In conclusion, we firmly believe that PSB represent a highly significant biotechnological tool for enhancing agricultural productivity and offers a wide range of extensive potential applications.

Evidence of elevated heavy metals concentrations in wild and farmed sugar kelp (Saccharina latissima) in New England

Seaweed farming in the United States is gaining significant financial and political support due to prospects to sustainably expand domestic economies with environmentally friendly products. Several networks are seeking appropriate synthesis of available science to both inform policy and substantiate the sector's sustainability claims. Significant knowledge gaps remain regarding seaweed-specific food hazards and their mitigation; a resource-intensive challenge that can inhibit sustainable policies. This is particularly concerning for rapidly expanding Saccharina latissima (sugar kelp) crops, a brown seaweed that is known to accumulate heavy metals linked to food hazards. Here, we present baseline information about concentrations of arsenic, cadmium, lead, and mercury, in both wild and farmed sugar kelp from the New England region. We interpret our findings based on proximity to potential sources of contamination, location on blade, and available heavy metals standards. Contrary to our expectations, high concentrations were widespread in both wild and farmed populations, regardless of proximity to contamination. We find, like others, that cadmium and arsenic consistently reach levels of regulatory concern, and that dried seaweeds could harbor higher concentrations compared to raw products. We also share unique findings that suggest some toxins concentrate at the base of kelp blades. Our results are one step towards aggregating vital data for the region to expand its seaweed farming footprint.

Effect of phosphate on arsenic species uptake in plants under hydroponic conditions

Monothioarsenate (MTA) is a newly discovered arsenic (As) compound that can be formed under reduced sulfur conditions, mainly in paddy soil pore waters. It is structurally similar to arsenate As(V) and inorganic phosphate (Pi), which is taken up through phosphate transporters. Due to the similarity between As(V) and Pi, As(V) enters into plants instead of Pi. The important role played by phytochelatin (PC), glutathione (GSH), and the PC-vacuolar transporters ABCC1 and ABCC2 under As stress in plants is well known. However, the plant uptake and mechanisms surrounding MTA still have not been completely addressed. This investigation was divided in two stages: first, several hydroponic assays were set up to establish the sensibility-tolerance of wild-type Arabidopsis thaliana (accession Columbia-0, Col-0). Then Col-0 was used as a control plant to evaluate the effects of As(V) or MTA in (PC)-deficient mutant (cad1-3), glutathione biosynthesis mutant (cad2), and PC transport (abcc1-2). The inhibitory concentration (IC50) root length was calculated for both As species. According to the results, both arsenic species (As(V) and MTA) exhibited high toxicity for the genotypes evaluated. This could mean that these mechanisms play a constitutive role in MTA detoxification. Second, for the Pi-MTA and As(V)-Pi competition assays, a series of experiments on hydroponic seedlings of A. thaliana were carried out using Col-0 and a pht1;1. The plants were grown under increasing Pi concentrations (10 μM, 0.1 mM, or 1 mM) at 10 μM As(V) or 50 μM MTA. The total As concentration in the roots was significantly lower in plants exposed to MTA, there being less As content in the pht1;1 mutant at the lowest Pi concentrations tested compared with the As(V)/Pi treatments. In addition, a higher rate of As translocation from the roots to the shoots under MTA was observed in comparison to the As(V)-treatments.

Arsenic toxicity to earthworms in soils of historical As mining sites: an assessment based on various endpoints and chemical extractions

Eisenia fetida is an earthworm species often used to assess the toxicity of contaminants in soils. Several studies indicated that its response can be unpredictable because it depends both on total concentrations of contaminants and also on their forms that differ in susceptibility to be released from soil solid phase. The issue is complex because two various uptake routes are concurrently involved, dermal and ingestion in guts, where the bioavailability of contaminants can considerably change. The aim of this study was to analyze the toxicity of arsenic (As) in various strongly contaminated meadow and forest soils, representative for former As mining and processing area, to earthworms E. fetida and its accumulation in their bodies. An attempt was made to find relationships between the response of earthworms and chemical extractability of As. In the bioassay, carried out according to the standard ISO protocol, different endpoints were applied: earthworm survival, fecundity measured by the numbers of juveniles and cocoons, earthworm weight and As accumulation in the bodies. The results proved that E. fetida can tolerate extremely high total As concentrations in soils, such as 8000 mg/kg, however, the individual endpoints were not correlated and showed different patterns. The most sensitive one was the number of juveniles. No particular soil factor was identified that would indicate an exceptionally high As susceptibility to the release from one of soils, however, we have demonstrated that the sum of non-specifically and specifically bound As (i.e. fractions F1 + F2 in sequential extraction according to Wenzel) could be a good chemical indicator of arsenic toxicity to soil invertebrates.

The influence of diverse fertilizer regimes on the phytoremediation potential of Pteris vittata in an abandoned nonferrous metallic mining site

Organic waste comprises a large amount of hydrocarbon containing organic substances, which is regarded as a potential resource rather than simply a waste. A field experiment was conducted in a poly-metallic mining area to investigate the potential of organic waste to facilitate the soil remediation process. Different organic wastes and a commonly used commercial fertilizer were added to heavy metal contaminated soil, which was under phytoremediation using the As hyperaccumulator Pteris vittata. The influence of diverse fertilizer regimes on the biomass of P. vittata and heavy metal removal by P. vittata, was investigated. The soil properties were analyzed after the application of phytoremediation with or without the addition of organic wastes. Results indicated that sewage sludge compost is an appropriate amendment to improve the phytoremediation efficiency. Compared to the control, the application of sewage sludge compost significantly reduced the extractability of As in soil by 26.8 %, and increased the removal of As and Pb by 26.9 % and 186.5 %, respectively. The highest removal of As and Pb reached 33 and 34 kg/ha, respectively. The sewage sludge compost-strengthened phytoremediation improved soil quality. And the diversity and richness of the bacterial community were improved, as represented by the increase in Shannon and Chao index. With improved efficiency and acceptable cost, the organic waste-strengthened phytoremediation can be used to control the risks posed by high concentrations of heavy metals in mining areas.

Assessing indicators of arsenic toxicity using variable fluorescence in a commercially valuable microalgae: Physiological and toxicological aspects

Indicators signaling Arsenic (As) stress through physiology of microalgae using non-destructive methods like variable fluorescence are rare but requisite. This study reports stress markers indicating arsenic (As) toxicity (in two concentrations 11.25 µg/L and 22.5 µg/L compared to a control) exposed to a microalga (Diacronema lutheri), using fast repetition rate fluorometry (FRRf). Growth and physiological parameters such as cell density, chl a and the maximum quantum yield F_v/F_m showed coherence and impeded after the exponential phase (day 9 - day 12) in As treatments compared to the control (p < 0.05). On contrary photo-physiological constants were elevated showing higher optical (a_LHII) and functional [Sigma (σ_PSII)] absorption cross-section for the As treatments (p < 0.05) further implying the lack of biomass production yet an increase in light absorption. In addition, As exposure increased the energy dissipation by heat (NPQ-NSV) showing a strong relationship with the de-epoxidation ratio (DR) involving photoprotective pigments. Total As bioaccumulation by D. lutheri showed a strong affinity with Fe adsorption throughout the algal growth curve. This study suggests some prompt photo-physiological proxies signaling As contamination and endorsing its usefulness in risk assessments, given the high toxicity and ubiquitous presence of As in the ecosystem.

Wheat PHT1;9 acts as one candidate arsenate absorption transporter for phytoremediation

Arsenate (AsV) is one of the most common forms of arsenic (As) in environment and plant high-affinity phosphate transporters (PHT1s) are the primary plant AsV transporters. However, few PHT1s involved in AsV absorption have been identified in crops. In our previous study, TaPHT1;3, TaPHT1;6 and TaPHT1;9 were identified to function in phosphate absorption. Here, their AsV absorption capacities were evaluated using several experiments. Ectopic expression in yeast mutants indicated that TaPHT1;9 had the highest AsV absorption rates, followed by TaPHT1;6, while not for TaPHT1;3. Under AsV stress, further, BSMV-VIGS-mediated TaPHT1;9-silencing wheat plants exhibited higher AsV tolerance and lower As concentrations than TaPHT1;6-silenced plants, whereas TaPHT1;3-silencing plants had similar phenotype and AsV concentrations to control. These suggested that TaPHT1;9 and TaPHT1;6 possessed AsV absorption capacity with the former showing higher activities. Under hydroponic condition, furthermore, CRISPR-edited TaPHT1;9 wheat mutants showed the enhanced tolerance to AsV with decreased As distributions and concentrations, whereas TaPHT1;9 ectopic expression transgenic rice plants had the opposite results. Also, under AsV-contaminated soil condition, TaPHT1;9 transgenic rice plants exhibited depressed AsV tolerance with increased As concentrations in roots, straws and grains. Moreover, Pi addition alleviated the AsV toxicity. These suggested that TaPHT1;9 should be a candidate target gene for AsV phytoremediation.

Plant-microbe interactions ameliorate phosphate-mediated responses in the rhizosphere: a review

Phosphorus (P) is one of the essential minerals for many biochemical and physiological responses in all biota, especially in plants. P deficiency negatively affects plant performance such as root growth and metabolism and plant yield. Mutualistic interactions with the rhizosphere microbiome can assist plants in accessing the available P in soil and its uptake. Here, we provide a comprehensive overview of plant-microbe interactions that facilitate P uptake by the plant. We focus on the role of soil biodiversity in improved P uptake by the plant, especially under drought conditions. P-dependent responses are regulated by phosphate starvation response (PSR). PSR not only modulates the plant responses to P deficiency in abiotic stresses but also activates valuable soil microbes which provide accessible P. The drought-tolerant P-solubilizing bacteria are appropriate for P mobilization, which would be an eco-friendly manner to promote plant growth and tolerance, especially in extreme environments. This review summarizes plant-microbe interactions that improve P uptake by the plant and brings important insights into the ways to improve P cycling in arid and semi-arid ecosystems.

Arbuscular mycorrhizal fungi community analysis revealed the significant impact of arsenic in antimony- and arsenic-contaminated soil in three Guizhou regions

Introduction

The lack of systematic investigations of arbuscular mycorrhizal fungi (AMF) community composition is an obstacle to AMF biotechnological applications in antimony (Sb)- and arsenic (As)-polluted soil.

Methods

Morphological and molecular identification were applied to study the AMF community composition in Sb- and As-contaminated areas, and the main influencing factors of AMF community composition in Sb- and As-contaminated areas were explored.

Results

(1) A total of 513,546 sequences were obtained, and the majority belonged to Glomeraceae [88.27%, 193 operational taxonomic units (OTUs)], followed by Diversisporaceae, Paraglomeraceae, Acaulosporaceae, Gigasporaceae, and Archaeosporaceae; (2) the affinity between AMF and plants was mainly related to plant species (F = 3.488, p = 0.022 < 0.050), which was not significantly correlated with the total Sb (TSb) and total As (TAs) in soil; (3) the AMF spore density was mainly related to the available nitrogen, available potassium, and total organic carbon; (4) The effect of soil nutrients on AMF community composition (total explanation: 15.36%) was greater than that of soil Sb and As content (total explanation: 5.80%); (5) the effect of TAs on AMF community composition (λ = -0.96) was more drastic than that of TSb (λ = -0.21), and the effect of As on AMF community composition was exacerbated by the interaction between As and phosphorus in the soil; and (6) Diversisporaceae was positively correlated with the TSb and TAs.

Discussion

The potential impact of As on the effective application of mycorrhizal technology should be further considered when applied to the ecological restoration of Sb- and As-contaminated areas.

Two-Dimensional Mapping of Arsenic Concentration and Speciation with Diffusive Equilibrium in Thin-Film Gels

We present a new approach combining diffusive equilibrium in thin-film gels and spectrophotometric methods to determine the spatial distribution of arsenite, arsenate, and phosphate at submillimeter resolution. The method relies on the simultaneous deployment of three gel probes. Each retrieved gel is exposed to malachite green reagent gels differing in acidity and oxidant addition, leading to green coloration dependent on analyte speciation and concentration. Hyperspectral images of the gels enable mapping the three analytes in the 2.5-20 μM range. This method was applied in a contaminated brook in the Harz mountains, Germany, together with established mapping of dissolved iron. The use of two-dimensional (2D) gel probes was compared to traditional porewater extraction. The gels revealed banded porewater patterns on a mm-scale, which were undetectable using traditional methods. Small-scale correlation analyses of arsenic and iron microstructures in the gels suggested active iron-driven local redox cycling of arsenic. Overall, the results indicate continuous net release of arsenic from contaminant particles and deepen our understanding of arsenate transformation under anaerobic conditions. This study is the first fine-scale 2D characterization of arsenic speciation in porewater and represents a crucial step toward understanding the transfer and redox cycling of arsenic in contaminated sediment/soil ecosystems.

Remediating flooding paddy soils with schwertmannite greatly reduced arsenic accumulation in rice (Oryza sativa L.) but did not decrease the utilization efficiency of P fertilizer

Planting rice (Oryza sativa L.) in As-contaminated paddy soils can lead to accumulation of arsenic (As) in rice grains, while the application of phosphorus (P) fertilizers during rice growth may aggravate the accumulation effect. However, remediating flooding As-contaminated paddy soils with conventional Fe(III) oxides/hydroxides can hardly achieve the goals of effectively reducing grain As and maintaining the utilization efficiency of phosphate (Pi) fertilizers simultaneously. In the present study, schwertmannite was proposed to remediate flooding As-contaminated paddy soil because of its strong sorption capacity for soil As, and its effect on the utilization efficiency of Pi fertilizer was investigated. Results of a pot experiment showed that Pi fertilization along with schwertmannite amendment was effective to reduce the mobility of As in the contaminated paddy soil and meanwhile increase soil P availability. The schwertmannite amendment along with Pi fertilization reduced the content of P in Fe plaque on rice roots, compared with the corresponding amount of Pi fertilizer alone, which can be attributed to the change in mineral composition of Fe plaque mainly induced by schwertmannite amendment. Such reduction in P retention on Fe plaque was beneficial for improving the utilization efficiency of Pi fertilizer. In particular, amending flooding As-contaminated paddy soil with schwertmannite and Pi fertilizer together has reduced the content of As in rice grains from 1.06 to 1.47 mg/kg to only 0.38-0.63 mg/kg and significantly increased the shoot biomass of rice plants. Therefore, using schwertmannite to remediate flooding As-contaminated paddy soils can achieve the dual goals of effectively reducing grain As and maintaining the utilization efficiency of P fertilizers.

Transcriptome analysis provides insights into the response of Lotus corniculatus roots to low-phosphorus stress

INTRODUCTION

A lack of soil phosphorus (P) is a principal factor restricting the normal growth of Lotus corniculatus in the karst area of Guizhou Province, China, but the response mechanism of L. corniculatus under low-phosphorus stress remains unclear.

METHODS

Therefore, we treated two selected L. corniculatus lines (low-P-intolerant line 08518 and low-P-tolerant line 01549) from 13 L. corniculatus lines with normal phosphorus (0.5 mmol/L KH₂PO₄, NP) and low phosphorus (0.005 mmol/L KH₂PO₄, LP) concentrations to study changes in morphological, physiological and transcriptome data under low-phosphorus stress.

RESULTS

The low-P-tolerant line 01549 exhibited better performance under low-phosphorus stress. Compared with the NP treatment, all root morphological indicators of the low-P-tolerant line 01549 increased, and those of the low-P-intolerant line 08518 decreased under low-P stress. Compared with the NP treatment, acid phosphatase (ACP), catalase (CAT), superoxide dismutase (SOD), and peroxidase (POD) activities, and the malondialdehyde (MDA), soluble sugar (SS), soluble protein (SP) and proline (Pro) contents of the two L. corniculatus lines increased under low-P stress. A transcriptome analysis of L. corniculatus showed that a total of 656 and 2243 differentially expressed genes (DEGs) were identified in line 01549 and line 08518, respectively. Meanwhile, the main pathways, such as carbohydrate metabolism, acid phosphatases, phosphate transporters and biosynthesis of secondary metabolites, as well as related genes were also screened by performing a KEGG enrichment analysis.

DISCUSSION

The findings provide an essential point of reference for studying the physiological and molecular mechanism of the response to low-P stress in L. corniculatus.

Multiple-functionalized biochar affects rice yield and quality via regulating arsenic and lead redistribution and bacterial community structure in soils under different hydrological conditions

Rice grown in soils contaminated with arsenic (As) and lead (Pb) can cause lower rice yield and quality due to the toxic stress. Herein, we examined the role of functionalized biochars (raw phosphorus (P)-rich (PBC) and iron (Fe)-modified P-rich (FePBC)) coupled with different irrigation regimes (continuously flooded (CF) and intermittently flooded (IF)) in affecting rice yield and accumulation of As and Pb in rice grain. Results showed that FePBC increased the rice yield under both CF (47.4%) and IF (19.6%) conditions, compared to the controls. Grain As concentration was higher under CF (1.94-2.42 mg kg^-1) than IF conditions (1.56-2.31 mg kg^-1), whereas the concentration of grain Pb was higher under IF (0.10-0.76 mg kg^-1) than CF (0.12-0.48 mg kg^-1) conditions. Application of PBC reduced grain Pb by 60.1% under CF conditions, while FePBC reduced grain As by 12.2% under IF conditions, and increased grain Pb by 2.9 and 6.6 times under CF and IF conditions, respectively, compared to the controls. Therefore, application of the multiple-functionalized biochar can be a promising strategy for increasing rice yield and reducing the accumulation of As in rice grain, particularly under IF conditions, whereas it is inapplicable for remediation of paddy soils contaminated with Pb.

Arsenic contribution of poultry manure towards soils and food plants contamination and associated cancer risk in Khyber Pakhtunkhwa, Pakistan

Exposure to high level of arsenic (As) through the ingestion of contaminated soil, dust and food plants can pose health risk to humans. This study investigates the total arsenic (As), arsenobetaine (AsB), monomethylarsenate (MMA), dimethylarsenate (DMA), arsenite (As³⁺) and arsenate (As⁵⁺) concentrations in poultry feed, manure, agricultural soils and food plants collected from Khyber Pakhtunkhwa Province, Pakistan. The total mean As concentrations in the edible parts of food plants ranged from 0.096 mg kg^-1 to 1.25 mg kg^-1 with percentile (P) values (P25-0.039, P50-0.0765, P75-0.165 1 mg kg^-1 to P25-0.95, P50-1.23, P75-1.6 1 mg kg^-1) and exceeded the food safety limit (0.1 mg kg^-1) of Food & Agriculture Organization (FAO) and World Health Organization (WHO) in all plant species except Pisum sativum (pea) and Mentha arvensis (mint). The risk to human health was assessed through the average daily intake (ADI), hazards quotient (HQ), health risk index (HRI) and lifetime cancer risk (LTCR). The highest average daily intake of As via the ingestion of Malva neglecta (mallow, a leafy plant) was observed for adults and children. The ADI for adults and children (2.36 × 10^-4 mg kg^-1 day^-1 and 6.33 × 10^-4 mg kg^-1 day^-1) was about 13% and 5%, respectively, of the Bench Mark Dose Limit (BMDL_0.5) of 3.00 × 10^-3 mg kg^-1 day^-1 set by WHO. The HRI was 3 times more in the children (2.1) than the adults (0.79), posing non-cancer health risks (health risk index > 1) for children. The LTCR values were slightly higher (1.53 × 10^-4) relative to USEPA and WHO limits (1 × 10^-6 to 1 × 10^-4) for children whereas a minimal cancer risk was observed for adults via consumption of selected food plants. The results showed that poultry manure can contaminate food plants that may lead to cancer and non-cancer risks in agricultural areas, Pakistan. Thus, it is important to minimize As concentration in poultry feed to safeguard human health and environment from adverse effects.

Arsenic-induced up-regulation of P transporters PvPht1;3-1;4 enhances both As and P uptake in As-hyperaccumulator Pteris vittata

Plants often up-regulate gene expression of P transporters under P deficiency, but down-regulate them under arsenic stress. Different from other P transporters, PvPht1;3 and PvPht1;4 expressions in As-hyperaccumulator Pteris vittata are up-regulated under P deficiency and As stress, showing strong transport capacity for both As and P. This study examined the mechanisms behind As-induced up-regulation of P transporters in P. vittata after exposing to 10-50 µM arsenate (AsV) for 14 d under hydroponics, with non-hyperaccumulator P. ensiformis as a control. Under As stress, P. vittata was more efficient in taking up both As and P than P. ensiformis, showing 48-84% more P content in the fronds and roots, leading to 18-79% greater biomass. Though As enhanced the P uptake by P. vittata, the inorganic P was reduced by 25-64% from 140-347 to 65-126 mg kg^-1. It is likely that, under As stress, more P was utilized by P. vittata to counter As toxicity, causing reduction in inorganic P. This was supported by As-induced conversion of inorganic P to phytate in P. vittata, with phytate-P being increased by 26-75% from 239-713 to 418-1221 mg kg^-1, maintaining internal low P levels. Under As-induced low inorganic-P conditions, the expressions of P transporters PvPht1;3 and PvPht1;4 were up-regulated by 1.4- and 2.7-fold in the roots, helping greater As and P uptake by P. vittata. Clearly, As-induced overexpression of P transporters in P. vittata roots plays a critical role in taking up both As and P, thereby increasing its efficiency in As-hyperaccumulation from contaminated media.

Biological effect of phosphate on the dissimilatory arsenate-respiring bacteria-catalyzed reductive mobilization of arsenic from contaminated soils

Dissimilatory arsenate-respiring prokaryotes (DARPs) are considered to be the major drive of the reductive mobilization of arsenic from solid phases. However, it is not fully understood how phosphate, a structural analog of arsenate, affects the DARPs-mediated arsenic mobilization. This work aimed to address this issue. As-contaminated soils were collected from a Shimen Realgar Mine-affected area. We identified a unique diversity of DARPs from the soils, which possess high As(V)-respiring activities using one of multiple small organic acids as the electron donor. After elimination of the desorption effect of phosphate on the As mobilization, the supplement of additional 10 mM phosphate to the active slurries markedly increased the microbial community-mediated reductive mobilization of arsenic as revealed by microcosm tests; this observation was associated to the fact that phosphate significantly increased the As(V)-respiratory reductase (Arr) gene abundances in the slurries. To confirm this finding, we further obtained a new DARP strain, Priestia sp. F01, from the samples. We found that after elimination of the chemical effect of phosphate, the supplement of 10 mM phosphate to the active slurries resulted in an 82.2% increase of the released As(III) in the solutions, which could be contributed to that excessive phosphate greatly increased the Arr gene abundance, and enhanced the transcriptional level of arrA gene and the bacterial As(V)-respiring activity of F01 cells. Considering that phosphate commonly coexists with As in the environment, and is a frequently-used fertilizer, these findings are helpful for deeply understanding why As concentrations in contaminated groundwater are dynamically fluctuated, and also provided new knowledge on the interactions between the biogeochemical processes of P and As.

An insight into the act of iron to impede arsenic toxicity in paddy agro-system

Surplus research on the widespread arsenic (As) revealed its disturbing role in obstructing the metabolic function of plants. Also, the predilection of As towards rice has been an interesting topic. Contrary to As, iron (Fe) is an essential micronutrient for all life forms. Past findings propound about the enhanced As-resistance in rice plants during Fe supplementation. Thus, considering the severity of As contamination and resulting exposure through rice crops, as well as the studied cross-talks between As and Fe, we found this topic of relevance. Keeping these in view, we bring this review discussing the presence of As-Fe in the paddy environment, the criticality of Fe plaque in As sequestration, and the effectiveness of various Fe forms to overcome As toxicity in rice. This type of interactive analysis for As and Fe is also crucial in the context of the involvement of Fe in cellular redox activities such as oxidative stress. Also, this piece of work highlights Fe biofortification approaches for better rice varieties with optimum intrinsic Fe and limited As. Though elaborated by others, we lastly present the acquisition and transport mechanisms of both As and Fe in rice tissues. Altogether we suggest that Fe supply and Fe plaque might be a prospective agronomical tool against As poisoning and for phytostabilization, respectively.

Effects of Phosphate, Red Mud, and Biochar on As, Cd, and Cu Immobilization and Enzymatic Activity in a Co-Contaminated Soil

Arsenic (As), cadmium (Cd), and copper (Cu) are the primary inorganic pollutants commonly found in contaminated soils. The simultaneous stabilization of the three elements is a preferred approach for mixture-contaminated soils which has received extensive research attention. However, few studies have focused on the immobilization efficiency of a single amendment on the three elements. In this study, phosphate, red mud, and biochar were used to remediate As (237.8 mg kg−1), Cd (28.72 mg kg−1), and Cu (366.5 mg kg−1) co-contaminated soil using a 180-day incubation study. The BCR (European Community Bureau of Reference) extraction method, NH4H2PO4–extractable As, and diethylenetriamine penta-acetic acid (DTPA)–extractable Cd and Cu were analyzed at different time intervals. The results indicated that the application of red mud and biochar significantly reduced soil DTPA–Cd and Cu concentrations during the incubation, while the decrease in soil NH4H2PO4–As was much less than that of soil DTPA–Cd and Cu. After 180 days of incubation, the concentrations of NH4H2PO4–As in red mud and biochar treatments decreased by 2.15~7.89% and 3.01~9.63%, respectively. Unlike red mud and biochar, phosphate significantly reduced the concentration of soil DTPA–Cd and Cu, but failed to lower that of As. The BCR extraction method confirmed that red mud and biochar addition increased the reducible fraction of As due to the surface complexes of As with Fe oxide. Canonical correspondence analysis (CCA) demonstrated that soil pH in addition to available As, Cd, and Cu concentrations were the primary factors in driving the changes in soil enzymatic activity. Soil pH showed positive correlation with soil urease and catalase activities, while negative correlation was observed between soil-available As, Cd, and Cu, and soil enzyme activities. This study revealed that it is difficult to simultaneously and significantly reduce the bioavailabilities of soil As, Cd, and Cu using one amendment. Further research on modifying these amendments or applying combined amendments will be conducted, in order to develop an efficient method for simultaneously immobilizing As, Cd, and Cu.

Cannabis sativa L. and Brassica juncea L. grown on arsenic-contaminated industrial soil: potentiality and limitation for phytoremediation

Phytoremediation represents a natural method to remove contaminants from soil. The goal of this study was to investigate the potential of phosphate-assisted phytoremediation by two energy crops, Cannabis sativa L. and Brassica juncea L., for the sustainable remediation of heavily arsenic-contaminated industrial soil. The two species were investigated for uptake, translocation, and physiological effects of arsenic and phosphate in a microcosm test. Although C. sativa and B. juncea were symptomless when grown in arsenic-contaminated soil, an important reduction of biomass (50 and 25%, respectively) was observed as a stress marker. Phytotoxicity and cytotoxicity effects promoted by contaminated soils were investigated in both the species and a model plant for ecotoxicity studies, Vicia faba L., which is the most developed model to test genotoxicity effects in terms of chromosomal aberration and micronuclei presence. The higher amount of arsenic was found in C. sativa and B. juncea roots (on average 1473 and 778 mg kg-1, respectively), but both species were able to uptake and translocate arsenic in leaves and stems, up to 47.0 and 189 mg kg-1, respectively. Phosphate treatment had no effect on arsenic uptake in none of the crop, but significantly improved the plant performance. Biomass production resulted similar to that of B. juncea control plants. Antioxidant enzymatic activities and photosynthetic performance responded differently in the two crops. The present investigation provides new insight for a proficient selection of the most suitable crop species for sustainable phytomanagement of a highly polluted As-contaminated site by coupled phytoremediation-bioenergy approach.

A Panax notoginseng phosphate transporter, PnPht1;3, greatly contributes to phosphate and arsenate uptake

The crisis of arsenic (As) accumulation in rhizomes threatens the quality and safety of Panax notoginseng (Burk.) F.H. Chen, which is a well-known traditional Chinese herb with a long clinical history. The uptake of arsenate (AsV) could be suppressed by supplying phosphate (Pi), in which Pi transporters play important roles in the uptake of Pi and AsV. Herein, the P . notoginseng Pi transporter-encoding gene PnPht1;3 was identified and characterised under Pi deficiency and AsV exposure. In this study, the open reading frame (ORF) of PnPht1;3 was cloned according to RNA-seq and encoded 545 amino acids. The relative expression levels revealed that PnPht1;3 was significantly upregulated under phosphate deficiency and AsV exposure. Heterologous expression in Saccharomyces cerevisiae MB192 demonstrated that PnPht1;3 performed optimally in complementing the yeast Pi-transport defect and accumulated more As in the cells. Combined with the subcellular localisation prediction, it was concluded that PnPht1;3 encodes a functional plasma membrane-localised transporter protein that mediates putative high-affinity Pi/H+ symport activity and enhances the uptake of Pi and AsV. Therefore, a better understanding of the roles of the P . notoginseng Pi transporter could provide new insight for solving As accumulation in medicinal plants.

The Role of H2O2-Scavenging Enzymes (Ascorbate Peroxidase and Catalase) in the Tolerance of Lemna minor to Antibiotics: Implications for Phytoremediation

We investigated the individual and combined contributions of two distinct heme proteins namely, ascorbate peroxidase (APX) and catalase (CAT) on the tolerance of Lemna minor plants to antibiotics. For our investigation, we used specific inhibitors of these two H₂O₂-scavenging enzymes (p-aminophenol, 3-amino,1,2,4-triazole, and salicylic acid). APX activity was central for the tolerance of this aquatic plant to amoxicillin (AMX), whereas CAT activity was important for avoiding oxidative damage when exposed to ciprofloxacin (CIP). Both monitored enzymes had important roles in the tolerance of Lemna minor to erythromycin (ERY). The use of molecular kinetic approaches to detect and increase APX and/or CAT scavenging activities could enhance tolerance, and, therefore, improve the use of L. minor plants to reclaim antibiotics from water bodies.

Calcium Oxide Nanoparticles Have the Role of Alleviating Arsenic Toxicity of Barley

Arsenic (As) contamination in agricultural soils has become a great threat to the sustainable development of agriculture and food safety. Although a lot of approaches have been proposed for dealing with soil As contamination, they are not practical in crop production due to high cost, time-taking, or operational complexity. The rapid development of nanotechnology appears to provide a novel solution to soil As contamination. This study investigated the roles of calcium oxide nanoparticles (CaO NPs) in alleviating As toxicity in two barley genotypes (LJZ and Pu-9) differing in As tolerance. The exposure of barley seedlings to As stress showed a significant reduction in plant growth, calcium and chlorophyll content (SPAD value), fluorescence efficiency (Fv/m), and a dramatic increase in the contents of reactive oxygen species (ROS), malondialdehyde (MDA) and As, with LJZ being more affected than Pu-9. The exogenous supply of CaO NPs notably alleviated the toxic effect caused by As in the two barley genotypes. Moreover, the expression of As transporter genes, that is, HvPHT1;1, HvPHT1;3, HvPHT1;4 and HvPHT1;6, was dramatically enhanced when barley seedlings were exposed to As stress and significantly reduced in the treatment of CaO NPs addition. It may be concluded that the roles of CaO NPs in alleviating As toxicity could be attributed to its enhancement of Ca uptake, ROS scavenging ability, and reduction of As uptake and transportation from roots to shoots.

Alteration in soil arsenic dynamics and toxicity to sunflower (Helianthus annuus L.) in response to phosphorus in different textured soils

Being analogue to arsenic (As), phosphorus (P) may affect As dynamics in soil and toxicity to plants depending upon many soil and plant factors. Two sets of experiments were conducted to determine the effect of P on As fractionation in soils, its accumulation by plants and subsequent impact on growth, yield and physiological characteristics of sunflower (Helianthus annuus L.). Experimental plan comprised of two As levels (60 and 120 mg As kg^-1 soil), four P (0-5-10-20 g phosphate rock kg^-1 soil) and three textural types (sandy, loamy and clayey) with three replications. Among different As fractions determined, labile, calcium-bound, organic matter-bound and residual As increased while iron-bound and aluminum-bound As decreased with increasing P in all the three textural types. Labile-As percentage increased in the presence of P by 16.9-48.0% at As60 while 36.0-68.1% at As120 in sandy, 19.1-64.0% at As60 while 11.5-52.3% at As120 in loamy, and 21.8-58.2% at As60 while 22.3-70.0% at As120 in clayey soil compared to respective As treatment without P. Arsenic accumulation in plant tissues at both contamination levels declined with P addition as evidenced by lower bioconcentration factor. Phosphorus mitigated the As-induced oxidative stress expressed in term of reduced hydrogen peroxide, malondialdehyde while increased glutathione, and consequently improved the achene yield. Although, P increased As solubility in soil but restricted its translocation to plant, leading to reversal of oxidative damage, and improved sunflower growth and yield in all the three soil textural types, more profound effect at highest P level and in sandy texture.

Phosphorus-arsenic interaction in the 'soil-plant-microbe' system and its influence on arsenic pollution

Elevated arsenic (As) in soil is of public concern due to the carcinogenicity. Phosphorus (P) strongly influences the adsorption, absorption, transport, and transformation of As in the soil and in organisms due to the similarity of the chemical properties of P and As. In soil, P, particularly inorganic P, can release soil-retained As (mostly arsenate) by competing for adsorption sites. In plant and microbial systems, P usually reduces As (mainly arsenate) uptake and affects As biotransformation by competing for As transporters. The intensity and pattern of PAs interaction are highly dependent on the forms of As and P, and strongly influenced by various biotic and abiotic factors. An understanding of the PAs interaction in 'soil-plant-microbe' systems is of great value to prevent soil As from entering the human food chain. Here, we review PAs interactions and the main influential factors in soil, plant, and microbial subsystems and their effects on the As release, absorption, transformation, and transport in the 'soil-plant-microbe' system. We also analyze the application potential of P fertilization as a control for As pollution and suggest the research directions that need to be followed in the future.

Transfer of Macronutrients, Micronutrients, and Toxic Elements from Soil to Grapes to White Wines in Uncontaminated Vineyards

Wine is a popular beverage and may be a source of nutrient and toxic elements during human consumption. Here, we explored the variation in nutrient and toxic elements from soils to grape berries and commercial white wines (Chardonnay) at five USA vineyards (New York, Vermont, California, Virginia) with strongly contrasting geology, soils, and climates. Samples were analyzed for macronutrients (Ca, K, and Mg), micronutrients (Mn, Cu, and Zn), and toxic elements (As, Cd, and Pb). Our study showed contrasting macronutrient, micronutrient, and toxic element concentrations in soils and in vines, leaves, and grapes. However, plant tissue concentrations did not correspond with total soil concentrations, suggesting a disconnect governing their accumulation. Bioconcentration factors for soil to grape berry transfer suggest the accumulation of Ca, K and Mg in berries while Fe, Mn, Cu, Zn, and Pb were generally not accumulated in our study or in previous studies. Wines from the five vineyards studied had comparable nutrient, micronutrient, and toxic metal concentrations as wines from Germany, Italy, Portugal, Spain, Croatia, Czech Republic, and Japan. The transfer of nutrients and toxic elements from grape berries to wine indicated that only Ca, K, and Mg were added or retained while concentrations of all other micronutrients and toxic elements were somewhat to extensively diminished. Thus, there appears to be a substantial effect on the geochemistry of the wine from the grape from either the fermentation process (i.e., flocculation), or a dilution effect. We conclude that soils, geology, and climate do not appear to generate a unique geochemical terroir as the transfer and concentration of inorganic nutrients appear to be comparable across strongly contrasting vineyards. This has several implications for human health. Nutrients in wine have potential impacts for human nutrition, as wine can meet or exceed the recommended dietary requirements of Ca, K, Mg, and Fe, and toxic metals As and Pb concentrations were also non-trivial.

Arsenic contamination, impact and mitigation strategies in rice agro-environment: An inclusive insight

Arsenic (As) contamination and its adverse consequences on rice agroecosystem are well known. Rice has the credit to feed more than 50% of the world population but concurrently, rice accumulates a substantial amount of As, thereby compromising food security. The gravity of the situation lays in the fact that the population in theAs uncontaminated areas may be accidentally exposed to toxic levels of As from rice consumption. In this review, we are trying to summarize the documents on the impact of As contamination and phytotoxicity in past two decades. The unique feature of this attempt is wide spectrum coverages of topics, and that makes it truly an interdisciplinary review. Aprat from the behaviour of As in rice field soil, we have documented the cellular and molecular response of rice plant upon exposure to As. The potential of various mitigation strategies with particular emphasis on using biochar, seed priming technology, irrigation management, transgenic variety development and other agronomic methods have been critically explored. The review attempts to give a comprehensive and multidiciplinary insight into the behaviour of As in Paddy -Water - Soil - Plate prospective from molecular to post-harvest phase. From the comprehensive literature review, we may conclude that considerable emphasis on rice grain, nutritional and anti-nutritional components, and grain quality traits under arsenic stress condition is yet to be given. Besides these, some emerging mitigation options like seed priming technology, adoption of nanotechnological strategies, applications of biochar should be fortified in large scale without interfering with the proper use of biodiversity.

Rhizosphere interactions between PAH-degrading bacteria and Pteris vittata L. on arsenic and phenanthrene dynamics and transformation

The pot experiment was conducted to monitor the dynamics in soil solution chemistry in order to determine the main rhizosphere processes determining As and PAH bioavailability when utilizing P. vittata and PAH-degrading bacteria to remediate co-contaminated soils. The result showed that P. vittata was capable of depleting soil solution As and increasing phenanthrene solubilization, and thus facilitating plant As uptake and phenanthrene dissipation. Bacterial inoculation enhanced soil phenanthrene dissipation and concurrently modified As bioavailability though increasing soil pH, facilitating Fe and Ca minerals solubilization, and accelerating organic matter decomposition. However, the main factors that determine As bioavailability in the rhizosphere considerably varied with plant genotypes. Upon bacterial inoculation, P and Fe strongly influenced As(V) availability and its uptake by the Guangxi accession, and DOC, Fe, and pH were the main parameters correlated with As(V) availability in the rhizosphere of the Hunan accession. Bacterial inoculation tended to stimulate As(V) reduction in the rhizosphere of P. vittata. Microbial-induced changes in Ca, S, and C cycling and pH were indicators of As(V) reduction. Although bacterial inoculation increased soil As and phenanthrene availability, striking differences in As and nutrients uptake and phenanthrene dissipation were observed between P. vittata genotypes. It is suggested that apart from the microbial transformation, plant genotypes and bacterial mediated plant nutrition are also the critical factors in controlling the fates of As and phenanthrene. Our results uncovered the interactions between P. vittata and PAH-degrading bacteria on rhizosphere properties and nutrients cycling regulating As and PAH availability and remediation efficiency.

Effect of P/As molar ratio in soil porewater on competitive uptake of As and P in As sensitive and tolerant rice genotypes

Phosphorus (P) can affect the bioavailability and mobility of arsenic (As) in paddy soil-plant system, but it is not clear how different forms of phosphorus fertilizers affect P/As molar ratio in soil and how the ratio in turn affects the competitive uptake of P and As in two genotypes. Different P fertilizers, i.e., calcium-magnesium phosphate (CMP), superphosphate (SP) and potassium phosphate monobasic (PPM), were used to investigate the difference in competitive uptake between As sensitive (IIY3301) and As tolerant (SY9519) rice genotypes. Our results indicated that the contents of total As in brown rice of PPM and SP treatments (II-PPM and II-SP) were 15.4% and 26.9% lower than that of CMP treatment (II-CMP) for IIY3301 genotype, but their P contents were 27.0% and 17.8% higher than that of II-CMP treatment. However, the As content in brown rice showed no significant difference between PPM and CMP treatments for SY9519 genotype (S-PPM and S-CMP). The net As accumulation in shoots of II-PPM during the tillering stage was significantly lower than that of II-CMP, but the difference of net As accumulation between S-PPM and S-CMP was not significant. The As translocation factor in II-PPM and II-SP were 16.7% and 22.2% lower than that in II-CMP, but the difference of As translocation factor between S-PPM and S-CMP was not significant. In addition, the contents of total As in porewater showed no significant difference between PPM and CMP. Conversely, the P/As molar ratio in porewater of PPM during tillering stage was 10.9% higher than that of CMP. In summary, PPM led to a higher P/As molar ratio in porewater, which promoted the competitive uptake of As and P by IIY3301 genotype; and the competitive uptake of As and P was more likely to occur in As sensitive rice genotype than in As tolerant rice genotype.

Water management of alternate wetting and drying combined with phosphate application reduced lead and arsenic accumulation in rice

Lead (Pb) and arsenic (As) exist in soil with different ionic forms, and it is difficult to immobilize simultaneously Pb and As in soil. The objective of this study is to determine the effects of water management including flooding (FL), alternate wetting and drying (AWD) and dry farming (DF) combined with addition of phosphate (P) on the accumulation of Pb and As in rice. Our results showed that Pb accumulated in root during vegetative stage, and most of As in root was transported to the above ground parts during the reproductive stage. Pb was evenly distributed in grains, and As was mostly accumulated in bran and aleurone layer. Water management had a reverse effect on the accumulation of Pb and As in rice. However, the effects of P on arid soil environment and Pb, As accumulation in rice were stronger than that in flooded soil. Application of P under AWD treatment could maintain a similar quantity of Fe plaque with flooding, decrease the availability of Pb in rhizosphere soil, reduce Pb and As accumulation in root, and result in the reduction of Pb and As accumulation in grains by 86% and 66% respectively. Besides, our study also found that flooding or AWD during vegetative stage facilitated the formation of iron plaque. In conclusion, AWD combined with P application could maintain a relatively lower concentrations of Pb and As in grains.

Biomineralization of Cd2+ and inhibition on rhizobacterial Cd mobilization function by Bacillus Cereus to improve safety of maize grains

Reducing cadmium (Cd) bioavailability and rhizobacterial Cd mobilization functions in the rhizosphere via the inoculation of screened microbial inoculum is an environmental-friendly strategy to improve safety of crop grains. In this study, Bacillus Cereus, a model Cd resistant strain, was selected to explore its effects on Cd bioavailability and uptake, bacterial metabolic functions related to Cd mobilization. Results indicated that inoculation of Bacillus Cereus in maize roots of sand pot with water-soluble Cd (0.06-0.15 mg/kg) and soil pot with high Cd-contaminated soil (total Cd: 2.33 mg/kg; Cd extracted by NH₄NO₃: 38.6 μg/kg) could decrease water-soluble Cd ion concentration by 7.7-30.1% and Cd extracted with NH₄NO₃ solution by 7.8-22.5%, inducing Cd concentrations in maize grains reduced by 10.6-39.9% and 17.4-38.6%, respectively. Even for a single inoculation in soil, Cd concentration in maize grains still satisfy food safety requirements (Cd content: 0.1 mg/kg dry weight) due to its successful colonization on root surface of maize. Bacillus Cereus could enrich more plant growth promotion bacteria (PGPB) and down-regulate the expression of genes related to bacterial motility, membrane transports, carbon and nitrogen metabolism in the rhizosphere soil, decreasing Cd bioavailability in soil. Approximately 80% Cd²⁺ in media was transferred into intracellular, meanwhile Cd salts (sulfide and/or phosphate) were produced in Bacillus Cereus through biomineralization process. Overall, this study could provide a feasible method for improving safety of maize grains via the inoculation of Bacillus Cereus under Cd pollution.

Arsenate toxicity to the marine microalga Chlorella vulgaris increases under phosphorus-limited condition

To understand the arsenic (As) toxicity to aquatic organisms in the phosphors-polluted aquatic ecosystem, the growth, the physiological response of Chlorella vulgaris exposed to As (V), and the underlying mechanism were investigated under different phosphorus (P) levels (0, 6, 13, 32 μM). Results showed that As toxicity to the marine microalga C. vulgaris was enhanced under P-limited condition. P supply distinctly altered the effect of As on the light-harvesting efficiency of photosystem. Insufficient P supply also resulted in an enhanced level of membrane integrity loss, which probably facilitated As entering cells and led to stronger toxicity to C. vulgaris under low P supply. At high concentrations of As, the relative superoxide dismutase (SOD) activity was significantly enhanced. When phosphorus was limited, the activation of peroxidase (POD) was significantly enhanced after adding As (V). When intracellular SOD activity was at its highest level, the level of membrane peroxidation (MDA) was also at the highest level, and membrane peroxidation level was positively related to the level of membrane integrity loss (Pearson R²=0.8977). These results suggested that alternation of light-harvesting efficiency of photosystem and As-induced oxidative damage, resulting in membrane peroxidation and integrity loss, were the possible mechanism of As toxicity to C. vulgaris. This study provided insight into the understanding of As toxicity to algae in the eutrophication aquatic system and the potential application of algae in As remediation.

Usage of Si, P, Se, and Ca Decrease Arsenic Concentration/Toxicity in Rice, a Review

Rice is one of the most important routes for arsenic to enter the human food chain and threatens more than half of the world’s population. In addition, arsenic-contaminated soils and waters increase the concentration of this element in various tissues of rice plants. Thus, direct or indirect—infecting livestock and poultry—increase diseases such as respiratory diseases, gastrointestinal tract, liver, and cardiovascular diseases, cancer, and ultimately death in the long term. Therefore, finding different ways to reduce the uptake and transfer of arsenic by rice would reduce the contamination of rice plants with this dangerous element and improve animal and human nutrition and ultimately disease and mortality. In this article, we aim to take a small step in improving sustainable life on earth by referring to the various methods that researchers have taken to reduce rice contamination by arsenic in recent years. Adding micronutrients and macronutrients as fertilizer for rice is one way to improve this plant’s growth and health. In this study, by examining two types of macronutrients and two types of micronutrients, their role in reducing arsenic toxicity and absorption was investigated. Therefore, both calcium and phosphorus were selected from the macronutrients, and selenium and silicon were selected from the micronutrients, whose roles in previous studies had been investigated.