Cadmium(Cd^(2+))exhibits pronounced phytotoxicity and poses significant risks to human health through bioaccumulation in agricultural products.This study investigates the mitigative effects of foliar-applied nano-moly...Cadmium(Cd^(2+))exhibits pronounced phytotoxicity and poses significant risks to human health through bioaccumulation in agricultural products.This study investigates the mitigative effects of foliar-applied nano-molybdenum particles(MoNPs)on Cd accumulation and growth rates in rice(Oryza sativa).Our findings demonstrate that MoNPs application effectively alleviates Cd-induced root growth suppression and reduces Cd deposition in root cell walls,through MoNPs-mediated attenuation of Cd-induced elevation of pectin content.Through cross-sectional analysis combined with ROS-specific fluorescent probes revealed a spatial pattern of Cd-induced H_(2)O_(2)accumulation,with strongest signals observed in the apoplastic regions of root elongation and maturation zones,with minimal accumulation in meristematic regions.This oxidative burst was significantly mitigated by MoNPs treatment,which enhanced plasma membrane(PM)-localized respiratory burst oxidase homolog(RBOH)activity via transcriptional upregulation of OsRBOH genes.Furthermore,foliar MoNPs application activated the ascorbate–glutathione(ASA-GSH)cycle through selective upregulation of OsAPXs and OsGRs,enhancing cellular capacity for H_(2)O_(2)detoxification.These coordinated mechanisms collectively suggest that MoNPs treatment offers dual protection against Cd toxicity by 1)reducing Cd bioavailability in plant tissues and 2)counteracting Cd-induced oxidative damage,thereby effectively ameliorating root growth inhibition under Cd stress.展开更多
Soil secondary minerals are important scavengers of rare earth elements(REEs) in soils and thus affect geochemical behavior and occurrence of REEs. The fractionation of REEs is a common geochemical phenomenon in soils...Soil secondary minerals are important scavengers of rare earth elements(REEs) in soils and thus affect geochemical behavior and occurrence of REEs. The fractionation of REEs is a common geochemical phenomenon in soils but has received little attention, especially fractionation induced by secondary minerals. In this study, REEs(La to Lu and Y) associated with soil-abundant secondary minerals Fe-, Al-, and Mn-oxides in 196 soil samples were investigated to explore the fractionation and anomalies of REEs related to the minerals. The results show right-inclined chondrite-normalized REE patterns for La–Lu in soils subjected to total soil digestion and partial soil extraction. Light REEs(LREEs) enrichment features were negatively correlated with a Eu anomaly and positively correlated with a Ce anomaly. The fractionation between LREEs and heavy REEs(HREEs) was attributed to the high adsorption affinity of LREEs to secondary minerals and the preferred activation/leaching of HREEs.The substantial fractions of REEs in soils extracted byoxalate and Dithionite-Citrate-Bicarbonate buffer solutions were labile(10 %–30 %), which were similar to the mass fraction of Fe(10 %–20 %). Furthermore, Eu was found to be more mobile than the other REEs in the soils, whereas Ce was less mobile. These results add to our understanding of the distribution and geochemical behavior of REEs in soils, and also help to deduce the conditions of soil formation from REE fractionation.展开更多
Nitrate(NO3^(-))is known to be actively involved in the processes of mineralization and heavy metal transformation;however,it is unclear whether and how it affects the bioavailability of antimony(Sb)in paddy soils and...Nitrate(NO3^(-))is known to be actively involved in the processes of mineralization and heavy metal transformation;however,it is unclear whether and how it affects the bioavailability of antimony(Sb)in paddy soils and subsequent Sb accumulation in rice.Here,the effects of NO3^(-)on Sb transformation in soil-rice system were investigated with pot experiments over the entire growth period.Results demonstrated that NO3^(-)reduced Sb accumulation in brown rice by 15.6%compared to that in the control.After amendment with NO3^(-),the Sb content in rice plants increased initially and then gradually decreased(in roots by 46.1%).During the first 15 days,the soil p H increased,the oxidation of Sb(Ⅲ)and sulfides was promoted,but the reduction of iron oxide minerals was inhibited,resulting in the release of adsorbed and organic-bound Sb from soil.The microbial arsenite-oxidizing marker gene aox B played an important role in Sb(Ⅲ)oxidation.From days 15 to 45,after NO3^(-)was partially consumed,the soil p H decreased,and the reductive dissolution of Fe(Ⅲ)-bearing minerals was enhanced;consequently,iron oxide-bound Sb was transformed into adsorbed and dissolved Sb species.After day 45,NO3^(-)was completely reduced,Sb(V)was evidently reduced to Sb(Ⅲ),and green rust was generated gradually.Thus,the available Sb decreased due to its enhanced affinity for iron oxides.Moreover,NO3^(-)inhibited the reductive dissolution of iron minerals,which ultimately caused low Sb availability.Therefore,NO3^(-)can chemically and biologically reduce the Sb availability in paddy soils and alleviate Sb accumulation inrice.This study provides a potential strategy for decreasing Sb accumulation in rice in the Sb-contaminated sites.展开更多
Zero-valent iron(ZVI)is a promising material for the remediation of Cd-contaminated paddy soils.However,the effects of ZVI added during flooding or drainage processes on cadmium(Cd)retention remain unclear.Herein,Cd-c...Zero-valent iron(ZVI)is a promising material for the remediation of Cd-contaminated paddy soils.However,the effects of ZVI added during flooding or drainage processes on cadmium(Cd)retention remain unclear.Herein,Cd-contaminated paddy soil was incubated for 40days of flooding and then for 15 days of drainage,and the underlying mechanisms of Cd immobilization coupled with Fe/S/N redox processes were investigated.The addition of ZVI to the flooding process was more conducive to Cd immobilization.Less potential available Cd was detected by adding ZVI before flooding,which may be due to the increase in paddy soil pH and newly formed secondary Fe minerals.Moreover,the reductive dissolution of Fe minerals promoted the release of soil colloids,thereby increasing significantly the surface sites and causing Cd immobilization.Additionally,the addition of ZVI before flooding played a vital role in Cd retention after soil drainage.In contrast,the addition of ZVI in the drainage phase was not conducive to Cd retention,which might be due to the rapid decrease in soil pH that inhibited Cd adsorption and further immobilization on soil surfaces.The findings of this study demonstrated that Cd availability in paddy soil was largely reduced by adding ZVI during the flooding period and provide a novel insight into the mechanisms of ZVI remediation in Cd-contaminated paddy soils.展开更多
Foliar application of Si can generally reduce As translocation from roots to shoots in rice;however, it does not always work, particularly under high As stress. Here, the effects of foliar application of nanoscale sil...Foliar application of Si can generally reduce As translocation from roots to shoots in rice;however, it does not always work, particularly under high As stress. Here, the effects of foliar application of nanoscale silica sol on As accumulation in rice were investigated under low(2 μmol/L) and high(8 μmol/L) arsenite stress. The results revealed that foliar Si application significantly decreased the As concentration in shoots under low arsenite stress, but showed different effects under high arsenite stress after 7 days of incubation. The reduction in root-to-shoot As translocation under the 2 As + Si treatment was related to the down-regulation of Os Lsi1 and Os Lsi2 expression and up-regulation of Os ABCC1 expression in roots. In the 8 As + Si treatment, the expressions of Os Lsi1, Os Lsi2, and Os ABCC1 were significantly promoted, which resulted in substantially higher As accumulation in both the roots and shoots. In the roots, As predominantly accumulated in the symplasts(90.6%–98.3%), in which the majority of As was sequestered in vacuoles(79.0%–94.0%) under both levels of arsenite stress. Compared with that of the 8 As treatment, the 8 As + Si treatment significantly increased the As concentration in cell walls, but showed no difference in the vacuolar As concentration, which remained constant at approximately 69.1–71.7 mg/kg during days 4–7. It appeared that the capacity of root cells to sequester As in the vacuoles had a threshold, and the excess As tended to accumulate in the cell walls and transfer to the shoots via apoplasts under high arsenite stress. This study provides a better understanding of the different effects of foliar Si application on As accumulation in rice from the view of arseniterelated gene expression and As subcellular distribution in roots.展开更多
Silicon(Si)has been shown to alleviate Cd stress in rice.Here,we investigated the beneficial effects of foliar Si in an indica rice Huanghuazhan(HHZ).Our results showed that foliar Si in-creases the dry weight and dec...Silicon(Si)has been shown to alleviate Cd stress in rice.Here,we investigated the beneficial effects of foliar Si in an indica rice Huanghuazhan(HHZ).Our results showed that foliar Si in-creases the dry weight and decreases Cd translocation in Cd-exposed rice at the grain-filling stage only,implying that the filling stage is critical for foliar Si to reduce Cd accumulation.We also investigated the transcriptomics in flag leaves(FLs),spikelets(SPs),and node Is(NIs)of Cd-exposed HHZ after foliar Si application at the filling stage.Importantly,the gene expression profiles associated with the Si-mediated alleviation of Cd stress were tissue spe-cific,while shared pathways were mediated by Si in Cd-exposed rice tissues.Furthermore,after the Si treatment of Cd-exposed rice,the ATP-binding cassette(ABC)-transporters were mostly upregulated in FL and SP,while the bivalent cation transporters were mostly down-regulated in FL and NI,possibly helping to reduce Cd accumulation.The genes associated with essential nutrient transporters,carbohydrate and secondary metabolite biosynthesis,and cytochrome oxidase activity were mostly upregulated in Cd-exposed FL and SP,which may help to alleviate oxidative stress and improve plant growth under Cd exposure.Inter-estingly,genes responsible for signal transduction were negatively regulated in FL,but pos-itively regulated in SP,by foliar Si.Our results provide transcriptomic evidence that foliar Si plays an active role in alleviating the effects of Cd exposure in rice.In particular,foliar Si may alter the expression pattern of genes associated with transport,biosynthesis and metabolism,and oxidation reduction.展开更多
The inessential heavy metal/loids cadmium(Cd)and arsenic(As),which often co-occur in polluted paddy soils,are toxic to rice.Silicon(Si)treatment is known to reduce Cd and As toxicity in rice plants.To better understan...The inessential heavy metal/loids cadmium(Cd)and arsenic(As),which often co-occur in polluted paddy soils,are toxic to rice.Silicon(Si)treatment is known to reduce Cd and As toxicity in rice plants.To better understand the shared mechanisms by which Si alleviates Cd and As stress,rice seedlings were hydroponically exposed to Cd or As,then treated with Si.The addition of Si significantly ameliorated the inhibitory effects of Cd and As on rice seedling growth.Si supplementation decreased Cd and As translocation from roots to shoots,and significantly reduced Cd-and As-induced reactive oxygen species generation in rice seedlings.Transcriptomics analyses were conducted to elucidate molecular mechanisms underlying the Si-mediated response to Cd or As stress in rice.The expression patterns of the differentially expressed genes in Cd-or As-stressed rice roots with and without Si application were compared.The transcriptomes of the Cd-and As-stressed rice roots were similarly and profoundly reshaped by Si application,suggesting that Si may play a fundamental,active role in plant defense against heavy metal/loid stresses by modulating whole genome expression.We also identified two novel genes,0s01g0524500 and 0s06g0514800,encoding a myeloblastosis(MYB)transcription factor and a thionin,respectively,which may be candidate targets for Si to alleviate Cd and As stress in rice,as well as for the generation of Cd-and/or As-resistant plants.This study provides valuable resources for further clarification of the shared molecular mechanisms underlying the Si-mediated alleviation of Cd and As toxicity in rice.展开更多
The flooding and drainage of paddy fields has great effects on the transformation of heavy metals, however, the transformation of Cr in basalt-derived paddy soil with high geological background values was less recogni...The flooding and drainage of paddy fields has great effects on the transformation of heavy metals, however, the transformation of Cr in basalt-derived paddy soil with high geological background values was less recognized. The typical basalt-derived paddy soil was incubated under alternating redox conditions. The Cr fractions and the dynamics of Fe/N/S/C were examined. The HCl-extractable Cr increased under anaerobic condition and then decreased during aerobic stage. The UV-vis spectra of the supernatant showed that amounts of colloids were released under anaerobic condition, and then re-aggregated during aerobic phase. The scanning transmission electron microscopy(TEM) and X-ray photoelectron spectroscopy(XPS) revealed that Fe oxides were reduced and became dispersed during anaerobic stage, whereas Fe(Ⅱ) was oxidized and recrystallized under aerobic condition. Based on these results, a kinetic model was established to further distinguish the relationship between the transformation of Cr and Fe. During anaerobic phase, the reduction of Fe(Ⅲ) oxides not only directly released the structurally bound Cr, but also enhanced the breakdown of soil aggregation and dissolution of organic matter causing indirect mobilization of Cr. During aerobic phase, the oxidation of Fe (Ⅱ) and further recrystallization of newly formed Fe(Ⅲ) oxides might induce the re-aggregation of soil colloids and further incorporation of Cr. In addition,the kinetic model of Cr and Fe transformation was further verified in the pot experiment.The model-based findings demonstrated that the Cr transformation in the basalt-derived paddy soil with high geological background values was highly driven by redox sensitive iron cycling.展开更多
Antimony(Sb)contamination in paddy fields can lead to its accumulation in rice grains,posing a threat to food safety.To address this issue,the combined use of zero-valent iron(ZVI)and biochar(BC)were applied to decrea...Antimony(Sb)contamination in paddy fields can lead to its accumulation in rice grains,posing a threat to food safety.To address this issue,the combined use of zero-valent iron(ZVI)and biochar(BC)were applied to decrease the uptake of Sb in Sb-polluted soils,and their effects on Sb uptake from soil to rice grains were investigated.Our results showed that the combination treatment of 0.05%ZVI and 0.095%BC resulted in a significant decrease(42.8%)in Sb accumulation in rice grains that was comparably more efficient than that by 0.05%ZVI(decrease of 15.8%Sb accumulation)or 0.095%BC(decrease of 12.7%Sb accumulation)alone,demonstrating the synergistic effect of ZVI and BC on mitigating Sb uptake by rice plants.ZVI presence resulted in the formation of iron oxides in the soil and on root surfaces,and the S^(2-)/S_(2)^(2-)ascent also increased by 58.7%on day 75 compared with that of the control,facilitating the reduction of Sb(Ⅴ)to less mobile Sb(Ⅲ),thereby decreasing Sb accumulation in rice plants.BC initially increased themobility of Sb owing to its alkaline nature,whereas the electron shuttle properties of BC contributed to a decrease in Sbmobility.The abundance of the arsenite-reducing gene arrA ultimately increased by 203.2% on day 120 compared with the initial phase on day 5,and BC caused a remarkable increase in arrA gene abundance.This study revealed the synergistic mechanisms by combining ZVI and BC to mitigate Sb uptake by rice,which may be useful for the sustainable remediation of contaminated rice paddies.展开更多
Paddy soil and irrigation water are commonly contaminated with hexavalent chromium[Cr(Ⅵ)]near urban industrial areas,thereby threatening the safety of agricultural products and human health.In this study,we develop a...Paddy soil and irrigation water are commonly contaminated with hexavalent chromium[Cr(Ⅵ)]near urban industrial areas,thereby threatening the safety of agricultural products and human health.In this study,we develop a porous and high specific area bone char(BC)to support nanoscale zero-valent iron(n ZVI)and apply it to remediate Cr(Ⅵ)pollution in water and paddy soil under anaerobic conditions.The batch experiments reveal that BC/n ZVI exhibits a higher removal capacity of 516.7 mg/(g·n ZVI)for Cr(Ⅵ)than n ZVI when normalized to the actual n ZVI content,which is 2.8 times that of n ZVI;moreover,the highest n ZVI utilization is the n ZVI loading of 15%(BC/n ZVI15).The Cr(Ⅵ)removal efficiency of BC/n ZVI15 decreases with increasing p H(4–10).Coexisting ions(phosphate and carbonate)and humic acid can inhibit the removal of Cr(Ⅵ)with BC/n ZVI15.Additionally,BC exhibits a strong advantage in promoting Cr(Ⅵ)removal by n ZVI compared to the widely used biochar and activated carbon.Our results demonstrate that reduction and coprecipitation are the dominant Cr(Ⅵ)removal mechanisms.Furthermore,BC/n ZVI15 shows a significantly higher reduction and removal efficiency as well as a strong anti-interference ability for Cr(Ⅵ)in paddy soil,as compared to n ZVI.These findings provide a new effective material for remediating Cr(Ⅵ)pollution from water and soil.展开更多
The OsLCD gene,which has been implicated in cadmium (Cd) accumulation in rice,might be a useful target for CRISPR/Cas9 editing.However,the effects of Os LCD gene editing on Cd accumulation,plant growth,and yield trait...The OsLCD gene,which has been implicated in cadmium (Cd) accumulation in rice,might be a useful target for CRISPR/Cas9 editing.However,the effects of Os LCD gene editing on Cd accumulation,plant growth,and yield traits remain unknown.Here,we used CRISPR/Cas9to generate oslcd single mutants from indica and japonica rice cultivars.We also generated osnramp5 single mutants and oslcd osnramp5 double mutants in the indica background.When grown in Cd-contaminated paddy soils,all oslcd single mutants accumulated less Cd than the wild types (WTs).Consistent with this,oslcd single mutants grown in Cd-contaminated hydroponic culture accumulated significantly less Cd in the shoots as compared to WTs.This decrease in accumulation probably resulted from the reduction of Cd translocation under Cd stress.Oxidative damage also decreased,and plant growth increased in all oslcd single mutant seedlings as compared to WTs in the presence of Cd.Plant growth and most yield traits,as well essential element concentrations in rice seedling shoots,brown rice,and rice straw,were similar between oslcd single mutants and WTs.In the presence of Cd,Cd concentrations in the brown rice and shoots of oslcd osnramp5 double mutants were significantly decreased compared with WTs as well as osnramp single mutants.Our results suggested that OsL CD knockout may reduce Cd accumulation alone or in combination with other knockout mutations in a variety of rice genotypes;unlike Os Nramp5 mutations,Os LCD knockout did not reduce essential element contents.Therefore,Os LCD knockout might be used to generate low-Cd rice germplasms.展开更多
1.Introduction Agricultural soil pollution is a major threat affecting soil health and the ability of soil to yield safe and sufficient food;thus,it is a barrier to the goal of zero hunger worldwide[1].The food defici...1.Introduction Agricultural soil pollution is a major threat affecting soil health and the ability of soil to yield safe and sufficient food;thus,it is a barrier to the goal of zero hunger worldwide[1].The food deficiency problem continues to grow,particularly under the current atmosphere of global tension.United Nations(UN)organizations.展开更多
While the transformation of antimony(Sb) in paddy soil has been previously investigated, the biogeochemical processes of highly chemical active Sb in the soil remain poorly understood. In addition, there is a lack of ...While the transformation of antimony(Sb) in paddy soil has been previously investigated, the biogeochemical processes of highly chemical active Sb in the soil remain poorly understood. In addition, there is a lack of quantitative understanding of Sb transformation in soil. Therefore, in this study, the kinetics of exogenous Sb in paddy soils were investigated under anaerobic and aerobic incubation conditions. The dissolved Sb(V) and the Sb(V) extracted by diffusive gradient technique decreased under anaerobic conditions and then increased under aerobic conditions. The redox reaction of Sb occurred, and Sb bioavailability significantly decreased after 55 days of incubation. The kinetics of Fe and the scanning transmission electron microscopy analysis revealed that the Fe oxides were reduced and became dispersed under anaerobic conditions, whereas they were oxidized and re-aggregated during the aerobic stage. In addition, the redox processes of sulfur and nitrogen were detected under both anaerobic and aerobic conditions. Based on these observations, a simplified kinetic model was established to distinguish the relative contributions of the transformation processes. The bioavailability of Sb was controlled by immobilization as a result of S reduction and by mobilization as a result of Fe reductive dissolution and S oxidation, rather than the p H. These processes coupled with the redox reaction of Sb jointly resulted in the complex behavior of Sb transformation under anaerobic and aerobic conditions. The model-based method and findings of this study provide a comprehensive understanding of the Sb transformation in a complex soil biogeochemical system under changing redox conditions.展开更多
The membrane-associated c-type cytochromes(c-Cyts) have been well known as the key enzymes mediating extracellular electron transfer to terminal electron acceptors, resulting in biogeochemical elemental transformation...The membrane-associated c-type cytochromes(c-Cyts) have been well known as the key enzymes mediating extracellular electron transfer to terminal electron acceptors, resulting in biogeochemical elemental transformation, contaminant degradation, and nutrient cycling. Although c-Cyts-mediated metal reduction or oxidation have been mainly investigated with the purified proteins of metal reducing/oxidizing bacteria, the in vivo behavior of c-Cyts is still unclear, given the difficulty in measuring the proteins of intact cells. Fortunately, the in situ spectroscopy would be ideal for measuring the reaction kinetics of c-Cyts in intact cells under noninvasive physiological conditions. It can also help the establishment of kinetic/thermodynamic models of extracellular electron transfer processes, which are essential to understand the electron transfer mechanisms at the molecular scale. This review briefly summarizes the current advances in spectral methods for examining the c-Cyts in intact cells of dissimilatory metal reducing bacteria and Fe(Ⅱ)-oxidizing bacteria.展开更多
Iron oxidation is a prevalent and important biogeochemical process in paddy soil,but little is known about whether and how microbially mediated iron oxidation is coupled with carbon assimilation,particularly under mic...Iron oxidation is a prevalent and important biogeochemical process in paddy soil,but little is known about whether and how microbially mediated iron oxidation is coupled with carbon assimilation,particularly under microaerobic conditions.Here,we investigated kinetics of CO_2 assimilation and Fe(Ⅱ)oxidation in an incubation experiment with paddy soil under suboxic conditions,and profiled the associated microbial community using DNA-stable isotope probing and 16S r RNA gene-based sequencing.The results showed that CO_2 assimilation and Fe(II)oxidation in the gradient tubes were predominantly mediated by the microbes enriched in the paddy soil,primarily Azospirillum and Magnetospirillum,as their relative abundances were higher in the^( 13)C heavy fractions compared to^( 12)C heavy fractions.This study provided direct evidence of chemoautotrophic microaerophiles linking iron oxidation and carbon assimilation at the oxic–anoxic interface in the paddy soil ecosystem.展开更多
Mercury(Hg)is one of the most dangerous contaminants and has sparked global concern since it poses a health risk to humans when consumed through rice.Sulfur(S)is a crucial component for plant growth,and S may reduce H...Mercury(Hg)is one of the most dangerous contaminants and has sparked global concern since it poses a health risk to humans when consumed through rice.Sulfur(S)is a crucial component for plant growth,and S may reduce Hg accumulation in rice grains.However,the detailed effects of S and the mechanisms underlying S-mediated responses in Hg-stressed rice plants remain unclear.Currently,to investigate the effects of S addition on rice growth,Hg accumulation,physiological indexes,and gene expression profiles,rice seedlings were hydroponically treated with Hg(20μmol/L Hg Cl_(2))and Hg plus elemental sulfur(100 mg/L).S application significantly reduced Hg accumulation in Hg-stressed rice roots and alleviated the inhibitory effects of Hg on rice growth.S addition significantly reduced Hg-induced reactive oxygen species generation,membrane lipid peroxidation levels,and activities of antioxidant enzymes while increasing glutathione content in leaves.Transcriptomic analysis of roots identified 3,411,2,730,and 581 differentially expressed genes in the control(CK)vs.Hg,CK vs.Hg+S,and Hg vs.Hg+S datasets,respectively.The pathway of S-mediated biological metabolism fell into six groups:biosynthesis and metabolism,expression regulation,transport,stimulus response,oxidation reduction,and cell wall biogenesis.The majority of biological process-related genes were upregulated under Hg stress compared with CK treatment,but downregulated in the Hg+S treatment.The results provide transcriptomic and physiological evidence that S may be critical for plant Hg stress resistance and will help to develop strategies for reduction or phytoremediation of Hg contamination.展开更多
We investigated the reduction of lepidocrocite(γ-FeOOH) by Shewanella oneidensis MR-1 in the presence and absence of Cd. The results showed that Cd^(2+) retarded microbial reduction of γ-Fe OOH and avoided formation...We investigated the reduction of lepidocrocite(γ-FeOOH) by Shewanella oneidensis MR-1 in the presence and absence of Cd. The results showed that Cd^(2+) retarded microbial reduction of γ-Fe OOH and avoided formation of magnetite. The inhibitory effect on γ-Fe OOH transformation may not result from Cd^(2+) toxicity to the bacterium; it rather was probably due to competitive adsorption between Cd^(2+) and Fe^(2+) on γ-Fe OOH as its surface reduction catalyzed by adsorbed Fe^(2+) was eliminated by adsorption of Cd^(2+).展开更多
In modern society,the ceaselessly increasing demand for clean energy has spurred the exploration of novel low-carbon technologies.Nuclear power has proven its effectiveness in resolving the energy crisis.With the rapi...In modern society,the ceaselessly increasing demand for clean energy has spurred the exploration of novel low-carbon technologies.Nuclear power has proven its effectiveness in resolving the energy crisis.With the rapid expansion of nuclear power facilitating humanity’s shift towards a low-carbon energy society,proper management of nuclear waste generated by nuclear plants has become crucial for minimizing environmental impacts and alleviating public concerns.To promote the development of removal techniques and control strategies for radionuclides in the wastewater,we have organized a special topic on“Nuclear Environment Advances”in National Science Open(NSO).We have invited nine scientists from different fields to present their latest research findings and prospective analyses of radionuclides in the environment systematically.Continuous attention to nuclear safety,strict regulatory supervision,and enhanced emergency response measures are of great significance for reducing the environmental impact during operation of nuclear plants.Assessing the impacts of radiation on various organisms to understand the toxicity mechanisms,potential health effects,and dose-response relationships related to radionuclide exposure can help assess the potential consequences of radionuclide leakage and providing information for decision making in risk management.Huang et al.[1]provide an overview and highlight the importance of environmental toxicology in the risk assessment and management of radionuclides,suggesting that both chemical toxicity and radiotoxicity are indispensable in evaluating the toxicology of radionuclides.Concerned about the absence of environmental pollution standards,they suggest that future research should focus on the long-term impacts of these radionuclides on human health,especially the risks related to low-dose radiation exposure.In the nuclear fuel cycle,radioactive iodine is one of the major gaseous contaminants due to nuclear energy utilization,posing threats to the environment and public health.Covalent Organic Frameworks(COFs)are as a novel class of crystalline porous materials that has been proven promising for iodine capture.Chen et al.[2]systematically analyze the structure-activity relationship of COFs in iodine adsorption by evaluating the critical factors like pore structure,electron-rich groups,and ionic sites influencing adsorption performance.展开更多
Globally,nitrogen(N)fertilizer demand is expected to reach 112 million tonnes to support food production for about 8 billion people.However,more than half of the N fertilizer is lost to the environment with impacts on...Globally,nitrogen(N)fertilizer demand is expected to reach 112 million tonnes to support food production for about 8 billion people.However,more than half of the N fertilizer is lost to the environment with impacts on air,water and soil quality,and biodiversity.Importantly,N loss to the environment contributes to greenhouse gas emissions and climate change.Nevertheless,where N fertilizer application is limited,severe depletion of soil fertility has become a major constraint to sustainable agriculture.To address the issues of low fertilizer N use efficiency(NUE),biochar-based N fertilizers(BBNFs)have been developed to reduce off-site loss and maximize crop N uptake.These products are generally made through physical mixing of biochar and N fertilizer or via coating chemical N fertilizers such as prilled urea with biochar.This review aims to describe the manufacturing processes of BBNFs,and to critically assess the effects of the products on soil properties,crop yield and N loss pathways.展开更多
In paddy fields, the opposing transformation of arsenic (As) and cadmium (Cd) poses many challenges for their simultaneous remediation.In our previous study,we reported that combined biochar and zero-valent iron(ZVI)a...In paddy fields, the opposing transformation of arsenic (As) and cadmium (Cd) poses many challenges for their simultaneous remediation.In our previous study,we reported that combined biochar and zero-valent iron(ZVI)amendment had great potential for the simultaneous alleviation of As and Cd bioavailability in contaminated acid paddy soil.In this study,an As-and Cd-contaminated alkaline paddy soil was further studied,and the same ZVI-biochar mixtures amendments were applied to evaluate the impact of the mixtures on As and Cd transformation and translocation in the soil-rice system by performing pot experiments with rice.In line with our previous study,the ZVI-biochar composites significantly reduced As and Cd accumulation in different rice tissues,leading to a 42%and 47%decrease in rice grain As and Cd levels,respectively,compared with the control values.The ZVI-biochar mixtures exhibited synergistic effects of biochar and ZVI by enhancing the transformation of bioavailable As and Cd fractions into less bioavailable fractions,and by increasing iron plaque formation to reduce As and Cd bioavailability.Although the bioaccumulation and translocation factors of As and Cd in alkaline paddy soil were generally lower than those in acid paddy soil,particularly in the presence of the ZVI-biochar mixtures,the grain As and Cd levels did not achieve the desired food safety standard levels,probably related to the high soil As content and the small changes in soil pH.Nevertheless,for treating lightly and moderately contaminated paddy soils,ZVI-biochar mixtures can still be a good choice in the future.展开更多
基金funding support,including the National Natural Science Foundation of China(W2421108,42377042,32402672)the Basic and Applied Research Foundation of Guangdong province(2023A1515110151,2024A1515140040)+1 种基金the China Postdoctoral Science Foundation(2024 M750949)the Science and Technology Innovation Strategy Fund of Guangdong province(pdjh2024a390).
文摘Cadmium(Cd^(2+))exhibits pronounced phytotoxicity and poses significant risks to human health through bioaccumulation in agricultural products.This study investigates the mitigative effects of foliar-applied nano-molybdenum particles(MoNPs)on Cd accumulation and growth rates in rice(Oryza sativa).Our findings demonstrate that MoNPs application effectively alleviates Cd-induced root growth suppression and reduces Cd deposition in root cell walls,through MoNPs-mediated attenuation of Cd-induced elevation of pectin content.Through cross-sectional analysis combined with ROS-specific fluorescent probes revealed a spatial pattern of Cd-induced H_(2)O_(2)accumulation,with strongest signals observed in the apoplastic regions of root elongation and maturation zones,with minimal accumulation in meristematic regions.This oxidative burst was significantly mitigated by MoNPs treatment,which enhanced plasma membrane(PM)-localized respiratory burst oxidase homolog(RBOH)activity via transcriptional upregulation of OsRBOH genes.Furthermore,foliar MoNPs application activated the ascorbate–glutathione(ASA-GSH)cycle through selective upregulation of OsAPXs and OsGRs,enhancing cellular capacity for H_(2)O_(2)detoxification.These coordinated mechanisms collectively suggest that MoNPs treatment offers dual protection against Cd toxicity by 1)reducing Cd bioavailability in plant tissues and 2)counteracting Cd-induced oxidative damage,thereby effectively ameliorating root growth inhibition under Cd stress.
基金funded by the National Natural Science Foundation of China(41420104007,41330857,and 41673135)the Guangdong Natural Science Foundation of China(S2013050014266)the One Hundred Talents Programme of The Chinese Academy of Sciences
文摘Soil secondary minerals are important scavengers of rare earth elements(REEs) in soils and thus affect geochemical behavior and occurrence of REEs. The fractionation of REEs is a common geochemical phenomenon in soils but has received little attention, especially fractionation induced by secondary minerals. In this study, REEs(La to Lu and Y) associated with soil-abundant secondary minerals Fe-, Al-, and Mn-oxides in 196 soil samples were investigated to explore the fractionation and anomalies of REEs related to the minerals. The results show right-inclined chondrite-normalized REE patterns for La–Lu in soils subjected to total soil digestion and partial soil extraction. Light REEs(LREEs) enrichment features were negatively correlated with a Eu anomaly and positively correlated with a Ce anomaly. The fractionation between LREEs and heavy REEs(HREEs) was attributed to the high adsorption affinity of LREEs to secondary minerals and the preferred activation/leaching of HREEs.The substantial fractions of REEs in soils extracted byoxalate and Dithionite-Citrate-Bicarbonate buffer solutions were labile(10 %–30 %), which were similar to the mass fraction of Fe(10 %–20 %). Furthermore, Eu was found to be more mobile than the other REEs in the soils, whereas Ce was less mobile. These results add to our understanding of the distribution and geochemical behavior of REEs in soils, and also help to deduce the conditions of soil formation from REE fractionation.
基金the National Key Research and Development Program of China(Nos.2017YFD0801002,2018YFF0213403)GDAS’Project of Science and Technology Development(No.2020GDASYL-20200103076)China Postdoctoral Science Foundation(No.2019M652834)。
文摘Nitrate(NO3^(-))is known to be actively involved in the processes of mineralization and heavy metal transformation;however,it is unclear whether and how it affects the bioavailability of antimony(Sb)in paddy soils and subsequent Sb accumulation in rice.Here,the effects of NO3^(-)on Sb transformation in soil-rice system were investigated with pot experiments over the entire growth period.Results demonstrated that NO3^(-)reduced Sb accumulation in brown rice by 15.6%compared to that in the control.After amendment with NO3^(-),the Sb content in rice plants increased initially and then gradually decreased(in roots by 46.1%).During the first 15 days,the soil p H increased,the oxidation of Sb(Ⅲ)and sulfides was promoted,but the reduction of iron oxide minerals was inhibited,resulting in the release of adsorbed and organic-bound Sb from soil.The microbial arsenite-oxidizing marker gene aox B played an important role in Sb(Ⅲ)oxidation.From days 15 to 45,after NO3^(-)was partially consumed,the soil p H decreased,and the reductive dissolution of Fe(Ⅲ)-bearing minerals was enhanced;consequently,iron oxide-bound Sb was transformed into adsorbed and dissolved Sb species.After day 45,NO3^(-)was completely reduced,Sb(V)was evidently reduced to Sb(Ⅲ),and green rust was generated gradually.Thus,the available Sb decreased due to its enhanced affinity for iron oxides.Moreover,NO3^(-)inhibited the reductive dissolution of iron minerals,which ultimately caused low Sb availability.Therefore,NO3^(-)can chemically and biologically reduce the Sb availability in paddy soils and alleviate Sb accumulation inrice.This study provides a potential strategy for decreasing Sb accumulation in rice in the Sb-contaminated sites.
基金supported by the National Natural Science Foundation of China(Nos.42277034 and 42207249)the Guangdong Basic and Applied Basic Research Foundation(No.2021A1515110904)+1 种基金the Guangdong Academy of Sciences(GDAS)Project of Science and Technology Development(No.2022GDASZH-2022010105)the Guangdong Foundation for Program of Science and Technology Research(No.2020B1212060048)。
文摘Zero-valent iron(ZVI)is a promising material for the remediation of Cd-contaminated paddy soils.However,the effects of ZVI added during flooding or drainage processes on cadmium(Cd)retention remain unclear.Herein,Cd-contaminated paddy soil was incubated for 40days of flooding and then for 15 days of drainage,and the underlying mechanisms of Cd immobilization coupled with Fe/S/N redox processes were investigated.The addition of ZVI to the flooding process was more conducive to Cd immobilization.Less potential available Cd was detected by adding ZVI before flooding,which may be due to the increase in paddy soil pH and newly formed secondary Fe minerals.Moreover,the reductive dissolution of Fe minerals promoted the release of soil colloids,thereby increasing significantly the surface sites and causing Cd immobilization.Additionally,the addition of ZVI before flooding played a vital role in Cd retention after soil drainage.In contrast,the addition of ZVI in the drainage phase was not conducive to Cd retention,which might be due to the rapid decrease in soil pH that inhibited Cd adsorption and further immobilization on soil surfaces.The findings of this study demonstrated that Cd availability in paddy soil was largely reduced by adding ZVI during the flooding period and provide a novel insight into the mechanisms of ZVI remediation in Cd-contaminated paddy soils.
基金supported by the National Natural Science Foundation of China(No.41877043)the Guangdong Key Re-search and Development Project(No.2019B110207002)+2 种基金the Guangdong Natural Science Funds for Distinguished Young Scholars(No.2017A030306010)the National Key Research and Development Project of China(No.2016YFD08007010)the Guangdong Special Support Plan for High-Level Talents(No.2017TQ04Z511).
文摘Foliar application of Si can generally reduce As translocation from roots to shoots in rice;however, it does not always work, particularly under high As stress. Here, the effects of foliar application of nanoscale silica sol on As accumulation in rice were investigated under low(2 μmol/L) and high(8 μmol/L) arsenite stress. The results revealed that foliar Si application significantly decreased the As concentration in shoots under low arsenite stress, but showed different effects under high arsenite stress after 7 days of incubation. The reduction in root-to-shoot As translocation under the 2 As + Si treatment was related to the down-regulation of Os Lsi1 and Os Lsi2 expression and up-regulation of Os ABCC1 expression in roots. In the 8 As + Si treatment, the expressions of Os Lsi1, Os Lsi2, and Os ABCC1 were significantly promoted, which resulted in substantially higher As accumulation in both the roots and shoots. In the roots, As predominantly accumulated in the symplasts(90.6%–98.3%), in which the majority of As was sequestered in vacuoles(79.0%–94.0%) under both levels of arsenite stress. Compared with that of the 8 As treatment, the 8 As + Si treatment significantly increased the As concentration in cell walls, but showed no difference in the vacuolar As concentration, which remained constant at approximately 69.1–71.7 mg/kg during days 4–7. It appeared that the capacity of root cells to sequester As in the vacuoles had a threshold, and the excess As tended to accumulate in the cell walls and transfer to the shoots via apoplasts under high arsenite stress. This study provides a better understanding of the different effects of foliar Si application on As accumulation in rice from the view of arseniterelated gene expression and As subcellular distribution in roots.
基金This work was financially supported by the National Key Research and Development Project of China(No.2016YFD0800700)the National Natural Science Foundation of China(No.41877143)+2 种基金the Science and Technology Planning Project of Guangdong Province,China(No.2015B020237008)the Guangdong Basic and Applied Basic Research Foundation(No.2020A1515010906)the Special Rural Revitalization Funds of Guangdong Province(No.2021KJ382).
文摘Silicon(Si)has been shown to alleviate Cd stress in rice.Here,we investigated the beneficial effects of foliar Si in an indica rice Huanghuazhan(HHZ).Our results showed that foliar Si in-creases the dry weight and decreases Cd translocation in Cd-exposed rice at the grain-filling stage only,implying that the filling stage is critical for foliar Si to reduce Cd accumulation.We also investigated the transcriptomics in flag leaves(FLs),spikelets(SPs),and node Is(NIs)of Cd-exposed HHZ after foliar Si application at the filling stage.Importantly,the gene expression profiles associated with the Si-mediated alleviation of Cd stress were tissue spe-cific,while shared pathways were mediated by Si in Cd-exposed rice tissues.Furthermore,after the Si treatment of Cd-exposed rice,the ATP-binding cassette(ABC)-transporters were mostly upregulated in FL and SP,while the bivalent cation transporters were mostly down-regulated in FL and NI,possibly helping to reduce Cd accumulation.The genes associated with essential nutrient transporters,carbohydrate and secondary metabolite biosynthesis,and cytochrome oxidase activity were mostly upregulated in Cd-exposed FL and SP,which may help to alleviate oxidative stress and improve plant growth under Cd exposure.Inter-estingly,genes responsible for signal transduction were negatively regulated in FL,but pos-itively regulated in SP,by foliar Si.Our results provide transcriptomic evidence that foliar Si plays an active role in alleviating the effects of Cd exposure in rice.In particular,foliar Si may alter the expression pattern of genes associated with transport,biosynthesis and metabolism,and oxidation reduction.
基金supported by the National Natural Science Foundation of China(No.41877143)the National Key Research and Development Project of China(No.2016YFD0800700)the Science and Technology Planning Project of Guangdong Province(Nos.2015B020237008 and 2015B020207001).
文摘The inessential heavy metal/loids cadmium(Cd)and arsenic(As),which often co-occur in polluted paddy soils,are toxic to rice.Silicon(Si)treatment is known to reduce Cd and As toxicity in rice plants.To better understand the shared mechanisms by which Si alleviates Cd and As stress,rice seedlings were hydroponically exposed to Cd or As,then treated with Si.The addition of Si significantly ameliorated the inhibitory effects of Cd and As on rice seedling growth.Si supplementation decreased Cd and As translocation from roots to shoots,and significantly reduced Cd-and As-induced reactive oxygen species generation in rice seedlings.Transcriptomics analyses were conducted to elucidate molecular mechanisms underlying the Si-mediated response to Cd or As stress in rice.The expression patterns of the differentially expressed genes in Cd-or As-stressed rice roots with and without Si application were compared.The transcriptomes of the Cd-and As-stressed rice roots were similarly and profoundly reshaped by Si application,suggesting that Si may play a fundamental,active role in plant defense against heavy metal/loid stresses by modulating whole genome expression.We also identified two novel genes,0s01g0524500 and 0s06g0514800,encoding a myeloblastosis(MYB)transcription factor and a thionin,respectively,which may be candidate targets for Si to alleviate Cd and As stress in rice,as well as for the generation of Cd-and/or As-resistant plants.This study provides valuable resources for further clarification of the shared molecular mechanisms underlying the Si-mediated alleviation of Cd and As toxicity in rice.
基金supported by the National Natural Science Foundation of China (No. 41807026)China Postdoctoral Science Foundation (No. 2021M700888)+1 种基金GDAS’ Project of Science and Technology Development (No. 2021GDASYL20210302003)the China Agriculture Research System, assigned to Ministry of Finance & Ministry of Agriculture and Rural Affairs。
文摘The flooding and drainage of paddy fields has great effects on the transformation of heavy metals, however, the transformation of Cr in basalt-derived paddy soil with high geological background values was less recognized. The typical basalt-derived paddy soil was incubated under alternating redox conditions. The Cr fractions and the dynamics of Fe/N/S/C were examined. The HCl-extractable Cr increased under anaerobic condition and then decreased during aerobic stage. The UV-vis spectra of the supernatant showed that amounts of colloids were released under anaerobic condition, and then re-aggregated during aerobic phase. The scanning transmission electron microscopy(TEM) and X-ray photoelectron spectroscopy(XPS) revealed that Fe oxides were reduced and became dispersed during anaerobic stage, whereas Fe(Ⅱ) was oxidized and recrystallized under aerobic condition. Based on these results, a kinetic model was established to further distinguish the relationship between the transformation of Cr and Fe. During anaerobic phase, the reduction of Fe(Ⅲ) oxides not only directly released the structurally bound Cr, but also enhanced the breakdown of soil aggregation and dissolution of organic matter causing indirect mobilization of Cr. During aerobic phase, the oxidation of Fe (Ⅱ) and further recrystallization of newly formed Fe(Ⅲ) oxides might induce the re-aggregation of soil colloids and further incorporation of Cr. In addition,the kinetic model of Cr and Fe transformation was further verified in the pot experiment.The model-based findings demonstrated that the Cr transformation in the basalt-derived paddy soil with high geological background values was highly driven by redox sensitive iron cycling.
基金financially supported by the National Natural Science Foundation of China(Nos.42030702,42307014,and 42077354)the Guangdong Foundation for Program of Science and Technology Research(No.2020B1212060048)+7 种基金the China Postdoctoral Science Foundation(No.2022M720847)the GDAS’Project of Science and Technology Development(Nos.2023GDASZH-2023010103,and 2020GDASYL-20200104017)the open competition program of top ten critical priorities of Agricultural Science and Technology Innovation for the 14th Five-Year Plan of Guangdong Province(No.2022SDZG08)Research Project of Hunan Provincial Department of Education(No.21C0788)National Key Technology R&D Program of China(No.2022YFD1700804)Guangdong Province Key Field R&D Project(No.2023B0202010027)Guangzhou Science and Technology Plan Project(No.2023B03J1286)the research platformwas also supported by Guangdong Science and Technology Infrastructure development(No.2019B121201004).
文摘Antimony(Sb)contamination in paddy fields can lead to its accumulation in rice grains,posing a threat to food safety.To address this issue,the combined use of zero-valent iron(ZVI)and biochar(BC)were applied to decrease the uptake of Sb in Sb-polluted soils,and their effects on Sb uptake from soil to rice grains were investigated.Our results showed that the combination treatment of 0.05%ZVI and 0.095%BC resulted in a significant decrease(42.8%)in Sb accumulation in rice grains that was comparably more efficient than that by 0.05%ZVI(decrease of 15.8%Sb accumulation)or 0.095%BC(decrease of 12.7%Sb accumulation)alone,demonstrating the synergistic effect of ZVI and BC on mitigating Sb uptake by rice plants.ZVI presence resulted in the formation of iron oxides in the soil and on root surfaces,and the S^(2-)/S_(2)^(2-)ascent also increased by 58.7%on day 75 compared with that of the control,facilitating the reduction of Sb(Ⅴ)to less mobile Sb(Ⅲ),thereby decreasing Sb accumulation in rice plants.BC initially increased themobility of Sb owing to its alkaline nature,whereas the electron shuttle properties of BC contributed to a decrease in Sbmobility.The abundance of the arsenite-reducing gene arrA ultimately increased by 203.2% on day 120 compared with the initial phase on day 5,and BC caused a remarkable increase in arrA gene abundance.This study revealed the synergistic mechanisms by combining ZVI and BC to mitigate Sb uptake by rice,which may be useful for the sustainable remediation of contaminated rice paddies.
基金financially supported by the National Natural Science Foundation of China(Nos.21876161,42077301,41420104007)the National Key Research and Development Project of China(No.2018YFF0213403)+1 种基金the Guangdong Academy of Sciences'Project(Nos.2019GDASYL-0102006,2019GDASYL-0301002,2018GDASCX-0501)the Research Fund of China Geological Survey(DD20190703)。
文摘Paddy soil and irrigation water are commonly contaminated with hexavalent chromium[Cr(Ⅵ)]near urban industrial areas,thereby threatening the safety of agricultural products and human health.In this study,we develop a porous and high specific area bone char(BC)to support nanoscale zero-valent iron(n ZVI)and apply it to remediate Cr(Ⅵ)pollution in water and paddy soil under anaerobic conditions.The batch experiments reveal that BC/n ZVI exhibits a higher removal capacity of 516.7 mg/(g·n ZVI)for Cr(Ⅵ)than n ZVI when normalized to the actual n ZVI content,which is 2.8 times that of n ZVI;moreover,the highest n ZVI utilization is the n ZVI loading of 15%(BC/n ZVI15).The Cr(Ⅵ)removal efficiency of BC/n ZVI15 decreases with increasing p H(4–10).Coexisting ions(phosphate and carbonate)and humic acid can inhibit the removal of Cr(Ⅵ)with BC/n ZVI15.Additionally,BC exhibits a strong advantage in promoting Cr(Ⅵ)removal by n ZVI compared to the widely used biochar and activated carbon.Our results demonstrate that reduction and coprecipitation are the dominant Cr(Ⅵ)removal mechanisms.Furthermore,BC/n ZVI15 shows a significantly higher reduction and removal efficiency as well as a strong anti-interference ability for Cr(Ⅵ)in paddy soil,as compared to n ZVI.These findings provide a new effective material for remediating Cr(Ⅵ)pollution from water and soil.
基金supported by the National Natural Science Foundation of China (No.41877143)the Guangdong Province Basic and Applied Basic Research Fund Project (No.2022A1515010775)+1 种基金the National Key Research and Development Project of China (No.2016YFD0800700)the Science and Technology Planning Project of Guangdong Province,China (No.2015B020237008)。
文摘The OsLCD gene,which has been implicated in cadmium (Cd) accumulation in rice,might be a useful target for CRISPR/Cas9 editing.However,the effects of Os LCD gene editing on Cd accumulation,plant growth,and yield traits remain unknown.Here,we used CRISPR/Cas9to generate oslcd single mutants from indica and japonica rice cultivars.We also generated osnramp5 single mutants and oslcd osnramp5 double mutants in the indica background.When grown in Cd-contaminated paddy soils,all oslcd single mutants accumulated less Cd than the wild types (WTs).Consistent with this,oslcd single mutants grown in Cd-contaminated hydroponic culture accumulated significantly less Cd in the shoots as compared to WTs.This decrease in accumulation probably resulted from the reduction of Cd translocation under Cd stress.Oxidative damage also decreased,and plant growth increased in all oslcd single mutant seedlings as compared to WTs in the presence of Cd.Plant growth and most yield traits,as well essential element concentrations in rice seedling shoots,brown rice,and rice straw,were similar between oslcd single mutants and WTs.In the presence of Cd,Cd concentrations in the brown rice and shoots of oslcd osnramp5 double mutants were significantly decreased compared with WTs as well as osnramp single mutants.Our results suggested that OsL CD knockout may reduce Cd accumulation alone or in combination with other knockout mutations in a variety of rice genotypes;unlike Os Nramp5 mutations,Os LCD knockout did not reduce essential element contents.Therefore,Os LCD knockout might be used to generate low-Cd rice germplasms.
基金financially supported by the National Natural Science Foundation of China(42030702)the Guangdong Academy of Sciences’Project(2019GDASYL-0102006 and 2019GDASYL-0301002)。
文摘1.Introduction Agricultural soil pollution is a major threat affecting soil health and the ability of soil to yield safe and sufficient food;thus,it is a barrier to the goal of zero hunger worldwide[1].The food deficiency problem continues to grow,particularly under the current atmosphere of global tension.United Nations(UN)organizations.
基金This work was supported by the National Key Research and Development Program of China(No.2016YFD0800700)the National Natural Science Foundation of China(Nos.420307020 and 41977028)Guangdong Key Research and Development Project(No.2019B110207002).
文摘While the transformation of antimony(Sb) in paddy soil has been previously investigated, the biogeochemical processes of highly chemical active Sb in the soil remain poorly understood. In addition, there is a lack of quantitative understanding of Sb transformation in soil. Therefore, in this study, the kinetics of exogenous Sb in paddy soils were investigated under anaerobic and aerobic incubation conditions. The dissolved Sb(V) and the Sb(V) extracted by diffusive gradient technique decreased under anaerobic conditions and then increased under aerobic conditions. The redox reaction of Sb occurred, and Sb bioavailability significantly decreased after 55 days of incubation. The kinetics of Fe and the scanning transmission electron microscopy analysis revealed that the Fe oxides were reduced and became dispersed under anaerobic conditions, whereas they were oxidized and re-aggregated during the aerobic stage. In addition, the redox processes of sulfur and nitrogen were detected under both anaerobic and aerobic conditions. Based on these observations, a simplified kinetic model was established to distinguish the relative contributions of the transformation processes. The bioavailability of Sb was controlled by immobilization as a result of S reduction and by mobilization as a result of Fe reductive dissolution and S oxidation, rather than the p H. These processes coupled with the redox reaction of Sb jointly resulted in the complex behavior of Sb transformation under anaerobic and aerobic conditions. The model-based method and findings of this study provide a comprehensive understanding of the Sb transformation in a complex soil biogeochemical system under changing redox conditions.
基金funded by the National Natural Science Foundations of China(41522105 and 41571130052)Guangdong Natural Science Funds for Distinguished Young Scholar(2014A030306041)Special Support Program(2016)
文摘The membrane-associated c-type cytochromes(c-Cyts) have been well known as the key enzymes mediating extracellular electron transfer to terminal electron acceptors, resulting in biogeochemical elemental transformation, contaminant degradation, and nutrient cycling. Although c-Cyts-mediated metal reduction or oxidation have been mainly investigated with the purified proteins of metal reducing/oxidizing bacteria, the in vivo behavior of c-Cyts is still unclear, given the difficulty in measuring the proteins of intact cells. Fortunately, the in situ spectroscopy would be ideal for measuring the reaction kinetics of c-Cyts in intact cells under noninvasive physiological conditions. It can also help the establishment of kinetic/thermodynamic models of extracellular electron transfer processes, which are essential to understand the electron transfer mechanisms at the molecular scale. This review briefly summarizes the current advances in spectral methods for examining the c-Cyts in intact cells of dissimilatory metal reducing bacteria and Fe(Ⅱ)-oxidizing bacteria.
基金funded by the National Natural Science Foundations of China(41420104007,41330857,and 41701295)Guangdong Natural Science Funds for Distinguished Young Scholar(2014A030306041)and Special Support Program(2016)
文摘Iron oxidation is a prevalent and important biogeochemical process in paddy soil,but little is known about whether and how microbially mediated iron oxidation is coupled with carbon assimilation,particularly under microaerobic conditions.Here,we investigated kinetics of CO_2 assimilation and Fe(Ⅱ)oxidation in an incubation experiment with paddy soil under suboxic conditions,and profiled the associated microbial community using DNA-stable isotope probing and 16S r RNA gene-based sequencing.The results showed that CO_2 assimilation and Fe(II)oxidation in the gradient tubes were predominantly mediated by the microbes enriched in the paddy soil,primarily Azospirillum and Magnetospirillum,as their relative abundances were higher in the^( 13)C heavy fractions compared to^( 12)C heavy fractions.This study provided direct evidence of chemoautotrophic microaerophiles linking iron oxidation and carbon assimilation at the oxic–anoxic interface in the paddy soil ecosystem.
基金supported by the National Natural Science Foundation of China (Nos.42030702 and 41877143)the Guangdong Key Research and Development Project (No.2019B110207002)the Local Innovative and Research Teams Project of the Guangdong Pearl River Talents Program (No.2017BT01Z176)。
文摘Mercury(Hg)is one of the most dangerous contaminants and has sparked global concern since it poses a health risk to humans when consumed through rice.Sulfur(S)is a crucial component for plant growth,and S may reduce Hg accumulation in rice grains.However,the detailed effects of S and the mechanisms underlying S-mediated responses in Hg-stressed rice plants remain unclear.Currently,to investigate the effects of S addition on rice growth,Hg accumulation,physiological indexes,and gene expression profiles,rice seedlings were hydroponically treated with Hg(20μmol/L Hg Cl_(2))and Hg plus elemental sulfur(100 mg/L).S application significantly reduced Hg accumulation in Hg-stressed rice roots and alleviated the inhibitory effects of Hg on rice growth.S addition significantly reduced Hg-induced reactive oxygen species generation,membrane lipid peroxidation levels,and activities of antioxidant enzymes while increasing glutathione content in leaves.Transcriptomic analysis of roots identified 3,411,2,730,and 581 differentially expressed genes in the control(CK)vs.Hg,CK vs.Hg+S,and Hg vs.Hg+S datasets,respectively.The pathway of S-mediated biological metabolism fell into six groups:biosynthesis and metabolism,expression regulation,transport,stimulus response,oxidation reduction,and cell wall biogenesis.The majority of biological process-related genes were upregulated under Hg stress compared with CK treatment,but downregulated in the Hg+S treatment.The results provide transcriptomic and physiological evidence that S may be critical for plant Hg stress resistance and will help to develop strategies for reduction or phytoremediation of Hg contamination.
基金financially supported by the National Natural Science Foundation of China(41601239)the Highlevel Leading Talent Introduction Program of GDAS,the China Postdoctoral Science Foundation(2016M600644)the"Pearl River Talents"Postdoctoral Program of Guangdong Province,and the National Key Research and Development Program of China(2016YFD0800703)
文摘We investigated the reduction of lepidocrocite(γ-FeOOH) by Shewanella oneidensis MR-1 in the presence and absence of Cd. The results showed that Cd^(2+) retarded microbial reduction of γ-Fe OOH and avoided formation of magnetite. The inhibitory effect on γ-Fe OOH transformation may not result from Cd^(2+) toxicity to the bacterium; it rather was probably due to competitive adsorption between Cd^(2+) and Fe^(2+) on γ-Fe OOH as its surface reduction catalyzed by adsorbed Fe^(2+) was eliminated by adsorption of Cd^(2+).
文摘In modern society,the ceaselessly increasing demand for clean energy has spurred the exploration of novel low-carbon technologies.Nuclear power has proven its effectiveness in resolving the energy crisis.With the rapid expansion of nuclear power facilitating humanity’s shift towards a low-carbon energy society,proper management of nuclear waste generated by nuclear plants has become crucial for minimizing environmental impacts and alleviating public concerns.To promote the development of removal techniques and control strategies for radionuclides in the wastewater,we have organized a special topic on“Nuclear Environment Advances”in National Science Open(NSO).We have invited nine scientists from different fields to present their latest research findings and prospective analyses of radionuclides in the environment systematically.Continuous attention to nuclear safety,strict regulatory supervision,and enhanced emergency response measures are of great significance for reducing the environmental impact during operation of nuclear plants.Assessing the impacts of radiation on various organisms to understand the toxicity mechanisms,potential health effects,and dose-response relationships related to radionuclide exposure can help assess the potential consequences of radionuclide leakage and providing information for decision making in risk management.Huang et al.[1]provide an overview and highlight the importance of environmental toxicology in the risk assessment and management of radionuclides,suggesting that both chemical toxicity and radiotoxicity are indispensable in evaluating the toxicology of radionuclides.Concerned about the absence of environmental pollution standards,they suggest that future research should focus on the long-term impacts of these radionuclides on human health,especially the risks related to low-dose radiation exposure.In the nuclear fuel cycle,radioactive iodine is one of the major gaseous contaminants due to nuclear energy utilization,posing threats to the environment and public health.Covalent Organic Frameworks(COFs)are as a novel class of crystalline porous materials that has been proven promising for iodine capture.Chen et al.[2]systematically analyze the structure-activity relationship of COFs in iodine adsorption by evaluating the critical factors like pore structure,electron-rich groups,and ionic sites influencing adsorption performance.
基金the National Natural Science Foundation of China(21876027)Science and Technology Innovation Project Guangdong Province(2019KQNCX169)+1 种基金the Key Scientific and Technological Project of Foshan City,China(2120001008392)the Science and Technology Innovation Project of Foshan,China(1920001000083).
文摘Globally,nitrogen(N)fertilizer demand is expected to reach 112 million tonnes to support food production for about 8 billion people.However,more than half of the N fertilizer is lost to the environment with impacts on air,water and soil quality,and biodiversity.Importantly,N loss to the environment contributes to greenhouse gas emissions and climate change.Nevertheless,where N fertilizer application is limited,severe depletion of soil fertility has become a major constraint to sustainable agriculture.To address the issues of low fertilizer N use efficiency(NUE),biochar-based N fertilizers(BBNFs)have been developed to reduce off-site loss and maximize crop N uptake.These products are generally made through physical mixing of biochar and N fertilizer or via coating chemical N fertilizers such as prilled urea with biochar.This review aims to describe the manufacturing processes of BBNFs,and to critically assess the effects of the products on soil properties,crop yield and N loss pathways.
基金the National Natural Science Foundation of China(41420104007 and 41671472)the Special Support Plan for High-level Talents of Guangdong,China(2016TQ03Z565)Guangdong Academy of Sciences’Projects(2019GDASYL-0103050,2018GDASCX-0501,and 2017GDASCX-0106).
文摘In paddy fields, the opposing transformation of arsenic (As) and cadmium (Cd) poses many challenges for their simultaneous remediation.In our previous study,we reported that combined biochar and zero-valent iron(ZVI)amendment had great potential for the simultaneous alleviation of As and Cd bioavailability in contaminated acid paddy soil.In this study,an As-and Cd-contaminated alkaline paddy soil was further studied,and the same ZVI-biochar mixtures amendments were applied to evaluate the impact of the mixtures on As and Cd transformation and translocation in the soil-rice system by performing pot experiments with rice.In line with our previous study,the ZVI-biochar composites significantly reduced As and Cd accumulation in different rice tissues,leading to a 42%and 47%decrease in rice grain As and Cd levels,respectively,compared with the control values.The ZVI-biochar mixtures exhibited synergistic effects of biochar and ZVI by enhancing the transformation of bioavailable As and Cd fractions into less bioavailable fractions,and by increasing iron plaque formation to reduce As and Cd bioavailability.Although the bioaccumulation and translocation factors of As and Cd in alkaline paddy soil were generally lower than those in acid paddy soil,particularly in the presence of the ZVI-biochar mixtures,the grain As and Cd levels did not achieve the desired food safety standard levels,probably related to the high soil As content and the small changes in soil pH.Nevertheless,for treating lightly and moderately contaminated paddy soils,ZVI-biochar mixtures can still be a good choice in the future.
