Surfactant-assisted removal of 2,4-dichlorophenol from soil by zero-valent Fe/Cu activated persulfate

The organic compounds contaminated soil substantially threatens the growth of plants and food safety.In this study,we synthesis zero-valent bimetallic Fe/Cu catalysts for the degradation of 2,4-dichlorophenol(DCP)in soils with persulfate(PS)in combination of organic surfactants and exploring the main environmental impact factors.The kinetic experiments show that the 5%(mass)dosage of Fe/Cu exhibits a higher degradation efficiency(86%)of DCP in soils,and the degradation efficiency of DCP increases with the increase of the initial PS concentration.Acidic conditions are favorable for the DCP degradation in soils.More importantly,the addition of Tween-80,and Triton-100 can obviously desorb DCP from the soil surface,which enhances the degradation efficiency of DCP in soils by Fe/Cu and PS reaction system.Furthermore,the Quenching experiments demonstrate that SO_(4)^(-1)·and·OH are the predominant radicals for the degradation of DCP during the Fe/Cu and PS reaction system as well as non-radical also exist.The findings of this work provide an effective method for remediating DCP from soils.

Microaerobic iron oxidation and carbon assimilation and associated microbial community in paddy soil

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.

Fractionation characteristics of rare earth elements(REEs) linked with secondary Fe, Mn, and Al minerals 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.

碳中和愿景下中国可持续农田土壤修复路径

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.

Effects of zero-valent iron added in the flooding or drainage process on cadmium immobilization in an acid paddy soil

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.

Arsenic release from microbial reduction of scorodite in the presence of electron shuttle in flooded soil

Scorodite (FeAsO_(4)·H_(2)O) is a common arsenic-bearing (As-bearing) iron mineral in nearsurface environments that could immobilize or store As in a bound state.In flooded soils,microbe induced Fe(Ⅲ) or As(Ⅴ) reduction can increase the mobility and bioavailability of As.Additionally,humic substances can act as electron shuttles to promote this process.The dynamics of As release and diversity of putative As(Ⅴ)-reducing bacteria during scorodite reduction have yet to be investigated in detail in flooded soils.Here,the microbial reductive dissolution of scorodite was conducted in an flooded soil in the presence of anthraquinone-2,6-disulfonate (AQDS).Anaeromyxobacter,Dechloromonas,Geothrix,Geobacter,Ideonella,and Zoogloea were found to be the dominant indigenous bacteria during Fe(Ⅲ) and As(Ⅴ) reduction.AQDS increased the relative abundance of dominant species,but did not change the diversity and microbial community of the systems with scorodite.Among these bacteria,Geobacter exhibited the greatest increase and was the dominant Fe(Ⅲ)-and As(Ⅴ)-reducing bacteria during the incubation with AQDS and scorodite.AQDS promoted both Fe(Ⅲ) and As(Ⅴ) reduction,and over 80%of released As(Ⅴ) was microbially transformed to As(Ⅲ).The increases in the abundance of arrA gene and putative arrA sequences of Geobacter were higher with AQDS than without AQDS.As a result,the addition of AQDS promoted microbial Fe(Ⅲ) and As(Ⅴ) release and reduction from As-bearing iron minerals into the environment.These results contribute to exploration of the transformation of As from As-bearing iron minerals under anaerobic conditions,thus providing insights into the bioremediation of As-contaminated soil.

The in situ spectral methods for examining redox status of c-type cytochromes in metal-reducing/oxidizing bacteria

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.

Chromium transformation driven by iron redox cycling in basalt-derived paddy soil with high geological background values

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.

Multifaceted Insight into Sensitivity Analysis and Environmental Impact on Human Health of Soil Contamination Risk Assessment

Sensitivity analysis is a valuable method for evaluating the impact of model parameters on health risk characterization,thereby supporting the prediction of critical uncertainty factors.However,limitations arise in terms of cross-disciplinary discussions and in-depth analyses of previous research.To overcome these limitations,a systematic and multifaceted approach was introduced for analyzing the parameter sensitivities in soil contamination risk assessment.This approach specifically targeted the 12 main parameters associated with 65 soil contaminants for health risk assessment,employing detailed authoritative statistics for risk assessment.Screening analysis revealed that identified heavy metals and organics were influenced by key parameters,such as PM_(10),body weight of adults(BW_(a)),daily air inhalation rate of adults(DAIR_(a)),air exchange rate(ER),and typical soil parameters.PM_(10) showed a positive 100%correlation with inorganics and metals,but BW_(a) and DAIR_(a) exhibited different impacts on different chemicals,with an increase in potential risk observed with higher BW_(a) and lower DAIR_(a).Furthermore,incorporating soil parameters in the analysis showed that compact soil could improve the protection against vapor organic compounds for human health.This refined study presents a comprehensive strategy for sensitivity analysis in health risk assessment of soil contamination,thereby offering substantial support for the protection and preservation of human health.A logical framework also was provided for addressing the limitations of sensitivity analysis and facilitating an understanding of the complex relationships between model parameters and the health risk of soil contamination.

Efficient reduction and adsorption of Cr(Ⅵ)using FeCl_(3)-modified biochar:Synergistic roles of persistent free radicals and Fe(Ⅱ)

Transition metal iron and persistent free radicals(PFRs)both affect the redox properties of biochar,but the electron transfer relationship between them and the coupling reduction mechanism of Cr(Ⅵ)requires further investigation.To untangle the interplay between iron and PFRs in biochar and the infuences on redox properties,FeCl_(3)-modified rice husk biochar(FBCs)was prepared and its reduction mechanism for Cr(Ⅵ)without light was evaluated.The FBCs had higher surface positive charges,oxygen-containing functional groups,and PFRs compared with pristine rice husk biochar(BC).Phenoxyl PFRs with high electrondonating capability formed in biochar.The pronounced electron paramagnetic resonance signals showed that the PFRs preferred to form at lower Fe(Ⅲ)concentrations.While a high concentration of Fe(Ⅲ)would be reduced to Fe(Ⅱ)and consumed the formed PFRs.Adsorption kinetics and X-ray photoelectron spectroscopy analysis indicated that the FBCs effectively enhanced the Cr(Ⅵ)removal efficiency by 1.54-8.20 fold and the Cr(Ⅵ)reduction efficiency by 1.88-9.29 fold compared to those of BC.PFRs quenching and competitive reductant addition experiments revealed that the higher Cr(Ⅵ)reduction performance of FBCs was mainly attributed to the formed PFRs,which could contribute to~74.0%of Cr(Ⅵ)reduction by direct or indirect electron transfer.The PFRs on FBCs surfaces could promote the Fe(Ⅲ)/Fe(Ⅱ)cycle through single electron transfer and synergistically accelerate~52.3%of Cr(Ⅵ)reduction.This study provides an improved understanding of the reduction mechanism of iron-modified biochar PFRs on Cr(Ⅵ)in environments.

Prediction model on hydrolysis kinetics of phthalate monoester:A density functional theory study

As primary degradation products of phthalate esters,phthalate monoesters(MPEs)have been widely detected in various aquatic environments and drawn growing toxicological concerns.Hydrolysis kinetics that is of importance for assessing environmental persistence of chemicals remain elusive for MPEs.Herein,kinetics of base-catalyzed and neutral hydrolysis for 18 MPEs with different leaving groups was investigated by density functional theory calculation.Results indicate that MPEs with leaving groups having p Kaof<10 prefer dissociative transition states.MPEs are more persistent than their parents,and their hydrolysis half-lives were calculated to vary from 3.4 min to 79.2 years(p H=7–9).A quantitative structure-activity relationship model was developed for predicting the hydrolysis kinetics parameters.It was found that p Kaof the leaving groups and electronegativity of the MPEs are key factors determining the hydrolysis kinetics.This work may lay a theoretical foundation for better understanding the chemical process that governs MPE persistence in aquatic environments.

Transcriptomics and physiological analyses reveal that sulfur alleviates mercury toxicity in rice(Oryza sativa L.)

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.

Electrochemical and spectroscopic characteristics of dissolved organic matter in a forest soil profile

Dissolved organic matter （DOM） represents one of the most mobile and reactive organic compounds in ecosystem and plays an important role in the fate and transport of soil organic pollutants, nutrient cycling and more importantly global climate change. Electrochemical methods were first employed to evaluate DOM redox properties, and spectroscopic approaches were utilized to obtain information concerning its composition and structure. DOM was extracted from a forest soil profile with five horizons. Differential pulse voltammetry indicated that there were more redox-active moieties in the DOM from upper horizons than in that from lower horizons. Cyclic voltammetry further showed that these moieties were reversible in electron transfer. Chronoamperometry was employed to quantify the electron transfer capacity of DOM, including electron acceptor capacity and electron donor capacity, both of which decreased sharply with increasing depth. FT-IR, UV-Vis and fluorescence spectra results suggested that DOM from the upper horizons was enriched with aromatic and humic structures while that from the lower horizons was rich in aliphatic carbon, which supported the findings obtained by electrochemical approaches. Electrochemical approaches combined with spectroscopic methods were applied to evaluate the characteristics of DOM extracted along a forest soil profile. The electrochemical properties of DOM, which can be rapidly and simply obtained, provide insight into the migration and transformation of DOM along a soil profile and will aid in better understanding of the biogeochemical role of DOM in natural environments.

A highly porous animal bone-derived char with a superiority of promoting nZVI for Cr(Ⅵ)sequestration in agricultural soils

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.

Cadmium isotope compositions of Fe-Mn nodules and surrounding soils: Implications for tracing Cd sources

Cadmium (Cd) pollution in agricultural soils has become a severe threat to food security and human health in recent years. Stable Cd isotopes are a potentially powerful tool for identifying the sources of Cd in soils. However, many Earth surface processes, including adsorption, leaching, and biogeochemical cycles in plants, may generate Cd isotope fractionation, which can complicate the potential application of Cd isotopes in tracing the sources of Cd pollution in soils. In this work, the Cd isotope compositions of typical Fe-Mn nodules (FMNs) and surrounding soils in two different soil profiles are investigated. Our results show that the FMNs in lower layers (i.e., C and W horizons) are isotopically lighter than the surrounding soils by –0.114‰ to –0.156‰ (Δ114/110CdFMN-soil). We interpret this fractionation as the result of preferential adsorption of isotopically light Cd onto the surface of goethite. In the upper layers (i.e., P and A horizons), the Δ114/110CdFMN-soil values are more negative in the P horizon (–0.213‰ to –0.388‰) but more positive in the A horizon (0.061‰ to 0.204‰). We interpret these fractionations as the result of natural biogeochemical processes (i.e., leaching and biological cycling) during soil development. Soil leaching preferentially releases isotopically heavy Cd into the underlying soil (i.e., P horizon), shifting the topsoil towards lower δ114/110Cd values but the underlying soils towards higher δ114/110Cd values. Moreover, biological cycling contributes isotopically heavy Cd to the topsoil, probably shifting the topsoil towards higher δ114/110Cd values. Our study demonstrates that the formation of Fe oxyhydroxides, leaching, and biological cycling can considerably modify the soil Cd isotope signature, highlighting the need to consider natural biogeochemical processes when using Cd isotopes to trace heavy metal pollution in soils.

New insight into iron biogeochemical cycling in soil-rice plant system using iron isotope fractionation

Iron (Fe) migration in soil-plants is a critical part of Fe biogeochemical cycling in the earth surface system. Fe isotope fractionation analysis in the soil-rice system is promising for quantitatively assessing various pathways and clarifying Fe transformation processes. However, the mechanisms of Fe isotope fractionation in the soil-rice system are not well understood. In this study, the Fe isotopic compositions (δ^(56)Fe) of rhizosphere soils, pore water, Fe plaque, and rice plant tissues at the jointing and mature stages of the plants were determined. The rice plants were slightly enriched in heavier δ^(56)Fe by 0.3‰ relative to the soil, and the stele and cortex showed similar δ^(56)Fe values, indicating that the uptake of Fe by rice plants predominantly occurred via Fe(III)-phytosiderophores (Fe(III)-PS) chelation, but not Fe(III) reduction. Additionally, at both the jointing and mature stages, the rice plant tissues showed similar δ^(56)Fe values. However, the Fe isotope fractionation between the roots and stems (Δ56Feroot−stem) was 1.39 ± 0.13‰, which is similar to the previously Ab initio-calculated values between Fe(III)-citrate and Fe(III)- 2-deoxymugineic acid (DMA), indicating that both the phloem and xylem have similar δ^(56)Fe values, and the major Fe-chelating substances in the phloem of the rice plants are Fe(III)-DMA and Fe(II)- Nicotianamine (NA). Therefore, this study demonstrates that Fe isotope fractionation can be used as a signature for interpreting the Fe uptake and translocation mechanism in the soil-rice system.

Kinetics of antimony biogeochemical processes under pre-definite anaerobic and aerobic conditions in a paddy soil

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.

Two-step calculation method to enable the ecological and human health risk assessment of remediated soil treated through thermal curing

The centralized utilization of heavy-metal-contaminated soil has become the main strategy to remediate brownfield-site pollution.However,few studies have evaluated the ecological and human health risks of reusing these remediated soils.Considering Zn as the target metal,systematic pHdependent leaching and the Community Bureau of Reference(BCR)extraction were conducted at six pH values(pH=2,4,6,8,10,12)for the remediated soil treated through thermal curing.The pHdependent leaching results showed that with the formation of ZnCr2O4 spinel phases,the remediated soil exhibited strong inherent resistance to acidic attack over longer leaching periods.Furthermore,the BCR extraction results showed that the leaching agent pH value mainly affected the acid-soluble fraction content.Moreover,a strong complementary relationship was noted between the leaching and acid-soluble fraction contents,indicating that the sum of these two parameters is representative of the remediated soil risk value.Therefore,we proposed a two-step calculation method to determine the sum of the two heavy metal parameters as the risk value of remediated soil.In contrast to the traditional one-step calculation method,which only uses the leaching content as the risk value,this two-step calculation method can effectively avoid underestimating the risk of remediated soil.

Generation of low-cadmium rice germplasms via knockout of OsLCD using CRISPR/Cas9

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.

Performance Assessment of a Novel Polygeneration System Based on the Integration of Waste Plasma Gasification,Tire Pyrolysis,Gas Turbine,Supercritical CO_(2)Cycle and Organic Rankine Cycle

In this paper,a novel polygeneration system involving plasma gasifier,pyrolysis reactor,gas turbine(GT),supercritical CO_(2)(S-CO_(2))cycle,and organic Rankine cycle(ORC)has been developed.In the proposed scheme,the syngas is obtained by the gasification and the pyrolysis is first burned and drives the gas turbine for power generation,and then the resulting hot exhaust gas is applied to heat the working fluid for the supercritical CO_(2)cycle and the working fluid for the bottom organic Rankine cycle.In addition to the electrical output,the pyrolysis subsystem also produces pyrolysis oil and char.Accordingly,energy recovery is achieved while treating waste in a non-hazardous manner.The performance of the new scheme was examined by numerous methods,containing energy analysis,exergy analysis,and economic analysis.It is found that the net total energy output of the polygeneration system could attain 19.89 MW with a net total energy efficiency of 52.77%,and the total exergy efficiency of 50.14%.Besides,the dynamic payback period for the restoration of the proposed project is only 3.31 years,and the relative net present value of 77552640 USD can be achieved during its 20-year lifetime.