Isomorphic substitution of ferric ion(Fe~(3+))by aluminum ion(Al~(3+))in iron(hydro)oxides is ubiquitous in natural environments.Aluminum substitution inevitably leads to changes in the microstructures,physicochemical...Isomorphic substitution of ferric ion(Fe~(3+))by aluminum ion(Al~(3+))in iron(hydro)oxides is ubiquitous in natural environments.Aluminum substitution inevitably leads to changes in the microstructures,physicochemical properties,and surface reactions of iron(hydro)oxides,which may have great impacts on the sequestration of nutrients and contaminants in soils and aquatic environments.Over the past decades,the structural properties and surface reactivity of Al-substituted iron(hydro)oxides have been intensively studied.Iron(hydro)oxides in various structural forms and with different Al substitution amounts present high application potentials in addressing environmental issues.A timely summary of the structural properties and interfacial reactions of the most common and representative Al-substituted iron(hydro)oxides is of significance.Herein,the effects of Al substitution on the structural properties and surface activities of iron(hydro)oxides were clarified according to the microstructure,crystal facets,surface site type and density,interfacial reaction mechanisms,and modeling parameters of iron(hydro)oxides.This review systematically elucidates how Al substitution affects the structural properties and surface reactions of iron(hydro)oxides,including the well crystallized goethite and hematite and the poorly crystallized ferrihydrite,providing theoretical guidance for further exploration of the mineralogical characteristics and environmental geochemical behaviors of iron(hydro)oxides.展开更多
Underground fires are characterized by smouldering combustion with a slow rate of spread rate and without flames.Although smouldering combustion releases large amounts of gaseous pollutants,it is difficult to discover...Underground fires are characterized by smouldering combustion with a slow rate of spread rate and without flames.Although smouldering combustion releases large amounts of gaseous pollutants,it is difficult to discover by today's forest fire monitoring technologies.Carbon monoxide(CO),nitrogen oxides(NO_(x))and sulfur dioxide(SO_(2))were identified as high concentration marker gases of smouldering combustion-easily-be monitored.According to a two-way ANOVA,combustion time had a significant impact on CO and NO_(x) emissions;smoldering-depth also had a significant impact on NO_(x) emissions but not on CO emissions.Gas emission equations were established by multiple linear regression,C_(co)=156.989-16.626 t and C_(NOx)=3.637-0.252 t-0.039 h.展开更多
Forest fires are influenced by several factors,including forest location,species type,age and density,date of fire occurrence,temperatures,and wind speeds,among others.This study investigates the quantitative effects ...Forest fires are influenced by several factors,including forest location,species type,age and density,date of fire occurrence,temperatures,and wind speeds,among others.This study investigates the quantitative effects of these factors on the degree of forest fire disaster using nonparametric statistical methods to provide a theoretical basis and data support for forest fire management.Data on forest fire damage from 1969 to 2013 was analyzed.The results indicate that different forest locations and types,fire occurrence dates,temperatures,and wind speeds were statistically significant.The eastern regions of the study area experienced the highest fire occurrence,accounting for 85.0%of the total number of fires as well as the largest average forested area burned.April,May,and October had more frequent fires than other months,accounting for 78.9%,while September had the most extensive forested area burned(63.08 ha)and burnt area(106.34 ha).Hardwood mixed forest and oak forest had more frequent fires,accounting for 31.9%and 26.0%,respectively.Hardwood-conifer mixed forest had the most forested area burned(50.18 ha)and burnt area(65.09 ha).Temperatures,wind speeds,and their interaction had significant impacts on forested area burned and area burnt.展开更多
Hausmannite is a common low valence Mn oxide mineral,with a distorted spinel structure,in surficial sediments.Although natural Mn oxides often contain various impurities of transitional metals(TMs),few studies have ad...Hausmannite is a common low valence Mn oxide mineral,with a distorted spinel structure,in surficial sediments.Although natural Mn oxides often contain various impurities of transitional metals(TMs),few studies have addressed the effect and related mechanism of TM doping on the reactivity of hausmannite with metal pollutants.Here,the reactivity of cobalt(Co)doped hausmannite with aqueous As(Ⅲ)and As(Ⅴ)was studied.Co doping decreased the point of zero charge of hausmannite and its adsorption capacity for As(Ⅴ).Despite a reduction of the initial As(Ⅲ)oxidation rate,Co-doped hausmannite could effectively oxidize As(Ⅲ)to As(Ⅴ),followed by the adsorption and fixation of a large amount of As(Ⅴ)on the mineral surface.Arsenic K-edge EXAFS analysis of the samples after As(Ⅴ)adsorption and As(Ⅲ)oxidation revealed that only As(Ⅴ)was adsorbed on the mineral surface,with an average As-Mn distance of 3.25–3.30 A,indicating the formation of bidentate binuclear complexes.These results provide new insights into the interaction mechanism between TMs and low valence Mn oxides and their effect on the geochemical behaviors of metal pollutants.展开更多
Deuteriodifluoromethyl(CF_(2)D)is a challenging and important functional group due to difficult deuterium incorporation and lack of effective precursor reagents.Herein,we report a bench-stable reagent,deuteriodifluoro...Deuteriodifluoromethyl(CF_(2)D)is a challenging and important functional group due to difficult deuterium incorporation and lack of effective precursor reagents.Herein,we report a bench-stable reagent,deuteriodifluoromethyl phosphine(DDFP)from cheap deuterium source for selectivity deuteriodifluoromethylation of azines with a high deuterium incorporation yield.The late-stage modification of complex molecules further confirmed the potential of this reagent for practical applications.We expect that our reagent to find applications in synthesis of isotope-labelled molecules of interests for drug-discovery and related ilucidation of mechanism of action.展开更多
Focal plants are considerably affected by their neighbouring plants,especially when growing in heterogeneous soils.A previous study on grasses demonstrated that soil heterogeneity and species composition affected plan...Focal plants are considerably affected by their neighbouring plants,especially when growing in heterogeneous soils.A previous study on grasses demonstrated that soil heterogeneity and species composition affected plant biomass and above-and belowground allocation patterns.We now tested whether these findings were similar for forbs.Three forb species(i.e.Spartina anglica,Limonium bicolor and Suaeda glauca)were grown in pots with three levels of soil heterogeneity,created by alternatively filling resource-rich and resource-poor substrates using small,medium or large patch sizes.Species compositions were created by growing these forbs either in monocultures or in mixtures.Results showed that patch size×species composition significantly impacted shoot biomass,root biomass and total biomass of forbs at different scales.Specifically,at the pot scale,shoot biomass,root biomass and total biomass increased with increasing patch size.At the substrate scale,shoot biomass and total biomass were higher at the large patch size than at the medium patch size,both in resource-rich and resource-poor substrates.Finally,at the community scale,monocultures had more shoot biomass,root biomass and total biomass than those in the two-or three-species mixtures.These results differ from earlier findings on the responses of grasses,where shoot biomass and total biomass decreased with patch size,and more shoot biomass and total biomass were found in resource-rich than resource-poor substrates.To further elucidate the effects of soil heterogeneity on the interactions between neighbour plants,we advise to conduct longer-term experiments featuring a variety of functional groups.展开更多
Biochar is an effective absorbent for remediating heavy metal contaminated soil,but functional optimization is still needed to improve its performance in field application.Here,we characterized the physical structures...Biochar is an effective absorbent for remediating heavy metal contaminated soil,but functional optimization is still needed to improve its performance in field application.Here,we characterized the physical structures and surface chemical properties of raw wood biochar and palm biochar(WB and PB)and the corresponding sulfhydryl-modified biochar(SWB and SPB).Their adsorption capacity for Pb was evaluated by combining thermodynamic and kinetic adsorption at 0.01 mol/L KCl and corresponding model simulation.The results demonstrated successful grafting of sulfhydryl groups onto the biochar,which dramatically reduced the specific surface area(SSA)and pore volume of biochar.The pKa in the surface complexation model(SCM)indicated similar proton affinity between sulfhydryl groups and original functional groups on the biochar.SCM could satisfactorily fit the Pb adsorption behaviors,and model analysis revealed that Pb tended to be adsorbed on low-proton affin-ity sites at low pH,but high-proton affinity sites became dominant in Pb adsorption with increasing pH and adsorbed almost all Pb ions at pH>7.0.Besides,the Pb adsorption density of SWB and SPB was improved by 8.86 and 3.64 folds relative to that of WB and PB,respectively.Over 90% of initially added Pb ions were removed in 1440 and 720 min by raw and sulfhydryl-modified biochar,respectively,indicating that sulfhydryl modification accelerated the Pb adsorption of biochar.These results suggest that site density,SSA and pore structure of biochar play crucial roles in heavy metal adsorption,and sulfhydryl modification may improve the performance of biochar in remediating heavy metal contaminated soil.展开更多
基金financially supported by the National Natural Science Foundation of China(Nos.42207352,42007020,and 42007015)the Natural Science Fund for Excellent Young Scholars of Hainan Province,China(No.324YXQN421)。
文摘Isomorphic substitution of ferric ion(Fe~(3+))by aluminum ion(Al~(3+))in iron(hydro)oxides is ubiquitous in natural environments.Aluminum substitution inevitably leads to changes in the microstructures,physicochemical properties,and surface reactions of iron(hydro)oxides,which may have great impacts on the sequestration of nutrients and contaminants in soils and aquatic environments.Over the past decades,the structural properties and surface reactivity of Al-substituted iron(hydro)oxides have been intensively studied.Iron(hydro)oxides in various structural forms and with different Al substitution amounts present high application potentials in addressing environmental issues.A timely summary of the structural properties and interfacial reactions of the most common and representative Al-substituted iron(hydro)oxides is of significance.Herein,the effects of Al substitution on the structural properties and surface activities of iron(hydro)oxides were clarified according to the microstructure,crystal facets,surface site type and density,interfacial reaction mechanisms,and modeling parameters of iron(hydro)oxides.This review systematically elucidates how Al substitution affects the structural properties and surface reactions of iron(hydro)oxides,including the well crystallized goethite and hematite and the poorly crystallized ferrihydrite,providing theoretical guidance for further exploration of the mineralogical characteristics and environmental geochemical behaviors of iron(hydro)oxides.
基金supported financially by the National Key Research and Development Plan(2018YFD0600205)the National Natural Science Foundation of China(31971669)。
文摘Underground fires are characterized by smouldering combustion with a slow rate of spread rate and without flames.Although smouldering combustion releases large amounts of gaseous pollutants,it is difficult to discover by today's forest fire monitoring technologies.Carbon monoxide(CO),nitrogen oxides(NO_(x))and sulfur dioxide(SO_(2))were identified as high concentration marker gases of smouldering combustion-easily-be monitored.According to a two-way ANOVA,combustion time had a significant impact on CO and NO_(x) emissions;smoldering-depth also had a significant impact on NO_(x) emissions but not on CO emissions.Gas emission equations were established by multiple linear regression,C_(co)=156.989-16.626 t and C_(NOx)=3.637-0.252 t-0.039 h.
基金supported financially by the National Key Research and Development Plan(2018YFD0600205)China’s National Foundation of Natural Sciences(31470497)the Project of Jilin Province Department of Education(JJKH20180347KJ)
文摘Forest fires are influenced by several factors,including forest location,species type,age and density,date of fire occurrence,temperatures,and wind speeds,among others.This study investigates the quantitative effects of these factors on the degree of forest fire disaster using nonparametric statistical methods to provide a theoretical basis and data support for forest fire management.Data on forest fire damage from 1969 to 2013 was analyzed.The results indicate that different forest locations and types,fire occurrence dates,temperatures,and wind speeds were statistically significant.The eastern regions of the study area experienced the highest fire occurrence,accounting for 85.0%of the total number of fires as well as the largest average forested area burned.April,May,and October had more frequent fires than other months,accounting for 78.9%,while September had the most extensive forested area burned(63.08 ha)and burnt area(106.34 ha).Hardwood mixed forest and oak forest had more frequent fires,accounting for 31.9%and 26.0%,respectively.Hardwood-conifer mixed forest had the most forested area burned(50.18 ha)and burnt area(65.09 ha).Temperatures,wind speeds,and their interaction had significant impacts on forested area burned and area burnt.
基金supported by the Key science and Technology Projects of Inner Mongolia Autonomous Region(No.2019ZD001)the National Natural Science Foundation of China(Nos.42077015,41771267 and 41877030)+1 种基金the National Key Research and Development Program of China(No.2016YFD0800403)the Fundamental Research Funds for the Central Universities(No.103-510320036)。
文摘Hausmannite is a common low valence Mn oxide mineral,with a distorted spinel structure,in surficial sediments.Although natural Mn oxides often contain various impurities of transitional metals(TMs),few studies have addressed the effect and related mechanism of TM doping on the reactivity of hausmannite with metal pollutants.Here,the reactivity of cobalt(Co)doped hausmannite with aqueous As(Ⅲ)and As(Ⅴ)was studied.Co doping decreased the point of zero charge of hausmannite and its adsorption capacity for As(Ⅴ).Despite a reduction of the initial As(Ⅲ)oxidation rate,Co-doped hausmannite could effectively oxidize As(Ⅲ)to As(Ⅴ),followed by the adsorption and fixation of a large amount of As(Ⅴ)on the mineral surface.Arsenic K-edge EXAFS analysis of the samples after As(Ⅴ)adsorption and As(Ⅲ)oxidation revealed that only As(Ⅴ)was adsorbed on the mineral surface,with an average As-Mn distance of 3.25–3.30 A,indicating the formation of bidentate binuclear complexes.These results provide new insights into the interaction mechanism between TMs and low valence Mn oxides and their effect on the geochemical behaviors of metal pollutants.
基金financial supported by Innovation Program of Shanghai Municipal Education Commission(No.201701070002E00037)supported by National Key Research Program of China(No.2017YFD0200505)the Fundamental Research Funds for the Central Universities。
文摘Deuteriodifluoromethyl(CF_(2)D)is a challenging and important functional group due to difficult deuterium incorporation and lack of effective precursor reagents.Herein,we report a bench-stable reagent,deuteriodifluoromethyl phosphine(DDFP)from cheap deuterium source for selectivity deuteriodifluoromethylation of azines with a high deuterium incorporation yield.The late-stage modification of complex molecules further confirmed the potential of this reagent for practical applications.We expect that our reagent to find applications in synthesis of isotope-labelled molecules of interests for drug-discovery and related ilucidation of mechanism of action.
基金supported by the Open Fund of Key Laboratory of Biodiversity and Environment on the Qinghai-Tibet Plateau,Ministry of Education(KLBE2024002)a start-up fund from Lanzhou University(508000-561119213).
文摘Focal plants are considerably affected by their neighbouring plants,especially when growing in heterogeneous soils.A previous study on grasses demonstrated that soil heterogeneity and species composition affected plant biomass and above-and belowground allocation patterns.We now tested whether these findings were similar for forbs.Three forb species(i.e.Spartina anglica,Limonium bicolor and Suaeda glauca)were grown in pots with three levels of soil heterogeneity,created by alternatively filling resource-rich and resource-poor substrates using small,medium or large patch sizes.Species compositions were created by growing these forbs either in monocultures or in mixtures.Results showed that patch size×species composition significantly impacted shoot biomass,root biomass and total biomass of forbs at different scales.Specifically,at the pot scale,shoot biomass,root biomass and total biomass increased with increasing patch size.At the substrate scale,shoot biomass and total biomass were higher at the large patch size than at the medium patch size,both in resource-rich and resource-poor substrates.Finally,at the community scale,monocultures had more shoot biomass,root biomass and total biomass than those in the two-or three-species mixtures.These results differ from earlier findings on the responses of grasses,where shoot biomass and total biomass decreased with patch size,and more shoot biomass and total biomass were found in resource-rich than resource-poor substrates.To further elucidate the effects of soil heterogeneity on the interactions between neighbour plants,we advise to conduct longer-term experiments featuring a variety of functional groups.
基金This research was supported by the National Natural Science Foundation of China(Nos.41601231 and 41425006)We are also thankful to Prof.Zuoxiong Liu from the Foreign Language School of HZAU for his help to edit and polish the English language of the manuscript.
文摘Biochar is an effective absorbent for remediating heavy metal contaminated soil,but functional optimization is still needed to improve its performance in field application.Here,we characterized the physical structures and surface chemical properties of raw wood biochar and palm biochar(WB and PB)and the corresponding sulfhydryl-modified biochar(SWB and SPB).Their adsorption capacity for Pb was evaluated by combining thermodynamic and kinetic adsorption at 0.01 mol/L KCl and corresponding model simulation.The results demonstrated successful grafting of sulfhydryl groups onto the biochar,which dramatically reduced the specific surface area(SSA)and pore volume of biochar.The pKa in the surface complexation model(SCM)indicated similar proton affinity between sulfhydryl groups and original functional groups on the biochar.SCM could satisfactorily fit the Pb adsorption behaviors,and model analysis revealed that Pb tended to be adsorbed on low-proton affin-ity sites at low pH,but high-proton affinity sites became dominant in Pb adsorption with increasing pH and adsorbed almost all Pb ions at pH>7.0.Besides,the Pb adsorption density of SWB and SPB was improved by 8.86 and 3.64 folds relative to that of WB and PB,respectively.Over 90% of initially added Pb ions were removed in 1440 and 720 min by raw and sulfhydryl-modified biochar,respectively,indicating that sulfhydryl modification accelerated the Pb adsorption of biochar.These results suggest that site density,SSA and pore structure of biochar play crucial roles in heavy metal adsorption,and sulfhydryl modification may improve the performance of biochar in remediating heavy metal contaminated soil.
