Harboring polyextremotolerant microbial topsoil communities,biological soil crusts(biocrusts)occur across various climatic zones,and have been well studied in the terrestrial drylands.However,little is known about the...Harboring polyextremotolerant microbial topsoil communities,biological soil crusts(biocrusts)occur across various climatic zones,and have been well studied in the terrestrial drylands.However,little is known about the functional metabolic potential of microbial communities involved in the biogeochemical processes during the early succession of biocrusts on the tropical reef islands.We collected 26 biocrusts and bare soil samples from the Xisha Islands and Nansha Islands,and applied a functional gene array(GeoChip 5.0)to reveal nitrogen(N)cycling processes involved in these samples.Both physicochemical measurement and enzyme activity assay were utilized to characterize the soil properties.Results revealed the composition of N-cycling functional genes in biocrusts was distinct from that in bare soil.Additionally,microorganisms in biocrusts showed lower functional potential related to ammonification,denitrification,N assimilation,nitrification,N fixation,and dissimilatory nitrate reduction to ammonium compared to bare soils.Although the abundance of nifH gene was lower in biocrusts,nitrogenase activity was significantly higher compared to that in bare soils.Precipitation,soil physicochemical properties(i.e.,soil available copper,soil ammonia N and pH)and soil biological properties(i.e.,β-glucosidase,fluorescein diacetate hydrolase,alkaline protease,urease,alkaline phosphatase,catalase and chlorophyll a)correlated to the N-cycling functional genes structure.Nitrate N and ammonia N were more abundant in biocrusts than bare soil,while pH value was higher in bare soil.Our results suggested biocrusts play an important role in N-cycling in coral sand soil,and will be helpful in understanding the development and ecological functions of biocrusts on tropical reef islands.展开更多
The continuous increase of nitrate(NO_(3)^(-))level in rivers is a hot issue in the world.However,the driving mechanism of high NO_(3)^(-)level in large rivers is still lacking,which has limited the use of river water...The continuous increase of nitrate(NO_(3)^(-))level in rivers is a hot issue in the world.However,the driving mechanism of high NO_(3)^(-)level in large rivers is still lacking,which has limited the use of river water and increased the cost of water treatment.In this study,multiple isotopes and source resolution models are applied to identify the driving mechanism of high NO_(3)^(-)level and key processes of nitrogen cycling in the lower reaches of the Yellow River(LRYR).The major sources of NO_(3)^(-)were sewage and manure(SAM)in the low-flow season and soil nitrogen(SN)and chemical fertilizer(CF)in the high-flow season.Nitrification was the most key process of nitrogen cycling in the LRYR.However,in the biological removal processes,denitrification may not occur significantly.The temporal variation of contributions of NO_(3)^(-)sources were estimated by a source resolution model in the LRYR.The proportional contributions of SAM and CF to NO_(3)^(-)in the low-flow and high-flow season were 32.5%-52.3%,44.2%-46.2%and 36.0%-40.8%,54.9%-56.9%,respectively.The driving mechanisms of high NO_(3)^(-)level were unreasonable sewage discharge,intensity rainfall runoff,nitrification and lack of nitrate removal capacity.To control the NO_(3)^(-)concentration,targeted measures should be implemented to improve the capacity of sewage and wastewater treatment,increase the utilization efficiency of nitrogen fertilizer and construct ecological engineering.This study deepens the understanding of the driving mechanism of high nitrate level and provides a vital reference for nitrogen pollution control in rivers to other area of the world.展开更多
The subtropical hilly region of China is a region with intensive crop and livestock production,which has resulted in serious N pollution in soil,water and air.This review summarizes the major soil N cycling processes ...The subtropical hilly region of China is a region with intensive crop and livestock production,which has resulted in serious N pollution in soil,water and air.This review summarizes the major soil N cycling processes and their influencing factors in rice paddies and uplands in the subtropical hilly region of China.The major N cycling processes include the N fertilizer application in croplands,atmospheric N deposition,biological N fixation,crop N uptake,ammonia volatilization,N_(2)O/NO emissions,nitrogen runoff and leaching losses.The catchment nutrients management model for N cycle modeling and its case studies in the subtropical hilly region were also introduced.Finally,N management practices for improving N use efficiency in cropland,as well as catchment scales are summarized.展开更多
Phenolic acids are secondary metabolites of plants that significantly affect nutrient cycling processes.To investigate such effects,the soil available nitrogen(N)content,phenolic acid content,and net N mineralization ...Phenolic acids are secondary metabolites of plants that significantly affect nutrient cycling processes.To investigate such effects,the soil available nitrogen(N)content,phenolic acid content,and net N mineralization rate in three successive rotations of Chinese fir plantations in subtropical China were investigated.Net N mineralization and nitrification rates in soils treated with phenolic acids were measured in an ex situ experiment.Compared with first-rotation plantations(FCP),the contents of total soil nitrogen and nitrate in second(SCP)-and third-rotation plantations(TCP)decreased,and that of soil ammonium increased.Soil net N mineralization rates in the second-and third-rotation plantations also increased by 17.8%and 39.9%,respectively.In contrast,soil net nitrification rates decreased by 18.0%and 25.0%,respectively.The concentrations of total phenolic acids in the FCP soils(123.22±6.02 nmol g^-1)were 3.0%and 17.9%higher than in the SCP(119.68±11.69 nmol g^-1)and TCP(104.51±8.57 nmol g^-1,respectively).The total content of phenolic acids was significantly correlated with the rates of net soil N mineralization and net nitrification.The ex situ experiment showed that the net N mineralization rates in soils treated with high(HCPA,0.07 mg N kg^-1 day^-1)and low(LCPA,0.18 mg N kg^-1 day^-1)concentrations of phenolic acids significantly decreased by 78.6%and 42.6%,respectively,comparing with that in control(0.32 mg N kg^-1 day^-1).Soil net nitrification rates under HCPA and LCPA were significantly higher than that of the control.The results suggested that low contents of phenolic acids in soil over successive rotations increased soil net N mineralization rates and decreased net nitrification rates,leading to consequent reductions in the nitrate content and enhancement of the ammonium content,then resulting in enhancing the conservation of soil N of successive rotations in Chinese fir plantation.展开更多
Southwest China is the primary area for damming rivers to produce hydroelectric energy and store water.River damming has changed hydrodynamic,chemical,and biological processes,which are related to sinks and sources of...Southwest China is the primary area for damming rivers to produce hydroelectric energy and store water.River damming has changed hydrodynamic,chemical,and biological processes,which are related to sinks and sources of greenhouse gases and carbon and nitrogen fluxes of different interfaces.Here,I provide an introduction to a river damming-related foundation,the National Key R&D Program of China(2016YTA0601000).Supported by the foundation,we carried out research on multiprocesses/multi-interfaces of carbon and nitrogen biogeochemical cycles in a dammed river system and have produced important results,as presented in this issue of the journal.展开更多
The coastal upwelling has profound influence on the surrounding ecosystem by supplying the nutrient-replete water to the euphotic zone.Nutrient biogeochemistry was investigated in coastal waters of the eastern Hainan ...The coastal upwelling has profound influence on the surrounding ecosystem by supplying the nutrient-replete water to the euphotic zone.Nutrient biogeochemistry was investigated in coastal waters of the eastern Hainan Island in summer 2015 and autumn 2016.From perspectives of nutrient dynamics and physical transport,the nutrient fluxes entered the upper 50 m water depth(between the mixed layer and the euphotic zone)arisen from the upwelling were estimated to be 2.5-5.4 mmol/(m^(2)·d),0.15-0.28 mmol/(m^(2)·d),and 2.2-7.2 mmol/(m^(2)·d)for dissolved inorganic nitrogen(DIN),phosphate(DIP),and dissolved silicate(DSi),respectively,which were around 6-to 12-fold those in the background area.The upwelled nutrients supported an additional plankton growth of(14.70±8.95)mg/m^(2)for chlorophyll a(Chl a).The distributions of nitrateδ^(15)N andδ^(18)O above the 300 m water depth(top of the North Pacific Intermediate Water)were different among the upwelling area,background area in summer,and the stations in autumn,and the difference of environmental and biogeochemical conditions between seasons should be the reason.The higher DIN/DIP concentration ratio,nitrate concentration anomaly,and lower nitrate isotope anomaly(Δ(15,18))in the upper ocean in summer than in autumn indicated the stronger nitrogen fixation and atmospheric deposition,and the following fixed nitrogen regeneration in summer.The higher values of Chl a and nitrateδ^(15)N andδ^(18)O within the euphotic zone in autumn than the background area in summer suggested the stronger nitrate assimilation in autumn.The differences in relatively strength of the assimilation,nitrogen fixation and atmospheric deposition,and the following remineralization and nitrification between the two seasons made the higherδ^(18)O:δ^(15)N and larger difference of enzymatic isotope fractionation factors^(15)εand^(18)εfor nitrate assimilation in summer than in autumn above the North Pacific Tropical Water.展开更多
The application of butachlor as an herbicide in paddy fields is widely practiced,aiming to increase rice yield by directly or indirectly influencing the paddy environment.Periphytic biofilms,which form at the soil-wat...The application of butachlor as an herbicide in paddy fields is widely practiced,aiming to increase rice yield by directly or indirectly influencing the paddy environment.Periphytic biofilms,which form at the soil-water interface in paddy fields,are complex bioaggregates that play an important role in nitrogen (N) cycling.The objective of this study was to investigate the effect of butachlor on periphytic biofilm growth and N cycling under both light and dark conditions in the laboratory.The results revealed that butachlor application hindered the growth of periphytic biofilms and led to the dominance of Cyanobacteria as the primary prokaryotes,while inhibiting the development of eukaryotic Trebouxiophyceae.Furthermore,the application of butachlor reduced the richness and diversity of prokaryotes,but increased those of eukaryotes in periphytic biofilms.The light treatments exhibited higher total N loss because light favored periphytic biofilm growth and enhanced ammonium (NH_(4)^(+)) assimilation and nitrification.Additionally,butachlor application resulted in the increased retention of NH_(4)^(+)-N and nitrate (NO_(3)^(-))-N and an increase in N loss via denitrification.The abundances of functional genes encoding enzymes such as ammonia monooxygenase,nitrite reductase,and nitrous oxide reductase were increased by butachlor application,favoring nitrification and denitrification processes.Overall,the results suggest that butachlor application leads to an increase in total N loss mainly through denitrification in paddy systems,particularly in the presence of periphytic biofilms.Thus,the results may provide valuable insights into the changes in periphytic biofilm growth and N cycling induced by butachlor,and future studies can further explore the potential implications of these changes in paddy soils.展开更多
Beech stands are considered part of the ancient forest ecosystems in the northern hemisphere.In mixed stands in beach forest ecosystems,the type of associated tree species can signifi cantly aff ect soil functions,but...Beech stands are considered part of the ancient forest ecosystems in the northern hemisphere.In mixed stands in beach forest ecosystems,the type of associated tree species can signifi cantly aff ect soil functions,but their infl uence on microbial activity,nutrient cycling and belowground properties is unknown.Here,we considered forest patches in northern Iran that are dominated by diff erent tree species:Fagus orientalis Lipsky,Quercus castaneifolia C.A.Mey.,Pterocarya fraxinifolia(Lam.),Tilia begonifolia Stev.,Zelkova carpinifolia Dippe,Acer cappadocicum Gled,Acer velutinum Boiss.,Fraxinus excelsior L.,Carpinus betulus L.,and Alnus subcordata C.A.Mey.For each forest patch–tree species,litter and soil samples(25×25×10 cm,100 of each)were analyzed for determine soil and litter properties and their relationship with tree species.The litter decomposition rate during a 1-year experiment was also determined.A PCA showed a clear diff erence between selected litter and soil characteristics among tree species.F.orientalis,Q.castaneifolia,P.fraxinifolia,T.begonifolia,Z.carpinifolia,A.cappadocicum,and A.velutinum enhanced soil microbial biomass of carbon,whereas patches with F.excelsior,C.betulus and A.subcordata had faster litter decomposition and enhanced biotic activities and C and N dynamics.Thus,soil function indicators were species-specifi c in the mixed beech forest.A.subcordata(a N-fi xing species),C.betulus and F.excelsior were main drivers of microbial activities related to nutrient cycling in the old-growth beech forest.展开更多
Ammonia plays an essential role in human production and life as a raw material for chemical fertilizers.The nitrate electroreduction to ammonia reaction(NO_(3)RR)has garnered attention due to its advantages over the H...Ammonia plays an essential role in human production and life as a raw material for chemical fertilizers.The nitrate electroreduction to ammonia reaction(NO_(3)RR)has garnered attention due to its advantages over the Haber-Bosch process and electrochemical nitrogen reduction reaction.Therefore,it represents a promising approach to safeguard the ecological environment by enabling the cycling of nitrogen species.This review begins by discussing the theoretical insights of the NO_(3)RR.It then summarizes recent advances in catalyst design and construction strategies,including alloying,structure engineering,surface engineering,and heterostructure engineering.Finally,the challenges and prospects in this field are presented.This review aims to guide for enhancing the efficiency of electrocatalysts in the NO_(3)RR,and offers insights for converting NO_(3)-to NH_(3).展开更多
As one typical cationic disinfectant, quaternary ammonium compounds(QACs) were approved for surface disinfection in the coronavirus disease 2019 pandemic and then unintentionally or intentionally released into the sur...As one typical cationic disinfectant, quaternary ammonium compounds(QACs) were approved for surface disinfection in the coronavirus disease 2019 pandemic and then unintentionally or intentionally released into the surrounding environment. Concerningly, it is still unclear how the soil microbial community succession happens and the nitrogen(N)cycling processes alter when exposed to QACs. In this study, one common QAC(benzalkonium chloride(BAC) was selected as the target contaminant, and its effects on the temporal changes in soil microbial community structure and nitrogen transformation processes were determined by q PCR and 16S r RNA sequencing-based methods. The results showed that the aerobic microbial degradation of BAC in the two different soils followed first-order kinetics with a half-life(4.92 vs. 17.33 days) highly dependent on the properties of the soil. BAC activated the abundance of N fixation gene(nif H) and nitrification genes(AOA and AOB) in the soil and inhibited that of denitrification gene(nar G). BAC exposure resulted in the decrease of the alpha diversity of soil microbial community and the enrichment of Crenarchaeota and Proteobacteria. This study demonstrates that BAC degradation is accompanied by changes in soil microbial community structure and N transformation capacity.展开更多
The rhizosphere is the most active soil area for material transformation and energy flow of soil,root,and microorganism,which plays an important role in soil biochemical cycling.Although the rhizospheric nitrogen(N)an...The rhizosphere is the most active soil area for material transformation and energy flow of soil,root,and microorganism,which plays an important role in soil biochemical cycling.Although the rhizospheric nitrogen(N)and phosphorous(P)were easily disturbed in the agroecosystem,the effects of rhizosphere on the dynamics of soil N and P cycling have not yet been systematically quantified globally.We summarized the magnitude,direction,and driving forces of rhizosphere effects on agroecosystem's N and P dynamics by 1063 observations and 15 variables from 122 literature.Rhizosphere effects increased available N(AN,9%),available P(AP,11%),and total P(TP,5%),and decreased nitrate N(NO_(3)-N,18%)and ammonia N(NH_(4)-N,16%).The effect of rhizosphere on total N(TN)was not significant.These effects improved AN in tropical(12%)and subtropical(14%)regions.The effect of rhizosphere on TP was greater under subtropical conditions than in other climates.The most substantial effects of the rhizosphere on TP and AP were observed under humid conditions.Rhizosphere effects increased AN and AP in vegetables more than in other crop systems.Application of N>30o kg ha^(-1) had the most significant and positive rhizosphere effects on TN and AN.P application of 100-150 kg ha^(-1) had the greatest rhizosphere effects on TP and AP.These effects also improved the microbial(biomass N and P)and enzymatic aspects(urease,acid phosphatase,and alkaline phosphatase)of soil P and N cycling.Structural equation modeling suggested that aridity indices,fertilizer application rate,soil pH,microbial biomass,and soil enzymes strongly influence the magnitude and direction of the rhizosphere's effect on the P and N cycles.Overall,these findings are critical for improving soil nutrient utilization efficiency and modeling nutrient cycling in the rhizosphereforagricultural systems.展开更多
Seasonal soil freeze-thaw events may enhance soil nitrogen transformation and thus stimulate nitrous oxide(N_2O)emissions in cold regions.However,the mechanisms of soil N_2O emission during the freeze-thaw cycling in ...Seasonal soil freeze-thaw events may enhance soil nitrogen transformation and thus stimulate nitrous oxide(N_2O)emissions in cold regions.However,the mechanisms of soil N_2O emission during the freeze-thaw cycling in the field remain unclear.We evaluated N_2O emissions and soil biotic and abiotic factors in maize and paddy fields over 20 months in Northeast China,and the structural equation model(SEM)was used to determine which factors affected N_2O production during non-growing season.Our results verified that the seasonal freeze-thaw cycles mitigated the available soil nitrogen and carbon limitation during spring thawing period,but simultaneously increased the gaseous N_2O-N losses at the annual time scale under field condition.The N_2O-N cumulative losses during the non-growing season amounted to 0.71 and 0.55 kg N ha^(–1) for the paddy and maize fields,respectively,and contributed to 66 and 18%of the annual total.The highest emission rates(199.2–257.4μg m^(–2) h^(–1))were observed during soil thawing for both fields,but we did not observe an emission peak during soil freezing in early winter.Although the pulses of N_2O emission in spring were short-lived(18 d),it resulted in approximately80%of the non-growing season N_2O-N loss.The N_2O burst during the spring thawing was triggered by the combined impact of high soil moisture,flush available nitrogen and carbon,and rapid recovery of microbial biomass.SEM analysis indicated that the soil moisture,available substrates including NH_4^+and dissolved organic carbon(DOC),and microbial biomass nitrogen(MBN)explained 32,36,16 and 51%of the N_2O flux variation,respectively,during the non-growing season.Our results suggested that N_2O emission during the spring thawing make a vital contribution of the annual nitrogen budget,and the vast seasonally frozen and snow-covered croplands will have high potential to exert a positive feedback on climate change considering the sensitive response of nitrogen biogeochemical cycling to the freeze-thaw disturbance.展开更多
Heterotrophic nitrification-aerobic denitrification(HNAD)is essential in diverse nitrogen-transforming processes.How HNAD is modulated by quorum sensing(QS)systems is still ambiguous.The QS system in Pseudomonas aerug...Heterotrophic nitrification-aerobic denitrification(HNAD)is essential in diverse nitrogen-transforming processes.How HNAD is modulated by quorum sensing(QS)systems is still ambiguous.The QS system in Pseudomonas aeruginosa manipulates colony behavior.Here,we described the influence of the Pseudomonas quinolone signal(PQS)and N-acyl-L-homoserine lactone(AHL)on HNAD.The HNAD of P.aeruginosa was inhibited by the oversecretion of PQS.AHL-or PQS-deficient P.aeruginosa mutants had a higher ability for nitrogen removal.QS inhibited heterotrophic nitrification mainly via controlling the activity of nitrite oxidoreductase(NXR)and the depressed aerobic denitrification by regulating the catalytic abilities of nitric oxide reductase(NOR),nitrite reductase(NIR),and nitrate reductase(NAR).The addition of citrate as the sole carbon source increased the nitrogen removal efficiency compared with other carbon sources.Nitrite,as the sole nitrogen source,could be used entirely with only the moderate concentration of PQS contained.AHL and PQS controlled both nitrification and denitrification,suggesting that QS plays an important role in nitrogen cycle under aerobic conditions.展开更多
Saltmarshes are one of the most productive ecosystems,which contribute significantly to coastal nutrient and carbon budgets.However,limited information is available on soil nutrient and carbon losses via porewater exc...Saltmarshes are one of the most productive ecosystems,which contribute significantly to coastal nutrient and carbon budgets.However,limited information is available on soil nutrient and carbon losses via porewater exchange in saltmarshes.Here,porewater exchange and associated fluxes of nutrients and dissolved inorganic carbon(DIC)in the largest saltmarsh wetland(Chongming Dongtan)in the Changjiang River Estuary were quantified.Porewater exchange rate was estimated to be(37±35)cm/d during December 2017 using a radon(^(222)Rn)mass balance model.The porewater exchange delivered 67 mmol/(m^(2)·d),38 mmol/(m^(2)·d)and 2690 mmol/(m^(2)·d)of dissolved inorganic nitrogen(DIN),dissolved silicon(DSi)and DIC into the coastal waters,respectively.The dominant species of porewater DIN was NH_(4)^(+)(>99%of DIN).However,different with those in other ecosystems,the dissolved inorganic phosphorus(DIP)concentration in saltmarsh porewater was significantly lower than that in surface water,indicating that saltmarshes seem to be a DIP sink in Chongming Dongtan.The porewater-derived DIN,DSi and DIC accounted for 12%,5%and 18%of the riverine inputs,which are important components of coastal nutrient and carbon budgets.Furthermore,porewater-drived nutrients had obviously high N/P ratios(160–3995),indicating that the porewater exchange process may change the nutrient characteristics of the Changjiang River Estuary and further alter the coastal ecological environment.展开更多
Over the past 30 years,super rice played an important role in boosting rice yield.The phenotype of erect panicle(EP)architecture controlled by dense and erect panicle 1(dep1)is the typical characteristic of super rice...Over the past 30 years,super rice played an important role in boosting rice yield.The phenotype of erect panicle(EP)architecture controlled by dense and erect panicle 1(dep1)is the typical characteristic of super rice,and the phenotype has been used in rice breeding for nearly a century.In this review,the molecular genetic basis of EP phenotype,and mechanism of how dep1 affects rice carbon,nitrogen metabolism and grain quality(grain shape and taste quality)were discussed.In addition,we discussed the possible improvement strategies of rice yield and quality.This review provides a quick overview of the whole process for rice quality formation,as well as suggestions and ideas for future research on rice quality improvement.展开更多
Environmental changes significantly alter the structure,diversity and activity of soil microbial communities during spring freezing-thawing period,leading to changes in the soil microbial nitrogen cycle.Changes in N_(...Environmental changes significantly alter the structure,diversity and activity of soil microbial communities during spring freezing-thawing period,leading to changes in the soil microbial nitrogen cycle.Changes in N_(2)O fluxes after land use conversion from primary forest to secondary forest,Korean pine plantation and cropland in northeast China have not been quantified.Field experiments were conducted to measure soil N_(2)O fluxes in a primary forest,two secondary forests,a Korean pine plantation,and one maize field in a temperate region in northeast China from 2017-03-06 to 2017-05-28.During the experimental period,the soil was exclusively a nitrogen source for all land uses.We found that N_(2)O emissions ranged from 15.63 to 68.74μg m^(-2) h^(-1),and cumulative N_(2)O emissions ranged from 0.33 to 2.10 kg ha^(-1) during the period.Cumulative N_(2)O emissions from the maize field were significantly higher than that from primary forest,Korean pine plantation,hardwood forest,and Betula platyphylla forest by 262.1% to 536.4%.Compared with other ecosystems in similar studies,the N_(2)O emission rates of all ecosystem types in this study were low during the spring thaw period.Stepwise multiple linear regression indicated that there were significant correlations between N_(2)O emissions and environmental factors(air temperature and soil temperature,soil water content,soil p H,NH_(4)^(+)-N,NO_(3)^(-)-N,and soil organic carbon).The results showed that conversion of land use from primary forest to hardwood forest,Korean pine plantation or maize field greatly increased soil N_(2)O emissions during spring freezing-thawing period,and N_(2)O emissions from primary forest were almost the same as those from Betula platyphylla forest.展开更多
Carbon-nitrogen coupling is a fundamental principle in ecosystem ecology.However,how the coupling responds to global change has not yet been examined.Through a comprehensive and systematic literature review,we assesse...Carbon-nitrogen coupling is a fundamental principle in ecosystem ecology.However,how the coupling responds to global change has not yet been examined.Through a comprehensive and systematic literature review,we assessed how the dynamics of carbon processes change with increasing nitrogen input and how nitrogen processes change with increasing carbon input under global change.Our review shows that nitrogen input to the ecosystem mostly stimulates plant primary productivity but inconsistently decreases microbial activities or increases soil carbon sequestration,with nitrogen leaching and nitrogenous gas emission rapidly increasing.Nitrogen fixation increases and nitrogen leaching decreases to improve soil nitrogen availability and support plant growth and ecosystem carbon sequestration under elevated CO_(2)and temperature or along ecosystem succession.We conclude that soil nitrogen cycle processes continually adjust to change in response to either overload under nitrogen addition or deficiency under CO_(2)enrichment and ecosystem succession to couple with carbon cycling.Indeed,processes of both carbon and nitrogen cycles continually adjust under global change,leading to dynamic coupling in carbon and nitrogen cycles.The dynamic coupling framework reconciles previous debates on the“uncoupling”or“decoupling”of ecosystem carbon and nitrogen cycles under global change.Ecosystem models failing to simulate these dynamic adjustments cannot simulate carbonnitrogen coupling nor predict ecosystem carbon sequestration well.展开更多
Straw and manure are widely applied to agricultural systems,and greatly shape soil N-cycling microflora.However,we still lack a comprehensive understanding of how these organic materials structure soil N-cycling micro...Straw and manure are widely applied to agricultural systems,and greatly shape soil N-cycling microflora.However,we still lack a comprehensive understanding of how these organic materials structure soil N-cycling microbial communities.In this study,metagenomic analysis was performed to investigate the compositional variation in N-cycling microbial communities in a 30-year long-term experiment under five fertilization regimes:no fertilization(Control),chemical fertilization only(NPK),and NPK with wheat straw(NPK+HS),pig manure(NPK+PM),and cow manure(NPK+CM).Long-term NPK application differentially changed N-cycling gene abundance and greatly altered N-cycling microbial community structure.NPK+HS resulted in a similar pattern to NPK in terms of gene abundance and community structure.However,NPK+PM and NPK+CM significantly increased most genes and resulted in a community similar to that of the Control.Further analysis revealed that serious soil acidification caused by long-term NPK fertilization was a major factor for the variation in N-cycling microbial communities.The addition of alkaline manure,rather than wheat straw,stabilized the N-cycling microbial community structure presumably by alleviating soil acidification.These results revealed the strong impact of soil acidification on microbial N-cycling communities and illustrated the possibility of resolving nitrogen-related environmental problems by manipulating pH in acidified agricultural soils.展开更多
Comprehensive nitrogen biogeochemical cycle has been reconstructed for representative lacustrine organic-rich sedimentary rock in China,namely the Triassic Yanchang Formation(YF,199–230 Ma)in Ordos and the Cretaceous...Comprehensive nitrogen biogeochemical cycle has been reconstructed for representative lacustrine organic-rich sedimentary rock in China,namely the Triassic Yanchang Formation(YF,199–230 Ma)in Ordos and the Cretaceous Qingshankou Formation(QF,86–92 Ma)in Songliao basins,by evaluating the organic and inorganic nitrogen isotopic compositions rather than only organic or bulk nitrogen isotopic compositions.The results indicate that the nitrogen isotope values of bulk rock(δ^(15)N_(bulk))in the non-metamorphic stage are significantly different from that of kerogen,which challenge the conceptual framework of sedimentary nitrogen isotope interpretation.Theδ^(15)N_(bulk)from the YF and QF were lower than their respective the nitrogen isotope values of kerogen(δ^(15)N_(ker)),with offsets up to5.1‰,which have the inverse relationship for the metamorphosed rock.Thermal evolution did not significantly modify the d15N of bulk rock and kerogen.The d15N of sediments from the YF(δ^(15)N_(bulk),1.6‰–5.6‰)were lower than that of rock from the QF(δ^(15)N_(bulk),10.2‰–15.3‰).The nitrogen isotope values of silicate incorporated nitrogen(δ^(15)N_(sil))were slightly lower than those of the d15Nker in the YF and obviously lower for the QF.The fact that different nitrogen cycles occur in the YF and QF due to the different depositional redox conditions leads to different isotopic results.The YF water environment dominated by oxic conditions is not conducive to the occurrence of denitrification and anammox,and no abundant N2 loss leads to the relatively lightδ^(15)N_(bulk).In the stratified water for the QF,redox transition zone promotes denitrification and anammox,resulting in the heavyδ^(15)N_(bulk)of rock and promotes the DNRA,resulting in heavyδ^(15)N_(ker)and lowδ^(15)N_(sil).展开更多
Plant growth-promoting rhizobacteria(PGPR)represent an important microbial community group and have beneficial effects on plant growth and development.A pot experiment was conducted to study the effect of biochar appl...Plant growth-promoting rhizobacteria(PGPR)represent an important microbial community group and have beneficial effects on plant growth and development.A pot experiment was conducted to study the effect of biochar applied with PGPR on the soil microbial community composition and nitrogen use efficiency(NUE)of tomato,which could provide a theoretical basis for rational fertilization.Six treatments were designed:no nitrogen(N),PGPR,or biochar control(CK);biochar without N or PGPR(BCK);N without PGPR or biochar(U);N and PGPR without biochar(UP);N and biochar without PGPR(UB);and N,PGPR,and biochar(UBP).The tomato yield in the UP treatment was 9.09% lower than that in the U treatment,whereas that in the UB treatment was 19.93% higher than that in the U treatment.The tomato yield in the UBP treatment was 32.45%,45.69%,and 10.44% higher than those in the U,UP,and UB treatments,respectively.Biochar combined with PGPR increased the relative abundance of Nitrospira and Bradyrhizobium in the soil.At the tomato maturity stage,the soil NO_(3)^(-)-N content in the UBP treatment was 87.12%,88.12%,and 31.04% higher than those in the U,UP,and UB treatments,respectively.The NUE in the UP treatment was 4.03% lower than that in the U treatment,and that in the UBP treatment was 13.63%,17.66%,and 10.77% higher than those in the U,UP,and UB treatments,respectively.This study showed that biochar combined with PGPR can improve soil microbial community structure and increase the NUE of tomato.展开更多
基金The Strategic Priority Research Program of the Chinese Academy of Sciences under contract Nos XDA13020301 and XDA13010500the Fund of Innovation Academy of South China Sea Ecology and Environmental EngineeringChinese Academy of Sciences under contract No.ISEE2018PY01。
文摘Harboring polyextremotolerant microbial topsoil communities,biological soil crusts(biocrusts)occur across various climatic zones,and have been well studied in the terrestrial drylands.However,little is known about the functional metabolic potential of microbial communities involved in the biogeochemical processes during the early succession of biocrusts on the tropical reef islands.We collected 26 biocrusts and bare soil samples from the Xisha Islands and Nansha Islands,and applied a functional gene array(GeoChip 5.0)to reveal nitrogen(N)cycling processes involved in these samples.Both physicochemical measurement and enzyme activity assay were utilized to characterize the soil properties.Results revealed the composition of N-cycling functional genes in biocrusts was distinct from that in bare soil.Additionally,microorganisms in biocrusts showed lower functional potential related to ammonification,denitrification,N assimilation,nitrification,N fixation,and dissimilatory nitrate reduction to ammonium compared to bare soils.Although the abundance of nifH gene was lower in biocrusts,nitrogenase activity was significantly higher compared to that in bare soils.Precipitation,soil physicochemical properties(i.e.,soil available copper,soil ammonia N and pH)and soil biological properties(i.e.,β-glucosidase,fluorescein diacetate hydrolase,alkaline protease,urease,alkaline phosphatase,catalase and chlorophyll a)correlated to the N-cycling functional genes structure.Nitrate N and ammonia N were more abundant in biocrusts than bare soil,while pH value was higher in bare soil.Our results suggested biocrusts play an important role in N-cycling in coral sand soil,and will be helpful in understanding the development and ecological functions of biocrusts on tropical reef islands.
基金supported by the open Funds of laboratory of water environmental science of Hebei Province,China(No.HBSHJ202103)the Natural Science Foundation of Hebei Province of China(Nos.D2022504015,D2020504001 and D2021504003)+2 种基金the High-level talent Funding project of Hebei Province,China(No.A202101003)the Fundamental Research Funds for the Institute of Hydrogeology and Environmental Geology,Chinese Academy of Geological Sciences(Nos.SK202117 and SK202209)China Geological Survey,China(No.DD20221773)。
文摘The continuous increase of nitrate(NO_(3)^(-))level in rivers is a hot issue in the world.However,the driving mechanism of high NO_(3)^(-)level in large rivers is still lacking,which has limited the use of river water and increased the cost of water treatment.In this study,multiple isotopes and source resolution models are applied to identify the driving mechanism of high NO_(3)^(-)level and key processes of nitrogen cycling in the lower reaches of the Yellow River(LRYR).The major sources of NO_(3)^(-)were sewage and manure(SAM)in the low-flow season and soil nitrogen(SN)and chemical fertilizer(CF)in the high-flow season.Nitrification was the most key process of nitrogen cycling in the LRYR.However,in the biological removal processes,denitrification may not occur significantly.The temporal variation of contributions of NO_(3)^(-)sources were estimated by a source resolution model in the LRYR.The proportional contributions of SAM and CF to NO_(3)^(-)in the low-flow and high-flow season were 32.5%-52.3%,44.2%-46.2%and 36.0%-40.8%,54.9%-56.9%,respectively.The driving mechanisms of high NO_(3)^(-)level were unreasonable sewage discharge,intensity rainfall runoff,nitrification and lack of nitrate removal capacity.To control the NO_(3)^(-)concentration,targeted measures should be implemented to improve the capacity of sewage and wastewater treatment,increase the utilization efficiency of nitrogen fertilizer and construct ecological engineering.This study deepens the understanding of the driving mechanism of high nitrate level and provides a vital reference for nitrogen pollution control in rivers to other area of the world.
基金supported by the National Natural Science Foundation of China(41771336,41471267,4211101081,42161144002)Youth Innovation Promotion Association of the Chinese Academy of Sciences(Y2021102)+1 种基金Key Research and Development Program of Hunan Province(2020NK2011)Chinese Academy of Science and Technology Service Network Initiative Project(KFJ-STSQYZD-2021-22-002).
文摘The subtropical hilly region of China is a region with intensive crop and livestock production,which has resulted in serious N pollution in soil,water and air.This review summarizes the major soil N cycling processes and their influencing factors in rice paddies and uplands in the subtropical hilly region of China.The major N cycling processes include the N fertilizer application in croplands,atmospheric N deposition,biological N fixation,crop N uptake,ammonia volatilization,N_(2)O/NO emissions,nitrogen runoff and leaching losses.The catchment nutrients management model for N cycle modeling and its case studies in the subtropical hilly region were also introduced.Finally,N management practices for improving N use efficiency in cropland,as well as catchment scales are summarized.
基金supported by the National Key Research and Development Program of China(Grant No.2016YFD0600304-2)the National Natural Science Foundation of China(Grant Nos.31830015 and 41630755)Hunan Province Science and Technology Program(2017TP1040)
文摘Phenolic acids are secondary metabolites of plants that significantly affect nutrient cycling processes.To investigate such effects,the soil available nitrogen(N)content,phenolic acid content,and net N mineralization rate in three successive rotations of Chinese fir plantations in subtropical China were investigated.Net N mineralization and nitrification rates in soils treated with phenolic acids were measured in an ex situ experiment.Compared with first-rotation plantations(FCP),the contents of total soil nitrogen and nitrate in second(SCP)-and third-rotation plantations(TCP)decreased,and that of soil ammonium increased.Soil net N mineralization rates in the second-and third-rotation plantations also increased by 17.8%and 39.9%,respectively.In contrast,soil net nitrification rates decreased by 18.0%and 25.0%,respectively.The concentrations of total phenolic acids in the FCP soils(123.22±6.02 nmol g^-1)were 3.0%and 17.9%higher than in the SCP(119.68±11.69 nmol g^-1)and TCP(104.51±8.57 nmol g^-1,respectively).The total content of phenolic acids was significantly correlated with the rates of net soil N mineralization and net nitrification.The ex situ experiment showed that the net N mineralization rates in soils treated with high(HCPA,0.07 mg N kg^-1 day^-1)and low(LCPA,0.18 mg N kg^-1 day^-1)concentrations of phenolic acids significantly decreased by 78.6%and 42.6%,respectively,comparing with that in control(0.32 mg N kg^-1 day^-1).Soil net nitrification rates under HCPA and LCPA were significantly higher than that of the control.The results suggested that low contents of phenolic acids in soil over successive rotations increased soil net N mineralization rates and decreased net nitrification rates,leading to consequent reductions in the nitrate content and enhancement of the ammonium content,then resulting in enhancing the conservation of soil N of successive rotations in Chinese fir plantation.
基金kindly supported by the National Key Research and Development Program of China through grant 2016YFA0601000
文摘Southwest China is the primary area for damming rivers to produce hydroelectric energy and store water.River damming has changed hydrodynamic,chemical,and biological processes,which are related to sinks and sources of greenhouse gases and carbon and nitrogen fluxes of different interfaces.Here,I provide an introduction to a river damming-related foundation,the National Key R&D Program of China(2016YTA0601000).Supported by the foundation,we carried out research on multiprocesses/multi-interfaces of carbon and nitrogen biogeochemical cycles in a dammed river system and have produced important results,as presented in this issue of the journal.
基金The National Natural Science Foundation of China under contract No.41376086the Taishan Scholars Programme of Shandong Provincethe Aoshan Talents Program supported by the Pilot National Laboratory for Marine Science and Technology(Qingdao)under contract No.2015ASTP-OS08。
文摘The coastal upwelling has profound influence on the surrounding ecosystem by supplying the nutrient-replete water to the euphotic zone.Nutrient biogeochemistry was investigated in coastal waters of the eastern Hainan Island in summer 2015 and autumn 2016.From perspectives of nutrient dynamics and physical transport,the nutrient fluxes entered the upper 50 m water depth(between the mixed layer and the euphotic zone)arisen from the upwelling were estimated to be 2.5-5.4 mmol/(m^(2)·d),0.15-0.28 mmol/(m^(2)·d),and 2.2-7.2 mmol/(m^(2)·d)for dissolved inorganic nitrogen(DIN),phosphate(DIP),and dissolved silicate(DSi),respectively,which were around 6-to 12-fold those in the background area.The upwelled nutrients supported an additional plankton growth of(14.70±8.95)mg/m^(2)for chlorophyll a(Chl a).The distributions of nitrateδ^(15)N andδ^(18)O above the 300 m water depth(top of the North Pacific Intermediate Water)were different among the upwelling area,background area in summer,and the stations in autumn,and the difference of environmental and biogeochemical conditions between seasons should be the reason.The higher DIN/DIP concentration ratio,nitrate concentration anomaly,and lower nitrate isotope anomaly(Δ(15,18))in the upper ocean in summer than in autumn indicated the stronger nitrogen fixation and atmospheric deposition,and the following fixed nitrogen regeneration in summer.The higher values of Chl a and nitrateδ^(15)N andδ^(18)O within the euphotic zone in autumn than the background area in summer suggested the stronger nitrate assimilation in autumn.The differences in relatively strength of the assimilation,nitrogen fixation and atmospheric deposition,and the following remineralization and nitrification between the two seasons made the higherδ^(18)O:δ^(15)N and larger difference of enzymatic isotope fractionation factors^(15)εand^(18)εfor nitrate assimilation in summer than in autumn above the North Pacific Tropical Water.
基金supported by the State Key Development Program for Basic Research of China(No.2015CB158200)。
文摘The application of butachlor as an herbicide in paddy fields is widely practiced,aiming to increase rice yield by directly or indirectly influencing the paddy environment.Periphytic biofilms,which form at the soil-water interface in paddy fields,are complex bioaggregates that play an important role in nitrogen (N) cycling.The objective of this study was to investigate the effect of butachlor on periphytic biofilm growth and N cycling under both light and dark conditions in the laboratory.The results revealed that butachlor application hindered the growth of periphytic biofilms and led to the dominance of Cyanobacteria as the primary prokaryotes,while inhibiting the development of eukaryotic Trebouxiophyceae.Furthermore,the application of butachlor reduced the richness and diversity of prokaryotes,but increased those of eukaryotes in periphytic biofilms.The light treatments exhibited higher total N loss because light favored periphytic biofilm growth and enhanced ammonium (NH_(4)^(+)) assimilation and nitrification.Additionally,butachlor application resulted in the increased retention of NH_(4)^(+)-N and nitrate (NO_(3)^(-))-N and an increase in N loss via denitrification.The abundances of functional genes encoding enzymes such as ammonia monooxygenase,nitrite reductase,and nitrous oxide reductase were increased by butachlor application,favoring nitrification and denitrification processes.Overall,the results suggest that butachlor application leads to an increase in total N loss mainly through denitrification in paddy systems,particularly in the presence of periphytic biofilms.Thus,the results may provide valuable insights into the changes in periphytic biofilm growth and N cycling induced by butachlor,and future studies can further explore the potential implications of these changes in paddy soils.
基金Tarbiat Modares University for the financial support of the study reported in this paper
文摘Beech stands are considered part of the ancient forest ecosystems in the northern hemisphere.In mixed stands in beach forest ecosystems,the type of associated tree species can signifi cantly aff ect soil functions,but their infl uence on microbial activity,nutrient cycling and belowground properties is unknown.Here,we considered forest patches in northern Iran that are dominated by diff erent tree species:Fagus orientalis Lipsky,Quercus castaneifolia C.A.Mey.,Pterocarya fraxinifolia(Lam.),Tilia begonifolia Stev.,Zelkova carpinifolia Dippe,Acer cappadocicum Gled,Acer velutinum Boiss.,Fraxinus excelsior L.,Carpinus betulus L.,and Alnus subcordata C.A.Mey.For each forest patch–tree species,litter and soil samples(25×25×10 cm,100 of each)were analyzed for determine soil and litter properties and their relationship with tree species.The litter decomposition rate during a 1-year experiment was also determined.A PCA showed a clear diff erence between selected litter and soil characteristics among tree species.F.orientalis,Q.castaneifolia,P.fraxinifolia,T.begonifolia,Z.carpinifolia,A.cappadocicum,and A.velutinum enhanced soil microbial biomass of carbon,whereas patches with F.excelsior,C.betulus and A.subcordata had faster litter decomposition and enhanced biotic activities and C and N dynamics.Thus,soil function indicators were species-specifi c in the mixed beech forest.A.subcordata(a N-fi xing species),C.betulus and F.excelsior were main drivers of microbial activities related to nutrient cycling in the old-growth beech forest.
基金supported by the National Natural Science Foundation of China(22202151)Fundamental Research Program of Shanxi Province(202203021212243)。
文摘Ammonia plays an essential role in human production and life as a raw material for chemical fertilizers.The nitrate electroreduction to ammonia reaction(NO_(3)RR)has garnered attention due to its advantages over the Haber-Bosch process and electrochemical nitrogen reduction reaction.Therefore,it represents a promising approach to safeguard the ecological environment by enabling the cycling of nitrogen species.This review begins by discussing the theoretical insights of the NO_(3)RR.It then summarizes recent advances in catalyst design and construction strategies,including alloying,structure engineering,surface engineering,and heterostructure engineering.Finally,the challenges and prospects in this field are presented.This review aims to guide for enhancing the efficiency of electrocatalysts in the NO_(3)RR,and offers insights for converting NO_(3)-to NH_(3).
基金supported by the National Natural Science Foundation of China (No. 42177363)the National Key R&D Program of China (No. 2019YFC1805502)+1 种基金the Open Project of National and Local Joint Engineering Research Center of Shale Gas Exploration and Development (No. YYQKTKFGJDFLHGCYJZX-201904)the Innovation Support Program for Chongqing Overseas Returnees (2017)。
文摘As one typical cationic disinfectant, quaternary ammonium compounds(QACs) were approved for surface disinfection in the coronavirus disease 2019 pandemic and then unintentionally or intentionally released into the surrounding environment. Concerningly, it is still unclear how the soil microbial community succession happens and the nitrogen(N)cycling processes alter when exposed to QACs. In this study, one common QAC(benzalkonium chloride(BAC) was selected as the target contaminant, and its effects on the temporal changes in soil microbial community structure and nitrogen transformation processes were determined by q PCR and 16S r RNA sequencing-based methods. The results showed that the aerobic microbial degradation of BAC in the two different soils followed first-order kinetics with a half-life(4.92 vs. 17.33 days) highly dependent on the properties of the soil. BAC activated the abundance of N fixation gene(nif H) and nitrification genes(AOA and AOB) in the soil and inhibited that of denitrification gene(nar G). BAC exposure resulted in the decrease of the alpha diversity of soil microbial community and the enrichment of Crenarchaeota and Proteobacteria. This study demonstrates that BAC degradation is accompanied by changes in soil microbial community structure and N transformation capacity.
基金supported by National Natural Science Foundation of China(42007073)。
文摘The rhizosphere is the most active soil area for material transformation and energy flow of soil,root,and microorganism,which plays an important role in soil biochemical cycling.Although the rhizospheric nitrogen(N)and phosphorous(P)were easily disturbed in the agroecosystem,the effects of rhizosphere on the dynamics of soil N and P cycling have not yet been systematically quantified globally.We summarized the magnitude,direction,and driving forces of rhizosphere effects on agroecosystem's N and P dynamics by 1063 observations and 15 variables from 122 literature.Rhizosphere effects increased available N(AN,9%),available P(AP,11%),and total P(TP,5%),and decreased nitrate N(NO_(3)-N,18%)and ammonia N(NH_(4)-N,16%).The effect of rhizosphere on total N(TN)was not significant.These effects improved AN in tropical(12%)and subtropical(14%)regions.The effect of rhizosphere on TP was greater under subtropical conditions than in other climates.The most substantial effects of the rhizosphere on TP and AP were observed under humid conditions.Rhizosphere effects increased AN and AP in vegetables more than in other crop systems.Application of N>30o kg ha^(-1) had the most significant and positive rhizosphere effects on TN and AN.P application of 100-150 kg ha^(-1) had the greatest rhizosphere effects on TP and AP.These effects also improved the microbial(biomass N and P)and enzymatic aspects(urease,acid phosphatase,and alkaline phosphatase)of soil P and N cycling.Structural equation modeling suggested that aridity indices,fertilizer application rate,soil pH,microbial biomass,and soil enzymes strongly influence the magnitude and direction of the rhizosphere's effect on the P and N cycles.Overall,these findings are critical for improving soil nutrient utilization efficiency and modeling nutrient cycling in the rhizosphereforagricultural systems.
基金supported by the National Science and Technology Major Project of China (2014ZX07201-009)
文摘Seasonal soil freeze-thaw events may enhance soil nitrogen transformation and thus stimulate nitrous oxide(N_2O)emissions in cold regions.However,the mechanisms of soil N_2O emission during the freeze-thaw cycling in the field remain unclear.We evaluated N_2O emissions and soil biotic and abiotic factors in maize and paddy fields over 20 months in Northeast China,and the structural equation model(SEM)was used to determine which factors affected N_2O production during non-growing season.Our results verified that the seasonal freeze-thaw cycles mitigated the available soil nitrogen and carbon limitation during spring thawing period,but simultaneously increased the gaseous N_2O-N losses at the annual time scale under field condition.The N_2O-N cumulative losses during the non-growing season amounted to 0.71 and 0.55 kg N ha^(–1) for the paddy and maize fields,respectively,and contributed to 66 and 18%of the annual total.The highest emission rates(199.2–257.4μg m^(–2) h^(–1))were observed during soil thawing for both fields,but we did not observe an emission peak during soil freezing in early winter.Although the pulses of N_2O emission in spring were short-lived(18 d),it resulted in approximately80%of the non-growing season N_2O-N loss.The N_2O burst during the spring thawing was triggered by the combined impact of high soil moisture,flush available nitrogen and carbon,and rapid recovery of microbial biomass.SEM analysis indicated that the soil moisture,available substrates including NH_4^+and dissolved organic carbon(DOC),and microbial biomass nitrogen(MBN)explained 32,36,16 and 51%of the N_2O flux variation,respectively,during the non-growing season.Our results suggested that N_2O emission during the spring thawing make a vital contribution of the annual nitrogen budget,and the vast seasonally frozen and snow-covered croplands will have high potential to exert a positive feedback on climate change considering the sensitive response of nitrogen biogeochemical cycling to the freeze-thaw disturbance.
基金supported by the National Key Research and Development Program of China(No.2018YFD1100503).
文摘Heterotrophic nitrification-aerobic denitrification(HNAD)is essential in diverse nitrogen-transforming processes.How HNAD is modulated by quorum sensing(QS)systems is still ambiguous.The QS system in Pseudomonas aeruginosa manipulates colony behavior.Here,we described the influence of the Pseudomonas quinolone signal(PQS)and N-acyl-L-homoserine lactone(AHL)on HNAD.The HNAD of P.aeruginosa was inhibited by the oversecretion of PQS.AHL-or PQS-deficient P.aeruginosa mutants had a higher ability for nitrogen removal.QS inhibited heterotrophic nitrification mainly via controlling the activity of nitrite oxidoreductase(NXR)and the depressed aerobic denitrification by regulating the catalytic abilities of nitric oxide reductase(NOR),nitrite reductase(NIR),and nitrate reductase(NAR).The addition of citrate as the sole carbon source increased the nitrogen removal efficiency compared with other carbon sources.Nitrite,as the sole nitrogen source,could be used entirely with only the moderate concentration of PQS contained.AHL and PQS controlled both nitrification and denitrification,suggesting that QS plays an important role in nitrogen cycle under aerobic conditions.
基金The Natural Science Foundation of Shanghai under contract No.19ZR1415300the Zhejiang Provincial Natural Science Foundation of China under contract No.LQ21D060005the China Postdoctoral Science Foundation under contract No.2020M681931。
文摘Saltmarshes are one of the most productive ecosystems,which contribute significantly to coastal nutrient and carbon budgets.However,limited information is available on soil nutrient and carbon losses via porewater exchange in saltmarshes.Here,porewater exchange and associated fluxes of nutrients and dissolved inorganic carbon(DIC)in the largest saltmarsh wetland(Chongming Dongtan)in the Changjiang River Estuary were quantified.Porewater exchange rate was estimated to be(37±35)cm/d during December 2017 using a radon(^(222)Rn)mass balance model.The porewater exchange delivered 67 mmol/(m^(2)·d),38 mmol/(m^(2)·d)and 2690 mmol/(m^(2)·d)of dissolved inorganic nitrogen(DIN),dissolved silicon(DSi)and DIC into the coastal waters,respectively.The dominant species of porewater DIN was NH_(4)^(+)(>99%of DIN).However,different with those in other ecosystems,the dissolved inorganic phosphorus(DIP)concentration in saltmarsh porewater was significantly lower than that in surface water,indicating that saltmarshes seem to be a DIP sink in Chongming Dongtan.The porewater-derived DIN,DSi and DIC accounted for 12%,5%and 18%of the riverine inputs,which are important components of coastal nutrient and carbon budgets.Furthermore,porewater-drived nutrients had obviously high N/P ratios(160–3995),indicating that the porewater exchange process may change the nutrient characteristics of the Changjiang River Estuary and further alter the coastal ecological environment.
基金supported by the National Key Research and Development Program of China(Grant No.2016YFD0300504)Liaoning Revitalization Talent Program of China(Grant No.XLYC1807233).
文摘Over the past 30 years,super rice played an important role in boosting rice yield.The phenotype of erect panicle(EP)architecture controlled by dense and erect panicle 1(dep1)is the typical characteristic of super rice,and the phenotype has been used in rice breeding for nearly a century.In this review,the molecular genetic basis of EP phenotype,and mechanism of how dep1 affects rice carbon,nitrogen metabolism and grain quality(grain shape and taste quality)were discussed.In addition,we discussed the possible improvement strategies of rice yield and quality.This review provides a quick overview of the whole process for rice quality formation,as well as suggestions and ideas for future research on rice quality improvement.
基金financial assistance and support from the Hubei Key Laboratory of Construction and Management in Hydropower Engineering,China Three Gorges University(No.2020KSD09)the National Key Research and Development Program of China(2017YFC0504102)+1 种基金the National Natural Science Foundation of China(51979147)the Ministry of Finance,the Ministry of Industry and Information Technology,and the Ministry of Science and Technology for support of the High Tech Zone in Yichang in creating a special project for highly talented research(No.B19-004)。
文摘Environmental changes significantly alter the structure,diversity and activity of soil microbial communities during spring freezing-thawing period,leading to changes in the soil microbial nitrogen cycle.Changes in N_(2)O fluxes after land use conversion from primary forest to secondary forest,Korean pine plantation and cropland in northeast China have not been quantified.Field experiments were conducted to measure soil N_(2)O fluxes in a primary forest,two secondary forests,a Korean pine plantation,and one maize field in a temperate region in northeast China from 2017-03-06 to 2017-05-28.During the experimental period,the soil was exclusively a nitrogen source for all land uses.We found that N_(2)O emissions ranged from 15.63 to 68.74μg m^(-2) h^(-1),and cumulative N_(2)O emissions ranged from 0.33 to 2.10 kg ha^(-1) during the period.Cumulative N_(2)O emissions from the maize field were significantly higher than that from primary forest,Korean pine plantation,hardwood forest,and Betula platyphylla forest by 262.1% to 536.4%.Compared with other ecosystems in similar studies,the N_(2)O emission rates of all ecosystem types in this study were low during the spring thaw period.Stepwise multiple linear regression indicated that there were significant correlations between N_(2)O emissions and environmental factors(air temperature and soil temperature,soil water content,soil p H,NH_(4)^(+)-N,NO_(3)^(-)-N,and soil organic carbon).The results showed that conversion of land use from primary forest to hardwood forest,Korean pine plantation or maize field greatly increased soil N_(2)O emissions during spring freezing-thawing period,and N_(2)O emissions from primary forest were almost the same as those from Betula platyphylla forest.
基金supported by the National Natural Science Foundation of China(31988102)the National Key Research and Development Program of China(2022YFF0802102)。
文摘Carbon-nitrogen coupling is a fundamental principle in ecosystem ecology.However,how the coupling responds to global change has not yet been examined.Through a comprehensive and systematic literature review,we assessed how the dynamics of carbon processes change with increasing nitrogen input and how nitrogen processes change with increasing carbon input under global change.Our review shows that nitrogen input to the ecosystem mostly stimulates plant primary productivity but inconsistently decreases microbial activities or increases soil carbon sequestration,with nitrogen leaching and nitrogenous gas emission rapidly increasing.Nitrogen fixation increases and nitrogen leaching decreases to improve soil nitrogen availability and support plant growth and ecosystem carbon sequestration under elevated CO_(2)and temperature or along ecosystem succession.We conclude that soil nitrogen cycle processes continually adjust to change in response to either overload under nitrogen addition or deficiency under CO_(2)enrichment and ecosystem succession to couple with carbon cycling.Indeed,processes of both carbon and nitrogen cycles continually adjust under global change,leading to dynamic coupling in carbon and nitrogen cycles.The dynamic coupling framework reconciles previous debates on the“uncoupling”or“decoupling”of ecosystem carbon and nitrogen cycles under global change.Ecosystem models failing to simulate these dynamic adjustments cannot simulate carbonnitrogen coupling nor predict ecosystem carbon sequestration well.
基金This work was supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB40020204)the National Key R&D Program of China(Grant No.2021YFF1000403).
文摘Straw and manure are widely applied to agricultural systems,and greatly shape soil N-cycling microflora.However,we still lack a comprehensive understanding of how these organic materials structure soil N-cycling microbial communities.In this study,metagenomic analysis was performed to investigate the compositional variation in N-cycling microbial communities in a 30-year long-term experiment under five fertilization regimes:no fertilization(Control),chemical fertilization only(NPK),and NPK with wheat straw(NPK+HS),pig manure(NPK+PM),and cow manure(NPK+CM).Long-term NPK application differentially changed N-cycling gene abundance and greatly altered N-cycling microbial community structure.NPK+HS resulted in a similar pattern to NPK in terms of gene abundance and community structure.However,NPK+PM and NPK+CM significantly increased most genes and resulted in a community similar to that of the Control.Further analysis revealed that serious soil acidification caused by long-term NPK fertilization was a major factor for the variation in N-cycling microbial communities.The addition of alkaline manure,rather than wheat straw,stabilized the N-cycling microbial community structure presumably by alleviating soil acidification.These results revealed the strong impact of soil acidification on microbial N-cycling communities and illustrated the possibility of resolving nitrogen-related environmental problems by manipulating pH in acidified agricultural soils.
基金supported by the National Natural Science Foundation of China(General Program,No.41972127)the National Key Research and Development Program of China(No.2021YFA0719000)。
文摘Comprehensive nitrogen biogeochemical cycle has been reconstructed for representative lacustrine organic-rich sedimentary rock in China,namely the Triassic Yanchang Formation(YF,199–230 Ma)in Ordos and the Cretaceous Qingshankou Formation(QF,86–92 Ma)in Songliao basins,by evaluating the organic and inorganic nitrogen isotopic compositions rather than only organic or bulk nitrogen isotopic compositions.The results indicate that the nitrogen isotope values of bulk rock(δ^(15)N_(bulk))in the non-metamorphic stage are significantly different from that of kerogen,which challenge the conceptual framework of sedimentary nitrogen isotope interpretation.Theδ^(15)N_(bulk)from the YF and QF were lower than their respective the nitrogen isotope values of kerogen(δ^(15)N_(ker)),with offsets up to5.1‰,which have the inverse relationship for the metamorphosed rock.Thermal evolution did not significantly modify the d15N of bulk rock and kerogen.The d15N of sediments from the YF(δ^(15)N_(bulk),1.6‰–5.6‰)were lower than that of rock from the QF(δ^(15)N_(bulk),10.2‰–15.3‰).The nitrogen isotope values of silicate incorporated nitrogen(δ^(15)N_(sil))were slightly lower than those of the d15Nker in the YF and obviously lower for the QF.The fact that different nitrogen cycles occur in the YF and QF due to the different depositional redox conditions leads to different isotopic results.The YF water environment dominated by oxic conditions is not conducive to the occurrence of denitrification and anammox,and no abundant N2 loss leads to the relatively lightδ^(15)N_(bulk).In the stratified water for the QF,redox transition zone promotes denitrification and anammox,resulting in the heavyδ^(15)N_(bulk)of rock and promotes the DNRA,resulting in heavyδ^(15)N_(ker)and lowδ^(15)N_(sil).
基金funded by the National Key R&D Program of China(No.2017YFD0200804)the Shandong Provincial Key R&D Program of China(No.2017CXGC0306)the Shandong Provincial Development Plan of China(No.2013GNC11309)。
文摘Plant growth-promoting rhizobacteria(PGPR)represent an important microbial community group and have beneficial effects on plant growth and development.A pot experiment was conducted to study the effect of biochar applied with PGPR on the soil microbial community composition and nitrogen use efficiency(NUE)of tomato,which could provide a theoretical basis for rational fertilization.Six treatments were designed:no nitrogen(N),PGPR,or biochar control(CK);biochar without N or PGPR(BCK);N without PGPR or biochar(U);N and PGPR without biochar(UP);N and biochar without PGPR(UB);and N,PGPR,and biochar(UBP).The tomato yield in the UP treatment was 9.09% lower than that in the U treatment,whereas that in the UB treatment was 19.93% higher than that in the U treatment.The tomato yield in the UBP treatment was 32.45%,45.69%,and 10.44% higher than those in the U,UP,and UB treatments,respectively.Biochar combined with PGPR increased the relative abundance of Nitrospira and Bradyrhizobium in the soil.At the tomato maturity stage,the soil NO_(3)^(-)-N content in the UBP treatment was 87.12%,88.12%,and 31.04% higher than those in the U,UP,and UB treatments,respectively.The NUE in the UP treatment was 4.03% lower than that in the U treatment,and that in the UBP treatment was 13.63%,17.66%,and 10.77% higher than those in the U,UP,and UB treatments,respectively.This study showed that biochar combined with PGPR can improve soil microbial community structure and increase the NUE of tomato.
