• Volume 14,Issue 1,2022 Table of Contents
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    • A meta-analysis of response and feedback of terrestrial carbon and nitrogen cycling to drought

      2022, 14(1):1-10. DOI: 10.13878/j.cnki.jnuist.2022.01.001

      Abstract (520) HTML (248) PDF 2.34 M (1492) Comment (0) Favorites

      Abstract:Drought has been shown to alter terrestrial ecosystem carbon (C) and nitrogen (N) dynamics,and thus feedback to future climate.However,drought-induced changes in terrestrial upland C and N pools and the drought response of soil carbon dioxide (CO2) and nitrous oxide (N2O) fluxes are yet to be quantified.A meta-analysis was conducted that compiled 1 344 measurements from 128 manipulative studies worldwide to obtain a general picture of terrestrial C and N cycling responses to soil drought stress and identify the primary driving factors.We showed that drought significantly decreased plant C pools,with stronger negative responses of aboveground than belowground C components.Drought significantly decreased soil CO2 and N2O fluxes.There were non-significant changes in soil organic C and N pools in response to drought;in contrast to a considerable decrease in soil dissolved organic C,there was a robust increase in soil NO3--N following short-term drought impact.Furthermore,drought also significantly decreased Net Ecosystem Productivity (NEP).Our study provides insights into soil release of CO2 and N2O with a linkage to the changes in terrestrial C and N pools in response to drought across upland biomes.Our findings highlight that,despite the lowered soil C release rate,the capacity of upland biomes as a C sink to slow climate change would still be weakened in a future drier climate.

    • Variations and controlling factors of carbon fluxes from a restored mangrove wetland

      2022, 14(1):11-20. DOI: 10.13878/j.cnki.jnuist.2022.01.002

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      Abstract:Mangroves are important blue carbon ecosystems.During the restoration processes,the carbon exchange processes of mangroves are affected by climate and vegetation factors,thus show different characteristics from those of mature mangroves.In this study,we observed the characteristics of CO2 and CH4 fluxes from a restored mangrove at Pearl River estuary based on the closed-path eddy covariance system.We further analyzed the influences of environmental factors on carbon fluxes by path analysis method.The observations showed significant diurnal variations in CO2 fluxes.There were no significant seasonal variations in CO2 fluxes due to the collaborative impact of Gross Primary Productivity (GPP) and ecosystem respiration (Re).The seasonal variations of CH4 fluxes were significant.During 2019-2020,the annual CO2 fluxes were 79.4-138.4 g·m-2·a-1,and the annual CH4 fluxes were 25.1-25.9 g·m-2·a-1.Path analysis showed that GPP directly influenced the seasonal variation of CO2 fluxes.The radiation (Ra),air temperature (Ta) and vegetation index (NDVI) had indirect impact on CO2 seasonal variations.While seasonal variations of CH4 fluxes were directly influenced by Ta,Re and NDVI.

    • Characteristics of dissolved organic carbon in algal-dominated lake and its influence on methane emission

      2022, 14(1):21-31. DOI: 10.13878/j.cnki.jnuist.2022.01.003

      Abstract (566) HTML (545) PDF 4.37 M (1529) Comment (0) Favorites

      Abstract:The carbon cycle in lakes has been receiving great concerns and has become a hot issue.This study aimed at investigating the characteristics of Dissolved Organic Carbon (DOC) and its influence on methane emission based on continuous field sampling in a year cycle from algal-dominated zones of Lake Taihu.Results showed that the DOC with mean value of 4.15 mg/L varied spatially due to external input and internal algal blooms.Overall,peak DOC occurred in Northwest Zone and Meiliang Bay,and temporal variations of DOC in the two zones were associated with basin precipitation,especially for Northwest Zone (R2=0.67,P<0.01).It should be noted that the temporal variation of DOC in Central Zone were highly positively correlated with algal biomass mostly due to the less external input.The CH4 diffusion emission flux with mean value of 0.083 mmol·m-2·d-1 varied greatly across zones.Algal blooms significantly stimulated the CH4 emissions via increasing DOC concentration.Overall,the algal-dominated lake was a hot spot of CH4 emission due to DOC enrichment.Considering the effects of DOC on lake CH4 emission was regulated by multiple factors related to internal metabolic activities and external loading,further studies are needed to reveal the potential control mechanism.

    • Effects of four plant growth-promoting rhizo bacteria on N2O emission from farmland soil

      2022, 14(1):32-39. DOI: 10.13878/j.cnki.jnuist.2022.01.004

      Abstract (527) HTML (106) PDF 2.69 M (1555) Comment (0) Favorites

      Abstract:Farmland soil is one of the most important anthropogenic sources of nitrous oxide (N2O).In this paper,four plant growth-promoting rhizo bacteria were used as the candidate strains,namely Bacillus albus Lv5A,Bacillus subtilis sp.subtilis NRCB002,Pseudomonas stutzeri NRCB010,and Bacillus siamensis NRCB026.The greenhouse pot experiment,soil microcosm experiment,and field plot experiment were established to explore the effect of these growth-promoting rhizo bacteria on N2O emission from farmland soil.The results showed that cumulative N2O emissions from tested soils were NRCB002 > Lv5A > NRCB026 > NRCB010 after the inoculation with these four growth-promoting rhizo bacteria in the greenhouse pot experiment.The cumulative N2O emissions were decreased by 2.3%,33.1%,34.2% and 40% after the inoculation with these four strains compared with that from the non-inoculated control.Then two strains of NRCB010 and NRCB026 were chosen for further soil microcosm experiment and field experiment.The inoculation with NRCB010 decreased the cumulative N2O emissions by 21% and 44% in soil microcosm and field plot experiment,respectively;while the inoculation with NRCB026 decreased the cumulative N2O emissions by 48% and 73% in soil microcosm and field plot experiments,respectively.In conclusion,plant growth-promoting rhizo bacteria NRCB010 and NRCB026 can effectively mitigate N2O emission from farmland soil.Our results provides critical scientific basis for N2O mitigation in farmland soil and important practical guidance for development of novel biofertilizer with both plant growth-promoting and greenhouse gas mitigating effects.

    • Atmospheric CO2 concentration and its influence factors during 2020 COVID-19 pandemic in Nanchang

      2022, 14(1):40-49. DOI: 10.13878/j.cnki.jnuist.2022.01.005

      Abstract (130) HTML (53) PDF 5.23 M (1460) Comment (0) Favorites

      Abstract:The atmospheric CO2 concentrations are mainly influenced by regional sinks/sources and atmospheric transport processes,thus observations in urban area contain essential information of anthropogenic CO2 emissions.To investigate the effect of COVID-19 on atmospheric CO2 concentration and its anthropogenic emissions,this study chose Nanchang city as the study area and used a priori emission inventory with WRF-STILT (Stochastic Time-Inverted Lagrangian Transport) atmospheric transport model to simulate hourly CO2 concentrations from January 24th to April 30th,2020.In accordance with the government measures to control COVID-19 epidemic,the whole study period was divided into two periods of Level 1 period (from January 24th to March 11th) and Level 2 period (from March 12th to April 30th).Results indicate the model can well capture hourly variations of CO2 concentration,but it overestimated nighttime concentrations due to the negligence of emission source height.During Level 1 period,the observed and simulated afternoon (12:00-18:00) CO2 mole fractions were 433.63×10-6 and 438.22×10-6,respectively,in which the anthropogenic emissions were 21.9% overestimated by simulation compared with observations.While during Level 2 period,the observation and simulation were very close as 432.06×10-6 and 432.24×10-6.The above comparisons indicate that the CO2 emissions can be represented by a priori CO2 emission inventory in Level 2 period,but was overestimated by 21.9% in Level 1 period,and the discrepancy was mainly due to government measures to control COVID-19 pandemic during this period.Besides,the average biological NEE enhancements were generally lower than 2×10-6,indicating a small contribution compared with anthropogenic emissions.The higher PBLH (Planetary Boundary Layer Height) in Level 2 period also offset the enhancement in CO2 emissions,which was also the main reason for the close observations during two periods.Our findings can provide scientific method supports for greenhouse gas emission inversions at urban scale.

    • Effects of digested dairy slurry application on soil aggregates and their organic carbon composition in wheat and maize rotation system

      2022, 14(1):50-61. DOI: 10.13878/j.cnki.jnuist.2022.01.006

      Abstract (606) HTML (59) PDF 1.59 M (1443) Comment (0) Favorites

      Abstract:The organic carbon in soil aggregates plays an important role in the dynamic balance of soil carbon pool.In order to explore the impacts of digested dairy slurry application on soil aggregates and their organic carbon composition,this study was carried out in a wheat and maize rotation system applied with digested dairy slurry for two years.The characteristics of soil aggregates and their total organic carbon and compositions in soil layer of 0-10 cm and 10-20 cm were studied after harvest.The results were that the stability of soil aggregates increased significantly (P<0.05) after the digested dairy slurry application.The digested dairy manure was beneficial to the improvement of macro aggregates.Meanwhile,this trend was more obvious with the increase of the amount of digested dairy slurry.The soil carbon stock in the treatment of digested dairy slurry application increased by 25.9%-35.2% compared with that in treatments of chemical fertilizer application.The changes of soil carbon stock were mainly due to high-activity organic carbon.The soil carbon pool activity was improved due to the input of labile carbon in the digested dairy slurry.In addition,the soil carbon pool activity in the soil layer of 10-20 cm was more sensitive to the input of additive organic matters.The highly active organic carbon in the macro aggregates was the main drive factor.This study could provide scientific support for the reasonable application of digestates for the improvement of carbon sequestration potential from the farmland ecosystems.

    • Effects of experimental warming and Spartina alterniflora invasion on soil carbon cycle functional genes in Chongming Dongtan wetland

      2022, 14(1):62-76. DOI: 10.13878/j.cnki.jnuist.2022.01.007

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      Abstract:The carbon cycling process in wetland ecosystems has an important impact on global climate change.In this study,we used the GeoChip technology to detect the key functional genes of soil carbon cycle in the wetland soil of Chongming Dongtan,China.We also studied the effects of experimental warming and Spartina alterniflora invasion on carbon cycle of wetland soil and their relationships with environmental factors.The results showed that:1) the number and abundance of functional genes in soil carbon cycle were higher than those in other categories;2) the signal intensity of functional soil carbon cycle genes was higher in S.alterniflora community than in Phragmites australis community with the same temperature treatment;3) warming significantly reduced the signal intensity of most functional genes in soil carbon cycle,including the basic processes of carbon degradation,carbon fixation,and methane metabolism,but the influence was not significant for the S.alterniflora invasion and its interaction with warming (P>0.05);4) compared with the control,warming significantly reduced the abundance of functional genes of carbon cycle in the P.australis community,mainly including cda,exopolygalacturonase_fungi,rgh,xyla,xylanase,cellobiase and endoglucanase genes in the carbon degradation process and rubisco genes related to Calvin cycle during carbon fixation (P<0.01),but the changes were not significant in the S.alterniflora community and their mixed community (P>0.05);5) soil microbial carbon cycle functional genes were significantly and negatively correlated with soil reactive nitrogen gas emission and soil pH (P<0.05).In conclusion,warming significantly changes the functional gene abundances of soil carbon cycle.The research results provide data support for quantifying the impact of global warming on wetland carbon cycle and greenhouse gas emissions,and realizing carbon neutralization,and also provide scientific basis for the protection and management of wetland ecosystem.

    • Effect of different elevated CO2 concentrations and nitrogen application on net CO2 fluxes in wheat field

      2022, 14(1):77-87. DOI: 10.13878/j.cnki.jnuist.2022.01.008

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      Abstract:To investigate the effect of different CO2 concentrations and nitrogen application on net CO2 fluxes in wheat field,an automatic CO2 concentration control platform consisting of open-top chamber (OTC) was used to simulate an elevated CO2 concentration environment.Three CO2 concentration levels were set:CK (ambient atmospheric CO2 concentration),C1(CO2 concentration increased by 120 μmol·mol-1 compared with CK) and C2(CO2 concentration increased by 200 μmol·mol-1 compared with CK);two nitrogen fertilizer treatments were set at regular nitrogen fertilizer (N1,25 g·m-2) and low nitrogen fertilizer (N2,15 g·m-2).The net CO2 fluxes in the wheat field were observed using a static chamber-high precision gas analyzer.The results showed a consistent trend of net CO2 fluxes in wheat field under all treatments:increased until peaked at the jointing and heading stages,and then decreased.Under the N1 treatment,the CO2 accumulation under CK,C1 and C2 treatments were-105.8±12.6,-123.1±11.5 and-120.2±4.1 kg·hm-2,respectively.Under the N2 treatment,the CO2 accumulation under CK,C1 and C2 treatments were-82.3±9.2,-95.4±7.6 and-96.7±2.8 kg·hm-2,respectively;the CO2 accumulation of C2 treatment at jointing stage was significantly higher than that of CK by 31.8%(P=0.024).Under the C1 treatment,the CO2 accumulation of N1 treatment was significantly higher than that of N2 treatment by 55.0%(P=0.009) at the jointing stage.Under the C2 treatment,the CO2 accumulation of N1 treatment was significantly higher than that of N2 treatment by 23.6%(P=0.010) during the whole growth stage.The correlation between net CO2 fluxes and soil moisture reached significance under all treatments.Under the N1 treatment,the correlation between net CO2 fluxes and photosynthetic effective radiation under C1 and C2 treatments was significant,and under the N2 treatment,the correlation between net CO2 fluxes and photosynthetic effective radiation under CK and C1 treatment was significant.Under the N1 treatment,the correlation between net CO2 fluxes and air temperature was significant only under C1 treatment.This study showed that the effect of nitrogen application on the net CO2 fluxes in wheat field was more significant than that of elevated CO2 concentration at the jointing and heading stages of wheat,and there was no significant interaction between the elevated CO2 concentration and nitrogen application on the net CO2 fluxes in wheat field.

    • Effect of soil biochemical properties on soil respiration and N2O emission under simulated nitrogen deposition

      2022, 14(1):88-97. DOI: 10.13878/j.cnki.jnuist.2022.01.009

      Abstract (136) HTML (87) PDF 1.42 M (1405) Comment (0) Favorites

      Abstract:Soil respiration and nitrous oxide (N2O) emission have attracted great concern for their contribution to global warming.The biological processes particularly microbial processes play a dominant role in soil respiration and N2O emission processes.Southeast China is a region with high nitrogen deposition.The effect of nitrogen deposition on carbon and nitrogen cycling varies enormously in different soils.The purpose of this study was to determine soil biochemical factors which hold key roles in soil respiration and N2O emission under simulated nitrogen deposition.Thirteen types of soil from different land use systems in Jiangsu province were collected and their biochemical characteristics were analyzed,then an indoor soil incubation experiment with ammonium nitrate (NH4NO3) input was carried out at constant soil temperature (25℃) and soil moisture (0.30 g·g-1,simulated upland).The results showed that,when nitrogen addition significantly promoted CO2 emission,the soils had the properties of low clay composition,low ratio of soil microbial carbon to nitrogen (MC/MN),high soil basic respiration,high soil available nitrogen value,and high abundances of bacterial and fungal.When nitrogen addition significantly promoted N2O emission,the soils had the properties of high basic respiration,low endogenous N2O emissions,low total nitrogen content as well as available nitrogen value,and low abundances of actinomycetes and fungi.Stepwise regression analysis suggested that soil respiration could be quantitatively determined by a linear combination of the abundance of soil bacteria and pH value.At the absence of the exogenous nitrogen,N2O emission was mainly dependent on the values of soil bacteria and ammonium nitrogen.When the exogenous nitrogen was added,N2O emission was only dependent on the value of soil bacteria.No significant correlation was found between endogenous N2O emission and soil basic respiration (P>0.05),but there was a significantly positive correlation between N2O emission and soil respiration (P<0.01) after exogenous nitrogen addition.Moreover,the CO2 emission per gram exogenous nitrogen was positively correlated with soil organic carbon,total nitrogen contents and the abundance of soil fungi (P<0.05),and negatively correlated with the ratio of MC/MN (P<0.05),while the N2O emission factor was significantly positively correlated with the abundance of soil bacteria (P<0.01).Stepwise regression analysis showed that the CO2 emission per gram nitrogen could be quantitatively determined by the ratio of MC/MN,and the N2O emission factor was mainly dependent on the abundance of soil bacteria.In conclusion,the ratio of MC/MN and soil bacterial value were the determinants of soil respiration and N2O emissions under simulated nitrogen deposition,respectively.

    • Research advances in effects of biochar addition on soil nitrous oxide emissions

      2022, 14(1):98-109. DOI: 10.13878/j.cnki.jnuist.2022.01.010

      Abstract (396) HTML (216) PDF 1.23 M (1669) Comment (0) Favorites

      Abstract:Nitrous oxide (N2O) is a long-lived greenhouse gas that can destroy stratospheric ozone.Agricultural soil is the largest contributor to anthropogenic N2O emissions.It is thus urgent to reduce N2O emissions from agricultural soil.Biochar is a carbon material produced by pyrolysis of biomass at low temperature and limited oxygen with rich pore structures.Biochar is one of the important means to reduce greenhouse N2O emissions,but there are few systematic reports on its effect and mechanism.We describe the effects of biochar on N2O emissions from soil.We then discuss the possible mechanisms of biochar on soil N2O emissions.From a biological point of view,the"liming effect"of biochar could increase soil pH and change soil microbial processes to promote the reduction of N2O to N2,and also act as an "electron shuttle" in this process.In addition,biochar could increase the population of denitrification bacteria containing nosZ gene to promote the reduction of N2O to N2.When soil N2O was mainly generated through nitrification,the addition of biochar could increase the abundance of ammonia-oxidizing bacteria harboring amoA gene in soil,which led to the increase of soil N2O emissions.From an abiotic point of view,the adsorption of N2O on the surface of biochar could reduce the release of N2O emission from soil,and then the surface C C may react with N2O to consume it.The effects of biochar amendments on N2O emissions depend on the characteristics of biochar (raw materials,pyrolysis conditions,C/N ratio,application rate,and aging degree),nitrogen application rate,and soil physico-chemical properties.Finally,we summarize and put forward further prospect on biochar in reducing N2O emissions from soil.This review will provide an important technical reference for mitigation of N2O emissions from agricultural soil as well as agricultural carbon neutrality in the future.

    • Carbon footprint dynamics and composition assessment of major crops production in Jiangsu province

      2022, 14(1):110-119. DOI: 10.13878/j.cnki.jnuist.2022.01.011

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      Abstract:Jiangsu is a major agricultural province and grain producing area.The comprehensive accounting of the temporal dynamics and composition of carbon footprint of major crops could provide decision-making basis for environmental management and green development of the agricultural sector in Jiangsu province.In this paper,Life Cycle Assessment (LCA) was used to calculate the carbon emission intensity of rice,wheat,maize,soybean and rapeseed production processes in Jiangsu province during 1990-2019,and the temporal dynamics,composition and influencing factors of carbon footprints of these crops were analyzed.The results showed that the carbon footprint per unit yield of major crops in Jiangsu province decreased but the carbon footprint per unit area increased in recent 30 years.The carbon footprint per unit yield for different crops showed as rapeseed (1.74 kg (CO2-eq)·kg-1)> rice (1.36 kg (CO2-eq)·kg-1)> wheat (0.99 kg (CO2-eq)·kg-1)> maize (0.81 kg (CO2-eq)·kg-1)> soybean (0.64 kg CO2-eq kg-1).For the composition of carbon footprint,CH4 emission (54.43%) and chemical fertilizer input (20.65%) were the two major sources for rice production,while chemical fertilizer input and soil N2O emission are the most important sources for wheat,maize,soybean and rapeseed production.Random forest analysis showed that the variation of seed,nitrogen fertilizer and agricultural machinery input were the main driving factors for the interannual change of carbon footprints for different crops.Therefore,it is necessary to take targeted emission reduction strategies for different crop production and adjust agricultural inputs and process management in order to promote the green and efficient development of agriculture.

    • Comparative study on nitrite-dependent anaerobic methane oxidation in different types of paddy field

      2022, 14(1):120-126. DOI: 10.13878/j.cnki.jnuist.2022.01.012

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      Abstract:Anaerobic methane (CH4) oxidation is an important process to reduce greenhouse gas emissions in paddy soil.The nitrite-dependent Denitrifying Anaerobic Methane Oxidation (n-DAMO) potential and its microbial mechanism in cultivated layer (0-10 cm) and deep layer (50-60 cm) of inland (Nanjing) and coastal (reclaimed Shanghai Chongming Island) paddy fields were studied.The results showed that n-DAMO rate of topsoil in Nanjing paddy field was 3.51 nmol 13CO2·g-1·d-1,which was significantly higher than that of topsoil in reclaimed paddy field (1.43 nmol 13CO2·g-1·d-1).The n-DAMO rates in the cultivated layer soil were significantly higher than those in the deep layer soil in the two types of paddy field.The copy numbers of 16S rRNA gene of functional microorganism M.oxyfera-like bacteria in Nanjing paddy field and reclaimed paddy field were 2.31×107-4.82×107 copies·g-1 and 0.89×107-2.12×107 copies·g-1,respectively,which was significantly positively correlated with nitrite-dependent anaerobic CH4 oxidation rate.Regression analysis showed that soil organic carbon,total nitrogen and inorganic nitrogen were important factors for n-DAMO rate differentiation in paddy fields.In conclusion,the n-DAMO potential of inland paddy soil is higher than that in reclaimed paddy field,which is mainly caused by the different levels of soil background carbon and nitrogen and the abundance of functional microorganisms.


2022, Volume 14, No. 1

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