Nitrous oxide(N_(2)O),as an important gas affecting climate warming,is attracting attention from allwalks of life.This reviewaddresses N_(2)O emissions status in the adipic acid industry,a significant industrial green...Nitrous oxide(N_(2)O),as an important gas affecting climate warming,is attracting attention from allwalks of life.This reviewaddresses N_(2)O emissions status in the adipic acid industry,a significant industrial greenhouse gas source.It elucidates the N_(2)O emission mechanism and influencing factors in adipic acid production.It extensively evaluates N_(2)O emission accounting methods,including Intergovernmental Panel on Climate Change(IPCC)Guidelines,World Resources Institute(WRI)Protocol,and others.While the IPCC emission factor method offers simplicity and comparability,it may lack precision for facilities with advanced emission reduction measures.To address this,a combined modeling and monitoring approach is advocated.It scrutinizes modeling methods(statistical techniques,Greenhouse Gas and Air Pollution Interactions and Synergies,and Life-cycle Assessment)and highlights their reliance on specific data and perspectives.It emphasizes the growing importance of on-site monitoring with mid-IR technology.Additionally,it underscores the potential of aircraft-based and satellite remote sensing for comprehensive N_(2)O emissions data.The reviewalso highlights recent advancements in emission mitigation,particularly in adipic acid synthesis techniques,showing substantial potential for N_(2)O reduction.Innovative paradigms and strategies for N_(2)O mitigation in the adipic acid industry are presented,with a focus on achieving nitrogen oxides(NO_(x))-free production.These approaches hold promise for emission reduction,given the high removal efficiency in plant end-of-treatment processes.Various accounting methods,monitoring techniques,and mitigation strategies were integrated and analyzed to provides a comprehensive overview of N_(2)O emissions in the adipic acid industry,with the aim of guiding future research and policy initiatives.展开更多
The objectives of this study which included two experiments were to investigate the effects of dietary inclusion of sorghum grain rich in condensed tannins(CT)(18.9 g kg^(–1)dry matter(DM))on nitrogen(N)metabolism an...The objectives of this study which included two experiments were to investigate the effects of dietary inclusion of sorghum grain rich in condensed tannins(CT)(18.9 g kg^(–1)dry matter(DM))on nitrogen(N)metabolism and urine nitrous oxide(N_(2)O)emissions of beef steers.In experiment 1,six Limousin×Luxi crossbreed steers with an initial liveweight of(245.0±18.7)kg were used as experimental animals.Three levels of sorghum grain,i.e.,0,167 and 338 g kg^(–1)DM were included in diets as experimental treatments.The animals and the treatments were randomly assigned to a replicated 3×3 Latin square design.In experiment 2,static incubation technique was used to determine the N_(2)O emissions of the urine samples collected in experiment 1.The results of experiment 1 showed that dietary inclusion of sorghum grain linearly increased the faecal N excretion(P=0.001),the total N excretion(P=0.010)and the faecal N to N intake ratio(P=0.021),but it did not affect the N retention and the N utilization efficiency(P>0.10).The plasma metabolomic data showed that dietary inclusion of sorghum grain increased the relative concentrations of phenolic acid(N1,N5,N10-tris-trans-p-coumaroylspermine and prenyl cis-caffeate)and carnitine(3-hydroxyisovalerylcarnitine and linoelaidyl carnitine).The results also showed that dietary inclusion of sorghum grain linearly increased the urinary urea excretion(P=0.010)and decreased the urinary excretion of purine derivatives(P=0.041)as well as the estimated rumen microbial N supply(P=0.012)based on urinary purine derivatives.The results of experiment 2 showed that including sorghum grain in the diet linearly increased the average concentrations of NH_(4)^(+)-N(P=0.012),NO_(2)^(–)-N(P=0.009),NO_(3)^(-)-N(P=0.001)and the total inorganic N(P<0.001)in the soil enriched with urine samples.The urine sample N_(2)O-N flux(P=0.001),the estimated steer urine N_(2)O-N flux(P=0.021)and the N_(2)O-N to urinary N ratio(P=0.038)linearly increased with increasing inclusion of sorghum grain in the diet.In conclusion,dietary inclusion of sorghum grain containing high CT at 167 and 338 g kg^(–1)DM did not affect the N utilization efficiency of steers but increased the urine N_(2)O-N emissions by 5.7 and 31.4%,respectively.For reducing the N_(2)O emissions to the environment,high levels of sorghum grain should not be included in the diet of steers.展开更多
The valorization of nitrous oxide(N_(2)O)as an oxygen atom donor presents an attractive opportunity for green chemistry applications,leveraging both its industrial abundance and thermodynamically favorable oxidation p...The valorization of nitrous oxide(N_(2)O)as an oxygen atom donor presents an attractive opportunity for green chemistry applications,leveraging both its industrial abundance and thermodynamically favorable oxidation potential.However,practical implementation has been constrained by the inherent kinetic inertness and poor coordinating ability of N_(2)O.While prior studies achieved N_(2)O-mediated conversion of aryl halides to phenols,such transformations necessitated stoichiometric chemical reductants and elevated pressure(2 atm),posing challenges in operational safety and process scalability.This study focuses on an electrochemical strategy that enables efficient oxygen atom transfer under ambient pressure through controlled current application.This methodology facilitates the selective transformation of aryl iodides to phenols without external reducing agents,establishing an environmentally benign synthetic pathway.By replacing traditional chemical reductants with electrons as the sole reducing equivalent,our approach addresses critical sustainability challenges in aromatic oxygenation chemistry while maintaining operational simplicity under mild conditions.展开更多
The global ocean is a major source of the climate-relevant atmospheric trace gas nitrous oxide(N_(2)O).However,an accurate assessment of the global oceanic emissions of N_(2)O is hampered by missing data on dissolved ...The global ocean is a major source of the climate-relevant atmospheric trace gas nitrous oxide(N_(2)O).However,an accurate assessment of the global oceanic emissions of N_(2)O is hampered by missing data on dissolved N_(2)O from large regions such as the Southern Ocean.To address this deficit,N_(2)O was measured in the Prydz Bay in February 2015 during the 31st Chinese National Antarctic Research Expedition.N_(2)O concentrations(saturation)in the surface layer were generally low(undersaturation with respect to atmospheric equilibrium)and ranged from 13.3 nmol/L to 16.1 nmol/L(83%–102%)at the time of sampling.A comparison of our observations with archived data revealed that no discernible trend in N_(2)O concentrations in the surface waters of Prydz Bay could be detected for the period between 2006 and 2015.Temperature and salinity changes driven by meltwater input were the predominant controls on N_(2)O concentrations in surface waters.At depth,the distribution of N_(2)O concentrations was dominated by production via nitrification in offshore deep waters and vertical convection in the shelf waters,where concentrations were lower and gradients were less steep.Our results suggest a rather unusual pattern of N_(2)O distribution in the Prydz Bay(low N_(2)O in shelf waters compared with the open ocean),providing important insights into the coastal dynamics of N_(2)O in high-latitude polar regions.展开更多
Eutrophic shallow lakes are generally considered as a contributor to the emission of nitrous oxide(N_(2)O),while regional and global estimates have remained imprecise.This due to a lack of data and insufficient unders...Eutrophic shallow lakes are generally considered as a contributor to the emission of nitrous oxide(N_(2)O),while regional and global estimates have remained imprecise.This due to a lack of data and insufficient understanding of the multiple contributing factors.This study characterized the spatiotemporal variability in N_(2)O concentrations and N_(2)O diffusive fluxes and the contributing factors in LakeWuliangsuhai,a typical shallow eutrophic and seasonally frozen lake in Inner Mongolia with cold and arid climate.Dissolved N_(2)O concentrations of the lake exhibited a range of 4.5 to 101.2 nmol/L,displaying significant spatiotemporal variations.The lowest and highest concentrations were measured in summer and winter,respectively.The spatial distribution of N_(2)Ofluxwas consistent with that of N_(2)O concentrations.Additionally,the hotspots of N_(2)O emissions were detected within close to the main inflow of lake.The wide spatial and temporal variation in N_(2)O emissions indicate the complexity and its relative importance of factors influencing emissions.N_(2)O emissions in different lake zones and seasons were regulated by diverse factors.Factors influencing the spatial and temporal distribution of N_(2)O concentrations and fluxes were identified as WT,WD,DO,Chl-a,SD and COD.Interestingly,the same factor demonstrated opposing effects on N_(2)O emission in various seasons or zones.This research improves our understanding of N_(2)O emissions in shallow eutrophic lakes in cold and arid areas.展开更多
Aquaculture,as the fastest-growing food production sector in the world,is becoming an increasingly nonnegligible source of greenhouse gas emissions.Despite this,there has been limited research on nitrous oxide(N_(2)O)...Aquaculture,as the fastest-growing food production sector in the world,is becoming an increasingly nonnegligible source of greenhouse gas emissions.Despite this,there has been limited research on nitrous oxide(N_(2)O)emission from marine aquaculture in China,where more marine aquaculture occurs than anywhere else,globally.We estimated N_(2)O emissions(E)from marine mariculture of 10 fish and 6 crustacean species in China from 2003 to 2022 using production data from the China Fishery Statistical Yearbook(2004–2023),and data for feed conversion rates and types from the literature.From 2003,marine aquaculture production,the annual N_(2)O emissions(E_(A)),and the annual N_(2)O emissions per unit of aquaculture area(EI_(A))trend upward.The E_(A)of fish culture was lower than that of crustaceans,but the EI_(A)of fish culture was generally higher.Sea bass(0.308 Tg/a,in terms of N)and white shrimp(0.945 Tg/a,in terms of N)had the highest average E_(A)among fish and crustacean cultures,respectively.The highest average E_(A)from fish and crustacean were both Guangdong Province(fish:0.248 Tg,crustacean:0.547 Tg),and the highest sea area were both the South China Sea(fish:0.316 Tg,crustacean:1.082 Tg);the highest average EI_(A)for fish and crustacean were Tianjin City[35.40 t/(hm^(2)·a)]and Guangxi Zhuang Autonomous Region[19.83 t/(hm^(2)·a)],respectively,and the highest sea areas were both the South China Sea(fish:0.316 Tg,crustacean:1.082 Tg).These analyses provide baseline data for a greenhouse gas emissions inventory for China,based on an interpretation of them,we provide recommendations for reducing N_(2)O emissions in marine fish and crustacean culture.展开更多
This paper monitors the differences of early rice yield and the emissions of methane and nitrous oxide in the paddy field, based on the different cultivation technologies（high-yield scattered-planting mode, transplan...This paper monitors the differences of early rice yield and the emissions of methane and nitrous oxide in the paddy field, based on the different cultivation technologies（high-yield scattered-planting mode, transplanting mode, farmer-planting mode）. Results suggested that the rice yield by high-yield scattered-planting mode and transplanting mode was significantly higher than farmer-planting mode, and the increase reached 16.4% and 17.7%. The difference of high-yield scattered-planting mode and transplanting mode was insignificant. The potential contributions of the methane amount by these three patterns to the global contribution were all above90%. The emission of methane during the growth period by the high-yield scatteredplanting mode was dramatically lower than that by transplanting mode and farmerplanting mode, while the differences between the high-yield transplanting mode and the farmer mode were insignificant. The changes of global temperature increase and the emission of methane were the same. The greenhouse gas intensity of high-yield scattered-planting mode was the lowest, and the farmer-planting mode was the highest. Therefore, the scattered-planting with reasonable fertilizing method is the most essential way to realize high yield of rice and the reducing the greenhouse gas emission as well.展开更多
Nitrous oxide （N 2 O） emissions from a maize field in the North China Plain （Wangdu County,Hebei Province,China） were investigated using static chambers during two consecutive maize growing seasons in the 2008 and...Nitrous oxide （N 2 O） emissions from a maize field in the North China Plain （Wangdu County,Hebei Province,China） were investigated using static chambers during two consecutive maize growing seasons in the 2008 and 2009.The N 2 O pulse emissions occurred with duration of about 10 days after basal and additional fertilizer applications in the both years.The average N 2 O fluxes from the CK （control plot,without crop,fertilization and irrigation）,NP （chemical N fertilizer）,SN （wheat straw returning plus chemical N fertilizer）,OM- 1/2N （chicken manure plus half chemical N fertilizer） and OMN （chicken manure plus chemical N fertilizer） plots in 2008 were 8.51,72.1,76.6,101,107 ng N/（m 2 ·sec）,respectively,and in 2009 were 33.7,30.0 and 35.0 ng N/（m 2 ·sec） from CK,NP and SN plots,respectively.The emission factors of the applied fertilizer as N 2 O-N （EFs） were 3.8% （2008） and 1.1% （2009） for the NP plot,3.2% （2008） and 1.2% （2009） for the SN plot,and 2.8% and 2.2% in 2008 for the OM-1/2N and OMN plots,respectively.Hydromorphic properties of the investigated soil （with gley） are in favor of denitrification.The large differences of the soil temperature and water-filled pore space （WFPS） between the two maize seasons were suspected to be responsible for the significant yearly variations.Compared with the treatments of NP and SN,chicken manure coupled with compound fertilizer application significantly reduced fertilizer loss rate as N 2 O-N.展开更多
Many studies have focused on various agricultural management measures to reduce agricultural nitrous oxide （N2O） emission. However, few studies have investigated soil N2O emissions in intercropping systems in the No...Many studies have focused on various agricultural management measures to reduce agricultural nitrous oxide （N2O） emission. However, few studies have investigated soil N2O emissions in intercropping systems in the North China Plain. Thus, we conducted a ifeld experiment to compare N2O emissions under monoculture and maize-legume intercropping systems. In 2010, ifve treatments, including monocultured maize （M）, maize-peanut （MP）, maize-alfalfa （MA）, maize-soybean （MS）, and maize-sweet clover （MSC） intercropping were designed to investigate this issue using the static chamber technique. In 2011, M, MP, and MS remained, and monocultured peanuts （P） and soybean （S） were added to the trial. The results showed that total production of N2O from different treatments ranged from （0.87＆#177;0.12） to （1.17＆#177;0.11） kg ha-1 in 2010, while those ranged from （3.35＆#177;0.30） to （9.10＆#177;2.09） kg ha-1 in 2011. MA and MSC had no signiifcant effect on soil N2O production compared to that of M （P＆lt;0.05）. Cumulative N2O emissions from MP in 2010 were signiifcantly lower than those from M, but the result was the opposite in 2011 （P＆lt;0.05）. MS signiifcantly reduced soil N2O emissions by 25.55 and 48.84%in 2010 and 2011, respectively （P＆lt;0.05）. Soil N2O emissions were signiifcantly correlated with soil water content, soil temperature, nitriifcation potential, soil NH4＋, and soil NO3-content （R2=0.160-0.764, P＆lt;0.01）. A stepwise linear regression analysis indicated that soil N2O release was mainly controlled by the interaction between soil moisture and soil NO3-content （R2=0.828, P＆lt;0.001）. These results indicate that MS had a coincident effect on soil N2O lfux and signiifcantly reduced soil N2O production compared to that of M over two growing seasons.展开更多
A laboratory incubation experiment was conducted to investigate nitrous oxide(N 2O) emission and reduction in a paddy soil(Stagnic Anthrosol) response to the pretreatment of water regime. The paddy soil was maintaine...A laboratory incubation experiment was conducted to investigate nitrous oxide(N 2O) emission and reduction in a paddy soil(Stagnic Anthrosol) response to the pretreatment of water regime. The paddy soil was maintained under either air dried(sample D) or submerged(sample F) conditions for 110 d before the soil was adjusted into soil moisture of 20%, 40%, 60%, 80% and 100% water holding capacity(WHC) respectively, and then incubated with or without 10%(v/v) acetylene for 138 h at 25℃. At lower soil water content (≤60% WHC), N 2O emission from the sample F was 2 29 times higher than that from the sample D( P <0 01). While, N 2O emission from the sample F was only 29 and 14 percent of that from the sample D at the soil moisture of 80% and 100% WHC, respectively( P <0 01). The maximal N 2O emissions observed at soil moisture of 80% WHC were about 24 and 186 times higher than the minima obtained at the soil moisture of 20% WHC for the sample F and D, respectively. But at the soil moisture of 80% and 100% WHC, N 2O emission from the sample F with acetylene(F+ACE) was comparable to that of the sample D with acetylene (D+ACE). The results showed that the F sample produced N 2O ability in denitrification was similar to the sample D, however, the sample F was in the better reduction of N 2O to N 2 than the sample D even after the soil moisture was adjusted into the same level of 80% or 100% WHC. Therefore, the pretreatment of water regime influenced the strength and product composition of denitrification and N 2O emission from the paddy soil.展开更多
Nitrous oxide （N2O） emission during denitrification is receiving intensive attention due to its high potential to cause greenhouse effects. In this study, denitrifiers were acclimated in sequencing batch reactors wi...Nitrous oxide （N2O） emission during denitrification is receiving intensive attention due to its high potential to cause greenhouse effects. In this study, denitrifiers were acclimated in sequencing batch reactors with methanol or acetate as the electron donor and nitrate as the electron acceptor. The effects of ammonium on NzO emission were examined in batch experiments with various electron donors. With the addition of ammonium, N2O emission increased under all the examined conditions compared to experiments without ammonium addition. With different electron donors, the highest ratio of N2O emission to the removed oxidized nitrogen was 0.70% for methanol, 5.34% for acetate, and 34.79% for polyhydroxybutyrate.展开更多
Water regime and nitrogen（N） fertilizer are two important factors impacting greenhouse gases（GHG） emission from paddy field, whereas their effects have not been well studied in cold region. In this study, we condu...Water regime and nitrogen（N） fertilizer are two important factors impacting greenhouse gases（GHG） emission from paddy field, whereas their effects have not been well studied in cold region. In this study, we conducted a two-year field experiment to study the impacts of water regime and N fertilizer on rice yields and GHG emissions in Harbin, China, a cold region located in high latitudes. Our results showed that intermittent irrigation significantly decreased methane（CH4） emission compared with continuous flooding, however,the decrement was far lower than the global average level. The N2O emissions were very small when flooded but peaked at the beginning of the disappearance of floodwater. The N fertilizer treatments increased CH4 emissions at low level（75 kg N/ha）. But both CH4 and N2O emissions were uninfluenced at the levels of 150 kg N/ha and 225 kg N/ha. Rice yields increased under intermittent irrigation and were highest at the level of 150 kg N/ha. From our results, we recommended that the intermittent irrigation and 150 kg N/ha as the ideal water regime-nitrogen fertilizer incorporation for this area to achieve low GHG emissions without impacting rice yields.展开更多
Rice-duck （RD） and rice-fish （RF） ecological systems are major complex planting and breeding models of rice paddy fields in southern China. Studying the methane （CH4） and nitrous oxide （N2O） emissions and thei...Rice-duck （RD） and rice-fish （RF） ecological systems are major complex planting and breeding models of rice paddy fields in southern China. Studying the methane （CH4） and nitrous oxide （N2O） emissions and their economic value from these two ecosystems can provide theoretical and practical basis for further development and utilization of these classical agricultural techniques. CH4 and N2O emissions from RD and RF ecological systems were measured in situ by using static chambers technique. Using global warming potentials （GWPs）, we assessed the greenhouse effect of CH4 and N2O and their economic value. Results showed that the peaks of CH4 emission fluxes from RD and RF appeared at full tillering stage and at heading stage, and the average emission fluxes were significantly （P〈 0.05） lower than that from CK. N2O fluxes remained low when the field is flooded and high after draining the water. Compared with CK, the total amount of N2O emissions was significantly （P〈0.05） higher and slightly lower than those from RD and RF, respectively. In 2006 and 2007, the total greenhouse effect of CH4 and N20 from RD and RF were 4 728.3 and 4 611 kg CO2 ha^-1, 4 545 and 4 754.3 kg CO2 ha^-1, respectively. The costs of greenhouse effect were 970.89 and 946.81 RMB yuan ha^-1, and 933.25 and 976.23 RMB yuan ha^-1, respectively, which were significant lower than those from CK （5 997.6 and 5 391.5 RMB yuan ha^-1）. Except for the environment cost of CH4 and N2O, the economic benefits from RD and RF were 2 210.64 and 4 881.92 RMB yuan ha^-1; 3 798.37 and 5 310.64 RMB yuan ha^-1, respectively, higher than those from CK. Therefore, RD and RF complex ecological planting and breeding models can effectively decrease and control CH4 and N2O emissions, and they are two of the effective strategies to reduce greenhouse gases from rice paddy fields and contribute in alleviating global warming. Thus, their adoption is important to the environment together with their economy benefits.展开更多
Aquatic ecosystems have been identified as a globally significant source of nitrous oxide(N_2O) due to continuous active nitrogen involvement, but the processes and influencing factors that control N_2O production are...Aquatic ecosystems have been identified as a globally significant source of nitrous oxide(N_2O) due to continuous active nitrogen involvement, but the processes and influencing factors that control N_2O production are still poorly understood, especially in reservoirs. For that, monthly N_2O variations were monitored in Dongfeng reservoir(DFR)with a mesotrophic condition. The dissolved N_2O concentration in DFR displayed a distinct spatial–temporal pattern but lower than that in the eutrophic reservoirs. During the whole sampling year, N_2O saturation ranging from 144% to 640%, indicating that reservoir acted as source of atmospheric N_2O. N_2O production is induced by the introduction of nitrogen(NO_3^-, NH_4^+) in mesotrophic reservoirs, and is also affected by oxygen level and water temperature. Nitrification was the predominate process for N_2O production in DFR due to well-oxygenated longitudinal water layers.Mean values of estimated N_2O flux from the air–water interface averaged 0.19 μmol m^(-2)h^(-1) with a range of 0.01–0.61 μmol m^(-2)h^(-1). DFR exhibited less N_2O emission flux than that reported in a nearby eutrophic reservoir, but still acted as a moderate N_2O source compared with other reservoirs and lakes worldwide. Annual emissions from the water–air interface of DFR were estimated to be 0.32×10~5 mol N–N_2O, while N_2O degassing from releasing water behind the dam during power generation was nearly five times greater. Hence, N_2O degassing behind the dam should be taken into account for estimation of N_2O emissions from artificial reservoirs, an omission that historically has probably resulted in underestimates. IPCC methodology should consider more specifically N_2O emission estimation in aquatic ecosystems, especially in reservoirs, the default EF5 model will lead to an overestimation.展开更多
Increased precipitation during the vegetation periods was observed in and further predicted for Inner Mongolia. The changes in the associated soil moisture may affect the biosphere-atmosphere exchange of greenhouse ga...Increased precipitation during the vegetation periods was observed in and further predicted for Inner Mongolia. The changes in the associated soil moisture may affect the biosphere-atmosphere exchange of greenhouse gases. Therefore, we set up an irrigation experiment with one watered （W） and one unwatered plot （UW） at a winter-grazed Leymus chinensis-steppe site in the Xilin River catchment, Inner Mongolia. UW only received the natural precipitation of 2005 （129 mm）, whereas W was additionally watered after the precipitation data of 1998 （in total 427 mm）. In the 3-hour resolution, we determined nitrous oxide （N20）, methane （CH4） and carbon dioxide （CO2） fluxes at both plots between May and September 2005, using a fully automated, chamber-based measuring system. N20 fluxes in the steppe were very low, with mean emissions （±s.e.） of 0.9-4-0.5 and 0.7-4-0.5 μg N m^-2 h^-1 at W and UW, respectively. The steppe soil always served as a CH4 sink, with mean fluxes of -24.1-4-3.9 and -31.1-4- 5.3 μg C m^-2 h^-1 at W and UW. Nighttime mean CO2 emissions were 82.6±8.7 and 26.3±1.7 mg C m^-2 h^-1 at W and UW, respectively, coinciding with an almost doubled aboveground plant biomass at W. Our results indicate that the ecosystem CO2 respiration responded sensitively to increased water input during the vegetation period, whereas the effects on CH4 and N2O fluxes were weak, most likely due to the high evapotranspiration and the lack of substrate for N2O producing processes. Based on our results, we hypothesize that with the gradual increase of summertime precipitation in Inner Mongolia, ecosystem CO2 respiration will be enhanced and CH4 uptake by the steppe soils will be lightly inhibited.展开更多
Most aquatic ecosystems contribute elevated N2 O to atmosphere due to increasing anthropogenic nitrogen loading. To further understand the spatial heterogeneity along an aquatic continuum from the upriver to wetland t...Most aquatic ecosystems contribute elevated N2 O to atmosphere due to increasing anthropogenic nitrogen loading. To further understand the spatial heterogeneity along an aquatic continuum from the upriver to wetland to lake to downriver, the study was conducted on spatial variations in N2 O emission along Poyang Lake aquatic continuum during the flood season from 15 July 2013 to 10 August 2013. The results showed the N2 O concentrations, the ratio of N2O/dinitrogen（N2） gases production, N2 O emission and denitrification rates ranged from 0.10 to 1.11 μg N/L,- 0.007% to 0.051%,- 9.73 to 127 μg N/m2/hr and 1.33 × 104to31.9 × 104μg N2/m2/hr, respectively, across the continuum. The average N2 O concentrations,the ratio of N2O/N2 and N2O emission was significantly lower in wetlands as compared to the rivers and lake（p 〈 0.01）. The significantly high denitrification rate and low N2 O emission together highlighted that most N2 O can be converted into N2 via near complete denitrification in the Poyang Lake wetlands. Our study suggests that the wetlands might impact N2 O budget in an integrated aquatic ecosystems. Moreover, N2 O emission from different aquatic ecosystem should be considered separately when quantifying the regional budget in aquatic ecosystem.展开更多
The absorption spectrum of the C1Ⅱ state of N2O molecule in the wavelength range of 142.5-147.5 nm has been measured under the jet-cooled condition, and the clear spectral features are displayed. A vibrational progre...The absorption spectrum of the C1Ⅱ state of N2O molecule in the wavelength range of 142.5-147.5 nm has been measured under the jet-cooled condition, and the clear spectral features are displayed. A vibrational progression is observed with a frequency interval of about 500 cm-1. With the aid of potential energy surfaces （PES） of the low-lying electronic states of N2O, the vibrational progression is assigned as the bending mode of the repulsive C1Ⅱ state. From the Fourier transformation analysis, the recurrence period of the periodic orbit near the transition state region is derived to be 65 fs. Through the least-square Lorentzian fitting, the lifetimes of the resonance levels are estimated from their profile widths to be about 20 fs, which is shorter than the recurrence period. Therefore, a new explanation is suggested for the observed diffuse spectral structure, based on the behavior of dissociating N20 on PES of the C1Ⅱ state in the present excitation energy range.展开更多
The rate of nitrous oxide emission from a laboratory sequence batch reactor （SBR） wastewater treatment system using synthetic wastewater was measured under controlled conditions. The SBR was operated in the mode of ...The rate of nitrous oxide emission from a laboratory sequence batch reactor （SBR） wastewater treatment system using synthetic wastewater was measured under controlled conditions. The SBR was operated in the mode of 4 h for aeration, 3.5 h for stirring without aeration, 0.5 h for settling and drainage, and 4 h of idle. The sludge was acclimated by running the system to achieve a stable running state as chemical oxygen demand, NO2^-, NO3^-, NH4^＋, pH, and N2O. indicated by rhythmic changes of total N, dissolved oxygen, Under the present experimental conditions measured nitrous oxide emitted from the off-gas in the aerobic and anaerobic phases, respectively, accounted for 8.6%-16.1% and 0-0.05% of N removed, indicating that the aerobic phase was the main source of N2O emission from the system. N2O dissolved in discharged water was considerable in term of concentration. Thus, measures to be developed for the purpose of reducing N2O emission from the system should be effective in the aeration phase.展开更多
Paddy field is a primary agricultural landscape in the south of China and is often regarded as one of main sources emitting nitrous oxide to atmosphere. The nitrous oxide emissions under a variety of paddy field pract...Paddy field is a primary agricultural landscape in the south of China and is often regarded as one of main sources emitting nitrous oxide to atmosphere. The nitrous oxide emissions under a variety of paddy field practices, such as fertilization, flooding/draining management were investigated to study on agricultural activities on paddy field affect the dynamic process of the emission. Under no addition of fertilizers the average emission flux of nitrous oxide was 8 55 μg/(m 2·h) during the rice( Oryza Sativa L.) growth season. The results indicated that most of nitrous oxide emissions occurred during the crack forming and expansion period when paddy field was being drained. The diurnal emissions peak of nitrous oxide appeared at 20∶30 at night in cracked rice fields. The statistical analysis suggested that the correlation of nitrous oxide emissions flux( Y ) with soil water content( X 1), soil temperature( X 2), and E h( X 3), could be described in a regression equation: Y =-1498 95+2895 48 X 1+50 63 X 2-96 99 X 1· X 2+0 006 X 2· X 3 There were the different power equations to simulate the correlations between the everyday dynamic N 2O emissions and the mean surface area of cracks, mean volume and depth of cracks respectively during paddy soil drying by soil columns incubation experiments. Taken all together, the current study presented a dynamic analysis of nitrous oxide emission of paddy field under various conditions, therefore provided a basis for the management to balance between environmental effect and paddy field activities.展开更多
The concentrations of nitrous oxide varies between 57 and 329 nmol/dm3, saturation is 674%～4 134% in the Zhujiang River Estuary. This suggests that the area is an emissive source of nitrous oxide. The acetylene inhib...The concentrations of nitrous oxide varies between 57 and 329 nmol/dm3, saturation is 674%～4 134% in the Zhujiang River Estuary. This suggests that the area is an emissive source of nitrous oxide. The acetylene inhibition technique is employed to evaluate the rates of nitrification, denitrification and nitrate reduction by bacterial activities in the sediments at three sites. The average of nitrification, denitrification and nitrate reduction rates ranges from 0.32 to 2.43, 0.03 to 0.84 and 4.17 to 13.06 mmol/(m2·h), respectively. The ver- tical profiles of the sediments show that the nitrification and denitrification processes mainly take place in the depth from 0 to 4 cm and depend on regional conditions. The rates of nitrification, denitrification and nitrate reduction are dominated by Eh, nitrate and ammoni- um concentrations in sediments and DO in overlay water. There is a coupling between nitrification and denitrification.展开更多
基金supported by the National Key R&D Program of China(No.2023YFC3707201)the National Natural Science Foundation of China(No.52320105003)+1 种基金the Informatization Plan of Chinese Academy of Sciences(No.CAS-WX2023PY-0103)the Fundamental Research Funds for the Central Universities(No.E3ET1803).
文摘Nitrous oxide(N_(2)O),as an important gas affecting climate warming,is attracting attention from allwalks of life.This reviewaddresses N_(2)O emissions status in the adipic acid industry,a significant industrial greenhouse gas source.It elucidates the N_(2)O emission mechanism and influencing factors in adipic acid production.It extensively evaluates N_(2)O emission accounting methods,including Intergovernmental Panel on Climate Change(IPCC)Guidelines,World Resources Institute(WRI)Protocol,and others.While the IPCC emission factor method offers simplicity and comparability,it may lack precision for facilities with advanced emission reduction measures.To address this,a combined modeling and monitoring approach is advocated.It scrutinizes modeling methods(statistical techniques,Greenhouse Gas and Air Pollution Interactions and Synergies,and Life-cycle Assessment)and highlights their reliance on specific data and perspectives.It emphasizes the growing importance of on-site monitoring with mid-IR technology.Additionally,it underscores the potential of aircraft-based and satellite remote sensing for comprehensive N_(2)O emissions data.The reviewalso highlights recent advancements in emission mitigation,particularly in adipic acid synthesis techniques,showing substantial potential for N_(2)O reduction.Innovative paradigms and strategies for N_(2)O mitigation in the adipic acid industry are presented,with a focus on achieving nitrogen oxides(NO_(x))-free production.These approaches hold promise for emission reduction,given the high removal efficiency in plant end-of-treatment processes.Various accounting methods,monitoring techniques,and mitigation strategies were integrated and analyzed to provides a comprehensive overview of N_(2)O emissions in the adipic acid industry,with the aim of guiding future research and policy initiatives.
基金supported by the National Natural Science Foundation of China(31572428)。
文摘The objectives of this study which included two experiments were to investigate the effects of dietary inclusion of sorghum grain rich in condensed tannins(CT)(18.9 g kg^(–1)dry matter(DM))on nitrogen(N)metabolism and urine nitrous oxide(N_(2)O)emissions of beef steers.In experiment 1,six Limousin×Luxi crossbreed steers with an initial liveweight of(245.0±18.7)kg were used as experimental animals.Three levels of sorghum grain,i.e.,0,167 and 338 g kg^(–1)DM were included in diets as experimental treatments.The animals and the treatments were randomly assigned to a replicated 3×3 Latin square design.In experiment 2,static incubation technique was used to determine the N_(2)O emissions of the urine samples collected in experiment 1.The results of experiment 1 showed that dietary inclusion of sorghum grain linearly increased the faecal N excretion(P=0.001),the total N excretion(P=0.010)and the faecal N to N intake ratio(P=0.021),but it did not affect the N retention and the N utilization efficiency(P>0.10).The plasma metabolomic data showed that dietary inclusion of sorghum grain increased the relative concentrations of phenolic acid(N1,N5,N10-tris-trans-p-coumaroylspermine and prenyl cis-caffeate)and carnitine(3-hydroxyisovalerylcarnitine and linoelaidyl carnitine).The results also showed that dietary inclusion of sorghum grain linearly increased the urinary urea excretion(P=0.010)and decreased the urinary excretion of purine derivatives(P=0.041)as well as the estimated rumen microbial N supply(P=0.012)based on urinary purine derivatives.The results of experiment 2 showed that including sorghum grain in the diet linearly increased the average concentrations of NH_(4)^(+)-N(P=0.012),NO_(2)^(–)-N(P=0.009),NO_(3)^(-)-N(P=0.001)and the total inorganic N(P<0.001)in the soil enriched with urine samples.The urine sample N_(2)O-N flux(P=0.001),the estimated steer urine N_(2)O-N flux(P=0.021)and the N_(2)O-N to urinary N ratio(P=0.038)linearly increased with increasing inclusion of sorghum grain in the diet.In conclusion,dietary inclusion of sorghum grain containing high CT at 167 and 338 g kg^(–1)DM did not affect the N utilization efficiency of steers but increased the urine N_(2)O-N emissions by 5.7 and 31.4%,respectively.For reducing the N_(2)O emissions to the environment,high levels of sorghum grain should not be included in the diet of steers.
基金National Natural Science Foundation of China(Project No.:52320105003,Project No.:52303019)the CAS-ANSO Co-funding Research Project(Project No.:CAS-ANSO-CF-2024)+2 种基金the National Key R&D Program of China(Project No.:2023YFC3707201)the Fundamental Research Funds for the Central Universities(Project No.:E3ET1803)China Postdoctoral Science Foundation(Project No:2024T170904)。
文摘The valorization of nitrous oxide(N_(2)O)as an oxygen atom donor presents an attractive opportunity for green chemistry applications,leveraging both its industrial abundance and thermodynamically favorable oxidation potential.However,practical implementation has been constrained by the inherent kinetic inertness and poor coordinating ability of N_(2)O.While prior studies achieved N_(2)O-mediated conversion of aryl halides to phenols,such transformations necessitated stoichiometric chemical reductants and elevated pressure(2 atm),posing challenges in operational safety and process scalability.This study focuses on an electrochemical strategy that enables efficient oxygen atom transfer under ambient pressure through controlled current application.This methodology facilitates the selective transformation of aryl iodides to phenols without external reducing agents,establishing an environmentally benign synthetic pathway.By replacing traditional chemical reductants with electrons as the sole reducing equivalent,our approach addresses critical sustainability challenges in aromatic oxygenation chemistry while maintaining operational simplicity under mild conditions.
基金The National Natural Science Foundation of China under contract No.41906193the Scientific Research Foundation of Third Institute of Oceanography,Ministry of Natural Resources,under contract No.2019033+2 种基金the Natural Science Foundation of Fujian Province under contract No.2019J05147the Federal Ministry of Education and Research of Germany under contract No.FKZ 03F03F0783Athe National Polar Special Program under contract Nos IRASCC 01-01-02 and IRASCC 02-02.
文摘The global ocean is a major source of the climate-relevant atmospheric trace gas nitrous oxide(N_(2)O).However,an accurate assessment of the global oceanic emissions of N_(2)O is hampered by missing data on dissolved N_(2)O from large regions such as the Southern Ocean.To address this deficit,N_(2)O was measured in the Prydz Bay in February 2015 during the 31st Chinese National Antarctic Research Expedition.N_(2)O concentrations(saturation)in the surface layer were generally low(undersaturation with respect to atmospheric equilibrium)and ranged from 13.3 nmol/L to 16.1 nmol/L(83%–102%)at the time of sampling.A comparison of our observations with archived data revealed that no discernible trend in N_(2)O concentrations in the surface waters of Prydz Bay could be detected for the period between 2006 and 2015.Temperature and salinity changes driven by meltwater input were the predominant controls on N_(2)O concentrations in surface waters.At depth,the distribution of N_(2)O concentrations was dominated by production via nitrification in offshore deep waters and vertical convection in the shelf waters,where concentrations were lower and gradients were less steep.Our results suggest a rather unusual pattern of N_(2)O distribution in the Prydz Bay(low N_(2)O in shelf waters compared with the open ocean),providing important insights into the coastal dynamics of N_(2)O in high-latitude polar regions.
基金supported by the National Natural Science Foundation of China(Nos.52260028,52060022,52260029,and 52160021)the National Key Research and Development Program of China(Nos.2017YFE0114800 and 2019YFC0409200)+1 种基金Inner Mongolia Autonomous Region Science and Technology Plan(No.2021GG0089)personal grant to Guohua Li by China Scholarship Council(CSC).
文摘Eutrophic shallow lakes are generally considered as a contributor to the emission of nitrous oxide(N_(2)O),while regional and global estimates have remained imprecise.This due to a lack of data and insufficient understanding of the multiple contributing factors.This study characterized the spatiotemporal variability in N_(2)O concentrations and N_(2)O diffusive fluxes and the contributing factors in LakeWuliangsuhai,a typical shallow eutrophic and seasonally frozen lake in Inner Mongolia with cold and arid climate.Dissolved N_(2)O concentrations of the lake exhibited a range of 4.5 to 101.2 nmol/L,displaying significant spatiotemporal variations.The lowest and highest concentrations were measured in summer and winter,respectively.The spatial distribution of N_(2)Ofluxwas consistent with that of N_(2)O concentrations.Additionally,the hotspots of N_(2)O emissions were detected within close to the main inflow of lake.The wide spatial and temporal variation in N_(2)O emissions indicate the complexity and its relative importance of factors influencing emissions.N_(2)O emissions in different lake zones and seasons were regulated by diverse factors.Factors influencing the spatial and temporal distribution of N_(2)O concentrations and fluxes were identified as WT,WD,DO,Chl-a,SD and COD.Interestingly,the same factor demonstrated opposing effects on N_(2)O emission in various seasons or zones.This research improves our understanding of N_(2)O emissions in shallow eutrophic lakes in cold and arid areas.
基金The Basic Research Funding Projects of Liaoning Provincial Education Department unde contract No.JYTMS20230498the State Environmental Protection Key Laboratory of Coastal Ecosystem Open Project Fund of China unde contract No.202305+1 种基金the Research Foundation for Talented Scholars of Dalian Ocean University unde contract No.HDYJ202121the Key Laboratory of Environment Controlled Aquaculture(Dalian Ocean University)Ministry of Education Open Project Fund of China unde contract No.2021-MOEKLECA-KF-01。
文摘Aquaculture,as the fastest-growing food production sector in the world,is becoming an increasingly nonnegligible source of greenhouse gas emissions.Despite this,there has been limited research on nitrous oxide(N_(2)O)emission from marine aquaculture in China,where more marine aquaculture occurs than anywhere else,globally.We estimated N_(2)O emissions(E)from marine mariculture of 10 fish and 6 crustacean species in China from 2003 to 2022 using production data from the China Fishery Statistical Yearbook(2004–2023),and data for feed conversion rates and types from the literature.From 2003,marine aquaculture production,the annual N_(2)O emissions(E_(A)),and the annual N_(2)O emissions per unit of aquaculture area(EI_(A))trend upward.The E_(A)of fish culture was lower than that of crustaceans,but the EI_(A)of fish culture was generally higher.Sea bass(0.308 Tg/a,in terms of N)and white shrimp(0.945 Tg/a,in terms of N)had the highest average E_(A)among fish and crustacean cultures,respectively.The highest average E_(A)from fish and crustacean were both Guangdong Province(fish:0.248 Tg,crustacean:0.547 Tg),and the highest sea area were both the South China Sea(fish:0.316 Tg,crustacean:1.082 Tg);the highest average EI_(A)for fish and crustacean were Tianjin City[35.40 t/(hm^(2)·a)]and Guangxi Zhuang Autonomous Region[19.83 t/(hm^(2)·a)],respectively,and the highest sea areas were both the South China Sea(fish:0.316 Tg,crustacean:1.082 Tg).These analyses provide baseline data for a greenhouse gas emissions inventory for China,based on an interpretation of them,we provide recommendations for reducing N_(2)O emissions in marine fish and crustacean culture.
基金Supported by National"Twelfth Five-Year Plan"of Scientific and Technological Support Plan(No.2011BAD16B04)~~
文摘This paper monitors the differences of early rice yield and the emissions of methane and nitrous oxide in the paddy field, based on the different cultivation technologies（high-yield scattered-planting mode, transplanting mode, farmer-planting mode）. Results suggested that the rice yield by high-yield scattered-planting mode and transplanting mode was significantly higher than farmer-planting mode, and the increase reached 16.4% and 17.7%. The difference of high-yield scattered-planting mode and transplanting mode was insignificant. The potential contributions of the methane amount by these three patterns to the global contribution were all above90%. The emission of methane during the growth period by the high-yield scatteredplanting mode was dramatically lower than that by transplanting mode and farmerplanting mode, while the differences between the high-yield transplanting mode and the farmer mode were insignificant. The changes of global temperature increase and the emission of methane were the same. The greenhouse gas intensity of high-yield scattered-planting mode was the lowest, and the farmer-planting mode was the highest. Therefore, the scattered-planting with reasonable fertilizing method is the most essential way to realize high yield of rice and the reducing the greenhouse gas emission as well.
基金supported by the National Natural Science Foundation of China (No. 40830101,20977097, 41075094,21177140)the Special Fund for Environmental Research in the Public Interest (No. 201009001)+1 种基金the National Water Special Project (No. 2008ZX07421-001,2009ZX07210-009)the National Basic Research and the Development Program (973) of China (No. 2010CB732304)
文摘Nitrous oxide （N 2 O） emissions from a maize field in the North China Plain （Wangdu County,Hebei Province,China） were investigated using static chambers during two consecutive maize growing seasons in the 2008 and 2009.The N 2 O pulse emissions occurred with duration of about 10 days after basal and additional fertilizer applications in the both years.The average N 2 O fluxes from the CK （control plot,without crop,fertilization and irrigation）,NP （chemical N fertilizer）,SN （wheat straw returning plus chemical N fertilizer）,OM- 1/2N （chicken manure plus half chemical N fertilizer） and OMN （chicken manure plus chemical N fertilizer） plots in 2008 were 8.51,72.1,76.6,101,107 ng N/（m 2 ·sec）,respectively,and in 2009 were 33.7,30.0 and 35.0 ng N/（m 2 ·sec） from CK,NP and SN plots,respectively.The emission factors of the applied fertilizer as N 2 O-N （EFs） were 3.8% （2008） and 1.1% （2009） for the NP plot,3.2% （2008） and 1.2% （2009） for the SN plot,and 2.8% and 2.2% in 2008 for the OM-1/2N and OMN plots,respectively.Hydromorphic properties of the investigated soil （with gley） are in favor of denitrification.The large differences of the soil temperature and water-filled pore space （WFPS） between the two maize seasons were suspected to be responsible for the significant yearly variations.Compared with the treatments of NP and SN,chicken manure coupled with compound fertilizer application significantly reduced fertilizer loss rate as N 2 O-N.
基金supported by the National Key Technologies R&D Program of China (2011BAD16B15 and 2012BAD14B03)
文摘Many studies have focused on various agricultural management measures to reduce agricultural nitrous oxide （N2O） emission. However, few studies have investigated soil N2O emissions in intercropping systems in the North China Plain. Thus, we conducted a ifeld experiment to compare N2O emissions under monoculture and maize-legume intercropping systems. In 2010, ifve treatments, including monocultured maize （M）, maize-peanut （MP）, maize-alfalfa （MA）, maize-soybean （MS）, and maize-sweet clover （MSC） intercropping were designed to investigate this issue using the static chamber technique. In 2011, M, MP, and MS remained, and monocultured peanuts （P） and soybean （S） were added to the trial. The results showed that total production of N2O from different treatments ranged from （0.87＆#177;0.12） to （1.17＆#177;0.11） kg ha-1 in 2010, while those ranged from （3.35＆#177;0.30） to （9.10＆#177;2.09） kg ha-1 in 2011. MA and MSC had no signiifcant effect on soil N2O production compared to that of M （P＆lt;0.05）. Cumulative N2O emissions from MP in 2010 were signiifcantly lower than those from M, but the result was the opposite in 2011 （P＆lt;0.05）. MS signiifcantly reduced soil N2O emissions by 25.55 and 48.84%in 2010 and 2011, respectively （P＆lt;0.05）. Soil N2O emissions were signiifcantly correlated with soil water content, soil temperature, nitriifcation potential, soil NH4＋, and soil NO3-content （R2=0.160-0.764, P＆lt;0.01）. A stepwise linear regression analysis indicated that soil N2O release was mainly controlled by the interaction between soil moisture and soil NO3-content （R2=0.828, P＆lt;0.001）. These results indicate that MS had a coincident effect on soil N2O lfux and signiifcantly reduced soil N2O production compared to that of M over two growing seasons.
文摘A laboratory incubation experiment was conducted to investigate nitrous oxide(N 2O) emission and reduction in a paddy soil(Stagnic Anthrosol) response to the pretreatment of water regime. The paddy soil was maintained under either air dried(sample D) or submerged(sample F) conditions for 110 d before the soil was adjusted into soil moisture of 20%, 40%, 60%, 80% and 100% water holding capacity(WHC) respectively, and then incubated with or without 10%(v/v) acetylene for 138 h at 25℃. At lower soil water content (≤60% WHC), N 2O emission from the sample F was 2 29 times higher than that from the sample D( P <0 01). While, N 2O emission from the sample F was only 29 and 14 percent of that from the sample D at the soil moisture of 80% and 100% WHC, respectively( P <0 01). The maximal N 2O emissions observed at soil moisture of 80% WHC were about 24 and 186 times higher than the minima obtained at the soil moisture of 20% WHC for the sample F and D, respectively. But at the soil moisture of 80% and 100% WHC, N 2O emission from the sample F with acetylene(F+ACE) was comparable to that of the sample D with acetylene (D+ACE). The results showed that the F sample produced N 2O ability in denitrification was similar to the sample D, however, the sample F was in the better reduction of N 2O to N 2 than the sample D even after the soil moisture was adjusted into the same level of 80% or 100% WHC. Therefore, the pretreatment of water regime influenced the strength and product composition of denitrification and N 2O emission from the paddy soil.
基金supported by the Shenzhen Science and Technology Development Funding-Fundamental Research Plan (No. JC201006030878A)the Environmental Protection Funding from Human Settlements and Environment Commission of Shenzhen Municipality
文摘Nitrous oxide （N2O） emission during denitrification is receiving intensive attention due to its high potential to cause greenhouse effects. In this study, denitrifiers were acclimated in sequencing batch reactors with methanol or acetate as the electron donor and nitrate as the electron acceptor. The effects of ammonium on NzO emission were examined in batch experiments with various electron donors. With the addition of ammonium, N2O emission increased under all the examined conditions compared to experiments without ammonium addition. With different electron donors, the highest ratio of N2O emission to the removed oxidized nitrogen was 0.70% for methanol, 5.34% for acetate, and 34.79% for polyhydroxybutyrate.
基金supported by the China Postdoctoral Science Foundation(No.2012M511005)National Key Technology Support Program of China(No.2015BAC02B02)+6 种基金the Agro-scientific Research Programs in Public Interest(No.201303102)National Natural Science Foundation of China(No.31501263)the Postdoctoral Financial Assistance of Heilongjiang Province(No.LBH-Z12232)the Scientific Research Initiation Fund for Introduction of Ph.D Talent of Heilongjiang Academy of Agricultural Sciences(No.201507-14)the State Key Program of China(No.2016YFD0300900)the Major Project of Research and Development of Applied Technology of Heilongjiang Province(No.GA15B101)the Provincial Matching Funds to the National Foundation of Applied Technology Research and Development Program in Heilongjiang Province(No.GX16B002)
文摘Water regime and nitrogen（N） fertilizer are two important factors impacting greenhouse gases（GHG） emission from paddy field, whereas their effects have not been well studied in cold region. In this study, we conducted a two-year field experiment to study the impacts of water regime and N fertilizer on rice yields and GHG emissions in Harbin, China, a cold region located in high latitudes. Our results showed that intermittent irrigation significantly decreased methane（CH4） emission compared with continuous flooding, however,the decrement was far lower than the global average level. The N2O emissions were very small when flooded but peaked at the beginning of the disappearance of floodwater. The N fertilizer treatments increased CH4 emissions at low level（75 kg N/ha）. But both CH4 and N2O emissions were uninfluenced at the levels of 150 kg N/ha and 225 kg N/ha. Rice yields increased under intermittent irrigation and were highest at the level of 150 kg N/ha. From our results, we recommended that the intermittent irrigation and 150 kg N/ha as the ideal water regime-nitrogen fertilizer incorporation for this area to achieve low GHG emissions without impacting rice yields.
基金supported by Important National Science&Technoligy Specific Projects, China (2004BA520A02)
文摘Rice-duck （RD） and rice-fish （RF） ecological systems are major complex planting and breeding models of rice paddy fields in southern China. Studying the methane （CH4） and nitrous oxide （N2O） emissions and their economic value from these two ecosystems can provide theoretical and practical basis for further development and utilization of these classical agricultural techniques. CH4 and N2O emissions from RD and RF ecological systems were measured in situ by using static chambers technique. Using global warming potentials （GWPs）, we assessed the greenhouse effect of CH4 and N2O and their economic value. Results showed that the peaks of CH4 emission fluxes from RD and RF appeared at full tillering stage and at heading stage, and the average emission fluxes were significantly （P〈 0.05） lower than that from CK. N2O fluxes remained low when the field is flooded and high after draining the water. Compared with CK, the total amount of N2O emissions was significantly （P〈0.05） higher and slightly lower than those from RD and RF, respectively. In 2006 and 2007, the total greenhouse effect of CH4 and N20 from RD and RF were 4 728.3 and 4 611 kg CO2 ha^-1, 4 545 and 4 754.3 kg CO2 ha^-1, respectively. The costs of greenhouse effect were 970.89 and 946.81 RMB yuan ha^-1, and 933.25 and 976.23 RMB yuan ha^-1, respectively, which were significant lower than those from CK （5 997.6 and 5 391.5 RMB yuan ha^-1）. Except for the environment cost of CH4 and N2O, the economic benefits from RD and RF were 2 210.64 and 4 881.92 RMB yuan ha^-1; 3 798.37 and 5 310.64 RMB yuan ha^-1, respectively, higher than those from CK. Therefore, RD and RF complex ecological planting and breeding models can effectively decrease and control CH4 and N2O emissions, and they are two of the effective strategies to reduce greenhouse gases from rice paddy fields and contribute in alleviating global warming. Thus, their adoption is important to the environment together with their economy benefits.
基金financially supported by the National Key Research and Development Program of China through grant 2016YFA0601000the National Major Scientific Research Program Grant No.2013CB956401+1 种基金the National Natural Science Foundation of China through Grants Nos.41325010,41403082,and 41302285the Tianjin Research Program of Application Foundation and Advanced Technology Grant No.14JCQNJC08800
文摘Aquatic ecosystems have been identified as a globally significant source of nitrous oxide(N_2O) due to continuous active nitrogen involvement, but the processes and influencing factors that control N_2O production are still poorly understood, especially in reservoirs. For that, monthly N_2O variations were monitored in Dongfeng reservoir(DFR)with a mesotrophic condition. The dissolved N_2O concentration in DFR displayed a distinct spatial–temporal pattern but lower than that in the eutrophic reservoirs. During the whole sampling year, N_2O saturation ranging from 144% to 640%, indicating that reservoir acted as source of atmospheric N_2O. N_2O production is induced by the introduction of nitrogen(NO_3^-, NH_4^+) in mesotrophic reservoirs, and is also affected by oxygen level and water temperature. Nitrification was the predominate process for N_2O production in DFR due to well-oxygenated longitudinal water layers.Mean values of estimated N_2O flux from the air–water interface averaged 0.19 μmol m^(-2)h^(-1) with a range of 0.01–0.61 μmol m^(-2)h^(-1). DFR exhibited less N_2O emission flux than that reported in a nearby eutrophic reservoir, but still acted as a moderate N_2O source compared with other reservoirs and lakes worldwide. Annual emissions from the water–air interface of DFR were estimated to be 0.32×10~5 mol N–N_2O, while N_2O degassing from releasing water behind the dam during power generation was nearly five times greater. Hence, N_2O degassing behind the dam should be taken into account for estimation of N_2O emissions from artificial reservoirs, an omission that historically has probably resulted in underestimates. IPCC methodology should consider more specifically N_2O emission estimation in aquatic ecosystems, especially in reservoirs, the default EF5 model will lead to an overestimation.
基金the German Research Foundation (DFG, Research UnitNo. 536, "Matter fluxes in grasslands of Inner Mongo-lia as influenced by stocking rate", MAGIM) (BU 1173/6-2)the National Natural Science Foundation of China(NSFC) (Grant Nos. 40425010, 40331014)
文摘Increased precipitation during the vegetation periods was observed in and further predicted for Inner Mongolia. The changes in the associated soil moisture may affect the biosphere-atmosphere exchange of greenhouse gases. Therefore, we set up an irrigation experiment with one watered （W） and one unwatered plot （UW） at a winter-grazed Leymus chinensis-steppe site in the Xilin River catchment, Inner Mongolia. UW only received the natural precipitation of 2005 （129 mm）, whereas W was additionally watered after the precipitation data of 1998 （in total 427 mm）. In the 3-hour resolution, we determined nitrous oxide （N20）, methane （CH4） and carbon dioxide （CO2） fluxes at both plots between May and September 2005, using a fully automated, chamber-based measuring system. N20 fluxes in the steppe were very low, with mean emissions （±s.e.） of 0.9-4-0.5 and 0.7-4-0.5 μg N m^-2 h^-1 at W and UW, respectively. The steppe soil always served as a CH4 sink, with mean fluxes of -24.1-4-3.9 and -31.1-4- 5.3 μg C m^-2 h^-1 at W and UW. Nighttime mean CO2 emissions were 82.6±8.7 and 26.3±1.7 mg C m^-2 h^-1 at W and UW, respectively, coinciding with an almost doubled aboveground plant biomass at W. Our results indicate that the ecosystem CO2 respiration responded sensitively to increased water input during the vegetation period, whereas the effects on CH4 and N2O fluxes were weak, most likely due to the high evapotranspiration and the lack of substrate for N2O producing processes. Based on our results, we hypothesize that with the gradual increase of summertime precipitation in Inner Mongolia, ecosystem CO2 respiration will be enhanced and CH4 uptake by the steppe soils will be lightly inhibited.
基金supported by the Research Program of State Key Laboratory of Lake Science and Environment(No.2012SKL012)CAS Key Project(No.KJZD-EW-TZ-G10)+1 种基金the National Basic Research Program(973)of China(No.2012CB417005)the Poyang Lake Wetland Integrated Research Station for their help on field study
文摘Most aquatic ecosystems contribute elevated N2 O to atmosphere due to increasing anthropogenic nitrogen loading. To further understand the spatial heterogeneity along an aquatic continuum from the upriver to wetland to lake to downriver, the study was conducted on spatial variations in N2 O emission along Poyang Lake aquatic continuum during the flood season from 15 July 2013 to 10 August 2013. The results showed the N2 O concentrations, the ratio of N2O/dinitrogen（N2） gases production, N2 O emission and denitrification rates ranged from 0.10 to 1.11 μg N/L,- 0.007% to 0.051%,- 9.73 to 127 μg N/m2/hr and 1.33 × 104to31.9 × 104μg N2/m2/hr, respectively, across the continuum. The average N2 O concentrations,the ratio of N2O/N2 and N2O emission was significantly lower in wetlands as compared to the rivers and lake（p 〈 0.01）. The significantly high denitrification rate and low N2 O emission together highlighted that most N2 O can be converted into N2 via near complete denitrification in the Poyang Lake wetlands. Our study suggests that the wetlands might impact N2 O budget in an integrated aquatic ecosystems. Moreover, N2 O emission from different aquatic ecosystem should be considered separately when quantifying the regional budget in aquatic ecosystem.
基金This work was supported by the National Natural Science Foundation of China （No.10979042 and No.21073173）, the National Key Basic Research Special Foundation of China （No.2007CB815204）, and the Fundamental Research Funds for the Central Universities. Authors also would like to thank Prof. J. B. Nee to provide his experimental data for our reference.
文摘The absorption spectrum of the C1Ⅱ state of N2O molecule in the wavelength range of 142.5-147.5 nm has been measured under the jet-cooled condition, and the clear spectral features are displayed. A vibrational progression is observed with a frequency interval of about 500 cm-1. With the aid of potential energy surfaces （PES） of the low-lying electronic states of N2O, the vibrational progression is assigned as the bending mode of the repulsive C1Ⅱ state. From the Fourier transformation analysis, the recurrence period of the periodic orbit near the transition state region is derived to be 65 fs. Through the least-square Lorentzian fitting, the lifetimes of the resonance levels are estimated from their profile widths to be about 20 fs, which is shorter than the recurrence period. Therefore, a new explanation is suggested for the observed diffuse spectral structure, based on the behavior of dissociating N20 on PES of the C1Ⅱ state in the present excitation energy range.
基金Project supported by the National Natural Science Foundation of China (Nos. 40471072 and 30470060) and the Knowledge Innovation Program of Chinese Academy of Sciences (No. KZCX2-413-3-1).
文摘The rate of nitrous oxide emission from a laboratory sequence batch reactor （SBR） wastewater treatment system using synthetic wastewater was measured under controlled conditions. The SBR was operated in the mode of 4 h for aeration, 3.5 h for stirring without aeration, 0.5 h for settling and drainage, and 4 h of idle. The sludge was acclimated by running the system to achieve a stable running state as chemical oxygen demand, NO2^-, NO3^-, NH4^＋, pH, and N2O. indicated by rhythmic changes of total N, dissolved oxygen, Under the present experimental conditions measured nitrous oxide emitted from the off-gas in the aerobic and anaerobic phases, respectively, accounted for 8.6%-16.1% and 0-0.05% of N removed, indicating that the aerobic phase was the main source of N2O emission from the system. N2O dissolved in discharged water was considerable in term of concentration. Thus, measures to be developed for the purpose of reducing N2O emission from the system should be effective in the aeration phase.
文摘Paddy field is a primary agricultural landscape in the south of China and is often regarded as one of main sources emitting nitrous oxide to atmosphere. The nitrous oxide emissions under a variety of paddy field practices, such as fertilization, flooding/draining management were investigated to study on agricultural activities on paddy field affect the dynamic process of the emission. Under no addition of fertilizers the average emission flux of nitrous oxide was 8 55 μg/(m 2·h) during the rice( Oryza Sativa L.) growth season. The results indicated that most of nitrous oxide emissions occurred during the crack forming and expansion period when paddy field was being drained. The diurnal emissions peak of nitrous oxide appeared at 20∶30 at night in cracked rice fields. The statistical analysis suggested that the correlation of nitrous oxide emissions flux( Y ) with soil water content( X 1), soil temperature( X 2), and E h( X 3), could be described in a regression equation: Y =-1498 95+2895 48 X 1+50 63 X 2-96 99 X 1· X 2+0 006 X 2· X 3 There were the different power equations to simulate the correlations between the everyday dynamic N 2O emissions and the mean surface area of cracks, mean volume and depth of cracks respectively during paddy soil drying by soil columns incubation experiments. Taken all together, the current study presented a dynamic analysis of nitrous oxide emission of paddy field under various conditions, therefore provided a basis for the management to balance between environmental effect and paddy field activities.
基金supported by the Knowledge Innovation Engineering of Chinese Academy of Sciences under contract No.KZCX3-SW-214,KSCX2-SW-132the Natural Science Foundation of Guangdong Province under contract No.032622.
文摘The concentrations of nitrous oxide varies between 57 and 329 nmol/dm3, saturation is 674%～4 134% in the Zhujiang River Estuary. This suggests that the area is an emissive source of nitrous oxide. The acetylene inhibition technique is employed to evaluate the rates of nitrification, denitrification and nitrate reduction by bacterial activities in the sediments at three sites. The average of nitrification, denitrification and nitrate reduction rates ranges from 0.32 to 2.43, 0.03 to 0.84 and 4.17 to 13.06 mmol/(m2·h), respectively. The ver- tical profiles of the sediments show that the nitrification and denitrification processes mainly take place in the depth from 0 to 4 cm and depend on regional conditions. The rates of nitrification, denitrification and nitrate reduction are dominated by Eh, nitrate and ammoni- um concentrations in sediments and DO in overlay water. There is a coupling between nitrification and denitrification.
