The application of nitrogen fertilizers in agricultural fields can lead to the release of nitrogen-containing gases(NCGs),such as NO_(x),NH_(3) and N_(2)O,which can significantly impact regional atmospheric environmen...The application of nitrogen fertilizers in agricultural fields can lead to the release of nitrogen-containing gases(NCGs),such as NO_(x),NH_(3) and N_(2)O,which can significantly impact regional atmospheric environment and con-tribute to global climate change.However,there remain considerable research gaps in the accurate measurement of NCGs emissions from agricultural fields,hindering the development of effective emission reduction strategies.We improved an open-top dynamic chambers(OTDCs)system and evaluated the performance by comparing the measured and given fluxes of the NCGs.The results showed that the measured fluxes of NO,N_(2)O and NH_(3)were 1%,2%and 7%lower than the given fluxes,respectively.For the determination of NH_(3) concentration,we employed a stripping coil-ion chromatograph(SC-IC)analytical technique,which demonstrated an absorption efficiency for atmospheric NH_(3) exceeding 96.1%across sampling durations of 6 to 60 min.In the summer maize season,we utilized the OTDCs system to measure the exchange fluxes of NO,NH_(3),and N_(2)O from the soil in the North China Plain.Substantial emissions of NO,NH_(3) and N_(2)O were recorded following fertilization,with peaks of 107,309,1239 ng N/(m^(2)·s),respectively.Notably,significant NCGs emissions were observed following sus-tained heavy rainfall one month after fertilization,particularly with NH_(3) peak being 4.5 times higher than that observed immediately after fertilization.Our results demonstrate that the OTDCs system accurately reflects the emission characteristics of soil NCGs and meets the requirements for long-term and continuous flux observation.展开更多
China has pledged to peak carbon dioxide(CO_(2))emissions by 2030 and achieve carbon neutrality by 2060.Carbon capture and storage(CCS)will play a key role in these efforts.Over the past several years,the China Geolog...China has pledged to peak carbon dioxide(CO_(2))emissions by 2030 and achieve carbon neutrality by 2060.Carbon capture and storage(CCS)will play a key role in these efforts.Over the past several years,the China Geological Survey(CGS)has completed the Suitability Evaluation Map of CO_(2)Geological Storage in Main Sedimentary Basins in China and Adjacent Sea Regions in 2017.This map reflects the suitability of the first-and secondary-order tectonic units within sedimentary basins for cO_(2)geological storage for CCS planning.The Junggar Basin is recognized as an important region for future CCS projects.Results from a mesoscale evaluation using the volume method indicate that deep saline aquifers represent the most significant resources for CO_(2)storage,with potential ranging from 48×10^(9)to 164×10^(9)t(with a P50 value of 96×10^(9)t).The highest storage potential is identified in the central and northern parts of the basin,reaching up to 9.5×10^(6)t/km^(2)at the P50 probability level.In contrast,the hinterland,eastern,and western parts of the basin generally exhibit storage potential of below 1.0×10^(6)t/km^(2)at the same probability level.The CGs has also characterized historical CO_(2)plume migration in reservoirs at the storage site of the Shenhua CCS demonstration project and conducted numerical simulations of CO_(2)plume migration for periods of 10 and 20 years following the shutdown of the injection well.The CGS implemented a kiloton-scale pilot test on CO_(2)-enhanced water recovery(CO_(2)-EWR)in eastern Junggar,revealing that CO_(2)flooding can improve the pressure for fluid production,with the highest ratio of CO_(2)to produced fluids estimated at approximately 1.2.Besides,an observation field for natural CO_(2)leakage,covering about 930 m^(2),was built in Qinghai Province.In natural CO_(2)fields or at artificial CO_(2)injection research sites,cO_(2)leakage points are primarily related to the distribution of faults(especially fault crossing),which can serve as pathways for CO_(2)leakage.The observation field provides a natural analog to wellbore failure and offers an opportunity to further monitor CO_(2)geological storage sites.However,it has been inferred that borehole ZK10 at the observation field has become a leakage pathway due to the drilling activities,inadequate well-plugging,and abandonment procedures without considering CO_(2)corrosion.展开更多
Gaseous nitrous acid(HONO)is a critical contributor to daytime hydroxyl radical in the troposphere.Livestock farming has been recognized as an overlooked HONO source,but the lack of detailed flux measurements from liv...Gaseous nitrous acid(HONO)is a critical contributor to daytime hydroxyl radical in the troposphere.Livestock farming has been recognized as an overlooked HONO source,but the lack of detailed flux measurements from livestock and poultry wastes would cause uncertainties in modeling its environmental impacts.Here,based on field flux measurements and laboratory experiments,we observed substantial HONO emissions from the composting of swine feces and chicken manure in the warm season,which might be mainly attributed to nitrification process in livestock and poultry wastes.The HONO emission from chicken manure was found to bemuch higher than that from swine feces,and the higher NH3 emission but lower N2O and NO emissions fromchicken manurewere also observed.Considering that the interaction among these nitrogen species during nitrification process,the obviously lower HONO emission from swine feces was likely to be explained by the lack of the total ammonia nitrogen and H+donors in swine feces.Temperature is also a key factor that influences the HONO emission from livestock wastes.In addition,the total HONO emission from swine feces in Chinawas estimated to be approximately 107.7 Gg-N/yr according to the national swine amounts,which is comparable to the national soil HONO emissions,underscoring its non-negligible contribution to regional air quality.Therefore,effective emission control of HONO fromlivestock and poultry wastes should be carried out to further improve air quality in China.展开更多
Three-dimensional(3D)braided composites have significant potential for use in engineering structural materials.However,conventional 3D braiding machines are insufficient for designing composites with complex geometrie...Three-dimensional(3D)braided composites have significant potential for use in engineering structural materials.However,conventional 3D braiding machines are insufficient for designing composites with complex geometries.This paper proposes a programmable design methodology for 3D rotary braiding machines using circle-cutting and combination strategies.By introducing varying numbers of incisions on the circle,a diverse range of horn gears can be designed.Different combinations of these cut-circles allow the horn gears to be assembled into various 3D rotary braiders.The parametric equation for the braider plate is derived,showing that a combination strategy involving two cut-circles is feasible for braider design,whereas integrating three cut-circles simultaneously is impossible for a single machine.The construction of an automatic 6-3 type 3D braiding machine demonstrates the effectiveness of the proposed design strategy.This flexible braider design approach provides a practical solution for producing 3D braided composites with complex geometries.展开更多
Warm dense plasmas are crucial for high-energy-density physics and inertial confinement fusion research.Experiments involving laser-irradiated copper(Cu)foil were performed at the Shenguang-II facility.A highly orient...Warm dense plasmas are crucial for high-energy-density physics and inertial confinement fusion research.Experiments involving laser-irradiated copper(Cu)foil were performed at the Shenguang-II facility.A highly oriented pyrolytic graphite crystal spectrometer measured the time-integrated spectral distribution of Cu under varying laser intensities.Using the two-dimensional radiation-hydrodynamics code FLASH and the spectral analysis code FLYCHK,we simulated the temporal evolution of plasma density and temperature distributions,as well as the emission intensities of spectral lines at different temperatures and densities.The simulation results revealed that the two-electron satellite lines(J)and the resonance line(W)emissions of Cu originate predominantly from the radiation region near the critical density surface,with a density range from approximately 0.5 nc to 1.0 nc,and radiate primarily during the laser irradiation period.By analyzing the J/W intensity ratio of the measured spectral lines,we estimated the electron temperatures near the critical-density surface under different laser intensities.展开更多
Air concentrations of volatile organic compounds(VOCs) were continually measured at a monitoring site in Shenyang from 20 August to 16 September 2017. The average concentrations of alkanes, alkenes, aromatics and carb...Air concentrations of volatile organic compounds(VOCs) were continually measured at a monitoring site in Shenyang from 20 August to 16 September 2017. The average concentrations of alkanes, alkenes, aromatics and carbonyls were 28.54, 6.30, 5.59 and9.78 ppbv, respectively. Seven sources were identified by the Positive Matrix Factorization model based on the measurement data of VOCs and CO. Vehicle exhaust contributed the most(36.15%) to the total propene-equivalent concentration of the measured VOCs,followed by combustion emission(16.92%), vegetation emission and secondary formation(14.33%), solvent usage(10.59%), petrochemical industry emission(9.89%), petrol evaporation(6.28%), and liquefied petroleum gas(LPG) usage(5.84%). Vehicle exhaust, solvent usage and combustion emission were found to be the top three VOC sources for O_3 formation potential, accounting for 34.52%, 16.55% and 11.94%, respectively. The diurnal variation of the total VOCs from each source could be well explained by their emission characteristics,e.g., the two peaks of VOC concentrations from LPG usage were in line with the cooking times for breakfast and lunch. Wind rose plots of the VOCs from each source could reveal the possible distribution of the sources around the monitoring site. The O_3 pollution episodes during the measurement period were found to be coincident with the elevation of VOCs, which was mainly due to the air parcel from the southeast direction where petrochemical industry emission was found to be dominant, suggesting that the petrochemical industry emission from the southeast was probably a significant cause of O_3 pollution in Shenyang.展开更多
The pollution levels,composition characteristics and sources of atmospheric PM2.5 were investigated based on field measurement at a rural site in the North China Plain(NCP) from pre-heating period to heating period in...The pollution levels,composition characteristics and sources of atmospheric PM2.5 were investigated based on field measurement at a rural site in the North China Plain(NCP) from pre-heating period to heating period in winter of 2017.The hourly average concentrations of PM2.5 frequently exceeded 150 μg/m3 and even achieved 400 μg/m3,indicating that the PM2.5pollution was still very serious despite the implementation of stricter control measures in the rural area.Compared with the pre-heating period,the mean concentrations of organic carbon(OG),element carbon(EC) and chlorine ion(Cl-) during the heating period increased by 20.8%,36.6% and 38.8%,accompanying with increments of their proportions in PM2.5from 37.5%,9.8% and 5.5% to 42.9%,12.7% and 7.2%,respectively.The significant increase of both their concentrations and proportions during the heating period was mainly ascribed to the residential coal combustion.The proportions of sulfate,nitrate and ammonium respectively increased from 9.9%,10.9% and 9.0% in nighttime to 13.8%,16.2% and 11.1% in daytime,implying that the daytime photochemical reactions made remarkable contributions to the secondary inorganic aerosols.The simulation results from WRF-Chem revealed that the emission of residential coal combustion in the rural area was underestimated by the current emission inventory.Six sources identified by positive matrix factorization(PMF) based on the measurement were residential coal combustion,secondary formation of inorganic aerosols,biomass burning,vehicle emission and raising dust,contributing to atmospheric PM2.5 of 40.5%,21.2%,16.4%,10.8%,8.6% and 2.5%,respectively.展开更多
Tropospheric ozone(O_(3))pollution is increasing in the Beijing-Tianjin-Hebei(BTH)region despite a significant decline in atmospheric fine aerosol particles(PM_(2.5))in recent years.However,the intrinsic reason for th...Tropospheric ozone(O_(3))pollution is increasing in the Beijing-Tianjin-Hebei(BTH)region despite a significant decline in atmospheric fine aerosol particles(PM_(2.5))in recent years.However,the intrinsic reason for the elevation of the regional O_(3)is still unclear.In this study,we analyzed the spatio-temporal variations of tropospheric O_(3)and relevant pollutants(PM_(2.5),NO_(2),and CO)in the BTH region based on monitoring data from the China Ministry of Ecology and Environment during the period of 2014-2019.The results showed that summertime O_(3)concentrations were constant in Beijing(BJ,0.06μg/(m^(3)·year))but increased significantly in Tianjin(TJ,9.09μg/(m^(3)·year))and Hebei(HB,6.06μg/(m3·year)).Distinct O_(3)trends between Beijing and other cities in BTH could not be attributed to the significant decrease in PM_(2.5)(from-5.08 to-6.32μg/(m3·year))and CO(from-0.053 to-0.090 mg/(m^(3)·year))because their decreasing rates were approximately the same in all the cities.The relatively stable O_(3)concentrations during the investigating period in BJ may be attributed to a faster decreasing rate of NO_(2)(BJ:-2.55μg/(m^(3)·year);TJ:-1.16μg/(m^(3)·year);HB:-1.34μg/(m3·year)),indicating that the continued reduction of NOx will be an effective mitigation strategy for reducing regional O_(3)pollution.Significant positive correlations were found between daily maximum8 hr average(MDA8)O_(3)concentrations and vehicle population and highway freight transportation in HB.Therefore,we speculate that the increase in rural NO_(x)emissions due to the increase in vehicle emissions in the vast rural areas around HB greatly accelerates regional O_(3)formation,accounting for the significant increasing trends of O_(3)in HB.展开更多
As green solvents,ionic liquids(ILs)are quite suitable for the absorption of volatile organic compounds(VOCs)such as benzene and its homologues.However,solvent selection is the key to the VOC absorption process.In the...As green solvents,ionic liquids(ILs)are quite suitable for the absorption of volatile organic compounds(VOCs)such as benzene and its homologues.However,solvent selection is the key to the VOC absorption process.In the present study,a rapid solvent screening tool,Conductor-like Screening Model for Real Solvents(COSMO-RS),was used to predict the solubility of toluene in 816 ILs.The effects of four structure characters,namely,the type and alkyl chain length of the cations and anions on the solubility of toluene were discussed.The following conclusions were drawn from the results:(1)ILs with pyrrolidinium-based cations showed better solubility than pyridinium-and imidazoliumbased ones.(2)The solubility of toluene in PF6-based ILs increased with the increasing alkyl chain length,while its solubility in Ac-based ILs exhibited the opposite trend.(3)Toluene showed greater solubility in Cl-based ILs than those based on other anions.(4)The solubility of toluene increased with the anion alkyl chain length.Ac-based ILs were chosen as the most promising potential solvents,and further studied to determine the relationship between various interaction energy parameters and toluene solubility.The results showed that the misfit energy played a dominant role during the absorption process.Furthermore,several ILs were selected for experimental verification of the predicted solubility behavior using liquid and gaseous toluene.The results demonstrated that COSMO-RS could be used to semi-quantitatively and qualitatively predict the solubility of toluene,and this model had promising prospects in screening ILs for VOCs absorption.In summary,this study provided a fundamental basis and practical data for the control and treatment of VOCs.展开更多
Atmospheric peroxyacetyl nitrate （PAN）, peroxypropionyl nitrate （PPN）, and carbon tetrachloride （CCl4） were measured from September 2010 to August 2011 in Beijing. PAN exhibited low values from mid-autumn to ear...Atmospheric peroxyacetyl nitrate （PAN）, peroxypropionyl nitrate （PPN）, and carbon tetrachloride （CCl4） were measured from September 2010 to August 2011 in Beijing. PAN exhibited low values from mid-autumn to early spring （October to March） with monthly average concentrations ranging from 0.28 to 0.73 ppbV, and increased from early spring to summer （March to August）, ranging from 1.37-3.79 ppbV. The monthly variation of PPN was similar to PAN, with low values （below detection limit to 0.18 ppbV） from mid-autumn to early spring, and a monthly maximum in September （1.14 ppbV）. The monthly variation of CCl4 was tightly related to the variation of temperature, exhibiting a minimum in winter （69.3 pptV） and a maximum of 180.6 pptV in summer. Due to weak solar intensity and short duration, PAN and O3 showed no distinct diurnal patterns from morning to night during winter, whereas for other seasons, they both exhibited maximal values in the late afternoon （ca. 15：00 to 16：00 local time） and minimal values during early morning and midnight. Good linear correlations between PAN and PPN were found in autumn （R = 0.91）, spring （R = 0.94）, and summer （R = 0.81）, with slopes of 0.130, 0.222, and 0.133, respectively, suggesting that anthropogenic hydrocarbons dominated the photochemical formation of PANs in Beijing. Positive correlation between PAN and O3 in summer with the low slopes （AO3/APAN） ranging from 9.92 to 18.0 indicated serious air pollution in Beijing, and strong negative correlation in winter reflected strong O3 consumption by NO titration and less thermal decompositin of PAN.展开更多
Submarine volcanism is widely developed in the South China Sea(SCS).However,the characteristics,distribution,and genesis of submarine volcanoes in the southern margin of the SCS remain obscure.In this study,we analyze...Submarine volcanism is widely developed in the South China Sea(SCS).However,the characteristics,distribution,and genesis of submarine volcanoes in the southern margin of the SCS remain obscure.In this study,we analyzed the characteristics of submarine volcanoes and identified a total of 43 submarine volcanoes in the southern margin of the SCS,based on a newly acquired 310-km seismic reflection profile,along with previous 45 multi-channel seismic(MCS)profiles,petrological results from volcanic rocks sampled by dredging and drilling,nearby ocean bottom seismometer(OBS)wide-angle seismic profiles,and gravity and magnetic data.The study ascertains that most of these volcanoes are located in fault-block belts and graben-horst zones with strong crustal stretching and thinning.These volcanoes exhibit positive high-amplitude external seismic reflections,weak and chaotic internal seismic reflections,and are accompanied by local deformation of the surrounding sedimentary strata.Meanwhile,they have higher positive gravity anomalies and higher magnetic anomalies than the background strata.The petrological dating results show that volcanic ages are primarily in the Pliocene-Pleistocene,with geochemical characteristics indicating dominance of oceanic island basalt(OIB)-type alkali-basalts.Extensional faults have obviously spatial correspondence with post-spreading volcanism,suggesting these faults may provide conduits for submarine volcanism.The high-velocity bodies(HVBs)in the lower crust and magma underplating exist in the southern SCS,which could provide a clue of genesis for submarine volcanism.The inference is that the intensity of post-spreading volcanism in the southern margin might be affected by stretching faults,crustal thinning and magma underplating.展开更多
Atmospheric carbonyls were measured at a typical rural area of the North China Plain(NCP)from November 13 to December 24,2017 to investigate the pollution characteristics,sources and environmental implications.Fifteen...Atmospheric carbonyls were measured at a typical rural area of the North China Plain(NCP)from November 13 to December 24,2017 to investigate the pollution characteristics,sources and environmental implications.Fifteen carbonyls were detected,and formaldehyde,acetaldehyde and acetone accounted for about 81% at most.The concentration of the total carbonyls in heavily polluted days was twice more than that in clean days.In contrast to other carbonyls,m-tolualdehyde exhibited relatively high concentrations in the clean days in comparison with the polluted days.The ratios of three principal carbonyls to CO showed similar daily variations at different pollution levels with significant daytime peaks.Multiple linear regression analysis revealed that the contributions of background,primary and secondary sources to three principal carbonyls showed similar variation trends from the clean level to the heavily polluted level.The OH formation rate of formaldehyde showed a similar variation trend to its photodegradation rate,reaching the peak value at noon,which is important to maintain relatively high OH levels to initiate the oxidation of various gas-phase pollutants for secondary pollutant formation at the rural site.OH radical consumption rate and ozone formation potential(OFP) calculations showed that formaldehyde and acetaldehyde were the dominant oxidative species among measured carbonyls.As for OH radical consumption,n-butyraldehyde and m-tolualdehyde were important contributors,while for ozone formation potential,n-butyraldehyde and propionaldehyde made significant contributions.In addition,the contribution of carbonyl compounds to secondary organic aerosol(SOA) formation was also important and needs further investigation.展开更多
The efficient maintenance of the activity of excised branches is the powerful guarantee to accurately determine gas exchange flux between the detached branches of tall trees and the atmosphere. In this study, the net ...The efficient maintenance of the activity of excised branches is the powerful guarantee to accurately determine gas exchange flux between the detached branches of tall trees and the atmosphere. In this study, the net photosynthetic rate(NPR) of the excised branches and branches in situ were measured simultaneously by using two photosynthetic instruments to characterize the activity of the excised branches of Phyllostachys nigra. The ratio of normalized NPR of excised branches to NPR in situ was used to assess the photosynthetic activity of detached branches. Based on photosynthetic activity, an optimal hydroponics protocol for maintaining activity of excised P. nigra branches was presented:1/8 times the concentration of Gamborg B5 vitamin mixture with p H = 6. Under the best cultivation protocol, photosynthetic activity of excised P. nigra branches could be maintained more than 90% within 6 hr in the light intensity range of 200–2000 μmol/(m2·sec) and temperature range of 13.4–28.7°C. The nitrogen dioxide(NO2) flux differences between in situ and in vitro branches and the atmosphere were compared using double dynamic chambers.Based on the maintenance method of excised branches, the NO2 exchange flux between the excised P. nigra branches and the atmosphere(from-1.01 to-2.72 nmol/(m2·sec) was basically consistent with between the branches in situ and the atmosphere(from-1.12 to-3.16 nmol/(m2 sec)) within 6 hr. Therefore, this study provided a feasible protocol for in vitro measurement of gas exchange between tall trees and the atmosphere for a period of time.展开更多
Atmospheric mixing ratios of carbonyl sulfide（COS） in Beijing were intensively measured from March 2011 to June 2013. COS mixing ratios exhibited distinct seasonal variation, with a maximum average value of 849 ...Atmospheric mixing ratios of carbonyl sulfide（COS） in Beijing were intensively measured from March 2011 to June 2013. COS mixing ratios exhibited distinct seasonal variation, with a maximum average value of 849 ± 477 pptv in winter and a minimal value of 372 ± 115 pptv in summer. The seasonal variation of COS was mainly ascribed to the combined effects of vegetation uptake and anthropogenic emissions. Two types of significant linear correlations（R2〉 0.66） were found between COS and CO during the periods from May to June and from October to March, with slopes（ΔCOS/ΔCO） of 0.72 and 0.14 pptv/ppbv, respectively. Based on the emission ratios of COS/CO from various sources, the dominant anthropogenic sources of COS in Beijing were found to be vehicle tire wear in summer and coal burning in winter. The total anthropogenic emission of COS in Beijing was roughly estimated as 0.53 ± 0.02 Gg/year based on the local CO emission inventory and the ΔCOS/ΔCO ratios.展开更多
Carbonaceous aerosols(CA) are crucial components in the atmospheric PM_(2.5) and derived from diverse sources. One of the major sources for CA is from the incomplete combustion of bituminous coal that has been prevail...Carbonaceous aerosols(CA) are crucial components in the atmospheric PM_(2.5) and derived from diverse sources. One of the major sources for CA is from the incomplete combustion of bituminous coal that has been prevailingly used by household stoves in rural areas for heating during winter. To efficiently eliminate the CA emission, a new household stove(NHS) was developed based on a novel combustion technology and CA emissions from the NHS and a traditional household stove(THS) were comparably investigated under the actual stove operation conditions in a farmer’s house. Compared with the THS, the emission factors of organic carbon(OC), elemental carbon(EC), and water-soluble organic carbon(WSOC) from the NHS were reduced by 96%±1%, 98%±1%, and 91%±1% under the flaming process and 95%±1%, 96%±2%, and 83%±4% under the smoldering process, respectively. Additionally,the mass absorption efficiency of WSOC from the NHS reduced by 3 folds and the radiative forcing by WSOC relative to EC shrank remarkably by a factor of 3-8. Based on the reduction of emissions and light absorption of WSOC, the promotion of the NHS offers a possible solution to achieve the clean combustion of residential solid fuel.展开更多
Atmospheric BTEX compounds（benzene, toluene, ethylbenzene and xylenes） in a rural site of the North China Plain（NCP） were preliminarily investigated in winter, and the outdoor concentrations（25.8–236.0 μg/m^3）...Atmospheric BTEX compounds（benzene, toluene, ethylbenzene and xylenes） in a rural site of the North China Plain（NCP） were preliminarily investigated in winter, and the outdoor concentrations（25.8–236.0 μg/m^3） were found to be much higher than those reported in urban regions. The pollution of BTEX inside a farmer＇s house was even more serious, with combined concentrations of 254.5–1552.9 μg/m^3. Based on the ratio of benzene to toluene（1.17 ± 0.34） measured, the serious BTEX pollution in the rural site was mainly ascribed to domestic coal combustion for heating during the winter season. With the enhancement of farmers＇ incomes in recent years, coal consumption by farmers in the NCP is rapidly increasing to keep their houses warm, and hence the serious air pollution in rural areas of the NCP during winter, including BTEX, should be paid great attention.展开更多
Nitrogen dioxide(NO2)is an important substance in atmospheric photochemical processes and can also be absorbed by plants.N02 fluxes between the atmosphere and P.nigrc seedlings were investigated by a double dynamic ch...Nitrogen dioxide(NO2)is an important substance in atmospheric photochemical processes and can also be absorbed by plants.N02 fluxes between the atmosphere and P.nigrc seedlings were investigated by a double dynamic chambers method in Beijing from June 15to September 3,2017.The range of N02 exchange fluxes between P.nigra seedlings and the atmosphere was from-14.6 to 0.8 nmol/(m2.sec)(the positive data represent N02 emissior from trees,while the negative values indicate absorption).Under ambient concentrations the mean NO2 flux during the fast-growing stage(Jun.15-Aug.4)was-3.0 nmol/(m2·sec)greater than the flux of-1.5 nmol/(m2-sec)during the later growth stage(Aug.8-Sept.3)The daily exchange fluxes of NO2 obviously fluctuated.The fluxes were largest in the morning and decreased gradually over time.Additionally,the N02 fluxes were larger undei high light intensities than under low light intensities during the whole growth period.The effects of temperature on N02 fluxes were different under two growth periods.The NO2exchange fluxes were larger in a range of temperatures close to 44℃in the fast-growing stage,whereas there were no evident differences in N02 exchange fluxes under widel differing temperatures in the later growth stage.Under polluted conditions,the uptake ability of N02 was weakened.Additionally,the compensation point of N02 was 5.6 ppb ir the fast-growing stage,whereas it was 1.4 ppb in the later growth stage.The depositior velocities of NO2 were between 0.3 and 2.4 mm/sec.展开更多
基金supported by the National Key Research and Develop-ment Program(No.2022YFC3701103)the National Natural Science Foundation of China(Nos.42130714 and 41931287).
文摘The application of nitrogen fertilizers in agricultural fields can lead to the release of nitrogen-containing gases(NCGs),such as NO_(x),NH_(3) and N_(2)O,which can significantly impact regional atmospheric environment and con-tribute to global climate change.However,there remain considerable research gaps in the accurate measurement of NCGs emissions from agricultural fields,hindering the development of effective emission reduction strategies.We improved an open-top dynamic chambers(OTDCs)system and evaluated the performance by comparing the measured and given fluxes of the NCGs.The results showed that the measured fluxes of NO,N_(2)O and NH_(3)were 1%,2%and 7%lower than the given fluxes,respectively.For the determination of NH_(3) concentration,we employed a stripping coil-ion chromatograph(SC-IC)analytical technique,which demonstrated an absorption efficiency for atmospheric NH_(3) exceeding 96.1%across sampling durations of 6 to 60 min.In the summer maize season,we utilized the OTDCs system to measure the exchange fluxes of NO,NH_(3),and N_(2)O from the soil in the North China Plain.Substantial emissions of NO,NH_(3) and N_(2)O were recorded following fertilization,with peaks of 107,309,1239 ng N/(m^(2)·s),respectively.Notably,significant NCGs emissions were observed following sus-tained heavy rainfall one month after fertilization,particularly with NH_(3) peak being 4.5 times higher than that observed immediately after fertilization.Our results demonstrate that the OTDCs system accurately reflects the emission characteristics of soil NCGs and meets the requirements for long-term and continuous flux observation.
基金funded by the National Natural Science Foundation of China(No.42141013)China Geological Survey(DD20221818,DD20242513).
文摘China has pledged to peak carbon dioxide(CO_(2))emissions by 2030 and achieve carbon neutrality by 2060.Carbon capture and storage(CCS)will play a key role in these efforts.Over the past several years,the China Geological Survey(CGS)has completed the Suitability Evaluation Map of CO_(2)Geological Storage in Main Sedimentary Basins in China and Adjacent Sea Regions in 2017.This map reflects the suitability of the first-and secondary-order tectonic units within sedimentary basins for cO_(2)geological storage for CCS planning.The Junggar Basin is recognized as an important region for future CCS projects.Results from a mesoscale evaluation using the volume method indicate that deep saline aquifers represent the most significant resources for CO_(2)storage,with potential ranging from 48×10^(9)to 164×10^(9)t(with a P50 value of 96×10^(9)t).The highest storage potential is identified in the central and northern parts of the basin,reaching up to 9.5×10^(6)t/km^(2)at the P50 probability level.In contrast,the hinterland,eastern,and western parts of the basin generally exhibit storage potential of below 1.0×10^(6)t/km^(2)at the same probability level.The CGs has also characterized historical CO_(2)plume migration in reservoirs at the storage site of the Shenhua CCS demonstration project and conducted numerical simulations of CO_(2)plume migration for periods of 10 and 20 years following the shutdown of the injection well.The CGS implemented a kiloton-scale pilot test on CO_(2)-enhanced water recovery(CO_(2)-EWR)in eastern Junggar,revealing that CO_(2)flooding can improve the pressure for fluid production,with the highest ratio of CO_(2)to produced fluids estimated at approximately 1.2.Besides,an observation field for natural CO_(2)leakage,covering about 930 m^(2),was built in Qinghai Province.In natural CO_(2)fields or at artificial CO_(2)injection research sites,cO_(2)leakage points are primarily related to the distribution of faults(especially fault crossing),which can serve as pathways for CO_(2)leakage.The observation field provides a natural analog to wellbore failure and offers an opportunity to further monitor CO_(2)geological storage sites.However,it has been inferred that borehole ZK10 at the observation field has become a leakage pathway due to the drilling activities,inadequate well-plugging,and abandonment procedures without considering CO_(2)corrosion.
基金supported by the National Key Research and Development Program(No.2022YFC3701102)the National Natural Science Foundation of China(Nos.41905109,42405114,and 42105105).
文摘Gaseous nitrous acid(HONO)is a critical contributor to daytime hydroxyl radical in the troposphere.Livestock farming has been recognized as an overlooked HONO source,but the lack of detailed flux measurements from livestock and poultry wastes would cause uncertainties in modeling its environmental impacts.Here,based on field flux measurements and laboratory experiments,we observed substantial HONO emissions from the composting of swine feces and chicken manure in the warm season,which might be mainly attributed to nitrification process in livestock and poultry wastes.The HONO emission from chicken manure was found to bemuch higher than that from swine feces,and the higher NH3 emission but lower N2O and NO emissions fromchicken manurewere also observed.Considering that the interaction among these nitrogen species during nitrification process,the obviously lower HONO emission from swine feces was likely to be explained by the lack of the total ammonia nitrogen and H+donors in swine feces.Temperature is also a key factor that influences the HONO emission from livestock wastes.In addition,the total HONO emission from swine feces in Chinawas estimated to be approximately 107.7 Gg-N/yr according to the national swine amounts,which is comparable to the national soil HONO emissions,underscoring its non-negligible contribution to regional air quality.Therefore,effective emission control of HONO fromlivestock and poultry wastes should be carried out to further improve air quality in China.
基金funded by the Shanghai Natural Science Foundation of Shanghai Municipal Science and Technology Commission(20ZR1400600)the Fundamental Research Funds for the Central Universities(2232023G-06)through collaborative research with the Advanced Fibrous Materials Lab(AFML)at the University of British Columbia.
文摘Three-dimensional(3D)braided composites have significant potential for use in engineering structural materials.However,conventional 3D braiding machines are insufficient for designing composites with complex geometries.This paper proposes a programmable design methodology for 3D rotary braiding machines using circle-cutting and combination strategies.By introducing varying numbers of incisions on the circle,a diverse range of horn gears can be designed.Different combinations of these cut-circles allow the horn gears to be assembled into various 3D rotary braiders.The parametric equation for the braider plate is derived,showing that a combination strategy involving two cut-circles is feasible for braider design,whereas integrating three cut-circles simultaneously is impossible for a single machine.The construction of an automatic 6-3 type 3D braiding machine demonstrates the effectiveness of the proposed design strategy.This flexible braider design approach provides a practical solution for producing 3D braided composites with complex geometries.
基金Project supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant Nos.XDA25051000,XDA25010100,XDA25010300,XDA25030100,and XDA25030200)。
文摘Warm dense plasmas are crucial for high-energy-density physics and inertial confinement fusion research.Experiments involving laser-irradiated copper(Cu)foil were performed at the Shenguang-II facility.A highly oriented pyrolytic graphite crystal spectrometer measured the time-integrated spectral distribution of Cu under varying laser intensities.Using the two-dimensional radiation-hydrodynamics code FLASH and the spectral analysis code FLYCHK,we simulated the temporal evolution of plasma density and temperature distributions,as well as the emission intensities of spectral lines at different temperatures and densities.The simulation results revealed that the two-electron satellite lines(J)and the resonance line(W)emissions of Cu originate predominantly from the radiation region near the critical density surface,with a density range from approximately 0.5 nc to 1.0 nc,and radiate primarily during the laser irradiation period.By analyzing the J/W intensity ratio of the measured spectral lines,we estimated the electron temperatures near the critical-density surface under different laser intensities.
基金supported by the National Key Research and Development Program of China(Nos.2016YFC0202200,2017YFC0209703)the National Natural Science Foundation of China(Nos.91544211,4127805,41575121,21707151)the National research program for Key issues in air pollution control(Nos.DQGG0103,DQGG0206,DQGG0209)
文摘Air concentrations of volatile organic compounds(VOCs) were continually measured at a monitoring site in Shenyang from 20 August to 16 September 2017. The average concentrations of alkanes, alkenes, aromatics and carbonyls were 28.54, 6.30, 5.59 and9.78 ppbv, respectively. Seven sources were identified by the Positive Matrix Factorization model based on the measurement data of VOCs and CO. Vehicle exhaust contributed the most(36.15%) to the total propene-equivalent concentration of the measured VOCs,followed by combustion emission(16.92%), vegetation emission and secondary formation(14.33%), solvent usage(10.59%), petrochemical industry emission(9.89%), petrol evaporation(6.28%), and liquefied petroleum gas(LPG) usage(5.84%). Vehicle exhaust, solvent usage and combustion emission were found to be the top three VOC sources for O_3 formation potential, accounting for 34.52%, 16.55% and 11.94%, respectively. The diurnal variation of the total VOCs from each source could be well explained by their emission characteristics,e.g., the two peaks of VOC concentrations from LPG usage were in line with the cooking times for breakfast and lunch. Wind rose plots of the VOCs from each source could reveal the possible distribution of the sources around the monitoring site. The O_3 pollution episodes during the measurement period were found to be coincident with the elevation of VOCs, which was mainly due to the air parcel from the southeast direction where petrochemical industry emission was found to be dominant, suggesting that the petrochemical industry emission from the southeast was probably a significant cause of O_3 pollution in Shenyang.
基金supported by the National Natural Science Foundation of China(Nos.91544211,41727805,41575121,and 21707151)the National research program for Key issues in air pollution control(Nos.DQGG0103,DQGG0209,and DQGG0206)+1 种基金the National Key Research and Development Program of China(Nos.2016YFC0202200,2017YFC0209703,and 2017YFF0108301)Key Laboratory of Atmospheric Chemistry,China Meteorological Administration(No.2018B03)
文摘The pollution levels,composition characteristics and sources of atmospheric PM2.5 were investigated based on field measurement at a rural site in the North China Plain(NCP) from pre-heating period to heating period in winter of 2017.The hourly average concentrations of PM2.5 frequently exceeded 150 μg/m3 and even achieved 400 μg/m3,indicating that the PM2.5pollution was still very serious despite the implementation of stricter control measures in the rural area.Compared with the pre-heating period,the mean concentrations of organic carbon(OG),element carbon(EC) and chlorine ion(Cl-) during the heating period increased by 20.8%,36.6% and 38.8%,accompanying with increments of their proportions in PM2.5from 37.5%,9.8% and 5.5% to 42.9%,12.7% and 7.2%,respectively.The significant increase of both their concentrations and proportions during the heating period was mainly ascribed to the residential coal combustion.The proportions of sulfate,nitrate and ammonium respectively increased from 9.9%,10.9% and 9.0% in nighttime to 13.8%,16.2% and 11.1% in daytime,implying that the daytime photochemical reactions made remarkable contributions to the secondary inorganic aerosols.The simulation results from WRF-Chem revealed that the emission of residential coal combustion in the rural area was underestimated by the current emission inventory.Six sources identified by positive matrix factorization(PMF) based on the measurement were residential coal combustion,secondary formation of inorganic aerosols,biomass burning,vehicle emission and raising dust,contributing to atmospheric PM2.5 of 40.5%,21.2%,16.4%,10.8%,8.6% and 2.5%,respectively.
基金supported by the National Natural Science Foundation of China(Nos.41975164,41727805,41931287,21976190,22076202,21876186,and 41905109)
文摘Tropospheric ozone(O_(3))pollution is increasing in the Beijing-Tianjin-Hebei(BTH)region despite a significant decline in atmospheric fine aerosol particles(PM_(2.5))in recent years.However,the intrinsic reason for the elevation of the regional O_(3)is still unclear.In this study,we analyzed the spatio-temporal variations of tropospheric O_(3)and relevant pollutants(PM_(2.5),NO_(2),and CO)in the BTH region based on monitoring data from the China Ministry of Ecology and Environment during the period of 2014-2019.The results showed that summertime O_(3)concentrations were constant in Beijing(BJ,0.06μg/(m^(3)·year))but increased significantly in Tianjin(TJ,9.09μg/(m^(3)·year))and Hebei(HB,6.06μg/(m3·year)).Distinct O_(3)trends between Beijing and other cities in BTH could not be attributed to the significant decrease in PM_(2.5)(from-5.08 to-6.32μg/(m3·year))and CO(from-0.053 to-0.090 mg/(m^(3)·year))because their decreasing rates were approximately the same in all the cities.The relatively stable O_(3)concentrations during the investigating period in BJ may be attributed to a faster decreasing rate of NO_(2)(BJ:-2.55μg/(m^(3)·year);TJ:-1.16μg/(m^(3)·year);HB:-1.34μg/(m3·year)),indicating that the continued reduction of NOx will be an effective mitigation strategy for reducing regional O_(3)pollution.Significant positive correlations were found between daily maximum8 hr average(MDA8)O_(3)concentrations and vehicle population and highway freight transportation in HB.Therefore,we speculate that the increase in rural NO_(x)emissions due to the increase in vehicle emissions in the vast rural areas around HB greatly accelerates regional O_(3)formation,accounting for the significant increasing trends of O_(3)in HB.
基金supported by the National Natural Science Foundation of China(51474146,21806102)Graduate Program Funding of Shanghai Polytechnic University(A01GY18F022-d04,EGD18YJ0004)Gaoyuan Discipline of Shanghai–Environmental Science and Engineering(Resource Recycling Science and Engineering)
文摘As green solvents,ionic liquids(ILs)are quite suitable for the absorption of volatile organic compounds(VOCs)such as benzene and its homologues.However,solvent selection is the key to the VOC absorption process.In the present study,a rapid solvent screening tool,Conductor-like Screening Model for Real Solvents(COSMO-RS),was used to predict the solubility of toluene in 816 ILs.The effects of four structure characters,namely,the type and alkyl chain length of the cations and anions on the solubility of toluene were discussed.The following conclusions were drawn from the results:(1)ILs with pyrrolidinium-based cations showed better solubility than pyridinium-and imidazoliumbased ones.(2)The solubility of toluene in PF6-based ILs increased with the increasing alkyl chain length,while its solubility in Ac-based ILs exhibited the opposite trend.(3)Toluene showed greater solubility in Cl-based ILs than those based on other anions.(4)The solubility of toluene increased with the anion alkyl chain length.Ac-based ILs were chosen as the most promising potential solvents,and further studied to determine the relationship between various interaction energy parameters and toluene solubility.The results showed that the misfit energy played a dominant role during the absorption process.Furthermore,several ILs were selected for experimental verification of the predicted solubility behavior using liquid and gaseous toluene.The results demonstrated that COSMO-RS could be used to semi-quantitatively and qualitatively predict the solubility of toluene,and this model had promising prospects in screening ILs for VOCs absorption.In summary,this study provided a fundamental basis and practical data for the control and treatment of VOCs.
基金supported by the National Natural Science Foundation of China(No.41075094,21177140,20977097)the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDB05010100)the National Basic Research Program(973)of China(No.2010CB732304)
文摘Atmospheric peroxyacetyl nitrate （PAN）, peroxypropionyl nitrate （PPN）, and carbon tetrachloride （CCl4） were measured from September 2010 to August 2011 in Beijing. PAN exhibited low values from mid-autumn to early spring （October to March） with monthly average concentrations ranging from 0.28 to 0.73 ppbV, and increased from early spring to summer （March to August）, ranging from 1.37-3.79 ppbV. The monthly variation of PPN was similar to PAN, with low values （below detection limit to 0.18 ppbV） from mid-autumn to early spring, and a monthly maximum in September （1.14 ppbV）. The monthly variation of CCl4 was tightly related to the variation of temperature, exhibiting a minimum in winter （69.3 pptV） and a maximum of 180.6 pptV in summer. Due to weak solar intensity and short duration, PAN and O3 showed no distinct diurnal patterns from morning to night during winter, whereas for other seasons, they both exhibited maximal values in the late afternoon （ca. 15：00 to 16：00 local time） and minimal values during early morning and midnight. Good linear correlations between PAN and PPN were found in autumn （R = 0.91）, spring （R = 0.94）, and summer （R = 0.81）, with slopes of 0.130, 0.222, and 0.133, respectively, suggesting that anthropogenic hydrocarbons dominated the photochemical formation of PANs in Beijing. Positive correlation between PAN and O3 in summer with the low slopes （AO3/APAN） ranging from 9.92 to 18.0 indicated serious air pollution in Beijing, and strong negative correlation in winter reflected strong O3 consumption by NO titration and less thermal decompositin of PAN.
基金Supported by the National Key Research and Development Program of China(No.2022YFC3102200)the Guangdong Research Foundation(No.2019BT02H594)+3 种基金the National Natural Science Foundation of China(No.42076071)the Key Special Project for Introduced Talents Team of the Southern Marine Science and Engineering Guangdong Laboratory(Guangzhou)(No.GML2019ZD0204)the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDA22020303)the Key Research Program of the Chinese Academy of Sciences(No.ZDRW-XH-2021-2-02)。
文摘Submarine volcanism is widely developed in the South China Sea(SCS).However,the characteristics,distribution,and genesis of submarine volcanoes in the southern margin of the SCS remain obscure.In this study,we analyzed the characteristics of submarine volcanoes and identified a total of 43 submarine volcanoes in the southern margin of the SCS,based on a newly acquired 310-km seismic reflection profile,along with previous 45 multi-channel seismic(MCS)profiles,petrological results from volcanic rocks sampled by dredging and drilling,nearby ocean bottom seismometer(OBS)wide-angle seismic profiles,and gravity and magnetic data.The study ascertains that most of these volcanoes are located in fault-block belts and graben-horst zones with strong crustal stretching and thinning.These volcanoes exhibit positive high-amplitude external seismic reflections,weak and chaotic internal seismic reflections,and are accompanied by local deformation of the surrounding sedimentary strata.Meanwhile,they have higher positive gravity anomalies and higher magnetic anomalies than the background strata.The petrological dating results show that volcanic ages are primarily in the Pliocene-Pleistocene,with geochemical characteristics indicating dominance of oceanic island basalt(OIB)-type alkali-basalts.Extensional faults have obviously spatial correspondence with post-spreading volcanism,suggesting these faults may provide conduits for submarine volcanism.The high-velocity bodies(HVBs)in the lower crust and magma underplating exist in the southern SCS,which could provide a clue of genesis for submarine volcanism.The inference is that the intensity of post-spreading volcanism in the southern margin might be affected by stretching faults,crustal thinning and magma underplating.
基金supported by National Key R&D Program of China(No.2016YFF0201101)the National Natural Science Foundation of China(Nos.91544211,41727805,41305124,and 21976106)+2 种基金the Opening Project of Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention(Nos.FDLAP18005 and 19006)the supports from the Co-Innovation Center for Green Building of Shandong Province(No.X18027Z)the Introduction and Cultivation Plan for Young Innovative Talents of Colleges and Universities by the Education Department of Shandong Province(No.142,2019)
文摘Atmospheric carbonyls were measured at a typical rural area of the North China Plain(NCP)from November 13 to December 24,2017 to investigate the pollution characteristics,sources and environmental implications.Fifteen carbonyls were detected,and formaldehyde,acetaldehyde and acetone accounted for about 81% at most.The concentration of the total carbonyls in heavily polluted days was twice more than that in clean days.In contrast to other carbonyls,m-tolualdehyde exhibited relatively high concentrations in the clean days in comparison with the polluted days.The ratios of three principal carbonyls to CO showed similar daily variations at different pollution levels with significant daytime peaks.Multiple linear regression analysis revealed that the contributions of background,primary and secondary sources to three principal carbonyls showed similar variation trends from the clean level to the heavily polluted level.The OH formation rate of formaldehyde showed a similar variation trend to its photodegradation rate,reaching the peak value at noon,which is important to maintain relatively high OH levels to initiate the oxidation of various gas-phase pollutants for secondary pollutant formation at the rural site.OH radical consumption rate and ozone formation potential(OFP) calculations showed that formaldehyde and acetaldehyde were the dominant oxidative species among measured carbonyls.As for OH radical consumption,n-butyraldehyde and m-tolualdehyde were important contributors,while for ozone formation potential,n-butyraldehyde and propionaldehyde made significant contributions.In addition,the contribution of carbonyl compounds to secondary organic aerosol(SOA) formation was also important and needs further investigation.
基金supported by projects of the National Key Research and Development of China (No. 2017YFC0209700)the National Natural Science Foundation of China (Nos. 41575121, 91544211, 41727805, 21477142)
文摘The efficient maintenance of the activity of excised branches is the powerful guarantee to accurately determine gas exchange flux between the detached branches of tall trees and the atmosphere. In this study, the net photosynthetic rate(NPR) of the excised branches and branches in situ were measured simultaneously by using two photosynthetic instruments to characterize the activity of the excised branches of Phyllostachys nigra. The ratio of normalized NPR of excised branches to NPR in situ was used to assess the photosynthetic activity of detached branches. Based on photosynthetic activity, an optimal hydroponics protocol for maintaining activity of excised P. nigra branches was presented:1/8 times the concentration of Gamborg B5 vitamin mixture with p H = 6. Under the best cultivation protocol, photosynthetic activity of excised P. nigra branches could be maintained more than 90% within 6 hr in the light intensity range of 200–2000 μmol/(m2·sec) and temperature range of 13.4–28.7°C. The nitrogen dioxide(NO2) flux differences between in situ and in vitro branches and the atmosphere were compared using double dynamic chambers.Based on the maintenance method of excised branches, the NO2 exchange flux between the excised P. nigra branches and the atmosphere(from-1.01 to-2.72 nmol/(m2·sec) was basically consistent with between the branches in situ and the atmosphere(from-1.12 to-3.16 nmol/(m2 sec)) within 6 hr. Therefore, this study provided a feasible protocol for in vitro measurement of gas exchange between tall trees and the atmosphere for a period of time.
基金financially supported by the National Natural Science Foundation of China (No. 21177140)the Strategic Priority Research Program of the Chinese Academy of Sciences (No. XDB05010100)the National Basic Research and the Development Program 973 (No. 2010CB732304)
文摘Atmospheric mixing ratios of carbonyl sulfide（COS） in Beijing were intensively measured from March 2011 to June 2013. COS mixing ratios exhibited distinct seasonal variation, with a maximum average value of 849 ± 477 pptv in winter and a minimal value of 372 ± 115 pptv in summer. The seasonal variation of COS was mainly ascribed to the combined effects of vegetation uptake and anthropogenic emissions. Two types of significant linear correlations（R2〉 0.66） were found between COS and CO during the periods from May to June and from October to March, with slopes（ΔCOS/ΔCO） of 0.72 and 0.14 pptv/ppbv, respectively. Based on the emission ratios of COS/CO from various sources, the dominant anthropogenic sources of COS in Beijing were found to be vehicle tire wear in summer and coal burning in winter. The total anthropogenic emission of COS in Beijing was roughly estimated as 0.53 ± 0.02 Gg/year based on the local CO emission inventory and the ΔCOS/ΔCO ratios.
基金supported by the National Natural Science Foundation of China (Nos. 21876186, 41727805, 41975164)the National Research Program of Key Issues in Air Pollution Control (Nos. DQGG0206, DQGG0103, DQGG0209)。
文摘Carbonaceous aerosols(CA) are crucial components in the atmospheric PM_(2.5) and derived from diverse sources. One of the major sources for CA is from the incomplete combustion of bituminous coal that has been prevailingly used by household stoves in rural areas for heating during winter. To efficiently eliminate the CA emission, a new household stove(NHS) was developed based on a novel combustion technology and CA emissions from the NHS and a traditional household stove(THS) were comparably investigated under the actual stove operation conditions in a farmer’s house. Compared with the THS, the emission factors of organic carbon(OC), elemental carbon(EC), and water-soluble organic carbon(WSOC) from the NHS were reduced by 96%±1%, 98%±1%, and 91%±1% under the flaming process and 95%±1%, 96%±2%, and 83%±4% under the smoldering process, respectively. Additionally,the mass absorption efficiency of WSOC from the NHS reduced by 3 folds and the radiative forcing by WSOC relative to EC shrank remarkably by a factor of 3-8. Based on the reduction of emissions and light absorption of WSOC, the promotion of the NHS offers a possible solution to achieve the clean combustion of residential solid fuel.
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences (No. XDB05010100)the National Basic Research and the Development Program 973 (No. 2010CB732304)+1 种基金the National Natural Science Foundation of China (No. 21177140, 41203070)the China Postdoctoral Science Foundation (No. 2012M520404)
文摘Atmospheric BTEX compounds（benzene, toluene, ethylbenzene and xylenes） in a rural site of the North China Plain（NCP） were preliminarily investigated in winter, and the outdoor concentrations（25.8–236.0 μg/m^3） were found to be much higher than those reported in urban regions. The pollution of BTEX inside a farmer＇s house was even more serious, with combined concentrations of 254.5–1552.9 μg/m^3. Based on the ratio of benzene to toluene（1.17 ± 0.34） measured, the serious BTEX pollution in the rural site was mainly ascribed to domestic coal combustion for heating during the winter season. With the enhancement of farmers＇ incomes in recent years, coal consumption by farmers in the NCP is rapidly increasing to keep their houses warm, and hence the serious air pollution in rural areas of the NCP during winter, including BTEX, should be paid great attention.
基金supported by projects of the National Key Research and Development of China (No. 2017YFC0209700, 2016YFC0202202)the National Natural Science Foundation of China (No. 41575121, 91544211, 41727805, 21477142)
文摘Nitrogen dioxide(NO2)is an important substance in atmospheric photochemical processes and can also be absorbed by plants.N02 fluxes between the atmosphere and P.nigrc seedlings were investigated by a double dynamic chambers method in Beijing from June 15to September 3,2017.The range of N02 exchange fluxes between P.nigra seedlings and the atmosphere was from-14.6 to 0.8 nmol/(m2.sec)(the positive data represent N02 emissior from trees,while the negative values indicate absorption).Under ambient concentrations the mean NO2 flux during the fast-growing stage(Jun.15-Aug.4)was-3.0 nmol/(m2·sec)greater than the flux of-1.5 nmol/(m2-sec)during the later growth stage(Aug.8-Sept.3)The daily exchange fluxes of NO2 obviously fluctuated.The fluxes were largest in the morning and decreased gradually over time.Additionally,the N02 fluxes were larger undei high light intensities than under low light intensities during the whole growth period.The effects of temperature on N02 fluxes were different under two growth periods.The NO2exchange fluxes were larger in a range of temperatures close to 44℃in the fast-growing stage,whereas there were no evident differences in N02 exchange fluxes under widel differing temperatures in the later growth stage.Under polluted conditions,the uptake ability of N02 was weakened.Additionally,the compensation point of N02 was 5.6 ppb ir the fast-growing stage,whereas it was 1.4 ppb in the later growth stage.The depositior velocities of NO2 were between 0.3 and 2.4 mm/sec.
