Black carbon （BC） is a component of fine particulate matter （PM2.5）, associated with climate, weather, air quality, and people＇s health. However, studies on temporal variation of atmospheric BC concentration at b...Black carbon （BC） is a component of fine particulate matter （PM2.5）, associated with climate, weather, air quality, and people＇s health. However, studies on temporal variation of atmospheric BC concentration at background stations in China and its source area identification are lacking. In this paper, we use 2-yr BC observations from two background stations, Lin＇an （LAN） and Longfengshan （LFS）, to perform the investigation. The results show that the mean diurnal variation of BC has two significant peaks at LAN while different characteristics are found in the BC vari- ation at LFS, which are probably caused by the difference in emission source contributions. Seasonal variation of monthly BC shows double peaks at LAN but a single peak at LFS. The annual mean concentrations of BC at LAN and LFS decrease by 1.63 and 0.26 μg m 3 from 2009 to 2010, respectively. The annual background concentration of BC at LAN is twice higher than that at LFS. The major source of the LAN BC is industrial emission while the source of the LFS BC is residential emission. Based on transport climatology on a 7-day timescale, LAN and LFS stations are sensitive to surface emissions respectively in belt or approximately circular area, which are dominated by summer monsoon or colder land air flows in Northwest China. In addition, we statistically analyze the BC source regions by using BC observation and FLEXible PARTicle dispersion model （FLEXPART） simulation. In summer, the source regions of BC are distributed in the northwest and south of LAN and the southwest of LFS. Low BC concentration is closely related to air mass from the sea. In winter, the source regions of BC are concentrated in the west and south of LAN and the northeast of the threshold area of stot at LFS. The cold air mass in the northwest plays an important role in the purification of atmospheric BC. On a yearly scale, sources of BC are approximately from five provinces in the northwest/southeast of LAN and the west of LFS. These findings are helpful in reducing BC emission and con- trolling air pollution.展开更多
Any accurate simulation of regional air quality by numerical models entails accurate and up-to-date emissions data for that region.The INTEX-B2006 （I06）,one of the newest emission inventories recently popularly used...Any accurate simulation of regional air quality by numerical models entails accurate and up-to-date emissions data for that region.The INTEX-B2006 （I06）,one of the newest emission inventories recently popularly used in China and East Asia,has been assessed using the Community Multiscale Air Quality model and observations from regional atmospheric background stations of China.Comparisons of the model results with the observations for the species SO2,NO 2,O 3 and CO from the three regional atmospheric background stations of Shangdianzi,Longfengshan and Linan show that the model can basically capture the temporal characteristics of observations such as the monthly,seasonal and diurnal variance trends.Compared to the other three species,the simulated CO values were grossly underestimated by about two-third or one-half of the observed values,related to the uncertainty in CO emissions.Compared to the other two stations,Shangdianzi had poorer simulations,especially for SO2 and CO,which partly resulted from the site location close to local emission sources from the Beijing area;and the regional inventory used was not capable of capturing the influencing factors of strong regional sources on stations.Generally,the fact that summer gave poor simulation,especially for SO2 and O 3,might partly relate to poor simulations of meteorological fields such as temperature and wind.展开更多
Lorentz curve fittings are applied to frequency distributions of the concentrations of O 3 , CO, NO x and SO 2 recorded at the Jinsha regional atmospheric background station (JSH) from June 2006 to July 2007, and the ...Lorentz curve fittings are applied to frequency distributions of the concentrations of O 3 , CO, NO x and SO 2 recorded at the Jinsha regional atmospheric background station (JSH) from June 2006 to July 2007, and the peak concentrations of these species for the different seasons are obtained. The peak concentrations are considered to be representative of different background levels for certain processes. The peak concentrations are compared with the corresponding mean (median) concentrations, and the suitability and limitations of the mean (median) values as the background levels are discussed. The mean (median) values might represent the background concentrations in the region under some circumstances, but in other cases these values often underestimate or overestimate the true background concentrations owing to the transport of pollutants and other factors. The effects of air masses transported from different regions on the pollutant background concentrations are obtained by analyzing the 72-hour backward trajectories of air masses 100 m above the ground at JSH. These trajectories are estimated using the HYSPLIT model and then clustered for the measurement period. The spatial distribution and seasonal variations of trajectories and the corresponding mean concentrations of O 3 , SO 2 , NO x and CO for different clusters are analyzed. After filtering the seasonal changes in pollutant concentrations, the relative influences of air masses from different regions are obtained. The results show that JSH can be used to obtain the atmospheric background information of different air masses originating from or passing over the Yangtze River Delta, Central South China and the Jianghan Plain. Air masses from Central China, South China, and the western Yangtze River Delta contribute significantly to O 3 at JSH. Air masses from the north and northeast of JSH (i.e., the Jianghan Plain, Huang-Huai Plain and North China Plain) and the south (Central South China) contribute significantly to SO 2 , CO and NO x concentrations. Air masses originating from the ocean often bring clean air. Air masses originating from high altitudes over northwestern regions often have lower CO and NO x concentrations, lower relative humidity, and higher concentrations of O 3 and SO 2 .展开更多
Ground-basedMulti-AXis Differential Optical Absorption Spectroscopy(MAX-DOAS)measurements were performed at Shangdianzi(SDZ)regional atmospheric background station in northern China from March 2009 to February 2011.Th...Ground-basedMulti-AXis Differential Optical Absorption Spectroscopy(MAX-DOAS)measurements were performed at Shangdianzi(SDZ)regional atmospheric background station in northern China from March 2009 to February 2011.The tropospheric NO_2vertical column densities(VCDs)were retrieved to investigate the background condition of the Beijing–Tianjin–Hebei developed economic circle in China.The seasonal variation of mean NO_2tropospheric VCDs(VCD_(Trop))at SDZ is apparent,with the maximum(1.3×10^(16)molec/cm^2)in February and the minimum(3.5×10^(15)molec/cm^2)in August,much lower than those observed at the Beijing city center.The average daytime diurnal variations of NO_2VCD_(Trop )are rather consistent for all four seasons,presenting the minimum at noon and the higher values in the morning and evening.The largest and lowest amplitudes of NO_2VCD_(Trop)diurnal variation appear in winter and in summer,respectively.The diurnal pattern at SDZ station is similar to those at other less polluted stations,but distinct from the ones at the urban or polluted stations.Tropospheric NO_2VCDs at SDZ are strongly dependent on the wind,with the higher values being associated with the pollution plumes from Beijing city.Tropospheric NO_2VCDs derived from ground-based MAX-DOAS at SDZ show to be well correlated with corresponding OMI(Ozone Monitoring Instrument)satellite products with a correlation coefficient R=0.88.However,the OMI observations are on average higher than MAX-DOAS NO_2VCDs by a factor of 28%,probably due to the OMI grid cell partly covering the south of SDZ which is influenced more by the pollution plumes from the urban areas.展开更多
The comprehensive impact of atmospheric dry deposition and wet deposition and the pollution sources of farmlands, mining areas, and towns along the Baihe River on the water quality of Miyun reservoir is investigated f...The comprehensive impact of atmospheric dry deposition and wet deposition and the pollution sources of farmlands, mining areas, and towns along the Baihe River on the water quality of Miyun reservoir is investigated from the angle of the complex sources of air-soil-water pollution processes, in the context of the 1990-2001 precipitation chemical data at Shangdianzi station--a WMO regional background air pollution monitoring station 15 km far from the Miyun reservoir, in conjunction with the atmospheric dry deposition and wet deposition data of the 2002-2003 Beijing City Air Pollution Observation Field Experiment (BECAPEX). Analysis results suggest that the major ions in precipitation in the Miyun reservoir region in this period were SO, NO, NH and Ca2+; wet acid deposition quantity of Miyun reservoir in the summer half year (April to September) was greater than the quantity in the winter half year (October to March), and the annual wet acid deposition in the reservoir exhibited a rising trend with the mean 1038.45 t, the maximum 1766.31 t occurred in 1996, and the minimum 604.02 t in 1994; the long-term averaged pH of atmospheric precipitation in the Miyun reservoir region was 5.20, i.e. weakly acidic, and the interannual variation of pH values displayed a falling trend. pH values of water body at various depths in the Miyun reservoir were all greater than 7.0, but they exhibited vertical and horizontal nonhomogeneity, and at the same region pH decreased vertically with depth; the 2002 and 2003 annual dustfalls in the Miyun reservoir were 13513.08 t and 3577.64 t, respectively, and the spring dustfall was the number one in a year, accounting for the 61.91% and 44.56% of the annual totals of 2002 and 2003, respectively. Because the atmospheric dry deposition and wet depositions contain multiple types heavy metal elements and harmful elements, they to some extent exacerbated the eutrophication, acidification and potential heavy metal pollution of the reservoir water. The above comprehensive analysis results reveal the complex source characters of the air-soil-water pollution process and the multi-sphere interaction effect. Besides, summer (rainy season) is a season when local soil pollutants enter the water system of reservoir after being washed out by torrential rain or heavy precipitation, which starts the air-soil- water chaining pollution processes, and results in the water pollution of rivers and reservoirs. It is found from the statistical analysis in this paper that the water pollution of Miyun reservoir was correlated with the rain wash-out and confluent flow in the peripheral and upstream local region of the reservoir, and the pollutant concentration of the reservoir water was significantly correlated with the upstream local region precipitation. Those correlation characters reveal the effect of the air-soil-water multi-spheric interaction of reservoir water pollution process. This paper presents the point of view of the complex source analysis of reservoir water pollution and a technical approach for tracing the spatial distribution of the upstream pollution source of the water systems of reservoir.展开更多
基金Supported by the International Cooperation Program of Ministry of Science&Technology of China(2015DFG21960)National Natural Science Foundation of China(41505123 and 41275167)+1 种基金Fundamental Research Fund of Chinese Academy of Meteorological Sciences(2015Y002)National(Key)Basic Research and Development(973)Program of China(2014CB441201)
文摘Black carbon （BC） is a component of fine particulate matter （PM2.5）, associated with climate, weather, air quality, and people＇s health. However, studies on temporal variation of atmospheric BC concentration at background stations in China and its source area identification are lacking. In this paper, we use 2-yr BC observations from two background stations, Lin＇an （LAN） and Longfengshan （LFS）, to perform the investigation. The results show that the mean diurnal variation of BC has two significant peaks at LAN while different characteristics are found in the BC vari- ation at LFS, which are probably caused by the difference in emission source contributions. Seasonal variation of monthly BC shows double peaks at LAN but a single peak at LFS. The annual mean concentrations of BC at LAN and LFS decrease by 1.63 and 0.26 μg m 3 from 2009 to 2010, respectively. The annual background concentration of BC at LAN is twice higher than that at LFS. The major source of the LAN BC is industrial emission while the source of the LFS BC is residential emission. Based on transport climatology on a 7-day timescale, LAN and LFS stations are sensitive to surface emissions respectively in belt or approximately circular area, which are dominated by summer monsoon or colder land air flows in Northwest China. In addition, we statistically analyze the BC source regions by using BC observation and FLEXible PARTicle dispersion model （FLEXPART） simulation. In summer, the source regions of BC are distributed in the northwest and south of LAN and the southwest of LFS. Low BC concentration is closely related to air mass from the sea. In winter, the source regions of BC are concentrated in the west and south of LAN and the northeast of the threshold area of stot at LFS. The cold air mass in the northwest plays an important role in the purification of atmospheric BC. On a yearly scale, sources of BC are approximately from five provinces in the northwest/southeast of LAN and the west of LFS. These findings are helpful in reducing BC emission and con- trolling air pollution.
基金supported by the Chinese Ministry of Science and Technology(No.2011CB403404)the CAMS Basic Research Funds-regular(No.2010Y005)+1 种基金the Specific Team Fund of CAMS(No.2010Z002)the National Natural Science Foundation of China(No.40875086)
文摘Any accurate simulation of regional air quality by numerical models entails accurate and up-to-date emissions data for that region.The INTEX-B2006 （I06）,one of the newest emission inventories recently popularly used in China and East Asia,has been assessed using the Community Multiscale Air Quality model and observations from regional atmospheric background stations of China.Comparisons of the model results with the observations for the species SO2,NO 2,O 3 and CO from the three regional atmospheric background stations of Shangdianzi,Longfengshan and Linan show that the model can basically capture the temporal characteristics of observations such as the monthly,seasonal and diurnal variance trends.Compared to the other three species,the simulated CO values were grossly underestimated by about two-third or one-half of the observed values,related to the uncertainty in CO emissions.Compared to the other two stations,Shangdianzi had poorer simulations,especially for SO2 and CO,which partly resulted from the site location close to local emission sources from the Beijing area;and the regional inventory used was not capable of capturing the influencing factors of strong regional sources on stations.Generally,the fact that summer gave poor simulation,especially for SO2 and O 3,might partly relate to poor simulations of meteorological fields such as temperature and wind.
基金supported by National Basic Research Program of China (Grant No. 2005CB4222002)Project of China Meteorological Administration (Grant No. GYHY[QX]200706005)National Natural Science Foundation of China (Grant No. 40705042)
文摘Lorentz curve fittings are applied to frequency distributions of the concentrations of O 3 , CO, NO x and SO 2 recorded at the Jinsha regional atmospheric background station (JSH) from June 2006 to July 2007, and the peak concentrations of these species for the different seasons are obtained. The peak concentrations are considered to be representative of different background levels for certain processes. The peak concentrations are compared with the corresponding mean (median) concentrations, and the suitability and limitations of the mean (median) values as the background levels are discussed. The mean (median) values might represent the background concentrations in the region under some circumstances, but in other cases these values often underestimate or overestimate the true background concentrations owing to the transport of pollutants and other factors. The effects of air masses transported from different regions on the pollutant background concentrations are obtained by analyzing the 72-hour backward trajectories of air masses 100 m above the ground at JSH. These trajectories are estimated using the HYSPLIT model and then clustered for the measurement period. The spatial distribution and seasonal variations of trajectories and the corresponding mean concentrations of O 3 , SO 2 , NO x and CO for different clusters are analyzed. After filtering the seasonal changes in pollutant concentrations, the relative influences of air masses from different regions are obtained. The results show that JSH can be used to obtain the atmospheric background information of different air masses originating from or passing over the Yangtze River Delta, Central South China and the Jianghan Plain. Air masses from Central China, South China, and the western Yangtze River Delta contribute significantly to O 3 at JSH. Air masses from the north and northeast of JSH (i.e., the Jianghan Plain, Huang-Huai Plain and North China Plain) and the south (Central South China) contribute significantly to SO 2 , CO and NO x concentrations. Air masses originating from the ocean often bring clean air. Air masses originating from high altitudes over northwestern regions often have lower CO and NO x concentrations, lower relative humidity, and higher concentrations of O 3 and SO 2 .
基金supported by the National Natural Science Foundation of China (Nos. 41505123, 41330422, 41075095)the CAMS Development Funds of Science and Technology (Nos. 2018KJ001, 2018KJ002)
文摘Ground-basedMulti-AXis Differential Optical Absorption Spectroscopy(MAX-DOAS)measurements were performed at Shangdianzi(SDZ)regional atmospheric background station in northern China from March 2009 to February 2011.The tropospheric NO_2vertical column densities(VCDs)were retrieved to investigate the background condition of the Beijing–Tianjin–Hebei developed economic circle in China.The seasonal variation of mean NO_2tropospheric VCDs(VCD_(Trop))at SDZ is apparent,with the maximum(1.3×10^(16)molec/cm^2)in February and the minimum(3.5×10^(15)molec/cm^2)in August,much lower than those observed at the Beijing city center.The average daytime diurnal variations of NO_2VCD_(Trop )are rather consistent for all four seasons,presenting the minimum at noon and the higher values in the morning and evening.The largest and lowest amplitudes of NO_2VCD_(Trop)diurnal variation appear in winter and in summer,respectively.The diurnal pattern at SDZ station is similar to those at other less polluted stations,but distinct from the ones at the urban or polluted stations.Tropospheric NO_2VCDs at SDZ are strongly dependent on the wind,with the higher values being associated with the pollution plumes from Beijing city.Tropospheric NO_2VCDs derived from ground-based MAX-DOAS at SDZ show to be well correlated with corresponding OMI(Ozone Monitoring Instrument)satellite products with a correlation coefficient R=0.88.However,the OMI observations are on average higher than MAX-DOAS NO_2VCDs by a factor of 28%,probably due to the OMI grid cell partly covering the south of SDZ which is influenced more by the pollution plumes from the urban areas.
文摘The comprehensive impact of atmospheric dry deposition and wet deposition and the pollution sources of farmlands, mining areas, and towns along the Baihe River on the water quality of Miyun reservoir is investigated from the angle of the complex sources of air-soil-water pollution processes, in the context of the 1990-2001 precipitation chemical data at Shangdianzi station--a WMO regional background air pollution monitoring station 15 km far from the Miyun reservoir, in conjunction with the atmospheric dry deposition and wet deposition data of the 2002-2003 Beijing City Air Pollution Observation Field Experiment (BECAPEX). Analysis results suggest that the major ions in precipitation in the Miyun reservoir region in this period were SO, NO, NH and Ca2+; wet acid deposition quantity of Miyun reservoir in the summer half year (April to September) was greater than the quantity in the winter half year (October to March), and the annual wet acid deposition in the reservoir exhibited a rising trend with the mean 1038.45 t, the maximum 1766.31 t occurred in 1996, and the minimum 604.02 t in 1994; the long-term averaged pH of atmospheric precipitation in the Miyun reservoir region was 5.20, i.e. weakly acidic, and the interannual variation of pH values displayed a falling trend. pH values of water body at various depths in the Miyun reservoir were all greater than 7.0, but they exhibited vertical and horizontal nonhomogeneity, and at the same region pH decreased vertically with depth; the 2002 and 2003 annual dustfalls in the Miyun reservoir were 13513.08 t and 3577.64 t, respectively, and the spring dustfall was the number one in a year, accounting for the 61.91% and 44.56% of the annual totals of 2002 and 2003, respectively. Because the atmospheric dry deposition and wet depositions contain multiple types heavy metal elements and harmful elements, they to some extent exacerbated the eutrophication, acidification and potential heavy metal pollution of the reservoir water. The above comprehensive analysis results reveal the complex source characters of the air-soil-water pollution process and the multi-sphere interaction effect. Besides, summer (rainy season) is a season when local soil pollutants enter the water system of reservoir after being washed out by torrential rain or heavy precipitation, which starts the air-soil- water chaining pollution processes, and results in the water pollution of rivers and reservoirs. It is found from the statistical analysis in this paper that the water pollution of Miyun reservoir was correlated with the rain wash-out and confluent flow in the peripheral and upstream local region of the reservoir, and the pollutant concentration of the reservoir water was significantly correlated with the upstream local region precipitation. Those correlation characters reveal the effect of the air-soil-water multi-spheric interaction of reservoir water pollution process. This paper presents the point of view of the complex source analysis of reservoir water pollution and a technical approach for tracing the spatial distribution of the upstream pollution source of the water systems of reservoir.
