Xiamen, located on the southeastern coastal line of China, is undergoing rapid urbanization and industrialization, so its air quality has a trend of degradation. However, studies on level, temporal and spatial changes...Xiamen, located on the southeastern coastal line of China, is undergoing rapid urbanization and industrialization, so its air quality has a trend of degradation. However, studies on level, temporal and spatial changes of fine particles （PM2.5） and their carbonaceous fractions are scarce. In this article, abundance, sources, seasonal and spatial variations, distribution of organic carbon （OC） and elemental carbon （EC） in PM2.5, were studied at suburban, urban and industrial sites in Xiamen during four season-representative months in 2009-2010. PM2.5 samples were collected with middle volume sampler and were analyzed for OC and EC with thermal optical transmittance （TOT） method. Results showed that the annual average PM2.5 concentrations were 63.88-74.80 Ixg/m3 at three sites. While OC and EC concentrations were in the range of 15.81-19.73 [xg/m3 and 2.74-3.49 ~tg/m3, respectively, and clearly presented the summer minima and winter maxima in this study. The carbonaceous aerosol accounted for 42.8%-47.3% of the mass of PMzs. The annual average of secondary organic carbon （SOC） concentrations in Xiamen were 9.23-11.36 ~g/m3, accounting for approximately 56% of OC. Strong correlations between OC and EC was found in spring （R2 = 0.50） and autumn （R2 = 0.73）, suggesting that there were similar emission and transport processes for carbonaceous aerosols in these two seasons, while weak correlations were found in summer （R2 = 0.33） and winter （R2 = 0.41）. The OCI＇EC ratios in PM2.5 varied from 2.1 to 8.7 with an annual average of 5.7, indicating that vehicle exhaust, coal smoke and biomass burning were main source apportionments of carbonaceous fractions in Xiamen.展开更多
A continuous air and precipitation sampling for carbonaceous particles was conducted in a field observatory beside Nam Co, Central Tibetan Plateau during July of 2006 through January of 2007. Organic carbon （OC） was...A continuous air and precipitation sampling for carbonaceous particles was conducted in a field observatory beside Nam Co, Central Tibetan Plateau during July of 2006 through January of 2007. Organic carbon （OC） was the dominant composition of the carbonaceous particles both in the atmosphere （1660 ng/m ^3 ） and precipitation （476 ng/g） in this area, while the average elemental carbon （BC） concentrations in the atmosphere and precipitation were only 82 ng/m 3 and 8 ng/g, respectively. Very high OC/BC ratio suggested local secondary organic carbon could be a dominant contribution to OC over the Nam Co region, while BC could be mainly originated from Southern Asia, as indicated by trajectory analysis and aerosol optical depth. Comparison between the BC concentrations measured in Lhasa, those at ＂Nepal Climate Observatory at Pyramid （NCO-P）＂ site on the southern slope of the Himalayas, and Nam Co suggested BC in the Nam Co region reflected a background with weak anthropogenic disturbances and the emissions from Lhasa might have little impact on the atmospheric environment here, while the pollutants from the Indo-Gangetic Basin of Southern Asia could be transported to the Nam Co region by both the summer monsoon and the westerly.展开更多
Characteristics of atmospheric carbonaceous aerosols in Lanzhou City from December 2014 to November 2015 are analyzed using a multiwavelength thermal/optical carbon analyzer. Results reveal that average concentrations...Characteristics of atmospheric carbonaceous aerosols in Lanzhou City from December 2014 to November 2015 are analyzed using a multiwavelength thermal/optical carbon analyzer. Results reveal that average concentrations of black carbon (BC) and organic carbon in atmospheric aerosols at Lanzhou are 6.7 and 25.4 μg m^(-3), respectively, showing obvious seasonality (higher in winter and lower in summer). This is consistent with findings in cities of northern China. Primary organic aerosols and secondary organic aerosols respectively account for approximately 60% and 17% of carbonaceous aerosols. No significant seasonality is found for secondary organic carbon, indicating that its potential sources do not vary significantly throughout the study period. The mass absorption cross-section (MAC_(632nm)) of BC is 7.1 m^2g^(-1), slightly higher than that of immediately emitted BC. MAC values of BC at different wavelengths vary drastically; they are higher for ultraviolet and visible light (8.5–10.2 m^2g^(-1)) than for near-infrared light (4.9–5.7 m^2g^(-1)). The aerosol absorption optical depth generally declines from the near-infrared to the near-ultraviolet region. The values are higher in winter than in summer, thus showing there are different contributions of BC deposition in different seasons. Brown carbon (BrC) has an ?ngstr?m absorption exponent (AAE) value of approximately 2.75, which is similar to the AAE value of BrC generated by diesel combustion (2.3). The contribution of BrC to light absorption is as much as 34% at a wavelength of 635 nm. This study demonstrates that the multiwavelength thermal/optical carbon analyzer can quantify absorption properties of BrC in atmospheric aerosols. This can enhance understanding of carbonaceous aerosols and provide key parameters for simulations of climate models.展开更多
A water cyclone,developed to collect and preserve biological aerosols in a small liquid flow,was interfaced with a total organic carbon analyzer to measure the aerosol organic and inorganic carbon fractions.The total ...A water cyclone,developed to collect and preserve biological aerosols in a small liquid flow,was interfaced with a total organic carbon analyzer to measure the aerosol organic and inorganic carbon fractions.The total carbon was compared against parallel measurements of elemental carbon (EC) and organic carbon (OC) using a Sunset Real Time ECOC Analyzer between 12-29 January 2009.A National Institute for Occupational Safety and Health (NIOSH) like protocol for the measurements included four temperature steps ending at 840 ℃ for OC under a helium atmosphere followed by two temperature steps ramped to 850 ℃ for EC in a helium-oxygen atmosphere,Carbon data comparison between the water cyclone-TOC and the TOC measured by the analyzer indicated good agreement (r2 =0.82,linear regression slope =0.98,p < 0.001).Analyses of the relationship between total water organic carbon and OC,investigated using data sets from case studies spanning two different events,suggested it was possible to distinguish between the primary and secondary sources.展开更多
基金supported by the Knowledge Innovation Program of the Chinese Academy of Sciences (No. KZCX2-YW-453,KZCX2-YW-JS404,KZCX2-EW-408)the Commonweal Program of Environment Protection Department of China (No. 201009004)the Program of Bureau of Science and Technology,Xiamen (No. 3502Z20081117,350205Z20095001)
文摘Xiamen, located on the southeastern coastal line of China, is undergoing rapid urbanization and industrialization, so its air quality has a trend of degradation. However, studies on level, temporal and spatial changes of fine particles （PM2.5） and their carbonaceous fractions are scarce. In this article, abundance, sources, seasonal and spatial variations, distribution of organic carbon （OC） and elemental carbon （EC） in PM2.5, were studied at suburban, urban and industrial sites in Xiamen during four season-representative months in 2009-2010. PM2.5 samples were collected with middle volume sampler and were analyzed for OC and EC with thermal optical transmittance （TOT） method. Results showed that the annual average PM2.5 concentrations were 63.88-74.80 Ixg/m3 at three sites. While OC and EC concentrations were in the range of 15.81-19.73 [xg/m3 and 2.74-3.49 ~tg/m3, respectively, and clearly presented the summer minima and winter maxima in this study. The carbonaceous aerosol accounted for 42.8%-47.3% of the mass of PMzs. The annual average of secondary organic carbon （SOC） concentrations in Xiamen were 9.23-11.36 ~g/m3, accounting for approximately 56% of OC. Strong correlations between OC and EC was found in spring （R2 = 0.50） and autumn （R2 = 0.73）, suggesting that there were similar emission and transport processes for carbonaceous aerosols in these two seasons, while weak correlations were found in summer （R2 = 0.33） and winter （R2 = 0.41）. The OCI＇EC ratios in PM2.5 varied from 2.1 to 8.7 with an annual average of 5.7, indicating that vehicle exhaust, coal smoke and biomass burning were main source apportionments of carbonaceous fractions in Xiamen.
基金supported by National Basic Research Program(973) of China(No.2007CB411503)the National Natural Science Foundation of China(No.40901046)+1 种基金the State Key Laboratory of Cryospheric Sciences,and Chinese Academy of Sciences(No.SKLCS-ZZ-2008-01,SKLCS08-08)the China Meteorological Administration(No.CCSF2006-3)
文摘A continuous air and precipitation sampling for carbonaceous particles was conducted in a field observatory beside Nam Co, Central Tibetan Plateau during July of 2006 through January of 2007. Organic carbon （OC） was the dominant composition of the carbonaceous particles both in the atmosphere （1660 ng/m ^3 ） and precipitation （476 ng/g） in this area, while the average elemental carbon （BC） concentrations in the atmosphere and precipitation were only 82 ng/m 3 and 8 ng/g, respectively. Very high OC/BC ratio suggested local secondary organic carbon could be a dominant contribution to OC over the Nam Co region, while BC could be mainly originated from Southern Asia, as indicated by trajectory analysis and aerosol optical depth. Comparison between the BC concentrations measured in Lhasa, those at ＂Nepal Climate Observatory at Pyramid （NCO-P）＂ site on the southern slope of the Himalayas, and Nam Co suggested BC in the Nam Co region reflected a background with weak anthropogenic disturbances and the emissions from Lhasa might have little impact on the atmospheric environment here, while the pollutants from the Indo-Gangetic Basin of Southern Asia could be transported to the Nam Co region by both the summer monsoon and the westerly.
基金supported by the National Natural Science Foundation of China (Grant Nos. 41671067, 41630754)the Key Research Program of Frontier Sciences CAS (Grant No. QYZDJSSW-DQC039)+1 种基金the State Key Laboratory of Cryospheric Sciences, Chinese Academy of Sciences (Grant No. SKLCS-ZZ-2018)the Youth Talents Project of Northwest Institute of Environmental Resources, Chinese Academy of Sciences, China Scholarship Council Project
文摘Characteristics of atmospheric carbonaceous aerosols in Lanzhou City from December 2014 to November 2015 are analyzed using a multiwavelength thermal/optical carbon analyzer. Results reveal that average concentrations of black carbon (BC) and organic carbon in atmospheric aerosols at Lanzhou are 6.7 and 25.4 μg m^(-3), respectively, showing obvious seasonality (higher in winter and lower in summer). This is consistent with findings in cities of northern China. Primary organic aerosols and secondary organic aerosols respectively account for approximately 60% and 17% of carbonaceous aerosols. No significant seasonality is found for secondary organic carbon, indicating that its potential sources do not vary significantly throughout the study period. The mass absorption cross-section (MAC_(632nm)) of BC is 7.1 m^2g^(-1), slightly higher than that of immediately emitted BC. MAC values of BC at different wavelengths vary drastically; they are higher for ultraviolet and visible light (8.5–10.2 m^2g^(-1)) than for near-infrared light (4.9–5.7 m^2g^(-1)). The aerosol absorption optical depth generally declines from the near-infrared to the near-ultraviolet region. The values are higher in winter than in summer, thus showing there are different contributions of BC deposition in different seasons. Brown carbon (BrC) has an ?ngstr?m absorption exponent (AAE) value of approximately 2.75, which is similar to the AAE value of BrC generated by diesel combustion (2.3). The contribution of BrC to light absorption is as much as 34% at a wavelength of 635 nm. This study demonstrates that the multiwavelength thermal/optical carbon analyzer can quantify absorption properties of BrC in atmospheric aerosols. This can enhance understanding of carbonaceous aerosols and provide key parameters for simulations of climate models.
文摘A water cyclone,developed to collect and preserve biological aerosols in a small liquid flow,was interfaced with a total organic carbon analyzer to measure the aerosol organic and inorganic carbon fractions.The total carbon was compared against parallel measurements of elemental carbon (EC) and organic carbon (OC) using a Sunset Real Time ECOC Analyzer between 12-29 January 2009.A National Institute for Occupational Safety and Health (NIOSH) like protocol for the measurements included four temperature steps ending at 840 ℃ for OC under a helium atmosphere followed by two temperature steps ramped to 850 ℃ for EC in a helium-oxygen atmosphere,Carbon data comparison between the water cyclone-TOC and the TOC measured by the analyzer indicated good agreement (r2 =0.82,linear regression slope =0.98,p < 0.001).Analyses of the relationship between total water organic carbon and OC,investigated using data sets from case studies spanning two different events,suggested it was possible to distinguish between the primary and secondary sources.
