汉中市秋季PM_(2.5)昼夜变化特征
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摘要
为探讨汉中市秋季PM_(2.5)昼夜变化特征。于2015年9月7日至9月17日利用中流量大气颗粒物采样仪在汉中市三个不同站点分昼夜采集PM_(2.5)滤膜样品,并分别利用热光碳分析仪(DRI—2011)和离子色谱(Dionex—600)分析PM_(2.5)中碳组分和水溶性离子组分,主要探讨PM_(2.5)及其碳组分和水溶性离子昼夜变化特征。结果显示:汉中秋季PM_(2.5)浓度低于国家空气质量一级标准;PM_(2.5)中主要化学组分包括SNA (硫酸盐、硝酸盐、铵盐)和有机类物质,白天和夜间占比分别达到32.3%、39.6%和28.9%、39.6%; PM_(2.5)颗粒物呈酸性。除SO_4~(2-)、Mg~(2+)和Ca~(2+)之外,PM_(2.5)及其化学组分均呈现夜间浓度高于白天的特征。离子的赋存形态分析表明:SO_4~(2-)更多以(NH_4~+)_2SO_4~(2-)的形式存在于PM_(2.5)中。本文相关结果可为地方环保政策的制定提供参考和基础数据。
Background, aim, and scope Fine particulate matter(PM_(2.5)) has been widely concerned by people and scientists due to its negative impacts on climate, human health and ecological environment. To better understand air pollution in China, more characteristics of PM_(2.5) chemical components should be considered in urban areas.Hanzhong(105°30.5'-108°24.6'E, 32°15.3'-33°56.6'N) is located in southwest of Shaanxi Province and has a special basin topography. The air pollution in Hanzhong has gradually become severe with economic development, but research on PM_(2.5) in Hanzhong was limited. In the present study, PM_(2.5) samples were collected at three urban sites in Hanzhong to investigate the characterizations of chemical species in PM_(2.5) during autumn.This study could provide valuable information and dataset for air pollution prevention in Hanzhong. Materials and methods PM_(2.5) samples including daytime(08:00-20:00) and night(20:00-08:00) were collected at three observation sites in Hanzhong from 7 to 17 September 2015. The samples were collected on pre-baked quartz fiber filters(QM/A, Whatman Inc., U.K.) by mid-volume samplers(TE-5030, TISCH Inc., USA).The PM2 5 mass concentrations of each sample was weighted by a microbalance(± 1 μg sensitivity,Mettle M3,Switzerland). The organic carbon(OC) and element carbon(EC) were analyzed by a Thermal/Optical Carbon Analyzer(DRI-2001) with IMPROVE_A protocol. Water-soluble inorganic ions(C1~-,NO_3~-,SO_4~(2-),Na~+,NH_4~+,K~+,Mg~(2+),Ca~(2+))were analyzed by an Ion Chromatograph(Dionex-600) using the aqueous extracts of the aerosol filters. Results The average mass concentrations of PM_(2.5) was 27.04 μg·m~(-3) in autumn, the main components in PM_(2.5) were SNA(sulfates, nitrates and ammonium, calculated by SO_4~(2-),NO_3~-and NH_4~+) and organic matter with both contribution of～30% to PM_(2.5) mass. The average concentrations of OC, EC, SO_4~(2-),NO_3~-and NH_4~+ were3.85 μg·m~(-3), 2.93 μg·m~(-3), 1.62 μg·m~(-3), 5.43μg·m~(-3), 1.67 μg·m~(-3) during daytime and 5.76 μg·m~(-3), 3.29μg·m~(-3),1.96 μg·m~(-3), 4.95μg·m~(-3), 1.75 μg·m~(-3) at night, respectively. Furthermore, the concentrations of anions followed the order of SO_4~(2-)>NO_3~->C1~-,while in cations followed the order of NH_4~+ > K~+>Ca~(2+)>Na~+>Mg~(2+). A strong correlation(R~2>0.93) was found between anions and cations for all samples, indicating that the five cations and three anions were the major ions extracted from filters. The slope(cation/anion) of linear regression during daytime and at night were 0.86 and 0.81, respectively, which indicates the aerosol particles were acidic in Hanzhong. Furthermore, OC correlated strongly with EC(R~2>0.82), which indicated similar sources for carbonaceous species. Discussion The diffusion of pollutants was difficult at night due to low atmospheric boundary layer, which led to higher PM_(2.5) loadings at night compared with the daytime. The strong correlation among SO_4~(2-), NO_3~-and NH_4~+ and the results of regression analysis indicated that main existing forms of the three ions were(NH_4)_2 SO_4, NH_4 HSO_4, NH_4 NO_3 in PM_(2.5).Further, the estimated NH_4~+ concentrations correlated well with the measured values(R~2>0.93) with a slope of 1.2 indicating that SO_4~(2-)was maily in the form of(NH_4)_2 SO_4.The well correlation between K~+ and C1~-at night(R~2>0.73) revelated that they may come from biomass burning.Conclusions The average concentration of PM_(2.5) was lower than the first level of national ambient air quality standards. The concentrations of SNA and organic matter accounted for 32.3% and 39.6% of PM_(2.5) mass during daytime, 28.9% and 39.6% abundance at night, respectively. PM_(2.5) was generally acidic. The PM_(2.5) concentration at night was higher than daytime in autumn. Recommendations and perspectives This research provides a significant scientific basis for understanding the characteristics of PM_(2.5) and its chemical components. However,for the future pollution mitigation, more researches on aerosol in Hanzhong should be conducted.
Background, aim, and scope Fine particulate matter(PM_(2.5)) has been widely concerned by people and scientists due to its negative impacts on climate, human health and ecological environment. To better understand air pollution in China, more characteristics of PM_(2.5) chemical components should be considered in urban areas.Hanzhong(105°30.5'-108°24.6'E, 32°15.3'-33°56.6'N) is located in southwest of Shaanxi Province and has a special basin topography. The air pollution in Hanzhong has gradually become severe with economic development, but research on PM_(2.5) in Hanzhong was limited. In the present study, PM_(2.5) samples were collected at three urban sites in Hanzhong to investigate the characterizations of chemical species in PM_(2.5) during autumn.This study could provide valuable information and dataset for air pollution prevention in Hanzhong. Materials and methods PM_(2.5) samples including daytime(08:00-20:00) and night(20:00-08:00) were collected at three observation sites in Hanzhong from 7 to 17 September 2015. The samples were collected on pre-baked quartz fiber filters(QM/A, Whatman Inc., U.K.) by mid-volume samplers(TE-5030, TISCH Inc., USA).The PM2 5 mass concentrations of each sample was weighted by a microbalance(± 1 μg sensitivity,Mettle M3,Switzerland). The organic carbon(OC) and element carbon(EC) were analyzed by a Thermal/Optical Carbon Analyzer(DRI-2001) with IMPROVE_A protocol. Water-soluble inorganic ions(C1~-,NO_3~-,SO_4~(2-),Na~+,NH_4~+,K~+,Mg~(2+),Ca~(2+))were analyzed by an Ion Chromatograph(Dionex-600) using the aqueous extracts of the aerosol filters. Results The average mass concentrations of PM_(2.5) was 27.04 μg·m~(-3) in autumn, the main components in PM_(2.5) were SNA(sulfates, nitrates and ammonium, calculated by SO_4~(2-),NO_3~-and NH_4~+) and organic matter with both contribution of～30% to PM_(2.5) mass. The average concentrations of OC, EC, SO_4~(2-),NO_3~-and NH_4~+ were3.85 μg·m~(-3), 2.93 μg·m~(-3), 1.62 μg·m~(-3), 5.43μg·m~(-3), 1.67 μg·m~(-3) during daytime and 5.76 μg·m~(-3), 3.29μg·m~(-3),1.96 μg·m~(-3), 4.95μg·m~(-3), 1.75 μg·m~(-3) at night, respectively. Furthermore, the concentrations of anions followed the order of SO_4~(2-)>NO_3~->C1~-,while in cations followed the order of NH_4~+ > K~+>Ca~(2+)>Na~+>Mg~(2+). A strong correlation(R~2>0.93) was found between anions and cations for all samples, indicating that the five cations and three anions were the major ions extracted from filters. The slope(cation/anion) of linear regression during daytime and at night were 0.86 and 0.81, respectively, which indicates the aerosol particles were acidic in Hanzhong. Furthermore, OC correlated strongly with EC(R~2>0.82), which indicated similar sources for carbonaceous species. Discussion The diffusion of pollutants was difficult at night due to low atmospheric boundary layer, which led to higher PM_(2.5) loadings at night compared with the daytime. The strong correlation among SO_4~(2-), NO_3~-and NH_4~+ and the results of regression analysis indicated that main existing forms of the three ions were(NH_4)_2 SO_4, NH_4 HSO_4, NH_4 NO_3 in PM_(2.5).Further, the estimated NH_4~+ concentrations correlated well with the measured values(R~2>0.93) with a slope of 1.2 indicating that SO_4~(2-)was maily in the form of(NH_4)_2 SO_4.The well correlation between K~+ and C1~-at night(R~2>0.73) revelated that they may come from biomass burning.Conclusions The average concentration of PM_(2.5) was lower than the first level of national ambient air quality standards. The concentrations of SNA and organic matter accounted for 32.3% and 39.6% of PM_(2.5) mass during daytime, 28.9% and 39.6% abundance at night, respectively. PM_(2.5) was generally acidic. The PM_(2.5) concentration at night was higher than daytime in autumn. Recommendations and perspectives This research provides a significant scientific basis for understanding the characteristics of PM_(2.5) and its chemical components. However,for the future pollution mitigation, more researches on aerosol in Hanzhong should be conducted.
引文
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王向锋,黄战胜.2016.2014年宝鸡市大气颗粒物时空分布特征分析[J].环境保护科学,42(1):100-103.[Wang X F,Huang Z S.2016.analysis of spatial-temporal distribution characteristics of PM in Baoji city in 2014[J].Environmental Protection Science,42(1):100-103.]
王英锋,张姗姗,李杏茹,等.2010.北京大气颗粒物中多环芳烃浓度季节变化及来源分析[J].环境化学,29(3):369-375.[Wang Y F,Zhang S S,Li X R,et al.2010.Seasonal variation and source identification of polycyclic aromatic hydrocarbons(PAHs)in airborne particulates of Beijing[J].Environmental Chemistry,29(3):369-375.]
卫菲菲,刘昊,陆晓波,等.2017.南京市大气细颗粒物二次组分的时空变化特征[J].中国环境科学,37(8):2866-2876.[Wei F F,Liu H,Lu X B,et al.2017.Temporal and spatial characteristics of secondary components of PM2.5 in Nanjing[J].China Environmental Science,37(8):2866-2876.]
张婷,曹军骥,刘随心.2017.宝鸡市PM2.5中水溶性离子组分污染特征及来源分析[J].地球环境学报,8(1):46-54.[Zhang T,Cao J J,Liu S X.2017.Pollution characteristics and sources of water-soluble ions in PM2.5in Baoji[J].Journal of Earth Environment,8(1):46-54.]
张婷,曹军骥,吴枫,等.2007.西安春夏季气体及PM2.5中水溶性组分的污染特征[J].中国科学院研究生院学报,24(5):641-647.[Zhang T,Cao J J,Wu F,et al.2007.Characterization of gases and water-soluble ion of PM2.5during spring and summer of 2006 in Xi’an[J].Journal of the Graduate School of the Chinese Academy of Sciences,24(5):641-647.]
张仁健,王明星,胡非,等.2002.采暖期前和采暖期北京大气颗粒物的化学成分研究[J].中国科学院研究生院学报,19(1):75-81.[Zhang R J,Wang M X,Hu F,et al.2002.Elemental concentrations and distributions of atmospheric particles before and in heating period in Beijing[J].Journal of the Graduate School of the Chinese Academy of Sciences,19(1):75-81.]
张懿华,王东方,赵倩彪,等.2014.上海城区PM2.5中有机碳和元素碳变化特征及来源分析[J].环境科学,35(9):3263-3270.[Zhang Y H,Wang D F,Zhao Q B,et al.2014.Characteristics and sources of organic carbon and elemental carbon in PM2.5 in Shanghai urban area[J].Environmental Science,35(9):3263-3270.]
Booth B B B,Dunstone N J,Halloran P R,et al.2012.Aerosols implicated as a prime driver of twentieth-century north Atlantic climate variability[J].Nature,484(7393):228-232.
Cao J J,Lee S C,Ho K F,et al.2003.Characteristics of carbonaceous aerosol in Pearl River Delta Region,China during 2001 winter period[J].Atmospheric Environment,37(11):1451-1460.
Cao J J,Xu B Q,He J Q,et al.2009a.Concentrations,seasonal variations,and transport of carbonaceous aerosols at a remote mountainous region in western China[J].Atmospheric Environment,43(29):4444-4452.
Cao J J,Zhu C S,Chow J C,et al.2009b.Black carbon relationships with emissions and meteorology in Xi’an,China[J].Atmospheric Research,94(2):194-202.
Censi P,Zuddas P,Randazzo L A,et al.2011.Source and nature of inhaled atmospheric dust from trace element analyses of human bronchial fluids[J].Environmental Science&Technology,45(15):6262-6267.
Chen J,Li C,Ristovski Z,et al.2016.A review of biomass burning:emissions and impacts on air quality,health and climate in China[J].Science of the Total Environment,579:1000-1034.
Cheng M C,You C F,Cao J J,et al.2012.Spatial and seasonal Variability of water-soluble ions in PM2.5 aerosols in 14major cities in China[J].Atmospheric Environment,60(6):182-192.
Chow J C,Watson J G,Chen L W,et al.2007.The IMPROVE_Atemperature protocol for thermal/optical carbon analysis:maintaining consistency with a long-term database[J].Journal of Air&Waste Management Association,57(9):1014-1023.
Hallquist M,Wenger J C,Baltensperger U,et al.2009.The formation,properties and impact of secondary organic aerosol:current and emerging issues[J].Atmospheric Chemistry&Physics,9(1):5155-5236.
Haywood J,Boucher O.2000.Estimates of the direct and indirect radiative forcing due to tropospheric aerosols:a review[J].Reviews of Geophysics,38:513-543.
Huang H,Zou C W,Cao J J,et al.2012.Water-soluble ions in PM2.5on the Qianhu campus of Nanchang University,Nanchang city:indoor-outdoor distribution and source implications[J].Aerosol and Air Quality Research,12(3):435-443.
Huang R J,Zhang Y,Bozzetti C,et al.2014.High secondary aerosol contribution to particulate pollution during haze events in China[J].Nature,514(7521):218-222.
Kang C,Lee H,Kang B S,et al.2004.Chemical characteristics of acidic gas pollutants and PM2.5 species during hazy episodes in Seoul,South Korea[J].Atmospheric Environment,38(28):4749-4760.
Liu J,Scheuer E,Dibb J,et al.2015.Brown carbon aerosol in the north American aontinental troposphere:sources,abundance,and radiative forcing[J].Atmospheric Chemistry&Physics,15(14):7841-7858.
Paulot F,Jacob D J,Pinder R W,et al.2014.Ammonia emissions in the United States,European Union,and China derived by high-resolution inversion of ammonium wet deposition data:interpretation with a new agricultural emissions inventory(MASAGE_NH3)[J].Journal of Geophysical Research Atmospheres,119(7):4343-4364.
Poschl U.2005.Atmospheric aerosols:composition,transformation,climate and health effects[J].Angewandte Chemie International Edition,44(46):7520-7540.
Shen Z X,Arimoto R,Cao J J,et al.2008.Seasonal variations and evidence for the effectiveness of pollution controls on water-soluble inorganic species in total suspended particulates and fine particulate matter from Xi’an,China[J].Journal of Air&Waste Management Association,58(12):1560-1570.
Watson J G,Tropp R J,Kohl S D,et al.2017.Filter processing and gravimetric analysis for suspended particulate matter samples[J].Aerosol Science&Engineering,1(2):93-105.
Wen W,Cheng S Y,Liu L,et al.2016.Source apportionment of PM2.5 in Tangshan,China-hybrid approaches for primary and secondary species apportionment[J].Frontiers of Environmental Science&Engineering,10(5):83-96.
Zhang F,Wang Z W,Cheng H R,et al.2015.Seasonal variations and chemical characteristics of PM2.5 in Wuhan,central China[J].Science of the Total Environment,518/519:97-105.
Zhang T,Cao J J,Tie X X,et al.2011.Water-soluble ions in atmospheric aerosols measured in Xi’an,China:seasonal variations and sources[J].Atmospheric Research,102(1):110-119.
刘立忠,薛梁磊,韩婧,等.2017.西安市全年中PM2.5水溶性无机离子变化特征[J].环境工程学报,11(4):2402-2406.[Liu L Z,Xue L L,Han J,et al.2017.Annual variation of water-soluble inorganic ions in PM2.5 in Xi’an[J].Chinese Journal of Environmental Engineering,11(4):2402-2406.]
谭吉华,赵金平,段菁春,等.2013.广州秋季灰霾污染过程大气颗粒物有机酸的污染特征[J].环境科学,34(5):1982-1987.[Tan J H,Zhao J P,Duan J C,et al.2013.Pollution characteristics of organic acids in atmospheric particles during haze periods in autumn in Guangzhou[J].Environmental Science,34(5):1982-1987.]
王向锋,黄战胜.2016.2014年宝鸡市大气颗粒物时空分布特征分析[J].环境保护科学,42(1):100-103.[Wang X F,Huang Z S.2016.analysis of spatial-temporal distribution characteristics of PM in Baoji city in 2014[J].Environmental Protection Science,42(1):100-103.]
王英锋,张姗姗,李杏茹,等.2010.北京大气颗粒物中多环芳烃浓度季节变化及来源分析[J].环境化学,29(3):369-375.[Wang Y F,Zhang S S,Li X R,et al.2010.Seasonal variation and source identification of polycyclic aromatic hydrocarbons(PAHs)in airborne particulates of Beijing[J].Environmental Chemistry,29(3):369-375.]
卫菲菲,刘昊,陆晓波,等.2017.南京市大气细颗粒物二次组分的时空变化特征[J].中国环境科学,37(8):2866-2876.[Wei F F,Liu H,Lu X B,et al.2017.Temporal and spatial characteristics of secondary components of PM2.5 in Nanjing[J].China Environmental Science,37(8):2866-2876.]
张婷,曹军骥,刘随心.2017.宝鸡市PM2.5中水溶性离子组分污染特征及来源分析[J].地球环境学报,8(1):46-54.[Zhang T,Cao J J,Liu S X.2017.Pollution characteristics and sources of water-soluble ions in PM2.5in Baoji[J].Journal of Earth Environment,8(1):46-54.]
张婷,曹军骥,吴枫,等.2007.西安春夏季气体及PM2.5中水溶性组分的污染特征[J].中国科学院研究生院学报,24(5):641-647.[Zhang T,Cao J J,Wu F,et al.2007.Characterization of gases and water-soluble ion of PM2.5during spring and summer of 2006 in Xi’an[J].Journal of the Graduate School of the Chinese Academy of Sciences,24(5):641-647.]
张仁健,王明星,胡非,等.2002.采暖期前和采暖期北京大气颗粒物的化学成分研究[J].中国科学院研究生院学报,19(1):75-81.[Zhang R J,Wang M X,Hu F,et al.2002.Elemental concentrations and distributions of atmospheric particles before and in heating period in Beijing[J].Journal of the Graduate School of the Chinese Academy of Sciences,19(1):75-81.]
张懿华,王东方,赵倩彪,等.2014.上海城区PM2.5中有机碳和元素碳变化特征及来源分析[J].环境科学,35(9):3263-3270.[Zhang Y H,Wang D F,Zhao Q B,et al.2014.Characteristics and sources of organic carbon and elemental carbon in PM2.5 in Shanghai urban area[J].Environmental Science,35(9):3263-3270.]
Booth B B B,Dunstone N J,Halloran P R,et al.2012.Aerosols implicated as a prime driver of twentieth-century north Atlantic climate variability[J].Nature,484(7393):228-232.
Cao J J,Lee S C,Ho K F,et al.2003.Characteristics of carbonaceous aerosol in Pearl River Delta Region,China during 2001 winter period[J].Atmospheric Environment,37(11):1451-1460.
Cao J J,Xu B Q,He J Q,et al.2009a.Concentrations,seasonal variations,and transport of carbonaceous aerosols at a remote mountainous region in western China[J].Atmospheric Environment,43(29):4444-4452.
Cao J J,Zhu C S,Chow J C,et al.2009b.Black carbon relationships with emissions and meteorology in Xi’an,China[J].Atmospheric Research,94(2):194-202.
Censi P,Zuddas P,Randazzo L A,et al.2011.Source and nature of inhaled atmospheric dust from trace element analyses of human bronchial fluids[J].Environmental Science&Technology,45(15):6262-6267.
Chen J,Li C,Ristovski Z,et al.2016.A review of biomass burning:emissions and impacts on air quality,health and climate in China[J].Science of the Total Environment,579:1000-1034.
Cheng M C,You C F,Cao J J,et al.2012.Spatial and seasonal Variability of water-soluble ions in PM2.5 aerosols in 14major cities in China[J].Atmospheric Environment,60(6):182-192.
Chow J C,Watson J G,Chen L W,et al.2007.The IMPROVE_Atemperature protocol for thermal/optical carbon analysis:maintaining consistency with a long-term database[J].Journal of Air&Waste Management Association,57(9):1014-1023.
Hallquist M,Wenger J C,Baltensperger U,et al.2009.The formation,properties and impact of secondary organic aerosol:current and emerging issues[J].Atmospheric Chemistry&Physics,9(1):5155-5236.
Haywood J,Boucher O.2000.Estimates of the direct and indirect radiative forcing due to tropospheric aerosols:a review[J].Reviews of Geophysics,38:513-543.
Huang H,Zou C W,Cao J J,et al.2012.Water-soluble ions in PM2.5on the Qianhu campus of Nanchang University,Nanchang city:indoor-outdoor distribution and source implications[J].Aerosol and Air Quality Research,12(3):435-443.
Huang R J,Zhang Y,Bozzetti C,et al.2014.High secondary aerosol contribution to particulate pollution during haze events in China[J].Nature,514(7521):218-222.
Kang C,Lee H,Kang B S,et al.2004.Chemical characteristics of acidic gas pollutants and PM2.5 species during hazy episodes in Seoul,South Korea[J].Atmospheric Environment,38(28):4749-4760.
Liu J,Scheuer E,Dibb J,et al.2015.Brown carbon aerosol in the north American aontinental troposphere:sources,abundance,and radiative forcing[J].Atmospheric Chemistry&Physics,15(14):7841-7858.
Paulot F,Jacob D J,Pinder R W,et al.2014.Ammonia emissions in the United States,European Union,and China derived by high-resolution inversion of ammonium wet deposition data:interpretation with a new agricultural emissions inventory(MASAGE_NH3)[J].Journal of Geophysical Research Atmospheres,119(7):4343-4364.
Poschl U.2005.Atmospheric aerosols:composition,transformation,climate and health effects[J].Angewandte Chemie International Edition,44(46):7520-7540.
Shen Z X,Arimoto R,Cao J J,et al.2008.Seasonal variations and evidence for the effectiveness of pollution controls on water-soluble inorganic species in total suspended particulates and fine particulate matter from Xi’an,China[J].Journal of Air&Waste Management Association,58(12):1560-1570.
Watson J G,Tropp R J,Kohl S D,et al.2017.Filter processing and gravimetric analysis for suspended particulate matter samples[J].Aerosol Science&Engineering,1(2):93-105.
Wen W,Cheng S Y,Liu L,et al.2016.Source apportionment of PM2.5 in Tangshan,China-hybrid approaches for primary and secondary species apportionment[J].Frontiers of Environmental Science&Engineering,10(5):83-96.
Zhang F,Wang Z W,Cheng H R,et al.2015.Seasonal variations and chemical characteristics of PM2.5 in Wuhan,central China[J].Science of the Total Environment,518/519:97-105.
Zhang T,Cao J J,Tie X X,et al.2011.Water-soluble ions in atmospheric aerosols measured in Xi’an,China:seasonal variations and sources[J].Atmospheric Research,102(1):110-119.