摘要
利用平行因子分析和后向轨迹模型,采用紫外光谱法、三维荧光光谱法,分析西安市PM_(2.5)碳组成及水溶性有机物(Water-Soluble Organic Matters,WSOM)的荧光组分、分子特性和来源。结果显示,西安市各季节PM_(2.5)及其有机碳(Organic Carbon,OC)和元素碳(Elemental Carbon,EC)的质量浓度由高到低依次为:冬、秋、春、夏,且南北郊差异不显著。PM_(2.5)中水溶性有机碳(Water-Soluble Organic Carbon,WSOC)质量浓度为3.50~17.29μg/m^(3),冬季WSOC质量浓度最高。四季的WSOM中均含有紫外光类腐殖质和可见光类腐殖质。秋、冬和夏季类富里酸的荧光强度占比最大。WSOM的E_(2)/E_(3)、E_(3)/E_(4)和AAE值由高到低依次是:冬、春、夏、秋。SUVA 254和MAE_(3)65值均在冬季最高,夏季最低。冬季WSOM的相对分子质量和腐殖化程度较小,分子苯环取代程度最大,光吸收能力对光吸收的波长依赖性较强;秋季WSOM的相对分子质量较大,腐殖化程度较强,光吸收的波长依赖性较弱;夏季WSOM的芳香化程度和光吸收能力及春季WSOM分子苯环取代程度最弱。碳组分质量浓度、UV 254、α350和荧光强度两两呈显著正相关(p<0.01)。WSOM的荧光指数(Fluorescence Index,FI)、生物源指数(Biogenic Index,BIX)和腐殖化指数(Humification Index,HIX)值分别为1.51~2.15、0.88~1.46、1.18~3.19。冬季WSOM的自生来源最高,夏季WSOM的陆源来源比例相对较大。西安市污染气团主要来自于陕西省区域气团传输。西安市四季PM_(2.5)碳组成及WSOM的荧光组分、分子特性和来源存在季节差异,但北郊和南郊的紫外荧光光谱特性和来源差异不显著。
By using parallel factor analysis,backward trajectory models,UV spectroscopy,and three-dimensional fluorescence spectroscopy to analyze the carbon composition,molecular characteristics,and sources of Water-Soluble Organic Matter(WSOM)in PM_(2.5) in Xi'an.The results show that the seasonal variations of PM_(2.5),OC and EC in Xi'an follow a descending order of winter,autumn,spring,and summer,with no significant difference between the southern and northern suburbs.The concentrations of WSOM are 3.5017.29μg/m^(3),with the highest concentration in winter.WSOM in all seasons both contained UV humus-like and visible humus-like substances.In autumn,winter,and summer,the fluorescence intensity of fulvic acid-like accounts for the largest proportion.The seasonal variation of E_(2)/E_(3),E_(3)/E_(4),and AAE values follow the descending order of winter,spring,summer,and autumn.The values of SUVA 254 and MAE_(3)65 are highest in winter and lowest in summer.The E_(2)/E_(3),E_(3)/E_(4) and AAE values in the southern suburbs are higher than those in the northern suburbs,while UV 253/UV 203,SUVA 254,and MAE_(3)65 values were lower.The molecular weight and humification degree of WSOM are smaller,the degree of molecular benzene ring substitution is the largest,and the capacity and wavelength dependence of light absorption is stronger in winter;the molecular weight and humification degree of WSOM are larger,and the wavelength dependence of light absorption was weaker in autumn;the degree of aromatization and light absorption capacity in summer and the degree of molecular benzene ring substitution of WSOM in spring were the weakest.The concentrations of carbon composition,UV 254,α350,and fluorescence intensity were significantly positively correlated with each other(p<0.01).The values of FI,BIX,and HIX are 1.512.15,0.881.46,and 1.183.19,respectively.The autochthonous source of WSOM is the highest in winter,while terrestrial sources are larger in summer.The humification degree of WSOM in autumn and summer is higher.Polluted air mass in Xi'an mainly comes from local transmission.There are seasonal differences in carbon composition,molecular characteristics,and sources of WSOM in Xi'an,but there is no significant difference between the northern and southern suburbs.
作者
杨毅
赵明佳
张亚楠
刘伟
YANG Yi;ZHAO Mingjia;ZHANG Yanan;LIU Wei(School of Environmental and Municipal Engineering,Xi'an University of Architecture and Technology,Xi'an 710055;Shaanxi Key Laboratory of Environmental Engineering,Xi'an University of Architecture and Technology,Xi'an 710055)
出处
《安全与环境学报》
CAS
CSCD
北大核心
2024年第7期2860-2868,共9页
Journal of Safety and Environment
基金
国家自然科学基金项目(52070154、21407119)
陕西省自然科学基础研究计划项目(2021JM-375)
陕西省教育厅重点实验室科研计划项目(18JS055)。
