西安冬季PM_(2.5)中不同极性水溶性有机物的污染特征及氧化潜势

Pollution Characterizations and Oxidative Potentials of Water-Soluble Organic Matters at Different Polarity Levels in Winter PM_(2.5) Over Xi'an

大气细颗粒物(PM_(2.5))通过产生活性氧(ROS)对健康造成不利影响.酸性、中性和高极性水溶性有机物(WSOM)是有机气溶胶中产生ROS的重要成分.采集西安市区2019年冬季PM_(2.5)样品,深入探究不同极性水平WSOM组分的污染特征和健康风险.结果表明,西安市PM_(2.5)中ρ(WSOM)为(4.62±1.89)μg·m^(-3),类腐殖质物质(HULIS)是WSOM的重要组成部分(78.81%±10.50%),霾天HULIS的占比更高.三类不同极性WSOM的碳浓度水平在霾天和非霾天大小分别为:中性HULIS(HULIS-n)>酸性HULIS(HULIS-a)>高极性有机物(HP-WSOM)和HULIS-n>HP-WSOM>HULIS-a.采用DCFH(2′,7′-二氯二氢荧光素)法测量其氧化潜势(OP),发现霾天和非霾天单位质量OP(OPm)的规律均为HP-WSOM>HULIS-a>HULIS-n,单位空气体积OP(OPv)特征为:HP-WSOM>HULIS-n>HULIS-a.整个采样期间OPm与WSOM的三类组分碳浓度呈负相关.霾天HULIS-n(R2=0.866 9)和HP-WSOM(R2=0.858 2)的OPm与其碳浓度高度相关,非霾天HULIS-n、 HULIS-a和HP-WSOM的OPm对各碳浓度都有很强的依赖性.

Atmospheric fine particulate matter(PM_(2.5))can produce reactive oxygen species(ROS),which have adverse effects on health.Acidic,neutral,and highly polar water-soluble organic matter(WSOM)is an important component of ROS in organic aerosols.PM_(2.5) samples were collected in winter 2019 in Xi'an City to deeply explore the pollution characteristics and health risks of WSOM components with different polarity levels.The results showed that the concentration of WSOM in PM_(2.5) in Xi'an was(4.62±1.89)μg·m^(-3),humic-like substances(HULIS)were an important part of WSOM(78.81%±10.50%),and the proportion of HULIS was higher in haze days.The concentration levels of three WSOM components with different polarities in haze and non-haze days were:neutral HULIS(HULIS-n)>acidic HULIS(HULIS-a)>highly-polarity WSOM(HP-WSOM)and HULIS-n>HP-WSOM>HULIS-a.The oxidation potential(OP)was measured using the 2',7'-dichlorodihydrofluorescein(DCFH)method.It was found that the law of OPm in haze and non-haze days was HP-WSOM>HULIS-a>HULIS-n,and the characteristic of OPv was HP-WSOM>HULIS-n>HULIS-a.During the whole sampling period,OPm was negatively correlated with the concentrations of the three components of WSOM.The OPm of HULIS-n(R2=0.8669)and HP-WSOM(R2=0.8582)in haze days were highly correlated with their respective concentrations.The OPm of HULIS-n,HULIS-a,and HP-WSOM in non-haze days were strongly dependent on their respective component concentrations.