白马泉风景区夏季大气PM2.5中二次有机物的初步研究

实验选择2010年7月于雅安市白马泉风景区常绿阔叶林内采集PM2.5样本,并对样本进行甲醇提取、三甲硅醚衍生化及GC/MS分析,探讨研究区域内气溶胶中异戊二烯氧化产物、α-/β-蒎烯氧化产物、小分子羧酸(苹果酸、2-羟基戊二酸)的浓度与昼夜变化趋势,并结合大气污染气体(SO2、NOx、O3)和环境气候条件(风速、温度、湿度等)对其浓度的影响进行讨论.结果表明,24 h PM2.5样本中,2-甲基丁四醇、异丁烯三醇、2-甲基甘油酸的浓度分别为63.3、45.0、4.4 ng.m-3;降蒎酸、3-羟基戊二酸、3-羟基-1,2,3-丁三酸的浓度分别为4.1、5.0、5.3 ng.m-3.除降蒎酸外,此次研究的其他二次有机气溶胶组分均呈现昼高夜低.白马泉风景区聚集了较高浓度的天然源二次有机物与当地亚热带繁茂的植被、湿热气候、沟谷型地貌及大气污染状况等诸多环境因素有关.

Secondary Organic Tracers in Summer PM2.5 Aerosols from Baima Spring Scenic Area, Yaan, Sichuan Province

Integrated PM2.5 aerosol samples were collected at Baima Spring Scenic Area, a forest site of Yaan, Sichuan Province, during the summer of 2010. Organic speciation including isoprene oxidation products (2-methyltetrols, C5-alkene trols, 2-methylyceric acid), alpha-/beta-pinene oxidation products (norpinic acid, 3-hydroxyglutaric acid, 3-methy-1,2,3-butanetricarboxylic acid), and small molecular carboxylic acid (malic acid, 2-hydroxyglutaric acid) were analyzed. The generation mechanisms of SOA as well as their influencing factors were particularly discussed. Results show that average concentrations of 2-methyltetrols, C5-alkene triols, 2-methyglyceric acid, norpinic acid, 3-hydroxyglutaric acid and 3-methy-1,2,3-butanetricarboxylic acid are 63.3, 45.0, 4.4, 4.1, 5.0, 5.3 ng x m(-3) respectively, of 24-hour lapse samples. SOA compounds are consistent with higher concentrations in the day than during the night only except for norpinic acid. Relatively high level of biogenic SOA at the study area is concerned with many environmental factors, i. e. local abundant vegetations, warm and humid climate, sunken valley topography, the atmospheric pollution state, etc.