PM_(2.5) aerosol samples were collected over 12 hr and 24 hr intervals in an inland background area, Gongga Mountain National Nature Reserve(hereafter shortened to Gongga), during the summer of 2011. Polar organic tracers, inorganic ions and meteorological data were measured. The purpose of this work was to investigate the variation patterns, formation and sources of the secondary organic aerosol tracers in the studied atmosphere. The average concentrations of isoprene oxidation products, α-pinene oxidation products, β-caryophyllinic acid, sugars, sugar alcohols and anhydrosugars were 88.6 ± 106.1, 3.6 ± 5.7,0.13 ± 0.30, 13.6 ± 13.1, 31.9 ± 31.4 and 14.8 ± 10.7 ng/m3 respectively in all aerosol samples.The aged α-pinene second organic aerosol(SOA) tracers(i.e., 3-hydroxyglutraric acid(3 HGA), 3-hydroxy-2,2-dimethylglutaric acid(HDMGA), 3-acetylpentandioic acid(APDA) and 3-methyl-1,2,3-butanetricarboxylic acid(MBTCA)) correlated significantly with each other in the 24 hr PM2.5 aerosol samples, indicating that OH· is the major factor controlling the formation of these α-pinene SOA tracers. Using the positive matrix factorization(PMF) model and the tracer-based source apportionment method, we calculated that isoprene oxidation products, α-pinene oxidation products, sesquiterpene oxidation products, biomass burning, fungi spores and anthropogenic SOA accounted for 21.9% ± 5.5%, 8.4% ± 2.1%, 3.0% ± 0.7%, 5.2% ± 5.3%, 5.0% ± 6.2% and 31.4% ± 7.8% of organic carbon respectively during the sampling period.
Li LiWei LaiJinguo PuHengqin MoDongjue DaiGuilin WuShihuai Deng
Aerosol samples were collected over 24 and 12 h to represent day/night aerosol characteristics in forest areas at Ya'an Baima Spring Scenic Area(BM),Panzhihua Cycas National Nature Reserve(PZ),Gongga Mountain National Nature Reserve(GG),and Wolong National Nature Reserve(WL),during the summers of 2010-2012.Mass and chemical component concentrations,including organic carbon,elemental carbon,and inorganic ions(F^-,Cl^-,NO_2^-,NO_3^-,SO_4^(2-),C_2O_4^(2-),PO_4^(3-),K^+,Na^+,Ca^(2+),Mg^(2+),and NH_4^+),of PM_(2.5) aerosols were measured.The average PM2.5 concentrations for 24 h were 72.42,104.89,20.55,and29.19 μg/m^3 at BM,PZ,GG,and WL,respectively.Organic matter accounted for 38.0-49.3%,while elemental carbon accounted for 2.0-5.7%of PM2.5 mass.The sum concentrations of SO_4^(2-),NH_4^+,and NO_3^-accounted for 23.0%,17.4%,22.1%,and 30.5%of PM2.5 mass at BM,PZ,GG,and WL,respectively.Soil dust was also an important source of PM2.5,accounting for 6.3%,17.0%,10.4%,and 19.1%of PM2.5 mass at BM,PZ,GG,and WL,respectively.These reconstructed masses accounted for 75.9-102.0%of PM2.5 mass from the four forest areas of SW China.
Hengqin MoLi LiWei LaiMin ZhaoJinguo PuYi ZhouShihuai Deng
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.
