PDF《陕南农村冬季 PM2.5 主要化学组分特征》

陕南农村冬季 PM2.

5 主要化学组分特征 朱崇抒 1,

2 ,曹军骥 1,

2 ,刘随心 1,

2 ,屈? 1,

2 ,张? 婷1,

2 (1. 中国科学院地球环境研究所 中国科学院气溶胶化学与物理重点实验室,西安 710061;

2. 中国科学院地球环境研究所 黄土与第四纪地质国家重点实验室,西安 710061) 摘? 要:通过对陕南农村冬季 PM2.5 采样分析,获得 PM2.5 质量浓度及主要化学组分特征.PM2.5 平均质量浓度为 89.5?±?42.0 ?g??m?3 ,超过国家二级标准.观测期间 PM2.5 中OC、EC 浓度平均值 分别为 16.0?±?6.9 ?g??m?3 和5.7 ± 3.2 ?g??m?3 ,OC/EC 平均比值为 3.0?±?0.4.主要水溶性离子组分 为、和.粒子数浓度与表面积浓度峰值主要集中在 0.5 μm 以下粒径段.PAHs、 BeP 和BaP 平均质量浓度分别为 48.9?±?10.9 ng??m?3 、3.0?±?0.9 ng??m?3 和1.2?±?0.7 ng??m?3 ,PAHs 污 染较严重,强致癌物 BaP 浓度超过国家环境空气质量标准年平均浓度限值.当地农村以石煤为 主的能源结构及采用的燃烧方式是导致污染的重要因素. 关键词:PM2.5;

化学组分;

农村;

陕南 The characteristics of chemical components for rural PM2.5 in winter over Shaannan ZHU Chongshu1,

2 , CAO Junji1,

2 , LIU Suixin1,

2 , QU Yao1,

2 , ZHANG Ting1,

2 (1. Key Laboratory of Aerosol Chemistry &

Physics, Institute of Earth Environment, Chinese Academy of Sciences, Xi'

an 710061, China;

2. State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi'

an 710061, China) Abstract: Background, aim, and scope The usage of biomass and coal for cooking and heating is common in rural area in China. In reality, the emission largely contributes to the chemical components of particulates. The study here presented the levels of rural carbonaceous fractions, ions and PAHs over Shaannan. Materials and methods The observation campaign was conducted in a rural site at Shaannan. Samples were collected by using mini-volume samplers (Airmetrics, USA) operating with a flow rate of

5 L??min?1 for

24 hours. All samples were collected on

47 mm Whatman quartz microfibre filters (QM/A). The filters were pre-heated before sampling at 800℃ for

3 hours. After collection, the filters were stored in a refrigerator before chemical analysis. Before and after field sampling, quartz filters were equilibrated for

24 hours in the box at a constant temperature (20℃ to 23℃) and relative humidity (35% to 45%). The PM2.5 mass was determined by weighing the filters before and after sampling on an electronic microbalance (1 μg sensitivity) (Sartorius, MC5, Germany). All the filters were analyzed for carbon fractions using a DRI Model

2001 Thermal/Optical Carbon Analyzer (Atmoslytic Inc., Calabasas, CA, USA). Carbon fractions were analyzed following the Interagency Monitoring of Protected Visual Environments (IMPROVE-A) thermal/optical reflectance (TOR) protocol. The method produced data for four OC fractions (OC1, OC2, OC3, and OC4 in a helium atmosphere at 140℃, 280℃, 480℃, and

495 580°C, respectively), a pyrolyzed carbon fraction (OP, determined when reflected laser light attained its original intensity after oxygen was added to the combustion atmosphere), and three EC fractions (EC1, EC2, and EC3 in a 2% oxygen/98% helium atmosphere at 580℃, 740℃, and 840℃, respectively). The IMPROVE protocol defined OC as OC1+OC2+OC3+OC4+OP and EC as EC1+EC2+EC3?OP. The analyzer was calibrated with known quantities of CH4 each day. Replicate analyses were performed once every ten samples. The blank filters were also analyzed for quality control and the sample results were corrected by the average of the blank concentrations, which were 0.96 ?g??m?3 and 0.23 ?g??m?3 for OC and EC, respectively. The concentrations of three anions (Cl? , and ) and five cations (Na+ , , K+ , Mg2+ and Ca2+ ) were determined in aqueous extracts of the sample filters by using a Dionex-600 Ion Chromatograph (Dionex Inc., Sunnyvale, CA, USA). Standard solution and blank test were performed before sample analysis and the result of correlation coefficient of standard samples was more than 0.999. One in