ELPI 测定环境空气 PM2．5的现场比对研究

采用ELPI自动监测方法与手工采样－重量法对环境空气PM2．5监测进行现场比对研究,按照两种方法数据的相对偏差来评价ELPI方法的数据质量。实验结果表明,两种方法数据的相对偏差范围为－12．9％～17．4％,加权平均值为3．0％;相对偏差的绝对值范围为1．1％～17．4％,平均值为9．3％。 ELPI法的数据质量总体较好,方法的准确度尚可。只是随着空气PM2．5浓度测定值的升高,ELPI法与重量法相对偏差的绝对值显著减小,可见,在低浓度下,ELPI法的数据质量相对较差,此时方法的准确度有待进一步验证、提高。     

矩形喷嘴PM2.5惯性冲击采样器的研制

惯性冲击器是最重要的颗粒物采样器之一,被广泛用于大气颗粒物的分级采样。设计了一种中流量的矩形喷嘴PM2.5惯性冲击采样器。根据Marple准则设计了冲击器的结构参数,用CFX软件进行了惯性冲击器内部气固两相流场的CFD模拟,得出了惯性冲击器的最优结构参数。根据得出的最优设计参数,进行了PM2.5惯性冲击器样机的结构设计,并在实验室用APS气溶胶空气动力学粒度仪进行了标定。实验标定和CFD数值模拟的结果基本吻合,当采样流量为100L/min,冲击器的切割粒径dp50=2.55μm,切割锐度σg=1.4,满足设计要求。     

Comprehensive characterization of ambient nanoparticles collected near an industrial science park: Particle size distributions and relationships with environmental factors

We investigated the characteristics of ambient particles and their relationships with various environmental factors, including gaseous pollutants (CH4, non-methane hydrocarbons (NMHC), total hydrocarbons (THC), NOx, CO, SO2), meteorological parameters (humidity, temperature), and time (day/night, workday/weekend). We used an electrical low-pressure cascade impactor to measure the number and size distributions of ambient particles (0.007–10 m) that were collected approximately 1 km northwest of Hsinchu Science Park in Taiwan between February and May 2007. The number concentrations of particles were enhanced through photochemical reactions during the day. In addition, high traffic flow during workdays increased the formation of particulates. Except for SO2, all of the gaseous pollutants we studied (CH4, NMHC, THC, NOx, CO) correlated positively with the total number concentrations of ambient particles during daytime, indicating that they might contribute to the particulate burden. The poorer relationship between the SO2 level and the total number concentration of particles suggests that SO2 might participate indirectly in the nucleation process during particle formation, The high enrichment factors for Zn, Pb, Cu, and Mn, which mostly comprised the ultrafine particles (diameter: < 0.1 m) and fine particles (diameter: 0.1–1 m), presumably arose from emissions from traffic and high technology factories. Heterogeneous reactions on solid particles might play a role in the removal of SOx and NOx from the atmosphere. Sulfides and nitrides can further react with these local pollutants, forming specific Cu-containing compounds: CuO (39%), CuSO4 (34%), and Cu(NO3)2 (27%), within the ambient particles in this industrial area.     

冲击采样器设计参数分析

在颗粒物研究中 ,分级采样是一种常用的监测方法 ,而冲击采样器是颗粒物分级采样的重要仪器。从颗粒物的受力分析着手 ,得到了冲击采样器重要参数———斯托克斯数的表达式 ,并对TSP、PM1 0 和PM2 5冲击采样器设计参数进行了详细分析 ,得到了采样器设计参数的关系式及相关曲线     

Inertial oscillations and particle flux interactions in a marine protected area in Gulf of Naples

The area between the island of Capri and Punta Campanella was investigated from June to November 2003. Punta Campanella separates the Gulf of Naples from the Gulf of Salerno and has been declared a marine protected area in 1997. The study area has a particular interesting topography, due to the presence of a sill situated at a depth of 80 m. Samples were collected by instruments carried on a mooring array (sediment trap, current meters, and temperature sensors) and by CTD cast (along transects perpendicular to the coast). We observed most important fluctuations in the temperature spectra (corresponding to the inertial oscillations period), in August. The total mass flux was 585.67 mg m^-2 d^-1 in the summer, while in early autumn the flux exhibited values one order of magnitude higher than in summer (1539.97 mg m^-2 d^-1). The main focus of this study was to understand the influence of the internal waves on the particle flux. During the autumn, in the particle flux collected, there is a strong resuspension component, and the observation that the enhanced inertial oscillations and increased sedimentation occur at the same time allows us to presume that the inertial oscillations could be one of the reasons for the resuspension process during the sampling period.     

基于ELPI的南京城区大气可吸入颗粒物现状分析

采用电称低压冲击器(ELPI)对南京城区可吸入颗粒物粒径分布和质量浓度进行连续在线测量,得到了南京城区大气可吸入颗粒物的日变化特征,表明其呈现双峰、双谷分布,夜间高,白天低,上午高,下午低;结合气象参数,研究了大气可吸入颗粒物浓度变化与气象因子的相关性;此外,对可吸入颗粒物粒径分布特征也进行了研究,可以看出,南京地区可吸入颗粒物的主要成分是细颗粒(PM2.5),粒径在0.028～2.31μm的颗粒物占可吸入颗粒物的98%～99%。     

固定污染源排气中PM2.5采样方法综述

我国新的环境空气质量标准已于2012年颁布并将自2016年起全面实施.为使新标准规定的细颗粒物(PM2.5)达标,各地需对固定污染源排气中PM2.5进行监测和控制,但目前国内尚无固定源PM2.5采样标准方法.本文系统地介绍了国内外固定源PM2.5采样方法及相应的国际标准,包括直接采样法和稀释采样法,并分析了这些方法的优缺点及用于我国固定源PM2.5测量的可行性.为了便于环境管理和监测,建议确立基于虚拟惯性撞击原理的烟道内直接采样方法为标准方法,用于测定固定源排气中的可捕集PM2.5;为了评估固定源PM2.5排放对大气环境质量和健康的影响,建议同时确立以烟道外稀释采样为基础的标准方法,用于测定固定源排气中包括可捕集和可凝结的PM2.5.     

基于虚拟撞击原理的固定源PM10/PM2.5采样器的研制

目前我国尚无固定源PM2.5采样标准方法,现有商业化的固定源PM2.5采样器在使用中存在明显不足,因此本研究开发了一种固定源PM10/PM2.5双级虚拟撞击采样器.经实验室标定,该采样器切割效率曲线优于国际标准ISO 7708:1995对采样器的规定,采样器横截面直径为74 mm,满足我国固定源采样口尺寸要求.采样器既可以安装滤膜,也可以安装滤筒,适用于不同浓度的烟尘采样.虚拟撞击器的切割点与次流所占比值呈负相关,比值减小时,切割点增大.为降低颗粒物损失,虚拟撞击器喷嘴距收口的距离至少应为喷嘴直径的1.5~2倍.     

2002年春季沙尘暴对青岛大气气溶胶的影响

根据TSP,PM10,分级粒子质量浓度观测资料,分析了2002年春季发生于我国北方的2次沙尘天气过程对青岛大气环境的影响.在3月15-19日和21-23日的2次沙尘天气过程中TSP质量浓度分别为0.488和0.721 mg/m\+3,比平时增加了2.8和4.1倍.沙尘天气期间2～7 μm粒子为影响青岛的主要成分,在第2次沙尘暴期间该粒径的粒子质量浓度增加了30倍,其中2.1～3.3 μm粒子质量浓度达到0.13 mg/m\+3.根据地面气象资料和PM10连续监测资料发现,在地面风向转北之前,高空气流携带的沙尘首先影响到青岛.      

用于挥发性颗粒物连续测量的冲击式采样器设计

为了实现滤膜式PM2.5测量仪中挥发性颗粒物的连续补偿测量,根据挥发性颗粒物加热挥发、冷却凝结的物理特性,利用冷凝装置和串级冲击采样器原理,设计了双通道的挥发性颗粒物连续采样测量装置。按照采样粒径为10、5、2.5μm的颗粒物设计了3级冲击采样器,通过理论计算得到了采样器的孔径、孔数等相关参数;对采样器中采集的样品使用石英晶体微天平(QCM)直接测量,并采用加热清洗的方式结合双通道的设计实现挥发性颗粒物的连续采样测量。该装置不但可以应用于目前滤膜式颗粒物监测仪中的挥发性颗粒物补偿测量,使测量结果更加准确可靠;也可直接应用于挥发性颗粒物的测量分析。