北京地区大气中VHCs观测结果的初步分析

采用Tenax TA和碳分子筛吸附富集— 热脱附— 毛细管柱气相色谱法, 测定了北京地区大气中C2～C10可挥发性烃类化合物(简称VHCs)的浓度变化。从2001年9月到2003年8月, 先后采集到有效样品113个。检出55个VHCs组分, 其中烷烃26个, 烯烃19个,芳香烃10个。TVHCs的平均浓度为364.3 ±99.3 μg/ m3;11月份浓度最高, 为546.9 ±353.5 μg/m3, 8月份浓度最低, 为251.8 ±152.4 μg/m3;采暖季比非采暖季高30%, 城区比郊区高10%;有明显的日变化。初步分析发现, 机动车尾气排放和天气气象条件是造成北京地区大气VHCs污染的两个最主要因素。     

Variation Characteristics of Ambient NMHCs at Shangdianzi and Lin＇an Regional GAW Sites

In order to study the variation characteristics of concentration of the atmospheric non-methane hydrocarbons (NMHCs) in background area of China, the atmospheric concentrations of NMHCs were measured at Lin'an (LA) regional GAW (Global Atmosphere Watch) Station (30°25'N, 119°44'E; 132.0 m ASL) and Shangdianzi (SDZ) regional GAW Station (40°19'N, 117°07'E; 286.5 m ASL) with the sorbent sorp-tion/thermal desorption/gas chromatographic method. Totally 145 samples were collected during the period of October 2003 and July 2004. Among the 52 NMHC species of C2-C10 detected there were 26 alkanes, 17 alkenes, and 9 aromatics. The average concentrations of total NMHCs (TNMHCs) at LA and SDZ were (238.5±126.0)×KT9C and (278.7±185.5)x10-9C, respectively. The results showed the ambient concentrations of TNMHCs at LA regional GAW Station increased notably over the last decade. The compositions of NMHCs at SDZ and LA were relatively similar. The proportions of alkanes, alkenes, and aromatics for SDZ and LA were hi ranges of (27.3±4.0)%, (10.3±3.5)%, and (62.5±4.8)%, respectively, with features of vehicle exhaust emissions. The concentrations of NMHCs at the two sites showed obvious diurnal and seasonal variations. The TNMHC concentrations in October-November were high at the two sites, and relatively low in April and July. The diurnal variation patterns at the sites were different. The high TNMHC concentrations at SDZ normally appeared in evening and night, but appeared in morning at LA. The TNMHCs concentrations at the two sites were significantly influenced by the meteorological condition. The high TNMHC concentration associated with the local wind from the urban areas or traffic in upper reaches.     

北京城区大气边界层空气污染特征观测研究

2001年1～3月共分3期,在北京城市地区大气边界层进行了大气化学和气象现埸观测.结果表明北京城市低层大气中主要的气体污染物是NOx,其次为SO2;各高度SO2和NOx之间的关系有较好的一致性,NOx大约为SO2浓度的2倍或2倍以上;污染源排放是造成北京城市低层大气空气污染严重与否的主要原因之一;同一季节中空气污染状况很大程度上取决于天气条件;NO2/NO和NO之间有着较好的负幂指数相关关系;近地层不同高度和不同地点观测到的大气污染物随时间变化趋势有较好的一致性.     

北京北郊冬季低空大气气溶胶分析

文章分析了2001年1月10～16日和2月20日～3月2日两时段北京北郊中国科学院大气物理研究所325 m高的气象塔上距地面320、100和8 m 3个高度所采得的气溶胶样品的物理化学特征.计算了气溶胶的TSP浓度、化学组分及其分布和粒度谱.探讨了气象条件对气溶胶浓度及其来源和分布的影响.初步发现在所测的高度范围内,气溶胶TSP的浓度随高度的增高而下降,70%以上浓度分布在细粒组(d<2.1 μm).气溶胶中浓度最高的前20个元素是S、Fe、Ca、Al、K、Na、Mg、Zn、P、Ti、Pb、Ba、Mn、Cu、V、As、Cr、 Rb、Sb和Br.挥发性元素主要分布在细粒组,元素浓度随高度增加而减少.气溶胶的离子浓度也有相同的分布特征.风速变小、层结呈现稳定,尤其逆温以及大气湿度升高均为气溶胶浓度升高的因素.人为排放源是大气气溶胶的主要贡献者.导致北京严重空气污染的气溶胶源地以北京当地及其周边邻近地区的污染源为主.     

RESEARCH ON SURFACE O_3 WITH METEOROLOGICAL CONDITIONS UNDER ATMOSPHERIC BACKGROUND CONDITIONS IN NORTHEAST CHINA

Surface O_3 concentration and its precursors have been observed at Longfengshan station,Heilongjiang Province for a period of one year from August 13,1994 to July 30,1995.Relationship between surface O_3 and the meteorological conditions during this period is analyzed inthis study.Observation results show that diurnal variation of surface O_3 follows a pattern ofdouble-peaks with amplitude of 27—28 ppb under fine days in summer and autumn.Although thediurnal variation is small(14 ppb),it is still detectable when it is overcast.Diurnal variation of O_3is irregular under rainy days.Surface O_3 concentration rises when wind speed starts to increase at0800 BT(Beijing Time)from 0 to 6 m s~(-1)in autumn,winter and summer.Relative high surfaceO_3 concentration is noticed frequently when S,SSW,SW and WSW wind are encountered at thestation during all seasons.At 0800 BT and 1400 BT the surface O_3 concentration increases with theincrease of global radiation accordingly during fine days in winter,spring and autumn.During finedays average peak of O_3 concentration in summer is 20 ppb higher than that in winter while theaverage peak of global radiation in summer is almost twice as high as that in winter.The averagesurface O_3 concentration under fine days in autumn at Longfengshan station is 14 ppb lower incomparison to the observation results from Lin'an station where Lin'an is at about the samelongitude and lower latitude,with same environment,which is mainly caused by the difference ofglobal radiation due to different latitudes in these two areas(difference of average peak globalradiation about 100 W m~(-2)).     

庐山降水化学垂直分布的初步研究

庐山大气降水中离子浓度随高度降低而增高，但pH值减小。锋面过境降水与变性高压西南侧降水中各种离子浓度以及山下与山上测点离子浓度比有明显差异，这可能与气流来向和污染源的分布有关。气溶胶对降水中SO4=贡献为91.0%。气流不同来向影响气溶胶浓度。不同天气过程，不同离子的云下冲刷过程是不同的。     

美国NOAA的气候变化地球物理监测

美国的气候变化地球物理监测(Geophsical Monitoring for Climatic Change简称GMCC)是美国国家海洋大气局(NOAA)环境科学研究院下属的空气资源实验室的一个机构。它管辖分布在地球边远地区的四个本底空气污染监测基准站(简称基准站)。本文将重点介绍GMCC和四个基准站之一的莫纳洛瓦(Maura Loa)基准站。     

INTERCOMPARISON OF OZONE VERTICAL PROFILES BETWEEN ECC OZONESONDE AND BREWER UMKEHR MADE OVER QINGHAI PLATEAU OF CHINA

From October 1995 to August 1996.a total of 50 ECC(electrochemical concentration cell)ozonesoundings were made in Xining(36.43°N,101.45°E,2296 m ASL)to study the distributionand seasonal characteristics of ozone profile,and intercompare the Brewer Umkehr ozone profilesobtained at Waliguan Baseline Station over the Qinghai Plateau.It was demonstrated that(1)Umkehr produced estimates of the ozone comparing with ECC profiles were accurate to better than25% in the 20—38 km altitude range,and where 23—33 km region was the most accurate,withinabout 15% of the ECC ozonesonde:(2)higher differences between Brewer Umkehr and ECCozonesonde occurred in the troposphere and lower stratosphere;and ozone amounts wereoverestimated in Umkehr layers 1,2 and 3,and were underestimated in Umkehr layers 6 and 7 byBrewer Umkehr method.     

北京地区气溶胶PM2.5粒子浓度的相关因子及其估算模型

文中运用统计分析和气象统计预报的方法 ,使用北京白石桥小区的污染物观测资料和同期北京地区的气象观测资料 ,对影响大气污染的气象因子进行了综合分析 ,并分别建立了气溶胶PM 2 .5粒子浓度与气体污染物、气象要素场的两类统计相关拟合模型。发现气溶胶PM2 .5粒子浓度与气体污染物浓度存在不同程度的相关性 ,且与气象条件亦存在显著的相关关系 ,此类时空变化及其量化估算模型具有一定实际应用价值。通过确定气象要素场和气溶胶浓度的关系可进一步研究不同地区的污染物输送和污染源扩散影响的问题。     

2006年春季沙尘天气下背景地区大气气溶胶光学特性的观测研究

利用2006年3～5月北京上甸子本底站气溶胶细粒子(PM2.5)质量浓度、吸收和散射系数的连续观测资料,对2006年春季上甸子本底站清洁、污染输送及典型沙尘天气下气溶胶的消光特性进行了分析.结果显示:①本底站在春季清洁情况下PM2.5质量浓度、吸收和散射系数的日均值水平分别为:10 μg/m3、7 Mm-1和20Mm-1左右,单散射反照率分布在0.71～0.78之间;此次观测到的污染输送过程中PM2.5质量浓度、吸收和散射系数平均值分别为:145 μg/m3、44.5 Mm-1、374.3 Mm-1,单散射反照率分布在0.84～0.94之间;沙尘影响期间,PM2.5质量浓度、吸收和散射系数以及单散射反照率的测量结果分布在248.2～424.1 μg/m3、10.8～44.7Mm-1、225.4～392.5 Mm-1和0.89～0.96之间.②观测得出,沙尘影响集中的时段细粒子质量浓度、气溶胶散射系数和气溶胶吸收系数都成倍地上升,其中质量浓度和散射系数上升的幅度要高于吸收系数.③3种天气条件的对比结果显示.受沙尘天气影响PM2.5质量浓度明显上升,且逐时波动幅度大;吸收系数远高于清洁天气下的观测结果,但比污染输送过程的测量结果偏低;散射系数同样高于清洁天气下的观测结果,与污染输送情况下的测量结果接近.沙尘天气导致颗粒物浓度明显上升,其对气溶胶粒子散射作用的贡献要大于吸收作用.