首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到18条相似文献，搜索用时 93 毫秒
1.
2014年3月13日至4月20日在福建三明市利用PM2.5中流量采样器采集大气中PM2.5膜样品,测定了PM2.5的质量浓度,并用热/光碳分析仪和离子色谱分析了其组分变化特征.结果表明,三明市观测期间PM2.5的平均质量浓度为73.61±0.73 μg/m3,有机碳(OC)和元素碳(EC)的平均质量浓度分别为7.26±1.00和5.63±0.27 μg/m3,水溶性离子中SO42-、NH4+、NO3-和Na+的质量浓度分别为18.08±12.19、4.18±3.56、2.77±1.16和2.73±0.23 μg/m3,总和占总水溶性离子的87.76%.结合后向轨迹分析了福建三明市的污染物来源特征.该地区OC/EC的平均比值小于2,SOC(二次有机碳)生成量很少,主要以一次有机污染物为主,OC、EC与K+的相关性分析表明OC、EC与K+的来源相近,可以判断OC、EC绝大部分来源是生物质燃烧产生的污染物.在水溶性离子分析中,观测期间NO3-/SO42-为0.159±0.02,表明三明市主要以固定源为主,机动车辆等移动源贡献较少.  相似文献   

2.
自2014年以来,中国细颗粒物（PM2.5）浓度大幅度下降,但臭氧（O3）浓度逐年缓慢上升,厘清PM2.5和O3（P-O）相关性尤为关键.在本研究中,2014—2019年北京和南京PM2.5年均质量浓度下降幅度分别为-6.86和-6.15 μg·m-3·a-1;而日最大8小时平均O3质量浓度（MDA8 O3）年均增长幅度为1.50和1.75 μg·m-3·a-1.研究期间,北京地区MDA8 O3质量浓度小于100 μg·m-3,P-O呈负相关;而当质量浓度大于100 μg·m-3时,P-O为正相关.通过Pearson相关系数研究P-O两者相关性.在两个城市每月相关性分析中,在每日时间尺度5—9月为强的正相关;而小时时间尺度11月至次年2月趋于负相关.在北京,P-O每月和季节相关性变化大于南京.在日变化中,夏季在16时为强的正相关,春秋两季在13—17时为弱的正相关,而在春、秋和冬季8时,却为强的负相关.  相似文献   

3.
针对地面站点稀疏不足以提供高空间覆盖、高空间分辨率的面域PM2.5数据支撑区域细颗粒物污染防治的问题,以湖北地区2015-2017年的MODIS卫星遥感气溶胶光学厚度（AOD）产品数据为主预测量,结合温度、湿度、风速、压强等气象参数和植被指数数据等辅助预测量,建立了AOD-PM2.5关系逐日变化的线性混合效应（LME）模型,用于估算湖北地区的PM2.5浓度水平.利用十折交叉验证方法进行了模型精度评估.结果表明：1）2015-2017年的交叉验证R2分别达到0.89、0.85和0.88,利用MODIS AOD数据反演近地面PM2.5质量浓度的线性混合效应模型能很好地用于区域细颗粒物遥感监测;2）省内PM2.5质量浓度空间差异显著,鄂东、鄂南和鄂北高,鄂西北和鄂东南低;3）全省PM2.5估算时空数据年均值呈下降态势,分别为65.6±39.8、57.1±34.1和48.1±28.3 μg/m3,各市除随州、咸宁2016、2017年年均值持平外,都呈下降趋势.  相似文献   

4.
为了监测北京奥运主场馆附近大气颗粒物的污染状况以及评估奥运污染源减排措施对北京大气颗粒物质量浓度变化的影响,利用颗粒物在线监测仪器TEOM于2007年和2008年夏季,在奥运主场馆附近的中国科学院遥感应用研究所办公楼楼顶对大气颗粒物PM10和PM2.5进行了连续同步观测。结果表明,2007年夏季监测点附近大气PM10与PM2.5质量浓度的平均值分别为153.9和71.2μg·m-3,而2008年夏季PM10与PM2.5质量浓度的平均值分别为85.2和52.8μg·m-3。与奥运前一年同时段相比,奥运时段大气PM10和PM2.5的质量浓度分别下降44.5%和25.1%。对比分析奥运前后的2次典型污染过程发现,空气相对湿度的增加和偏南气流输送的共同影响易造成大气颗粒物的累积增长,而降雨的湿清除作用和偏北气流则会使大气颗粒物浓度迅速降低。在相近的气象条件下,奥运前后的污染过程中,大气细粒子的日均增长速率分别为25.1和13.9μg·m-3·d-1,而大气粗粒子的日均增长速率分别为20.8和2.2μg·m-3·d-1,奥运时段污染累积过程中大气粗、细粒子的增长速率分别显著低于和略低于奥运前同时段污染过程中颗粒物的增长速率。污染源减排措施的实施是奥运期间大气颗粒物质量浓度降低的主要原因,从控制效果来看,奥运期间实施的污染源减排措施对大气粗粒子的控制效果明显好于大气细粒子。  相似文献   

5.
基于2016年11月24日—12月23日南京市草场门站、鼓楼站和仙林站的强化试验观测资料,分析了城市和郊区主要大气污染物的时空变化特征及其与气象要素的相互关系。研究发现：观测期间南京PM2.5、PM10、NO2、O3、CO、SO2月均质量浓度分别为52.84~84.34 μg·m-3、88.36~120.34 μg·m-3、49.98~51.66 μg·m-3、24.85~50.57 μg·m-3、0.99~1.2 mg·m-3和22.1~26.48 μg·m-3;近地面,城市大气污染物质量浓度高于郊区,其中城市O3比郊区高61.0%;在城市地区,除NO2和CO外,鼓楼站大气污染物质量浓度高于草场门站,其中鼓楼站PM2.5比草场门站高42.7%;PM2.5小时质量浓度最大为210.93 μg·m-3,重污染过程出现时风速较低、温度较高,郊区PM10、PM2.5、NO2质量浓度呈现高值时的最频风向为南风,O3和SO2质量浓度呈现高值时的最频风向分别为西风和西南风,所以郊区大气污染受城市输送影响。利用HYSPLIT模式研究发现12月4—8日和16—20日的污染气团分别来自西部和北方地区,聚类分析发现12月影响南京市的污染气团45%来自西部地区且移动速度较快,55%来自北方地区且移动速度较慢。由此可见,南京市冬季出现的大气污染,其形成不仅与本地排放和局地气象条件有关,而且西部和北方地区的远距离输送也会造成影响。  相似文献   

6.
南京市城市不同功能区PM10和PM2.1质量浓度的季节变化特征   总被引：1，自引：0，他引：1  
使用Anderson-Ⅱ型9级撞击采样器测量了南京市鼓楼商业区、江北工业区、钟山风景区和宁六高速公路交通源春、夏、秋三季的大气气溶胶质量浓度。分析结果表明:南京市PM2.1和PM10的质量浓度存在明显的季节变化,秋季>春季>夏季;ρPM10春季为167.47 μg/m3,夏季为 85.99 μg/m3,秋季为238.99 μg/m3;ρPM2.1春季为59.66 μg/m3,夏季为42.80 μg/m3,秋季为100.15 μg/m3。不同季节中ρPM10和ρPM2.1均存在较好的相关性,夏季相关性最好,相关系数为0.952;秋季次之,相关系数为0.783;春季相对较差,相关系数为0.613。城市不同功能区之间ρPM2.1和ρPM10的质量浓度值差异很大,交通源>工业区>商业区>风景区。城市不同功能区的质量浓度谱分布基本一致,均为双峰型分布,峰值分别位于0.43~0.65 μm/m3和9.0~10.0 μm/m3。南京市春、夏、秋三个季节大气粒子质量浓度谱为双峰分布,粒子主要集中在0.43~3.3 μm/m3的粒径段。江北工业区ρPM10和ρPM2.1质量浓度的相关系数为0.814,略高于鼓楼商业区的0.797。  相似文献   

7.
为了研究海南省三亚地区冬春季大气污染状况,于2011年12月—2013年4月的冬春季节在三亚鹿回头村(监测点位于三亚市郊,三面临海,周围没有工业污染源)开展了大气主要污染物(NOx、O3、PM2.5)的连续监测,利用观测数据对三亚地区冬春季大气污染变化特征进行分析.结果表明:三亚地区大气污染物浓度均低于国家一级标准的浓度值,NO、NO2、NOx、O3、PM2.5质量浓度的日平均值(平均值±标准差)分别为(2.1±2.2)、(5.2±3.4)、(7.3±3.8)、(59.8±28.4)和(17.5±14.3)μg·m-3.在污染物的日变化方面,NOx、PM2.5呈现典型的双峰型,其峰值分别出现在08:00和17:00,峰谷在13:00;O3的日变化为单峰型,峰值出现在13:00.通过后向轨迹分析发现,三亚地区大气污染物受局地源排放和外源输送的共同影响,来自陆地的气流易造成污染物的积累,而来自海上的气流则有利于污染物的清除.  相似文献   

8.
使用Anderson-Ⅱ型9级撞击采样器测量了南京市鼓楼商业区、江北工业区、钟山风景区和宁六高速公路交通源春、夏、秋三季的大气气溶胶质量浓度。分析结果表明:南京市PM2.1和PM10的质量浓度存在明显的季节变化,秋季>春季>夏季;ρPM10春季为167.47 μg/m3,夏季为 85.99 μg/m3,秋季为238.99 μg/m3;ρPM2.1春季为59.66 μg/m3,夏季为42.80 μg/m3,秋季为100.15 μg/m3。不同季节中ρPM10和ρPM2.1均存在较好的相关性,夏季相关性最好,相关系数为0.952;秋季次之,相关系数为0.783;春季相对较差,相关系数为0.613。城市不同功能区之间ρPM2.1和ρPM10的质量浓度值差异很大,交通源>工业区>商业区>风景区。城市不同功能区的质量浓度谱分布基本一致,均为双峰型分布,峰值分别位于0.43~0.65 μm/m3和9.0~10.0 μm/m3。南京市春、夏、秋三个季节大气粒子质量浓度谱为双峰分布,粒子主要集中在0.43~3.3 μm/m3的粒径段。江北工业区ρPM10和ρPM2.1质量浓度的相关系数为0.814,略高于鼓楼商业区的0.797。  相似文献   

9.
武汉作为中部地区高湿度代表城市,大气污染严重,霾天气多发,但有关该地区大气能见度与PM2.5浓度及相对湿度(RH)的定量关系尚不明确。利用2014年9月—2015年3月武汉地区逐时能见度、相对湿度及颗粒物质量浓度观测数据,研究分析了武汉大气能见度与PM2.5浓度及相对湿度的关系,并进行能见度非线性预报初探,得到以下结论:武汉霾时数发生比例高,霾的发生和加重是能见度降低的主要原因;能见度降低伴随大量细粒子产生和累积,这是武汉大气能见度恶化的重要诱因。细颗粒物浓度与相对湿度共同影响和制约大气能见度变化,高湿高浓度时能见度显著下降,湿情景下(RH≥40%),能见度恶化主要是由湿度增高诱使细颗粒物粒径吸湿增长导致其散射效率增大造成的。当RH >90%时,能见度随湿度升高成线性递减,相对湿度每升高1%,武汉平均能见度降低0.568 km。而干情景下(RH<40%),能见度迅速降低的关键因素是PM2.5质量浓度升高。在城市大气细粒子污染背景下,能见度与相对湿度成非线性关系,这主要与PM2.5对能见度的影响及吸湿性颗粒物的散射效率变化有关。PM2.5浓度与能见度成幂函数非线性关系,80%≤RH<90%湿度区段下相关性最强。PM2.5浓度对能见度的影响敏感阈值是随着湿度升高而减小的,干情景下能见度10 km对应的PM2.5浓度阈值为70 μg/m3,湿情景下该阈值为18—55 μg/m3。当PM2.5质量浓度低于约40 μg/m3时,继续降低PM2.5可显著提高武汉大气能见度。预报试验表明,基于神经网络方法建立大气能见度非线性预报模型是可行的,预报能见度相关系数为0.86,均方根误差为1.9 km,能见度≤10 km的TS评分为0.92。网络模型具有较高预报性能,对霾的判别有较高准确性,为衔接区域环境气象数值预报模式,建立大气能见度精细化动力统计模型提供参考依据。  相似文献   

10.
南京北郊2011年春季气溶胶粒子的散射特征   总被引：3，自引：2，他引：1       下载免费PDF全文
利用南京北郊2011年春季积分浊度仪的观测资料,结合PM2.5质量浓度、能见度和常规气象资料,分析了南京北郊春季气溶胶散射系数的变化特征、散射系数与PM2.5质量浓度和能见度的关系。结果表明,观测期间气溶胶散射系数平均值为311.5±173.3 Mm-1,小时平均值出现频率最高的区间为100~200 Mm-1;散射系数的日变化特征明显,总体为早晚大,中午及午后小。散射系数与PM2.5质量浓度的变化趋势基本一致,但与能见度呈负相关关系。霾天气期间散射系数日平均值为700.5±341.4 Mm-1,最高值达到近1 900 Mm-1;结合地面观测资料、NCEP/NCAR再分析资料和后向轨迹模式分析显示,霾期间气块主要来自南京南部和东南方向。  相似文献   

11.
Products and mechanisms of the reaction between the nitrate radical (NO3) and three of the most abundant reduced organic sulphur compounds in the atmosphere (CH3SCH3, CH3SH and CH3SSCH3), have been studied in a 480 L reaction chamber using in situ FT-IR and ion chromatography as analytical techniques. In the three reactions, methanesulphonic acid was found to be the most abundant sulphur containing product. In addition the stable products SO2, H2SO4, CH2O, and CH3ONO2 were identified and quantified and thionitric acid-S-methyl ester (CH3SNO2) was observed in the i.r. spectrum from all of the three reactions. Deuterated dimethylsulphide (CD3SCD3) showed an isotope effect on the reaction Deuterated dimethylsulphide (CD3SCD3) showed an isotope effect on the reaction rate constant (kH/kD) of 3.8±0.6, indicating that hydrogen abstraction is the first step in the NO3+CH3SCH3 reaction, probably after the formation of an inital adduct.Based on the products and intermediates identified, reaction mechanisms are proposed for the three reactions.  相似文献   

12.
The pK 1 * and pK 2 * of H2SO3 have been determined in NaCl solutions as a function of ionic strength (0.1 to 6 m) and temperature (5 and 25 °C). The extrapolated values in water were found to be in good agreement with literature data. The experimental results have been used to determine the Pitzer interaction parameters for SO2, HSO 3 - and SO 3 - in NaCl solutions. The resultant parameters for NaHSO3 and Na2SO3 were found to be in reasonable agreement with the values for NaHSO4 and Na2SO4. It, thus, seems reasonable to assume that the interactions of Mg2+ and Ca2+ with HSO 3 - and SO 3 - can be estimated from the values with HSO 4 - and SO 4 - until experimental values are available. Measurements of pK 1 * and pK 2 * in artificial seawater were found to be in good agreement with the calculated values using the derived Pitzer parameters. It is, thus, possible to make reasonable estimates of the activity coefficients of HSO 3 - and SO 3 - ions and pK 1 * and pK 2 * for the ionization of H2SO3 in marine aerosols.  相似文献   

13.
对临安大气本底站2003-2004年冬、夏季二氧化氮(NO2)、二氧化硫(SO2)、臭氧(O3)进行了分析.结果表明:冬季NO2和SO2平均体积分数分别为19.48×10-9和35.74 x10-9,而夏季的平均体积分数分别为4.81×10-9和8.12×10-9,冬季高于夏季;O3在夏季的平均体积分数为33.55×10-9,略高于冬季的25.44×10-9;夜间NO2和SO2体积分数比白天高,并且NO2呈明显的单峰单谷型分布,O3也呈单峰型但峰值出现在白天.NO2、SO2体积分数存在着明显的“假日效应”,假日比非假日低,周五高于假日和非假日;但O3体积分数没有明显的假日效应.降水对SO2有明显的清除作用,但对NO2的清除作用不明显.与风向对比发现,夏季高体积分数的NO2、SO2都受到NW、WNW风的影响,冬季则分别受NE和SW、SSW风的影响;而O3受风向的影响较复杂,与局地光化学反应有关.  相似文献   

14.
In a nighttime system and under relatively dry conditions (about 15 ppm H2O), the reaction mixture of NO2, O3, and NH3 in purified air turns out to result in the formation of nitrous oxide (N2O). The experiments were performed in a continuous stirred flow reactor, in the concentration region of 0.02–2 ppm.N2O is thought to arise through the heterogeneous reaction of gaseous N2O5 and absorbed NH3 at the wall of the reaction vessel % MathType!MTEF!2!1!+-% feaafeart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqaqpepeea0xe9qqVa0l% b9peea0lb9sq-JfrVkFHe9peea0dXdarVe0Fb9pgea0xa9pue9Fve9% Ffc8meGabaqaciGacaGaaeqabaWaaeaaeaaakeaatCvAUfKttLeary% qr1ngBPrgaiuaacqWFOaakcqWFobGtcqWFibasdaWgaaWcbaGae83m% amdabeaakiab-LcaPmaaBaaaleaacqWFHbqyaeqaaOGaey4kaSIaai% ikaiab-5eaonaaBaaaleaacqWFYaGmaeqaaOGae83ta80aaSbaaSqa% aiab-vda1aqabaGccaGGPaWaaSbaaSqaaiaadEgaaeqaaOGaeyOKH4% Qae8Nta40aaSbaaSqaaiab-jdaYaqabaGccqWFpbWtcqGHRaWkcqWF% ibascqWFobGtcqWFpbWtdaWgaaWcbaGae83mamdabeaakiabgUcaRi% ab-HeainaaBaaaleaacqWFYaGmaeqaaOGae83ta8eaaa!59AC!\[(NH_3 )_a + (N_2 O_5 )_g \to N_2 O + HNO_3 + H_2 O\]In principle, there is competition between this reaction and that of adsorbed H2O with N2O5, resulting in the formation of HNO3. At high water concentrations (RH>75%), no formation of N2O was found. Although the rate constant of adsorbed NH3 with gaseous N2O5 is much larger than that of the reaction of adsorbed H2O with gaseous N2O5, the significance of the observed N2O formation for the outside atmosphere is thought to be dependent on the adsorption properties of H2O and NH3 on a surface. A number of NH3 and H2O adsorption measurements on several materials are discussed.  相似文献   

15.
Results from numerical investigations regarding the exchange of HNO3, NH3, and NH4NO3 between the atmosphere and the biosphere are presented. The investigations were performed with a modified inferential method which is based on the generally accepted micrometeorological ideas of the transfer of momentum, sensible heat and matter near the Earth's surface and the chemical reactions among these nitrogen compounds. This modified inferential method calculates the micrometeorological quantities (such as the friction velocity and the fluxes of sensible and latent heat), the height-invariant fluxes of the composed chemically conservative trace species with group concentrationsc 1=[HNO3]+[NH4NO3] (total nitrate),c 2=[NH3]+[NH4NO3] (total ammonia), andc 3=[HNO3]-[NH3] as well as the fluxes of the individual nitrogen compounds. The parameterization of the fluxes is based on the flux-gradient relationships in the turbulent region of the atmospheric surface layer. The modified inferential method requires only the data of wind velocity, temperature, humidity and concentrations (HNO3, NH3, and NH4NO3) measured at a reference height by stations of a monitoring network.  相似文献   

16.
O_3和PM_(2.5)是影响长三角地区空气质量的主要污染物。利用2016年33个城市大气环境监测站6项污染物的小时浓度及4个省会城市的气象数据进行统计分析,研究了该地区O_3和PM_(2.5)浓度的时空分布特征及其影响因素。结果表明:长三角地区O_3年平均浓度为50～73μg·m~(-3),平均为61μg·m~(-3);除芜湖和宣城外,其余31城市均存在不同程度的超标状况,超标率为0.34%～18.86%,平均为5.68%。O_3在5月和9月达到浓度高值;四季O_3日变化均呈单峰型,峰值出现在15∶00,夏季O_3峰值浓度最高值为157μg·m~(-3)。O_3浓度沿海城市整体高于内陆城市;夏季宿迁—淮安—滁州片区O_3污染较重。O_3与NO_2、CO显著负相关,且与NO_2相关性较强;O_3与气温、日照时数显著正相关,与相对湿度、降水呈负相关。PM_(2.5)年平均浓度在25～62μg·m~(-3)范围内,平均为49μg·m~(-3);各城市均出现PM_(2.5)超标,滁州PM_(2.5)超标率最大,为23.91%。PM_(2.5)在3月和12、1月达到浓度峰值;其日变化呈双峰型,09∶00—10∶00和22∶00—23∶00达到峰值。冬季徐州PM_(2.5)浓度最高,为102μg·m~(-3)。PM_(2.5)与NO_2、CO、SO_2、PM_(10)显著正相关,与气温、风速、降水负相关。  相似文献   

17.
An instrument for measuringtropospheric OH/HO2 radicals by laser-inducedfluorescence developed in our laboratory is presentedin detail. It is based on FAGE (fluorescence assay bygas expansion) technique and OH is both excited anddetected at 308 nm corresponding to its A-X(0,0) band.The alignment of the laser beam, the design of thesample gas inlet, and the devices for the fluorescencedetection are optimized so as to reduce the backgroundsignal while keeping the OH sensitivity as high aspossible. A thermalized position of the expanding gasbeam is probed in our system and we did not observe asevere decrease of the HOx sensitivities under humidconditions. An optical fiber is used for deliveringthe laser light to the fluorescence detection cellmounted outside at a high position. Thus the laserbeam alignment is by far simplified and is made highlyreproducible, once settled properly. For thecalibration, two methods are employed: a system withlaser absorption measurements of OH and a system ofsimultaneous photolysis of H2O and O2. Thecalibration factors are compared well within thecombined uncertainty. Using the latter system, theconversion efficiency of HO2 to OH by NO additionis measured to be around 90%. The detection limitsfor OH and HO2 (S/N = 2) are estimated to be3.3 × 106 and 3.6 × 106cm–3 at noon,respectively, with an integration time of 1 min. Theresults of test observations at our institute are alsopresented.  相似文献   

18.
Simultaneous measurements of peroxy and nitrate radicals at Schauinsland   总被引：3，自引：0，他引：3  
We present simultaneous field measurements of NO3 and peroxy radicals made at night in a forested area (Schauinsland, Black Forest, 48° N, 8° N, 1150 ASL), together with measurements of CO, O3, NO x , NO y , and hydrocarbons, as well as meteorological parameters. NO2, NO3, HO2, and (RO2) radicals are detected with matrix isolation/electron spin resonance (MIESR). NO3 and HO2 were found to be present in the range of 0–10 ppt, whilst organic peroxy radicals reached concentrations of 40 ppt. NO3, RO2, and HO2 exhibited strong variations, in contrast to the almost constant values of the longer lived trace gases. The data suggest anticorrelation between NO3 and RO2 radical concentrations at night.The measured trace gas set allows the calculation of NO3 and peroxy radical concentrations, using a chemical box model. From these simulations, it is concluded that the observed anthropogenic hydrocarbons are not sufficient to explain the observed RO2 concentrations. The chemical budget of both NO3 and RO2 radicals can be understood if emissions of monoterpenes are included. The measured HO2 can only be explained by the model, when NO concentrations at night of around 5 ppt are assumed to be present. The presence of HO2 radicals implies the presence of hydroxyl radicals at night in concentrations of up to 105 cm–3.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号