洞庭湖区一次重度空气污染过程成因分析

利用AQI和PM_(2. 5)质量浓度、地面气象要素、NCEP、ERSST_V3、GBL等资料,对2016年12月29日至2017年1月5日洞庭湖区一次重度空气污染过程成因进行了分析。结果表明,静稳天气形势下的累积效应和本地持续升温、降压、增湿、小风导致污染物浓度不断增加。本地风速与雨量对污染物浓度产生显著影响。降温前风速明显加大,有利于污染物快速扩散。湿度增加有利于污染物吸湿性增长,但高湿易引起降水有利于污染物的湿清除。此次重度空气污染过程中大气稳定度为中性或稳定,14:00混合层高度逐渐降低且重度空气污染日降至100 m以下。污染物空间分布与主导风向和污染通道密切相关。气流后向轨迹分析表明,洞庭湖区各地气流来源和影响路径差异明显,且存在大范围区域性同步污染现象。北方外来污染源是洞庭湖区重要的污染面源,本地工业污染排放点源和地理条件也是洞庭湖区空气污染物空间分布差异的重要因素。     

成渝地区一次区域重污染过程来源解析及减排效果研究

基于嵌套网格空气质量预报模式(NAQPMS)及耦合的污染来源追踪模块模拟2017年12月16日至2018年1月3日成渝地区一次区域重污染过程,定量解析成渝地区主要城市PM2.5来源,评估过程中应急减排的成效。结果表明,天气静稳和风向辐合是造成此次重污染过程的重要因素,污染峰值阶段,成渝地区多个城市PM2.5日均质量浓度超过150μg/m3,达到重度污染级别。污染过程中,成都市PM2.5本地排放的贡献率为42%,眉山和德阳贡献率将近30%;重庆市PM2.5本地排放的贡献率为60%,外来输送以湖北、湖南和其他地区为主,贡献率为24%,成都和重庆市的工业源和交通源的贡献最大。区域联防联控应急减排对成渝各城市空气质量改善效果显著,成渝地区PM2.5浓度降低率为5%~11%,对于未实施应急预警方案的地区(如眉山市)受周边城市减排影响,浓度降低可达6%。     

江淮地区秋季一次典型污染过程分析

结合2018年10月15—20日国控站点监测数据、气象资料及激光雷达走航观测结果,对江淮地区一次重度污染过程进行了分析。利用拉格朗日粒子扩散模型和拉格朗日混合单粒子轨迹模型定性分析了区域污染来源,分别基于激光雷达和空气站实测数据提出了外来源占比的估算方法,结合嵌套网格空气质量预报模式(NAQPMS)的源解析结果,对比分析了外来源占比。以淮北市为例,结合NAQPMS和单颗粒气溶胶质谱的PM2.5在线源解析结果,对比分析此次污染过程的行业来源。结果表明,本地污染累积时段,主要以燃煤和机动车尾气混合源为主(占比>70%);受北方污染输送时段,机动尾气占比显著升高,从19.4%(16日00:00)升至66.7%(17日11:00),淮北市、蚌埠市、合肥市3个城市污染物外来输送占比分别为52.2%~70.6%、48.8%~58.8%、41.5%~59.0%。     

秸秆焚烧对哈尔滨市灰霾天气的影响

2015年11月1—4日,哈尔滨市及周边地区发生了连续的灰霾天气,颗粒物浓度急剧升高。污染发生时,监测仪器均布设在哈尔滨市区上风向30 km处(哈尔滨市双城区)并开展了连续96 h的监测分析。综合利用气象观测资料,3D可视激光雷达监测资料及地面空气污染监测资料分析了灰霾天气发生的气象条件和污染边界层特征,根据哈尔滨市双城区大气污染物排放源谱库对主要成分进行来源解析,结合颗粒物质量浓度和气象条件研究了秸秆焚烧对灰霾天气的影响。结果表明,灰霾天气持续期间,夜间生物质燃烧源成为该地区颗粒物的第二大源;秸秆焚烧产生的大气污染物,由于地面长时间静风,污染边界层降低等原因,致使本地污染物累积、不易扩散,加剧了本次污染。     

京津冀地区臭氧污染特征与来源分析

2013—2014年京津冀地区13个城市O_3日最大8 h平均值第90百分位数平均为155~162μg/m3,京津冀地区已成为全国O_3污染最严重的地区之一,京津冀地区O_3污染程度有所加重。京津冀地区夏季O_3浓度高,冬季浓度低,O_3质量浓度较高的月份集中在5—9月,12月—次年1月浓度最低。在O_3污染较重的夏季,每日6:00~7:00,O_3质量浓度最低,15:00~16:00 O_3浓度最高。在空间分布上郊区点位的O_3质量浓度往往高于主城区点位。京津冀区域夏季O_3小时浓度和NO2浓度呈高度负相关关系,和其他污染物无明显的相关性。O_3质量浓度和气温呈显著的正相关关系,和大气相对湿度呈显著的负相关关系。京津冀区域O_3的主要来源为NOX和VOC等一次污染物在日光照射下发生光化学反应而产生,控制O_3前体物的源排放,尤其是控制好VOC的排放是控制O_3污染的有效途径。     

G20峰会期间长三角区域臭氧变化及管控效果评估

为了研究2016年二十国集团领导人峰会(G20峰会)期间长三角区域臭氧(O3)变化特征,评估管控措施对O3浓度的影响,利用2016年8月10日至9月20日杭州及周边地区的空气质量监测数据、气象数据以及排放清单数据,分析了O3和NO2浓度及气象条件的时空分布特征,研究了不同管控区域不同保障时期O3浓度的时空变化和O3敏感控制区的改变。结果表明:峰会保障期间对于一次排放污染物和细颗粒物的管控措施效果明显,但核心区的O3质量浓度高于严控区和管控区,分别高出11. 2、9. 2μg/m^3。日间的NOx管控导致O3日变化幅度增高接近50μg/m^3。在峰会保障期间,卫星数据和站点观测结果显示核心区O3由VOCs控制区转为NOx-VOCs协同控制区,整个长三角区域的O3生成对于NOx排放量更为敏感。管控措施越强,核心区的O3生成对于NOx排放越敏感,且O3浓度与NOx浓度的相关性越强。对NOx和VOCs的协同控制降低排放,是关系O3浓度管控的一项重要工作。     

冷空气南下对江苏省重污染天气过程的影响

根据2013—2015年江苏省重污染(重度污染和严重污染)个例,分析冷空气南下对重污染天气过程的影响机制和特征。将冷空气南下过程按路径分为东路、中路和西路,分别统计了不同路径冷空气影响江苏的特征,以及冷空气背景下重污染发生时的气象条件,总结了不同路径冷空气对污染物浓度日增幅的影响,探讨了冷空气对江苏省大气污染的影响机制。研究表明,江苏省的重污染天气主要发生在中路冷空气影响时,东路冷空气影响概率相对较小;中路、西路易出现区域性、连续性重污染;东路多单站点污染,连续污染概率较小。重污染日的高空冷空气主体偏北,中低层为槽后脊前西北气流或有弱切变,地面处于冷高压前部;中路、西路冷空气对污染的输送贡献大于东路,对上游污染呈负输送,如有强逆温、小风速的"静稳"天气,重污染仍可能加剧;重污染天气的发生,是本地污染、外源输送和局地不利污染扩散的气象条件共同作用造成的。     

基于激光雷达分析2020年冬季镇江地区一次大气污染过程

利用气溶胶激光雷达观测结果,结合环境监测站污染物浓度数据、气象观测资料及HYSPLIT后向轨迹模式结果,综合分析2020年1月17—22日镇江市一次大气污染过程。结果显示,此次污染过程前期天气形势稳定,不利于污染物的清除及扩散,后期受偏北风影响,北方污染物向镇江输送,使得本地污染物持续累积,污染不断加重。特征雷达图分析表明此次污染为以PM2.5为主的二次污染。激光雷达显示污染日消光系数为0.0~0.9 km-1,消光系数垂直廓线日变化特征明显,气溶胶粒子主要堆积在0.6 km高度以下,并且很好地揭示了污染气团从高空逐渐下沉最终与本地污染叠加的过程,与HYSPLIT模式解析的污染气团来源结果基本一致。     

2022年青岛市沿海区域臭氧污染特征及传输影响分析

基于2022年1—12月青岛市沿海区域臭氧（O₃）自动监测数据和气象观测资料，对O₃污染变化特征及影响因素进行了分析，结合后向轨迹聚类与潜在源区分析等方法，对O₃外来输送通道及潜在源分布情况进行分析研究。结果表明：青岛市沿海区域O₃污染主要集中在4—10月份，日变化特征呈单峰单谷趋势，峰值出现在15：00—16：00；气象因素中，地面短波辐射对O₃浓度变化的相对贡献最大，偏南风易导致O₃污染；受二氧化氮（NO₂）滴定作用以及海陆风转换影响，沿海区域O₃峰值与谷值均滞后青岛城区1 h左右；O₃生成整体处于VOCs控制区，1-丁烯、正丁烷与异戊烷是O₃污染期间导致O₃浓度上升的关键组分；O₃污染的主要潜在源区为长三角北部和黄海近岸海域，以及山东中南部地区。     

大连市夏季近地面臭氧污染数值模拟和控制对策研究

通过区域空气质量模型CAMx对大连市2015年8月近地面臭氧(O_3)污染进行模拟,探讨了O_3及其生成前体物(NOx和VOCs)的来源,O_3生成控制区,并根据敏感性分析结果对前体物排放的控制效果进行了定量评估。结果表明:本地NOx排放对大连地区的NOx浓度贡献占90%以上,本地VOCs排放对大连地区的VOCs浓度贡献占80%以上,而本地NOx和VOCs排放对大连地区O_3浓度贡献仅占29%;大连市整体上为VOCs控制区,控制VOCs能有效降低O_3污染,还能有效削减O_3的峰值浓度;通过敏感性分析结果计算得出,削减大连本地工业源VOCs和民用源VOCs能够有效降低大连地区O_3浓度,削减10%的工业源VOCs能使市区O_3平均浓度降低2%左右,削减10%的民用源VOCs能使大连市区平均O_3浓度降低1%左右。建议NOx与VOCs削减比例为1∶2,对大连市O_3和PM2.5污染进行协同控制。     

Evaluation of the urban/rural particle-bound PAH and PCB levels in the northern Spain (Cantabria region)

The aim of the present study was to evaluate the polycyclic aromatic hydrocarbon (PAH) and polychlorinated biphenyl (PCB) levels in PM(10) and PM(2.5), at one rural and three urban sites in the Cantabria region (northern Spain). From all of these pollutants, benzo(a)pyrene is regulated by the EU air quality directives; its target value (1?ng/m(3)) was not exceeded. The concentration values of the studied organic pollutants at the studied sites are in the range of those obtained at other European sites. A comparison between the rural-urban stations was developed: (a) PAH concentration values were lower in the rural site (except for fluorene). Therefore, the contribution of local sources to the urban levels of PAHs seems relevant. Results from the coefficient of divergence show that the urban PAH levels are influenced by different local emission sources. (b) PCB rural concentration values were higher than those found at urban sites. Because no local sources of PCBs were identified in the rural site, the contribution of more distant emission sources (about 40?km) to the PCB levels is considered to be the most important; the long-range transport of PCBs does not seem to be significant. Additionally, local PAH tracers were identified by a triangular diagram: higher molecular weight PAHs in Reinosa, naphthalene in Santander and anthracene/pyrene in Castro Urdiales. A preliminary PAH source apportionment study in the urban sites was conducted by means of diagnostic ratios. The ratios are similar to those reported in areas affected by traffic emissions; they also suggest an industrial emission source at Reinosa.     

Physical Modeling of Emissions from Naturally Ventilated Underground Parking Garages

The dispersion of pollutants from naturally ventilated underground parking garages has been studied in a boundary layer wind tunnel. Two idealized model setups have been analysed, one was simulating pollutant dispersion around an isolated rectangular building and one was representing dispersion in a finite array of idealized building blocks. Flow and dispersion close to modelled ground level emission sources was measured. The results illustrate the complexity of the flow around buildings and provide insight in pollutant transport from ground level sources located directly on building surfaces. As a result, areas critical with respect to high pollutant concentrations could be visualized. Particularly, the results show high concentration gradients on the surface of the buildings equipped with modelled emission sources. Inside the boundary layers on the building walls, a significant amount of pollutants is transported to upwind locations on the surface of the building. The paper documents the potential of physical modelling to be used for the simulation and measurement of dispersion close to emission sources and within complex building arrangements.     

River water quality and pollution sources in the Pearl River Delta, China

Some physicochemical parameters were determined for thirty field water samples collected from different water channels in the Pearl River Delta Economic Zone river system. The analytical results were compared with the environmental quality standards for surface water. Using the SPSS software, statistical analyses were performed to determine the main pollutants of the river water. The main purpose of the present research is to investigate the river water quality and to determine the main pollutants and pollution sources. Furthermore, the research provides some approaches for protecting and improving river water quality. The results indicate that the predominant pollutants are ammonium, phosphorus, and organic compounds. The wastewater discharged from households in urban and rural areas, industrial facilities, and non-point sources from agricultural areas are the main sources of pollution in river water in the Pearl River Delta Economic Zone.     

A source study of atmospheric polycyclic aromatic hydrocarbons in Shenzhen, South China

Air pollution has become a serious problem in the Pearl River Delta, South China, particularly in winter due to the local micrometeorology. In this study, atmospheric polycyclic aromatic hydrocarbons (PAHs) were monitored weekly in Shenzhen during the winter of 2006. Results indicated that the detected PAHs were mainly of vapor phase compounds with phenanthrene dominant. The average vapor phase and particle phase PAHs concentration in Shenzhen was 101.3 and 26.7 ng m^???3, respectively. Meteorological conditions showed great effect on PAH concentrations. The higher PAHs concentrations observed during haze episode might result from the accumulation of pollutants under decreased boundary layer, slower wind speed, and long-term dryness conditions. The sources of PAHs in the air were estimated by principal component analysis in combination with diagnostic ratios. Vehicle exhaust was the major PAHs source in Shenzhen, accounting for 50.0% of the total PAHs emissions, whereas coal combustion and solid waste incineration contributed to 29.4% and 20.6% of the total PAHs concentration, respectively. The results clearly indicated that the increasing solid waste incinerators have become a new important PAHs source in this region.     

Simulation of Wind Circulation and Pollutant Diffusion Over the Pearl River Delta Region

Changes in urban surface areas and population growth have significantly affected the weather and environment. Emissions of nitrogen oxides are increasing in the Pearl River Delta region. Nitrogen compounds emitted by factories and motor vehicles are the major sources of nitric pollution. To study the impacts of urbanization and the relationship between pollutant diffusion and the atmospheric environment, the nonhydrostatic mesoscale forecast model MM5 (v3.73), which was developed by Penn State University and the National Center of Atmospheric Research, and a mass continuity equation for air pollutants, were used in this study. Two experiments were designed. One experiment (BE) applied horizontal grid resolutions of 27, 9, 3, and 1?km in four nested domains. The other experiment adopted new land-use data (in domain 4) directly retrieved from Landsat Thematic Mapper imagery to replace the 1980s data of the United States Geological Survey in BE. A 48-h simulation (from 0000?UTC on 21 October to 0000?UTC on 23 October 2008) was conducted, with the first 12?h being the spin-up time and the remaining 36?h being the effective simulation, so as to capture the diurnal features of the thermally induced winds associated with the land–sea breeze and urban heat island circulations. The different results obtained from the two tests for wind circulation and air pollution dispersion and transportation in the Pearl River Delta region were analyzed. The simulated results show that the both experiments can well simulate land–sea breeze circulation and remarkable land–sea breeze evolution, comparing with observation data. The height of the PBL had a significant diurnal cycle. The structure of the wind field can obviously impact the dispersion of the NO _x in three dimensions. Nitrogen oxides mainly diffused along the dominant wind direction (east or southeast wind), therefore the majority of the pollutants accumulated in the northwest region of the fine domain in both simulation experiments. However, it induced the pollutants concentration in an irregular pattern due to the fine-resolution grid spaces and complicated inland wind field in the northwest area of the inner domain. Moreover, increasing the proportion of urban surface caused sensible heat flux increase, latent heat flux decrease and humility reducing relatively in the region of urban surface characteristics apparently. Urbanization will cause pollution accumulated severely over the urban surface.     

颗粒物激光雷达在大气复合污染立体监测中的应用

针对由于局地污染、沙尘输入、外源性输入与局地污染物相互叠加所导致的3种灰霾污染发生过程,分别选取3个典型案例,采用颗粒物激光雷达对污染物的时空分布特征进行解析。研究发现,在局地污染发生时,污染物从地面开始垂直向上扩散,扩散高度约1 km。重度污染过程中,气溶胶的日均垂直消光系数随高度的变化背离指数衰减特征,800 m高度处出现消光系数的极大值层,极大值超过2.5 km-1,800 m以下消光系数近乎常数,约为0.3 km-1。这说明,重污染过程中,有一层较厚重的颗粒物分布,使近地面污染物在垂直方向的扩散能力减弱,形成积累效应,造成大面积空气混浊。当有外源性沙尘输入时,激光雷达能够清晰地监测到污染团输入的全过程。沙团突然出现在高空2~3 km。污染团退偏振度较大,超过0.3。随着沙尘粒子的重力沉降,沙团的轮廓在垂直方向上不断地增大。沙团的输入,导致近地面粗颗粒质量浓度的增加幅度明显大于细颗粒。在第3个案例中,激光雷达清晰地监测到高空1.8~3 km突然出现含有大量球形细颗粒的污染团,同时还发现此污染团与近地面的污染物有不同的演化特征。近地面污染物随时间垂直向上扩散,12:00左右扩散高度超过1.8 km。而高空的污染团逐渐沉降进入边界层内,与近地面扩散的污染物相互混合,共同导致本地的灰霾天气。综上所述,激光雷达可以清晰地捕获污染物的垂直结构特征,对不同的致霾过程进行立体解析,实现对大气复合污染的监测和机理研判。     

西太平洋台风“苏迪罗”对我国珠三角地区臭氧污染影响研究

通过资料分析和数值模拟开展了2015年8月1日—10日台风“苏迪罗”对珠三角地区臭氧（O₃）污染影响的机理研究。结果表明，2015年8月5—8日，在台风接近登陆点的过程中，台风外围天气导致了高温、高辐射和静小风等气象条件，促进了光化学反应的进行和污染物的局地积累。同时，高温、高辐射等气象条件加剧了植被源区生物源挥发性有机物（BVOCs）的排放。采用化学传输模式模拟发现，植被BVOCs对O₃污染的贡献最高可达24×10^-9。结合拉格朗日粒子扩散模式（LPDM）探索了影响珠三角地区的主导气团，发现珠三角城市地区和高BVOCs源区存在交互传输的现象。污染期间，高BVOCs源区的一次排放产物（BVOCs）和二次产物(O₃)经区域输送加剧了珠三角地区O₃的污染。此外，研究发现台风外围条件下珠三角内陆盛行的偏北风与海陆热力差异引起的海风在沿海地区辐合，造成污染物局地积累，加剧并延长了O₃污染。研究有利于加强对O₃污染机理的认识，进而更好地采取针对性措施，有助于减小O₃污染带来的危害。     

污染源减排对长三角区域冬季细颗粒物污染的敏感性研究

为了进一步精准有效地降低细颗粒物浓度,针对长三角区域细颗粒物PM2.5浓度,选取8个省级区域的5种污染物为减排目标,设定5个基准排放情景,采用CMAQ-DDM敏感性技术分别进行敏感性分析。结果表明,冬季长三角区域PM2.5污染受区域内的4个省级区域一次PM2.5排放影响最大,区域外的排放影响主要来自河南省和山东省的氨气和一次PM2.5。分别削减本地60%一次PM2.5的排放,安徽省PM2.5平均质量浓度下降了23. 24μg/m^3,江苏省下降了18. 32μg/m^3,上海市下降了15. 17μg/m^3,浙江省下降了9. 07μg/m3。综合各省(市)浓度响应曲线,最大排放因子均为本地一次PM2.5,削减20%左右存在敏感性最大值,削减60%之后浓度曲线趋于平缓,其他因子削减40%以后PM2.5浓度下降逐渐明显,对最后一位排放因子的响应则比较平缓。