Investigating the Transport Mechanism of PM2.5 Pollution during January 2014 in Wuhan,Central China

Severe haze pollution that occurred in January 2014 in Wuhan was investigated. The factors leading to Wuhan’s PM_2.5 pollution and the characteristics and formation mechanism were found to be significantly different from other megacities, like Beijing. Both the growth rates and decline rates of PM_2.5 concentrations in Wuhan were lower than those in Beijing, but the monthly PM_2.5 value was approximately twice that in Beijing. Furthermore, the sharp increases of PM_2.5 concentrations were often accompanied by strong winds. A high-precision modeling system with an online source-tagged method was established to explore the formation mechanism of five haze episodes. The long-range transport of the polluted air masses from the North China Plain (NCP) was the main factor leading to the sharp increases of PM_2.5 concentrations in Wuhan, which contributed 53.4% of the monthly PM_2.5 concentrations and 38.5% of polluted days. Furthermore, the change in meteorological conditions such as weakened winds and stable weather conditions led to the accumulation of air pollutants in Wuhan after the long-range transport. The contribution from Wuhan and surrounding cities to the PM_2.5 concentrations was determined to be 67.4% during this period. Under the complex regional transport of pollutants from surrounding cities, the NCP, East China, and South China, the five episodes resulted in 30 haze days in Wuhan. The findings reveal important roles played by transregional and intercity transport in haze formation in Wuhan.     

2020年新冠肺炎疫情管控期江苏省大气污染物浓度变化特征

利用江苏省大气环境监测站点的大气污染物监测数据,分析了2020年初新冠肺炎疫情管控期间(2—3月)主要大气污染物浓度的变化特征。结果显示,相比于2019、2020年疫情管控期间PM_2.5、PM₁₀、NO₂、SO₂、CO浓度的全省平均降幅分别为37.5%、36.9%、31.9%、28.2%和21.2%。严格管控期的2月和生产恢复期的3月,江苏省十三市PM_2.5、PM₁₀浓度同比降幅大致相当,呈现出较好的时间连续性和空间均匀性。但各市臭氧浓度同比变化呈现出较大的时空差异。空间上,沿江以南城市南京、无锡、常州、苏州和镇江五市臭氧浓度明显上升,而其他城市臭氧浓度以下降为主;时间上,2月南京等九市臭氧浓度上升,3月徐州等八市臭氧浓度持平或者下降。假设未发生新冠肺炎疫情以及未采取为阻断疫情蔓延而实施的种种举措,在仅考虑近年来大气污染防治政策持续实施的情况下,与预期降幅相比,疫情管控对NO₂实况浓度降幅的影响最大,其次是PM_2.5     

The statistical characters of PM10 in Belgrade area

The concentrations of air pollutants depend on meteorological conditions and pollutant emission level. From the statistical properties of air pollutants the number of times the daily average concentrations exceed the assigned air quality standard (AQS) can be estimated, as well as the level of reduction of particle matter emission sources required to meet the AQS. In this paper three statistical distributions (lognormal, Weibull and type V Pearson distribution) were used to fit the complete set of PM₁₀ data for the Belgrade urban area during a three-year period (2003–2005). The method of moments and the method of least squares were both used to estimate the parameters of the three theoretical distributions. The type V Pearson distribution represented the PM₁₀ daily average concentration most closely. However, the parent distributions sometimes diverged in predicting a high PM₁₀ concentration and therefore asymptotic distributions of extreme values were used to fit the high PM₁₀ concentration distribution more correctly. This method can successfully predict the return period and exceedances over a critical concentration in succeeding years. The estimated emission source reduction of PM₁₀ to meet the assigned standard varied from 53% to 63% in the Belgrade urban area. The results provide useful information for air quality management and could be used to examine the similarities and differences among air pollution types in diverse areas.     

大气物理过程方案对PM2.5预报的敏感性试验

利用WRF-Chem大气化学模式,选择2015年12月中旬发生在我国的大范围空气污染过程,在采用同样化学方案条件下,针对模式中不同物理过程及其参数化方案开展了地面PM_(2.5)预报的敏感性试验。结果表明:该模式能较好展示此次PM_(2.5)污染的演变过程,与实况也较接近,但对青海经宁夏至内蒙的PM_(2.5)高值区出现了漏报现象,这可能是模式外边界未对污染物做更新所致。对地面PM_(2.5)的预报,各物理过程的敏感度不同,边界层(含近地面层)过程的影响要明显大于积云对流及微物理过程的影响,不同的参数化方案会造成不同的预报误差。边界层过程QNSE和与其配套的近地面层方案的组合是预报的较佳组合;而TEMF和与其配套的组合以及ACM2和Pleim-X的组合则不佳。合理的物理过程参数化方案有助于提高PM_(2.5)预报质量。模式预报对排放源也有适应过程,其Spin-up时间较气象要素长。     

Comparison of Ozone and PM2.5 Concentrations over Urban,Suburban, and Background Sites in China

Surface ozone (O₃) and fine particulate matter (PM_2.5) are dominant air pollutants in China. Concentrations of these pollutants can show significant differences between urban and nonurban areas. However, such contrast has never been explored on the country level. This study investigates the spatiotemporal characteristics of urban-to-suburban and urban-to-background difference for O₃ (Δ[O₃]) and PM_2.5 (Δ[PM_2.5]) concentrations in China using monitoring data from 1171 urban, 110 suburban, and 15 background sites built by the China National Environmental Monitoring Center (CNEMC). On the annual mean basis, the urban-to-suburban Δ[O₃] is ?3.7 ppbv in Beijing–Tianjin–Hebei, 1.0 ppbv in the Yangtze River Delta, ?3.5 ppbv in the Pearl River Delta, and ?3.8 ppbv in the Sichuan Basin. On the contrary, the urban-to-suburban Δ[PM_2.5] is 15.8, ?0.3, 3.5 and 2.4 μg m^?3 in those areas, respectively. The urban-to-suburban contrast is more significant in winter for both Δ[O₃] and Δ[PM_2.5]. In eastern China, urban-to-background differences are also moderate during summer, with ?5.1 to 6.8 ppbv for Δ[O₃] and ?0.1 to 22.5 μg m^?3 for Δ[PM_2.5]. However, such contrasts are much larger in winter, with ?22.2 to 5.5 ppbv for Δ[O₃] and 3.1 to 82.3 μg m^?3 for Δ[PM_2.5]. Since the urban region accounts for only 2% of the whole country’s area, the urban-dominant air quality data from the CNEMC network may overestimate winter [PM_2.5] but underestimate winter [O₃] over the vast domain of China. The study suggests that the CNEMC monitoring data should be used with caution for evaluating chemical models and assessing ecosystem health, which require more data outside urban areas.     

中国主要城市群在灰霾污染下的近地面风场特征

利用2015-2016年全国PM2.5质量浓度站点资料及CCMP(Cross Calibrated Multi-Platform)风场再分析资料,对中国华北、长三角、珠三角以及四川盆地主要城市在PM2.5污染下的近地面风场及其影响进行统计分析.结果表明:(1)近地面风速与PM2.5质量浓度表现为负相关,低风速有利于PM...     

A wedge-based approach to estimating health co-benefits of climate change mitigation activities in the United States

While it has been recognized that actions reducing greenhouse gas (GHG) emissions can have significant positive and negative impacts on human health through reductions in ambient fine particulate matter (PM_2.5) concentrations, these impacts are rarely taken into account when analyzing specific policies. This study presents a new framework for estimating the change in health outcomes resulting from implementation of specific carbon dioxide (CO₂) reduction activities, allowing comparison of different sectors and options for climate mitigation activities. Our estimates suggest that in the year 2020, the reductions in adverse health outcomes from lessened exposure to PM_2.5 would yield economic benefits in the range of $6 to $30 billion (in 2008 USD), depending on the specific activity. This equates to between $40 and $198 per metric ton of CO₂ in health benefits. Specific climate interventions will vary in the health co-benefits they provide as well as in potential harms that may result from their implementation. Rigorous assessment of these health impacts is essential for guiding policy decisions as efforts to reduce GHG emissions increase in scope and intensity.     

PM2.5 co-benefits of climate change legislation part 1: California’s AB 32

The Scoping Plan for compliance with California Assembly Bill 32 (Global Warming Solutions Act of 2006; AB 32) proposes a substantial reduction in 2020 greenhouse gas (GHG) emissions from all economic sectors through energy efficiency, renewable energy, and other technological measures. Most of the AB 32 Scoping Plan measures will simultaneously reduce emissions of traditional criteria pollutants along with GHGs leading to a co-benefit of improved air quality in California. The present study quantifies the airborne particulate matter (PM_2.5) co-benefits of AB 32 by comparing future air quality under a Business as Usual (BAU) scenario (without AB 32) to AB 32 implementation by sector. AB 32 measures were divided into five levels defined by sector as follows: 1) industrial sources, 2) electric utility and natural gas sources, 3) agricultural sources, 4) on-road mobile sources and 5) other mobile sources. Air quality throughout California was simulated using the UCD source-oriented air quality model during 12 days of severe air pollution and over 108 days of typical meteorology representing an annual average period in the year 2030 (10 years after the AB 32 adoption deadline). The net effect of all AB 32 measures reduced statewide primary PM and NO_x emissions by ~1 % and ~15 %, respectively. Air quality simulations predict that these emissions reductions lower population-weighted PM_2.5 concentrations by ~6 % for California. The South Coast Air Basin (SoCAB) experienced the greatest reductions in PM_2.5 concentrations due to the AB 32 transportation measures while the San Joaquin Valley (SJV) experiences the smallest reductions or even slight increases in PM_2.5 concentrations due to the AB 32 measures that called for increased use of dairy biogas for electricity generation. The ~6 % reduction in PM_2.5 exposure associated with AB 32 predicted in the current study reduced air pollution mortality in California by 6.2 %, avoiding 880 (560–1100) premature deaths per year for the conditions in 2030. The monetary benefit from this avoided mortality was estimated at $5.4B/yr with a weighted average benefit per tonne of $35 k/tonne ($23 k/tonne–$45 k/tonne) of PM, NO_x, SO_x, and NH₃ emissions reduction.     

关中5市环境空气质量特征与成因分析

基于国家生态环境部发布的环境空气质量监测数据等资料,采取调查研究与量化分析相结合的方法,对关中地区西安、渭南、咸阳、铜川、宝鸡5市空气质量的总体特征和空间差异进行研究.结果表明：颗粒污染物普遍严重超标,其中PM_2.5和PM₁₀分别超标91%和77%;空气污染具有明显的季节性,冬季的首要污染物是PM_2.5和PM₁₀,夏季的主要污染物是O₃;关中空气污染受地形、气象条件和工业排放、采暖、施工、道路扬尘、汽车尾气等人类活动综合影响,大气污染具有相似性,同时表现出一定的差异性.     

Investigating the Changes in Air Pollutant Emissions over the Beijing-Tianjin-Hebei Region in February from 2014 to 2019 through an Inverse Emission Method

In recent years, China has implemented several measures to improve air quality. The Beijing-Tianjin-Hebei(BTH)region is one area that has suffered from the most serious air pollution in China and has undergone huge changes in air quality in the past few years. How to scientifically assess these change processes remain the key issue in further improving the air quality over this region in the future. To evaluate the changes in major air pollutant emissions over this region, this paper employs ens...     

RMAPS_Chem V1.0系统SO2排放清单优化效果评估

RMAPS_Chem V1.0系统是基于WRF_Chem模式建立的服务于华北区域雾霾等污染预报业务的模式系统,该研究着重针对系统中污染排放清单不确定性带来的SO₂浓度预报偏差较大问题,采用EnKF源反演和误差统计订正相结合的方法对排放清单进行了改进,形成了一套优化后的华北区域SO₂排放清单。通过输入初始清单和优化清单对2017年10月进行模拟,并与华北地区616个地面环境监测站观测值进行对比,结果表明:EnKF源反演结合误差统计订正的排放清单优化方法适用于SO₂排放清单的改进,有效降低了清单系统性偏差,针对主要区域及重点城市的检验显示模拟结果接近观测值;排放清单优化后模拟误差显著降低,如河北南部、山东西部至北京一带模式预报均方根误差与归一化平均绝对误差明显下降,区域内站点模拟误差呈正态分布特征,误差分布范围、最大概率出现范围均明显变窄,且最大误差概率明显上升。     

Impacts of ENSO on wintertime PM2.5 pollution over China during 2014–2021

China has implemented a series of emission reduction policies since 2013, and the concentration of air pollutants has consequently decreased significantly. However, PM_2.5 (particulate matter with an aerodynamic diameter less than 2.5 µm) pollution still occurs in China in relation to the interannual variations in meteorological conditions. Considering that El Niño–Southern Oscillation (ENSO) is the strongest signal modulating the interannual variation in the atmosphere–ocean system, in this study the authors investigate the variations in PM_2.5 concentrations in four megacity clusters of China during the winter season associated with four individual ENSO events from 2014 to 2021. Results show that the wintertime PM_2.5 concentrations in the Beijing–Tianjin–Hebei and Fenwei Plain regions during El Niño years are higher than those during La Niña years, which can be explained by the anomalous southerly (northerly) winds during El Niño (La Niña) favoring PM_2.5 accumulation (diffusion). In the Pearl River Delta region, PM_2.5 concentrations decrease in El Niño relative to La Niña years owing to the enhanced water vapor flux and precipitation, removing more PM_2.5 from the atmosphere. The comprehensive effects of wind and precipitation anomalies lead to the unpredictability of the impacts of ENSO on PM_2.5 over the Yangtze River Delta region, which should be analyzed case by case.摘要2013年以来中国实施了一系列减排政策, 大气污染物浓度明显下降, 但由于气象条件的年际变化, 中国PM_2.5 (空气动力学直径小于2.5 µm的颗粒物) 污染仍然存在. 厄尔尼诺–南方涛动 (ENSO) 是调节大气–海洋系统年际变化的最强信号. 本文研究了2014–2021年四次ENSO事件期间, 中国四个特大城市群冬季PM_2.5浓度的变化. 结果表明, 在京津冀和汾渭平原地区, 由于厄尔尼诺 (拉尼娜) 期间的偏南风 (偏北风) 异常有利于 PM_2.5 的积累 (扩散), 冬季PM_2.5浓度在厄尔尼诺年高于拉尼娜年. 在珠三角地区, 由于厄尔尼诺冬季水汽通量和降水的增加有利于大气中PM_2.5的湿清除, 冬季PM_2.5浓度在厄尔尼诺年低于拉尼娜年. 在环流和降水异常的综合作用下, ENSO对长三角地区PM_2.5浓度的影响难以预测, 应逐案分析.     

Variations of levels and composition of PM10 and PM2.5 at an insular site in the Western Mediterranean

The insular suburban site of Castillo de Bellver was selected for the study of the variability of PM levels and composition in the Western Mediterranean Basin (WMB).Mean annual (in 2004) PM₁₀ and PM_2.5 levels at this site were 29 and 20 µg/m³, respectively. These levels may be regarded as relatively low when compared with other suburban insular locations in the Eastern Mediterranean Basin (EMB), but they are higher than those recorded at most of the European suburban sites, especially in Northern and Western Europe. Seasonal variability of PM levels at this site is governed by meteorology rather than local emissions, whereas the daily cycles are clearly defined by the anthropogenic emissions, mainly coming from the urban area of Palma de Mallorca and the harbour area of the same city.Concerning the aerosol composition at this site, the main PM constituent is the mineral matter (29% in PM₁₀ and 16 % in PM_2.5), more than 50% (in PM₁₀) being attributable to African dust. The amount of secondary inorganic aerosols is also very high (27% in PM₁₀ and 34% in PM_2.5), with the predominance of fine ammonium sulphate, and in a less proportion fine ammonium nitrate (in winter) and coarse Ca and Na nitrate (with higher importance in summer). The carbonaceous particles, dominantly fine, account for 17% of PM₁₀ and 25% of PM_2.5. The elemental carbon/organic carbon (EC/OC) ratio reached a mean value of 0.17, similar to those observed at regional background sites in the WMB coast of Spain. The sea spray aerosols (mainly coarse) represented around 10% of PM₁₀, and only 4% in PM_2.5. Finally, the unaccounted fraction increased from 15% to 20% in PM_2.5, being mostly attributed to water.The concentrations of trace elements in PM₁₀ and PM_2.5 were usually in the range to those observed in regional background sites in the Iberian Peninsula, with the exception of the typical tracers of road traffic such as Cu, Sb, Zn, Sn and Ba, which presented concentrations in the range of urban sites of Iberia. Other elements such as Cr, Zr, Hf and Co have been identified as the main tracers of the harbour contributions.     

基于空气质量模拟的江苏省大气污染物排放清单比较研究

大气污染物排放清单是空气质量模拟和空气污染治理的重要依据.本研究比较分析了两套覆盖江苏省的2017年大气污染物排放清单，即分别由上海市环境科学研究院、江苏省环境科学研究院编制的"长三角清单"和"江苏省清单"，并结合区域空气质量模型CMAQ评估不同清单对长三角地区2017年1、4、7、10月的空气质量模拟的影响.清单比较结果表明，除二氧化硫（SO₂）以外，江苏省清单估算的各污染物排放量较长三角清单低.通过与观测数据比较，发现两套清单对SO₂、氮氧化物（NO_x）、臭氧（O₃）和细颗粒物（PM_2.5）的模型模拟性能均较好.江苏省清单与长三角清单两者的模拟结果空间分布接近，其中江苏省清单模拟的PM_2.5和O₃在长三角多数地区略低于长三角清单的模拟结果（1月O₃除外）.江苏省清单与长三角清单均能够用于空气质量模式模拟，可为江苏地区的细颗粒物和光化学烟雾污染的控制策略制定提供参考.     

Elemental composition of PM2.5 and PM10 at Mount Gongga in China during 2006

In order to investigate the chemical characteristics of atmospheric aerosols in a regional background site, PM_2.5 and PM₁₀ were collected at Mount Gongga Station once a week in 2006. The concentrations of fifteen elements including Na, Mg, Al, K, Ca, V, Fe, Ni, Cu, Zn, As, Ag, Ba, Tl, and Pb were detected by Inductively Coupled Plasma Mass Spectrometer (ICP-MS). The results showed that Na, Mg, Al, K, Ca, Fe were the major components of elements detected in PM_2.5 and PM₁₀, occupied 89.5% and 91.3% of all the elements. Crustal enrichment factor (EF) calculation indicated that several anthropogenic heavy metals (Ni, Cu, Zn, As, Ag, Tl, Pb) were transported long distances atmospherically. The concentrations of all elements (except Na) measured in PM_2.5 and PM₁₀ in spring and winter were higher than those in summer and autumn. The backward air mass trajectory analysis suggests that northeast India may be the source region of those pollutants.     

湖北2015年冬季PM2.5重污染过程的气象输送条件及日变化特征分析

PM_2.5污染仍然是湖北省冬季大气污染的首要污染类型,且具有明显区域传输特征,重污染过程的空气污染气象条件有别于华北地区,值得关注。采用WRF/Chem不同排放情景下的模拟结果,并结合观测分析,研究了2015年12月—2016年1月湖北省PM_2.5重污染过程的气象输送条件及日变化特征,从大尺度输送条件和局地边界层动力作用分析了外来污染物水平传输、悬浮聚集和向下传输的过程,并解释了该地区观测到的午后PM_2.5浓度特殊峰值的气象成因。结果表明,湖北重污染爆发以区域传输为主,地面观测PM_2.5极值对应10 m风速可达8—10 m/s,边界层0—1 km为较强偏北风输送,污染传输通量极值位于400 m高度附近,为重要传输通道,低空无明显逆温,重污染过程具有“非静稳”边界层气象特征。重污染形成的大尺度输送条件为,长江中下游及北部地区偏北风异常偏强,南部地区风速减缓,使污染物在中游平原堆积,鄂北边界风速越大,越有利污染输送增长。传输性污染主要来自偏北和东北方向的污染源输送,潜在源区贡献主要为途经偏北通道上的豫中、南阳盆地和关中地区,以及途经东北通道上的鲁、皖、苏等部分地区。PM_2.5浓度日变化双峰结构的天气成因不同,21—24时（北京时）峰值为静稳性污染,11—14时峰值为传输性污染。污染输送受大气边界层高度影响,日出前大气边界层高度较低,层结稳定并伴有上升运行,使得低空外来输送悬浮聚集在400 m高度附近;日出后随大气边界层高度升高,静稳层结被破坏,在干沉降作用下高浓度PM_2.5开始向下传输,并在午后地面形成峰值。      

我国甲烷排放情景分析:IPAC模型结果

近期发布的IPCC第六次评估报告再次强调了短寿命期温室气体减排对温升减缓的作用。甲烷是最重要的短寿命期非CO₂温室气体。在各国提出各自新的减排目标之后,针对甲烷减排的行动方案也越来越多。甲烷减排正在成为下一阶段各国和全球合作的重点领域之一。本文在我国碳减排目标下的能源转型基础上,结合其他非能源活动的减排排放源的减排技术选择基础上,利用IPAC模型对未来甲烷的排放情景进行了分析。在模型设定的两个情景分析基础之上,研究发现,到2050年的能源转型可明显减少能源活动的甲烷排放,和2015年相比能源活动的排放可减少67％。和其他行业相比,能源部门的甲烷减排具有更好的协同性。如果考虑进一步减排甲烷,则需要在考虑其他大气污染物减排的基础上,可通过实现天然气的进一步减排来实现。同时其他部门的甲烷减排也具有很大潜力,低甲烷排放情景可以实现到2050年将甲烷排放减少到1 494万吨,和2015年相比全范围排放可减排58％。     

大气PM2.5源解析“源清单化学质量平衡法(I-CMB)”模型的建立与应用

针对受体模型对大气PM2.5中二次无机、有机气溶胶不能给出有效源贡献的问题,建立了一种基于污染源清单的化学质量平衡(Inventory-Chemical Mass Balance,I-CMB)颗粒物源解析受体模型,代入北京市近年的污染物排放数据进行了解析应用。结果表明,燃煤是北京大气PM2.5的最大来源(占比约28.06%),其余依次为机动车(19.73%)、扬尘(17.88%)、工业(16.50%)、餐饮(3.43%)、植物(3.40%)。相比于传统的化学质量平衡法(Chemical Mass Balance,CMB),I-CMB的源解析过程对源成分谱的要求较低、抗干扰性更强,计算结果均衡、详尽,比较适合我国当前大气PM2.5控制的需求。     

Impacts of 21st century climate change on global air pollution-related premature mortality

Climate change modulates surface concentrations of fine particulate matter (PM_2.5) and ozone (O₃), indirectly affecting premature mortality attributed to air pollution. We estimate the change in global premature mortality and years of life lost (YLL) associated with changes in surface O₃ and PM_2.5 over the 21st century as a result of climate change. We use a global coupled chemistry-climate model to simulate current and future climate and the effect of changing climate on air quality. Epidemiological concentration-response relationships are applied to estimate resulting changes in premature mortality and YLL. The effect of climate change on air quality is isolated by holding emissions of air pollutants constant while allowing climate to evolve over the 21st century according to a moderate projection of greenhouse gas emissions (A1B scenario). Resulting changes in 21st century climate alone lead to an increase in simulated PM_2.5 concentrations globally, and to higher (lower) O₃ concentrations over populated (remote) regions. Global annual premature mortality associated with chronic exposure to PM_2.5 increases by approximately 100 thousand deaths (95 % confidence interval, CI, of 66–130 thousand) with corresponding YLL increasing by nearly 900 thousand (95 % CI, 576–1,128 thousand) years. The annual premature mortality due to respiratory disease associated with chronic O₃ exposure increases by +6,300 deaths (95 % CI, 1,600–10,400). This climate penalty indicates that stronger emission controls will be needed in the future to meet current air quality standards and to avoid higher health risks associated with climate change induced worsening of air quality over populated regions.     

降水对江浙沪PM_(2.5)的清除效率研究

为了解不同程度的降水对江浙沪地区大气PM_(2.5)的清除作用,搜集了2014—2016年该地区41个城市的降水和PM_(2.5)观测数据,通过对比2 a非降水和全时段PM_(2.5)平均浓度的差异,发现前者显著高于后者,说明降水对该地区PM_(2.5)具有清除作用。利用降水前与降水期间PM_(2.5)的浓度差异作为降水对PM_(2.5)的清除率,降水后与降水期间的浓度差异作为雨后浓度回升的增加率,分别研究了目标区域不同时期、不同降雨量以及不同降雨时长对PM_(2.5)的清除效果。结果显示:(1)与江浙沪南部地区不同的是,北部地区降水清除率与降水前浓度存在正相关,降水后浓度的增加与当地的排放量呈正相关。(2)当降水量为30 mm或者降水时长为36 h时,清除率增幅减缓,说明降水对PM_(2.5)的清除效率存在着阈值。