Sustainable development goals link policies addressing air quality and energy efficiency to synergistic benefits for climate mitigation. However, the coal-dominated energy system poses major challenges for Henan Province in mitigating air pollution and climate change. While the government has issued a series of clean air policies and low-carbon energy targets, the simultaneous achievements of low-carbon transition and air quality goals at the sub-national level remain unclear. This study evaluates the effectiveness of policy implementation in Henan’s energy system using an integrated assessment framework that combines emission scenarios, air quality simulations, and health impact assessments. The results indicated that, by 2030, without system-wide energy transformation driven by carbon mitigation policies, air quality improvements in Henan Province will be limited, even under stringent end-of-pipe emission control measures. In contrast, low-carbon policies would yield significant co-benefits for both air quality improvement and climate mitigation. Beyond stringent end-of-pipe controls, the implementation of carbon mitigation policies aligned with China’s enhanced climate targets could further reduce Henan’s average PM2.5 concentration by up to 4.1 µg/m3. The monetized health co-benefits in Henan Province would reach 4.57 billion RMB under the stringent carbon mitigation scenario. These results highlight the critical role of effectively implementing existing air pollution and energy policies in simultaneously achieving air quality, public health, and carbon mitigation goals in Henan.

In recent years, ozone (O3) pollution in many Chinese cities has worsened. Several cities have also experienced incidents where nocturnal O3 concentrations did not decrease as expected, and instead remained at high levels (above 50 ppb). However, there have been few detailed studies on the causes of these events. The present study used air quality and meteorological monitoring data, along with the Hybrid Single-Particle Lagrangian Integrated Trajectory model, to investigate the causes contributing to nocturnal O3 remaining at high values (NORHV) in Linfen City, a typical basin city in the Fenhe River Basin, characterized by severe O3 pollution. These events are influenced by the individual or combined impacts of mountain-valley breezes, along with vertical and horizontal transport of O3-rich air masses. In addition, the influencing mechanisms of three NORHV events were identified as: 1) the alternating effect of the descent of upper-level air masses enriched with O3, CO, and SO2 and downslope mountain breezes carrying the O3-rich air mass; 2) the interaction between the transport of polluted air masses across mountains and downslope mountain breezes on both sides of the two mountains in urban areas; and 3) the O3-rich air mass from high-altitude regions descended into the urban area following two LLJ events. These conclusions were supported by vertical distributions of O3 concentrations in the three cases simulated using the WRF-CMAQ model. In addition, the NORHV events resulted in higher initial O3 concentrations on the following day compared to normal days, exacerbating O3 pollution. The results of this study demonstrate the significant contributions of complex synergistic effects, such as mountain-valley breezes and vertical transport, to the occurrence of NORHV events in basin cities. These findings may be applicable to other basin cities around the world.

Volatile organic compounds (VOCs) are considered as important precursors of ozone in the air, while the contribution of VOCs from pesticide application (PVOCs) to ozone production is unknown. Utilizing data from the Ministry of Agriculture and Rural Affairs of the People's Republic of China and ChinaCropPhen1km, this paper developed PVOC emission inventories with a resolution of 1 km for the main crops (rice, maize, and wheat) from 2012 to 2019 in China. The results revealed that pesticide application is an important VOC emission source in China. Specially, the PVOC emissions from the major grain-producing regions in June accounted for approximately 30% of the annual total PVOC emissions in the local regions. The simulation with the Weather Research and Forecasting Community Multiscale Air Quality model (WRF-CMAQ) indicated that the PVOC emissions increased the mean maximum daily 8-hour average (MDA8) ozone concentration across China by 2.5 ppb in June 2019. During the same period, PVOCs in the parts of North China Plain contributed 10% of the ozone formation. Under the comprehensive emission reduction scenario, it is anticipated that by 2025, the joint implementation of measures including reducing pesticide application, improving pesticide utilization efficiency and promoting solvent substitution will decrease PVOC emissions by 60% compared with 2019, thereby mitigating ozone pollution.

Frequent haze pollution during winter crucially affects public health in the urban agglomerations on the northern slopes of the Tianshan Mountains. However, research examining the relationship between local environmental emissions and the associated health hazards is scarce. In this study, PM2.5 filter membrane samples were collected from the residential and industrial areas of Shihezi during December 2020–January 2021. Seventeen elements were measured to evaluate the health risks associated with PM2.5. Total element concentrations on severe pollution days were 2.6 and 2.8 times higher than those on low-pollution days in residential and industrial areas, respectively. The sources of elements in residential and industrial areas were resolved into vehicle-related emissions, coal combustion, industrial pollution, dust emissions, and oil combustion using positive matrix factorisation (PMF). In residential areas, a complex mixture of vehicular emissions, coal combustion, and dust pollution is prevalent, whereas industrial parks are more susceptible to industrial pollution. Notably, a significant increase in coal combustion sources was observed during days of severe pollution in the residential areas. Simultaneously, industrial pollution in industrial parks rapidly escalated during days characterised by moderate and severe pollution levels. Combining the methods of source apportionment and health risk assessment, we observed that vehicles, coal combustion, and industrial pollution dominated the non-carcinogenic risk (NCR) of residential and industrial area elements, whereas coal combustion was the most important contributor to induced carcinogenic risk (CR).

Meteorological conditions play a key role in the occurrence and evolution of atmospheric complex pollution. Considering the different pollution formation mechanisms of PM2.5 and O3, statistical calculation and in-depth learning methods were used to construct the PM2.5 and O3 meteorological condition indexes based on long-term pollution meteorological observation data. A research method was developed to study the meteorological characteristics and impact contribution of atmospheric complex pollution by using the meteorological condition index, and quantitative analysis of the distribution and variation of pollution excluding the influence of regional meteorological differences was also conducted. The results showed that in the summer of 2021, the pollution meteorological conditions in the key regions in central and eastern China were generally worse in the north and better in the south(index:"2+26" cities>the border area of Jiangsu, Anhui, Shandong, and Henan>the Yangtze River Delta) and the worst in June and the best in July. The "double high" pollution began to appear when the PM2.5 meteorological condition index>30 and O3 meteorological condition index>100; meanwhile, the unfavorable meteorological conditions for O3 also promoted the increase in PM2.5 concentration, resulting in the frequency of "double high" increases with the increase in O3 meteorological condition index. Compared with that during the same period last year, ρ(PM2.5) of each region decreased by 3.9 μg·m-3, 3.3 μg·m-3, and 1.4 μg·m-3 due to the contribution of the improvement in the pollution meteorological conditions, which is nearly 58.5% on average of the total decrease in PM2.5 concentration. However, the change in O3 pollution meteorological conditions was better in the north and worse in the south, and the overall deterioration in the Yangtze River Delta Region led to approximately 2.8 μg·m-3 growth for the O3 concentration. The PM2.5 and O3 concentrations after excluding the impact of meteorological differences showed different distribution characteristics from the air quality monitoring, in which the high concentrations of PM2.5 were distributed along the Bohai Sea, the inter-provincial border, and the south of the region, whereas the high concentrations of O3 were concentrated along the Taihang Mountains, around Mount Tai, and in parts of the Yangtze River Delta. The daily concentration variations in a single city during a specific pollution control period could be used as a basis for evaluating the effectiveness of local supervision and control, which will provide a reference for the dynamic supervision and daily scheduling of local control management.

The north slope of Tianshan Mountains is one of the important areas in the national wide battle for eliminating heavy polluted days. To investigate the pollution characteristics of atmospheric ammonium ion (NH 4 + ) and its contribution to PM 2.5 concentration during the period of heavy air pollution in winter， the concentrations of gaseous ammonia (NH 3 ) and water-soluble ions in PM 2.5 were monitored during December 2020 and January 2021 in Shihezi， a typical industrial city in the north slope of Tianshan Mountains. The variations of atmospheric NH 4 + concentration， NH 3 -NH 4 + gas-solid conversion rate， and the existence forms of NH 4 + under different air quality levels were studied. It was found that: （1） During the monitoring period， the concentrations of PM 2.5 ， NH 4 + ， and other cations (except NH 4 + ) were 164， 25.3， and 3.60 μg/m 3 ， respectively. The NH 4 + concentration was 6.0 times higher than that of other cations， and accounts for 15.4% of PM 2.5 concentration， just lower than that of SO 4 2ˉ and NO 3 ˉ . The concentrations of NH 4 + and other cations rose with the escalated pollution， but the increase of NH 4 + was greater than that of other cations. （2） With the aggravation of air pollution， NH 3 -NH 4 + gas-solid conversion rate increased gradually. The average conversion rates on the clean days， the light and moderate pollution days， and the heavy and serious pollution days were 0.23， 0.51， and 0.69， respectively. The conversion rate was positively correlated with PM 2.5 and NH 4 + concentration， and was negatively correlated with gaseous NH 3 concentration and temperature. （3） The atmospheric NH 4 + in winter was abundant in Shihezi， and was mainly in the form of (NH 4 ) 2 SO 4 ， and the remaining NH 4 + existed in the form of NH 4 NO 3 and NH 4 Cl. The study showed that the NH 3 -NH 4 + gas-solid conversion rate and NH 4 + concentration increased significantly during the period of heavy air pollution in winter in the north slope of Tianshan Mountains， and it was necessary to pay attention to NH 3 pollution prevention while focusing on the control of SO 2 and NO x pollution.

Field measurements of atmospheric carbonyl compounds (carbonyls) and essential precursors of O-3 were carried out in the urban area of Linfen City (Linfen) where serious O-3 pollution has occurred in recent years due to its unique terrain. Carbonyls were sampled using an automatic carbonyl sampler in August 2019 to determine their pollution characteristics and sources. An average concentration of ten carbonyls was 27 +/- 5.7 lig m(-3) detected using an HPLC-UV system. The concentrations of most detected carbonyls in August were significantly higher than those in the winter months in China. Acetone, formaldehyde and acetaldehyde were the most abundant species, accounting for 73% of all detected carbonyls. Formaldehyde, acetaldehyde, and methacrolein (MACR) were the most significant contributors to OH center dot reactivity and ozone generation, indicating that these three carbonyls were the key species influencing the production of O-3. The concentrations of formaldehyde, acetaldehyde, and MACR showed similar diurnal variations on most days, with high values during the daytime reaching a peak at 10:00. However, the concentrations of the latter two species varied less than that of formaldehyde during the day. The acetone concentration generally increased continuously from morning to night, with the maximum value around 22:00. The C1/C2 ratio in summer was higher than that in winter. These results indicated that the carbonyls in Linfen were not only affected by anthropogenic sources such as vehicle exhaust but also by secondary photochemical production. The results of formaldehyde source apportionment showed that the contributions of background, primary, and secondary sources to the observed formaldehyde concentration were 27.6%, 36.6%, and 35.8%, respectively. Additionally, this study revealed for the first time that the vertical transport of air masses containing high concentrations of O-3 and NO3 radicals above the boundary layer could increase the secondary generation of formaldehyde at night in summer.

石河子市是位于新疆乌昌石区域中部的工业城市,2020年12月和2021年1月在石河子市城区和工业区共布设2个采样点,全天候采集细颗粒物(PM2.5)样品61d,利用电感耦合等离子质谱仪(ICP-MS)对24种元素含量进行分析,并通过富集因子法(EF)解析PM2.5中无机元素的污染特征及来源.结果表明,冬季采样期间,石河子市重度及以上污染天数占整个采样期的53.2％,以PM2.5为首要污染物的污染天数占整个采样期的98.4％,采样期城区和工业区的PM2.5日均值分别为164.7μg·m-3和113.6 μg·m-3,表明石河子市冬季PM2.5污染严重;采样期城区和工业区PM2.5中无机元素浓度分别为4.4 μg·m-3和3.6μg·m-3,主要成分均为K、Ca、Na、Mg、Al、Fe,6种元素之和在城区和工业区元素中的占比分别为97.4％和97.5％,表明这6种元素为城区和工业区元素的主要组分,城区和工业区主要元素组成差异性较小,污染天K和Ca元素的累积速度最快,Na和Ca元素的累积量最大;石河子市2020年冬季PM2.5中主要富集元素为K、Ca、Na、Mg、Fe,富集元素主要来源于工业区、机动车、地壳物质以及餐饮油烟等,城区元素富集程度和污染程度略高于工业区.

To evaluate the ability of the Predicted Particle Properties (P3) scheme in the Weather Research and Forecasting (WRF) model, we simulated a stratiform rainfall event over northern China on 22 May 2017. WRF simulations with two P3 versions, P3-nc and P3-2ice, were evaluated against rain gauge, radar, and aircraft observations. A series of sensitivity experiments were conducted with different collection efficiencies between ice and cloud droplets. The comparison of the precipitation evolution between P3-nc and P3-2ice suggested that both P3 versions overpredicted surface precipitation along the Taihang Mountains but underpredicted precipitation in the localized region on the leeward side. P3-2ice had slightly lower peak precipitation rates and smaller total precipitation amounts than P3-nc, which were closer to the observations. P3-2ice also more realistically reproduced the overall reflectivity structures than P3-nc. A comparison of ice concentrations with observations indicated that P3-nc underestimated aggregation, whereas P3-2ice produced more active aggregation from the self-collection of ice and ice-ice collisions between categories. Efficient aggregation in P3-2ice resulted in lower ice concentrations at heights between 4 and 6 km, which was closer to the observations. In this case, the total precipitation and precipitation pattern were not sensitive to riming. Riming was important in reproducing the location and strength of the embedded convective region through its impact on ice mass flux above the melting level.

Taking Shihezi City, a typical city on the northern slope of Tianshan Mountains, as the case, based on the ground conventional pollutant monitoring, meteorological observation, the LiDAR observation, and the mesoscale Weather Research and Forecast（WRF） model simulation results, the impact of meteorological parameters and boundary layer structure changes on the air quality in Shihezi City were comprehensively analyzed. The results showed that the seasonal differences of air quality in Shihezi City were quite significant, with the highest difference of 11.4 times of PM 2.5 concentrations between winter and summer, and the occurrence rate of air pollution episodes in December to February in winter is as high as 81.2%, with 59.1% of heavy and above polluted days. In the winter of 2020-2021, four heavy pollution processes occurred, and each heavy pollution process lasted for 7-27 d, with the interval period of only 1-3 d. Each process was dominated by fine particle pollution. In total, the period of December-February could be considered as a continuous "pollution season", with the peak value of 373-425 μg/m~3 of PM 2.5 , and the average value of 0.82 for PM 2.5 /PM 10 . After entering autumn and winter, the continuous low temperature and high humidity meteorological conditions on the ground had a significant negative effect on PM 2.5 concentration, and the main influence conditions were T＜-3 ℃ and 65%＜RH＜92%. Under these conditions, the significant declining of boundary layer height and the change of near-ground diffusion caused by continuous strong inversion were the fundamental reasons for the formation of winter "pollution season". In the heavy pollution process on January 16-22, 2021, the continuous low temperature, high humidity and breezy/still wind conditions were the dominant ground meteorological conditions, and the generation and dissipation of heavy pollution only changed with the boundary layer and inversion conditions. The boundary layer height in the pollution accumulation period decreased by nearly 5 times compared with that in the clean days, and the intensity of the inversion temperature exceeded 1.5 ℃/（100 m）. Immediately after the heavy pollution episode, 3 clean days appeared following with the receding of inversion temperature and the rising of boundary layer height.

To study the pollution characteristics and sources of water-soluble inorganic ions (WSIIs) in Shihezi city in winter, 122 PM2.5 samples were collected in two sites of the urban areas and industrial areas from December 2020 to January 2021. The chromatography system (Dionex ics-900) was used to detect the cations and anions (\begin{document}${\rm{SO}}_4^{2-} $\end{document}, \begin{document}${\rm{NO}}_3^{-} $\end{document}, Cl−, F−, \begin{document}${\rm{NH}}_4^{+} $\end{document}, Na+, K+, Ca2+ and Mg2+) of PM2.5. The results showed that, in winter the concentrations of WSIIs in urban areas and industrial areas were (107.18±50.66) μg·m−3 and (85.32±35.56) μg·m−3, respectively, and the proportion of that in PM2.5 were 56.3%—67.2% and 62.2%—63.0%, respectively. WSIIs were the main component of PM2.5 in Shihezi city in winter. The trend of ions concentrations in urban areas were \begin{document}${\rm{SO}}_4^{2-} $\end{document}＞\begin{document}${\rm{NO}}_3^{-} $\end{document}＞\begin{document}${\rm{NH}}_4^{+} $\end{document}＞Cl−＞Ca2+＞Na+＞F−＞K+＞Mg2+, and the urban areas were \begin{document}${\rm{SO}}_4^{2-} $\end{document}＞\begin{document}${\rm{NO}}_3^{-} $\end{document}＞\begin{document}${\rm{NH}}_4^{+} $\end{document}＞Cl−＞Na+＞Ca2+＞F−＞K+＞Mg2+. The concentrations of SNA (\begin{document}${\rm{SO}}_4^{2-} $\end{document}, \begin{document}${\rm{NO}}_3^{-} $\end{document} and \begin{document}${\rm{NH}}_4^{+} $\end{document}) in urban and industrial areas were (97.71±46.13) μg·m−3 and (76.97±32.87) μg·m−3, respectively, and those accounted for 91.2%±3.1% and 90.3%±2.7% of WSIIs, respectively. The results indicated that SNA was the main component of WSIIs and PM2.5. The concentration of Cl− in urban areas was lower than that in industrial areas, and there was different result for Ca2+. The results indicated that the PM2.5 was greatly affected by fossil fuel combustion in industrial areas, while the PM2.5 in urban areas was greatly affected by dust. In severe pollution days, the contribution of coal-fired emission to PM2.5 was greater than that of motor vehicles, and the contribution of coal-fired emission in urban areas was greater than that of industrial areas. The main components of ions in urban areas were (NH4)2SO4 and NH4HSO4, and in industrial areas were mainly (NH4)2SO4, NH4HSO4 and NH4NO3, There was a high degree of homology between \begin{document}${\rm{SO}}_4^{2-} $\end{document}, \begin{document}${\rm{NO}}_3^{-} $\end{document} and \begin{document}${\rm{NH}}_4^{+} $\end{document} in industrial areas.

City clusters play an important role in air pollutant and greenhouse gas (GHG) emissions reduction in China, primarily due to their high fossil energy consumption levels. The "2 + 26" Cities, i.e., Beijing, Tianjin and 26 other perfectures in northern China, has experienced serious air pollution in recent years. We employ the Greenhouse Gas and Air Pollution Interactions and Synergies model adapted to the "2 + 26" Cities (GAINS-JJJ) to evaluate the impacts of structural adjustments in four major sectors, industry, energy, transport and land use, under the Three-Year Action Plan for Blue Skies (Three-Year Action Plan) on the emissions of both the major air pollutants and CO2 in the "2 + 26" Cities. The results indicate that the Three-Year Action Plan applied in the "2 + 26" Cities reduces the total emissions of primary fine particulate matter with an aerodynamic diameter of ≤ 2.5 μm (PM2.5), SO2, NOx, NH3 and CO2 by 17%, 25%, 21%, 3% and 1%, respectively, from 2017 to 2020. The emission reduction potentials vary widely across the 28 prefectures, which may be attributed to the differences in energy structure, industrial composition, and policy enforcement rate. Among the four sectors, adjustment of industrial structure attains the highest co-benefits of CO2 reduction and air pollution control due to its high CO2 reduction potential, while structural adjustments in energy and transport attain much lower co-benefits, despite their relatively high air pollutant emissions reductions, primarily resulting from an increase in the coal-electric load and associated carbon emissions caused by electric reform policies..

The Beijing area experienced daily ozone increases after the Belt and Road Forum in May 2017, with the maximum hourly O-3 peak exceeding 400 mu g/m(3). The high O-3 event was analyzed by using observed data and model simulations. Results indicated that the local photochemistry was the major driver boosting O-3 formation for northern suburban sites and regional transport in the late afternoon made another peak in O-3 diurnal variation for urban sites. A prominent VOC-limited sensitivity regime was dominant in the Beijing area, even over suburban areas far away from the Beijing urban center. The rapid increase in VOCs emissions from both biogenic and anthropogenic sources under high air temperatures provided the needed VOCs for O-3 formation, resulting in a dramatic O-3 increase after the summit. It was also found that PM2.5 experienced steady daily increases after the summit, leading to a gradual decrease in the UV radiation measured at the ground; however, O-3 showed a dramatically increasing trend, in contrast to the expectation that the high-level PM2.5 would restrain the O-3 formation by the theoretical deduction in the O-3 and aerosol interaction. The results suggest that the abrupt change in emissions during the study period overwhelmed the effects of the O-3 and aerosol interaction. Such temporary changes in emissions should be considered in mitigation strategies of O-3 control.

The presence of embedded convection in stratiform clouds strongly affects ice microphysical properties and precipitation formation. In situ aircraft measurements, including upward and downward spirals and horizontal penetrations, were performed within both embedded convective cells and stratiform regions of a mixed-phase stratiform cloud system on 22 May 2017. Supercooled liquid water measurements, particle size distributions, and particle habits in different cloud regions were discussed with the intent of characterizing the riming process and determining how particle size distributions vary from convective to stratiform regions. Significant amounts of supercooled liquid water, with maxima up to 0.6 g m −3 , were observed between −3°C and −6°C in the embedded convective cells while the peak liquid water content was generally less than 0.1 g m −3 in the stratiform regions. There are two distinct differences in particle size distributions between convective and stratiform regions. One difference is the significant shift toward larger particles from upper −15°C to lower −10°C in the convective region, with the maximum particle dimensions increasing from less than 6000 µm to over 1 cm. The particles larger than 1 cm at −10°C are composed of dendrites and their aggregates. The other difference is the large concentrations of small particles (25–205 µm) at temperatures between −3°C and −5°C in the convective region, where rimed ice particles and needles coexist. Needle regions are observed from three of the five spirals, but only the cloud conditions within the convective region fit into the Hallett-Mossop criteria.

In order to study the pollution characteristics and causes of winter haze pollution in Beijing, a typical PM2.5 pollution process in Beijing in December 2019 was used as the analysis object using aerosol vertical detection data, boundary layer meteorological field and near-ground turbulence data, and the difference in haze. The characteristics of the pollution stage and the evolution of the physical and chemical characteristics of the boundary layer were comprehensively analyzed. The results showed that ① the pollution process in Beijing during the observation period lasted 5 d and experienced two generations and eliminations. The maximum hourly PM2.5 concentration was 220 μg·m-3 and the time exceeding the severe pollution standard was 64 h, thereby accounting for 53% of the total time. ② The aerosol optical properties and meteorological field observation data showed that the pollution originated from the regional transmission of aerosols and water vapor on the surface of the southwest urban agglomeration in Beijing, which accounted for 48% of the total pollution transmission, followed by a stable high-altitude situation and ground pressure field configuration. The near-surface layer maintained weak southerly winds (wind speed: 1-2 m·s-1), a strong inversion temperature close to the ground ［0.8 K·(100 m)-1］, high humidity (relative humidity above 80%), and other unfavorable diffusion weather conditions, thereby promoting the accumulation of pollutants and the conversion of moisture absorption. Superimposing local pollution emissions were the main reasons for the maintenance of haze days. In addition, the near-ground extinction coefficient increased from 0.070 km-1 to 5.954 km-1, and the depolarization ratio decreased from 0.05 to 0.02 during the two pollution generation and disappearance processes, thereby indicating that the spherical characteristics of aerosols gradually became significant as the pollution increased. ③ The analysis of the turbulence observation data showed that the characteristic quantities of different pollution stages were significantly different and negatively correlated with the pollutant concentration. Before the occurrence of heavy pollution, the turbulence statistics (turbulence intensity, friction velocity, and turbulent kinetic energy) suddenly decreased from high values (the hourly variation rate was 77%, thereby far exceeding the daily fluctuation of 33%), and the turbulence intensity responded first. During the pollution accumulation stage, the friction velocity (0.04-0.21 m·s-1), turbulence intensity (average: 0.678 m2·s-2), and turbulence energy (average: 0.643 m2·s-2) were maintained at a low level, and the bottom atmosphere had a poor mixing and diffusion ability, which is important for continuous pollution accumulation. Four hours before the end of the pollution event, the turbulence intensity again showed a sharp increase (increment of more than one order of magnitude); thus, the turbulence intensity can be used as a predictive indicator of the occurrence and end of a heavy pollution event, and the response time is the same as the continuous turbulence intensity after the turbulence peak. In addition, the sensible heat fluxes on sunny days and haze days were both transported from the ground to the atmosphere, and showed clear daily single-peak changes. The sensible heat flux on haze days (20 W·m-2) was smaller than that on sunny days (60 W·m-2). The latent heat flux was approximately 0 W·m-2 in the whole process. ④ There was a feedback effect between the meteorological conditions of the pollution layer and the boundary layer. On the one hand, unfavorable diffusion of the meteorological conditions was conducive to the accumulation of pollution. On the other hand, the aerosol layer and water vapor cooling effect that accumulated near the ground were worse than the night cooling radiation on the inversion layer The contribution was greater, thereby further inhibiting the development of turbulent motion and ultimately resulting in increased pollution.

为研究唐山市大气PM2.5中元素组成特征及其来源,于2017年10月19日—2018年1月31日(秋冬季)在唐山市的超级站(典型城市站点)、开平站(工业站点)和古冶站(工业站点)开展了PM2.5的手工连续采样,定量分析测定了PM2.5中23种无机元素.结果 表明:Si、Al、Ca和Na等地壳元素的质量浓度均在10月最高,在1月最低.10月,ρ(Cr)在开平站最高(0.0200μg∕m3),随后逐月略微降低,其主要受钢铁冶炼工业的减产和限产影响.多数重金属元素质量浓度在11月或12月最高,包括Zn、Pb、Mn、Cu、Ni、Se、V、Cd和Co,其可能受燃煤取暖影响.Cd、Zn、Pb和Cu四种元素的富集因子值分别为2677、616、422和77,均达到极强富集,且均受人为排放源影响最大.基于因子分析法得出,唐山市大气PM2.5中元素的主要来源有燃煤源、钢铁工业源与扬尘源的混合源、交通源以及土壤扬尘源,其方差贡献率分别为56.3％、21.6％、7.1％、5.4％.研究显示,秋冬季唐山市大气颗粒物PM2.5中元素最主要的污染来源为工业源、燃煤源和扬尘源.

ABSTRACTThis study analyzed the increase in the surface ozone over Beijing-Tianjin-Hebei (BTH) and its surrounding areas during the period of 2005–2018 using satellite-retrieved data. First, a geographically weighted regression (GWR) model was developed to estimate the surface ozone concentration (SOC) between 2005 and 2018 based on Ozone Monitoring Instrument (OMI) ozone profiles. The resultant values and their growth rate were then analyzed. The SOC exhibited significant variation in the spatial distribution over the study area, with the maximum and the minimum values occurring in the southeast and the northeast, respectively. The latter region also displayed the highest SOC growth rate, however, whereas the southwest displayed the lowest one. Additionally, prominent seasonality was observed in the SOC: The concentration peaked during the warm season and troughed during the cold season, but the growth rate showed the opposite trend. The values during the cold season greatly affected the annual spatial distribution and the growth rate of the SOC, whereas those during the warm season significantly contributed to the annual concentration. From 2005 till 2018, the SOC showed an upward trend with an average growth rate of 3.4 µg m–3 y–1, with a greater increase in the second half (2012–2018) than the first half (2005–2011) of the study period because of the stronger photochemical reactions caused by the continual increase in HCHO during summer and the weaker NO titration effect caused by the rapid decrease in NO2 during winter. With constantly rising levels of HCHO and a VOCs-limited regime in the study area, we must formulate an effective reduction scheme for VOCs and NO2 co-emissions in order to mitigate the surface ozone pollution, despite the risk that decreasing the NO2 will lead to a certain increase in the SOC.

针对低空急流(Low-Level Jet,LLJ)这种与空气污染等现象密切相关的天气现象,综述了低空急流的定义、日变化特征、季节性变化特征,以及包括惯性振荡理论、地形的热力和动力作用、天气系统强迫等低空急流的形成和发展机制,总结国内外开展的低空急流数值模拟及其在大气污染源排放污染物的输送、扩散中的影响等研究成果,提出了下一步应开展低空急流的选取标准及其与空气污染学科的交叉研究,并开展适宜本地区低空急流数值模拟的参数化方案和小尺度研究等建议.