Search

Ground-level ozone (O 3) pollution is a major air quality issue in densely populated urban areas. Despite a significant decline in human activities in the megacity Shanghai from March 28 to May 31, 2022, ground-level measurements indicate a rise in maximum daily average 8-h (MDA8) O 3 concentrations in comparison to the corresponding period in 2021. There is a need for quantitative analysis to identify the reasons behind this increasing O 3 concentration. We analyzed ground measurements of O 3 and its precursors and meteorological parameters made in Shanghai, using random-forest (RF) model and chemical box model to elucidate the roles of meteorological and chemical factors in influencing O 3 concentrations. Across urban, suburban, semi-rural, and coastal sites, the urban center of Shanghai experienced the largest decreases in the concentrations of nitrogen oxides (NO x ; 53%) and volatile organic compounds (VOCs; 52%), with the most notable rise in MDA8 O 3 concentrations (16%). RF modeling indicates that meteorological factors reduced MDA8 O 3 concentrations by a marginal 3%, whereas a decline in anthropogenic emissions resulted in a 17% increase in MDA8 O 3 concentrations. Chemical box modeling at the Pudong urban site indicates that while the decline in VOCs reduced O 3 production by 42%, this was negated by a reduction in NO x from traffic emissions, which enhanced O 3 production by 51%, resulting in an increase in O 3 production overall. Despite a halving in precursor levels, Shanghai's urban centre remains predominately under VOC-limited conditions throughout the study period, with high NO 2 levels from the petrochemical industry and traffic emissions. Joint control of anthropogenic VOCs (AVOCs) and NO x , with a ratio greater than 1.29, could help avoid exacerbation of O 3 pollution and reduce NO 2 pollution. Our findings emphasize the necessity of reducing industrial emissions along with ongoing green transportation strategies for alleviating O 3 pollution in megacities like Shanghai. • Emission reductions drove an O 3 increase in Shanghai during the 2022 lockdown. • Shanghai's urban centre remains predominately under VOC-limited conditions. • The high NO 2 level was attributed to petrochemical industry and traffic emissions. [ABSTRACT FROM AUTHOR]

A Tethered balloon-based field campaign was launched for the vertical observation of air pollutants within the lower troposphere of 1000 m for the first time over a Chinese megacity, Shanghai in December of 2013. A custom-designed instrumentation platform for tethered balloon observation and ground-based observation synchronously operated for the measurement of same meteorological parameters and typical air pollutants. One episodic event (December 13) was selected with specific focus on particulate black carbon, a short-lived climate forcer with strong warming effect. Diurnal variation of the mixing layer height showed very shallow boundary of less than 300 m in early morning and night due to nocturnal inversion while extended boundary of more than 1000 m from noon to afternoon. Wind profiles showed relatively stagnant synoptic condition in the morning, frequent shifts between upward and downward motion at noon and in the afternoon, and dominant downward motion with sea breeze in the evening. Characteristics of black carbon vertical profiles during four different periods of a day were analyzed and compared. In the morning, surface BC concentration averaged as high as 20 μg/m 3 due to intense traffic emissions from the morning rush hours and unfavorable meteorological conditions. A strong gradient of BC concentrations with altitude was observed from the ground to the top of boundary layer at around 250–370 m. BC gradients turned much smaller above the boundary layer. BC profiles measured during noon and afternoon were the least dependent on heights. The largely extended boundary layer with strong vertical convection was responsible for a well mixing of BC particles in the whole measured column. BC profiles were similar between the early-evening and late-evening phases. The lower troposphere was divided into two stratified air layers with contrasted BC vertical distributions. Profiles at night showed strong gradients from the relatively high surface concentrations to low concentrations near the top of the boundary layer around 200 m. Above the boundary layer, BC increased with altitudes and reached a maximum at the top of 1000 m. Prevailing sea breeze within the boundary layer was mainly responsible for the quick cleanup of BC in the lower altitudes. In contrast, continental outflow via regional transport was the major cause of the enhanced BC aloft. This study provides a first insight of the black carbon vertical profiles over Eastern China, which will have significant implications for narrowing the gaps between the source emissions and observations as well as improving estimations of BC radiative forcing and regional climate. [ABSTRACT FROM AUTHOR]

The heaviest aerosol pollution day in the historical record of the Yangtze River Delta occurred on 19 January 2007, in which the daily concentration of PM10 reached 512μgm−3 in Shanghai, 463μgm−3 in Suzhou, 354μgm−3 in Hangzhou, and 282μgm−3 in Nanjing. The hourly concentrations of PM2.5 and PM10 reached peak values of 466 and 744μgm−3, respectively, in Shanghai. With visibility <0.6km, the regional haze covered nearly the entire Yangtze River Delta. High ratios of PM2.5/PM10 (61%), SO2/PM10 (0.38) and NO2/PM10 (0.24) were observed. The unusual stagnant dispersion conditions before a cold front played the predominant role in this high pollution episode, with relative humidity (RH) of 88%, both surface and upper-level inversions, as well as low wind speed (<1ms−1). The sulfur oxidation rate (SOR) reached 0.67 and the nitrogen oxidation rate (NOR) reached 0.61, signifying that formation of sulfate and nitrate contributed significantly to the high secondary aerosol concentration of PM2.5. The enrichment factors of As, Cd, and Pb reached 4058, 6971, and 3972, which were 4.45–6.68 times higher than those on good/moderate days. It was demonstrated that emissions from anthropogenic sources, especially stationary sources such as power plants, industrial boilers, and furnaces, were the major contributors to the heaviest aerosol pollution in the delta. More attention should be paid to the increases in emissions and the higher occurrence of haze days that have accompanied the rapid development of the economy in the Yangtze River Delta. [Copyright &y& Elsevier]

A tethered balloon-based measurement was conducted to investigate vertical distribution of O 3 over Shanghai, China, during May of 2016. The time-series and diurnal variation of ground-level air pollutants (including O 3 , NO, NO 2 and VOCs) were analyzed systematically. By using TrajStat (a GIS-based software), the potential distant contributions of O 3 might come from East China Sea, and the Yangtze River Delta (YRD). Within 1000 m above ground, the average vertical profiles of O 3 exhibited obviously diurnal characteristics. Most of the NO and O 3 profiles measured on high-ozone days demonstrated anti-correlation. The launches on May 11, 2016 revealed that the Atmospheric Boundary Layer (ABL) and shifting of wind direction contributed to the peaks of O 3 at the upper altitude. A typical case of vertical mixing of O 3 was caught on May 18, 2016, when the ground-level O 3 was greatly influenced by the O 3 transported from high altitude (1500 m above sea level). The present study provides an important insight of the vertical distribution of O 3 over Eastern China, which implied that coupling effects of horizontal and vertical transportations on ground-level ozone should be investigated in future studies. Image 1 • Ozone in rural Shanghai were highly influenced by nearby areas. • Vertical profiles of ozone exhibited obviously diurnal differences. • Vertical mixing of O 3 is an important source of high O 3 in rural Shanghai. [ABSTRACT FROM AUTHOR]

Air quality has improved significantly in the recent 10 years, but there is still a wide gap compared to the WHO AQG level. The concentration of PM 2.5 during OMICRON in 2022 was 21.7 μg m−3, which marked the lowest historical record under the lockdown status of the whole urban area, still exceeding the national Level 1 standard. PMF results have shown that the contributions of ship emissions increased from 2020 to 2022 during the historical OMICRON episodes, with growth rates of 9.7% and 10.7%, respectively. AIS data indicated an overall increase in shipping activities around Shanghai during the OMICRON22-2021 period. The strict control of urban activities during the silent period in 2022 reduced ship activities by 21.0% and 31.8% in the ChongMingMsa and WuSongMsa ranges close to Shanghai, respectively. However, significant growth was observed in the sea regions of ShanghaiMsa and ZhouShan-NingBoMsa, with growth rates of 44.2% and 33.7%, respectively. The total number of anchored ships in the sea region of YangShanGangMsa increased by 56.7%. CWT analysis indicated that the lockdown measures only changed the distributions of the ship emissions. More forceful measures for the reductions of the ship emissions should be considered. [Display omitted] • PM 2.5 concentration under the lockdown status still exceeded the national Level 1 standard and WHO AQG level. • The concentration of ship emission marker-Vanadium decreased with the benefit of ECA,but increased after 2020. • No obvious reduction of ship activities and emissions were found around Shanghai during OMICRON episode. • Epidemic events changed the distributions of the ship activities and the related emissions. [ABSTRACT FROM AUTHOR]

New particle formation (NPF) is one main source of atmospheric aerosols and plays an important role in global climate by contributing up to two thirds of the atmospheric cloud condensation nuclei. Numerous studies on characteristics and mechanisms of near-surface NPF have been conducted in last decades. However, the characteristics of NPF around the top of the planetary boundary layer (PBL) remains unclear due to the limitations of vertical measurements. In this study, a tethered airship onboard with advanced particle instruments was deployed for directly measurement of the NPF exactly above and under the top of the PBL in the Yangtze River Delta (YRD) of eastern China in December 2017. Coupled with the real time ground Lidar observation, we successfully conducted measurement of aerosol size distribution, chemical components of aerosol and gas pollutants with 100 m above/under the top of the PBL. Despite not being observed within the PBL during the flight and at three ground sites in YRD, NPF event with the growth rate of 3.8 nm/h was detected above the PBL. High oxidizing capacity, enough condensable vapors and low condensation sink above the PBL favor the onset of NPF. Model simulation and the aerosol chemical composition result indicate the important role of gaseous sulfuric acid in NPF and its subsequent growth in the upper atmosphere. Our study highlights the potential mechanism of NPF above the PBL and the need of direct vertical measurements to better understand NPF in the atmosphere and its climate effect. • Tethered airship platform made it possible to understand subtle vertical structure. • Model forecast and online measurements can reduce the risk of experiment. • New particle formation was detected only above the planetary boundary layer. • The growth rate above the planetary boundary layer was about 3.8 nm/h. • High H 2 SO 4 values above planetary boundary layer favor the new particle formation. [ABSTRACT FROM AUTHOR]

Abstract Multi-AXis-Differential Optical Absorption Spectroscopy (MAX-DOAS) measurements were performed to remote sensing the aerosol vertical profiles in suburb area of Shanghai, China from April to December 2017. The retrieval of aerosol extinction was based on the optimal estimation method combing the measured oxygen dimer O 4 absorption with simulation of forward radiative transfer model. It suggests that the employment of O 4 correction factor (CF O4) for daily aerosol retrieval should be adjusted, which includes three typical cases that a fixed CF O4 , no usage of CF O4 and different CF O4 in the morning and afternoon. In cases of using CF O4 , elevation angle dependent CF O 4 (α) were further proposed. Moreover, the retrieval results can be improved if the local sounding data of atmospheric temperature and pressure profiles were introduced into the forward radiative transfer model without utilizing additional CF O4. Afterwards, the retrieved Aerosol Optical Depth (AOD) and the surface Aerosol Extinction Coefficient (AEC) was in a good agreement with the AOD obtained from sun photometer observations and in-suit PM 2.5 concentrations, with a correlation coefficient R of 0.866 and 0.833, respectively. Besides, the vertical AEC profiles retrieved by MAX-DOAS were also validated well by the co-located lidar measurement. It can be found that the particles were mainly distributed below 1 km, and the maximum AEC usually appeared in the lowest 300 m and decreased with the altitudes. The averaged AEC within 1 km varied from 0.20 to 0.75 km−1, 0.25 to 1.08 km−1, 0.55 to 2.45 km−1 and 0.70 to 2.75 km−1 under different air quality of Grade II, III, IV and V. The sounding meteorological parameters and backward trajectories of air masses were integrated to diagnose the influencing factor of AEC at different altitudes, which illustrated that the AEC levels at lowest layer were impacted by the long distance transportation of air pollutants from north-northwest and regional local air pollution nearby during the winter time. The study shows that ground-based MAX-DOAS observation is powerful remote sensing technique to provide better understanding of aerosol properties at both ground surface and higher altitudes. Highlights • Aerosol vertical distribution were obtained by MAX-DOAS measurements in Shanghai. • O 4 correction factor (CF O4) need to be adjusted in the aerosol retrieval scheme. • Using local temperature and pressure profiles can improve the aerosol retrieval. • MAX-DOAS remote sensing are well validated by other auxiliary datasets. • High aerosol extinction usually occurred at the lowest layer below 0.3 km in winter. [ABSTRACT FROM AUTHOR]

Air pollution has become one of the most stubborn environmental problem in China, the traditional environmental monitoring mainly focus on the horizontal distribution of the pollutants, while it is still of great importance to have the knowledge of the vertical profiles of them. The present study, for the first time, attempted to acquire the vertical distributions of O 3 and one of its precursors, volatile organic compounds (VOCs) within 1000 m of lower troposphere by using a tethered balloon in the suburban of Shanghai, a Chinese megacity. We analyze the concentration and the ozone formation potential (OFP) at three height level of 50–350, 350–700, and 700–1000 m. According to our measurement, the total concentration of VOC decreased with the altitude increasing. In addition, the dominant species of OFP was alkene, aromatics, and alkene at height level of 50–350, 350–700 and 700–1000 m, respectively. Our results suggest that, in the morning, the fresh emission contributed a lot to the high concentration of benzene and toluene near ground. Furthermore, the regression analyzes showed toluene decreased faster than benzene in the troposphere. The VOC concentration can be used as initial values for numerical simulations of chemical reaction in the lower troposphere. [ABSTRACT FROM AUTHOR]

A tethered balloon-based measurement campaign of particle number concentration (PNC) and particle number size distribution (PNSD) in the size range of 15.7–661.2 nm was conducted within the lower troposphere of 1000 m in Shanghai, a Chinese megacity, during December of 2015. The meteorological conditions, PNC, and PNSD were synchronously measured at the ground-based station as well as by the tethered balloon. On ground level, the 88.2 nm particles were found to have the highest PNC. The Pearson correlation analysis based on the ground level data showed NO 2 had a strong correlation with PNC. The synchronous measurement of PNC and PNSD at the ground station and on the tethered balloon showed that the 15.7–200 nm particles had higher PNC on ground level, but the PNC of 200–661.2 nm particles was higher at 400 m. One haze event (Dec 22nd-Dec 23rd) was selected for detailed discussion on the variation of vertical profiles of PNSD and PNC. The vertical distribution of characteristics of PNC and PNSD were observed and compared. Results indicated that the highest MaxDm (the diameter with the highest PNC) during those three launches all appeared at a high altitude, usually above 300 m. Compared to the clean days, the relatively bigger MaxDm at each height in the haze days also indicated regional transport of pollutants might contribute to more to that haze event. [ABSTRACT FROM AUTHOR]

During the Covid-19 outbreak, strict lockdown measures led to notable reductions in transportation-related emissions and significantly altered atmospheric pollution characteristics in urban and suburban areas. In this work, we compare comprehensive online measurements of PM 2.5 major components and organic molecular markers in a suburban location in Shanghai, China before lockdown (Dec. 28, 2019 to Jan. 23, 2020) and during lockdown (Jan. 24 to Feb. 9, 2020). The NO x levels declined sharply by 59% from 44 to 18 ppb during the lockdown, while O 3 rose two times higher to 42 ppb. The PM 2.5 level dropped from 64 to 49 μg m−3 (−24%). The major components all showed reductions, with the reduction of nitrate most prominent at −58%, followed by organics at −19%, and sulfate at −17%. Positive matrix factorization analysis identifies fourteen source factors, including nine primary sources and five secondary sources. The secondary sources consist of sulfate-rich factor, nitrate-rich factor, and three secondary organic aerosol (SOA) factors, with SOA_I being anthropogenic SOA, SOA_II associated with later generation products of organic oxidation, and SOA_III being biogenic SOA. The combined secondary sources contributed to 69% and 63% (40 and 22 μg m−3) of PM 2.5 before and during lockdown, respectively, among which the reductions in the nitrate-rich (−55%) factor was the most prominent. Among primary sources, large reductions (>80%) were observed in contributions from industrial, cooking, and vehicle emissions. Unlike some studies reporting that the restriction during the Covid-19 resulted in enhanced secondary sulfate and SOA formation, we observed decreases in both secondary inorganic and SOA formation despite the overall elevated oxidizing capacity in the suburban site. Our results indicate that the formation change in secondary inorganic and organic compounds in response to substantial reductions in urban primary precursors are different for urban and suburban environments. [Display omitted] • Covid lockdown lowered PM 2.5 and NO x while increased O 3 levels in suburban Shanghai. • Nitrate was the most prominent contributor to PM 2.5 reduction during lockdown. • Lockdown led to reduced PM 2.5 contributions by 8 primary and 5 secondary sources. • Contribution percent drop from industrial and vehicular sources were as high as 87%. • Lockdown effects on SOA formation likely differ in suburban and urban environments. [ABSTRACT FROM AUTHOR]

Joint field observations were conducted from October to November in 2011 to observe haze pollution in the Yangtze River Delta (YRD), China. Samples of particulate matter with diameter less than 2.5 μm (PM 2.5 ) and less than 10 μm (PM 10 ), gaseous pollutants and meteorology data were collected in five cities – Shanghai, Suzhou, Nanjing, Ningbo and Hangzhou – in the YRD. The chemical composition of PM 2.5 was analyzed and the light extinction resulting from each chemical species was calculated using the IMPROVE algorithm. A typical heavy haze episode was selected and the chemical mass balance (CMB) model was applied to identify the sources of PM 2.5 . The average PM 2.5 and PM 10 mass concentrations during the haze episode were 100 ± 24 μg/m 3 and 164 ± 19 μg/m 3 , respectively; visibility decreased to 1 km. Organic matter (OM), sulfate, nitrate, and ammonium were the dominant components of PM 2.5 , accounting for 33%, 19%, 17% and 11% of PM 2.5 mass, respectively. Sulfate, OM and nitrate had the highest impact on light extinction, contributing 30%, 28% and 19%, respectively. The source apportionment indicate that PM 2.5 is primarily from secondary pollutants and primary emissions from vehicles and biomass burning. A polluted air mass from north Jiangsu Province and stagnant meteorology further aggravated the haze pollution. The five cities had similar characteristics and pollution sources. [ABSTRACT FROM AUTHOR]

PM 2.5 with its major chemical components were measured and analyzed during a concurrent haze in Jan. 1–19, 2013 at three sites (Shanghai, Beijing, and Huaniao, a remote isle over the East China Sea) to probe the sources and formation process of such a severe haze over three typical regions in China. The mean PM 2.5 concentrations during the severely polluted days reached 180.8 μg m −3 , 299.2 μg m −3 , and 131.1 μg m −3 in Shanghai, Beijing, and the Huaniao Isle, respectively. The mass ratio of the sum of SO 4 2 − , NO 3 − , and NH 4 + to PM 2.5 were over 1/3 during the polluted days at all the three sites. Promoted gas-to-particle transformations from acidic SO 2 and NO x to SO 4 2 − and NO 3 − under high relative humidity conditions played a major role in the formation of this severe haze. Significant contribution of traffic emissions to the haze formation over China was suggested to be one of the major sources in triggering the heavy haze over China. Specifically, there was a more contribution from traffic in Shanghai than in Beijing as indicated by the higher NO 3 − / SO 4 2− ratio in Shanghai. In Beijing, the enhanced coal combustion for winter heating along with the traffic emission was suggested to be the major two sources of this haze episode. Typical pollution elements such as As, Cd, and Pb as well as Cl − and K + were substantially enhanced in the severely polluted days. Although the Huaniao Isle is located in the remote oceanic area as a background site, pollution elements, secondary ions, and K + all increased substantially during the polluted days. As visualized by the backward air mass trajectories associated with the potential source region identification technique, air masses that passed over Northern China and Yangtze River Delta evidently invaded the offshore areas of Eastern China. The ratios of As, Cd, Cu, Zn, and K + to Al at the Huaniao Isle were closer to those of Beijing rather than Shanghai, indicating that the marine aerosol over the East China Sea had been significantly polluted via the long-range transport of anthropogenic pollutants originating from Northern China. [ABSTRACT FROM AUTHOR]

Abstract: A multi-year (2004–2008) study of horizontal visibility and factors controlling its variations was conducted in Shanghai. The seasonal average visibility in spring, summer, autumn, and winter was 7.7 km, 8.4 km, 8.1 km, and 6.5 km, respectively, significantly exceeding the haze criteria of 10 km throughout all four seasons. Although SO2 and NO2 concentrations gradually shifted to lower levels on an annual basis, no distinct improvement of the annual mean visibility was noticed. Via a grouping method, it was found that the water soluble ions and black carbon were the major contributors to haze formation while the role of mineral aerosol was negligible. Of the ions, SO4 2−, NO3 −, NH4 +, K+, and C2O4 2− were most associated with the formation of heavy haze. SO4 2− and NO3 − were both found to have significant decreasing trends with annual decreasing rates of 0.96 and 0.56 μg/m3/yr, respectively. Conversely, NH4 + showed a significant increasing trend with the annual increasing rate of 0.52 μg/m3/yr. Based on a quantitative correlation analysis, the roles of NH4 + and Ca2+ on the acids neutralization were almost equivalent in the earlier years of 2004–2005. While the role of Ca2+ had tremendously dropped to less than 23% in the later years of 2006–2008. Intense control measures on the emissions of construction works and roadside dust were the main driving force for the evident decreasing trend of annual Ca2+ concentrations. This study found that the gradual replacement of CaSO4 and Ca(NO3)2 by (NH4)2SO4 and NH4NO3 in aerosol was the major cause of no improvement of the visibility impairment in Shanghai during recent years. [Copyright &y& Elsevier]

High levels of formaldehyde (HCHO) have been frequently detected during spring-summertime in the densely populated and rapidly developing Yangtze River Delta (YRD) region, China. However, the detailed formation mechanism of HCHO pollution remains unclear. Based on a comprehensive field campaign conducted at Dianshan Lake (DSL) station, a supersite located in the suburban YRD region, the influence of VOCs on HCHO formation, as well as the role of HCHO in the RO x radical recycling was analyzed. Results indicate that the maximum atmospheric oxidation capability (AOC) during HCHO pollution episodes varies from 0.65 × 108 to 1.29 × 108 molecules cm−3 s−1, and high AOC value favors the secondary formation of HCHO. Meanwhile, the photolysis of HCHO accounts for 21.2% of the primary RO x , suggesting the significant role of HCHO in RO x recycling. Isoprene was identified to be a key precursor of HCHO, and the RO from isoprene contributed ∼15% to the total daytime HCHO production rate (P HCHO). Sensitivity analysis reveal that when isoprene, xylene or ethylene was cut off, the simulated HCHO concentration could be reduced by 50%, 15%, or 13%, respectively. Based on the isopleth of HCHO under different VOCs/NO x reduction ratios, we found that the VOCs/NO x reduction ratio should be above 1.03 to mitigate the HCHO pollution. Reactive VOCs (such as isoprene, xylene and alkenes) should be reduced to suppress HCHO pollution in the YRD region. [Display omitted] • Photolysis of HCHO is a significant source of RO x. • Isoprene was found as a key precursor of HCHO. • More active VOCs should be reduced to mitigate HCHO pollution in the YRD region. [ABSTRACT FROM AUTHOR]

Abstract: To characterize the air pollutants in Shanghai Port and identify the contribution from ship traffic emission, field measurements have been conducted in 2011. The trace gases SO2, NO2 and O3 were monitored and aerosol samples of TSP, PM2.5 and size-segregated particles were collected in a working area of Shanghai Port. Elements including V, Ni, Al, Fe, Si, Ca, Na, Mg, Mn, Zn, Co, Cr in aerosol samples and heavy fuel oil samples were analyzed. The results revealed that average hourly SO2 and NO2 concentrations in Shanghai Port were respectively 29.4 and 63.7 μg m−3, average daily concentrations of TSP and PM2.5 were 114.39 and 62.60 μg m−3, comparable with the ones in Shanghai land area. Ni and V were found enriched in fine particles with averaged concentrations of 80.0 and 14.8 ng m−3 in PM2.5 respectively. Also ratio of V/Ni in aerosol under summertime airflow was 3.4, very close to the ratio of averaged V and Ni content in international heavy fuel oils used in Shanghai Port. The backward trajectory analysis further revealed that SO2, NO2, and V under coastal airflows were mainly from ship traffic emission. The mean concentration of V was 15.84 ng m−3 under hybrid coastal airflows, much higher than that of 9.84 ng m−3 under continental airflows. Furthermore, V was found to be highly correlated with ship fluxes, and was selected as an indicator of ship traffic emission in Shanghai. The estimated primary PM2.5 contribution from ship traffic ranged from 0.63 to 3.58 μg m−3, with an average of 1.96 μg m−3. This PM2.5 fraction accounted for 4.23% of the total PM2.5 in an average level, and reached to a maximum of 12.8%. Furthermore, there could be 64% of primary PM2.5 contributed by ships in Shanghai Port transported to inland region. Our results suggest that ship traffic has a non-negligible contribution on ambient levels of fine particles and secondary contribution of SO2 and NO2 emitted by ships need to be estimated on local and regional scale in future. [Copyright &y& Elsevier]

Odor pollutants from a landfill can have serious impacts on the surrounding environment and nearby residents. Moreover, the variety and complexity of volatile organic compounds (VOCs) along with the landfill odor makes sampling and identifying compounds challenging. In this study, the authors monitored municipal solid waste (MSW)-related areas, sludge-related areas and waste coverage with the most malodorous compounds. In terms of all 120 VOCs, 67 malodorous VOCs with significant variations were categorized into six classes of compounds under all test conditions. Among the concentration characteristics, Site B concentrations were the highest. For the odor index (OI), the OI values of Site B were higher than those on other sites. The organic sulfides, organic acids and amine were the major malodorous pollutants emitted from landfill and influenced the residential area. Through a coefficient of divergence analysis, the CD jk values of Sites A (0.66) and B (0.69) were lower than others, indicating the effects of odor emission on the surrounding residential area were slightly more severe than on the other sites because of the meteorological condition during the study period. The results of this study can provide essential information to enhance understanding the actual odor emission intensity and characteristics of landfill and the migration, transportation and influence of odorant emissions on the working surface of the landfill. [Display omitted] • Various VOCs from a typical landfill were monitored and distinguished. • The most abundant odorous contributors to total odors were calculated. • Malodorous landfill gases had a slightly effect on residential areas. [ABSTRACT FROM AUTHOR]

Scarce evidence is available on the health effects of various chemical constituents of PM 2.5 on hospital visits in China. To examine the short-term associations between a wide range of PM 2.5 constituents and hospital outpatient and emergency room visits in Shanghai. We obtained daily concentrations of PM 2.5 total mass, organic carbon (OC), elemental carbon (EC), eight water-soluble ions and thirteen elemental constituents between January 1, 2014 and December 31, 2015. We analyzed the data using over dispersed generalized additive models with Poisson regression. Single-constituent, PM 2.5 -adjusted and constituent-residual models were built respectively to assess the associations. Exposure-response curves for the PM 2.5 constituents with robust effects were graphed. The average daily mean PM 2.5 concentration was 63.3 μg/m3 in Shanghai during the study period. An interquartile range (IQR) increase in PM 2.5 was associated with a 2.57% (95% confidence interval [CI]: 1.28%, 3.87%) increase in outpatient visits, and a 3.60% (95% CI: 2.16%, 5.03%) increase in emergency room visits. We observed robust and positive associations between Mg2+, Ca2+, six elemental components (Ca, Mn, Fe, Zn, Ga and Se) and outpatient visits. OC, EC, Cl−, Mg2+, Ca2+ and ten elemental components (Ca, Cr, Mn, Fe, Zn, Ga, As, Se, Pb, and Ni) were significantly and positively associated with emergency room visits. The exposure-response relationships were positive and generally linear for the above constituents. This time-series study in Shanghai demonstrated significant associations between various carbonaceous, water-soluble and elemental constituents of PM 2.5 and hospital visits, providing evidence for source-specific control of particulate air pollution. [Display omitted] • Scarce evidence on the health effects of PM 2.5 constituents on hospital visits. • Mg2+, Ca2+ and six elemental constituents linked with outpatient visits. • Carbonaceous and ten elemental constituents associated with emergency room visits. • Positive and linear exposure-response relationship curves for these constituents. [ABSTRACT FROM AUTHOR]

Based on the concentrations of the carbonaceous components and the typical organic tracers in 682 p.m. 2.5 samples collected in Shanghai from 2012 to 2018, the temporal trends of the concentrations and potential sources of the secondary organic aerosols in PM 2.5 in Shanghai were investigated. The annual average concentrations of organic carbon (OC), elemental carbon (EC) and water-soluble organic carbon (WSOC) all showed a decreasing trend along with the PM 2.5 concentration. The annual concentration of total carbon (TC) in 2018 (4.3 μg m−3) was about 34% of that in 2012. Compared with that in 2013, the concentrations of isoprene and sesquiterpene SOA tracers in 2018 decreased by 48% and 43%. Meanwhile, the concentration of monoterpene SOA tracers kept stable in 2 ng m−3 to 3 ng m−3, and the concentration of toluene SOA tracer decreased slightly from 1.3 ng m−3 in 2013 to 1.0 ng m−3 in 2018. Correlation analysis with levoglucosan suggested that biomass burning should be an important source of sesquitertene in Shanghai. It was found that the 2-MGA/2-MTLs ratio of the isoprene tracers was more strongly affected by the ambient temperature but not NOx in Shanghai. The concentration of secondary organic carbon (SOC) estimated with OC/EC-based, WSOC-based and tracer-based methods showed a decreasing trend during the study period, but the contribution of SOC to OC was increasing. Anthropogenic aromatic volatile organic compounds was the increasingly important contributor to the SOC in PM 2.5 , and should be the key pollutants to be controlled to further improve the air quality in Shanghai. • Temporal trend of SOC in PM 2.5 in Shanghai during 2012 and 2018 investigated. • The concentration of SOC decreasing while the contribution to OC increasing in the last decade. • Relative contribution of SOA from toluene was found increased but not decreased. • Biomass burning was the important source of seisquiterpene in Shanghai. • 2-MG/2-MTLs ratio in urban environment strongly affected by ambient temperature. [ABSTRACT FROM AUTHOR]

To investigate the potential public health impact of ambient air pollution under various energy scenarios in Shanghai, we estimated the air pollution exposure level of the general population under various planned energy scenarios, and assessed the potential public health impact using the concentration–response functions derived from available epidemiologic studies. The results show that ambient air pollution in relation to various energy scenarios could have significant impact on the health status of Shanghai residents. Compared with base case scenario, implementation of various energy scenarios could prevent 608–5144 and 1189–10,462 PM10-related avoidable deaths (mid-value) in 2010 and 2020, respectively; and it could also decrease substantial cases of relevant diseases. These findings illustrate that an effective energy and environmental policy will play an active role in reduction of air pollutant emissions, improvement of air quality, and public health. [Copyright &y& Elsevier]

China's lockdown to control COVID-19 brought significant declines in air pollutant emissions, but haze was still a serious problem in North China Plain (NCP) during late-January to mid-February of 2020. We seek the potential causes for the poor air quality in NCP combining satellite data, ground measurements and model analyses. Efforts to constrain COVID-19 result in a drop-off of primary gaseous pollutants, e.g., −42.4% for surface nitrogen dioxide (NO 2) and −38.9% for tropospheric NO 2 column, but fine particulate matter (PM 25) still remains high and ozone (O 3) even increases sharply (+84.1%). Stagnant weather during COVID-19 outbreak, e.g., persistent low wind speed, frequent temperature inversion and wind convergence, is one of the major drivers for the poor air quality in NCP. The surface PM 2.5 levels vary between −12.9~+15.1% in NCP driven by the varying climate conditions between the years 2000 and 2020. Besides, the persistent PM 2.5 pollution might be maintained by the still intensive industrial and residential emissions (primary PM 2.5), and increased atmospheric oxidants (+26.1% for ozone and +29.4% for hydroxyl radical) in response to the NO 2 decline (secondary PM 2.5). Further understanding the nonlinear response between atmospheric secondary aerosols and NO x emissions is meaningful to cope with the emerging air pollution problems in China. Image 1 • Both satellite data and ground measurements confirm improved NO 2 air quality. • PM 2.5 varies between −12.9~+15.1% driven by climate conditions. • High PM 2.5 is maintained by intensive primary emission and increased oxidants. [ABSTRACT FROM AUTHOR]

One vertical observation field campaign based on a tethered mega-balloon (with onboard instruments over 200 kg) was conducted at a campus site in rural Shanghai in order to investigate the vertical distributions of key air pollutants (PM 2.5 , SO 2 , black carbon (BC) and O 3) and regional transport characteristics during a severe air pollution episode in mid-December 2015. Vertical patterns of measured air pollutants show relatively even profiles within the planetary boundary layer (PBL) while declined sharply above PBL during the daytime. Specifically, high concentrations of SO 2 were observed near the top of the boundary layer. Lagrangian particle dispersion modeling showed air pollutants within the boundary layer mainly derived from local sources (i.e. Shanghai) and regional transport within the Yangtze River Delta (YRD) region in the morning before the development of boundary layer. Aerosol chemical components measured at a ground site (about 60 km northwest of the balloon site) showed that regional transport brought a large amount of aged sulfate and nitrate. This study provides new insights in the vertical distribution and transport of haze associated with the PBL development and long-range transport. • A vertical observation from 0 to 1000 m based on a tethered mega-balloon was conducted in winter of 2015, Shanghai. • Vertical profiles of key air pollutants (PM 2.5 , SO 2 , O 3 and black carbon) with high spatiotemporal resolution were revealed. • PM 2.5 in Shanghai was mainly derived from transport within the YRD based on a synergy of measurement techniques. • Nitrate contributed most to the increase of PM 2.5 with high SO 2 during regional transport. [ABSTRACT FROM AUTHOR]

Ambient heavy fine particulate matter (PM 2.5) pollution events occur frequently during winter seasons in eastern China. Investigating the evolution of source contributions during heavy pollution episodes is critical for strategies of pollution relief. In this study, a two-month field campaign was conducted in the winters of 2015 and 2016 at a regional supersite in eastern China and over one thousand hourly online measurements for twenty PM 2.5 species were obtained. Hourly source apportionment for the total mass of PM 2.5 , and its major species (primary organic carbon, elemental carbon, nitrate, sulfate and ammonium), were then performed by Positive Matrix Factorization (PMF) and Multilinear Engine-2 (ME2) models. Three PM 2.5 heavy pollution episodes including ten high concentration peaks were identified for further analysis. Results showed that ME2 performed better than PMF by fixing source profiles of secondary nitrate, secondary sulfate and sea salt, although they have dominant consistencies. Two types of pollution sources were identified from high PM 2.5 mass peaks: coal combustion-oriented responsible for four peaks and secondary inorganic aerosol-oriented responsible for the remaining six peaks. Low wind speed and planetary boundary layer favorited the coal combustion-oriented peaks, but also weakened the secondary inorganic formation due to low temperature and accumulated nitric oxide. Primary emissions from coal combustion can contribute 18% to ammonium in addition to 72% from secondary inorganic aerosol. Secondary organic aerosol would contribute 20% of PM 2.5 mass during the heaviest episodes. Findings in this study provide insights into the causes of heavy pollution episodes and support implementing effective control strategies to mitigate heavy pollution events in eastern China. • Distinct source characteristics during heavy pollution evolution could be identified based on high time resolution. • Coal combustion and secondary inorganic aerosol were responsible for the highest PM 2.5 mass peaks separately. • ME2 fixing known source profiles could obtain more reasonable apportionment results than PMF. [ABSTRACT FROM AUTHOR]

Volatile organic compounds (VOCs) are important precursors of photochemical smog and secondary organic aerosol (SOA). Quantitatively assessing the impact of VOCs on ozone (O 3) formation could provide valuable information for the management of emission reduction and photochemical pollution control. In this study, we first figured out the ozone pollution episodes during 2018 at Dianshan Lake (DSL), which is located in the suburban area of Shanghai and is adjacent to three provinces of the YRD region. Then we analyzed continuous variation of O 3 precursors and meteorological parameters. The online measurements show that the average volume mixing ratio of total VOCs (TVOC) was 15.41 ± 11.39 ppbv during the ozone pollution episodes, with the largest contribution from alkanes. To further identify the sources of VOCs, VOC concentration-weighted trajectories (CWT) were analyzed, and the results suggested that Zhejiang province could be the most important source region of VOCs at DSL. Analysis using an observation-base model showed that NO x and alkenes exhibited the most significant negative and positive influences on O 3 formation, respectively. As for individual species, toluene and isoprene, whose S-weighted concentrations were 6.67 × 10−2 and 5.94 × 10−2 ppbv, respectively, were the key factors promoting the formation of O 3 at DSL. To control the increase of O 3 , considering the policy feasibility, the abatement ratio of VOCs/NO x should be no less than 0.72. The findings advanced our knowledge of VOCs and their impact on O 3 formation and will be helpful in formulating emission control strategies for coping with O 3 pollution in YRD region. • Characteristics of ambient VOCs and their influences on O 3 formation in a rural area downwind Shanghai were investigated. • Strong photochemical losses of VOCs, especially alkenes, were found under high O x concentrations situations. • Abatement ratio of VOCs/NOx should be no less than 0.72 to effectively control O 3. [ABSTRACT FROM AUTHOR]

Carbonaceous aerosols have adverse effects on both human health and the climate. To understand the temporal variations and sources of carbonaceous aerosols, organic carbon (OC) and elemental carbon (EC) were measured hourly in suburban Shanghai in 2015–2017 during winter. The average OC concentrations were 7.34 ± 4.51 μgC/m3 in 2015, 7.16 ± 4.43 μgC/m3 in 2016, and 6.4 ± 3.22 μgC/m3 in 2017. The EC concentrations decreased significantly each year, with average concentrations of 3.82 ± 2.43, 2.91 ± 2.28, and 2.46 ± 1.88 μgC/m3, respectively, which caused the OC/EC ratio to increase from 2015 to 2017. Although the meteorological conditions differed each winter, there was a similar pattern of OC and EC diurnal variations, with concentrations peaking at 08:00 and 20:00, largely due to rush-hour vehicle emissions. A downward trend of EC/CO and EC/NO 2 (mass ratios) but steady CO and NO 2 concentrations from 2015 to 2017 revealed that the characteristics of primary vehicle emissions changed, and that less EC was emitted. Secondary organic carbon (SOC) and primary organic carbon (POC) were estimated with the minimum R 2 (MRS) method. The hiemal SOC/OC values in suburban Shanghai were 19.2 ± 18.6% in 2015, 31.1 ± 18.6% in 2016, and 51.0 ± 21.4% in 2017, exhibiting an increasing trend. As the PM 2.5 concentration increased (from 0 to 50 μg/m3 to 100–300 μg/m3), a decreasing SOC/OC ratio (from 43.6 ± 23.9% to 21.8 ± 17.7%) was observed over the three years, showing that primary emissions were the main contributors to carbonaceous aerosols on haze days. Case analysis of haze events further demonstrated that the primary sources of OC and EC were vehicle emissions. The contributions of biomass burning and coal combustion to carbonaceous aerosols became less important over the study period. This study highlights the importance of controlling vehicle emissions to reduce carbonaceous aerosol concentrations in the suburbs of the Chinese megacity, Shanghai. Image 1 • Hourly OC and EC were analyzed at suburban Shanghai in winter 2015 to 2017. • SOC/OC decreased with increased PM 2.5 pollution. • Biomass burning and coal combustion contribution to OC and EC decreased. • Vehicle emissions are the dominant source of carbonaceous aeorosols. [ABSTRACT FROM AUTHOR]

Portable air pollutant monitors onboard unmanned aerial systems (UAS) are increasingly being used to make vertical observations within the lower part of the troposphere. An overall evaluation of the UAS platform is critical before its wide application. To our knowledge, these evaluations have rarely been reported. This study is aimed at evaluating the performance of a fixed-wing UAS platform that is deployed with portable ozone (O 3) and fine particulate matter (PM 2.5) monitors. A tethered airship platform deployed with conventional O 3 and PM 2.5 monitors was used as a reference method to evaluate the UAS platform. To obtain custom calibration factors, the portable monitors were evaluated primarily with respect to corresponding conventional monitors at the ground level in three atmospheric environments. Then, the UAS assessment experiment was conducted over a coastal area in Shanghai, China. Seven statistical metrics were used to assess the performance of the portable monitors on the UAS platform. The results revealed that the portable monitors were capable of accurately capturing temporal variations in air pollutant concentrations after custom calibrations. The UAS platform could also accurately capture the vertical variations in O 3 and PM 2.5 concentrations within the lower troposphere. However, significant discrepancies between the UAS and airship platforms were observed for both O 3 and PM 2.5 measurements within the planetary boundary layer (PBL). The relative humidity (RH) values measured in this layer demonstrated significantly larger vertical variations and were substantially larger than those above the PBL. The discrepancies between the two platforms were associated mainly with horizontal variations in the UAS measurements over the experimental area, as well as large vertical variations in ambient temperature and RH within the lower troposphere. • Portable O 3 and PM 2.5 monitors were deployed on an UAS platform. • Portable monitors agree well with conventional monitors in temporal variations. • The fixed wing UAS platform was evaluated against a tethered airship platform. • The UAS platform could well capture the vertical variations in both O 3 and PM 2.5. [ABSTRACT FROM AUTHOR]

Few studies have investigated respiratory effects of particulate matter air pollution using a full range of particle size distribution. To explore the short-term associations between size-fractionated particle number concentration (PNC) and chronic obstructive pulmonary disease (COPD) mortality. We conducted a time-series study to explore the associations between size-fractionated PNC and daily COPD mortality in the Pudong New Area of Shanghai, China, from 2014 to 2016. We evaluated particle size distribution from 0.01 μm to 10 μm, which was segregated into 7 ranges to better explore the size-dependent associations. We used over-dispersed generalized additive models to estimate the associations after controlling for time trends, temperature, humidity, day of the week and holidays. A total of 5430 deaths due to COPD were identified during the study period. For size ranges from 2.5 – 10 μm, 1–2.5 μm to 0.3–1 μm, there were stronger associations between PNC and COPD mortality, but the associations were statistically insignificant. However, for the smaller size ranges from 0.3 to 0.01 μm, the associations became statistically significant and the magnitude of association remained stable. An interquartile range increase in PNC at lag 0–1 day for size ranges 0.01–0.03 μm, 0.03–0.05 μm, 0.05–0.1 μm and 0.1–0.3 μm was associated with increments of 4.44% (95% CI: 1.16%, 7.73%), 4.31% (95% CI: 1.16%, 7.47%), 4.22% (95% CI: 1.05%, 7.40%), and 4.28% (95% CI: 0.48%, 8.09%) in COPD mortality, respectively. This study suggested that particles below 0.3 μm in diameter might be mainly responsible for the adverse effect of particulate air pollution on CDPD mortality in Shanghai, China. • A study linking a full range of particle size distribution and COPD mortality. • The associations generally increased with smaller particle size. • Particles below 0.3 μm in diameter may be mainly responsible for the associations. • Particles above 0.3 μm in diameter showed no significant associations. [ABSTRACT FROM AUTHOR]