COVID-19-associated 2020 lockdown: a study on atmospheric black carbon fall impact on human health.

The mean mass concentrations of black carbon (BC), biomass burning (BC)bb, and fossil fuel combustion (BC)ff have been estimated during March-May 2020 (during the COVID-19 outbreak) and March-May 2019 at a semiarid region of Agra over the Indo-Gangetic basin region. The daily mean mass concentration of BC in 2020 and 2019 was 3.9 and 6.9 µg m-3, respectively. The high monthly mean mass concentration of BC was found to be 4.7, 3.4 and 3.3 µg m-3 in Mar-2020, Apr-2020, and May-2020, respectively, whereas in Mar-2019, Apr-2019, and May-2019 was 7.7, 7.5 and 5.4 µg m-3, respectively. The absorption coefficient (babs) and absorption angstrom exponent (AAE) of black carbon were calculated. The highest mean AAE was 1.6 in the year 2020 (Mar-May 2020) indicating the dominance of biomass burning. The mean mass concentration of fossil fuel (BC)ff and biomass burning (BC)bb is 3.4 and 0.51 µg m-3, respectively, in 2020 whereas 6.4 and 0.73 µg m-3, respectively, in 2019. The mean fraction contribution of BC with fossil fuel (BC)ff was 82.1 ± 13.5% and biomass burning (BC)bb was 17.9 ± 4.3% in 2020, while in 2019, fossil fuel (BC)ff was 86.7 ± 13.5% and biomass burning (BC)bb was 13.3 ± 6.7%. The population-weighted mean concentration of BC, fossil fuel (BC)ff, and biomass burning (BC)bb has been calculated. The health risk assessment of BC has been analyzed in the form of attributable relative risk factors and attributed relative risk during the COVID-19 outbreak using AirQ + v.2.0 model. The attributable relative risk factors of BC were 20.6% in 2020 and 29.4% in 2019. The mean attributed relative risk per 10,000,000 populations at 95% confidence interval (CI) due to BC was 184.06 (142.6-225.2) in 2020 and 609.06 (418.3-714.6) in 2019. The low attributed factor and attributed relative risk in 2020 may be attributed to improvements in air quality and a fall in the emission of BC. In 2020, due to the COVID-19 pandemic, the whole country faced the biggest lockdown, ban of the transportation of private vehicles, trains, aircraft, and construction activities, and shut down of the industry leading to a fall in the impact of BC on human health. Overall, this was like a blessing in disguise. This study will help in future planning of mitigation and emission control of air pollutants in large and BC in particular. It only needs a multipronged approach. This study may be like torch bearing to set path for mitigation of impacts of air pollution and improvement of air quality.

Implications of the Improvement in Atmospheric Fine Particles: A Case Study of COVID-19 Pandemic in Northern Taiwan

The outbreak of COVID-19 pandemic in northern Taiwan led to the implementation of Level 3 alert measures during 2021 and thereby impacted the air quality significantly, which provided an unprecedented opportunity to better understand the control strategies on air pollutants in the future. This study investigated the variations in sources, chemical characteristics and human health risks of PM2.5 comprehensively. The PM2.5 mass concentrations decreased from pre-alert to Level 3 alert by 49.4%, and the inorganic ions, i.e., NH4+, NO3- and SO42-, dropped even more by 71%, 90% and 52%, respectively. Nonetheless, organic matter (OM) and elemental carbon (EC) simply decreased by 36% and 13%, which caused the chemical composition of PM2.5 to change so that the carbonaceous matter in PM2.5 dominated instead of the inorganic ions. Correlation-based hierarchical clustering analysis further showed that PM2.5 was clustered with carbonaceous matter during the Level 3 alert, while that clustered with inorganic ions during both pre-alert and post-alert periods. Moreover, 6 sources of PM2.5 were identified by positive matrix factorization (PMF), in which secondary nitrate (i.e., aging traffic aerosols) exhibited the most significant decrease and yet primary traffic-related emissions, dominated by carbonaceous matter, changed insignificantly. This implied that secondary traffic-related aerosols could be easily controlled when traffic volume declined, while primary traffic source needs more efforts in the future, especially for the reduction of carbonaceous matter. Therefore, cleaner energy for vehicles is still needed. Assessments of both carcinogenic risk and non-carcinogenic risk induced by the trace elements in PM2.5 showed insignificant decrease, which can be attributed to the factories that did not shut down during Level 3 alert. This study serves as a metric to underpin the mitigation strategies of air pollution in the future and highlights the importance of carbonaceous matter for the reduction in PM2.5.

Characterization and Source Apportionment of PM in Handan—A Case Study during the COVID-19

Handan is a typical city affected by regional particulate pollution. In order to investigate particulate matter (PM) characterization, source contributions and health risks for the general populations, we collected PM samples at two sites affected by a pollution event (12–18 May 2020) during the COVID-19 pandemic and analyzed the major components (SNA, OCEC, WSIIs, and metal elements). A PCA-MLR model was used for source apportionment. The carcinogenic and non-carcinogenic risks caused by metal elements in the PM were assessed. The results show that the renewal of old neighborhoods significantly influences local PM, and primarily the PM10;the average contribution to PM10 was 27 μg/m3. The source apportionment has indicated that all other elements came from dust, except Cd, Pb and Zn, and the contribution of the dust source to PM was 60.4%. As PM2.5 grew to PM10, the PM changed from basic to acidic, resulting in a lower NH4+ concentration in PM10 than PM2.5. The carcinogenic risk of PM10 was more than 1 × 10−6 for both children and adults, and the excess mortality caused by the renewal of the community increased by 23%. Authorities should pay more attention to the impact of renewal on air quality. The backward trajectory and PSCF calculations show that both local sources and short-distance transport contribute to PM—local sources for PM10, and short-distance transport in southern Hebei, northern Henan and northern Anhui for PM2.5, SO2 and NO2. © 2023 by the authors.

Changes of atmospheric metal(loid) deposition from 2017 to 2021 at Mount Emei under China's air pollution control strategy

Acid deposition and particulate matter (PM) pollution have declined considerably in China. Although metal(loid) and acid deposition and PM have many common sources, the changes of metal(loid) deposition in China in the recent decade have not been well explored by using long-term monitoring. Therefore, we analyzed the dry and wet deposition of eleven metal(loid)s (including Al, As, Ba, Cd, Cu, Cr, Fe, Mn, Pb, Sr, and Zn) from 2017 to 2021 at Mount Emei, which is adjacent to the most economic-developed region in western China (Sichuan Basin (SCB)). Anthropogenic emissions contributed to over 80% of the annual wet deposition fluxes of metal(loid)s and acids (SO4 2-, NO3 -, and NH4 +) at Mount Emei, and the major source regions were the SCB, the Yunnan-Guizhou Plateau, and Gansu Province. Metal(loid) and acid deposition had similar seasonal variations with higher wet deposition fluxes in summer but higher wet deposition concentrations and dry fluxes in winter. The seasonal variations were partially associated with higher precipitation but lower pH in summer (968 mm and 5.52, respectively) than in winter (47 mm and 4.73, respectively). From 2017 to 2021, metal(loid) deposition did not decline as substantially as acid deposition (5.6%-30.4%). Both the annual total deposition fluxes and concentrations of Cr, Cu, Sr, Ba, and Pb were even higher in 2020-2021 than in 2017-2018. The inter-annual and seasonal changes implied the responses of metal(loid) deposition to anthropogenic emission changes were buffered (e.g., transformation, dilution, and degradation) by precipitation rates, acidity, natural emissions, and chemical reactions in the atmosphere, among others.Copyright © 2023 Elsevier Ltd

Positive Matrix Factorization as Source Apportionment of Paddy Soil Heavy Metals in Black Shale Areas in Western Zhejiang Province, China

The source apportionment of pollutants is the key to preventing and controlling the pollution caused by heavy metals in soils. The aim of this study was to investigate the main sources of heavy metals in the soils of black shale areas in western Zhejiang, China. Based on geostatistical spatial analysis, this research employed positive matrix factorization (PMF) for the source apportionment of heavy metals in paddy soil. The results showed that contaminated arable soils were concentrated in the western and southern study areas. At least five major sources of heavy metals were screened in this study: natural sources (39.66%), traffic emissions (32.85%), industrial emissions (9.23%), agricultural activities (9.17%), and mining (9.10%). To be specific, Cd was mainly from mining;As originated from agricultural inputs such as fertilizers and pesticides;and Hg, as an industrial pollutant, was transported by atmospheric deposition in the study area. The accumulation of Pb, Zn, and Cu was mainly influenced by natural sources and anthropogenic sources, i.e., traffic emissions, while that of Cr and Ni was controlled by natural sources.

[Variations in PM2.5 Composition and Sources During 2020-2021 COVID-19 Epidemic Periods in Nanjing].

To understand the changes in chemical composition and sources of PM2.5 under the extreme reduction background during the COVID-19 epidemic periods in Nanjing, hourly observation results of PM2.5 components (water-soluble inorganic ions, carbonaceous components, and inorganic elements) of two epidemic events from January to March 2020 and June to August 2021 were analyzed. In comparison to that during pre-epidemic periods, the concentration of NO3- during the two epidemic control periods decreased by 52.9% and 43.0%, respectively, which was larger than the decreases in NH4+(46.4% and 31.6%) and SO42-(33.8% and 16.5%). Since the observation site was located close to a main road, the decrease in elemental carbon (EC, 35.4% and 20.6%) was higher than that in organic carbon (OC, 11.1% and 16.2%). In reference to the variations in the characteristic ratios of the bulk components mentioned above, the epidemic control showed a more substantial influence on traffic emissions than industrial activities. The concentration time series of PM2.5 major components over the epidemic periods indicated that NOx from local traffic emissions had substantial contributions to the formation of NO3-, which led to local short-term PM2.5 pollution. In addition, the positive matrix factorization (PMF) model was used to analyze the hourly observation data of PM2.5 components. The seven identified factors were linked with metallurgy, firework and firecracker combustions, road traffic emissions, coal combustion, dust resuspension, secondary sulfate, and secondary nitrate. Because the nitrate was unstable under high temperature, the contribution of secondary nitrate to PM2.5 during the epidemic control period of 2021 (summer, 21.2%) was much lower than that during the epidemic control period of 2020 (winter, 60.6%); however, the formation of secondary components always dominated the contribution of PM2.5 sources. Therefore, emissions of NOx and SO2 should be further controlled to continuously reduce ambient PM2.5 concentrations in Chinese cities.

Emissions of black carbon and polycyclic aromatic hydrocarbons: Potential implications of cultural practices during the Covid-19 pandemic

Emissions of black carbon (BC) and polycyclic aromatic hydrocarbons (PAHs) from various anthropogenic activities are often reported, yet cultural practices such as the multi-day Diwali festival and its influences on the emissions of these compounds are often overlooked. Major activities during this festival include burning rows of oil-filled earthen lamps (diyas) and fireworks (bursting of crackers). A comprehensive field investigation was conducted to document the role of Diwali celebrations on the releases of BC and PAHs during the ongoing Covid pandemic. The results show that large-scale releases of BC and PAHs were observed on the first day of Diwali compared to the remaining four days. BC and PM2.5 mass concentrations throughout the monitoring period ranged from 3.24 to 27.64 µg m−3 and 83.33 to 288.13 µg m−3, respectively. The source apportionment was performed based on the calculated backward trajectories. The results show that the contribution of fossil fuel emission at Adityapur (ADP), Sakchi (SAK), and Gamharia (GMA) was approximately 36.1 %, 34.4 %, and 55.56 %, while biomass burning contribution was approx. 56.9 %, 59.9 %, 41.67 %, respectively. The result showed that fossil fuel emissions were lower compared to biomass combustion during Diwali. Simultaneously, PAHs diagnostic ratio showed that vehicular discharge and coal burning significantly contributed to PAHs at these study sites. © 2022 The Author(s)

SOURCE APPORTIONMENT ANALYSIS IN PM AND O3 CONCENTRATIONS DURING COVID-19 LOCKDOWN PERIOD IN MADRID (SPAIN)

In a first analysis of the impacts of the reduction of anthropogenic emissions during COVID-19 lockdown over Madrid (Spain) area, we found an important NOx level reduction but the O3 and PM concentrations were increased. In this work the causes of the increments are studied using Source Apportionment Technology (SAT) included in the Comprehensive Air Quality Model with Extensions (CAMx) model. CAMx is driven by the Weather Research and Forecasting model (WRF). Two simulations are run: one simulation considers the emission reductions during the lockdown (COVID simulation) and a second simulation,” business as usual” (BAU simulation) with an emissions scenario without restrictions. Source apportionment techniques are used to identify and quantify the contributions from main pollution sources with the purpose to provide understanding on what measures should be taken to address them and this work shows the potential of these technique. SAT was used to estimate the contributions of multiple sources, and pollutant types (NOx and VOC) to ozone and particle formation in a single model run. Differences in SAT results under baseline (BAU) and COVID scenarios are used to quantify the contributions of O3 and PM2.5 reductions associated with emissions reduction in individual sectors due to the lowered human activities with a high spatial resolution (1 km). Road transport is the main emission source reduced by the lockdown and reduction in NOx emissions (59%) is higher that VOC reduction (14%). This study helps to elucidate the complex and nonlinear response of O3 and PM concentrations after a reduction of emissions mainly from the transport sector, during the COVID-19 lockdown period, that must be taken into account in the control strategies to mitigate haze pollution. The results show that despite extreme reductions in primary emissions, current air pollution cannot be fully tackled. Further consideration needs to be given to the reorganisation of energy and industrial strategy together with trans-regional joint monitoring for a comprehensive long-term air pollution plan. Source apportionment studies can support of authorities responsible to develop air quality plans. © British Crown Copyright (2022)

Enhanced natural releases of mercury in response to the reduction in anthropogenic emissions during the COVID-19 lockdown by explainable machine learning

The wide spread of the coronavirus (COVID-19) has significantly impacted the global human activities. Compared to numerous studies on conventional air pollutants, atmospheric mercury that has matched sources from both anthropogenic and natural emissions is rarely investigated. At a regional site in eastern China, an intensive measurement was performed, showing obvious decreases in gaseous elemental mercury (GEM) during the COVID-19 lockdown, while it was not as significant as most of the other measured air pollutants. Before the lockdown, when anthropogenic emissions dominated, GEM showed no correlation with temperature and negative correlations with wind speed and the height of the boundary layer. In contrast, GEM showed significant correlation with temperature, while the relationship between GEM and the wind speed/boundary layer disappeared during the lockdown, suggesting the enhanced natural emissions of mercury. By applying a machine learning model and the SHAP (SHapley Additive exPlanations) approach, it was found that the mercury pollution episodes before the lockdown were driven by anthropogenic sources, while they were mainly driven by natural sources during and after the lockdown. Source apportionment results showed that the absolute contribution of natural surface emissions to GEM unexpectedly increased (44 %) during the lockdown. Throughout the whole study period, a significant negative correlation was observed between the absolute contribution of natural and anthropogenic sources to GEM. We conclude that the natural release of mercury could be stimulated to compensate for the significantly reduced anthropogenic GEM via the surface-air exchange in the balance of mercury.

Heavy haze pollution during the COVID-19 lockdown in the Beijing-Tianjin-Hebei region, China.

To investigate the characteristics of particulate matter with an aerodynamic diameter less than 2.5 µm (PM2.5) and its chemical compositions in the Beijing-Tianjin-Hebei (BTH) region of China during the novel coronavirus disease (COVID-19) lockdown, the ground-based data of PM2.5, trace gases, water-soluble inorganic ions, and organic and elemental carbon were analyzed in three typical cities (Beijing, Tianjin, and Baoding) in the BTH region of China from 5-15 February 2020. The PM2.5 source apportionment was established by combining the weather research and forecasting model and comprehensive air quality model with extensions (WRF-CAMx). The results showed that the maximum daily PM2.5 concentration reached the heavy pollution level (>150 µg/m3) in the above three cities. The sum concentration of SO42-, NO3- and NH4+ played a dominant position in PM2.5 chemical compositions of Beijing, Tianjin, and Baoding; secondary transformation of gaseous pollutants contributed significantly to PM2.5 generation, and the secondary transformation was enhanced as the increased PM2.5 concentrations. The results of WRF-CAMx showed obviously inter-transport of PM2.5 in the BTH region; the contribution of transportation source decreased significantly than previous reports in Beijing, Tianjin, and Baoding during the COVID-19 lockdown; but the contribution of industrial and residential emission sources increased significantly with the increase of PM2.5 concentration, and industry emission sources contributed the most to PM2.5 concentrations. Therefore, control policies should be devoted to reducing industrial emissions and regional joint control strategies to mitigate haze pollution.

Hourly organic tracers-based source apportionment of PM2.5 before and during the Covid-19 lockdown in suburban Shanghai, China: Insights into regional transport influences and response to urban emission reductions.

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 PM2.5 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 NOx levels declined sharply by 59% from 44 to 18 ppb during the lockdown, while O3 rose two times higher to 42 ppb. The PM2.5 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 PM2.5 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.

Characteristics of PM2.5 concentration and water-soluble ions in the typical town of southern Gansu

In order to study the pollution levels of PM2.5 and water-soluble inorganic ions（WSIIs）in the towns of southern Gansu, PM2.5 samples were collected quarterly in Cheng County of Gansu from April 2019 to February 2020. Their characteristics of variation were analyzed, and the sources were apportioned using correlation and principal component analysis. The results showed that the mean annual mass concentration of PM2.5 was（57.2±26.9）μg·m-3 in Cheng County of Gansu Province. The seasonal variation of PM2.5 concentration was represented by winter>spring>autumn>summer during the sampling period, and the concentrations in winter were about 1.9 times than that in summer. The annually good air quality rate was 81%, of which 100% in summer. The ranking of WSII concentrations was SO42->NO3->Na+>NH4+>Ca2+>K+>Cl->Mg2+.SNA is the highest water-soluble ions, accounting for 70.1% of the concentration of eight main water-soluble ions. The mean ratio of ρ（NO3-）/ρ（SO42-）was 0.6, indicating that fixed sources such as industrial and agricultural production and fossil fuel combustion emissions, was the major source for particulate pollution. During the 2019 coronavirus epidemic, control measures had a significant impact on the concentration of PM2.5 and SNA in water-soluble ions, and the mean concentration of PM2.5 was reduced by 44.2%. Source apportionment showed that WSIIs in PM2.5 were mainly from fossil fuel combustion, biomass combustion, secondary formation and road construction dust, etc. © 2022 Science Press. All rights reserved.

PM2.5 bound species variation and source characterization in the post-lockdown period of the Covid-19 pandemic in Delhi

This work analyzes the PM2.5 bound highly time-resolved non-refractory and elemental compositions to observe the lag effects of the COVID-19 lockdown in the capital city of India. To the best of our knowledge, this is the first study that focuses on PM2.5 bound highly time-resolved chemical species and source apportionment to assess the contribution of various sources in the post lockdown period (June to September 2020). Here, a comparative scenario between lockdown and unlock periods along with previous years' work is presented. The following eight source profiles are identified from the source apportionment of elements such as power plant (35.6%), dust (25.7%), biomass burning (16.2%), vehicular emission (10%), secondary chloride (4%), waste incineration (3.6%), coal combustion (2.8%) and industrial emission (2.2%). The apportion sources of organic aerosol (OA) yielded two primary factors, primary organic aerosol (POA) and biomass burning organic aerosol (BBOA), and two secondary factors, oxygenated organic aerosols 1 and 2 (OOA-1 and OOA-2). The two oxygenated factors, OOA-1 and OOA-2 dominated the total OA mass concentration with 67.5% and 22% contribution, followed by POA and BBOA with 6.5% and 4%, respectively. The primary factors, POA and BBOA, also showed significant dependency on meteorological conditions during the post lockdown period. A significantly low contribution from the primary factors is seemingly the lagging effect of the lockdown imposed by the government in the earlier months. The meteorological conditions also significantly impacted OOA-1 concentration, which decreased by around 50% in August compared to June 2020. To understand the formation pathways of secondary nitrate and sulphate, NOR and SOR values were calculated and their variation during different RH periods was studied. It was found that photochemical oxidation was the primary pathway of SO2 to SO42− conversion while heterogeneous aqueous pathway was the primary mechanism for nitrate formation during the study period.

Evaluating the influence of constant source profile presumption on PMF analysis of PM2.5 by comparing long- and short-term hourly observation-based modeling.

Hourly PM2.5 speciation data have been widely used as an input of positive matrix factorization (PMF) model to apportion PM2.5 components to specific source-related factors. However, the influence of constant source profile presumption during the observation period is less investigated. In the current work, hourly concentrations of PM2.5 water-soluble inorganic ions, bulk organic and elemental carbon, and elements were obtained at an urban site in Nanjing, China from 2017 to 2020. PMF analysis based on observation data during specific pollution (firework combustion, sandstorm, and winter haze) and emission-reduction (COVID-19 pandemic) periods was compared with that using the whole 4-year data set (PMFwhole). Due to the lack of data variability, event-based PMF solutions did not separate secondary sulfate and nitrate. But they showed better performance in simulating average concentrations and temporal variations of input species, particularly for primary source markers, than the PMFwhole solution. After removing event data, PMF modeling was conducted for individual months (PMFmonth) and the 4-year period (PMF4-year), respectively. PMFmonth solutions reflected varied source profiles and contributions and reproduced monthly variations of input species better than the PMF4-year solution, but failed to capture seasonal patterns of secondary salts. Additionally, four winter pollution days were selected for hour-by-hour PMF simulations, and three sample sizes (500, 1000, and 2000) were tested using a moving window method. The results showed that using short-term observation data performed better in reflecting immediate changes in primary sources, which will benefit future air quality control when primary PM emissions begin to increase.

Comparative Analysis of Pollutant Levels during Lockdowns Across Different Land-Use over the Emirate of Abu Dhabi, United Arab Emirates

The outbreak of the COVID-19 pandemic has had a significant effect on people all over the world, posing health, economic, and social threats to the entire human population. As a part of preventive measures, at the end of March 2020 the UAE promulgated various lockdown measures to reduce the risk of the pandemic, which have a major impact on its local air quality levels. This research investigates the effect of the lockdown measures on the levels of the air pollutants like NO2 and PM2.5in Abu Dhabi Emirate using air quality stations data for the months of March and April 2020. Overall, NO2 levels have fallen dramatically by a range of 19% to 60% across all land use areas within the Emirate. Conversely, PM2.5 levels varied during the lockdown in April 2020, with increases ranging from 31% to 65% in rural and suburban industrial areas and decreases ranging from 2% to 33% in urban and suburban population areas. It can be observed that the lockdown measures had a huge impact on the NO2 levels due to reduced transportation and human activities while PM2.5 levels displayed great variability. The statistical analysis shows a significant moderate positive relationship (rs 0.476) at 0.05 level between NO2 and traffic volume crossing Musaffah Bridge. © 2021 Geo Publishing, Toronto Canada.

Assessment of Atmospheric PM2.5 and PCDD/Fs Collected by Different High-volume Ambient Air Sampling Systems

To evaluate the difference in hazardous air pollutants in PM2.5 between reference method (National Institute of Environmental Analysis;NIEAA205) and high-volume air sampler (European standard:EN14907 and Japan method), we set up a sampling station on the campus of National Yang-Ming Chiao Tung University, northern Taiwan, during 2014-2015. Both vapor and solid phases of dioxins were collected using high-volume samplers, according to EN14907 and Japan method. The flow rate was set at 500 L min(-1) and 1000 L min(-1), respectively. To compare the difference with the high-volume air sampler, we simultaneously used the reference air sampler based on Taiwan NIEA A205.11C, at the flow rate of 16.7 L min(-1) (BGI PQ200-FRM). The mass concentrations of PM2.5 measured with NIEA A205, EN14907, and Japan method were 20.2 +/- 8.79, 25.4 +/- 10.5 and 28.6 +/- 13.9 mu g m(-3), respectively. The difference of the mass concentration of PM2.5 obtained from two different methods was lower than 3.9%. Moreover, the concentrations of PCDD/F between solid and vapor phases were 56.9-1,090 and 38.6-67.1 fg m(-3) via EN14907 and 51.1-1,150 and 18.4-81.8 fg m(-3) via Japan method, respectively. Obviously, there is no significant difference between these two samplers. Compared to the method of NIEA, high volume air sampling method not only provided equivalently good quality data but offer a higher sample quantity for analyzing the trace level chemical component of hazardous air pollutants and the toxicity in different areas.

The effect of COVID-19 lockdown and meteorological parameters on air pollutants in Samsun, Turkey

In this study, to determine the effect of the lockdown applied in Samsun, Turkey, between 1 March to 31 May due to the COVID-19 pandemic, the concentration of air pollutants parameters (PM10, SO2, NO2 and O-3) were measured at the same time interval of before lockdown and during the lockdown were compared. In addition, the relationship between the concentration of air pollutants and meteorological parameters such as wind speed, temperature, relative humidity, dew point and pressure was analysed statistically. The lockdown caused the most significant reduction in the concentration of NO2, followed by SO2, O-3 and PM10. Unlike SO2 and NO2, PM10 was less affected by lockdown since it also has natural sources. Between the meteorological parameters interested, wind speed and temperature showed a strong correlation with the air pollutants due to their transportation and conversion effects, while relative humidity, dew point and pressure showed a very weak correlation.

Pharmaceuticals and Personal Care Products across Different Water Bodies in Taihu Lake Basin, China: Occurrence, Source, and Flux.

Although pharmaceuticals and personal care products (PPCPs) have attracted great attentions, their occurrence characteristics across different water bodies at a basin scale remain poorly understood. To grasp a more comprehensive understanding of PPCP pollution from the perspective of the whole basin, the occurrence, spatial and seasonal variation, source, and flux of thirteen PPCPs across the different environmental compartments of the northern Taihu Lake Basin (TLB) were studied. The results showed that the non-therapeutic pharmaceuticals caffeine (CFI) and n, n-diethyl-m-toluamide (DEET) were the main components across the different environmental compartments. The total concentrations of detected PPCPs ranged from 0.2 to 2437.9 ng/L. Higher concentrations of PPCPs were observed in spring and autumn, which were mainly attributed to seasonal differences in PPCP consumption. Generally, pollution level was higher in industry and agriculture area and in the inner bay and southwest of Taihu Lake. Source apportionment indicated that untreated water was the main source of PPCPs in river waters of the northern TLB. Flux estimation showed that the mean annual flux of PPCPs from northern TLB to Taihu Lake in 2021 was 1.6 t/a, which was higher in comparison with other areas. Overall, the resulting data will be useful to enrich the research of PPCPs in freshwater for environmental investigations.

Measurement of Black Carbon in Delhi: Evidences of Regional Transport, Meteorology and Local Sources for Pollution Episodes

Measurement of particulate matter (PM) constituent such as black carbon (BC) over urban sites is critically important owing to its adverse health and climate impacts. However, the impacts associated with BC are poorly understood primarily because of the scarcity and uncertainties of measurements of BC. Here, we present BC measurement at an urban site of Delhi using a characterized continuous soot monitoring system (COSMOS) for a year-long period, i.e., from September, 2019 to August, 2020. This measurement period covers events, i.e., period of crop residue burnings from nearby states, festive events, e.g., Diwali and New Year, and first COVID-19 lockdown period. Effects of these events combining with local emissions and meteorological conditions on BC mass concentration (MBC) are investigated to find the possible cause of severe pollution levels in Delhi. Mean MBC for the complete observation period was found to be 5.02 ?? 4.40 ??g m???3. MBC showed significant seasonal as well diurnal variations. Winter season (December to February) is observed to be the most polluted season owing to increased local emissions and non-favorable meteorological conditions. Regional emission from crop burning in nearby states during October and November is the main contributing factor for increased pollution in this postmonsoon season. Furthermore, analysis reveals that cracker burning during festivals can also be considered as contributing factor to high MBC for a short period in post-monsoon and winter seasons. Significant decrease in MBC due to COVID-19 lockdown is also observed. MBC in summer and monsoon are lower as compared to other seasons but are still higher than mean MBC levels in several other urban cities of different countries. Also, the BC data obtained from nearby sites surface black carbon (SBC) are compared against the MBC to evaluate coherency among the different datasets, and discussed in detail.

Local and transboundary impacts of PM2.5 sources identified in Seoul during the early stage of the COVID-19 outbreak.

Countries in Northeast Asia have been regulating PM2.5 sources and studying their local and transboundary origins since PM2.5 causes severe impacts on public health and economic losses. However, the separation of local and transboundary impacts is not fully realized because it is impossible to change air pollutant emissions from multiple countries experimentally. Exceptionally, the early stage of the COVID-19 outbreak (January-March 2020) provided a cross-country experiment to separate each impact of PM2.5 sources identified in Seoul, a downwind area of China. We evaluated the contributions of PM2.5 sources compared to 2019 using dispersion normalized positive matrix factorization (DN-PMF) during three meteorological episodes. Episodes 1 and 2 revealed transboundary impacts and were related to reduced anthropogenic emissions and accumulated primary pollutants in Northeast China. Anthropogenic emissions, except for the residential sector, decreased, but primary air pollutants accumulated by residential coal combustion enhanced secondary aerosol formation. Thus, the contributions of sulfate and secondary nitrate increased in Seoul during episode 1 but then decreased maximally with other primary sources (biomass burning, district heating and incineration, industrial sources, and oil combustion) during episode 2 under meteorological conditions favorable to long-range transport. Local impact was demonstrated by atmospheric stagnation during episode 3. Meteorological condition unfavorable to local dispersion elevated the contributions of mobile and coal combustion and further contributed to PM2.5 high concentration events (HCE). Our study separates the local and transboundary impacts and highlights that cooperations in Northeast Asia on secondary aerosol formation and management of local sources are necessary.