Unfavorable Meteorological Conditions Research Articles

Numerical Simulation of the Effect of Construction Dust Emission on Air Quality in Jinan, a Central City in the North China Plain

<p>Numerical simulation was conducted to assess the impact of dust emission on typical environmental sites in Jinan City. The CALPUFF model was applied to five simulation scenarios. The results showed that dust emission had a significant impact on air quality in Jinan. The impact of dust emission on the average concentration of PM10 at 15 monitoring sites was 19.8 μg/m3, accounting for 14.9% of the annual total. The impact of dust emission on the average concentration of PM2.5 was 5.2 μg/m3, accounting for 8.1% of the annual total. Adoption of yellow warning measures in the emission reduction scenarios had insignificant environmental effects due to unfavorable meteorological conditions. Compared with the baseline scenario, the average concentrations of PM10 and PM2.5 decreased by 13.6% and 1.9%, respectively. After adoption of orange and red warning measures, the impact of site dust emission on air quality at the monitoring site was reduced significantly. Significant environmental effects were achieved after all construction sites within a 2-km radius of the monitoring site were closed. Compared with the baseline scenario, the average concentrations of PM10 and PM2.5 were reduced by 45.5% and 42.3%, respectively. The results showed that under adverse meteorological conditions, higher-level warning measures should be undertaken to reduce the impact of site emissions on environmental quality. Considering the economic and social effects of emission reduction, temporary construction stoppage within 2 km of the monitoring site is a feasible plan that is in accordance with the goals of comprehensive environmental management.</p>

Disperzija hemijskih sredstava u policijskoj praksi suzbijanja građanskih nereda

This study seeks to determine the spatial and temporal concentration of chemical agents (specifically - orthochlorobenzylidenemalononitrile - corson & stought (CS)) used by law enforcement in controlling civil disorders, depending on meteorological conditions and the time of the day. This study was conducted using the Gaussian air pollutant dispersion model. Based on findings of this study, conclusions pertaining to distance (in meters) and duration (in seconds) of the use of chemical agents under favorable, average, and unfavorable meteorological conditions, as well as conditions determined by the time of the day, both in urban and rural areas were drawn. Based on these conclusions, recommendations were made for the management and tactics of the engagement of police units in situations where the use of chemical agents occurs. Additionally, recommendations for future research in this area have been identified.

Effects of organic and microbiological fertilizers on morphological and productive characteristics of triticale in the organic farming system

The aim of the study was to examine the impact of microbiological and organic fertilizers on morphological and productive characteristics of triticale during a three-year period (2009/10-2011/12). A two-factorial field experiment was arranged using a randomized block design with four replications. The object of the study was the triticale winter cultivar Odisej, and the following treatments were applied: a control variant without fertilization, microbiological fertilizer ?Slavol? (Agrounik Serbia) 5.0 l ha-1, organic fertilizer ?Biohumus Royal offert? (Altamed RS) 3.0 t ha-1 + microbiological fertilizer ?Slavol? (Agrounik Serbia) 5.0 l ha-1. The results showed that the expression of the characteristics was significantly affected by the environment. The lowest values were obtained in the first year when the most unfavourable meteorological conditions were observed. The application of microbiological fertilizer had no impact on the stem length and grain weight per spike, but it significantly increased the number of fertile spikelets (3.7%), spike length (7.7%) and grain yield (18.6%). The combined application of fertilizers provided better results for all the examined characteristics, while in comparison with the control, the differences ranged from 4.3% for the number of fertile spikelets to 46.5% for grain yield. The strongest correlation was determined between the spike length and the number of fertile spikelets (r = 0.939**). The obtained results lead to the conclusion that under variable environmental conditions, the application of fertilizers has a significant impact on morphological and productive characteristics of triticale, and consequently on the stability of this crop production in the organic farming system.

Air pollution in three megacities of India during the Diwali festival amidst COVID-19 pandemic

• Seven air pollutant levels were analyzed during Diwali in three megacities of India. • Scenario of Diwali 2019 (non-pandemic) and Diwali 2020 (amidst pandemic) was compared. • Pre-Diwali to Diwali changes in air pollutant levels were highest in Delhi. • Mumbai and Kolkata exhibited minimal increase in pollutant levels during Diwali 2020. • Unfavorable meteorological conditions worsened the air pollution scenario in Delhi. The present study characterized the difference in air pollution levels between Diwali celebrations amidst the Covid-19 pandemic (14 November 2020) and the previous year (27 October 2019). The concentration of seven principal air pollutants, namely PM 2.5 , PM 10 , NO 2 , NH 3 , SO 2 , CO, and O 3 , was substantially higher in 2020 Diwali than in 2019 Diwali. PM 2.5 , PM 10 , and CO were always above the permissible limits in all three megacities, with the highest concentrations observed in Delhi. This observation indicates that amidst the pandemic, people burnt more firecrackers than the preceding year. However, the pre-Diwali to Diwali changes in pollutant concentrations suggested that Mumbai and Kolkata had lower pollution levels due to the fireworks. The firework-induced air pollutant load in Delhi was enhanced by a higher margin in the pandemic year. The difference in meteorological conditions between the two consecutive year's Diwali might have led to the enhanced pollutant load in 2020, especially in Delhi. Delhi showed a tendency to retain the pollutants in the ground-level atmosphere for almost one week after the event. Thus, this study implies the need for stringent law enforcement to ameliorate the pollution levels due to such celebrations.

ВРЕДОНОСНОСТЬ ГРИБНОГО ЗАБОЛЕВАНИЯ ФОМОПСИС НА ВИНОГРАДНИКАХ РОСТОВСКОЙ ОБЛАСТИ

The results of studies of the influence of me-teorological conditions on the intensity of the development of Phomopsis (Phomopsis viti-cola) on plants of different grapevine varie-ties during 2019‒2021 are presented. It was established that the absence of extreme sub-zero temperatures during dormant period con-tributed to the preservation of the infectious onset of the disease. In most phases of the growing season 2019‒2021 unfavorable me-teorological conditions for the development of pycnidia and sporulation of the fungus Phomopsis viticola were observed ‒ high temperature and low air humidity. Despite this, the activity of the pathogen increased during the vegetation season and reached its maximum values in the phase of technical ma-turity of berries. Amoung the studied varie-ties, the most susceptible to Phomopsis were: Tsvetochny, Cabernet Sauvignon, Vostorg, Baklanovsky with a lesion intensity of more than 2 points. The most resistant varieties, with the intensity of damage up to 1 point and without signs of damage, were the fol-lowing varieties: Denisovsky, Pervenets Magarach, Krasnostop Zolotovsky, Sibirkovy.

Численное моделирование качества воздуха над городом Томском при слабом ветре

A mathematical model and a numerical method for calculating meteorological parameters and quantities characterizing the quality of atmospheric air in the city, obtained using mesoscale models of numerical weather forecasting and impurity transport, are presented. The results of numerical calculations were compared with the data of observations performed with the instruments of the Central Collective Use Center "Atmosfera" of the Institute of Atmospheric Optics of the Siberian Branch of the Russian Academy of Sciences. The conducted studies have shown that the most unfavorable meteorological conditions leading to the accumulation of impurities near the earth's surface are observed in the morning and evening hours - this is a weak wind of variable direction and stable or neutral stratification of the surface air layer.

The Impact of COVID-19 Lockdowns on Satellite-Observed Aerosol Optical Thickness over the Surrounding Coastal Oceanic Areas of Megacities in the Coastal Zone

Nearly 40 years of aerosol optical thickness (AOT) climate data record (CDR) derived from NOAA operational satellite Advanced Very High Resolution Radiometer (AVHRR) observation over the global oceans is used to study the AOT changes due to the COVID-19 lockdown over the surrounding coastal oceanic areas of 18 megacities in the coast zone (MCCZ). The AOT difference between the annual mean AOT values of 2020 with COVID-19 lockdown and 2019 without the lockdown along with the 2020 AOT annual anomaly are used to effectively identify the AOT changes that are a result of the lockdown. We found that for most of the 18 MCCZ, the COVID-19 lockdowns implemented to contain the spread of the coronavirus resulted in a decrease between 1% and 30% in AOT due to reduced anthropogenic emissions associated with the lockdowns. However, the AOT long-term trend and other aerosol interannual variations due to favorable or unfavorable meteorological conditions may mask AOT changes due to the lockdown effect in some MCCZ. Different seasonal variations of aerosol amount in 2020 relative to 2019 due to other natural aerosol emission sources not influenced by the lockdown, such as dust storms and natural biomass burning and smoke, may also conceal a limited reduction in the annual mean AOT due to the lockdown in MCCZ with relatively loose lockdown. This study indicates that the use of long-term satellite observation is helpful for studying and monitoring the aerosol changes due to the emission reduction associated with the COVID-19 lockdown in the surrounding coastal oceanic areas of MCCZ, which will benefit the future development of the mitigation strategy for air pollution and emissions in megacities.

Аномальное аэрозольное загрязнение воздуха в Москве вблизи локального антропогенного источника в июле 2021 года

The paper analyzes the composition of surface aerosol close to the local intense anthropogenic source of pollution associated with the active phase of demolition of multistorey buildings in the center of Moscow. An abnormal increase in the daytime PM10 aerosol particle concentration to 5 MPC for daily values and to 14 MPC for maximum single values was reinforced by unfavorable meteorological conditions in the middle of July 2021. Preliminary estimation of the power of the dust aerosol source and its effect on the aerosol air pollution in nearby areas of the city is performed. The extreme and background values of the aerosol mass concentration, its elemental composition and particle size distribution during this period are determined. It is necessary to take into account such point pollutant sources in estimating and forecasting environmental conditions in a densely populated city. Keywords: surface aerosol, local anthropogenic source, Moscow, aerosol mass concentration, elemental composition, meteorological conditions

Аномальное аэрозольное загрязнение воздуха в Москве вблизи локального антропогенного источника в июле 2021 года

The paper analyzes the composition of surface aerosol close to the local intense anthropogenic source of pollution associated with the active phase of demolition of multistorey buildings in the center of Moscow. An abnormal increase in the daytime PM10 aerosol particle concentration to 5 MPC for daily values and to 14 MPC for maximum single values was reinforced by unfavorable meteorological conditions in the middle of July 2021. Preliminary estimation of the power of the dust aerosol source and its effect on the aerosol air pollution in nearby areas of the city is performed. The extreme and background values of the aerosol mass concentration, its elemental composition and particle size distribution during this period are determined. It is necessary to take into account such point pollutant sources in estimating and forecasting environmental conditions in a densely populated city. Keywords: surface aerosol, local anthropogenic source, Moscow, aerosol mass concentration, elemental composition, meteorological conditions

Farming intensity indirectly reduces crop yield through negative effects on agrobiodiversity and key ecological functions

Farming intensity and landscape heterogeneity influence agrobiodiversity and associated ecological functions. The relative contributions of these agroecosystem components to agricultural production remain unclear because of inter-relations and weather-dependant variations. Using a structural equation modelling approach, we estimated direct and indirect contributions of farming intensity (soil management, pesticide use and fertilisation) and landscape heterogeneity (of semi-natural covers and crop mosaic) to cereal crop production, in 54 fields (mostly wheat), in two years (24 and 30 fields). Indirect effects were evaluated through agrobiodiversity (carabid and plant communities) and ecological functions (pollination and pest control). In 2016, farming intensity had the largest direct positive effect on cereal crop yield, followed by agrobiodiversity (74% of the farming intensity impact) and ecological functions. However, the direct benefits of farming intensity were halved due to negative indirect effects, as farming intensity negatively affected within-field biodiversity and ecological functions. Overall, agrobiodiversity and farming intensity had equal net contributions to cereal crop yields, while heterogeneity of the crop mosaic enhanced biodiversity. In 2017, neither higher farming intensity nor agrobiodiversity and ecological functions could lift cereal production, which suffered from unfavourable meteorological conditions. Semi-natural habitats supported agrobiodiversity. Our study suggests that a reduction of farming intensity combined with higher heterogeneity of crop mosaic can enhance the benefits of ecological functions towards crop production. Semi-natural covers seem to play an essential role in the face of climatic events, by supporting agrobiodiversity and the potential resilience of the agroecosystem functioning.

The Occurrence of Heavy Air Pollution during the COVID-19 Outbreak in Beijing, China: Roles of Emission Reduction, Meteorological Conditions, and Regional Transport

To prevent the spread of coronavirus disease (COVID-19) and mitigate the epidemic risk, strict lockdown measures were implemented in Beijing during the quarantine period, significantly reducing human activities. However, severe air pollution episodes occurred frequently in Beijing. To explore the occurrence of severe air pollution during the quarantine period, the impacts of emission reductions, meteorological conditions, and regional transport on heavy air pollution were individually evaluated using the Community Multiscale Air Quality (CMAQ) model. Observations showed that the more unfavorable meteorological conditions which occurred during the pandemic as compared to the corresponding 2019 levels, including higher temperature, relative humidity, and frequency of strong southerly winds, and lower HPBL, led to an increase in PM2.5 concentrations. The model results also showed that the meteorological conditions in February 2020 favored PM2.5 formation. The PM2.5 concentrations were mainly dominated by regional transport, which became more significant in the quarantine period than in 2019, suggesting the importance of joint control on regional sources for reducing heavy air pollution. This study highlights that, although the emissions in Beijing and surrounding regions were largely reduced during the quarantine period, severe air pollution in Beijing did not reduce due to the unfavorable meteorological conditions.

Influence of rootstock on the quality of sweet cherry fruits in the conditions of the Lower Volga region

Sweet cherry is a thermophilic and whimsical crop that reacts painfully to unfavorable meteorological conditions, such as frost, drought or high humidity in the air and soil. At the same time, this crop requires a uniform supply of heat and moisture during the growing season. In the climatic conditions of the Volgograd region, stressful situations often arise that can partially or completely reduce the yield of fruit crops, especially those introduced to our region from other regions. To reduce the risk of losing the yield of fruit plantations, including sweet cherry, it is necessary to pay special attention to the choice of the variety, as well as the rootstock on which this variety is grafted. The publication presents the results of studying the influence of rootstocks on the qualitative and quantitative indicators of sweet cherry fruits, such as taste, weight, uniformity, color, and productivity. According to the results of the study in the field (in the garden), varietal-rootstock combinations were identified that have one-dimensional, crack-resistant, large fruits, while maintaining high and stable productivity. According to the results of research, it was found that the rootstock affects not only the strength of growth and the shape of the crown, but also the quality of the fruit. The most dependent of the studied varieties on the type of rootstock is Euphoria, the lowest weight of berries was observed on the rootstock VSL-1. At the same time, this rootstock has a higher percentage of resistance to cracking of the fruit. Based on the conducted research, it can be concluded that with the help of rootstock, it becomes possible to influence the quality indicators of fruits.

Turtledove Streptopelia turtur in the North Western Black Sea region

The results of field surveys, regarding seasonal migration and nesting numbers, of the turtle dove S. turtur in the North-Western Black Sea region show that in 2021 they were close to the average long-term levels. However, the change of the migration corridor and the departure of the turtle dove, before the beginning of the hunting season (August 7), caused a false picture of the small number of species. This situation is similar to 2020. The main reason was unfavorable meteorological conditions of the spring-summer period. Due to the delay in ripening sunflower, which is a key high-energy feed for migrating turtledoves. Therefore, the lack of ripe sunflower 2020–2021 caused the early flight of birds in order to make up for the forage potential in the fields in the Balkans and Asia Minor. The peak of summer-autumn migration fell on August 9–13, which is 12–12 days earlier than the average long-term period. This situation indicates a sufficient ecological plasticity of the species, expressed in the ability of local and migratory turtledoves to vary the timing of migration and migration corridors, thus responding to changes in environmental conditions. Also, this situation indicates a sharp decrease in the volume of hunting turtle dove — in the hunting season of 2021. Only 5.7 thousand individuals were harvested, which is much less than in 1985–1991. Summarizing the above, the study is evidence that the reduction of migratory birds from 1.5–1.7 million recorded in 1996–2004 to the existing to date 0.9 million. The prospects for further research are in more advanced and in-depth studies of local and flying necks using special accounting methods based on the mass labeling of birds.

Study on the causes of heavy pollution in Shenyang based on the contribution of natural conditions, physical processes, and anthropogenic emissions

This study investigated the impacts of meteorological and geographical conditions, the roles of individual physical processes, and the contribution of emissions during severe PM2.5 (fine particulate matter) pollution events in Shenyang, one of the largest industrial cities in China. Simulations of six severe PM2.5 pollution events that occurred in 2015 and 2016 revealed that unfavorable meteorological conditions, including high relative humidity, low depth of the planetary boundary layer, low wind speed, changes in wind direction, and unfavorable geographical conditions underly severe PM2.5 pollution events in Shenyang. Regarding individual physical processes, emission and aerosol processes increased the concentration of PM2.5, while horizontal advection, vertical advection, and vertical diffusion processes dominated the decrease in PM2.5. Analysis of source apportionment found that residential (37%) and transportation (30%) dominated PM2.5 pollution as categories, and Shenbei New District contributed 75% of regional emissions. The main causes of the severe PM2.5 pollution events in Shenyang are complex, and include local emissions associated with transportation emissions from Shenbei New District; local emissions associated with agricultural emissions and low northwesterly winds; long-range transport with a southeasterly wind; and middle-range transport with a northerly wind.

Aerosol transport pathways and source attribution in China during the COVID-19 outbreak

Abstract. Due to the coronavirus disease 2019 (COVID-19) pandemic, human activities and industrial productions were strictly restricted during January–March 2020 in China. Despite the fact that anthropogenic aerosol emissions largely decreased, haze events still occurred. Characterization of aerosol transport pathways and attribution of aerosol sources from specific regions are beneficial to air quality and pandemic control strategies. This study establishes source–receptor relationships in various regions covering all of China during the COVID-19 outbreak based on the Community Atmosphere Model version 5 with Explicit Aerosol Source Tagging (CAM5-EAST). Our analysis shows that PM2.5 burden over the North China Plain between 30 January and 19 February is mostly contributed by local emissions (40 %–66 %). For other regions in China, PM2.5 burden is largely contributed from nonlocal sources. During the most polluted days of the COVID-19 outbreak, local emissions within the North China Plain and eastern China contributed 66 % and 87 % to the increase in surface PM2.5 concentrations, respectively. This is associated with the anomalous mid-tropospheric high pressure at the location of the climatological East Asia trough and the consequently weakened winds in the lower troposphere, leading to the local aerosol accumulation. The emissions outside China, especially those from South Asia and Southeast Asia, contribute over 50 % to the increase in PM2.5 concentration in southwestern China through transboundary transport during the most polluted day. As the reduction in emissions in the near future is desirable, aerosols from long-range transport and unfavorable meteorological conditions are increasingly important to regional air quality and need to be taken into account in clean-air plans.

DETERMINATION OF THE CONDITIONS FOR APPLYING THE TECHNOLOGY OF TARGET GRAVITY BRAKING OF UNCOUPLED CARS

Improving the efficiency of the process of train uncoupling remains one of the mosturgent problems in railway transport. The priority areas for solving this problem today include thedevelopment and implementation of integrated automation systems for hump technologies, the use ofartificial intelligence in decision support systems and procedures for calculating the controlparameters of car retarders. These systems provide high accuracy in designing and implementingcontrol actions, taking into account indeterminacy and multiple random parameters.However, a number of factors that are quite difficult to take into account, predict, or formalize.Such factors include the technical condition of rail car retarders, their random brakingcharacteristics, constant changes in wind speed and direction, the condition of wheel pairs, theresponse rate of hump operators, and others. These factors can have significant impact on the qualityof the marshalling process, even on automated marshalling humps.To increase the efficiency of the train uncoupling technology, researchers have developed anumber of scientific approaches and technical solutions: approaches to control using the equipmentfor controlling the speed of rolling uncoupled cars in automated mode have been formed, new designsof car retarders have been developed and the existing ones were improved, optimizing methods forbraking modes of uncoupled cars, the longitudinal profile of marshalling humps and the design ofhump necks have been proposed.
 The introduction of target gravity braking technology for uncouples cars is one of the ways toimprove the efficiency of the marshalling process. This technology can be implemented provided thata special profile design of the marshalling device is used.To determine the conditions for applying the target gravity braking technology for uncoupledcars, simulation modeling of rolling of model cars in favorable and unfavorable meteorologicalconditions was carried out.The results of simulation modeling showed that the proposed technology can be definitely used,if the number of tracks in the marshalling yard is up to 32 and estimated wind speeds up to 6 m/s,when it provides an uncoupling rate of up to 1,8 m/s. If the marshalling yard has a larger number oftracks and/or in case of powerful winds, the technology can be applied if the uncoupling rate isreduced. In this case, the feasibility of using the technology should be verified with technical andeconomic calculations.

Modelling of the Chemical Halo of Dust Pollution Migration in Loparite Ore Tailings Storage Facilities

The article presents a study of the environmental impact of dusting tailing dumps of rare-metal ore dressing in the Murmansk region of Russia. The purpose of the study was to establish patterns in the atmochemical halo migration of the dust pollution of loparite ore dressing tailings. The geotechnical characteristics and material composition of the tailings material have been investigated. Potentially dusty areas identified. Models of dispersion of inorganic dust under different meteorological scenarios are constructed: at low wind load, normal and unfavorable meteorological conditions. The modeling of the spread of pollutants in the area exposed to dust at the storage site was carried out in the program for modeling atmospheric pollution Ecolog-4.60. Calculation of the dispersion of inorganic dust containing 20–70% SiO2 showed that the atmochemical halo of tailings dust pollution spreads over tens of kilometers, and already at a wind speed of about 8 m/s, the concentration of suspended solids at the border of the enterprise sanitary protection zone exceeds the maximum one-time maximum permissible concentration is 3–3.3 times, and under unfavorable meteorological conditions—Dusting reaches the boundaries of the residential area (inhabited locality Revda), located in the north-west of the enterprise, and exceeds the MPCm.o. 1.5 times.

Impacts of COVID-19 on air quality in mid-eastern China: An insight into meteorology and emissions

The coronavirus disease (COVID-19) spread rapidly worldwide in the first half of 2020. Stringent national lockdown policies imposed by China to prevent the spread of the virus reduced anthropogenic emissions and improved air quality. A weather research and forecasting model coupled with chemistry was applied to evaluate the impact of meteorology and emissions on air quality during the COVID-19 outbreak (from January 23 to February 29, 2020) in mid-eastern China. The results show that air pollution episodes still occurred on polluted days and accounted for 31.6%–60.5% of the total number of outbreak days in mid-eastern China from January 23 to February 29, 2020. However, anthropogenic emissions decreased significantly, indicating that anthropogenic emission reduction cannot completely offset the impact of unfavorable meteorological conditions on air quality. Favorable meteorological conditions in 2019 improved the overall air quality for a COVID-19 outbreak in 2019 instead of 2020. PM2.5 concentrations decreased by 4.2%–29.2% in Beijing, Tianjin, Shijiazhuang, and Taiyuan, and increased by 6.1%–11.5% in Jinan and Zhengzhou. PM2.5 concentrations increased by 10.9%–20.5% without the COVID-19 outbreak of 2020 in mid-eastern China, and the frequency of polluted days increased by 5.3%–18.4%. Source apportionment of PM2.5 during the COVID-19 outbreak showed that industry and residential emissions were the dominant PM2.5 contributors (32.7%–49.6% and 26.0%–44.5%, respectively) followed by agriculture (18.7%–24.0%), transportation (7.7%–15.5%), and power (4.1%–5.9%). In Beijing, industrial and residential contributions to PM2.5 concentrations were lower (32.7%) and higher (44.5%), respectively, than in other cities (38.7%–49.6% for industry and 26.0%–36.2% for residential). Therefore, enhancing regional cooperation and implementing a united air pollution control are effective emission mitigation measures for future air quality improvement, especially the development of new technologies for industrial and cooking fumes.

Estimation of ship emission rates at a major shipping lane by long-path DOAS measurements

Abstract. Ships are an important source of SO2 and NOx, which are key parameters of air quality. Monitoring of ship emissions is usually carried out using in situ instruments on land, which depend on favourable wind conditions to transport the emitted substances to the measurement site. Remote sensing techniques such as long-path differential optical absorption spectroscopy (LP-DOAS) measurements can supplement those measurements, especially in unfavourable meteorological conditions. In this study 1 year of LP-DOAS measurements made across the river Elbe close to Hamburg (Germany) have been evaluated. Peaks (i.e. elevated concentrations) in the NO2 and SO2 time series were assigned to passing ships, and a method to derive emission rates of SO2, NO2 and NOx from those measurements using a Gaussian plume model is presented. A total of 7402 individual ship passages have been monitored, and their respective NOx, SO2 and NO2 emission rates have been derived. The emission rates, coupled with the knowledge of the ship type, ship size and ship speed, have been analysed. Emission rates are compared to emission factors from previous studies and show good agreement. In contrast to emission factors (in grams per kilogram fuel), the derived emission rates (in grams per second) do not need further knowledge about the fuel consumption of the ship. To our knowledge this is the first time emission rates of air pollutants from individual ships have been derived from LP-DOAS measurements.

Characteristics and Control Strategies on Summertime Peak Ozone Concentration in Shanghai

With the continuous development of air pollution control measures, the concentration of PM2.5 in Shanghai has shown a conspicuous downward trend in recent years. However, frequent O3 pollution events have highlighted the urgent need to explore the occurrence patterns of O3 pollution and develop scientific strategies for reducing O3 peaks. This study examines data from July 2017, when the cumulative number of O3 pollution days in 17 cities in the Yangtze River Delta was 165 days, of which Shanghai was the most serious, with an exceedance rate of 64.5%. During this period, the average concentration of NO2 in Shanghai was 27.1 μg·m-3 and volatile organic copunds (VOCs) mixing ratio was 22.5×10-9. By analyzing ozone precursor concentrations and meteorological factors, we determined that these events mainly resulted from a combination of unfavorable meteorological conditions such as high temperature, low humidity, low wind speed, and high precursor emissions. WRF-CMAQ scenario simulations showed that a reduction in precursor emissions in Shanghai alone would have a limited controlling effect on regional O3 pollution. Thus, regional joint control is recommended when widespread pollution events occur. Our analysis shows that if VOCs in Shanghai and nine neighboring cities can be reduced by 30%, the maximum 8-h O3 concentration in Shanghai could be reduced by 7.2%. If the reduction number of these cities rises to 17, the maximum 8-h O3 concentration reduction rate in Shanghai will increase to 7.8%. It is also recommended that the VOCs:NOx reduction ratio should be strictly controlled at more than 3:1, or else the O3 concentration in some areas will increase.