ABSTRACT
The synergistic response of urban atmospheric aerosols and ozone (O3) to reduction of anthropogenic emissions is complicated and still needs further study. Thus, the changes in physical and chemical properties of urban atmospheric aerosols and O3 during the Coronavirus Disease 2019 (COVID-19) lockdown were investigated at three urban sites and one rural site in Lanzhou with semi-arid climate. Fine particulate matter (PM2.5) decreased at four sites by â¼ 20% while O3 increased by >100% at two urban sites during the COVID-19 lockdown. Both primary emissions and secondary formation of PM2.5 decreased during the lockdown. Significant increase in both sulfur and nitrogen oxidation ratios was found in the afternoon, which accounted for 48.7% of the total sulfate and 40.4% of the total nitrate, respectively. The positive matrix factorization source apportionment revealed increased contribution of secondary formation and decreased contribution of vehicle emissions. Aerosol scattering and absorption decreased by 33.6% and 45.3%, resulting in an increase in visibility by 30% and single scattering albedo (SSA) at 520 nm slightly increased by 0.02. The enhanced O3 production was explained by increased volatile organic compounds to nitrogen oxides ratio, decreased aerosol, as well as increased SSA. The primary emissions of secondary aerosol precursors significantly decreased while Ox (i.e., NO2 and O3) exhibited little change. Consequently, Ox to CO ratio, PM2.5 to elemental carbon (EC) ratio, secondary inorganic aerosols to EC ratio, and secondary organic carbon to EC ratio increased, confirming enhanced secondary aerosol production efficiency during the lockdown. Positive feedback among O3 concentration, secondary aerosol formation, and SSA was revealed to further promote O3 production and secondary aerosol formation. These results provide scientific guidance for collaborative management of O3 and particulate matter pollution for cities with semi-arid climate.
ABSTRACT
The present study's main objective was to analyze and determine the impact of digital marketing on the management of relationships with university students in times of Covid-19. The study was conducted from a quantitative approach, with a non-experimental transactional correlational transactional research design. A questionnaire was applied to 400 students aged 18 to 37 years belonging to the Continental University of the city of Huancayo in Peru. The analysis of the results was developed through a data structure and tabulation model with the SmartPLS3 program and it was obtained that Content Marketing has a significant influence on the operational management of customer relationships (p<0.05), as well as on the analytical and collaborative management of customer relationships. As for Social Media Marketing, it was identified that it has a significant influence on operational customer relationship management (p<0.05), as well as on analytical and collaborative customer relationship management, due to the fact that the digital media used by Continental University are attractive to parents and families. It is concluded that Digital Marketing has a great impact on the management of relationships with students of the Continental University in the city of Huancayo in Peru. © 2022 by the authors;licensee Growing Science, Canada.