[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.

The Social Media “Magic”: Virtually Engaging Visitors during COVID-19 Temporary Closures

The purpose of this study was to explore what types of digital content cultural institutions implemented during COVID-19 temporary closures and their effects on social media engagement. Existing research identified the role of digital content and social media in cultural institutions, but only in times of normal operations. This study adds to the existing literature by exploring the types of digital content implemented, impacts on social media engagement, measures of social media engagement, and future implications in regard to COVID-19 temporary closures. This study recruited 66 cultural institutions from across the United States to take part in in-depth semi-structured phone interviews to fulfill the research goals. Museums, zoos, aquariums, performing arts organizations, heritage foundations, and historical societies were represented. A qualitative approach was adopted, and content analysis on the interview transcripts indicated that cultural institutions implemented digital content to build communities through live and serialized content, partnerships, fundraising, increased transparency, and increased accessibility during temporary closures. Using primarily Instagram and Facebook with their digital content, cultural institutions increased social media engagement during this time. Although there was no consensus on best practices in measuring social media engagement, many institutions highlighted tracking active engagement such as likes, comments, and shares. As a result of the success of the digital content, cultural institutions planned continued digital content campaigns such as videos, blogs, partnerships, and paid educational content in times of normal operations.