Air Quality in Rocky Mountain National Park during the 2020 COVID19 Shutdown
Lillian Naimie1, Katherine Benedict2, Amy Sullivan3, Bret Schichtel4 and Jeff Collett5
The air quality in Rocky Mountain National Park (RMNP) has been monitored over recent years to examine the influence of sources in the Front Range and other regions on fine particulate matter and trace gas concentrations. Reactive nitrogen species have been examined closely due to their contributions to excess nitrogen deposition and its impacts on RMNP ecosystems. Monitoring was originally not planned for 2020 but reinstated after the start of the COVID19 pandemic to explore whether the shutdown significantly changed the composition or concentration of key aerosol and gas species. Data collection began on April 25, 2020. Measurements were made using URG denuder-filter-pack sampling to measure inorganic gas and particle composition and wet-only precipitation sampling to measure wet deposition. The URG sampling began at daily (24 hr) time resolution and switched to twice weekly on June 8. Precipitation sampling began with bucket switches three times a week and switched to a weekly basis on June 8. Concentrations of PM2.5 NH4+, NO3-, and SO42- and gaseous NH3, HNO3, and SO2 were compared to concentrations measured in 2016-2019. The period of the shutdown was analyzed directly by comparing the data from April 25 – May 31 (a period when Colorado was under the tightest pandemic activity restrictions) to the previous years. No evidence was found of significant decreases in concentrations of the measured species during the COVID shutdown.[N1] While this result is somewhat surprising, it is important to keep in mind that, given the distance of RMNP from major pollutant sources, changes in meteorology (transport patterns, precipitation occurrence) play a large role in determining the likelihood of emissions from those sources reach the park. Air quality data from the Front Range will be examined to see if stronger pollutant trends are apparent closer to major source regions The RMNP wet deposition data will also be examined to compare nitrogen deposition during the shutdown period to previous years. As upslope events with transport from the Front Range are major contributors to RMNP reactive N deposition, transport conditions from this year will also be compared to previous years.
[N1]Not certain about this section. I could also just include average values from the shutdown period with the URG and their corresponding standard deviations
1Colorado State University, Graduate Research Assistant, lnaimie@gmail.com
2Colorado State University, Atmospheric Science, katherine.benedict@colostate.edu
3Colorado State University, Atmospheric Science, amy.sullivan@colostate.edu
4National Park Services Air Resources Division, bret.schichtel@colostate.edu
5Colorado State University, Atmospheric Science, jeffrey.collett@colostate.edu