The transport of aerosols into Denali National Park and Preserve

Abstract

Denali National Park and Preserve (DNPP) is a federally protected Class I visibility area in Alaska. The Regional Haze Rule in the U.S. Clean Air Act requires the visibility in all Class I areas to be 'pristine.' According to the EPA DNPP does not have `pristine' air. Therefore, the Alaska Department of Environmental Conservation conducted a 15-month study of particulate matter smaller than 2.5 micrometers (PM2.5) from March, 2008 through June, 2009 to identify the aerosol sources in DNPP. DRUM aerosol impactors collected aerosols at four sites (DNPP Headquarters, Trapper Creek, McGrath, and Lake Minchumina) around DNPP. The aerosol data underwent a series of analyses including: a seasonal analysis of elemental composition, an analysis of potential source regions as identified by the HYbrid Single-Particle Lagrangian Integrated Trajectory ectory (HYSPLIT) model, and Chemical Mass Balance (CMB) analyses to identify specific aerosol sources. These analyses show that the predominant sources of aerosols impacting DNPP during winter and spring lie outside of Alaska and during summer and fall are from outside and local sources. Outside sources include deserts in China and industry in Russia. Because many of the aerosols impacting DNPP are produced internationally, the visibility in DNPP cannot be restored without international collaboration.