Author(s)

Nicole Mölders^1*, Scott Gende²

¹Department of Atmospheric Sciences, Geophysical Institute, College of Natural Science, University of Alaska Fairbanks, Fairbanks, AK, USA.
²National Park Service, Juneau, AK, USA.

In Glacier Bay National Park, about 95% of the visitors come on board of cruise ships. The National Park Service has the mandate to manage park resources like air quality and visibility, while ensuring visitation. To understand the impact of cruise-ship emissions on the overall concentrations in Glacier Bay, emission-source contribution ratios (ESCR) and the interaction of pollutant from local and/or distant sources were determined using results from four WRF/Chem simulations of the 2008 tourist season (May 15 to September 15). These simulations only differed by the emissions considered: Biogenic emissions only (CLN), biogenic plus activity-based cruise-ship emissions (REF), biogenic plus all anthropogenic emissions except cruise-ship emissions (RETRO), and all aforementioned emissions (ALL). In general, ESCRs differed among pollutants. Interaction between pollutants from cruise-ship emissions and species from other sources including those advected into the bay decreased towards the top of the atmospheric boundary layer. Pollutants from different sources interacted strongest (lowest) in the west arm of the fjord where ships berthed for glacier viewing (in areas of the bay without cruise-ship travel). Pollutant interaction both enhanced/reduced NO₂ concentrations by 10% (4 - 8 ppt absolute). Except for ozone, cruise-ship emissions on average governed air quality in the bay. On days with cruise-ship visits, they contributed between 60% and 80% of the bay-wide daily mean SO₂ and NO₂ concentrations below 1 km height. On days without visits, cruise-ship contributions still reached 40% due to previous visits. Highest cruise-ship ESCRs occurred during stagnant weather conditions. Despite the fact that all coarse particulate matter was due to anthropogenic sources, worst visibility conditions were due to meteorology. The results suggest limits as well as windows for managing air quality and visibility in Glacier Bay.

Glacier Bay National Park, Emission-Source Contribution, Cruise-Ship Emissions, Air-Quality Management, Interaction of Pollutants

Mölders, N. and Gende, S. (2016) On the Limits to Manage Air-Quality in Glacier Bay. Journal of Environmental Protection, 7, 1923-1955. doi: 10.4236/jep.2016.712151.