TITLE:
On the Limits to Manage Air-Quality in Glacier Bay
AUTHORS:
Nicole Mölders, Scott Gende
KEYWORDS:
Glacier Bay National Park, Emission-Source Contribution, Cruise-Ship Emissions, Air-Quality Management, Interaction of Pollutants
JOURNAL NAME:
Journal of Environmental Protection,
Vol.7 No.12,
November
29,
2016
ABSTRACT: 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.