Investigation of the impact of ship emissions on atmospheric composition and deposition into remote, coastal landscapes of Southwest Alaska

Abstract

"Every summer season, the Gulf of Alaska experiences an influx of shipping traffic, yet ship emissions are only modestly regulated allowing for substantial amounts of pollutants to be released. These pollutants can be transformed and transported affecting atmospheric composition and deposition of contaminants in even remote landscapes. The fully coupled Weather Research and Forecasting meteorology and chemistry transport model, WRFChem, is used to simulate physical and chemical processes such as transport, transformation, and deposition. Model simulations for a tourist season are performed without and with the inclusion of a ship emission inventory developed for this study. Ship emissions are shown to significantly increase both primary and secondary pollutant concentrations in the Gulf of Alaska causing reduced visibility and contributing greatly to accumulated deposition into coastal ecosystems. Complex topography also plays a role in regions most affected by ship emissions including Prince William Sound and the Kenai Peninsula. Meteorological conditions govern the temporal evolution of air quality and deposition throughout the season. Evaluation of WRFChem with meteorological observations reveals that it well captures the synoptic situation during the season. WRFChem underestimates aerosol concentrations, but aerosol monitoring sites are sparse within the Gulf of Alaska and may not accurately reflect overall performance"--Leaf iii