Geothermal, Oceanic, Wildfire, Meteorological and Anthropogenic Impacts on PM<sub>2.5</sub> Concentrations in the Fairbanks Metropolitan Area

Abstract

The impacts of low and high-frequency variability from teleconnections between large scale atmospheric processes and local weather as well as emissions changes on concentrations of particulate matter of 2.5 µm or less in diameter ([PM 2.5 ]) were examined for the Fairbanks Metropolitan Area (FMA). October to March and May to August mean [PM 2.5 ] were 1.8 and 3.1 µg•m −3 higher for positive than negative annual mean Pacific Decadal Oscillation. Annual mean [PM 2.5 ] were 3.8 µg•m −3 lower for positive than negative Southern Oscillation Index. On 1999-2018 average, [PM 2.5 ] decreased 2.9 µg•m −3 •decade −1. On average over October to March, decadal and inter-annual variability caused higher or similar differences in mean observed [PM 2.5 ] and its species than emission-control measures. The 2006 implementation of Tier 2 for new vehicles decreased observed sulfate concentrations the strongest (~4.95 µg•m −3 •decade −1) of all occurred emissions changes. On average, observed [PM 2.5 ] showed elevated values at all sites when wind blew from directions of hot springs. The same was found for the sulfate, ammonium and non-metal components of PM 2.5. Observations showed that these geothermal waters contain sulfate, ammonia, boric acid and non-metals. Hot springs of such composition are known to emit hydrogen sulfide and ammonia that can serve as precursors for ammonium and sulfate aerosols.

Mesoscale Impacts on Cold Season PM<sub>2.5</sub> in the Yukon Flats

“…Being mostly located north of the Arctic Circle, the Yukon Flats in Interior Alaska receive little to no insolation from late November to late January, for which radiative cooling may lead to multi-day surface-based temperature inversions (SBI) wherein pollutants may accumulate over time [1] [2]. Besides such local causes, some large-scale synoptic conditions can cause temperature inversions.…”