Contributions of Transported Prudhoe Bay Oilfield Emissions to the Aerosol Population in Utqiaġvik, Alaska.

Loss of sea ice is opening the Arctic to increasing development involving oil and gas extraction and shipping. Given the significant impacts of absorbing aerosol and secondary aerosol precursors emitted within the rapidly warming Arctic region, there is a need to characterize local anthropogenic aerosol sources and compare to natural conditions. From August-September 2015 in Utqiaġvik, AK, the chemical composition of individual atmospheric particles was measured by computer-controlled scanning electron microscopy with energy dispersive X-ray spectroscopy (0.13-4 μm projected area diameter) and real-time single particle mass spectrometry (0.2-1.5μm aerodynamic diameter). During Arctic Ocean influenced periods (70% of the study), our results show that fresh sea spray aerosol contributed ~20%, by number, of particles between 0.13-0.4μm, 40-70% between 0.4-1μm, and 80-100% of 1-4μm particles. In contrast, for periods influenced by emissions from Prudhoe Bay (10% of the study), the third largest oilfield in North America, there was a strong influence from submicron (0.13-1μm) combustion derived particles (20-50% OC, by number, 5-10% soot by number). While sea spray aerosol still comprised a large fraction of particles (90% by number from 1-4μm) detected under Prudhoe Bay influence, these particles were internally mixed with sulfate and nitrate indicative of aging processes during transport. In addition, the overall mode of the particle size number distribution shifted from 76nm during Arctic Ocean influence to 27nm during Prudhoe Bay influence with particle concentrations increasing from 130cm^-3 to 920cm^-3 due to transported particle emissions from the oil fields. The increased contributions of carbonaceous combustion products and partially aged SSA should be taken into consideration for future Arctic atmospheric composition and climate simulations. [ABSTRACT FROM AUTHOR]