Contributions of transported Prudhoe Bay oil field emissions to the aerosol population in Utqiaġvik, Alaska

摘要

Loss of seaice is opening the Arctic to increasing developmentinvolving oil and gas extraction and shipping. Given the significantimpacts of absorbing aerosol and secondary aerosol precursorsemitted within the rapidly warming Arctic region, it is necessary tocharacterize local anthropogenic aerosol sources and compare tonatural conditions. From August to September 2015 in Utqiaġvik (Barrow),AK, the chemical composition of individual atmospheric particles wasmeasured by computer-controlled scanning electron microscopy withenergy-dispersive X-ray spectroscopy (0.13–4 µmprojected area diameter) and real-time single-particle massspectrometry (0.2–1.5 µm vacuum aerodynamic diameter). During periodsinfluenced by the Arctic Ocean (70 % of the study), our resultsshow that fresh sea spray aerosol contributed  ∼ 20 %, bynumber, of particles between 0.13 and 0.4 µm, 40–70 %between 0.4 and 1 µm, and 80–100 % between1 and 4 µm particles. In contrast, for periods influencedby emissions from Prudhoe Bay (10 % of the study), the thirdlargest oil field in North America, there was a strong influencefrom submicron (0.13–1 µm) combustion-derived particles(20–50 % organic carbon, by number; 5–10 % soot by number). While seaspray aerosol still comprised a large fraction of particles(90 % by number from 1 to 4 µm) detected under PrudhoeBay influence, these particles were internally mixed with sulfateand nitrate indicative of aging processes during transport. Inaddition, the overall mode of the particle size number distributionshifted from 76 nm during Arctic Ocean influence to27 nm during Prudhoe Bay influence, with particleconcentrations increasing from 130 to 920 cm due totransported particle emissions from the oil fields. The increasedcontributions of carbonaceous combustion products and partially agedsea spray aerosol should be considered in future Arctic atmosphericcomposition and climate simulations.