Influences on Summertime Arctic Aerosol Chemical Mixing States

Ongoing unprecedented summertime Arctic sea ice loss is expected to be changing atmospheric composition of the region through increasing development and available open water for the production of marine aerosols and trace gases. Both anthropogenic and natural aerosols have significant climate effects, including interacting with radiation, forming cloud droplets and ice crystals, and depositing onto surfaces. Given the challenges of Arctic measurements and the evolving nature of atmospheric particles, significant uncertainties remain in our understanding of particle sources, evolution, and impacts in the Arctic. Internal composition (mixing state) of atmospheric particles is examined for samples collected in Barrow, Alaska during August-September 2015, aboard the RV Araon in the Chukchi Sea during August 2016, and Oliktok Point, Alaska during August-September 2016. Computer-controlled scanning electron microscopy with energy dispersive X-ray (CCSEM-EDX) analysis is utilized to probe morphology and elemental composition of individual particles, with detailed information about the spatial distribution of elements within these particles. During ground-based sampling at Barrow and Oliktok Point, aerosol time-of-flight mass spectrometry provided real-time analysis of the size and chemical composition of individual particles with detailed source identification. Sea spray particle mixing state and secondary processing will be discussed in detail, with focus on anthropogenic and biogenic influences.