Individual Particle Characterization of the Carbon Content of Aerosols Collected in the Eastern North Atlantic

Description

As part of the ACE-ENA field campaign, aerosol samples were collected at the long-term ENA field site operated by the DOE ARM program. During the two intensive operating periods (IOP1 – Summer 2017 and IOP2 – Winter 2018), size segregated sampling was carried out using a micro-orifice uniform deposit impactor. These samples were collected on several different substrates to enable the determination of the detailed chemical and physical properties of individual particles including chemical composition and ice nucleation activity. Chemical composition of elements with Z>23 was determined using scanning electron microscopy coupled with energy dispersive X-ray (SEM-EDX) spectroscopy. For lighter elements (C, N, and O), scanning transmission X-ray microscopy coupled with near edge X-ray absorption spectroscopy (STXM-NEXAFS) was used to determine spatially resolved elementally specific molecular information. Using these techniques, marine primary biological particles were observed infrequently. Generally, the aerosol composition was consistent with air mass back trajectories. Inorganic sea spray aerosol was the major particle type for air masses originating over the ocean and carbonaceous (organic and soot) particles were the major particle type for air masses originating from north America. Overall, these results will aid in developing a better understanding of the CCN budget for the Eastern North Atlantic.