Investigating the temporal trends and source apportionment of total and speciated volatile organic compounds and size-resolved particle mass and number on Sable Island (2016)

Over the past 6 years, an atmospheric observatory, located on the remote sandbar Sable Island in the Northwest Atlantic, has collected near-continuous records of various atmospheric chemistry metrics. This small island is unique in that its atmospheric composition is influenced by several sources: oil and gas production activity, continental outflow, on-island sources of gases and aerosol, sea salt spray, and marine biogenic processes such as the emission of volatile organic compounds (VOCs) by phytoplankton. This provided an ideal natural laboratory to conduct studies on techniques to identify and quantify the sources and drivers of anthropogenic, geogenic and biogenic volatile organic compounds, gases and aerosol emission sources affecting its atmospheric composition. Due to its highly synergistic research objectives, the project became part of the NASA North Atlantic Aerosols and Marine Ecosystems Study (NAAMES). Study metrics included total-VOC, black carbon, hydrogen sulfide, mono-nitrogen oxides, ozone, sulfur dioxide, particulate matter with a median aerodynamic diameter less than or equal to 10/4/2.5/1 microns (PM_10/4/2.5/1), and size-resolved particle number counts between 20 nm and 20 microns, over 58 size bins. VOC species were collected over a 24-hour period onto thermal desorption tubes. Positive Matrix Factorization modeling was used to apportion aerosol sources impacting Sable Island. In order to investigate potential sources of the secondary marine biogenic particles, satellite-derived chlorophyll-a concentration records were examined for the surrounding region. A strong correlation was found with ultrafine particle number (20-30 nm & 30-50 nm) - R²= 0.66 and R² = 0.71 respectively, suggesting that processes associated with the presence of phytoplankton contributes significantly to the formation of potentially climate-relevant particulate matter. These findings are highly relevant to ongoing efforts to quantify the role of ocean-atmosphere processes in particulate and cloud formation, which remains a source of high uncertainty in global climate modeling.