Have questions about ancient carbon in aerosols generated by bursting bubbles from breaking waves? Then come to the hotel Scandic Lerkendal in beautiful Trondheim, Norway on Tuesday, June 6, at 2 pm for my talk at the 2018 Radiocarbon Conference:
Radiocarbon (14C) constraints on the fraction of refractory dissolved organic carbon in primary marine aerosol from the Northwest Atlantic
Steven R. Beaupré, David J. Kieber, William C. Keene, Michael S. Long, Amanda A. Frossard, Joanna D. Kinsey, Patrick Duplessis, Rachel Chang, John R. Maben, Xi Lu, Yuting Zhu, John Bisgrove
Nearly all organic carbon in seawater is dissolved (DOC), with more than 95% considered refractory based on modeled average lifetimes (~16,000 years) and characteristically old bulk radiocarbon (14C) ages (4000 – 6000 years) that exceed the timescales of overturning circulation. Although this refractory dissolved organic carbon (RDOC) is present throughout the oceans as a major reservoir of the global carbon cycle, its sources and sinks are poorly constrained. Recently, RDOC was proposed to be removed from the oceans through adsorption onto the surfaces of rising bubble plumes produced by breaking waves, ejection into the atmosphere via bubble bursting as a component of primary marine aerosol (PMA), and subsequent oxidation in the atmosphere. To test this mechanism, we used natural abundance 14C (5730 ± 40 yr half-life) to trace the fraction of RDOC in PMA produced in a high capacity generator at two biologically-productive and two oligotrophic hydrographic stations in the Northwest Atlantic Ocean during a research cruise aboard the R/V Endeavor (Sep – Oct 2016). The 14C signatures of PMA generated day and night from near-surface (5 m) and deep (2500 m) seawater were compared with corresponding 14C signatures in seawater of near-surface dissolved inorganic carbon (DIC, a proxy for recently produced organic matter), bulk deep DOC (a proxy for RDOC), and near-surface bulk DOC. Results constrain the selectivity of PMA formation from RDOC in natural mixtures of recently produced and refractory DOC. The implications of these results for PMA formation and RDOC biogeochemistry will be discussed.