Cycling of black carbon in the ocean

Black carbon (BC) is a byproduct of combustion from wildfires and fossil fuels and is a slowcycling component of the carbon cycle. Whether BC accumulates and ages on millennial timescales in the world oceans has remained unknown. Here, we quantified dissolved BC (DBC) in marine dissolved organic carbon (DOC) isolated by solid phase extraction (SPE) at several sites in the world ocean. We find that DBC in the Atlantic, Pacific and Arctic oceans ranges from 1.4 to 2.6 �M in the surface and is 1.2 ± 0.1 �M in the deep Atlantic. The average 1�C age of surface DBC is 4,800 ± 620 1�C yrs, and much older in a deep water sample (23,000 ± 3,000 1�C yrs). The range of DBC structures and 1�C ages indicates that DBC is not homogeneous in the ocean. We show that there are at least two distinct pools of marine DBC, a younger pool that cycles on centennial timescales and an ancient pool that cycles on >10� year timescales. DOI: https://doi.org/10.1002/2016GL068574 Posted at the Zurich Open Repository and Archive, University of Zurich ZORA URL: https://doi.org/10.5167/uzh-123985 Accepted Version Originally published at: Coppola, Alysha I; Druffel, Ellen R M (2016). Cycling of black carbon in the ocean. Geophysical Research Letters, 43(9):4477-4482. DOI: https://doi.org/10.1002/2016GL068574