High Resolution Image Download MS PowerPoint Slide Black carbon (BC) dynamics in polar fjords remain poorly understood despite their importance in organic carbon (OC) cycling. We investigated BC dynamics in the water column and sediments of Antarctic fjords. Dissolved BC concentrations in Marian Cove and Maxwell Bay ranged from 0.10–2.71 and 0.70–2.70 μM, respectively, with molecular characteristics indicating highly condensed, locally anthropogenic BC rather than photochemically aged biomass-burning sources. Bayesian mixing model analyses showed that fossil-fuel-derived BC increased 2.7-fold, from 6% in 2019 to 16% in 2023, reflecting intensified tourism and research activities following COVID-19-related restrictions. Sedimentary BC (73–85% C 3 -derived) suggests local combustion sources, although minor contributions from natural biomass burning cannot be excluded. In contrast, Arctic Kongsfjorden sediments showed 53% C 4 contribution, indicating long-range wildfire BC transport. Marian Cove sediment traps yielded a BC flux of 0.04 g m –2 d –1 (22% of OC flux). Higher apparent burial efficiency of BC (89–114%) relative to OC (75–95%), together with elevated Δ(SBC:OC) values (1.20) and millennial-scale radiocarbon ages (4700–5120 yr), indicate preferential BC preservation. These findings show that Antarctic fjords effectively sequester anthropogenic BC and highlight the importance of incorporating BC dynamics into polar coastal carbon budgets.
Min et al. (Sat,) studied this question.