Marine primary production enhances removal of hydrophobic organic contaminants from Eurasian Arctic shelf waters

Global oceans store large quantities of human-made persistent hydrophobic organic contaminants (HOCs), driven by the organic carbon (OC) cycle. Despite diverse organic matter composition, bulk OC is typically treated as a uniform sorbent when assessing HOC fate. Significant uncertainty remains regarding the factors controlling variability in the sorption of HOCs by organic matter. Using surface sediments across the Eurasian Arctic shelves, spanning a land-to-ocean continuum of OC, we show that polychlorinated biphenyl concentrations per unit marine‑derived OC are up to an order of magnitude higher than those per unit terrestrial OC. Coupling these empirical relationships with a state‑of‑the‑art ocean biogeochemistry model shows that climate‑driven increases in marine primary production in the Eurasian Arctic shelves lead to 1.3 times more HOC removal from the water column. These findings reveal that both OC quantity and quality control the sediment HOC sink and that climate‑induced shifts in OC cycles may restructure HOC fate in the Arctic Ocean.