Boundary exchange and benthic fluxes drive trace element cycling in North Pacific marginal seas

Abstract Trace elements are essential micronutrients for primary producers in the ocean, supporting vital metabolic functions. However, their behavior in the northwestern Pacific remains unknown. This study investigated the behavior and benthic fluxes of Mn, Fe, Co, Ni, Cu, Zn, and Cd in the East/Japan Sea and the Yellow Sea. Rare earth element fractionations ([Nd/Er] PAAS and Ce/Ce* ratios) were used to trace scavenging and water mass inputs. In the East/Japan Sea, trace element distributions were categorized into three categories. Mn, Fe, and Co were influenced by atmospheric deposition in surface waters and benthic input, with fluxes of 742, 96, and 0.8 μ mol m −2 yr −1 , respectively. Ni and Cu were depleted from surface waters and had a limited influence from benthic inputs. Zn and Cd were regulated by biological activity. Zn concentrations ranged from 0.6 to 1.5 nmol kg −1 at the surface, peaked at 6.8–11.8 nmol kg −1 at a depth of 500 m, and decreased to 3.5–7.9 nmol kg −1 at the bottom. Zn correlated positively with in the upper 500 m but negatively at greater depths, likely owing to shelf inputs. In the Yellow Sea, all trace elements exhibited a vertically conserved distribution owing to rapid water mixing. These results contribute to the current biogeochemical understanding of the region by providing higher‐resolution cross‐transect investigations and report the decoupling of Zn– in the East/Japan Sea for the first time.