First Data on Vertical Particle Fluxes and Environmental Conditions in the Northern Segment of the Mohns Ridge, Norwegian Sea

Abstract

Continuous two-year studies of particle fluxes and associated environmental parameters in the axial zone of the Arctic segment of the Mid-Atlantic Ridge at the junction of the Mohns and Knipovich ridges (Norwegian Sea) have been carried out for the first time. Sediment traps were deployed from the R/V Akademik Mstislav Keldysh in June 2019 in the northeastern part of the Mohns Ridge with revision in August 2020 and lifting in July 2021. It is shown that the sedimentation of particles in the study area was affected by the global transport of water masses in the northeasterly direction, with Atlantic waters in the subsurface layer and water masses of Arctic origin recirculating deeper in the subsurface. A weak positive temperature trend at a depth of more than 2500 m (0.02°C over two years) is detected. The bimodal vertical distribution of fluxes and changes in the composition of sinking particles corresponded to the pattern of sediment recycling in the ocean. The annual course of fluxes in the subsurface layer is determined by the activity of Si-concentrating and calcifying plankton, while the maximum bloom period is also manifested in the deep layer. At the same time, the main significant source of the flux deeper than 2000 m is the supply of lithogenic matter from the near-bottom nepheloid layer.