High latitude controls on dissolved barium isotope distributions in the global ocean

Abstract

The high latitude regions play a key role in regulating the marine biogeochemical cycling of barium (Ba) and the pre-formed Ba isotope compositions in the global ocean. In this study, we present 17 new depth profiles of dissolved Ba concentrations ([Ba]) and isotope compositions (δ138Ba) from the high latitude Atlantic, Pacific and Southern Oceans to trace the ventilation of deep waters in the Southern Ocean and their subsequent transport throughout the global ocean. Our data reveal how biogeochemical processes in the Southern Ocean generate distinct δ138Ba signatures of upper ocean water masses, and that large scale ocean circulation constrains the meridional gradient of δ138Ba distributions in the deep Atlantic Ocean. The significant increase in [Ba] of dee waters in the North Pacific is mainl achieved throu h dissolution of sinking particles which adds a δ138Ba signal comparable to the deep Pacific Ocean.(Figure Presented).