Distinct drivers control trace metal distributions through the Atlantic Ocean

Abstract

Trace metals (TMs) including iron, manganese, cobalt, nickel, copper, zinc, cadmium, and lead have important biogeochemical roles in the ocean. However, the controlling factors of TM distributions have not yet been quantified and investigated on an ocean scale. Here we take a holistic approach to demonstrate that transport through water masses formed in high latitudes can explain 60–90% of dissolved TM distributions and >75% of TM inventories in the interior Atlantic. Water mass signatures were slightly modified by sinking organic matter remineralization mainly for iron, cobalt, nickel, cadmium, scavenging removal for iron, manganese, cobalt, lead, and hydrothermal inputs for iron and manganese. Our approach allowed prediction of the baseline TM distributions through the Atlantic at high spatial resolution. Through quantification, our findings emphasize the important role of large-scale oceanic circulation in determining global TM distributions once the water mass endmembers are set, despite the distinctive geochemical behaviors of the assessed TMs. Climate-related changes in a future ocean that impact endmember concentrations or relative water mass contributions may therefore perturb downstream TM inventories and ultimately affect ocean productivity and ocean carbon pump. Transport through water masses formed in high latitudes can explain 60–90% of dissolved trace metal distributions and higher than 75% of trace metal inventories in the interior of the Atlantic Ocean, based on water mass analysis.