The Xiamen Symposium on Marine Environmental Sciences (XMAS 2025)

The Nordic Seas are a key transition zone between the Atlantic and Arctic Oceans, where the northward advection of warm Atlantic water encounters the southward flowing cold Arctic water. The interaction between these two water masses has been shown to govern macro- and micro-nutrient availability, potentially influencing primary production in Fram Strait (Northern Greenland Sea). However, little is known how Arctic and Atlantic waters impact micronutrient availability in the central and southern Greenland Sea, Norwegian Sea, and Iceland Sea. To address this gap, we present a dataset from the JR271 expedition (June 2012), focusing on macronutrients [fixed N (NO₃^-+NO₂^-), phosphate (PO₄^3-) and silicic acid (Si(OH)₄)] and key micronutrients including dissolved Fe (dFe), manganese (dMn) and cobalt (dCo) that are thought to impact primary production in the region.
Our data reveal a distinct north-to-south gradient in surface Si(OH)₄ and micronutrient concentrations, following the pathway of the East Greenland Current (EGC), which is influenced by the Transpolar Drift (TPD) fed by contributions from riverine and sediment sources on the Arctic Ocean shelves. The surface waters of eastern Iceland Sea and southwestern Greenland Sea exhibit elevated concentrations of fixed N and PO₄^3- but negative values of Fe* (the relative excess of Fe in comparison to N, assuming typical phytoplankton requirements), suggesting Fe scarcity driven by the influence of North Atlantic Current and drawdown by phytoplankton. In the water column, macronutrients increase with depth, representing a nutrient reservoir supplying surface waters during deep winter mixing, while trace element concentrations remain relatively homogenous across the wider region. On a local scale, shelf sediments are a further source of micronutrients as evident near the North Sea slope and Svalbard shelf slope. The relationship of trace elements with nutrients across different water masses, further highlights the mixing of Arctic and Atlantic waters with different nutrient regimes.
This study delineates the southern extent of Arctic Ocean trace metal export into the North Atlantic Ocean via the TPD-EGC network. Our findings stress the importance of Siberian Shelf inputs and long-range transport in shaping micronutrient and Si(OH)₄ availability in the western Nordic Seas. We suggest that the interaction between Arctic and Atlantic Waters significantly affects nutrient stoichiometry, potentially enhancing primary production (as indicated by elevated chlorophyll-a) in an otherwise perhaps iron-depleted region following the spring bloom.