Solid-phase Mn speciation in suspended particles along meltwater-influenced fjords of West Greenland

Manganese (Mn) is an essential micro-nutrient that can limit or, along with iron (Fe), co-limit phytoplankton growth in the ocean. Glacier meltwater thought to be a key source of trace metals high latitude coastal systems, but little known about nature Mn delivered glacially-influenced fjords and adjacent waters. In this work, we combine in-situ dissolved (dMn) measurements surface waters K-edge X-ray absorption spectroscopy (XAS) data suspended particles four West Greenland. Data were collected from transects up 100 km different underlying bedrock geology 64 70°N. We found dMn concentrations generally decreased conservatively increasing salinity (from 80 120 nM at < 8 40 salinities > 25). Dissolved Fe (dFe) trends these similarly declined distance glacier outflows (declining 20 nM). However, dMn/dFe ratio increased rapidly likely due greater stability intermediate (i.e. 10–20) compared rapid precipitation dFe across gradient. The XAS indicated widespread presence Mn(II)-rich near fjord surfaces, structures akin Mn(II)-bearing phyllosilicates. distinct increase oxidation state depth predominance birnessite-like Mn(IV) oxides was observed for tertiary basalt geology. similar behaviour particle speciation (i.e., phyllosilicates Mn(IV)-rich birnessite) consistent decoupling particulate suggests on scale are controlled primarily by dilution freshwater rather than exchange between phases. This work provides new insights into cycle waters, where small changes relative availabilities dMn, macronutrients may affect identity nutrient(s) proximally limiting primary production.