Iron isotope systematics in Arctic rivers

• Published in: Comptes Rendus Geoscience
• Main Authors: Escoube, R., Rouxel, Olivier, Pokrovsky, O.S., Schroth, A., Max Holmes, R., Donard, O.F.X.
• Other Authors: Institut des sciences analytiques et de physico-chimie pour l'environnement et les materiaux (IPREM), Université de Pau et des Pays de l'Adour (UPPA)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2015
• Subjects: [CHIM.ANAL]Chemical Sciences/Analytical chemistry; Arctic; Arctic Ocean; Climate change; Alaska
• Online Access: https://hal.archives-ouvertes.fr/hal-01590277; https://doi.org/10.1016/j.crte.2015.04.005

cited By 7 International audience The input of iron to the Arctic Ocean plays a critical role in the productivity of aquatic ecosystems and is potentially impacted by climate change. We examine Fe isotope systematics of dissolved and colloidal Fe from several Arctic and sub-Arctic rivers in northern Eurasia and Alaska. We demonstrate that the Fe isotopic (δ56Fe) composition of large rivers, such as the Ob' and Lena, has a restricted range of δ56Fe values ca.-0.11±0.13‰, with minimal seasonal variability, in stark contrast to smaller organic-rich rivers with an overall δ56Fe range from-1.7 to+1.6‰. The preferential enrichment with heavy Fe isotopes observed in low molecular weight colloidal fraction and during the high-flow period is consistent with the role of organic complexation of Fe. The light Fe isotope signatures of smaller rivers and meltwater reflect active redox cycling. Data synthesis reveals that small organic-rich rivers and meltwater in Arctic environments may contribute disproportionately to the input of labile Fe in the Arctic Ocean, while bearing contrasting Fe isotope compositions compared to larger rivers. © 2015 Académie des sciences.