Tropical mangrove forests as a source of dissolved rare earth elements and yttrium to the ocean

Tropical mangrove forests as a source of dissolved rare earth elements and yttrium to the ocean Duc Huy Dang auteur aut IRD Zhirou Zhang auteur aut IRD Wei Wang auteur aut IRD Oursel B. auteur aut IRD Juillot Farid auteur aut IRD Dupouy Cécile auteur aut IRD Lemonnier H. auteur aut IRD Mounier S. auteur aut IRD text journalArticle eng text/pdf born digital access Rare earth elements (REEs) and Y are commonly used as geochemical proxies for water chemistry, history of the continental crust and provenance studies. At the continent-ocean interface, the estuarine geochemistry of REEs is commonly considered to be driven by a largescale removal. Consequently, the river-borne flux of dissolved REEs to the marine budget is assumed as a minor fraction. Here, we report a significant release of dissolved REEs, together with a fractionation between light, heavy REEs and Y, in the tropical mangrove estuaries of New Caledonia. These observations were associated with internal recycling within the redox-dynamic mangrove system. The possible contribution of groundwater can be ruled out based on water stable isotopes. These findings imply that tropical mangrove estuaries act as a sizeable source of REEs and Y to the ocean rather than as a buffer zone. We extrapolated our data toward global dissolved fluxes of REEs and Y through the mangroves. This preliminary calculation suggests that the mangrove system supplies 2.6-5% of global river-borne dissolved Nd, a REE with the most comprehensive mass balance. Therefore, oceanic mass balance budget models may need to consider this atypical system as an input to balance the global distribution of REEs and Y. specialized ESTUAIRE CHIMIE DE L'EAU TERRES RARES MANGROVE ANALYSE ISOTOPIQUE CYCLE BIOGEOCHIMIQUE YTTRIUM NOUVELLE CALEDONIE PACIFIQUE ZONE TROPICALE 032MILPHY 064GEOCHI 082ECOSYS Chemical Geology 576 120278 [12 ] 2021 0009-2541 https://www.documentation.ird.fr/hor/fdi:010080310 10.1016/j.chemgeo.2021.120278 0009-2541 [F B010080310] https://www.documentation.ird.fr/hor/fdi:010080310 https://www.documentation.ird.fr/intranet/publi/2021-06/010080310.pdf Accès réservé (Intranet de l'IRD) IRD - Base Horizon / Pleins textes 2021-06-02 2025-02-24 fdi:010080310 fre