Decoupling of dissolved and particulate Li isotopes during estuarine processes

Type : ACL
Nature : Production scientifique
Au bénéfice du Laboratoire : Oui
Statut de publication : Publié
Année de publication : 2021
Auteurs (5) : YANG Chengfan VIGIER Nathalie LIAN Ergang LAI Z YANG Shouye
Revue scientifique : Geochemical Perspectives Letters
Volume : 19
Fascicule :
Pages : 40-44
DOI : 10.7185/geochemlet.2133
URL : -
Abstract : Lithium isotopes in marine authigenic or detrital sedimentary archives have been recently used to trace continental weathering over geologic timescales. However, interpretations are predominantly based on the assumption that riverine Li isotopic signals can be propagated through estuaries without modification. Here, we verify this hypothesis by investigating the behaviour of Li isotopes in the Changjiang (Yangtze) River estuary. We observe a conservative mixing of dissolved Li and its iso- topes between the Changjiang River water and seawater. The dissolved δ7Li yields a non-linear increase with salinity, and a significant increase occurs during the initial water mixing. Through the studied transect, estuarine flocculation and resuspension processes cause the homogenisation of offshore particulate δ7Li values, which are
close to the average composition of upper continental crust. This study provides clear and direct evidence that the riverine dis- solved Li isotopic signal is not modified during estuarine processes in large rivers, but caution should be exercised when using detrital δ7Li in marginal seas to investigate past continental weathering.
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Citation :
Yang C, Vigier N, Lian E, Lai Z, Yang S (2021) Decoupling of dissolved and particulate Li isotopes during estuarine processes. Geochem Persp Let 19: 40-44 | doi: 10.7185/geochemlet.2133