caa a22 4500 605516464 CHVBK 20210128100714.0 cr unu---uuuuu 210128e20150501xx s 000 0 eng 10.1007/s10533-015-0081-8 doi (NATIONALLICENCE)springer-10.1007/s10533-015-0081-8 Silicon isotope composition of dissolved silica in surface waters of the Elbe Estuary and its tidal marshes [Elektronische Daten] [Andreas Weiss, Christina De La Rocha, Thorben Amann, Jens Hartmann] Land ocean silica fluxes pass estuaries. Recent data suggest that the isotopic composition of dissolved silica (DSi) is not altered during this transition. This could have major implication for the oceanic isotopic silicon cycle. To improve our knowledge about isotopic Si cycling in estuaries we investigate the silicon isotopic composition (δ30Si) of DSi of the Elbe Estuary and for the first time of tidal marsh areas. DSi concentrations in the tidal marshes were generally higher during seepage phase than during bulk phase. Negligible tidal variation in δ30Si (1.71±0.08-1.87±0.13‰) occurred in the freshwater marsh. In the brackish marsh δ30Si was higher during the seepage phase than during the bulk phase, with highest noted values being >2.78±0.11‰. In the salt marsh, seepage water had lower δ30Si than bulk water over a total range of 1.81±0.03-2.62±0.02‰. In the estuary in October, DSi concentrations in the freshwater zone were diminished through removal by diatoms. The δ30Si of DSi increased from 1.43±0.11 to 2.33±0.08‰. In December, DSi concentrations increased along the estuary through lateral input from tributaries and tidal marshes. δ30Si values in the freshwater and brackish zones were lower than in October. The most notable changes in δ30Si occurred in the tidal freshwater zone of the estuary. This underscores that this zone modulates the delivery of reactive silica from land to sea. If true for other systems estuarine transformation would significantly contribute to the long term control of the silicon isotopic composition of the ocean. Springer International Publishing Switzerland, 2015 Silicon isotopes nationallicence δ30Si nationallicence Dissolved silica nationallicence Elbe Estuary nationallicence Tidal marsh nationallicence Silica cycling nationallicence Weiss Andreas Institut für Geologie, Universität Hamburg, KlimaCampus, Bundesstraße 55, 20146, Hamburg, Germany aut De La Rocha Christina CNRS UMR 6539, Institut Universitaire Européen de la Mer, Université de Bretagne Occidentale, Technôpole Brest-Iroise, Place Nicholas Copernic, 29280, Plouzané, France aut Amann Thorben Institut für Geologie, Universität Hamburg, KlimaCampus, Bundesstraße 55, 20146, Hamburg, Germany aut Hartmann Jens Institut für Geologie, Universität Hamburg, KlimaCampus, Bundesstraße 55, 20146, Hamburg, Germany aut Biogeochemistry Springer International Publishing 124/1-3(2015-05-01), 61-79 0168-2563 124:1-3<61 2015 124 10533 https://doi.org/10.1007/s10533-015-0081-8 text/html Onlinezugriff via DOI BK010053 XK010053 XK010000 Metadata rights reserved Springer special CC-BY-NC licence nationallicence 1 research-article jats NATIONALLICENCE NATIONALLICENCE NL-springer NATIONALLICENCE 856 40 https://doi.org/10.1007/s10533-015-0081-8 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Weiss Andreas Institut für Geologie, Universität Hamburg, KlimaCampus, Bundesstraße 55, 20146, Hamburg, Germany aut NATIONALLICENCE 700 1- De La Rocha Christina CNRS UMR 6539, Institut Universitaire Européen de la Mer, Université de Bretagne Occidentale, Technôpole Brest-Iroise, Place Nicholas Copernic, 29280, Plouzané, France aut NATIONALLICENCE 700 1- Amann Thorben Institut für Geologie, Universität Hamburg, KlimaCampus, Bundesstraße 55, 20146, Hamburg, Germany aut NATIONALLICENCE 700 1- Hartmann Jens Institut für Geologie, Universität Hamburg, KlimaCampus, Bundesstraße 55, 20146, Hamburg, Germany aut NATIONALLICENCE 773 0- Biogeochemistry Springer International Publishing 124/1-3(2015-05-01), 61-79 0168-2563 124:1-3<61 2015 124 10533