Contrasting complexing capacity of dissolved organic matter produced during the onset,development and decay of a simulated bloom of the marine diatom Skeletonema costatum |
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| Affiliation: | 1. Clermont Université, Université Blaise Pascal, Institut Pascal, UMR 6602 CNRS. Polytech Clermont-Ferrand, 24 avenue des Landais, BP206, F-63174 Aubière cedex, France;2. UMR 7266 CNRS, ULR LIENSs, Equipe Approches Moléculaires Environnement Santé, Université de La Rochelle, UFR Sciences, Bâtiment Marie Curie, avenue Michel Crépeau, 17042 La Rochelle, France;3. Université de Caen Basse-Normandie, CNRS FRE 3484 BioMEA, Esplanade de la Paix, 14032 Caen, France;1. Research Group for Marine Geochemistry (ICBM-MPI Bridging Group), Institute for Chemistry and Biology of the Marine Environment (ICBM), Carl von Ossietzky Universität Oldenburg, Carl-von-Ossietzky-Straße 9-11, D-26129 Oldenburg, Germany;2. Institut für Chemie (IfC), Carl von Ossietzky Universität Oldenburg, Carl-von-Ossietzky-Straße 9-11, D-26129 Oldenburg, Germany;1. School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, GA 30332-0340, USA;2. School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA 30332-0340, USA;3. United States Geological Survey, Boulder, CO 80303, USA;4. Department of Chemistry and Biochemistry, Old Dominion University, Norfolk, VA 23529, USA;5. Research Group for Marine Geochemistry, University of Oldenburg, Institute for Chemistry and Biology of the Marine Environment (ICBM), Carl-von-Ossietzky-Strasse 9-11, D-26129 Oldenburg, Germany;6. Skidaway Institute of Oceanography, Department of Marine Sciences, University of Georgia, Savannah, GA 31411, USA |
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| Abstract: | The capacity of natural dissolved organic matter (DOM) produced during the onset, development and decay of a simulated bloom of the marine diatom Skeletonema costatum to complex free copper has been followed for a 2 week period. Copper binding capacity of the culture was measured by anodic stripping voltammetry (ASV) with a hanging mercury drop electrode (HMDE). The concentration of dissolved organic carbon (DOC) and two fluorophores, M (humic-like, Ex/Em: 320 nm/410 nm) and T (protein-like, Ex/Em: 280 nm/350 nm), were followed during the course of the incubation. Models using DOC concentrations alone could not accurately predict the complexing capacity of the culture, especially at the end of the bloom, and better predictions were obtained when fluorescence measurements were considered. They were helpful in characterising two types of copper ligands produced in the culture. The first type, traced by the fluorescence of peak T, was related to labile DOC directly exuded by phytoplankton. The second type, traced by the fluorescence of peak M, was the refractory humic-like material presumably produced in situ as a by-product of the bacterial degradation of phytogenic materials. During the onset and development of the bloom (days 0 to 7), the fluorescence of peak T explains 60–80% of the total complexing capacity of the culture, suggesting that exuded “protein-like” compounds among other exuded complexing agents efficiently complexed free copper. On the contrary, during the decay (days 8 to 13), these ligands were replaced by humic substances as the complexing agent for copper. |
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