Nanoscale lignin particles as sources of dissolved iron to the ocean

Author(s): Regina Krachler, Frank von der Kammer, Franz Jirsa, Altan Süphandag, Rudolf Krachler, Christof Plessl, Bernhard Keppler, Thilo Hofmann
Abstract: Primary production in large areas of the open ocean is limited by low iron concentrations. Rivers are potential sources of iron to the ocean, however, riverine iron is prone to intense flocculation and sedimentation in the estuarine mixing zone. Here we report the detection of iron-rich nanoparticles in a typical peatland-draining creek which are resistant against salt-induced flocculation i.e., their behavior is in sharp contrast to the well-known behavior of Fe colloids in river waters. Sample fractionation by AsFlFFF (Asymmetric Flow Field Flow Fractionation) revealed that these powerful iron carriers are in the size range of only 0.5-3.0 nm hydrodynamic diameter. They were isolated from the water phase using solid phase extraction/gel permeation chromatography, and analyzed by a CuO oxidation/GC-MS method. Our results suggest that the particles consist mainly of lignin catabolites and that gymnosperm as well as angiosperm tissues are contributors to the seawater-resistant iron-bearing DOM. Lignin phenols, which have no autochthonous source in the ocean, have been nevertheless found in low concentrations throughout the entire Arctic, Atlantic, and Pacific oceans. It is therefore tempting to speculate that peatland-derived iron-bearing lignin particles may have a sufficiently long half-life in ocean waters to sustain iron concentration in extended regions of the ocean.
Organisation(s): Department of Inorganic Chemistry
Journal: Global Biogeochemical Cycles: an international journal of global change
Volume: 26
ISSN: 0886-6236
DOI: https://doi.org/10.1029/2012GB004294
Publication date: 2012
Peer reviewed: Yes
Austrian Fields of Science 2012: 104023 Environmental chemistry
Portal url: https://ucrisportal.univie.ac.at/en/publications/18896b6c-39ff-4fe2-b137-6620abaf99ed

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