Biogenic Origin of Polymetallic Nodules from the C

Authors: Xiaohong Wang Ute Schloßmacher Matthias Wiens Heinz C Schröder Werner E G Müller

Publish Date: 2008/08/01

Volume: 11, Issue: 1, Pages: 99-

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Abstract

Polymetallic/ferromanganese nodules Mnnodules have been assigned a huge economic potential since they contain considerable concentrations of manganese copper nickel iron and cobalt It has been assumed that they are formed by besides hydrogenous nonbiogenic processes biogenic processes based on metabolic processes driven by microorganisms In the present study we applied the techniques of digital optical microscopy and highresolution scanning electron microscopy to search for microorganisms in Mnnodules They were collected from the ClarionClipperton Zone in the Eastern Pacific Ocean and are composed of Mn 239 Cu 069 Ni 102 Fe 109 and Co 029 These Mnnodules between 23 and 48 cm show a distinct lamination they are composed of smallsized micronodules 100 to 450 μm in size which are bound together by an interstitial whitish material In the micronodules a dense accumulation of microorganisms/bacteria could be visualized Only two morphotypes exist 1 roundshaped cocci and 2 elongated rods The cocci diameter ≈35 μm are arranged in beadlike chains while the rods ≈2 × 04 μm are arranged either as palisades or in a linear row Energydispersive Xray spectroscopy analyses showed that the areas rich in microorganisms/bacteria are also rich in Mn while in regions where no microorganisms are found the element Si is dominant We suggest that growth of the Mnnodules starts with the formation of “micronodules” The formation of micronodules is assumed to be mediated by microorganisms After accretion of biogenic and additional nonbiogenic minerals the micronodules assemble to large nodules on the sea floor through additional inclusion of nonbiogenic materialWe thank Mr G Glasser and Ms M Müller Research group “Surface Chemistry” Dr I Lieberwirth and Dr M Kappl Max Planck Institute for Polymer Research Mainz for excellent assistance in electron microscopic analysis We thank Prof Dr GN Baturin Shirshov Institute of Oceanology Russian Academy of Sciences Moscow for helpful advices This work was supported by grants from the Bundesministerium für Bildung und Forschung Germany project Center of Excellence BIOTECmarin from International S T Cooperation Program of China Grant No 2008DFA00980 and from the Key Laboratory of Marine Sedimentology and Environmental Geology State Oceanic Administration Grant No MASEG200602

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