Microbially mediated cobalt oxidation in seawater revealed by radiotracer experiments
Open Access
- 22 December 1993
- journal article
- research article
- Published by Wiley in Limnology and Oceanography
- Vol. 38 (8) , 1593-1602
- https://doi.org/10.4319/lo.1993.38.8.1593
Abstract
The influence of microbial activity on Co and Mn oxidation in decomposing diatom cultures was determined with radiotracer techniques. Adding a consortium of microorganisms collected from coastal seawater (0.2–3‐µm size fraction) to the cultures increased particulate Co formation rates at 18°C by an order of magnitude (to 3.8% d−1) and particulate Mn formation rates 3‐fold (to 7.9% d−1) over rates in cultures without added microorganisms. The rates of both particulate Co and Mn formation increased with incubation temperature (Q10 = 2.5–2.9 for Co and 1.3–1.8 for Mn; T = 4–18°C) and were faster in the dark than in the light. Ascorbic acid (used as a reducing agent) rinses of particulate Co and Mn indicated that these particles were primarily formed by the oxidation of Co(II) and Mn(II) to metal oxides. By manipulating Mn: Co ratios we showed that formation of particulate Co is directly mediated by microbial activity rather than Co adsorption to or oxidation by Mn oxides. The results help explain the scavenged‐type profile exhibited by Co in the water column and the high Kds of Co in marine sediments.Keywords
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