Immobilisation of manganese,cobalt and nickel by deep-sea-sediment microbial communities |
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Authors: | P. P. Sujith Anindita Das Babu Shashikant Mourya |
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Affiliation: | Microbiology Laboratory , National Institute of Oceanography, Council of Scientific and Industrial Research , Dona Paula , Goa , India |
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Abstract: | Box core samples BC26 and BC36 from geologically different settings were examined to test the hypothesis that autochthonous microbial communities from polymetallic-nodule-rich Central Indian Basin sediments actively participate in immobilising metal ions. The bottom water dissolved oxygen concentration was reported to be 4.2–4.3 mL·L?1 in the northern siliceous ooze (BC26) and 4.1–4.2 mL·L?1 in the southern pelagic red clay (BC36); the sedimentation rates for these regions were 0.834 and 0.041 cm·kyr?1, respectively. An onboard experiment, conducted under oxic and sub-oxic conditions with 100 μmol of Mn, Co and Ni, showed that microbial immobilisation under sub-oxic conditions was higher than in azide-treated controls in BC26 for Mn, Co and Ni at 30, 2 and 4 cm below sea floor (bsf), respectively, after 45 days. The trend in immobilisation was BC 26>BC 36, Co>Mn>Ni under oxic conditions and Mn>Co>Ni under sub-oxic conditions. The depth of maximum immobilisation for Co in BC26 under sub-oxic conditions coincided with the yield of cultured Co-tolerant bacteria and Ni only with organic carbon at 4 cm bsf. This study demonstrates that the organic carbon content and bioavailable metal concentrations in sediments regulate microbial participation in metal immobilisation. |
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Keywords: | metals microbes immobilisation sediment Central Indian Basin |
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