Dissolved organic carbon lability and stable isotope shifts during microbial decomposition in a tropical river system
A significant amount of carbon is transported to the ocean as dissolved organic carbon (DOC) in rivers. During transport, it can be transformed through microbial consumption and photochemical oxidation. In dark incubation experiments with water from the Tana River, Kenya, we examined the consumption...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2016-01-01
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| Series: | Biogeosciences |
| Online Access: | http://www.biogeosciences.net/13/517/2016/bg-13-517-2016.pdf |
| _version_ | 1811236727615913984 |
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| author | N. Geeraert F. O. Omengo G. Govers S. Bouillon |
| author_facet | N. Geeraert F. O. Omengo G. Govers S. Bouillon |
| author_sort | N. Geeraert |
| collection | DOAJ |
| description | A significant amount of carbon is transported to the ocean as dissolved
organic carbon (DOC) in rivers. During transport, it can be transformed
through microbial consumption and photochemical oxidation. In dark
incubation experiments with water from the Tana River, Kenya, we examined
the consumption of DOC through microbial decomposition and the associated
change in its carbon stable isotope composition (<i>δ</i><sup>13</sup>C). In 15
of the 18 incubations, DOC concentrations decreased significantly by 10 to
60 %, with most of the decomposition taking place within the first
24–48 h. After 8 days, the remaining DOC was up to 3 ‰ more
depleted in <sup>13</sup>C compared with the initial pool, and the change in
<i>δ</i><sup>13</sup>C correlated strongly with the fraction of DOC remaining. We hypothesize
that the shift in <i>δ</i><sup>13</sup>C is consistent with greater microbial
lability of DOC originating from herbaceous C<sub>4</sub> vegetation than DOC derived
from woody C<sub>3</sub> vegetation in the semi-arid lower Tana. The results
complement earlier findings that the stable isotope concentration of riverine
DOC does not necessarily reflect the proportion of C<sub>3</sub> and C<sub>4</sub>-derived DOC
in the catchment: besides spatial distribution patterns of different vegetation types,
processing within the river can further influence the <i>δ</i><sup>13</sup>C of riverine OC. |
| first_indexed | 2024-04-12T12:13:01Z |
| format | Article |
| id | doaj.art-f72ce53680c843fa80f6c1fd622d6f51 |
| institution | Directory Open Access Journal |
| issn | 1726-4170 1726-4189 |
| language | English |
| last_indexed | 2024-04-12T12:13:01Z |
| publishDate | 2016-01-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Biogeosciences |
| spelling | doaj.art-f72ce53680c843fa80f6c1fd622d6f512022-12-22T03:33:31ZengCopernicus PublicationsBiogeosciences1726-41701726-41892016-01-0113251752510.5194/bg-13-517-2016Dissolved organic carbon lability and stable isotope shifts during microbial decomposition in a tropical river systemN. Geeraert0F. O. Omengo1G. Govers2S. Bouillon3KU Leuven, Department of Earth and Environmental Sciences, Leuven, BelgiumKU Leuven, Department of Earth and Environmental Sciences, Leuven, BelgiumKU Leuven, Department of Earth and Environmental Sciences, Leuven, BelgiumKU Leuven, Department of Earth and Environmental Sciences, Leuven, BelgiumA significant amount of carbon is transported to the ocean as dissolved organic carbon (DOC) in rivers. During transport, it can be transformed through microbial consumption and photochemical oxidation. In dark incubation experiments with water from the Tana River, Kenya, we examined the consumption of DOC through microbial decomposition and the associated change in its carbon stable isotope composition (<i>δ</i><sup>13</sup>C). In 15 of the 18 incubations, DOC concentrations decreased significantly by 10 to 60 %, with most of the decomposition taking place within the first 24–48 h. After 8 days, the remaining DOC was up to 3 ‰ more depleted in <sup>13</sup>C compared with the initial pool, and the change in <i>δ</i><sup>13</sup>C correlated strongly with the fraction of DOC remaining. We hypothesize that the shift in <i>δ</i><sup>13</sup>C is consistent with greater microbial lability of DOC originating from herbaceous C<sub>4</sub> vegetation than DOC derived from woody C<sub>3</sub> vegetation in the semi-arid lower Tana. The results complement earlier findings that the stable isotope concentration of riverine DOC does not necessarily reflect the proportion of C<sub>3</sub> and C<sub>4</sub>-derived DOC in the catchment: besides spatial distribution patterns of different vegetation types, processing within the river can further influence the <i>δ</i><sup>13</sup>C of riverine OC.http://www.biogeosciences.net/13/517/2016/bg-13-517-2016.pdf |
| spellingShingle | N. Geeraert F. O. Omengo G. Govers S. Bouillon Dissolved organic carbon lability and stable isotope shifts during microbial decomposition in a tropical river system Biogeosciences |
| title | Dissolved organic carbon lability and stable isotope shifts during microbial decomposition in a tropical river system |
| title_full | Dissolved organic carbon lability and stable isotope shifts during microbial decomposition in a tropical river system |
| title_fullStr | Dissolved organic carbon lability and stable isotope shifts during microbial decomposition in a tropical river system |
| title_full_unstemmed | Dissolved organic carbon lability and stable isotope shifts during microbial decomposition in a tropical river system |
| title_short | Dissolved organic carbon lability and stable isotope shifts during microbial decomposition in a tropical river system |
| title_sort | dissolved organic carbon lability and stable isotope shifts during microbial decomposition in a tropical river system |
| url | http://www.biogeosciences.net/13/517/2016/bg-13-517-2016.pdf |
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