Article (Scientific journals)
Dynamics of dissolved inorganic carbon and aquatic metabolism in the Tana River basin, Kenya
Tamooh, F.; Borges, Alberto; Meysman, F. J. R. et al.
2013In Biogeosciences, 10 (11), p. 6911-6928
Peer Reviewed verified by ORBi
 

Files


Full Text
tamooh_et_al_2013b.pdf
Publisher postprint (10.21 MB)
Download
Annexes
bg-10-6911-2013-supplement.pdf
Publisher postprint (444.21 kB)
data base
Download

All documents in ORBi are protected by a user license.

Send to



Details



Abstract :
[en] A basin-wide study was conducted in the Tana River basin (Kenya) in February 2008 (dry season), September–November 2009 (wet season) and June– July 2010 (end of the wet season) to assess the dynamics and sources of dissolved inorganic carbon (DIC) as well as to quantify CO2 fluxes, community respiration (R), and primary production (P). Samples were collected along the altitudinal gradient (from 3600 to 8 m) in several headwater streams, reservoirs (Kamburu and Masinga), and the Tana River mainstream. DIC concentrations ranged from 0.2 to 4.8 mmol L−1, with exceptionally high values (3.5±1.6 mmol L−1) in Nyambene Hills tributaries. The wide range of 13CDIC values (−15.0 to −2.4 ‰) indicate variable sources of DIC, with headwater streams recording more positive signatures compared to the Tana River mainstream. With with only a few exceptions, the entire riverine network was supersaturated in CO2, implying the system is a net source of CO2 to the atmosphere. pCO2 values were generally higher in the lower Tana River mainstream compared to headwater tributaries, opposite to the pattern typically observed in other river networks. This was attributed to high suspended sediment in the Tana River mainstream fuelling in-stream community respiration and net heterotrophy. This was particularly evident during the 2009 wet season campaign (median pCO2 of 1432 ppm) compared to the 2010 end of the wet season (1002 ppm) and 2008 dry season(579 ppm). First-order estimates show that in-stream community respiration was responsible for the bulk of total CO2 evasion (77 to 114 %) in the Tana River mainstream, while in the tributaries, this could only account for 5 to 68% of total CO2 evasion. This suggests that CO2 evasion in the tributaries was to a substantial degree sustained by benthic mineralisation and/or lateral inputs of CO2-oversaturated groundwater. While sediment loads increased downstream and thus light availability decreased in the water column, both chlorophyll a (0.2 to 9.6 μg L−1) and primary production (0.004 to 7.38 μmol CL−1 h−1) increased consistently downstream. Diurnal fluctuations of biogeochemical processes were examined at three different sites along the river continuum (headwater, reservoir and mainstream), and were found to be substantial only in the headwater stream, moderate in the reservoir and not detectable in the Tana River mainstream. The pronounced diurnal fluctuations observed in the headwater stream were largely regulated by periphyton as deduced from the low chlorophyll a in the water column.
Disciplines :
Aquatic sciences & oceanology
Author, co-author :
Tamooh, F.
Borges, Alberto  ;  Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Unité d'Océanographie chimique (UOC)
Meysman, F. J. R.
Van Den Meersche, K.
Dehairs, F.
Merckx, R.
Bouillon, S.
Language :
English
Title :
Dynamics of dissolved inorganic carbon and aquatic metabolism in the Tana River basin, Kenya
Publication date :
2013
Journal title :
Biogeosciences
ISSN :
1726-4170
eISSN :
1726-4189
Publisher :
European Geosciences Union (EGU), Germany
Volume :
10
Issue :
11
Pages :
6911-6928
Peer reviewed :
Peer Reviewed verified by ORBi
European Projects :
FP7 - 240002 - AFRIVAL - African river basins: catchment-scale carbon fluxes and transformations.
Name of the research project :
AFRIVAL
Funders :
CE - Commission Européenne [BE]
Available on ORBi :
since 04 November 2013

Statistics


Number of views
58 (10 by ULiège)
Number of downloads
146 (1 by ULiège)

Scopus citations®
 
34
Scopus citations®
without self-citations
25
OpenCitations
 
31

Bibliography


Similar publications



Contact ORBi