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Organic carbon transport and C/N ratio variations in a large tropical river: Godavari as a case study, India

Balakrishna, K. and Probst, Jean-Luc Organic carbon transport and C/N ratio variations in a large tropical river: Godavari as a case study, India. (2005) Biogeochemistry, vol. 7 (n° 3). pp. 457-473. ISSN 0168-2563

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Official URL: http://dx.doi.org/10.1007/s10533-004-0879-2

Abstract

This study gives an insight into the source of organic carbon and nitrogen in the Godavari river and its tributaries, the yield of organic carbon from the catchment, seasonal variability in their concentration and the ultimate flux of organic and inorganic carbon into the Bay of Bengal. Particulate organic carbon/particulate organic nitrogen (POC/PON or C/N) ratios revealed that the dominant source of organic matter in the high season is from the soil (C/N = 8–14), while in the rest of the seasons, the river-derived (in situ) phytoplankton is the major source (C/N = l–8). Amount of organic materials carried from the lower catchment and flood plains to the oceans during the high season are 3 to 91 times higher than in the moderate and low seasons. Large-scale erosion and deforestation in the catchment has led to higher net yield of organic carbon in the Godavari catchment when compared to other major world rivers. The total flux of POC, and dissolved inorganic carbon (DIC) from the Godavari river to the Bay of Bengal is estimated as 756 · 109 and 2520 · 109 g yr1, respectively. About 22% of POC is lost in the main channel because of oxidation of labile organic matter, entrapment of organic material behind dams/sedimentation along flood plains and river channel; the DIC fluxes as a function of alkalinity are conservative throughout the river channel. Finally, the C/N ratios (12) of the ultimate fluxes of particulate organic carbon suggest the dominance of refractory/ stable soil organic matter that could eventually get buried in the coastal sediments on a geological time scale.

Item Type:Article
Additional Information:Thanks to Springer editor. The definitive version is available at http://www.springerlink.com/home/main.mpx The original PDF of the article can be found at Biogeochemistry website : http://www.springerlink.com/content/100244
Audience (journal):International peer-reviewed journal
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Institution:French research institutions > Institut de Recherche pour le Développement - IRD
Université de Toulouse > Université Paul Sabatier-Toulouse III - UPS
French research institutions > Centre National de la Recherche Scientifique - CNRS
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Deposited By:Florence Amor

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