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CO2 supersaturation and net heterotrophy in a tropical estuary (Cochin, India): Influence of anthropogenic effect - Carbon dynamics in tropical estuary

DRS at CSIR-National Institute of Oceanography

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Title CO2 supersaturation and net heterotrophy in a tropical estuary (Cochin, India): Influence of anthropogenic effect - Carbon dynamics in tropical estuary
 
Creator Gupta, G.V.M.
Thottathil, S.D.
Balachandran, K.K.
Madhu, N.V.
Madeswaran, P.
Nair, S.
 
Subject organic carbon
anthropogenic factors
supersaturation
heterotrophy
 
Description Carbon biogeochemistry of a tropical ecosystem (The Cochin Estuary, India) undergoing increased human intervention was studied during February (premonsoon), April (early monsoon) and September (monsoon) 2005. The Cochin estuary sustains high levels of pCO sub(2) (up to 6000 mu atm) and CO sub(2) effluxes (up to 274 mmolC m sup(-2) d sup(-1)) especially during monsoon. A first-order estimate of the carbon mass balance shows that net production of dissolved inorganic carbon is an order of magnitude higher than the net loss of dissolved and particulate organic carbon from the estuary. This imbalance is attributed to the organic inputs to the estuary through anthropogenic supplies. The bacteria-mediated mineralization of organic matter is mainly responsible for the build-up of pCO sub(2) and increased CO sub(2) emission to the atmosphere indicating heterotrophy. The linear correlation between excess CO sub(2) and apparent oxygen utilization indicates respiration as the chief mechanism for CO sub(2) supersaturation. An increase in the net negative ecosystem production (–ve NEP) between premonsoon (-136 mmolC m sup(-2) d sup(-1) or -376 MgC d sup(-1) and monsoon (-541 mmolC m sup(-2) d sup(-1) or -1500 MgC d sup(-1)) is supported by a corresponding increase in O sub(2) influxes from 17 mmol O sub(2) m sup(-2) d sup(-1) (126 MgC d sup(-1)) to -128 mmol O sub(2) m sup(-2) d sup(-1) (-946 MgC d sup(-1)) and CO sub(2) emissions from 65 mmolC m sup(-2) d sup(-1) (180 MgC d sup(-1)) to 267 mmolC m sup(-2) d sup(-1) (740 MgC d sup(-1)). There is a significant north-south gradient in metabolic rates and CO sub(2) fluxes attributable to the varying flow patterns and anthropogenic inputs into the estuary. The study reveals that the Cochin estuary, a previously autotrophic (CO sub(2) sink) system, has been transformed to a heterotrophic (CO sub(2) source) system following rapid urbanization and industrialization. Moreover, the export fluxes from the Cochin estuary appear to be quite important in sustaining net heterotrophy in the southeastern Arabian Sea
 
Date 2009-12-08T07:00:20Z
2009-12-08T07:00:20Z
2009
 
Type Journal Article
 
Identifier Ecosystems, vol.12(12); 1145-1157
http://drs.nio.org/drs/handle/2264/3460
 
Language en
 
Rights An edited version of this paper was published by Springer. This paper is for R & D pupose and Copyright [2009] Springer.
 
Publisher Springer