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Titel |
Revisiting the CO2 "source" problem in upwelling areas – a comparative study on eddy upwellings in the South China Sea |
VerfasserIn |
N. Jiao, Y. Zhang, K. Zhou, Q. Li, M. Dai, J. Liu, J. Guo, B. Huang |
Medientyp |
Artikel
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Sprache |
Englisch
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ISSN |
1726-4170
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Digitales Dokument |
URL |
Erschienen |
In: Biogeosciences ; 11, no. 9 ; Nr. 11, no. 9 (2014-05-06), S.2465-2475 |
Datensatznummer |
250117394
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Publikation (Nr.) |
copernicus.org/bg-11-2465-2014.pdf |
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Zusammenfassung |
The causes for a productive upwelling region to be a source of CO2 are
usually referred to the excess CO2 supplied via
upwelling of high dissolved inorganic carbon (DIC) from deep water. Furthermore, we hypothesize that microbial
activity plays a significant role on top of that. To test this hypothesis, multiple
biogeochemical parameters were investigated at two cyclonic-eddy-induced
upwelling sites, CE1 and CE2, in the western South China Sea. The data showed
that upwelling can exert significant influences on biological activities in
the euphotic zone and can also impact on particulate organic
carbon (POC) export flux depending on upwelling conditions, such as the
magnitude, timing, and duration of nutrient input and consequent microbial
activities. At CE2, the increase of phytoplankton biomass caused by the
upwelled nutrients resulted in increase of POC export flux compared to
non-eddy reference sites, while at CE1 the microbial respiration of organic
carbon stimulated by the upwelled nutrients significantly contributed to the
attenuation of POC export flux. These results suggest that on top of
upwelled DIC, microbial activities stimulated by
upwelled nutrients and labile organic carbon produced by phytoplankton can play a
critical role for an upwelling area to be outgassing or uptaking CO2.
We point out that even though an upwelling region is outgassing CO2, carbon
sequestration still takes place through the POC-based biological pump as
well as the refractory dissolved organic carbon (RDOC)-based microbial
carbon pump. |
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