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Marine Carbon Sequestration (MARCO): Multiscale Regulation and Response to Global Change
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Assessment of primary production in the South China Sea: A comparison of fast repetition rate fluorometry and 14C measurement
P-SPS5-05-S
Lei Yang* , State Key Laboratory of Marine Environmental Science(Xiamen University)
Yuyuan Xie, State Key Laboratory of Marine Environmental Science(Xiamen University)
Haoran Liu, State Key Laboratory of Marine Environmental Science(Xiamen University)
Bangqin Huang, State Key Laboratory of Marine Environmental Science(Xiamen University)
Presenter Email: lyang@stu.xmu.edu.cn |
| Phytoplankton primary productivity is most commonly measured by 14C assimilation, which is invasive, requiring bottle incubation for up to 24 h. However, as an alternative, FastOcean APD based on Fast Repetition Rate fluorometry (FRRf), can estimate photosystem II (PSII) electron transport rate (ETR) on wide temporal and spatial scales within aquatic systems, It is more labor-saving and needs short measurement time. Light energy absorbed by chlorophyll molecules can undergo three fates: photosynthesis (photochemistry), heat or light-chlorophyll fluorescence. In the photosynthetic system, linear electron flow begins with excitation of the photosynthetic reaction centers, PSII and PSI, and with splitting of water by the oxygen-evolving complex of PSII. Electrons are passed from PSII to the plastoquinone (PQ) pool and then to PSI, where NADPH is formed. However, the electrons emitted from water molecule in PSII is not all transported into carbon fixation in the dark reaction. And our work concentrates on studying the variability of ETR/CO2 uptake rate. The reported ratios of ETR/CO2 uptake rate range from 2.5 to 12 mol e-[mol CO2]-1, which is an approximately 5-fold range in the currency conversion rate, and the theoretical value of ETR/CO2 uptake rate is 4. Our studies show that it has much connection with the water parameter characterization. The range of ETR/CO2 uptake rate variation in oligotrophic ocean is much smaller, comparing with the eutrophic water. |
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