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General Session 2: Marine & estuarine biogeochemistry |
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CO2 dynamics in the Dongsha Atoll, northern South China Sea
Tuesday 10th @ 1545-1605
Conference Hall
Wen-Chen Chou* , National Taiwan Ocean University
Ting-Chih Liu, National Taiwan Ocean University
Keryea Soong, National Sun Yat-sen Univerisity
Presenter Email: wcchou@mail.ntou.edu.tw
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| In this study, the carbonate parameters around the Dongsha Atoll (DA), including dissolved inorganic carbon (DIC), total alkalinity (TA), pH, partial pressure of CO2, and saturation state of aragonite, were thoroughly investigated in June (summer) and December (winter) 2013. The results show that the seagrass-dominated areas, including the small lagoon of the Dongsha Island (DI), and the north and west coast of the DI, were sinks of atmospheric CO2 in both summer and winter. On the contrary, the coral reef-dominated area, i.e. the DA lagoon, was a source of atmospheric CO2. The contrasting behaviors in CO2 dynamics can be attributed to the heterogeneity of community metabolism: in the seagrass-dominated area, photosynthesis and carbonate dissolution are the controlling metabolic processes, which can consume DIC and release TA, and thereby turning the DI lagoon to be a sink of atmospheric CO2; meanwhile in the coral reef-dominated area, respiration and calcification are the predominant metabolic processes, which can release DIC and consume TA, and thereby making the DA lagoon being a source of atmospheric CO2. Additionally, the dominance of photosynthesis and carbonate dissolution in the seagrass-dominated area can also result in the augmentation of pH and saturation level of aragonite of seawater, which is thought to be favorable for the calcification of coral reef, and thus could be beneficial for the DA to cope with ocean acidification. |
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