New constraints on biological production and mixing processes in the South China Sea from triple isotope composition of dissolved oxygen
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Published:2022-04-14
Issue:7
Volume:19
Page:2043-2058
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ISSN:1726-4189
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Container-title:Biogeosciences
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language:en
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Short-container-title:Biogeosciences
Author:
Jurikova Hana, Abe Osamu, Shiah Fuh-Kwo, Liang Mao-ChangORCID
Abstract
Abstract. The South China Sea (SCS) is the world's largest marginal
sea, playing an important role in the regional biogeochemical cycling of
carbon and oxygen. However, its overall metabolic balance, primary
production rates and links to East Asian Monsoon forcing remain poorly
constrained. Here, we report seasonal variations in triple oxygen isotope
composition (17Δ) of dissolved O2, a tracer for biological
O2, gross primary production (GP; inferred from δ17O and
δ18O values) and net community production (NP; evaluated from
oxygen–argon ratios) from the SouthEast Asian Time-series Study (SEATS) in
the SCS. Our results suggest rather stable mixed-layer mean GP rates of
∼ 1500 ± 350 mg C m−2 d−1 and mean NP of
∼ −13 ± 20 mg C m−2 d−1 during the summer
southwest monsoon season. These values indicate, within uncertainties and
variabilities observed, that the metabolism of the system was in net
balance. During months influenced by the stronger northeast monsoon forcing,
the system appears to be more dynamic and with variable production rates,
which may shift the metabolism to net autotrophy (with NP rates up to
∼ 140 mg C m−2 d−1). Furthermore, our data from the
deeper regions show that the SCS circulation is strongly affected by monsoon
wind forcing, with a larger part of the water column down to at least 400 m
depth fully exchanged during a winter, suggesting the 17Δ of
deep O2 as a valuable novel tracer for probing mixing processes.
Altogether, our findings underscore the importance of monsoon intensity on
shifting the carbon balance in this warm oligotrophic sea and on driving
the regional circulation pattern.
Funder
Ministry of Science and Technology, Taiwan Academia Sinica
Publisher
Copernicus GmbH
Subject
Earth-Surface Processes,Ecology, Evolution, Behavior and Systematics
Reference89 articles.
1. Barkan, E. and Luz, B.: High-precision measurements of 17O/16O and
18O/16O of O2 and O2/Ar ratio in air, Rapid
Commun. Mass Sp., 17, 2809–2814, https://doi.org/10.1002/rcm.1267, 2003. 2. Benson, B. B. and Krause Jr., D. K.: The concentration and isotopic
fractionation of oxygen dissolved in freshwater and seawater in equilibrium
with the atmosphere, Limnol. Oceanogr., 29, 620–632, https://doi.org/10.4319/lo.1984.29.3.0620, 1984. 3. Cai, W.-J. and Dai, M.: Comment on “Enhanced open ocean storage of CO2
from shelf sea pumping”, Science, 306, 1477, https://doi.org/10.1126/science.1102132, 2004. 4. Carr, M.-E., Friedrichs, M. A. M., Schmeltz, M., Aita, M. N., Antoine, D., Arrigo, K. R., Asanuma, I., Aumont, O., Barber, R., Behrenfeld, M., Bidigare, R., Buitenhuis, E. T., Campbell, J., Ciotti, A., Dierssen, H., Dowell, M., Dunne, J., Esaias, W., Gentili, B., Gregg, W., Groom, S., Hoepffner, N., Ishizaka, J., Kameda, T., Le Quéré, C., Lohrenz, S., Marra, J., Mélin, F., Moore, K., Morel, A., Reddy, T. E., Ryan, J., Scardi, M., Smyth, T., Turpie, K., Tilstone, G., Waters, K., and Yamanaka, Y.: A comparison of global estimates of marine primary
production from ocean color, Deep-Sea Res. Pt. II, 53, 741–770, https://doi.org/10.1016/j.dsr2.2006.01.028, 2006. 5. Castro-Morales, K. and Kaiser, J.: Using dissolved oxygen concentrations to determine mixed layer depths in the Bellingshausen Sea, Ocean Sci., 8, 1–10, https://doi.org/10.5194/os-8-1-2012, 2012.
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