Photomineralization of organic carbon in a eutrophic, semiarid estuary

Date

2020-01-28

Authors

Wang, Hongjie
Hu, Xinping
Wetz, Michael S.
Hayes, Kenneth C.
Lu, Kaijun

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Wiley Periodicals, Inc.

Abstract

The effect of photomineralization on the carbon cycle in a eutrophic, semiarid estuary (Baffin Bay, Texas) was investigated using closed-system incubations. Photochemical production rate of dissolved inorganic carbon ranged from 0.16 to 0.68 μM hr−1, with a daily removal of 0.3∼1.5% of the standing stock of dissolved organic carbon (DOC). The photomineralization rate was negatively correlated with chlorophyll a concentration, suggesting that plankton-derived DOC was less photoreactive to solar radiation. The stable carbon isotope composition (δ13C∼ −18.6‰) of degraded DOC, as calculated using the DIC “Keeling” plot, further indicated high photochemical lability of 13C-enriched DOC in this semiarid environment. Our finding showed that photomineralization of 13C-enriched DOC is an important component of carbon cycle in this system, and this process does not necessarily remove 13C-depleted organic carbon as observed in other coastal systems.

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Citation

Wang, H., X. Hu, M.S. Wetz, K.C. Hayes, and K. Lu. 2020. Photomineralization of organic carbon in a eutrophic, semiarid estuary. Limnology and Oceanography Letters 5: 246-253

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