Photomineralization of organic carbon in a eutrophic, semiarid estuary

• Published in: Limnology and Oceanography Letters
• Main Authors: Wang, Hongjie, Hu, Xinping, Wetz, Michael S., Hayes, Kenneth C., Lu, Kaijun
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: Wiley Periodicals, Inc. 2020
• Subjects: Baffin Bay
• Online Access: https://hdl.handle.net/1969.6/89590; https://doi.org/10.1002/lol2.10146

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.