Wang, HongjieHu, XinpingWetz, MichaelLu, KaijunWang, HongjieHu, XinpingWetz, MichaelLu, Kaijun2019-12-202019-12-202019-12-202019-12-202020-01-012020-01-012378-22422378-22422378-2242https://hdl.handle.net/1969.6/87603https://hdl.handle.net/1969.6/87603https://hdl.handle.net/1969.6/87603The 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 the chlorophyll a concentration, suggesting that the 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 that the high photochemical lability of 13C-enriched DOC in this semiarid environment. Our finding showed that the photomineralization of 13C-enriched DOC is an important component of the carbon cycle in this system, and this process does not necessarily remove 13C-depleted organic carbon as observed in other coastal areas.en-USAttribution 3.0 United Stateshttp://creativecommons.org/licenses/by/3.0/us/photomineralizationestuarystable carbon isotopedissolved organic carbonArticle