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.

中文翻译：

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富营养化的半干旱河口中有机碳的光矿化

使用封闭系统孵育研究了富矿化，半干旱河口（德克萨斯州巴芬湾）中光矿化对碳循环的影响。溶解的无机碳的光化学生产速率的范围为0.16至0.68  μ中号小时^-1，每日除去溶解的有机碳（DOC）的竖立股票的0.3〜1.5％。光矿化速率与叶绿素a浓度呈负相关，表明浮游生物来源的DOC对太阳辐射的光反应性较低。稳定的碳同位素组合物（δ ¹³ C~ -18.6‰）退化的DOC的，作为使用DIC“基林”图计算，还显示出高的光化学的不稳定性¹³在这种半干旱环境中富含C的DOC。我们的发现表明，富集¹³ C的DOC的光矿化是该系统中碳循环的重要组成部分，并且此过程未必像其他沿海系统中观察到的那样会去除¹³ C贫化的有机碳。