Coupling of surface pCO2 and dissolved oxygen in the northern South China Sea: Impacts of contrasting coastal processes
Coupling of surface pCO2 and dissolved oxygen in the northern South China Sea: Impacts of contrasting coastal processes
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DOI：
10.5194/bg-6-2589-2009
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发表时间：
2009-11
期刊：
影响因子：
4.9
通讯作者：
W. Zhai;M. Dai;W. Cai
中科院分区：
文献类型：
--
作者：
W. Zhai;M. Dai;W. Cai
抽象的。我们根据 2004 年 7 月在南海北部（东经 111°–118°，北纬 18°–23°）进行的一次巡航，研究了二氧化碳分压 (pCO2) 和溶解氧 (DO) 之间的关系，该巡航跨越了河口羽流、沿海上升流和深盆区域。在不同的情况下，pCO2 和 DO 饱和度之间存在明显的关系。在沿海上升流区和珠江口，同时观察到pCO2的生物下降和O2的产生。这两种特性主要通过光合作用和呼吸作用相互结合。然而，由于 Revelle 因子的值不同，这两种特性的化学计量关系在这两种环境中完全不同。在近海区域，除河口和上升流外，pCO2和DO的动态主要受水混合过程中海气交换的影响。鉴于O2的海气再平衡速度比CO2快得多，观测到的pCO2-DO关系与近海地区基于Redfield关系的理论预测存在偏差。尽管这项研究受到采样时间和空间覆盖范围的限制，但我们已经展示了一种基于高分辨率表面 pCO2 和 DO 测量相结合的评估群落代谢状态的简单程序，该程序可能适用于许多物理和生物地球化学条件变化梯度较大的沿海系统。
Abstract. We examined the relationship between CO2 partial pressure (pCO2) and dissolved oxygen (DO) based on a cruise conducted in July 2004 to the northern South China Sea (111°–118° E 18°–23° N), spanning from estuarine plume, coastal upwelling and deep basin areas. Distinct relationships between pCO2 and DO saturation were identified in different regimes. In coastal upwelling areas and the Pearl River estuary, biological drawdown of pCO2 and production of O2 were simultaneously observed. The two properties were coupled with each other primarily via photosynthesis and respiration. The stoichiometric relationship of the two properties however, was quite different in these two environments due to different values of the Revelle factor. In the offshore areas, apart from the estuary and upwelling, the dynamics of pCO2 and DO were mainly influenced by air-sea exchange during water mixing. Given the fact that air-sea re-equilibration of O2 is much faster than that of CO2, the observed pCO2-DO relationship deviated from that of the theoretical prediction based on the Redfield relationship in the offshore areas. Although this study is subject to the limited temporal and spatial coverage of sampling, we have demonstrated a simple procedure to evaluate the community metabolic status based on a combination of high-resolution surface pCO2 and DO measurements, which may have applicability in many coastal systems with a large gradient of changes in their physical and biogeochemical conditions.