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首页> 外文期刊>Continental Shelf Research: A Companion Journal to Deep-Sea Research and Progress in Oceanography >Riverine input and air-sea CO2 exchanges near the Changjiang (Yangtze River) Estuary: Status quo and implication on possible future changes in metabolic status
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Riverine input and air-sea CO2 exchanges near the Changjiang (Yangtze River) Estuary: Status quo and implication on possible future changes in metabolic status

机译：长江口附近的河流输入和海-海CO2交换：新陈代谢状态的现状及其对未来可能变化的启示

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Due to anthropogenic activities, the nutrient loadings of the Changjiang (Yangtze River) are strickly on the rise. The high nutrient concentrations notwithstanding, river water was pCO(2) supersaturated in the inner estuary during summer 2003 but decreased quickly in the mid-estuary due to mixing with low pCO(2) waters from offshore. In addition, settling of particles in the estuary resulted in better light conditions so that phytoplankton bloomed, driving down pCO(2) to similar to 200 mu atm. In the outer estuary and outside of the bloom area, pCO(2) increased again to near or just below saturation. Literature data also reveal that the mainstream of the Changjiang is always supersaturated with respect to CO2 probably because the decomposition of terrestrial organic matter overwhelms the consumption of CO2 due to biological production. Because the Changjiang outflow accounts for 90% of the total river flow to the East China Sea (ECS), any variation in the Changjiang could have significant implications for the ECS. For instance, completion of the Three Gorge's Dam could change the metabolic status of the estuary by cutting off 70% of the downstream transport of organic carbon-containing particles. This would reduce the extent of organic carbon decomposition, producing better light conditions and enhancing autotrophy. As a result, the estuary could become a smaller source of CO2 to the atmosphere. On the other hand, if the Three Gorge's Dam reduced freshwater output, especially in summer, upwelling of nutrient-rich offshore waters would be reduced resulting in a reduction in autotrophy in the much wider ECS shelves. This effect could outweigh the reduced heterotrophy in the estuary and the ECS as a whole could become a smaller Co-2 sink. (c) 2008 Elsevier Ltd. All rights reserved.
机译：由于人为活动，长江（长江）的养分含量急剧上升。尽管养分浓度很高，但2003年夏季河口内河口的pCO（2）过饱和，但由于与近海低pCO（2）水混合，河口中部的pCO（2）迅速减少。此外，河口中的颗粒沉降导致更好的光照条件，使浮游植物开花，将pCO（2）压低至类似于200微米大气压。在河口外和开花区域外，pCO（2）再次增加到接近或刚好低于饱和度。文献数据还表明，长江的主流相对于CO2总是过饱和的，这可能是由于生物生产导致陆地有机物的分解压倒了CO2的消耗。由于长江流出量占流入东海（ECS）的总河流流量的90％，因此长江中的任何变化都可能对ECS产生重大影响。例如，三峡大坝的建成可能会切断下游70％的有机含碳颗粒，从而改变河口的代谢状态。这将减少有机碳的分解程度，产生更好的光照条件并增强自养能力。结果，河口可能成为大气中二氧化碳的较小来源。另一方面，如果三峡大坝减少了淡水输出，尤其是在夏天，则营养丰富的近海水的上升流将减少，从而导致更广泛的ECS架上的自养减少。这种影响可能会超过河口减少的异养性，整个ECS可能会变成一个较小的Co-2水槽。 （c）2008 Elsevier Ltd.保留所有权利。

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