pstrongAbstract./strong Carbon transport in river systems is an important component of the global carbon cycle. Most rivers of the world act as atmospheric COsub2/sub sources due to high riverine COsub2/sub partial pressure (ip/iCOsub2/sub). By determining the ip/iCOsub2/sub from alkalinity and pH, we investigated its spatial and temporal variation in the Yellow River watershed using historical water chemistry records (1950sa??1984) and recent sampling along the mainstem (2011a??2012). Except the headwater region where the ip/iCOsub2/sub was lower than the atmospheric equilibrium (i.e. 380 ??atm), river waters in the remaining watershed were supersaturated with COsub2/sub. The average ip/iCOsub2/sub for the watershed was estimated at 2810 ?± 1985 ??atm, which is 7-fold the atmospheric equilibrium. As a result of severe soil erosion and dry climate, waters from the Loess Plateau in the middle reaches had higher ip/iCOsub2/sub than that from the upper and lower reaches. From a seasonal perspective, the ip/iCOsub2/sub varied from about 200 ??atm to 30 000 ??atm with higher ip/iCOsub2/sub usually occurring in the dry season and lower ip/iCOsub2/sub in the wet season (at 73% of the sampling sites), suggesting the dilution effect of water. While the ip/iCOsub2/sub responded exponentially to total suspended solids (TSS) export when the TSS concentration was less than 100 kg msupa??3/sup, it decreased slightly and remained stable if the TSS concentration exceeded 100 kg msupa??3/sup. This stable ip/iCOsub2/sub is largely due to gully erosion that mobilizes subsoils characterized by low organic carbon for decomposition. In addition, human activities have changed the ip/iCOsub2/sub dynamics. Particularly, flow regulation by dams can diversely affect the temporal changes of ip/iCOsub2/sub, depending on the physiochemical properties of the regulated waters and adopted operation scheme. Given the high ip/iCOsub2/sub in the Yellow River waters, large potential for COsub2/sub evasion is expected and warrants further investigation./p.
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机译：> >摘要。河流系统中的碳迁移是全球碳循环的重要组成部分。由于河流中的CO 2 分压高（ p CO 2 >）。通过确定碱度和pH值中的 p CO 2 ，我们利用历史水化学记录（1950年至1984年）以及最近的水化学记录，研究了其在黄河流域的时空变化。沿主干采样（2011a ?? 2012）。除了 p CO 2 的源头区域低于大气平衡（即380 atm）之外，其余流域中的河水都被CO 过饱和。 2 。流域的平均 p CO 2 估计为2810？±1985 atm，是大气平衡的7倍。由于严重的水土流失和干旱的气候，中游黄土高原地区的水 p CO 2 高于上下游。从季节的角度来看， p CO 2 从大约200 atm到> 30 000 atm，而更高的 p CO 2 通常出现在干燥季节，而 p CO 2 发生在潮湿季节（在73％的采样点）较低，表明对水。当TSS浓度低于100 kg m a ?? 3 时， p CO 2 对总悬浮固体（TSS）出口呈指数响应。如果TSS浓度超过100 kg m a ?? 3 ，则略有下降并保持稳定。这种稳定的 p CO 2 很大程度上是由于沟壑侵蚀而动员了以有机碳含量低为特征的地下土壤进行分解。此外，人类活动改变了 p CO 2 动力学。特别是，大坝的水流调节可以根据调节水的理化特性和采用的运行方案，对 p CO 2 的时间变化产生不同的影响。鉴于黄河水域中的 p CO 2 较高，预计有很大的CO 2 规避潜力，因此有待进一步研究。 。
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