[Nutrient Exchange Between Meixi River and Yangtze River Due to the Typical Interaction Process of the Three Gorges Reservoir and Its Tributary].

Frequent algal blooms have been observed in the Meixi bay of the Three Gorges Reservoirs (TGR) since its initial filling. In order to understand the effects of intrusions from Changjiang mainstream on the nutrient supply of the Meixi Bay, a detailed field monitoring was conducted from August 2012 to July 2013. The results showed that there were significant intrusions from the mainstream to the Meixi Bay during the different water level scheduling periods of the TGR. As a result, the invading flow from the mainstream of the Changjiang caused a significant effect on the nutrient distribution in the Meixi River. Annually, the mainstream transportednet fluxes of 5 478.02 t DIN, 234.04 t DIP and 5 935.22 t DSi to the Meixi Bay, which were 2.37 times, 4.32 times and 1.33 times of the corresponding fluxes from the upstream, respectively. The influence on the nutrient distributions was not only limited in the estuary area but also in the upper reaches, the supply of DIP changed the nutrient structure and relieved the P restrictions on phytoplankton growth.

[Partial pressure and diffusion flux of dissolved carbon dioxide in the mainstream and tributary of the central Three Gorges Reservoir in summer].

This study investigated the partial pressure of CO2 (pCO2) in the mainstream of the Three Gorges Reservoir and its tributary (Meixi River) in May 2013. Results showed that pCO2 in the surface water of the Meixi River and mainstream of the Three Gorges Reservoir was 6.8-7.5 Pa and 201.4-210.2 Pa, respectively. At the mixing area between the Meixi River and the mainstream of Changjiang, the lowest value of pCO2 in surface water was 53.5 Pa, and pCO2 gradually increased downwardly. Below 3 m in depth, pCO2 kept the stable value of around 210 Pa. Based on the calculation results, the emission flux of CO2 in the Meixi River and the mainstream of the central Three Gorges Reservoir was about -7.48 mmol x (m2 x d)(-1) and 39.58 mmol x (m2 x d)(-1), respectively. These results showed that the Meixi River is a sink for atmospheric CO2, and the mainstream of the Three Gorges Reservoir is a source for atmospheric CO2.