Potential effect of upstream sediment trap by a dam on dissolved organic matter transported into the Three Gorges Reservoir, China

• Published in: Journal of physics. Conference series Vol. 1735; no. 1; pp. 12001 - 12010
• Main Authors: Cao, Zhijing, Bao, Yuhai, Chen, Xiaoqing, Zhang, Xinbao
• Format: Journal Article
• Language: English
• Published: IOP Publishing 01.01.2021
• ISSN: 1742-6588; 1742-6596
• DOI: 10.1088/1742-6596/1735/1/012001

This paper demonstrates how suspended sediment trapped by dam construction may impact the quantity of dissolved organic matter (DOM) exported discharge entering the Three Gorges Reservoir (TGR). Suspended sediment and water samples were collected along the upper Yangtze River and its major tributaries, and their water and sediment properties determined. The results provided evidence of the more organic polluted nature of the tributaries compared to the upper mainstream Yangtze River. However, the measured DOM concentration in the waters within the TGR downstream from the tributary confluence, was 14% - 25% lower than that estimated just from mixing runoff. In contrast, the measured contents of particulate organic matter (POM) along the main Yangtze River increased by around 20%, whilst the partitioning coefficient of organic matter between sediment and water peaked 2.99 × 103. The results indicated that the sediment from the upper Yangtze River possibly absorbed the DOM sourced from the tributaries with the organic contamination. The annual DOM load which equals the average concentration of DOM multiplied by exported runoff, entering the TGR has been predicted to increase by 15% - 23% during the operation period of an another dam named after Xiluodu constructed upstream from the TGR.