Journal of Geographical Sciences ›› 2017, Vol. 27 ›› Issue (6): 697-710.doi: 10.1007/s11442-017-1401-9

• Orginal Article • Previous Articles     Next Articles

Simulation on phosphorus release characteristics of Poyang Lake sediments under variable water levels and velocities

Yali TONG(), Tao LIANG*, Lingqing WANG(), *   

  1. Key Laboratory of Land Surface Pattern and Simulation, Institute of Geographic Sciences and Natural Resources Research, CAS, Beijing 100101, China
  • Received:2016-06-15 Accepted:2016-08-20 Online:2017-06-10 Published:2017-06-10
  • Contact: Tao LIANG, E-mail:tongyali123@163.com;wanglq@igsnrr.ac.cn; Li Kexin, likx@igsnrr.ac.cn
  • About author:

    Author: Tong Yali, MS, specialized environmental geography. E-mail: tongyali123@163.com

    *Corresponding author: Wang Lingqing, E-mail: wanglq@igsnrr.ac.cn; Li Kexin, likx@igsnrr.ac.cn

  • Supported by:
    National Key Project for Basic Research, No.2012CB417004

Abstract:

Since the construction of the Three Gorges Dam, the Poyang Lake hydrological characteristics obviously changed. During the impoundment period of the Three Gorges Reservoir, the hydrodynamic factors of Poyang Lake varied. Water level dropped, the velocity decreased and water exchange time lengthened, which changed the release of phosphorous from sediments. In order to investigate how the hydrodynamic factors influence the release of phosphorous from sediments, we used a two-way annular flume device to simulate the release characteristics of phosphorous from sediments under variable water levels and velocities. We found that both water level rising and velocity increasing could enhance the disturbance intensity to sediments, which caused the increase of suspended solids (SS) concentration, total phosphorus (TP) concentration in the overlying water, and the ability that phosphorus released to overlying water from sediments enhanced as well: when overlying water velocity maintained 0.3 m/s, SS concentration increased to 4035.85 mg/L at the water level 25 cm which was about 25 times compared to the minimum value and TP concentration in the overlying water also reached the maximum value at the water level 25 cm which was 1.2 times that of the value at 10 cm; when water level maintained 15 cm, SS concentration increased to 4363.35 mg/L at the velocity of 0.5 m/s which was about 28 times compared to the value of 0 m/s, and TP concentration in the overlying water increased from 0.11 mg/L to 0.44 mg/L. When the water level maintained 15 cm, the phosphorous release rate reached the maximum value of 4.86 mg/(md) at 0.4 m/s. The concentration of total dissolved phosphorous (TDP) and soluble reactive phosphate (SRP) both in overlying water and sediment-water interface were negatively correlated with pH. Using the parabolic equation, the optimum water level at a velocity of 0.3 m/s was calculated to be 0.57 cm, and the optimum velocity at water level of 15 cm was found to be 0.2 m/s.

Key words: hydrodynamic factors, sediment-water interface, total phosphorous, total dissolved phosphorous, soluble reactive phosphate, Poyang Lake