The release of phosphorus from sediment is an important source of endogenous phosphorus in water bodies and is an important factor affecting the total phosphorus content in river system. Water velocity is key factor affecting the rate of phosphorus release from sediments. In this paper, the effects of water velocity on the release of phosphorus from sediments in a plateau cold water type river were investigated. The ecological environment of plateau cold water rivers is sensitive and fragile. The changes in environmental conditions can easily lead to changes in the overall water quality of rivers. Therefore, exploring the release process of phosphorus in plateau cold water rivers under changes in hydrodynamic conditions is important for protecting the ecological environment of plateau rivers. The results showed that the release of total phosphorus from sediments followed a first-order kinetic process, when the flow velocity was lower than the threshold velocity of sediments. The total phosphorus release coefficient of sediment linearly increased with increases in water flow velocity. The total phosphorus release coefficient of sediment was related to the flow velocity by $k_{\mathrm{TP}\left(20\right)}=3.03v/v_c+0.08\left(v<v_c\right)$ at 20 °C. The release equilibrium concentration of total phosphorus from the sediment was increased with the increase of velocity. The relationship between the balance concentration of total phosphorus release and water velocity was expressed as $C_{s\left(20\right)}=0.10v/v_c+0.04\left(v<v_c\right)$ at 20 °C. The results could provide a quantitative basis for the source term expression of phosphorus release kinetics in the mathematical model of phosphorus transport in the plateau cold water type river.

沉积物磷的释放是水体内源磷的重要来源，是影响河流水系总磷含量的重要因素。水流速度是影响沉积物磷释放速率的关键因素。本文研究了高原冷水型河流中水流流速对沉积物磷释放的影响。高原冷水河流生态环境敏感脆弱。环境条件的变化很容易导致河流整体水质的变化。因此，探索水动力条件变化下高原冷水河流磷的释放过程对于保护高原河流生态环境具有重要意义。结果表明，当流速低于沉积物阈值速度时，沉积物中总磷的释放遵循一级动力学过程。沉积物总磷释放系数随水流速度的增加而线性增加。沉积物总磷释放系数与流速的关系为$k_{\mathrm{TP}\left(20\right)}=3.03v/v_C+0.08\left(v<v_C\right)$在20°C。沉积物中总磷的释放平衡浓度随着流速的增大而增大。总磷释放平衡浓度与水流速度的关系为$C_{s\left(20\right)}=0.10v/v_C+0.04\left(v<v_C\right)$在20°C。研究结果可为高原冷水型河流磷迁移数学模型中磷释放动力学的源项表达式提供定量依据。