海湾水库沉积物对水体咸化影响的时间尺度

为预测海湾水库沉积物盐分释放对库水咸化影响的持续时间,建立了描述沉积物孔隙水盐分剖面分布的非稳态数学模型,并优化选取模型的边界条件与关键参数(沉积物孔隙水盐分的扩散系数)。稳态与非稳态条件下沉积物盐分释放的对比分析表明,在计算污染沉积物对其上覆水水质的影响时间时,按非稳态释放更符合实际情况。非稳态盐分释放的计算结果表明,拟建沐官岛海湾水库沉积物中盐分释放对库水咸化的影响时间将大于600年,该影响时间远长于水库的寿命;表明在水库的整个生命周期内,均需要定期监测海湾水库底层水的盐分浓度,并需采取有效措施预防水体的突然泛咸,而不能仅在建库初期关注咸化问题。

Time scale for effects of sediment on water salinization of estuary reservoirs

To predict the time scale for the effects of salt release from sediments on estuary reservoir water, a transient diffusional model was developed to describe the profile of salts in the pore water of sediments. The upper boundary condition and the salt diffusion coefficient of this model were optimized to decrease the uncertainty of the simulation results. A comparison of the transient and steady state release of salts from sediments shows that transient release agrees well with the actual process. The result of a transient simulation for salt release illustrates that it takes more than 600 years for saline sediments to affect the fresh overlying water in the Muguandao Estuary Reservoir. This duration is significantly longer than the life span of a reservoir. The result suggests that instead of measures being taken only at the early stage of an estuary reservoir, effective measures such as periodic monitoring of benthic water and discharging of benthic brackish water should be implemented to prevent salinization throughout its life cycle.