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以西安市金盆水库为对象,通过对水温、水化学及水生生物因子的连续监测,初步探明其动态水体分层过程与季节性水质迁移分布的内在相关性。研究表明:水库于每年3—12月间形成并保持热分层状态,水温梯度的稳定存在有效限制了垂向水层间氧的传质交换,加速库底向厌氧状态过渡,滞水层溶解氧(DO)平均浓度随时间呈明显线性衰减趋势,水层呼吸速率高达0.0356～0.0372mg/(L·d)(O_2);缺氧/厌氧环境下,沉积物中N、P、Fe等大量释放并向上覆水扩散,底层水质污染加剧。同温混合期后(1—2月),分层结构破坏,全库处于好氧(DO大于8mg/L)、微碱性(pH为7.1～7.3)状态,垂向水质分层异质特征消失。监测期间,水库湖泊区稳态叶绿素a含量(基于Lois Elle稳态假设前提)随混合深度增大而降低,两者存在显著指数负相关。热分层效应的稳定存在是加速金盆水库富营养化进程的重要因素;而其周期性结构失稳所带来的水质突发性污染风险将伴随水库运行时间的延长而上升。
Based on the continuous monitoring of water temperature, water chemistry and aquatic biological factors, the Jinpen Reservoir in Xi’an City is initially investigated to find out the inherent correlation between the dynamic stratification process and the seasonal distribution of water quality. The results show that the reservoirs are formed and kept hot stratification from March to December each year. The steady existence of water temperature gradient effectively limits the mass transfer of oxygen between vertical aquifers and accelerates the transition from the bottom to the anaerobic state. The aquifer The average concentration of dissolved oxygen (DO) decreased linearly with time, and the respiratory rate of water layer was as high as 0.0356-0.0372 mg / (L · d) (O 2). Under hypoxia / anaerobic conditions, the concentrations of N, P, Fe A large number of release and spread to the water, the underlying water pollution intensified. After stratified mixing (January-February), the layered structure was destroyed, and the whole reservoir was in a state of aerobic (DO> 8mg / L) and slightly alkaline (pH = 7.1-7.3) disappear. During the monitoring period, the steady-state chlorophyll-a content in reservoirs and lakes (based on Lois Elle’s assumption of steady-state assumptions) decreased as the mixing depth increased, both of which had a significant exponential negative correlation. Stable existence of thermal stratification is an important factor in accelerating the eutrophication process of Jinpen Reservoir. The risk of sudden water pollution caused by its periodic structural instability will increase with the extension of reservoir operation time.