Characteristics of seasonal variation and water-lifting aerator improvement of water quality in a steady stratified reservoir

Abstract

为了解深水型水库水体的热分层结构、水质特征及扬水曝气系统对水质的改善情况,对水温、溶解氧、pH、叶绿素a、营养盐、溶解性有机碳浓度等水质指标进行为期一年的监测,探讨各项指标的季节性变化规律.结果表明,黑河水库水体呈单循环混合模式,在3-10月形成自然热分层,水体的热分层导致相应水库水质明显分层.黑河水库为偏碱性水体,叶绿素a、总磷、总氮、铵态氮和溶解性有机碳浓度平均值分别为2.21 μg/L、0.022 mg/L、1.32 mg/L、0.20 mg/L和2.93 mg/L,表明黑河水库处于中-富营养状态.热分层期底部水体溶解氧浓度在0～7.9 mg/L之间,平均值为2.9 mg/L,氮磷质量比在41～100之间,表明黑河水库是一个底部季节性缺氧、高营养盐型水库.在水库自然热分层末期,应用扬水曝气技术,不仅改善了底部水体的厌氧/缺氧环境,抑制了厌氧/缺氧条件下内源污染物的释放和藻类的增殖,而且还使得水库水体提前混合,实现了强制混合与水体自然混合过程的有机衔接,延长了水质持续改善的作用时效,有效地改善了水环境,保障了安全供水.;In order to understand the thermal stratification, the characteristics of the water quality and the application of water-lifting aerator system in the deep reservoir, water temperature, dissolved oxygen, pH, chlorophyll-a, nutrient and dissolved organic carbon(DOC) were monitored in a whole year. The results showed that Heihe Reservoir belonged to single hybrid mode, and the natural thermal stratification period was from March to October. The thermal stratification led water quality stratifications. The chlorophyll-a, total phosphorus, total nitrogen, ammonium nitrogen and DOC average concentrations were 2.21 μg/L, 0.022 mg/L, 1.32 mg/L, 0.20 mg/L and 2.93 mg/L, respectively, which showed that Heihe Reservoir was mesotrophic. In the thermal stratification period, the dissolved oxygen in the underlying water ranged from 0 mg/L to 7.9 mg/L, with an average of 2.9 mg/L, and the ratio of N/P was between 41 and 100, which showed that Heihe Reservoir had a seasonal hypoxia, with high nutrient concentrations. In the end of natural thermal stratification period, the application of water-lifting aerator technology can not only improve the bottom anaerobic/anoxic environment, and reduce the release of endogenous pollutants and the proliferation of algae, but also enhance the water mixture.