微囊藻属一日内垂向分布的数值模拟  

Modelling daily variation in the vertical distribution of Microcystis

作　　者：俞茜[1] 刘昭伟[1] 陈永灿[1] 朱德军[1] 

机构地区：[1]清华大学,水沙科学与水利水电工程国家重点实验室,北京100084

出　　处：《中国环境科学》2015年第6期1840-1846,共7页China Environmental Science

基　　金：国家自然科学基金资助项目(51039002);教育部新世纪优秀人才支持计划(NCET-12-0309);教育部创新团队发展计划(IRT13025)

摘　　要：将水质模型与微囊藻属浮力调节模型相结合,建立微囊藻属垂向浓度分布模型,该模型不仅保留了以往模型的优点且改进了以往模型的不足,如考虑了微囊藻群体的直径大小及微囊藻属的浮力调节能力.模型结果与荷兰的Vinkeveen湖的实际测量数据吻合良好.此外,模拟结果也表明：微囊藻属在垂向的分布受水体紊动程度影响显著.微囊藻群体的最大浓度并不在水体表面,而是在水下一定深度处.小尺寸群体微囊藻群体（20～50μm）在水深方向的分布比大尺寸群体（100～200μm）更加均匀.日落后,微囊藻属会因为密度减小上浮至水面,反之,白日里,微囊藻属密度增加向水底方向下沉,因此日出前水面的微囊藻属浓度高于日落前的水面浓度.By coupling advection-diffusion equation and buoyancy regulation, a coupled model for simulating diurnal changes of vertical concentration distribution of Microcystis was developed. Different from existing models, the present model incorporated the buoyancy regulation of the Microcystis colonies with different diameters. The numerical simulations showed a good agreement with the field data acquired in Lake Vinkeveen, the Netherlands. It was found that the highest concentration showed up below rather than on the water surface and turbulent diffusion had a significant impact on the vertical distribution. The colonies with smaller sizes （20-50~m in diameter） distributed more uniformly than those with larger sizes （100-200~rn in diameter）. The densities of colonies decreased in the evening, and thus Microcystis float upwards. However, the densities increased and the Microcystis sank in the daytime. Hence, the surface concentration of the Microcystis reached the highest value at the sunrise and reached the lowest value at the sunset.

关 键 词：微囊藻属 垂向分布 浮力调节 移流传输方程 数值模拟 日变化 

分 类 号：X703.5[环境科学与工程—环境工程]