中文摘要：

采用数值和理论相结合的方法,通过水藻扩散模型定量研究了沉降、扩散、生长、死亡、水深等因素对水藻生长状态的影响,提出初步判断水藻生长状态的判别标准. 针对以往研究中对于水藻生长率、垂向紊动扩散系数垂向均匀假设过于简化,与实际情况不符的问题,本文分别研究了考虑光照条件下、营养盐限制条件下以及垂向扩散系数非均匀条件下,对于水藻生长状态以及水藻暴发判别标准的影响,结果发现光照引起的＂遮蔽效应＂,营养盐的＂通量限制＂都会促使水藻由暴发或衰减状态向平衡状态发展. 垂向扩散系数的分布形态对水藻生长状态影响大小受l/H（真光层深度和水深比）的影响,只有当水深较大时,即l/H较小时,应考虑垂直扩散系数垂向分布不均的影响. 因此对于水深较小的宽浅湖泊,垂直扩散系数的形态变化对水藻生长状态的影响不明显.

英文摘要：

This study investigated the effect quantitatively on phytoplankton population by various factors such as sinking velocity, diffusivity, growth, mortality and water depth, through both numerically and theoretical methods, then proposed an initial judgment criterion for estimating phytoplankton population development. To the conventional simplification about even growth rate and vertical turbulent diffusivity, which is not consistent with the fact, this study investigated the influence by the asymmetric growth rate, as a result of light attenuation and nutrient limit, and uneven vertical turbulent diffusivity. It was shown that the ‘shade effect＇ by light attenuation and nutrient flux limit both led. phytoplankton population from blooming or collapsing to quasi-steady condition. The uneven vertical turbulent diffusivity influenced the phytoplankton population by l/H which is upper euphotic layer depth by water depth. The influence is not apparent only if the water depth is large enough while l/H is small. Hence even vertical turbulent diffusivity can be utilized approximately in very shallow lakes.