大宁河水华敏感期浮游植物与环境因子关系

Exploration of Relationships Between Phytoplankton and Related Environmental Factors in the Daning River During Sensitive Period of Algal Blooms

以三峡支流大宁河水华敏感期(2008年4～5月)水环境状况的监测数据为基础,运用数理统计分析手段,对浮游植物的分布特征及其与环境因子的关系进行了讨论.结果表明,水温、总氮(TN)、硝酸盐氮(NO3–-N)、pH和溶解氧(DO)时空分布差异显著(ANOVA,p<0.05).浮游植物细胞密度时空分布差异显著(ANOVA,p<0.05),最高值出现在大昌样点,最低值出现在长江干流巫峡口样点;7个采样点藻细胞密度的最高值均出现在水华期,发生多藻种同时同地水华的情况.利用相关分析方法分析藻细胞密度与环境因子间的关系,表明藻细胞密度与TN呈显著负相关(r=-0.789,p<0.05);与NO3–-N呈显著负相关(r=-0.825,p<0.05);与NO2–-N呈显著负相关(r=-0.803,p<0.05);表明在调查期间N是影响浮游植物细胞密度的关键因子.利用冗余度分析(redundancy analysis,RDA)浮游植物种类组成与环境因子之间的关系,表明营养盐(TN、TP、NO3–-N和NO2–-N)、悬浮物和透明度是影响浮游植物组成的主要因素.浮游植物的大量生长对环境因子反馈效应显著,水体的pH值随着藻类细胞密度的增加而上升.大宁河水体水生态环境特征存在显著的空间特征异质性.浮游植物群落结构组成受到水环境特征和空间相邻性的双重影响.

To elucidate relationships between phytoplankton and related environmental factors,phytoplankton and environmental parameters of water quality in the Daning River were conducted using multivariate statistical analysis.Most of the investigated physico chemical parameters [water temperature,total nitrogen,nitrate-N（NO 3--N）,pH and dissolved oxygen concentration（DO）]in Daning River are significantly different among those sampling sites（ANOVA,p 0.05）.The results indicate that the Daning River has a comparatively high spatial and temporal heterogeneity in the phytoplankton community composition（ANOVA,p 0.05）.The maximum cell density was recorded in Dachang and the minimum density was found at Wuxia-kou sites.Multi-algal species blooms were observed in the same time and place with the maximum density appeared.Correlation analysis was performed to illuminate the relationships between algae density and environmental variables,TN（r =-0.789,p 0.05）,NO 3--N（r =-0.825,p 0.05） and NO 2--N（r =-0.803,p 0.05） were negatively correlated with algae density.The results indicate that nitrogen soluble nutrients are key regulatory factors for phytoplankton abundance.The results of redundancy analysis（RDA） indicate that main soluble nutrients（TN,TP,NO 3--N and NO 2--N）,suspended substance（SS） and transparency contributed significantly to phytoplankton community composition.Phytoplankton growth could enhance the pH value.The environmental characterizations and sample sites adjacency contributed significantly to phytoplankton community composition.