水华条件下鄱阳湖区植物叶片碳氮同位素特性

为探讨水华发生区水生植物微观碳氮代谢特性,于2014年同期监测了鄱阳湖6个具重要生态功能的湖区水质,同时采集各湖区两种生活型优势水生植物——马来眼子菜(Potamogeton malaianus)和荇菜(Nymphoides peltatum),并对其叶片中δ13C和δ15N同位素进行分析. 结果表明,相对于非水华区,水华区水体中ρ(Chla)、ρ(TN)、ρ(TP)、ρ(NH₄+-N)明显偏高,处于富营养态. 马来眼子菜叶片δ13C偏低0.22‰~3.91‰,δ15N偏低0.66‰~10.15‰；荇菜叶片δ13C偏高1.15‰~2.37‰,δ15N偏低3.02‰~4.81‰. 水华区马来眼子菜叶与荇菜叶中δ13C、δ15N趋同,差异变小,分别为3.53‰和0.37‰(非水华区δ13C差异为5.93‰~8.59‰,δ15N差异为0.63‰~7.50‰)；各采样点马来眼子菜叶δ15N相对于荇菜叶δ15N偏高0.37‰~7.50‰,其δ13C变幅(3.91‰)更大(荇菜叶片为2.37‰). 研究显示,马来眼子菜受环境的影响更大,能更敏感地指示环境灾变. 

Characteristics of Stable Carbon and Nitrogen Isotope Signatures of Aquatic Plants to Algal Blooms in Poyang Lake

In order to investigate the C-N metabolism characteristics of aquatic plants in the algal bloom zones of lakes, six key eco-functional zones were selected during the same period in 2014. Dominant aquatic plant species, such as Potamogeton malaianus and Nymphoides peltatum, were collected to determine water quality. Stable isotopic analysis (δ13C, δ15N signature) of aquatic plant leaves was applied to explore the influence of algal blooms on the C-N metabolism of aquatic plants in lakes with clean water. The results indicated that the trophic state level was higher in the water body of algal bloom areas compared with other lake zones. In contrast with non-bloom water, ρ(Chla), ρ(TN), ρ(TP) and ρ(NH₄+-N) were apparently higher in the water column of bloom areas in the eutrophic state. In the lake zones with existence of algal blooms, lower δ13C (0.22‰-3.91‰) and δ15N (0.66‰-10.15‰) in the leaves of P. malaianus were detected, and higher δ13C (1.15‰-2.37‰) and lower δ15N (3.02‰-4.81‰) in the leaves of N. peltatum were found. Of note, in the area of algal blooms, both of δ13C and δ15N values between P. malaianus and N. peltatum leaves were separately convergent, and the differences were both smaller (δ13C:3.53‰, δ15N:0.37‰) than those in the clean-water areas (difference of δ13C:5.93‰-8.59‰, difference of δ15N:0.63‰-7.50‰). Compared with stable C & N isotope signatures of N. peltatum (δ13C:2.37‰), higher δ15N values (0.37‰-7.50‰) and larger amplitude of variation in the δ13C values (3.91‰) were found in the leaves of P. malaianus throughout all the studied zones of Poyang Lake. Research shows that P. malaianus is more sensitive to environmental disaster.