太湖高等水生植物稳定碳、氮同位素特征

高等水生植物的稳定碳、氮同位素能够反映其生理生态学信息.从太湖贡湖湾和梅梁湾采集高等水生植物,分析两湖湾高等水生植物的稳定碳、氮同位素值时空变化和种类差异.结果显示:水生植物的稳定碳、氮同位素值因时间、空间和种类而发生变化,总体上时间变化规律不明显,空间变化有一定规律性:梅梁湾中穗花狐尾藻、马来眼子菜、苦草、凤眼莲的δ~(15)N明显高于贡湖湾,挺水植物芦苇的δ~(15)N差异不显著,反映了梅梁湾较贡湖湾有较高的营养水平;贡湖湾中穗花狐尾藻、苦草的δ~(13)C显著高于梅梁湾,其它种类没有显著差异.从种类特征来看,贡湖湾和梅梁湾浮叶植物与挺水植物芦苇、凤眼莲、菱的δ~(13)C偏低,而微齿眼子菜、金鱼藻、马来眼子菜、苦草、伊乐藻、穗花狐尾藻等沉水植物的δ~(13)C值较高,这与它们所处的环境和碳源有关.

Carbon and nitrogen stable isotopes of macrophytes from Lake Taihu

Nitrogen and carbon stable isotope values can be used to obtain eco-physiological information on macrophytes. This study collected macrophytes at different seasons from Gonghu Bay and Meiliang Bay of Lake Taihu, China to determine the variations of stable isotope values with regard to different season, space and species. The results showed that, with the season, space and species changing, nitrogen and carbon stable isotope values of macrophytes were changed, and the changed values were not obvious with seasonal variation in general, but had certain regularity with the space changes. The nitrogen stable isotopes of Myriophyllum spicatum, Potamogeton malaianus, Vallisneria natans and Eichhornia crassipes in Meiliang Bay were significantly higher than those of Gonghu Bay. The nitrogen stable isotope from emergent plants of Phragmites communis showed higher level in Meiliang Bay than that in Gonghu Bay. However, the carbon stable isotope values of Myriophyllum spicatum and Vallisneria natans in Gonghu Bay were significantly higher than those in Meiliang Bay, others were not significant in the differences. In Gonghu Bay and Meiliang Bay, the carbon stable isotope values of floating plants and emergent plants were lower in Phragmites communis, Eichhornia crassipes and Trapa incise, while Potamogeton maackianus, Ceratophyllum demersum, Potamogeton malaianus, Vallisneria natans, Elodea nuttallii and Myriophyllum spicatum of submerged plants were higher. This might due to the different environments and carbon sources.