中文摘要：

为研究太湖春季浮游植物群落氮吸收特征及其与浮游植物群落结构和环境因子的关系,于2010年5月中旬采集太湖6个点位水样,利用15N稳定同位素示踪技术,测定太湖浮游植物群落对硝态氮,铵态氮和尿素的吸收,结果表明：太湖浮游植物群落对铵态氮的吸收速率均值最高,占几种氮总吸收量ρ（DN）的62.8%,各点位值在0.181-1.575μmol/（L.h）之间.各点位浮游植物群落对硝态氮和尿素态氮的吸收速率范围分别为0.004-0.118μmol/（L.h）和0.043-1.116μmol/（L.h）.梅梁湾,湖心以及五里湖三个湖区浮游植物群落均优先吸收铵态氮、其次为尿素,对三种氮的吸收速率都是ρ（NH4）〉ρ（UREA）〉ρ（NO3）,而胥口浮游植物群落优先吸收尿素,且对尿素的绝对吸收速率最大,其次为铵态氮,硝态氮最低.在可利用氮含量较高的情况下,浮游植物丰度、组成结构等因子可能是影响太湖浮游植物群落氮吸收空间差异的最重要因素.

英文摘要：

To characterize the nitrogen uptake by phytoplankton and its relationships with phytoplankton community structure and enviromental factors,we measureed the uptake of ammonium,nitrate and urea by phytoplankton community from different areas of Lake Taihu in mid-May,2010,using the 15N-tracer technology.The results showed that： Uptake rate of ammonium was highest for all lake areas,accounting for 62.8% of the total nitrogen uptake.The uptake rates were 0.181-1.575,0.004-0.118 and 0.043-1.116μmol/（L·h）for ammonium,nitrate and urea,respectively.Phytoplankton communities preferred uptaking ammonium in Meiliang Bay,Lake Center and Wuli Bay and the uptake rates of the three forms of nitrogen were arranged as follows： ρ（NH4）ρ（UREA） ρ（NO3）.However,phytoplankton community in Xukou Bay preferred urea to ammonium and the uptake rate of urea was the highest,the uptake rate of nitrate was the lowest.When concentrations of nitrogen are high,phytoplankton abundance and community structure are likely important factors determining the nitrogen uptake by phytoplankton community in Lake Taihu.