海洋浮游生物氮吸收动力学及其粒级特征

于１９９１年秋－１９９２年夏在中国科学院生态网络站之一的胶州湾进行了４个季节的现场实验，运用＾１５Ｎ同位素示踪方法研究胶州湾浮游生物群落对两种主要源铵态氮和硝态氮的吸收动力学及其粒级特征。研究初步阐明自然浮游生物落在不同季节，对不同氮源的吸收特性和受控机制，首次在群落水平上给出不同粒级浮游生物氮吸收特征的定量描述，从而为新生产力研究，生态系能流分配和生源要素生物地化循环研究提供重要参数。

MARINE MICROPLANKTON NITROGEN UPTAKE KINETICS WTH SPECIAL REFERENCE TO SIZE-FRACTIONATION

In situ experiments with 15N isotope tracer techniques were conducted seasonally from Nov. 1991 to Aug. 1992 in Jiaozhou Bay to inquire into the kinetics of ammonium and nitrate uptakes by size-fractionated natural microplankton assemblages.Obvious differences between the uptake kinetics of the two principal nitrogen sources were observed in all seasons. For total assemblages, potential maximum uptake rates of ammonium were always higher than those of nitrate, and half uptake saturation constants of nitrate were not remarkably lower than those of ammonium,indicating the uptake preference of microplankton for ammonnium to nitrate. Furthermore, the uptake of nitrate was influenced much by environmental factors (such as temperature, light etc.). In winter, variations of nitrate uptake witli increaasing nitrate concentration could not fit the Michaelis-Menten equation.Singnificant differences of nitrogen uptake among different size fractions were also found. First, nitrate was mainly uptaken by netplankton, and ammonium was mainlly uptaken by nanoplankton and picoplankton. Secondly, the light dependences for both nitrate and ammonium uptake of netplankton and nanoplankton were much stronger than that of picoplankton. These findings suggested that new production is contributed mainly by netplankton and regenerated production is contributed mainly by nanoplankton, especially picoplankton.