基于碳氮稳定同位素组成分析的孔石莼对氨氮的吸收

氨氮(NH4-N)是水体中能被藻类直接吸收利用的无机氮。利用稳定同位素技术研究了不同浓度下孔石莼(Ulvapertusa)对NH4-N的吸收,藻类体内δ15N、δ13C的变化。结果显示:试验初始阶段,孔石莼大量吸收水体中的14NH4-N、12CO2用于自身组织的合成,导致水体中氨氮浓度、δ15N和δ13C急剧下降,约在5～25 h,这一阶段水体中氨氮浓度变化很小,藻体15N缓慢降低,达到平缓期;约在25 h后,氨氮浓度缓慢下降,海水中的底物浓度很低,水体中14NH4-N几乎被吸收殆尽,孔石莼开始大幅吸收15NH4-N,δ15N上升。δ13C在4 h后呈现无规律波动。

Uptake of ammonium by Ulva pertusa based on carbon and nitrogen stable isotope analyses

Ammonia(NH4-N)is thought to be the preferred source of fixed nitrogen for algae in waters.This paper studied the uptake of ammonium by Ulva pertusa based on carbon and nitrogen stable isotope analyses.The result showed that,the assimilation of 14NH4-N and 12CO2 by U.pertusa in order to satisfy their nitrogen demand for growth in the initial test phase,which lead to the concentration of ammonia,δ15N and δ 13C sharp decline in waters.About 5~25 h,it was very small change of concentration of ammonia in water,δ 15N slowly decreased to moderate phase.After about 25 h,the concentration of ammonia decreased slowly,and the substrate concentration in seawater was very low,U.pertusa assimilated a grate quantity of 15NH4-N when 14NH4-N in waters was almost exhausted,however,δ 15N rised.4h later,δ 13C took on erratic fluctuations.