摘要
利用15N标记技术,比较了附着藻类对太湖3种氮源(尿素、NH4^+和NO3^-)的吸收能力。附着藻类对尿素的吸收速率为1.93~5.52μmol/(g.h),对NH4^+的吸收速率为0.89~7.67μmol/(g.h),而对NO3^-的吸收速率为0.09~0.35μmol/(g.h)。各氮源的贫化百分比在0.18 %~9.03 %。在浓度为20和50μmol/L时,尿素的贫化值分别为8.41 %和8.14 %,与NH4^+的贫化值相当(分别为9.03 %和 7.01 %);NO3^-的贫化值在各浓度下都低于0.29 %。附着藻类对每种氮源的吸收速率在3种氮源吸收速率总和中的相对比重:尿素平均为47.9 %,NH4^+平均为49.6 %,NO3^-平均为2.5 %。根据Vmax与Ks比值,附着藻类对3种氮源的吸收亲和力大小顺序为:尿素>NH4^+>NO3^-。研究表明,尿素是除NH4^+外附着藻类生长可利用的又一重要氮源。
The uptake ability of periphytic algae to three different nitrogen substrates (urea, NH4^+ and NO3^-) was examined using 15N tracer techniques in eutrophic Lake Taihu in China.The periphytic algae uptake rates of urea and NH4^+ were 1.93~5.52μmol/(g?h) and 0.89~7.67μmol/(g?h), respectively, accounting for 47.9 % and 49.6 % of the total N uptake rates ,which were significantly higher than that of NO3^- (0.09~0.35μmol/(g?h)) accounting for 2.5 % to the total N uptake rates.The depletion rates of each nitrogen source ranged from 0.18 % to 9.03 % in the experiment. At concentrations of 20μmol/L and 50μmol/L, the depletion rates of urea were 8.41 % and 8.14 % respectively , 9.03 % and 7.01 % for NH4^+ , while both much lower than 0.29 % for NO3^- . According to the Vmax : KS ratio of periphytic algal uptake kinetics, the sequence of uptake affinity was urea〉NH4^+〉NO3^-. Our results suggested that the ability to absorb urea gives periphytic algae access to additional nitrogen source in eutrophic lakes.
出处
《水生态学杂志》
北大核心
2014年第1期60-64,共5页
Journal of Hydroecology
基金
中国科学院南京地理与湖泊研究所"一三五"战略发展规划项目(NIGLAS2012135007)
国家重大科学研究计划项目(2012CB956104)