| 摘要: |
| 浮游藻类对溶解态氮的吸收同化是湖泊氮生物循环和水体富营养化发生机制探讨的关键环节。本文通过15N稳定同位素添加实验以铜绿微囊藻（Microcystis aeruginosa）、海链藻（Thalassiosira sp.）、卡德藻（Tetraselmis sp.）、剧毒卡尔藻（Karlodinium veneficum）以及盐水隐藻（Rhodomonas salina）为研究对象，从浮游藻类氮素吸收时间、营养盐基质以及藻种差异三个方面研究五种藻类对铵氮（NH4+-N）、硝氮（NO3--N）、尿素氮（Urea-N）三种形态氮的吸收特征。研究发现：（1）浮游藻类对三种形态氮的吸收均在1h时吸收速率最高，其氮素吸收过程为快速吸收。（2）浮游藻类优先吸收还原态氮，其中NH4+-N吸收速率最高，当培养周期为1d和4d时浮游藻类对NH4+-N吸收速率的均值分别为4.05和4.15μmol/（L·h）；浮游藻类对Urea-N吸收相对偏好系数为25.18—713.42，表现出对小分子溶解态有机氮的特定偏好性。（3）不同藻种对氮素吸收具有不同特征，其中，剧毒卡尔藻对三种形态氮的吸收速率均为最高，而铜绿微囊藻的吸收速率均为最低；不同藻种不同培养时间氮素吸收速率差异与浮游藻类生长周期等特性有关。不同浮游藻类对不同形态氮素表现出吸收特异性，对水体氮负荷和浮游藻类水华优势种形成将产生重要影响。 |
| 关键词: 氮吸收 15N同位素 相对偏好系数 氮形态 浮游藻类 |
| DOI：10.11693/hyhz20181200289 |
| 分类号:Q178 |
| 基金项目:国家自然科学基金项目，41771519号，41671477号；研究所一三五规划重点培育项目“湖泊复合污染的生态效应与防控治理”，NIGLAS2018GH05号。 |
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| THE USE OF 15N TO MEASURE NITROGEN UPTAKE OF PHYTOPLANKTON |
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HAN Fei-Er1,2, ZHAO Zhong-Hua2, LI Da-Peng1, ZHANG Lu2
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1.School of Environmental Science and Engineering, Suzhou University of Science and Technology, Suzhou 215009, China;2.State Key Laboratory of Lake Science and Environment Research, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China
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| Abstract: |
| The uptake of dissolved nitrogen by phytoplankton is a key link in the mechanism of lake nitrogen biocirculation and eutrophication. Characteristics of nitrogen uptake by Microcystis aeruginosa, Thalassiosira sp., Tetraselmis sp., Karlodinium veneficum and Rhodomonas salina were studied in three parts:the time of nitrogen uptake by phytoplankton, nitrate forms and the difference of algae species. The uptake of three forms of nitrogen:NH4+-N, NO3--N and Urea-N, was studied by using 15N isotope addition experiments. The uptake of three nitrogen forms by planktonic algae was the highest at 1h, and the nitrogen uptake was rapid. Phytoplankton preferentially uptakes the reduced nitrogen, such as ammonia. When the incubation time of algae is 1d and 4d, the mean uptake rate of NH4+-N is 4.05μmol/(L·h) and 4.15μmol/(L·h), respectively; The relative preference index of phytoplankton to Urea-N is 25.18-713.42, which shows the specific preference for micro-molecule dissolved organic nitrogen. Different species of algae have different characteristics for nitrogen uptake. The uptake rate of NH4+-N, NO3--N, and Urea-N by Karlodinium veneficum is the highest, while the Microcystis aeruginosa is the lowest. Different algae species have different nitrogen uptake rates when the incubation time is different, which is related to the characteristic growth cycle of planktonic algae. Different planktonic algae exhibit uptake specificity for different forms of nitrogen, and play an important role in the nitrogen load of water and the formation of dominant species of planktonic algae. |
| Key words: Nitrogen uptake 15N isotope relative preference index nutrient substrate phytoplankton species |
