Gu B, Alexander V
Institute of Marine Science, School of Fisheries and Ocean Sciences, University of Alaska Fairbanks, 99775-1080, Fairbanks, AK, USA.
Oecologia. 1993 Oct;96(1):43-48. doi: 10.1007/BF00318029.
The dynamics of nitrogen supply was investigated for blue-green and green algae from Smith Lake and other freshwaters of subarctic and arctic Alska. The natural abundance of N (defined as δN) of six N-fixing blue-green algae was 1.0±%(X±SE), indicating supply of metabolic nitrogen from atmospheric N (δN=0.0). The δN of six green algae showed an average of 6.6±4.5%, which is significantly higher than δN of N-fixing blue-green algae from the same waters, reflecting the utilization of dissolved inorganic nitrogen (DIN). Nitrogen-fixing algae also showed higher nitrogen content (7.1±2.1%) than non-N-fixing algae (2.9±1.5%). The δN of a bloom-forming species, Anabaena flos-aquae (Lyngb.) Breb. in Smith Lake showed no significant interannual variations during a three-year study period. The changes in δN during each bloom were probably due to variations in the N composition of DIN and in the proportional uptake of DIN and N fixation. An estimation of the fractional contribution of atmosphere-derived nitrogen (ADN) from δN indicated that A. flos-aquae obtained 58-75% of its nitrogen by N fixation. This technique agreed with the result obtained using a N enrichment method. The δN of the presumed N-fixing terrestrial plant was similar to that of the atmospheric N, whereas the δN of the presumed non-N-fixing terrestrial plants reflected their nitrogen sources.
对来自阿拉斯加亚北极和北极地区史密斯湖及其他淡水水体中的蓝藻和绿藻的氮供应动态进行了研究。六种固氮蓝藻的氮自然丰度（定义为δN）为1.0±%（X±SE），表明代谢氮来自大气氮（δN = 0.0）。六种绿藻的δN平均为6.6±4.5%，显著高于同一水体中固氮蓝藻的δN，这反映了溶解无机氮（DIN）的利用情况。固氮藻类的氮含量（7.1±2.1%）也高于非固氮藻类（2.9±1.5%）。在一项为期三年的研究期间，史密斯湖中的一种形成水华的物种——水华鱼腥藻（Anabaena flos-aquae (Lyngb.) Breb.）的δN没有显著的年际变化。每次水华期间δN的变化可能是由于DIN的氮组成变化以及DIN和固氮的比例吸收变化所致。根据δN对大气源氮（ADN）的贡献率进行估算表明，水华鱼腥藻通过固氮获得其58 - 75%的氮。该技术与使用氮富集方法获得的结果一致。假定的固氮陆生植物的δN与大气氮的δN相似，而假定的非固氮陆生植物的δN反映了它们的氮源。
