应用离子吸收动力学方法比较鹿蕊地衣对不同氮素的吸收能力  

Differences in Cladonia rangiferina nitrogen uptake capacity between ammonium and nitrate with uptake kinetics

作　　者：陈润玉 胡雯惠 刘学炎[1] CHEN Runyu;HU Wenhui;LIU Xueyan(School of Earth System Science,Tianjin University,Tianjin 300072,China)

机构地区：[1]天津大学地球系统科学学院,天津300072

出　　处：《应用生态学报》2024年第7期1859-1865,共7页Chinese Journal of Applied Ecology

基　　金：国家杰出青年科学基金项目(42125301)资助。

摘　　要：大气氮沉降增加影响着陆地植被群落结构与功能。非固氮型地衣主要依赖大气沉降的无机氮(铵态氮和硝态氮)作为氮源,因此,成为大气氮沉降的生物指示器,但地衣对这两种无机氮的吸收能力差异尚不清楚,这严重限制了利用地衣氮含量解译大气氮沉降水平的准确性。本研究以鹿蕊地衣为对象,在光照和避光条件下对鹿蕊地衣进行单独铵根(NH_(4)^(+))或硝酸根(NO_(3)^(-))添加以及NH_(4)^(+)和NO_(3)^(-)按不同比例混合添加处理,分析地衣氮吸收能力差异。结果表明:鹿蕊地衣对NH_(4)^(+)和NO_(3)^(-)的吸收速率随浓度增加而增加,并呈Michaelis-Menten曲线特征。鹿蕊地衣偏好吸收NH_(4)^(+),NH_(4)^(+)的亲和力和吸收效率均高于NO_(3)^(-);随着NH_(4)^(+)与NO_(3)^(-)混合比例的增加,鹿蕊地衣吸收NO_(3)^(-)的速率和总量降低,但吸收NH_(4)^(+)的速率基本不受影响,这表明NH_(4)^(+)增加会抑制鹿蕊地衣对NO_(3)^(-)的吸收能力。避光显著降低鹿蕊地衣对NO_(3)^(-)的最大吸收速率和效率,但对鹿蕊地衣NH_(4)^(+)吸收能力的影响较小。本研究揭示了地衣具有喜NH_(4)^(+)和亲NH_(4)^(+)的氮吸收策略,因此,在利用地衣监测大气氮污染水平及评价大气氮沉降对地衣生理生态特征的影响时需要考虑大气无机氮沉降的主要类型。Atmospheric nitrogen(N)deposition could affect the structure and function of terrestrial plants.Non-N_(2)-fixing lichens are used to monitor atmospheric N deposition because they rely on the deposited inorganic N(i.e.,ammonium and nitrate)as N sources.However,the uptake capacities of lichen on ammonium and nitrate remain unclear,which hinders the application of lichen N content to accurate bioindication of atmospheric N deposition levels.We investigated ammonium and nitrate uptake capacities of Cladonia rangiferina,which was treated with ammonium alone,nitrate alone,and ammonium and nitrate mixture solutions with different mixing ratios under light and dark conditions.The results showed that N uptake rates increased with ammonium and nitrate concentrations in solutions and generally followed the Michaelis-Menten saturation kinetics.Ammonium uptake of C.rangiferina showed higher values of affinity,and was more efficient than the nitrate uptake.Both rates and amounts of nitrate uptake decreased with increasing ratios of ammonium to nitrate in solutions,while ammonium uptake showed no substantial variations,indicating an inhibition of ammonium on nitrate uptake capability.The darkness significantly decreased the maximum uptake rate and efficiency of nitrate,but had much weaker effects on lichen ammonium uptake.These findings highlight the preference of lichen on ammonium as a key N uptake strategy.It is thus necessary to consider the main types of atmospheric inorganic N deposition when using lichens to monitor atmospheric N pollution levels and evaluate N deposition based on lichen ecophysiology.

关 键 词：地衣 铵根 硝酸根 氮吸收 大气氮沉降 

分 类 号：Q948[生物学—植物学]