法国梧桐叶片氮含量及氮同位素对城市大气湿沉降氮的响应研究  

Platanus orientalis Foliar N% and δ^(15)N Responses to Nitrogen of Atmospheric Wet Deposition in Urban Area

作　　者：王燕丽[1,2] 肖化云[1] 肖红伟[1,2] 

机构地区：[1]中国科学院地球化学研究所环境地球化学国家重点实验室,贵阳550002 [2]中国科学院研究生院,北京100049

出　　处：《环境科学》2012年第4期1080-1085,共6页Environmental Science

基　　金：国家自然科学基金项目(40573006;40721002)

摘　　要：通过对贵阳市法国梧桐叶片为期1 a的监测(2009-03～2010-04),分析其叶片氮含量及氮同位素组成随季节变化的规律,并与同期湿沉降监测结果进行对比,探讨维管束植物叶片响应大气湿沉降氮的可能性.结果表明,法国梧桐叶片N%变化范围为1.48%～5.27%,均值为3.36%,根际土TN%为0.29%,叶片δ15N变化范围为4.48‰～8.39‰,均值为6.38‰.叶片N%与δ15N具有较好的相关性,随时间变化皆呈现春夏较高、秋季降低的趋势,冬季落叶,无监测数据.结合该采样点同期雨水监测数据,发现叶片N%与雨水中DIN浓度(0.57～6.74 mg.L-1)、叶片δ15N与雨水δ15NH4+-N呈现一致的变化规律,表明湿沉降氮是叶片吸收氮的一个重要来源,法国梧桐叶片指示大气N沉降量的变化成为可能.研究还发现法国梧桐叶片δ15N比其吸收氮的2个主要端元(根际土δ15TN:3.19‰±1.04‰,雨水δ15N-NH4+:-19.76‰～-10.41‰)都偏正,表明法国梧桐在吸收氮的过程中存在着较大的同位素分馏.Leaves of Platanus orientalis were collected since Mar.2009 till Apr.2010,in an urban area at Guiyang.After mass of experiments and analysis,we carried out constructing the temporal variation of foliar N% and δ15N： both higher in Spring/Summer,lower in Autumn,no data of Winter because of leaf abscission.Results showed that foliar N% varied from 1.48% to 5.27%,with an annual average of 3.36%,while the average concentration of total N in rhizospheric soil was 0.29%.The foliar N% rose and fell relative to DIN in rainwater（range from 0.57 mg·L-1 to 6.74 mg·L-1）,indicating that the N% content in foliar tissue of plant was approximately proportional to atmospheric N inputs.The range of foliar δ15N were from 4.48‰ to 8.39‰,with the average of 6.33‰,much higher than the δ15N-NH＋4 of rain water（-19.76‰——10.41‰） and δ15TN of rhizospheric soil（3.19‰±1.04‰）.Besides,a good uniform correlation between foliar δ15N and δ15N-NH＋4of rain water were found.As synthesis of two main N sources,the more positive δ15N values of Platanus orientalis can be explained by isotopic fractionation during N uptake and basipetal translocation.These responses of both foliar N% and δ15N to atmospheric nitrogen deposition,revealed the potential value in using vascular leaves as bio-monitors for assessment of N deposition,furthermore,for prevention and control of air pollution in urban ecosystem.

关 键 词：法国梧桐 湿沉降氮 叶片组织氮含量 叶片氮同位素 

分 类 号：X142[环境科学与工程—环境科学] X517