交通NOx排放对南京城郊国道杨树防护林带N含量及δ^(15)N的影响

Impact of traffic emission NOx on N concentration and ^(15)N natural abundance in Poplar shelterbelt beside the Nanjing suburban highway

以南京城郊国道杨树防护林带为对象,研究道路交通排放的NOx对杨树各器官及土壤N含量和δ15N的影响。结果表明:随着离国道距离越远,叶片N含量和δ15N整体呈下降趋势,并均与距离成线性相关。杨树大部分器官N含量都是10 m处大于与80 m处,而各器官δ15N 10 m处均大于80 m处;10 m和80 m两处各器官N含量表现为叶片>树根皮>树干皮>树根木质部>树干木质部A>树干木质部B,δ15N表现为树根皮>树根木质部>树干木质部A>树干木质部B>叶片>树干皮。相比植物体,杨树林带土壤N含量和δ15N则没有表现出很好的规律性。

The poplar shelterbelt beside the Nanjing suburban highway was investigated to research the impact of traffic emission NOx on N concentration and 1 5N natural abundance in different organs of poplar and the soil. The results showed that the N concentrations and the δ15N values in the leaves were all reduced according to the increase of the distances from the highway, and linearly correlative with the distances. The N concentrations of most poplar organs were greater in 10 m sampling point than in 80 m sampling point, while the 15 N natural abundance values of all poplar organs were greater in 10 m sampling point than in 80 m sampling. In 10 m and 80 m sampling points, the N concentrations of all poplar organs had the same order of leaf〉root bark〉trunk bark〉root xylem〉trunk xylem A〉trunk xylem B, and the order of 15 N natural abundance values was root bark〉root xylem〉trunk xylem A〉trunk xylem B〉leaf〉trunk bark. Compared with plants, the N concentrations and 15 N natural abundance values in soil were not well correlated with the change of distances.