N% and S% in Leaves of Vascular Plants Cinnamomum camphora and Pinus massoniana Lamb. for Indicating the Spatial Variation of Atmospheric Nitrogen and Sulfur Deposition

Abstract

N and S contents in Cinnamomum camphora leaves, Pinus massoniana Lamb. leaves, epilithic Haplocladium microphyllum(Hedw.) Broth. and rhizosphere soil collected along 3 directions from urban area to rural area at Guiyang city in a total of 296 samples were investigated systematically. The level of atmospheric N deposition and atmospheric SO2 concentrations at each sampling site were calculated according to the quantitative relationship between moss N content and atmospheric N deposition and the quantitative relationship between moss S content and atmospheric SO2 concentration. Leaves N content in Cinnamomum camphora(1.01%-2.37%) and Pinus massoniana Lamb.(0.99%-2.42%)showed significant decrease from urban area with the highest atmospheric nitrogen deposition to suburb, while slightly higher leaves N reemerged at rural area beyond 24 km, suggesting increased N deposition occurred in rural area. Leaves S content in Cinnamomum camphora(0.16%-0.43%) and Pinus massoniana Lamb.(0.18%-0.32%) showed significant decrease from urban area to suburb, the highest level at urban was mainly contributed by the high sulfur released from the production and living of urban areas into the atmosphere, and the lowest level occurred at rural area(30-36km). No significant difference was seen for soil N and S contents. The relationships between the estimated input of atmospheric N deposition and the leaves N content of Cinnamomum camphora and Pinus massoniana Lamb. at the sites investigated were found to be significant linear correlations, and the relationships between the estimated atmospheric SO2 concentration and the leaves S content of Cinnamomum camphora and Pinus massoniana Lamb. were also significant linear correlations(P<0.05). The results indicated that N and S contents in Cinnamomum camphora and Pinus massoniana Lamb. leaves can be used to show the spatial variation of atmospheric N and S deposition.