『Abstract
　We used the dual isotope method to study differences in nitrate export in two subwatersheds in Vermont, USA. Precipitation, soil water and streamwater samples were collected from two watersheds in Camels Hump State Forest, located within the Green Mountains of Vermont. These samples were analyzed for the δ^15N and δ¹⁸O of NO3^-. The range of δN-NO3^- values overlapped, with precipitation -4.5‰ to +2.0‰ (n = 14), soil solution -10.3‰ to +6.2‰ (n = 12) and streamwater +0.3‰ to +3.1‰ (n = 69). The δ¹⁸O of precipitation NO3^- (mean 46.8±11.5‰) was significantly different (P＜0.001) from that of the stream (mean 13.2±4.3‰) and soil waters (mean 14.5±4.2‰) even during snowmelt periods. Extracted soil solution and streamwater δ¹⁸O of NO3^- were similar and within the established range of microbially produced NO3^-, demonstrating that NO3^- was formed by microbial processes. The δ¹⁵N and δ¹⁸O of NO3^- suggests that although the two tributaries have different seasonal NO3^- concentrations, they have a similar NO3^- source.

Keywords: δ^15N; δ¹⁸O; Nitrate; Nitrogen; isotopes; Oxygen isotopes; Vermont』

Introduction
Methods
　Site description
　Sample collection
　　Precipitation
　　Streamwater
　　Soil and extracted soil solution
　Laboratory analyses
　　Isotope procedure
　Quality control
　Statistical methods
Results
　Precipitation chemistry
　Streamwater chemistry
　Soil nitrate
Discussion
　Streamwater nitrate dynamics
　Streamwater nitrate sources
　Soil nitrate
　Comparison among precipitation, streamwater and soil solution
　Snow melt
Conclusions
Acknowledgements
References