Tracing sources of nitrate in snowmelt runoff using a high‐resolution isotopic technique
Tracing sources of nitrate in snowmelt runoff using a high‐resolution isotopic technique
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DOI：
10.1029/2004gl020908
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发表时间：
2004-11
影响因子：
5.2
通讯作者：
N. Ohte;S. Sebestyen;J. Shanley;D. Doctor;C. Kendall;S. Wankel;E. Boyer
中科院分区：
文献类型：
--
作者：
N. Ohte;S. Sebestyen;J. Shanley;D. Doctor;C. Kendall;S. Wankel;E. Boyer
硝酸盐双同位素组成（δ 15 N和δ 18 O）的测定方法适用于径流过程中氮素对河流的贡献研究。该方法仅需70 nmol NO3−，可实现高通量样品。我们通过在美国佛蒙特州的Sleepers River Research Watershed生成高时间分辨率数据集，研究了融雪期间源头流的硝酸盐来源。在径流的最早阶段，溪流NO3−浓度最高，而溪流流量、NO3−浓度和NO3−的δ 18 O在日融化过程中通常相互跟踪。NO3-流的同位素组成在大气和地下水NO3-端成员之间变化，表明大气来源的NO3-从积雪到流的直接贡献。在融雪的中期到后期，来源转向土壤NO3-通过浅层地下流路径进入河流。
The denitrifier method to determine the dual isotopic composition (δ15N and δ18O) of nitrate is well suited for studies of nitrogen contributions to streams during runoff events. This method requires only 70 nmol of NO3− and enables high throughput of samples. We studied nitrate sources to a headwater stream during snowmelt by generating a high‐temporal resolution dataset at the Sleepers River Research Watershed in Vermont, USA. In the earliest phase of runoff, stream NO3− concentrations were highest and stream discharge, NO3− concentrations, and δ18O of NO3− generally tracked one another during diurnal melting. The isotopic composition of stream NO3− varied in‐between atmospheric and groundwater NO3− end members indicating a direct contribution of atmospherically‐derived NO3− from the snow pack to the stream. During the middle to late phases of snowmelt, the source shifted toward soil NO3− entering the stream via shallow subsurface flow paths.