Multiyear Measurements on Δ17O of Stream Nitrate Indicate High Nitrate Production in a Temperate Forest

Shaonan Huang, Fan Wang, Emily M. Elliott, Feifei Zhu, Weixing Zhu, Keisuke Koba, Zhongjie Yu, Erik A. Hobbie, Greg Michalski, Ronghua Kang, Anzhi Wang, Jiaojun Zhu, Shenglei Fu, Yunting Fang

Research output: Contribution to journalArticlepeer-review


Nitrification is a crucial step in ecosystem nitrogen (N) cycling, but scaling up from plot-based measurements of gross nitrification to catchments is difficult. Here, we employed a newly developed method in which the oxygen isotope anomaly (Δ17O) of nitrate (NO3 -) is used as a natural tracer to quantify in situ catchment-scale gross nitrification rate (GNR) for a temperate forest from 2014 to 2017 in northeastern China. The annual GNR ranged from 71 to 120 kg N ha-1 yr-1 (average 94 ± 10 kg N ha-1 yr-1) over the 4 years in this forest. This result and high stream NO3 - loss (4.2-8.9 kg N ha-1 yr-1) suggest that the forested catchment may have been N-saturated. At the catchment scale, the total N output of 10.7 kg N ha-1 yr-1, via leaching and gaseous losses, accounts for 56% of the N input from bulk precipitation (19.2 kg N ha-1 yr-1). This result indicates that the forested catchment is still retaining a large fraction of N from atmospheric deposition. Our study suggests that estimating in situ catchment-scale GNR over several years when combined with other conventional flux estimates can facilitate the understanding of N biogeochemical cycling and changes in the ecosystem N status.

Original languageEnglish (US)
Pages (from-to)4231-4239
Number of pages9
JournalEnvironmental Science and Technology
Issue number7
StatePublished - Apr 7 2020
Externally publishedYes

ASJC Scopus subject areas

  • General Chemistry
  • Environmental Chemistry


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