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Updated: Jun 25, 2026
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Automated, High-resolution Mobile Collection System for the Nitrogen Isotopic Analysis of NOx
Published on: December 20, 2016
Tree-ring nitrogen isotopes reflect anthropogenic NOx emissions and climatic effects
Martine M Savard1, Christian Bégin, Anna Smirnoff
1Natural Resources Canada, Geological Survey of Canada, Division Québec, 490 rue de la Couronne, Québec, Canada. msavard@nrcan.gc.ca
Environmental Science & Technology
|February 28, 2009
Summary
Tree rings reveal past nitrogen cycle changes. Nitrogen isotope analysis in tree rings tracks local climate and pollution, offering insights into atmospheric nitrogen deposition. This method aids in understanding historical environmental conditions.
Area of Science:
- Environmental Science
- Geochemistry
- Paleoclimatology
Background:
- Anthropogenic nitrogen emissions have risen significantly over the past century.
- Monitoring nitrous oxide (N2O) concentrations is a recent development.
- Understanding past nitrogen cycles is crucial for assessing long-term environmental impacts.
Purpose of the Study:
- To investigate if tree rings from temperate regions can be used to infer past changes in nitrogen cycles.
- To analyze nitrogen isotope (delta15N) trends in tree rings and correlate them with environmental factors.
- To assess the potential of tree-ring delta15N as a proxy for anthropogenic nitrogen perturbations.
Main Methods:
- Analysis of nitrogen isotope (delta15N) ring series from pine and beech trees near Montréal and beech trees from Georgian Bay Islands.
- Examination of intertree and interspecies delta15N trends, accounting for sapwood-heartwood zones.
- Correlation of isotopic fluctuations with precipitation, temperature, and a proxy for nitrogen oxide (NOx) emissions.
Main Results:
- Delta15N values showed coherent trends across trees and species, reflecting local environmental conditions.
- Short-term isotopic fluctuations correlated with precipitation (positive) and temperature (negative).
- Long-term delta15N decreases (1.5–2‰) after 1951 suggest soil nitrogen changes, while a 1.5‰ increase after 1971 in Georgian Bay indicates a distinct event. Both sites showed correlation with NOx emissions proxies.
Conclusions:
- Tree-ring delta15N series can serve as a proxy for regional climatic conditions and anthropogenic perturbations of nitrogen cycles.
- Contrasted long-term delta15N changes at Montréal and Georgian Bay likely reflect varying contributions of NOx emissions from vehicles and coal-power plants.
- This research highlights the utility of tree rings in reconstructing historical environmental changes related to nitrogen pollution.
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