RESEARCH METHOD
Stable isotopes
δ¹³C, δ¹⁵N and related biogeochemical indicators.
01
What the method shows
Stable isotope ratios, especially δ¹³C and δ¹⁵N, integrating organic-matter sources and biogeochemical processes.
How we use it in HEL
When well-defined categories, controls and historical or archaeological context can be compared.
02
How the method works
Isotopes of the same element share chemical behaviour but differ in mass. Mass spectrometry measures their ratios and reports them as δ values relative to international standards; in soils we primarily work with δ¹³C and δ¹⁵N.
δ¹³C responds, among other factors, to the origin of organic matter and contributions from plants with different photosynthetic pathways. δ¹⁵N is sensitive to nitrogen cycling and can record manuring and other biogeochemical processes. Soil values integrate processes over time and may persist long after land use changes.
An isotope difference rarely has a single cause. Control soils, comparative categories, C/N, geochemistry and known land-use history are essential for interpretation.
C/N, soil geochemistry, vegetation and historical context, GIS and statistical group comparison.
03
In practice
- Input / materialsoil organic matter and other environmental material depending on the study
- Scale / resolutionsample, spatial zone and comparative dataset
- Sampling / preparationcontext-controlled samples with contamination-aware preparation
- Typical outputδ¹³C and δ¹⁵N values, category comparisons and spatial patterns
04
Limits and control
The signal is integrative and non-unique; manuring, vegetation, soil formation and other processes require controls and additional proxies.
Třebokov revealed a long-term agricultural imprint beneath present forest; Ravat compares prehistoric and later land use.
05
References and HEL studies
Selected studies underpinning the method descriptions and examples used by Human Earth Lab.