δ 15 N
δ 15 N or Delta-N-15 is in the geochemistry , palaeoclimatology and Palaeoceanography a measure of the ratio of stable nitrogen - isotope 15 N to 14 N in a test sample . It is defined as:
In this isotope test , the 15 N content of the sample is compared with the 15 N content of a standard, i.e. the isotope ratio is determined. In this way, various aspects of the nitrogen cycle can be examined. They are: The mixing rate of an introduced nitrogenous substance with a deviating 15 N content and the rate at which nitrogen is absorbed or converted by the ecosystem. In this way, enrichment and depletion processes can also be made quantifiable.
Nitrogen is a component of nutrients that are important for plant metabolism and are also industrially produced in the form of nitrogen fertilizers in order to increase the yield of crops. Nitrogen in the form of amino acids is used by plants and animals to build proteins . It enters the body of herbivores via the food chain . Thus the nitrogen exchange between plants and animals can also be investigated by examining δ 15 N.
A study carried out in the mountain region of Kilimanjaro , for example, revealed a significantly changed δ 15 N signature due to climate change and intensive use as pasture land . While this is normally 3.5 ‰ there, values of 6.5 ‰ were found in heavily affected regions.
See also
Individual evidence
- ↑ David Robinson: δ 15 N as an integrator of the nitrogen Archived from the original on September 3, 2013. (pdf) In: TRENDS in Ecology & Evolution . 16, No. 3, March 2001. Retrieved June 22, 2016.
- ↑ Michael Zech, Carolin Bimüller, Andreas Hemp, Cyrus Samimi, Christina Broesike, Claudia Hörold & Wolfgang Zech : Human and climate impact on 15N natural abundance of plants and soils in high-mountain ecosystems: a short review and two examples from the Eastern Pamirs and Mt. Kilimanjaro . In: Isotopes in Environmental and Health Studies . 47, No. 3, July 2011, pp. 286-296. doi : 10.1080 / 10256016.2011.596277 .