Emissions and Isotopes

Understanding the generation and evolution of greenhouse gases and other air pollutants is the first step for their reduction and therefore essential for our climate, health and well-being. This, however, requires precise knowledge of the involved source and reduction processes.

The Group for Emissions and Isotopes provides analytical tools and technical know-how for the characterization and quantification of air pollution. We serve the industry, policy makers and the public with a thorough understanding of anthropogenic and natural emissions. Our main activities focus on the analysis of trace gases and their isotopes to quantify emissions, identify precursors and trace transformation pathways. An overview of ongoing project activities can be found below.

Nitrous oxide isotopic analysis


Trace-N2O: N2O from the Swiss midlands – regional sources and hot spots

Global N2O cycle: Assessment of the global N2O budget based on seasonal and long-term isotope measurements at Jungfraujoch and the Cape Grim Air Archive

Clumped isotopes as a novel tracer for the N2O cycle

ISOMOL: Advanced understanding of autotrophic nitrogen removal and associated N2O emissions in mixed nitritation-anammox systems through combined stable ISOtopic and MOLecular constraints

Methane isotopic analysis


Real-time analysis of δ13C- and δD-CH4 in ambient air with laser spectroscopy

High-precision analysis of doubly-substituted "clumped" methane isotopologues 13CH3D and 12CH2D2 with laser spectroscopy

STELLAR: Stable isotope metrology to enable climate action and regulation

CLUMPME: Clumped isotopes of methane and dolomite to assess the thermal history of orogens and the origin of thermogenic methane 


Ammonia and greenhouse gas emissions from agriculture


EVS: Emissionsversuchsstall - Experimental dairy housing for quantifying methane and ammonia emission abatement strategies under entire herd conditions

Carbon dioxide isotopic analysis


CO2 isotope measurements at Jungfraujoch









Completed projects

  • Laboratory studies: N2O emissions and isotopic signatures from abiotic processes and soil and wastewater incubation experiments.
  • Ambient N2O studies above grassland and from pristine soils.
  • HIGHGAS: Metrology for High Impact GreenHouse GASes.
  • FOCAWIN I + II: Fossil carbon dioxide emissions from waste incineration facilities. The determination of biogenic vs. fossil CO2 emissions during waste incineration by 14CO2 analysis.
  • GASOMEP: Current status and new concepts of gasoline vehicle emission control for organic metallic, and particulate non-legislative pollutants (GasOMeP)
  • EMPAIREX: Emissions of Particulate and gaseous pollutants in AIRcraft engine EXhaust
  • EMIRI: Ammonia and PM10 emission of naturally ventilated dairy housing with solid floor and an outdoor exercise area in Switzerland.
  • ESAS: Ammonia and PM10 emission from closed housing and housing combined with open exercise yards for growing-finishing pigs.
  • SIRS: Metrology for stable isotope reference standards
Dr. Joachim Mohn

Dr. Joachim Mohn
Group Leader Emissions & Isotopes
503 - Air Pollution / Environmental Technology

Phone: +41 58 765 4687

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