The doctoral dissertation in the field of Aerosol Physics, will be examined at the Faculty of Science, Forestry and Technology, Kuopio campus.
What is the topic of your doctoral research? Why is it important to study the topic?
My doctoral research investigates ecosystem-scale emissions of biogenic and agricultural aerosol precursors into the boreal atmosphere, focusing specifically on volatile organic compounds (VOCs) such as isoprene and terpenes, and ammonia (NH₃). The study employs advanced measurement techniques, including chemical ionization mass spectrometry (CIMS) and the eddy covariance method, to quantify real-time atmospheric emissions from boreal wetlands and agricultural fields. These aerosol precursors are key drivers of air pollution, cloud formation, and climate change. Understanding their emissions is crucial, especially in boreal regions that are warming four times faster than the global average. Quantifying emissions at the ecosystem level improves the accuracy of climate models and helps assess the feedback effects of global warming on atmospheric chemistry.
What are the key findings or observations of your doctoral research?
Boreal wetlands emit much higher levels of isoprene and terpenes than previously assumed, with a fivefold increase in temperature sensitivity for isoprene emissions. Sedges, a dominant wetland plant, were found to be a primary source of this strong temperature response. The research led to updates in the MEGAN emission model, projecting a 20% increase in isoprene emissions during 2000–2009, particularly during heatwaves. A novel benzene-based ionization method was developed to improve the detection of ammonia emissions from agricultural fields. NH₃ emissions from solid fraction of cow manure showed greater temperature dependence than traditional slurry-based applications.
The results highlight that climate warming will likely amplify these emissions, leading to increased aerosol and ozone formation. This could affect air quality, climate forcing, and human health. The study's novel methodologies improve our ability to monitor emissions more accurately and inform climate models, agricultural practices, and environmental policy.
How can the results of your doctoral research be utilised in practice?
Climate models can now incorporate updated temperature sensitivity parameters to improve predictions of aerosol formation. Agricultural policymakers and practitioners can reassess manure management strategies to reduce ammonia emissions. The research supports EU and global air quality regulations by providing more accurate emission data for inventories.
What are the key research methods and materials used in your doctoral research?
The research used ecosystem-scale eddy covariance measurements combined with cutting-edge mass spectrometry to monitor aerosol precursor fluxes. Field campaigns were conducted in: Siikaneva, a boreal wetland, to measure biogenic VOC emissions; Viikki, an agricultural research station, to monitor NH₃ emissions following manure application. Additionally, high-performance computing, lab experiments, and model simulations (MEGAN) were used to analyze, calibrate, and interpret data collected from high-resolution field instrumentation.
The doctoral dissertation of Lejish Vettikkat Parameswaran, MSc, entitled Ecosystem-scale emissions of biogenic and agricultural aerosol precursors into the boreal atmosphere will be examined at the Faculty of Science, Forestry and Technology, Kuopio Campus. The opponent will be Professor Steffen M. Noe, Estonian University of Life Sciences, Estonia, and the custos will be Professor Siegfried Schobesberger, 91. Language of the public defence is English.
For more information, please contact:
Lejish Vettikkat Parameswaran, lejivett@uef.fi, tel. 050 478 0742
- Public examination
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