SNSF Ambizione MACrAA
Macromolecular aerosols in the cryosphere from the Arctic to the Alps (MACrAA)
The idea behind MACrAA
During combustion, tiny particles and gases are emitted, many of which are not known to date. This is because there are no methods to analyse them comprehensively, especially as the molecules, which are created during combustion, react with each other and with other molecules in the environment to produce a huge variety of molecules, many of which are very large macromolecules. Because it is difficult to follow the molecules and their reactions in the environment, the fraction of particles that can be analysed becomes smaller and smaller with time and as they age. This makes it difficult to detect them with contemporary methods. The objective of this project is to develop methods to analyse aerosol particles which cannot currently be analysed.
The idea behind this project is a method that stems from polymer chemistry and will allow to look into particles like polymers, more broadly known as microplastics - thereby a broad spectrum of aerosols can be analysed. The method we plan to develop will hopefully allow to better analyse many such large molecules.
The interest in the project is not just of scientific nature but also because of the possible influence on climate and health. Aerosol particles can be the seed for clouds which reflect sunlight and have a cooling influence. Other types of particles are quite dark so they absorb sunlight and heat up the atmosphere a bit more, especially when they are deposited on a lighter surface like on the Arctic’s snow and ice. The project’s focus is therefore on the cryosphere such as the Arctic and Alps where bright surfaces like snow and ice are prevalent.
The direct impact of this method is that new chemical tracers (found in the environment) will be used as chemical fingerprints which can be traced back to predecessor molecules and their specific sources. This allows to identify the origins of pollutants which are potentially harmful for health and climate. The analysis of macromolecules allows to trace them back to their original source. An example would be wood combustion, i.e. the burning of wood results in large molecules, which could then be traced back to wood combustion. This method could then be used in all kinds of samples, like ice cores or sediments, which may lead to information like historical changes in global fire behaviour, linked to changes of human behaviours, which affect health as well as the climate.
First year results
1. To establish a reference data set for the analysis with our new method, we analyzed 11 years of Jungfraujoch filter samples using our state-of-the art mass spectrometers (EESI-L-ToF, EESI-Orbitrap and AMS-L-ToF), with a method that was previously developed at PSI-LAC and has become a gold-standard in our lab (Daellenbach et al. 2016). Data analysis is currently in progress.
2. In collaboration with the Aerosol Group at the Institute for Sensors and Electronics at University of Applied Sciences and Arts Northwestern Switzerland (FHNW), we built a pyrolysis oven prototype, which will be the core of our new method development.
3. During the summer of 2023, we joined the Swiss Polar Institute Flag Ship project GreenFjord, to collect aerosol particles (PM2.5 and PM10) in southern Greenland.
4. We succesfully concluded PSI's first ever crowdfunding campaign, to cover the cost for the analysis of Saharan dust events and wildfire events in our Jungfraujoch samples.