New publication: Potential impacts of atmospheric microplastics and nanoplastics on cloud formation processes

Mischa Aesclimann, Guangyu Li, Zamin Kanji, Denise Mitrano. Potential impacts of atmospheric microplastics and nanoplastics on cloud formation processes. Nature Geoscience. 2022 external page See full text here

Abstract:

The presence of microplastics and nanoplastics (MnPs) in the atmosphere and their transport on a global scale has previously been demonstarated. However, little is known about their environmental impacts in the atmosphere. MnPs could act as cloud condentation nuclei (CCN) or ice-nucleating partilces (INPs), afecting cloud formation processes. In sufficieint quantities, they could change the cloud albedo, precipitation and lifetime, collectively impacting the Earth's radiation balance and climate. In this Perspective, we evaluate the potential impact of MnPs on cloud formation by assessing their ability to act as CCN or IINPs. Based on an analysis of their physiochemical properties, we propose that MnPs can act as INPs and potentially as CCN after environmental aging processes such as photochemical weathering and the sorption of macromolecules or trace soluble species onto the particle surface. The actual climate impact(s) of MnPs depend on their abundance relative to other aerosols. The concentration of MnPs in the atmposhere is currently low, so they are unlikely to make a substrantial contribution to radiative forcing in regions exposed to other aerosols, either from natural sources or anthropogenic pollution. Nevertheless, MnPs wil potentially cause non-negligible pertubations in unpolluted remote or marine clouds and generate local climate impacts, particiularly in view of an increase in the release of MnPs to the environemnt in the future. Further measurements, coupled with better charcterization of the physiochemical propertiers of MnPs, will enable a more accurate assessment of the climate impacts of MnPs acting as INPs or CCN

Highlights: 

• There are several possible pathways for micro- and nanoplastics cycling in the atmosphere, from direct emissions to re-suspension from water and soil
• While microplastics and nanoplastics may be relevant for cloud droplet activation, we hypothesize this highly depends on particle aging and weathering
• Some cloud forming processes are expected to be relevant for microplastics and nanoplastics, but if they act as cloud condensation nuclei or ice nucleating particles depends on weathering state, location, and atmospheric conditions
• Many aerosols play a role in cloud formation, but the (relative) concentration of microplastics and nanoplastics compared to other (natural and anthropogenic) aerosols is key to understand how important plastics are to this process
• This has been quite an adventure to move my research out of the water and soil and learn more about atmospheric chemistry! One of the best things about working at ETH and in the Environmental Systems Science Department is collaborating with amazing scientists for transdisciplinary research