PT Section Seminar: Dr Bryan Bzdek
Dr Bryan Bzdek
"Atmospheric Nanoparticle Formation, Growth, and Activation to Cloud Droplets"
Dr Bryan Bzdek (University of Bristol)
Atmospheric aerosols impact human health and global climate. With respect to climate, aerosols are mainly thought to cool Earth’s surface either directly by scattering sunlight back into space or indirectly by serving as the seeds for cloud droplets and modifying the reflectivity of clouds. Although the climate impacts of greenhouse gases are well understood, those of aerosols are poorly constrained. A better understanding of aerosol impacts on climate is required to reduce uncertainty in anthropogenic climate effects. An important contributor to atmospheric aerosol loading is new particle formation, where gas phase species nucleate to form new particles that rapidly grow to climate-relevant sizes and can ultimately serve as the seeds for cloud droplets. The chemical mechanism governing new particle formation is poorly constrained due to the small size of atmospheric nanoparticles. As a result, it is difficult to predict the contribution of new particle formation to ambient aerosol concentrations. This presentation will discuss measurements of the chemical composition, reactivity, and energetics of atmospherically relevant clusters and ambient nanoparticles using a range of mass spectrometry approaches, shedding new light on how atmospheric particles grow in the atmosphere. Once grown to a critical size, atmospheric particles can activate to serve as the seeds for cloud droplets. A key parameter governing the activation process is the particle surface tension, which is a poorly known quantity and is typically assumed to be equivalent to that of pure water. A novel approach to directly measure the surface tension of picolitre droplets enables determination of surface tension at compositions inaccessible to bulk approaches and helps to constrain the value of surface tension in ambient aerosol.
Dr Tom Oliver
School of Chemistry
Ph: (0117) 928 7668