Topic status: In progress
Sea salt (SS) particles produced naturally by bubble bursting processes on the ocean surface contribute significantly to the global aerosol load. Therefore they have a significant effect on the Earth’s climate through the way they scatter and absorb solar radiation and form clouds. Recent studies have shown that during the bubble bursting process an organic coating is imparted from the ocean surface onto the SS particles. This organic component can have a potentially large effect on the climatic influence of SS particles by altering their ability to form cloud droplets. Recent studies have attempted to quantify the size resolved organic fraction of SS particles through sampling SS aerosol produced under controlled conditions (bubble chambers) onto filters that are subsequently chemically analysed offline to determine organic fraction. These methods are limited by the ability of capturing sufficient mass of the smallest SS particles (<200nm) onto filters and therefore they are unable to accurately quantify the organic fraction of these smallest, and most numerous, SS particles.
The organic fraction of these smallest SS particles can be measured online using a VHTDMA system. QUTs VHTDMA system measures the size changes resulting from the heating and/or humidification of nanoparticles 7-120nm in diameter. This information can be combined to calculate the percentage of organics present in SS particles. In addition to the VHTDMA system an Aerosol Time of Flight Mass Spectrometer (ToF-AMS) will be used to investigate the chemical composition of the organic fraction. The VHTDMA will provide the percentage of organics present in SS particles while the AMS will provide the composition of the organic fraction.
The student will:
- collect appropriate samples of seawater from various places around Brisbane (i.e Moreton Bay, Pacific Ocean of the coast of Gold Coast, etc.)
- undertake laboratory measurements using the bubble-bursting chamber to determine the organic fraction in various water samples and under various conditions
- analyse the results and write a scientific report.
Dependence of the organic content and composition on the origin of the seawater samples (Bay, Open Ocean, Estuary, etc.). A manuscript will be prepared for the submission into a peer reviewed journal.
Duration of project
8 weeks split into 2 4week components. The first component will be conducted from mid November to mid December 2011. The second component will be conducted from mid January to mid-February 2012.