Atmospheric supply of trace element pollutants in the Hobart region: a comparison of two study sites

Supervisory Team:

Prof Andrew Bowie

Dr Thomas Holmes

Dr Scott Meyerink (AAPP, IMAS, University of Tasmania)

Research advisor:

Dr Morgane Perron (IUEM, France)

Brief project description:

The atmosphere transports mineral dust, bushfire particles and anthropogenic emissions from terrestrial and human sources. These aerosols contain micronutrients and pollutants which can impact marine ecosystems and affect human health. This project aims to quantify the atmospheric deposition of trace metals contained in aerosols in the Hobart region of southern Tasmania (Australia). We will use data and samples collected from a unique archive from two different study sites. Since 2016, a fortnightly sampling program has collected aerosol samples at the top of kunanyi/Mount Wellington (MW). Aerosols and rainwater samples collected on the IMAS roof since 2017 provide a second time-series for this study. This urban collection site will allow the identification of anthropogenic pollution to the atmosphere in the Hobart region and focus on anthropogenic sources (e.g., from vehicles, cruise ships, wood burning, etc). Pollution fingerprints found in IMAS rooftop samples will be compared to kunanyi/MW aerosols which may capture pollutants from Tasmania and mainland Australia upwind along the atmospheric transport pathway.

We will focus on pollutant aerosols (e.g., Pb, Cu, V, Cu), whilst also obtaining important information on lithogenic trace elements (e.g., Al, Fe, Th, Ti) and micronutrients needed for biological productivity (e.g., Fe, Zn, Mn), and how the transport of these elements may vary seasonal and interannually. If time allows, we will also examine major ions (e.g., nutrients, oxalate, sulfate) and biomass burning tracers (e.g., levoglucosan) in the IMAS roof samples. The project will use existing aerosol data from kunanyi/MW (Perron et al., 2022) and acquire new geochemical data through the analysis of aerosol and rainwater samples collected from the IMAS roof. The aerosol data will be interpreted in the context of remotely sensed aerosol deposition and atmospheric transport models.

Specific questions addressed by the project:

1. How does the particle concentration and chemical composition of trace elements vary seasonally and interannually at the IMAS roof study site, including comparison of PM sensor data at both sites?

2. Does the IMAS roof study site allow for the identification of local pollution compared to the kunanyi/MW time series site? How different is the deposition of trace elements from the IMAS rooftop compared to the more pristine kunanyi/MW sampling station?

3. What are local sources of pollution to southern Tasmania and do they mostly originate from the Hobart region or from upwind along the atmospheric transport pathway.

4. How do lithogenic tracers in aerosols (e.g., Fe, Al, Ti, Th) on the IMAS roof compare to their atmospheric dry deposition at kunanyi/MW study sites?

Skills students will develop during this research project:

The student will learn laboratory skills and techniques including acid digestion and ICP-MS trace metal analysis following GEOTRACES clean protocols. The student will also learn data processing techniques, including script-based methods (Matlab, R) associated with these analytical methods and with the analysis of remotely-sensed environmental data.

The student will also participate in field sampling at the kunanyi/ Mt Wellington sampling site and on the IMAS roof. The student will need to be comfortable working in a clean lab, have exceptional record keeping skills and attention to detail, and be familiar with basic concepts in environmental and analytical chemistry.