DoctorGeorge Rowland

Project Total: $0; The project aims to quantify dust deposited in remote regions of the Southern Indian Ocean using the geochemistry of marine sediment cores and measurements of anthropogenic radionuclides. Mineral dust is a key source of nutrients for remote ocean ecosystems, yet is very poorly constrained, especially in the Southern Ocean. This dust is thought to be a key factor driving how much CO2 is stored in the ocean, and so is critical to constrain for studies of future and past climates. The project will assess the question: what are the magnitudes, spatial distributions and sources of dust to the Southern Indian Ocean during the late-Holocene and present-day? Additional objectives to assess: - the importance of dust for sustaining marine ecosystems - The degree of agreement between dust models and the new geochemical reconstructions. - the flux of plutonium fallout to the deep ocean, contributing to global databases in a rarely sampled location. Marine sediment cores (held at UTAS) spanning a wide spatial range from near Western Australia to the remote Southern Indian Ocean will be targeted to provide the best estimates of dust deposition gradients by combining geochemical proxies measured at UTAS with a novel application of plutonium measurements measured at ANSTO. Because plutonium is deposited in the ocean from atmospheric fallout with aerosols I will use the spatial pattern, quantity, and isotopic composition of plutonium to understand dust deposition in the remote ocean. Geochemical measures made routinely at our UTAS lab can allow us to quantify fluxes of Pu to the deep ocean an important but under constrained parameter. Funded by: Australian Nuclear Science & Technology Organisation - Grant-Access to Major Research Facilities Program; University of Tasmania.

Project Total: $16,997; The project will reconstruct the sources of terrigenous material deposited in the southern Indian Ocean over the last glacial cycle by measuring radiogenic isotope composition (Nd, Pb, Sr) of the detrital sediment.The project aims to: Determine an end-member 'fingerprint' for Australian-derived dust and use this to deconvolve the primary lithogenic sources to the remote southern Indian Ocean Identify how sources of dust alter during periods of climatic change (e.g., last glacial maximum) Evaluate existing source apportionment dust model experiments and compare with radiogenic isotope data in other regions of the Southern Ocean and in Antarctic Ice cores Funded by: Australian and New Zealand International Ocean Drilling Program Consortium - Grant ($16,997); University of Tasmania.

Project Total: $3,400; The input of dust to remote the remote Southern Ocean has been identified as a crucial yet largely unquantified parameter involved in ocean biogeochemical cycles and past climate changes. Using a set of marine sediment cores from the Southern Indian Ocean I will reconstruct the flux of dust deposited in this region by combining a suite of established geochemical tracers of dust with new measurements of anthropogenic radionuclides. In this ANSTO access project I will use specialist facilities at ANSTO toanalyse plutonium isotopes in the sediments. This will provide a novel tracer of atmospheric inputs as plutonium is deposited on the ocean alongside aerosols. Measuring the concentration and isotopic composition will allow me to establish both the amount and the source of atmospheric inputs to the region. Existing geochemical (230Th) data for these cores will allow me to quantify spatial pattern of plutonium fluxes in a very remote ocean setting with no existing estimates. This project is therefore important for studies of environmental radioactivity/nuclear industry as well as marine sciences and climate. I will compare plutonium fluxes to those of natural radionuclides (232Th) and other tracers to scrutinise the different geochemical approaches and quantify aerosol inputs from different sources. These inputs are currently poorly constrained but are important for ocean biology and climate. Funded by: Australian Institute of Nuclear Science & Engineering - Grant-Early Career Researchers ($3,400); University of Tasmania.