Why are we concerned with Australian Drought?
Unlocking eastern Australia’s past climate
Working towards answers
The two main research areas for my thesis are: 1) evaluate the paleoclimate of the eastern subtropics of Australia by utilizing stable isotopes, and 2) create a modern hydrological model of the Coalstoun Lakes system using a mass balance approach. These research focuses will be accomplished utilizing an assortment of samples (ie: vegetation, a 4.5 m sediment core, two species of snail shells, and soil samples) which were collected by a variety of scientists over several years. In addition, future plans are in motion to extract two pairs of cores from both lakes approximate depth of 15 m, covering nearly 150,000 years of climate. My intended focus is on stable isotopes from sponge spicules but I have taken advantage of an available core (thanks to efforts from Mike Evans and Kevin Welsh) to look at some carbon isotopes also.
To start my project off on the right foot, in mid-September I undertook a three week stint at the British Geological Survey’s Stable Isotopes Facility and the University of Nottingham under the advisement of Prof. Melanie Leng and Dr. Matthew Jones, respectively. The first two weeks at BGS were focused on preparing and weighing vegetation and sediments to be analyzed for organic carbon isotopes, along with any calcium carbonate containing layers for bulk oxygen isotopes. With any additional time between running samples, I began sampling on a snail shell. In short, snails consume moisture from rainfall which is incorporated in the structure of its aragonite based shell. As, the organism grows it retains the oxygen isotope allowing us to reconstruct the precipitation variability over its lifespan (~10 yrs). We selected one species of snail (biggenden banded snail) and began the intricate sampling by drilling 0.8 mm holes into the shell. In all, 200 samples were attained from the apex (oldest section of the snail) to the outer rim. Samples were carefully collected perpendicular to the growth bands simultaneously recording all flaws or cracks to aid in data interpretation. Results of the analysis will not only give us insight on the modern climate, but it will also provide us with an interesting perspective on the local biology and lifecycles of the Biggenden Band Snail that has yet been documented.
During my final week, I spent acquiring information on hydrological and isotopic modeling at the University of Nottingham. I focused my attention on developing an experimental design and setup to aid in model selection. Specifically, I annotated manuscripts utilizing mass balance approaches help in my understanding of model sensitivity and complexity. This prompted discussions on future sampling procedures and instrument set up that will optimize our modeling efforts.
My time at BGS and the University of Nottingham has provided a fantastic opportunity to work with an interdisciplinary group of scientist. In the future, I hope continued collaboration is possible to help guide my academic growth and cementing the techniques and skills needed for coupling of both hydrologic and isotopic disciplines. As the preliminary data are continued to be analyzed, we begin to piece together the intricate past of Australia’s drought history. With any luck, the implications of our work will directly address frequency, severity, and duration of drought hazards and future climate scenarios we may face.
Nick Patton is a PhD student at the University of Queensland, working in collaboration with Prof Melanie Leng and Dr Matt Jones (BGS and University of Nottingham).
Twitter @NickRPatton, webpage: nicholasrpatton.weebly.com