Name: Anthony David

Position: PhD Student, Research School of Earth Sciences, Australian National University

Area of study: Marine geochemistry

Project: Modelling Early Diagenesis of Magnesium Calcite in Sediments of the Curtis Channel in the Great Barrier Reef

What does that mean??

Environmental systems are usually very difficult and expensive to monitor. This is particularly true if we want to completely understand a system. Completely monitoring past systems is impossible. Modelling allows scientists to study a representation of the system and allows them to vary parts of that representation without disturbing or destroying the real system. For example, testing what really happens when a 10km-wide object strikes the earth at supersonic speeds is probably not something scientists would get funding for, unless they make friends with a bald man who likes fluffy white cats.

Diagenesis describes physical and chemical changes to sediments after they are deposited. I will be developing a mathematical model of the diagenesis of magnesium calcite in sediments in the south of the Great Barrier Reef on the scale of a few decades. Magnesium calcite is chemically similar to calcite(CaCO3), except Magnesium(Mg) atoms substitute for some of the Calcium(Ca) atoms in the calcite crystal structure. In simple terms, The ratio between Mg and Ca varies according to how the calcite is formed (organic or inorganic), the type of organisms forming the calcite(if organic) and environmental factors such as temperature, salinity and pH. One of the keys to success is identifying the minimal set of these factors that contribute to a model. This is verified by identifying and minimising uncertainties in the input factors (model parameters) and the accuracy of the model output.

Naturally the model inputs must be based on the actual environment (or a reasonable approximation) and results have to be compared with what is actually happening in the reef environment. I will generally be using results of other people’s field and lab work. If the opportunity for me to get out and see the location in person, I’ll jump at it.

How did I get here?

After practically frittering away free education in the 70s on a near-complete Botany/Computer Science degree, spent over 30 years following the “Siren call” of IT. Boyhood dreams of science bubbled to the surface during a life and career re-evaluation early this century. Did a BSc(REM) Hons, ANU degree part-time. Dreams of traipsing through the wilds in pursuit of science were tempered by a determination to do some serious mathematics with the science. Combining maths with career skills means spending most of any “science-time” tapping on a keyboard rather than tapping on an outcrop.

Where will I go?

Part-time PhD is a long slog. At worst, I will spend the same amount of time doing it as it took to complete my part-time undergraduate degree. Getting through it all with some good work behind me is my primary focus. I am already working in the field of High Performance Computing which can partly be attributed to my study thus far. Specialising in projects involving science and computing in the future would be my optimum outcome.