Dust – it can be the bane of life in the bush, getting into everything, damaging equipment, making work around the house and shed.
But it turns out we can learn a lot from dust about the Earth’s history. Every grain has a unique chemical signature that provides information both about its origin and about the chemistry of the environment in which it accumulates.
At Hamelin Pool beside Bush Heritage’s Hamelin Station Reserve in Western Australia, structures called stromatolites have been slowly growing over the past several thousand years as mats of algae, cyanobacteria and other microbes capture and cement together fine layers of dust and silt.
The chemical make up of dust grains in these layers has the potential to reveal information about Australia’s climate during the past two thousand years as dust has blown in from the continent’s interior and elsewhere. And by comparing dust from Hamelin Pool’s stromatolites with that in ancient fossil stromatolites we can learn about the Earth’s atmosphere billions of years ago. In particular recent research on the chemistry of rare earth elements such as Strontium Neodynium and Hafnium in stromatolite dust has shown that they can reveal how much oxygen was in the atmosphere at the time the grains were captured. The atmosphere first started to accumulate oxygen during the Precambrian about 3.5 billion years when cyanobacteria began producing it through photosynthesis. So research into the chemistry of dust and stromatolites at Hamelin pool can reveals details about the primordial arrival of life on Earth!
In October, Agouron Institute Post-Doctoral Geobiology Fellow Amanda Oehlert travelled to the Hamelin Reserve to work on a number of projects with Bush Heritage’s Dr. Erica Suosaari and Cat Cushenan of University of Algarve). Among the fieldwork they did was the installation of two dust collectors. They were assisted by Bush Heritage field officers Tony Loechte and Larissa Lauder and volunteers Rex George and Gail Holt.
The collectors will capture weekly samples of fine dust carried by the wind (aeolian) as well as dust grains that saltate (bounce) along the ground. Aeolian dust is transported via wind currents in the atmosphere and rains down to the ground. It can be carried vast distances, including between continents. To collect this type of dust, a bucket shaped dust collector was mounted on the top of a pole. Saltating dust will be collected with an additional collector mounted about 30cm above the ground. This has a tail that allows it to turn like a windvane so the collection port always faces into the wind. Each dust collector will be emptied weekly by Tony and Larissa to gather a set of 52 samples of each dust type.
We eagerly look forward to what the scientists discover. Dust, it’s a lot more interesting than most people imagine!