Monash University scientists Dr Andrew Tomkins and Dr Sasha Wilson, who were part of the team that have discovered 2.7 billion year old micrometeorites preserved in ancient sedimentary rocks, an example of which is shown in the background. This research team have recognised that fossil micrometeorites sampled the chemistry of the Earth's ancient upper atmosphere, opening a new avenue for investigating atmospheric evolution in deep time. Credit: Steven Morton
Using the oldest fossil micrometeorites – space dust – ever found, Monash University-led research has made a surprising discovery about the chemistry of Earth’s atmosphere 2.7 billion years ago.
The findings of a new study published today in the journal Nature – led by Dr Andrew Tomkins and a team from the School of Earth, Atmosphere and Environment at Monash, along with scientists from the Australian Synchrotron and Imperial College, London – challenge the accepted view that Earth’s ancient atmosphere was oxygen-poor. The findings indicate instead that the ancient Earth’s upper atmosphere contained about the same amount of oxygen as today, and that a methane haze layer separated this oxygen-rich upper layer from the oxygen-starved lower atmosphere.
Dr Tomkins explained how the team extracted micrometeorites from samples of ancient limestone collected in the Pilbara region in Western Australia and examined them at the Monash Centre for Electron Microscopy (MCEM) and the Australian Synchrotron.
‘Using cutting-edge microscopes we found that most of the micrometeorites had once been particles of metallic iron – common in meteorites – that had been turned into iron oxide minerals in the upper atmosphere, indicating higher concentrations of oxygen than expected.
‘This was an exciting result because it is the first time anyone has found a way to sample the chemistry of the ancient Earth’s upper atmosphere.’
Imperial College researcher Dr Matthew Genge – an expert in modern cosmic dust - performed calculations that showed oxygen concentrations in the upper atmosphere would need to be close to modern day levels to explain the observations.
‘This was a surprise because it has been firmly established that the Earth’s lower atmosphere was very poor in oxygen 2.7 billion years ago; how the upper atmosphere could contain so much oxygen before the appearance of photosynthetic organisms was a real puzzle,’ Dr Genge said.
Dr Tomkins explained that the new results suggest the Earth at this time may have had a layered atmosphere with little vertical mixing, and higher levels of oxygen in the upper atmosphere produced by the breakdown of CO2 by ultraviolet light.
‘A possible explanation for this layered atmosphere might have involved a methane haze layer at middle levels of the atmosphere. The methane in such a layer would absorb UV light, releasing heat and creating a warm zone in the atmosphere that would inhibit vertical mixing.
‘It is incredible to think that by studying fossilised particles of space dust the width of a human hair, we can gain new insights into the chemical makeup of Earth’s upper atmosphere, billions of years ago.’
Dr Tomkins outlined next steps in the research.
‘The next stage of our research will be to extract micrometeorites from a series of rocks covering over a billion years of Earth’s history in order to learn more about changes in atmospheric chemistry and structure across geological time. We will focus particularly on the great oxidation event, which happened 2.4 billion years ago when there was a sudden jump in oxygen concentration in the lower atmosphere.’
A film about Dr Andrew Tomkins and his research is available here.
- ‘World's oldest fossil micrometeorites ever found contain hints of oxygen in early Earth's atmosphere’ on ABC News online, Thursday 12 May 2016
- 'Fossilised space dust offers startling insight into our ancient atmosphere', on News.com.au, Thursday 12 May 2016.
- 'Meteorite dust changes theory of life's origin', on The Australian online, Thursday 12 May 2016.
The Australian Synchrotron’s X-ray Fluorescence Microscopy beamline shows the concentration and distribution of zinc in a cross-sectioned grain of rice with no treatment (left) and a grain of rice following soaking in water at 90˚C followed by steaming (right).
Efforts to address chronic malnutrition in billions of people have taken a step forward with Australian researchers defining processing conditions that boost the nutritional value of white rice – the staple food of more than a third of the world’s population.
While it is known parboiling grains before milling helps retain essential micronutrients, researchers from Charles Sturt University (CSU) and the NSW Department of Primary Industries (DPI) have used the Australian Synchrotron to compare parboiling techniques, showing in the LWT – Food Science and Technology journal that longer parboiling processes at higher temperatures cause more micronutrients to migrate from the outer bran layer into the starchy core of the grain.
Dr Peter Torley, Senior Lecturer Food Science and Technology at RMIT University and formerly of CSU, says the Australian Synchrotron’s X-ray Fluorescence Microscopy beamline has enabled researchers to accurately track the diffusion of nutrients at sub-micron resolution levels without damaging the rice grain’s internal structure.
‘Using the powerful and tightly-focused synchrotron beam meant we didn’t have to grind the rice to prepare our samples, which is necessary when using standard laboratory equipment, enabling more accurate interpretation as we could plot essential micronutrients to their precise locations within the grain, before and after parboiling.
‘Of the approaches in our experiments, soaking in water at 90˚C followed by steaming proved to be the most effective for retaining nutrients.’
White rice – prepared by drying and milling rice kernels, a process that strips the outer bran containing most of the nutrients, including iron, manganese, potassium and zinc – provides up to 80 per cent of the total caloric intake for people in some regions of the world, such as South-East Asia. Over two billion people, or 30 per cent of the world's population, suffer from iron deficiency with symptoms ranging from poor mental development in children to depressed immune function and anaemia.
NSW DPI researcher Mr Prakash Oli, lead author of the recently published paper and CSU PhD candidate, says the findings will have significant implications for rice production as researchers work to address micronutrient deficiency around the world.
‘Improving rice processing is one of two approaches we’re working on to combat widespread malnutrition; the second involves fine-tuning rice species to express more iron and other important nutritional minerals in the grain core during growth and during soaking, which can also reduce the glycaemic index (GI) of white rice.
‘Optimising rice processing is also important for farmers and industry as grain breakage during milling can cause crop value to plummet to as little as one per cent, something parboiling can help to avoid.’
Dr Laura Pallas, Rice Chemist at the NSW DPI, says changing global rice processing and eating habits is an enormous task, as there are deeply entrenched expectations across various cultures around consistency and flavour, and different approaches to parboiling ranging from those in small home farms to large industrial plants.
‘Rice is the closest thing we have to a global dish and it is gluten-free and a good source of complex carbohydrates.
‘If we can combine the higher micronutrient content of brown and coloured rice varieties with the light and fluffy texture of white rice, we could reach the holy grail: a rice version of “wonder white” bread that people, everywhere, really want to eat.’
This research was supported by the New South Wales Industry Synchrotron Access Scheme, supported in turn by the Office of the Chief Scientist NSW. The support of the NSW Department of Primary Industries in submitting the proposal to the New South Wales Industry Synchrotron Access Scheme is also acknowledged.
- ‘Aussies zap rice to find its vitals in search for a wonder white’, The Australian online, Thursday 28 April 2016.
Dr Rachel Popelka-Filcoff, an Australian Institute of Nuclear Science and Engineering (AINSE) Senior Research Fellow; image courtesy of Flinders University
The first non-destructive analysis of Australian Aboriginal ochre artefacts using advanced X-Ray technology has paved the way for more accurate cultural mapping and new insights into the origin and style of Indigenous artworks.
While European-style artworks have been analysed using X-Ray Fluorescence Microscopy (XFM) techniques, the new research kickstarts ‘hands off’ high-tech analysis of Aboriginal Australian art, beginning with a boomerang and a bark painting from the South Australian Museum's Australian Aboriginal Culture Collection.
Lead researcher Dr Rachel Popelka-Filcoff from Flinders University says the sensitive analysis of ochre-decorated objects using the XFM beamline at the Australian Synchrotron will help researchers better understand the cultural uses and techniques of Indigenous art and artefacts.
‘Relatively little is understood about the procurement, composition, and mixing of the natural mineral pigments that have been used in Aboriginal Australian objects.
‘This new method provides higher resolution information and an alternative to traditional destructive testing, while returning the object unharmed to the museum collection.’
In Indigenous communities, from human habitation of Australia to contemporary communities, ochres of many colours are used with wood and bark for cultural expression and exchange of ideas and knowledge.
Dr Popelka-Filcoff, an Australian Institute of Nuclear Science and Engineering (AINSE) Senior Research Fellow who has previously analysed more than 150 different kinds of ochre used around Australia, says high-resolution maps of pigment application generated at the Australian Synchrotron investigate the layering and application of ochre minerals without physically removing samples from the object.
‘Investigating the fine lines and dots in many Aboriginal objects, this technique has unparalleled resolution over other existing techniques, allowing further insights into the composition, application and layering of natural pigment on the micron scale.
‘The findings from across Australia will help to reconstruct ancient exchange routes, build on the existing provenance of Aboriginal art and objects, and help conservation and authentication studies.’
Dr David Paterson, Principal Scientist on the X-ray fluorescence microprobe at the Australian Synchrotron says the use of a highly sensitive and very efficient X-ray detector allows the radiation dose, particularly on these very old objects, to be as low as possible.
‘By using the powerful X-ray fluorescence microprobe for this research experts could gain more accurate data on the composition of the mineral pigments, much faster than other traditional X-ray methods, without damaging the ochre.’
- ‘Advanced x-ray analysis paints Indigenous artefacts in a new light’ on ABC radio’s ‘AM’, Friday 1 April 2016
- ‘Aboriginal ochre fingerprinting helping researchers trace ancient Indigenous trade routes’ on ABC news online, Thursday 31 March 2016