Sloshing around in mud may not be everyone’s idea of the ideal way to spend a working day but to a small group of scientists employed by the Australian Nuclear Science and Technology Organisation (ANSTO) it is par for the course as they delve into past human activity and open the door to our previous climatic conditions.
Mud, for all its dirty, slimy glory, contains a wealth of information about the environment it was formed in. Each year layers of sediment are deposited in lakes, swamps and bogs and with it pollen, algae, charcoal, the remains of microscopic animals, traces of metals and naturally occurring radioactive isotopes. Through studying these microfossils and natural radioactive isotopes it is possible to unlock the door to our past.
Dr Kate Harle from the Environment division at ANSTO is the task leader of a small group of four scientists who spend up to ten days at a time in the wilderness areas of Australia researching the contents of the cores of mud they pull up from swamps and lakes.
Her team has recently been in the south west of Tasmania analysing mud samples obtained from several small lakes. For example, in sediments from a lake in the remote Gordon River region in Tasmania the group found evidence of the impact of convict logging of Huon Pine (Lagarostrobos franklinii) during the 1820s.
They have also found evidence of increased levels of trace metals in the environment in samples derived from mining sites around Queenstown, and in some instances in samples from sites many kilometres from the actual mining operations. However, the good news is that these levels appear to have fallen in the past few years as mining companies have become more environmentally conscious.
"The work involves extracting a core sample of mud just 7cm deep from a targeted area, such as a small lake northeast of Queenstown, and being able to piece together the effects of mining in the area. The trace metals deposited in the mud through time have enabled us to see the changing levels of pollution associated with the expansion of the mining industry around Queenstown," Dr Harle said.
" The pollen has provided a clear story of deforestation in response to these increased levels of pollution as well as higher levels of burning. The algae and microscopic animals deliver evidence of changing water conditions in the lake. Charcoal has also proven particularly powerful in reconstructing the history of fire, showing that burning significantly increased with the arrival of miners in western Tasmania 150 years ago," she said.
Tasmania is not the only location where this valuable work is being done. The task team are also looking at sites in the Northern Territory, the Blue Mountains, Victoria, the Atherton Tablelands and the Antarctica for clues to our past climatic conditions and human occupation and activity.