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Research Topics within Earth Environment
Our research draws upon a unique group of World-class research facilities that enable the analysis of a wide range of trace element and isotopic systems, with an emphasis on the timing and rate of change of major environmental and Earth surface processes. Emphasis is placed on developing diagnostic environmental proxies within an absolute chronologic framework that spans a few tens to several hundred thousand years of the Earth's history, and to use these as a basis for understanding past and present environmental change and predicting future trends. Earth Environment specialises in the reconstruction of high-resolution environmental records from growth banding preserved in fossil and modern corals, speleothems (cave deposits), layered sedimentary deposits and anthropologic sites of special significance.
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Earth Environment Research Topics
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Radiocarbon is produced in the stratosphere by the collision of nitrogen atoms with thermal neutrons produced naturally by cosmic rays or artificially by atmospheric nuclear bomb testing. Atomic 14 C is rapidly oxidized to 14 CO 2 in the atmosphere and enters plants and animals via photosynthesis and the food chain. When an organism dies the 14 C decays back to Nitrogen 14. The half-life (the time it takes for half of the carbon-14 to decay) is 5730 years. After about 10 half-lives there is essentially no carbon-14 left in a sample. This results in a limit of this technique of 50-60,000 years, after which other radiometric techniques have to be used to age a sample. |
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The Indian Ocean Dipole is now recognised as a climate system of international importance because of its effect on rainfall in Indonesia, Australia, Asia, and East Africa. Resolving the debate about how the Dipole and ENSO climate systems interact, and how they respond to different background climates, is essential for understanding the nature of drought in southern Australasia. |
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Sea level is a major key to understanding the system because it varies with the volume of the icecaps. Recently we found that sea level rises of 9-16 m accompanied Heinrich events during the period 30 - 65 ka, when abrupt climate changes were particularly strong. Based on evidence in coral terraces at Huon Penisula, Papua New Guinea |
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Paleogeographic reconstructions indicate that parts of the Australian continent have been exposed above sea level for hundreds of millions of years. A range of dating methods are being used to investigate the age of regolith in selected regions.
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The primary focus of the ocean chemistry group within Earth Environment is on understanding the behaviour of trace elements and isotopes in ocean, their sources and sinks and the role they play in biological systems. Microscopic plankton form the base of the marine food-chain and account for more than half of global primary production, and hence modulate our climate through the ocean's ability to drawdown CO 2 . |
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