Germanium gamma-ray spectrometer for high resolution dating of lake sediment records

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Over the last ~150 years human activities have altered many ecosystem processes to the point that the concept of the “Anthropocene”, a geological period where people are a dominant force shaping planet Earth, has become widely accepted. To study how humans have altered freshwater resources in the Anthropocene we need to reliably date natural archives of these changes (such as lake sediments) at timescales relevant to major human impacts on these resources. The dating of lake sediments using gamma-ray spectroscopy is based on the analysis of 210Pb (a radioistope with a half life of ~22 years) and sister radionuclides of the uranium (238U) decay series. This technique of dating lake sediment cores is well established, robust, and widely used to track environmental changes over the last ~150 years. In addition to the analysis of 210Pb, gamma-ray spectroscopy also measures an additional independent chronological marker of the human produced 137Cs that peaks at the height of atmospheric testing of nuclear bombs (~1962). Our proposed project will allow for the purchase of a cutting-edge gamma-ray spectrometer that will be housed at Carleton University and be widely used by environmental change researchers at Carleton, York, and Mount Allison universities as well as Environment Canada. This cutting-edge gamma-ray spectrometer technology will double our chronological resolution, reduce age estimation errors, and cut our current costs of dating lake sediment records by ~80% allowing for more of our research funding to be spent on the direct training of both undergraduate and graduate students.