Radioanalytical techniques for quaternary dating

该研究计划的全球长期目标是：（1）开发新的放射化学分析技术和（2）应用改进的放射性测量技术测定第四纪环境样品的年代。 当事件发生的时间比有记载的历史更早时，确定环境样品的年龄并不简单;然而，它对环境科学的许多方面都很重要。 许多环境过程的历史年表可以通过老化样品来建立。 例如，使用地球化学理论解释的大气和地下水迁移以及岩石和沉积物年龄可用于重建时间趋势，确定环境变化速率，并测试环境过程模型。 放射性测年法可以利用原子核的放射性衰变或以恒定和已知速率发生的核反应产生给定同位素的速率来获得。 许多年轻的第四纪样品的年代测定已被证明是困难的，因为在封闭系统中进行高精度测量是不可能的。 在较旧的系统中，准确的日期往往被证明是困难的，因为大多数14 C已经衰变或最初的活动是不确定的，其他技术往往违反了封闭系统的要求。 这项研究将为测量放射性核素提供新的方法，并为涵盖广泛年龄的第四纪物质提供更强大的测年技术。 这些技术将用于环境评估、气候变化研究、生态影响报告和其他应用，在这些应用中，必须观察系统的长期行为以及人类和自然事件对该系统的影响。

The global long-term goals of this research program are: (1) to develop new radiochemical analytical techniques and (2) to apply improved radiometric techniques for dating environmental samples from the Quaternary. The determination of the age of environmental samples is not simple when events are older than recorded history; yet it is fundamental to many aspects of environmental science. Historical chronologies of many environmental processes can be developed by aging samples. For example, atmospheric and groundwater transport, as well as rock and sediment ages, interpreted using geochemical theories, can be used to reconstruct temporal trends, to determine rates of environmental change, and to test models of environmental processes. Radiometric dates can be obtained using either the radioactive decay of a nucleus or the rate of production of a given isotope by a nuclear reaction that occurs at a constant and known rate. The dating of many young Quaternary samples has proven difficult because high precision measurements on closed systems are not possible. In older systems, accurate dates often prove difficult because most 14C has already decayed or the initial activity is uncertain, and other techniques often violate the requirements of a closed system. This research will provide new ways to measure radionuclides and more robust dating techniques for Quaternary materials covering a wide range of ages. These techniques will be used to in environmental assessments, climate change studies, ecological impact statements and other applications where it is important to look at the longer term behaviour of a system and the impact of human and natural events on that system.