Radioanalytical techniques for quaternary dating

这项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来测定第四纪环境样品的年龄。当事件比有记录的历史更古老时，确定环境样品的年龄并不简单；但这对环境科学的许多方面都是基本的。许多环境过程的历史年表可以通过老化样本得到。例如，使用地球化学理论解释的大气和地下水运移以及岩石和沉积物年龄可以用来重建时间趋势，确定环境变化速度，并测试环境过程的模型。 可以使用原子核的放射性衰变或以恒定和已知的速率发生的核反应产生特定同位素的速率来获得辐射测量数据。许多年轻的第四纪样品的测年被证明是困难的，因为在封闭系统上进行高精度测量是不可能的。在较老的系统中，准确的日期往往被证明是困难的，因为大多数14C已经衰变或初始活动不确定，而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，并为覆盖广泛年龄范围的第四纪材料提供更可靠的测年技术。 这些技术将被用于环境评估、气候变化研究、生态影响陈述和其他应用，在这些应用中，考察系统的长期行为以及人类和自然事件对该系统的影响非常重要。

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.