Acquisition of Intrinsic Ge Gamma Spectrometers

这笔赠款用于购置两台锗伽马射线闪烁仪，用于分析短寿命放射性同位素(例如，7Be T1/2=53d和210PbT1/2=22.3yr)。由于它们的半衰期很短，这些放射性核素是短期河床床沙停留时间的极佳示踪剂。7Be和210Pb都是反应性的，很容易被河流床沙中常见的细粒矿物(2毫米)吸附。考虑到它们的半衰期的不同，7Be/210Pb的活度比自最后一次暴露在大气中以来随着沉积物停留时间的增加而降低，在大气中获得了最初的尘埃活动。细颗粒泥沙(标称直径小于~2 mm)的输运控制着河流环境中污染物的隔离。此外，细粒泥沙往往是整个泥沙通量的重要组成部分，因此可以成为地貌变化的重要因素。建议的设备将立即用于由达特茅斯学院PIS资助的NSF研究，以研究混合负荷河流中细颗粒泥沙的床面停留时间，以了解大坝建设和拆除对泥沙动力学的影响，以及颗粒活性有害物质(如痕量金属、碳氢化合物)的迁移和去向。拟议中的设备将影响达特茅斯学院地球科学、地理学和环境研究系的研究和教学。该设备将支持本科生和研究生在河流沉积物动力学方面的研究。PIS计划让本科生女性参加达特茅斯的女性科学项目-该项目旨在通过指导和早期实践研究经验，鼓励女性进入并继续从事科学、数学和工程领域的工作。

This grant provides support for the acquisition of two Germanium gamma ray scintillometers for the analysis of short lived radioisotopes (e.g., 7Be T1/2 = 53 d and 210Pb T1/2 = 22.3 yr). As a result of their short half lives, these fallout radionuclides make excellent tracers of short term riverine bed load residence times. Both 7Be and 210Pb are reactive and readily adsorb to fine grained minerals ( 2 mm) common in fluvial bed loads. Given the differences in their half lives, the activity ratio 7Be/210Pb decreases with increased residence time of the sediments since last exposure to the atmosphere where it acquired its initial fallout activity. The transport of fine sediment (nominal diameter of less than ~2 mm) controls the sequestration of contaminants in fluvial environments. In addition, fine sediment is often a significant component of overall sediment flux, and thus can be an important agent of geomorphic change. The proposed equipment will be immediately employed in NSF-funded research by PIs at Dartmouth College to study the bed residence time of fine sediment in mixed-load rivers with relevance to understanding the effects of dam construction and removal on sediment dynamics and the transport and fate of particle reactive deleterious substances (e.g., trace metals, hydrocarbons). The proposed equipment would impact research and teaching in the Departments of Earth Sciences, Geography, and Environmental Studies at Dartmouth College. The equipment will support undergraduate and graduate student research in riverine sediment dynamics. The PIs plan to involve undergraduate women participating in Dartmouth's Women In Science Program - a program designed to encourage women to enter and continue in science, math, and engineering through mentoring and early hands-on research experience.