The Short-lived isotope laboratory in the Department of Earth Sciences at Dartmouth College is equipped to measure the abundance of a variety of short-lived isotopes. We specialize in the development of methods for, and application of, techniques for the measurement of very low-levels of natural and anthropogenic fallout radionuclides in environmental samples such as soil, sediment, and snow and ice packs. Most commonly we analyze for 210lead (half-life = 22.3 years), 7beryllium (half-life = 53 days), and 137cesium (half-life = 32.1 years).  For several weeks after the March 2011 failure of the Fukushima Daiichi nuclear complex we were able to measure fallout 13Iiodine (half-life = 8 days) in New England rainfall, soil, and sediment, allowing us to investigate  problems such as particle/contaminant transport in a natural landscape and atmospheric transport of contaminants in high-latitude environs.  Less common fallout radionuclides we area also capable of measuring include 241Am (half-life = 432 years), a daughter of  241Pu (half-life =14.4 years).

Fallout radionuclides are useful for tracing atmospheric and fluvial transport and the physical processes (soil mixing, erosion, sedimentation) and geochemical processes occurring at the earth's surface on timescales of years to decades. 210lead is also useful as a chronometer for dating of both lake and fluvial sediments.  

We are also capable of analyzing for “geogenic” radionuclides such as 238uranium (via 234Th), 226radium,  and 222radon (via 214Pb, 214Bi). Geogenic radionuclides can be used alone or in conjunction with fallout radionuclides to source sediment, quantify sedimentation processes, and investigate particulate dynamics in lakes, rivers, estuaries, and in the ocean. 

We have seven Canberra high-resolution, low background gamma spectroscopy systems (“Broad Energy” Intrinsic Ge Detectors), each equipped with a low-background lead shield for the determination of natural and anthropogenic radionuclides in soils and sediment. 

© Dartmouth College 2012