earth science

Glen Snyder

Research Scientist

Ph.D (2001) University of Rochester

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Publication list (pdf).

Curriculum vitae (pdf)


Phone: (713)348-4054

Office: Keith Weiss Earth Science 330B

Rice Earth Science
Dispersal of anthropogenic isotopes:

Nuclear reprocessing of spent fuel rods, coupled with nuclear bomb tests of the 1960's, has greatly increased global concentrations of several man-made isotopes. The release of these isotopes into the environment allows us to determine the extent to which modern waters have migrated into aquifers, and they also provide an indicator of how different elements migrate through ecosystems. Several of these isotopes, such as 131I or 3H, have short half-lives and generally return to pre-anthropogenic levels after months or several decades. In the case of long-lived 36Cl, dilution from "dead" chloride in seawater, has also caused 36Cl/Cl ratios to return to near-preanthropogenic values. My research has focused on global variations in 129I in rivers and lakes, and the effect of different climate-related factors on iodine mobilization. These factors are important to human health, given that inhabitants of certain regions are more prone to iodine deficiency syndrome. In the case of nuclear accidents, the mobility of iodine through the food chain is also important, since the dispersal of short-lived iodine isotopes from fission products is a contributing factor to thyroid cancer. Prior to human nuclear activities, the total pre-anthropogenic reservoir of 129iodine in the oceans was only 90 kg. Today, major point-source releases of 129I into the oceans come from two major reprocessing plants in Europe, Sellafield and La Hague.

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Point sources of 129iodine into the environment (in kilograms). Major contributors over the past few decades have been Sellafied (800 kg) and La Hague (1300 kg). Releases from the Chernobyl accident (red) were relatively small when compared with the reprocessing plants.
Revolatilization of 129iodine in shallow ocean waters and soils has resulted in its migration from the Northern to the Southern hemisphere. Elevated concentrations are even present in Antarctica.
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Global distribution of 129iodine. Land releases from nuclear processing in Russia have led to elevated ratios along the Ob River.