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A Rare Isotope Helps Track an Ancient Water Source
Krypton is the product of atmospheric reactions with the other naturally occurring isotopes of krypton [ 78 Kr 0. It is radioactive with a half-life of , years. Little use of this isotope has been made due to interference from 85 Kr; however, it has been used for age determination in old 50,, year groundwater Oeschger, ; Lehman et al. Sources have included nuclear-bomb testing, nuclear reactors, and the release of 85 Kr during the reprocessing of fuel rods from nuclear reactors Sittkus and Stockburger,
Skip to search form Skip to main content You are currently offline. Some features of the site may not work correctly. Save to Library. Create Alert. Launch Research Feed. Share This Paper. Top 3 of 19 Citations View All Reconciling contradictory environmental tracer ages in multi-tracer studies to characterize the aquifer and quantify deep groundwater flow: an example from the Hutton Sandstone, Great Artesian Basin, Australia.
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The Nubian Aquifer, the font of fabled oases in Egypt and Libya, stretches languidly across , square miles of northern Africa, a pointillist collection of underground pools of water migrating, ever so slowly, through rock and sand toward the Mediterranean Sea. But its workings — how it flows and how quickly surface water replenishes it — have been hard to understand, in part because the tools available to study it have provided, at best, a blurry image.
Their first success was in distilling these elusive isotopes, krypton 81, from the water in the huge Nubian Aquifer , part of which lies two miles below the oases of western Egypt where temples honor Alexander the Great. Their second was in holding these isotopes still and measuring how much they had decayed since they last saw sunlight.
By combining Argonne’s pioneering radiokrypton dating technique with isotope krypton, which can date water up to million years old.
Getting reliable precipitation data from the past has proven difficult, as is predicting regional changes for climate models in the present. A combination of isotope techniques developed by researchers at Argonne and UChicago may help resolve both. The Negev desert, which covers half of Israel’s land mass, is so dry that parts of it get less than three inches of water a year.
So dry, its climatological term is “hyperarid. Today, despite its parched exterior, there is still water under the Negev. Understanding where it came from, how much is there, and what’s happening to it is critical to the security and allocation of that crucial resource. Department of Energy’s Argonne National Laboratory and the University of Chicago to better understand the Nubian Sandstone Aquifer system, which lies beneath a large portion of the Negev and other parts of Israel.
By combining Argonne’s pioneering radiokrypton dating technique with other isotopic fingerprints of the water’s composition, the researchers are not only able to tell when that water was deposited, but where it came from and the climate conditions that produced it nearly , years ago. The result marks the first time that scientists have been able to use groundwater to build a picture of ancient hydro-climates dating back that far.
ATTA measures water for traces of the rare krypton Kr isotope 81 Kr, which can date water within a range of approximately 40, to 1. This boosts it well beyond the range of radiocarbon dating, which cannot reach accurately beyond about 40, years.
Radiokrypton dating plumbs mysteries of water aquifers
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81Kr is cosmogenic and can be used for dating groundwater beyond the 14C age. 85Kr is a fission product and can be applied in atmospheric.
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Radiokrypton dating finally takes off
Top: satellite imagery of Taylor Glacier. Kr sampling locations are indicated as blue dots. Bottom: location of Taylor Glacier on map of Antarctica.
Krdating, a concept pursued in the past four decades by numerous laboratories employing a variety of techniques, is now available for the first time to the.
NSF-funded technique may eventually allow scientists to better understand cycles of ice ages. This material is available primarily for archival purposes. Telephone numbers or other contact information may be out of date; please see current contact information at media contacts. A team of scientists, funded by the National Science Foundation NSF , has successfully used a new technique to confirm the age of a ,year-old sample of Antarctic ice.
The new dating system is expected to allow scientists to identify ice that is much older, thereby reconstructing climate much farther back into Earth’s history and potentially leading to an understanding of the mechanisms that cause the planet to shift into and out of ice ages. The new technique provides an accurate means of confirming the age of ice samples, and researchers note it is now the most precise dating tool for ancient ice.
Department of Energy. Buizert, whose work also was supported in part by the National Oceanic and Atmospheric Administration, said reconstructing the Earth’s climate back to 1.
Isotopes of krypton
Krypton is a noble gas with eight isotopes, 6 stable and 2 radioactive. The stable isotopes are considered separately with the noble gases. Natural variation in the abundance of these isotopes can be useful in determining paleo recharge temperatures of groundwater.
Due to the large required sample size (5–10 μL STP of krypton), so far 81Kr has been used mainly for dating groundwater, while for glacier ice.
Ok, so I took some license with the title. In fact, Krypton 81Kr is a radioisotope of the noble gas krypton and ATTA, which stands for atom trap trace analysis, is the revolutionary technique that has made its analysis possible. Figure 1. Used with permission. This 81Kr then settles to the earth surface and is incorporated into groundwater recharge and can then used to date groundwater from thousand to 1.
In order to use this method we assume that the initial concentration in the recharge is in equilibrium with the concentration of 81Kr in the atmosphere, which is well mixed. ATTA then measures the amount of 81Kr that is left in the water sample compared to the other Kr isotopes and an age can be calculated from the difference between this ratio and the intial ratio.
Facts About Krypton
Ventilation studies of the lung with krypton – 81 m. During a 2-year study period it was found that krypton – 81 m was useful in clinical practice. During this period technetiumm perfusion studies and krypton – 81 m ventilation studies were performed. A distinct advantage of krypton – 81 m was the ease with which multiple views could be obtained. These views could be directly compared with those of preceding perfusion studies.
Recently, because of 81 Kr’s advantages of steady chemical property, long half-life and no extra source in the movement of groundwater, it is.
Springer Professional. Back to the search result list. Table of Contents. Hint Swipe to navigate through the chapters of this book Close hint. Abstract In a semi-arid to arid climate region, socio-economic development is mainly dependent on deep groundwater resources. This aquifer system, extending over more than a million of km 2 , is mainly confined, poorly recharged but intensely abstracted in Southern Tunisia.