Ocean ventilation is the integrated effect of various processes that exchange surface properties with the ocean interior and is essential for oxygen supply, storage of anthropogenic carbon and the heat budget of the ocean, for instance. Current observational methods utilise transient tracers, e. However, their dating ranges are not ideal to resolve the centennial-dynamics of the deep ocean, a gap filled by the noble gas isotope 39 Ar with a half-life of years. Our data reveal previously not quantifiable ventilation patterns in the Tropical Atlantic, where we find that advection is more important for the ventilation of the intermediate depth range than previously assumed. Now, the demonstrated analytical capabilities allow for a global collection of 39 Ar data, which will have significant impact on our ability to quantify ocean ventilation. The well-mixed surface layer of the ocean exchanges properties with the atmosphere through air—sea gas exchange. Various processes such as advection and eddy diffusion are responsible for transporting surface waters with their corresponding properties to the ocean interior.
Groundwater dating with Atom Trap Trace Analysis of 39Ar
In the earth and environmental sciences, radioactive isotopes, atom variants that decay over time, play a major role in age determination. A radioactive isotope of the inert gas argon 39 Ar , for example, is used to determine the age of water or ice. Such isotopes are extremely rare, however — only a single 39 Ar isotope occurs in a thousand trillion argon atoms. Hence researchers’ attempts to isolate and detect such atoms remain the proverbial search for the needle in a haystack.
Towards the realization of atom trap trace · analysis for 39Ar. J Welte, F Ritterbusch, itoring , groundwater dating [2,3], and discovery of plu-.
Lu, P. Schlosser , W. Smethie, N. Sturchio, T. Fischer, B. Kennedy, R.
Groundwater dating with Atom Trap Trace Analysis of39Ar
We use advanced technologies to measure and trace the histories of water systems. We partner across scientific disciplines and institutions. Characterising groundwater flow on time scales that date back a million years requires new technology for detecting noble gas isotopes. The complexity of natural groundwater systems and the limitations of many traditional environmental tracers calls for the use of a new suite of ‘ideal’ tracers: the noble gases.
Atom Trap Trace Analysis (ATTA) with Krypton Dating old groundwater to study the source, sink, and flow pattern of aquifers. Applicable abundance of 39Ar).
With a half-life of years, carbon- 14 is well suited for radioisotope dating of fossils and other archeological finds. On the other end of the time spectrum, tritium half-life of There are, however, many geological changes that occur on a timescale of 10 — years. Argon- 39 , which is produced in the atmosphere by cosmic rays and has a half-life of years, would seem an ideal isotope to fill this niche. Writing in Physical Review Letters , a team of scientists working at Argonne National Laboratory, US, reports they have reached an isotopic sensitivity of 10 – 16 for argon- 39 using a specialized magneto-optical atom trap that allows them to detect single atoms.
In their setup, the team laser-cools and traps argon atoms with a laser tuned to the vicinity of an argon- 39 atomic resonance. Since it takes many cycles of absorption to trap the atoms, there is a nearly complete rejection of the other isotopes from the trap and only the remaining argon- 39 atoms are detected. Alternative methods to analyze the abundance of argon- 39 exist, such as accelerator mass spectrometry. Jiang, W. Williams, K.
Atom trap trace analysis of krypton in xenon for the XENON Dark Matter Project
The first sample for Argon measurements using the new ATTA method, collected at a depth of 4, metres. The sample was obtained during a pilot study in the tropical North Atlantic off the Cape Verde Islands. The age of the water in the world’s oceans is critical for understanding ocean circulation, especially for the transport of gases from the atmosphere into the deep ocean.
Researchers from Heidelberg University recently used an atomic physics technique they developed to determine the age of deep ocean water ranging from 50 to 1, years.
A radioactive isotope of the inert gas argon (39Ar), for example, is used to Groundwater dating with Atom Trap Trace Analysis of39Ar.
The United States government has rights in the invention described herein pursuant to Contract No. The invention relates to methods and systems for detecting selected isotopes of all noble gases. Krypton permeates through the atmosphere at a concentration of about one part per million. Upon the discovery of 81 Kr in the atmosphere, it has been proposed that 81 Kr is an ideal tracer isotope for dating water and ice in the age range of 10 5 6 years, a range beyond the reach of 14 C-dating.
Due to its long residence time, 81 Kr is expected to be distributed uniformly throughout the atmosphere. Subsurface sources and sinks for 81 Kr other than radioactive decay are most likely negligible. Human activities involving nuclear fission have a negligible effect on the 81 Kr concentration because the stable 81 Br shields 81 Kr from the decay of the neutron-rich fission products. All of these favorable conditions combine to support the case for 81 Kr-dating. The other long-lived krypton isotope, 85 Kr, has a completely different production source.
It is a fission product of U and Pu, and is released into the atmosphere primarily by nuclear fuel reprocessing activities. For 85 Kr analysis, low level decay counting LLC is performed routinely in a few specialized laboratories around the world. In general, counting atoms is preferable to counting decays for analyses of long-lived isotopes because of the enhanced efficiency, and because of the immunity to other decay backgrounds from both the sample and the surroundings.
An accelerator mass spectrometry AMS method for counting 81 Kr ions has been developed, and has been used to perform 81 Kr-dating of four groundwater samples from the Great Artesian Basin of Australia. However, due to the complexity of this technique, which required the use of a high energy 4 GeV cyclotron to produce fully stripped 81 Kr ions, and the large sample size required 16 tons of water , the AMS effort on 81 Kr-dating was halted following these proof-of-principle measurements.
Recent advances in Atom Trap Trace Analysis ATTA , a laser-based atom counting method, have enabled routine measurements of the radiokrypton isotopes, as well as the demonstration of the ability to measure 39Ar in environmental samples. Here we provide an overview of the ATTA technique, and a survey of recent progress made in several laboratories worldwide. We review the application of noble gas radionuclides in the geosciences and discuss how ATTA can help advance these fields, specifically: determination of groundwater residence times using 81Kr, 85Kr, and 39Ar; dating old glacial ice using 81Kr; and an 39Ar survey of the main water masses of the oceans, to study circulation pathways and estimate mean residence times.
ATTA for 39Ar Analysis If a fold improvement in counting rate and of the atomic structure between argon and krypton, we expect the overall trapping Dating Groundwater Of fundamental importance in hydrological sciences is the ability to 0 Atom Trap Trace Analysis of Rare Noble Gas Isotopes 5.
Methods for using argon to age-date groundwater using ultra-low-background proportional counting. Argon can be used as a tracer for age-dating glaciers, oceans, and more recently, groundwater. With a half-life of years, 39Ar fills an intermediate age range gap , years not currently covered by other common groundwater tracers.
Therefore, adding this tracer to the data suite for groundwater studies provides an important tool for improving our understanding of groundwater systems. We present the methods employed for arriving at an age-date for a given sample of argon degassed from groundwater. Degradation of sucralose in groundwater and implications for age dating contaminated groundwater.
The artificial sweetener sucralose has been in use in Canada and the US since about and in the EU since , and is now ubiquitous in sanitary wastewater in many parts of the world. It persists during sewage treatment and in surface water environments and as such, has been suggested as a powerful tracer of wastewater. In this study, longer-term persistence of sucralose was examined in groundwater by undertaking a series of three sampling snapshots of a well constrained wastewater plume in Canada Long Point septic system over a 6-year period from to A shrinking sucralose plume in , compared to earlier sampling, during this period when sucralose use was likely increasing, provides clear evidence of degradation.
Even though sucralose degradation is noted in the Long Point plume, its ubiquitous presence in the groundwater plumes at all seven sites implies a relatively slow rate of decay in many groundwater septic plume environments. Thus, sucralose has the potential to be used as an indicator of ‘recent’ wastewater contamination.
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the laser-cooling technique “Atom Trap Trace Analysis” (). With this approach and specific focus is put on dating of groundwater with 39Ar. Basic information.
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