Recent developments on field gas extraction and sample preparation methods for radiokrypton dating of groundwater

Yokochi, Reika

doi:10.1016/j.jhydrol.2016.06.020

Cited by 24 publications

(20 citation statements)

References 43 publications

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“…Groundwater samples were collected from 22 production wells in the eastern Negev Desert using a field gas-extraction device (19). The studied wells had perforated screens installed against water-bearing formations at various depths within the Nubian Sandstone Aquifer, as detailed in SI Appendix, Table S1.…”

Section: Resultsmentioning

confidence: 99%

“…Following Kr purification (14, 19), samples were analyzed using the ATTA instrument to determine the isotopic abundances of both 85 Kr (t 1/2 = 10.76 y) and 81 Kr (17). The 14 C activities of CO2 in 9 of the bulk gas samples were measured (19) using accelerator mass spectrometry.…”

Section: Resultsmentioning

confidence: 99%

“…Krypton and CO 2 were collected together with other bulk gases (about 10 L standard temperature and pressure [STP]) from groundwater using the field gas extraction device (for details see ref. 19), equipped with a commercial membrane contactor, Liqui-Cel Extra-Flow. As filtered water flows through the shell side of the contactor, dissolved gas is pumped out from the lumen side and compressed into a gas cylinder.…”

Section: Methodsmentioning

confidence: 99%

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Radiokrypton unveils dual moisture sources of a deep desert aquifer

Yokochi

Ram

Zappala

et al. 2019

Proc. Natl. Acad. Sci. U.S.A.

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In arid regions, groundwater is a vital resource that can also provide a long-term record of the regional water cycle. However, the use of groundwater as a paleoclimate proxy has been limited by the complex hydrology and the lack of appropriate chronometers to determine the recharge time without complication. Applying 81Kr, a long-lived radioisotope tracer, we investigate the paleohydroclimate and subsurface water storage properties of the Nubian Sandstone Aquifer in the Negev Desert, Israel. Based on the spatial distributions of stable isotopes and the abundance of 81Kr, we resolve subsurface mixing and identify two distinct moisture sources of the recharge: one recent (<38 ky ago) from the Mediterranean and the other 361 ± 30 ky ago from the tropical Atlantic, both of which occurred under conditions of low orbital eccentricity comparable to that of the present. The recent recharge provided by the moisture from Mediterranean cyclones can be attributed to the southward shift of the storm track during the Last Glacial Maximum, and the earlier recharge can be attributed to moisture from the Atlantic delivered as tropical plumes under a climate colder than the present. Furthermore, the residence time of the latter reveals that tectonically active terrain can store groundwater for an unexpectedly long period, likely due to strongly attenuated groundwater flow across the fault zones. With this tracer, groundwater can now serve as a direct record of paleoprecipitation over land and of subsurface water storage from the mid-Pleistocene and onward.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Radiokrypton unveils dual moisture sources of a deep desert aquifer

Yokochi

Ram

Zappala

et al. 2019

Proc. Natl. Acad. Sci. U.S.A.

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“…Arrows show water and gas flow directions. For portability, a 12 VDC battery-operated vacuum pump may be implemented as Device A in Yokochi (2016). 14 C analyses in water.…”

Section: Dic Speciation Dissolved Gas Chemistry and Atmospheric Conmentioning

confidence: 99%

Field Degassing as a New Sampling Method for¹⁴C Analyses in Old Groundwater

et al. 2017

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ABSTRACT. Radiocarbon ( 14 C) activity in groundwater can be used to determine subsurface residence time up to ∼40 kyr, providing crucial information on dynamic properties of groundwater and on paleoclimate. However, commonly applied sampling methods for dissolved inorganic carbon (DIC-14 C) are prone to low level of modern atmospheric contamination, resulting in underestimation of groundwater ages that cluster around 30-40 kyr. We extract CO 2 gas from groundwater using a device originally developed for studies of noble gas radionuclides. Carbon is collected in the gas phase, eliminating the possibility of fostering microbial activities and aqueous chemical reactions during sample storage. This method collects C except where mixing sources of young groundwater is suspected. These field data serve as confirmations for the reliability of the newly presented sample collection and CO 2 -14 C method, and for the outstanding roles of radiokrypton isotopes in characterizing old groundwater.

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“…Ten microliters of krypton gas (STP) can be purified in the laboratory from 10 L of air in approximately 75 min. In the field, this amount of air can typically be degassed from 100 L of groundwater in 30–60 min [ Yokochi , ].…”

Section: Introductionmentioning

confidence: 99%

Rapid processing of ⁸⁵Kr/Kr ratios using Atom Trap Trace Analysis

Zappala

Bailey

Müller

et al. 2017

Water Resources Research

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We report a methodology for measuring 85Kr/Kr isotopic abundances using Atom Trap Trace Analysis (ATTA) that increases sample measurement throughput by over an order of magnitude to six samples per 24 h. The noble gas isotope 85Kr (half‐life = 10.7 years) is a useful tracer for young groundwater in the age range of 5–50 years. ATTA, an efficient and selective laser‐based atom counting method, has recently been applied to 85Kr/Kr isotopic abundance measurements, requiring 5–10 μL of krypton gas at STP extracted from 50 to 100 L of water. Previously, a single such measurement required 48 h. Our new method demonstrates that we can measure 85Kr/Kr ratios with 3–5% relative uncertainty every 4 h, on average, with the same sample requirements.

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Recent developments on field gas extraction and sample preparation methods for radiokrypton dating of groundwater

Cited by 24 publications

References 43 publications

Radiokrypton unveils dual moisture sources of a deep desert aquifer

Radiokrypton unveils dual moisture sources of a deep desert aquifer

Field Degassing as a New Sampling Method for¹⁴C Analyses in Old Groundwater

Rapid processing of ⁸⁵Kr/Kr ratios using Atom Trap Trace Analysis

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Recent developments on field gas extraction and sample preparation methods for radiokrypton dating of groundwater

Cited by 24 publications

References 43 publications

Radiokrypton unveils dual moisture sources of a deep desert aquifer

Radiokrypton unveils dual moisture sources of a deep desert aquifer

Field Degassing as a New Sampling Method for14C Analyses in Old Groundwater

Rapid processing of 85Kr/Kr ratios using Atom Trap Trace Analysis

Contact Info

Product

Resources

About

Field Degassing as a New Sampling Method for¹⁴C Analyses in Old Groundwater

Rapid processing of ⁸⁵Kr/Kr ratios using Atom Trap Trace Analysis