title: A portable membrane contactor sampler for analysis of noble gases in groundwater.
abstract: To enable a wider use of dissolved noble gas concentrations and isotope ratios in groundwater studies, we have developed an efficient and portable sampling device using a commercially available membrane contactor. The device separates dissolved gases from a stream of water and collects them in a small copper tube (6 mm in diameter and 100 mm in length with two pinch-off clamps) for noble gas analysis by mass spectrometry. We have examined the performance of the sampler using a tank of homogeneous water prepared in the laboratory and by field testing. We find that our sampling device can extract heavier noble gases (Ar, Kr, and Xe) more efficiently than the lighter ones (He and Ne). An extraction time of about 60 min at a flow rate of 3 L/min is sufficient for all noble gases extracted in the sampler to attain equilibrium with the dissolved phase. The extracted gas sample did not indicate fractionation of helium ((3) He/(4) He) isotopes or other noble gas isotopes. Field performance of the sampling device was tested using a groundwater well in Vienna and results were in excellent agreement with those obtained from the conventional copper tube sampling method.
authors.affiliation: Isotope Hydrology Section, Division of Physical and Chemical Sciences, Department of Nuclear Sciences and Applications, International Atomic Energy Agency, Vienna, Austria. t.matsumoto@iaea.org
authors.forename: Takuya
authors.initials: T
authors.lastname: Matsumoto
authors.forename: Liang-Feng
authors.initials: LF
authors.lastname: Han
authors.forename: Manfred
authors.initials: M
authors.lastname: Jaklitsch
authors.forename: Pradeep K
authors.initials: PK
authors.lastname: Aggarwal
mesh_terms: D001317:Austria; D004784:Environmental Monitoring / Q000295:instrumentation* / Q000379:methods*; D004867:Equipment Design; D060587:Groundwater / Q000032:analysis* / Q000737:chemistry; D006371:Helium / Q000032:analysis; D007554:Isotopes / Q000032:analysis; D013058:Mass Spectrometry / Q000379:methods; D005741:Noble Gases / Q000032:analysis*
chemical_list: D007554:Isotopes; D005741:Noble Gases; D006371:Helium