title: Development of a trace gas stable isotope capture system in a mobile laboratory for temporal and spatial sampling of field and laboratory experiments.
abstract: We describe the development of a novel mobile field laboratory, purposely designed for the automated capture and subsequent stable isotopic analyses of multiple gas samples. The multiple capture system is integrated into a mobile laboratory that is fully capable of measuring the concentration of carbon dioxide, methane and nitrous oxide trace gases in a flow-through system connected to a gas chromatograph fitted with both electron capture and flame ionisation detectors. The capture of gases is achieved by routing samples through a series of 135 mL gas flasks that are sealed by micro-solenoid valves triggered by a timing system. Trace gas light stable isotope ratio mass spectrometry can then be carried out on gas samples collected by the system (NERC (15)N Stable Isotope Facility). The excitingly unique potential of the system to the ecological research field is that it will allow the collection of cyclical data for three different trace gases both in real-time and in situ. We present data arising from the validation of this mobile system as well as a preliminary experimental assessment of this technique. This technique was used to measure delta(13)C in CO(2) and CH(4) in soil gases released from waterlogged cores and delta(13)C-CH(4) values were significantly depleted in wet cores compared with dry ones (p < 0.001).
authors.affiliation: Centre for Ecology and Hydrology, Merlewood Research Station, Grange-over-Sands, Cumbria LA11 6JU, UK. nmcn@ceh.ac.uk
authors.forename: Niall
authors.initials: N
authors.lastname: McNamara
authors.forename: David
authors.initials: D
authors.lastname: Benham
authors.forename: Darren
authors.initials: D
authors.lastname: Sleep
authors.forename: Helen
authors.initials: H
authors.lastname: Grant
authors.forename: Andrew
authors.initials: A
authors.lastname: Stott
mesh_terms: D002245:Carbon Dioxide / Q000032:analysis; D002247:Carbon Isotopes / Q000032:analysis; D005740:Gases / Q000737:chemistry*; D007753:Laboratories; D008697:Methane / Q000032:analysis; D008952:Mobile Health Units; D009609:Nitrous Oxide / Q000032:analysis; D012987:Soil / Q000032:analysis; D014131:Trace Elements / Q000032:analysis
chemical_list: D002247:Carbon Isotopes; D005740:Gases; D012987:Soil; D014131:Trace Elements; D002245:Carbon Dioxide; D009609:Nitrous Oxide; D008697:Methane