scholarly journals Dissolved gas measurements in oceanic waters made by membrane inlet mass spectrometry

2005 ◽  
Vol 3 (1) ◽  
pp. 24-37 ◽  
Author(s):  
Philippe D. Tortell
Keyword(s):  
Mass Spectrometry ◽  
Dissolved Gas ◽  
Membrane Inlet Mass Spectrometry ◽  
Gas Measurements

The effect of temperature on methane dynamics in soil and peat cores: Calculations from membrane inlet mass spectrometry

2007 ◽  
Vol 87 (1) ◽  
pp. 11-22 ◽  
Author(s):  
Samuel Keir Sheppard ◽  
Manfred Beckmann ◽  
David Lloyd
Keyword(s):  
Mass Spectrometry ◽  
Plant Cover ◽  
Bubble Formation ◽  
Soil Surface ◽  
Effect Of Temperature ◽  
Emission Rates ◽  
Dissolved Gas ◽  
Gas Emission ◽  
Membrane Inlet Mass Spectrometry ◽  
Aerobic Soil

Methanogenesis and methane oxidation, fundamental microbial processes in the global carbon cycle, are mediated by numerous factors in terrestrial soil and wetland ecosystems. Accurate quantification of CH4 and CO2 concentrations in soils and wetlands is now possible using membrane inlet mass spectrometry. Below-ground production and headspace exchange of O2, CO2 and CH4 were monitored in microcosms from an upland Soil (Scotland) and three different peat bog systems (Sweden, Iceland and Scotland) by membrane inlet mass spectrometry. A comparison of cores from the different locations revealed that temperature, soil structure, plant cover and water table level are associated with the regulation of the depth of oxygen available for methanotrophic processes in the oxic zone and therefore gas emission rates. In aerobic soil cores, all the methane produced in anaerobic sites is oxidised rather than being emitted from the soil surface. In peat cores, molar CH4:CO2-ratios of around 1:10 indicate the boundary between the oxic and the anoxic zones. Changes in dissolved gas concentrations with depth and especially the molar CH4 :CO2-ratios are discussed. We also demonstrate that inconsistencies in dissolved gas profiles, along with higher localized molar CH4:CO2-ratios, indicate bubble formation at depths greater than 10 cm; gas emission by ebullition was promoted at these sites. Increase in temperature had a particularly strong effect upon gas dynamics in soil and peat cores. Gas solubilities were reduced and elevated CO2 and CH4 emission rates were observed potentially due to increased microbial activity. Key words: Methane, CO2, membrane inlet mass spectrometry, soil

scholarly journals Simultaneous Measurement of Denitrification and Nitrogen Fixation Using Isotope Pairing with Membrane Inlet Mass Spectrometry Analysis

2001 ◽  
Vol 67 (3) ◽  
pp. 1171-1178 ◽  
Author(s):  
Soonmo An ◽  
Wayne S. Gardner ◽  
Todd Kana
Keyword(s):  
Nitrogen Fixation ◽  
Sediment Cores ◽  
Coastal Sediments ◽  
Mass Spectrometry Analysis ◽  
Dissolved Gas ◽  
Spectrometry Analysis ◽  
Membrane Inlet Mass Spectrometry ◽  
Gas Measurement ◽  
Isotope Pairing ◽  
Gas Measurements

ABSTRACT A method for estimating denitrification and nitrogen fixation simultaneously in coastal sediments was developed. An isotope-pairing technique was applied to dissolved gas measurements with a membrane inlet mass spectrometer (MIMS). The relative fluxes of three N2 gas species (28N2,29N2, and 30N2) were monitored during incubation experiments after the addition of15NO3 −. Formulas were developed to estimate the production (denitrification) and consumption (N2 fixation) of N2 gas from the fluxes of the different isotopic forms of N2. Proportions of the three isotopic forms produced from15NO3 − and14NO3 − agreed with expectations in a sediment slurry incubation experiment designed to optimize conditions for denitrification. Nitrogen fixation rates from an algal mat measured with intact sediment cores ranged from 32 to 390 μg-atoms of N m−2 h−1. They were enhanced by light and organic matter enrichment. In this environment of high nitrogen fixation, low N2 production rates due to denitrification could be separated from high N2 consumption rates due to nitrogen fixation. Denitrification and nitrogen fixation rates were estimated in April 2000 on sediments from a Texas sea grass bed (Laguna Madre). Denitrification rates (average, 20 μg-atoms of N m−2 h−1) were lower than nitrogen fixation rates (average, 60 μg-atoms of N m−2 h−1). The developed method benefits from simple and accurate dissolved-gas measurement by the MIMS system. By adding the N2 isotope capability, it was possible to do isotope-pairing experiments with the MIMS system.

In situ determination of porewater gases by underwater flow-through membrane inlet mass spectrometry

2012 ◽  
Vol 10 (3) ◽  
pp. 117-128 ◽  
Author(s):  
Ryan J. Bell ◽  
William B. Savidge ◽  
Strawn K. Toler ◽  
Robert H. Byrne ◽  
R. Timothy Short
Keyword(s):  
Mass Spectrometry ◽  
Membrane Inlet Mass Spectrometry ◽  
Flow Through

Analysis of Semivolatile Pharmaceuticals and Pollutants in Organic Micro Extracts Using Hot Cell Membrane Inlet Mass Spectrometry

2009 ◽  
Vol 81 (10) ◽  
pp. 4010-4014 ◽  
Author(s):  
Hua Chen ◽  
Zhining Xia ◽  
Stig Pedersen-Bjergaard ◽  
Bo Svensmark ◽  
Frants R. Lauritsen
Keyword(s):  
Mass Spectrometry ◽  
Cell Membrane ◽  
Membrane Inlet Mass Spectrometry
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