11 research outputs found
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Evaluation of coated QCM for the detection of atmospheric ozone
A coated acoustic wave sensor has been developed to selectively detect atmospheric ozone. The selective detection has been assessed using a variety of coatings: beeswax, gallic acid, indigo carmine, polybutadiene, potassium iodide and sodium nitrite. Polybutadiene was the most sensitive with a limit of detection of 55 ppb. The sensitivity was improved by operating at higher harmonics and was shown to increase linearly with harmonic up to the 11th harmonic. This novel work shows that ozone detection can be improved by operating at the crystals' harmonic frequencies and in conjunction with a suitable flow rate, a potentially highly sensitive and fast response sensor can be created based on acoustic wave technolog
Methane and carbon dioxide fluxes and their regional scalability for the European Arctic wetlands during the MAMM project in summer 2012
Airborne and ground-based measurements of methane (CH4), carbon dioxide (CO2) and boundary layer thermodynamics were recorded over the Fennoscandian landscape (67â69.5° N, 20â28° E) in July 2012 as part of the MAMM (Methane and other greenhouse gases in the Arctic: Measurements, process studies and Modelling) field campaign. Employing these airborne measurements and a simple boundary layer box model, net regional-scale (~ 100 km) fluxes were calculated to be 1.2 ± 0.5 mg CH4 hâ1 mâ2 and â350 ± 143 mg CO2 hâ1 mâ2. These airborne fluxes were found to be relatively consistent with seasonally averaged surface chamber (1.3 ± 1.0 mg CH4 hâ1 mâ2) and eddy covariance (1.3 ± 0.3 mg CH4 hâ1 mâ2 and â309 ± 306 mg CO2 hâ1 mâ2) flux measurements in the local area. The internal consistency of the aircraft-derived fluxes across a wide swath of Fennoscandia coupled with an excellent statistical comparison with local seasonally averaged ground-based measurements demonstrates the potential scalability of such localised measurements to regional-scale representativeness. Comparisons were also made to longer-term regional CH4 climatologies from the JULES (Joint UK Land Environment Simulator) and HYBRID8 land surface models within the area of the MAMM campaign. The average hourly emission flux output for the summer period (JulyâAugust) for the year 2012 was 0.084 mg CH4 hâ1 mâ2 (minimum 0.0 and maximum 0.21 mg CH4 hâ1 mâ2) for the JULES model and 0.088 mg CH4 hâ1 mâ2 (minimum 0.0008 and maximum 1.53 mg CH4 hâ1 mâ2) for HYBRID8. Based on these observations both models were found to significantly underestimate the CH4 emission flux in this region, which was linked to the under-prediction of the wetland extents generated by the models
UK Acid Water Monitoring Network: 15 Year Report. Analysis and interpretation of results: April 1988 - March 2003
This report summarises the findings of the UK Acid Waters Monitoring Network (AWMN) 15 year data interpretation exercise. The AWMN is funded by the UK Department for Environment Food and Rural Affairs. The report also incorporates an analysis of data collated by the UK Acid Deposition Network (ADN) run by NETCEN
The first UK measurements of nitryl chloride using a chemical ionization mass spectrometer in central London in the summer of 2012, and an investigation of the role of Cl atom oxidation
The first nitryl chloride (ClNO2) measurements in the UK were made during the summer 2012 ClearfLo campaign with a chemical ionization mass spectrometer, utilizing an Iâ ionization scheme. Concentrations of ClNO2 exceeded detectable limits (11âppt) every night with a maximum concentration of 724âppt. A diurnal profile of ClNO2 peaking between 4 and 5 A.M., decreasing directly after sunrise, was observed. Concentrations of ClNO2 above the detection limit are generally observed between 8 P.M. and 11 A.M. Different ratios of the production of ClNO2:N2O5 were observed throughout with both positive and negative correlations between the two species being reported. The photolysis of ClNO2 and a box model utilizing the Master Chemical Mechanism modified to include chlorine chemistry was used to calculate Cl atom concentrations. Simultaneous measurements of hydroxyl radicals (OH) using low pressure laserâinduced fluorescence and ozone enabled the relative importance of the oxidation of three groups of measured VOCs (alkanes, alkenes, and alkynes) by OH radicals, Cl atoms, and O3 to be compared. For the day with the maximum calculated Cl atom concentration, Cl atoms in the early morning were the dominant oxidant for alkanes and, over the entire day, contributed 15%, 3%, and 26% toward the oxidation of alkanes, alkenes, and alkynes, respectively