CH4 continuous measurements in the upper Spanish plateau
M Luisa Sánchez1, M Ángeles García, Isidro A Pérez
1Department of Applied Physics, Faculty of Sciences, University of Valladolid, Paseo Belén 7, 47011, Valladolid, Spain, marisa@fa1.uva.es.
Environmental Monitoring and Assessment
|December 25, 2013
Summary
Local pollution significantly impacts methane (CH4) levels in Spain, altering daily and seasonal patterns. Even with infrequent southeast winds, urban plumes and landfills demonstrably increase CH4 concentrations.
Area of Science:
- Atmospheric Chemistry
- Environmental Science
- Air Quality Monitoring
Background:
- Methane (CH4) is a potent greenhouse gas with significant anthropogenic sources.
- Understanding local emission impacts is crucial for accurate atmospheric modeling.
- Rural atmospheric measurements provide baseline data, but local influences can complicate interpretation.
Purpose of the Study:
- To quantify the impact of local anthropogenic sources on continuous methane concentrations.
- To differentiate between background CH4 levels and those influenced by nearby pollution.
- To analyze diurnal and seasonal patterns of CH4 in response to local emissions.
Main Methods:
- Continuous methane (CH4) concentration measurements using cavity ring-down spectroscopy.
- Data analysis differentiating between wind sectors to identify local source contributions.
- Statistical analysis to determine significance of observed CH4 anomalies.
Main Results:
- Local anthropogenic sources, including urban plumes and landfills, significantly elevated CH4 concentrations, particularly from the southeast sector.
- CH4 background levels were established from undisturbed sectors, averaging 1,887.1 ppb.
- Diurnal and seasonal CH4 patterns were primarily driven by OH radical reactions, with higher concentrations at night/early morning and in winter.
Conclusions:
- Local pollution sources exert a substantial influence on measured CH4 concentrations, masking true background levels.
- Despite low frequency of relevant winds, urban and landfill emissions demonstrably impacted CH4 levels.
- Accurate assessment of CH4 requires accounting for local emission impacts, even in areas presumed to be rural.
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