Improving the reliability of closed chamber methodologies for methane emissions measurement in treatment wetlands
Non-homogeneous mixing of methane (NHM) within closed chambers was studied under laboratory conditions. The experimental set-up consisted of a PVC vented chamber of 5.3 litres of effective volume fitted with a power-adjustable 12 V fan. NHM within the chamber was studied according to fan position (t...
| Veröffentlicht in: | Water science and technology : a journal of the International Association on Water Pollution Research. - 1986. - 68(2013), 9 vom: 13., Seite 2097-102 |
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| Format: | Online-Aufsatz |
| Sprache: | English |
| Veröffentlicht: |
2013
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| Zugriff auf das übergeordnete Werk: | Water science and technology : a journal of the International Association on Water Pollution Research |
| Schlagworte: | Evaluation Study Journal Article Research Support, Non-U.S. Gov't Air Pollutants Gases Methane OP0UW79H66 |
| Zusammenfassung: | Non-homogeneous mixing of methane (NHM) within closed chambers was studied under laboratory conditions. The experimental set-up consisted of a PVC vented chamber of 5.3 litres of effective volume fitted with a power-adjustable 12 V fan. NHM within the chamber was studied according to fan position (top vs lateral), fan airflow strength (23 vs 80 cubic feet per minute) and the mixing time before sample withdrawal (5, 10, 15 and 20 minutes). The potential bias of methane flux densities caused by NHM was addressed by monitoring the difference between linearly expected and estimated flux densities of ca. 400, ca. 800 and ca. 1,600 mg CH(4).m(-2) d(-1). Methane within the chamber was under non-homogeneous conditions. Accordingly, methane concentrations at the bottom of the chamber were between 20 to 70% higher than those recorded at the middle or top sections of the chamber, regardless of fan position, fan air-flow strength or time before sample withdrawal. NHM led to notable biases on flux density estimation. Accordingly, flux density estimated from top and middle sampling sections were systematically lower (ca. 50%) than those expected. Flux densities estimated from bottom samples were between 10% higher and 25% lower than expected, regardless of the flux density considered |
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| Beschreibung: | Date Completed 06.02.2014 Date Revised 10.12.2019 published: Print Citation Status MEDLINE |
| ISSN: | 0273-1223 |
| DOI: | 10.2166/wst.2013.469 |