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Methane emissions from a constructed wetland treating wastewater: Seasonal and spatial distribution and dependence on edaphic factors
Department of Microbiology, Swedish Univ. of Agricultural Sci., Uppsala S-750 07, Sweden.
Linköping University, The Tema Institute, Department of Water and Environmental Studies. Linköping University, Faculty of Arts and Sciences.
Department of Forest Ecology, Swedish Univ. of Agricultural Sci., Umeå S-901 83, Sweden.
Linköping University, The Tema Institute, Department of Water and Environmental Studies. Linköping University, Faculty of Arts and Sciences.
2004 (English)In: Water Research, ISSN 0043-1354, E-ISSN 1879-2448, Vol. 38, no 18, 3960-3970 p.Article in journal (Refereed) Published
Abstract [en]

Constructed wetlands for wastewater treatment have many advantages. They can be used for several purposes, for example, to reduce levels of organic matter and nutrients, and to retain toxic metals. However, most wetlands are inherently net sources of gaseous compounds like methane and nitrous oxide, which are of environmental concern due to their rapid current accumulation in the atmosphere and their potent global warming capacity. In order to determine the flux of methane from a constructed wetland a study was conducted over two growth seasons on a pilot scale wetland constructed to reduce nutrient levels in secondary treated wastewater. The emissions for the spring to autumn period averaged 141 mg CH4 m-2 d-1 (S.D.=187), ranging from consumption of 375 mg CH4 m-2 d-1 to emissions of 1739 mg CH4 m-2 d-1. The spatial and temporal variations were large, but could be accounted for by measured environmental factors. Among these factors, sediment and water temperatures were significant in all cases and independent of the scale of analysis (r2 up to 0.88).

Place, publisher, year, edition, pages
2004. Vol. 38, no 18, 3960-3970 p.
Keyword [en]
CH4 fluxes, Greenhouse gas, Seasonal and spatial distribution, Wastewater
National Category
Social Sciences
URN: urn:nbn:se:liu:diva-45628DOI: 10.1016/j.watres.2004.07.008OAI: diva2:266524

The original title of this article was: Seasonal and Spatial Distribution of Methane Emissions in a Constructed Wetland Treating Wastewater : dependence on edaphic factors.

Available from: 2009-10-11 Created: 2009-10-11 Last updated: 2014-09-12Bibliographically approved
In thesis
1. Constructed Wetlands and Deconstructed Discourses: Greenhouse gas fluxes and discourses on purifying capacities
Open this publication in new window or tab >>Constructed Wetlands and Deconstructed Discourses: Greenhouse gas fluxes and discourses on purifying capacities
2002 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis is a study within the sciences ofconstructed wetlands. It has two sections. Section one is a natural scienrific study ofgas fluxes from construcred wetlands and section two is an analysis ofhow natural sciences describe constructed wetlands.

The aim of section one was to determine methane and nitrous oxide fluxes between the atmosphere and constructed wetlands. The result from these gas flux studies showed that methane fluxes ranged between -375 and 1739 mg m-2 day1, whereas the nitrous oxide fluxes ranged from consumption at -350 to emissions at 1791 Jlg m-2 h-1. The annual inregrated methane fluxes were 87 mg m-2 day1, whereas the inregrated nitrous oxide fluxes resulred in an overall average of 126 µg N2O m-2 h-1. There were large temporal and spatial variations in gas fluxes but no differences between night and day. The methane rates were lower than the average rate, 225 mg m-2 day1, found at a constructed pilot scale wetland treating dairy wastewater in New Zealand (Tanner, 1997), but the cited measuremenrs were only taken during one monrh in mid-summer. The average and range of methane flux values in my study also showed that the methane emission rates were of the same magnitude as those observed from natural wetlands with similar vegetational composition. The nitrous oxide emissions observed in the Nykvarn study were ca. three to ten times higher than in previous studies of constructed wetlands treating wastewater, whereas the nitrous oxide consumption rate was approximately 80 times higher. The nitrous oxide fluxes were 3 to 180 times higher compared to other wetland systems. Emission factors were calculated according to the methods presenred by the Inrergovernmenral Panel of Climate Change (IPCC). The calculated nitrous oxide emission factors from Nykvarn were always lower (0.02 to 0.27%) compared to the default factor provided by the IPCC (0.75%).

The aim of section two was to analyse descriptions on purifying capacities in constructed wetlands in selected scienrific articles. This was made with help of a discourse analysis, which can be explained as a study of communication. The results from this analysis showed that the wetlands were described in terms of self-purifying, biochemical cycles. The cycle concept is used in all three discourses (case I to 3) but it is comprehended differently. In case I the cycling processes are treated as inrrinsic and unproblematic in relation to purification. In case 2, the purifying cycles are treated as dynamic, complex and problematic, but humans could influence them and develop their inrrinsic ability. In case 3 th~ cycling processes became a tool, allowing us to grasp, handle, act upon and influence the wetlands. In the thesis these differences are discussed with respecr to scienrific ideals including language in general and metaphors and concepts in parricular as weil as to the ambiguous relationship between humans and wetlands. Finally, the thesis conrain a reflection on the studies discussed in section I and II. The reflection aims at developing new paths for of gas flux investigations (with biosemiotic perspectives) in research fields related to constructed wetlands.

Place, publisher, year, edition, pages
Linköping: Linköpings universitet, 2002. 106 p.
Linköping Studies in Arts and Science, ISSN 0282-9800 ; 253
växthuseffekter, vattenrening, miljöaspekter
National Category
Social Sciences Interdisciplinary
urn:nbn:se:liu:diva-29577 (URN)14953 (Local ID)91-7373-321-0 (ISBN)14953 (Archive number)14953 (OAI)
Public defence
2002-04-26, Elysion, Hus T, Campus VAlla, Linköpings universitet, Linköping, 10:15 (English)
Available from: 2009-10-09 Created: 2009-10-09 Last updated: 2014-08-29Bibliographically approved

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