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Nitrogen retention versus methane emission: Environmental benefits and risks of large-scale wetland creation

Thiere, Geraldine LU ; Stadmark, Johanna LU and Weisner, Stefan E.B. (2011) In Ecological Engineering: the Journal of Ecotechnology 37(1). p.6-15
Abstract
Coastal eutrophication by nutrient fluxes from agricultural land to marine recipients is presently com- bated by measures such as the implementation of watershed-scale wetland creation programs aimed at nitrogen removal. Such created agricultural wetlands – termed ‘nitrogen farming wetlands’ (NFWs) – receive nitrogen (N) loads predominantly as nitrate, facilitating N removal by denitrification. However, the conversion of agricultural soils into waterlogged wetland area is likely to increase climate gas emissions, particularly methane (CH4). There is thus a need to evaluate the benefits and risks of wetland creation at a large, watershed-scale.

Here we investigate N retention and CH4 emission originating from watershed-scale... (More)
Coastal eutrophication by nutrient fluxes from agricultural land to marine recipients is presently com- bated by measures such as the implementation of watershed-scale wetland creation programs aimed at nitrogen removal. Such created agricultural wetlands – termed ‘nitrogen farming wetlands’ (NFWs) – receive nitrogen (N) loads predominantly as nitrate, facilitating N removal by denitrification. However, the conversion of agricultural soils into waterlogged wetland area is likely to increase climate gas emissions, particularly methane (CH4). There is thus a need to evaluate the benefits and risks of wetland creation at a large, watershed-scale.

Here we investigate N retention and CH4 emission originating from watershed-scale wetland creation in South Sweden, the relation between both processes, and how CH4 emission depends on individual wetland parameters. We combine data from intensively studied reference wetlands with an extensive wetland survey to predict N retention and CH4 emission with simple models, to estimate the overall process rates (large-scale effects) as well as spatial variation among individual NFWs.

We show that watershed-scale wetland creation serves targeted environmental objectives (N reten- tion), and that CH4 emission is comparably low. Environmental benefit and risk of individual wetlands were not correlated, and may thus be managed independently. High cover of aquatic plants was the most important wetland property that suppressed CH4 net production, potentially facilitating N retention simultaneously. Further, differences between wetlands in water temperature and wetland age seemed to contribute to differences in CH4 net production. The nationally planned wetland creation (12,000 ha) could make a significant contribution to the targeted reduction of N fluxes (up to 27% of the Swedish environmental objective), at an environmental risk equaling 0.04% of the national anthropogenic climate gas emission. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Ecological Engineering: the Journal of Ecotechnology
volume
37
issue
1
pages
6 - 15
publisher
Elsevier
external identifiers
  • wos:000287464400002
  • scopus:78650252641
ISSN
1872-6992
DOI
10.1016/j.ecoleng.2009.02.002
language
English
LU publication?
yes
id
a5b69fe1-8673-4e68-a470-5a9c875db534 (old id 1748210)
date added to LUP
2011-01-10 12:55:13
date last changed
2017-11-12 03:07:13
@article{a5b69fe1-8673-4e68-a470-5a9c875db534,
  abstract     = {Coastal eutrophication by nutrient fluxes from agricultural land to marine recipients is presently com- bated by measures such as the implementation of watershed-scale wetland creation programs aimed at nitrogen removal. Such created agricultural wetlands – termed ‘nitrogen farming wetlands’ (NFWs) – receive nitrogen (N) loads predominantly as nitrate, facilitating N removal by denitrification. However, the conversion of agricultural soils into waterlogged wetland area is likely to increase climate gas emissions, particularly methane (CH4). There is thus a need to evaluate the benefits and risks of wetland creation at a large, watershed-scale.<br/><br>
Here we investigate N retention and CH4 emission originating from watershed-scale wetland creation in South Sweden, the relation between both processes, and how CH4 emission depends on individual wetland parameters. We combine data from intensively studied reference wetlands with an extensive wetland survey to predict N retention and CH4 emission with simple models, to estimate the overall process rates (large-scale effects) as well as spatial variation among individual NFWs.<br/><br>
We show that watershed-scale wetland creation serves targeted environmental objectives (N reten- tion), and that CH4 emission is comparably low. Environmental benefit and risk of individual wetlands were not correlated, and may thus be managed independently. High cover of aquatic plants was the most important wetland property that suppressed CH4 net production, potentially facilitating N retention simultaneously. Further, differences between wetlands in water temperature and wetland age seemed to contribute to differences in CH4 net production. The nationally planned wetland creation (12,000 ha) could make a significant contribution to the targeted reduction of N fluxes (up to 27% of the Swedish environmental objective), at an environmental risk equaling 0.04% of the national anthropogenic climate gas emission.},
  author       = {Thiere, Geraldine and Stadmark, Johanna and Weisner, Stefan E.B.},
  issn         = {1872-6992},
  language     = {eng},
  number       = {1},
  pages        = {6--15},
  publisher    = {Elsevier},
  series       = {Ecological Engineering: the Journal of Ecotechnology},
  title        = {Nitrogen retention versus methane emission: Environmental benefits and risks of large-scale wetland creation},
  url          = {http://dx.doi.org/10.1016/j.ecoleng.2009.02.002},
  volume       = {37},
  year         = {2011},
}