Abstract
Abstract. Drained peatlands are significant hotspots of carbon dioxide (CO2) emissions and may also be more vulnerable to fire with its associated gaseous emissions. Under the United Nations Framework Convention on Climate Change (UNFCCC) and the Kyoto Protocol, greenhouse gas (GHG) emissions from peatlands managed for extraction are reported on an annual basis. However, the Tier 1 (default) emission factors (EFs) provided in the IPCC 2013 Wetlands Supplement for this land use category may not be representative in all cases and countries are encouraged to move to higher-tier reporting levels with reduced uncertainty levels based on country- or regional-specific data. In this study, we quantified (1) CO2-C emissions from nine peat extraction sites in the Republic of Ireland and the United Kingdom, which were initially disaggregated by land use type (industrial versus domestic peat extraction), and (2) a range of GHGs that are released to the atmosphere with the burning of peat. Drainage-related methane (CH4) and nitrous oxide (N2O) emissions as well as CO2-C emissions associated with the off-site decomposition of horticultural peat were not included here. Our results show that net CO2-C emissions were strongly controlled by soil temperature at the industrial sites (bare peat) and by soil temperature and leaf area index at the vegetated domestic sites. Our derived EFs of 1.70 (±0.47) and 1.64 (±0.44) t CO2-C ha−1 yr−1 for the industrial and domestic sites respectively are considerably lower than the Tier 1 EF (2.8 ± 1.7 t CO2-C ha−1 yr−1) provided in the Wetlands Supplement. We propose that the difference between our derived values and the Wetlands Supplement value is due to differences in peat quality and, consequently, decomposition rates. Emissions from burning of the peat (g kg−1 dry fuel burned) were estimated to be approximately 1346 CO2, 8.35 methane (CH4), 218 carbon monoxide (CO), 1.53 ethane (C2H6), 1.74 ethylene (C2H4), 0.60 methanol (CH3OH), 2.21 hydrogen cyanide (HCN) and 0.73 ammonia (NH3), and this emphasises the importance of understanding the full suite of trace gas emissions from biomass burning. Our results highlight the importance of generating reliable Tier 2 values for different regions and land use categories. Furthermore, given that the IPCC Tier 1 EF was only based on 20 sites (all from Canada and Fennoscandia), we suggest that data from another 9 sites significantly expand the global data set, as well as adding a new region.
Highlights
Greenhouse gas (GHG) emissions to the atmosphere have increased significantly since pre-industrial times as a direct result of human activities, such as fossil fuel burning, cementPublished by Copernicus Publications on behalf of the European Geosciences Union.D
The objectives of the study are (1) to provide estimates of the annual CO2-C exchange (i.e. CO2-Con−site) for nine peat extraction sites in the Republic of Ireland (ROI) and the United Kingdom (UK), (2) to derive regional-specific CO2-C emission factors (EFs) for drained peat extraction areas that would permit the ROI and the UK to progress to the Tier 2 reporting level, (3) analyse the factors that influence CO2-C dynamics in this region, and (4) to report GHG emissions associated with the burning of Irish Sphagnum moss peat in the first laboratory study to investigate fire emissions from European temperate peats
Rainfall and site water table levels were similar to the other sites, soil temperatures at this site remained below 0 ◦C for a high proportion (∼ 14 %) of the year and are likely to have resulted in a slowdown of extracellular enzymatic diffusion (Davidson and Janssens, 2006), reduced microbial activity (Fenner et al, 2005) and lower rates of CO2 production (Basiliko et al, 2007)
Summary
Greenhouse gas (GHG) emissions to the atmosphere have increased significantly since pre-industrial times as a direct result of human activities, such as fossil fuel burning, cementD. Natural (i.e. undrained) peatlands function as long-term carbon (C) stores as the sequestration of CO2 over time is greater than the amount of C that is emitted from the peatland as methane (CH4) and leached in waterborne exports (Roulet et al, 2007; Nilsson et al, 2008; Koehler et al, 2011; Gažovicet al., 2013). Key to this role is the position of the water table, which largely dictates the rate of decomposition within the peatland. There is an accumulation of peat (and C within; Dise, 2009)
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