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NERC has developed NORA to enable users to access research outputs wholly or partially funded by NERC. Copyright and other rights for material on this site are retained by the rights owners. Users should read the terms and conditions of use of this material at http://nora.nerc.ac.uk/policies.html#access This document is the author's final manuscript version of the journal article, incorporating any revisions agreed during the peer review process. Some differences between this and the publisher's version remain. You are advised to consult the publisher's version if you wish to cite from this article.The definitive version is available at http://onlinelibrary.wiley.com Contact CEH NORA team at noraceh@ceh.ac.ukThe NERC and CEH trademarks and logos ('the Trademarks') are registered trademarks of NERC in the UK and other countries, and may not be used without the prior written consent of the Trademark owner. (Evans et al., 2005). In the water 55 industry, the high cost of DOC removal, and associated health risks through trihalomethane 56 formation (e.g. Chow et al., 2003), result in it being widely viewed as a pollutant. Changes in DOC 57 export to surface waters also affect aquatic energy supply and light regime (due to the 58 chromophoric properties of organic compounds), with potentially major consequences for the 59 functioning of aquatic ecosystems (Cole et al., 2001; Battin et al., 2009;Karlsson et al., 2010). When 60 first detected, DOC increases were thought to be a consequence of climate change (Freeman et al., 61 2001; Hejzlar et al., 2003;Worrall & Burt, 2007; Hongve et al., 2004), and thus evidence of 62 ecosystem destabilisation, contributing to terrestrial carbon losses (Bellamy et al., 2005). Some 63 recent studies also suggest high climate-sensitivity of DOC leaching (e.g. Larssen et al., 2011; Fenner 64 & Freeman, 2011 Oulehle & Hruska, 2009; Chapman et 72 al., 2010; Arvola et al., 2010; Clark et al., 2011; Ekström et al., 2011;SanClements et al., 2012) and 73 challenging (e.g. Roulet & Moore, 2006; Eimers et al., 2008;Worrall et al., 2008; Clair et al., 2008; 74 Sarkkola et al., 2009;Sarkkola et al., 2009;Zhang et al., 2010; Couture et al., 2011; Löfgren and 75 Zetterberg, 2011; Pärn & Mander, 2012) Figure S1b). 167At the Afon Gwy AWMN site, 50 km to the south, DOC has increased by 51% over the same period , pH range 3.9 to 4.4). In addition, the Peak District peat 237 and Migneint podzol sites exhibited some pre-treatment differences in mean DOC concentrations 238 between control and treatment plots ( Figure 1, Table 1). To explore underlying relationships 239 between DOC and pH change, we therefore standardised DOC concentrations by dividing mean DOC 240 for each treatment at each site and sampling interval by the corresponding pre-treatment mean. 241Deviation from this initial level due to treatment was quantified as the ratio of mean standardised habitats showed an increase in mean pH between the two surveys, and these mean values were 296 used to calculate RH std as above,...

Abstract. Peatlands are large terrestrial stores of carbon, and sustained CO 2 sinks, but over 1 the last century large areas have been drained for agriculture and forestry, potentially 2 converting them into net carbon sources. More recently, some peatlands have been re-wetted 3 by blocking drainage ditches, with the aims of enhancing biodiversity, mitigating flooding 4 and promoting carbon storage. One potential detrimental consequence of peatland re-wetting 5 is an increase in methane (CH 4 ) emissions, offsetting the benefits of increased CO 2 6 sequestration. We examined differences in CH 4 emissions between an area of ditch-drained 7 blanket bog, and an adjacent area where drainage ditches were recently infilled. Results 8 showed that Eriophorum vaginatum colonisation led to a 'hotspot' of CH 4 emissions from the 9 infilled ditches themselves, with smaller increases in CH 4 from other re-wetted areas. 10Extrapolated to the area of blanket bog surrounding the study site, we estimated that CH 4 11 emissions were around 60 kg CH 4 ha -1 yr -1 prior to drainage, reducing to 44 kg CH 4 ha -1 yr

Rachel; Jones, Timothy G.; Lebron, Inma. 2014. UV-visible absorbance spectroscopy as a proxy for peatland dissolved organic carbon (DOC) quantity and quality: considerations on wavelength and absorbance degradation. Environmental Science: Processes & Impacts, 16 (6

Globally, there are millions of kilometres of drainage ditches which have the potential to emit the powerful greenhouse gas methane (CH4), but these emissions are not reported in budgets of inland waters or drained lands. Here, we synthesise data to show that ditches spanning a global latitudinal gradient and across different land uses emit large quantities of CH4 to the atmosphere. Area-specific emissions are comparable to those from lakes, streams, reservoirs, and wetlands. While it is generally assumed that drainage negates terrestrial CH4 emissions, we find that CH4 emissions from ditches can, on average, offset ∼10% of this reduction. Using global areas of drained land we show that ditches contribute 3.5 Tg CH4 yr−1 (0.6–10.5 Tg CH4 yr−1); equivalent to 0.2%–3% of global anthropogenic CH4 emissions. A positive relationship between CH4 emissions and temperature was found, and emissions were highest from eutrophic ditches. We advocate the inclusion of ditch emissions in national GHG inventories, as neglecting them can lead to incorrect conclusions concerning the impact of drainage-based land management on CH4 budgets.

Inland waters emit significant quantities of greenhouse gases (GHGs) such as methane (CH4) and carbon dioxide (CO2) to the atmosphere. On a global scale, these emissions are large enough that their contribution to climate change is now recognized by the Intergovernmental Panel on Climate Change. Much of the past focus on GHG emissions from inland waters has focused on lakes, reservoirs, and rivers, and the role of small, artificial waterbodies such as ponds has been overlooked. To investigate the spatial variation in GHG fluxes from artificial ponds, we conducted a synoptic survey of forty urban ponds in a Swedish city. We measured dissolved concentrations of CH4 and CO2, and made complementary measurements of water chemistry. We found that CH4 concentrations were greatest in high‐nutrient ponds (measured as total phosphorus and total organic carbon). For CO2, higher concentrations were associated with silicon and calcium, suggesting that groundwater inputs lead to elevated CO2. When converted to diffusive GHG fluxes, mean emissions were 30.3 mg CH4·m−2·d−1 and 752 mg CO2·m−2·d−1. Although these fluxes are moderately high on an areal basis, upscaling them to all Swedish urban ponds gives an emission of 8336 t CO2eq/yr (±1689) equivalent to 0.1% of Swedish agricultural GHG emissions. Artificial ponds could be important GHG sources in countries with larger proportions of urban land.

Ditch blocking in blanket peatlands is common as part of peatland restoration. The effects of ditch blocking on flow regimes and nearby water tables were examined in a field trial. After an initial 6‐month monitoring period, eight ditches had peat dams installed 10 m apart along their entire length (dammed), four of these ditches were also partially infilled through bank reprofiling (reprofiled). Four ditches were left open with no dams or reprofiling (open). These 12 ditches and the surrounding peat were monitored for 4 more years. An initial five‐fold reduction in discharge occurred in the dammed and the reprofiled ditches with the displaced water being diverted to overland flow and pathways away from the ditches. However, there was a gradual change over time in ditch flow regime in subsequent years, with the overall volume of water leaving the dammed and the reprofiled ditches increasing per unit of rainfall to around twice that which occurred in the first year after blocking. Hence, monitoring for greater than one year is important for understanding hydrological impacts of peatland restoration. Overland flow and flow in the upper ~4 cm of peat was common and occurred in the inter‐ditch areas for over half of the time after ditch blocking. There was strong evidence that topographic boundaries of small ditch catchments, despite being defined using a high‐resolution Light Detection And Ranging‐based terrain model, were not always equivalent to actual catchment areas. Hence, caution is needed when upscaling area‐based fluxes, such as aquatic carbon fluxes, from smaller scale studies including those using ditches and small streams. The effect of ditch blocking on local water tables was spatially highly variable but small overall (time‐weighted mean effect <2 cm). Practitioners seeking to raise water tables through peatland restoration should first be informed either by prior measurement of water tables or by spatial modelling to show whether the peatland already has shallow water tables or whether there are locations that could potentially undergo large water‐table recoveries.

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