The impact of ditch blocking on fluvial carbon export from a <scp>UK</scp> blanket bog

Evans, C. D.; Peacock, Mike; Green, Sophie M.; Holden, Joseph; Chapman, P. J.; Lebron, Inma; Callaghan, Nathan; Grayson, Richard; Baird, Andrew J.

doi:10.1002/hyp.13158

Cited by 17 publications

(26 citation statements)

References 46 publications

(103 reference statements)

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“…Detailed data concerning the dynamics of DOC quantity at this site are presented by Evans et al () but in summary (Table ) show no effect of rewetting on concentrations or fluxes of DOC. Changes in water table following blocking were variable but very small (<2 cm; Holden et al, ), but rewetting did lead to increases in wet‐indicator testate amoeba suggesting the creation of wetter conditions across the site (Swindles et al, ).…”

Section: Discussionmentioning

confidence: 85%

“…Repeated measures ANOVA showed no significant treatment effect for any water type. Full data and details of statistical analysis are detailed in Evans et al ().…”

Section: Resultsmentioning

confidence: 99%

“…Peat dams are also placed along the reprofiled ditches, creating shallow pools. The experimental site was used to investigate the effects of peatland rewetting on numerous ecological responses such as greenhouse gas emissions (Green et al, ), DOC fluxes (Evans et al, ), hydrology (Holden et al, ), vegetation (Green et al, ), extracellular enzyme activity (Peacock et al, ), and testate amoeba (Swindles et al, ). Further information concerning the study site can be found in Green et al () and includes soil physical and chemical properties, detailed meteorological data, and ditch topographical details.…”

Section: Methodsmentioning

confidence: 99%

“…Mean pH was 4.2, 4.1, and 5.1, and mean EC was 49.3, 60.6, and 53.8 μS cm −1 for ditch water ( n = 624), pore water ( n = 480), and overland flow water ( n = 1,065), respectively. Full water chemistry data are presented in Evans et al () and comprise DOC, POC, dissolved CH 4 and CO 2 , pH, EC, and alkalinity.…”

Section: Methodsmentioning

confidence: 99%

“…Armstrong et al () conducted a snapshot survey across a number of sites and found that DOC concentrations were lower in blocked ditches with flowing water compared to unblocked ditches with flowing water, but this difference was not significant at the conventional p < 0.05 significance threshold. Some studies have found significant effects of rewetting on DOC concentrations but of such small magnitude that they will have no meaningful impact on water treatment (e.g., 0.3 mg L −1 by Gibson, Worrall, Burt, and Adamson (); 2.5% by Turner, Worrall, and Burt (), both of which had preblocking data), especially considering that the annual range in DOC in such systems can be ~25 mg L −1 (Evans et al, ), and that individual storm events can increase DOC by ~10 mg l −1 (Austnes, Evans, Eliot‐Laize, Naden, & Old, ). It is worth noting that the majority of blanket bog rewetting studies compare drained and rewetted treatments, due to the fact that most U.K. blanket bog has been managed by drainage, grazing, or burning, leaving little undisturbed bog left (Ramchunder et al, ).…”

Section: Introductionmentioning

confidence: 99%

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Peatland ditch blocking has no effect on dissolved organic matter (DOM) quality

Peacock

Jones

Futter

et al. 2018

Hydrological Processes

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The globally widespread drainage of peatlands has often been shown to lead to increased concentrations and fluxes of dissolved organic carbon (DOC) in streams and rivers. Elevated DOC concentrations have implications for carbon cycling, ecosystem functioning, and potable water treatment. Peatland rewetting, principally through ditch blocking, is often carried out with the expectation that this will reduce DOC concentrations. Uncertainty still remains as to whether drainage, or its reversal via ditch blocking, will also lead to changes in the molecular composition of DOC/dissolved organic matter (DOM), which have the potential to affect downstream processing and treatability of U.K. drinking water supplies. To investigate this question, we used a replicated experiment consisting of 12 parallel ditches on an upland bog and took samples of ditch water, pore water, and overland flow water for 4 years. After a brief preblocking baseline period, eight ditches were blocked using two methods. A complementary suite of optical metrics, chemical measurements, and analytical techniques revealed that ditch blocking had no consistent effect on DOM quality, up to 4 years after blocking. Where significant differences were found, effect size calculations demonstrated that these differences were small and would therefore have minimal impact upon water treatability. Furthermore, some differences between ditches were evident before blocking took place, highlighting the need for robust baseline monitoring before intervention. Based on our results from a hillslope‐scale experiment, we were unable to identify clear evidence that peatland ditch blocking will deliver benefits in terms of DOM treatability in potable water supplies, although we also did not find any evidence of short‐term deterioration in water quality during the restoration period. We conclude that, although peatland restoration can be expected to deliver other benefits such as reduced carbon loss and enhanced biodiversity, it is doubtful whether it will lead to improvements in drinking water treatability.

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Section: Discussionmentioning

confidence: 85%

“…Repeated measures ANOVA showed no significant treatment effect for any water type. Full data and details of statistical analysis are detailed in Evans et al ().…”

Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Peatland ditch blocking has no effect on dissolved organic matter (DOM) quality

Peacock

Jones

Futter

et al. 2018

Hydrological Processes

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Organic Carbon Flux in Ditches during the Growing Season in a Drained Alpine Peatland

Wang

et al. 2019

Ecohydrology

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The carbon budget dynamics of peatlands plays a crucial role in both the response of peatland ecosystems to environmental change and the effect of environmental change on peatlands. Studies on northern peatlands have suggested that the reliable assessment of the carbon budget must include the carbon flux at the land-stream interface. But this argument has not been proved in the Qinghai-Tibet Plateau, the world's largest alpine system. To address the knowledge gap, in the growing season (May to October) of 2016, we chose Riganqiao peatland, a typical peatland in the Zoige Basin of the Qinghai-Tibet Plateau which has been intensely drained via ditches since the 1960s. The objective of this study was to measure the organic carbon export from ditches, and to estimate what proportion of the carbon budget can be attributed to this export. Results showed that, during the growing season in 2016, total organic carbon flux in ditches was 2,345 t (8.6 g m −2 ), of which particulate organic carbon accounted for 12% and dissolved organic carbon for 88%. This flux decreased the carbon budget of Riganqiao peatland by 11.2% (from +76.8 g m −2 to +68.2 g m −2 ), making it a weakened carbon sink. This result revealed that organic carbon export from ditches plays an important role in the carbon balance in peatland of the Qinghai-Tibet Plateau.

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Towards understanding organic matter fluxes and reactivity in surface waters: Filtering impact on DOC and POC degradation

Moody

Worrall

2021

Hydrological Processes

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Peatlands cover a very small area of the Earth, but store globally significant quantities of carbon and export disproportionate quantities of fluvial organic carbon, especially when the peatlands are degraded or disturbed. Peatland headwater catchments with high concentrations of dissolved and particulate organic carbon (DOC and POC) provide an opportunity to investigate the possibility of competing effects that could lead to enhanced or diminished turnover of DOC in the presence of POC. Both POC and DOC can be degraded by light and microbes, producing smaller molecules and releasing CO 2 and CH 4 to the atmosphere, and POC can inhibit light penetration, stabilize DOC by providing adsorption sites and providing surfaces for microbes to interact with DOC. However, the majority of peatland fluvial carbon studies are conducted using filtered water samples, and measure only the DOC concentration, so the impact of the particulate organic matter (POM) on in-stream processing of organic carbon is relatively unknown. It is therefore possible that studies have underestimated carbon transformations in rivers as they have not considered the interaction of the particulate material on the dissolved concentrations; there could be higher losses than previously estimated, increasing the contribution of peatland headwaters to GHG emissions. In this study, we assessed if the current approach of DOC degradation studies accurately represent the impact of POM on DOC degradation, by quantifying DOC production from POM, and therefore POC, over time in water with manipulated POM concentrations. Both filtered and unfiltered water lost 60% of the DOC over 70 hours, whereas the treatment with additional POM lost only 35%. The results showed that filtering does not significantly impact the DOC degradation rates; however, when the POC concentration was doubled, there was a significant reduction in DOC degradation, suggesting that filtering would still be necessary to get accurate rates of DOC transformations in waters with high POC concentrations.

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The impact of ditch blocking on fluvial carbon export from a UK blanket bog

Cited by 17 publications

References 46 publications

Peatland ditch blocking has no effect on dissolved organic matter (DOM) quality

Peatland ditch blocking has no effect on dissolved organic matter (DOM) quality

Organic Carbon Flux in Ditches during the Growing Season in a Drained Alpine Peatland

Towards understanding organic matter fluxes and reactivity in surface waters: Filtering impact on DOC and POC degradation

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