Export of dissolved organic carbon from an upland peatland during storm events: Implications for flux estimates

Clark, J. M.; Lane, Stuart N.; Chapman, P. J.; Adamson, J.

doi:10.1016/j.jhydrol.2007.09.030

Cited by 161 publications

(174 citation statements)

References 36 publications

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“…Moreover, the characteristics of rainfall, runoff volume and storm events have a great impact on pesticide transport and losses (Muller et al, 2003). The role of stormy periods is highlighted in transport of TSM and DOC, and the findings are in accordance with the survey results of Clark et al (2007), Zhang et al (2009) and Ollivier et al (2010). A cyclical trajectory relationship (hysteresis) has already been reported between river discharge and solute concentration during storm events (Jardine et al, 1990;Hill, 1993).…”

Section: Discussionsupporting

confidence: 75%

“…Hourly mean discharge values were available for all sampling points for the entire investigation periods from CACG (Compagnie d'Aménagement des Coteaux de Gascogne), in charge of the Larra gauging station. This method is common in the literature to estimate the flux of the organic carbon, the total suspended matter and the pesticide (Walling and Webb, 1985;Hope et al, 1997;Worrall and Burt, 2004;Clark et al, 2007).…”

Section: > Flux Calculationmentioning

confidence: 99%

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The role of storm flows in concentration of pesticides associated with particulate and dissolved fractions as a threat to aquatic ecosystems - Case study: the agricultural watershed of Save river (Southwest of France)

Taghavi

Merlina

Probst

2011

Knowl. Managt. Aquatic Ecosyst.

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Key-words: pesticide, TSM, DOC, hysteresis patterns, flood flowMeasurement of the fluxes of pesticides was carried out for a year, ending in March 2009, in the Save catchment, in the vicinity of Toulouse. The hydrograph separation technique was used to evaluate the respective contribution of stormflow and baseflow in transport of 12 pesticide molecules. Transport of over 59% of pesticides and their controlling factors such as total suspended matter (TSM), particulate organic carbon (POC) and dissolved organic carbon (DOC) occurred during storm periods. Hysteresis patterns could be observed in the concentration-discharge relationships only for some molecules between rising and falling periods of the storm hydrograph. Clockwise hysteresis was noticed for low to moderately soluble pesticide molecules and for particulate fractions, which explains the role of surface runoff in pesticide displacement. In contrast, anticlockwise hysteresis was registered for soluble molecules and dissolved fractions, explaining the role of subsurface flows and soil leaching processes. The important role of TSM, POC and DOC in pesticide transport was clearly established. We also came to the conclusion that the role of stormy periods in pesticide movement and their controlling factors worked as a threat to aquatic ecosystems. And there was a positive relation between riverine TSM, POC, DOC and pesticides according to pesticide properties. RÉSUMÉLe rôle des crues sur la concentration en pesticides associés aux fractions particulaires et dissoutes, une menace pour les écosystèmes aquatiques Cas d'étude : le bassin versant agricole de la rivière Save (sud-ouest de la France) Mots-clés :pesticide, MES, COD, hystérésis, crue transportés durant les périodes de crue. Des hystérésis peuvent être observées sur les relations concentrations-débits, uniquement pour quelques molécules, entre la montée et la descente de crue. Des hystérésis dextres (sens des aiguilles d'une montre) sont observées pour les molécules peu ou modérément solubles et pour les fractions particulaires montrant le rôle du ruissellement de surface dans le transfert des pesticides. Au contraire, des hystérésis senestres (sens inverse) sont observées pour les molécules solubles et les fractions dissoutes montrant le rôle des écoulements hypodermiques et du lessivage des sols. On a pu établir clairement le rôle important des MES, du COP et du COD dans le transport des pesticides. Les résultats obtenus nous montrent aussi le rôle joué par les épisodes de crue sur les transferts de pesticides et de leurs facteurs de contrôle, représen-tant un risque potentiel important de contamination des eaux et une menace pour les écosystèmes aquatiques. Des relations positives sont mises en évidence entre les teneurs en MES, COD ou COP et les concentrations en pesticides selon les propriétés physico-chimiques des différents pesticides.

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Section: Discussionsupporting

confidence: 75%

Section: > Flux Calculationmentioning

confidence: 99%

The role of storm flows in concentration of pesticides associated with particulate and dissolved fractions as a threat to aquatic ecosystems - Case study: the agricultural watershed of Save river (Southwest of France)

Taghavi

Merlina

Probst

2011

Knowl. Managt. Aquatic Ecosyst.

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“…It is produced through biological activity including plant exudation and decomposition processes, although its transport into drainage waters is also influenced by hydrological factors (e.g. Clark et al, 2007) and chemical solubility controls . Once in the drainage network, it is susceptible to photochemical breakdown (e.g.…”

Section: 'On-site' and 'Off-site' Emissionsmentioning

confidence: 99%

The role of waterborne carbon in the greenhouse gas balance of drained and re-wetted peatlands

2015

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Article (refereed) -postprintEvans, Chris D.; Renou-Wilson, Flo; Strack, Maria. 2016. The role of waterborne carbon in the greenhouse gas balance of drained and rewetted peatlands [in special issue: Carbon cycling in aquatic ecosystems] Aquatic Sciences, 78 (3). 573-590. 10.1007/s00027-015-0447-y 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.The role of waterborne carbon in the greenhouse gas balance of drained and re-wetted peatlands AbstractAccounting for greenhouse gas (GHG) emissions and removals in managed ecosystems has generally focused on direct land-atmosphere fluxes, but in peatlands a significant proportion of total carbon loss occurs via fluvial transport. This study considers the composition of this 'waterborne carbon' flux, its potential contribution to GHG emissions, and the extent to which it may change in response to land-management. The work describes, and builds on, a methodology to account for major components of these emissions developed for the 2013 Wetland Supplement of the Intergovernmental Panel on Climate Change. We identify two major components of GHG emissions from waterbodies draining organic soil: i) 'on site' emissions of methane (and to a lesser extent CO2) from drainage ditches located within the peatland; and ii) 'off site' emissions of CO2 resulting from downstream oxidation of dissolved and particulate organic carbon (DOC and POC) within the aquatic system. Methane emissions from ditches were found to be large in many cases (mean 60 g CH4 m -2 yr -1 based on all reported values), countering the view that methane emissions cease following wetland drainage. Emissions were greatest from ditches in intensive agricultural peatlands, but data were sparse and showed high variability. For DOC, the magnitude of the natural flux varied strongly with latitude, from 5 g C m -2 yr -1 in northern boreal peatlands to 60 g C m -2 yr -1 in tropical peatlands. Available data suggest that DOC fluxes increase by around 60% following drainage, and that this increase may be reversed in the longer-term through re-wetting, although variability between studies was high, especially in relation to re-wetting response. Evidence regarding the fate of DOC is complex and inconclusive, but overall suggests that the majority of DOC exported from peatlands is converted to CO2 through photo-and/or bio-degradation in rivers, standing waters and oceans. The contribution of POC export to GHG emissions is even more uncertain, but we estimate that over half of exported POC may eventually be converted to CO2. Although POC fluxes are normally small, they can become very large when bare peat surfaces are exposed to fluvial erosion. Overall, we estimate that waterborne carbon emissions may contribute about 1 to 4 t CO2-eq ha -1 yr -1 of additional GHG emissions from drained peatlands. For a number of worked examples this repres...

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“…Therefore, sampling DOC at monthly or weekly intervals in rivers draining ombrotrophic peatlands is likely to be inadequate for deriving annual flux estimates because crucial phases of flow will probably be under-represented by the samples. For this reason some researchers also supplement their weekly (or less frequent) sampling regime with storm event sampling for a handful of events throughout the year (Clark et al, 2007;Worrall et al, 2012). While this additional storm sampling may provide improved estimates of DOC flux there will still be large uncertainties because the relationship between discharge and DOC concentration is non-linear and may vary strongly depending on antecedent conditions.…”

Section: Introductionmentioning

confidence: 99%

Improved automation of dissolved organic carbon sampling for organic-rich surface waters

Grayson

Holden

2016

Science of The Total Environment

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In-situ UV-Vis spectrophotometers offer the potential for improved estimates of dissolved organic carbon (DOC) fluxes for organic-rich systems such as peatlands because they are able to sample and log DOC proxies automatically through time at low cost. In turn, this could enable improved total carbon budget estimates for peatlands. The ability of such instruments to accurately measure DOC depends on a number of factors, not least of which is how absorbance measurements relate to DOC and the environmental conditions. Here we test the ability of a S::can Spectro::lyser TM for measuring DOC in peatland streams with routinely high DOC concentrations. Through analysis of the spectral response data collected by the instrument we have been able to accurately measure DOC up to 66 mg L -1 , which is more than double the original upper calibration limit for this particular instrument. A linear regression modelling approach resulted in an accuracy > 95%. The greatest accuracy was achieved when absorbance values for several different wavelengths were used at the same time in the model. However, an accuracy > 90% was achieved using absorbance values for a single wavelength to predict DOC concentration. Our calculations indicated that, for organicrich systems, in-situ measurement with a scanning spectrophotometer can improve fluvial DOC flux estimates by 6 to 8% compared with traditional sampling methods. Thus, our techniques pave the way for improved long-term carbon budget calculations from organicrich systems such as peatlands.

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Export of dissolved organic carbon from an upland peatland during storm events: Implications for flux estimates

Cited by 161 publications

References 36 publications

The role of storm flows in concentration of pesticides associated with particulate and dissolved fractions as a threat to aquatic ecosystems - Case study: the agricultural watershed of Save river (Southwest of France)

The role of storm flows in concentration of pesticides associated with particulate and dissolved fractions as a threat to aquatic ecosystems - Case study: the agricultural watershed of Save river (Southwest of France)

The role of waterborne carbon in the greenhouse gas balance of drained and re-wetted peatlands

Improved automation of dissolved organic carbon sampling for organic-rich surface waters

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