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| Titel |
DOC export from an upland peat catchment in the Flow Country, northern Scotland |
| VerfasserIn |
Shailaja Vinjili, Ruth Robinson, Yit Arn Teh, Susan Waldron, Michael Singer |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250041906
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| Zusammenfassung |
| ABSTRACT
Flow Country blanket bogs in northern Scotland are the most expansive in Europe covering
an area of ~4000 km2, and they significantly impact the global carbon cycle because of their
high rates of carbon production and storage, as well as their role in the transfer of
carbon to oceans through rivers or greenhouse gas exchange (Moore et al., 1998).
These upland areas are highly susceptible to climatic and landuse changes, and
currently, large areas of previously drained and forested peatlands are being felled
and blocked to increase the water table level and rejuvenate the peatlands (LIFE
Peatlands Project 2001-2006; Holden et al., 2004). This study is examining the
event-based export of dissolved and particulate organic carbon (DOC and POC) from one
of the main upland Flow Country catchments that drains into the north-draining
Halladale River. For a time-series of summer rainfall events, we have focussed
particularly on a comparison of DOC/POC exports from three different land use areas in
the catchment: forested plots, felled to waste (restoration) plots (felled between
2005-2007), and near-pristine bog sites. DOC concentrations have been measured using a
combination of methods including TOC and EA analyses, and in situ absorbance
measurements using a spectrophotometer (Thurman, 1985; Worrall et al., 2002). Our results
show that the stream water draining the felled to waste site records the highest
levels of DOC concentration (and DOC variability), and the near-pristine site has
the lowest export rate of DOC (and lowest variability). All sites exhibit positive
DOC responses to the flood hydrograph, and the near-pristine and forested sites
have a similar maximum concentrations of DOC. The felled site concentrations are
about 2times greater than the near-pristine and forested sites, and the non-linear
response to flow reflects the hydrophobic nature of peats after a period of drought,
and the lag time required for them to saturate. The integrated downstream DOC
concentrations on forested land and on the main stem of the Halladale River have
“forest-like” values reflecting a dilution in DOC concentrations from the felled site, and
mixing of stream water from other sources. The initial results from this study imply
that i) the felled to waste site (after 2-3 years) releases the highest (up to x2) DOC
into stream waters that drain them, ii) DOC concentrations are more sensitive to
hydrological variation in sites felled to waste but not yet fully restored, and iii)
saturation-excess overland flow is the predominant response of near-pristine site to the
rainfall events.
References:
Holden J., Chapman P.J., and Labadz J.C. 2004. Artificial drainage of peatlands:
hydrological and hydrochemical process and wetland restoration. Progress in Phy Geography,
28, 1, pp: 95-123.
Life Peatlands Project 2001-2006. www.lifepeatlandsproject.com
Moore T.R., Roulet N.T. and Waddington J.M. 1998. Uncertainty in Predicting the Effect
of Climatic Change on the Carbon Cycling of Canadian Peatlands. Climate Change, 40, 2,
pp: 229-245.
Thurman E.M. 1985. Organic Geochemistry of Natural Waters. Netherlands, Martinus
Nijhoff/Dr. W.Junk Publishers.
Worrall F., Burt T. P., Jaeban R. Y., Warburton ,J. and R. Shedden, 2002. Release
of dissolved organic carbon from upland peat. Hydrol. Process. 16, 3487–3504. |
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