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| Titel |
Quantifying impacts of windfarm development on peatland for aquatic carbon, nitrogen and phosphorus fluxes |
| VerfasserIn |
Antony Phin, Kate Heal, Susan Waldron, Hugh Flowers |
| Konferenz |
EGU General Assembly 2013
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250072472
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| Zusammenfassung |
| Many onshore windfarms in Scotland are being built on peatlands; consequently the
impacts of construction-related activities on the peatland itself and downstream
environments are an important emerging issue. For example, a reduction of the quantity of
carbon (C) stored in the peatland and increased phosphorus (P) and nitrogen (N)
concentrations in streams may cause changes in the peatland C sink strength and aquatic C
emissions and exceedance of EU Water Framework Directive (WFD) threshold
values, respectively. Quantifying the fluxes of C, N and P via streams draining
peatland has often been overlooked when assessing impacts from peatland based
development.
To address this gap, a three-weekly streamwater monitoring programme has been
conducted from August 2011 at a site in central Scotland, UK, where windfarm
construction on peatland is ongoing. Eighteen streamwater sampling points were selected
in the study catchment area of 11.5 km2 to assess the effect on aquatic fluxes of
the typical activities involved in windfarm construction on peatland in the UK.
These are: excavation of peat to install turbine bases and cable trenches, excavation
of quarries to obtain hardcore for windfarm roads, the construction of roads and
associated drainage, and forest felling to create space for the turbines and increase wind
fetch. Streamwater samples were analysed for dissolved organic carbon (DOC),
particulate organic carbon (POC), alkalinity, total oxidisable nitrogen (TON: NO3- +
NO2-), soluble reactive phosphorus (SRP) and total phosphorus (TP). Exports of
DOC, POC, TON and SRP have been calculated using continuously monitored flow
data from the catchment outlet, scaled to the sub-catchment area of each sampling
point.
To date, streamwater [DOC] has ranged from 6.2 to 89 mg l-1, [TON] from 0.01 to 7.2
mg l-1, [POC] from 0.02 to 18 mg l-1 and SRP concentrations from 4 to 516 μg l-1. [TON]
was not considered an issue in the streams since P is the limiting nutrient. [DOC] measured at
the catchment outlet and the control sampling point in the headwaters are very
similar, despite the increase in flow between the two points, indicating contributions
to DOC from the land use activities in the catchment. The annual mean [SRP] at
sampling points downstream of forest felling exceeded the “poor” WFD threshold value
of 150Â μg l-1 for an upland stream with annual mean alkalinity below 50Â mg
l-1 as CaCO3. A GIS analysis is being conducted to assess the extent to which
construction-related activities control concentrations and fluxes of aquatic C, N and P. The
results of this can be used to suggest how to improve windfarm construction on
peatland so as to limit negative impacts on C storage and emissions and on aquatic
ecosystems.
Keywords: carbon cycle, DOC, forest felling, peatlands, phosphorus, windfarms |
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