A model of potential carbon dioxide efflux from surface water across England and Wales using headwater stream survey data and landscape predictors
Measurements of CO<sub>2</sub> partial pressures (<i>p</i>CO<sub>2</sub>) in small headwater streams are useful for predicting potential CO<sub>2</sub> efflux because they provide a single concentration representing a mixture from different hydrologica...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2014-04-01
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| Series: | Biogeosciences |
| Online Access: | http://www.biogeosciences.net/11/1911/2014/bg-11-1911-2014.pdf |
| Summary: | Measurements of CO<sub>2</sub> partial pressures (<i>p</i>CO<sub>2</sub>) in small headwater
streams are useful for predicting potential CO<sub>2</sub> efflux because they
provide a single concentration representing a mixture from different
hydrological pathways and sources in the catchment. We developed a model to
predict <i>p</i>CO<sub>2</sub> in headwater streams from measurements undertaken on
snapshot samples collected from more than 3000 channels across the landscape
of England and Wales. We used a subset of streams with upstream catchment
areas (CA) of less than 8 km<sup>2</sup> because below this scale threshold
<i>p</i>CO<sub>2</sub> was independent of CA. A series of catchment characteristics were
found to be statistically significant predictors of <i>p</i>CO<sub>2</sub>, including
three geomorphic variables (mean altitude, mean catchment slope and relief)
and four groups of dominant catchment land cover classes (arable, improved
grassland, suburban and all other classes). We accounted for year-round,
temporal variation in our model of headwater <i>p</i>CO<sub>2</sub> by including weekly
or monthly analyses of samples from three headwater catchments with different
land use and geomorphic features. Our model accounted for 24% of the
spatial and temporal variation in <i>p</i>CO<sub>2</sub>.
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We combined predictions from the <i>p</i>CO<sub>2</sub> model (on a 1 km grid) and
monthly runoff volumes (litres) on 0.5° resolution grid across
England and Wales to compute potential C fluxes to the atmosphere. Our model
predicts an annual average potential C flux of 65.4 kt C across England and
Wales (based on free C concentrations), with lower and upper 95% confidence
values of 56.1 and 77.2 kt C, respectively. |
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| ISSN: | 1726-4170 1726-4189 |