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| Titel |
Contribution of different land-cover types to CO2 emissions from streams and rivers, in South-Western Germany |
| VerfasserIn |
Celia Somlai, Ralf B. Schaefer, Andreas Lorke |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250089586
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| Publikation (Nr.) |
 EGU/EGU2014-14676.pdf |
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| Zusammenfassung |
| Recent findings indicate that freshwater ecosystems are significant sources of atmospheric
greenhouse gases. While most quantitative estimates of CO2 emissions were obtained
for lakes, reservoirs, and rivers, only few studies considered smaller streams and
headwater systems. Here, we present estimates of the CO2 emissions from the 16 *
106 km long stream network in South-Western Germany (22272 km2) including
streams of Strahler order 1-7. We calculated equilibrium dissolved inorganic carbon
speciation and partial pressure of dissolved CO2from governmental water quality
monitoring data (pH, temperature and alkalinity) available for 37 years. CO2 partial
pressure estimated for 1780 sampled stream segments were linearly extrapolated
along the entire stream network consisting of 7890 segments. The mean partial
pressure of dissolved CO2 was 2286 ppm with a high spatial variation (SD 2735
ppm).
Moreover, the gas exchange velocity for each stream segment was estimated using flow
velocity and slope. Our calculations based on dissolved CO2 concentration, gas
exchange velocity and water surface area yield a total emission rate of 86 Gg C per
year with mean 1240 mg C m-2 d-1arealflux. Stream segments with a Strahler
order between 1 and 4 contributed to 48% of the total emissions, highlighting the
importance of smaller streams and headwater systems for regional-scale carbon
fluxes.
Finally, we investigated the contribution of land-cover types to CO2 emissions. Our study
area was divided into 6 different land-cover types, forested, cultivated, grassland, urbanized,
vineyard and tree nursery. Areal normalized emissions of urbanized, vineyard, tree
nursery, grassland, forested and cultivated were 17, 16, 12, 9, 8, 7 mg C m-2 d-1,
respectively.
The results of our study show clearly, that small streams play a non-negligible role in the
carbon emissions from freshwaters. In addition, land cover further impacts the carbon
emissions, e.g. urbanized areas showed the highest flux rates. |
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