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| Titel |
The effects of river inflow and retention time on the spatial heterogeneity of chlorophyll and water–air CO2 fluxes in a tropical hydropower reservoir |
| VerfasserIn |
F. S. Pacheco, M. C. S. Soares, A. T. Assireu, M. P. Curtarelli, F. Roland, G. Abril, J. L. Stech, P. C. Alvalá, J. P. Ometto |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 12, no. 1 ; Nr. 12, no. 1 (2015-01-09), S.147-162 |
| Datensatznummer |
250117763
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| Publikation (Nr.) |
 copernicus.org/bg-12-147-2015.pdf |
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| Zusammenfassung |
| Abundant research has been devoted to understanding the complexity of the
biogeochemical and physical processes that are responsible for greenhouse
gas (GHG) emissions from hydropower reservoirs. These systems may have
spatially complex and heterogeneous GHG emissions due to flooded biomass,
river inflows, primary production and dam operation. In this study, we
investigated the relationships between the water–air CO2 fluxes and the
phytoplanktonic biomass in the Funil Reservoir, which is an old, stratified
tropical reservoir that exhibits intense phytoplankton blooms and a low
partial pressure of CO2 (pCO2). Our results indicated that the
seasonal and spatial variability of chlorophyll concentrations (Chl) and
pCO2 in the Funil Reservoir are related more to changes in the river
inflow over the year than to environmental factors such as air
temperature and solar radiation. Field data and hydro\-dynamic simulations
revealed that river inflow contributes to increased heterogeneity during the
dry season due to variations in the reservoir retention time and river
temperature. Contradictory conclusions could be drawn if only temporal data
collected near the dam were considered without spatial data to represent
CO2 fluxes throughout the reservoir. During periods of high retention,
the average CO2 fluxes were 10.3 mmol m−2 d−1 based on
temporal data near the dam versus −7.2 mmol m−2 d−1 with spatial
data from along the reservoir surface. In this case, the use of solely
temporal data to calculate CO2 fluxes results in the reservoir acting
as a CO2 source rather than a sink. This finding suggests that the
lack of spatial data in reservoir C budget calculations can affect regional
and global estimates. Our results support the idea that the Funil Reservoir
is a dynamic system where the hydrodynamics represented by changes in the
river inflow and retention time are potentially a more important force
driving both the Chl and pCO2 spatial variability than the in-system
ecological factors. |
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