Kurzfassung

Inland waters transport and transform large amounts of carbon and account for ~18% of global methane emissions. Recent estimates point towards a significant contribution to these emissions from man-made reservoirs. Actual emission rates have mainly been estimated for large reservoirs located in the tropics and in
the boreal zone. In a reference study at six impoundments of the River Saar in Central Europe, we have demonstrated that also smaller reservoirs, which are not considered in global...Inland waters transport and transform large amounts of carbon and account for ~18% of global methane emissions. Recent estimates point towards a significant contribution to these emissions from man-made reservoirs. Actual emission rates have mainly been estimated for large reservoirs located in the tropics and in
the boreal zone. In a reference study at six impoundments of the River Saar in Central Europe, we have demonstrated that also smaller reservoirs, which are not considered in global assessments, can be a significant and unexpectedly strong source for atmospheric methane. The spatial and temporal dynamics of
the corresponding fluxes are mainly determined by the spatial distribution of sediment deposition and by temporal variations of hydrodynamic conditions. Both are, to a large extent, controlled by anthropogenic activities associated with river management and navigation. Here we apply for a renewal period of project funding, where we aim at answering follow-up research questions regarding the environmental conditions potentially affecting methane emissions from impounded
rivers and therewith the larger-scale significance of our findings from the Saar. In particular we will investigate the processes controlling bubble formation and evasion from river sediments at greater detail by developing a
mechanistic model for methane and other gas phase dynamics within the sediment and in the overlaying water column. The model will be validated using extensive field measurements from various impoundments within the Rhine river system, differing in sediment and water-quality characteristics. Based on the methodologies developed during the first project phase, we will estimate methane emission rates along with their spatial and temporal variations. In combination with existing data sets, particularly on the spatial distribution of fine sediments within the Rhine and its tributaries, the model will be used to estimate larger-scale emission rates and their response to changing temperature and sediment management measures.» weiterlesen» einklappen