Interaction between Geochemistry, Redox Conditions and Hydro-physics
Re-establishment of wetlands on peat soils containing phosphorus bound to iron(III)-oxides can lead to an undesirable phosphorus loss to the aquatic environment due to the reductive dissolution of iron(III)-oxides. Thus it is important to be able to assess the potential phosphorus mobilisation from peat soils before a re-establishment takes place. The potential phosphorus mobilisation from a peat soil depends not only on the geochemical characteristics but also on the redox conditions, the hydrological regime in the area as well as the hydro-physical properties of the soil. The hypothesis for this study is (i) the release of phosphorus in peat is controlled by the geochemistry; (ii) the mobilisation of phosphorus is controlled by both geochemistry and hydro-physics of the soil. For this study, 10 Danish riparian lowland areas with peat soil were selected based on their geochemical characteristics. Batch experiments were used to determine the potential phosphorus release for each location. The measured phosphorus release was related to the geochemical characteristic for the respective location. Furthermore, the potential phosphorus release was compared with the measured phosphorus mobilisation for each location. This mobilisation was measured using intact soil cores (d: 6 cm; h: 15 cm) from the 10 locations set up in an anaerobic closed-flow system. Finally, the hydro- physical parameters like soil-water retention curves, break-through curves, air-filled porosity and bulk density were measured on intact soil samples from each of the 10 locations. As a result the geochemical key parameters controlling the potential phosphorus release from peat soils has been pointed out. Furthermore, it has been emphasised how much the hydro-physical properties influence the potential phosphorus mobilisation from a Danish peat soil.
Proceedings From the 7th Sws 2012 European Chapter Meeting: Wetland Restoration – Challenges and Opportunities, 2012
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Society of Wetland Scientists meeting European, 2012