22-27 September 2019
Trade Fairs and Congress Center (FYCMA)
Europe/Madrid timezone

Inverse modelling of hydrogeochemical processes analysed along a flowpath within the Doñana National Park (Southern Spain)

23 Sep 2019, 16:00
1h
Trade Fairs and Congress Center (FYCMA)

Trade Fairs and Congress Center (FYCMA)

Av. de José Ortega y Gasset, 201 29006 Malaga, Spain
Poster Topic 1 - Groundwater assessment and management Poster with refreshments

Speaker

Mrs Ana Fernández-Ayuso (Pablo de Olavide University)

Description

The Santa Olalla pond is the only permanent pond located in the Doñana National Park (Southern Spain). Hydrochemistry of both surface and groundwater samples was analyzed during 2017 and 2018. Those samples were representative of the wet and dry seasons, respectively. In total, 22 samples were analyzed. Samples were taken in alignment with the general flow path from the dunes to the pond. Sampling points were: one medium-depth piezometer (21 m depth), three shallow piezometers (3 m) and surface water. Groundwater samples were taken using a pump and conserved for subsequent analysis. Physical-chemical parameters and iron analysis were measured in situ. Salinity values ranged from 45 mg/l at the beginning of the flow path, close to the dunes, to 8,850 mg/l in the pond itself. Facies varied from calcium-bicarbonate to sodium-chloride facies depending both on seasonality and location. The three inverse model scenarios performed with Phreeqc 3.0 and the database Wateq4f reveal sulfate reduction, redox reactions (Fe-S), mineral dissolution-precipitation, evaporation and mixing with deep water. These processes change seasonally, in accordance with hydrodynamic modifications in the flux directions in this pond. Minerals that were found to play a role in the pond hydrodynamics were calcite, gypsum, halite and pyrite. Evaporation was also found to be one of the main driving factors controlling the ionic composition in the surface water.

Primary author

Mrs Ana Fernández-Ayuso (Pablo de Olavide University)

Co-authors

Dr Claus Kohfahl (Spanish Geological Survey) Prof. Gudrun Massmann (Oldenburg University) Dr Janek Greskowiak (Oldenburg University) Prof. Miguel Rodríguez-Rodríguez (Pablo de Olavide University)

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