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Fernando Ruiz Bermudo Instituto Geológico y Minero de España Unidad de Sevilla

Changes of the isotopic signatures and hydrochemistry in the unsaturated zone detected by a precision lysimeter installed in a dune belt ( Doñana National Park, southwest Spain ). Fernando Ruiz Bermudo, Claus Kohfahl , Iñaki Vadillo Pérez.

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Fernando Ruiz Bermudo Instituto Geológico y Minero de España Unidad de Sevilla

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  1. Changes of the isotopic signatures and hydrochemistry in the unsaturated zone detected by a precision lysimeter installed in a dune belt (Doñana National Park, southwest Spain) • Fernando Ruiz Bermudo,Claus Kohfahl, Iñaki Vadillo Pérez • Geological Resources, Instituto Geológico y Minero de España, Spain, • Grupo de Hidrogeología, Universidad de Málaga, Spain. • 46th IAH Congress • Malaga, Spain • Sep 27, 2019 • Fernando Ruiz Bermudo • Instituto Geológico y Minero de España Unidad de Sevilla

  2. INTRODUCTION Points to consider • 1. Dune systems are important hydrological systems for groundwater recharge especially in semiarid areas. • 2. Infiltrated water may be subjected to evaporation due to vapor flow and to water-rock interaction due to precipitation/dissolution changing the hydrochemicalcomposition • 3. In areas with high atmospheric moisture content, vapor adsorption may also contribute to groundwater recharge. • 4. Precision lysimetersare the most preside tools to measure the hydrological components of the soil water. • => Objective: Hydrochemical and stable isotope data of a precision lysimeter experiment are used to investigate vapor flow and hydrochemicalprocesses affecting groundwater recharge in dune belt systems.

  3. MATERIAL AND METHODS • METEO LYSIMETER

  4. MATERIAL AND METHODS • MeteoLysimeter Site Equipment • Weighing Lysimeter • (METER, Munich, Germany) • 1 m2 area • 1.5 m height • 10 g resolution • Six CS650 soil moisture sensors (Campbell Scientific, Logan UT) • 2.Meteorological Stations • (Vantage PRO2 Davis, California, USA; UMS AG, Munich, Germany) Weighing Rain Gauge Meteo-station DAVIS • 1 Weighing Rain Gauge (OTT pluvio1) Lysimeter Meteo-station UMS • Rain water collector (5 liters) Rain water collector

  5. INTRODUCTION • Doñana National Park (Wetland) • Southwest Spain: Doñana National Park => Almonte-Marismas aquifer • Geography • surrounded by 46 villages and towns =>1.5 Mio people • Agriculture and Tourism • Geology • dunes • beaches • marshes • Climate • Sub-humid Mediterranean with Atlantic influence • Average rainfall: 500-600 mm • Average Temperature: 17-18ºC Ortophoto from Junta de Andalucia webpage: http://www.ign.es/wms-inspire/pnoa-ma

  6. MATERIAL AND METHODS • Where do we put the lysimeter? • Site with high recharge => e.g. Dunes • Site with previous information • Site of environmental and economic concern • Dune belt of coastal aquifer in the Doñana • National Park (SW Spain)

  7. MATERIAL AND METHODS • Sample collection and analysis • Rain samples: 37 samples (February 2016 to April 2019) • Drainage samples: 49 samples (February 2016 - June 2019) • Rain samples were collected connecting with a tube a funnel to a high-density polyethylene bottle (5L) containing paraffin oil to prevent evaporation. • Drainage samples were collected directly from the lysimeter drainage vessel. • Collection intervals: 2 weeks (generally) • Conservation in 100 ml polyethylene bottles at 4ºC. • Stable isotopes of water (δ18O and δ2H) were analyzed with a PICARRO™ laser spectroscope (mod. L1102-i) at the laboratory of the Center of Hydrogeology of the University of Malaga. • Hydrochemical composition and parameters were analyzed at the laboratory of Instituto Geológico y Minero de España • Initialwatercontent of lysimeter isapproximately 110 l

  8. ResultsHydrochemistry Calcium-Magnesium- Bicarbonate (Ca-Mg-HCO3) to Sodium-Chloride (NaCl) types Sodium-Chloride (NaCl) and Calcium Sulfate (CaSO4) types • 8 samples of drainagevessellysimeter(march-2017 to septebmer-2017) • 10 samples of rain (march-2017 to june-2018) • Soil water evaporation causes concentration of salts and other minerals such as gypsum that are dissolves with rainfall events. • Gypsumdissolutionoverprintsrainwatercomposition

  9. Results isotopes δ2H=6.71*(δ18O)+6.68 R2=0.9431 • The LMWL is very similar to Gibraltar and Faro LMWL (GNIP) • (~ 150 km) • Isotopesignals of drainedwaterplotbelow LMWL withattenuatedrange • Isotopic signals of drainage water is controlled by (i) mix of previous rainfall events and (ii) vapor flow δ2H=6.05*(δ18O)-0.2 R2=0.9016 (Craig, 1961)

  10. Results isotopes • Temporal variations of δ18O and δ2H in Rainfall and Drainage samples. • Warm periods samples show higher content in 18Oand 2H than cold ones. (May 1st - October 31th)

  11. Results isotopes • δ18O values ranges from -9 ‰ to 0 ‰ in rain samples. • Rain samples that correspond to lower rainfall are more enriched in 18O than those that correspond to higher rainfall typical in cold season • δ18O values ranges from -6 ‰ to -2 ‰ in drainage samples.

  12. Results isotopes Sequences of isotopes signals Sequence Date Precipitation (mm) Drainage (mm) 0 27-07-2018 0 2.50 • Vessel 0: end of dry period in summer Two months since the last major rains

  13. Results isotopes Sequence Date Precipitation (mm) Drainage (mm) 27.05 • Vessel 1 plots on evaporation line of vessel 0 which reflects lysimeter composition=> no mixing with rain 1 visible. 7 days since the last major rains Evaporation 12.26 mm

  14. Results isotopes Sequence Date Precipitation (mm) Drainage (mm) 27.05 • Vessel 2 is hardly influenced by rain 2. Major rains in the last 7 days Evaporation 17.41 mm

  15. Results isotopes Sequence Date Precipitation (mm) Drainage (mm) 27.05 • Vessel 3 shows mix of vessel 2(lysimeter) water, and rain water 2 or/and 3 + evaporation (it does not plot on a mixing line!!) Major rains in the last 2 days Evaporation 20.04 mm

  16. Results isotopes Sequence Date Precipitation (mm) Drainage (mm) 27.05 • Vessel 4 plots on a mixing line between vessel 3 and rain 3. Rain event 4 not visible in vessel 4 • No additionalevaporation visible 4 days since the last major rains Evaporation 7.19 mm

  17. Results isotopes Sequence Date Precipitation (mm) Drainage (mm) 27.05 • Vessel 5 plots on mixing line between vessel 4 and rain 4. Rain 5 not visible in vessel 5 • No additionalevaporation 5 days since the last major rains Evaporation 8.45 mm

  18. Results isotopes Annual weighted average of isotope composition (September 1st to August 31th) Why?

  19. Results isotopes Annual weighted average of isotope composition (September 1st to August 31th) Hypothesis 1 ? Hypothetical weighted average that produce recharge in lysimeter?

  20. Results isotopes Annual weighted average of isotope composition (September 1st to August 31th) Hypothesis 2 ? Hypothesis 2: a second vapor source

  21. Results • Evidence of vapor flow lysimeter measurements • (contribution 277, Kohfahl et. al.) Vapor adsorption(0.3 – 0.4 mm/d) Evaporation (0.4 - 0.6 mm/d) Kohfahl C. et al (2018). Determininggroundwaterrecharge and vapor flow in dunesedimentsusing a weighableprecisionmeteolysimeter. Science of the Total Environment.

  22. Conclusions • Gypsumdissolutionoverprintsrainwatercomposition • Isotopesignals of drainedwaterplotbelow LMWL withattenuatedrange • Individual isotopesignals of drainedwaterpoint to mixing of lysimeter waterwithsecondlast rain eventand additionalevaporation in warmseason=>minimalresidence time detectedisbetween 9-12 days • A possiblecontribution of vapor adsorption to rechargemayexistbutmay be hiddendue to superpositionbyevaporation.

  23. Outlook • Weighing of individual events of rain and vessel • Isotopesampling of vapor (atmosphere, soil) and soilwater • New infrastructurewill be installed in 2019/2020 (EQC2018-004130-P*) • Add 3 more lysimeters • Improveresolution of sampling (eventsampler) • Improvelowerboundary control • Improveinformationavailable in thelysimeter *Subprograma Estatal de Infraestructuras Científicas y Técnicas y de Equipamiento, en el marco del Programa Estatal de Fomento de la Investigación Científica y Técnica de Excelencia del Plan Estatal de Investigación Científica y Técnica y de Innovación, así como en el artículo 18.2 de la resolución de la convocatoria, el 15/10/2018

  24. ACKNOWLEDGMENTS • Funding: • European Research Funds (SE Scientific Infrastructures and Techniques and Equipment 2013, IGME13-1E-2113). • Spanish National Plan for Scientific and Technical Research and Innovation: CLIGRO Project (MICINN, CGL2016-77473-C3-1-R). • National System of Youth Guarantee (MINECO activity with reference PEJ-2014-85121) co-financed under the Youth Employment Operational Program, with financial resources from the Youth Employment Initiative (YEI) and the European Social Fund (ESF). • Technical support: • Biological Station of Doñana, the Biological Reserve of Doñana and the administration of the Doñana National Park. • IñakiVadillo from University of Malaga for isotope analysis. • UMS AG, Munich (Germany) • A. Peters for providing AWAT filter. • THANK YOU!

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