Judit Mádl-Szőnyi 1 and József Tóth GSA Annual Meeting From Volcanoes to Vineyards: Living with Dynamic Landscapes T 25 Groundwater in Ecosystems October Portland, Oregon, USA Oregon Convention Center 1 Department of Physical and Applied Geology, Eötvös Loránd University 1/c. Pázmány P. sétány, Budapest, Hungary 2 Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, AB T6G 2E3 Canada

 Objectives  The Study Area  Database and Methods  Results Groundwater Flow Pattern Water and Soil-Salinity  Interpretation in a Schematic Pattern  Summary and Conclusion

Goals of the study: 1. What is the source of the salts? 2. What are the controls and mechanisms of their distribution pattern? Background: The Duna- Tisza Interfluve is plagued by soil and wetland salinization.

The Study Area 1 Physiography Physiography m asl 2-3 m m asl 2-3 m m asl 3-4 m Kolon Lake Kelemenszék Lake ( Mádl-Sz ő nyi and Tóth 2009, Fig. 2) ( Mádl-Sz ő nyi and Tóth 2009, Fig. 2 ) Locations of data, sections and pressure profiles

Generalized hydrostratigraphic section, Great Plain, Hungary (Tóth and Almási, 2001, Fig. 8, based on Juhász, 1991, Fig. 7)

 Major data types: water levels, pore pressures from water- and hydrocarbon wells, chemical data from water- and hydrocarbon wells, lithologic samples, petrophysical and geological bore-hole logs, seismic sections, ecological landscape data.  Methods: - hydrostratigraphic evaluation, analysis of groundwater flow-distribution; maps, sections and p(z) profiles were produced. - chemical evaluation; only Na +, Cl - and TDS content were considered. - ecological and soil evaluation; ecological site map.

Deep regional sections (Mádl-Sz ő nyi and Tóth, 2009, Fig. 4) ALGYŐ AQUITARD Deep regional sections (Mádl-Sz ő nyi and Tóth 2009, Fig. 4b) Deep regional sections (Mádl-Sz ő nyi and Tóth 2009, Fig. 4b )

Seismic section: Ki-3 (Mészáros, 2005, Fig. 6.6.) SUBHYDROSTATIC GRADIENT HYDROSTATICGRADIENT SUPERHYDROSTATICGRADIENT Pressure profile: Izsák (Mádl-Sz ő nyi and Tóth 2009, Fig. 8c) (Mádl-Sz ő nyi and Tóth 2009, Fig. 8c ) Izsák- Kolon Lake

SUBHYDROSTATIC GRADIENT HYDROSTATIC GRADIENT Detailed local section: hydrostratigraphy and hydraulics (Mádl-Sz ő nyi and Tóth 2009, Fig. 6)

Evaluation of groundwater salinity for hydrostratigraphic units (Mádl-Sz ő nyi and Tóth 2009, Table 1) (Mádl-Sz ő nyi and Tóth 2009, Table 1 )

Detailed local section: hydrostratigraphy and Cl -, TDS content of groundwater (Mádl-Sz ő nyi and Tóth 2009, Fig. 10) TDS: <500 mg/l Cl - : <30 mg/l Duna Valley TDS:>2000 mg/l, TDS: >2000 mg/l, Cl - :>500 mg/l Cl - : >500 mg/l

Shallow groundwater chemistry map (modified from Kuti and K ő rössy 1989, K ő rössy 1989, Mádl-Sz ő nyi and Tóth, 2009 Fig. 12) Ecological site map (Mádl-Sz ő nyi and Tóth, 2009, Fig. 13) Duna Valley

The Duna-Tisza Interfluve Hydrogeological Type Section (Mádl-Sz ő nyi and Tóth 2009, Fig. 14)

1. Sources of the salts:  NaCl type water, TDS: mgL -1 from the Pre-Neogene basement.  NaHCO 3 type water, TDS: mgL -1 in the Neogene sediments.  The two water mix, with basement origine Cl - beeng a natural tracer of deep water at shallower depths. Summary and Conclusion 1

2. Mechanism of salt distribution:  Gravitational flow-systems of meteoric fresh water are perched hydraulically upon the rising salt waters. The hydraulic interaction between the two regimes controls the transport routes to, and distribution of the salts at, the land surface. 3. Distribution pattern:  Salinity distribution at the surface is explained by the tectonically driven cross-formational rise of deep saline waters channeled in and mixed with fresh waters by near-surface sediments and gravity flow- systems.

 The authors are pleased to acknowledge the assistance and contributions received from the following agencies and individuals for data and logistical support: the Kiskunság National Park (A. Iványosi-Szabó); the Institutes for Soil Science and Agricultural Chemistry, and Ecology and Botany (Zs. Bakacsi, Zs. Molnár) of the Hungarian Academy of Sciences. Gy. Pogácsás, Associate Professor, Eötvös Loránd Science University (ELTE).  L. Máté; K. Nyúl; Sz. Simon; R. Varga, F. Zsemle, B. Czauner former students of ELTE, kindly contributed results from their graduate theses.  The research was supported by the Hungarian OTKA grant No. T to J. Sz ő nyi-Mádl, and the Canadian Natural Sciences and Engineering Research Council’s „Discovery grant” No. A-8504 to J. Tóth.

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