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Abstract: In the course of our work the chemical composition of thermal water utilized in the Southern Great Hungarian Plain and disposed to the environment was investigated from the viewpoint of soil and groundwater degradation. Temporary disposal of these sewage thermal waters are executed in cooling pools and released across ground channels into natural surface waters afterwards. During this process the waste water infiltrates into the soil, altering soil and groundwater parameters.
It can be claimed that thermal water is characterized by pollutants of Hg, As, Cd and Pb, which can get to the groundwater across the soil. In most cases, ammonium concentration and Na % have also exceeded the limit value. From the thermal water with high Na%, Na⁺ gets to the groundwater and raises its Na⁺-rate. Ammonium content of thermal water transforms into nitrate on the surface during utilization and then appears in the groundwater, as well. In the soils close to the channel, alkalinization and salt accumulation is characteristic.
We focused on a selected sample area, Cserkeszőlő in order to present in detail manifestation of the waste thermal water effects in particular regard to the salinzation-sodification-alkalinization processes. The characteristic changes are represented on Chernozem and Phaeozem soil types of this sample area. It was concluded that the high total salt content of the seeping used thermal water facilitated salt accumulation in other horizons of both soil types. Alkalinization of above-mentioned soil degradation processes also could be detected. ESP values of soils have not attained the hazardous value, so sodification has not appeared yet.

Keyword: thermal water, soil degradation, human-induced salt accumulation