Fórizs I., Tóth T. ÉS Kuti L. 2006. Isotope hydrogeochemical investigation of salinization on the Nyírő-lapos,
Hortobágy, Hungary. Magyarország környezetgeokémiai állapota. MTA Földrajztudományi Osztály.
Környezetgeokémiai Albizottság. Budapest.

Abstract

A cca. 600mx800m pilot plot in the most characteristic sodic landscape of Hortobágy (Nyírő-lapos) has been studied
by isotope hydrogeochemical methods. The Hortobágy is a discharge area of a regional flow system, where the
upwelling groundwater was infiltrated during the latest glaciation (Ice Age) according to the stable isotopic
composition of the deeper aquifers (d18O = -11.8‰ to -11.3‰, ?D = -91‰ to -86‰). On the pilot plot monitoring wells
were installed to study the groundwater in three depths: 3.5m, 6m, and 10m. The stable hydrogen and oxygen isotope
compositions of the water samples indicate that the ascending old groundwater (?18O<-11‰) mixes with the descending
modern water (18O = -9.3±0.3‰). The groundwater moves not only vertically, but horizontally as well, and the
direction of movement may change or even return in the different seasons of the year horizontally and vertically as
well. The flow system of this small pilot plot is extremely heterogeneous and varies in time
and space. At some places water, which suffered evaporation nearby the surface, could get down even to the 10
meters depth providing example for the complex spatial-temporal characteristics of subsurface water movement.