Isotopic and hydrogeochemical evaluation of springs discharging from high-elevation karst aquifers in Lar National Park, northern Iran
Author(s)
Shamsi, Abdollah
Gholam, Hossein Karami
Azizollah, Taheri
Date issued
October 2018
In
Hydrogeology Journal
Vol
27
No
2019
From page
655
To page
667
Reviewed by peer
1
Subjects
Stable isotope Karst spring Hydrochemistry Iran
Abstract
Stable isotopes oxygen-18 (δ18O) and deuterium (δD) and the hydrochemistry of the main springs of well-developed karst
aquifers in Lar watershed in the Haraz basin, northern Iran, were investigated. Water samples were collected in the recession
period for analysis of major ions and the stable isotopes. Predominant hydrochemical types of main karst springs samples were
Ca2+ – Mg2+ – HCO−3 type. The hydrochemical composition of the karst springs is dominated by Ca2+, Mg2+, HCO−3 and SO2−
4
ions. The hydrochemical results indicate that dissolution of carbonate rocks (limestone and dolomite) governs the major ion
concentrations, with minor effects of silicate weathering, ion exchange and precipitation effects on concentrations of Na+, Cl−,
K+, and SO2−
4 . In the northern parts of the study area, hydrothermal fluid affects the chemistry of the draining springs. The
isotopic content ranges from −43.8 to −52.9‰ and from −7.09 to −8.97‰ for δD and δ18O, respectively. The karst spring
samples lie above the local meteoric water line, similar to the δ18O and δD signature of the snowpack samples, and have small
spatial and temporal variability. The similarity of the isotopic composition of the springs to the snowpack suggests that the
dominant recharge is by snowmelt water.
aquifers in Lar watershed in the Haraz basin, northern Iran, were investigated. Water samples were collected in the recession
period for analysis of major ions and the stable isotopes. Predominant hydrochemical types of main karst springs samples were
Ca2+ – Mg2+ – HCO−3 type. The hydrochemical composition of the karst springs is dominated by Ca2+, Mg2+, HCO−3 and SO2−
4
ions. The hydrochemical results indicate that dissolution of carbonate rocks (limestone and dolomite) governs the major ion
concentrations, with minor effects of silicate weathering, ion exchange and precipitation effects on concentrations of Na+, Cl−,
K+, and SO2−
4 . In the northern parts of the study area, hydrothermal fluid affects the chemistry of the draining springs. The
isotopic content ranges from −43.8 to −52.9‰ and from −7.09 to −8.97‰ for δD and δ18O, respectively. The karst spring
samples lie above the local meteoric water line, similar to the δ18O and δD signature of the snowpack samples, and have small
spatial and temporal variability. The similarity of the isotopic composition of the springs to the snowpack suggests that the
dominant recharge is by snowmelt water.
Publication type
journal article
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