『Summary
Stable isotopes of hydrogen (δD) and oxygen (δ18O)
in groundwater, submarine springs and seawater collected in coastal
south-eastern Sicily were investigated. While the spatial distribution
of δ18O in groundwater showed that most of the heavy-isotope-depleted
samples (from -5.7‰ to -6.9‰) were located in the higher portion
of the Hyblean Mountains, more positive values (from -3‰ to -5.6‰)
were found in the marginal areas. The isotope composition of submarine
springs was characterized by significant variability (δ18O
between -5.6‰ and +1.0‰ and δD between -30‰ and +5.0‰) reflecting
seasonal variations and different seawater contributions. The
isotopic and chemical composition of coastal groundwater showed
the presence of a surficial aquifer, while the composition of
inland groundwater and beach springs characterizes a deeper limestone
aquifer. The amount of NO3 entering the sea
from land-based sources was estimated to be >60 kg/day, which
could be of potential environmental concern. Since the submarine
groundwater manifestations are fed by coastal contaminated groundwater
and re-circulated seawater, environmental implication on the freshwater
resources management in the region is of particular interest,
especially their protection against contaminants from land-based
sources represented by growing agricultural activities in the
region.
Keywords: Deuterium; Oxygen-18; Groundwater; Submarine groundwater
discharge; Coastal zone; Sicily』
Introduction
Geological and hydrological background
Methods
Results and discussion
Hydrogeochemistry
Isotope geochemistry
Groundwater-seawater boundary
Conclusions
Acknowledgements
References