Kouli_etal_2008_Groundwater modelling_BOOK.pdf - Pantelis ...

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Franco Cucchi, Giuliana Franceschini and Luca Zini
mg/l (mean of 62.5 mg/l) in shallow confined groundwater and from 30.9 mg/l to 67.6 mg/l
(mean of 49.5 mg/l) in the deep confined aquifers. In contrast to the elements discussed
above, the distribution of SO 4 is very different. Sulphate concentration decreases with the
distance to the Tagliamento River that has 130 mg/l of sulphate when its waters enter in the
Friuli Plain due to gypsum formations outcropping in the Carnic Alps.
Figure 8. SO 4 , Piper diagram of the unconfined and confined groundwater samples.
Environmental Isotopes
The δ 18 O of groundwater (Figure 9) fall in the range -6.25‰ to -8.90‰ with a mean value of
-7.59‰ in the unconfined aquifer, from -6.83‰ to -9.14‰ with a mean value of -8.05‰ in
the shallow confined aquifer and from -7.01‰ to -10.35‰ with a mean value of -8.74‰ in
the deeper confined aquifer (Tables 1 and 3). The most depleted groundwater samples are
located in the Carnic Alps (Table 1). The rainfall samples show a great variation in isotopic
composition (calculated over a two year monitoring period), the δ 18 O weighted mean values
range from -7.09‰ to -10.39‰ with an average value of -9.04‰ in the mountainous areas
and from -7.45‰ to -7.78‰ for δ 18 O in the Friuli Venezia Giulia Plain with a mean of -
7.62‰ (Table 3).