In the Piedmont plain there are some sectors in which the separation among the aquifers is not well marked from the lithostratigraphic point of view, because of large thickness of coarse sediments (Bortolami et alii, 2002; Bove et alii, 2005). A lithostratigraphic study integrated with chemical and isotopic methodologies has been carried out in the sector of plain among the Turin and Cuneo districts (South-Western Piedmont), in order to define a separation between superficial and deep groundwater circulation. From the lithostratigraphic analysis of the Piedmont plain a mean value of 50 meters for the superficial aquifer bottom has been evaluated. In the study area water wells (generally for irrigated use) whose depth is less than 50 meters have been selected. Likewise, drinking water wells, extracting water only under such threshold have been identified. During the summer 2005, 20 samples of shallow groundwater and 4 samples of deep groundwater have been analyzed. From the main chemical parameters (conductibility, calcium, magnesium, sodium, potassium, chlorides, bicarbonates, sulfates and nitrates) the conductibility of the superficial groundwater is about twice the deep groundwater, especially because of bicarbonate concentration. Also sulfates, chlorides and nitrates of the superficial groundwater have values 2 - 4 times higher than in the deep one. The concentrations of minor chemical elements (Aluminum, Barium, Boron, Beryllium, Cadmium, Chromium, Iron, Fluorides, Lithium, Manganese, Mercury, Nickel, Lead, Copper, Strontium, Vanadium and Zinc) were lesser than instrumental limit or showing any difference between superficial and deep groundwater. The stable isotopes analysis of superficial groundwater has shown a content of heavy isotopes higher than the deep waters. The difference of about 1 δ180‰ and 10 δ2H‰ depends on the temperature of waters condensation and rainfall. The isotopic difference is probably caused by a different groundwater recharge area, located at higher altitude for the deeper groundwater circuit, according to previous studies (Bortolami et al, 1996). From the study, the isotopic analysis seem to give an important contribution to the characterisation and differentiation of aquifers, justifying future researches extended to the other component of the hydrological balance with a larger number of samples.
Characterisation and differentiation of groundwater circulation
BOVE, ANNALISA;ALBANESE, Adriana;MASCIOCCO, LUCIANO
2007-01-01
Abstract
In the Piedmont plain there are some sectors in which the separation among the aquifers is not well marked from the lithostratigraphic point of view, because of large thickness of coarse sediments (Bortolami et alii, 2002; Bove et alii, 2005). A lithostratigraphic study integrated with chemical and isotopic methodologies has been carried out in the sector of plain among the Turin and Cuneo districts (South-Western Piedmont), in order to define a separation between superficial and deep groundwater circulation. From the lithostratigraphic analysis of the Piedmont plain a mean value of 50 meters for the superficial aquifer bottom has been evaluated. In the study area water wells (generally for irrigated use) whose depth is less than 50 meters have been selected. Likewise, drinking water wells, extracting water only under such threshold have been identified. During the summer 2005, 20 samples of shallow groundwater and 4 samples of deep groundwater have been analyzed. From the main chemical parameters (conductibility, calcium, magnesium, sodium, potassium, chlorides, bicarbonates, sulfates and nitrates) the conductibility of the superficial groundwater is about twice the deep groundwater, especially because of bicarbonate concentration. Also sulfates, chlorides and nitrates of the superficial groundwater have values 2 - 4 times higher than in the deep one. The concentrations of minor chemical elements (Aluminum, Barium, Boron, Beryllium, Cadmium, Chromium, Iron, Fluorides, Lithium, Manganese, Mercury, Nickel, Lead, Copper, Strontium, Vanadium and Zinc) were lesser than instrumental limit or showing any difference between superficial and deep groundwater. The stable isotopes analysis of superficial groundwater has shown a content of heavy isotopes higher than the deep waters. The difference of about 1 δ180‰ and 10 δ2H‰ depends on the temperature of waters condensation and rainfall. The isotopic difference is probably caused by a different groundwater recharge area, located at higher altitude for the deeper groundwater circuit, according to previous studies (Bortolami et al, 1996). From the study, the isotopic analysis seem to give an important contribution to the characterisation and differentiation of aquifers, justifying future researches extended to the other component of the hydrological balance with a larger number of samples.
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