Hydrogeochemistry of Roccamonfina volcano (Southern Italy)

Abstract

This is the first hydro-geochemical investigation carried out on the Roccamonfina Volcanic Complex groundwaters. The chemistry of Roccamonfina waters is defined by water-rock and water-rock-gas interactions. In fact, interactions between rocks of the first eruptive high-K formations and circulating groundwaters are recognized by high K concentrations. On the other hand, inverse concentration of calcium versus alkali metals is related to two different rock interactions occurring in different areas of the volcano: (a) within the caldera where groundwaters flow within latite and pyroclastic formations releasing calcium, and (b) similarly at the base of the volcano where groundwaters flowing from surrounding carbonates got strongly enriched in Ca. These geochemical processes are also associated with K (SE of caldera) and Mg/Ca (in sites located at the NE base of the volcano) decrease. Completely different dynamics occurs at Riardo groundwaters (SE). Here waters are the result of a mix between the Roccamonfina deep aquifer and the carbonate aquifer of the Riardo plain. Rich-CO 2 emissions make these waters strongly mineralized. Minor elements show a similar geochemical behavior of major ions and are crucial defining interactions processes. The evolution of Roccamonfina groundwaters is also evident along the simultaneous enrichment of Ba, Sr, and Ca. Ba increase is the result of deep local carbonate alteration enhanced by CO 2 emissions and, the lower Sr/Ca ratio, from 10 to 2 (ppb/ppm), is also due to the same process. In the light of our results the Roccamonfina aquifer can be schematically divided into two main reservoirs: (a) a superficial aquifer which basically follows the volcanic structure morphology and tectonics and (b) a deeper reservoir, originating within the oldest Roccamonfina volcano ultra potassic lavas and then flowing into the carbonate aquifers of the neighboring plain. Eventually, the chemistry of the Roccamonfina aquifer does not show any specific and visible pollution, contrary to what happens in the volcano surrounding plains. In fact, only 14% of the samples we collected (206) show a NO 3 content[30 mg/l. These sites are all located at the base of the volcano, near the plain.

Hydrogeochemical Characteristics and Assessment of Drinking Water Quality in the Urban Area of Zamora, Mexico

“…greater subsurface flow path and deep circulation [41]. In this study area, a range from 2.90 to 4.26 was obtained, indicating the presence of cold water of short and rapid path through the aquifer.…”

“…Values greater than 1.0 of HCO 3 − /Cl − ratio are frequently observed in cold groundwater, with a short flow path and rapid circulation. Values under 1.0 indicate the presence of thermal water, with greater subsurface flow path and deep circulation [41]. In this study area, a range from 2.90 to 4.26 was obtained, indicating the presence of cold water of short and rapid path through the aquifer.…”

Geolithological and anthropogenic controls on the hydrochemistry of the Volturno river (Southern Italy)

“…Of these samples, 72 were collected from springs, 88 were collected along the Volturno river using an irregular sampling scheme to capture tributaries' contribution and/ or lithological changes, and 8 samples each were collected from upland lakes and rainfall events spanning from 2008 to 2014. An additional 16 spring and river samples from the Roccamonfina volcano end-member were previously reported in Cuoco et al (2010).…”

Simplified two-dimensional modelling to constrain the deep groundwater contribution in a complex mineral water mixing area, Riardo Plain, southern Italy

“…Points monitoring the carbonate aquifer are mainly clustered in the Ferrarelle S.p.A. mineral water bottling plant near Riardo Town, where the basement upraises and the fault systems allow local mixing between the carbonate and volcanic aquifers (Cuoco et al 2010). As a result, the potentiometric levels of the two aquifers near the mixing area are very similar in absolute values and trends, related to the local seasonal thermo-pluviometric conditions.…”