The introduction of Directive 98/83/EC on the quality of
water intended for human consumption, has posed problems of noncompliance for
some of the most common contaminants in natural Italian groundwater, such as vanadium
(V). The Ministerial Decree (DM) of December 22, 2011 considering the
current scientific knowledge and the findings of studies carried out by ISS has
set the parameter value of 140 mg/L as the limit of the total presence of vanadium
in water intended for human consumption without adverse effects for human
health. Vanadium is a ubiquitous metal found naturally in all environmental
matrices: air, soil, plants, and water. Its concentration measured in these is
largely influenced by the geographical location: i.e. ambient air from urban
locations is characterized by greater atmospheric levels of vanadium than rural
sites and it is, furthermore, dependent on time of season. Groundwater from
volcanic areas is characterized by high concentrations of V, from 0.05 to 2.47
mg/L.
The main source of these items has identified in the interaction between
rainwater and rocks belonging to the hydrogeological system of the volcanoes.
Here, the water aquifers, interacting with the volcanic soil characterized by
high CO2 pressure in gaseous form, are particularly acidic and this facilitates
the leaching of elements and compounds from the volcanic rock.
Several studies have demonstrated the natural origin of
vanadium in the Mt Etna groundwater supplies, especially in the lower areas of
the south and southwest slopes. Here the major aquifer provides drinking water
to more than 750,000
people and irrigation water for extensive farmed areas, and the local
population could be therefore at risk of excessive V exposure. Since 1990,
monitoring data in the area of Mt. Etna revealed that concentration of vanadium
is rather variable: from values below the limit of quantification to values of
135 μg/L in Ciapparazzo source (south-west side).
The average concentrations
calculated pointed out the existence of significant differences between Mt.
Etna’ slopes, with higher values at south-south/west faces, with concentrations
respectively of 31.3 μg/L and 25.7 μg/L, and values below the method detection
limit in the northern side.
Comments
Post a Comment