In 2010 a significant deterioration of flowers, plants and vegetables watered with domestic wells was observed north of Arezzo (Tuscany, Italy). These phenomena were ascribed to the presence of high concentrations of boron (above the threshold limit for the European, 98/83/CE, and Italian, Dlgs. 31/2001, directives, i.e. 1 mg/L) in the shallow aquifers. In May-June 2012, a geochemical and isotopic survey of surface, ground and waste waters, drill samples and anthropogenic materials produced by local industries was carried out to understand the origin and the possible source(s) of boron contamination. In the area, dominated by sedimentary rocks, three aquifers were recognized: deep (≈60 m deep), intermediate (≈30 m) and shallow (<10 m). Four surface waters were collected from the Arno River and a small creek nearby, along with 50 wells (from the three aquifers) and piezometers (<10 m depth). Sediment samples were collected from seven 10 m deep cores drilled in the industrial area, where small - to medium-factories, which use or have used boron in their industrial cycles, are present. Waters mainly have a Ca(Mg)-HCO3 composition, although Na-HCO3 (mainly related to the deep aquifer) and Na-Cl geochemical facies were also recognized. pH and Total Dissolved Solids values are between 6.89 and 8.82 and 300 and 3,000 mg/L, respectively. Slags, muds, raw products, e.g. borax and sodium boron-hydride, were also collected to test whether their boron concentrations and isotopic (δ11B) signature were able to explain the sometime strikingly high content of boron (up to 120 mg/L) detected in the groundwaters. According to these data, the contamination is mainly restricted to the shallow aquifer, which is hosted in the Arno alluvial deposits. No boron anomalies were found in the deep aquifer. Some analogies between the chemical composition of a piezometer, having the highest salinity and B concentrations, and that of the leaching tests performed in the industrial slags and muds were recognized. This may imply that industrial materials interacting with meteoric water represent a possible contamination source of the underground waters. However, B-isotopes for some selected water samples and industrial materials produced no univocal information, likely because of isotopic fractionation processes able to alter the original isotopic signature of the anthropogenic material before the leaching waters enter the hydrological circuits. To better understand the evolution and the possible source(s) of boron contamination, a geochemical monitoring on a monthly basis is presently on.

High Boron concentrations in some groundwaters from Arezzo (Tuscany, Italy) / Stefania Venturi; Orlando Vaselli; Luca Rossato; Barbara Nisi; Maddalena Pennisi; Jacopo Cabassi; Franco Tassi. - STAMPA. - (2013), pp. 207-207. (Intervento presentato al convegno Geoitalia 2013 IX Forum Italiano di Scienze della Terra tenutosi a Pisa nel 16-18 settembre 2013).

High Boron concentrations in some groundwaters from Arezzo (Tuscany, Italy)

VENTURI, STEFANIA;VASELLI, ORLANDO;CABASSI, JACOPO;TASSI, FRANCO
2013

Abstract

In 2010 a significant deterioration of flowers, plants and vegetables watered with domestic wells was observed north of Arezzo (Tuscany, Italy). These phenomena were ascribed to the presence of high concentrations of boron (above the threshold limit for the European, 98/83/CE, and Italian, Dlgs. 31/2001, directives, i.e. 1 mg/L) in the shallow aquifers. In May-June 2012, a geochemical and isotopic survey of surface, ground and waste waters, drill samples and anthropogenic materials produced by local industries was carried out to understand the origin and the possible source(s) of boron contamination. In the area, dominated by sedimentary rocks, three aquifers were recognized: deep (≈60 m deep), intermediate (≈30 m) and shallow (<10 m). Four surface waters were collected from the Arno River and a small creek nearby, along with 50 wells (from the three aquifers) and piezometers (<10 m depth). Sediment samples were collected from seven 10 m deep cores drilled in the industrial area, where small - to medium-factories, which use or have used boron in their industrial cycles, are present. Waters mainly have a Ca(Mg)-HCO3 composition, although Na-HCO3 (mainly related to the deep aquifer) and Na-Cl geochemical facies were also recognized. pH and Total Dissolved Solids values are between 6.89 and 8.82 and 300 and 3,000 mg/L, respectively. Slags, muds, raw products, e.g. borax and sodium boron-hydride, were also collected to test whether their boron concentrations and isotopic (δ11B) signature were able to explain the sometime strikingly high content of boron (up to 120 mg/L) detected in the groundwaters. According to these data, the contamination is mainly restricted to the shallow aquifer, which is hosted in the Arno alluvial deposits. No boron anomalies were found in the deep aquifer. Some analogies between the chemical composition of a piezometer, having the highest salinity and B concentrations, and that of the leaching tests performed in the industrial slags and muds were recognized. This may imply that industrial materials interacting with meteoric water represent a possible contamination source of the underground waters. However, B-isotopes for some selected water samples and industrial materials produced no univocal information, likely because of isotopic fractionation processes able to alter the original isotopic signature of the anthropogenic material before the leaching waters enter the hydrological circuits. To better understand the evolution and the possible source(s) of boron contamination, a geochemical monitoring on a monthly basis is presently on.
2013
Epitome geoitalia 2013
Geoitalia 2013 IX Forum Italiano di Scienze della Terra
Pisa
Stefania Venturi; Orlando Vaselli; Luca Rossato; Barbara Nisi; Maddalena Pennisi; Jacopo Cabassi; Franco Tassi
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Utilizza questo identificatore per citare o creare un link a questa risorsa: https://hdl.handle.net/2158/950963
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