Italian law concerning the remediation of polluted areas forces the responsible party of the contamination to provide the complete characterization of the site, the project and the operative tasks for cleaning up soils and waters. In this context, determining the origin of pollution is mandatory for a correct approach to the whole remediation process. Our research group has been studying for two years the problem of Arsenic pollution in the area of an industrial plant for the production of sulphuric acid (SA) from pyrite roasting. The plant is located in a former wetland, in Scarlino, southwest of Tuscany. Horizontal distribution shows an almost regular decrease in the As concentration going, far from the plant, but with the presence of "hot spots" ([As]> 600 ppm) at large distance. Other irregularities in the vertical distribution of As concentration in the clay-rich soil, were found. Several evidences identified the SA plant wastes as largely responsible for the high Arsenic levels of the soil, but other theories were suggested. One of the prominent explanations concerned the natural Arsenic anomaly of the area; this was proposed to explain the wide distribution of the element and its irregular trend. This hypothesis was supported by the fact that the site under study is relatively close (about 15 km south-west) to the "Colline Metallifere" mine field, from which pyrite and blended sulfides were extracted. In fact, As enriched sediments could be transported from the river and stream beds which originate in that area. In order to verify the basis of these theories and the mechanism of As diffusion in the environment, we started an extensive sampling of the stream sediments of several rivers which originate in the mining field area. Comparing all the data for Arsenic and other elements we were able to demonstrate that: i) the natural Arsenic levels were significantly lower than the values recorded in the site under study; ii) other wetlands with similar geo-mineralogical origin as the former Scarlino wetland did not present Arsenic and other metal anomalies; iii) all the high Arsenic values found in the stream sediments of the stream beds studied and in the soil were correlated with the presence of ancient mining sites or iron smelter. The results obtained are in favour of an anthropogenic source of the high Arsenic level in the site under study.

Influence of ancient mining settlements on Arsenic pollution in the southwest of Tuscany

ROSSI, FEDERICO;
2004

Abstract

Italian law concerning the remediation of polluted areas forces the responsible party of the contamination to provide the complete characterization of the site, the project and the operative tasks for cleaning up soils and waters. In this context, determining the origin of pollution is mandatory for a correct approach to the whole remediation process. Our research group has been studying for two years the problem of Arsenic pollution in the area of an industrial plant for the production of sulphuric acid (SA) from pyrite roasting. The plant is located in a former wetland, in Scarlino, southwest of Tuscany. Horizontal distribution shows an almost regular decrease in the As concentration going, far from the plant, but with the presence of "hot spots" ([As]> 600 ppm) at large distance. Other irregularities in the vertical distribution of As concentration in the clay-rich soil, were found. Several evidences identified the SA plant wastes as largely responsible for the high Arsenic levels of the soil, but other theories were suggested. One of the prominent explanations concerned the natural Arsenic anomaly of the area; this was proposed to explain the wide distribution of the element and its irregular trend. This hypothesis was supported by the fact that the site under study is relatively close (about 15 km south-west) to the "Colline Metallifere" mine field, from which pyrite and blended sulfides were extracted. In fact, As enriched sediments could be transported from the river and stream beds which originate in that area. In order to verify the basis of these theories and the mechanism of As diffusion in the environment, we started an extensive sampling of the stream sediments of several rivers which originate in the mining field area. Comparing all the data for Arsenic and other elements we were able to demonstrate that: i) the natural Arsenic levels were significantly lower than the values recorded in the site under study; ii) other wetlands with similar geo-mineralogical origin as the former Scarlino wetland did not present Arsenic and other metal anomalies; iii) all the high Arsenic values found in the stream sediments of the stream beds studied and in the soil were correlated with the presence of ancient mining sites or iron smelter. The results obtained are in favour of an anthropogenic source of the high Arsenic level in the site under study.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11386/3985654
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