The Valmalenco serpentinite (central Alps, northern Italy) is marketed worldwide as dimension and decorative stone. However, the same area was once subject to chrysotile asbestos mining, from the XIX century till 1975. Asbestos is a well-known carcinogen, and there is the possibility of releasing fibres during quarrying, subsequently exposing workers. From 2004 till 2011, extensive sampling and monitoring of quarry fronts, asbestos veins, commercial stones and airborne asbestos was carried out. Massive rock and vein samples were analyzed by a combined use of optical microscopy, X-ray powder diffraction (XRPD) and quantitative electron microscopy (SEM). Asbestos is concentrated almost exclusively in discrete horizons, that coincide with the main discontinuities of the rock mass. Commercial stones without fractures and veins are practically asbestos free, whereas there is a slight contamination (sometimes exceeding the 1,000 ppm threshold) close to hydrothermal salvages. Quarry floors were always quite contaminated by chrysotile “beards” detached from the surface of the blocks. The airborne asbestos concentrations (PCM and SEM) were distributed over a wide range, mostly below the occupational exposure limit of 0.1 fml-1. Concentrations at quarry property border or at the closest villages were always below the environmental exposure limit of 0.002 fml-1. The extreme thinness of chrysotile fibrils produced during quarrying activities, and the abundance of pseudo-fibrous antigorite cleavage fragments proved the SEM-EDS analytical procedure to be the most suitable. It is of crucial importance to avoid the interception of veins during quarrying and to remove all visible asbestos from the extracted blocks, before any further processing
Cavallo, A., Rimoldi, B. (2013). Chrysotile asbestos in serpentinite quarries: a case study in Valmalenco, Central Alps, Northern Italy. JOURNAL OF ENVIRONMENTAL MONITORING, 15(7), 1341-1350 [10.1039/c3em00193h].
Chrysotile asbestos in serpentinite quarries: a case study in Valmalenco, Central Alps, Northern Italy
CAVALLO, ALESSANDRO;
2013
Abstract
The Valmalenco serpentinite (central Alps, northern Italy) is marketed worldwide as dimension and decorative stone. However, the same area was once subject to chrysotile asbestos mining, from the XIX century till 1975. Asbestos is a well-known carcinogen, and there is the possibility of releasing fibres during quarrying, subsequently exposing workers. From 2004 till 2011, extensive sampling and monitoring of quarry fronts, asbestos veins, commercial stones and airborne asbestos was carried out. Massive rock and vein samples were analyzed by a combined use of optical microscopy, X-ray powder diffraction (XRPD) and quantitative electron microscopy (SEM). Asbestos is concentrated almost exclusively in discrete horizons, that coincide with the main discontinuities of the rock mass. Commercial stones without fractures and veins are practically asbestos free, whereas there is a slight contamination (sometimes exceeding the 1,000 ppm threshold) close to hydrothermal salvages. Quarry floors were always quite contaminated by chrysotile “beards” detached from the surface of the blocks. The airborne asbestos concentrations (PCM and SEM) were distributed over a wide range, mostly below the occupational exposure limit of 0.1 fml-1. Concentrations at quarry property border or at the closest villages were always below the environmental exposure limit of 0.002 fml-1. The extreme thinness of chrysotile fibrils produced during quarrying activities, and the abundance of pseudo-fibrous antigorite cleavage fragments proved the SEM-EDS analytical procedure to be the most suitable. It is of crucial importance to avoid the interception of veins during quarrying and to remove all visible asbestos from the extracted blocks, before any further processingFile | Dimensione | Formato | |
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Cavallo and Rimoldi - Valmalenco chrysotile asbestos - Env.Sci.Proc.Imp. 2013.pdf
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