The land surface is damaged by mining activities and waste rocks often become sources of pollution. Near Gromo village, on both sides of the Valseriana in the Central Orobic Alps (Bergamo, Italy), several proofs of historical mining activities are present. Since XIth century these mines, exploited specifically for Fe and Ag, historically played an important rule for the economic development of the valley. The ore deposits, made up mainly by sulphide, sulphosalts and carbonate were intensely exploited in the medieval epoch and abandoned in the early decades of XXth century. The ore mineralization, represented by a complex and polyphase association of sulfides and sulfosalts containing Cu, Fe, Zn, Pb, Co, Ni, Ag, Sb, As with dominant chalcopyrite and tetrahedrite, is hosted in quartz breccia bodies that crop out along contacts between South Alpine basement and Permo-Triassic cover rocks. Mining activities generated a large amount of waste rocks dumps located near some villages. Three dumps (Coren del Cucì, Pradel and Vedriol) were investigated in details: an amount of 75 earth samples were collected from 15 to 40 cm depth and the fraction < 2 cm were separated for subsequent pH and geochemical analyses. Representative quantities of aerial parts and roots of two plant species that grow over the dumps, Calluna vulgaris (15 samples) and Dryopteris filix-mas (20 samples), were collected in the same soil sampling places. Trace elements concentrations (Pb, Zn, Co, Ni, Ag, Cu, Cd and As) in both earth and plant samples were determined by ICP-AES. Bioaccumulation Factor (BF) and Traslocation Factor (TF) were calculated for plants data set. In earth materials all elements reach high level concentrations: if only averages are considered, Zn and Pb exceed 3500 and 3000 mg kg-1 respectively, As reaches 860 mg kg-1. The three sites show different element associations. Metals high concentration values have been founded also in soils far from dumps, upholding the presence of an anomalous area that must be carefully controlled and observed for its potential geochemical risk. Data set elaboration had led to establish that elements are in geochemical immobility's conditions and several accumulations are mainly related to morphological factors. Calluna vulgaris shows several BF values >1 displaying an evident tendency to accumulate metals, especially in roots. In aerial parts BF value for Cd reaches 2.90. Range of TF values uphold the behaviour of this species as a metal bio-accumulator, when present around mine sites (Wilson and Pyatt, 2007). In Dryopteris filix-mas metals concentrations are like to normal and exceed a bit the toxic levels only for As and Pb (Kabata Pendias, 2001). BF values are low and < 1 for all elements. Evaluation of trace-element concentrations shows that this two species are not hyperaccumulators; however they appear interesting for soil stabilization and could be use to re-establish a vegetative cover at sites where natural vegetation is scarce due to high metal concentrations, such as contaminated habitats. Especially Calluna vulgaris is able to grow on acid, ore-characterized and nutrients-poor substrates by employing a metal exclusion-strategy and it could be use to contaminated land phytostabilization.
Persistence and bioaccumulation of heavy metals around an ancient mine site at Gromo-Gandellino (Valseriana, Northern Italy) / L. De Capitani, G. Grieco, S. Porro. - In: ACTA MINERALOGICA-PETROGRAPHICA. - ISSN 0365-8066. - (2010). ((Intervento presentato al 20. convegno General Meeting of the International Mineralogical Association : Bonds and bridges tenutosi a Budapest nel 2010.
|Titolo:||Persistence and bioaccumulation of heavy metals around an ancient mine site at Gromo-Gandellino (Valseriana, Northern Italy)|
DE CAPITANI, LUISA (Primo)
GRIECO, GIOVANNI (Secondo)
PORRO, SILVIA (Ultimo)
|Settore Scientifico Disciplinare:||Settore GEO/09 - Georisorse Miner.Appl.Mineral.-Petrogr.per l'amb.e i Beni Cul|
Settore GEO/08 - Geochimica e Vulcanologia
|Data di pubblicazione:||2010|
|Appare nelle tipologie:||01 - Articolo su periodico|