Author(s):
Silva, Eduardo Ferreira da 
; Ávila, Paula Freire ; Salgueiro, Ana Rita ; Candeias, Carla ; Pereira, Henrioque Garcia
Date: 2013
Persistent ID: http://hdl.handle.net/10400.9/2164
Origin: Repositório do LNEG
Subject(s): Contaminação do ambiente; Contaminação de solos; Actividade mineira; Minas da Panasqueira (Portugal)
Description
Through the years, mining and beneficiation processes produces large amounts of As-rich mine wastes laid up in huge tailings and open-air impoundments
(Barroca Grande and Rio tailings) that are the main source of pollution in the surrounding area once they are exposed to the weathering conditions leading to
the formation of AMD and consequently to the contamination of the surrounding environments, in particularly soils. In order to investigate the environmental
contamination impact on S. Francisco de Assis (village located between the two major impoundments and tailings) agricultural soils, a geochemical survey was
undertaken to assess toxic metals associations, related levels and their spatial distribution, and to identify the possible contamination sources. According to
the calculated contamination factor, As and Zn have a very high contamination factor giving rise to 65.4 % of samples with a moderate to high pollution
degree; 34.6 % have been classified as nil to very low pollution degree. The contamination factor spatial distribution put in evidence the fact that As, Cd, Cu,
Pb, and Zn soils contents, downstream Barroca Grande tailing, are increased when compared with the local Bk soils. The mechanical dispersion, due to
erosion, is the main contamination source. The chemical extraction demonstrates that the trace metals distribution and accumulation in S. Francisco de Assis
soils is related to sulfides, but also to amorphous or poorly crystalline iron oxide phases. The partitioning study allowed understanding the local chemical
elements mobility and precipitation processes, giving rise to the contamination dispersion model of the study area. The wind and hydrological factors are
responsible for the chemical elements transport mechanisms, the water being the main transporter medium and soils as one of the possible retention media.
