Bioaccessibility of metals in soils surrounding two dismissed mining sites in Northern Italy

Abstract

Mining activities are one of the main contributors to metals contamination of soils, most often due to the inappropriate management of the mining residues. In Italy, hundreds of small mining sites are scattered around the mountainous areas, near small villages with fragile environments. Here, wastes and residues may have polluted the surrounding soils and become a threat to living organisms. We investigated two dismissed sites in Northern Italy with extractive wastes in unmanaged areas close to villages using bioaccessibility and size fractionation methods, focussing on particles that can potentially be eroded and/or ingested (< 10 µm and < 200 µm). In the Campello Monti site, Co, Cu and Ni showed high values in soils near the landfills, with the highest concentrations in the < 10 µm particles around the landfills and along the valley bottom. Lead and Ni were the most bioaccessible metals. In the Plassa site, Cd and Zn were the most important contaminants, with an average content of 118 and 34,000 mg/kg. They originated from mining wastes scattered through the slope and had a particularly high bioaccessible fractions, close to the 100% for Zn and above 80% for Cd in the fine particles. The study of the fine, more reactive and mobile particles offered a close insight into the lability of contaminants, as in both sites, a dispersion of metal contaminants through very fine particles in surrounding and downhill areas was observed, resulting in an increased risk to all living organism and for the environment.

Potential Release of Zinc and Cadmium From Mine-Affected Soils Under Flooding, a Mesocosm Study

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Fig. 1 Geographic location of the sampling points (background image: Google, Digital Globe, 2018), adapted from Padoan et al ( 2020 )

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“…The waste rock dumps have not been remediated after the conclusion of the mining activities. The mining debris were then scattered across the surrounding areas during and after the very long period of exploitation and now most of the slope appears to be heavily contaminated, particularly around the former dumping areas, with Cd concentrations in the topsoil between 13 and 493 mg/kg and Zn values in the range 9–132 g/kg (Padoan et al 2020 ). After the dismissal of the mining operation, the entire area was open to tourism and agriculture and pastures.…”

“…Following previous characterization studies (Padoan et al 2020 ; Mehta et al 2020 ), we selected and sampled two soil samples representative of the slope. The soils also were selected in view of their similarity in organic carbon and Fe content and their difference in pH and presence of carbonates.…”

Health and environmental impact assessment of landfill mining activities: A case study in Norfolk, UK

“…Heavy metals are of great concern because, unlike organic pollutants, they remain unaffected during the degradation of waste, thereby having adverse impacts on living organisms ( Esakku et al., 2003 ; Hogland et al., 2014 ; Jain et al., 2005 ; Mehta et al., 2019 ; Ngole-Jeme and Fantke, 2017 ). Some metals such as, Cd, Cr, and Pb are well known to be toxic to human health, even at very low concentrations ( Adewumi and Laniyan, 2020 ; Csavina et al., 2012 ; Padoan et al., 2020 ), and can pose carcinogenic risks ( Bhatti et al., 2020 ; Gujre et al., 2021 ; Kamunda et al., 2016 ; Thongyuan et al., 2020 ). Exposure to such heavy metal concentrations may lead to numerous health problems, particularly in susceptible individuals, including the elderly and children ( Briki et al., 2017 ; Csavina et al., 2012 ; Dubey et al., 2012 ; Kamunda et al., 2016 ; Stewart, 2019 ).…”

“…A critical review of studies on LFM revealed that research has primarily focussed on material and energy recovery ( Dino et al., 2018 ; Gutiérrez-Gutiérrez et al., 2015 ; Mehta et al., 2020 ; Pecorini and Iannelli, 2020 ). However, there is a fundamental lack of understanding of how these activities could affect the environment and human health ( Frändegård et al., 2013 ; Nguyen et al., 2018 ; Padoan et al., 2020 ). Therefore, this study considered such environmental and human health impacts.…”