Relationships between bioaccessibility and speciation of ETPs in mining-affected soils.

The consequences of mining activities on the earth's surface inevitably lead to situations in which measures are needed to mitigate the impact on soil, water and air. The measures that counteract these negative effects are defined in what is known as remediation or remediation, recovery, rehabilitation and restoration. It constitutes the so-called R4 strategy (Lima et al., 2016), being sometimes difficult to be able to differentiate the nuances contained in these four terms when they are referred to the elimination of the effects produced by mining. In the case of large areas, such as a large natural area that is affected to varying degrees by mining, the strategies to be considered can be very varied and include more than one R, trying to minimize the impacts and reduce the risks by making them acceptable.

In the new European landscape, healthy soils are essential to achieve climate neutrality, a clean and circular economy and to stop desertification and land degradation. They are also essential to reverse biodiversity loss, provide healthy food and safeguard human health. The proposed tool to achieve this is the new Soil Monitoring Law provides a legal framework to help achieve healthy soils by 2050. In the case of soils with mining influence, the policies to be followed must be associated to the risk, since these soils naturally present a high level of PTEs.

In this work, 60 samples obtained from different abandoned mining sites in the Region of Murcia are evaluated to determine the risks they present in terms of the health of people, ecosystems and structures. For this purpose, different extracting media (water, acid and Olsen extraction (natural mobility), Mehra - Jackson extraction and oxidizing medium (potential mobility)) and the Solubility Bioaccessibility Research Consortium (SBRC) method are used, distinguishing two phases, stomach and intestinal. The PTEs evaluated were: As, Cd, Cu, Pb and Zn.

The results were contrasted with the differential mineralogy calculated for each sample, estimating the relationship between the mineralogical phase present and the mobility and bioaccessibility of the PTE. The bioaccessibility of the PTEs contained in the soils and their natural or potential mobility are determining factors in the risk assessment that will later affect the R measures, allowing to manage abandoned mining areas safely and efficiently.

Reference:

Lima, A.T., Mitchell, K., O’Connell, D.W., Verhoeven, J., Van Cappellen, P., 2016. The legacy of surface mining: Remediation, restoration, reclamation and rehabilitation. Environmental Science & Policy 66, 227-233.