Rare Earth Elements in Urban and mining aReas: an EmErging Concern for soil (and human) heAlth

Rare Earth Elements (REEs) are a group of elements with unique physical and chemical properties. Their importance grew in recent years, becoming essential as industrial materials, particularly in electronics and in technologies involved in the transition to a low-carbon technology. As a result, REEs content in urban environments and areas exploited for mining activities increased substantially in the last decades, and REEs are now regarded as Contaminants of Emerging Concern (CEC) due to their potential human and ecological risks. In urban, mining and industrial areas, REEs can have diverse sources and one major sink, namely soils. These latter, in turn, may become a source of REEs for plants and soil microorganisms, as well as for other environmental compartments, having significant consequences for soil and possibly human health due, for example, to the transfer of REEs-contaminated soil particles into the atmosphere. The overall aim of the project is to obtain a picture of REEs occurrence, mobility and ecotoxicity in the pedosphere, and their transfer to the atmosphere and the biosphere, plants in particular. To this aim, the project will consider the main environmental compartments where REEs can be found in substantial amounts and will evaluate the source-sink relationships by running experiments on their possible transfer to appraise the environmental risk related to these CEC. The studied environments will be urban, industrial and mining areas in Piedmont, Tuscany and Sardinia (Italy), where large urban areas and sites affected by intense mining and smelting activities are present together with industrial sites. After exploratory surveys and analyses, soils and native plants will be sampled in the aforementioned areas according to a unified procedure and will be characterized for their chemical and physical properties. The REEs content in soil and plant samples will be determined using a common methodology and the data shared with all partners. A suitable set of soil samples (SET) will then be selected for the subsequent experiments to investigate the source-sink relationships. In particular, the following experiments will be run: - Chemical fractionation of REEs - REEs bioaccessibility assessment - REEs release in different redox conditions - REEs soil-plant transfer - REEs Impact on soil microbial characteristics and enzyme activity - Nd, Pb and Sr isotope fingerprinting of samples The results arising from this project are expected to provide a detailed picture on REEs occurrence, concentration, bioaccessibility and impact on soil health, in different REE hotspots. This will be fundamental in order to design sustainable approaches for the remediation of REEs contaminated sites. At the same time, a more detailed knowledge of REEs occurrence and impact will be useful to define (or update) health risks connected to the investigated areas.