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The waste rock, tailings and soil around an abandoned mine site in Gorno (northwest Italy) contain elevated concentrations of potentially toxic elements (PTE) exceeding the permissible limits for residential uses. Specifically, the maximum concentrations of As, Cd, Pb, and Zn were 107 mg/kg, 340 mg/kg, 1064 mg/kg, and 148 433 mg/kg, respectively. A site-specific human health risk assessment (HHRA) was conducted for residential and recreational exposure scenarios, using an approach based on Risk Based Corrective Action (RBCA) method, refined by incorporating oral bioaccessibility data. Oral bioaccessibility analyses were performed by simulating the human digestion process in vitro (Unified BARGE Method). Detailed analysis of oral bioaccessible fraction (BAF i.e. ratio of bioaccessible concentrations to total concentrations on 1) for 50% of the samples, indicating potential human health risks. This study provides information for site-specific risk assessments and planning future research.

The relevant environmental hazard related to the presence of pharmaceuticals in water sources requires the development of high effective and suitable wastewater treatment technologies. In the present work, a hybrid process coupling electro-Fenton (EF) process and aerobic biological treatment (Bio-EF process) was implemented for the efficient and cost-effective mineralization of beta-blocker metoprolol (MPTL) aqueous solutions. Firstly, operating factors influencing EF process were assessed. MTPL solutions were completely mineralized after 4 h-electrolysis under optimal operating conditions and BDD anode demonstrated its oxidation superiority. The absolute rate constant of MTPL oxidation by OH ( k MTPL ) was determined by the competition kinetics method and found to be (1.72 ± 0.04) × 10 9 M −1 s −1 . A reaction pathway for the mineralization of the drug was proposed based on the identification of oxidation by-products. Secondly, EF process was used as pre-treatment. An increase of BOD 5 /COD ratio from 0.012 to 0.44 was obtained after 1 h EF treatment, along with 47% TOC removal and a significant decrease of toxicity, demonstrating the feasibility of a post-biological treatment. Finally, biological treatment successfully oxidized 43% of the total TOC content. An overall 90% mineralization of MPTL solutions was achieved by the Bio-EF process, demonstrating its potentiality for treating wastewater containing pharmaceutical residues.

Antibiotic resistance genes (ARGs) constitute emerging environmental pollutants and pose risks to public health. Toxic metals are known to select for metal-resistant bacteria in metal-contaminated soils, but there is growing concern that metal contaminants can also act as co-selective agents thereby causing environmental proliferation of antibiotic resistance. In this study, we quantified ARGs and selected mobile genetic elements (MGEs) known to constitute potential ARG hosts in 50 archived urban and suburban soils from the Belfast metropolitan area using a high-throughput qPCR ARG chip. ARG prevalence was linked to concentrations of individual metals and a soil metal toxicity index calculated based on the relative toxicity of different metals to soil microbial processes. A total of 164 ARGs were detected across the 50 soils analyzed with an average absolute abundance of 3.4 × 107 ARG gene copies per gram of soil. A significant correlation between abundance of ARGs and MGEs was observed, suggesting the importance of horizontal gene transfer for ARG dissemination. Network analysis revealed significant co-occurrence patterns between specific metals (As, Cd, Co, Cr, Cu. Hg, Ni and Zn) and associated ARGs. Path analysis further indicated that the soil metal toxicity index significantly affected the number of detected ARGs (λ = 0.32, P < 0.001) and the abundance of metal co-occurring ARGs (λ = 0.612, P < 0.001) via effects on MGEs. Collectively, our results indicate a role of soil metals in co-selection of ARGs and MGEs in urban and semi-urban soils and suggest a risk for environmental ARG dissemination via horizontal gene transfer.

Oral bioaccessibility and solid phase distribution of potentially toxic elements (PTE) from extractive waste streams were investigated to assess the potential human health risk posed by abandoned mines. The solid phase distribution along with micro-X-ray fluorescence (micro-XRF) and scanning electron microscopy (SEM) analysis were also performed. The results showed that the total concentrations of PTE were higher in

Mining activities have led to the introduction of high levels of heavy metal (HM) concentrations in soils. This has attracted governmental and public attention due to their non-biodegradable nature and hazards posed to human health and the environment. However, total concentrations of HM are poor indicators of actual risk hazard to human health and can lead to overestimation of risk. In this study, oral bioaccessibility (the fraction available for absorption via oral ingestion), was used to refine human health risk assessment. Solid phase distribution of the HM was also investigated to characterize HM distribution and behavior in the extractive waste streams and impacted soil. The study was undertaken at an abandoned mine site from Campello Monti, in the Southern Italian Alps used for Ni exploitation from 1863 to 1940s. The results showed that total concentrations of HM were high and reached upto 7400 mg/kg for Ni due to parent material, however, only 11% was bioaccessible. Detailed analysis showed that the bioaccessible fraction (BAF) of Ni, Cu and As varied from 0.5 to 21%, 2 to 47%, and 7 to 28%, respectively. The variation can be attributed to the difference in pH, organic matter content and mineralogical composition of the samples. Results of non-specific sequential extraction showed that non-mobile forms of the elements were associated with the residual and Fe-oxides components of the matrix. The present study highlights that including bioaccessibility and solid phase distribution can refine and inform risk assessment of abandoned mine sites.