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Soil contamination by heavy metals represents an important environmental and public health problem of global concern. Biocrust-forming cyanobacteria offer promise for heavy metal immobilisation in contaminated soils due to their unique characteristics, including their ability to grow in contaminated soils and produce exopolysaccharides (EPS). However, limited research has analysed the representativeness of cyanobacteria in metal-contaminated soils. Additionally, there is a lack of studies examining how cyanobacteria adaptation to specific environments can impact their metal-binding capacity. To address this research gap, we conducted a study analysing the bacterial communities of cyanobacteria-dominated biocrusts in a contaminated area from South Sardinia (Italy). Additionally, by using two distinct approaches, we isolated three Nostoc commune strains from cyanobacteria-dominated biocrust and we also evaluated their potential to immobilise heavy metals. The first isolation method involved acclimatizing biocrust samples in liquid medium while, in the second method, biocrust samples were directly seeded onto agar plates. The microbial community analysis revealed Cyanobacteria, Bacteroidota, Proteobacteria, and Actinobacteria as the predominant groups, with cyanobacteria representing between 13.3 % and 26.0 % of the total community. Despite belonging to the same species, these strains exhibited different growth rates (1.1-2.2 g L -1 of biomass) and capacities for EPS production (400-1786 mg L -1 ). The three strains demonstrated a notable ability for metal immobilisation, removing up to 88.9 % of Cu, 86.2 % of Pb, and 45.3 % of Zn from liquid medium. Cyanobacteria EPS production showed a strong correlation with the removal of Cu, indicating its role in facilitating metal immobilisation. Furthermore, differences in Pb immobilisation (40-86.2 %) suggest possible environmental adaptation mechanisms of the strains. This study highlights the promising application of N. commune strains for metal immobilisation in soils, offering a potential bioremediation tool to combat the adverse effects of soil contamination and promote environmental sustainability., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

Juncus acutus has been proposed as a suitable species for the design of phytoremediation plans. This research aimed to investigate the role played by rhizosphere minerals and water composition on Zn transformations and dynamics in the rhizosphere-plant system of J. acutus exposed to different Zn sources. Rhizobox experiments were conducted using three different growing substrates (Zn from 137 to 20,400 mg/kg), and two irrigation lines (Zn 0.05 and 180 mg/l). The plant growth was affected by the substrate type, whereas the Zn content in the water did not significantly influence the plant height for a specific substrate. J. acutus accumulated Zn mainly in roots (up to 10,000 mg/kg dw); the metal supply by the water led to variable increases in the total Zn concentration in the vegetal organs, and different Zn distributions both controlled by the rhizosphere mineral composition. Different Zn complexation mechanisms were observed, mainly driven by cysteine and citrate compounds, whose amount increased linearly with Zn content in water, but differently for each of the investigated systems. Our study contributes to gain a more complete picture of the Zn pathway in the rhizosphere-plant system of J. acutus. We demonstrated that this vegetal species is not only capable of developing site-specific tolerance mechanisms, but it is also capable to differently modulate Zn transformation when Zn is additionally supplied by watering. These findings are necessary for predicting the fate of Zn during phytoremediation of sites characterized by specific mineralogical properties and subject to water chemical variations., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

This work is a part of a research project conducted in order to characterize the volcanic ash from Mount Etna, focusing in particular on the surface reactivity of ashes and possible consequence for human health. In this framework, a sampling campaign began on 16 March 2013, taking advantage of the intense volcanic activity on Etna. The interaction between volcanic ash and human organism was simulated treating two classes of representative Etnean particles with ultrapure water (grainsize of 850 um) and Gamble's solution mimic lug fluids (grainsize <38 μm) with the aim to evaluate the risk due to gastric and respiratory exposure to volcanic particles. The leachates were analysed by Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES), Inductively Coupled Plasma Mass Spectrometry (ICP-MS) and Ionic Chromatography (CI) in order to highlight possible dangerous elements released in water solutions according to USGS protocol. Analyses of Gamble's solution highlighted a release of elements smaller than in watery solutions and always below the thresholds established by the Italian law. On the contrary, analyses of watery solutions evidenced, for some elements (B, Cd, Ni and As), levels higher than permitted by Italian law. Considering the effects of these elements on human health, further investigations are necessary and currently carried out in order to better constrain the release process and the specific effects on human organism., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)