Serena Carbone

Toxicity and transfer of metal oxide nanoparticles from microalgae to sea urchin larvae

Nanoparticles (NPs) contained in commercial products are released and enter into the aquatic ecosystem, posing serious possible risks to the environment and affecting the food chain. Therefore, investigating the potential toxicity of NPs on aquatic organisms has become an important issue. This study assessed the toxicity and trophic transfer of metal oxide NPs from marine microalgae (Cricosphaera elongata) to the larvae of the sea urchin Paracentrotus lividus. Larvae (24 h old) were fed on 2000 cell mL−1 48 h of microalgae contaminated with 5 mg L−1 of several metal oxide NPs (SiO2, SnO2, CeO2, Fe3O4) for 15 days. Larval viability and development were monitored from the 4-arm stage to the 8-arm pluteus stage. A significant decrease in survival was observed in larvae fed with microalgae exposed to SiO2 and CeO2 NPs. Abnormal development, characterised by skeletal degeneration and altered rudiment growth, was observed in all larvae fed with contaminated NP algae. Our findings revealed that SiO2 and CeO2 NPs exerted a toxic effect in the trophic interaction analysed, by reducing sea urchin larval viability, and all metal oxide NPs induced toxicological effects. In conclusion, metal oxide NPs may enter the food chain and become bioavailable for marine organisms, affecting their development.

Bioavailability and biological effect of engineered silver nanoparticles in a forest soil

The extensive use of silver nanoparticles (SNPs) as antimicrobial in food, clothing and medicine, leads inevitably to a loss of such nanomaterial in soil and water. Little is known about the effects of soil contamination, in particular, on microbial cells, which play a fundamental ecological role. In this work, the impact of SNPs on forest soil has been studied, investigating eco-physiological indicators of microbial biomass and microbial diversity with culture-dependent and independent techniques. Moreover, SNPs bioavailability and uptake were assessed. Soil samples were spiked with SNPs at two different concentrations (10 and 100 μg g(-1)dw) and incubated with the relative controls for 30, 60 and 90 days. The overall parameters showed a significant influence of the SNPs on the soil microbial community, revealing a marked shift after 60 days of incubation.

Bioavailability of CeO2 and SnO2 nanoparticles evaluated by dietary uptake in the earthworm Eisenia fetida and sequential extraction of soil and feed

The growing number of nanotechnology products on the market will inevitably lead to the release of engineered nanomaterials with potential risk to humans and environment. This study set out to investigate the exposure of soil biota to engineered nanoparticles (NPs). Cerium dioxide (CeO2 NPs) and tin dioxide nanoparticles (SnO2 NPs) were radiolabelled using neutron activation, and employed to assess the uptake and excretion kinetics in the earthworm Eisenia fetida. Through sequential extraction, NPs bioavailability in two contrasting soils and in earthworm feed was also investigated. Neither CeO2 NPs nor SnO2 NPs bioaccumulated in earthworms, and both were rapidly excreted when worms were transferred to clean soil. Low bioavailability was also indicated by low amounts of NPs recovered during extraction with non-stringent extractants. CeO2 NPs showed increasing mobility in organic soil over time (28 days), indicating that organic matter has a strong influence on the fate of CeO2 NPs in soil.

Thallium Toxicity in Mediterranean Horticultural Crops (Fragaria vesca L., Mentha pulegium L., Ocimum basilicum L.)

Thallium is a non-essential, toxic element that concerns mining areas and their acid drainage effluents. Minerals containing thallium can be eroded, and Tl can be leached into soil, thus being spread into the environment and adsorbed by plants and living organisms, entering the food chain, and inducing serious toxicity problems. In this study, the Tl cycle was observed and analyzed on basil, mint, and strawberry cultivated in a greenhouse and irrigated with Tl-contaminated water. The Tl content in both bulk and rhizosphere soils as well as thallium present in different plant organs were analyzed during the experiment, with the aim of revealing both physiological symptoms and metabolic disorders linked to the Tl toxicity. The mechanism of plants to exclude, uptake, translocate, and tolerate Tl varied among the different species, and both the bioconcentration factor (BCF) and the translocation index (TI) were calculated to highlight a different response to Tl toxicity of strawberry, mint, and basil. Basil is the less tolerant species, while mint and strawberry showed different self-defense mechanism against Tl adsorption and translocation.