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The present study was aimed at identifying geospatial patterns of pollutants including concentrations and toxicity as complex environmental mixtures, in topsoil samples close to petrochemical facilities in the heavily industrialized area of Augusta and Priolo in south-eastern Sicily (Italy). Elemental analysis of soil was conducted by ICP-MS for 23 metals and 16 rare earth elements (REEs). Organic analyses were primarily focused on poly- cyclic aromatic hydrocarbons (PAHs) (16 parent homologs) and total aliphatic hydrocarbons (C10–C40). Topsoil samples were tested for toxicity in multiple bioassay models including: 1) developmental defects and cytogenetic anomalies in sea urchinSphaerechinus granularisearly life stages; 2) growth inhibition of diatomPhaeodactylum tricornutum; 3) mortality in nematodeCaenorhabditis elegans; and 4) induction of mitotic abnor- malities in onionAllium cepa. Samples collected at sites closest to defined petrochemical facilities were highest in select pollutants and correlated with biological effects in different toxicity endpointthe increased level of total REEs in sites closest to petrochemical facilities, suggesting their contributions to identifying petrochemical sources of pollutants to the environment. The combined data obtained in the different bioassays allowed exploration of geospatial patterns of effect in biota as a function of contaminant levels. In conclusion, this study provides consistent data of soil toxicity, metal and REE contamination at Augusta-Priolo sampling sites, and may provide an appropriate baseline for epidemiological studies on high incidences of congenital birth defects in the area and identification of at-risk localities.

Silver nanoparticles (AgNPs) are of great interest due to their antimicrobial properties, but their reactivity and toxicity pose a significant risk to aquatic ecosystems. In biological systems, AgNPs tend to aggregate and dissolve, so they are often stabilized by agents that affect their physicochemical properties. In this study, microalga Chlorella vulgaris was used as a model organism to evaluate the effects of AgNPs in aquatic habitats. Algae were exposed to AgNPs stabilized with citrate and cetyltrimethylammonium bromide (CTAB) agents and to AgNO3 at concentrations that allowed 75% cell survival after 72 h. To investigate algal response, silver accumulation, ROS content, damage to biomolecules (lipids, proteins, and DNA), activity of antioxidant enzymes (APX, PPX, CAT, SOD), content of non-enzymatic antioxidants (proline and GSH), and changes in ultrastructure were analyzed. The results showed that all treatments induced oxidative stress and adversely affected algal cells. AgNO3 resulted in the fastest death of algae compared to both AgNPs, but the extent of oxidative damage and antioxidant enzymatic defense was similar to AgNP-citrate. Furthermore, AgNP- CTAB showed the least toxic effect and caused the least oxidative damage. These results highlight the importance of surface-stabilizing agents in determining the phytotoxicity of AgNPs and the underlying mechanisms affecting aquatic organisms.

Plastics in the environment has become a global problem, not only due to their presence as macro-scale marine litter, but also as small particles arising from the degradation of larger plastics under UV light and the mechanical action of waves. As the smallest fraction, nanoparticles of plastic, typically characterised by dimensions less than 100 nm, may be extremely widespread and available to biota, potentially leading to bioaccumulation and biomagnification within food chains that may ultimately impact upon human health. Moreover, as nanoplastics have significant ability to sorb secondary pollutants, understanding their behaviour and fate in marine waters is of great importance, particularly in terms of their toxicity potential towards biota. In this direction, we report on the synthesis, characterisation and behaviour of polymer nanoparticles in aquatic matrices. Polystyrene (PS) and polymethyl methacrylate (PMMA) nanoparticles were synthesised by mini-emulsion polymerisation with sizes in range 25- 430 nm. Narrow particle size distributions by volume were demonstrated by dynamic light scattering (DLS), and their morphology was confirmed by transmission electron microscopy (TEM) and atomic force microscopy (AFM). The concurrent influence of abiotic parameters and natural organic matter (NOM) on nanoplastic stability was determined in aqueous matrices with varying electrolyte concentrations as proxies for freshwater, brackish water and seawater. Bovine serum albumin (BSA) was selected as a model for proteinaceous matter in wastewater, while humic acid (HA) and alginate (Alg) were selected as representatives of NOM in fresh and marine waters, respectively. The influence of salinity, ranging between S 0-38, pH values from 6.8 to 7.8 and NOM at concentrations in range 0-100 mg L–1 was determined. Additionally, the impact of oxygen saturation (50% and 90%) on nanoplastic behaviour was defined. PMMA nanoparticles showed strong colloidal stability in all cases, in contrast to PS nanoparticles, and despite of the widely varying parameters did not show any indication of agglomeration/aggregation. This indicates that of the tested nanoplastics, PMMA may remain longer in the water column and be more available for sequestration by biota living in those environmental compartments. Ultimately, this work is a step in the direction of creating tailored polymer nanoparticles to enable greater understanding of their pathways through the environment and modes of toxicity in marine biota.