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Nanosilver applications, including sensing and water treatment, have significantly increased in recent years, although safety for humans and the environment is still under debate. Here, we tested the environmental safety of a novel formulation of silver nanoparticles functionalized with citrate and L-cysteine (AgNPcitLcys) on freshwater cnidarian

Plastic pollution is recognized as a global environmental threat and concern is increasing regarding the potential interactions of the smallest fragments, nanoplastics (1 µm), with either physical and chemical entities encountered in the natural environment, including toxic pollutants. The smallest size of nanoplastics (100nm) rebounds to their safety associated with remarkable biological, chemical and physical reactivity that allow them to interact with cellular machinery by crossing biological barriers and causing damage to living beings. Recent findings on nanoplastic occurrence in marine coastal waters, including the Mediterranean Sea, leave open the question on their ability to act as a vector of other contaminants of emerging concerns (CECs) concomitantly released by wastewater treatment plants and reaching marine coastal waters. Here, we assess for the first time the role of non-functionalized polystyrene nanoparticles (PS NPs, 20 nm) as a proxy for nanoplastics (1 and 10 µg/mL) alone and in combination with bisphenol A (BPA) (4.5 and 10 µM) on

Plastic pollution is a global issue posing a threat to marine biota with ecological implications on ecosystem functioning. Micro and nanoplastic impact on phytoplankton autotrophic species (e.g., cell growth inhibition, decrease in chlorophyll a and photosynthetic efficiency and hetero-aggregates formation) have been largely documented. However, the heterogeneity of data makes rather difficult a comparison based on size (i.e. micro vs nano). In addition, knowledge gaps on the ecological impact on phytoplankton assemblage structure and functioning are evident. A new virtual meta-analysis on cause-effect relationships of micro and nanoplastics on phytoplankton species revealed the significant effect posed by polymer type on reducing cell density for tested PVC, PS and PE plastics. Linked with autotrophic phytoplankton role in atmospheric CO2 fixation, a potential impact of plastics on marine carbon pump is discussed. The understanding of the effects of microplastics and nanoplastics on the phytoplankton functioning is fundamental to raise awareness on the overall impact on the first level of marine food web. Interactions between micro and nanoplastics and phytoplankton assemblages have been quite documented by in vitro examinations; but, further studies considering natural plankton assemblages and/or large mesocosm experiments should be performed to evaluate and try predicting ecological impacts on primary producers.

Marine diatoms have been identified among the most abundant taxa of microorganisms associated with plastic waste collected at sea. However, the impact of nano-sized plastic fragments (nanoplastics) at single cell and population level is almost unknown. We exposed the marine diatom Skeletonema marinoi to model polystyrene nanoparticles with carboxylic acid groups (PS–COOH NPs, 90 nm) for 15 days (1, 10, 50 μg/mL). Growth, reactive oxygen species (ROS) production, and nano-bio-interactions were investigated. No effect on diatom growth was observed, however Dynamic light scattering (DLS) demonstrated the formation of large PS aggregates which were localized at the diatoms’ fultoportula process (FPP), as shown by TEM images. Increase production of ROS and reduction in chain length were also observed upon PS NPs exposure (p < 0.005). The observed PS-diatom interaction could have serious consequences on diatoms ecological role on the biogeochemical cycle of carbon, by impairing the formation of fast-sinking aggregates responsible for atmospheric carbon fixation and sequestration in the ocean sea floor. S. marinoi exposure to PS NPs caused an increase of intracellular and extracellular oxidative stress, the reduction of diatom's chain length and the adhesion of PS NPs onto the algal surface.

Acid mine drainage (AMD) is a global environmental challenge that represents a primary source of contamination of heavy metals in both active and abandoned mining areas. The present study explored the suitability of a carboxymethylcellulose (CMC) hydrogel cross-linked with functionalized magnetite (Fe3O4) nanoparticles, (CMC-Fe3O4), for the removal of heavy metals from AMD-affected stream waters and tested its eco-friendly nature. AMD-affected stream waters, collected in a former mining site located in the Metalliferous Hills ore district (Central Italy), were chosen as a suitable benchmark for validating the CMC-Fe3O4 hydrogel applications. The remediation capability of the CMC-Fe3O4 hydrogel was investigated on solutions of Zn(II) in deionized (DI) water and on samples of AMD-affected stream waters. The CMC-Fe3O4 hydrogel was able to adsorb Zn(II) from DI water solutions as well as to reduce significantly the concentration of Zn and other heavy metals such as Cd, Co, Cu, Ni and Pb, in AMD-affected stream waters. CMC-Fe3O4 hydrogel and treated waters (both Zn-solution and AMD-affected stream waters) were tested for their effects on the freshwater green alga R. subcapitata by using 72-h growth inhibition tests. No effects were observed on the R. subcapitata growth upon exposure to CMC-Fe3O4 hydrogel, suggesting its eco-friendly nature. Moreover, CMC-Fe3O4 hydrogel was able to reduce the toxicity of heavy metals to the green alga, both in DI and AMD-affected stream water. Based on our findings, CMC-Fe3O4 hydrogel could be considered as a valuable tool for an environmentally safe treatment of AMD-affected stream waters.