Civilization development is associated with the use of plastic. When plastic was introduced to the market, it was assumed that it was less toxic than glass. Recently, it is known that plastics are serious ecological problem they, do not degrade and remain in the environment for hundreds of years.Plastic may be degraded into micro-particles < 5000 nm in diameter, and further into nanoparticles (NPs) < 100 nm in diameter. NPs have been detected in air, soil, water and sludge.One of the most commonly used plastics is polystyrene (PS) - a product of polymerization of styrene monomers. It is used for the production of styrofoam and other products like toys, CDs and cup covers. In vivo and in vitro studies have suggested that polystyrene nanoparticles (PS-NPs) may penetrate organisms through several routes i.e. skin, respiratory and digestive tracts. They can be deposited in living organisms and accumulate further along the food chain. NPs are surrounded by “protein corona” that allows them penetrating cellular membranes and interacting with cellular structures. Depending on the cell type, NPs may be transported through pinocytosis, phagocytosis, or be transported passively. Currently there are no studies that would indicate a carcinogenic potential of PS-NPs. On the other hand, the PS monomer (styrene) was classified by the International Agency for Research on Cancer (IARC) as a potentially carcinogenic substance (carcinogenicity class B2).Despite of the widespread use of plastics and the presence of plastic NPs of secondary or primary nature, there are no studies that would assess the effect of those substances on human organism. This study was aimed at the review of the literature data concerning the formation of PS-NPs in the environment, their accumulation along the food chain, and their potential adverse effects on organisms on living various organization levels.

Oxidative stress is considered a main commonly reported mechanism of nanoparticles toxicity, so this study aimed to evaluate oxidative stress and biochemical alterations in the haemolymph and digestive gland of snail, Monacha cartusiana exposed to sublethal concentrations of zinc oxide nanoparticles (ZnONPs) for 14 days (d). The results indicated that, ZnONPs induced significant increases in lipid peroxidation (LPO) and lactate dehydrogenase (LDH) in treated animals and did not return to normal levels after recover period. A significant decline of glutathione peroxidase (GPx), glutathione-S-transferase (GST) activities, and glutathione (GSH) content in the haemolymph and digestive gland of snails was observed when compared with control. A significant increase was observed in catalase (CAT), alanine aminotransferase (ALT), and aspartate aminotransferase (AST) activities of treated animals. In general, nano-materials are able to induce oxidative stress in exposed animals. The present findings indicate that, alterations of antioxidant enzyme activities, increase of LPO, LDH, and reducing of GSH content and GST, GPx activities are recognized to oxidative stress and cell damage. This species could be considered a good bioindicator to assess nano-materials exposure.

The interactive effects of elevated atmospheric CO₂ and nanoparticles (NPs) on the structure and function of soil bacterial community remain unknown. Here we compared the impacts of CeO₂ (nCeO₂) and Cr₂O₃ (nCr₂O₃) nanoparticles on the taxonomic compositions and functional attributes of bacterial communities under elevated CO₂ (eCO₂). The stimulated enzyme activities (dehydrogenase, acid phosphatase and urease), increased microbial biomass carbon (MBC), and higher bacterial alpha-diversity were observed under the combined effects of eCO₂ and NPs compared to the single NP treatment, indicating eCO₂ could mitigate the adverse effect of NPs on soil microorganisms. NPs and eCO₂ are important factors influencing the alpha- and beta-diversity (17% and 18% of variations were explained) as well as functional profile (20% and 26% of variations were explained) of bacterial communities. Rising CO₂ level promoted the resilience of NP-resistant bacterial populations, primarily the members of Alphaproteobacteria, Gammaproteobacteria and Bacteroidia, which are also characterized by the fast carbon use capability. Moreover, the significantly (P < 0.05) higher metabolic quotient (qCO₂), reduced available carbon and overrepresented carbon metabolism genes at eCO₂vs. ambient CO₂ (aCO₂) indicate the acceleration of available carbon turnover in NP-exposed soils. Correlation analysis revealed that mitigation of NPs toxicity by eCO₂ could be attributed to the remarkable decline of bioavailable metals disassociated from NPs and available carbon level, as well as promotion of the rapid carbon-metabolizing microbes. Our study pointed out the positive role of eCO₂ in alleviating the adverse effect of NPs on microbiological soil environment, and results can serve as important basis in establishing guidelines for lowering the ecotoxicity of NPs.

The production and soil accumulation of nanoparticles (NPs) from the industrial sector has increased concerns about their toxic effects in plants which needs the research to explore the ways of reducing NPs toxicity in pants. The gibberellic acid (GA) has been found to reduce abiotic stresses in plants. However, the effect of GA in reducing zinc oxide (ZnO) NPs-mediated toxicity in plants remains unclear. In this study, foliar application of GA was used to explore the possible role in reducing ZnO NPs toxicity in wheat (Triticum aestivum L.) plants. The plants were grown in pots spiked with ZnO NPs (0, 300, 600, 900, 1200 mg/kg) and GA (0, 100, 200 mg/L) was foliar sprayed at different times during the growth period under ambient environmental conditions. Our results demonstrated that GA inhibited the toxicity of ZnO NPs in wheat especially at higher levels of NPs. The GA application improved the plant biomass, photosynthesis, nutrients, and yield under ZnO NPs stress. The GA reduced the Zn accumulation, and reactive oxygen species generation in plants caused by toxicity of NPs. The protective effect of GA in decreasing ZnO NPs-induced oxidative stress was related to GA-mediated enhancement in antioxidant enzymes in plants. The role of GA in enhancing tolerance of wheat against ZnO NPs was further confirmed by the enhancement in nutrient contents in shoots and roots of wheat. Overall, our study provides the evidence that GA can reduce ZnO NPs-induced toxicity in wheat and probably in other crops which needs further in-depth investigation.

Mercury (Hg) and methylmercury (CH3Hg) bind strongly to micro and nano (NP) particles and this partitioning impacts their fate and bioaccumulation into food webs, and, as a result, potential human exposure. This partitioning has been shown to influence the bioavailability of inorganic Hg to methylating bacteria, with NP-bound Hg being more bioavailable than particulate HgS, or organic particulate-bound Hg. In this study we set out to investigate whether the potential interactions between dissolved ionic Hg (HgII) and CH3Hg and NPs was due to incorporation of Hg into the core of the cadmium selenide and sulfide (CdSe; CdS) nanoparticles (metal exchange or surface precipitation), or due purely to surface interactions. The interaction was assessed based on the quenching of the fluorescence intensity and lifetime observed during HgII or CH3Hg titration experiments of these NP solutions. Additional analysis using inductively coupled plasma mass spectrometry of CdSe NPs and the separated solution, obtained after HgII additions, showed that there was no metal exchange, and X-ray photoelectron spectroscopy confirmed this and further indicated that the Hg was bound to cysteine, the NP capping agent. Our study suggests that Hg and CH3Hg adsorbed to the surfaces of NPs would have different bioavailability for release into water or to (de)methylating organisms or for bioaccumulation, and provides insights into the behavior of Hg in the environment in the presence of natural or manufactured NPs.

Although the development of constructing oil-water separation materials is quick, the defects of using harmful regents, weak stability and single function still exist. Here, we report an effective and less-harmful system with poly-dimethylsiloxane (PDMS)/ZnO composite solution to fabricate robust superhydrophobic surfaces for oil-water separation and removal of organic pollutant. The obtained samples were characterized by a range of instruments. The water contact angle (WCA) of coated cotton was 155.6°, which attributed to the synergetic effect of low surface energy of PDMS and roughness of ZnO nanoparticles. The coated cotton was tolerant to mechanical damage, various corrosive solvents and temperature conditions. The emphasis of this study is the combination of superhydrophobicity and photocatalysis, resulting in multifunctional cotton with dual self-cleaning properties, outstanding oil-water separation ability and efficient water purification property. When utilized a simple laboratory facility, the cotton could separate water from oil-water mixture with a high efficiency (99.3%). Furthermore, the dyed water could be purified with coated cotton through photocatalysis under UV light and became colorless. Meanwhile, this mild and facile method could also be utilized to modify other porous substrates, such as PET, silk, non-woven and sponge. Therefore, the characteristics of environmental protection and easy operation make this cotton a desirable candidate for extensive applications in self-cleaning, oil-water separation and water purification.

Sewage sludge contains Ag₂S-NPs causing NP exposure of soil fauna when sludge is applied as soil amendment. Earthworm bioturbation is an important process affecting many soil functions. Bioturbation may be affected by the presence of Ag₂S-NPs, but the earthworm activity itself may also influence the displacement of these NPs that otherwise show little transport in the soil. The aim of this study was to determine effects of Ag₂S-NPs on earthworm bioturbation and effect of this bioturbation on the vertical distribution of Ag₂S-NPs. Columns (12 cm) of a sandy loamy soil with and without Lumbricus rubellus were prepared with and without 10 mg Ag kg⁻¹, applied as Ag₂S-NPs in the top 2 cm of the soil, while artificial rainwater was applied at ∼1.2 mm day⁻¹. The soil columns were sampled at three depths weekly for 28 days and leachate collected from the bottom. Total Ag measurements showed more displacement of Ag to deeper soil layers in the columns with earthworms. The application of rain only did not significantly affect Ag transport in the soil. No Ag was detected in column leachates. X-ray tomography showed that changes in macro porosity and pore size distribution as a result of bioturbation were not different between columns with and without Ag₂S-NPs. Earthworm activity was therefore not affected by Ag₂S-NPs at the used exposure concentration. Ag concentrations along the columns and the earthworm density allowed the calculation of the bioturbation rate. The effect on the Ag transport in the soil shows that earthworm burrowing activity is a relevant process that must be taken into account when studying the fate of nanoparticles in soils.

Antibiotics in water and soil are persistent, bioaccumulative and toxic to aquatic organisms and human health. To address it, as one of the new technologies, green synthesized magnetic Fe₃O₄ nanoparticles by Excoecaria cochinchinensis extract used to remove rifampicin (RIF) was investigated in this study. Results showed the adsorption efficiency of RIF reached 98.4% and the maximum adsorption capacity is 84.8 mg/g when 20 mL of RIF at a concentration of 20 M was adsorbed by 10 mg Fe₃O₄ at a temperature of 303 K. The morphology of the green Fe₃O₄ characterized by SEM demonstrated the dimensions ranging from 20 to 30 nm. The N₂ adsorption/desorption isotherms revealed that the surface area of Fe₃O₄ was 111.8 m²/g. In addition, adsorption studies indicated that the kinetics fitted the pseudo second-order and isothermal adsorption conformed to the Langmuir isotherm. Furthermore, due to their magnetic properties, the Fe₃O₄ nanoparticles were easily separated and reused and the mechanism for removing RIF occurred through adsorption rather than chemical redox reaction. Finally, the reusability of Fe₃O₄ for adsorption of RIF showed that the removal efficiency decreased to 61.5% after five cycles.

Degrading aquatic organic pollutants efficiently is very important but strongly relied on the design of photocatalysts. Porous graphene could increase photocatalytic performance of ZnO nanoparticles by promoting the effective charge separation of electron-hole pairs if they can be composited. Herein, porous graphene, ZnO nanoparticles and porous graphene/ZnO nanocomposite were prepared by fine tuning of partial combustion, which graphene oxide imperfectly covered by the layered Zn salt was combusted under muffle furnace within few minutes. Resulting ZnO nanoparticles (32–72 nm) are dispersed uniformly on the surface of graphene sheets, the pore sizes of porous graphene are in the range from ∼3 to ∼52 nm. The synthesized porous graphene/ZnO nanocomposite was confirmed to show enhanced efficiency under natural sunlight irradiation compared with pure ZnO nanoparticles. Using porous graphene/ZnO nanocomposite, 100% degradation of methyl orange can be achieved within 150 min. The synergetic effect of photocatalysis and adsorption is main reason for excellent MO degradation of PG/ZnO nanocomposite. This work may offer a new route to accurately prepare porous graphene-based nanocomposite and open a door of their applications.

Hematite nanoparticles (NPs) exist naturally and ubiquitously in soil, and they are always associated with soil organic matter by forming organic-inorganic complexes. In this work, hematite NPs coated with peat humic acid (HAₚₑₐₜ) and soil humic acid (HAₛₒᵢₗ) were chosen as sorbents for hydrophobic organic contaminants (HOCs) to simulate the sorption processes in soil. Ionizable pentachlorophenol (PCP) and non-ionizable phenanthrene (PHE) were selected as representative HOCs. Compared with sorption isotherms of uncoated hematite NPs, the coating of HA onto the surface of hematite NPs substantially increased its sorption affinity for PCP and PHE by about 1-2 orders of magnitude, and the increasing degree was positively correlated to the HA content. These phenomena emphasized the dominant role of HA in the sorption process. The reduced polarity and the introduction of functional groups contributed to the enhanced sorption of HOCs on HA-coated hematite NPs. Furthermore, HAₚₑₐₜ-hematite NPs showed higher sorption affinity for both PCP and PHE than HAₛₒᵢₗ-hematite NPs, which was mainly due to the lower polarity and higher hydrophobicity of HAₚₑₐₜ-hematite NPs. The sorption of PCP and PHE on HA-coated hematite NPs was inhibited obviously with increasing pH values and the pH effect on PCP sorption was more significant than that of PHE, due to the deprotonation of functional groups within adsorbed HA, the loose structure of adsorbed HA and the dissociation of PCP. Our findings elucidated the mechanisms involved in HOCs sorption processes by HA-hematite NPs and provided a theoretical basis for environmental remediation with natural NPs (e.g., hematite NPs).