Plastic pollution has become a global environmental threat, and its potential to affect the bioavailability and toxicity of pharmaceuticals to aquatic organism are of growing concern. However, little ...is known regarding the combined toxicity of micro/nano-plastics and pharmaceuticals to benthic organisms in sediments. Thus, we employed a freshwater benthic bivalve, Corbicula fluminea (C. fluminea), to investigate the individual and co-toxicity of model plastics, microscopic fluorescent polystyrene (PS) (PS nano-plastic (PS-NP) and PS micro-plastic (PS-MP), 80 nm and 6 μm, respectively) and the common antibiotic ciprofloxacin (CIP) in formulated sediments. Our results suggest that oxidative damage and neurotoxicity were confirmed to occur in C. fluminea in all the treatments. The oxidative damage in the digestive glands reduced the clam ability to scavenge free radicals, causing severe tissue damage to the digestive glands of C. fluminea. Filtration rates of C. fluminea were significantly decreased in a concentration-dependent manner across all the treatments, which might be due to the inhibition of acetylcholinesterase activities. Interactions between CIP and micro/nano-plastic were observed, whereby the presence of PS decreased the toxicity of CIP in the digestive glands but aggravated the C. fluminea siphoning inhibition rate in the nano-plastic co-treatments group; in addition, the CIP toxicity to C. fluminea decreased because that the concentration of free dissolved CIP was lowered by micro/nano-PS. Taken together, the current study could contribute greatly to evaluating the ecological risk of CIP and PS in aquatic environments and sheds light on potential issues of food safety caused by both emerging pollutants.
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•PS decreased the toxicity of CIP in digestive glands but aggravated the siphon inhibition.•Oxidative damages and neurotoxicity of C. fluminea were evident across all treatments.•Oxidative damage causes severe tissue damage to the digestive glands of C. fluminea.•Filtration rates of C. fluminea in NP group were significantly lower than those in MP group.
The potential risks from metal-based nanoparticles (NPs) in the environment have increased with the rapidly rising demand for and use of nanoenabled consumer products. Plant’s central roles in ...ecosystem function and food chain integrity ensure intimate contact with water and soil systems, both of which are considered sinks for NPs accumulation. In this review, we document phytotoxicity caused by metal-based NPs exposure at physiological, biochemical, and molecular levels. Although the exact mechanisms of plant defense against nanotoxicity are unclear, several relevant studies have been recently published. Possible detoxification pathways that might enable plant resistance to oxidative stress and facilitate NPs detoxification are reviewed herein. Given the importance of understanding the effects and implications of metal-based NPs on plants, future research should focus on the following: (1) addressing key knowledge gaps in understanding molecular and biochemical responses of plants to NPs stress through global transcriptome, proteome, and metablome assays; (2) designing long-term experiments under field conditions at realistic exposure concentrations to investigate the impact of metal-based NPs on edible crops and the resulting implications to the food chain and to human health; and (3) establishing an impact assessment to evaluate the effects of metal-based NPs on plants with regard to ecosystem structure and function.
Iron oxide nanoparticles (γ-Fe2O3 NPs) have emerged as an innovative and promising method of iron application in agricultural systems. However, the possible toxicity of γ-Fe2O3 NPs and its uptake and ...translocation require further study prior to large-scale field application. In this study, we investigated uptake and distribution of γ-Fe2O3 NPs in corn (Zea mays L.) and its impacts on seed germination, antioxidant enzyme activity, malondialdehyde (MDA) content, and chlorophyll content were determined. 20 mg/L of γ-Fe2O3 NPs significantly promoted root elongation by 11.5%, and increased germination index and vigor index by 27.2% and 39.6%, respectively. However, 50 and 100 mg/L γ-Fe2O3 NPs remarkably decreased root length by 13.5% and 12.5%, respectively. Additionally, evidence for γ-Fe2O3 NPs induced oxidative stress was exclusively found in the root. Exposures of different concentrations of NPs induced notably high levels of MDA in corn roots, and the MDA levels of corn roots treated by γ-Fe2O3 NPs (20–100 mg/L) were 5–7-fold higher than that observed in the control plants. Meanwhile, the chlorophyll contents were decreased by 11.6%, 39.9% and 19.6%, respectively, upon NPs treatment relative to the control group. Images from fluorescence and transmission electron microscopy (TEM) indicated that γ-Fe2O3 NPs could enter plant roots and migrate apoplastically from the epidermis to the endodermis and accumulate the vacuole. Furthermore, we found that NPs mostly existed around the epidermis of root and no translocation of NPs from roots to shoots was observed. Our results will be highly meaningful on understanding the fate and physiological effects of γ-Fe2O3 NPs in plants.
•The lower concentration of γ-Fe2O3 NPs had more positive effects on corn seeding growth.•The higher concentration of γ-Fe2O3 NPs stress induced modulation of antioxidant enzymes and relevant mechanisms were studied.•γ-Fe2O3 NPs mostly existed around epidermis of root and could not translocate from roots to shoots.
Customized Cu
(PO
)
and CuO nanosheets and commercial CuO nanoparticles were investigated for micronutrient delivery and suppression of soybean sudden death syndrome. An ab initio thermodynamics ...approach modelled how material morphology and matrix effects control the nutrient release. Infection reduced the biomass and photosynthesis by 70.3 and 60%, respectively; the foliar application of nanoscale Cu reversed this damage. Disease-induced changes in the antioxidant enzyme activity and fatty acid profile were also alleviated by Cu amendment. The transcription of two dozen defence- and health-related genes correlates a nanoscale Cu-enhanced innate disease response to reduced pathogenicity and increased growth. Cu-based nanosheets exhibited a greater disease suppression than that of CuO nanoparticles due to a greater leaf surface affinity and Cu dissolution, as determined computationally and experimentally. The findings highlight the importance and tunability of nanomaterial properties, such as morphology, composition and dissolution. The early seedling foliar application of nanoscale Cu to modulate nutrition and enhance immunity offers a great potential for sustainable agriculture.
Cation–pi attraction is a major force that determines macromolecular structures and drug-receptor interactions. However, the role of the cation–pi interaction in sorption of fluoroquinolone ...antibiotics by pyrogenic carbonaceous materials (PCMs) has not been addressed. We studied sorption of ciprofloxacin (CIP) on graphite to quantify the contribution of the cation–pi interaction. Through competition experiments, the decreased amount of sorbed CIP by sequential treatment with hexadecane, phenanthrene and benzylamine represents the contribution of hydrophobic, pi-pi and cation–pi interactions, respectively. Benzylamine competed more strongly with CIP than n-hexadecane and phenanthrene, indicating that cation–pi is a major force. Cation–pi interactions accounted for up to 72.6% of the total sorption at an initial CIP concentration of 0.000015 mmol/L. Importantly, species transformation (CIP(0) captures H+ from water to form CIP(+1)) induced by cation-pi interactions was verified both experimentally and theoretically and can be used to explain the environmental behavior of other fluoroquinolone antibiotics and biochemical processes of amino acids that interact with aromatic moieties. Because of the significant role of cation–pi interactions, CIP desorption increased up to 2.32 times when Na+ increased from 0.01 mM to 0.45 mM, which is an environmentally relevant scenario at river estuaries. Hence, behaviors of fluoroquinolone antibiotics that are affected by ionic strength changes need to be carefully evaluated, especially in river estuaries.
Concerns over the potential risks of nanomaterials to ecosystem have been raised, as it is highly possible that nanomaterials could be released to the environment and result in adverse effects on ...living organisms. Carbon dioxide (CO2) is one of the main greenhouse gases. The level of CO2 keeps increasing and subsequently causes a series of environmental problems, especially for agricultural crops. In the present study, we investigated the effects of TiO2 NPs on wheat seedlings cultivated under super-elevated CO2 conditions (5000 mg/L CO2) and under normal CO2 conditions (400 mg/L CO2). Compared to the normal CO2 condition, wheat grown under the elevated CO2 condition showed increases of root biomass and large numbers of lateral roots. Under both CO2 cultivation conditions, the abscisic acid (ABA) content in wheat seedlings increased with increasing concentrations of TiO2 NPs. The indolepropioponic acid (IPA) and jasmonic acid (JA) content notably decreased in plants grown under super-elevated CO2 conditions, while the JA content increased with increasing concentrations of TiO2 NPs. Ti accumulation showed a dose-response manner in both wheat shoots and roots as TiO2 NPs concentrations increased. Additionally, the presence of elevated CO2 significantly promoted Ti accumulation and translocation in wheat treated with certain concentrations of TiO2 NPs. This study will be of benefit to the understanding of the joint effects and physiological mechanism of high-CO2 and nanoparticle to terrestrial plants.
The outstanding commercial application potential of graphene oxide (GO) will inevitably lead to its increasing release into the environment, and then affect the environmental behavior and toxicity of ...conventional pollutants. Interactions between arsenite As (III)/arsenate As (V) with GO and their combined toxicity to Chlorella pyrenoidosa were investigated. Under abiotic conditions, approximately 42% of the adsorbed As (III) was oxidized by GO with simulated sunlight illumination, which was induced by electron-hole pairs on the surface of GO. Co-exposure with GO greatly enhanced the toxicity of As (III, V) to alga. When adding 10 mg/L GO, the 72 h median effect concentration of As (III) and As (V) to C. pyrendoidosa decreased to 12.7 and 9.4 mg/L from 30.1 and 16.3 mg/L in the As alone treatment, respectively. One possible mechanism by which GO enhanced As toxicity could be that GO decreased the phosphate concentration in the algal medium, and then increased the accumulation of As (V) in algae. In addition, transmission electron microscope (TEM) images demonstrated that GO acted as a carrier for As (III) and As (V) transport into the algal cells. Also, GO induced severe oxidative stress, which could have subsequently compromised important detoxification pathways (e.g., As complexation with glutathione, As methylation, and intracellular As efflux) in the algal cells. Our findings highlight the significant impact of GO on the fate and toxicity of As in the aquatic environment.
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•GO could oxidize 42% of the adsorbed As (III) to As (V) under light irradiation.•Co-exposure with GO greatly enhanced the toxicity of As (III, V) to alga.•GO could act as a carrier for As (III) and As (V) transport into the algal cells.•GO induced severe oxidative stress, and inhibited As complexation with glutathione.•GO inhibited As methylation and intracellular As efflux.
The aim of this study was to investigate the phytotoxicity of thin-walled carbon nanotubes (CNTs) to rice (Oryza sativa L.) seedlings. Three different CNTs, including hollow multi-walled carbon ...nanotubes (MWCNTs), Fe-filled carbon nanotubes (Fe-CNTs), and Fe-Co-filled carbon nanotubes (FeCo-CNTs), were evaluated. The CNTs significantly inhibited rice growth by decreasing the concentrations of endogenous plant hormones. The carbon to nitrogen ratio (C:N ratio) significantly increased in rice roots after treatments with CNTs, and all three types of CNTs had the same effects on the C:N ratio. Interestingly, the increase in the C:N ratio in roots was largely because of decreased N content, indicating that the CNTs significantly decreased N assimilation. Analyses of the Fe and Co contents in plant tissues, transmission electron microscope (TEM) observations and energy dispersive X-ray spectroscopy (EDS) analysis proved that the CNTs could penetrate the cell wall and the cell membrane, and then enter the root cells. According to the author's knowledge, this is the first time to study the relationship between carbon nanotubes and carbon nitrogen ratio and plant hormones.
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•Flooding and Cu pollution reduced aromaticity of rhizosphere DOC.•Cu pollution induced more carbohydrate and protein-like species of rhizosphere DOC.•Flooding and Cu pollution ...reduced soil invertase, urease and cellulase activities.•There was a link between enzyme activity and rhizosphere DOC molecular composition.
Dissolved organic carbon (DOC) in rhizosphere soil is critical for multiple geochemical processes. Soils that suffer from heavy metal pollution accompanied by flooding are present worldwide, while little research has explored their effects on rhizosphere DOC structures, especially at the molecular level. Therefore, this study was designed with the aim of improving the understanding of rhizosphere DOC fate in copper (Cu) amended and/or flooded soils. A 180-day laboratory incubation including soils with different Cu levels with and without flooding was conducted. Fourier transform ion cyclotron resonance mass spectrometry analysis showed that the number of formulas detected only in the rhizosphere DOC of flooded and Cu-treated soil was as high as 528–1375. Flooding and Cu pollution reduced molecular weight, aromaticity and compounds containing CHON2 and CHON3 of rhizosphere DOC, but increased its oxidation degree. Furthermore, Cu pollution resulted in DOC with more abundant lignin-, carbohydrate- and protein-like components but less condensed aromatic-like components. Overall, due to Cu pollution and flooding, the rhizosphere DOC pool contained more chemically and biologically labile components. Structural equation modeling indicated that this change in DOC structure was partly explained by soil enzyme activities (decrease in invertase, cellulase, urease activity and the increase in polyphenol oxidase and peroxidase activity). The findings highlighted the ecological risk of Cu pollution and flooding to soil health from the perspective of rhizosphere carbon.
Nanoparticles (NPs) have great potential for use in the fields of biomedicine, building materials, and environmental protection because of their antibacterial properties. However, there are few ...reports regarding the antifungal activities of NPs on plants. In this study, we evaluated the antifungal roles of NPs against
, which is a notorious worldwide fungal pathogen. Three common carbon nanomaterials, multi-walled carbon nanotubes, fullerene, and reduced graphene oxide, and three commercial metal oxidant NPs, copper oxide (CuO) NPs, ferric oxide (Fe
O
) NPs, and titanium oxides (TiO
) NPs, were independently added to water-agar plates at 50 and 200-mg/L concentrations. Detached rose petals were inoculated with spores of
and co-cultured with each of the six nanomaterials. The sizes of the lesions on infected rose petals were measured at 72 h after inoculation, and the growth of fungi on the rose petals was observed by scanning electron microscopy. The six NPs inhibited the growth of
, but different concentrations had different effects: 50 mg/L of fullerene and CuO NPs showed the strongest antifungal properties among the treatments, while 200 mg/L of CuO and Fe
O
showed no significant antifungal activities. Thus, NPs may have antifungal activities that prevent
infections in plants, and they could be used as antifungal agents during the growth and post-harvesting of roses and other flowers.
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