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).

Release of fluoride from Quaternary sediments produces F-contaminated groundwater which threatens the health of millions of people worldwide. Despite the mechanisms of fluoride release from sediments are documented by numerous studies, it remains poorly understood that whether indigenous microbes participate in or not for the formation of F-rich groundwater by releasing fluoride from aquifer sediments. A microcosm-based approach, geochemistry and techniques of microbiology and molecular ecology were conducted together to investigate these mechanisms. Results show that microbes are abundant in high [F] groundwater containing at least 1129 operational taxonomic units (OTUs), and indigenous microbes can have an essential role in the mobilization of fluoride in sediments collected from aquifers in a typical fluorosis area in China. It also shows that for the sediments in this study, fluoride release (ca. 2 mg/L) is coupled with elevated concentrations of Ca (△ = 75 mg/L), Mg (△ = 33 mg/L), Al (△ = 0.2 mg/L) and Mn (△ = 1.4 mg/L). This suggests that the fluoride may source from the dissolution of F-bearing carbonate minerals and/or Al-Mn hydroxides in a local acidic environment. The findings provide additional insights into the biogeochemical circulation of fluoride in natural environment, especially in groundwater system and the development of effective strategies for the management of F-contaminated groundwater worldwide.

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.

Graphene oxide (GO) has been demonstrated to be key component for diverse applications. However, their potential environmental reactivity, fate and risk have not been fully evaluated to date. In this study, we investigated the photochemical reactivity of four types of GO with different oxidation degrees in aqueous environment, and their related toxicity to two bacterial models Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) was further compared. After UV-irradiation, a large amount of oxygen functional groups on GO were reduced and the electronic conjugations within GO were restored as indicated by UV–visible absorption spectra, X-ray photoelectron spectroscopy and Raman spectroscopy analysis. Moreover, the higher the oxidation degree of the pristine GO was, the more obvious of the photo-transformation changes were. In order to further reveal the photochemical reactivity mechanisms, the reactive oxygen species (ROS) generation of GO was monitored. The quantity of ROS including singlet oxygen (1O2), superoxide anions (O2·-), and hydroxyl radicals (·OH) increased with increasing oxidation degree of GO, which was in accordance with the previous characterization results. Scanning electron microscopy and cell growth analyses of E. coli and S. aureus showed that the photochemical transformation enhanced the toxicity of GO, which might be due to an increase in functional group density. The higher conductivity of the reduced graphene oxide (RGO) was responsible for its stronger toxicity than GO through membrane damage and oxidative stress to bacteria. This study revealed that the oxidation degrees play important roles in photochemical transformation and the resulting toxicity of GO, which is helpful for understanding the environmental behaviors and risks of GO in aquatic environments.

Iron fertilizers are worthy to be studied due to alleviate the Fe deficiency. Different forms of iron oxide nanoparticles are selected to better understand possible particle applications as an Fe source for crop plants. In this study, we assessed the different effects of γ-Fe2O3 and Fe3O4 NPs on the physiology and fruit quality of muskmelon plants in a pot experiment for five weeks. Results showed that no increased iron content was found under NPs treatment in root, stem, leaf and fruit, except 400 mg/L Fe3O4 NPs had a higher iron content in muskmelon root. With the extension of NPs exposure, both γ-Fe2O3 and Fe3O4 NPs began to promote plant growth. In addition, γ-Fe2O3 and Fe3O4 NPs could increase chlorophyll content at a certain stage of exposure. Happily, 200 mg/L γ-Fe2O3 NPs and 100, 200 mg/L Fe3O4 NPs significantly increased fruit weight of muskmelon by 9.1%, 9.4% and 11.5%. It is noteworthy that both γ-Fe2O3 and Fe3O4 NPs caused positive effects on VC content, particularly 100 mg/L Fe3O4 NPs increased the VC content by 46.95%. To the best of our knowledge, little research has been done on the effect of nanoparticles on the whole physiological cycle and fruit quality of melon. The assessment of physiology and fruit quality of muskmelon plants in vitro upon γ-Fe2O3 and Fe3O4 NPs exposure could lay a foundation for NPs potential impact at every growth period of muskmelon plants.

Severe pollution caused by atmospheric particulate matter (PM) has become a global environmental issue. Samples of atmospheric PM were collected before and during the Chinese Spring Festival in Xiamen, a coastal city in Southeast China, to investigate their chemical characteristics, sources, and formation mechanisms. The results indicated that PM₂.₅ mass concentrations comprised 53.60% and 56.31% of total suspended particulates before and during the Spring Festival, respectively. Due to the halt of factory production and construction and the reduction of vehicle flow during the Spring Festival, the concentrations of organic carbon, elemental carbon and water soluble ions in PM₂.₅ decreased by 78.56%, 84.19% and 27.53%, respectively, compared with those before the Spring Festival. However, the concentrations of K⁺, Mg²⁺, Al, Sr, and Ba increased by 3121.76%, 571.67%, 183.71%, 180.15%, and 137.58%, respectively, resulting from the display of fireworks and firecrackers during the Spring Festival. Analysis of backward air mass trajectory indicated that the concentrations of PM₂.₅ and its components were dominated by local pollution sources before and during the Spring Festival. The relationships between meteorological conditions and pollutant concentrations showed that the secondary organic aerosol was generated from the heterogeneous reaction before the Spring Festival, and the secondary inorganic aerosol was formed by the photochemical reaction during the Spring Festival.

The increase in ambient fine dust particles (FDP) due to urbanization and industrialization has been identified as a major contributor to air pollution. It has become a serious issue that threatens human health because it causes respiratory diseases and skin aging. In the present study, the protective effect of the green tea catechin, (−)-epigallocatechin gallate (EGCG), against FDP (ERM-CZ100)-stimulated skin aging in human dermal fibroblasts (HDFs) was investigated. The results demonstrate that EGCG significantly and dose-dependently scavenged intracellular reactive oxygen species (ROS) in and increased the viability of FDP-stimulated HDFs. In addition, EGCG dose-dependently recovered collagen synthesis and inhibited intracellular elastase and collagenase activities. Moreover, EGCG decreased the expression of human matrix metalloproteinases (MMPs) via regulation of nuclear factor kappa B (NF-κB), activator protein 1 (AP-1), and mitogen-activated protein kinases (MAPKs) signaling pathways in FDP-stimulated HDFs. This study suggests that EGCG is a potential anti-aging candidate that can be used for FDP-induced skin aging as a therapeutic agent itself or as an ingredient in pharmaceutical and cosmeceutical products.

The 6:2 chlorinated polyfluoroalkyl ether sulfonic acids (6:2 Cl-PFAES), 2,3,3,3-tetrafluoro-2-(1,1,2,2,3,3,3-heptafluoropropoxy)-propanoic acid (HFPO-DA) and perfluoroethylcyclohexane sulfonate (PFECHS) are emerging per- and polyfluoroalkyl substances (PFASs) that are being applied to replace phased-out PFASs, which have high persistency, high bioaccumulation potential and high toxicity. Recently, these emerging PFASs were observed in estuary and marine areas with a pollution level of ng/L. In this study, three levels (10 ng L⁻¹, 100 ng L⁻¹ and 1000 ng L⁻¹) for these PFASs were selected to investigate the response of marine Chlorella sp. to 14 days of exposure. The growth of Chlorella sp. was significantly inhibited by each PFAS over time. Treatments with 1000 ng/L exposure caused the most severe reduction in growth for each PFAS treatment. For the first half of the experimental period (from Day 0 to Day 6), the influence of each PFAS was not significant (p > 0.05). However, treatments with all concentrations of 6:2 Cl-PFAES, HFPO-DA and 1000 ng L⁻¹ PFECHS significantly reduced the growth of Chlorella sp. from Day 8. The superoxide dismutase (SOD) activities in Chlorella sp. were significantly increased (p < 0.05) when exposed to 6:2 Cl-PFAES, HFPO-DA and PFECHS. The catalase (CAT) and peroxidase (POD) activities in Chlorella sp. were significantly inhibited (p < 0.05) by each PFAS. The glutathione (GSH) contents in Chlorella sp. were significantly increased by each PFAS. However, the increases in GSH concentration in Chlorella sp. were low. The inhibition of algal growth was primarily due to the reduction of the activities of CAT and POD. PFECHS had the lowest toxicity among the three PFASs, and it induced less oxidized damage to Chlorella sp. In conclusion, as alternatives to phased-out PFASs, the emerging PFASs are not safe in aquatic environment, and attention should be paid to the management and restriction of these emerging PFASs.

Deoxynivalenol (DON) frequently detected in a wide range of foods and feeds, inducing cytotoxicity to animals and humans. To investigate the underlying mechanism of DON-induced apoptosis and inflammation in porcine small intestinal epithelium, intestinal porcine epithelial cells (IPEC-J2 cells) were chosen as objects, and were treated by different concentrations (0 μg/mL, 0.2 μg/mL, 0.5 μg/mL, 1.0 μg/mL, 2.0 μg/mL, 4.0 μg/mL, 6.0 μg/mL) of DON. The results showed that DON induced cytotoxicity of IPEC-J2 cells in a dose-dependent manner, which is demonstrated by decreasing cell viability. Compared with the control group, DON treatment increased the expressions of genes associated with inflammation and apoptosis, such as interleukin-1 beta (IL-1β), cyclooxgenase-2 (COX-2), interleukin-6 (IL-6), tumour necrosis factor-alpha (TNF-α), caspase-3, caspase-8, caspase-9, and decreased the cell anti-oxidative status. Protein immunofluorescence showed increased expression of caspase-3, nuclear factor kB (NF-κB) and phosphorylated NF-κB in IPEC-J2 cells. DON increased the content of intracellular reactive oxygen species (ROS) of IPEC-J2 cells. N-Acetyl-L-cysteine (NAC), a commonly used antioxidant, blocked DON-induced ROS generation, alleviated the DON-induced apoptosis and inflammation. These results suggested that DON-induced impairment of IPEC-J2 cells is possibly due to increased ROS production, and expressions of genes and proteins associated with apoptosis and inflammation.

Because of its analgesic properties, acetaminophen (AAP) is widely used to relieve headache. AAP is generally considered safe for humans, but its effects on aquatic organisms are not well known. Here, we have hypothesis that effects of AAP on aquatic organisms would be environmental temperature dependent, because their physiological function depend on the temperature. To test this hypothesis, we used medaka (Oryzias latipes) as a model, because they can live at a wide range of temperatures (0–40 °C). We exposed medaka larvae to 0 (control), 50, or 150 mg/L of AAP at 15, 25 (optimal temperature), or 30 °C for 4 days. Egg yolk absorption was accelerated with raising temperature at any AAP dose. AAP exposure did not have biologically significant effects on survival ratio and body length of larvae at any tested temperature or dose, but heart rate decreased as the dose of AAP and environmental temperature increased. In addition, as the temperature increased, amount of ATP in individual larvae increased in control group, but decreased in AAP exposed group. Subsequently, exposure to 150 mg/L of AAP at 30 °C decreased the number of red blood cells in the gills; we used 150 mg/L of AAP in subsequent hematological and histological analyses. Hematological analysis showed that rising temperature increased the proportion of morphologically abnormal red blood cells in AAP-exposed larvae, suggesting that AAP induced anemia-like signs in larvae. Histological observation of the kidney, which is a hematopoietic organ in fish, revealed no abnormalities. However, in the liver, which is responsible for drug metabolism, the proportion of vacuoles increased with increasing temperature. Although the exposure concentration we tested was higher than environmentally relevant concentrations, our data indicated that rising temperature enhances the toxicity of AAP to medaka larvae, suggesting an ecological risk of AAP due to global warming.