Photocatalysis is a promising method to eliminate hexavalent uranium (U(Ⅵ)) and recycle it from wastewater. However, most of researched photocatalysts are metal-contained, inactive in visible light, and inconvenient to recycle, which unfortunately impedes the further utilization of photocatalytic technology in U(Ⅵ) pollution treatment. Herein, g-C₃N₄ isotype heterojunction with interpenetrated tri-s-triazine structure (ipCN) was prepared by inserting urea into the interlayer of tri-s-triazine planes of thiourea-derived g-C₃N₄ and in-site thermal treating. The synthesized nanocomposites were used to convert soluble U(Ⅵ) ions into U(Ⅳ) sediment under visible light. Experimental and characterization results reveal that ipCN possess larger BET surface area, more negative-charged surface, higher U(Ⅵ) adsorption capability, and more efficient mass diffusion and charges transfer properties. With these excellent characteristics, nearly 98% U(Ⅵ) could be removed within 20 min over ipCN₅:₁ and 92% photoreduction efficiency could also be kept after 7 cycle uses, which were equal to or even superior than most reported metal-based photocatalysts. It is also proven that the configuration of U(Ⅵ) and photogenerated ·O₂⁻ play a significant role in the photocatalytic U(Ⅵ) reduction process, with (UO₂)ₓ(OH)y²ˣ⁻ʸ are more prone to be adsorbed and the photoinduced process of ·O₂⁻ will steal electrons from photocatalysts. Furthermore, with the self-generated ·O₂⁻ and H₂O₂, a green and facile regeneration process of photocatalysts was proposed This work provides a promising scheme to extract U(Ⅵ) from the perspectives of photocatalysts exploitation, photocatalytic reduction, and photocatalysts regeneration, which is meaningful for the sustainable U(Ⅵ) resource recovery and U(Ⅵ) pollution purification.

The ongoing development of nanotechnology has raised concerns regarding the potential risk of nanoparticles (NPs) to the environment, particularly aquatic ecosystems. A relevant aspect that drives NP toxicity is represented by the abiotic and biotic processes occurring in natural matrices that modify NP properties, ultimately affecting their interactions with biological targets. Therefore, the objective of this study was to perform an ecotoxicological evaluation of CeO₂NPs with different surface modifications representative of NP bio-interactions with molecules naturally occurring in the water environment, to identify the role of biomolecule coatings on nanoceria toxicity to aquatic organisms. Ad hoc synthesis of CeO₂NPs with different coating agents, such as Alginate and Chitosan, was performed. The ecotoxicity of the coated CeO₂NPs was assessed on the marine bacteria Aliivibrio fischeri, through the Microtox® assay, and with the freshwater crustacean Daphnia magna. Daphnids at the age of 8 days were exposed for 48 h, and several toxicity endpoints were evaluated, from the molecular level to the entire organism. Specifically, we applied a suite of biomarkers of oxidative stress and neurotoxicity and assessed the effects on behaviour through the evaluation of swimming performance. The different coatings affected the hydrodynamic behaviour and colloidal stability of the CeO₂NPs in exposure media. In tap water, NPs coated with Chitosan derivative were more stable, while the coating with Alginate enhanced the aggregation and sedimentation rate. The coatings also significantly influenced the toxic effects of CeO₂NPs. Specifically, in D. magna the CeO₂NPs coated with Alginate triggered oxidative stress, while behavioural assays showed that CeO₂NPs coated with Chitosan induced hyperactivity. Our findings emphasize the role of environmental modification in determining the NP effects on aquatic organisms.

The accumulation of cadmium (Cd) in rice grains is closely associated with the content of mineral nutrients and amino acid metabolism, but the causal link among them is unclear. Profiles of amino acids (AAs) and quantities of essential nutrients in grains from early and late rice cultivars grown at four sites with different Cd levels were analyzed in the present study. Hazard quotients (HQs) for consumers by intake of rice from late cultivars were much higher than that from early cultivars at sites with soil Cd content of 0.25, 0.61 and 0.84 mg kg⁻¹. Cadmium accumulation in grains resulted in a sharp reduction of total essential AAs and non-essential AAs in both early and late rice cultivars. High-Cd-accumulating (HCA) cultivars had significantly higher level of glutamate (Glu) than low-Cd-accumulating (LCA) cultivars when rice Cd content was less than 0.20 mg kg⁻¹. However, Glu level in grains dramatically declined with the accumulation of Cd, which subsequently leaded to the reduction of other AAs. Cadmium content was well predicted by five amino acids (i.e., Glu, Alanine, Phenylalanine, Glycine and Threonine) or four essential elements (Ca, Fe, Mn and Zn) when rice Cd was less than 0.80 mg kg⁻¹. Amino acids played more important roles than nutrients in Cd accumulation. When Cd content was in the range of 0.40–1.16 mg kg⁻¹, the Mn content in rice increased significantly with the increase of Cd content, while the Glu content dropped down synchronously. Remarkably, the ratio between Mn and Glu displayed the highest direct path coefficient on Cd accumulation than any single cation or amino acid. These results indicate that high capacity in synthesizing Glu and concentrating Mn is the determinant factor for Cd accumulation in rice grains, and abundant Glu in aleurone layer may alleviate Cd toxicity by forming Glu-Cd complex.

Atmospheric heavy metal contamination is becoming a serious threat to environmental and human health in Chinese megacities. This study evaluated the concentrations of arsenic (As), cadmium (Cd), copper (Cu), lead (Pb) and zinc (Zn) and Pb isotopic compositions in herbarium and native bryophytes collected from Guangzhou from 1932 to 2018. Relatively low mean metal concentrations were measured for bryophytes collected in the 1930s. The highest mean concentrations of Cd (0.72 ± 0.32 mg/kg), Cu (28.1 ± 9.8 mg/kg), Pb (125.9 ± 62.4 mg/kg) and Zn (273 ± 130 mg/kg) were found in the bryophytes from 1979 to 2000, following the commencement of the Reform and Opening-Up Program in 1978. The mean Pb concentrations (74.7 ± 6.3 mg/kg) decreased sharply from 2001 onwards, following the cessation of leaded petrol across the Chinese mainland in 2000. However, these values are still higher than those in 1950–1978, corresponding to a significant increase in atmospheric Pb emissions from coal combustion, nonferrous metal smelting and motor vehicle petrol consumption in China in the 2000s. The lead isotopic ratios of bryophyte archives (²⁰⁶Pb/²⁰⁷Pb 1.141–1.229, ²⁰⁸Pb/²⁰⁷Pb 2.376–2.482) indicate that lithogenic input and anthropogenic input arising from leaded petrol and industrial emissions have been the main sources of atmospheric heavy metal deposition in the city of Guangzhou over the past 85 years. Herbarium bryophyte can be utilised to reconstruct temporal and spatial shifts in atmospheric heavy metal deposition to better understand and manage the current air quality in Chinese megacities.

Per- and polyfluoroalkyl substances (PFASs) are used in specialty/functional textiles to impart oil, water, and stain repellency. Little is known, however, with regard to the occurrence of PFASs in textiles including infant clothing. In this study, 13 perfluoroalkyl acids (PFAAs), comprising four perfluoroalkyl sulfonic acids (PFSAs; C4–C10) and nine perfluoroalkyl carboxylic acids (PFCAs; C4–C12) were determined in 160 textile samples collected from the United States. Two extraction methods, one involving a simple solvent extraction (i.e., before oxidation) and the other with an oxidative treatment (i.e., after oxidation) of textile extracts, were used. The sum concentrations of 13 PFAAs (i.e., ∑PFAA) in textile extracts before oxidation ranged from <LOD to 63.7 μg/m² (<LOD–285 ng/g), with a mean value of 3.18 μg/m² (14.2 ng/g). ∑PFAA concentrations were the highest in flame retarded textiles (n = 23; mean: 13.3 μg/m²; 59.4 ng/g), followed by water repellent textiles (n = 56; 2.88 μg/m²; 12.9 ng/g) and infant clothes (n = 81; 0.521 μg/m²; 2.33 ng/g). C4–C10 PFCAs accounted for at least three-quarters of the ∑PFAA content in our textile samples. Textile extracts analyzed after oxidative treatment exhibited ∑PFAA concentrations 10-fold higher than those in extracts analyzed prior to oxidation, which suggested that PFAA precursors are used in textiles. Precursors that generated C4–C5 PFCAs, upon oxidation, were more prevalent than those that yielded PFOA. The calculated dermal exposure doses in infants of PFAAs present in clothes were at least 1–2 orders of magnitude below the reference doses proposed by the United States Environmental Protection Agency. This is the first time that the oxidative treatment was applied in the analysis of PFASs in textiles, and our results suggest the existence of PFCA precursors in textiles.

Characterizing Black Carbon (BC) at regional background areas is important for better understanding its impact on climate forcing and health effects. The variability and sources of Equivalent Black Carbon (EBC) in PM₁₀ (atmospheric particles with aerodynamic diameter smaller than 10 μm) have been investigated during a 5-year measurement period at the National Atmospheric Observatory Košetice (NAOK), Czech Republic. Ground based measurements were performed from September 2012 to December 2017 with a 7-wavelength aethalometer (AE31, Magee Scientific). The contributions of fossil fuel (EBCff) and biomass burning (EBCbb) were estimated using the aethalometer model. Seasonal, diurnal and weekly variations of EBC were observed that can be related to the sources fluctuations and transport characteristic of pollutants predominantly associated with regional air masses recirculating over the Czech Republic and neighboring countries. The absorption Ångström exponent (α-value) estimated in summer (1.1 ± 0.2) was consistent with reported value for traffic, while the mean highest value (1.5 ± 0.2) was observed in winter due to increased EBCbb accounting for about 50% of the total EBC. This result is in agreement with the strong correlation between EBCbb and biomass burning tracers (levoglucosan and mannosan) in winter. During this season, the concentrations of EBCbb and Delta-C (proxy for biomass burning) reached a maximum in the evening when increasing emissions of wood burning in domestic heating devices (woodstoves/heating system) is expected, especially during the weekend. The diurnal profile of EBCff displays a typical morning peak during the morning traffic rush hour and shows a decreasing concentration during weekends due to lower the traffic emission.

Mercury (Hg) concentrations in Tilefish (Lopholatilus chamaeleonticeps) have been reported to be one of the highest of all fish species, resulting in advisories that, historically, have recommended zero consumption. The current study assesses Hg bioaccumulation in Tilefish targeted by the commercial fisheries operating off the coast of South Carolina, USA. We provide results for an under-sampled region and explore how life history potentially impacts Hg uptake in Tilefish. Mercury concentration in Tilefish muscle tissue ranged from 0.10 to 0.99 ppm, with a mean of 0.23 ppm (n = 63). The majority of Tilefish samples (95%) were within the “Good Choices” range for consuming at least one serving per week, with 62% being within the range considered best for eating two meals a week”, per suggestion by the US EPA and US FDA (2017). The present study of Tilefish from the western Atlantic further substantiates the importance of monitoring Hg in commercial fish species regionally.

Land use/Land cover (LULC) associated with Cryptosporidium sp. and Giardia sp. quantification and distribution can provide identification of the environmental circulation patterns of these parasites. The aim of this research was to relate the occurrence and circulation of these parasites to the LULC watershed with poor sanitation infrastructure and livestock as important economic activity. The study involved 11 municipalities in the state of São Paulo, located in southeastern Brazil. Sampling was carried out at the catchment sites of each water supply on a monthly basis, starting in December 2014 and lasting until November 2015, totalizing 128 samples. Protozoans were quantified according to the 1623.1 US. EPA Method. For watershed delimitation, the hydrographic network was extracted from the hydrology tool of ArcGIS 10.1. The frequency of occurrence of these pathogens and the high concentrations were evidenced in the municipality with the largest urban area (16.2%) and intense livestock activity (39%) near the catchment site. The municipality that showed the lowest frequency of occurrence presented the smallest urban area (0.87%) and absence of livestock activity near the catchment site. The high concentration of pathogens suggests a correlation between the impact on water supply networks and river basin degradation caused by urban activity and livestock.

This work aimed to investigate the metal accumulation characteristics as well as biogeochemical changes in the rhizosphere and root foraging strategies of this plant species. Previous reports suggested that Noccaea rotundifolia ssp. cepaeifolia is a Zn, Cd and Pb hyperaccumulator. We used hydroponic, rhizobox and split-pot experiments for studying metal accumulation and related rhizosphere processes. Although this species accumulated up to 1250 mg Pb kg⁻¹ and 27,000 mg Zn kg⁻¹ in shoots, translocation factors <1 do not meet the hyperaccumulation criteria. Substantial increases in Ca(NO₃)₂-extractable metals in the N. rotundifolia rhizosphere of a metal-spiked soil can be explained by proton release from N. rotundifolia roots to maintain the charge balance during excessive metal uptake; this was not observed for the non-spiked, moderately contaminated control soil. Specific rhizosphere mechanisms targeting the alleviation of metal toxicity in N. rotundifolia rhizosphere were not detected. Generally, N. rotundifolia had larger total root and shoot mass in soils with heterogeneous distribution of Zn and Pb relative to homogeneous treatments, associated with less root mass placed in metal-enriched patches. However, the avoidance strategy was not reflected by low shoot metal concentrations. Metal accumulation rates and translocation factors do not meet the criteria for hyperaccumulation. Changes of pH and DOC in N. rotundifolia rhizosphere were apparently not involved in targeted immobilisation or detoxification of Pb, Zn and Cd. Avoidance of metal-rich patches in soil is a major tolerance strategy of N. rotundifolia.

Microplastics are ubiquitous in marine environments. Sediments and marine organisms are recognized as the carriers and final destinations of microplastics. However, research on the concentration and abundance of microplastics in deep-sea sediments and organisms is limited. In this study, samples of sediments and organisms were collected from deep-sea locations of the western Pacific Ocean, with the depth ranging from 4601 m to 5732 m. Microplastics were extracted from the samples and analyzed by micro-Fourier-transform infrared spectroscopy. The average abundance of microplastics in the sediments was 240 items per kg dry weight of sediment. The microplastics were predominantly fibrous in shape (52.5%), blue in color (45.0%), and less than 1 mm in size (90.0%). The most commonly detected polymers were poly(propylene-ethylene) copolymer (40.0%) and polyethylene terephthalate (27.5%). The concentrations of polychlorinated biphenyls (PCBs), which are representatives of persistent organic pollutants, in the pore water of sediment samples were also investigated. A significant correlation between the distribution of microplastics and the PCB concentrations in sediments was found (P = 0.016). Microplastics were also detected in deep-sea organisms (i.e., Crinoidea, Pheronematidae, Ophiuroidea, and Gammaridea) in the sampling region, with an abundance of 0–3 items per individual biological sample. This assessment of microplastics in deep-sea sediments and benthic organisms of the western Pacific Ocean confirms that microplastic pollution exists in the deep-sea ecosystems of this region.