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The proven high carcinogenicity to humans and high destructive force to the environment determine the extreme urgency of eliminating hypertoxic Cr(VI) in water bodies. Herein, a route of room temperature synthesis and secondary grafting was proposed to fabricate graphene oxide-based nanoadsorbent co-functionalized with polydopamine and branched polyethyleneimine (GOPP) to remove Cr(VI). The flexible decoration of polydopamine and polyethyleneimine on GO flakes could gradually enhance the amount of N-containing functional groups and realize selective removal of Cr(VI) with the maximum experimental adsorption capacity of 564.7 mg/g, displaying a significantly high separation factor against alkali metal, alkaline earth metal, and other transition metal ions. Various combination mechanisms, such as electrostatic attraction, reduction, complexation, and hydrogen bonding, were demonstrated to be involved in the adsorption process of Cr(VI) by XPS, ESP, and DFT calculations. And the interaction energies of the five protonated configurations of primary amine, tertiary amine, secondary amine, imine, and secondary amine on the ring with HCrO 4 − were: −22.66, −12.08, −24.92, −24.26, −27.64 kcal/mol. In the actual industrial wastewater study, a Cr(VI) removal rate of 85.8% was realized. This work provided a viable idea for the elimination of Cr(VI) and was expected to be applied in the field of wastewater treatment. The hypertoxic Cr (VI) poses a serious hazard to humans and the environment. Herein, GOPP were synthesized and applied to the adsorption process of Cr (VI), aiming to achieve effective control of Cr (VI) pollution in actual fluids. [Display omitted] • The flexible decoration of PDA and PEI could gradually enhance N content. • The protonation order of the five N-containing sites were revealed. • The interaction energies of the five configurations with HCrO 4 − were researched. • Imines and secondary amines play important roles in the adsorption of Cr(VI). • The GOPP exhibited 564.7 mg/g adsorption capacity towards Cr(VI). [ABSTRACT FROM AUTHOR]

The antibiotics released by human and animals end up in the environmental sinks like soil and water to cause contamination and induce resistance in the microflora. The knowledge of fate and behavior of antibiotics in diverse geographical, climatological, and physicochemical is limited. Therefore, present study investigated the spatial distribution of antibiotics and their relationship with various factors and the source-sink relationship between soil and poultry manure. This was achieved by employing spatially constrained hierarchical clustering, global and local spatial autocorrelation, and spatial regression techniques. Most of the antibiotics co-occurred in both soil and poultry manure matrices, however antibiotic concentration in soil (1.20 μg kg−1 < antibiotics ≤21.38 μg kg−1) was lower than that in the poultry manure (7.05 μg kg−1< antibiotics ≤60.2 μg kg−1). Majority of the antibiotics showed spatial independence in both poultry manure and soil, except for sulfadiazine, sulfanilamide and sulfapyridine with Moran's I > − 0.111. Local indicator of spatial association indicated localized spatial clustering and outlier behavior of antibiotics. The underlying reasons for spatial heterogeneity of antibiotics resolved by spatial regression models indicated elevation, S%, C%, pH and mean annual temperature as the major factors. The influence of antibiotic concentration in poultry manure as a source was significant but marginal compared to the other predictors of spatial heterogeneity. [Display omitted] • Antibiotic residues co-occurred in both soil and poultry manure matrices. • Majority of antibiotic were distributed independent of spatial contiguity. • Localized spatial clusters and outliers existed among antibiotics. • Geographical, physicochemical, and meteorological factors influence spatial heterogeneity. [ABSTRACT FROM AUTHOR]

As a widely produced and used antibiotic, tetracycline (TC) has been frequently found in rivers, soil and drinking water. In this study, the degradation of TC was investigated by UV/Fe3+/persulfate (PS) coupled process. The degradation behavior was well fitted with pseudo-first-order model. Hydroxyl radicals (·OH), sulfate radicals (SO 4 −·) and superoxide radical (O 2 −·) were identified as the primary reactive oxygen species (ROS) in UV/Fe3+/PS process, the contribution to TC degradation were found to be 41.94%, 33.94% and 17.44% at pH 3.0, respectively. Fe(IV) generated from the system also played a crucial role in TC removal. The effects of process parameters (PS/Fe3+ dosages, pH, humic acid, Cl−, HCO 3 −, NO 3 − and CO 3 2−) on degradation were investigated. It was found that the degradation of TC was highly pH-dependent, and the optimal performance was obtained at pH 3.0. Except for Cl−, the presence of HA, HCO 3 −, NO 3 − and CO 3 2− inhibited TC degradation. The possible transformation pathway involving the hydroxylation, N -demethylation, hydrogenation and dehydroxylation was proposed. Furthermore, the toxicity and mutagenicity of TC and transformation products (TPs) were estimated using ECOSAR and TEST softwares, demonstrating that the toxicity level of most TPs was lower/equal to their precursors. The evaluation of DBPs showed that UV/Fe3+/PS process could reduce the potential of DBPs formation, especially for TCAA and TCM. Microbial community composition was analyzed by 16 S rDNA sequencing, and the relative abundance of ARG-carrying opportunistic pathogens was significantly declined after UV/Fe3+/PS treatment. In general, this study provides an economical, efficient and safe strategy for TC removal. [Display omitted] • UV/Fe3+/persulfate combined process exhibited favorable performance for TC degradation. • OH· is the dominant radical to TC removal, while Fe(IV) also functioned a crucial role. • UV/Fe3+/persulfate treatment decreased the formation potential of DBPs after chlorination. • Most of transformation products were less toxic than TC itself. • Bacterial community analysis showed that UV/Fe3+/persulfate presented a certain control effect on ARB and ARG. [ABSTRACT FROM AUTHOR]

Traditional high-throughput methods for identification of chemicals with liver tumor promotion potentials are based on established cancer cell lines, and rapid and cost-effective high-throughput screening assays in whole organisms are presently lacking. In this study, a transgenic zebrafish liver cancer model was employed to develop a method that could be used to identify chemicals with liver tumor promotion effect quickly and accurately. The method consisted of three parts, including exposure preparation, exposure process and image acquisition. In brief, after chemical exposure for 7 days, 96-well plate exposure system for zebrafish larvae was assessed by microplate reader. Then, the liver cancer promoting potential chemicals were evaluated by field area and field average intensity of fluorescence. The results were further validated by conducting histopathological examination. Our data demonstrated that the high-throughput screening assay developed in this study was reproducible and could be used to rapidly screen chemicals with liver tumor promoting potentials by using tris-(2-chloropropyl)-phosphate (TDCIPP) as a positive control. Furthermore, some other positive chemicals found in previous studies and environmental compounds were assessed using the established method. Results indicated that 86.7% of the positive chemicals and five environmental compounds out of seventeen compounds could enhance liver tumor progression. [Display omitted] • A high-throughput assay was developed to identify liver tumor promoting chemicals. • The method developed was reproducible and accurate. • The results were validated by histopathological examination. • Some environmental pollutants were found to have liver tumor promoting potential. [ABSTRACT FROM AUTHOR]

The accumulation of trace elements in rice, such as antimony (Sb), has drawn special attention owing to the potential increased risk to human health. However, the effects of two common irrigation methods, alternate wetting and drying and continuous flooding, on Sb behaviors and subsequent accumulation in rice is unclear. In this study a pot experiment with various Sb additions (0, 50, 200, 1000 mg Sb kg−1) was carried out with these two irrigation methods in two contrasting paddy soils (an Anthrosol and a Ferralic Cambisol). The dynamics of Sb in soil porewater indicated that continuous flooding generally immobilized more Sb than alternate wetting and drying, concomitant with a pronounced reduction of Sb(V) in porewater. However, a higher phytoavailable fraction of Sb was observed under continuous flooding. The content of Sb in the rice plant decreased in the order of root > shoot > husk > grain, and continuous flooding facilitated Sb accumulation in rice root and shoot as compared with alternate wetting and drying. The differences of Sb content in root, shoot, and husk between the two irrigation methods was smaller in aboveground parts, and almost no difference in Sb was observed in grain between the two methods. The findings of this study facilitates the understanding of Sb speciation and behavior in soils with these common yet different water management regimes. [Display omitted] • Continuous soil flooding decreased Sb in porewater with pronounced Sb(V) reduction. • Continuous soil flooding increased phytoavailable Sb and total Sb in root and shoot. • Sb in grain was below acceptable limit and not affected by two water treatments. [ABSTRACT FROM AUTHOR]

The mutual interaction of a microalga Chlorella vulgaris with four antibiotics viz. sulfamethoxazole (SMX), trimethoprim (TMP), azithromycin (AZI), and levofloxacin (LEV) individually and in mixture was studied in batch culture. SMX, TMP, and LEV stimulated algal growth, while AZI inhibited its growth. The Combination Index (CI)-isobologram indicated antagonism of the antibiotic mixture on the growth of C. vulgaris. Higher removal efficiency was observed in the mixed antibiotic than in the single antibiotic batch cultures. Biodegradation was the main antibiotic removal mechanism with a similar antibiotic biosorption pattern in single and mix antibiotic cultures. Scanning electron microscopy and Fourier transform infrared spectrophotometry showed minor biochemical alterations on algal cells surface and a stable algal population. Monod kinetics model was successfully applied to understand the growth with respect to the removal efficiency of C. vulgaris in single and mix antibiotic batch cultures. Results indicated relatively higher specific growth rate in the mix antibiotic batch culture with removal efficiency in the order of SMX > LEV > TMP > AZI. In total, 46 metabolites with 18 novel ones of the four antibiotics were identified by using high-resolution mass spectrometry based on the suspect screening approach to propose the potential transformation pathways. Most of the transformation products demonstrated lower toxicity than their respective parents. These findings implied that C. vulgaris could be an outstanding candidate for advanced treatment of antibiotic removal in wastewater. [Display omitted] • Antibiotics stimulated the growth of Chlorella vulgaris. • Antibiotic removal by C. vulgaris was enhanced in mixed antibiotic culture. • C. vulgaris degradative affinity followed the antibiotic stimulative effect order. • Biodegradation pathways were proposed based on identified transformation products. [ABSTRACT FROM AUTHOR]

This study explored the combined effects of titanium dioxide nanoparticles (nano-TiO 2) and triphenyl phosphate (TPhP) on the neurodevelopment of zebrafish larvae as well as the underlying mechanisms. With this regard, zebrafish embryos were exposed to nano-TiO 2 of 100 μg·L−1, TPhP of 0, 8, 24, 72, and 144 μg·L−1, or their combinations until 120 h post-fertilization (hpf). Results indicated 100 μg·L−1 nano-TiO 2 alone to be nontoxic to zebrafish larvae. However, obvious developmental toxicity manifested as inhibition of surviving rate, heart rate and body length as well as increased malformation was observed in the higher concentrations of TPhP (72 and 144 μg·L−1) alone and the co-exposure groups. Additionally, results suggested that nano-TiO 2 significantly enhanced the bioaccumulation of TPhP in zebtafish larvae, and thus aggravated the abnormities of spontaneous movement and swimming behavior in zebrafish larvae induced by TPhP. Nano-TiO 2 also exacerbated the TPhP-induced inhibition of the axonal growth on the secondary motor neuron, and aggravated the TPhP-induced decrease on expressions of neuron-specific green fluorescent protein (GFP) and neuronal marker genes (ngn1 and elavl3). Further, the content of neurotransmitter serotonin was not altered by TPhP alone exposure, but was decreased significantly in the co-exposure group of 144 μg·L−1 TPhP and nano-TiO 2. Our data indicated that nano-TiO 2 might aggravate the neuron abnormities and serotonin system dysfunction by enhancing the TPhP accumulation, leading to exacerbated abnormal locomotors in zebrafish larvae. [Display omitted] • Nano-TiO 2 aggravated accumulation and developmental toxicity of TPhP in zebrafish larvae. • Nano-TiO 2 aggravated TPhP-induced abnormities of spontaneous movement and swimming behavior in zebrafish larvae. • Nano-TiO 2 enhanced TPhP-induced inhibition of secondary motor neuron axon growth. • Nano-TiO 2 enhanced TPhP-induced decreased expressions of the neuron-specific GFP. • Co-exposure of TPhP and nano-TiO 2 leads to dysfunction of the 5-HT system. [ABSTRACT FROM AUTHOR]