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Increasing evidence shows that an adverse environment during the early fetal development can affect the epigenetic modifications on a wide range of diabetes-related genes, leading to an increased diabetic susceptibility in adulthood or even in subsequent generations. p,p'-Dichlorodiphenoxydichloroethylene (p,p'-DDE) is a break-down product of the pesticide dichlorodiphenyltrichloroethane (DDT). p,p'-DDE has been associated with various health concerns, such as diabetogenic effect. However, the precise molecular mechanism remains unclear. In this study, p,p'-DDE was given by gavage to pregnant rat dams from gestational day (GD) 8 to GD15 to generate male germline to investiagate the transgenerational effects. We found that early-life p,p'-DDE exposure increased the transgenerational diabetic susceptibility through male germline inheritance. In utero exposure to p,p'-DDE altered the sperm DNA methylome in F1 progeny, and a significant number of those differentially methylated genes could be inherited by F2 progeny. Furthermore, early-life p,p'-DDE exposure altered DNA methylation in glucose metabolic genes Gck and G6pc in sperm and the methylation modification were also found in liver of the next generation. Our study demonstrate that DNA methylation plays a critical role in mediating transgenerational diabetogenic effect induced by early-life p,p'-DDE exposure. [Display omitted] • Early-life p,p'-DDE exposure increased the transgenerational diabetic susceptibility through the male germline. • Early-life p,p'-DDE exposure altered DNA methylome in F1 sperm, part of which was inherited by F2 progeny. • Early-life p,p'-DDE exposure altered DNA methylation in Gck and G6pc in sperm and in liver of the next generation. [ABSTRACT FROM AUTHOR]

Nitrate contamination in aquatic systems is a widespread problem across the world. The isotopic composition (δ15N, δ18O) of nitrate and their isotope effect (15ε, 18ε) can facilitate the identification of the source and transformation of nitrate. Although previous researches claimed the isotope fractionations may change the original δ15N/δ18O values and further bias identification of nitrate sources, isotope effect was often ignored due to its complexity. To fill the gap between the understanding and application, it is crucial to develop a deep understanding of isotopic fractionation based on available evidence. In this regard, this study summarized the available methods to determine isotope effects, thereby systematically comparing the magnitude of isotope effects (15ε and 18ε) in nitrification, denitrification and anammox. We found that the enzymatic reaction plays the key role in isotope fractionations, which is significantly affected by the difference in the affinity, substrate channel properties and redox potential of active site. Due to the overlapping of microbial processes and accumulation of uncertainties, the significant isotope effects at small scales inevitably decrease in large-scale ecosystems. However, the proportionality of N and O isotope fractionation (δ18O/δ15N; 18ε/15ε) associated with nitrate reduction generally follows enzyme-specific proportionalities (i.e., Nar, 0.95; Nap, 0.57; eukNR, 0.98) in aquatic ecosystems, providing enzyme-specific constant factors for the identification of nitrate transformation. With these results, this study finally discussed feasible source portioning methods when considering the isotope effect and aimed to improve the accuracy in nitrate source identification. [Display omitted] • Ignorance of isotope fractionations impedes the nitrate source identification. • Enzymatic reaction is the fundamental factor to drive isotope fractionations. • 18ε/15ε provides specific constant factors for nitrate source identification • Appropriate practices of isotopic effect improves the accuracy of identification. [ABSTRACT FROM AUTHOR]

Nitrate contamination in aquatic systems is a widespread problem across the world. The isotopic composition (δ15N, δ18O) of nitrate and their isotope effect (15ε, 18ε) can facilitate the identification of the source and transformation of nitrate. Although previous researches claimed the isotope fractionations may change the original δ15N/δ18O values and further bias identification of nitrate sources, isotope effect was often ignored due to its complexity. To fill the gap between the understanding and application, it is crucial to develop a deep understanding of isotopic fractionation based on available evidence. In this regard, this study summarized the available methods to determine isotope effects, thereby systematically comparing the magnitude of isotope effects (15ε and 18ε) in nitrification, denitrification and anammox. We found that the enzymatic reaction plays the key role in isotope fractionations, which is significantly affected by the difference in the affinity, substrate channel properties and redox potential of active site. Due to the overlapping of microbial processes and accumulation of uncertainties, the significant isotope effects at small scales inevitably decrease in large-scale ecosystems. However, the proportionality of N and O isotope fractionation (δ18O/δ15N; 18ε/15ε) associated with nitrate reduction generally follows enzyme-specific proportionalities (i.e., Nar, 0.95; Nap, 0.57; eukNR, 0.98) in aquatic ecosystems, providing enzyme-specific constant factors for the identification of nitrate transformation. With these results, this study finally discussed feasible source portioning methods when considering the isotope effect and aimed to improve the accuracy in nitrate source identification. [Display omitted] • Ignorance of isotope fractionations impedes the nitrate source identification. • Enzymatic reaction is the fundamental factor to drive isotope fractionations. • 18ε/15ε provides specific constant factors for nitrate source identification • Appropriate practices of isotopic effect improves the accuracy of identification. [ABSTRACT FROM AUTHOR]

Abstract Particulate organic matter (POM), composed of fine root fragments and other organic debris, is an important fraction of soil organic matter which can affect the fate of nanoparticles and influence their performance in nanoparticle-based remediation technologies due to aggregation. Effects of POM are not well studied compared with those of dissolved organic matter. In this research, POM was extracted from black soil by sieving, and heteroaggregation of selenium nanoparticles (SeNPs) with POM and consequences for elemental mercury (Hg0) immobilization were investigated. It was found that low concentrations of more negatively charged POM (0–60 mg L−1) inhibited homoaggregation as well as heteroaggregation with SeNPs which had a lower negative charge through electrostatic repulsion. In the presence of high concentrations of POM (80–100 mg L−1), SeNPs were more likely to attach to POM with more Hg0 remaining in the POM since a larger concentration of nanoparticles would lead to more effective collisions. However, Hg0 immobilization efficiency using SeNPs was not significantly influenced by the addition of POM. This work is helpful to further understand the nanoparticle's behaviour in the environment and consequences for toxic metal remediation. Graphical abstract Image 102269 Highlights • POM can affect the fate of SeNPs in the environment. • POM (0–60 mg L−1) inhibited its homoaggregation and heteroaggregation with SeNPs. • Hg0 immobilization efficiency by SeNPs was not inhibited in the presence of POM. [ABSTRACT FROM AUTHOR]

With the vigorous development of industrial economy, energy and environmental problems have become the most serious issues affecting people's production and life. Therefore, the demand for clean energy production, effective separation and storage is growing. Metal-organic frameworks (MOFs), as a kind of porous crystalline materials with large surface area and porosity, which is self-assembled by metal ions or clusters and organic ligands through coordination bonds. Thanks to a number of unique characteristics such as adjustable pore environment, homogeneous void structure, abundant active sites, unprecedented chemical composition tunability and functional versatility, it has been widely studied, especially for the clean energy conversion in catalysis. In this review, we focus on the research progress of clean energy in catalysis based on MOFs. Emphasis is placed on MOFs with different structures of compositions and their applications in catalytic for clean energy conversion, such as CO oxidation, CO 2 reduction and H 2 evolution. In addition, the situation of MOFs assisting environmental remediation is also briefly described. Finally, the prospects and challenges of MOFs in clean energy and the remaining issues in this field are presented. [Display omitted] • MOFs based materials for CO2 Conversion and CO oxidation are summarised. • MOFs based materials for energy related hydrogen evolution are summarised. • MOFs based materials for environment catalytic degradation are discussed. • MOFs based membranes for various separation applications are summarised. • The advantage and disadvantage of MOF membranes are discussed. [ABSTRACT FROM AUTHOR]

The taste and odor (T&O) problem represented by 2-methylisoborneol (2-MIB) and geosmin (GSM) in water is the multiple undesirable substances in the drinking water and the aquatic industry. In this study, the UV-assisted photoelectrochemical, a prospective advanced oxidation process (AOP), was evaluated for the degradation of 2-MIB and GSM. In contrast to UV photochemical and electrochemical, the degradation ratio of GSM (2-MIB) increase to 96% (95%) in 25 min. The removal ratio and rate depended on reaction time, electrolyte concentration, current density, and water quality parameters (e.g. pH, HCO 3 −, natural organic matter, and tap water). Among these parameters, a high concentration of electrolyte and acidic solutions could accelerate the rate and increase the ratio, while alkaline conditions and the impurity content had negative effects. Furthermore, the significant role of various reactive species (e.g. HO∙, Cl , ClO , etc) were highlighted by scavenging experiments. Complex free radicals exist was further verified by electron paramagnetic resonance spectroscopy (EPR) experiments. The intermediates were identified and the possible degradation pathways during the UV-assisted photoelectrochemical reactions of both compounds were proposed. Overall, the UV-assisted photoelectrochemical is beneficial to the removal of GSM and 2-MIB in water. [Display omitted] • The UV-assisted photoelectrochemical can be effective in degrading GSM and 2-MIB. • Influencing factors in degrading GSM and 2-MIB were evaluated. • The contributions of free radicals for degradation were investigated. • Possible pathways of GSM and 2-MIB degradation were proposed. [ABSTRACT FROM AUTHOR]

Strobilurin fungicides are widely used pesticides in the world. They can have toxic effects not only to target organisms, but also to nontarget organisms. To assess their ecological risk, species sensitivity distributions (SSDs) are required for the development of water quality criteria (WQC). In this paper, the acute toxicity of four methoxyacrylate fungicides were experimentally determined and evaluated at 24, 48, 72 and 96 h for the species of Rana chensinensis and Limnodrilus hoffmeisteri , respectively. Acute and chronic HC 5 (5% hazard concentration) values and WQC values were calculated from SSDs based on the toxicity values determined in this paper and compiled from literature. SSDs revealed that aquatic animals were relatively sensitive species and aquatic plants are insensitive species for the four fungicides. However, different orders of species sensitivity in the acute and chronic toxicity indicated that these four fungicides had different toxic mechanisms or mode of action (MOA) to different species. According to toxicity correlation and principal component analysis (PCA), the kresoxim-methyl toxicity was very close to trifloxystrobin as compared with others due to that they are neutral compounds with very similar physicochemical properties. Quantitative structure-activity relationship (QSAR) revealed that toxicity of strobilurin fungicides were dependent both on chemical hydrophobicity and hydrogen bond basicity. These two molecular descriptors reflect the bio-uptake process and interaction of compounds with target receptors in an organism. WQC values and interspecies correlation are valuable for assessing water quality and understanding toxic mechanisms to different species. [Display omitted] • Acute toxicity of four fungicides have been determined and evaluated at 24, 48, 72 and 96 h. • Water quality criteria of acute and chronic toxicity have been developed for four strobilurin fungicides. • Toxicity of strobilurin fungicides is related with chemical hydrophobicity and hydrogen bonding potential. • The toxicity of four fungicides is not only dependent on the species, but also on the chemical structure. • Kresoxim-methyl toxicity is significantly related to trifloxystrobin toxicity because of their similar structure. [ABSTRACT FROM AUTHOR]

In this study, a lab-scale sequencing batch reactor (SBR) was established to assess the feasibility of maintaining partial nitrification in treating high-ammonium wastewater under the condition of excessive aeration (1 L/min, 1289 min). Results showed that the average ammonia (NH 4 +-N) removal efficiency (ARE) was 93.4 ± 2.7% and the average nitrite accumulation ratio (NAR) was 90.7 ± 2.8% during 15–50 d. In a typical cycle, free ammonia (FA) and free nitrous acid (FNA) alternately inhibited the activity of nitrite oxidizing bacteria (NOB), while low alkalinity limited further nitrification at even excessive aeration. Metagenomic analysis revealed that the relative abundance of Nitrosomonas , as the ammonia oxidizing bacteria (AOB), was up to 1.61%, while NOB were not detected. Taken together, this study indicated partial nitrification was almost not affected by excessive aeration, demonstrating its robustness depending on the cooperative strategy of the low alkalinity limitation and the inhibition of FA and FNA. [Display omitted] • Combined inhibition of FA and FNA resulted in the wash-out of NOB. • Low alkalinity limited further oxidation of NO 2 −-N caused by excessive aeration. • Nitrite accumulation ratio of 91.7% was maintained under excessive aeration condition. • Denitrification providing alkalinity for PN ensured high ARE and NAR concurrently. • Nitrosomonas (1.6%) was identified as the exclusive genus of AOB in the PN-SBR. [ABSTRACT FROM AUTHOR]

Abstract Uranium phytoextraction is a promising technology, however, facing difficult that limited plant biomass due to nutrient deficiency in the contaminated sites. The aim of this study is to evaluate the potential of a symbiotic associations of a legume Sesbania rostrata , rhizobia and arbuscular mycorrhiza fungi (AMF) for reclamation of uranium contaminated soils. Results showed AMF and rhizobia had a mutual beneficial relations in the triple symbiosis, which significantly increased plant biomass and uranium accumulation in S. rostrata plant. The highest uranium removal rates was observed in plant-AMF-rhizobia treated soils, in which 50.5–73.2% had been extracted, whereas 7.2–23.3% had been extracted in plant-treated soil. Also, the S. rostrata phytochelatin synthase (PCS) genes expression were increased in AMF and rhizobia plants compared with the plants. Meantime, content of malic acid, succinic acid and citric acid were elevated in S. rostrata root exudates of AMF and rhizobia inoculated plants. The facts suggest that the mutual interactions in the triple symbiosis help to improve phytoremediation efficiency of uranium by S. rostrata. Highlights • AMF and rhizobium had a mutual beneficial relations. • The inoculation of AMF/rhizobium enhanced PCS genes expression. • AMF/rhizobium improve phytoremediation efficiency of uranium by S. rostrata. [ABSTRACT FROM AUTHOR]

Although modes of action (MOAs) play a key role in the understanding of the toxic mechanism of chemicals, the MOAs have not been investigated for antibiotics to green algae. This paper is to discriminate excess toxicity from baseline level and investigate the MOAs of 13 different antibiotics to algae by using the determined toxicity values. Comparison of the toxicities shows that the inhibitors of protein synthesis to bacteria, such as azithromycin, doxycycline, florfenicol and oxytetracycline, exhibit significantly toxic effects to algae. On the other hand, the cell wall synthesis inhibitors, such as cefotaxime and amoxicillin, show relatively low toxic effects to the algae. The concentrations determined by HPLC indicate that quinocetone and amoxicillin can be easily photodegraded or hydrolyzed during the toxic tests. The toxic effects of quinocetone and amoxicillin to the algae are attributed to not only their parent compounds, but also their metabolites. Investigation on the mode of action shows that, except rifampicin, all the tested antibiotics exhibit excess toxicity to Pseudokirchneriella subcapitata ( P. subcapitata) . These antibiotics can be identified as reactive modes of action to the algae. They act as electrophilic mechanism of action to P. subcapitata . These results are valuable for the understanding of the toxic mechanism to algae. [ABSTRACT FROM AUTHOR]

The production of high quality liquid nitrogen fertilizer with both nutrient comprehensive and biostimulant properties by alkaline thermal hydrolysis of sewage sludge has shown great potential in agricultural production. However, little is known about the effects of sewage sludge-derived nutrients, and biostimulants (SS-NB) on leaf photosynthesis and root growth in rice. Phenotypic, metabolic and microbial analyses were used to reveal the mechanism of SS-NB on rice. Compared to NF treatment, phenotypic parameters (fresh/dry weight, soluble sugar, amino acid, protein) were increased by SS-NB in rice. SS-NB can enhance the photosynthesis of rice leaves by improving the photoconversion efficiency, chlorophyll content, ATP synthase activity, Rubisco and NADPH production. Meanwhile, SS-NB also increased antioxidant capacity (SOD, POD, CAT and proline) in rice leaf and root tissues. Metabolomics revealed that SS-NB application increased the expression levels of metabolites in root and leaf tissues, including carbohydrate, nitrogen and sulfur metabolism, amino acid metabolism, antioxidants, and phytohormone. Most importantly, the regulation of metabolites in rice root tissues is more sensitive than in leaf tissues, especially to the higher levels of antioxidants and phytohormones (IAA and GA) in rice root tissues. Furthermore, SS-NB increased the abundance of photosynthetic autotrophic, organic acids-degrading and denitrifying functional bacteria in rice roots and recruited plant growth-promoting bacteria (Azospirillum and norank_f_JG3 0-KF -CM45), while the NF treatment group resulted in an imbalance of the microbial community, leading to the dominance of pathogenic bacteria. The results showed that SS-NB had great application potential in crop growth and stress resistance improvement. [Display omitted] • SS-NB enhanced rice N metabolism and accumulation through microbial transformation. • The indole derivatives in SS-NB may stimulate root hormone activity and root growth. • Amino acid synthesis improves the photosynthesis capacity and sucrose accumulation. • The stimulatory effect of SS-NB on rice root was stronger than that on rice leaf. • Diterpenoid metabolites biosynthesize gibberellin to promote root growth. [ABSTRACT FROM AUTHOR]

Biomass-derived biochar shows broad promise for persistent organic pollutants (POPs) degradation and thus establishes a more sustainable homestead. However, effective catalytic performance is still challenging. Herein, an efficient catalyst (Prussian blue decorated wood-derived biochar, PBB) was constructed by introducing Prussian blue (PB) into wood-based biochar to activate peroxymonosulfate (PMS) for removing POPs. After anchoring of PB, the degradation performance of biochar was enhanced (degradation efficiency of methylene blue (MB, 20 mg/L) increased from 52% of biochar to 95% of PBB within 60 min). The PBB presents effective MB degradation performance with a wide pH value (3.0 < pH < 11.0) or co-existing diverse anions (Cl−, NO 3 −, H 2 PO 4 −, and HCO 3 −). Electron paramagnetic resonance (EPR) analysis as well as electrochemical tests confirmed that the non-radical pathway (1O 2) is the key to biochar activation of PMS, but by restricting PB into the biochar, the radical pathway (SO 4 •- and •OH), the non-radical pathway (1O 2), and direct electron transfer can work together to activate PMS. In addition, the degradation efficiency could remain about 80% after five-time cyclic tests. This work elucidates the role of PB nanoparticles in enhancing biochar catalysts, which can inspire the development of a carbon-neutralized, cost-effective, and effective strategy for POPs removal. [Display omitted] • Biochar-derived catalysts were developed. • Biochar and PB cubes work synergistically to achieve effective degradation. • The radical, non-radical way, and electron transfer facilized the MB degradation. [ABSTRACT FROM AUTHOR]

Poor effect of contaminants removal efficiency and low organic matter content of activated sludge are common in wastewater treatment plants (WWTPs) in China due to the low-strength wastewater. An anaerobic-anoxic-oxic (AAO) and an adsorption/AAO (A/AAO) combined system were established simultaneously to conduct a comparative study for realizing the conversion of carbon source in influent and the enrichment and recovery of proteins and amino acids through the assimilation of ammonia nitrogen. The experimental results showed that 63.5% of the organic matter in influent was adsorbed and flocculated in adsorption process, and the removal rates of chemical oxygen demand, total nitrogen and total phosphorus in A/AAO process were 88.7%, 77.1%, and 93.0% respectively, which were remarkably better than those in AAO process owing to the addition of improved carbon source. Ammonia assimilation rate of A/AAO process was 26.7% higher than that of AAO process, which implied that the ammonia used to synthesize sludge protein was prominently increased. Furthermore, intracellular proteins and amino acids in A/AAO process were 20% higher than those of AAO process, and the quality was equivalent with fish meal or soybean meal as feed. In addition, the microbial community analysis based on 16S rDNA was conducted. Dechloromonas , Zoogloea , Nitrospira , and Flavobacterium were the main genera, and played important roles in nutrient removal and ammonia nitrogen assimilation. The integration of adsorption process was significant to low-strength wastewater treatment and the improvement of excess sludge quality, which is a prospective inspiration for the resource recovery-based wastewater treatment process. • 63.5% of organic matter was adsorbed and flocculated in adsorption section. • Ammonia assimilation rate was 26.7% higher than traditional process. • The organic matter content of sludge in upgrading process reached 77%. • The quality of proteins and amino acids was equivalent with animal feed. • Dechloromonas, zoogloea and Flavobacterium were the main genus in upgrade process. [ABSTRACT FROM AUTHOR]

Organophosphate flame retardants (OPFRs) are extensively used as flame retardants and plasticizers, but their endocrine disrupting potentials have raised concerns. However, the impacts of OPFR exposures on reproductive and thyroid hormones in females remains unclear. In this study, serum concentrations of OPFRs were investigated, and levels of reproductive and thyroid hormones, including follicle-stimulating hormone (FSH), luteinizing hormone (LH), estradiol, anti-Müllerian hormone, prolactin (PRL), testosterone (T), and thyroid stimulating hormone, were analyzed in childbearing-age females undergoing in-vitro fertilization treatment from Tianjin, a coastal city in China (n = 319). Tris (2-chloroethyl) phosphate (TCEP) was the predominant OPFR, with a median concentration of 0.33 ng/mL and a detection frequency of 96.6%. In the whole population, tris(1,3-dichloro-2-propyl) phosphate (TDCIPP) and tris(2-chloroisopropyl) phosphate (TCIPP) were positively associated with T (p < 0.05), while triethyl phosphate (TEP) was negatively associated with LH (p < 0.05) and LH/FSH (p < 0.01). Particularly, TCIPP was negatively associated with PRL in the younger subgroup (age≤30, p < 0.05). Moreover, TCIPP was negatively associated with diagnostic antral follicle counting (AFC) in the mediation analysis by a dominating direct effect (p < 0.01). In conclusion, serum levels of OPFRs were significantly associated with reproductive and thyroid hormone levels and a risk of decreased ovarian reserve in childbearing-age females, with age and body mass index being significant influencing factors. [Display omitted] • Serum levels of OPEs are reported in Chinese females of childbearing age. • Serum TDCIPP and TCIPP are positively associated with serum T. • Serum TEP is negatively associated with serum LH and LH/FSH. • Serum TCIPP is negatively associated with serum antral follicle counting. • Age and BMI influence the associations between serum OPEs and reproductive hormones. [ABSTRACT FROM AUTHOR]

Abstract Due to its high mass transfer efficiency, microbubble ozonation has been widely used in water treatment to degrade refractory compounds. Compared to conventional bubbles (diameters larger than 1 mm), microbubbles (diameter less than 50 μm) have special interfacial characteristics that are probably advantageous in ozonation. However, the mechanisms involved are still unclear and therefore our primary aim here was to explore the interfacial effect of microbubbles during ozonation process. Phenol and nitrobenzene degradation by ozone microbubbles and conventional bubbles were carried out across a broad pH range. We found that microbubble decomposition of pollutants was markedly more efficient than conventional bubbles in terms of ozone consumption. Hydroxyl radical scavenger experiments of phenol revealed that the enhancement of microbubble might result from the increase of ozone concentration in interfacial region and a mathematical simulation further proved this synthesis by showing that ozone concentration is not homogenous throughout the reaction medium and forms a steep gradient in the liquid film of microbubbles. As for nitrobenzene, the acceleration of hydroxyl radicals was supposed to be the dominate factor which might be the consequence of high gas concentration in liquid film. These findings shed light on the mechanism of interfacial reaction in microbubble ozonation. Highlights • Microbubble decomposed pollutants more efficiently in terms of ozone consumption. • Ozone concentration forms a steep gradient in the liquid film of microbubbles. • Microbubbles could efficiently accelerate the generation of OH during ozonation. [ABSTRACT FROM AUTHOR]

Constructed wetlands (CWs) have been widely used for ecological remediation of micro-polluted source water. Nitrous oxide (N 2 O) from CWs has caused great concern as a greenhouse gas. However, the contribution of ammonia oxidation driven by ammonia oxidizing archaea (AOA) and ammonia oxidizing bacteria (AOB) to N 2 O emission, especially at low temperature, was unknown. This study aimed to quantify the contributions of AOA and AOB to N 2 O through lab-scale subsurface CWs. The N 2 O emission flux of CW at 8 °C was 1.23 mg m−2·h−1, significantly lower than that at 25 °C (1.92 mg m−2·h−1). The contribution of ammonia oxidation to N 2 O at 8 °C (33.04%) was significantly higher than that at 25 °C (24.17%). The N 2 O production from AOA increased from 1.91 ng N·g−1 at 25 °C to 4.11 ng N·g−1 soil at 8 °C and its contribution increased from 23.38% to 30.18% (P < 0.05). Low temperature impaired functional gene groups and inhibited the activity of AOB, resulting in its declined contribution. Based on the transcriptional analysis, AOA was less affected by low temperature, thus stably contributing to N 2 O. Moreover, community diversity and relationships of AOA were enhanced at 8 °C, while AOB declined. The results confirmed the significant contribution of AOA and demonstrated molecular mechanisms (higher activity and community stability) of the increased contribution of AOA to N 2 O at low temperature. [Display omitted] • N 2 O emission from ammonia oxidation in constructed wetlands was first quantified. • AOA produced 90.2% more N 2 O at low temperature than at room temperature. • The relative contribution of AOA to N 2 O at 8 °C was 121.61% of that at 25 °C. • Low temperature impaired functional gene groups and decreased the activity of AOB. • Contributions of AOA and AOB to N 2 O could not be ignored especially at low temperature. [ABSTRACT FROM AUTHOR]

Substrate clogging is one of the major operation challenges of subsurface flow constructed wetlands (SSF-CWs). And the phosphorus (P) removal performance and stability of P accumulation of SSF-CWs would be varied with the development of substrate clogging. In this study, three horizontal SSF-CWs microcosms with different clogging degrees were conducted to explore the mechanism of P accumulation behavior influenced by substrate clogging. Increase in clogging degree resulted in hydraulic retention time (HRT) diminution and adsorption sites increase, which jointly led to reduced P removal efficiency at low clogging degree (L-CW), however, higher P removal efficiency was obtained as adsorption sites increase offset HRT diminution at high clogging degree (H-CW). Substrate adsorption was the primary removal pathway in all SSF-CW systems. It accounted for 77.86 ± 2.63% of the P input in the H-CW, significantly higher than the control (60.08 ± 4.79%). This was attributed to a higher proportion of Fe/Al–P accumulated on the substrate of H-CW, since clogging aggravated the anaerobic condition and promoted the generation of Fe ions. The increase in clogging degree also elevated the release risk of the accrued P in SSF-CWs, since Fe/Al–P was considered bioavailable and readily released under environmental disturbance. The obtained results provide new insights into the P transport and transformation in SSF-CWs and would be helpful to optimize substrate clogging management. [Display omitted] • Clogging aggravated anaerobic condition in SSF-CWs and promoted Fe remobilization. • Newly generated Fe ions precipitation with dissolved P affected P fraction. • Clogging improved P removal as adsorption sites increase offset HRT diminution. • Fe/Al–P accumulation caused by clogging elevated P release risk of SSF-CWs. [ABSTRACT FROM AUTHOR]

The toxic effect can be affected by pH in water through affecting the degree of ionization of ionizable compounds. Wrong classification of mode of action can be made from the apparent toxicities. In this paper, the toxicity data of 61 compounds to Daphnia magna determined at three pH values were used to investigate the effect of pH on the discrimination of excess toxicity. The results show that the apparent toxicities are significantly less than the baseline level. Analysis on the effect of pH on bioconcentration factor (BCF) shows that the log BCF values are significantly over-estimated for the strongly ionizable compounds, leading to the apparent toxicities greatly less than the baseline toxicities and the toxic ratios greatly less than zero. A theoretical equation between the apparent toxicities and pH has been developed basing on the critical body residue (CBR). The apparent toxicities are non-linearly related to pH, but linearly to fraction of unionized form. The determined apparent toxicities are well fitted with the toxicities predicted by the equation. The toxicities in the unionized form calculated from the equation are close to, or greater than the baseline level for almost all the strongly ionizable compounds, which are very different from the apparent toxicities. The studied ionizable compounds can be either classified as baseline, less inert or reactive compounds in D. magna toxicity. Some ionizable compounds do not exhibit excess toxicity at a certain pH, due not to their poor reactivity with target molecules, but because of the ionization in water. [ABSTRACT FROM AUTHOR]

Paraquat (PQ) pollution has become an increasing seriously threat to the ecological environment. Thus, it is vital to study novel adsorption materials capable of removing PQ. Modified carbon tubes (MCT-600) were prepared by carbonizing the seed hair fibers of Metaplexis japonica at 600 °C and further modifying with nitric acid. The MCT-600 was found to possess a regular morphology, a good graphitization degree and an abundance of carboxyl functional groups. Moreover, this materil exhibits excellent adsorption performance for paraquat (PQ), such as a fast adsorption rate (adsorption equilibrium within 20 min), large adsorption capacity (218.61 mg g−1) and good regeneration ability (reused more than 5 times). The adsorption process for PQ onto MCT-600 was found to be well matched to a Langmuir isotherm and pseudo-second-order kinetics model. Owing to its unique surface properties, green raw material source and simple preparation process, MCT-600 shows potential as an outstanding candidate for PQ removal from water. Image 1 • Low cost and widespread source carbon tubes derived from biomass are prepared. • Adsorption of material fitted with Langmuir and pseudo-second-order kinetics model. • High binding capacity and fast kinetics endow material a wide application prospect. [ABSTRACT FROM AUTHOR]

Nowadays, the visible-light-driven photocatalysis via advanced photocatalyst for PS activation have promising applications in wastewater treatment. Herein, for the first time, two novel MOFs@COFs hybrid materials (denoted as MIL-101-NH 2 @TpMA and UiO-66-NH 2 @TpMA) with nitrogen-rich building blocks were fabricated via a feasible step-by-step assembly method, and then employed as efficient photocatalytic platform coupling with sulfate radical-based advanced oxidation processes for the degradation of BPA under visible light irradiation. Detailed analyses revealed that the hybridization of MOFs and COFs could greatly boost visible light absorption, while the heterojunction formed at the interface could effectively facilitate the separation and transfer of photogenerated electron-hole pairs. More importantly, the developed solar/MOFs@COFs/PS system exhibited the excellent degradation ability toward BPA, and an incredible degradation efficiency of 99% was eventually achieved. Possible mechanism for photocatalytic degradation of BPA was also proposed. Furthermore, the prepared composites with great reusability and stability possessed a broad potential for highly effective degradation of various organic contaminants. In short, this work not only demonstrated the combination of MOFs and COFs with C 3 N 4 active unit was a feasible strategy for improving photocatalytic activities in the degradation of organic contaminants, but also provided some novel inspirations for constructing high-efficient photocatalysts with heterostructure. Image 1 • Two novel MOFs@COFs hybrid materials with C 3 N 4 active units were first synthesized. • Developed solar/MOFs@COFs/PS system exhibited great degradation ability toward BPA. • Possible mechanisms for photocatalytic degradation of BPA was proposed. • As-obtained composites possessed excellent reusability and stability. • Prepared photocatalyst had a broad potential for degradation of various contaminants. [ABSTRACT FROM AUTHOR]