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Heavy metal (HM) pollution, particularly in its ionic form in water bodies, is a chronic issue threatening environmental security and human health. The microalgal-bacterial symbiosis (MABS) system, as the basis of water ecosystems, has the potential to treat HM wastewater in a sustainable manner, with the advantages of environmental friendliness and carbon sequestration. However, the differences between laboratory studies and engineering practices, including the complexity of pollutant compositions and extreme environmental conditions, limit the applications of the MABS system. Additionally, the biomass from the MABS system containing HMs requires further disposal or recycling. This review summarized the recent advances of the MABS system treating HM wastewater, including key mechanisms, influence factors related to HM removal, and the tolerance threshold values of the MABS system to HM toxicity. Furthermore, the challenges and prospects of the MABS system in treating actual HM wastewater are analyzed and discussed, and suggestions for biochar preparation from the MABS biomass containing HMs are provided. This review provides a reference point for the MABS system treating HM wastewater and the corresponding challenges faced by future engineering practices. [Display omitted] • The mechanisms of MABS system treating HM wastewater were reviewed. • The effects of HMs on growth and characteristics of MABS system were explored. • The structural form and characters of MABS system affect HM removal efficiency. • MABS system contribute to HMs removal through biosorption or bioaccumulation. • The challenges of MABS system treating HM wastewater were discussed. [ABSTRACT FROM AUTHOR]

Abstract It has been several years that a soft transparent polyvinyl chloride (PVC) plastic sheet, commonly known as “soft glass”, or “crystal plate” in China and other developing countries, has quietly and gradually found extensive applications. This material has widely replaced cloth and glass as table cover in household and office, and replaced cloth as door drape in public place in China. In this study, the concentration of plasticizer used in soft glass and the migration of the plasticizer from soft glass to olive oil and porcine skin during contact were determined. The oral exposure of young children to the plasticizer from soft glass was estimated for the first time. Two exposure routes, one via ingestion of contaminated food, the other via mouthing of contaminated hand, were considered. It is found that Di(2-ethylhexyl) phthalate (DEHP) is the major plasticizer used in soft glass, which could leach out of the material and migrate easily to the olive oil and porcine skin during contact. A rough estimation of oral exposure for young children to DEHP from soft glass was 126 μg/person/d, which would be converted to 12.6 μg/kg bw/d and 7.9 μg/kg bw/d, for body weight of 10 kg and 16 kg, respectively. The estimated exposure dosages would not pose immediate health hazard to the children. The implications of these dosages were also discussed. Highlights • DEHP is the main plasticizer in soft glass (or crystal plate), a soft PVC sheet. • DEHP accounts for more than 50% by weight of the transparent soft glass. • DEHP could leach out of soft glass to the olive oil and pork skin during contact. • Estimated DEHP exposure dosages would not pose immediate health hazard to children. [ABSTRACT FROM AUTHOR]

Passive sampling techniques have been widely used to determine the dissolved concentration profiles of hydrophobic organic compounds (HOCs) in sediment porewater. However, the effects of having a protection for the passive sampler on profiling HOCs concentrations in sediment porewater, especially in deep sediment, have remained unclear. To address this issue, low density polyethylene passive samplers with and without protectors, which consisted of glass fiber filter and porous stainless steel shield, were simultaneously deployed in sediment of the Dongjiang River, South China. The results showed that the protectors retarded the dissipation of performance reference compounds (PRCs) from the sampler by a factor of 2–9. The protectors seemed to exert a negligible effect on the measured concentrations of PAHs, BDE-47, and BDE-99 in surficial sediment porewater (0–14 cm depth) from both samplers. However, the sediment porewater concentration profiles of PAHs and BDE-47 from the sampler with protectors were in agreement with those normalized by dry weight in deep sediment (16–34 cm depth), indicating that a diffusion layer established by the protectors may minimize the probability of local depletion of the target analytes in deep sediment. In addition, the log K oc values of PAHs, BDE-47, and BDE-99 exhibited a slight increasing trend with sediment depth. This finding suggested that in situ passive sampling techniques could be a feasible tool in determining the site-specific log K oc values of HOCs at different sediment depths. Image 1 • Protectors significantly retarded the dissipation of PRCs. • Protectors did not affect the measured concentrations of PAHs in surficial porewater. • PAHs profile from the sampler with protectors was similar to that in deep sediment. [ABSTRACT FROM AUTHOR]

To investigate the degradation efficiency of conditioners and commercial microbial agents on estrogens (E1, 17α-E2, 17β-E2, E3, EE2, and DES) in the composting process of dairy manure, seven different treatments (RHB-BF, OSP-BF, SD-BF, MR-BF, MR-FS, MR-EM, and MR-CK) under forced ventilation conditions were composted and monitored regularly for 30 days. The results indicated that the removal rates of estrogens in seven treatments ranged from 95.35% to 99.63%, meanwhile the degradation effect of the composting process on 17β-Estradiol equivalent (EEQ) was evaluated, and the removal rate of ΣEEQ ranged from 96.42% to 99.72%. With the combined addition of rice husk biochar (RHB) or oyster shell powder (OSP) and bio-bacterial fertilizer starter cultures (BF), namely RHB-BF and OSP-BF obviously promoted the rapid degradation of estrogens. 17β-E2 was completely degraded on the fifth day of composting in OSP-BF. Microbial agents have some promotional effect and enhances the microbial degradation of synthetic estrogen (EE2, DES). According to the results of RDA, pH and EC were the main environmental factors affecting on the composition and succession of estrogen-related degrading bacteria in composting system. As predominant estrogens-degrading genera, Acinetobacter, Bacillus, and Pseudomonas effected obviously on the change of estrogens contents. The research results provide a practical reference for effective composting of dairy manure to enhancing estrogens removal and decreasing ecological risk. [Display omitted] • Conditioners and microbial agents could enhance estrogens degradation (>95% removal). • Conditioner OSP presented excellent removal effect (99.63%) on the estrogens in composting. • The addition of microbial agents promoted the degradation of synthetic estrogens (EE2, DES). • PH/EC dominantly effected on the composition and succession of estrogens-degrading genera. • Predominant genera for estrogens degradation were Acinetobacter, Bacillus, and Pseudomonas. [ABSTRACT FROM AUTHOR]

Isoniazid (INH) is a first-line anti-tuberculosis drug. INH has been detected in surface waters which may create a risk to aquatic organisms. In this study, the hepatotoxicity of INH was elucidated using zebrafish. The liver morphology, transaminase level, redox-related enzyme activity, reactive oxygen species (ROS) content and mRNA levels of liver injury-related genes were measured. The results showed that INH (4, 6 mM) significantly caused liver atrophy and increased levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) in zebrafish. INH (6 mM) led to decreased catalase (CAT) activity, glutathione peroxidase (GPx) activity and glutathione (GSH) content but increased ROS and malondialdehyde (MDA) levels. Moreover, INH (6 mM) decreased expression levels of miR-122 and pparα but increased mRNA levels of ap-1 and c-jun. Furthermore, mRNA levels of factors related to endoplasmic reticulum stress (ERS) (grp78 , atf6 , perk , ire1 , xbp1s and chop), apoptosis (bax , cyt , caspase-3 , caspase-8 and caspase-9) and the Nrf2 signalling pathway (nrf2 , ho-1 , nqo1 , gclm and gclc) were significantly upregulated. INH may act on hepatotoxicity in zebrafish by increasing ROS content, which weakens the antioxidant capacity, leading to ERS, cell apoptosis and liver injury. In addition, the Nrf2 signalling pathway is activated as a stress compensation mechanism during INH-induced liver injury, but it is not sufficient to counteract INH-induced hepatotoxicity. Image 1 • INH caused dose- and time-dependent increase in hepatotoxicity in zebrafish larvae. • INH (4 and 6 mM) caused an increase in ROS, which induced oxidative stress, leading to ERS, apoptosis and liver injury. • The Nrf2 signalling pathway is activated during the early stages of INH-induced liver injury. [ABSTRACT FROM AUTHOR]

Phenolic endocrine disrupting chemicals (EDCs) may pose a great hazard to wildlife and humans, owing to their ubiquitous presence in the environment and potential bioaccumulation ability. We investigated the bioaccumulation, metabolism, and human health risks of six phenolic EDCs, including bisphenol A (BPA), 4- tert -octylphenol (4- t -OP), 4-nonylphenol (4-NP), estrone (E1), 17 β -estradiol (E2), and 17 α -ethinylestradiol (EE2), in wild fish from the Pearl River system, South China. Except EE2, the other five EDCs were detected in at least one of the four fish tissues (bile, liver, plasma, and muscle). The concentrations of BPA and 4-NP were greater than those of 4- t -OP, E1, and E2 in all tissues. The median values of log bioaccumulation factors for EDCs at the range of 3.86–4.52 in bile, 2.06–3.16 in liver, 2.69–3.87 in plasma, and 1.34–2.30 in muscle, indicating a higher bioaccumulation potential in fish bile than in other tissues. Greater levels of glucuronide/sulfate conjugated EDCs were found in fish bile and liver than in the plasma and muscle, suggesting that the liver and bile played an important role in the metabolism and excretion of phenolic EDCs in fish. The calculated hazard quotient values were below 1 for each compound, implying low risk to human health by intake of edible fish. Image 1 • Higher levels of BPA and 4-NP were found than 4- t -OP, E1 and E2 in the four fish tissues. • Fish bile displayed greater bioaccumulation ability for the phenolic EDCs than liver, plasma and muscle. • Liver and bile played a significant role in metabolism and excretion of the phenolic EDCs in fish. • Consumption of edible wild fish muscle might not cause considerable risk to human health. [ABSTRACT FROM AUTHOR]

Abstract Being able to quantify nutrient stoichiometry in the waterbodies is especially important given its strong effects on a variety of ecological processes. China has made huge progress in the improvement of surface water quality, but the accompanying changes to water nutrient stoichiometry and implications are not well understood yet. Our results have shown that the water nutrient cycles have been decoupled in China's populated regions, and population density and GDP values in the same catchment are useful in explaining the variances of lake N:P stoichiometry in East China Lake Region. In other regions, water N and P tend to respond to the selected parameters in a similar way, leading to the poor prediction of N:P stoichiometry. With the progress of water management in China, a similar change of water nutrients and their stoichiometry as the developed countries is occurring, i.e., faster decrease of TP concentrations than TN, and continuing increase of N:P ratios. It is necessary for the managers to be aware of the quick and large-scale changes of nutrient stoichiometry in the water, since the ecological risk caused by the changes to the aquatic systems is still not well known. Graphical abstract Image 1 Highlights • We present an investigation of historical changes of water N, P and TN/TP ratio in China. • Human activities have decoupled the waterbody N:P ratio in populated regions. • A continued increase in water N:P ratio is observed with progress in water management. • A flexible regional water management strategy is needed due to the different drivers for nutrient changes. [ABSTRACT FROM AUTHOR]

A facile one-step assembly method was developed for the preparation of metal-organics @Bi 2 O 3 composites for photocatalysis. Two kinds of metal-organics (Ti-bdc and Cu-btc)@Bi 2 O 3 composites were synthesized via the coordination of btc 3− /bdc 2− and metal ions (Ti 4+ /Cu 2+ ) as well as OH on the surface of Bi 2 O 3 . Compared with pure Bi 2 O 3, Ti-bdc@Bi 2 O 3 shows a 1.7 times higher photocatalytic activity in the degradation of sulfamethoxazole (SMX) under a simulated solar irradiation with a cumulative removal of 62% within 60 min. The high photocatalytic activity could be attributed to the high charge separation, enhanced electron transfer as well as the low recombination rate of photo-generated electrons and holes due to the construction of hetero-structures. The stability test showed that Ti-bdc@Bi 2 O 3 is more stable in water than Cu-btc@Bi 2 O 3 . Furthermore, through the radical-trapping experiments and main intermediates detection, it is demonstrated that the photo-generated holes as well as the OH and O 2 − formed dominate the photocatalytic decomposition of SMX. These findings demonstrate the potential usage of a facile method to synthesize metal-organics and metal oxides composites, some of which possess high water stability and thus could be employed for water treatment. [ABSTRACT FROM AUTHOR]

Although various persistent organic pollutants (POPs) can affect microbial communities and functions in aquatic ecosystems, little is known about how bacteria and microeukaryotes respond to the POPs in sediments planted with different submerged macrophytes. Here, a 60-day microcosm experiment was carried out to investigate the changes in the diversity and interaction of bacterial and microeukaryotic communities in sediments collected from Taihu lake, either with decabromodiphenyl ether (BDE-209) own or combined with two common submerged macrophyte species (Vallisneria natans and Hydrilla verticillate). The results showed that BDE-209 significantly decreased the bacterial α-diversity but increased the microeukaryotic one. In sediments planted with submerged macrophytes, the negative effect of BDE-209 on bacterial diversity was weakened, and its positive effect on microeukaryotic one was strengthened. Co-occurrence network analysis revealed that the negative relationship was dominant in bacterial and microeukaryotic communities, while the cooperative relationship between microbial species was increased in planted sediments. Among nine keystone species, one belonging to bacterial family Thermoanaerobaculaceae was enriched by BDE-209, and others were inhibited. Notably, such inhibition was weakened, and the stimulation was enhanced in planted sediments. Together, these observations indicate that the responses of bacteria and microeukaryotes to BDE-209 are different, and their communities under BDE-209 contamination are more stable in sediments planted with submerged macrophytes. Moreover, the effects of plant species on the microbial responses to BDE-209 need to be explored by more specific field studies in the future. [Display omitted] • Responses of bacteria and microeukaryotes to BDE-209 were different in sediment. • Inhibition of BDE-209 on bacterial diversity was weakened in planted sediments. • Planting enhanced stimulation of BDE-209 on sediment microeukaryotic diversity. • Microbial cooperation was enhanced in planted sediments under BDE-209. • Effect of BDE-209 on microbial network module was weakened in planted sediments. [ABSTRACT FROM AUTHOR]

Androgens are one class of steroids that could cause endocrine disrupting effects in aquatic organisms. However, little information is available about androgens in wastewater treatment plants (WWTPs) with different treatment technologies. Here we investigated the occurrence, removal, and fate of fourteen natural and synthetic androgens in ten WWTPs of Guangdong province, south China. The results showed detection of ten androgens in the influents of the ten WWTPs, with concentrations up to 4650 ng/L (androsta-1,4-diene-3,17-dione). But only three androgens androsta-1,4-diene-3,17-dione, 4-androstene-3,17-dione and 17β-boldenone were detected in the final effluents of the ten WWTPs, while six androgens androsta-1,4-diene-3,17-dione (N.D. to 43.0 ng/g), 4-androstene-3,17-dione (2.06–42.7 ng/g), epi-androsterone (N.D. to 506 ng/g), testosterone (0.29–4.24 ng/g), 17β-boldenone (N.D. to 2.05 ng/g) and methyl testosterone (N.D. to 0.70 ng/g) were found in activated sludge. The aqueous phase removal rates for most androgens in the WWTPs exceeded 95% except for 4-androstene-3,17-dione with its removal rates varying between 79.5% and 100%. The removal of androgens in the WWTPs could be attributed mainly to biodegradation while removal by precipitation, volatilization, sludge absorption and oxidation was very limited. Eight androgens were also found in five receiving rivers. The risk quotients of some androgens (androsta-1,4-diene-3,17-dione, 4-androstene-3,17-dione, methyl testosterone, 17α-trenbolone) exceeded 1 in the receiving rivers, showing high risks to aquatic organisms. Further studies are needed to understand the origin of these high risk androgens and ecological effects. [ABSTRACT FROM AUTHOR]

Exudates by marine phytoplankton and metals coexist in the seawater, but little is known about their interaction. In this study, cultures of Prorocentrum donghaiense Lu were grown in urea and ammonium, and then exposed to different Ni ion levels in order to study the effects of Ni ions on algal growth. The regulatory mechanisms of P. donghaiense Lu for coping with different Ni ion levels was investigating by characterizing dissolved organic carbon (DOC), carbohydrate and protein content released per cell, hydropathy properties (hydrophilic and hydrophobic fractions) and thiol compounds (cysteine-like or glutathione-like). Lower levels of Ni ions (pNi>10.0) significantly promoted the growth of P. donghaiense Lu when incubated in urea; however, the same was not true for P. donghaiense Lu cultivated in ammonium. An increased presence of hydrophobic fractions and thiol compounds (cysteine-like or glutathione-like compounds) induced by low Ni ions (pNi>10.0) in urea cultures suggest that the activation of cellular mechanisms in response to insufficient Ni ion stress enhances Ni bioavailability. Furthermore, the abundance of carbohydrates and proteins released by cells when exposed to higher Ni ions levels (from pNi = 10.0 to pNi = 8.0) both in urea and ammonium cultures suggests that algal cells may utilize exudate to complex Ni cations and reduce their toxicity. Therefore, it can be speculated that phytoplankton can produce large amounts of specific exudate, which may accelerate the metal bioavailability (insufficient levels) and reduce metal toxicity (excess levels) to maintain an equilibrium with metals in the environment. [ABSTRACT FROM AUTHOR]

N -methyl-2-pyrrolidone (NMP) is widely used as a solvent in polymeric membrane fabrication process, its elimination from the process wastewater (normally at a high concentration > 1000 mg/L) prior to discharge is essential because of environmental concern. This study investigated the feasibility of treating high-strength NMP-containing process wastewater in a sequencing batch reactor (SBR; i.e., batch feeding and intermittent aerobic/anoxic condition) and a membrane bioreactor (MBR; i.e., continuous feeding and aeration), respectively. The results showed that the SBR with the acclimated sludge was capable of removing >90% of dissolved organic carbon (DOC) and almost 98% of NMP within 2 h. In contrast, the MBR with the acclimated sludge showed a decreasing NMP removal efficiency from 100% to 40% over 15-day operation. The HPLC and LC-MS/MS analytical results showed that NMP degradation in SBR and MBR could undergo different pathways. This may be attributed to the dissimilar bacterial community compositions in the SBR and MBR as identified by 16s rRNA gene sequencing analysis. Interestingly, the NMP-degrading capability of the activated sludge derived from MBR could be recovered to >98% after they were operated at the SBR mode (batch feeding mode with intermittent aerobic/anoxic condition). This study reveals that SBR is probably a more feasible process to treat high-strength NMP-containing wastewater, but residual NMP metabolites in the SBR effluent need to be post-treated by an oxidation or adsorption process in order to achieve zero-discharge of toxic chemicals. [ABSTRACT FROM AUTHOR]

Denitrification is a dominant reactive nitrogen removal pathway in most estuarine and coastal ecosystems, and plays a significant role in regulating N 2 O release. Although multiple antibiotics residues are widely detected in aquatic environment, combined effects of antibiotics on denitrification remain indistinct. In this work, 5 classes of antibiotics (sulfonamides, chloramphenicols, tetracyclines, macrolides, and fluoroquinolones) were selected to conduct orthogonal experiments in order to explore their combined effects on denitrification. 15 N-based denitrification and N 2 O release rates were determined in the orthogonal experiments, while denitrifying functional genes were examined to illustrate the microbial mechanism of the combined antibiotics effect. Denitrification rates were inhibited by antibiotics treatments, and synergistic inhibition effect was observed for multiple antibiotics exposure. Different classes of antibiotics had different influence on N 2 O release rates, but multiple antibiotics exposure mostly led to stimulatory effect. Abundances of denitrifying functional genes were inhibited by multiple antibiotics exposure due to the antimicrobial properties, and different inhibition on denitrifiers may be the major mechanism for the variations of N 2 O release rates. Combined effects of antibiotics on denitrification may lead to nitrate retention and N 2 O release in estuarine and coastal ecosystems, and consequently cause cascading environmental problems, such as greenhouse effects and hyper-eutrophication. [ABSTRACT FROM AUTHOR]

Abstract: Oral ingestion of contaminated soil is an important pathway of human exposure to hydrophobic organic contaminants (HOCs), particularly for children in developing countries. The mobilization potential of various contaminants from ingested soil is often characterized using an in vitro gastrointestinal model, based on the quantities of contaminants remaining in digestive fluid after digestion and separation. Recently, it was experimentally demonstrated that a large fraction of mobilized contaminants sorbed on the digested residue could be released if the dissolved fraction was removed by intestinal absorption. This hypothesis was further tested in this study. Soil spiked with dichlorodiphenyltrichloroethane and its metabolites (DDXs) and polycyclic aromatic hydrocarbons (PAHs) was digested using an in vitro gastrointestinal model. A human colon carcinoma cell line (Caco-2) was cultured in digestive fluid with or without soil residue (pre-equilibrated with the soil) for 2h. A large proportion of the contaminants (37–68%) was sorbed on the digested residue. Without this residue, 66±13% of DDXs and 73±14% of PAHs dissolved in the fluid, as means and standard deviations, were absorbed by the cell monolayer after exposure. With both digestive fluid and residue, the sorbed fraction of PAHs and DDXs decreased by 38–92%, while the ratios of the cellular to the dissolved concentrations were 2.7–2.8 times higher than those without the residue. This supported the hypothesis that the cell absorption of dissolved HOCs induces desorption of the sorbed fraction from digestive residue, and the desorbed HOCs can be absorbed as well. [Copyright &y& Elsevier]

Catalytic activation of peroxymonosulfate (PMS) to generate radicals has received considerable and increasing attention in the environmental catalysis for treatment of recalcitrant pollutants. In the current study, a series of highly porous, cobalt-loaded activated carbon nanofibers (Co/CNFs) were prepared by one-pot electrospinning followed by thermal treatment. Observations showed that the limited addition of Co (≤8%) had no obvious effect on the morphology of the resulted CNFs, but it did affect the surface area and porosity of the CNFs as well as the carbon graphitic process during the carbonization. The applicability of this confined nanoreactor used in sulfate-radical based advanced oxidation processes (SR-AOPs) was systematically investigated. The effect of pH on the radical generation and organics removal was examined. The oxygen species on the CNFs played an important role in the activation of PMS. The carbon layer encapsulated on the Co crystal surface inhibited the Co leaching during the reaction and increased the catalytic efficiency due to the enhanced interfacial charge transfer. Meanwhile, the carbon layer could synchronously function as the adsorptive active sites during the degradation of organics. Results showed that the Co/CNFs possessed the highest catalytic efficiency under neutral pH, corresponding to the sulfate radical generation. The Co leaching and XPS results showed that the Co served as the main active site in PMS activation. • Spatial confinement of cobalt crystals in carbon nanofibers was achieved. • The addition of Co affected the surface area and porosity of the resulted CNFs. • Co tuned the formation of CNFs and functioned as the active site for PMS activation. • The effect of pH on radical generation and organics degradation was investigated. • The synergistic effect between Co/CNFs and PMS enhanced catalytic efficiency. [ABSTRACT FROM AUTHOR]