Ecological risk assessment for typical organophosphorus pesticides in surface water of China based on a species sensitivity distribution model.

The ecological risks posed by widespread organophosphorus pesticide (OPs) pollution in the surface waters of China remain unclear. In this study, species sensitivity distribution (SSD) parametric statistical approaches were coupled with fully acute and chronic toxicity data to fit the sensitivity distributions of different aquatic species to five typical OPs: dimethoate, malathion, parathion-methyl, trichlorfon, and dichlorvos. Crustaceans exhibit the highest sensitivity to OPs, whereas algae are the least sensitive. The acute hazardous concentrations that affected 5 % of the species (HC5) were 0.112, 0.001, 0.001, 0.001, and 0.001 mg/L for dimethoate, malathion, parathion-methyl, trichlorfon, and dichlorvos, respectively, whereas their chronic HC5 values were 0.004, 0.004, 0.053, 0.001, and 0.0005 mg/L, respectively. Hence, dichlorvos is highly toxic and poses greater risk to non-target aquatic species. The evaluation data revealed varying geographical distribution characteristics of the ecological risks from OPs in 15 freshwater aquatic systems across different regions of China. Dichlorvos posed the highest risk in the basins of Zhejiang and Guangdong Provinces, with the highest chronic Risk Quotient (RQ) and Hazard Index (HI) at 9.34 and 9.92, respectively. This is much higher than what was collected and evaluated for foreign rivers (the highest chronic RQ and HI in foreign rivers were 1.65 and 2.24, respectively). Thus, dichlorvos in the surface waters of China poses a substantial ecological risk to aquatic organisms, and may endanger human health.

Plastic food? Energy compensation of zebrafish (Danio rerio) after long-term exposure to polylactic acid biomicroplastics.

The extensive use of bio-based plastics has led to their widespread distribution in the environment. However, their long-term ecological impact on aquatic animals is not well understood. In this study, adult zebrafish (Danio rerio) were exposed to 1000 items·L-1 of either polylactic acid (PLA) or polyethylene terephthalate (PET) microplastics (MPs), for 90 days. PLA is a typical bio-based plastic, while PET is a typical petroleum-derived plastic. The abundances of PLA and PET MPs in fish intestines were 981 ± 66 and 671 ± 151 items per fish, respectively, indicating a greater amount of PLA MP residues than PET MPs. However, the inhibitory effect of PET on fish weight was 1.8 times higher than that of PLA, suggesting energy compensation in PLA-treated zebrafish. Proliferation of Lactobacillus was observed in the fish intestines of the PLA group, indicating increased utilization capacity of intestinal flora for lactic acid production during PLA degradation. Metabolomics showed that the tricarboxylic acid pathway was up-regulated in the PLA group compared with that in the PET group, providing evidence of energy compensation. However, more ingested PLA MPs caused more significant histological damage to fish intestines than PET MPs. Therefore, the ecological risks of bio-based plastics still require attention.

Nanoplastics induce neuroexcitatory symptoms in zebrafish (Danio rerio) larvae through a manner contrary to Parkinsonian's way in proteomics.

Although nanoplastics (NPs) can penetrate the blood-brain barrier and accumulate in the brain, the neurotoxicity of these particles and the mechanisms associated with their unique physio-chemical properties have yet to be sufficiently ascertained. In this study, we assessed the neuroexcitatory symptoms of zebrafish (Danio rerio) larvae treated with polystyrene (PS) NPs based on an examination of locomotory behaviour, dopamine levels, and acetylcholinesterase activity. We found that PS NPs caused oxidative stress and inhibited atoh1a expression in the cerebellum of Tg(atoh1a:dTomato) transgenic zebrafish larvae, thereby indicating damage to the central nervous system. In contrast to the Parkinson's disease (PD) like effects induced by most types of nanoparticles, such as graphene oxide, we established that PS NPs influenced the neuronal proteomic profiles of zebrafish larvae in a manner contrary to the molecular pathways characteristic of PD-like effects, which could be explained by the molecular dynamic simulation. Unlike graphene oxide nanoparticles that promote significant change in the internal structure of neuroproteins, the complex macromolecular polymers of PS NPs promoted the coalescence and increased expression of neuroproteins, thereby plausibly contributing to the neuroexcitatory symptoms observed in treated zebrafish larvae. Consequently, compared with traditional nanoparticles, we believe that the unique physio-chemical properties of NPs could be a potential factor contributing to their toxicity.

Elevated temperature decreases cardiovascular toxicity of nanoplastics but adds to their lethality: A case study during zebrafish (Danio rerio) development.

To highlight the key role of global warming on the toxicity of contaminants, the cardiovascular toxicity of nanoparticles (NPs) was estimated in developing zebrafish (Danio rerio) at different exposure temperatures, and the toxicity mechanisms were explored via multi-omic analyses. Polystyrene NPs (50 nm) at 0.1 mg·L-1 entered zebrafish embryos at 24 h post-fertilization and caused cardiovascular toxicity in the developing zebrafish at 27 ℃. This was explained by the down-regulation of the branched-chain amino acid and insulin signaling pathways owing to induced oxidative stress. Elevated exposure temperatures promoted the accumulation of NPs in developing zebrafish, increased the levels of oxidative stress and enhanced the oxidative phosphorylation rate in mitochondria, thus resulting in an additive effect on the mortality of zebrafish larvae. Notably, elevated exposure temperatures reduced the cardiovascular toxicity of NPs, as the effective concentration of NPs for inhibiting embryonic heartbeat rate increased from 0.1 mg·L-1 at 27 ℃ to 1.0 mg·L-1 at 30 ℃. Experiments of transgenic zebrafish Tg(myl7:GFP) and multi-omic analyses revealed that elevated temperatures enhanced the myocardial contractility of larvae, thus reducing the cardiovascular toxicity of NPs. However, the health risks of enhanced myocardial contraction caused by NP exposure at elevated temperatures requires further consideration.

Effects of temperature on the toxicity of waterborne nanoparticles under global warming: Facts and mechanisms.

Global climate change is predicted to increase the average temperature of aquatic environments. Temperature changes modulate the toxicity of emerging chemical contaminants, such as nanoparticles (NPs). However, current hazard assessments of waterborne NPs seldom consider the influence of temperature. In this review, we gathered and analyzed the effects of temperature on the toxicity of waterborne NPs in different organisms. There was a general decrease in bioavailability with increasing temperature in algae and plants due to NPs aggregation, thus, reducing their toxicities. However, the agglomerated large particles caused by the increase in temperature induce a shading effect and inhibit algal photosynthesis. The toxicity of NPs in microorganisms and aquatic animals increases with increasing temperature. This may be due to the significant influence of high temperature on the uptake and excretion of chemicals across membranes, which increase the production of reactive oxygen species and enhance oxidative damage to organisms. High temperature also affect the formation and composition of a protein corona on NPs, altering their toxicity. Our results provide new insights into the toxicity of NPs in the context of global warming, and highlight the deficiencies of current research on NPs.

Polystyrene microplastics inhibit the neurodevelopmental toxicity of mercury in zebrafish (Danio rerio) larvae with size-dependent effects.

Insufficient evidence exists regarding the effects of microplastics (MPs) on the neuronal toxicity of heavy metals in the early stages of organisms. Herein, the effects of micro-polystyrene (µ-PS; 157 µm) and nano-polystyrene (n-PS; 100 nm) particles on the neurodevelopmental toxicity of mercury (Hg) in zebrafish embryos were compared. Zebrafish embryos exposed to Hg at the concentration of 0.1 mg L-1 revealed blood disorders, delayed hatching, and malformations such as pericardial oedema and tail deformity. The length of the larval head was significantly reduced (P < 0.01) and in vivo expression of atoh1a in the cerebellum of neuron-specific transgenic zebrafish Tg(atoh1a:dTomato) larvae was inhibited by 29.46% under the Hg treatment. Most of the toxic effects were inhibited by the combined exposure to µ-PS or n-PS with Hg, and n-PS decreased the neurodevelopmental toxicity of Hg more significantly than µ-PS. Metabolomic analysis revealed that in addition to inhibiting the amino acid metabolism pathway as in the µ-PS+Hg treatment, the n-PS+Hg treatment inhibited unsaturated fatty acid metabolism in zebrafish larvae, likely because of a greater reduction in Hg bioavailability, thus reducing the oxidative damage caused by Hg in the larvae. The combined effects of MPs and heavy metals differ greatly among different species and their targeted effects. We conclude that the combined toxicity mechanisms of MPs and heavy metals require further clarification.

Investigation of microplastic pollution on paddy fields in Xiangtan City, Southern China.

Microplastics (MPs) have become a hot issue of environmental pollution. However, insufficient evidence exists regarding the distributions and fates of MPs in terrestrial environment, especially in farmlands. The distributions of MPs in paddy fields were investigated in Xiangtan City, a typical rice production area in China. The abundance of MPs in paddy seedling raising fields was 3805 ± 511 n·kg-1, which increased by approximately 9 times than that in common paddy fields. Transparent films became the dominant forms due to the huge usage of mulching films, corresponding to that the proportion of polyvinyl chloride (PVC) increased to 17% there. Moreover, an industrial plant nearby also contributed considerably to the MP pollution; the proportion of PVC (33%) in the paddy fields nearby increased to approximately 4 times of common paddy fields, while polyvinyl alcohol (PVA; 13%) used as an important chemical raw material to synthesis in various applications was uniquely detected there. These results highlight the input of MPs from agricultural and industrial activities in farmlands. Their contributions to the MP pollution in farmlands should be continuously investigated.

A review of interactions of microplastics and typical pollutants from toxicokinetics and toxicodynamics perspective.

The widespread microplastics (MPs) pollution has become a concerning environmental issue. The interactions between MPs and typical pollutants may change the bioaccumulation, and toxicity of pollutants, leading to high uncertainty in risk assessment. Still, significant gaps remain in the knowledge available to integrate these interactions in the perspectives of toxicokinetics (TK) and toxicodynamics (TD), which is also an essential part of quantitative toxicological research. This review systematically summarizes the interaction between MPs and typical pollutants in TK and TD processes. MPs can be acted as the vector or sink of pollutants to increase or decrease their bioaccumulation, and also may not affect their bioaccumulation due to no interaction. The adverse outcome pathway (AOP) framework enables novel approaches for determining the interaction between MPs and pollutants in the TD process. MPs can directly or indirectly enhance, reduce and not affect the toxicity of pollutants. A series of factors influencing the interaction in TK and TD processes are summarized, including MPs characteristics and exposure scenarios. TK-TD approach can quantitatively understand the interaction between MPs and pollutants based on the mechanism. Given the current knowledge gap in TK and TD processes, future perspectives on combined exposure research are proposed.

Pulmonary toxicology assessment of polyethylene terephthalate nanoplastic particles in vitro.

Nanoplastics are more likely to be suspended in air and pose a risk of respiratory exposure. However, the early health effects of low-dose nanoplastics on the respiratory system, which are expected to reflect the risk of atmospheric nanoplastics, need to be further evaluated. In this study, nanoparticles of polyethylene terephthalate, a representative plastic polymer in air, were prepared by a precipitation method. The toxicity impacts of nano-PET at environmental concentrations on the human lung carcinoma cell A549 cells were evaluated. Although the nano-PET was identified to enter the cells by confocal microscope observation and alkali-assisted thermal depolymerization coupled with LC-MS/MS analysis, the nano-PET exhibited low toxicity on mitochondrial membrane potential levels and cell apoptosis. At low concentrations of 0.10 and 0.98 µg/mL, the nano-PET had a slight promotion effect on cell viability, while an inhibitory effect on cell viability presented at higher nano-PET concentrations of 98.40 and 196.79 µg/mL. The cell survival rate at 98.4 and 196.79 µg/mL of nano-PET are lower than that of the control, and significant oxidative stress in cells caused by the nano-PET exposure at 49.2 µg/mL was observed. A decrease tendency of mitochondrial membrane potential with the increasing nano-PET exposure presents, which is consistent with the change of reactive oxygen species. Furthermore, nano-PET at ≦ 98.4 µg/mL could not increase the sum of apoptotic in the cells, but the late apoptotic cells increased with the increase of the exposure dose. The major mechanism of the toxic effect of nano-PET on cells may be the increase of reactive oxygen species caused by oxidative stress, which in turn induces a decrease in the mitochondrial membrane potential. This study provides information on the toxicity of nano-PET at environmental concentrations in human lung cells, which helps to enrich the risk cognition of nanoplastics in the respiratory system.

Diet preference of zebrafish (Danio rerio) for bio-based polylactic acid microplastics and induced intestinal damage and microbiota dysbiosis.

The ingestion of petroleum-based microplastics (MPs) by aquatic animals and their toxicological effects are of wide concern. However, the ecological risks of bio-based MPs to aquatic animals remain largely unknown. In the present study, zebrafish (Danio rerio) were exposed to MPs of polylactic acid (PLA), the most widely used bio-based plastic, and polyethylene terephthalate (PET), a high-production volume petroleum-based plastic. PLA MPs were more actively ingested by fish than PET MPs. The abundance of PLA MPs in fish intestines was approximately 170 times greater than that of PET MPs after one day of exposure. The ingestion of PLA MPs caused gastrointestinal damage in zebrafish. In addition, the ingestion of PLA MPs induced specific changes in the diversity of intestinal microbiota and promoted species closely linked with energy metabolism, cellular processes, and fish diseases. This might have been related to the depolymerization of PLA in the digestive tract, which decreased the intestinal pH and changed the carbon source structure. Overall, bio-based MPs may have different ecological effects on aquatic animals than traditional petroleum-based MPs.

Immunotoxicity responses to polystyrene nanoplastics and their related mechanisms in the liver of zebrafish (Danio rerio) larvae.

Nanoplastics in aquatic environments may induce adverse immunotoxicity effects in fish. However, there is insufficient evidence on the visible immunotoxicity endpoints in the larval stages of fish. The liver plays an important role in systemic and local innate immunity in the fish. In this study, the hepatic inflammatory effects of polystyrene (PS) nanoplastic particles (NPs: 100 and 50 nm) and micron PS particles on transgenic zebrafish (Danio rerio) larvae were estimated using fluorescent-labeled neutrophils, macrophages, and liver-type inflammatory binding protein (fabp10a). Particles with smaller size induced higher aggregations of neutrophils and apoptosis of macrophages in the abdomen of the larvae, corresponding to greater hepatic inflammation in the larvae. NPs increased the expression of fabp10a in the larval livers in a dose- and size-dependent manner. PS particles of 50 nm at a concentration of 0.1 mg·L-1 increased the expression of fabp10a in the larval liver by 21.90% (P < 0.05). The plausible mechanisms of these effects depend on their distribution and the generation of reactive oxygen species in the larvae. Metabonomic analysis revealed that the metabolic pathways of catabolic processes, amino acids, and purines were highly promoted by NPs, compared to micron PS particles. NPs also activate steroid hormone biosynthesis in zebrafish larvae, which may lead to the occurrence of immune-related diseases. For the first time, the liver was identified as the target organ for the immunotoxicity effects of NPs in the larval stage of fish.

Size-dependent impact of polystyrene microplastics on the toxicity of cadmium through altering neutrophil expression and metabolic regulation in zebrafish larvae.

Insufficient evidence exists regarding the visible physiological toxic endpoints of MPs exposures on zebrafish larvae due to their small sizes. Herein, the impacts of micro-polystyrene particles (µ-PS) and 100 nm polystyrene particles (n-PS) on the toxicity of cadmium (Cd) through altering neutrophil expressions were identified and quantified in the transgenic zebrafish (Danio rerio) larvae Tg(lyz:DsRed2), and the effects were size-dependent. When exposed together with µ-PS, the amount of neutrophils in Cd treated zebrafish larvae decreased by 25.56% through reducing Cd content in the larvae. By contrast, although n-PS exposure caused lower Cd content in the larvae, the expression of neutrophils under their combined exposure remained high. The mechanism of immune toxicity was analyzed based on the results of metabonomics. n-PS induced high oxidative stress in the larvae, which promoted taurine metabolism and unsaturated fatty biosynthesis in n-PS + Cd treatment. This observation was accordance with the significant inhibition of the activities of superoxide dismutase and catalase enzymes detected in their combined treatment. Moreover, n-PS promoted the metabolic pathways of catabolic processes, amino acid metabolism, purine metabolism, and steroid hormone biosynthesis in Cd treated zebrafish larvae. Nanoplasctis widely coexist with other pollutants in the environment at relatively low concentrations. We conclude that more bio-markers of immune impact should be explored to identify their toxicological mechanisms and mitigate the effects on the environment.

Toxicities of microplastic fibers and granules on the development of zebrafish embryos and their combined effects with cadmium.

Toxicity of microplastics (MPs) in granular form to aquatic animals has been frequently tested, whereas the effects of fibrous MPs remain further explored. In this study, the effects of polyethylene terephthalate granular particles (p-PET, approximately 150 µm in diameter) and fibers (f-PET, approximately 3-5 mm in length and 20 µm in diameter) on the development of zebrafish embryos and their joint effects with cadmium (Cd) were compared. p-PET and f-PET accelerated the velocities of blood flow and heart rate and inhibited hatching in zebrafish embryos because of their barrier effects on the channels in the embryonic chorion and enhanced the mechanical strength of the chorion. The Cd content in the chorion increased by p-PET due to the adsorption of p-PET on the chorion. By contrast, more f-PET dissociated in culture medium and resulted in low Cd content in the chorion. Given that chorion can effectively block p-PET and f-PET, the Cd accumulation in eggs significantly decreased (p < 0.05) under p-PET/f-PET and Cd combined treatment because of the reduction in the bioavailability of Cd. Therefore, p-PET and f-PET decreased the toxicities of Cd on all the target endpoints in this study, and the detoxification effect of f-PET at 72 hpf was more significant than that of p-PET. These results suggest that the toxicity induced by MPs might be form-related.

[Distribution of Micro-plastics in the Soil Covered by Different Vegetation in Yellow River Delta Wetland].

Micro-plastics (MPs) pollution has been a hotspot in soil environment. To explore the correlation of the vegetation cover and the distribution of MPs in Yellow River Delta wetland, the characters of MPs in the soil sampled at 16 sites where reed (Phragmites communis, a low-salt dominant species) and Suaeda salsa (a high-salt dominant species) covered were investigated. The abundance of MPs here ranged to 80-4640 n·kg-1, and the particle size ranged to 13 µm-5 mm. The main components of MPs with large size were polyethylene (PE), polyethylene terephthalate (PET) and polystyrene (PS), and the content of PET ranged to 0.22-1.16 µg·kg-1. The barrier effect of reed on MPs was higher than that of Suaeda salsa. The average abundance of MPs and PET contents at the sites where reed covered were 1423 n·kg-1 and 0.62 µg·kg-1, and they mainly consisted of small particles with a size less than 50 µm. The average abundance of MPs and PET contents at the site Suaeda salsa covered were 584 n·kg-1 and 0.33 µg·kg-1, and they mainly consisted of fragments and fibers with a size ranged to 100-1000 µm. The abundance of MPs in the soil was significantly correlated with the growth statues of the vegetations (P=0.001). Therefore, the distribution of MPs in the soil in the same area covered by different vegetation might be spatial different.

Barrier function of zebrafish embryonic chorions against microplastics and nanoplastics and its impact on embryo development.

Embryonic stage is important for the development of aquatic animals, and embryonic chorion is an efficient barrier against exogenous pollutants. The efficient barrier function of zebrafish (Danio rerio) embryonic chorions against micro- and nano- polystyrene (PS) particles was observed. Embryonic chorions presented high affinity to PS particles. The covering layer of PS particles on the outer surface of chorions affected the patency of pores in chorions, and the nano- PS particles exerted a considerable effect. The accelerated heart rate and blood flow velocity in the embryos indicated that the PS particles adhering to embryonic chorions might cause an internal hypoxic microenvironment in the embryos. The coating of PS particles on embryonic chorions also resulted in delayed hatching of the embryos. The observed development toxicity induced by the nano- and micro-PS particles was confirmed via the expressions of metabolic pathways related to antioxidant system. The pathways of biosynthesis of unsaturated fatty acid, linoleic acid metabolism and alanine, and aspartate and glutamate metabolism extensively altered when the embryos were exposed to PS particles, especially to the nano- PS particles. Although micro- and nano- plastic particles can be efficiently blocked by embryonic chorions, they can still affect the early development of aquatic organisms.

Microplastics in Yellow River Delta wetland: Occurrence, characteristics, human influences, and marker.

Microplastics (MPs) are widespread in the environment including coastal wetlands. The influence of different types and intensities of human activities on the occurrence of MPs in coastal wetlands is still unknown. The aim of this study was to investigate the distribution of MPs and the contribution of human activities in different areas of Yellow River Delta wetland. MPs were widely detected in different areas of the wetland even in the protection area with little human activities. Direct human activities resulted in more severe MPs contamination in the protection area than the tourism area. In the soil of different areas, the MPs abundances ranged from 136 to 2060 items/kg. The concentrations of polyethylene terephthalate (PET) ranged from 536 to 660 µg/kg, and the concentrations of polycarbonate (PC) ranged from 83.9 to 196 µg/kg. The MP abundances of the three areas had significant correlations with PET concentrations. These results indicate that the direct influence of human activities has much greater contribution than indirect influence. These results also suggest that PET concentration can be used as a potential marker of MPs contamination in wetland soils.

Prevalence of non-syndromic orofacial clefts: based on 15,094,978 Chinese perinatal infants.

Non-syndromic orofacial clefts (NSOFC), which include cleft lip and palate (CLP), cleft lip only (CLO), and cleft palate only (CPO), contains a range of disorders affecting the lips and oral cavity. No systematic review and meta-analysis has been carried out to synthesize the prevalence of NSOFC in Chinese perinatal infants. We aimed to quantify and understand the variation of prevalence national and regional levels. Four English databases and four Chinese databases were searched using a comprehensive search strategy from inception to April 2017. The random effect model was used for this meta-analysis. To determine the sources of heterogeneity, subgroup analyses and meta-regression were conducted based on different categories. The protocol has been pre-registered in the PROSPERO, number CRD42017062293. 110 studies, including 15,094,978 Chinese perinatal infants, were eligible for inclusion. The pooled prevalence rate for NSOFC was 1.67‰ (95% CI 1.53-1.82), varying with provinces. The pooled prevalence estimate was 0.56‰ (0.50-0.63) for CLO, 0.82‰ (0.73-0.90) for CLP, and 0.27‰ (0.24-0.30) for CPO. Significant associations were found between overall prevalence estimates and survey year and study region. The prevalence of NSOFC was severe in Chinese perinatal infants, varying with provinces. The results will serve as a baseline for future assessment of the overall effectiveness of NSOFC control, and will also support and inform health policy for planning and helping health debates.

Hepatotoxicity of benzotriazole and its effect on the cadmium induced toxicity in zebrafish Danio rerio.

As an emerging contaminant, 1-H-benzotriazole (1H-BTR) has been detected in the engineered and natural aquatic environments, which usually coexists with heavy metals and causes combined pollution. In the present study, wild-type and transgenic zebrafish Danio rerio were used to explore the acute toxicity as well as the single and joint hepatotoxicity of cadmium (Cd) and 1H-BTR. Although the acute toxicity of 1H-BTR to zebrafish was low, increased expression of liver-specific fatty acid binding protein was observed in transgenic zebrafish when the embryos were exposed to 5.0 µM of 1H-BTR for 30 days. Besides, co-exposure to 1H-BTR not only reduced the acute toxic effects induced by Cd, but also alleviated the Cd-induced liver atrophy in transgenic fish. Correspondingly, effects of combined exposure to 1H-BTR on the Cd-induced expressions of several signal pathway-related genes and superoxide dismutase and glutathione-s-transferase proteins were studied. Based on the determination of Cd bioaccumulation in fish and the complexing stability constant (ß) of Cd-BTR complex in solution, the detoxification mechanism of co-existing 1H-BTR on Cd to the zebrafish was discussed.

Fe(III) and Fe(II) induced photodegradation of nonylphenol polyethoxylate (NPEO) oligomer in aqueous solution and toxicity evaluation of the irradiated solution.

Photodegradation of nonylphenol tri-ethoxylate (NPEO3) in aqueous solution, and the effects of Fe(III) or Fe(II) were studied. The increasing degradation kinetics of NPEO3 were observed when 500µM Fe(III) or Fe(II) was present in the solutions. Altered formation of NPEO oligomers with shorter EO chains, including nonyphenol (NP), NPEO1 and NPEO2, was observed in water and in solutions containing Fe(III) or Fe(II). The molar percentage yields of NP and NPEO1,2 production from NPEO3 photodegradation were approximately 20% in NPEO3 solution, while NPEO3 solution with Fe(III), this percentage increased to approximately 50%. In solution with Fe(II), the molar balance between the photodegradation of NPEO3 and the production of NP and NPEO1,2 was observed. A luminescent bacterium, Vibrio fischeri, was used to identify changes in the toxicity of NPEO3 solutions during the photodegradation process under different conditions, while dose addition (DA) model was used to estimate the toxicity of products. Toxicity of NPEO3/water solution increased significantly following the irradiation of UVA/UVB mixture. In contrast, obviously decreasing toxicity was observed when NPEO3 underwent photodegradation in the presence of Fe(III).

[Changes of Microbial Community Structure in Activated Sludge Bulking at Low Temperature].

The mechanism of activated sludge bulking in Zhengzhou wastewater treatment plant was studied by measurement of water quality parameters and high-throughput sequencing technology. The change of SVI value was significantly negatively correlated with the seasonal temperature variation, and sludge bulking was easy to occur during December to the next April, but the water quality was not affected. The result verified by high-throughput sequencing technology analysis showed that the microbial community structure of bulking sludge was significantly different from that of the non-bulking one. The dominant filamentous bacteria in the bulking sludge in this plant were Saprospiraceae and Flavobacterium. Therefore, the activated sludge bulking in this wastewater treatment plant was caused by the propagation of filamentous bacteria at low temperature.