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This study used the officially released data by the Chinese air quality monitoring network to analyze the pollution characteristics of six air pollutants (PM2.5, PM10, SO2, NO2, CO, and O3) for 29 cities in the Central Plains Economic Zone (CPEZ; China) in 2015. During 2015, serious particulate matter (PM) pollution often occurred, and the concentrations of PM2.5 and PM10 were 77 μg m−3 and 128 μg m−3, respectively. Air pollutants were at higher concentrations in the northern cities than those in the southern region of the CPEZ, and the correlation among the cities indicated that there was regional pollution in CPEZ. Generally, PM, SO2, NO2, and CO showed similar seasonal characteristics and the highest and lowest concentrations appeared in winter and summer, respectively. In addition, we used the HYSPLIT model and trajStat model to identify the potential source contribution function and concentration-weighted trajectory of Zhengzhou, the central city of CPEZ. More serious air pollution occurred when air masses were transported from the west of the CPEZ. Shaanxi Province, Hubei Province, Anhui Province and the northwest of the CPEZ were found to be the main exogenous sources of total PM with contributions of > 100 μg m−3 PM2.5 and > 180 μg m−3 PM10. Therefore, the concentrations of PM in 2015 at Zhengzhou were probably influenced by both long-distance transmission and local emissions.

Bioaerosols are an important component of particulate matter in the atmosphere and are harmful to human health. In this study, the concentration, size distribution, and factors influencing culturable airborne bacteria and fungi in the atmosphere were investigated using a six-stage impactor device in the city of Xinxiang, China, during the winter season. The results revealed that the concentration of culturable airborne bacteria and fungi varied significantly during the sampling period: 4595 ± 3410 and 6358 ± 5032 CFU/m3, respectively. The particle sizes of the bioaerosols were mainly within stage V (1.1-2.1 μm), and fine particulate matter accounted for 45.9% ± 18.9% of airborne bacteria and 52.0% ± 18.5% of airborne fungi, respectively. With the deterioration of air quality, the concentration of airborne fungi gradually increased, and that of airborne bacteria increased when the air quality index was lower than 200 and decreased when it was higher than 200. With respect to the diurnal variation pattern of bioaerosol concentration, the highest and lowest concentrations were registered at night and noon, respectively, probably because of changes in ultraviolet radiation intensity. Bioaerosol concentration positively correlated with humidity, concentration of PM2.5, PM10, SO2, and NO2 and negatively correlated with O3 concentration. The risk of exposure of humans to the airborne bacteria was primarily associated with the respiratory inhalation pathway, and the risk of skin exposure was negligible. These results should improve our understanding of the threat of bioaerosols to public health.

Herein, we fabricated an ultra-light graphene aerogel/Bi2WO6 (GA/BW) photocatalyst with macroscopic 3D architecture via in-situ synthesis, which had preferable activity for organic wastewater purification. We carefully characterized the physical and chemical properties of this macroscopic 3D architecture, finding that the flower-like Bi2WO6 (BW) uniformly loaded on the surface of GA, improving the visible light absorption performance, photon-generated carrier separation efficiency and organic contaminants adsorption ability, as well as photocatalytic ability compared with that of pure BW powders. When the mass ratio of GA and BW is 6:8, the degradation efficiency of rhodamine B (RhB) and sulfanilamide (SN) can reach 97.49% and 55.81% in 120 min, respectively. The as-prepared GA/BW composite is ultra-light and suitable for practical wastewater purification due to its flexibility and recyclability. The trapping experiments involved the main active species in the photocatalytic process were carried out and the results indicated that the h+ is the dominant oxidative species for the degradation of RhB.

Black carbon (BC) in surface sediments from Henan section of Yellow River and Huaihe River, China, was determined. Average content of BC in Huaihe River was 0.33%, higher than that in Yellow River ...

In this study, hexahydroxy-stannates (MSn(OH)6 (M = Cu, Zn)) with d10-d10 configuration were synthesized by using a simple coprecipitation method at room temperature to investigate the effect of cationic substitution with similar ionic radius. The obtained samples are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET) surface area analysis, Fourier transform-infrared spectra (FT-IR) and UV–Vis diffuse reflectance spectroscopy, etc. The photocatalytic properties of the obtained samples were evaluated by the degradation of methylene blue (MB). It is found that the difference of M2+ in MSn(OH)6 bring a change in crystal structure, morphology, chemical bond energy and photocatalytic property. The obtained MSn(OH)6 nanoparticles can be used to the preparation of the different mixtures by simple calcination, but the photocatalytic performance could not be improved after the heat treatment duo to the change of crystal structure by forming the mixture of oxide. These results suggested that metal cations in A sites could induce lattice distortion of the hexahydroxy-stannates with d10-d10 configuration although they have the similar ionic radius, accordingly inducing the change of morphology, chemical bond energy and photocatalytic activity.

Carbon sources are an important parameter in wastewater treatment processes and are closely related to treatment efficiency and nitrous oxide (N2O) emissions. In this study, three parallel sequencing batch reactors (SBRs) were processed with acetic acid, propionic acid, and a 1:1 mixture of both acids (calculated in COD) to study the effect of carbon sources on N2O generation and sludge properties (including intracellular polymer content, extracellular polymeric substance (EPS) composition, particle size distribution, settleability, and microbial community structure). The results showed that the highest COD, NH4+-N, and TP removal efficiencies (92.2%, 100%, and 82.3%, respectively) were achieved by the reactor with mixed acid as the carbon source, whereas the reactor using acetic acid had the highest TN removal rate (82.6%) and the lowest N2O-N conversion rate (1.4%, based on TN removal). The reactor with the carbon source of mixed acid produced the highest polyhydroxyalkanoate (PHA) content, which led to an increase in N2O generation from the aerobic denitrification pathway. The SBR with mixed acid carbon source also had the highest concentration of EPS, which resulted in the largest particle size and the lowest settleability of sludge flocs among the SBRs. Microbial analysis results revealed that the difference in carbon sources resulted in a variation in the microbial community as well as in the relative abundances of functional microbes involved in biological nitrogen removal processes. The mixed acid promoted the development of ammonia-oxidizing bacteria (AOB), which conducted the primary N2O generation pathway of aerobic denitrification bioreactions. The carbon source of acetic acid promoted the growth of denitrifying bacteria (DNB), which led to the highest TN removal rate. This study provides a comprehensive understanding of the effects of carbon sources on N2O generation and sludge properties for WWTPs.

The degradation of diclofenac sodium (DCF) in pre-magnetization Fe0/persulfate (Pre-Fe0/PS) and Fe0/PS systems were studied in detail in this study. The influencing operational conditions (initial PS dosage, Fe0 dosage, and pH) were studied for their effects on the DCF degradation. The removal rate constant for DCF by the Pre-Fe0/PS system was 2.1–6.2 times higher than that of the Fe0/PS system. A higher TOC removal efficiency (81.5%) was observed during the mineralization of DCF in the Pre-Fe0/PS process than that of the Fe0/PS process (70%). The results of electron paramagnetic resonance (EPR) confirmed that the Pre-Fe0/PS system could produce much more •OH and SO4−• at a faster rate than the Fe0/PS system. Moreover, the degradation mechanism of DCF by the Pre-Fe0/PS process was elucidated. This work would provide a perspective on the Pre-Fe0/PS process for efficient degradation of DCF, exhibiting advantages to removing DCF, such as broaden the range of working pH and reduce the amount of chemicals. So, it is an efficient and potential method to remove DCF from wastewater by the Pre-Fe0/PS process.

A total of 150 samples were collected from 25 sites in the Yellow River of Henan Province during 2014 to demonstrate the impact of suspended sediment (SS) load on the behavior of semi-volatile organic compounds (SVOCs) in the Yellow River. The average concentrations of SS ranged from

Emerging applications for environmental purification require agents that not only possess high decontamination efficiency, but also are capable of withstanding mechanical deformation without secondary pollution and degradation of performance. To this end, we have controlled synthesis of mechanically flexible graphene aerogel (GA) by vacuum freeze-drying of their hydrogel precursors obtained from heating the aqueous mixtures of graphene oxide (GO) and Vitamin C (VC) without stirring. Through the adaptable process conditions, such as the particle size of carbon, GO concentration, dosage of reducing agent and solution pH, the highly porous, ultralight and mechanically flexible GA are synthesized. Owing to the porous, robust and stable structure, the resulting GA show very promising performance in water purification including enrichment of organic liquid solvents (alcohols, oil and alkanes), removal of hexavalent chromium Cr(VI) and purified industrial wastewater, as well as flexible conductors. The successful creation of the GA may provide new insights into the design of carbon-based aerogels for various applications, as the GA can be prepared via a very simple procedure and available in macroscopic diverse morphologies with tunable porosity.

This study was conducted in order to explore the seasonal characteristics, climate impact and source of PM2.5 in Xinxiang, China. Daily PM2.5 samples were collected at urban site from January to December in 2015. Average PM2.5 concentration was 100.6 ± 65.8 μg m−3 in Xinxiang, which was several times higher than China Ambient Air Quality Standards (GB3095-2012). Secondary inorganic aerosols (SIA) constituted 70% of the total ionic concentrations. The average concentration of SO42- was 6.4 ± 12.0 μg m−3, which ranked the highest among the water-soluble ions analyzed. Seasonal variations of PM2.5 and its major chemical components were significant, most of them with high values in winter and the lowest values in summer, especially with heavier PM2.5 events (more than 200 μg/m3) in December. SIA and OC on polluted days were 2.1–2.3 times higher than those of on clean days. It was estimated that Fe, Li, Na, Mg, Al, K, Ca and Sr were emitted from crustal sources and Pb, Cr, Ni, Cu, Zn, As, Cd and V were emitted from anthropogenic emissions using the EF values. Analysis using the tracer and PCA/MLR revealed that vehicle exhausts were the most important source of PM2.5, which contributed 26.9% of PM2.5 over the whole study period. This study provides detailed composition data and first comprehensive analysis of PM2.5 in Xinxiang during a whole year.

The levels, spatial variation, congener profiles, impact factors, and ecological risk of polychlorinated biphenyls (PCBs) in the sediment from the Yellow River of Henan section, China, were investigated in this paper. Total concentration of 31 PCBs and seven indicator PCBs varied from ND to 1015 pg g-1 and ND to 423 pg g-1, respectively. Compared with other aquatic environments around China, PCB levels in the studied area were relatively low. Spatial variations revealed that tributaries possessed higher PCB levels, in comparison to mainstream, which acted as input sources of PCBs in the mainstream. The homolog profiles were dominated by lighter PCBs (Tri-PentaCBs), contributing above 70% of total PCBs. Correlation analysis between PCB concentrations and total organic carbon indicated that local input or atmospheric deposition was the primary controls of spatial variation of PCBs. According to simple sediment quality guidelines (SQG), the risks posed by PCBs in the sediments might be negligible.

Halogenated flame retardants (HFRs), mainly encompassing polybrominated diphenylethers (PBDEs), dechlorane plus (DP) and emerging bromine flame retardants (EBFRs), are widely employed nowadays in daily lives. However, limited knowledge has been gained to date on the concentrations and distributions of HFRs in particular within certain regions. In the present study, legacy and emerging HFRs were systematically measured in suspended particle matter (SPM) and sediments collected in 2014 from the middle and lower reach of the Yellow River in Henan province. The total concentrations of HFRs in SPM among the three seasons were 42.2±91.2ngg-1, which was far higher than the corresponding values of HFRs in sediments (1.82±2.94ngg-1). In this study, PBDEs, DP and EBFRs in sediment almost exhibited relatively lower levels as compared to those found in other studies, where the limited usage of HFRs in the middle and lower stream of the Yellow River was probably the major impact factor. EBFR was the predominate pollutant from SPM and sediments in most of the sampling sites, suggesting that EBFRs were widely used nowadays as substitute materials of 'old' FRs. The mean concentration values of DBDPE/BDE-209 in SPM and sediments were apparently higher than those of previous studies. Furthermore, it is interesting to reveal that herein almost all of the HFR concentrations were unrelated to the population and GDP, which might be attributed to the characteristics of 'elevated stream' of the Yellow River as well as the complex river systems in Henan province.

The thermokinetics of Chlorella pyrenoidosa (CP) devolatilization were investigated based on iso-conversional model and different distributed activation energy models (DAEM). Iso-conversional process result showed that CP devolatilization roughly followed a single-step with mechanism function of f(α) = (1 − α)3, and kinetic parameters pair of E0 = 180.5 kJ/mol and A0 = 1.5E + 13 s−1. Logistic distribution was the most suitable activation energy distribution function for CP devolatilization. Although reaction order n = 3.3 was in accordance with iso-conversional process, Logistic DAEM could not detail the weight loss features since it presented as single-step reaction. The un-uniform feature of activation energy distribution in Miura-Maki DAEM, and weight fraction distribution in discrete DAEM reflected weight loss features. Due to the un-uniform distribution of activation and weight fraction, Miura-Maki DAEM and discreted DAEM could describe weight loss features.

The concentrations and compositions of polychlorinated naphthalenes (PCNs) in sediments and suspended particulate matters (SPM) in the middle and lower reaches of the Yellow River were investigated. The mean concentrations of PCNs were 7.15 ± 19.3 ng/g dw in the sediment and 38.1 ± 58.4 ng/g dw in SPM. Tri- and tetra-CNs were the dominant homologue groups in most samples. CN-23 was the predominant congener at all sites, and its presence may be attributed to coal combustion. Combustion indicators showed that local combustion source was the main contributor to the PCN concentrations. These sources were related to the energy structure of this region, where coal is the most important energy resource. Human activities, including industrial thermal processes and reservoir construction, were major factors affecting PCN levels and hydrological conditions, which strongly influenced the environmental fate of PCNs in the Yellow River.

The pollution characteristics of PM2.5 and correlation analysis with meteorological parameters in Xinxiang during the Shanghai Cooperation Organization Prime Ministers’ Meeting were investigated. During the whole meeting, nine PM2.5 samples were collected at a suburban site of Xinxiang, and the average concentration of PM2.5 was 122.28 μg m−3. NO3 −, NH4 +, SO4 2− accounted for 56.8% of the total water-soluble ions. In addition, with an exception of Cl−, all of water-soluble ions decreased during the meeting. Total concentrations of crustal elements ranged from 6.53 to 185.86 μg m−3, with an average concentration of 52.51 μg m−3, which accounted for 82.5% of total elements. The concentrations of organic carbon and elemental carbon were 7.71 and 1.52 μg m−3, respectively, lower than those before and after the meeting. It is indicated that during the meeting, limiting motor vehicles is to reduce exhaust emissions, delay heating is to reduce the fossil fuel combustion, and other measures are to reduce the concentration of PM2.5. The directly dispersing by mixing layer height increase and the indirectly reducing the formation of secondary aerosol by low relative humidity, and these are the only two key removing mechanisms of PM2.5 in Xinxiang during the meeting.

Twenty-four PM 2.5 samples were collected at a suburban site of Xinxiang during Chinese Spring Festival (SF) in 2015. 10 water-soluble ions, 19 trace elements and 8 fractions of carbonaceous species in PM 2.5 were analyzed. Potential sources of PM 2.5 were quantitatively apportioned using principal component analysis (PCA)-multivariate linear regressions (MLR). The threat of heavy metals in PM 2.5 was assessed using incremental lifetime cancer risk (ILCR). During the whole period, serious regional haze pollution persisted, the average concentration of PM 2.5 was 111 ± 54 μg m − 3 , with 95.8% and 79.2% of the daily samples exhibiting higher PM 2.5 concentrations than the national air quality standard I and II. Chemical species declined due to holiday effect with the exception of K, Fe, Mg, Al and K + , Cl − , which increased on Chinese New Year (CNY)'s Eve and Lantern Festival in 2015, indicating the injection of firework burning particles in certain short period. PM 2.5 mass closure showed that secondary inorganic species were the dominant fractions of PM 2.5 over the entire sampling (37.3%). 72-hour backward trajectory clusters indicated that most serious air pollution occurred when air masses transported from the Inner Mongolia, Shanxi and Zhengzhou. Health risk assessment revealed that noncancerous effects of heavy metals in PM 2.5 of Xinxiang were unlikely happened, while lifetime cancer risks of heavy metals obviously exceeded the threshold, which might have a cancer risk for residents in Xinxiang. This study provided detailed composition data and first comprehensive analysis of PM 2.5 during the Spring Festival period in Xinxiang.

Mercury (Hg), six alkyl esters of p-hydroxybenzoic acid (parabens), and their metabolite, 4-hydroxybenzoic acid (PHBA), were simultaneously studied in sediments from the upper Huai River, Henan Province, China. There were higher concentrations of Hg in the surface sediments from the Huai River during the moderate precipitation season (MPS②) as compared to the minimal precipitation (MPS①) and high precipitation seasons (HPS), and as compared to core sediments. The Hg values in all sediments were above the background value. The Hg contents in the tributaries were much higher than those in the mainstream. The concentrations of ∑parabens in the core sediments ranged from 2.45 to 22.2 ng/g while the concentrations of PHBA ranged from 11.3 to 155 ng/g. Methylparaben (MeP) and propylparaben (PrP) were the most commonly detected parabens. Total organic carbon (TOC) and black carbon (BC) played important roles in the distribution of Hg in the surface sediments during the minimal precipitation and high precipitation seasons and affect the distribution of Hg and parabens in core sediments. Sand (>63 μm) was another factor affecting the distribution of Hg and parabens in core sediments. The concentrations of PHBA and Hg in core sediments were positively correlated. Temporal records of Hg and parabens in core sediments reflected local social changes. Hg content in the surface sediments during the MPS② was associated with relatively high ecological risks while parabens in the core sediments were associated with low level risks.

Seventeen PM2.5 samples were collected at Xinxiang during winter in 2014. Nine water-soluble ions, 19 trace elements and eight fractions of carbonaceous species in PM2.5 were analyzed. PM2.5 concentrations and elements species during different periods with different pollution situations were compared. The threat of heavy metals in PM2.5 was assessed using incremental lifetime cancer risk. During the whole period, serious regional haze pollution persisted, and the averaged concentration of PM2.5 was 168.5 μg m−3, with 88.2 % of the daily samples exhibiting higher PM2.5 concentrations than the national air quality standard II. The high NO3 −/SO4 2− ratio suggested that vehicular exhaust made an important contribution to atmospheric pollution. All of organic carbon and elemental carbon ratios in this study were above 2.0 for PM2.5, which might reflect the combined contributions from coal combustion, motor vehicle exhaust and biomass burning. Mean 96-h backward trajectory clusters indicated that more serious air pollution occurred when air masses transported from the Hebei, Shanxi and Zhengzhou. The concentrations of the water-soluble ions and trace elements on haze days were 2 and 1.8 times of those on clear days. The heavy metals in PM2.5 might not cause non-cancerous health issues by exposure through the human respiratory system. However, lifetime cancer risks of heavy metals obviously exceeded the threshold (10−6) and might have a cancer risk for residents in Xinxiang. This study provided detailed composition data and comprehensive analysis of PM2.5 during the serious haze pollution period and their potential impact on human health in Xinxiang.

To evaluate the effects of internal recycle ratio on nitrous oxide (N 2 O) generation, we set up three laboratory-scale anaerobic–anoxic–oxic (A 2 O) wastewater treatment processes, with internal recycle ratios of 100%, 200%, and 300%, respectively. Total nitrogen (TN) removal was markedly enhanced from 45.8% to 61.9%, as the internal recycle ratio increased from 100% to 300%. N 2 O generation was increased from 3.47 to 9.81 × 10 −2 mg/L during the treatment process, with the anoxic section showing the largest N 2 O increment from denitrification. This phenomenon is attributed to the increased amount of nitrate (NO 3 − -N) substrate available for denitrification, due to the increased volume of internal recycle liquid, as well as the increased amount of oxygen, which could restrain the activity of nitrous oxide reductase brought to the anoxic section. Nitrous oxide reductase was more sensitive to oxygen than nitrate and nitrite reductases. Microorganism analysis indicated that the population of nosZ gene-containing bacteria was only slightly affected by the recycle ratio. However, the number of nosZ gene copies decreased as the internal recycle ratio increased from 100% to 300%; this result reveals noticeable decreases in the denitrification capacity of the system for reducing N 2 O to N 2 .

Sludge properties are critical to the treatment performance and potentially correlate with nitrous oxide (N2O) generation during activated sludge processes. The hydrodynamic shear stress induced by aeration has a significant influence on sludge properties and is inevitable for wastewater treatment plants (WWTPs). In this study, the effects of aerobic induced hydrodynamic shear stress on sludge properties, N2O generation, and microbial community structure were investigated using three parallel sequencing batch reactors (SBRs) with identical dissolved oxygen (DO) concentrations. Results showed that with a shear stress increase from 1.5 × 10−2 N/m2 to 5.0 × 10−2 N/m2, the COD and NH4+-N removal rates were enhanced from 89.4% to 94.0% and from 93.9% to 98.0%, respectively, while the TN removal rate decreased from 66.0% to 56.5%. Settleability of the activated sludge flocs (ASFs) also increased with the enhancement of shear stress, due to variation in sludge properties including particle size, regularity, compactibility, and EPS (extracellular polymeric substances) composition. The increase in shear stress promoted oxygen diffusion within the ASFs and mitigated NO2−-N accumulation, leading to a decrease in the N2O–N conversion rate from (4.8 ± 0.3)% to (2.2 ± 0.6)% (based on TN removal). Microbial analysis results showed that the functional bacteria involved in the biological nitrogen removal was closely related with shear stress. The increase in shear stress favored the enrichment of nitrite oxidizing bacteria (NOB) while suppressed the accumulation of ammonia-oxidizing bacteria (AOB) and denitrifying bacteria (DNB).

In this study, the Fe, N co-doped biochar (Fe-N-BC) was prepared by pyrolyzing wheat straw, urea and iron salts and used to activate persulfate (peroxydisulfate, PS) for organic contaminant degradation. Iron oxide doping not only introduced magnetism into the biochar for easy separation, but also influenced its catalytic ability for PS activation. In the Fe-N-BC/PS system, almost all acid orange (AO7) was removed within 90 min with an apparent rate constant (kobs) of 0.114 min−1, which was almost 37 times larger than that of pure N-BC (0.003 min−1). Factors influencing the removal of AO7 were investigated, including PS concentration, catalyst dosage, and initial pH. The Fe-N-BC/PS system had high removal efficiencies for various organic contaminants and showed high resistance to inorganic anions in aquatic environments. The radical quenching studies, electron paramagnetic resonance (EPR) measurements, and electrochemical analyses verified that the mechanism of AO7 degradation in the Fe-N-BC/PS system included both radical and non-radical pathways involving the generation of OH, SO4− , O2− , 1O2, and electron transfer. Additionally, persistent free radicals (PFRs) on the catalysts also related to their catalytic efficiencies. These results demonstrated that the Fe-N-BC/PS system had the potential for wastewater treatment applications.