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In this work, the feasibility and performance of zero valent iron (ZVI) coupled anaerobic microorganisms in nitrogen removal under low organic carbon condition were investigated, through the comparison of mono-ZVI system and mono-cell system. Coupled system showed the highest total nitrogen (TN) removal efficiency of 67.85% with the addition of 15 g L−1 iron shavings at pH 7.0, which was higher than 29.62% in the mono-ZVI system and 43.86% in the mono-cell system. Besides, the activities of nitrate reductase (NAR), nitrite reductase (NIR), nitric oxide reductase (NOR) and nitrous oxide reductase (N 2 OR) were significantly improved at ZVI dosage of 15 g L−1 and pH 7.0, which contributed to the higher TN removal efficiency in coupled system. The extent of sludge granulation was greater in the coupled system than mono-cell system, which benefited to the high operational performance and stability of coupled system. The promoted generation of extracellular polymeric substances (EPS) and formation of iron oxides in the coupled system also took advantages on nitrogen removal through adsorption. In addition, ZVI could largely enrich the functional species related to nitrogen removal in the system at phyla and genera level, which could be reasoned for the enhanced nitrogen removal efficiency. In conclusion, this study will improve the understandings of nitrogen removal in the coupled system and be useful to ensure the application of ZVI-supported biological process in the remediation of farmland drainage. Unlabelled Image • Coupled bio-ZVI system presented better performance on nitrogen removal. • Optimum iron dosage and pH were discussed to reach the desirable nitrogen removal. • ZVI improves the activity of denitrifying enzymes including NAR, NIR, NOR and N 2 OR. • Functional microbes for nitrogen removal were enriched in the coupled system. [ABSTRACT FROM AUTHOR]

Carbon emissions have become a global environmental problem in recent years. It is necessary to explore methods to improve the efficiency of energy consumption and minimize carbon emissions that accompany economic development and rapid urbanization. In this paper, we quantitatively measure the total factor carbon emission performance (TFCP) and the carbon emission mitigation potential (CMP) of 39 industrial sectors in the Beijing–Tianjin–Hebei (BTH) region from 2010 to 2016 by employing a stochastic frontier approach. The results show that the average TFCP value of the 39 industrial sectors in the BTH region was relatively low (0.7733). From 2010 to 2016, the TFCP increased in Beijing, decreased in Tianjin and held steady in Hebei. The entire level of TFCP in Hebei was the greatest, followed by Tianjin and Beijing. The CMP in the BTH region increased slightly during the period 2010–2016. The total CMP of the 39 industrial sectors in the BTH region was 11.03 × 108 t from 2010 to 2016. The industrial sectors were divided into four categories according to the relationship between TFCP and CMP. Belonging to the low TFCP–high CMP quadrant, the Manufacture of Nonmetallic Mineral Products sector and the Production and Distribution of Electric Power and Heat Power sector should attract more attention when formulating carbon reduction policies and related regulations. According to the results, we also present suggestions to strengthen green economic growth and regional sustainable development. Unlabelled Image • A valid frontier model is built to measure TFCP and CMP. • The average TFCP of the 39 industrial sectors was relatively low (0.7733). • The total CMP of industrial sectors was 11.03 × 108 t in the period 2010–2016. • 39 industrial sectors were divided into four categories to support policy-making. [ABSTRACT FROM AUTHOR]

Abstract 2,2′,4,4′-Tetrabromodiphenyl ether (BDE47) is the most abundant PBDE congeners in biological samples. It has strong tendencies to bioaccumulate and potentially endangers development of mammals through oxidative stress. Isoliquiritigenin (ISL), an emerging natural chalcone-type flavonoid, possesses various biological and pharmacological properties, including antioxidant, anti-allergic, anti-inflammatory, anti-tumor and estrogenic activities. The purpose of the study is to explore the antioxidant effect of ISL on the amelioration of developmental anomalies induced by BDE47. Zebrafish (Danio rerio) embryos were exposed to BDE47 (1 and 10 μM) and/or ISL (4 μM) for 4 to 120 hours post fertilization (hpf), and the morphology, development, behavior, oxidative stress status and related genes expression were assessed. The results showed that BDE47 contributed to dose-dependent growth retardation and deformities, including delayed hatching, spinal curvature, reduced body length, increased death rate, aberrant behaviors and impaired dark-adapted vision, which were significantly mitigated by ISL. Besides, ISL ameliorated excessive ROS accumulation, and exaggerated the expressions of apoptosis-related genes p53 , Bcl - 2 , caspase 3 and caspase 9 induced by BDE47, suggesting that ISL protected zebrafish from the developmental toxicity of BDE47 by inactivation of programmed apoptosis and activation of antioxidant signaling pathways. Taken together, developing ISL as a dietary supplement might be a promising preventive strategy for the amelioration of developmental toxicity induced by environmental pollutants. Graphical abstract Unlabelled Image Highlights • BDE47 induced the developmental anomalies of zebrafish through oxidative stress. • Isoliquiritigenin (ISL) mitigated BDE47-induced zebrafish dysplasia via antioxidant. • ISL restored p53 / caspase signaling pathway and alleviated the toxicity of BDE47. • ISL as dietary supplement appears promising prevention for environmental pollutants. [ABSTRACT FROM AUTHOR]

Abstract Simvastatin is one of the most commonly cholesterol-lowering prescribed drugs all over the world. With the increase of consumption of these pharmaceuticals and subsequent their discharge into the aquatic environment in recent years, they are present at detectable levels in most sewage effluents. Unfortunately, limited information is provided about their potential impacts on aquatic organisms, especially on the detoxification-related metabolism in fish. In the present study, one local native benthic fish (Mugilogobius abei) in southern China was employed as test species and exposed to SV (0.5 μg L−1, 5 μg L−1, 50 μg L−1 and 500 μg L−1) for 72 h. The transcriptional expression of nucleus transcriptional factor pregnane X receptor (PXR) and its downstream targeted genes including multixenobiotics resistance protein or permeability glycoprotein (P-gp), cytochrome 1A (CYP1A), cytochrome P450 3A (CYP3A), glutathione-S-transferase (GST) and the expression of associated microRNA such as miR-27, miR-34 and miR-148 in Mugilogobius abei were investigated. Result showed that the expressions of P - gp , CYP 1A , CYP 3A , GST and PXR were induced to some extend under simvastatin exposure for 72 h. A positive correlation was observed between PXR and CYP1A , CYP3A and P - gp. While for microRNA, a negative relationship was found between miR - 34a and CYP3A , CYP1A. The expression of miR - 148a was significantly induced under the exposure of SV (50 μg L−1), which was positive related to the transcriptional expression of PXR. For enzyme activity, erythromycin N -demethylase (ERND) significantly increased at 24 h and the activity of catalase (CAT) and superoxide dismutase (SOD) exhibited different trends. CAT was slightly inhibited at 24 h exposure but SOD was significantly induced in high concentration. Glutathione-S-transferase (GST) activity was significant inhibited after 72 h exposure. The reductive small molecule glutathione (GSH) content showed obvious decrease, while the quantity of malondialdehyde (MDA) increased significantly in high concentrations of SV exposure. GSH and MDA showed a typical negative correlation to some degree. Moreover, simvastatin caused histological changes in the liver tissues of M. abei , especially the size of adipocyte significantly decreased. The present study indicated that environmentally relevant concentration SV may affect the PXR signaling pathway in M. abei and pose potential ecological risks to non-target organisms like fish. Graphical abstract Unlabelled Image Highlights • Simvastatin affects the expression of genes in PXR signaling pathway and related enzymes activity. • miR-27, miR-34 and miR-148 play a role in regulation of PXR signaling pathway. • Simvastatin cause histological changes in the liver tissues of M. abei. [ABSTRACT FROM AUTHOR]

Urban buses are heavy vehicles that move frequently throughout the day, and most of them are propelled by heavy-duty diesel engines. For these reasons, they have energy and environmental impacts that should not be ignored. Consequently, the primary objectives of this study were to compare the changes in bus speed, acceleration, and emissions between bus stops, intersections, and road sections by applying statistical methods; and to develop a vehicle specific power (VSP)-based artificial neural network (ANN) model to estimate emissions of CO, HC, NO X , and CO 2 for four different fuel types of buses including gas-electric hybrid electric buses (GEHE bus), compressed natural gas buses (CNG bus), EURO 4 heavy-duty diesel engine buses (EURO 4 bus), and EURO 5 heavy-duty diesel engine buses (EURO 5 bus). The results of t -tests (with p -values varying between <0.001 and 0.026, which were not >0.050) showed that the differences in emissions between different locations and between different fuel types of buses were all statistically significant. In addition, to evaluate the performance of the proposed method, a polynomial regression model using linear, quadratic, and cubic terms of transient speed and acceleration was utilized for comparison. According to the results, the proposed method had more accurate and reliable estimation, which increased the lower 10% of absolute percentage error (Lower-10% APE) by 65.2%; reduced mean absolute percentage error (MAPE) by 41.4%, root mean squared error (RMSE) by 44.9%, and mean absolute error (MAE) by 43.5%; and increased R-squared from 0.659 to 0.781. [ABSTRACT FROM AUTHOR]

The intracellular cyclic diguanylate acid ( c -di-GMP) has emerged as a prominent second signal molecule that coordinates sessile-motile transition and biofilm formation in many bacteria. Herein, we study the role of c -di-GMP in affecting microbial community shifts at different pH levels during simultaneous partial nitrification, anammox and denitrification process (SNAD) in integrated fixed film activated sludge (IFAS) reactor. The results demonstrated that the contents of c -di-GMP notably decreased in suspended sludge, whereas the contents of c -di-GMP in biofilm had no significant change as pH gradually increased from 7.5 to 8.5. Most of the bacteria ( Blastocatella , Brevundimonas ) with flagella that have been reported to be regulated by c -di-GMP were present in suspended sludge, and the microbial community structure of suspended sludge had obvious change than biofilm. The increased alkaline pH reduced intracellular c -di-GMP content for increasing the motility of bacteria to be washed out from the reactor, causing the microbial community shifts in suspended sludge. This change would lead to the increase of nitrite-oxidizing bacteria which would inhibit anammox activity. Overall, this study provided more comprehensive information regarding the shifts of microbial community induced by c -di-GMP in SNAD-IFAS reactor. [ABSTRACT FROM AUTHOR]

In photocatalytic systems, TiO 2 based particles in suspensions tend to aggregate spontaneously, resulting in low efficiency for light utilization and photocatalytic activity. In this study, various TiO 2 nanoparticles with different shapes were synthesized and characterized via various analysis. In atmosphere and aqueous environment, the nanoparticles demonstrated different properties in the nature of the agglomerations. Photocatalytic performances of the as-prepared samples were confirmed to be strongly influenced by the dispersion stabilities with TiO 2 nanotube exhibited higher colloidal dispersion stability and photocatalytic activity. Mixing binary TiO 2 photocatalysts with different shapes as a simple approach was firstly proposed for enhancing photoreforming hydrogen production from bio-glycerol aqueous solution. At a specific mixing ratio, the mixed suspension of TiO 2 nanosphere and nanosheet retained excellent colloidal dispersion stability, and photocatalytic hydrogen production was significantly promoted with its maximum H 2 production amount as 2.1–2.9 times high as that of TNP and TNS, respectively. This strategy of enhancing colloidal dispersion stability may provide new ideas for the design of efficient and energy-saving photocatalytic system. [ABSTRACT FROM AUTHOR]

The growing production and application of CuO nanoparticles increase the chance that these particles will be released into wastewater treatment plants (WWTPs) and interact with microorganisms. However, the toxicity response mechanism of biofilm to NP exposure may be different from that of activated sludge due to the denser and stronger microbial aggregate structure of biofilm. Thus, in this study, the response to CuO NPs of wastewater biofilm collected from a rotating biological contactor was investigated. Short-term exposure (24 h) to CuO NPs led to a great loss in cell viability, and SEM-EDS images revealed that the nano-CuO aggregates were not transformed to Cu-S species in the biofilm samples. In response, more extracellular polymeric substance (EPS) (especially loosely bound-EPS) was produced in wastewater biofilm exposed to CuO NPs, with a higher content of protein compared to polysaccharides. The shifts of fluorescence intensity and peak locations in 3D-EEM fluorescence spectra indicated chemical changes of the EPS components. FT-IR analysis revealed that exposure to nano-CuO had more distinct effects on the functional groups of proteins and polysaccharides in LB-EPS. Illumina sequencing of 16S rRNA gene amplicons revealed that CuO NPs enhanced bacterial diversity. The bacterial community structure significantly shifted, with a significantly increased abundance of Comamonas , a slight increase in Zoogloea , and a notable decrease in Flavobacterium . The shifts of these dominant genera may be associated with altered EPS production, which might result in microbial community function fluctuations. In conclusion, exposure to high concentrations of CuO NPs has the potential to shape wastewater biofilm bacterial community structure. [ABSTRACT FROM AUTHOR]

Polybrominated diphenyl ethers (PBDEs) have become ubiquitous environmental contaminants, particularly in mangrove wetlands. However, little is known about the long-term effect of mangrove plants on PBDE removal from contaminated sediments. A 12-month microcosm experiment was conducted to understand the effect of two mangrove species, namely Avicennia marina (Am) and Aegiceras corniculatum (Ac), on PBDE removal from the sediments spiked with 2000 ng g − 1 dry weight of BDE-47, and to explore the microbial mechanism responsible for the planting-induced effects on BDE-47 removal. Results showed that planting of mangrove species, either Am or Ac, could accelerate BDE-47 removal from contaminated sediments during the 12 months experiment, mainly through enhancing microbial degradation process. In particular, Am sediment had significantly higher BDE-47 degradation efficiency compared with Ac sediment, which may be mainly attributed to higher activities of urease and dehydrogenase, as well as higher 16S rRNA gene copies of total bacteria and organohalide-respiring bacteria (OHRB) in Am sediment. Moreover, planting could shift sediment bacterial community composition and selectively enrich some bacterial genera responsible for PBDE degradation. Such selective enrichment effect of Am on the potential PBDE-degrading bacteria differed distinctly from that of Ac. These results indicated that long-term planting of mangrove species, especially Am, could significantly promote BDE-47 removal from the contaminated sediments by enhancing microbial activity, increasing total bacterial and OHRB abundances and altering bacterial community composition. [ABSTRACT FROM AUTHOR]

Cropland expansion and fertilizer applications are among the most important substantial effects of human actions on the global nitrogen (N) cycle. However, questions remain over the fate of anthropogenic N inputs, particularly whether a significant fraction of N-based fertilizers have been lost to inert N 2 or reactive N forms. Here, we combine natural N isotope constraints on the pre-industrial N cycle with global mass-balance modeling to investigate the role of cropland conversion on gaseous N emissions and hydrological N leaching fluxes. We estimate that cropland expansion has been accompanied by > 9-fold increase in N input rates to cropping systems, roughly doubling the baseline N budget of the terrestrial biosphere. As a consequence, approximately 10 times more N is exported from modern croplands to the hydrosphere than in 1860, with a five-fold increase in cropland N gases emission to the atmosphere. Atmospheric NH 3 , NO, N 2 O and N 2 fluxes increased from 8.6, 16.6, 11.7 and 31.9 Tg N yr − 1 , respectively, in 1860 to 17.7, 23.6, 15.2 and 39.7 Tg N yr − 1 , respectively, by 2000. Thus, the growth in N 2 accounted for ~ 20% of cropland-driven N losses (dissolved plus gaseous pathways), with the remaining 80% exported as reactive N forms. Although the increase in N 2 emissions has mitigated some of the unwanted side-effects of N fertilizer applications on human health, the economy, and climate change, this inert sink has been unable to keep pace with the increase in N inputs for enhanced food production. Our results imply that, unless new management steps are taken, an increasing fraction of N fertilizers will mobilize to reactive N forms in the global land, air and water systems, thus further accelerating the negative consequences of human modifications of the N cycle this century. [ABSTRACT FROM AUTHOR]

A novel Zr oxide diffusive gradients in thin films (DGT)-based measurement technique for high-resolution imaging of labile Cr (VI) is introduced in this study. The method is based on the diphenylcarbazide coloration technique for Cr (VI) combined with computer-imaging densitometry, which provides a relation between the accumulated mass of Cr (VI) and the grayscale intensity. The Zr oxide gels show good performance in reflecting the accurate measurement of Cr (VI), independent of the effects of pH, ionic strength, and PO 4 3 − concentration. Settling of the Zr-oxide gel was identified as a simple and effective method to suppress leaching of the claret-colored compound out of the gel. In addition, the optimal volume of added coloration reagent was 125 times that of the binding gel and 30 min was selected as the optimal time for the chromogenic reaction. The relationship between the accumulated Cr (VI) and grayscale intensity was analyzed under the optimized conditions. The Zr oxide DGT technique could also obviously reflect the heterogeneity of sediment. Consequently, Zr oxide DGT-based coloration is certified to be a robust and suitable tool for providing effective and high-resolution information on bioavailable Cr (VI). [ABSTRACT FROM AUTHOR]

The influence of chironomid larvae and hydrodynamics on the bioavailable arsenic (As) in sediments under different conditions was comprehensively investigated through water tank experiments spanning 132 days. The high-resolution technique of revealing diffusive gradients in thin films (DGT) with ZrO-Chelex resin was employed in this study; this was done to simultaneously obtain concentrations of labile As and Fe in the profile at millimeter resolution. Bioturbation by larvae may significantly decrease the bioavailable As and Fe concentrations under different hydrodynamic intensities during the first two months of larval burrowing; the greatest difference between the bioavailable As concentration with and without the addition of larvae was seen on the 56th day, with around 49%, 47%, 73% and 67% reduction of As in the profile under static water, 0.3 m s − 1 , 0.5 m s − 1 and 1.0 m s − 1 , respectively. However, these effects were diminished after the 56th day due to the eclosion of the chironomid larvae. The hydrodynamic conditions appeared to not have any significant effect on the labile concentration of As or Fe until after eclosion. The changing distributions of labile As and Fe were consistent with the dissolved oxygen concentrations in the profile under different conditions. Labile As showed the significantly correlation coefficients with labile Fe by a stepwise multiple linear regression under different experimental conditions in this study. We conclude that the decreases in bioavailable As are directly related to conversions between Fe 2 + and Fe 3 . [ABSTRACT FROM AUTHOR]

Zinc oxide nanoparticles (ZnO NPs) used in consumer products are largely released into the environment through the wastewater stream. The health hazard of ZnO NPs and the contribution of dissolved Zn 2 + in toxicity of ZnO NPs has attracted extensive worldwide attention. In this study, the toxic effects of ZnO nanoparticles (ZnO NPs) and the effects of dissolved Zn 2 + on fluvial biofilms were investigated. At the end of the exposure time (21 days), scanning electron microscopy (SEM) images and bioaccumulation experiments revealed that large quantities of ZnO NPs were adsorbed on the biofilm. The algal biomasses were significantly decreased by six- and eleven-fold compared with the control (1.43 μg/L) by exposure to concentrations of 100 mg/L ZnO NPs and 7.85 mg/L Zn 2 + , respectively. Moreover, under the same exposure conditions, the quantum yields presented contents of 53.33 and 33.33% relative to the control, and a shift in the community composition that manifested as a strong reduction in diatoms was observed from 7 days and reached 15.63 and 6.25% of the control after 21 days of exposure, respectively. The reductions in bacteria viability and reactive oxygen species (ROS) production were noticeably enhanced following exposure to 100 mg/L ZnO NPs and 7.85 mg/L Zn 2 + , respectively. Additionally, the acute and rapid toxicity of Zn 2 + and the increasing toxicity of the ZnO NPs with increased bioaccumulation were noted in the exposure experiment. [ABSTRACT FROM AUTHOR]

The precise evaluation of arsenic (As) and mercury (Hg) bioavailability in sediment is crucial to controlling As and Hg contamination, but traditional ex situ measurements hamper comprehensive analysis of labile As and Hg in sediment. In this study, we characterized in situ labile As and Hg in sediment of Lake Hongze using the zirconium (Zr) oxide diffusive gradients in thin films (DGT) technique and 3-mercaptopropyl functionalized silica gel DGT, respectively. The concentrations of DGT-labile As and Hg in the sediment profiles were found to exhibit considerable variation, ranging from 0.15 to 4.15 μg L − 1 for As and from 0.04 to 1.35 μg L − 1 for Hg. As and Hg flux values, calculated based on the concentration gradients measured from the DGT profiles for both the overlying water and sediment close to the sediment–water interface, were used to determine the contamination status of As and Hg. Flux values of As and Hg were between − 0.066 and 0.067 ng cm − 2 d − 1 and between − 0.0187 and 0.0181 ng cm − 2 d − 1 , respectively. The GNU's Not Unix R (GNU R) programming language was used to identify outliers of As and Hg at various depths at the sampling sites. The results indicate that the sites with the most outliers were all located in the regions that were seriously affected by contaminants from the Huai River. The DGT-labile As and Hg concentrations in the 0–30 mm layer were found to be significantly correlated with concentrations of labile As and Hg, total dissolved As and Hg, and total As and Hg in the overlying water, as indicated by ex situ measurements. Results show that DGT is a reliable and high-resolution technique that can be used for in situ monitoring of the labile fractions of As and Hg in sediment in fresh water bodies. [ABSTRACT FROM AUTHOR]

Landfills implemented with onsite leachate recirculation can efficiently remove pollutants, but currently they are reckoned as N 2 O emission hot spots. In this project, we evaluated the relationship between N 2 O emission and nitrogen (N) removal efficiency with different types of leachate recirculated. Nitrate supplemented leachate showed low N 2 O emission rates with the highest N removal efficiency (~ 70%), which was equivalent to ~ 1% nitrogen emitted as N 2 O. Although in nitrite containing leachates' N removal efficiencies also reached to ~ 60%, their emitted N 2 O comprised ~ 40% of total removed nitrogen. Increasing nitrogen load promoted N 2 O emission and N removal efficiency, except in ammonia type leachate. When the ratio of BOD to total nitrogen increased from 0.2 to 0.4, the N 2 O emission flux from nitrate supplemented leachate decreased from ~ 25 to < 0.5 μg N/kg-soil · h. We argue prior to leachate in situ recirculation, sufficient pre-aeration is critical to mitigate N 2 O surges and simultaneously enhance nitrogen removal efficiency. [ABSTRACT FROM AUTHOR]

Abstract: Toxicological effects of nanoparticles (NPs) are still poorly documented while there are great demands for industrial applications and daily life. The aim of this study is to evaluate the influence of physicochemical characteristics on TiO2 NP toxicological effects toward protein. In order to better understand the physicochemical basis of the toxic of NP in industrial applications and under conditions of environmental exposure, we performed an array of photophysical measurements to quantify the interaction of TiO2 NP with protein. Fluorescence quenching, circular dichroism, dynamic light scattering and transmission electron microscopy measurements were performed on TiO2 NP having a diameter range from 10 to 35nm in the performance of protein. We find that the TiO2 NP strongly associates with protein where the binding constant, as well as the degree of cooperativity of particle–protein binding, depends on particle size. We also find tentative evidence that the protein undergoes conformational change upon association with the NP. These results indicate that exposure to TiO2 NP may have an unfavorable effect on human health by inactivating functional proteins. [Copyright &y& Elsevier]

An anaerobic hydrolysis denitrification (AnHD) process was developed to pretreat municipal wastewater for integrating partial nitration/anammox process. The results indicated that the carbon to nitrogen (C/N) ratio of municipal wastewater changed from 4.4 ± 0.3 to 2.2 ± 0.2 after pretreatment by AnHD process, which was favorable to the partial nitration/anammox process. The influent C/N ratio had influence on the formation of anaerobic granules. Two intrinsic factors, cyclic diguanylic acid (c -di-GMP) concentration and core bacterial community, were mainly responsible for the anaerobic granular formation. The higher c -di-GMP content increased the extracellular polymeric substances and decreased the motility of the bacteria, which was beneficial for the formation of anaerobic granules. The microbial community analysis showed that the lactic acid bacteria (Lactococcus) was the core bacteria during anaerobic hydrolysis process, while the denitrifying bacteria (Denitratisoma and unclassified Comamonadaceae) were the core bacterial community during AnHD process, which were responsible for nitrogen removal and anaerobic granular formation. Unlabelled Image • An anaerobic hydrolysis denitrification (AnHD) process was developed. • AnHD process was favorable to pretreatment for applying PN/Anammox process. • AnHD granule formation was related to c -di-GMP content and core bacteria community. • Denitrifying bacteria was core bacteria community of AnHD granule. [ABSTRACT FROM AUTHOR]