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Nanoparticles have been reported to induce toxicity to aquatic organisms, however, their potential impacts on phosphorus removal from wastewater by algae are unclear. In this study, the effects of nanoparticle ZnO (nano-ZnO) on phosphate (PO 4 3− ) removal by a green alga Chlorella vulgaris were investigated. We found that PO 4 3− removal efficiency was accelerated with high concentrations of nano-ZnO (0.04–0.15 mM) but reduced with low concentrations of nano-ZnO (0.005–0.04 mM) compared to the control (without nano-ZnO), suggesting that PO 4 3− removal efficiency by C. vulgaris was related to nano-ZnO concentrations. Moreover, we observed changes of nano-ZnO morphology and detected element P on the surface of nano-ZnO by using transmission electronic microscopy (TEM) combined with energy dispersive X-ray spectroscopy (EDX), indicating that PO 4 3− was interacted with nano-ZnO or the dissolved Zn 2+ from nano-ZnO. Furthermore, we confirmed this interaction induced the formation of Zn 3 (PO 4 ) 2 crystallites sedimentation by employing X-ray diffraction analysis (XRD) and X-ray photoelectron spectroscopy (XPS), which finally accelerates the removal of PO 4 3− . [ABSTRACT FROM AUTHOR]

Autophagy is a dynamic process for waste disposal and cell equilibrium. Previous studies have demonstrated that atmospheric particulate matter (APM) induces autophagy and enhances LC3II expression in human vascular endothelial cells. However, the underlying mechanism of autophagosome accumulation in human vascular endothelial cells under the exposure to APM has not been understood. In principle, the upregulation of LC3II or autophagosomes accumulation is presumably caused by the enhancement of autophagic ability, or alternatively, by the abnormal autophagic degradation. Therefore, in the current study, autophagic ability and autophagic flux are systemically studied to decipher the exact cause of autophagosomes accumulation in human umbilical vein endothelial cells (HUVECs) in response to a standard urban particulate matter, PM SRM1648a. As a result, it was observed that after 24 h of exposure, PM SRM1648a significantly increases LC3II expression with apparent autophagosomes accumulation in HUVECs. Compared with the control group, there is a time-dependent increase in p62, a protein of autophagic substrate that can be preliminarily used to evaluate the autophagic degradation, in the PM SRM1648a-exposed HUVECs, which suggested that normal function of autophagic degradation was probably impaired. Additionally, mRFP-GFP-LC3 assay and LAMP-2/LC3B co-localization suggested that autolysosomes (fusion between autophagosomes and lysosomes) were partially inhibited in PM SRM1648a-treated HUVECs. Furthermore, LC3II turn-over assay hinted that after 24 h, LC3II upregulation is attributed to the blockage of autophagic flux instead of the enhancement of autophagic induction. Mechanistically, the blockade of autophagic flux can be explained by the detrimental effects of PM SRM1648a on lysosomal function, including lysosomal destabilization, lysosomal alkalization and hydrolase inactivation, which are involved in the blockade of fusion between autophagosomes and lysosomes, further disrupting autophagic degradation and waste disposal. These observations provide evidence that PM SRM1648a destroys the equilibrium of lysosomal stability and thus results in the dysfunction of autophagic flux, eventually contributing to endothelial cell damage. Unlabelled Image • After 24 h, autophagic flux was blocked in HUVECs following exposure to PM SRM1648a. • PM SRM1648a causes defective autophagy in HUVECs. • Lysosomes are damaged in HUVECs in response to PM SRM1648a. • Particles-induced lysosomal impairment is responsible for dysfunction of autophagic flux. [ABSTRACT FROM AUTHOR]

Global warming and increased nutrient availability in the Arctic have attracted wide attention. However, it is unknown how an increased supply of nitrogen (N), phosphorus (P) and/or labile carbon (C) – alone and in combinations – affects the concentrations and pools of C and nutrients in plants, soil and soil microorganisms, and whether the cessation of these additions allows the ecosystem to recover from amendments. Six treatments (control, C, N, P, NP and C + NP) were applied at a subarctic heath for 8–10 years. After being untreated for two years, amendments were re-applied to one half of the plots for four years while the other plot half received no amendments. When the plots were harvested, we could therefore compare responses in plots with nearly continuous 14–16-year amendments to those with six years with discontinued treatments. The responses to individual and combined nutrient additions were mostly similar in re-initiated and discontinued plots. Individual N addition strongly increased the C and N pools in the graminoids, thereby also increasing the C and N pools in litter and fine roots compared to the plots without added N. This contributed to the increased microbial biomass C and total C in soil. P addition alone increased C and N pools in vascular cryptogams, as well as PO 4 3−, NH 4 +, dissolved organic carbon and dissolved organic nitrogen concentrations in soil compared to the plots without added P. Hence, plant functional groups showed differential responses to long-term N and P amendment, and after the initial nutrient additions for 8–10 years, the investigated subarctic tundra ecosystem had reached a new steady state that was resilient to further changes still six years after cessation of additions. Unlabelled Image • Similar effects for recent and old nutrient additions in a subarctic tundra ecosystem. • N addition alone increased C and N pools in graminoids, litter and fine roots. • P addition alone increased C and N pools in vascular cryptogams. • Individual and combined additions of C, N, and P increased microbial biomass C. • After long-term nutrient additions, the tundra ecosystem reached a new steady state. [ABSTRACT FROM AUTHOR]

Abstract This study investigated the influences of cetyltrimethyl trimethyl ammonium chloride (CTAC), an emerging pollutant quaternary ammonium compound (QAC) in municipal effluents, on the transfer and uptake of NH 4 + by Chlorella vulgaris F1068 cells removed EPS artificially (EPS-R) and coated EPS naturally (EPS-C) under different scenarios (e.g., the presence or absence of CTAC, different photoperiod sequences (light 12 h: dark 12 h or dark 12 h: light 12 h)). The results showed that the removal of EPS increased the transfer and uptake of NH 4 + but the presence of EPS caged NH 4 + and effectively weakened the stress of CTAC (<0.5 mg/L) on NH 4 + uptake. The main mechanism was considered that CTAC in the concentration range from 0.1 to 0.5 mg/L induced an increased amount of polysaccharide and protein in EPS and thus protected algal normal physiological functions (including cell membrane permeability and glutamine synthetase activity) from the damage of CTAC (0.1 to 0.5 mg/L) regardless of the photoperiod sequences. Thereby, the findings of this study provided an insight into the role of algal EPS in transfer and uptake of nutrients under the coexisted toxics for the future algae-based sewage treatment application. Graphical abstract Unlabelled Image Highlights • CTAC decreased uptake of NH 4 + but EPS retarded the decline of NH 4 + uptake. • EPS of algae F1068 decreased the toxicity of CTAC (<0.5 mg/L). • CTAC (<0.5 mg/L) increased the contents of polysaccharide and protein in EPS. • EPS protected algal membrane permeability, fluidity and glutamine synthetase. • EPS removal increased influx and uptake of NH 4 + compared to the presence of EPS. [ABSTRACT FROM AUTHOR]

Abstract Extracellular polymeric substances (EPS) play significant roles in protecting cells against environmental stresses. However, little information is known about the roles of different EPS in these processes. In this study, the productions and physicochemical characterizations of soluble-EPS (S-EPS) and bound-EPS (B-EPS), the two different fractions of EPS from a green alga Chlorella vulgaris under the stress of ZnO nanoparticle (nano-ZnO) were investigated. The contents of S-EPS and B-EPS which described as dissolved organic carbon, polysaccharides and proteins, both increased with the addition of tested nano-ZnO (0.01 and 0.04 mM) in a 72 h cultivation. EPS-Free (EPS-F) cells produced more S-EPS and B-EPS than the EPS-Cover (EPS-C) cells did with the tested nano-ZnO, especially the contents of protein in the S-EPS of EPS-F cells increased by 45.5% with 0.04 mM nano-ZnO compared to the control at 72 h. Tryptophan-like substances of the protein in S-EPS exhibited a stronger chemical static quenching than tyrosine-like substances with nano-ZnO. In addition, the hydroxyl (OH) as well as carboxyl (C O) group, and C O of amide I, N H/C N of amide II groups in proteins were confirmed that involved in the reaction of S-EPS and B-EPS with nano-ZnO, meanwhile hemiacetal groups in saccharides were oxidized to carboxyl groups. This study could provide a better understanding of EPS in protecting against cells damage with nanoparticles. Graphical abstract Unlabelled Image Highlights • More S-EPS and B-EPS were produced in EPS-F cells than in EPS-C cells with nano-ZnO. • More proteins were produced in S-EPS as a protective response of nano-ZnO. • Tryptophan-like substances in S-EPS showed strong interactions with nano-ZnO. • Hydroxyl, carboxyl and amide groups in S-EPS and B-EPS were involved in the reaction with nano-ZnO. [ABSTRACT FROM AUTHOR]

Zoxamide is a recently discovered chiral fungicide that applied to agricultural production, but the potential environmental risk may be underestimated because the risk posed by either enantiomer has not been adequately assessed. Therefore, systemic evaluation of zoxamide was first carried out at the enantiomeric level. Enantioselective bioactivity against target pathogens (Phytophthora capsici Leonian, Alternaria solani , Botryis cinerea , Colletotrichum gloeosprioides Penz, Phytophthora sojae Kaufmann & Gerdemann) was explored, and the order of the bioactivity was R -zoxamide > Rac -zoxamide > S -zoxamide, with a 9.9- to 140.0-times difference between two enantiomers. Molecular docking simulation was utilized to clarify the mechanism underlying the observed differences in enantioselective bioactivity, and the result indicated that a difference of Van der waals force between R / S -zoxamide and the specific receptor gave rise to the different antifungal activity. The enantioselective toxicity result demonstrated that R -zoxamide had 4.9- to 10.8- times greater acute toxicity to Selenastrum capricornutum and Daphnia magna than S -zoxamide. S -zoxamide degraded faster under aerobic condition in all three types of soils, giving rise to an enrichment of high-risk R -enantiomer. Under anaerobic condition, however, no significant difference in dissipation rate was observed between two enantiomers. R -zoxamide was 1.5- to 3.5-times more bioactive and 1.1- to 1.5-times more toxic than Rac -zoxamide, which means developing R-zoxamide instead of racemate is a potential way to reduce pesticide dosage without loss of efficacy against target organisms and that an inactive isomer would no more be released to the environment. This study may have implications for better practical application and environmental risk assessment of zoxamide enantiomers. Unlabelled Image • Systemic assessments of zoxamide enantiomers are conducted for the first time. • R-zoxamide is 9.9- to 140.0-times more bioactive than S-isomer. • Enantioselective mechanism is clarified with molecular docking. • Significant enantioselectivity is observed under aerobic condition. [ABSTRACT FROM AUTHOR]

Reducing the carbon footprint (CF) of crop production is an efficient way to mitigate climate change. Growing legume green manure (LGM) instead of summer fallow may achieve this goal by lowering synthetic nitrogen (N) fertilizer needs and replenishing the depleted soil carbon (C) pool. The Rothamsted Carbon (RothC) model was incorporated into the Life-Cycle Assessment (LCA) to evaluate the present and projected CFs of green manure-based wheat production systems in dryland agriculture on the Loess Plateau of China. The field study included four main treatments ( Huai bean, soybean and mung bean grown as green manure in summer and fallow as control) and four synthetic N rates (0, 108, 135 and 162 kg N ha − 1 ) applied at wheat sowing. Soybean as LGM increased averaged wheat yield over 4 synthetic N rates by 8% compared with fallow ( P < 0.05), and synthetic N requirement was reduced by 33% without compromising the wheat yield for all the main treatments. Although LGM treatments had higher greenhouse gas (GHG) emissions from agricultural inputs, the greater amount of C inputs elevated the corresponding SOC stocks (SOCS) by 14–24% after 8 years, thus significantly reducing the CF by 25–51% compared with fallow. The modelled SOCS equilibrium indicates that the CF for cropping systems with LGM will be 53–62% lower than fallow and 23–37% lower compared with their current level. In conclusion, introducing legume green manure instead of summer fallow is a highly efficient measure for persistent CF reduction, and coupling the RothC model and LCA is an alternative method to predict the long-term impact of different cropping systems on GHG emissions. [ABSTRACT FROM AUTHOR]

TiO 2 -based thin films have been intensively studied in recent years to develop efficient photocatalyst films to degrade refractory organics and inactivate bacteria for wastewater treatment. In the present work, P/Ag/Ag 2 O/Ag 3 PO 4 /TiO 2 composite films on the inner-surface of glass tube were successfully prepared via sol-gel approach. P/Ag/Ag 2 O/Ag 3 PO 4 /TiO 2 composite films with 3 coating layers, synthesized at 400 °C for 2 h, showed the optimal photocatalytic performance for rhodamine B (Rh B) degradation. The results indicated that degradation ratio of Rh B by P/Ag/Ag 2 O/Ag 3 PO 4 /TiO 2 composite film reached 99.9% after 60 min under simulated solar light, while just 67.9% of Rh B was degraded by pure TiO 2 film. Moreover, repeatability experiments indicated that even after five recycling runs, the photodegradation ratio of Rh B over composite film maintained at 99.9%, demonstrating its high stability. Photocatalytic inactivation of E. coli with initial concentration of 10 7 CFU/mL also showed around 100% of sterilization ratio under simulated solar light irradiation in 5 min by the composite film. The radical trapping experiments implied that the major active species of P/Ag/Ag 2 O/Ag 3 PO 4 /TiO 2 composite films were photo-generated holes and O 2 − radicals. The proposed photocatalytic mechanism shows that the transfer of photo-induced electrons and holes may reduce the recombination efficiency of electron-hole pairs and potential photodecomposition of composite film, resulting in enhanced photocatalytic ability of P/Ag/Ag 2 O/Ag 3 PO 4 /TiO 2 composite films. [ABSTRACT FROM AUTHOR]

Since 1999 Chinese government has made great effort to reforest the south and north mountains surrounding urban Lanzhou – a city located in a river valley, Northwestern China. Until 2009 obvious land use change occurred, with 69.2% of the reforested area been changed from grasslands, croplands, barren or sparsely vegetated land to closed shrublands and 20.6% from closed shrublands, grasslands, and croplands to forests. Reforestation changes land-surface properties, with possible impact on the evolution of atmospheric variables. To understand to what extent the local meteorology and environment could be affected by reforestation in winter, and through what processes, two sets of simulations were conducted using the Weather Research and Forecasting model (WRF) and the FLEXible PARTicle (FLEXPART) dispersion model for a control case with high-resolution remotely sensed land cover data for 2009 and a scenario assuming no reforestation since 1999. Results suggested that the changes in albedo, surface exchange coefficient and surface soil heat conductivity related to reforestation led to the changes in surface net radiation and surface energy partitioning, which in turn affected the meteorological fields and enhanced the mountain-valley wind circulation. Replacement of shrublands and grassland with forest in the south mountain through reforestation play a dominant role in the enhancement of mountain-valley wind circulation. Reforestation increased the amount of air exchanged between the valley and the outside during the day, with the largest hourly increase of 10% on calm weather days and a monthly mean hourly increase of 2% for the study period (Dec. 2009). Reforestation affected the spatial distribution of pollutants and slightly improved the urban air quality, especially in the eastern valley. Results from this study provide useful information for future urban air quality management and reforestation plan, and some experience for cities with similar situations in the world. [ABSTRACT FROM AUTHOR]