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Titanium dioxide nanoparticles (TiO 2 -NPs) are widely distributed in the environment. It has been demonstrated that TiO 2 -NPs could modify the environmental fate and bioavailability of organic pollutants, which affects ecological risks of TiO 2 -NPs and organic pollutants. In this study, the uptake, translocation and accumulation of perfluorooctanoic acid (PFOA) and perfluorooctanesulfonate (PFOS) in pumpkin plants was investigated in the presence of TiO 2 -NPs. We reported for the first time the negligible effects of TiO 2 -NPs at environmentally relevant concentrations (0.05–5 mg/L) on the uptake and accumulation of PFOA and PFOS in hydroponically grown pumpkin seedlings regardless of root, stem and leaf. This phenomenon was independent of the initial concentrations of PFOA/PFOS and TiO 2 -NPs in the exposure solution. Also, seedling mass and contents of chlorophyll and anthocyanin were not affected by the co-exposure. Adsorption tests demonstrated the negligible adsorption of PFOA/PFOS on TiO 2 -NPs in the exposure solution. Moreover, uptake of PFOA/PFOS was insensitive to aquaporin inhibitor AgNO 3 but significantly inhibited by niflumic acid (anion channel blocker) and 2,4-dinitrophenol (metabolic inhibitor) whereas Ti concentration in root was not affected by niflumic acid and 2,4-dinitrophenol but significantly decreased by AgNO 3 , indicating that transport of PFOA/PFOS and TiO 2 -NPs were via different routes into the pumpkin seedling. It was proposed that different pathways by which TiO 2 -NPs and PFOA/PFOS transported into the pumpkin seedling and negligible adsorption of PFOA/PFOS on TiO 2 -NPs contributed to the negligible effects of TiO 2 -NPs on the uptake, translocation and accumulation of PFOA/PFOS in pumpkin seedlings. In total, this work would improve our understanding of the ecological risks of TiO 2 -NPs in the environment. Unlabelled Image • Effect of TiO 2 -NPs on accumulation of PFOA/PFOS in pumpkin seedling was explored. • Environmentally relevant concentrations of TiO 2 -NPs were applied in this work. • The negligible effects were observed. • The negligible adsorption of PFOA/PFOS on TiO 2 -NPs was proposed as one reason. • Different pathways of TiO 2 -NPs and PFOA/PFOS into root were another reason. [ABSTRACT FROM AUTHOR]

Regional variation in both natural environment and human disturbance can influence performance of ecological assessments. In this study we calculated 5 types of benthic diatom multimetric indices (MMIs) with 3 different approaches to account for variation in ecological assessments. We used: site groups defined by ecoregions or diatom typologies; the same or different sets of metrics among site groups; and unmodeled or modeled MMIs, where models accounted for natural variation in metrics within site groups by calculating an expected reference condition for each metric and each site. We used data from the USEPA's National Rivers and Streams Assessment to calculate the MMIs and evaluate changes in MMI performance. MMI performance was evaluated with indices of precision, bias, responsiveness, sensitivity and relevancy which were respectively measured as MMI variation among reference sites, effects of natural variables on MMIs, difference between MMIs at reference and highly disturbed sites, percent of highly disturbed sites properly classified, and relation of MMIs to human disturbance and stressors. All 5 types of MMIs showed considerable discrimination ability. Using different metrics among ecoregions sometimes reduced precision, but it consistently increased responsiveness, sensitivity, and relevancy. Site specific metric modeling reduced bias and increased responsiveness. Combined use of different metrics among site groups and site specific modeling significantly improved MMI performance irrespective of site grouping approach. Compared to ecoregion site classification, grouping sites based on diatom typologies improved precision, but did not improve overall performance of MMIs if we accounted for natural variation in metrics with site specific models. We conclude that using different metrics among ecoregions and site specific metric modeling improve MMI performance, particularly when used together. Applications of these MMI approaches in ecological assessments introduced a tradeoff with assessment consistency when metrics differed across site groups, but they justified the convenient and consistent use of ecoregions. [ABSTRACT FROM AUTHOR]

• Diatom MMIs were mainly influenced by in-stream environments. • Natural factors accounted for most variance of in-stream environments. • Natural and human factors covaried, which was important in some regions. • Accounting for natural and covarying effects is important for bioassessments. Streams are influenced by watershed-scale factors, such as climate, geology, topography, hydrology, and soils, which mostly vary naturally among sites, as well as human factors, agriculture and urban development. Thus, natural factors could complicate assessment of human disturbance. In the present study, we use structural equation modeling and data from the 2008–2009 United States National Rivers and Streams Assessment to quantify the relative importance of watershed-scale natural and human factors for in-stream conditions. We hypothesized that biological condition, represented using a diatom multimetric index (MMI), is directly affected by in-stream physicochemical environment, which in turn is regulated by natural and human factors. We evaluated this hypothesis at both national and ecoregion scales to understand how influences vary among regions. We found that direct influences of in-stream environment on diatom MMIs were greater than natural and human factors at the national scale and in all but one ecoregion. Meanwhile, in-stream environments were jointly explained by natural variations in precipitation, base flow index, hydrological stability, % volcanic rock, soil water table depth, and soil depth and by human factors measured as % crops, % other agriculture, and % urban land use. The explained variance of in-stream environment by natural and human factors ranged from 0.30 to 0.75, for which natural factors independently accounted for the largest proportion of explained variance at the national scale and in seven ecoregions. Covariation between natural and human factors accounted for a higher proportion of explained variance of in-stream environment than unique effects of human factors in most ecoregions. Ecoregions with relatively weak effects by human factors had relatively high levels of covariance, high levels of human disturbance, or small ranges in human disturbance. We conclude that accounting for effects of natural factors and their covariation with human factors will be important for accurate ecological assessments. [ABSTRACT FROM AUTHOR]

Microbiological degradation of the racemic mixture, the enantiopure R- and S-fipronil was examined under both aerobic and flooded conditions in three Chinese paddy soils. The degradation kinectics and enantiomer fraction (EF) were determined by means of high-performance liquid chromatography (HPLC) with chiral Chiralcel OD-H column, while desulfinyl, sulfone and sulfide derivatives were monitored by reversed phase HPLC with diode array detection (DAD). The degradation/transformation of enantiomers of fipronil in the three live soils under aerobic and flooded conditions generally complied with the first-order kinetics (R 2 ≥0.94). The calculated t1/2 values of the enantiomers of fipronil ranged between 21 and 34 days for aerobic incubation experiments and between 8 and 19 days under flooded conditions incubation, respectively. The calculated EF values of fipronil during the incubation time were all close to 0.5, indicating that the degradation/transformation of fipronil was almost nonenantioselective. The main metabolites of fipronil formed in the incubation experiments were sulfone and sulfide derivatives by oxidative and reductive processes, respectively. The oxidative pathway seemed more active. Under flooded conditions, S-fipronil was preferentially degraded in the three soil samples used. The main metabolite was determined as fipronil sulfide. In control experiments, almost no removal of enantiomers of fipronil was observed indicating that the degradation of fipronil in the paddy soil used was attributed to microbial mediated processes under both aerobic and flooded conditions. In addition, no enantiomerization of fipronil was observed in the soil samples examined under both aerobic and flooded conditions. These results for major differences in the degradation of the enantiomers as well as the formation of toxic metabolites may have some implications for better environmental and ecological risks assessment for chiral pesticides. [Copyright &y& Elsevier]

Abstract Carbon dioxide and other greenhouse gas emissions leads to global warming. Biological capture through microalgae is a potential approach for solving this environmental problem. It is still a technical challenge to enhance the tolerance of microalgae to flue gas if CO 2 is fixed from flue gas directly. A new strain, Chlorella sp. Cv was obtained through adaptive evolution (46 cycles) against simulated flue gas (10% CO 2 , 200 ppm NO x and 100 ppm SO x). It was confirmed that Chlorella sp. Cv could tolerate simulated flue gas conditions and the maximum CO 2 fixation rate was 1.2 g L−1 d−1. In a two-stage process, the biomass concentration was 2.7 g L−1 and the carbohydrate content was 68.4%. Comparative transcriptomic analysis was performed for Chlorella sp. Cv under simulated flue gas and control conditions (10% CO 2). These responses against simulated flue gas uncovered the significant difference between the evolved strain and the original strain. The metabolic responses to flue gas were explored with focus on various specific genes. Upregulation of several genes related to photosynthesis, oxidative phosphorylation, CO 2 fixation, sulfur metabolism and nitrogen metabolism was beneficial for the evolved strain to tolerate the simulated flue gas. The upregulation of genes related to extracellular sulfur transport and nitrate reductase was essential to utilize the sulfate and nitrate from dissolved SO x and NO x. The results in this study are helpful to establish a new process for CO 2 capture directly from industrial flue gas. Graphical abstract Unlabelled Image Highlights • Chlorella sp. Cv, was obtained by adaptive evolution in 138 days. • Chlorella sp. Cv tolerates 10% CO 2 , 200 ppm NO x and 100 ppm SO x. • The maximum CO 2 fixation rate was 1.2 g L−1 d−1 from simulated flue gas. • Upregulations of photosynthesis and oxidative phosphorylation were identified. • Upregulation of extracellular sulfur transport is helpful to tolerate SO x. [ABSTRACT FROM AUTHOR]

A Chlorella sp.- Cupriavidus necator (C. necator) microcosm was artificially established for phenol degradation. The cooperation relationship between Chlorella sp. and C. necator was initially demonstrated, and then the effects of Chlorella sp./ C. necator inoculation ratio, light intensity, temperature and pH on the performance of this microcosm were systematically evaluated and optimized. The optimal conditions for phenol degradation were as follows: a Chlorella sp./ C. necator inoculation ratio of 1:1, a light intensity of 110 μmol m−2 s−1, a temperature in the range of 25–32 °C and a pH in the range of 5.5–7.5. Under optimal conditions, this microcosm could degrade phenol with a maximum concentration of 1200 mg L−1 within 60 h. It was found that only when the phenol concentration was reduced to the tolerance concentration of microalgae, that is, the last stage of phenol degradation, the cooperation effect could be generated, indicating that the tolerance of microalgae to phenol may be more important than its degradation performance. Comparative transcriptomic analysis was conducted to discuss the cooperation mechanism of this microcosm subject to high phenol concentrations. The up-regulation of genes involved in photosynthesis and carbon fixation of Chlorella sp. demonstrated the CO 2 and O 2 exchange between Chlorella sp. and C. necator and their cooperation relationship. This study suggests that this microcosm has great potential for the bioremediation of phenol contaminants. Unlabelled Image • A Chlorella sp.- Cupriavidus necator microcosm was artificially established for phenol degradation. • The influence of operating conditions on the phenol degradation was systematically evaluated and optimized. • This microcosm could completely degrade 600–1200 mg L−1 of phenol within 60 h. • The CO 2 and O 2 exchange between Chlorella sp. and Cupriavidus necator was discussed with comparative transcriptomic analysis. [ABSTRACT FROM AUTHOR]

With the ever-increasing consumption of polyethylene terephthalate (PET) related products, how to recycle the waste PET still remains as a great challenge for the sustainable development. Converting waste PET into porous carbon material has been emerged as a promising way to address this issue. Recently, the microporous carbon derived from waste PET has drawn considerable attention in adsorption field, but its electrochemical application is still impeded by low specific surface area (SSA <1500 m2 g−1) and small meso-/macropores volume (<0.2 cm3 g−1). Herein, hierarchical porous carbon (HPC) is successfully prepared from waste PET. The obtained HPC possesses a high SSA (2238 m2 g−1) and a large meso-/macropores volume (0.51 cm3 g−1). The formation mechanism of hierarchical porous structure is proposed: co-etching effect of sp2/sp3 hybridized carbon produces micropores and meso-/macropores, respectively. In a three-electrode configuration, HPC based electrode achieves an outstanding capacitance of 413 F g−1, while the traditional microporous carbon exhibits a low capacitance of 142 F g−1. The fabricated symmetric supercapacitor shows a high energy density of 25 Wh kg−1. This work provides a good reference to convert waste plastics into hierarchical porous carbon. Unlabelled Image • Waste polyethylene terephthalate (PET) results in serious ecological disaster. • Carbonization and activation process are applied to convert waste PET into carbon. • Co-etching effect of sp2 and sp3 carbon produces the hierarchical porous structure. • Hierarchical porous carbon from waste PET exhibits a high energy storage capacity. • This work provides a reference for the plastic waste treatment and energy storage. [ABSTRACT FROM AUTHOR]

• We tested ecological drivers of biodiversity indices across subtropical rivers. • Local environmental stressors were more important than the other factor groups. • Taxonomic distinctness indices performed best in portraying human disturbances. • Species and functional diversity indices were also related to climatic and spatial factors. • Bioassessment should consider various factors causing variation in bio-indicators. Metacommunity ecology emphasizes that community structure and diversity are not only determined by local environmental conditions through environmental filtering, but also by dispersal-related processes, such as mass effects, dispersal limitation and patch dynamics. However, the roles of dispersal processes are typically ignored in bioassessment approaches. Here, we simultaneously explored the potential influences of four groups of factors: local stressors, climatic factors, within-basin spatial factors and basin identity in explaining variation in diversity indices of macroinvertebrate assemblages from seven subtropical tributary rivers. A total of 12 biodiversity indices based on species identities, functional traits and taxonomic relatedness were calculated and used in the subsequent statistical analysis. Our results showed that, although differing in their relative importance, the four explanatory factor groups all played important roles in explaining variation in biodiversity indices. Of the pure fractions, index variation was best explained by local environmental stressors, whereas the other three explanatory factor groups appeared less influential. Furthermore, diversity indices from species, functional and taxonomic dimensions responded distinctly to the focal ecological factors, and differed in their abilities to portray the effects of human disturbances on macroinvertebrate communities. Taxonomic distinctness indices performed best, with the highest amount of variation associated to local stressors and hardly any variation explained by other factors, implying that these indices are robust in portraying human disturbances in streams. However, species diversity and functional diversity indices were also affected by spatial processes and climatic factors, suggesting that these indices should be used with caution in bioassessment. We hence conclude that environmental assessment of riverine ecosystems should not rely entirely on the perspective of species sorting. In contrast, both roles of spatial processes and environmental variables related to human disturbances and climatic variation should be incorporated in management and conservation of riverine ecosystems. [ABSTRACT FROM AUTHOR]