The goal of this study was to identify antibiotics with potential risk in river water of the megacity Beijing, China. This was accomplished by using a tiered approach that combined hazard (phase I) and monitoring-based risk (phase II) assessment. Ninety-five candidate antibiotics were screened and 31 was identified as hazardous during phase I assessment. Of these hazardous antibiotics, 29 were identified as persistent and 7 were identified as bioaccumulative antibiotics. Fluoroquinolones, macrolides, sulfonamides, and aminoglycosides account for over 80% of these hazardous antibiotics. During phase II, four antibiotics (erythromycylamine, cefotaxime, ampicillin, and fusidic acid) that were not previously reported were detected in the surface water sampled from four major rivers in Beijing, with concentrations ranging from not detected to approximately 300 ng/L. The ecological risk assessment showed that erythromycylamine, cefotaxime, and ampicillin posed low to high levels of risk to the aquatic organisms. To summarize, erythromycylamine, cefotaxime, and ampicillin were identified as priority antibiotics in rivers in Beijing, China. Our results demonstrated the necessity of conducting monitoring-based verification process in identification of priority antibiotics in a specific region.

The purpose of this study is to investigate the elution behavior of pool-dominated dense nonaqueous phase liquid (DNAPL) source zone mass during enhanced solubilization remediation. Flow-cell experiments were first conducted to investigate the performance of different solubilization agents on the DNAPL source zone mass removal in porous media. PCE was used as the model organic liquid, while sodium dodecyl sulfate and Tween 80 surfactants, methyl cyclodextrin (MCD) were selected as enhanced-flushing agents. The porous media considered were silica sand and natural calcareous soil. To gain further insight into the dynamics of source zone depletion, the flushing experiments were modeled using two approaches: a multiphase flow model and a simplified empirically based concentration mass discharge (CMD) model. Results of the flushing experiments indicated that the performance of solubilization agents on PCE source zone depletion was in the following order: Tween 80 > SDS > MCD > > Water. Both models reveal the non-ideal behavior observed during the flooding experiments. For all cases considered, the later stage of mass removal appears to be controlled by the portion poorly accessible mass associated with higher-saturation zones. The advantages and limitations of the two modeling approaches are discussed. It is shown that the two modeling approaches are complementary to each other. Whereas the multiphase model can reveal important aspects of the governing pore-scale processes, the latter approach can provide valuable source term depletion metrics, circumventing the need for detailed definition of DNAPL and porous media parameters.

The development of mixed microbial agents can reduce the use of pesticides and fertilizers in agriculture. However, most previous studies focused only on the overall effects of mixed microbial agents and ignored the interactions between bacteria in mixed systems. In this study, Bacillus subtilis SL-44 and Enterobacter cloacae Rs-2 were used to explore the interactions between two different functional plant growth-promoting rhizobacteria (PGPR). The plant growth-promotion properties and inhibition rate of Rhizoctonia solani were determined, and the mechanism of the interactions under single and co-culture conditions was elucidated via transcriptomics analysis under single and co-culture conditions. Results showed that the co-culture was not conducive to B. subtilis SL-44 growth. Furthermore, the differentially expressed genes related to B. subtilis SL-44 developmental process and cell differentiation were downregulated by 82.7% and 84.8% respectively. Moreover, among the properties, only siderophore production by the mixed culture was higher than that of single cultures because of the upregulation of the siderophore-related genes of B. subtilis SL-44. In addition, results revealed the altruistic relationship between the two strains, and the chemical and non-chemical signals of their interaction. This study provides unique insights into PGPR interactions and offers guidance for the development and application of mixed microbial agents.

This study is the first proper attempt to examine the influence of energy poverty on productivity. Specifically, the study investigates the effects on the level and convergence of total factor productivity of no access to clean fuels and technologies for cooking; no access to electricity in the total population; no access to electricity in the rural population; no access to electricity in the urban population; non-renewable electricity production; and non-renewable electricity consumption. The study examines a global sample of 45 developing countries from 2002 to 2017 and offers three empirical analysis findings. First, the mutual causalities between the five dimensions of energy poverty and total factor productivity are shown by a non-Granger causality test for panel data, except one-direction causality from no access to clean fuels and technologies for cooking to total factor productivity convergence, which hints a ‘vicious cycle’ of two variables. Second, the two-step system generalised method of moments estimates show significant negative impacts of no access to clean fuels and technologies for cooking and the three variables of no access to electricity on total factor productivity. In contrast, the production and consumption of non-renewable electricity appear to have significant positive effects. Third, the three-stage least squares estimates provide statistical evidence that the effects of energy poverty on total factor productivity are transmitted through human capital accumulation, Internet usage, and the shadow economy.

A thorough understanding of the processes and driving factors of ion migration, dilution, and enrichment in arid inland river basins is the basis for implementing water resources management. In this study, we analyzed the water chemistry of streamflow, groundwater, and precipitation and the behavior of main elements in the Shiyang River Basin by means of the hydrochemical diagram and multivariate statistical analysis. The spatial variation of water chemistry was obvious, and the conversion between different water bodies was frequent. The ions migrated from the mountain area to the oasis and desert and accumulated near the terminal lake finally. There were obvious differences in hydrochemistry between surface water and groundwater. From the mountain to the basin, the hydrochemical type of surfer water has varied, and the hydrochemical type of groundwater has changed from Ca–Cl type to Na–Cl type. The hydrochemistry of the basin was controlled by silicate weathering. However, the influence of water–rock interaction on surface water and groundwater was different, and the surface water was more complex. Significantly, agricultural activities and sewage discharge had a negative impact on the water environment. Interbasin water transfer (IBWT) was a form of external ions input from outside the basin, which affected the chemical characteristics of surface water in the lower reaches to a certain extent. In arid areas, human impact on water chemistry needs to be paid attention. These results are helpful to strengthen the understanding of the relationship between different regions and different water bodies in the arid basin.

Cyanobacteria are microorganisms capable of releasing toxic metabolites in freshwater, deleterious to humans and other living organisms even in very low concentrations. Removing both cyanobacteria cells and their metabolites in conventional water treatment systems is still a challenge that needs to be addressed. This paper evaluated the use of Moringa oleifera saline extract and polyaluminum chloride (PACl) as coagulants in order to remove cells and metabolites of M. aeruginosa from water. Samples consisted of synthetic water spiked with humic acid and M. aeruginosa cells, with a final turbidity of 25 NTU. Coagulation/flocculation/dissolved air flotation (C/D/DAF) tests were performed with 50 mg/L of M. oleifera coagulant, combined with different proportions of PACl (10–50%). For removal of metabolites, 25 μg/L of microcystin and 50 ng/L of 2-MIB and geosmin were spiked in water samples. The best results were obtained with 70:30 M. oleifera:PACl, achieving removal efficiencies of 81.37%, 74.69%, and 71.06% for turbidity, color, and cell density, respectively. For microcystin, 2-MIB, and geosmin, after filtration (30 min), global removal efficiencies (clarification + filtration) of 99.45%, 62.37%, and 100%, respectively, were obtained, using Sand+GAC filter. The results suggest that the substitution of PACl by M. oleifera extract can be a good option to remove cyanobacteria cells from water, and high removal efficiencies of metabolites can be achieved after the complete proposed treatment.

The synthetic organic surfactants linear alkylbenzene sulfonate (LAS) and polycyclic aromatic hydrocarbon naphthalene (NAP), two common organic pollutants, are frequently detected in freshwater environments. However, the combined ecotoxicological risks associated with these pollutants have not been fully elucidated. The present study investigated the effects of individual and combined treatments of LAS and NAP on the growth and physiological responses of Spirodela polyrrhiza. The results showed that LAS was the main compound toxic to S. polyrrhiza in a dose-dependent manner. The peroxidase (POD) enzyme and catalase (CAT) enzyme are the main antioxidant enzymes protecting S. polyrrhiza from LAS stress. When exposed to NAP stress alone, only slightly reversible damage was observed as the exposure time was extended (14 days). The antioxidant enzyme systems (including superoxide dismutase (SOD), CAT and POD) showed positive responses. Synergistic effects were induced with LAS-NAP mixtures (≥ 5 + 5 mg L⁻¹), and LAS played a major toxic role. The POD enzyme was a sensitive protective enzyme in duckweed during the joint exposure to LAS + NAP. The results indicate that LAS or NAP may cause serious damage to S. polyrrhiza and aggravate ecotoxicity in aquatic ecosystems.

Crop production systems involving the use of high rates of fertilizer application caused significant losses of nitrogen (N) and phosphorus (P) to the environment, resulting in air pollution and water body eutrophication. Quantitating N and P losses and its drivers in crop production systems was critical for optimizing water and fertilizer management measures to mitigate the nutrient losses. However, N and P losses estimation remains highly uncertain in the field at event scale. We here quantify daily N and P losses and its drivers (daily N and P water input, N and P uptake, N and P water surplus, water loss, etc.) in rice-rapeseed growing systems by high-frequency field experiments at event scale in Central China. Results revealed that there were significant trade-off relationships between daily uptake and surplus for N and P during the whole growing stages both for rice and rapeseed. Although it was not significantly related in heading to mature stage for rapeseed, synergies between daily input or surplus and loss were found for N. Redundancy analysis revealed that water input and leaching loss contributed most for N and P loss in rice and rapeseed. The nutrient losses in easier stages should be reduced by postponing the base fertilizer and making it in line with the crop uptake. The study enhanced our knowledge of N and P losses mechanism for crop production systems and provided a scientific basis for optimization of water and fertilizer managements and N and P loss estimation models.

The objective of the manuscript was to evaluate the concentration and distribution of nutrients and heavy metals (HMs) in the sediments of urban lakes, as well as the potential ecological risk to the lake. This paper discusses the risk assessment and its management via potential nature-based solutions (NBS), which are lessons learnt from nature. The HM pollution and potential ecological risk were evaluated using conventional geo-accumulation index (GI) and geo-accumulation vector (GV) model. So urban lakes are usually more of a source of pollution than non-urban lakes, and more widely based on the literature on lake sediment pollution assessments in China over the past 10 years, 42 urban lakes, and 5 typical non-urban lakes (five representative freshwater lakes in China) were selected. The average concentrations of total nitrogen (TN); total phosphorus (TP); and Cu, Zn, Pb, Cr, Cd, Ni, As, and Hg were 2382, 712, 33.10, 118.05, 38.30, 66.40, 0.82, 32.38, 11.33, and 0.12 mg/kg, respectively. The pollution levels of nutrients and HMs in sediments were evaluated using a single pollution index, a comprehensive pollution index, a ground accumulation index, a potential ecological risk index, and a sediment quality index. The evaluation results showed that the overall pollution level of urban lake sediments in China was higher than that of the selected five typical non-urban lakes, and the problem of nitrogen pollution in sediments was more prominent. There was no significant difference in the potential risk assessment of HMs between urban lakes and typical non-urban lakes, but the probability of negative biological effects was significant. The surface sediments from the estuaries of the tributaries flowing downtowns and heavy industrial parks showed high heavy metal pollution levels and potential ecological risk. The HM pollution and environmental risk assessment of the sediments from urban lakes is of great significance.

The effects of urbanization on carbon emissions (EUCE) are complex, while rare work has comprehensively elaborated on how various aspects affect and develop. In this study, utilizing Citespace and VOSviewer software, a global scientometric visualization analysis was conducted to excavate various impacts and future trends of urbanization on carbon emissions. Based on publications from the year 1982 to 2018, the spatial-temporal distribution of publications, collaboration, current hotspots, and future trends of EUCE were carried out. The results indicated that between 1992 and 2018, there were accelerated increasing trends of EUCE researches world widely, among which China, the USA, and UK ranked the top 3. Relevant research firstly appeared in the USA, while grew most rapidly in China. Research subjects mainly concentrate on population migration, resource consumption, land use and land cover change (LULCC), energy conservation, non-carbon greenhouse gases like CH₄ and N₂O. And attention on carbon footprint has become a hotspot for carbon mitigation. For research fronts, ecosystem service offered by urban green space has gradually evolved as a research focus. Besides, energy transformation technology is critical for mitigating carbon emissions and has become an important concern in the future development. Furthermore, the timeline visualization analysis indicates that all the research topics related to EUCE are cited and connected with each other, reflecting the necessity of interdisciplinary integration in scientific research. Overall, our study has provided a quantitative visualization on the current situation and future trends of EUCE subject, which will be helpful to subsequent research and policy guidance.