This study investigated the prevalence of antibiotic-resistant bacteria and genes in fecal sludge and soil in Ho Chi Minh City, Vietnam, and identified the factors contributing to the survival of antibiotic-resistant bacteria in soil. Sludge and soil samples (n = 24 and 55, respectively) were collected from residential septic systems and environmental reservoirs (i.e., canals, rivers, and parks) in twelve districts of Ho Chi Minh City and tested against a library of 12 antibiotic-resistant genes and 1 integron gene. The susceptibility of isolated Escherichia coli from sludge and soil (n = 104 and 129, respectively) was tested against nine antibiotics. Over 60% of sludge and soil samples harbored sul1, ere(A), intI1, cmIA, and tet(A) genes. The three most common phenotypic resistances found in E. coli isolated from sludge and soil were to ampicillin, tetracycline, and sulfamethoxazole/trimethoprim. In a temporal microcosm study of antibiotic-susceptible and multi-drug-resistant E. coli inoculated in soil, temperature (21.4 vs. 30 °C), resistance phenotype, and soil background microbial community were associated with E. coli decay rates over 73 days. This is the first study that provides insights into the high prevalence of antibiotic resistance in septic systems and environmental reservoirs in Ho Chi Minh City, Vietnam. Findings highlight that the fecal sludge and soil environments in Vietnam are likely reservoirs for dissemination of and human exposure to antibiotic resistance.

Pharmaceutical contamination in diverse water resources has been recognized as an emerging concern in environment because of its wide distribution and adverse effects on aquatic microorganisms and human health. Plant remediation with augmentation of microorganisms is a cost-effective and environmentally friendly approach toward an efficient treatment of pollutants, which can be easily applied in situ. (Bio)degradation of sulfamethazine (SMZ) by Iris pseudacorus, microalgal consortium, and plant–microalgal consortium was investigated. I. pseudacorus and microalgae could remove 63.5, and 25.8% of 1 mg SMZ L⁻¹, respectively, whereas, the plant–microalgal consortium achieved 74% removal. The identified intermediates extracted after plant remediation indicated (bio)degradation of SMZ was through ring cleavage, hydroxylation, and dehydroxylation. Pigment content (total chlorophyll and carotenoid) of I. pseudacorus was significantly influenced by SMZ stress. A phytoreactor (20 L) constructed with I. pseudacorus achieved 30.0% and 71.3% removal of 1 mg SMZ L⁻¹ from tap water and nutrient medium. This study has provided a better understanding of the metabolic mechanisms of SMZ in plants and showed the potential development of a plant–microalgal consortium as an advanced technology for treatment of these emerging contaminants. Graphical abstract

Few plant species used for revegetation grow well in multi-metal-contaminated soils. Vetiver grass (Vetiveria zizanioides) is known to be tolerant of heavy metals. Vetiver has been reported to be effective for revegetation and heavy metal phytoextraction by applying targeted amendments due to its large biomass. In this study, a greenhouse vetiver pot experiment and soil incubation were performed to investigate the growth and Cd, Cr, Cu, Pb, and Zn uptake of vetiver grown in multi-metal-contaminated soils treated with a CaO-activated Si-based slag amendment (0, 0.5, 1.0, and 2.0% w/w). The results showed that the effects of slag amendment on plant growth and heavy metal uptake and distribution were dependent on the amendment dosages and metal species. Although vetiver could grow in contaminated soils, its growth was obviously inhibited. The slag amendment enhanced the vetiver growth and the highest biomass (2.62-fold over the control) was determined at a 1.0% amendment rate. The slag amendment improved plant growth by alleviating the toxicity of heavy metals in plants. This result was mainly attributed to the increases in soil pH and citric acid-extractable Si caused by alkaline amendment. The results suggest that vetiver can be applied to remediate multi-metal-contaminated soils in conjunction with the application of CaO-activated Si-based slag amendment.

The present work is aimed to analyze the performance and emission characteristics of mahua biodiesel-fueled diesel engine with copper oxide nanoparticle at various particle sizes (10 and 20 nm) and the results compared with conventional diesel fuel (BD). Experiments were conducted in a four-stroke, single-cylinder, constant speed, and naturally aspirated research diesel engine with an eddy current dynamometer. Conventional transesterification process is carried out to convert the raw mahua oil into mahua oil biodiesel (BD100). Copper oxide (CuO) was chosen as a nanoparticle; the mass fraction of 100 ppm and the particle sizes of 10 and 20 nm were blended with mahua oil methyl ester using an ultrasonicator, and the physicochemical properties were measured. The physicochemical properties of BD100 and nanoparticle-included BD100 are at par with EN14214 limits. Brake-specific fuel consumption (BSFC) of BD100 is higher than that of diesel, and brake thermal efficiency (BTE) is lower than that of diesel (D100). The inclusion of 10-nm particle size of CuO nanoparticle in BD100 improves the BSFC and BTE by 1.3 and 0.7%, respectively, when compared with BD100. The CuO nanoparticle inclusion at 20-nm nanoparticle in biodiesel further improves the performance parameters than those at 10-nm nanoparticle. Further, the BD100 promotes a lower level of smoke emissions, carbon monoxide (CO), and hydrocarbon (HC) and with a prominent increase in oxides of nitrogen (NOₓ) emissions. The inclusion of 10-nm particle size of CuO nanoparticle in BD100 reduces the NOₓ, HC, CO, and smoke emission by 3.9, 5.6, 4.9, and 2.8%, respectively, at peak load condition when compared with BD100. The addition of CuO nanoparticle at 20-nm nanoparticle in biodiesel further reduces the NOₓ, HC, CO, and smoke emissions.

Northeastern China has long-term densely tilled soils that supply approximately 20% of the annual total national grains. There are very few reports on the agricultural soil quality subjecting to the predatory tillage. Here, the soil quality index (SQI) of a brunisolic soil was calculated using the minimum data set (MDS) and integrated quality index (IQI). The topsoil layer was divided into plow layer (11.9 ± 1.9 cm) and plow pan (11.4 ± 2.6 cm) in fields of high yields (HYB), medium yields (MYB), and low yields (LYB). Our results showed that the MDS of the topsoil layer only contained chemical indicators. The bulk density (BD), as one of the most important soil quality indicators, was found of no significant differences in the topsoil layers. In different layers (i.e., the topsoil layer, plow layer, and plow pan), the value of SQI presented a consistent tendency of HYB > MYB > LYB (p < 0.05). The correlation between SQI and yield was higher in the plow layer (0.60) and plow pan (0.63) than the topsoil layer (0.47). This further verified the reasonability of using soil stratification for SQI calculation. Our findings indicate the potential of using soil quality assessments to examine soil productivity (e.g., fertilizer deficiency) in crop lands with soil stratification.

Microbial-derived biodiesel was tested on a lab scale CI diesel engine for carrying out exhaust emission and performance characteristics. The performance, emission, and combustion characteristics of a single cylinder four stroke fixed compression ratio engine when fueled with microbial bio-diesel and its 10–30% blends with diesel (on a volume basis) were investigated and compared with conventional diesel. The bio-diesel was obtained from microbes which were grown by combining distillery spent wash with lignocellulosic hydrolysate at nutrient deprived conditions. The microbes consumed the wastes and converted the high strength waste water into lipids, which were trans-esterified to form bio-diesel. Testing of microbial bio-diesel blends with ordinary diesel at different loading pressures and the emission characteristics were compared. Results indicate that with increasing of the blends, reduction of HC and CO emissions were observed, whilst brake thermal efficiency maxed out at 20% blending. Further increase of blends showed a tendency of increasing of both emissions in the exhaust stream. The Brake Specific Fuel consumption was observed to decline with blending until 20% and then increased. The nitrogen oxide emissions, however, were found to increase with increasing blend ratios and reached a maximum at 20% blend. The escalation of HC, CO, CO₂, and NOx emissions was also observed at higher blending ratios and higher engine loads. The performance studies were able to show that out of the three blends of biodiesel, 20% biodiesel blend was able to deliver the best of reduced hydrocarbon and carbon monoxide emissions, whilst also delivering the highest Brake thermal efficiency and the lowest Brake Specific Fuel consumption.

This study attempts to investigate the relationship among electricity consumption, economic growth, and employment in China. Distinct from most of the previous studies, our empirical research identifies a long-run equilibrium cointegration relationship among the three covariates during the period of 1971–2009 with the recently developed autoregressive distributed lag (ARDL) bounds testing approach. The parameters are estimated through a long-run static solution of the estimated ARDL model and short-run dynamic solutions of the error correction model. The estimated models successfully pass diagnostic tests and both the long-run and short-run elasticities are found to be statistically significant. The study also indicates the existence of short-run and long-run causalities from electricity consumption and employment to economic growth. Results of this study show that electricity serves as an important driver of economic growth. Based on these results, several policy prescriptions on energy use and economic development are suggested for China.

Halophytes have several advantages to be more effective in metal phytoextraction. Little is known about the Cd-phytoextraction potential of Atriplex lentiformis under different levels of Cd. Seven levels of Cd (0, 40, 80, 120, 160, 200, and 240 mg per kg of soil) were added to A. lentiformis plants grown on pots filled with 5 kg of sandy loam soil. A. lentiformis plants achieve different defense mechanisms to meet the high concentration of Cd in the soil and plant. These mechanisms include reducing the number and area of leaves, minimizing chlorophyll synthesis, and enhancing synthesizing of oxalic acid, phenols, and proline. The critical point of Cd was 9.35 and 183 mg kg⁻¹ for available soil Cd and leaves concentrations, respectively. The maximum level of Cd displayed a 66% decrease in the chlorophyll content of the leaves. On the other hand, the oxalic acid, phenols, and proline in the leaves were increased significantly by 129, 100, and 200% when Cd increased from 0 to 240 mg. The tested plant removed 3.6% of the total soil Cd under the low Cd concentration (40 mg) but under the high level of Cd (240 mg), it only removed a negligible amount of soil Cd (0.74%). The current study confirmed that A. lentiformis plants lost the ability to cleanup Cd from contaminated soil under the high levels of contamination due to the high reduction in the production of dry matter.

Bacteria-derived biochars from Bucillus sp. biomass under different pyrolysis temperature (250 °C, 350 °C, 450 °C, and 550 °C, respectively) were prepared, forming polyptychial, mesoporous graphite-like structure. The adsorption and sequestration efficiencies of Cd²⁺ by these biochars were evaluated, and the underlying mechanisms were then discussed. Cd²⁺ sorption data could be well described by Langmuir mode while the pseudo-second-order kinetic model and Elovich model best fitted the kinetic data. The functional groups complexation, cation-π interactions, and interaction with minerals (including surface precipitation with phosphorus and ion exchange) jointly contributed to Cd²⁺ sorption and sequestration on biochar, but the interaction with minerals played a dominant role by forming insoluble cadmium salt composed by polycrystalline and/or amorphous phosphate-bridged ternary complex. The maximum sorption capacity of BBC350 in simulated water phase of soil for Cd²⁺ was 34.6 mg/g. Furthermore, the addition of bacteria-derived biochars (1%, w/w) decreased the fractions easily absorbed by plants for Cd in the test paddy soils by 1.9–26% in a 10-day time. Results of this study suggest that bacteria-derived biochar would be a promising functional material in environmental and agricultural application.

This study was conducted to investigate the effects of maternal exposure to bisphenol A (BPA) on testis development of F1 male mice. The BPA exposure model of pregnant mice was prepared by intragastric administration of BPA at the doses of 0, 2.5, 5, 10, 20, and 40 mg/kg/day at gestation day (GD) 0.5–17.5. The testis index of the offspring mice was calculated at postnatal day (PND) 21 and PND 56. The results showed that maternal exposure to 20 mg/kg BPA during pregnancy significantly increased the testicular index of F1 males at PND 21, and 40 mg/kg BPA significantly decreased the testicular index of F1 males at PND 56 (P < 0.01). BPA significantly reduced serum testosterone (T) and estradiol (E₂) levels, and improved testicular ERα and ERβ levels in F1 males at both PND 21 and PND 56. BPA exposure also upregulated transcription of testicular Dnmt1 and inhibited the transcription of testicular Dnmt3A and Dnmt3B in F1 mice at PND 21. BPA reduced the transcriptional level of testicular DNA methyltransferase (Dnmt), increased the expression of testicular caspase-7, caspase-9, and bax, and decreased the expression of bcl-2 in F1 mice at PND 56. Consistent with that, BPA improved the apoptosis rate in the testis at PND 56 (P < 0.01 or P < 0.05). Our study indicates that BPA disrupts the secretion of testosterone, estradiol, and estrogen receptors by interfering with the transcription of testicular DNA methyltransferase (Dnmt) in offspring males, which damages testicular tissues and affects the potential reproductive function.