The dissipation and terminal residues of difenoconazole in whole bananas and pulp were investigated under field conditions. The residual levels of difenoconazole in various parts of bananas grown in Guangdong, Hainan and Yunnan were determined by a GC-ECD detection method after simple, rapid pretreatment. The mean recovery was 80.66~107.40%, and the relative standard deviation was 3.36~9.84%. The results showed that the half-lives of difenoconazole in whole bananas and in the pulp were 12.16~13.33 days and 17.77~20.38 days, respectively. At harvest intervals of 28 and 35 days after the last application, the terminal residues of difenoconazole in whole bananas and pulp were 0.45~0.84 mg/kg and 0.19~0.37 mg/kg, respectively, which were lower than the maximum residue level established in China. The distribution of difenoconazole in banana pulp and peels was studied. The results showed that until harvesting, the residue in the peels was always 2.19~12.30 times larger than that in the pulp. Difenoconazole was mainly absorbed by the banana peels but did not easily penetrate into the pulp. Based on dietary risk assessment results, the residual levels of difenoconazole at the sampling interval of 28 days after the last application were within acceptable limits for chronic and acute dietary risks in different populations in China. This study can provide a reference for the safe and rational use of difenoconazole as a fungicide and for the future research and application of banana pulp and peels.

Hydrocarbon degradation is usually measured in laboratories under controlled conditions to establish the likely efficacy of a bioremediation process in the field. The present study used greenhouse-based bioremediation to investigate the effects of natural attenuation (NA) and necrophytoremediation (addition of pea straw (PS)) on hydrocarbon degradation, toxicity and the associated bacterial community structure and composition in diesel-contaminated soil. A significant reduction in total petroleum hydrocarbon (TPH) concentration was detected in both treatments; however, PS-treated soil showed more rapid degradation (87%) after 5 months together with a significant reduction in soil toxicity (EC₅₀ = 91 mg diesel/kg). Quantitative PCR analysis revealed an increase in the number of 16S rRNA and alkB genes in the PS-amended soil. Substantial shifts in soil bacterial community were observed during the bioremediation, including an increased abundance of numerous hydrocarbon-degrading bacteria. The bacterial community shifted from dominance by Alphaproteobacteria and Gammaproteobacteria in the original soil to Actinobacteria during bioremediation. The dominance of two genera of bacteria, Sphingobacteria and Betaproteobacteria, in both NA- and PS-treated soil demonstrated changes occurring within the soil bacterial community through the incubation period. Additionally, pea straw itself was found to harbour a diverse hydrocarbonoclastic community including Luteimonas, Achromobacter, Sphingomonas, Rhodococcus and Microbacterium. At the end of the experiment, PS-amended soil exhibited reduced ecotoxicity and increased bacterial diversity as compared with the NA-treated soil. These findings suggest the rapid growth of species stimulated by the bioremediation treatment and strong selection for bacteria capable of degrading petroleum hydrocarbons during necrophytoremediation. Graphical abstract

As a global problem, climate warming has received widespread attention recently. With trade development and labor division deepening, there exist large differences in carbon emission intensity (CEI) embodied in different trade patterns. Assessing environmental costs of different trade patterns is the core issue for policy makers. We decompose the overall CEI embodied in trade into CEI embodied in final goods trade, domestic trade, traditional intermediate trade, and global value chain trade. Using global multi-region input-output table provided by the WIOD database, we calculate the CEI embodied in different trade patterns during 1995–2014. Further, we analyze the influencing factors of CEI embodied in different trade patterns. We find that CEI embodied in domestic trade is lower than that of international trade. All kinds of embodied CEI in developing countries are higher than that in developed countries. Furthermore, the driving factors of the overall embodied CEI, including domestic trade and international trade, are population, PGDP, energy intensity, and trade. The expansion of industrialization can effectively reduce the CEI embodied in trade of developing countries. The increase of PGDP and industrialization can effectively reduce the CEI embodied in trade related to global value chain and traditional intermediate trade, while only the increase of PGDP can effectively reduce the CEI embodied in domestic trade and final goods trade. Population can reduce the embodied CEI in trade related to global value chain and traditional intermediate trade of developed countries. Economic development can almost promote the reduction of the CEI embodied in all trade patterns. Although industrialization has insignificant impact on the CEI embodied in final goods trade of the developed countries, it can reduce such CEI of developing countries.

The ability of vetiver grass (Chrysopogon zizanioides L.) for the reduction of anions and cations especially inorganic nitrogen compounds from the influent and effluent of sewages was investigated. Vetiver grass was grown hydroponically in influent (IN) and four different effluent (EF) sewages including control, 125 (EF125), 250 (EF250), and 500 (EF500) mg L⁻¹ Ca(NO₃)₂. During 18 days, phosphate concentration gradually declined in both influent and all effluent treatments. Unlike effluent treatments, the amount of ammonium in influent was greater than the standard (39.52 mg L⁻¹) and decreased severely down to 4.85 mg L⁻¹ at the end of the experiment. After just 48 h, the concentration of nitrate in EF treatment reached 2.25 mg L⁻¹ that is lower than the standard. The decrease of nitrate to concentrations less than the standard was also observed at days 8, 11, and 18 in EF125, EF250, and EF500 treatments, respectively, and about 90% of nitrate had been removed from 500 mg L⁻¹ Ca(NO₃)₂ treatment. Other ions such as Cl⁻, Ca²⁺, and K⁺ decreased in influent and all effluent sewages due to phytoremediation process. Accordingly, phytoremediation by vetiver grass could decrease concentrations of nitrate, ammonium, phosphate, chloride, and calcium in influent and all effluent sewages. Increasing the concentration of nitrate resulted in the increase in its uptake rate. In addition, a positive correlation was shown between the uptake rate of nitrate by vetiver grass and the duration of cultivation of this plant in nitrate-containing medium.

High alkali-metal sulfate contents in ash from high-alkali coal are a result of the alkali metals’ strong sulfur-capturing capacity. In this work, the effects of sulfates in ash on SO₃ formation were investigated by adding alkali-metal sulfates (Na₂SO₄ and K₂SO₄) to ash and performing experiments to simulate SO₃ formation. The results show that Na₂SO₄ and K₂SO₄ addition significantly increased SO₃ formation and the formation rate increased with increasing temperature. The formed SO₃ concentration increased by 6.8 ppm (adding Na₂SO₄) and 6.3 ppm (adding K₂SO₄) at 1000 °C. These increases are the result of SO₃ release from sulfate during the formation of aluminosilicates such as NaAlSi₃O₈ (albite), NaAlSiO₄ (nepheline), KAlSiO₄ (kalsilite), and KAlSi₃O₈ (feldspar) with the SiO₂ and Al₂O₃ in the ash. This was confirmed by X-ray diffraction (XRD) and thermodynamic calculation. In addition, increasing the SO₂ concentration increased the SO₃ concentration and decreased the SO₃ conversion ratio. Graphical abstract Note: This data is mandatory.

This manuscript communicates the use of cement-coated red bricks for augmenting the production of distilled water using a traditional single slope solar still by low cost energy storage. The exposure area of water is increased in modified solar still (MSS) by keeping the cement-coated red bricks in the absorber. Using the energy storage material in the absorber, the water temperature was higher in the case of MSS at 20 kg water mass which was the minimum mass used during the experiment in the basin. From the results, it was also found that there is an improvement of about 34% in the temperature of water which acts as the driving force for evaporation of water inside the closed chamber. Furthermore, with increase in water temperature the productivity was enhanced by 45% as compared to the CSS. Comparison of different solar still on productivity was also analysed, and it is seen that the yield is higher in the present study by 38.8% than double slope-double basin solar still with different energy storage. The daily yield from CSS for water depth of 20, 30, 40 and 50 was found as 3.2, 2.8, 2.7 and 2.6 kg, whereas the modified solar still produced 6.3, 6, 5. 8 and 5.6 kg, respectively. Due to the reduced daily yield at higher water masses, the cost per litre of water produced from both conventional and modified solar still is higher.

Cadmium (Cd) contamination in the soil-rice chain is the major threat to human health in China. It is very necessary to lower Cd phytoavailability in contaminated soils and reduce Cd transfer from soil to rice for food safety. This study applied the Si-Ca-K-Mg amendment (SCKM) to immobilize Cd in acidic soils and then reduce its accumulation in rice grain (Oryza sativa L.). Two agricultural soils (Alfisol and Ultisol) collected from Eastern China were treated with three levels of Cd concentration (0, 0.4, and 2.0 mg/kg), respectively, for pot experiment. The phytoavailability and chemical forms of Cd in two soils were determined using ethylenediaminetetraacetic acid (EDTA) and the European Community Bureau of Reference (BCR) extraction procedures. At 2.0 mg Cd/kg-treated soils, application of SCKM amendment increased the yield of rice grain by 10–17% for Alfisol and 14–39% for Ultisol, and reduced the concentrations of EDTA-extractable Cd by 6–27% for Alfisol and 5–25% for Ultisol, compared with treatment without amendment. SCKM amendment significantly (p < 0.05) reduced the bioconcentration factor (BCF) of Cd in root, straw, and grain of rice. Compared with treatment without amendment, the application of amendments decreased the Cd concentrations of rice grains by 35–76% for Alfisol and 31–72% for Ultisol, respectively. The BCR sequential extraction revealed that amendment reduced acid soluble Cd fraction by 6.2–13.6% for Alfisol and 6.1–13.5% for Ultisol, respectively, indicating that amendment could effectively transform the highly phytoavailable Cd into a more stable form. SCKM amendment addition significantly (p < 0.05) increased soil pH and exchangeable K⁺, and decreased exchangeable Al³⁺ contents in both soils. Our results demonstrated that SCKM amendment was effective in reducing the phytoavailability and transfer of Cd in soil-rice system, and ameliorating soil acidity. The SCKM amendment had greater potential as a low-cost and friendly environmentally amendment for safe production of rice in Cd-contaminated soils.

In this study, we analyzed the asymmetric short- and long-run causal links between foreign direct investments and emissions in Turkey over the time period 1974–2018. Using hidden co-integration techniques, we defined and tested the asymmetric pollution haven and asymmetric pollution halo hypotheses. To evaluate the long-run asymmetric causal relationship, we estimated both the crouching error correction model and vector error correction model. We performed a stepwise regression model to estimate the crouching error correction model. The empirical results confirmed an asymmetric causal relationship between positive shocks of foreign direct investments and positive movements in emissions in the short run as well as an asymmetric causal link between negative and positive shocks of foreign direct investments and positive emissions in the long run. Furthermore, the results showed that increases in foreign direct investments led to a decrease in the rate of emission growth in both the short and long run. This finding supports the validity of the asymmetric pollution halo hypothesis in Turkey’s case. Policymakers should strengthen their environmental protection laws to protect the quality of their environments as well as implement policies that encourage the use of clean technology and tax incentives that increase foreign direct investment inflows. Graphical Abstract

Excess sludge contains a high amount of protein, which can be recovered to prepare protein foaming agents and other products with high added value. Enzymatic hydrolysis (EH) is a promising technology for the recovery of protein from excess sludge, and ultrasound has been identified as a potential method to assist in sludge disintegration. Ultrasonic pretreatment was combined with alkaline protease hydrolysis to extract protein from excess sludge produced by A²/O treatment (S1) and an oxidation ditch treatment (S2), and the extraction effects and changes in sludge dewatering performance were studied. The effects of the six factors ultrasonic power density, ultrasonication time, enzyme dose, pH, hydrolysis temperature and hydrolysis time were analyzed. The results showed that the ultrasound-enhanced enzymatic method could effectively extract sludge protein. Although the extraction efficiencies for the different municipal sludges were different, their extraction conditions were relatively similar. Considering the protein extraction rate and sludge dewatering performance, the selected extraction conditions were as follows: ultrasonic power density, 1 W/mL; ultrasonication time, 20 min; enzyme dose, 3500 U/g; pH 11; hydrolysis temperature, 60 °C; and hydrolysis time, 3 h. Under these conditions, the protein extraction rate (Rₚ) of S1 and S2 reached 55.9% and 52.3%, respectively. Moreover, the improvement in sludge dewatering performance (Dw) of S1 and S2 was 49.5% and 52.4%, respectively. Comparison of the protein, polypeptide, and amino acid contents obtained from ultrasound-assisted enzymatic hydrolysis (UEH), EH, and ultrasonic hydrolysis (UH) further demonstrated the beneficial effect of ultrasound application on enzymatic hydrolysis.

Bioretention cell (BRC), bioretention cell with microbial fuel cell (BRC-MFC), and an enhanced combined BRC-MFC system with bimetallic zero-valent iron (BRC-MFC-BZVI) were implemented in current study to treat the domestic wastewater. Nitrogen removal characteristics of three systems were investigated by adjusting influent carbon/nitrogen ratio (C/N ratio of 2.54–19.36). Results revealed that the nitrification and denitrification performances were mainly influenced by organic matter and system combination, which further affected nitrogen removal. When the influent C/N ratio was between 2 to 3, compared with BRC system, in BRC-MFC and BRC-MFC-BZVI system, chemical oxygen demand (COD), total nitrogen (TN), and ammonical nitrogen (NH₄⁺-N) removal efficiencies were still reached to 83.04%, 61.06%, and 42.26% and 86.53%, 43.61%, and 50.99% respectively, which simultaneously achieved high-efficiency of organic matter and nitrogen removal. The efficient supply of electrons in the BRC-MFC and BRC-MFC-BZVI processes was the main reason to achieve profound denitrification removal under the condition of low C/N. Removal rates of nitrate (NO₃⁻−N) and nitrite (NO₂⁻−N) were relatively higher due to microbial-driven redox reactions caused by driving electrons to flow in the closed circuit of metal wire connection. Moreover, phylogenetic diversity of bacterial communities mainly induced the catalytic iron, which further enhanced biological nitrogen reduction. The maximum efficient removal of organic matter (OM), TN, and NH4 + −N were obtained in the BRC-MFC-BZVI system, which were 98.42% (C/N = 10.42), 55.61% (C/N = 4.16), and 61.13% (C/N = 4.16), respectively.