Anthropogenic activities have resulted in severe environmental degradation. Untreated wastewater from tanneries is hazardous to all kinds of life on earth. Effluent from tanning industries, containing large amount of Cr, is used to irrigate the crops in Pakistan. The current experiment was carried out to study the effects of tannery wastewater on spinach and the role of lysine-Zn in mitigating the severity of stress. The plants were grown in soil and the following treatments were used: irrigation with 0%, 33%, 66%, and 100% wastewater (ww) along with two doses (0 mM, 10 mM) of Zn-lysine. Foliar application of zinc-lysine enhanced the plant growth, biomass, Zn contents, photosynthesis, and enzyme activities in different tissues of plant. Zinc-lysine (10 mM) considerably decreased the Cr content in roots and shoots, along with ameliorating the oxidative stress by enhancing the activities of antioxidant enzymes in plants. Addition of Zn-lys (10 mM) improved the plant height by 19%, root length by 57%, leaf dry weight by 19%, and root dry weight by33% under 100% Cr treatment. Zn-lys significantly reduces the oxidative stress and concentration of Cr as compared with the Cr treatments alone. Application of Zn-lys (10 mM) reduced the Cr contents in roots by 27 and 22 under 33 and 66% Cr treatment, respectively. Taken together, Zn-lys chelates efficiently ameliorated the toxic effects of chromium. Zn-lysine has the extravagant potential of mitigating the heavy metal toxicity without harming the normal growth and development of the plants.

This study reports on acetylsalicylic acid (ASA) biosorption onto fungal-bacterial biofilm supported on two types of activated carbons (one commercial type made of coconut fibers, CAC, and one other manufactured from fruit rinds of Hymenaea stigonocarpa Mart., HYAC, which after biofilm inoculation, they were named CAC-b and HYAC-b), via batch and fixed-bed experiments. These materials were characterized by BET Specific Surface Area and Scanning Electronic Microscopy (SEM). Biosorption onto HYAC-b was 57.2% higher than HYAC. Despite presenting the highest biosorption capacity over time (qₜ = 85.4 ± 0.82 mg g⁻¹), CAC-b had a lower increase in efficiency (32.4%) compared to CAC. Kinetic data from the biosorption experiments responded well to the pseudo-first-order model thus suggests the predominance of physisorption, while without biofilm presence, there was a better agreement with the pseudo-second-order model, suggesting chemisorption. The possible interaction mechanism of ASA to biofilm was attributed to ionic forces between the drug in anionic form and eventual presence of cationic by-products of the biologically active surface metabolism. Biosorption equilibrium data responded better to the Sips model and CAC-b presented the highest biosorption capacity (qₑ = 292.4 ± 2.01 mg g⁻¹). A combination of faster volumetric flow rates, higher inlet concentrations and shorter beds accelerated the breakthrough time of ASA biosorption in the fixed-bed experiments. These operational conditions affected C/Cₒ ratio in the following magnitude order: volumetric flow rate < inlet concentration < bed height. Breakthrough data responded better to the modified dose-response model compared to Thomas and Yoon-Nelson models.

This study evaluates the filtration potential of the biomass obtained from Andropogon grass (Andropogon gayanus Kunth cv. Planaltina) that was converted to biochar by pyrolysis. The biochar is used in filtration systems for the post-treatment of paint industry effluents. The biomass is characterized by elemental analysis (CHSN-O), determination of specific compounds (cellulose/hemicellulose/lignin), FTIR, and SEM. The produced biochar is characterized by SEM, TGA, and surface area analysis. The efficiency of the filters is evaluated by the following parameters: color, turbidity, removal of total solids (suspended and sedimentable), chemical oxygen demand (COD), and metals (Al, Cu, Zn, Co, Cd, and Cr(VI)). Over 99% removal of aluminum, cadmium, and hexavalent chromium is achieved. Moreover, almost 100% of COD and solids are removed, whereas turbidity and color are reduced by over 90%.

The occurrence of plastic particles in aquatic environment has led to enormous concern in the past few years. The sorption behaviors of harmful organic compounds by plastic particles can increase their concentrations by several orders of magnitude influencing their global transport in the marine environment. Five types of mesoplastics (5–20 mm) and five types of microplastics (< 5 mm) were selected to investigate the sorption behaviors of three typical organic compounds (phenanthrene, nitrobenzene, and naphthalene). For phenanthrene, most microplastics have stronger sorption ability than that of mesoplastics due to the higher specific surface area (SSA). However, the sorption ability of nitrobenzene on low-density polyethylene (LDPE) mesoplastics was higher than that on LDPE microplastics, and the sorption ability of naphthalene on polyvinyl chloride (PVC) mesoplastics was higher than that on PVC microplastics, which were attributed to the presence of functional groups on the surface of mesoplastics, induced by adding slip agents, lubricant, plasticizer, stabilizer, etc. during film production. Talcum-filled polypropylene (PP) microplastics had strongest sorption ability to nitrobenzene and naphthalene due to the presence of talcum and high SSA. For unmodified microplastics, the sorption abilities of phenanthrene, nitrobenzene, and naphthalene were all followed the order of high-density polyethylene (HDPE) > polystyrene (PS) > LDPE > PVC after SSA normalization. Thus, SSA and the functional groups on the surface of plastic particles should be considered when the sorption behaviors of harmful organic compounds on plastic particles are studied.

Atmospheric precipitation is a very important link in the water cycle. The characteristics of major ions (n = 341) and stable isotopes (δ²H, δ¹⁸O; n = 157) were analysed in Hangzhou and Huzhou, which are economically prosperous cities in East China. The δ²H and δ¹⁸O values of precipitation ranged from − 109.70 to 21.30‰ and from − 14.87 to − 0.95‰, respectively. Compared with the local meteoric water line (LMWL) of China, the slope and intercept of the LMWL were much higher in Hangzhou and Huzhou, which is related to the effects of the humid climate and less secondary evaporation. The δ²H and δ¹⁸O values were highest in spring because of the influence of air masses from the northern Asian continent and other nearby sources. In contrast, the air masses from the South China Sea and the western Pacific Ocean in the summer had the lowest δ²H and δ¹⁸O. The dominant ions in precipitation indicate that Ca²⁺, HCO₃⁻, SO₄²⁻, NH₄⁺ and NO₃⁻ are the main ions of precipitation in Hangzhou and Huzhou, and the dilution of precipitation leads to lower concentrations of ions in spring and summer, similar to the values found in most Chinese cities. The increase in motor vehicle use resulted in a lower [SO₄²⁻]/[NO₃⁻] ratio (1.64) of precipitation, indicating mixed acid rain in Hangzhou and Huzhou (HZS). Based on a combination of the correlation analysis, enrichment factors and source contributions, we determined that SO₄²⁻ and NO₃⁻ were introduced mainly from anthropogenic activities such as coal combustion and vehicle exhaust, accounting for 89% and 99%, respectively. The strong correlation between Cl⁻ and Na⁺, as well as Ca²⁺, Mg²⁺ and K⁺, indicates that these ions commonly have marine and crustal origins, respectively, and 40% of Mg²⁺ comes from a marine source.

Biosynthesized nanocomposites are attracting growing interests because they are environmentally friendly. Ag₂S nanoparticles (Ag₂S NPs) are deposited in situ on the surfaces of TiO₂ nanotubes (TNTs) via Shewanella oneidensis MR-1 to form Ag₂S/TNT nanocomposites. The prepared Ag₂S/TNTs nanocomposites are characterized using high-resolution transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and energy-dispersive X-ray spectroscopy. The results show that Ag₂S NPs smaller than 8 nm are successfully synthesized and fabricated on the TNT surfaces with relatively uniform distribution. The catalytic performance of the Ag₂S/TNT nanocomposites is evaluated for catalytic reduction in the presence of NaBH₄ and the photocatalytic degradation of 4-nitrophenol (4-NP) under visible light. The Ag₂S/TNT nanocomposites show excellent catalytic activity and good stability in the 4-NP reduction process. The 4-NP degradation ratio reaches 98.3% in 50 min, and 87% conversion was achieved after eight cycles. The Ag₂S/TNT nanocomposites also exhibit excellent photocatalytic activity for 4-NP at a rate of 0.69 h⁻¹, and the complete degradation of 4-NP was observed within 5 h. Therefore, this study offers an environmentally friendly approach to synthesize nanocomposites for practical applications.

Fine particulate matter (PM₂.₅) is a mixture of multiple components, which is associated with several chronic diseases, including respiratory and cardiovascular diseases. We evaluated the association between daily PM₂.₅ and PM₂.₅–₁₀ exposure and hospital visits for respiratory diseases. Hospital visits for respiratory diseases were collected from Yinzhou Health Information System database. We used generalized additive models to examine the excess relative risk (ERR) and 95% confidence interval for hospital visits for respiratory diseases associated with each 10-μg/m³ increase in PM₂.₅ and PM₂.₅–₁₀ concentration. Non-linear exposure-response relationship between PM exposure and hospital visits for respiratory diseases was evaluated by a smooth spline. The ERRs for hospital visits for respiratory diseases associated with a 10-μg/m³ increase in the 6-day cumulative average concentration of PM₂.₅ and PM₂.₅–₁₀ were 5.40 (95% CI 2.32, 8.57) and 6.37% (95% CI 1.84, 11.10), respectively. The findings remained stable when we adjusted other gaseous air pollution. PM₂.₅ and PM₂.₅–₁₀ were associated with the increased visits for the acute upper respiratory infection, pneumonia, asthma, and COPD. In this time-series study, we found a positive association between daily particulate matter exposure and hospital visits for respiratory diseases.

Copper and zinc composite oxides (Cu₂O/ZnO) were synthesized by an impregnation-reduction-air oxidation method. A series of Cu₂O/ZnO/rGO ternary composites were prepared by coupling with graphene oxide (GO) with different mass fractions in a solvothermal reaction system. The microscopic morphology, crystal structure, and optical characteristics of the photocatalysts were characterized. The degradation of p-Nitrophenol (PNP) and polyacrylamide (PAM) by photocatalytic materials under simulated solar irradiation were studied, and the degradation kinetics were also investigated. The results showed that cubic Cu₂O was modified by ZnO nanorods and distributed on rGO nanosheets. The ternary Cu₂O/ZnO/rGO nanocomposites have stronger simulated solar absorption ability and higher photodegradation efficiency than pure ZnO and binary Cu₂O/ZnO nanocomposites. When the amount of Cu₂O/ZnO/rGO-10 was 0.3 g L⁻¹, the degradation rate of 10 mg L⁻¹ PNP reached 98% at 90 min and 99.6% of 100 mg L⁻¹ PAM at 30 min. The photocatalytic degradation processes of PNP and PAM all followed the pseudo-first-order kinetic model. Free radical trapping experiments showed that superoxide radicals were the main active substances to improve photocatalytic efficiency. In addition, after four recycles, the catalytic efficiency of Cu₂O/ZnO/rGO-10 was still over 90%. It showed that Cu₂O/ZnO/rGO-10 was a promising catalyst for wastewater treatment because of its good photostability and reusability.

Regarding the rapid progress in the production and consumption of nanobased products, this research considered the behavior of Melissa officinalis toward zinc oxide nanoparticles (nZnO), nanoelemental selenium (nSe), and bulk counterparts. Seedlings were irrigated with nutrient solution containing different doses of nZnO (0, 100, and 300 mg l⁻¹) and/or nSe (0, 10, and 50 mg l⁻¹). The supplements made changes in growth and morphological indexes in both shoot and roots. The mixed treatments of nSe10 and nZnO led to a drastic increase in biomass, activation of lateral buds, and stimulations in the development of lateral roots. However, the nSe50 reduced plants’ growth (45.5%) and caused severe toxicity which was basically lower than the bulk. Furthermore, the nSe and nZnO improved K, Fe, and Zn concentrations in leaves and roots, except for seedlings exposed to nSe50 or BSe50. Moreover, the nSe and nZnO supplementations in a dose-dependent manner caused changes in leaf non-protein thiols (mean = 77%), leaf ascorbate content (mean = 65%), and soluble phenols in roots (mean = 28%) and leaves (mean = 61%). In addition, exposure to nZnO and/or nSe drastically induced the expression of rosmarinic acid synthase (RAS) and Hydroxy phenyl pyruvate reductase (HPPR) genes. Besides, the nSe, nZnO, or bulk counterparts influenced the activities of nitrate reductase in leaves and peroxidase in roots, depending on dose factor and compound form. The comparative physiological and molecular evidence on phytotoxicity and potential advantages of nSe, nZnO, and their bulk counterparts were served as a theoretical basis to be exploited in food, agricultural, and pharmaceutical industries.

Recently, strict standards for ship domestic sewage discharge have been implemented by the International Maritime Organization (IMO). The high salinity of ship sewage was considered a key factor influencing the removal efficiency of ship sewage treatment systems. In the present study, the salinity effect on the removal of chemical oxygen demand (COD) and ammonia nitrogen (NH₄⁺-N) from ship domestic sewage was investigated by using a novel air-lift multilevel circulation membrane reactor (AMCMBR). Enzyme activity analysis and wavelet neural network (WNN) models were built to determine the mechanisms of the process. The experimental results indicate that high salinity levels (> 21 g/L) had a negative impact on COD and NH₄⁺-N removal efficiencies, and low saline concentrations (≤ 21 g/L) caused a negligible effect. The COD and NH₄-N removal efficiencies were 84% and 97%, respectively, at a salinity of 21 g/L, which were higher than those at low salinities (i.e., 7 g/L and 14 g/L). Invertase and nitrate reductase had a close relationship with removal performance, and they can be considered important indicators reflecting the operation effort under saline environments. With high predictive accuracies, the constructed WNN models simulated the complex COD and NH₄⁺-N removal processes well under different saline concentrations, ensuring the long-term stable operation of the AMCMBR under different salinities.