The presence of arsenic and fluoride in groundwater and their impacts on human health have been reported in many countries worldwide, but little information is available on As or F⁻ contamination in Xi’an city. This study highlights the distribution and sources of As and F⁻ anomalies in different aquifers of Xi’an city, based on the assessment of natural background levels (NBLs) and threshold values (TVs). Groundwater samples collected from phreatic and confined aquifers were analyzed to evaluate NBLs and TVs, using median + 2MAD, Tukey inner fence (TIF), and percentile-based methods. Results showed that NBLs and TVs of As and F⁻ in the phreatic aquifer were lower than those in the confined aquifer, indicating importance of the geological effects on the enrichment of arsenic and fluoride in the confined aquifer. Combined with hydrogeochemical methods, the distributions of As and F⁻ anomalies show that high concentrations of As in both aquifers and F⁻ in the confined aquifer can be attributed to the upward flow of geothermal water through faults and ground fissures, while high concentrations of F⁻ in the phreatic aquifer may be greatly influenced by contaminated rivers. Although geological structures such as faults and ground fissures contribute to the high concentrations of potentially toxic elements, anthropogenic activities cannot be ignored because over exploitation of groundwater accelerates the development of ground fissures and results in the upward flow and mixing of geothermal water with groundwater in the upper aquifers.

Ionizing radiation is a double-edged sword because of its benefits and risks to human health. Therefore, protecting human organs from harmful effects of radiation is an important concern of researchers. Kefir, as a good source of probiotics, received growing interest in protective medicine owing to its antioxidant, anti-inflammatory, and immunomodulatory properties. Thus, this study was planned to investigate the protective role of kefir against γ-radiation-induced hepatotoxicity. Thirty-two male rats were distributed in four groups: (I) control, (II) received Kefir orally (5 ml/kg body weight) for 28 days, (III) exposed to whole body γ-irradiation (6.5 Gy) to induce hepatotoxicity, and (IV) was pretreated with kefir for 21 days then exposed to γ-irradiation followed by 7 days of kefir treatment. At the end of the experiment, complete blood picture (CBC), liver function, and lipid profile were estimated. Furthermore, levels of lipid peroxidation, nitric oxide content, and endogenous antioxidants, in addition to concentrations of copper, iron, and calcium were measured in liver tissue. Furthermore, monocyte chemoattractant protein-1 (MCP-1) and relative gene expression of nuclear factor kappa (NF-κB) were assessed. The results revealed that oral administration of kefir significantly reduced the radiation-induced hepatic histological alterations, hepatic function impairment, and dyslipidemia. Moreover, kefir notably ameliorated the state of oxidative stress and appeared to inhibit the induced inflammation. This study provides a possible counteracting role of kefir against hepatotoxicity induced γ-radiation. This can focus the benefit of kefir application as a prophylactic treatment to limit hepatic inflammation during radiotherapy.

Compressed natural gas is an alternative green fuel for automobile industry. Recently, the Indian government is targeting to replace all the conventional fuel vehicles by compressed natural gas (CNG) automobiles due to its several merits. Still, the presence of a significant amount of CO, CH₄, and NOₓ gases in the CNG vehicle exhaust are quiet a matter of concern. Thus, to control the emissions from CNG engines, the major advances are under development of and oxidation is one of them in catalytic converter. In literature, the catalysts such as noble and non-noble metals have been reported for separate oxidation of CO and CH₄.. Experimentally, it was found that non-noble metal catalysts are preferred due to its low cost, good thermal stability, and molding tractability. In literature, several articles have been published for CO and CH₄ oxidation but no review paper is still available. Thus, the present review provides a comprehensive overview of separate as well as simultaneous CO and CH₄ oxidation reactions for CNG vehicular emission control.

Heavy metals (HMs) being the notorious and toxic are being introduced into the environment credited to natural and anthropogenic activities. The use of ornamental plants is being ignored as potential candidates for HMs phytoremediation. In this study, pot experiments were conducted on Catharanthus roseus (L.) G.Don to evaluate selected heavy metals tolerance and accumulation potential with reference to the bacterial endophyte (Bacillus cereus) and organic amendments (moss and compost at 5% v/v). Results indicated improvement in uptake of Cd (230 mg kg⁻¹), Cu (229 mg kg⁻¹), and Cr (458 mg kg⁻¹) by C. roseus with B. cereus. The concentration of Ni and Pb was found highest in controls (without strain) that were 420 and 904 mg kg⁻¹, respectively. Conversely, the addition of organic amendments enhanced biomass production, as compared to controls, 441, 471, and 763% by peat moss (T3), compost (T4), and peat moss + compost + inoculum treatments (T6), respectively, while reduction of plant HMs content was observed. Microbial-aided phytoremediation/phytoextraction could be a potential method for removal of Cd, Cr, and Cu, while organic amendments can significantly improve plant growth in the presence of heavy metals.

The nitrogen removal efficiency in constructed wetlands (CWs) was largely affected by the dissolved oxygen (DO). In this study, micro-aeration with different numbers of hollow fiber membrane modules (HFMEs) was adopted to increase the oxygen availability and improve the nitrogen removal efficiency in CWs under different air temperatures and different hydraulic retention time (HRT). Compared to the plant oxygen release (ROL) of wetland plants and traditional mechanical aeration, HFME increased the oxygen availability and enhanced the nitrogen removal efficiency in CWs. The COD and NH₄⁺–N removal efficiencies increased with the increase of the HMFE. TN removal efficiency was increased by 8~16% after the application of HFME in CWs in the high-temperature stage. However, less HFME in CW-M1 realized the highest TN removal efficiency in low- and medium-temperature stages. At low temperature after 4-day HRT, the DO concentration respectively reached 6.25 mg L⁻¹ and 3.25 mg L⁻¹ in the upper zone and the bottom of CW-M1. The TN removal efficiencies in the upper zone of CW-M1 (60.69%) and the bottom of CW-M1 (64.98%) were all significantly higher than those in the upper zone of CK (35.98%) and the bottom of CK (39.9%). In addition, the microbial biomass and community analyses revealed that CW-M1 showed the most nitrifying bacteria and the best metabolic activity of bacteria. HEMF in CW-M1 also increased the nitrifying capacity from 0.12 to 0.46 mg kg⁻¹ h⁻¹. The application of HFME in CWs accelerated the nitrification process by enhancing nitrifying bacteria and less HFME realized the highest TN removal efficiency through nitrification-denitrification processes. Graphical abstract The application of hollow fiber membrane modules in CWs enhanced the pollutants (TN and COD) removal efficiency in the process of biological nitrification-denitrification and increased the number of nitrifying bacteria.

The health and environmental consciousness of waste tires has increased tremendously over the years. This has motivated efforts to develop secondary applications that will utilize tire when they reach the end of their life cycle and limit their disposal in landfills. Among the applications of waste tires which are discussed in this review, the use of rubber crumbs in artificial turf fields has gained worldwide attention and is increasing annually. However, there are serious concerns regarding chemicals that are used in the manufacturing process of tires, which ultimately end up in rubber crumbs. Chemicals such as polycyclic aromatic hydrocarbons (PAH) and heavy metals which are found in rubber crumbs have been identified as harmful to human health and the environment. This review paper is intended to highlight some of the methods which have been used to manage waste tire; it also looks at chemicals/materials used in tire compounding which are identified as possible carcinogenic.

This study aimed to determine the arsenic (As), copper (Cu), cadmium (Cd), and lead (Pb) concentrations in the soil at e-waste separating houses in Buriram province. Soil samples were collected from five e-waste separating and five non-separating houses in each of two neighboring communities and from six reference houses located approximately 4 km away from the e-waste community. At each selected house, the surface (0–15-cm depth) and the subsurface (15–30-cm depths) soils were taken to be digested by a microwave digester and then analyzed for the heavy metal contents by atomic absorption spectrophotometry. The As, Pb, and Cd levels in the e-waste separating sites ranged from < 0.012 to 1.380, 0.110 to 15.283, and < 0.014 to 0.284 mg/kg, respectively, which were not in excess of the Thai standard level for residential soil (As = 3.9, Pb = 400, and Cd = 37 mg/kg), while Cu ranged from 1.180 to 380.413 mg/kg and exceeded the intervention value (190 mg/kg) of contaminated soil at three sites from a total of ten sampling sites. The physical e-waste dismantling activity enhanced the As, Cd, and Cu contamination levels in the surface soils. Ecological risk assessment revealed that the risk posed by the heavy metals in soils was higher at the e-waste separating houses than those at the non-separating sites and was mainly attributed to the levels of Cu > As > Cd > Pb for the surface soils and Cd > Cu > As > Pb for the subsurface soil. The association of the heavy metal soil levels with e-waste activity showed that if the e-waste activities were continuously operated, the As and Cu levels in the surface soil were more likely to exceed those levels in the reference houses. A good procedure for e-waste dismantling is necessary to be developed and implemented to prevent soil contamination and other related environmental problems.

Polymer fiber, a kind of versatile material, has been widely used in many fields. However, emerging applications still urge us to develop some new kinds of fibers. Advanced oxidation processes (AOPs) have created a promising prospect for organic wastewater decontamination; thus, it is of important significance to design a kind of special fiber that can be applied in AOPs. In this work, a viable route is proposed to fabricate manganese oxide-supporting melt-spun modified poly (styrene-co-butyl acrylate) fiber, and the prepared fiber has an excellent activity to catalyze H₂O₂ and O₃ to decolorize dye-containing water. The results show that the decolorization of a cationic blue solution can be completely accomplished within 10 min with the prepared fiber as a catalyst, and its decolorization efficiency can reach up to 96.2% within 40 min. The concentration of total organic carbon can decrease from 20.3 to 12.3 mg/L. The prepared fiber can be reused five times without any loss in decolorization efficiency. Compared with other manganese oxide-based catalysts reported in the literature, the prepared fiber also shows many advantages in decolorizing methylene blue such as easy separation, mild reaction condition, and high decolorization efficiency. Therefore, we are confident that the fiber introduced in this study will exhibit a great application potential in the field of dye wastewater treatment.

A series of hydrogel nanocomposites was fabricated by in situ polymerization of 2-(dimethylamino)ethyl methacrylate (DMAEMA) in presence of different amounts of (amine- and alkyl-modified) nanocrystalline cellulose (NCC). Modification and nanocomposites properties were proved by different analysis methods such as Fourier-transform infrared spectroscopy (FT-IR), dynamic light scattering (DLS), and field emission scanning electron microscopy (FE-SEM). The new hydrogel nanocomposites were applied for removing methyl orange (MO) used as anionic dye and presented in process water at different pH values. The effects of the fabrication process such as modification and content of NCC, contact time, and pH value on swelling ratio (SR), and equilibrium adsorption kinetics were studied. Results showed that the swelling ratio of PDMAEMA-based nanocomposites varied with the different types of nanoparticles showing the significant effect of the modification process. The MO adsorption into the hydrogel nanocomposites was affected by intermolecular and electrostatic interactions between functional groups of hydrogel and dye. The adsorption capacity decreased at high pH value, and it was significantly affected type of nanoparticles introduced into the hydrogel network. The addition of unmodified NCC did not affect adsorption kinetics significantly. Finally, adsorption kinetics was investigated by pseudo-first-order, pseudo-second-order and intraparticle diffusion models where pseudo-first-order model showed the best correlation with experimental results.