In anthropogenic soils, there have been relatively limited studies focusing on Cr and Ni contaminants because they exhibit less toxic effects to overall ecosystem and human health than other metal contaminants. In recent years, however, soil contamination with Cr and Ni has become a serious concern in several parts of the world because of the continuously increasing concentrations of these metals due to accelerated industrialization and urbanization. To investigate the status of soil contamination with Cr and Ni by anthropogenic activities, relevant global data sets in different land-use types reported by several studies were reviewed. This review presents the significant work done on Cr and Ni concentrations in roadside, central business district (CBD), and industrial soils in 46 global cities and evaluated their correlation by global data in the past few years. The highest concentrations of Cr and Ni were observed in industrial soils. Furthermore, a significant relationship was found between Cr and Ni concentrations in the soils, which might be because both metals are released from the same sources or anthropogenic activity processes. We also discuss the state of knowledge about the chemistry and distribution of Cr and Ni in the soil environment to understand how their processes such as redox reaction, precipitation–dissolution, and sorption–desorption affect the remediation of Cr- and Ni-contaminated soils using in situ immobilization technology. Application of organic and inorganic immobilizing agents (e.g., lime, compost, and sulfur) for the clean-up of Cr- and Ni-contaminated soils has received increasing interest from several researchers worldwide. Several immobilizing agents have been suggested and experimentally tested with varying degrees of achievement in Cr- and Ni-contaminated soils. Overall, the use of sulfur-containing amendments and pH-increasing materials could be considered the best options for the remediation of co-contamination of Cr and Ni in soil.

In granitic regions, water salinity typically ranges from 30 to 40 mg L⁻¹ at the surface and from 300 to 500 mg L⁻¹ for groundwater. Technogenic activity in Oaxaca has altered the concentration and chemical composition, which explains the occurrence of salinization processes and contamination of natural waters. To determine the physical–chemical composition of the Atoyac-Verde river, fifty-two water samples were collected from tributaries and semi-deep wells in the basin. The pH, electrical conductivity (EC), major cations and anions, total dissolved solids (TDS), residual sodium carbonate (RSC), and sodium adsorption ratio (SAR) were identified. Likewise, osmotic potential (Ψπ) was evaluated, and the effective salinity (ES) and potential salinity (PS) indexes. Results indicate that the water of the basin is bicarbonate-magnesium-calcium. Of the 52 samples analyzed, only 2 identified in the high relief points presented high levels of alkalinity and salinity with a pH of 8.1, EC of 2320 µS cm⁻¹, Ψπ of − 0.08 MPa, SAR of 3.74 (mmolc L⁻¹) ¹/², RSC of 0.53, ES of 9.88, and PS of 7.79 mmolc L⁻¹, indicating restriction for its use in agricultural and domestic activities. In the meso relief, the water did not present restrictive levels for anthropic use, while in the low relief, only two points presented high salinity levels and restriction of anthropic use. In conclusion, the greatest chemical alteration of the water was detected in areas close to the city of Oaxaca and to a lesser extent in areas adjacent to riverside populations of more than 2500 inhabitants.

Tin oxide (SnO₂) with versatile properties is of substantial standing for practical application, and improved features of the material are demonstrated in the current issue through the integration of nanotechnology with bio-resources leading to what is termed as biosynthesis of SnO₂ nanoparticles (NPs). This review reveals the recent advances in biosynthesis of SnO₂ NPs by chemical precipitation method focused on distinct methodologies, characterization, and reaction mechanism along with a photocatalytic application for dye degradation. According to available literature reviews, numerous bio-based precursors selectively extracted from biological substrates have effectively been applied as capping or reducing agents to achieve the metal oxide NPs. The major precursor obtained from the aqueous extract of root barks of Catunaregam spinosa is found to be 7-hydroxy-6-methoxy-2H-chromen-2-one that has been proposed as a model compound for the reduction of metal ions into nanoparticles due to having highly active functional groups, being abundant in plants (67.475 wt%), easy to extract, and eco benign. In addition, the photocatalytic activity of SnO₂ NPs for the degradation of organic dyes, pharmaceuticals, and agricultural contaminants has been discussed in the context of a promising bio-reduction mechanism of the synthesis. The final properties are supposed to depend exclusively upon a number of factors, e.g., particle size (< 50 nm), bandgap (< 3.6 eV), crystal defects, and catalysts dosage. With this contribution, it has been perceived not only to provide an overview of recent advances in the biosynthesis of SnO₂ NPs but also to indicate the main issues in need aiming to show vision towards innovative outcomes.

Microplastics are man-made pollutants which have been detected in surface water and groundwater. Research on microplastic concentration in aquatic environment is attracting scientists from developing countries, but in Nepal no information regarding microplastic in freshwater system is available. Therefore, this study investigates the presence and abundance of microplastic in lake surface water of Phewa Lake, the second largest lake in Nepal. The average concentration of microplastic for surface water was 2.96 ± 1.83 particles/L in winter (dry) season and 1.51 ± 0.62 particles/L in rainy (wet) season. Significant difference with t = 4.687 (p < 0.01) in microplastic concentration was observed in two different seasons. Fibers (93.04% for winter and 96.69% for rainy season) were the commonly found microplastic type in lake water and transparent as the dominant color for the two seasons. Almost all the detected microplastic were found to be < 1 mm in size. Due to the small size of microplastic and unavailability of micro-Fourier transform infrared spectroscopy (μ-FTIR) and Raman spectroscopy in Nepal, polymer identification was not done. The findings from this study can provide a valuable baseline data on microplastics for the first time in Nepal’s freshwater lake environment.

Manufacturing, as one of the most important sectors in a civilized society, has a strong impact on our city’s sustainability issues, and it is therefore justified in taking a more sustainable approach in the future. As a consequence, research works and the research trend of sustainable manufacturing (SM) play a critical role in supporting the sustainable development of industries. With the knowledge of the research themes on SM from the past to the present, preferred options for planning the future of manufacturing and executing SM could be offered to industries. Motivated by this, this study presents a thematic and bibliometric analysis on research papers of SM, with the goal of providing an overall overview of SM research trends, as well as identifying the critical time of having major breakthroughs and evolution of the corresponding research works by comparing the research themes across the longitudinal timeline. A thematic analysis was used to determine the keywords and main themes of the research on SM in various time frames, as well as the perspectives on how the research works in relation to current technology and dynamic changes. Finally, the three stages of SM research were determined based on the overall results. Furthermore, this article demonstrates the research directions and advancements of SM in 2020, presenting the most recent research trends in SM to both industry and academia.

This study revealed a dual pathway for the degradation of tris(1-chloro-2-propanyl) phosphate (TCPP) by zero-valent iron (ZVI) and persulfate as co-milling agents in a mechanochemical (MC) process. Persulfate was activated with ZVI to degrade TCPP in a planetary ball mill. After milling for 2 h, 96.5% of the TCPP was degraded with the release of 63.16, 50.39, and 42.01% of the Cl⁻, SO₄²⁻, and PO₄³⁻, respectively. In the first degradation pathway, persulfate was activated with ZVI to produce hydroxyl (·OH) radicals, and ZVI is oxidized to Fe(II) and Fe(III). A substitution reaction occurred as a result of the attack of ·OH on the P–O–C bonds, leading to the successive breakage of the three P–O–C bonds in TCPP to produce PO₄³⁻. In the second pathway, a C–Cl bond in part of the TCPP molecule was oxidized by SO₄·⁻ to carbonyl and carboxyl groups. The P–O–C bonds continued to react with ·OH to produce PO₄³⁻. Finally, the intermediate organochloride products were further reductively dechlorinated by ZVI. However, the synergistic effect of the oxidation (·OH and SO₄·⁻) and the reduction reaction (ZVI) did not completely degrade TCPP to CO₂, resulting in a low mineralization rate (35.87%). Moreover, the intermediate products still showed the toxicities in LD₅₀ and developmental toxicant. In addition, the method was applied for the degradation of TCPP in soil, and high degradations (> 83.83%) were achieved in different types of soils.

The identification and characterisation of diffuse pollutant sources in reservoirs remain a challenge due to the complexity of catchments with their variety of land use types. A sediment fingerprinting approach was used in this investigation for determining the sources of contaminants in sediments. By using this approach, we demonstrated how the effects of land use on pollution load of the subtropical Itupararanga Reservoir in Brazil can be de-convoluted. Sediments were collected at seven sampling sites (S1–S7) over the length of the reservoir. This was matched by eight sampling sites (P1–P8) of soils from different land use types (agriculture, urban and forest). Investigated parameters included grain size, total nitrogen (TN), total phosphorus (TP), total carbon (TC), organic matter by loss on ignition (OM), total sulphur (TS), and major ions and metals (Ca²⁺, Mg²⁺, Na⁺, K⁺, NH₄⁺, SO₄²⁻, Cl⁻, NO₃⁻, As, Al, Ba, Cr, Cu, Fe, Mn, Ni and Zn). Our fingerprinting approach helped to outline horizontal spatial heterogeneities (categorised as riverine, transitional and lacustrine areas) that were attributed mainly to sand (> 26.7%), Si (569 g kg⁻¹) and Cr (336 mg kg⁻¹) at S1 (riverine area). Moreover, fine particles of silt and clay leached from agricultural activities were enriched with OM, TP, TN, TC, As and Cr. These types of sediments were deposited into transitional and lacustrine areas. Furthermore, urban soils were a source of sand and phosphorus to sediments. The fingerprinting method reduced the number of relevant parameters for source identification and helped to identify non-point sources of sediments.

Hydrogen peroxide (H₂O₂) is a remarkably strong oxidant, and its vapour ([H₂O₂]g) has further advantages, such as a low cost and good light transmission. However, there has been very little research on its removal through gas-phase advanced oxidation (GPAO). In the present study, the photochemical oxidation of a gas that contains a series of benzene derivatives using ultraviolet (UV) irradiation and [H₂O₂]g was investigated in a transparent bag made of fluorinated ethylene propylene (FEP). UV and [H₂O₂]g barely reduced the pollutant within 5 h when used alone, and the reactant was also stable. When the pollutant concentration was high (248 to 756 mg/m³) and the residence time was short (3 s) compared with related studies on the removal of benzene, toluene and xylene, the apparent removal rate by UV/[H₂O₂]g/(powder active carbon, PAC) was higher than when other methods (UV/[H₂O₂]g, UV/[H₂O₂]g/TiO₂ and UV/[H₂O₂]g/ZnO), were used. However, it was found that the mineralization by UV/[H₂O₂]g significantly decreased, which in turn decreased the conductivity after the reaction. Increasing the pollutant concentration and the pH of the H₂O₂ had a negative effect on the treatment, but the UV radiation had a positive effect at powers of up to 40 W. In addition, the characteristic absorbance of three benzene derivatives showed that the key structure of the pollutant molecules was damaged during GPAO.

Human population growth and subsequent land use intensification are closely linked to contemporary increases in sediment and associated contaminants fluxes to fluvial systems, lakes, reservoirs, and coastal zones worldwide. In most urban areas, reservoirs that are the main source of fresh water supply, if not effectively managed, suffer from water quality decline and loss of capacity associated with accelerated siltation. This study analyzes watershed soil losses and sediment accumulation rates in two reservoirs in the Occoquan river basin, a sub-watershed of the Chesapeake Bay in the suburbs of the greater Washington, DC area. Lake Manassas is located in the upper reaches of the basin, characterized by mixed land use and cover of mostly forest, residential areas, and agriculture, whereas Occoquan Reservoir is located in the more urbanized lower reach of the basin in the heavily populated suburban zone south of Washington, DC. Five sediment cores from each lake were used in ²¹⁰Pb-based sediment accumulation rates analysis, and GIS-based Revised Soil Loss Equation (RUSLE) model and a sediment delivery ratio (SDR) were used to evaluate basin soil losses and sediment fluxes to the fluvial systems. ²¹⁰Pb sediment accumulation rate estimates in Occoquan Reservoir range from 0.26 g cm⁻² year⁻¹ in the upper reaches to 0.37 g cm⁻² year⁻¹ in the lower reaches. Lake Manassas also had comparable accumulation values ranging from 0.22 to 0.40 g cm⁻² year⁻¹. RUSLE/SDR estimated watershed sediment fluxes were 0.26 Mg ha⁻¹ year⁻¹ (Mg–mega gram) in the upper watershed, which is significantly higher than 0.07 Mg ha⁻¹ year⁻¹ estimates for the lower reaches of the watershed. The variability in the reservoirs’ sediment accumulation rates and basin soil losses reflects the variability of land use and cover, basin slopes, and erosion mitigation efforts within the watershed. The lower reaches, though more urbanized, have well-developed storm drain systems limiting run-off related soil losses. The well-managed riparian zones surrounding both reservoirs also limit sediment fluxes, hence the relatively low sediment accumulation rates. Although surficial sediment sources seem to be well managed, some of these efforts might be associated with the uptick in intrinsic sediment sources, leading to localized high sediment accumulation in the mouth of tributaries draining the high-intensity urban areas of the basin.

Nowadays, the world is facing a shortage of fresh water. Utilizing adsorbent materials to adsorb air moisture is a suitable method for producing freshwater, especially combining the adsorption desalination system with solar energy devices such as solar collectors. The low temperature of solar collectors has caused some water to remain in the adsorbents in the desorption process and has reduced the possibility of using these systems. In this research, for the first time, an evacuated tube collector (ETC) is used as an adsorbent bed so that the temperature of the desorption process reaches higher values and as a result, more fresh water is expected to produced. In this study, two adsorption desalination systems (ADS) are experimentally investigated. In the first system, a laboratory experimental setup using silica gel and hydrogel adsorbents is used to investigate freshwater production using each of the two adsorbents. The effect of different parameters such as variable adsorption and desorption time, variable temperature and humidity of inlet air, and variable adsorbent mesh sizes on the desalination process is evaluated. Then, in the second system, an innovative configuration of the solar-driven adsorption desalination system with an ETC full of silica gel is studied. In the laboratory experimental setup, the maximum amount of water produced by silica gel is 0.36 L/kg and by hydrogel is 0.58 L/kg. In the solar-driven adsorption desalination system, the largest amount of accumulated water production, daily efficiency, and cost per liter (CPL) of produced water are 1.518 kg/m² day, 11.25%, and 0.0699 $/L, respectively. Therefore, this new configuration for an adsorption desalination system seems feasible.