Tunnel boring muds, coming from underground works, are considered as specific materials due to their intrinsic characteristics (granularity, clay content, water content, presence of heavy metals). In order to determine if they can be valorized in road construction or civil engineering, a complete characterization, including their environmental behavior, is necessary. Thus, the aim of this study is to characterize a tunnel boring mud sample from chemical, mineralogical, and environmental point of view. The studied material, a limestone mud, was characterized using different analytical techniques. Some pollutants and heavy metals were identified, such as sulfates and molybdenum (Mo), and specific analyses were performed to identify molybdenum speciation. As molybdenum was detected as traces in the studied material, it was necessary to increase its concentration. Thus, a nitric acid extraction was specifically developed at a laboratory scale with the aim to remove its high-calcium carbonate content. Then, synchrotron analyses were performed, allowing to obtain data on the oxidation state of molybdenum.

In several countries, mining generates a high volume of tailing deposits, significantly impacting on soils. One of the non-metallic elements found in high concentrations in mine tailings is sulphur (S), in the form of sulphide minerals, whose oxidation causes acid drainage and metal mobility. The absorption of S in plants cultivated in mine tailings has been scarcely investigated. The objective of this study was to evaluate the extent to which a commercial humic substances and a vegetable waste compost can enhance the phytoremediation capacity of Atriplex nummularia for S and metals (Cu, Mo) in mine tailings. The plants were cultivated for 120 days under greenhouse conditions in pots with mine tailings (MT), with the addition of vegetable waste compost (VC) and a commercial humic substance (HS) in a 5% dose (W/W). At the end of the assay, the concentration of S in the aerial parts of plants cultivated in mine tailings, without amendments, reached 19,538 ± 4554 mg kg⁻¹, indicating a potential thiophore plant. In MT in which HS were applied, S and Cu concentration decreased significantly in aerial parts, while VC significantly increased Mo. The addition of HS generated significantly greater dry weight, reaching 11.55 ± 1.92 g in the aerial parts versus 2.08 ± 0.52 g in MT, which increased significantly S and Cu content in plant root and therefore favourable to phytostabilization. Regarding organic amendments, their chemical characteristics, availability, cost and quality in relation to organic matter are very important aspects for phytoremediation of mine tailings.

Regional averages of radon, thoron, and associated decay product concentration are reported to be higher than their respective global averages in recent studies conducted in Indian Himalayan belt. The present study explores another region in Indian Himalayan belt by conducting measurements of radon, thoron, and decay product’s activity concentration in 92 dwellings of Bageshwar district. The year-long measurements were performed in all 3 seasons distinguishing dwellings as per their construction material. The average radon and thoron concentration for the study region was measured as 57 Bq/m³ and 66 Bq/m³, respectively. Analysis of the measured data in terms of seasonal effects and construction material led to well established inferences, i.e., higher concentration for mud houses and for winter season. In addition, the present study focuses on lesser probed statistical inferences. One of them is related to the appropriateness of frequency distribution function for the measured data and other dwells upon the correlation analysis of inter-related factors for high concentration cases. Three distribution functions (Lognormal, Weibull, and Gamma) were found to be following the trend of frequency distribution curve of the measured data. For mud houses in winter season, variations of radon/thoron concentration were attempted to correlate with mass/surface exhalation rate, emanation rate, and source term content. More than 80% of the dwellings of the study region were found to have gas and decay product’s concentration levels, higher than the respective global average values. However, these values were mostly within the reference levels for residential environments. Nevertheless, this region requires further studies to pinpoint the causes for elevated levels and suggest simple remedial modifications if required.

An iron(III)-polyvinyl chloride (PVC)-Schiff base adsorbent was prepared for removal of methyl orange (MO) as an anionic dye from the aqueous samples. PVC was reacted with ethylenediamine to prepare aminated PVC. Salicylaldehyde was then added to the aminated PVC to incorporate the Schiff base group into the polymer structure. This product was further reacted with iron (III) nitrate to form an iron complex as the modified PVC adsorbent (PVC-[Fe(EDA)(Sald)]). The prepared adsorbent was characterized by Fourier transform-infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), Brunauer-Emmett-Teller (BET) surface area analysis, and thermogravimetric analysis (TGA). The special parameters influencing the adsorption process such as the solution pH, contact time, initial dye concentration, and the solution temperature were investigated. Removal percentage (%R) and adsorption capacity (qₜ) greater than 50% and 140 mg g⁻¹, respectively, were obtained under the following conditions: pH, 7;contact time, 150 min; dye concentration, 100 mg.L⁻¹; and solution temperature, 25 °C. The adsorption isotherm and kinetic data were well fitted by the Freundlich isotherm model and the pseudo-second-order kinetic model, respectively. The thermodynamic data revealed that the adsorption process was endothermic and spontaneous. The changes in entropy (ΔS°) and enthalpy (ΔH°) were calculated to be 0.110 kJ mol⁻¹ K⁻¹ and 31.011 kJ mol⁻¹, respectively. In this work, we developed for the first time the synthesis of an iron(III)-polyvinyl chloride (PVC)-Schiff base adsorbent that can be successfully used for removal of methyl orange from the aqueous sample. Furthermore, these findings showed that modified PVC was more efficient than neat PVC on MO removal for adsorption process.

This study investigated the performance of aerobic windrow systems by using coffee by-products and green waste to reduce gaseous emissions. Thereafter, a comparison with the current treatment and gaseous emissions at a Coffee Mill in Costa Rica was made. Two different studies where performed in Germany (pile I and II) and one study in a Coffee Mill in Costa Rica (pile III). Temperature, water content, and pH were the key parameters controlled over 35 days in all the systems. Moreover, CH₄ emission rates were quantified by a FTIR and by a portable gas detector device where the emissions reached values 100 times higher when coffee by-products as a unique material for the composting process was used. Results show that highest emission rates during the composting process for pile I was 0.007 g(m²)⁻¹ h⁻¹, for pile II 0.006 g(m²)⁻¹ h⁻¹, and for pile III 3.1 g(m²)⁻¹ h⁻¹. It was found that CH₄ emissions could be avoided if the mixture and the formation of the windrow piles were performed following the key parameter for composting, and the usage of additional material is used. With this, the reduction of CH₄ emissions at the Mill in Costa Rica could be achieved in the future.

Hydroxyapatite-silica fibers were prepared by sol-gel process and electrospinning, and their capacity for adsorption of cadmium and lead ions in aqueous solution was studied. The samples were characterized by SEM, FTIR, TGA, DSC, BET, and XRD. The composite consists on a network of continuous rough fibers with mean diameter of 150 ± 40 nm after thermal treatment. The fibers present a mesoporous structure with pore size of 15.75 nm. Fourier transformed infrared spectroscopy and X-ray diffraction demonstrated the presence of crystalline hydroxyapatite and amorphous silica. Adsorption process is represented by Freundlich isotherm, while the adsorption kinetics follow the pseudo-second-order model. The capacity shown by the fibrous material for the removal of lead ions (466.98 mg/g) was five times higher than the capacity observed for the adsorption of cadmium (93.30 mg/g). Therefore, the hydroxyapatite-silica electrospun fibers represent a suitable material for the efficient removal of lead and cadmium ions from aqueous solution.

Neurodegenerative disorders are commonly erratic influenced by various factors including lifestyle, environmental, and genetic factors. In recent observations, it has been hypothesized that exposure to various environmental factors enhances the risk of Alzheimer’s disease (AD). The exact etiology of Alzheimer’s disease is still unclear; however, the contribution of environmental factors in the pathology of AD is widely acknowledged. Based on the available literature, the review aims to culminate in the prospective correlation between the various environmental factors and AD. The prolonged exposure to the various well-known environmental factors including heavy metals, air pollutants (particulate matter), pesticides, nanoparticles containing metals, industrial chemicals results in accelerating the progression of AD. Common mechanisms have been documented in the field of environmental contaminants for enhancing amyloid-β (Aβ) peptide along with tau phosphorylation, resulting in the initiation of senile plaques and neurofibrillary tangles, which results in the death of neurons. This review offers a compilation of available data to support the long-suspected correlation between environmental risk factors and AD pathology. Graphical abstract .

Functionalized ordered mesoporous carbon (MOMC-NP) was synthesized by chemical modification using HNO₃ and H₃PO₄ to enhance Pb(II) adsorption. The phosphate functional group represented by P-O-C bonding onto the surface of OMC was verified by FT-IR and XPS. Batch adsorption experiments revealed the improvement of adsorption capacity by 39 times over the virgin OMC. Moreover, the Pb(II) adsorption results provided excellent fits to Langmuir model and pseudo-second-order kinetic model. The adsorption mechanism of Pb(II) onto MOMC-NP revealed the formation of metal complexes with carboxyl, hydroxyl, and phosphate groups through ion exchange reactions and hydrogen bondings. The calculated activation energy was 22.09 kJ/mol, suggesting that Pb(II) adsorption was a chemisorption. At pH>pHₚzc, the main Pb(II) existing species of Pb(II) and Pb(OH)⁺ combine with the carboxyl, hydroxyl, and phosphate functional groups via electrostatic interactions and hydrogen bonding. All these findings demonstrated that MOMC-NP could be a useful and potential adsorbent for adsorptive removal of Pb(II). Graphical abstract

This study calculates the green investment level of each province in China and objectively estimates the provincial environmental regulation level from the perspective of the government to examine the effectiveness and impact of the government’s environmental protection policy on the environmental regulation level. The carbon emission trading pilot policy is determined through a quasi-natural experiment difference in difference model to examine the impact and assess the effectiveness of green environmental protection policies on the environmental regulation level empirically. Results show that (i) the green investment level of the carbon emission trading pilot provinces is significantly lower than that of other nonpilot provinces after 2013, and (ii) the introduction of environmental protection policies has reduced the government’s green investment level by approximately 8%. These findings confirm that environmental regulation policies play a significant role in promoting the environmental regulation level. Further mechanism analysis shows that environmental regulation policies influence this level through carbon dioxide emissions. This study provides a reference for environmental regulation policy making.

Microplastics have become a major environmental concern globally due to their potential impact on ecosystem function. They are known to be ubiquitously present, persistent and bio-accumulative, yet there is a lack of abundance quantifications in freshwater shorelines. Furthermore, there is little understanding of combined effects of seasonality and human population density on the extent of microplastic pollution. In this study, we assessed microplastics in sediment along a subtropical reservoir shoreline across three seasons and seven sites to understand microplastic pollution dynamics along a human population gradient. Multivariable analysis was used to assess relationships among substrate embeddedness, sediment organic matter, human population density and microplastic particle densities and characteristics. Microplastic densities were relatively high during the hot–dry season (mean range 120–6417 particles kg⁻¹ dwt) whilst the hot–wet season had the lowest densities (mean range 5–94 particles kg⁻¹ dwt). Microplastic abundances were positively correlated with population density, demonstrating the direct effects of human activity on microplastic contamination. These results highlight the need to further explore microplastic distribution patterns in freshwater ecosystems in the Southern Hemisphere. Furthermore, our findings suggest particular risk for fauna during low rainfall periods through microplastic concentration effects.