International Journal of Environmental Research最新文献

Industrial decarbonisation has become an increasingly important policy issue in recent years, as governments and nations aim to tackle the climate crisis. This study makes use of UK research council and Horizon 2020 data to map the research landscape for industrial decarbonisation. This includes an analysis of 435 projects funded by various UK research councils, and 239 projects funded under Horizon 2020 linked to industrial decarbonisation. This study finds in the UK case, University–Industry–Government links are critical elements of the decarbonisation research landscape. Universities playing key roles in the UK system are often members of the prestigious Russell Group. In the case of the European industrial decarbonisation landscape (as captured by projects funded under Horizon 2020), private firms play a crucial role. This study also maps a country-to-country collaboration network based on industrial decarbonisation research projects funded under Horizon 2020. This study examines the link between country position in the network and share of electricity consumption that comes from coal; no significant relationship is identified.

Once hailed as a ‘wonder material'’ for its low cost, durability, lightweight, flexibility, and water resistance, plastics have now become one of the potent threats to human civilization. Imperatively, light and microbes could play significant roles in plastic degradation. Plastic–semiconductor composites enhance photodegradation, whereas the presence of biodegradable compound in composites may facilitate their degradation by soil microbes. In this work, composite films of polyvinyl chloride (PVC) and zinc oxide semiconductor (ZnO) are synthesized in various combinations and subjected to sequential photo- and biodegradation. The photodegradation was exclusively solar, whereas polycaprolactone (PCL) was apprehensively added to the composite for enhancing the biodegradability. The process sequence was also altered to investigate the possible effects. Sequential photocatalytic degradation under sunlight and biodegradation by bacteria isolated from soil could decrease the original weight of a photo-bio degradable polymer composite film comprising of PVC, PCL and ZnO in less than a month. The isolated microbe was later identified as Bacillus altitudinis by 16S rRNA gene sequencing. Identification and isolation of enzymes involved in PVC degradation by the isolated strain may be included in future work. Maximum 26.8 w% degradation was observed within 25 days in case of PVC–ZnO composite. The role of PCL was found to be insignificant in biodegradation especially in presence of ZnO. The solar photodegradation was modelled based on a proposed mechanism that finally led to two parallel reaction pathways following first- and zero-order kinetics, respectively. Biodegradation, on the other hand, was noted to be fairly consistent with the Michaelis–Menten kinetics.

The biomineralization process is a relatively modern ground improvement technique wherein microbial activity is increased to improve soil stiffness. Bacteria and enzymes are used to carry out the ureolysis process which leads to the formation of calcium carbonate that binds the soil particles. Biopolymers are also used to improve the engineering properties of soil. This study aims to present a detailed insight into the efficacy of various methods with respect to the type of bio-agent, soil, optimal concentration, and solution injection scheme. The effect of the biomineralization techniques on soil engineering properties such as unconfined compressive strength, shear strength, and permeability is discussed. The cost-effectiveness is studied to help identify the total optimum production cost of different methods in accordance with the raw materials cost. The concept has been found to be especially useful in the mitigation of liquefaction hazards and the prevention of soil erosion. The existing literature primarily discusses the increase in the strength of soil post-process. The potential field applicability, related challenges, and problems are also presented in this review. The major challenge in adopting the technology at field is the cost of the treatment and the problem is obtaining uniform bio-mineralization across the depth of treatment. The cost-related issue can be handled using industrial by-products for the growth of bacteria, while engineering aspects of bio-mineralization have to be understood to make it field applicable.

The leaching of contaminants is a complex, pivotal process for understanding how biochar can immobilize them effectively. In this study, we investigated the impact of biochar, produced at different temperatures, on the behavior of arsenic (As) and lead (Pb) in leached sediments. Before leaching, we combined biochar with sediment, allowing it to naturally age for 365 days. The biochar derived from sugarcane straw was pyrolyzed at 350 °C (BC350), 550 °C (BC550), and 750 °C (BC750). Using UV–Vis spectroscopy, we assessed changes in dissolved organic carbon quality and examined geochemical alterations employing high-performance liquid chromatography–inductively coupled plasma mass spectrometry (HPLC–ICP-MS). The addition of biochar decreased Pb mobility while increasing As mobility. The extent of immobilization varied depending on the pyrolysis temperature: BC750 notably reduced Pb leaching by 54%, whereas BC350 enhanced As mobility by 2.5 times. Although no leaching of monomethylarsonic or dimethylarsinic acids occurred, both BC350 and BC750 amplified As³⁺ leaching by 2.5 times. In summary, biochar addition at different temperatures altered the environmental fate of As and Pb. Higher pyrolysis temperatures, as seen with BC750, were more effective in mitigating Pb mobility, reducing sediment leaching by 54%. Interestingly, exogenous dissolved organic carbon and phosphorus promoted As leaching.

Abstract

The search for potent plastic-degrading bacteria has been a focal point of research over the recent decades to develop sustainable methods for plastic waste management. Despite promising results at the laboratory scale, replicating the same at the field scale has been limited. Natural extremophilic conditions of the landfill host many plastic-degrading bacteria, and recently, culture-independent Next-Generation Sequencing metagenomics approaches are being adopted to screen them and exploit their utilities. However, one of the main challenges is the difficulty in designing the optimum artificial test conditions for understanding the growth and metabolic activities of the concerned microorganisms. In the current study using precision metagenomics, genes coding for PET and PHA degrading enzymes were screened from a landfill-mined soil-like fraction (LMSF) sample, with landfill soil under a freshly deposited waste dump acting as the control. Subsequently, thorough geoenvironmental characterization of the samples was performed to generate an understanding of the growth conditions of the microorganisms. Genes encoding for MHETase outpopulated the genes encoding for PETase in LMSF, while the reverse trend was observed in the control. The abundance and taxonomic distribution of the hosts containing genes of PETase and MHETase enzymes in the samples, when co-related with the FTIR spectra of the samples, indicated that the PET residues might have possibly degraded to MHET under natural conditions. Usually, commercial composts, which are already a market-ready product for the agriculture sector, are used for polymer composting, which is not sustainable in the long run. The structural and functional patterns of the microbes obtained in the metagenomics study and permissible levels of leachable heavy metals generate promise for the landfill-mined soil-like fractions to be potentially used for polymer degradation. Alongside this, the presence of a monotypic oceanic genus Plesiocystis in the landfill environment was confirmed, which is of utmost importance to the field of microbial ecology.

Graphical Abstract

The development of stable electrodes with significant capacitance is necessary for the commercial viability of supercapacitors, which have generated a lot of interest. Metal oxides are a promising material because they have multiple valence shells for charge transfer, a high theoretical specific capacitance, and variable redox properties. Because of this, we explore, for the first time to the best of our knowledge, the effects of Copper (Cu) doping on the super capacitive performance of tin oxide (SnO₂). The pure, 2%, 7%, and 15% Cu-doped SnO₂ are synthesised by facile coprecipitation. We demonstrate a maximum electrochemical performance for 2% Cu-doped sample with a specific capacitance of 27.099 F/g at a sweep rate of 10 mV s⁻¹, while further increase in doping levels had a negative impact on the capacitive performance of SnO₂. The specific capacitance vale was found to be decreased with an increase in Cu concentration, which could be explained by the increasing trend found in the charge transfer resistance upon doping as observed from electrochemical impedance spectroscopy, the resistance increased from 5.85 to 7.19 Ω. The perfect reversible behaviour of a pseudocapacitor is estimated from the highly symmetric nature of chronopotentiometry (GCD) curves and the pseudo behaviour is further confirmed from the cyclic voltammetry curve with an excellent potential window of 1.3 V.

An investigation was conducted in the vicinity of a sustainable pig farm to assess the presence of antibiotics through SPE-HPLC/MS/MS, microbial communities via Illumina high-throughput sequencing, and antibiotic resistance genes using SmartChip technology. The study revealed that tetracyclines were the predominant antibiotics detected in the soil and sediment surrounding the pig farm, with residual concentrations ranging from 33.3 to 1244.2 μg∙kg⁻¹. The most prevalent phyla identified at various sampling sites were Firmicutes, Chloroflexi, Proteobacteria, Actinobacteria, and Acidobacteria. A total of 188 antibiotic resistance genes (ARGs) and 9 mobile genetic elements were found in the sediment, with aminoglycoside (particularly aadA2-03), sulfonamide (specifically sul2), and tetracycline (particularly tetX) resistance genes being the most frequently observed. The presence of tetracycline residue was observed to influence the composition of the microbial community, whereas no significant association was found between antibiotics and ARGs. Examination of the correlation between ARGs and bacteria at the phylum level demonstrated that Cyanobacteria, Acidobacteria, Planctomycetota, and Gemmatimonadota were the predominant phyla associated with ARG presence near an intensive pig farm. Notably, Cyanobacteria may function as a continual reservoir and/or shelter for ARGs, thereby potentially contributing to the dissemination of ARGs in the sediment environment in close proximity to a pig farm. This study presents evidence of the ecological risks posed by antibiotics in a pig farm-cropland system, highlighting the connection between microbial community structure and ARGs. Therefore, the issue of antibiotic residues must be factored into the sustainability of animal husbandry practices.

This study aimed to evaluate the effect of nanoclay (NC), zeolite (Z), biochar (B), municipal waste compost (MWC), and farmyard manure (FYM) at two application levels of 1% and 3% (w/w) on the saturated hydraulic conductivity (K_S) and sodification process of a calcareous soil under leaching by waters with different electrical conductivity (EC) and sodium absorption ratio (SAR) values. Columns containing control and amended soils were washed in three separate experiments using 20 pore volumes of three solutions classified in C3S1, C4S3, and C4S4 classes. The incorporation of the amendments led to a significant decrease in soil sodification because of decreasing exchangeable sodium and increasing exchangeable calcium. The exchangeable sodium percentage (ESP) of soils after leaching by solutions C3S1, C4S3, and C4S4 varied in the ranges of 1.80–5.79%, 2.78–7.85%, and 3.66–15.6%, respectively. The highest and lowest ESP values were obtained for control and 3% FYM treatment, respectively. For each leaching solution, the K_S was significantly higher in the control compared to the amended soils (P ≤ 0.05). The lowest value of K_S was obtained for the 3% B treatment. Furthermore, K_S values increased with an increase in SAR of water. This was likely due to the simultaneous increase in EC and concentration of divalent cations (calcium and magnesium). The most effective amendments in controlling soil sodification were FYM, B, and MWC at the application level of 3%.

PM_2.5 is a main air pollutant in China. Considering the unevenly distributed PM_2.5 and population in China, an accurate assessment of PM_2.5 exposure is needed. In this study, the population-weighted exposure (PWE) is used to measure the overall PM_2.5 exposure based on 2766 counties across mainland China. The population exposure risk (PER) is used to better assess the partial PM_2.5 exposure risk level for residents at the county level. The PM_2.5 PWE and PER are calculated with the latest 2020 census data and the predicted concentrations estimated by spatial models considering both the geographic similarities and aggregation. The PWE differed from the concentrations across China, especially in four heavily polluted regions and three detected high-concentration clusters. In China, the average PM_2.5 PWE in 2019 was 39.46 μg/m³, 2.41 μg/m³ higher than the mean concentration (37.05 μg/m³). The exposure in three detected clusters was much higher than in the Sichuan Basin (SCB), the Pearl River Delta (PRD), and the Yangtze River Delta (YRD), suggesting the focus of environmental governance should not only be the traditional heavily polluted areas according to administrative divisions. Regions with high concentrations also differed from regions with high PM_2.5 exposure risk. The counties with higher PM_2.5 PER were located in east-central and eastern coastal China, different from the distribution of concentrations. This study clarified the necessity of considering spatial aggregation of PM_2.5 in LUR models and also emphasized the importance of calculating PM_2.5 PWE as exposures in further health effect assessments.

Implementing nutrient recycling in wastewater treatment plants is essential for sustainable agriculture. In this study, we investigated a biphasic treatment system for anaerobic liquid digestate, which involved natural and K-enriched zeolite for NH₄⁺ recovery (phase 1), followed by struvite crystallization under two conditions: NH₄⁺ excess and Mg²⁺ excess (phase 2). The adsorption of NH₄⁺ by natural zeolite enabled saving Mg and P reagents, used to achieve target Mg:NH₄:PO₄ ratios. The reagent use efficiency of struvite precipitation was highest with natural zeolite under NH₄⁺ excess conditions (96%), whereas the other treatments exhibited lower yields. In this condition, the digestate enriched in Ca²⁺ released by zeolite; however, no P interferences occurred (Ca²⁺/Mg²⁺ < 0.5). Fractions of Ca²⁺ precipitated as CaCO₃. Both the isomorphic NH₄- and K-struvite occurred, distinguished by calibrating XRPD data (total struvite) with N contents (indicative of NH₄⁺-struvite). The precipitates comprised NH₄- and K-struvite at 60% and 30% (calcite at 9%) in the treatment that involved natural zeolite, 65% and 35% with the K-exchanged zeolite, due to higher presence of K⁺. Concerning the chemical evolution of the treated digestate, fewer alterations occurred for inorganic ions in the treatment that involved natural zeolite (phase 1) with NH₄⁺ excess condition (phase 2), besides for unreacted SO₄^2– derived from the Mg reagent. The recovered zeolite was enriched in N at 0.5%. Struvite precipitates met the EU regulations regarding permissible levels of organic C, P content, and heavy metal impurities, thereby potentially enabling its use as a fertilizer.