Thermal desorption (TD) technology is the preferred treatment technology for treating soil contaminated by organic compounds. Under laboratory conditions, eggshell and plant ash were studied as additives during thermal desorption to further improve the soil thermal desorption efficiency and the quality of soil after thermal desorption. The results showed that temperature was still an important factor affecting the soil quality and removal efficiency of PAHs (polycyclic aromatic hydrocarbons). The efficiency of the thermal desorption of soil was significantly improved (from 91.7 to 96.6%) by adding two additives, and the agglomeration of the soil was alleviated to some extent according to the decreased amount of large soil particle (100–400 μm). Moreover, the TOC (total organic carbon) and CEC (cation exchange capacity) of the soil were increased. This work suggested that the addition of similar alkaline additives to the soil during thermal desorption might have a positive impact on both thermal desorption behavior and soil quality.

Biochar is widely used as a soil amendment, either alone or in association with fertilizer. However, the effects of biochar particle size on the soil microbial community are largely unclear. Biochar was divided into two groups according to diameter sizes: < 1 mm and 2.5–5 mm (labeled as CB1 and CB5, respectively). A pot experiment was established in which maize (Zea maize L.) was treated with CB1, CB5, and/or external nitrogen (N, NH₄NO₃). At the end of the seedling period (45 days), analyses of soil microbial community structure and other soil and crop properties were conducted. The biochar (regardless of N addition) enhanced microbial biomass and activity. CB1 had a stronger capacity than CB5 to modify soil microbial community structure by promoting soil microbial groups (e.g., fungi, Gram-negative bacteria), which is likely due to CB1 undergoing a series of more intense processes (e.g., nutrient release, mineralization) than CB5. However, this difference was diminished or disappeared when N was added, mainly due to the masking effect of soil acidification that was induced by N fertilization. Collectively, fine biochar has a stronger effect on soil microbial community than coarse biochar. Particle size only affects soil microbial community structure when biochar is applied alone; it has no effect when biochar is applied in association with chemical N fertilizer, at least during the seedling period. The relationship between particle size and soil microbial community needs to be considered when using biochar for soil amendment.

Thriving industrialization for human lifestyle headway has seeded the roots of water intoxication with harmful and hazardous toxic metal ions and dyes, which may ingress into food chains and become homicidal or mutation causing for creatures. The degummed functionalized silk fibroin composites with different biomaterials and synthetic materials are able to show adsorption efficiencies equivalent to 52.5%, 90%, 81.1%, 93.75%, 84.2%, and 98.9% for chromium, copper, cadmium, lead, thorium, and uranium ions, respectively, and adsorption capacity of 88.5 mg/g, 74.63 mg/g, 76.34 mg/g, and 72 mg/L for acid yellow 11, naphthol orange, direct orange S, and methylene blue, respectively, which make them desirable solution for water toxicants removal. This review is intended to describe the ability of silk fibroins to adsorb and abolish toxic heavy metal ions and dyes from water reservoirs, thus, providing a way to step toward water sanitation and wholesome living. Graphical abstract

This paper investigates whether the effect of female parliamentarians on environmental performance differs by the level of income. To that end, a threshold estimation approach is applied to a panel of 91 countries over the period 2002–2012. The results suggest the existence of income threshold effects in female parliamentarians-environmental performance nexus. Specifically, when it is above the income threshold value, the extent of this positive correlation is much greater than below it. It means that theoretically although the female parliamentarians have a higher awareness of environmental protection and a positive effect on environmental performance than men, the economic development of countries will affect the implementation of this effect. Countries tend to prioritize economic development when income levels are low, only in high-income countries will the proportion of female parliaments significantly improve the country’s environmental performance. These results provide some important implications for policymakers when considering the relationship between female parliamentarians and environmental performance.

The improper disposal and informal processing of e-waste have raised serious concerns for the environment and human health worldwide. A variety of legislative frameworks have been implemented to regulate e-waste management and upcycling in order to prevent environmental pollution and adopt resource reuse. Current e-waste legislation in different countries mostly include restrictions on e-waste import/export, regulations for recycling specific categories of e-waste, and Extended Producer Responsibility (EPR). This article serves as a comprehensive commentary to weigh the advantages and drawbacks of the different e-waste legislation enforced around the world. Though each country’s e-waste legislation is enframed to address the country-specific problems, the legislation is mostly not holistic, leading to different management issues. A variety of e-waste management issues prevalent in most countries (with e-waste specific legislation) have been listed and categorized for better understanding of the status quo. Further, the article proposes a generic e-waste management model catering to requirements of countries around the world. The implementation of such a model for Europe, China, India, Japan, South Korea, Taiwan, and Australia has been illustrated to show that the model can suit both developed and developing countries with contrasting e-waste management issues. The challenges that would arise in implementing an effective legislation and mechanisms for overcoming these challenges have also been discussed. To conclude, the role of governing bodies in tackling the future e-waste problems has been highlighted. In total, the article promotes scaling up the feasibility and efficacy of the implementation of e-waste policies across the globe in the coming years.

Urban ecosystem has become a critical part of ecological security and draws much attention worldwide. It is both a result of natural ecological system development, and also an inevitable outcome of human ecological system development within a certain stage, with the objective of identifying the possible improvement space for unban ecological security evaluation from complex system perspective. Based on the brittle structure model and set pair theory, this paper firstly explored the main research methods of urban ecological security theory and its characteristics, then conducted a theory of complex system brittleness to analyze the urban ecological security brittle factors, brittle primitives, and brittle structure. Furthermore, it conducted a model of urban ecological system brittleness correlation entropy together with a set pair analysis method to discuss its brittleness. And finally, an ecological safety evaluation has been presented based on the empirical case in Chengdu City of China. The theoretical and empirical analysis shows that the brittle correlation entropy of natural subsystem in urban ecological security is the biggest one. The risks from natural subsystem collapse can easily trigger the brittleness of the entire urban system. The corresponding maximum brittle fluctuation entropy is from economic subsystem; it has a largest impact on the entropy change of urban ecosystem. The way of reducing the uncertainty of urban ecological risks is to lower difference degree coefficient in the system. Relevant decision makers should consider to reduce the increasing degree of entropy and eliminate the fluctuation of the brittle factors. Thus, the threats or risks of urban ecological system can be within the acceptable range and under control. An integrated system management combing with brittleness characters of natural, economics, and social subsystem is necessary. It is helpful for the ecological security construction.

Noise is considered as an underrated and underemphasized pollutant in contrast to other pollutants of the environment. Due to the non-acute response of health effects, people are not vigilant towards consequences regarding noise pollution. The expansion of the transportation industry is contributing towards the increment in the public and private vehicular volume which causes an increment in noise pollution. For evaluation of respective scenario, the research study has been conducted on one of the minor roads of Nagpur, India; for 2 years, viz., 2012 and 2019. The study concludes an increment of 5–6 dB(A) in noise level, 4–6 times in honking, and 1.7 times in traffic volume. The study confirms increment in sound pressure by 65.9% and 81.9% for the year 2012 and 2019 during morning and evening sessions, respectively. Noise prediction model has also been developed for the abovementioned years, using multiple regression analysis, considering traffic volume, honking, and speed against noise equivalent level. Honking has been further characterized into honk by light and medium category vehicles as acoustical properties of horns vary with respect to category of vehicle and introduced into the noise prediction model. Noise prediction model for 2019 has predicted the noise level in a range of − 1.7 to + 1.4 dB (Leq) with 84% of observations in the range of − 1 to + 1 dB (Leq), when compared with observed Leq on the field. For proper management of noise pollution, a noise prediction model is essentially needed so that the noise level can be anticipated, and accordingly, measures can be outlined and executed. This increased noise level has serious impacts on human hearing capacity and overall health. Accordingly, noise mitigation preventive measures are recommended to control traffic noise in the urban environment.

Cyanobacterial blooms caused by Microcystis have become a menace to public health and water quality in the global freshwater ecosystem. Alkaline phosphatases (APases) produced by microorganisms play an important role in the mineralization of dissolved organic phosphorus (DOP) into orthophosphate (Pi) to promote cyanobacterial blooms. However, the response of extracellular and intracellular alkaline phosphatase activity (APA) of Microcystis to different DOP sources is poorly understood. In this study, we compared the growth of M. aeruginosa on two DOP substrates (β-glycerol-phosphate (β-GP) and lecithin (LEC)) and monitored the changes of P fractions and the extra- and intracellular APA under different P sources and concentrations. M. aeruginosa can utilize both β-GP and LEC to sustain its growth, and the bioavailability of LEC was greater than β-GP. For the β-GP treatment, there was no significant difference in the algal growth at different concentrations (P > 0.05), while the algal growth in the LEC treatment groups was significantly affected by concentrations (P < 0.05). The results showed that intracellular APA of M. aeruginosa could be detected in all DOP treatment groups and generally higher than extracellular APA. In addition, the intracellular APA per cell increased first and then decreased in all DOP treatment groups. Compared with the β-GP treatment, M. aeruginosa in the LEC groups could secret more extracellular APA.

Microbial activities and community structures play crucial roles in the soil environment and can be served as effective indicators to assess the ecological influence of heavy metal pollution in soil. This article selected soil samples from five land use types (mining area, mineral processing area, heap mining area, tailing area, and vegetable area) in the Shizishan mining area in Tongling, Anhui Province, China. The physicochemical properties, pollution characteristics, enzyme activities (catalase, urease, alkaline phosphatase, neutral phosphatase, cellulase, and sucrase), microbial biomass carbon (MBC), basal respiration (SBR), and metabolic entropy (qCO₂) in soil were determined and compared, and the relationship between environmental factors and the microbial activities and community diversity was analyzed. The results showed that, according to the Nemerow’s Pollution Index (PN), the values were the heap mining area (24.47) > mineral processing area (12.55) > mining area (9.81) > tailings area (6.02) > vegetable area (4.51). With the increase of heavy metal contamination in the sampling area, the six enzyme activities, MBC and SBR decreased, but the qCO₂ increased. Principal coordinate analysis (PCoA) and canonical correlation analysis (CCA) showed that the land use types, soil moisture content (MC), heavy metal content, pH, MBC, SBR, and qCO₂ were significantly affected by the microbial community. The most dominant phyla were Proteobacteria (34.73%), Bacteroidetes (9.25%), Acidobacteria (8.99%), and Chloroflexi (8.68%) at the phylum (0.01) level by a total of 18 phyla. It was also found that Firmicutes and Phormidium were more tolerant to heavy metals. These results contributed to an insight into key environmental variables shaping the microbial activities, community structure, and diversity under various land use types in mining area.