The generation of acid mine drainage (AMD) may accelerate watershed erosion and promote the migration of heavy metals, then threaten local ecosystems such as aquatic life and even human health. Previous studies have focused primarily on influence of AMD in surface environment. In order to reveal the acidizing processes in karst high-sulfur coalfield in Southwest China, this study, by contrast, focused on the hydrogeochemical evolution process and acidification mechanism of mine water in Zhijin coalfield, western Guizhou Province. The oxidation of pyrite and other sulfides induced strong acidification of mine water according to the water chemical analysis. As a result, a series of geochemical processes such as dissolution of carbonates and silicates, hydrolysis of metal ions, and degassing of CO₂ complicated water chemical evolution. The dissolution of silicates controlled the chemical composition of mine water, but more carbonates might be dissolved during the acidification of mine water. The sources of sulfate are quite different in water samples collected from the two selected mine. According to sulfur isotope analysis, the dissolution of gypsum is the primary source of sulfate in samples from Hongfa mine, whereas sulfide oxidation contributed a large amount of sulfate to the mine water in Fenghuangshan mine. The dissolution of carbonates should be an important source of DIC in mine water and CO₂ originating from organic mineralization might also have a certain contribution. This study elucidated the groundwater chemical evolution processes in high-sulfur coal-bearing strata and provided a foundation for further study of carbonates erosion and carbon emission during acidification of mine water.

The focus of the present research work is to investigate the dynamic relationship between economic growth, road transport energy consumption, and environmental quality. To this end, we rely on time series data for the period 1971 to 2014 in the context of Pakistan. To use sulfur dioxide (SO₂) emission from transport sector as a new proxy for measuring environmental quality, the present work employs time series technique ARDL which allows energy consumption from the transport sector, urbanization, and road infrastructure to be knotted by symmetric relationships with SO₂ emissions and economic growth. From the statistical results, we confirm that road infrastructure boosts economic growth. Simultaneously, road infrastructure and urbanization hampers environmental quality and causes to accelerate emission of SO₂ in the atmosphere. Furthermore, economic growth has a diminishing negative impact on total SO₂ emission. Moreover, we did not find any proof of the expected role of transport energy consumption in SO₂ emission. The acquired results directed that care should be taken in the expansion of road infrastructure and green city policies and planning are required in the country.

Polychlorinated biphenyls (PCBs) are a class of persistent organic pollutants that are distributed worldwide. Although industrial PCB production has stopped, legacy contamination can be traced to several different commercial mixtures (e.g., Aroclors in the USA). Despite their persistence, PCBs are subject to naturally occurring biodegradation processes, although the microbes and enzymes involved are poorly understood. The biodegradation potential of PCB-contaminated sediments in a wastewater lagoon located in Virginia (USA) was studied. Total PCB concentrations in sediments ranged from 6.34 to 12,700 mg/kg. PCB congener profiles in sediment sample were similar to Aroclor 1248; however, PCB congener profiles at several locations showed evidence of dechlorination. The sediment microbial community structure varied among samples but was dominated by Proteobacteria and Firmicutes. The relative abundance of putative dechlorinating Chloroflexi (including Dehalococcoides sp.) was 0.01–0.19% among the sediment samples, with Dehalococcoides sp. representing 0.6–14.8% of this group. Other possible PCB dechlorinators present included the Clostridia and the Geobacteraceae. A PCR survey for potential PCB reductive dehalogenase genes (RDases) yielded 11 sequences related to RDase genes in PCB-respiring Dehalococcoides mccartyi strain CG5 and PCB-dechlorinating D. mccartyi strain CBDB1. This is the first study to retrieve potential PCB RDase genes from unenriched PCB-contaminated sediments.

Two-step physical activation was used to prepare activated carbon from textile waste jute. Raw material was first carbonized under nitrogen and then activated by CO₂. Based on yield and pore structure, the optimal carbonization temperature and time were 500 °C and 60 min, respectively. Carbonized sample was next activated. The development of porosity and surface chemistry was highly dependent on activation temperature and time. Activated carbon produced at 800 °C was predominantly microporous while that produced at 900 °C was more mesoporous and macroporous. The shift from microporosity to mesoporosity could be used to produce either microporous or mesoporous carbon just by changing the activation temperature. Activation also changed the surface chemistry and created a more carbonaceous structure. The jute-based activated carbon was mostly powdered in form, slightly acidic and effective in adsorbing both heavy metals and organics.

Surface waters are sometimes contaminated with neonicotinoids: a widespread, persistent, systemic class of insecticide with leaching potential. Previous ecotoxicological investigations of this chemical class in aquatic ecosystems have largely focused on the impacts of the neonicotinoid imidacloprid; few empirical, manipulative studies have investigated the effect on invertebrate abundances of two other neonicotinoids which are now more widely used: clothianidin and thiamethoxam. In this study, we employ a simple microcosm semi-field design, incorporating a one-off contamination event, to investigate the effect of these pesticides at field-realistic levels (ranging from 0 to 15 ppb) on invertebrate colonisation and survival in small ephemeral ponds. In line with previous research on neonicotinoid impacts on aquatic invertebrates, significant negative effects of both neonicotinoids were found. There were clear differences between the two chemicals, with thiamethoxam generally producing stronger negative effects than clothianidin. Populations of Chironomids (Diptera) and Ostracoda were negatively affected by both chemicals, while Culicidae appeared to be unaffected by clothianidin at the doses used. Our data demonstrate that field-realistic concentrations of neonicotinoids are likely to reduce populations of invertebrates found in ephemeral ponds, which may have knock on effects up the food chain. We highlight the importance of developing pesticide monitoring schemes for European surface waters.

Paddy soil experiences repeated anaerobic and aerobic changes during rice growth, the dramatic dynamics of soil water status accompanied by changes in redox condition and O₂ availability. However, the effect of rapid water status change on soil microbial biomass and community composition is not well explored. Here, we present a comprehensive study focusing on the short-term water status change in 13 Chinese paddy soils. In order to gain a reliable way to determine soil microbial biomass carbon (MBC) in flooded or water-saturated soils, we also evaluated two different procedures (nitrogen bubbled and 100 °C water bath) to remove chloroform in extracts during the fumigation process. Compared to non-flooded paddy soils, the flooded paddy soils tended to have a lower microbial biomass, and this was much clearer using adenosine 5′-triphosphate (ATP) and phospholipid fatty acid (PLFA) analysis compared to biomass measured by the fumigation method. Fungal biomass, which was indicated by both ergosterol and the PLFA 18:2ω6,9c, also decreased after short-term flooding. Changes in soil microbial community composition (determined by PLFA biomarkers) were observed after short-term flooding, but the extent varied between soils. This study indicates that the dynamics of short-term water status altered the soil microbial biomass (ATP, MBC, and total PLFA) and community composition. Finally, our results suggested that liquid fumigation combined with the nitrogen-bubbled method is the best choice for analyzing MBC concentrations in water-saturated soils.

In the present study, silver and gold nanoparticles (AgNPs and AuNPs) were green synthesised using the aqueous plant extract of Stemona tuberosa Lour. When plant extract was mixed with AgNO₃ and HAuCl₄ solutions in separate reactions, the amalgamated solutions turned deep reddish brown and dark purple in colour after 48 h indicating the formation of AgNPs and AuNPs. UV-Visible analysis of green synthesised AgNPs and AuNPs have shown absorption maximum at 443.85 nm and 539.72 respectively after 48 h. Energy dispersive X-ray spectroscopy (EDX) analysis confirmed the presence of pure silver in the green synthesised AgNPs and pure gold in the plant-mediated AuNPs. X-ray diffractometer (XRD) data revealed the face-centred cubic nature of AgNPs. Fluorescence transmission infrared (FTIR) spectrum has shown the characteristic peaks of different phytochemicals in the plant extract which acted as stabilising or capping agents of AgNPs. Scanning electron microscopy (SEM) analysis of AgNPs and AuNPs revealed that the nanoparticles are monodispersed. Transmission electron microscopy (TEM) studies revealed that AgNPs were mostly spherical with an average size of 25 nm whereas selected area electron diffraction (SAED) analysis confirmed their crystalline nature. Both AgNPs and AuNPs of S. tuberosa Lour have shown potential catalytic activity in the presence of sodium borohydride (NaBH₄) in the degradation and removal of 4-nitrophenol, methylene blue, methyl orange and methyl red.

The environmental-economic focus of wastewater treatment and management attracts growing attentions in recent years. The static efficiencies and their dynamic changes are helpful to systematically assess the environmental performance of the water agencies and wastewater treatment plants (WWTPs). Additionally, identifying key factors of efficiencies is critical to improve the operation of WWTPs. In this study, the window method of data envelopment analysis (DEA) was applied to estimate the annual efficiency for four Canadian WWTPs and to explore the variations of annual efficiency under different window lengths. Meanwhile, the Tobit regression analysis was developed to determine the driving forces for WWTPs’ efficiency. The empirical results showed that: (i) the selected DEA window length remarkably affected both the average efficiency and the variations; however, it had no impact on the ranking of plants’ efficiency; (ii) lower efficiencies were observed in plants with larger capacities due to higher infrastructure and operation investments involved; (iii) both the influent total phosphorus concentrations and influent flow rates had significant effects on the WWTPs’ performance. Moreover, the staff and utility expenditures should be reduced to generate greater potential cost savings and efficiency improvement given the treatment technologies employed.

The current study describes the preliminary assessment and securing activities of the largest and most hazardous POPs-contaminated sites in Kyrgyzstan. In 2010, cattle died and population were found with high pesticide levels in blood, human milk, and placenta. In the first phase of the study, a historic assessment of the pesticide dumping at the landfill/dump sites have been conducted. In the second phase, soil analysis for organochlorine pesticides in the areas of the pesticide disposal sites, the former pesticides storehouses, agro-air strips, and the cotton-growing fields were conducted. By this assessment, a first overview of the types and sources of pollution and of the scale of the problem is compiled including information gaps. From major pesticides used, DDT, DDE, and HCH were measured in the highest concentrations. With the limited analytical capacity present, a reasonable risk assessment could be performed. This paper also reports on practical risk reduction measures that have been carried out recently at the two major pesticide disposal sites with support of a Dutch environmental engineering company, an international NGO (Green Cross Switzerland) and local authorities from the Suzak region within an UN project. Local population living near the sites of the former pesticide storehouses and agro-airstrips are advised not to cultivate vegetables and melons or to raise cattle on these areas. Instead, it is recommended to grow technical crops or plant trees. Further recommendations on monitoring and assessment is given including the suggestion to consider the findings in the National Implementation Plan of Kyrgyzstan.

This study evaluated the genotoxic potential of atmospheric pollution associated with urbanization using the model organism Drosophila melanogaster and the Comet assay with hemolymph cells. Larvae were exposed to atmospheric compounds in an urban and a rural area in the municipality of Vitória de Santo Antão, Pernambuco, Brazil, for 6 days (from the embryo stage to the third larval stage) in April 2015 and April 2017. The results were compared to a negative environmental control group exposed to a preserved area (Catimbau National Park) and to a negative control exposed to the laboratory room conditions. The Comet assay demonstrated significant genetic damage in the organisms exposed to the urban area compared with those exposed to the rural area and negative control groups. The evidences were supported by particulate matter analysis showing higher photopeaks of chemical elements such as aluminum, silicon, sulfur, potassium, calcium, titanium, and iron, associated to road dust fraction in urban environment. Once again, the results confirm D. melanogaster an ideal bioindicator organism to monitor genotoxic hazard associated with atmospheric pollution.