Vertical variations of radionuclides, trace metals, and major elements were determined in two sediment cores, which were collected in the marine environment of Ierissos Gulf near Stratoni’s mining area. The enrichment factors (EFs) were also estimated and provided moderately severe to extremely severe enrichment for most trace elements and Mn, describing the anthropogenic influence in the gulf during the previous century. According to the applied dating models based on ²¹⁰Pb and ¹³⁷Cs, the effect in the marine sediment due to the exploitation of pyrite for the production of sulfuric acid during 1912–1920 was observed. Additionally, the decrease of mining activity during 1935–1945 due to the Second World War and the type of ore exploitation, the alteration of the exploited ores, and the construction and operation of Olympiada’s floatation plant during 1950–1970 were identified. The end of tailing discharging into the marine environment during 1980–2010 was also noted.

This paper reports the effects of single and combined application of biochar and phosphate fertilizer on immobilization of heavy metals in e-waste-contaminated soils. The results showed that combined amending biochar and phosphate fertilizer improved physical and chemical characteristics of soil but resulted in ammonium nitrogen loss. Biochar combined with phosphate fertilizer increased shoot biomass of lettuce while biochar applied alone could inhibit the growth of lettuce. A distinct decrease of heavy metal concentrations in lettuce was observed in phosphate fertilizer + biochar (3.0%) treatments while highest heavy metal concentrations in shoots and roots were observed in control treatments. In phosphate fertilizer (0.8%) + biochar (3.0%) treatment, Cd, Cu, Pb, and Zn concentrations of lettuce leaf were reduced by 34.78%, 29.37%, 46.59%, and 40.95%, respectively. Biochar + phosphate fertilizer and biochar both reduced bioconcentration of Cd, Cu, Pb, and Zn in different tissues of lettuce while transshipment of Cd, Cu, Pb, and Zn from root to shoot increased after combined amendment of biochar with phosphate fertilizer. Application of phosphate fertilizer + biochar enhanced the immobilization of Cd, Cu, Pb, and Zn by decreasing the exchangeable Cd, Cu, Pb, and Zn in the soil. Precipitation, adsorption, ionic exchange, and chelation contributed to the good immobilization capacity of biochar + phosphate fertilizer on Cd, Cu, Pb, and Zn in e-waste-contaminated soils.

Two materials (ZnO nanoparticles (nanZnO) and a composite (Ze-nanZnO)) were prepared; the composite was prepared by chemical precipitation on a natural zeolite. The materials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), UV-Vis spectroscopy (UV-Vis), and Branauer-Emmett-Teller (BET) surface area. These materials were evaluated for the removal of tartrazine; this dye was used because it is considered a dangerous contaminant. All experiments were done in batch process. The effect of different parameters such as the contact time, the initial dye concentration, and pH, in addition to the thermodynamic parameters, were studied in order to determine the best experimental conditions. The nanZnO shows a higher adsorption capacity than the Ze-nanZnO composite; however, the separation of the phases was difficult when nanoparticles were used. According to the kinetic data, the mechanism for the nanZnO is physisorption and for the Ze-nanZnO composite is chemisorption. The results show that this is a useful technique for the removal of this dye.

The effect of two freezing treatment methods, combined ultrasonic freezing and conventional freezing, on secondary municipal wastewater sludge particle size, and the relationship between particle size and soluble organic matter, and dewatering characteristics (filterability and settleability) were examined. Quantitative analysis was carried out to determine the change in sludge particle sizes and the correlation coefficients between particle size and sludge volume index (SVI), capillary suction time (CST), and soluble chemical oxygen demand (sCOD) following freezing treatments. Freezing treatments significantly increased sludge median particle size (d50) to 4 to 5 times of the control, and d10 and d90 increased by 3 to 4 times. The correlation coefficients indicated that both freezing treatment methods were able to simultaneously enhance dewaterability and soluble organic matter (sCOD). Comparisons of the test results of the two freezing methods, as well as freezing methods with other treatment methods examined (ultrasound, thermal, and microwave) were conducted. The relationship between particle size and dewaterability remained constant across all treatment methods with increase in particle size correlated to improved dewaterability while the correlation of particle size and soluble organic matter seemed to depend on the treatment methods.

Highly contaminated exposed legacy gold mine tailings from the late 1800s are present in many locations throughout North America and other parts of the world that experienced gold rushes at that time. Those tailing fields can pose risks to human health and the environment. Revegetation of tailing fields can reduce dust generation and other risks associated with these sites. The objective of this study was to investigate if native rapid-growing plants could be successfully germinated in mercury (Hg) and arsenic (As) contaminated legacy mine tailings, both untreated and treated with a low dose of sodium selenite (Na₂SeO₃) to promote growth and decrease bioaccumulation of contaminants. After screening many candidates, four wide-spread North American native plant species were selected, Juncus tenuis, Anaphalis margaritacea, Symphotrichum novi-belgii, and Panicum virgatum for their tolerance, presence near legacy gold mine sites, and ability to germinate rapidly in harsh conditions. Three of these species germinated and grew well in untreated tailings except for S. novi-belgii. The selenite treatment increased biomass, emergence, shoot height, and root length in J. tenuis; emergence in A. margaritacea; and root lengths in P. virgatum. This treatment also decreased shoot [Hg] and [As] in P. virgatum by 36% and 40%. Low-dose selenite treatments hold promise for supporting germination and growth of native plants in Hg- and As-contaminated tailing fields.

Many organochlorine pesticides (OCPs) are considerably high toxic, and have bioaccumulation potential and chronic adverse impact on both wildlife and human. This study focuses on the fate and metabolic degradation, which is the potential to be more efficient, economic, and safe compared to the aforementioned conventional methods. By these positive attributes, the present work then investigates the capability of newly isolated pathogenic yeast Pichia kluyveri FM012 for biodegradation of DDT in aquatic culture. Pichia kluyveri FM012 mycelia were cultured in a mineral liquid medium consisting of the solution of DDT (40 mg/l) with some experimental conditions such as the initial pH of the culture (5–8), agitation speed (0–150 rpm), and various carbon and nitrogen sources. The highest biodegradation of DDT by Pichia kluyveri FM012 was shown in the culture with pH 5 and 150 rpm agitation. Moreover, the use of glucose and yeast offers the best performance for the degradation compared to other carbon and nitrogen sources. The highest enzyme activity during the decolorization process was dioxygenase. Fourier-transform infrared spectroscopy (FTIR), UV-Vis spectrophotometer, and GC-MS profile showed that the transformation of DDT has occurred. The present DDE and DDD as metabolites of DDT were confirmed by GCMS at a retention time of 17.8 and 16.6 min. The outcomes of this study have several important implications for future practice, for instance in providing an alternative biodegradation agent to remove some organochlorine pollutants.

17-α-Ethinyl estradiol (EE2) is a widely used drug that acts in the endocrine system and in the environment; even at low concentrations, it causes extensive damage to organisms. The most relevant factors for understanding the EE2 degradation and transport mechanisms in soil are through sorption studies. This study investigated the sorption capacity of EE2 in soil collected amidst vegetation in the region of Sorocaba, São Paulo state, Brazil. The soil samples were submitted to the evaluation of the physical-chemical parameters to characterization. The zero point of charge test (ZPC) was run using the adapted method of the 11-point model. Kinetic tests were then carried out, varying the removal times of the samples with fixed EE2 concentration, whereas, for the isotherm tests, the concentrations were varied, and the fixed contact time was maintained. The final concentrations of EE2 were quantified by high-performance liquid chromatography. Data treatments were carried out using mathematical modeling tests present in the literature. The soil presented a medium texture, being predominantly sandy, and the chemical parameters were classified as high and medium. Only the pH parameter was classified as low. The ZPC was 5.57, indicating an adsorption favorable to the EE2 that presented an average pH of 5.73. The adsorption kinetics showed that the equilibrium time for EE2 in contact with the soil is 12 h. The adsorption isotherm presented values related as favorable and adjustable to the Sips isotherm model and estimated the maximum adsorption capacity of 154.2 mgEE₂ Kgₛₒᵢₗ⁻¹, showing affinity with EE2.

This study empirically investigates the agriculture-induced environmental Kuznets curve (EKC) hypothesis in an agrarian framework. Annual time series data from 1981–2014 was employed using augmented Dickey–Fuller and the Phillips–Perron (PP) unit root test complemented by the Zivot and Andrews unit root that accounts for a single structural break to ascertain stationarity properties of variables under consideration. For the cointegration analysis, an autoregressive distributive lag methodology and the recent novel Bayer and Hanck combined cointegration technique are employed. For the direction of causality, the Granger causality test is used as estimation technique. Empirical findings lend support for the long-run equilibrium relationship among the variables under consideration. This study also validates the inverted U-shaped pattern of EKC for the case of Nigeria, affirming that Nigeria remains at the scale-effect stage of its growth trajectory. Further empirical results show that foreign direct investment attraction helps mitigate carbon emissions in Nigeria. Based on these results, several policy prescriptions on the Nigeria energy mix and agricultural operations in response to quality of the environment were suggested for policymakers, stakeholders, and environmental economists that formulate and design environmental regulations and strategies to realise the goal 7 of sustainable development (SDG).

Pharmaceutically active compounds are carried into aquatic bodies along with domestic sewage, industrial and agricultural wastewater discharges. Psychotropic drugs, which can be toxic to the biota, have been detected in natural waters in different parts of the world. Conventional water treatments, such as activated sludge, do not properly remove these recalcitrant substances, so the development of processes able to eliminate these compounds becomes very important. Advanced oxidation processes are considered clean technologies, capable of achieving high rates of organic compounds degradation, and can be an efficient alternative to conventional treatments. In this study, the degradation of alprazolam, clonazepam, diazepam, lorazepam, and carbamazepine was evaluated through TiO₂/UV-A, H₂O₂/UV-A, and TiO₂/H₂O₂/UV-A, using sunlight and artificial irradiation. While using TiO₂ in suspension, best results were found at [TiO₂] = 0.1 g L⁻¹. H₂O₂/UV-A displayed better results under acidic conditions, achieving from 60 to 80% of removal. When WWTP was used, degradation decreased around 50% for both processes, TiO₂/UV-A and H₂O₂/UV-A, indicating a strong matrix effect. The combination of both processes was shown to be an adequate approach, since removal increased up to 90%. H₂O₂/UV-A was used for disinfecting the aqueous matrices, while mineralization was obtained by TiO₂-photocatalysis.

Polychlorinated diphenyl ethers (PCDEs) are a class of potential persistent organic contaminants, which have been widely detected in aquatic environment. In the present study, the effects of 3,4,4′-tri-CDE and its two possible metabolites (2-MeO-3′,4,4′-tri-CDE and 2-HO-3′,4,4′-tri-CDE) on oxidative stress biomarkers in liver of Carassius auratus were evaluated. The fish were treated with these three compounds at different doses (0.1, 1, and 10 μg/L) via semi-static water exposure. The liver samples were individually taken at 3, 7, and 21 days for analysis of oxidative stress indicators, including superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), reduced glutathione (GSH), and malondialdehyde (MDA). Compare to the control group, the hepatic antioxidant enzyme activity and GSH contents showed significant decreases (p < 0.05) at high-dose treatment (10 μg/L) and prolonged exposure time (21 days) in most of the toxicant-treated groups, indicating the occurrence of oxidative stress in fish liver. However, no consistent trend of the variations of antioxidant parameters was observed at low doses (0.1 and 1 μg/L). Meanwhile, the lipid peroxidation was significantly induced with extending exposure time and increasing dose. In addition, the toxicity order of three compounds was discussed using the integrated biomarker response (IBR) index. Notably, 2-HO-3′,4,4′-tri-CDE was indicated to cause the most severe hepatic oxidative stress.