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.

The aim of this study was to characterize qualitatively and quantitatively the composition of the main rhizodeposits emitted from maize (Zea mays) under Cd stress, in order to discuss their role in Cd availability and tolerance. Maize was grown for 6 weeks in sand at four Cd exposure levels (0, 10, 20, and 40 μM Cd in nutrient solution) and two types of rhizodeposits were collected at the end of cultivation period. Mucilage and other molecules adhering to rhizospheric sand were extracted with a buffer before root exudates were collected by diffusion into water. Total carbon, proteins, amino acids, and sugars were analyzed for both rhizodeposit types and about 40 molecules were identified using GC-MS and LC-MS. Cadmium effect on plant morphology and functioning was slight, but consistent with previous works on Cd toxicity. However, rhizodeposition did tend to be impacted, with a decrease in total carbon, sugars, and amino acids correlating with an increasing Cd content. Such a decrease was not noticeable for proteins in root exudates. These observations were confirmed by the same trends in individual compound contents, although the results were generally not statistically significant. Many of the molecules determined are well-known to modify, whether directly or indirectly, Cd speciation and dynamics in the soil and could play a role in Cd tolerance.

The in vitro effect of enrofloxacin (EFZ) was tested on two experimental somatic bovine cells in vitro: peripheral lymphocytes (PLs) and cumulus cells (CCs). The cytotoxicity and genotoxicity of this veterinary antibiotic were assessed using 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assays, single-cell gel electrophoresis (SCGE) assay, and cytokinesis-block micronucleus cytome (CBMN cyt) assay. Cells were treated during 24 h, and three concentrations were tested (50 μg/mL, 100 μg/mL, 150 μg/mL). When EFZ was tested in PLs, the results demonstrated that the antibiotic was able to induce cell death and DNA damage with all concentrations. In addition, 50 μg/mL and 100 μg/mL EFZ increased frequencies of micronuclei (MNi). On the other hand, the highest EFZ concentration occasioned cellular cytotoxicity in CCs as evidenced by mitochondrial activity alterations. Nevertheless, EFZ was not able to induce DNA damage and MNi in CCs. These results represent the first experimental evidence of genotoxic and cytotoxic effects exerted by EFZ in bovine PLs and CCs.

Plastic pollution is one of the most acute environmental topics of our time. While there is a great scientific effort to tackle this problem, it has not always been well-coordinated or properly targeted. In this short review, we call for scientists to get involved in three crucial topics (threats) underestimated—or ignored—in freshwater systems: (i) plastic-species entanglement, (ii) plastic as nesting material, and (iii) macroplastic debris coming from mismanaged household solid waste. Reducing the knowledge gaps between marine and freshwater environments will be crucial to solute the plastic pollution problem effectively and globally. Therefore, we make a plea here to reinforce research activities on these three issues in freshwater environments worldwide.

Epoxiconazole is a broad-spectrum fungicide described as highly persistent in soil and as such can be considered as an abiotic agent like other problematic agrochemicals. Furthermore, the plant phenotyping tool involving non-invasive monitoring of plant-emitted volatile organic compounds (VOCs) may be useful in the identification of metabolic markers for abiotic stress. We therefore decided to profile the VOCs from secondary metabolism of oilseed rape through a dose-response experiment under several epoxiconazole concentrations (0, 0.01, 0.1 and 1 mg L⁻¹). VOC collections of 35-day-old whole plantlets were performed through a dynamic headspace sampling technique under defined and controlled conditions. The plantlets grew freely within a home-made, laboratory and high-throughput glass chamber without any disturbance. Putative metabolic markers were analysed using a targeted metabolomic approach based on TD-GC-MS method coupled with data acquisition in SIM mode in order to focus on terpenes and sulphur-containing volatiles. Chromatograms of emitted terpenes were achieved accurately for the 35-day-old oilseed rape plantlets. We also analysed the presence of sulphur-containing volatiles in samples of shoot and root tissues using an innovative DHS-TD-GC-MS method, but no difference was found between qualitative profiles. Nevertheless, we demonstrated through this experiment that sesquiterpenes such as β-elemene and (E,E)-α-farnesene are involved in epoxiconazole dose-response. In particular, (E,E)-α-farnesene could serve as a metabolic marker of fungicide exposure for oilseed rape plantlets.