Water quality was evaluated in a coal mining area in the city of Figueira, Paraná State, Brazil, where uranium was associated with the coal deposit. Upstream the mine, groundwaters were more acid and some elements and compounds, such as iron, aluminum, and sulfate, were in higher concentration, possibly because of acid mine drainage (AMD) generation in tailing pit. ²³⁸U and ²³⁴U activity concentrations exceeded the standards proposed by the World Health Organization in two sampling periods in effluent samples and in some groundwater samples, indicating that waters from this aquifer system were unhealthy for human consumption. Uranium isotopes were more elevated in groundwaters in the rainy month probably because of a higher leaching and transport rate of this element from rocks/tailings pit to waters. The average radon activity concentration in groundwater was higher than in surface waters and effluents in both periods studied, possibly due to the enhanced presence of uranium and radium in the aquifer rocks that would favor the radon accumulation and entrapment. The effects of the mining activities on the groundwater quality were displayed in terms of activity ratios (²³⁴U/²³⁸U, ²²⁶Ra/²³⁸U), which showed different behaviors upstream the mine area relatively to areas downstream the mine.

Road dust impacts almost all terrestrial areas of the planet and may impact vegetation and nearby ecosystems. Therefore, research methods are needed for applying road dust in a controlled manner on targeted areas (e.g. plants). Three dust application methods, sifter, sieve, and sprayer, were investigated for their uniformity in applying dust in a 0.75 m × 0.75 m area. Within the treatment area 196, 37-ml cups were placed in a uniform fashion to collect dust applied at 15.8, 78.8, and 158 g. At the 15.8 and 78.8 g rates, the coefficient of uniformity for each method was >98% indicating a uniform amount of dust applied. At the 158 g rate, the sifter and sieve had coefficient of uniformities >95%, while the sprayer had a significantly lower (p < 0.05) coefficient of uniformity (46%). Although the sifter and sieve were simpler to use and the least expensive options, the sprayer may be more useful when applying dust to larger areas when the exact amount of dust entering and exiting the systems does not need to be controlled. This research is useful to anyone looking to apply road dust or similar sized particulates under controlled field or laboratory conditions.

This work studies the degradation of safranin T (SF, a recalcitrant pollutant) by an electrochemical process and three photochemical advanced oxidation technologies (TiO₂ photocatalysis, UV/H₂O₂, and photo-Fenton). The degradation routes of each process were elucidated initially. Based on the mineralization extent, improvement of the treated solutions’ biodegradability, and energy consumption, the most suitable process was identified. Interestingly, in the electrochemical system, safranin T was efficiently eliminated through electrogenerated HOCl. In contrast, the popular photo-Fenton process was unable to degrade SF. Moreover, the pollutant was refractory to highly energetic UV₂₅₄ irradiation. Meanwhile, the UV/H₂O₂ and TiO₂ photocatalysis processes removed SF slowly. Interestingly, the electrochemical system produced biodegradable solutions. Furthermore, the electrical energy consumption (EC) for the 100% removal of SF showed that the electrochemical process only spent 0.04 and 0.06% of the EC needed by TiO₂ photocatalysis and UV/H₂O₂, respectively. Therefore, the fast SF degradation, the high biodegradability intensification, and the very low energy consumption evidenced the relative advantages of the electrochemical process for the remediation of water containing safranin T. Finally, to obtain a deeper understanding of SF degradation by the electrochemical system, an analysis of structural transformations was made. It was found that the electrogenerated HOCl initially attacked the central azine and the aromatic amines on SF. Subsequently, aliphatic compounds were formed, which due to their biodegradable character could be completely eliminated by a conventional biological system or discharged into natural media.

The accumulation of ash, heavy metals, and polycyclic aromatic hydrocarbons (collectively called potential accumulating substances, PAS) was evaluated to ascertain the stability of lysis–cryptic growth sludge reduction process (LSRP) for municipal sludge treatment. One sequencing batch reactor (SBR) incorporated with homogenization was run to test the LSRP and another SBR as a control. The continuous monitoring results for 2 months showed that the ash and heavy metals slightly increased, and the polycyclic aromatic hydrocarbons decreased by 18.0%, indicating that there may be negligible accumulations during the LSRP. Their accumulations met pattern I, as demonstrated by statistical analysis, proving no PAS accumulation for LSRP. This was further confirmed by sludge activity and system performance. Moreover, the mechanism for no PAS accumulation was discussed. It was concluded that the LSRP was stable with no worries about PAS accumulation under the operational conditions.

The aim of this study was to evaluate the redox mediating capacity of anthraquinone-2,6-disulfonate (AQDS) immobilized on granular activated carbon (GAC) during the reductive decolorization of direct blue 71 (DB71) under microbial and chemical conditions. The immobilization of AQDS on GAC was conducted by adsorption, and it has obtained an uptake capacity of 0.227 mmol g⁻¹. The anchorage of AQDS on GAC improved its electron transfer capacity (ETC) up to 2.05 times higher than the raw material. Similarly, the addition of GAC-AQDS increased up to 1.75- and 1.16-fold the rate of decolorization (k d) of DB71 under microbial and chemical conditions, respectively, in comparison to the unmodified GAC. Surprisingly, a higher k d value was achieved in incubations without either GAC or GAC-AQDS because of the generation of aromatic amines, from the reduction DB71, taking into account that these species may act as a catalyst in the DB71 reduction process. In contrast, adsorption of aromatic amines on either GAC or GAC-AQDS decreased its redox mediating capacity as evidenced by spectrophotometric screenings of the decolorized solution and the supporting material. The development of materials with enhanced both redox and adsorption properties, as the GAC used in this study, offers a promising way to increase the redox conversion of recalcitrant pollutants commonly found in industrial wastewaters.

This study describes the immobilization of ginger peroxidase on amino-functionalized silica-coated titanium dioxide nanocomposite and its application in bioremediation process. A dramatic enhancement in enzyme activity was observed after immobilization on nanosupport which was evident from the effectiveness factor (η) value of 1.76. Immobilization of enzyme on nanosupport was confirmed by transmission electron microscopy, scanning electron microscopy, and Fourier transform infrared spectroscopy. Immobilized peroxidase exhibited higher activity in a broad range of pH and temperature as compared to free enzyme. Also, the thermostability of peroxidase was strikingly improved upon immobilization. After six repeated uses, the immobilized peroxidase retained around 62% of its dye decolorization activity. V ₘₐₓ of the enzyme was changed to 35.01 μmol L⁻¹ min⁻¹ from 8.42 μmol L⁻¹ min⁻¹ after immobilization on nanocomposite, which was a fourfold increase as compared to the free enzyme. Circular dichroism spectroscopy demonstrated conformational changes in the secondary structure of the enzyme, a possible reason for the enhanced enzyme activity after immobilization. Immobilized peroxidase was highly efficient in the removal of acid yellow 42 dye in a stirred batch process, i.e., 90% of the dye was decolorized within 1.5 h as compared to the free enzyme decolorizing only 69% of the dye in the same period. Our results clearly demonstrate that this nanobioconjugate with enhanced catalytic activity, high stability, and very good reusability has remarkable potential for the treatment of aromatic pollutants present in wastewater. Graphical Abstract Schematic representation of immobilization of ginger peroxidase on amino functionalized silica coated titanium dioxide nanocomposite and its use in dye decolorization process.

The functional classification of β-lactamases is done through assessing their ability to hydrolyze specific β-lactams and its inactivation by inhibitors. This study investigated the β-lactamases encoding genes present in soil samples from different origins (landfill, preservation area, and soil from a farm). Genes codifying for ESBL enzymes bla SHV, bla TEM₋₁₁₆ and bla OXA₋₁ were found in all analyzed samples. Gene for ESBL bla CTX₋M₋₁₄ was detected in the landfill and farm soil samples, but they were not found in the preservation area, while bla OXA₋₄₈₋ₗᵢₖₑ was present just in the soil from the landfill. The gene for the MBL bla VIM was found in the soil sample from a farm. The results indicate that bla SHV, bla TEM₋₁₁₆, and bla OXA₋₁ genes are scattered in soils with and without potential contaminants; however, genes bla CTX₋M₋₁₄, bla OXA₋₄₈, and bla VIM were detected just in polluted areas.

The progressive development of civilization and intensive industrialization has contributed to the global pollution of the natural environment by heavy metals, especially the soil. Degraded soils generally contain less organic matter, and thus, their homeostasis is more often disturbed, which in turn manifests in changes in biological and physicochemical properties of the soil. Therefore, new possibilities and solutions for possible neutralization of these contaminations are sought, inter alia, through reclamation of degraded land. At present, the use of additives supporting the reclamation process that exhibit heavy metal-sorbing properties is becoming increasingly important in soil recovery. Research was conducted to determine the role of compost in stabilizing the microbial and biochemical balance of the soil due to the significant problem of heavy metal-contaminated areas. The study was conducted on loamy sand, to which zinc was applied at the following doses: 0, 250, 500, 750, 1000, and 1250 mg Zn²⁺ kg⁻¹ DM of soil. Compost was introduced to the appropriate objects calculated on the basis of organic carbon content in the amount of 0, 10, and 20 g Cₒᵣg kg⁻¹ DM of soil. The study was conducted over a period of 20 weeks, maintaining soil moisture at 50% capillary water capacity. Zinc significantly modified soil microbiome status. The abundance of microorganisms and their biological diversity and the enzymatic activity of the soil were affected. The negative effects of contaminating zinc doses were alleviated by the introduction of compost into the soil. Organic fertilization led to microbial growth intensification and increased biochemical activity of the soil already 2 weeks after compost application. These effects persisted throughout the experiment. Therefore, it can be stated that the use of compost is an appropriate method for restoring normal functions of soil ecosystems contaminated with zinc.

Edible muscle tissues of Solea solea, Mullus barbatus, and Sardina pilchardus marketed in Mersin were analyzed for their Cr (total), Mn, Fe, Ni, Cu, Zn, As (total), Cd, Sn, and Pb levels. Metal levels of the tissues were determined using inductively coupled plasma-mass spectrophotometric (ICP-MS) methods. Muscle levels of Cr, Mn, Fe, Ni, Cu, Zn, As, Sn, and Pb were determined as 0.19–2.80, 0.08–3.88, 0.93–25.76, 0.03–0.63, 0.01–1.96, 1.28–45.95, 0.49–25.26, 0.14–4.03, and 0.02–1.37 mg kg⁻¹ w.w., respectively. Cadmium levels were below detection limits in all the muscle samples taken. Mean metal levels of the tissues were compared with the provisional tolerable daily (PTDs) and weekly (PTWIs) intake limits. Mean metal levels taken by the consumption of analyzed tissues were below PTDs and PTWIs; hence, the fish species studied do not pose any risk for human consumption from the point of heavy metals.

An effective reagent for mercury desorption from contaminated soil is a key condition for mercury remediation. Effects of time, pH, temperature on mercury desorption using sodium sulfite were studied with a series of batch experiments. Results showed that desorption rate of mercury increased rapidly in the stage of 0 to 1 h, after that, a much slower stage appeared. Desorption rate reached 92.05% with 0.7 mol/L sodium sulfite at 25°C in 24 h. Moreover, potential value increased rapidly from −162 to –31 mV in desorption of 1 h. It indicates that desorption process was a process of Hg(II) turning into Hg(I). A higher pH (10.5) or temperature (35°C) was helpful to increase mercury desorption rate. Furthermore, small fold and curves appeared in the surface of soil particles presented by scanning electron microscopy (SEM) show that soil particles may be destroyed in desorption process using sodium sulfite. The desorption of Hg from contaminated soil was accomplished within a reductive solution provided by sodium sulfite.