The aim of this study was to investigate the presence of heavy metals/metalloids (Pb, Cd, Hg, Cu, Fe, Zn, As) in the muscle tissue of fish from the Danube River (two locations: Zemun and Grocka). For the purpose of heavy metal determination in fish muscle, 120 samples of six different fish species, Prussian carp, barbel, bream, carp, pike perch, and catfish were collected. For determining heavy metals, we used microwave oven digestion and atomic absorption spectrometer methods. The highest average content of Pb (0.084 ± 0.004 mg kg⁻¹), Cd (0.082 ± 0.003 mg kg⁻¹), Hg (0.466 ± 0.006 mg kg⁻¹), and As (0.333 ± 0.007 mg kg⁻¹) was found in the muscle of carp (an omnivorous fish) from Grocka, while the highest average level of Fe (13.60 ± 0.03 mg kg⁻¹) was deposited in bream (also omnivorous) from Zemun. Also, the average Cu level (1.62 ± 0.13 mg kg⁻¹) was the highest in catfish muscle (a carnivorous fish) from Grocka, while the highest Zn content (11.16 ± 0.17 mg kg⁻¹) was determined in muscle of Prussian carp (an omnivorous fish) from Zemun. The highest content of heavy metals (Cu, Fe, and Zn, respectively) in muscle of the six different types of fish from both locations was symmetrically arranged by species (catfish, barbel, and Prussian carp, respectively). Concentrations of Pb, Hg, and As in the Danube River fish muscle were under the maximum residual levels prescribed by the European Union (EU) and the maximum allowed concentrations (MAC) for Serbia. On the other hand, in all fish muscle from both locations (Zemun and Grocka), higher concentrations of Cd than prescribed (MAC) were found, with the exception of bream and pike perch.

Spontaneous colonization of mine tailing dams by plants is a potential tool for phytostabilization of such reservoirs. However, the physical and chemical properties of each mine tailings deposit determine the success of natural plant establishment. The plant Baccharis linearis is the main native nanophanerophyte species (evergreen sclerophyllous shrub) that naturally colonizes abandoned copper tailings dams in arid to semiarid north-central Chile. This study compare growth of B. linearis against the physical and chemical properties of a Technosol derived from copper mine tailings. Five sites inside the deposit were selected based on B. linearis vegetation density (VD), at two soil sampling depths under the canopy of adult individuals. Physical and chemical properties of tailings samples and nutrient concentrations in tailings and plants were each determined. Some morphological features of the plants (roots and aerial parts) were also quantified. There were significant differences in soil available water capacity (AW) and relative density (Rd) at different VD. Sites with low AW and high Rd had lower nutrient concentrations and higher Zn content in tailings, decreased infection by arbuscular mycorrhizal fungi, and increased fine root abundance and root hair length in individual plants. In contrast, higher AW, which was positively correlated with fine particles and organic matter content, had a positive effect on vegetation coverage, increased N and P contents in tailings, and increased N contents in leaf tissues, even when available N and P levels in tailings were low. Multiple constraints, such as low AW, N, P, and B contents and high Zn concentrations in the tailings restricted vegetation coverage, but no phenotypic differences were observed between individuals. Thus, in order to promote dense coverage by B. linearis, water retention in these tailings must be improved by increasing colloidal particles (organic and/or inorganic) contents, which have a positive effect on colonization by this species.

With the increase in the occurrence of heavy metal polluted rice in Asian countries, food safety of rice products is of utmost concern to consumers. The current study discusses the distribution of trace elements Cr, Cu, Zn, As, Se, Cd, Hg, and Pb in Asian rice-derived food products. Three types of food products, rice noodles, rice vinegar/wine, and rice snacks, were chosen for examination. Most toxic heavy metals and metalloid such as As, Cd, Hg, and Pb were found to be within the safe level of EPA. Since rice vinegar/wine is not the staple food for people, there is no noticeable safety concern. Rice noodles and snacks are consumed with noticeable Se content and they are possible for human Se source addition. With comparison with raw rice, rice-derived food products showed better quality in terms of toxic heavy metals and metalloids. This study is for the first time reporting a thorough understanding of safety concern of rice-derived food products. It provides baselines and understanding on current levels of trace elements and heavy metals in Asian-derived rice products as affected by food processes. It would also help consumers build up confidence on the food safety of Asian rice products.

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.

In order to determine the possible impact on the marine environment, we present a study on the dispersal and bioavailability of sediment-associated heavy metals related to underwater blasting and dredging of bedrock operations during a quay construction. The environmental impact was primarily assessed by deploying a buoy setup including sediment traps, blue mussels, and passive samplers (diffusive gradient in thin films, DGTs) in a gradient from the construction site during the operations. Samplings were made during five separate periods covering a total span of about 2.5 months. Analyses included sedimentation rates, organic content, and metal concentrations of the material collected in the sediment traps and metal concentrations of the mussels and passive samplers. The construction work was associated with a considerable dispersion of sediments, organic material, and associated heavy metals. The major fraction of the sediment settled in the vicinity of the construction site. While the mussels were found to accumulate some metals in a distance-related manner to the construction site and no such accumulation in the DGTs occurred, we conclude that most of the dispersed metals were particle associated. It was found that while a large part of the material settled in the vicinity of the construction site, most of the fine-grained and/or organic sediment that was brought into suspension was transported further away from the construction site (beyond the 350 m) most likely carrying contaminants including heavy metals. For future studies of risks and monitoring of underwater blasting and dredging, we recommend to include a larger monitoring area and more importantly water samples of the suspended plumes. Graphical Abstract The dispersal of sediments and bioavailability of heavy metals were assessed using a buoy setup during underwater blasting and dredging. ᅟ

A treatment system combining the coal-based carbon membrane with electrochemical oxidation process was designed for the enhanced microalgae removal from simulated ballast water. The effects of various parameters including microalgae species, microalgae density, electric field intensity, and electrical conductivity on the separation performance were carried out. Fouling test was further performed for assessing the antifouling ability of the treatment system. The results showed big microalgae species tended to form a thick fouling layer on the carbon membrane, resulting in low permeate flux. High microalgae density gave rise to serious membrane fouling, which decreases the permeate flux. The treatment system showed enhanced permeate flux and fouling resistance by coupling with electrochemical oxidation process. High conductivity favored the electrochemical reactions on the surface of the carbon membrane, which reduces the clogging of the microalgae to the carbon membrane. After cleaning, the treatment system still kept high permeate flux, implying its good regeneration ability.

Modification of a catalyst with polyethylene glycol (PEG) created a dramatic increase in the catalytic activity for the degradation of phenol wastewater. The Fe/PEG-modified γ-Al₂O₃ catalyst was prepared by an impregnation method. The as-prepared catalyst was characterized by X-ray photoelectron spectroscopy, wide- and small-angle X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and N₂ adsorption-desorption experiments, and the results showed that the Fe species were highly dispersed on the surface of the PEG-modified support. At the same time, the PEG modification resulted in an increase in the Brunauer-Emmett-Teller surface area and pore volume. The catalytic activity test showed that the Fe/PEG-modified γ-Al₂O₃ catalyst exhibited a superior performance for the degradation of phenol wastewater in this study, and the phenol and COD removal values reached 94.1 and 88.9%, respectively, within 60 min. The results clearly show that PEG modification is a promising methodology for the preparation of a catalyst with good dispersal of the active component on the support.

Excessive algae growth has generated conflicts on the use of water supplies; therefore, the focus on new technologies to remove algae from water bodies is demanding. The aim of the present study was to assess the effect of hydrodynamic cavitation on the inactivation of microalgae belonging to genus Scenedesmus. A laboratory-scale experimental apparatus was built in order to accomplish this goal; it consisted of a Venturi device designed to generate the cavitation phenomenon. Suspended microalgae samples were treated for 60 minutes under different cavitation intensities (cavitation number—Cv—ranging from 0.17 to 0.27). Results evidenced that microalgae decay over time can be modeled through first-order kinetics. The maximum removal efficiency (85%) was recorded at the highest cavitation intensity (Cv = 0.17). The removal efficiency decreased as the cavitation number increased. Hydrodynamic cavitation was effective in inactivating Scenedesmus; it produced irreversible damages to cell morphology such as flotation spines removal, cell wall lesions, cytoplasm extravasation, and cavity formation. Assumingly, hydrodynamic cavitation has great potential to treat eutrophic water bodies. Furthermore, it represents a sustainable removal technique, since it does not produce secondary pollution.

Dissipation rates of copper following algaecide treatments resulting in pulse exposures can be accurately modeled if the component dissipation rates are known. Scaled experiments (in situ, laboratory and mesocosm) were used to parse and rank dominant processes from concurrent processes affecting copper fate in pulse exposures. Copper dissipation rates were measured cumulatively in situ and in mesocosms as well as individually in laboratory experiments. Predictions of the influence of individual dissipation rates on the cumulative dissipation rate were assessed mathematically. In situ aqueous copper dissipated rapidly following an algaecide treatment, with a measured half-life of 0.03 days. Based on laboratory experiments, the most rapid copper fate process was dilution with a half-life of 0.03 days, followed by sediment sorption with a half-life of approximately 3 days. Mesocosm experiments incorporating physical characteristics of the site (i.e., dilution, sediment, algae, and site water) resulted in similar copper dissipation rates (0.02 days) relative to the in situ copper dissipation rate. Prediction of the fate of copper from algaecide treatments requires incorporation of accurate estimates of dominant fate processes that can be determined physically and mathematically.

The objective of this study was to evaluate the influence of the soil parameters (particle size, initial contamination level, etc.) on the performances of an attrition process to remove As, Cr, Cu, pentachlorophenol (PCP) and dioxins and furans (PCDD/F). Five different contaminated soils were wet-sieved to isolate five soil fractions (< 0.250, 0.250–1, 1–4, 4–12 and > 12 mm). Five attrition steps of 20 min each, carried out in the presence of a biodegradable surfactant ([BW] = 2%, w w⁻¹) at room temperature with a pulp density fixed at 40% (w w⁻¹), were applied to the coarse soil fractions (> 0.250 mm) of different soils. The results showed good performances of the attrition process to simultaneously remove PCP and PCDD/F from contaminated soil fractions initially containing between 1.1 and 13 mg of PCP kg⁻¹ (dry basis) and between 1795 and 5720 ng TEQ of PCDD/F kg⁻¹. It appeared that the amounts of contaminants removed were significantly correlated (p value < 0.05, R ² = 0.96) with the initial amounts of PCP and PCDD/F, regardless of the particle size of the soils studied. The nature of the soil (granulometric distribution, pH, total organic carbon (TOC) (organic matter) and diverse industrial origin) slightly and negatively influenced the efficiency of organic contaminants removals using attrition. However, the attrition treatment allowed an efficient removal of both PCP and PCDD/F from the coarse fraction of contaminated soil, despite the nature of the soil.