In this study, the adsorption kinetic of cesium, strontium, and rubidium radionuclides was investigated using ferritin magnetic molecules. Kinetic investigation of synthetic and natural wastes was carried out and the results were compared. Pseudo first-order, pseudo second-order, Elovich, double-exponential, and intraparticle diffusion models were the kinetic models used in the fitting of experimental data. The kinetic study of synthetic waste revealed that the double-exponential model demonstrated excellent fitting. Coefficient of determination resulting from fitting of cesium, strontium, and rubidium radionuclide’s adsorption results via the double-exponential model are 0.9938, 0.9905, and 0.9863, respectively. In the experiments conducted on natural wastes, too, all of the five kinetic models were investigated. Results indicated that the double-exponential model matched greatly with the experimental data, and cesium, strontium, and rubidium radionuclide’s coefficients of determination were 0.9742, 0.9613, and 0.9442, respectively. Comparison of the results of natural and synthetic wastes showed that matching with the model and recovery of target elements were more prominent in experiments with synthetic waste (unicomponent) rather than natural waste (multicomponent).

Five common fungal strains, Cladosporium cladosporioides, Aspergillus clavatus, Penicillium citrinum, Fusarium oxysporum, and Alternaria alternata, were cultivated in presence of iodide and iodate to evaluate their efficiency in iodine biovolatilization and bioaccumulation. Our results suggest that iodide and iodate bioaccumulation by microscopic filamentous fungi is similar although the biological transformation into volatile iodine compounds is driven by various pathways resulting in higher volatilization efficiency of iodate. Thus, the mobilization of iodate by filamentous fungi is superior to iodide mobilization. Our paper is also the first to compare the iodide and iodate volatilization efficiency by microorganisms. Our results highlight the significant role of filamentous fungi in biogeochemistry of iodine, especially in formation of environmentally reactive volatile forms that may contribute to ozone layer destruction.

Metals are commonly determined in aquatic organisms, primarily using bivalves to provide important data on their bioavailability. The technique of diffusive gradients in thin films (DGTs) has also been employed to assess the concentration of metals in freshwater and marine environments, determining their lability. The present work evaluated and compared the labile and bioavailable concentrations of Cd, Co, Cu, Mn, Ni and Pb in seawater from Ilha Grande Bay, RJ, using DGT and transplanted bivalves (Nodipecten nodosus), respectively. The scallops and DGTs were immersed in water at three sampling locations within the bay from July to September 2012 (winter campaign) and from December 2012 to February 2013 (summer campaign). The metals were determined by inductively coupled plasma-mass spectrometry (ICP-MS) and optical emission spectrometry (ICP-OES). DGT technique was successfully used to determine the concentrations of metals in waters, except for Pb when short deployment times were used. All metals were determined using transplanted bivalves (N. nodosus), but pre-exposure to Cd was evident, which made the interpretation of the data for this analyte difficult. The data on metal lability in Ilha Grande Bay waters obtained from the DGT technique were correlated with the metal bioavailability determined in the soft tissues of the transplanted N. nodosus for Co, Cu, Mn, Ni and Pb. This is the first evaluation of this type for this area of high environmental concern. Both techniques revealed that Náutico was the location with the highest concentration of metals in the study area.

A novel adsorbent was prepared by introducing xanthate group onto pristine multi-walled carbon nanotubes (MWCNTs) for removing Pb (II) from aqueous solution. The structure and property of xanthate-modified MWCNT (MWCNT-X) were detected by the technologies of Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), thermal gravimetric analysis (TGA), and Brunauer–Emmett–Teller (BET). The investigation of various parameters, such as initial metal concentration, pH, contact time, and temperature, was taken to illustrate the adsorption behaviors of Pb (II) on MWCNT-X. Based on experimental data, Langmuir isotherm and pseudo-second-order kinetic provided a better correspondence to the adsorption process. The negative values of ΔG ᶿ and ΔH ᶿ indicated that the adsorption process is exothermic and spontaneous. Besides, the maximum uptake of MWCNT-X reached to 83.01 mg/g, which was much higher than that of pristine MWCNT and hydroxylated MWCNT (MWCNT-OH). Thus, the MWCNT-X can be potentially applied in heavy metal treatment.

Human health risks associated with the consumption of metal-contaminated fish over extended periods have become a concern particularly in Taiwan, where fish is consumed on a large scale. This study applied the interaction-based hazard index (HI) to assess the mixture health risks for fishers and non-fishers who consume the arsenic (As), copper (Cu), and zinc (Zn) contaminated milkfish from As-contaminated coastal areas in Taiwan, taking into account joint toxic actions and potential toxic interactions. We showed that the interactions of As–Zn and Cu–Zn were antagonistic, whereas As–Cu interaction was additive. We found that HI estimates without interactions considered were 1.3–1.6 times higher than interactive HIs. Probability distributions of HI estimates for non-fishers were less than 1, whereas all 97.5%-tile HI estimates for fishers were >1. Analytical results revealed that the level of inorganic As in milkfish was the main contributor to HIs, indicating a health risk posed to consumers of fish farmed in As-contaminated areas. However, we found that Zn supplementation could significantly decrease As-induced risk of hematological effect by activating a Zn-dependent enzyme. In order to improve the accuracy of health risk due to exposure to multiple metals, further toxicological data, regular environmental monitoring, dietary survey, and refinement approaches for interactive risk assessment are warranted.

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.

Nitrogen dioxide (NO₂) is one of the major atmospheric pollutants, and the concentration of NO₂ is regarded as one of the indicators of air quality. In the past decades, China has experienced rapid economic growth and severe NO₂ pollution to match. We evaluate the trends and spatiotemporal patterns of tropospheric NO₂ over mainland China from 2005 to 2014 using vertical column density (VCD) datasets retrieved from the Ozone Monitoring Instrument (OMI). Results show that from 2005 to 2014, NO₂ pollution regions have enlarged at the national scale, and high NO₂ VCDs are mainly concentrated over highly populated regions in eastern China. The year 2011 is the turning point. Tropospheric NO₂ VCDs first significantly increase by 0.19 × 10¹⁵ molec cm⁻² year⁻¹ (R ² = 0.94, P = 0.002) from 2005 to 2011, and then decrease by 0.21 × 10¹⁵ molec cm⁻² year⁻¹ (R ² = 0.97, P = 0.016) from 2011 to 2014. Since 2011, tropospheric NO₂ VCDs over central-east China decrease remarkably. Tropospheric NO₂ VCDs is higher in November (3.630 × 10¹⁵ molec/cm²), December (4.758 × 10¹⁵ molec/cm²), and January (4.863 × 10¹⁵ molec/cm²), while lower in July (1.684 × 10¹⁵ molec/cm²), August (1.627 × 10¹⁵ molec/cm²), and September (1.703 × 10¹⁵ molec/cm²), indicating that winter and spring are the most polluted seasons. Due to the huge gap in population density and industry development between western and eastern China, the spatial pattern of tropospheric NO₂ VCDs shows large west-east difference.

Present study investigates the coagulation ability of Plantago ovata (P. ovata) seed extracts for turbidity removal. The active coagulant agents were successfully extracted from P. ovata seeds using different solvents such as distilled water (PO-DW), tap water (PO-TW), NaCl (PO-NaCl), and ammonium acetate (PO-AA). Experiments were conducted in batch mode for initial turbidity such as 500 NTU (high), 150 NTU (medium), and 50 NTU (low). Results demonstrated that P. ovata extracts are less efficient in low turbidities, while PO-NaCl was found to provide high coagulation activity in all initial turbidity concentrations compared to other extracts. PO-NaCl was able to remove 98.2, 94.9, and 80.2% of turbidity from water having in initial turbidities of 500, 150, and 50 NTU, respectively. Coagulation activity of the extract was the best when the extraction was performed for 50 min at room temperature. Jar test procedure with the coagulation time of 1 min and flocculation time of 30 min was optimized, irrespective of the initial turbidity. The optimum settling time for 500, 150, and 50 NTU water samples were 20, 30, and 90 min, respectively. PO-NaCl was used in different pH turbid solutions and it was found to be working very efficiently in alkaline conditions. The coagulation efficiency of the coagulant stored in refrigerator was higher than that stored at room temperature. Thus, the natural coagulants extracted from P. ovata seeds revealed to be effective for turbidity removal.

In this study, in-house isolated laccase isoforms, i.e., Lac-I and Lac-II of the basidiomycete Pycnoporus sanguineus (CS43), were evaluated in relation to their Remazol Brilliant Blue R (RBBR) dye degradation capacity. A modified Dhouib medium additionally supplemented with 3% ethanol as a secondary inducer was used to propagate P. sanguineus CS43 for enhanced production of laccase under liquid state fermentation. The crude laccase extract was purified by passing through ion exchange diethylaminoethanol (DEAE)-Sepharose and gel filtration-based Sephadex G-200 column chromatography. The purified laccase fractions were subjected to the electrophoresis, and sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis revealed two laccase isoforms Lac-I and Lac-II with 66 and 68 kDa, respectively. To explore the industrial applicability, for RBBR dye, degradation efficiencies ranged from 82 to 88% after 3 h of incubation for both; Lac-I and Lac-II at both concentrations were recorded. However, with 8 U/mL, the degradation ranged between 70 to 80% during the first 5 min of incubation. Enhanced degradation of RBBR dye was obtained in the presence of violuric acid and N-hydroxypthalamide as laccase mediators. Finally, using RBBR as a substrate kinetic characterization of both Lac-I and Lac-II isoforms was performed that revealed K ₘ (0.243 and 0.117 mM for Lac-I and Lac-II) and V ₘₐₓ (1.233 and 1.012 mM/Sec for Lac-I and Lac-II) values, respectively.

This study sought to analyze the effects of the herbicide quinclorac on body condition indices; plasma levels of corticosterone, glucose, and uric acid; activity of the antioxidant enzymes superoxide dismutase (SOD), catalase (CAT), and glutathione S-transferase (GST); and levels of lipid peroxidation (LPO) in the liver and caudal muscle of American bullfrog (Rana catesbeiana) tadpoles. After a 7-day acclimation period, animals were exposed to four concentrations (0.05, 0.1, 0.2, and 0.4 μg/L) of herbicide for a further 7 days. Then, blood samples were obtained, animals were euthanized, and the liver and caudal muscle resected. Levels of corticosterone and uric acid were reduced in tadpoles exposed to the highest concentration of herbicide, and this reduction was preceded by an increase in glucose levels. In the liver tissue, LPO was increased after exposure to 0.1 μg/L quinclorac, followed by a return to baseline values in the remaining concentrations; this response was accompanied by an increase in SOD and GST and reduction of tissue protein levels. At the highest concentration, a reduction in activity of all enzymes was observed, with protein returning to control-like levels. In muscle, SOD and GST levels declined with exposures up to 0.1 g/L and 0.4 μg/L, respectively, whereas LPO decreased in animals exposed to 0.1 μg/L. These results suggest participation of nonenzymatic antioxidant defenses, as demonstrated by the reduction in uric acid levels. Exposure to the range of quinclorac concentrations used in this study slowed body mass and length gain, reduced corticosterone levels, and modulated antioxidant defenses. Graphical abstract ᅟ