The comparison of two methods in calculating transboundary concentrations of NO₂ and PM₁₀ using CMAQ chemical transport model is presented. The total mean annual concentrations for the pollutants were computed from the hourly outputs of the CMAQ model. The first method for calculating the transboundary concentrations is based on switching off the emissions from the studied country, while the remaining emissions are the same as in the full model run. The second method is based on running the model with the emissions from the studied country only. The resulting concentrations are then subtracted from the full model run concentrations. The result of this subtraction represents the transboundary air pollution together with pollution originating from the interaction of national and foreign sources. The pollution which cannot be attributed unambiguously to national or foreign sources is caused by the non-linear processes included in the model. It is evaluated as the difference between the two methods. It is shown that the non-linearity effect is more expressed for PM₁₀ than for NO₂ annual mean concentrations. It is estimated that the non-linearity effect for PM₁₀ can reach values up to 2.7 μg/m3 in absolute value, or up to 16% of the total annual mean concentrations and up to 25% of the total estimated transboundary concentrations in the studied area. It is also demonstrated that this non-linearity effect is more important for both pollutants during some episodes than in the annual mean. The method of removing the bias from the calculated transboundary concentrations is presented, together with the proposed method of evaluation of the uncertainties of the transboundary concentration calculations. The estimated transboundary contribution is evaluated at the locations of Slovak air-quality monitoring stations. The impact of several emission reduction levels on the estimation of the transboundary contribution is also presented. The simulations are performed for the reference year of 2015 for Slovakia, but the proposed methods can by applied universally.

The daily concentrations of 15 polycyclic aromatic hydrocarbons (PAHs) in PM₁ aerosol samples, including 7 carcinogenic PAHs, were determined in six urban/rural areas in the Czech Republic in winter seasons between 2013 and 2017. The PM₁ aerosol was collected on quartz fibre filters using high-volume samplers for 24 h and PAHs were analysed by GC-MS. The highest concentrations of PAHs were found in the industrial city Ostrava (60.8 ng m⁻³), which is one of the most polluted areas in the Czech Republic, while the lowest concentrations were obtained in the small town Čelákovice (11.7 ng m⁻³) and in the background rural area Košetice (12.3 ng m⁻³). Carcinogenic PAHs formed 43.9%–57.8% of total analysed PAHs.The toxic equivalence factors for individual PAHs adopted from literature and two unit risks (Cal-EPA and WHO) were used for the evaluation of carcinogenic risk of PAHs exposure. The inhalation cancer risk models assume a lifetime exposure (70 years), whereas our measurement was realized for a relatively short duration in winters where concentrations of PAHs are usually high. The average of PAHs concentrations will be lower for the whole year resulting in lower lung cancer risk values. The calculated lifetime lung cancer risk of PAHs exposure for the measured winter periods suggested 1545 cases per 1 million people in Ostrava (industrial area), 192–456 cases per 1 million people in other four investigated cities/towns and 182 cases per 1 million people in Košetice (rural area). The calculated lifetime lung cancer risk values are related only to ambient concentrations of PAHs in atmospheric aerosols. Nevertheless, other factors can influence and increase the lung cancer risk, e.g., occupation, smoking, indoor emissions of coal/wood combustion in stoves or genetic factors of individuals. Our results can also be underestimated due to the determination of PAHs only in PM₁ aerosol.

In the brackish water Baltic Sea, oil pollution is an ever-present and significant environmental threat mainly due to the continuously increasing volume of oil transport in the area. In this study, effects of exposure to crude oil on two common Baltic Sea species, the mussel Mytilus trossulus and the amphipod Gammarus oceanicus, were investigated. The species were exposed for various time periods (M. trossulus 4, 7, and 14 days, G. oceanicus 4 and 11 days) to three oil concentrations (0.003, 0.04, and 0.30 mg L−1 based on water measurements, nominally aimed at 0.015, 0.120, and 0.750 mg L−1) obtained by mechanical dispersion (oil droplets). Biological effects of oil exposure were examined using a battery of biomarkers consisting of enzymes of the antioxidant defense system (ADS), lipid peroxidation, phase II detoxification (glutathione S-transferase), neurotoxicity (acetylcholinesterase inhibition), and geno- and cytotoxicity (micronuclei and other nuclear deformities). In mussels, the results on biomarker responses were examined in connection with data on the tissue accumulation of polycyclic aromatic hydrocarbons (PAH). In M. trossulus, during the first 4 days of exposure the accumulation of all PAHs in the two highest exposure concentrations was high and was thereafter reduced significantly. Significant increase in ADS responses was observed in M. trossulus at 4 and 7 days of exposure. At day 14, significantly elevated levels of geno- and cytotoxicity were detected in mussels. In G. oceanicus, the ADS responses followed a similar pattern to those recorded in M. trossulus at day 4; however, in G. oceanicus, the elevated ADS response was still maintained at day 11. Conclusively, the results obtained show marked biomarker responses in both study species under conceivable, environmentally realistic oil-in-seawater concentrations during an oil spill, and in mussels, they are related to the observed tissue accumulation of oil-derived compounds.

International audience

FeMnMg-LDH with hydrotalcite-like structure was synthesized via a coprecipitation method and applied to copper ion removal from aqueous solution. FT-IR, SEM, PXRD, TEM, and XPS were applied to characterization analysis. Factors like temperature, pH, contact time, initial concentration, and coexisting cations were systematically studied. FeMnMg-LDH has an excellent performance on copper adsorption, with a maximum capacity of 204.07 mg/g at 25 °C, which is much higher than that of most other similar LDHs. The effects of coexisting cations on the removal efficiency of copper ions are various and following the order of Zn²⁺ > Pb²⁺ > Mg²⁺ > Ca²⁺, which may be due to the solubility of their hydroxides. The result of adsorption thermodynamics indicates that the adsorption process is endothermic and spontaneous. The adsorption kinetics are in accord with the pseudo-second-order kinetic model, and particles that appear in the SEM figures are both suggesting that chemical complex formed during the adsorption process. Meanwhile, the result of DKR model fitting indicates that the isomorphic substitution mechanism is involved in the adsorption process. Thus, the main adsorption mechanisms of FeMnMg-LDH in the removal of Cu²⁺ from aqueous solution in this study are isomorphic substitution and surface-induced precipitation. Graphical abstract

The sediment acts as not only sink but also source of heavy metals in aquatic environment, which may cause the endogenous pollution in drinking water reservoirs. In this work, we collected the surface sediments from Qingcaosha Reservoir, the largest river-embedded reservoir in China, and investigated the spatial distribution, risk, and sources of heavy metals in four seasons. Significant spatial and seasonal heterogeneity could be found in the distribution of five heavy metals (Cr, Cu, Mn, Zn, and Ni) in the surface sediments. The highest concentrations of the five metals were detected in the sediments from the reservoir downstream, especially in summer and next spring. The geo-accumulation index (Igₑₒ) and enrichment factor (EF) suggest that the sediment pollution caused by single metal was heavier in summer than in other seasons. Also, the Nemerow pollution index (PIN) manifests that the synergetic pollution induced by five metals was most serious in summer, followed by next spring. However, the potential ecological risk index (PERI) indicates that none of these metals caused potential ecological risk in four seasons. Comprehensive analysis demonstrates that the sediment pollution gradually increased from autumn to winter and then to next spring. Principal component analysis shows that the main pollution source of five heavy metals may come from industrial wastewater and domestic sewage, which was almost independent of seasons. This work can provide data support for the subsequent seasonal optimization of drinking water quality and reservoir management.

Since 2016, the impact of the best available techniques (BAT) on air quality in Bor is significant. Its performance is presented by the air quality assessment with respect to the average annual sulfur dioxide (SO₂) emitted concentrations and the total SO₂ volume emitted per year from the smelter and sulfuric acid plant, relative to the quantity of processed concentrate in the period when production was conducted with the old technology, in 2013.Air quality in Bor was categorized as category III, i.e., the air was heavily polluted due to the exceeded tolerance of SO₂ values. In the agglomeration Bor, during 2016/2017, air was of the category I, i.e., clean or slightly polluted air.The data illustrated that the temporal (yearly) variation of SO₂ concentration was more influenced by human-related factors, especially by secondary industry share, as SO₂ is mainly produced and discharged in the process of industrial production. The spatial variation of such concentration was more affected by meteorological indicators, especially by wind direction.In the period of the new technology, a significantly greater volume of concentrate was processed and a considerably larger quantity of cathode copper produced, and at the same time, total volume of emitted SO₂ and measured heavy metals (lead-Pb, arsenic-As, cadmium-Cd, and nickel-Ni) was substantially reduced.

Nickel-contaminated soil was treated by adding different amounts of calcium oxide in this study. The leaching concentration, pH, and bioavailability of the soil samples were investigated on the 3rd, 6th, 9th, 12th, and 15th days. The chemical speciation changes of the contaminated soil treated with calcium oxide were analyzed, and the soil phases were analyzed by X-ray diffraction (XRD). Results showed that the application of calcium oxide increased the pH of the soil, resulting in passivation of nickel ions in soil by forming a poorly soluble precipitate. It was identified that addition of 5% of calcium oxide showed the best result, with the leaching concentration on the third day reaching 0.35 mg/L, which is 99.21% lower than the untreated soil’s leaching concentration of 44.24 mg/L. On the 15th day, the bioavailability of nickel decreased from the untreated soil’s 93.82 to 36.73%. It was also observed that the pH of the soil increased at the beginning and decreased afterwards. The pH value was 7.94 on the 15th day. In addition, the water-soluble fraction of Ni decreased from 7.39 without treatment to 0.19%; the reducible fraction of Ni decreased from 35.14 to 25.79%, and the oxidizable fraction of Ni increased from 10.37 to 29.10%, respectively, on the 15th day after the treatment with calcium oxide. XRD analysis of soil samples showed the amorphous nickel hydroxide may be formed in the precipitation process.

The ecosystems near arsenic mining industrial areas are characterized with an elevated level of pollutants. In Caucasus region, such a hotspot is presented in Western Georgia: Uravi and Tsana abandoned arsenic production facilities and nearby mining tailings stored in deteriorating conditions that pose a threat to the population. The research presents a study of the local bacteria community of highly arsenic-contaminated soils (from 400 mg/kg at Uravi arsenic sulfide mineral processing facility to 11.3 g/kg at arsenic oxide storage area in Tsana) using an innovative, multitasking microscale bioanalytical method for environmental enquiries – DNA biochip (microarray). The detected Shewanella spp., Bacillus spp., and sulfate-reducing bacteria were considered as promising objects for future projects on in situ recovery of vast arsenic-contaminated areas applying remediation methods.

The study reports the preservative efficacy of Bunium persicum (Boiss) essential oil (BPEO) against fungal and aflatoxin B₁ (AFB₁) contamination of stored masticatories and boosting of its efficacy through encapsulation into chitosan. BPEO was chemically characterized through GC-MS analysis, which revealed γ-terpinene as the major compound. The BPEO at 1.2 μL/mL concentration completely inhibited the growth of toxigenic strain of Aspergillus flavus (AF-LHP-PE-4) along with 15 common food borne moulds and AFB₁ secretion. The BPEO exerts its antifungal action on plasma membrane, as confirmed through ergosterol inhibition, alteration of membrane fluidity and enhancement of cellular ions and 260 and 280 nm absorbing material leakage. The antiaflatoxigenic mechanism of action of BPEO was confirmed through methylglyoxal reduction. Further, BPEO showed strong antioxidant activity (IC₅₀ = 7.36 μL/mL) as measured by DPPH· assay. During in situ investigation, BPEO completely inhibited AFB₁ production in model food (Phyllanthus emblica) system without altering the sensory properties and also exhibited high LD₅₀ value (14,584.54 μL/kg) on mice. In addition, BPEO was encapsulated into chitosan, characterized and tested for their potential to inhibit growth and AFB₁ production. The mean particle size, PDI and zeta potential of formed BPEO-loaded chitosan nanoparticle (CS-Np-BPEO) were performed to confirm successful encapsulation. The result revealed nanoencapsulated BPEO showed enhanced activity and completely inhibited the growth and AFB₁ production by AF-LHP-PE-4 at 0.8 μL/mL. Based on findings, it could be concluded that the BPEO and its encapsulated formulation can be recommended as a potential plant-based preservative against fungal and aflatoxin contamination of stored masticatories.