This work evaluates the degradation of benzoic acid, a tracer from biomass burning, by different oxidation agents (Fe (III); H₂O₂; sunlight; and combinations of the previous ones) in model solutions and in real atmospheric waters. The extent of reactions was assessed by Ultraviolet–Visible and molecular fluorescence spectroscopies. The oxidation of benzoic acid occurred with the chemical oxidants Fe (III), H₂O₂, Fe (III) and H₂O₂ simultaneously in the presence of sunlight, and with Fe (III) and H₂O₂ simultaneously in the absence of light. The decrease of the pH value from neutral to acid for atmospheric waters generally increased the extent of oxidation. Sunlight was an important oxidation agent, and its combination with chemical oxidants increased the oxidation rate of benzoic acid, possibly due to the photogeneration of hydroxyl radicals. The results also suggested the occurrence of direct and indirect photolysis of benzoic acid in atmospheric waters. Moreover, the oxidation of benzoic acid produced new and more complex chromophoric compounds, which were then degraded. In addition, the nocturnal period is not sufficient for the full degradation of benzoic acid and of the intermediates formed by Fenton-like oxidation. The diurnal period may be enough for their full degradation through photo-Fenton-like oxidation, but this depends on the composition of the atmospheric waters, namely of the chromophoric content. Thus, this study highlights that benzoic acid from biomass burning, and its derivatives, may persist in atmospheric waters for periods of longer than one day, becoming available for other reactions, and may also affect the terrestrial and aquatic ecosystems through the wet depositions.

Atmospheric particulate matter (PM) pollution levels and human health risks resulting from exposure to non-anthropogenic pollution sources, such as coal mine-fires, are serious global issues. The toxicity of PM₁₀-bound metals and polycyclic aromatic hydrocarbons (PAHs) was assessed according to their non-cancer and cancer risks (CRs) at the mine-fire and in an adjacent city area. Health risks were estimated for inhalation, ingestion, and dermal absorption pathways. The non-cancer risks, presented in terms of the hazard index (HI) and hazard quotient (HQ), were found to be significant (>1) at all locations, except in the mining (for HQ-dermal) and city background area (for HQ-ingestion and HQ-dermal) in children and adults, respectively. The total CR was estimated to be highest at the city nearby the mine-fire area (3.31E-02 and 1.93E-02) followed by the mine-fire area (2.66E-02 and 1.71E-02) for children and adults, respectively. The total CR and CR via individual exposure routes were estimated to be in the high risk (10⁻³ ≤ CR < 10⁻¹) category at the mine-fire site and adjacent city area. For all exposures, CR levels were calculated to be higher than the acceptable range (from 1.00E-06 to 1.00E-04), except for the CR-inhalation level at the A5 location. Among all elements, Cd and BaPₑqᵤ were more significant for the CR at the coal mine-fire and the adjacent city area. Hence, this study concluded that non-anthropogenic sources, such as coal mine-fires, could be part for the significant health risk (carcinogenic and non-carcinogenic) levels in the study area.

Soil and sludge are important pools for microplastics (MPs), however standard separation methods for MPs from these pools are still missing. We tested the widely used methods for MPs extraction from water and sediment to six agriculture surface soils and three sewage sludges from municipal wastewater treatment plants and included an additional pre-digestion procedure with 30% H₂O₂ before floatation to remove soil or sludge organic matter (OM). Extraction efficiency of MPs were evaluated under different separation conditions, including floatation solution (NaCl, ZnCl₂, and NaI), filtration membrane, and oxidation solution. Results showed that H₂O₂ pre-digestion significantly increased MPs extraction in soil and sludge, especially the samples with high OM contents, particularly sludge. Floatation solution with higher densities recovered more MPs. The extra released MPs were mainly small fibrous MPs, probably because they are easily retained by aggregates. Our results provide an feasible separation method for MPs in soil and sludge, i.e., pre-digestion with 30% H₂O₂ at 70 °C, floatation with NaI solution, filtration through nylon membrane, and further oxidation with 30% H₂O₂ + H₂SO₄ or 30% H₂O₂ at 70 °C. About 420–1290 MP items/kg soil were detected in soil samples, while much higher numbers (5553–13460 MP items/kg) were found in sludge samples. The dominate morphology of MPs was white fiber with a size of 0.02–0.25 mm, while the main types of MPs, identified by a micro-Fourier transformed infrared spectroscopy (μ-FTIR), were polyethylene and polypropylene in soil samples and polyethylene, polyethylene terephthalate, and polyacrylonitrile in sludge samples.

Measurements of biological responses on living organisms are essential in aquatic biomonitoring. In freshwaters, Dreissena polymorpha is an invasive bivalve commonly used in ecotoxicological studies and considered as a model organism. However, D. polymorpha abundances are declining while another species colonizes most of the freshwaters: Dreissena rostriformis bugensis. This species has already been studied in ecophysiology but there is still a lack of data concerning its responses to stressors before its use as a bioindicator of environmental pollution. This study aims to compare the responses of the two species exposed to metal stress. Responses at different levels of biological organization were targeted with measurement of sub-cellular and individual biomarkers following an exposure of up to 7 days to cadmium at 10 μg.L−1. At the individual level, the scope for growth (SFG) was measured. It corresponds to the energy allocated to growth and reproduction. D. polymorpha exhibits variations in biomarker measurements as well as in the SFG in presence of Cd. D. r. bugensis shows no variation in its responses at the different targeted levels. According to the present results, energy metabolism seems to have an essential role for these species when facing a metal stress. Different energy allocation strategies were evidenced between the two species, although the link with biochemical biomarkers is more evident for D. polymorpha than for D. r. bugensis.

Nowadays Cylindrospermopsis raciborskii (C. raciborskii) and the metabolites produced, such as cylindrospermopsin (CYN), pose a serious threat to the ecosystem. Advanced oxidation technologies have been verified as constituting a very promising means to eliminate the risk from harmful algae. But so far little research has focused on the visible-light photocatalytic destruction of C. raciborskii cells and the degradation of their metabolites.In our study, N-doped TiO2 (N-TiO2) was used to degrade C. raciborskii and the degradation was compared with that of the Microcystis aeruginosa (M. aeruginosa). Results showed that although the photodegradation of C. raciborskii was more difficult than that of M. aeruginosa, the treatment with N-TiO2 was still satisfactory. After adding 200 mg/L N-TiO2, C. raciborskii cells (5 × 106 cells/mL) were completely destroyed within 20 h under visible light irradiation, and nearly 90% of the organic matter and CYN in the suspensions were also degraded, thereby markedly improving the water quality.The photocatalytic process starts with damage to the cell membrane resulting in the leakage of internal components. Subsequently, the leaked metabolites were oxidised by the reactive oxidizing species produced by N-TiO2. Thus, the application of N-TiO2 is a promising method for the treatment of C. raciborskii.

However the physiological stress in aquatic organisms associated with hydropower plants (HPP) ecosystems has been previously investigated, no studies have so far assessed it on biochemical level. Therefore this study evaluated an oxidative stress and toxicity in the gibel carp Carassius auratus gibelio associated with a small-scale HPP in the West Ukraine. A battery of liver, brain and blood markers was evaluated individuals inhabiting upstream and downstream of the dam of the small-scale Kasperivtci HPP (KHPP; an installed capacity of 7.5 MW), and from a reference site. Number of alterations were noted in fish from the KHPP impoundment facility including signs of oxidative stress (a decrease in superoxide dismutase (SOD) activity and an increase in protein carbonyls) and cytotoxicity (an increase in micronucleated erythrocytes and caspase-3 activity). No changes in DNA fragmentation in hepatocytes or brain cholinesterase activity were detected. As demonstrated by the integral stress index, fish associated with downstream of the dam revealed the greatest alterations reflected by the combined oppression of antioxidant system (SOD, catalase) and pro-oxidants (thiobarbituric acid reactive substances and oxyradicals), low concentration of metallothioneins, but high cathepsin D activity (as markers of lysosomal dysfunction and autophagy) and increased vitellogenin concentration in males (indicating an endocrine disruption). The study highlights that fish inhabiting ecosystems associated with HPP, particularly downstream of the dam, may face additional stresses with long-term effects yet to be evaluated.

A recent data set for 22 poly- and per-fluorinated compounds (PFASs) in Ponar grab samples of surface sediments and cores from the Great Lakes of North America was examined for concentrations, loads, correlations with geographical coordinates and depth (time), and for sources. Correlations were determined by multivariate regression analyses. Source apportionment of PFASs was carried out by positive matrix factorization (PMF) for two cores from Lake Ontario. For the five lakes together, the total load of PFASs in sediments was estimated to be 245 ± 24 tonnes, which is about half the load for total PCBs. The recent annual loading was 1812 ± 320 kg/yr. Concentrations and inventories of PFASs were greatest in Lakes Erie and Ontario. Since 1947, concentrations of perfluorooctane sulfonic acid (PFOS) in ten cores have increased exponentially as a function of time with doubling times between 10 and 54 yr and have leveled off in three cores since 2000. PMF demonstrated an effective grouping of two particle-associated factors, characterized mainly by longer-chain PFASs (C ≥ 8) and two other factors of mainly shorter-chain compounds (C ≤ 6). Two factors feature only one dominant compound: factor 1, PFOS, and factor 3, perfluorobutane sulfonic acid (PFBS). Of all factors, factor 3 with PFBS has the largest contribution (47.8%). Significant scores for perfluorohexane sulfonic acid (PFHxS) and PFBS, along with flat or decreasing PFOS contributions since 2003, indicate that the replacement of PFOS with these compounds is beginning to take effect in the environment.

The removal of particulate matter (PM) is an important issue in public health and the global atmospheric environment. Various PM removal methods have been suggested to effectively remove PM particles. However, the effects of various factors on PM deposition are not completely clear. We quantitatively investigated the effects of flow and humidity difference in a closed chamber on PM deposition. To elucidate the parameters affecting the deposition of PM particles, PM removal efficiency and deposition constant were examined at different flow rates, flow directions, and relative humidity (RH) inside the closed system. The highest PM deposition rate was achieved under humid condition with the upward direction flow at a fan speed of RPM = 150. Mean velocity fields inside the test chamber were obtained by a particle image velocimetry (PIV) technique to quantitatively examine the effect of flow conditions on the PM deposition. The flow structure and RH inside the closed chamber have significant influence on PM deposition.

Microplastics are an emerging pollutant of high concern, with their prevalence in the environment linked to adverse impacts on aquatic organisms. However, our knowledge of these impacts on freshwater species is rudimentary, and there is almost no research directly testing how these effects can change under ongoing and future climate warming. Given the potential for multiple stressors to interact in nature, research on the combined impacts of microplastics and environmental temperature requires urgent attention. Thus, we experimentally manipulated environmentally realistic concentrations of microplastics and temperature to partition their independent and combined impacts on metabolic and feeding rates of a model freshwater detritivore. There was a significant increase in metabolic and feeding rates with increasing body mass and temperature, in line with metabolic and foraging theory. Experimental warming altered the effect of microplastics on metabolic rate, which increased with microplastic concentration at the lowest temperature, but decreased at the higher temperatures. The microplastics had no effect on the amount of litter consumed by the detritivores, therefore, did not result in altered feeding rates. These results show that the metabolism of important freshwater detritivores could be altered by short-term exposure to microplastics, with greater inhibition of metabolic rates at higher temperatures. The consequences of these metabolic changes may take longer to manifest than the duration of our experiments, requiring further investigation. Our results suggest little short-term impact of microplastics on litter breakdown by gammarid amphipods and highlight the importance of environmental context for a better understanding of microplastic pollution in freshwater ecosystems.

In this study, we present the development of a mobile system to measure real-world total respiratory tract deposition of inhaled ambient black carbon (BC). Such information can be used to supplement the existing knowledge on air pollution-related health effects, especially in the regions where the use of standard methods and intricate instrumentation is limited. The study is divided in two parts. Firstly, we present the design of portable system and methodology to evaluate the exhaled air BC content. We demonstrate that under real-world conditions, the proposed system exhibit negligible particle losses, and can additionally be used to determine the minute ventilation. Secondly, exemplary experimental data from the system is presented. A feasibility study was conducted in the city of La Paz, Bolivia. In a pilot experiment, we found that the cumulative total respiratory tract deposition dose over 1-h commuting trip would result in approximately 2.6 μg of BC. This is up to 5 times lower than the values obtained from conjectural approach (e.g. using physical parameters from previously reported worksheets). Measured total respiratory tract deposited BC fraction varied from 39% to 48% during walking and commuting inside a micro-bus, respectively.To the best of our knowledge, no studies focusing on experimental determination of real-world deposition dose of BC have been performed in developing regions. This can be especially important because the BC mass concentration is significant and determines a large fraction of particle mass concentration. In this work, we propose a potential method, recommendations, as well as the limitations in establishing an easy and relatively cheap way to estimate the respiratory tract deposition of BC.