International audience

International audience | In comparison with northern countries, limited data are available on the occurrence and potential toxicity of cyanobacterial blooms in lakes and ponds in sub-Saharan countries. With the aim of enhancing our knowledge on cyanobacteria and their toxins in Africa, we performed a 17-month monitoring of a freshwater ecosystem, Lagoon Aghien (Ivory Coast), which is used for multiple practices by riverine populations and for drinking water production in Abidjan city. The richness and diversity of the cyanobacterial community were high and displayed few variations during the entire survey. The monthly average abundances ranged from 4.1 × 10 4 to 1.8 × 10 5 cell mL −1 , with higher abundances recorded during the dry seasons. Among the five cyanotoxin families analyzed (anatoxin-a, cylindrospermopsin, homoanatoxin, microcystins, saxitoxin), only microcystins (MC) were detected with concentrations ranging from 0 to 0.364 μg L −1 in phytoplankton cells, from 32 to 1092 μg fresh weight (FW) kg −1 in fish intestines, and from 33 to 383 μg FW kg −1 in fish livers. Even if the MC concentrations in water and fish are low, usually below the thresholds defined in WHO guidelines, these data raise the issue of the relevance of these WHO guidelines for sub-Saharan Africa, where local populations are exposed throughout the year to these toxins in multiple ways.

The increasing occurrence of micropollutants in natural water bodies has medium to long-term effects on both aquatic life and human health. The aim of this study is to optimize the degradation of two pharmaceutical pollutants of emerging concern: amoxicillin and acetaminophen in aqueous solution at laboratory and pilot scale, by solar photo-Fenton process carried out at neutral pH using ethylenediamine-N,N′-disuccinic acid (EDDS) as a complexing agent to maintain iron in solution. The initial concentration of each compound was set at 1 mg/L dissolved in a simulated effluent from a municipal wastewater treatment plant (MWTP). A factorial experimental design and its surface response analysis were used to optimize the operating parameters to achieve the highest initial degradation rate of each target. The evolution of the degradation process was measured by ultra-performance liquid chromatography (UPLC/UV), obtaining elimination rates above 90% for both contaminants. Statistical study showed the optimum concentrations of Fe(III) at 3 mg/L at an Fe-EDDS ratio of 1:2 and 2.75 mg/L H2O2 for the almost complete removal of the target compounds by solar photo-Fenton process. Validation of the experimental design was successfully carried out with actual MWTP effluent spiked with 100 μg/L of amoxicillin and acetaminophen, each at pilot plant scale.

People spend more than 90% of their time in indoor spaces, and, therefore, exposure to pollutants is high when inhabiting infrastructures with poor air quality. The pollutants present inside a building come either from inside the building itself (inhabitants, activity developed, etc), or from the outside (traffic, nearby industrial activity, etc). Among air cleaning techniques, building materials that incorporate a photocatalyst are considered to be a promising alternative. Photocatalysis is an Advanced Oxidation Process consisting of the oxidation/mineralization of pollutants in contact with a photocatalytic surface and the presence of UVA and sunlight irradiation. In this work, a photocatalytic paint based on TiO2 and active under indoor illumination conditions (ProCleanAir®, by PROQUICESA S.L.) was tested in a lecture room, evaluating the concentration of NO2 monitored by Palmes passive samplers. There was a decrease in the concentration of pollution after the application of the paint, with the depolluting effect remaining for one year, but also being dependent on atmospheric conditions. The statistical significance of the results was confirmed by t-student analyses.

Monitoring the abundance and characteristics of microplastics in estuarine waters is crucial for understanding the fate of microplastics at the land-sea continuum, and for developing policies and legislation to mitigate associated risks. However, if protocols to monitor microplastic pollution in ocean waters or beach sediments are well established, they may not be adequate for estuarine environments, due to the complex 3D hydrodynamics. In this note, we review and discuss sampling methods and strategies in relation to the main environmental forcing, estuarine hydrodynamics, and their spatio-temporal scales of variability. We propose recommendations about when, where and how to sample microplastics to capture the most representative picture of microplastic pollution. This note opens discussions on the urgent need for standardized methods and protocols to routinely monitor microplastics in estuaries which should, at the same time, be easily adaptable to the different systems to ensure consistency and comparability of data across different studies.

In aquatic ecosystems, microalgae are exposed to light fluctuations at different frequencies due to daily and seasonal changes. Although concentrations of herbicides are lower in Arctic than in temperate regions, atrazine and simazine, are increasingly found in northern aquatic systems because of long-distance aerial dispersal of widespread applications in the south and antifouling biocides used on ships. The toxic effects of atrazine on temperate microalgae are well documented, but very little is known about their effects on Arctic marine microalgae in relation to their temperate counterparts after light adaptation to variable light intensities. We therefore investigated the impacts of atrazine and simazine on photosynthetic activity, PSII energy fluxes, pigment content, photoprotective ability (NPQ), and reactive oxygen species (ROS) content under three light intensities. The goal was to better understand differences in physiological responses to light fluctuations between Arctic and temperate microalgae and to determine how these different characteristics affect their responses to herbicides. The Arctic diatom Chaetoceros showed stronger light adaptation capacity than the Arctic green algae Micromonas. Atrazine and simazine inhibited the growth and photosynthetic electron transport, affected the pigment content, and disturbed the energy balance between light absorption and utilization. As a result, during high light adaptation and in the presence of herbicides, photoprotective pigments were synthesized and NPQ was highly activated. Nevertheless, these protective responses were insufficient to prevent oxidative damage caused by herbicides in both species from both regions, but at different extent depending on the species. Our study demonstrates that light is important in regulating herbicide toxicity in both Arctic and temperate microalgal strains. Moreover, eco-physiological differences in light responses are likely to support changes in the algal community, especially as the Arctic ocean becomes more polluted and bright with continued human impacts.

Few studies exist on bioaccumulation and internal distribution of Rare Earth Elements (REEs) in marine fishes. REEs organotropism was determined in common sole (Solea solea) from the West Gironde Mud Patch (WGMP; N-E Atlantic Coast, France). The highest REEs concentrations occurred in liver (213 ± 49.8 µg kg-1 DW) and gills (119 ± 77.5 µg kg-1 DW) followed by kidneys (57.7 ± 25.5 µg kg-1 DW), whereas the lowest levels were in muscles (4.38 ± 1.20 µg kg-1 DW) of Solea solea. No significant age- or sex-related differences were observed. The organotropism varied among groups of REEs. Light and heavy REEs preferentially accumulated in liver and gills, respectively. All considered organs showed different normalized REEs patterns, suggesting differences in internal distribution processes between organs. Further work should address: (1) baseline levels worldwide, and (2) factors controlling uptake and organ-specific bioaccumulation of REEs.

Vast quantities of debris are beaching at remote islands in the western Indian Ocean. We carry out marine dispersal simulations incorporating currents, waves, winds, beaching, and sinking, for both terrestrial and marine sources of debris, to predict where this debris comes from. Our results show that most terrestrial debris beaching at these remote western Indian Ocean islands drifts from Indonesia, India, and Sri Lanka. Debris associated with fisheries and shipping also poses a major risk. Debris accumulation at Seychelles is likely seasonal, peaking during February–April. This pattern is driven by monsoonal winds and may be amplified during positive Indian Ocean Dipole and El-Niño events. Our results underline the vulnerability of small island states to marine plastic pollution, and are a crucial step towards improved management of the issue. The trajectories used in this study are available for download, and our analyses can be rerun under different parameter choices.