In rapidly expanding African cities, the ecotoxicological relevance of PM10 remains largely unresolved, especially where particle mass, chemical composition and emission sources are rarely assessed together. Here, 116 daily PM10 samples collected in Luanda between 27 June and 5 November 2023 were tested using the Microtox® Aliivibrio fischeri assay on aqueous extracts. Chemical speciation was combined with centred log-ratio (CLR) compositional clustering to identify recurring chemical regimes, while Positive Matrix Factorisation (PMF) was used to resolve the corresponding emission sources. Toxicity was moderate but highly variable: Toxic units after 15 min (TU15) ranged from 0.84 to 8.54, with changes in toxicity units between 5 and 15 min (ΔTU) varying from −1.51 to +4.84. Only 3 of the 116 samples showed TU15 < 1, and none reached TU15 ≥ 10. The strongest responses occurred under a metal-enriched chemical regime (C2), characterised by elevated Zn, Pb and Cd concentrations, which showed the highest mean TU15 (4.22) and ΔTU (1.52). This regime coincided with PMF evidence identifying non-ferrous metallurgy plus galvanised/metal scrap handling and burning as the factor most strongly associated with toxicity (ρTU15 = 0.63; ρΔTU = 0.78), followed by a Ni-rich metallurgical factor with possible aviation influence (ρTU15 = 0.51). Conversely, a marine/ionic chemical regime (C3) showed lower, stable toxicity, consistent with negative marine aerosol associations. These findings show that integrating chemical regimes with PMF-resolved sources identifies metal-related emissions as the main drivers of PM10 ecotoxicity.
Alan Victor da Silva, E. Vicente, Ana M. Sánchez de la Campa et al.· Toxics· 0 citations
Understanding more about the risks posed by hazardous pesticides is essential, particularly for ecologically and economically important species such as the Pacific oyster (Magallana gigas). Although dimethoate toxicity has been widely studied and has led to regulatory measures in certain regions, it is still used in others, such as Tunisia. Investigations on sensitive species in such contexts can provide valuable insights for better assessing and managing potential environmental risks. This study offers a novel evaluation of the toxic effects of experimental concentrations of dimethoate after a 72-h exposure period on the redox state, cholinergic system, and fatty acid composition in the gills of M. gigas oysters, as well as in terms of DNA damage on their hemocytes. Throughout the exposure period, we observed an increase in lipid and protein oxidation, along with changes in the activities of the antioxidant enzymes catalase, superoxide dismutase, and glutathione peroxidase, as well as an inhibition of the acetylcholinesterase activity in the tested oysters. Changes in fatty acid composition were detected, characterized by a decrease in saturated fatty acids and an increase in unsaturated fatty acids, particularly docosahexaenoic acid and arachidonic acid. After exposure to higher concentrations of dimethoate, genotoxic effects were observed, as evidenced by increased DNA damage in the oysters' hemolymph. Together, these biochemical and molecular alterations indicate that dimethoate exposure triggers complex physiological and behavioral adjustments in oysters when subjected to more severe stressors. These findings underscore potential threats to oyster quality and consumer safety under continued use of unregulated toxic pesticides.
D. Belhassen, Roberto Martins, S. Bejaoui et al.· Marine Pollution Bulletin· 0 citations
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