Comprehensive two-dimensional liquid chromatography (LC£LC) coupled with a diode array detector (DAD) has been used for the first time to investigate chemical heterogeneity and map the hydrophobicity versus molecular weight distribution of the most hydrophobic acid fractions in water-soluble organic matter (WSOM) from fine atmospheric aerosols collected over different seasons at a urban location. The use of LC£LC-DAD, combining the use of two independent separation mechanisms (per aqueous liquid chromatography [PALC] versus sizeexclusion chromatography [SEC]), has shown a great potential for unraveling and resolving the heterogeneity of WSOM, further providing a deeper insight into how size-distinguished aerosol WSOM fractions differ in hydrophobicity during different seasonal events. The combination of PALC£SEC-DAD data with an already proposed data treatment procedure revealed that the WSOM samples collected during warm seasons are enriched in aliphatic structures, while those collected during colder seasons exhibit a higher degree of structures with conjugation of p-bonds (e.g., aromatics) alongside aliphatic structures.
Sub‐Saharan Africa has been the last continent to experience a significant number of cases in the novel Coronavirus (COVID‐19). Studies suggest that air pollution is related to COVID‐19 mortality; poor air quality has been linked to cardiovascular, cerebrovascular, and respiratory diseases, which are considered co‐morbidities linked to COVID‐19 deaths. We examine potential connections between country‐wide COVID‐19 cases and environmental conditions in Senegal, Cabo Verde, Nigeria, Cote D'Ivorie, and Angola. We analyze PM2.5 concentrations, temperatures from cost‐effective in situ measurements, aerosol optical depth (AOD), and fire count and NO2 column values from space‐borne platforms from 1 January 2020 through 31 March 2021. Our results show that the first COVID‐19 wave in West Africa began during the wet season of 2020, followed by a second during the dry season of 2020. In Angola, the first wave starts during the biomass burning season but does not peak until November of 2020. Overall PM2.5 concentrations are the highest in Ibadan, Nigeria, and coincided with the second wave of COVID‐19 in late 2021 and early 2022. The COVID‐19 waves in Cabo Verde are not in phase with those in Senegal, Nigeria, and Cote, lagging by several months in general. Overall, the highest correlations occurred between weekly new COVID‐19 cases meteorological and air quality variables occurred in the dry season.
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