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The waste generated by the global fishing industry, such as fish scales, is mostly considered useless and discarded in a disorderly and/or unplanned way in inappropriate places, posing serious risks to both the environment and human health. This study proposes the use of fish scales in combustion processes as an alternative for such residues and to avoid their exposure in urban areas. Combustion experiments were conducted in a drop tube furnace (DTF), and the factors temperature, residence time, and sample particle size were investigated. The main atmospheric pollutants (CO, NO, CO2, and SO2) and the residues generated from the combustion processes were characterized by FTIR, EDS and ICP-OES analyses, and SEM images. The samples showed better performance at 1100 °C and 500 -ms residence time, when the burnout reached 96%, and particle size greater than 300-µm and 300-ms residence time led to the worst combustion performance (24.45% burnout), with the highest CO and NO peaks, indicating incomplete combustion of the fish scales. The analysis of the residues revealed total decomposition of the organic matter at temperatures above 700 °C and formation of hydroxyapatite. According to the DTF results, the use of fish scales in firing processes is a viable treatment of the residues, generating energy and avoiding environmental problems caused by inadequate disposal.

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RESUMO No presente trabalho foi realizada a estimativa das emissões dos gases de efeito estufa (CO2eq), monóxido de carbono (CO), óxido de nitrogênio (NOx), material particulado (MP), aldeído (RCHO) e hidrocarboneto não metano (NMHC) dos veículos licenciados nos cinco primeiro meses do ano de 2020 no Brasil. Os resultados foram comparados com as emissões veiculares da frota licenciada no mesmo período do ano de 2019 a fim de verificar o impacto da pandemia de COVID-19 nos referidos licenciamentos, nas emissões e, consequentemente, na qualidade do ar do país. Os resultados apontaram redução de 14% nas emissões dos gases de efeito estufa, com diminuição observada para todos os veículos, exceto para os caminhões semipesados, que tiveram incremento nas emissões de gases de efeito estufa de 12,8%. Os demais poluentes também reduziram, em 12,5% para o CO, em 29,6% para o NOx, em 24,1% para o MP, em 21,5% para o RCHO e em 16,3% para o NMHC. Por fim, quanto ao total de poluentes acumulados, entre todos os veículos analisados, os únicos que tiveram aumento nas emissões em relação a 2019, de 2,1%, foram as motocicletas com tecnologia flexfuel, que são abastecidas preferencialmente com etanol hidratado. Com isso, pôde-se concluir que a pandemia da COVID-19, por meio das medidas de restrição e isolamento social adotadas no país para frear a transmissão da doença, impactou positivamente a qualidade do ar no Brasil no período analisado.

ABSTRACT The estimated emissions of greenhouse gases (CO2eq), carbon monoxide (CO), nitrogen oxide (NOx), particulate matter (PM), aldehyde (RCHO) and non-methane hydrocarbon (NMHC) from vehicles licensed in the first five months of 2020 in Brazil were calculated in the present study, and the results compared with vehicular emissions from the licensed fleet in the same period of the year 2019, in order to verify the impact of the COVID-19 pandemic on these permits, emissions and, consequently, air quality in the country. The results showed a 14% reduction in greenhouse gas emissions, with a decrease observed for all vehicles, except for semi heavy trucks, which had a 12.8% increase in GHG emissions. The other pollutants also decreased, being 12.5% for CO, 29.6% for NOx, 24.1% for PM, 21.5% for RCHO, and 16.3% for NMHC. Finally, in relation to the total accumulated pollutants, among all vehicles analyzed, the only ones that had a 2.1% increase in emissions in relation to 2019 were the motorcycles with flexfuel technology, which are preferably fueled with hydrated ethanol. Thus, it was concluded that the COVID-19 pandemic, through the measures of restriction and social isolation adopted in the country to curb the transmission of the disease, had a positive impact on air quality in Brazil during the analyzed period.

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Meteorology and long-term trends in air pollutant concentrations may obscure the results from short-term policies implemented to improve air quality. This study presents changes in CO, NO2, O3, SO2, PM10, and PM2.5 based on their anomalies during the COVID-19 partial (Phase 2) and total (Phase 3) lockdowns in Mexico City (MCMA). To minimise the impact of the air pollutant long-term trends, pollutant anomalies were calculated using as baseline truncated Fourier series, fitted with data from 2016 to 2019, and then compared with those from the lockdown. Additionally, days with stagnant conditions and heavy rain were excluded to reduce the impact of extreme weather changes. Satellite observations for NO2 and CO were used to contrast the ground-based derived results. During the lockdown Phase 2, only NO2 exhibited significant decreases (p < 0.05) of between 10 and 23% due to reductions in motor vehicle emissions. By contrast, O3 increased (p < 0.05) between 16 and 40% at the same sites where NO2 decreased. During Phase 3, significant decreases (p < 0.05) were observed for NO2 (43%), PM10 (20%), and PM2.5 (32%) in response to the total lockdown. Although O3 concentrations were lower in Phase 3 than during Phase 2, those did not decrease (p < 0.05) from the baseline at any site despite the total lockdown. SO2 decreased only during Phase 3 in a near-road environment. Satellite observations confirmed that NO2 decreased and CO stabilised during the total lockdown. Air pollutant changes during the lockdown could be overestimated between 2 and 10-fold without accounting for the influences of meteorology and long-term trends in pollutant concentrations. Air quality improved significantly during the lockdown driven by reduced NO2 and PM2.5 emissions despite increases in O3, resulting in health benefits for the MCMA population. A health assessment conducted suggested that around 588 deaths related to air pollution exposure were averted during the lockdown. Our results show that to reduce O3 within the MCMA, policies must focus on reducing VOCs emissions from non-mobile sources. The measures implemented during the COVID-19 lockdowns provide valuable information to reduce air pollution through a range of abatement strategies for emissions other than from motor vehicles.

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During the COVID-19 pandemic lockdown, emissions of primary criteria pollutants in the Mexico City Metropolitan Area (MCMA) were substantially reduced, as in many other cities in the world. Unexpectedly, the daily average ozone concentration profile was practically indistinguishable from that of the past two years for the same time span in the calendar. So, we compared surface meteorology data, CO, NOx and O3 hourly concentrations in the MCMA from the ozone season (from March 1 to May 31) for the years 2018, 2019, and 2020. Also, TROPOMI satellite data on column count of CO, NO2 and HCHO, above a sparse grid of surface points in the MCMA, were also compared for March, April, and May 2020 with those from 2019. Population density used as a background variable to increase understanding of the observed differences allowed us to propose that reductions in NOx were so drastic that ozone formation moved rapidly from a VOC sensitive region towards a NOx sensitive region. The relevance of that unplanned policy provides impacts of contingent short-term emissions control actions during very high pollution episodes. Further analysis of these and other related data concerning VOC speciation and emissions patterns during the coronavirus lockdown may provide guidelines to enhance emission control policies in the post-COVID-19 times to come.

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Technical, economic, social and environmental conditions are turning natural gas into a feasible solution for sustainable transportation systems in the State of São Paulo (Brazil). Blue Corridors are routes that aim to enable the use of liquefied natural gas (LNG) for heavy vehicles as a substitute to Diesel oil. Therefore, this work proposes four scenarios for a Blue Corridor in the State of São Paulo and analyzes its environmental and economic impacts. The results are presented in cartographical figures and show that LNG costs up to 40% less than diesel, while reducing CO2 equivalent emissions by up to 5.2%. Particulate matter (PM) emissions are reduced by 88%, nitrogen oxides (NOx) by 75% and hydrocarbon emissions are eliminated. However, despite the economic and environmental advantages presented in the results of this study, LNG still faces regulatory barriers that must be addressed in order to allow its widespread use in the transportation sector.