Since January 2020, studies report reductions in air pollution among several countries due to social isolation measures, which have been adopted in order to contain the coronavirus outbreak progress (COVID-19). This study aims to evaluate the change in the atmospheric pollution levels by NO and NO 2 in São Paulo City for the social isolation period. The NO and NO 2 hourly concentrations were obtained through air quality monitoring stations from CETESB, from January 14, 2020 to April 12, 2020. Mann-Kendall and the Pettitt tests were performed in the air pollutant time series. We observed an overall negative trend in all stations, indicating a decreasing temporal pattern in concentrations. Regarding NO, the highest absolute decrease rates were observed in the Congonhas (− 6.39 μg m −3 month −1 ) and Marginal Tietê (− 6.19 μg m −3 month −1 ) stations; regarding NO 2 , the highest rates were observed in the Marginal Tietê (− 4.45 μg m −3 month −1 ) and Cerqueira César (− 4.34 μg m −3 month −1 ) stations. In addition, we identified a turning point in the NO and NO 2 series trends that occurred close to the start date of the social isolation period (March 20, 2020). Moreover, from statistical analysis, it was found that NO 2 is a suitable surrogate for monitoring economic activities during social isolation periods. Thus, we concluded that social isolation measures implemented on March 20, 2020 caused significant changes in the air pollutant concentrations in the city of São Paulo (as high as − 200% in NO 2 levels).
We investigated the influence of natural and anthropogenic sources on bulk atmospheric deposition chemistry, from November 2017 until October 2019, in a Brazilian agricultural area. The pH mean value was 5.99 (5.52–8.46) and most deposition samples (~98%) were alkaline (pH > 5.60). We identified Ca2+ as the predominant species, accounting for 33% of the total ionic species distribution and the main precursor of atmospheric acidity neutralization (Neutralization Factor = 6.63). PMF analysis resulted in four factors, which demonstrated the influence of anthropogenic and natural sources, such as fertilizer application and production, marine intrusion/biomass burning, and biogenic emissions, and revealed the importance of atmospheric neutralization processes.
Since January 2020, some studies have been reporting a reduction in air pollution in several countries due to social isolation measures, which have been adopted in order to contain the coronavirus outbreak progress (Covid-19). This study aims to evaluate the change in the atmospheric pollution levels by NO and NO2 in São Paulo city in the social isolation period. The NO and NO2 hourly concentrations were obtained through air quality monitoring stations from CETESB, from January 14 to April 12, 2020. Mann-Kendall and the Pettitt tests were performed in the air pollutants time series. We observed an overall negative trend in all stations, indicating a decreasing temporal pattern in concentrations. Regarding NO, the highest decrease rates were observed in Congonhas (-6.39 µg.m-3month-1) and Marginal Tietê (-6.19 µg.m-3month-1) stations; regarding NO2, the highest rates were observed in Marginal Tietê (-4.45 µg.m-3month-1) and Cerqueira César (-4.34 µg.m-3month-1) stations. In addition, we identified a turning point in the NO and NO2 series trends that occurred close to the start date of the social isolation period (March 20, 2020). Moreover, from statistical analysis, it was found that NO2 is a suitable surrogate for monitoring economic activities during social isolation period. Thus, we concluded that social isolation measures implemented in March 20, 2020 caused significant changes in the air pollutants concentrations in São Paulo city (as high as -200% in NO2 levels).
Understanding the seasonal patterns and in uencing factors of nitrogen atmospheric deposition is essential to evaluate human impacts on the air quality and nitrogen biogeochemical cycle. However, evaluation of the nitrogen deposition ux, especially in South America agricultural regions, has not been fully investigated. In this paper, we quanti ed the atmospheric wet deposition uxes of total dissolved nitrogen (TDN), dissolved organic nitrogen (DON) and dissolved inorganic nitrogen (DIN), in a region with agricultural and livestock predominance in the Southern Minas Gerais region, Brazil, from May 2018 to April 2019. Deposition uxes of nitrogen species in the wet season (October -March) were on average 4.8 fold higher than dry season, which revealed signi cant seasonal variations driven largely by the seasonality of rainfall and agricultural operations. We also found high NO 3 − /NH 4 + ratios (average = 8.25), with higher values in dry season (NO 3 − /NH 4 + = 12.8) in comparison with wet season (NO 3 − /NH 4 + = 4.48), which revealed a higher relative contribution of NO x emissions from tra c sources in dry season. We also estimated the in uence of atmospheric deposition of inorganic nitrogen (N-DIN) on environmental ecosystems, being 2.01 kgNha − 1 yr − 1 with potential risk of acidi cation and eutrophication of 30%.Therefore, attention should be paid to the role of wet atmospheric deposition of nitrogen as a source of nitrogen environmental pollution in agricultural regions.
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