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We aimed to study the daily formaldehyde (HCHO) columns over urban and forested areas in São Paulo State, Brazil, from rhe TROPOMI spectrometer onboard the Sentinel-5P satellite during 2020. Nineteen specific areas were defined in four regions: 3 areas in each of two preserved Atlantic Forests (PEMD and PETAR), 3 in a sugarcane growing region (NERG) and 10 in the Metropolitan Area of São Paulo (MASP), among which 2 areas are in the Morro Grande reserve, which is a significant remnant of Atlantic Forest outside the densely urbanized area of MASP. An analysis of variance and Tukey’s test showed that the mean annual columns over the Morro Grande reserve (1.69±1.05×10−4 mol/m² and 1.73±1.07×10−4 mol/m²) presented greater statistical similarity with the forest and rural areas of the state (<1.70×10−4 mol/m²) than with MASP (>2.00×10−4 mol/m²), indicating few effects from megacity anthropogenic emissions. Case studies addressing selected days in 2020 showed that fires in and around the state were related to episodes of maximum density of HCHO columns. The results showed significant seasonality, with lower concentrations during summer (wet season) and higher concentrations during winter and spring (dry and transition dry–wet seasons).

The Spill, Transport and Fate Model (STFM) is a new computational tool for modeling oil spills in Brazilian waters, developed at the Institute of Astronomy, Geophysics and Atmospheric Sciences at the University of São Paulo. The STFM was designed to assist in the analysis of environmental impact and water quality, for academic purposes and for environmental licensing studies. This work presents the formulation of the model, performance evaluations and validation of the results. These are necessary phases for the model to be made available to the public. Keywords: offshore contamination STFM, oil model, oil spill, water quality.

This study evaluates nine Planetary Boundary Layer (PBL) turbulence parameterization schemes from the Weather Research and Forecasting (WRF) mesoscale meteorological model, comparing hourly values of meteorological variables observed and simulated at the surface of the Metropolitan Region of São Paulo (MRSP). The numerical results were objectively compared with high-quality observations carried out on three micrometeorological platforms representing typical urban, suburban, and rural land use areas of the MRSP, during the 2013 summer and winter field campaigns as part of the MCITY BRAZIL project. The main objective is to identify which PBL scheme best represents the diurnal evolution of conventional meteorological variables (temperature, relative and specific humidity, wind speed, and direction) and unconventional (sensible and latent heat fluxes, net radiation, and incoming downward solar radiation) on the surface. During the summer field campaign and over the suburban area of the MRSP, most PBL scheme simulations exhibited a cold and dry bias and overestimated wind speed. They also overestimated sensible heat flux, with high agreement index and correlation values. In general, the PBL scheme simulations performed well for latent heat flux, displaying low mean bias error and root square mean error values. Both incoming downward solar radiation and net radiation were also accurately simulated by most of them. The comparison of the nine PBL schemes indicated the local Mellor-Yamada-Janjic (MYJ) scheme performed best during the summer period, particularly for conventional meteorological variables for the land use suburban in the MRSP. During the winter field campaign, simulation outcomes varied significantly based on the site’s land use and the meteorological variable analyzed. The MYJ, Bougeault-Lacarrère (BouLac), and Mellor-Yamada Nakanishi-Niino (MYNN) schemes effectively simulated temperature and humidity, especially in the urban land use area. The MYNN scheme also simulated net radiation accurately. There was a tendency to overestimate sensible and latent heat fluxes, except for the rural land use area where they were consistently underestimated. However, the rural area exhibited superior correlations compared to the urban area. Overall, the MYJ scheme was deemed the most suitable for representing the convectional and nonconventional meteorological variables on the surface in all urban, suburban, and rural land use areas of the MRSP.

The basins of Campos and Santos, the most important offshore oil reserves in Brazil, hold potential for being the largest offshore oil exploration fields in the next decades, mainly due to the oil located in the pre-salt layer. This region presents real conditions for the occurrence of intense atmospheric events added to the high velocity of the meanders of the Brazilian current. However, the increasing risk of accidents and damage in the region has been the subject of concern and discussion. The risks in the basins of Campos (2011) and Santos (2012) may not exhibit the the same potential for disastrous events as do those in the oil fields of Alaska and of the Gulf of Mexico, but accidents in these areas are not unlikely, as already evidenced by previous accidents under similar operating conditions (e.g. Chevron Platform accident in Campos Basin, RJ, Brazil, 2011). This paper highlights discussion of the multidisciplinary and substantial environmental features in oil exploration fields along the Brazilian coast based on Semi-Systematic Review methodology. The aspects evaluated cover not only geological traits, oceanic and meteorological circulation, but also current oil production, the most significant oil spill accidents recorded up to 2019 and the discussion about some current levels of seawater contamination.

In the second quarter of 2021, the companies at the Capuava Petrochemical Complex (CPC, Santo André, Brazil) carried out a 50-day scheduled shutdown for the maintenance and installation of new industrial equipment. This process resulted in severe uncontrolled emissions of particulate matter (PM) and volatile organic compounds (VOCs) in a densely populated residential area (~3400 inhabitants/km2). VOCs can be emitted directly into the atmosphere in urban areas by vehicle exhausts, fuel evaporation, solvent use, emissions of natural gas, and industrial processes. PM is emitted by vehicle exhausts, mainly those powered by diesel, industrial processes, and re-suspended soil dust, in addition to that produced in the atmosphere by photochemical reactions. Our statistical analyses compared the previous (2017–2020) and subsequent (2021–2022) periods from this episode (April–May 2021) from the official air quality monitoring network of the PM10, benzene, and toluene hourly data to improve the proportion of this period of uncontrolled emissions. Near-field simulations were also performed to evaluate the dispersion of pollutants of industrial origin, applying the Gaussian plume model AERMOD (steady-state plume model), estimating the concentrations of VOC and particulate matter (PM10) in which the population was exposed in the region surrounding the CPC. The results comparing the four previous years showed an increase in the mean concentrations by a factor of 2 for PM10, benzene, and toluene, reaching maximum values during the episode of 174 µg m−3 (PM10), 79.1 µg m−3 (benzene), and 58.7 µg m−3 (toluene). Meanwhile, these higher concentrations continued to be observed after the episode, but their variation cannot be fully explained yet. However, it is worth highlighting that this corresponds to the post-pandemic period and the 2022 data also correspond to the period from January to June, that is, they do not represent the annual variation. A linear correlation indicated that CPC could have been responsible for more than 60% of benzene measured at the Capuava Air Quality Station (AQS). However, the PM10 behavior was not fully explained by the model. AERMOD showed that the VOC plume had the potential to reach a large part of Mauá and Santo André municipalities, with the potential to affect the health of more than 1 million inhabitants.

Ammonia is a key alkaline species, playing an important role by neutralizing atmospheric acidity and inorganic secondary aerosol production. On the other hand, the NH 3 /NH 4 + increases the acidity and eutrophication in natural ecosystems, being NH 3 classified as toxic atmospheric pollutant. The present study aims to give a better comprehension of the nitrogen content species distribution in fine and coarse particulate matter (PM 2.5 and PM 2.5–10 ) and to quantify ammonia vehicular emissions from an urban vehicular tunnel experiment in the metropolitan area of São Paulo (MASP). MASP is the largest megacity in South America, with over 20 million inhabitants spread over 2000 km 2 of urbanized area, which faces serious environmental problems. The PM 2.5 and PM 2.5–10 median mass concentrations were 44.5 and 66.6 μg m −3 , respectively, during weekdays. In the PM 2.5 , sulfate showed the highest concentration, 3.27 ± 1.76 μg m −3 , followed by ammonium, 1.14 ± 0.71 μg m −3 , and nitrate, 0.80 ± 0.52 μg m −3 . Likewise, the dominance (30 % of total PM 2.5 ) of solid species, mainly the ammonium salts, NH 4 HSO 4 , (NH 4 ) 2 SO 4 , and NH 4 NO 3 , resulted from simulation of inorganic species. The ISORROPIA simulation was relevant to show the importance of environment conditions for the ammonium phase distribution (solid/aqueous), which was solely aqueous at outside and almost entirely solid at inside tunnel. Regarding gaseous ammonia concentrations, the value measured inside the tunnel (46.5 ± 17.5 μg m −3 ) was 3-fold higher than that outside (15.2 ± 11.3 μg m −3 ). The NH 3 vehicular emission factor (EF) estimated by carbon balance for urban tunnel was 44 ± 22 mg km −1 . From this EF value and considering the MASP traffic characteristics, it was possible to estimate more than 7 Gg NH 3  year −1 emissions that along with NOx are likely to cause rather serious problems to natural ecosystems in the region.

The broad expanse of the urban metropolitan area of São Paulo (MASP) has made buses, the predominant public transport mode for commuters in the city. In 2016, the bus fleet in the MASP reached 56,354 buses and it was responsible for more than 12 million daily trips. Here, we evaluate for the first time, the emission profile of gaseous and particulate pollutants from buses running on 7% biodiesel + 93% petroleum diesel and their spatial distribution in the MASP. This novel study, based on four bus terminal experiments, provides an extensive analysis of atmospheric pollutants of interest to public health and climate changes, such as CO2, CO, NOx, VOCs, PM10, PM2.5 and their constituents (black carbon (BC) and elements). Our results suggest that the renovation of the bus fleet from Euro II to Euro V and the incorporation of electric buses had a noticeable impact (by a factor of up to three) on the CO2 emissions and caused a decrease in NO emissions, by a factor of four to five. In addition, a comparison with previous Brazilian studies, shows that the newer bus fleet in the MASP emits fewer particles. Emissions from the public transport sector have implications for public health and air quality, not only by introducing reactive pollutants into the atmosphere but also by exposing the commuters to harmful concentrations. Our findings make a relevant contribution to the understanding of emissions from diesel-powered buses and about the impact of these new vehicular technologies on the air quality in the MASP.

The Metropolitan Area of São Paulo (MASP) is the largest megacity in South America, with 21 million inhabitants and more than 8 million vehicles. Those vehicles run on a complex fuel mix, with ethanol accounting for nearly 50% of all fuel sold. That has made the MASP a unique case study to assess the impact of biofuel use on air quality. Currently, the greatest challenge in terms of improving air quality is controlling the formation of secondary pollutants such as ozone, which represents the main air pollution problem in the MASP. We evaluated the temporal trends in the concentrations of ozone, its precursors (formaldehyde, acetaldehyde, and NO2), CO, and NO, from 2012 to 2016. Formaldehyde and acetaldehyde concentrations were frequently higher in winter than in other seasons, showing the importance of meteorological conditions to the distribution of atmospheric pollutants in the MASP. We found no clear evidence that the recent growth in ethanol consumption in Brazil has affected acetaldehyde concentrations, which are associated with emissions from ethanol combustion. In fact, the formaldehyde/acetaldehyde ratio remained relatively constant over the period studied, despite the change in the fuel consumption profile in the MASP.

Since 2000s, several studies have been reporting an increase of alkaline species in atmospheric deposition worldwide. This study aims to evaluate and give a better understanding about atmospheric deposition chemistry collected in Lavras, a Brazilian city with rural background. Bulk atmospheric deposition samples were collected from March 2018 to February 2019 and major ionic species were quantified. The pH values ranged from 5.52 to 8.29, with an average of 5.92 and most deposition samples (~ 94%) were alkaline (pH > 5.60). For the whole sampling campaign, the ions profile in volume weighted mean (VWM) was described as follows: Ca 2+ (35.02) > NH 4 + (11.26) > Cl − (11.19) > Mg 2+ (9.04) > NO 3 − (8.57) > Na + (5.65) > K + (2.61) > SO 4 2− (2.43) > H + (0.94) μmol L −1 . We identified Ca 2+ and NH 4 + as the most predominant species accounting for 53% of the total ionic species distribution. In addition, all samples showed neutralization factor (NF) index greater than 1, with mean value of 6.4. Regarding regression analysis, acidity neutralization precursors such as calcium and ammonia accounted for 50% and 4%, respectively. In addition, samples alkaline pattern was mainly due to agricultural sources, including fertilizer production and application, and cement manufacturing inside the county air basin.

Turbulence has a significant impact on the urban climate, affecting the well-being of millions of people living in cities. Spectral analysis is useful for understanding turbulent processes. However, there are gaps in the knowledge of turbulence spectral properties over urban surfaces, especially processes involving passive gases. In this study, turbulence spectral properties are investigated within the Monin–Obukhov similarity theory framework. In situ turbulence measurements of wind velocity components, temperature, and water vapor and carbon dioxide densities were carried out at 25–26 m above ground between 2009 and 2017 in a suburban area of the Metropolitan Region of São Paulo, Brazil. Our results indicated that the spectra (cospectra) of velocity and scalars followed the − 2/3 (− 4/3) slope in the inertial subrange. Under neutral conditions, the cospectra of the passive gases were nearly identical. The normalized dissipation rates of turbulent kinetic energy and scalar variances, as well as fluxes, can be described by similarity functions based on the local equilibrium assumption when the imbalance factors were considered. In addition, the similarity functions for the normalized dissipation rates of the water vapor and CO2 variances were nearly identical. A more suitable similarity function for the normalized dissipation rate of temperature variance in urban areas was proposed. The spectra of the passive gases exhibited a minor peak in the low-frequency range possibly associated with non-local effects. These results enhance our understanding of the turbulent exchanges in urban environments and can contribute to air quality assessment and engineering applications.