The increased emissions of reactive nitrogen gases from anthropogenic sources to the atmosphere has been pointed out as responsible for triggering a series of environmental problems at the local, regional, and global scale. Among the many consequences associated with the excess of reactive nitrogen in the environment is the increase of atmospheric aerosol formation. In this way, the present review article aims to provide an overview of the main aerosol formation reactions from the reactive nitrogen gases, their growth processes, and removal from the atmosphere. The paper also addresses the implications of increasing the atmospheric aerosol load, including effects on the planet’s radiative forcing, cloud formation and precipitation, macronutrient dispersion, visibility and human health. The possible relationship between the long-term exposure to these pollutants and COVID-19 fatality is also discussed. The need for more information related to reactive nitrogen gases and atmospheric aerosols is urgent since they act on fundamental processes on planet Earth and their quantity and composition have been abruptly changed over the last hundred years. Therefore, further investigations on this topic should be stimulated and better integrated in order to guide normative decisions and the delineation of possible solutions.

OZONE APPLICATIONS AND IMPLICATIONS FOR INDUSTRY, ENVIRONMENT, AND HEALTH. Stratospheric ozone is an efficient filter for ultraviolet radiation, which damages organisms’ lives exposed to sunlight. In the troposphere, ozone is essential to oxidate volatile organic compounds, but its effects are harmful to animals and plants, particularly humans. The high reactivity of ozone with some organic compounds makes it a promising agent for several applications, such as microbiological control and the medical field. However, their contact with surfaces containing unsaturated substances and other compounds can result in the formation of products that are harmful to human health or distort the organoleptic and structural properties of food. The results available in the literature are often divergent as to their safety and economic viability. Despite this, there are many cases of dermatological applications, and as sanitizing agents in several environments. Antiviral and bactericide properties were that guided the expansion of ozone application in the current coronavirus pandemic (COVID-19). However, more studies should be carried out to comprove its effectiveness, considering possible damages resulting from these applications.

A new methodology using gas-diffusion microextraction (GDME) was developed for the analysis of volatile corrosion inhibitors (VCIs). The evaluation of the inhibition efficiency and corrosion rate (ν) was performed by NaCl deliquescence tests and correlated with measurements of polarization resistance (Rp) obtained from electrochemical impedance spectroscopy (EIS) analysis and with the pH resulting from the atmosphere of the inhibitor (pHGDME). The correlation obtained between n and pHGDME indicates that the higher the value of pHGDME the lower the corrosion rate. The Raman spectra of steel was used to monitor in situ adsorption of VCI and the surface modifications caused by the inhibitors. The scanning electron microscopy (SEM) images corroborate the data of ν, both indicating that the cyclohexylamine vapor showed the best corrosion resistance performance.

A passive sampler constructed with a new type of material and used for measurement of ambient nitrogen dioxide is presented. The sampler was constructed with parts of two 50 mL conical centrifuge tubes. The procedure is based on NO2 uptaken on cellulose filter impregnated with triethanolamine. After sampling, the analyte is solubilized and placed to react with Griess-Saltzman solution. The absorbance of the formed complex is determined at 540 nm. A mean relative standard deviation of 9,72% was obtained using samplers exposed in triplicate, and a determination coefficient (R2) of 0,979 was achieved in parallel measurements using the samplers and a commercial NOx monitor. Advantages of the technique include ease of use, the ready availability of components, and excellent sensitivity.

In this contribution we propose, for the first time, the use of Methylene Violet 3 RAX dye for the detection and determination of nitrite in cured meats and vegetables. Quantification is based on the decrease in absorbance of the dye, which is proportional to the nitrite concentration. The proposed method presents linear response (r > 0.99) in the range from 1.8 to 9 µmol L-1 of nitrite, with a limit of detection of 0.14 µmol L-1. Satisfactory accuracy with the official Association of Official Agricultural Chemists (AOAC) method was achieved, and the method was successfully applied to a wide range of cured meats and vegetables. The proposed method offers similar or superior performance to other optical methods used for the determination of nitrite in different matrices, with advantage in terms of reduction of chemical waste for each analysis, by minimizing amounts of reagents and products.

O objetivo deste estudo foi investigar a composição das águas de chuva da cidade de Araraquara, Brasil, uma região influenciada pela queima da palha da cana-de-açúcar. Variáveis químicas e mineralógicas foram analisadas em águas de chuva coletadas durante o período de safra, período seco de 2009 e entressafra, período úmido de 2010. Ca2+ e NH4+ foram responsáveis por 55% dos cátions e NO3- por 45% dos ânions presentes nas águas de chuva. Al, Fe e K foram os elementos traço mais abundantes nas frações solúvel e insolúvel. Elevada concentração média ponderada pelo volume (MPV) foi observada para a maioria das espécies analisadas em amostras do período de safra, principalmente devido às atividades agrícolas e condições meteorológicas. A química das águas de chuva de Araraquara e a análise de componentes principais (ACP) indicaram que fontes naturais e antrópicas, principalmente as relacionadas às atividades agrícolas, são responsáveis pelas emissões para a atmosfera.

The purpose of this study was to assess the composition of the rainwater in Araraquara City, Brazil, a region strongly influenced by pre-harvest burning of sugar cane crops. Chemical and mineralogical variables were measured in rainwater collected during the harvest, dry period of 2009 and the non-harvest, wet period of 2010. Ca2+ and NH4+ were responsible for 55% of cations and NO3- for 45% of anions in rainwater. Al and Fe along with K were the most abundant among trace elements in both soluble and insoluble fractions. High volume weighted mean concentration (VWM) for most of the analyzed species were observed in the harvest, dry period, mainly due to agricultural activities and meteorological conditions. The chemistry of the Araraquara rainwater and principal component analysis (PCA) quantification clearly indicate the concurrence of a diversity of sources from natural to anthropogenic especially related to agricultural activities.

Um método fluorimétrico foi adaptado para determinação de amônia no ar ambiente. A coleta da amostra foi feita em filtros de celulose impregnados com ácido oxálico, seguida pela solubilização do íon amônio, adição dos reagentes e determinação fluorimétrica. Alguns parâmetros analíticos importantes foram avaliados, tais como tempo e vazão de amostragem. Formaldeído, dietilamina e sulfeto de hidrogênio não interferiram no método. A curva analítica apresentou linearidade até pelo menos 34 ppbv, em vazão e tempo de amostragem respectivos de 0,3 L min-1 e 20 min. Nestas condições, o limite de detecção alcançado foi de 3 ppbv. O método proposto aqui apresentou resultados similares ao método colorimétrico do indofenol, porém necessitou de um tempo de amostragem menor. Mostrou ser de fácil aplicação, sendo útil para medir baixas concentrações de amônia e possíveis flutuações na sua concentração em intervalos de tempo curtos, como 20 min.

A fluorimetric method was developed for the determination of ammonia in ambient air. Samples were collected using cellulose filters impregnated with oxalic acid, followed by solubilization of the ammonium ion, addition of reagents and fluorimetric detection. Important analytical parameters that were evaluated included sampling time and flow rate. Formaldehyde, diethylamine and hydrogen sulfide did not interfere in the method. The analytical curve was linear up to at least 34 ppbv of ammonia, using a sample flow rate of 0.3 L min-1 and a sampling time of 20 min. The limit of detection achieved under these conditions was 3 ppbv. The proposed method offers advantages compared to the indophenol colorimetric method, especially the ability to use a shorter sampling time. The method proved to be easy to apply, and should be useful in applications where measurements of low concentrations of ammonia are required, or where there are rapid fluctuations in ammonia concentrations over periods as short as 20 min.

É apresentado um modelo para quantificação de fontes e deposição de espécies nutrientes que contribuem com a formação e concentração do aerossol atmosférico. Para este procedimento foram utilizadas ferramentas estatísticas como: a análise de componentes principais (PCA) e análise de regressão linear múltipla (MLRA) associadas a modelos de deposição de partículas segregadas por tamanho. Em região rural do sudeste do Brasil, a queima de biomassa, produtos de reações secundárias, e re-suspensão de poeira do solo possibilitaram explicar 43%, 31% e 21% da massa do MP2.5, respectivamente. A re-suspensão de poeira e a queima de biomassa contribuíram com 22% e 19%, respectivamente, da massa do MP10. A re-suspensão possibilitou explicar cerca da metade da massa das partículas grossas. Cerca de 40% de NO3--N, 20% de fósforo e 55% de potássio depositados tem origem nas emissões relacionadas com a agricultura. Atualmente a deposição sobre a floresta tropical é aumentada pelos fatores de 12.2 (N), 6.2 (P) e 2.6 (K) com relação a aqueles que existiam nas condições naturais do passado.

A procedure is presented for quantification of sources contributing to atmospheric aerosol chemical nutrient concentrations and dry deposition fluxes. Source apportionment using principal component analysis (PCA) and multiple linear regression analysis (MLRA) was followed by application of a size-segregated particle dry deposition model. In a rural region of southeast Brazil, biomass burning, products of secondary reactions, and soil dust re-suspension explained 43%, 31% and 21% of PM2.5 mass, respectively. Re-suspension and biomass burning contributed 22% and 19%, respectively, to PM10 mass, and re-suspension accounted for approximately half of the mass of coarse particles. At least 40% of NO3--N, 20% of phosphorus and 55% of potassium deposited originated from agriculture-related emissions. Deposition to tropical forest is currently higher than the minimum under natural conditions by factors of 12.2 (N), 6.2 (P) and 2.6 (K).

Emissões industriais são as fontes principais de poluição atmosférica no parque industrial de Cubatão, no sudeste do Brasil, onde a dispersão é limitada pela extensa faixa de montanhas na região. O transporte de veículos pesados é uma fonte importante de gases e aerossóis e pode influenciar nas concentrações de poluentes atmosféricos próximos à superfície, dependendo das condições meteorológicas. Este trabalho mostra que as fontes industriais foram predominantes nos fluxos de SO2, enquanto que o transporte veicular foi a principal fonte de NO2 para a atmosfera. A rápida remoção de NO2 e SO2 da atmosfera foi atribuída às reações na fase gasosa e reações heterogêneas, respectivamente. Concentrações médias de MP10 aumentaram cerca de uma ordem de magnitude durante a circulação da brisa do mar. Foi demonstrado que instrumentação de resposta rápida pode fornecer uma alternativa conveniente às medidas obtidas com equipamentos fixos para mapeamento espacial (horizontal e vertical) de poluentes atmosféricos.

Industrial emissions are a notorious source of atmospheric pollution in the Cubatão industrial park of Southern Brazil, where dispersion is restricted by surrounding mountain ranges. It is shown here that road transport is also a large source of gases and aerosols, which can dominate pollutant concentrations at ground level, depending on meteorological conditions. SO2 was released mainly by industry, while road transport was a major source of NOx. Rapid removal of NO2 and SO2 was attributed to fast gas phase and heterogeneous reactions, respectively. Average PM10 concentrations increased by an order of magnitude during sea breeze fumigation, and high particulate pollution events were associated with vehicular activity. It is demonstrated that fast-response portable instrumentation can provide a useful alternative to measurements at fixed network sites for spatial (horizontal and vertical) mapping of atmospheric pollutants.

A new passive sampling system for monitoring NO2 in air has been developed to measure gas concentrations in indoor and outdoor air. The sampler is inexpensive, and easy to construct and operate. Nitrogen dioxide forms a derivative after reaction with a filter coated with triethanolamine and ethyleneglycol. The nitrogen dioxide derivative is extracted from the filter, and the concentration is determined by colorimetry. To test the sampler for measuring ambient level nitrogen dioxide, measurements were carried out inside homes and in a range of workplace environments.

Um método simples e sensível, baseado em uma gota líquida, é descrito para medida do ozônio atmosférico. Uma gota de 30 µL de solução de índigo azul é suspensa em uma corrente de ar para amostragem. O ozônio coletado reage com a solução de índigo azul, provocando seu descoramento. O sensor colorimétrico é composto por duas fibras ópticas; a fonte de luz monocromática usada foi um LED vermelho (625 nm). A curva analítica foi construída com concentrações padrão de ozônio, na faixa de 37 a 123 ppbv. O limite de detecção alcançado foi 7,3 ppbv. O método considerado mostrou-se de fácil aplicação e resposta rápida, com um tempo total de análise de apenas 5 minutos.

A simple and sensitive method based on a liquid droplet is described for the measurement of atmospheric ozone. A 30 µL drop of indigo blue solution is suspended in a flowing-air sampling stream. The ozone collected reacts with the indigo solution resulting in its decolorization. The colorimetric sensor is composed of two optical fibers and the source of monochromatic light was a red LED (625 nm). The calibration curve was constructed with ozone standard concentrations ranging from 37 - 123 ppbv. The detection limit achieved was 7.3 ppbv. The method considered here showed itself to be easy to apply with a fast response and a total analysis time of only 5 minutes.

This work reports the analysis of inorganic and organic contaminants in alcohol fuel samples using capillary electrophoresis. Chloride and sulfate were analyzed in nitrate/ monochloroacetic acid at 10 mmol L-1 concentration each under indirect UV detection (210 nm). The analysis of aldehydes is based on the 216 nm detection of 3-methyl-2-benzothiazoline hydrazone adducts. The running buffer consisted of 20 mmol L-1 tetraborate , 40 mmol L-1 sodium dodecyl sufate and 12 mmol L-1 beta-ciclodextrin. Both methodologies were applied to real samples indicating inorganic ion concentrations from 0.15 to 6.64 mg kg-1 and aldehydes from 32.0 to 91.3 mg L-1.

A sensitive and simple system was proposed for the in situ measurement of total aldehyde in outdoor or indoor ambient. The method is based on the use of a reagent drop as an useful interface to preconcentrate the sample prior to determination of total aldehyde as formaldehyde. The drop is formed at the tip of a cylindrical tube that contains two optical fibers placed on opposite sides and in contact with the reagent solution. One optical fiber carries the red light to the drop form a light emitting diode (LED). The transmitted light is measured by a second optical fiber/photodiode system. The analytical signal is read and converted into absorbance. The reagent solution of 3-methyl-2-benzothiazoline hydrazone (MBTH) forms a blue cation during reaction with formaldehyde that can be measured at 660 nm. Some aspects of kinetics reaction formation of dye were reevaluated. The formaldehyde reacts with MBTH and forms the azine in about 12 min. The oxidation of MBTH by Fe (III) and the formation of dye requires 3 min. The absorbance of the reagent drop is proportional to the sampling time and to the analyte concentration. The absorbance signal increases with increased sample gas flow until a maximum is reached then decreases until it forms a plateau. The proposed method was evaluated using both outdoor and indoor samples, and it was shown to viable provide an accurate measure of total aldehyde.

Neste trabalho foi avaliado o desempenho de filtros para dióxido de nitrogênio, buscando evitar perdas durante a amostragem de sulfetos orgânicos, provocadas por oxidantes atmosféricos. Diferentes compostos e misturas foram usadas para recobrir superfícies sólidas empregadas na preparação destes filtros. Um sistema automatizado de análise em fluxo foi utilizado para comparar a eficiência de retenção de dióxido de nitrogênio pelos filtros. Entre os materiais testados na preparação dos filtros, as melhores escolhas foram papel ou lã de vidro impregnados com a mistura de sulfato de ferro (II), ácido sulfúrico e ácido pirogalico e ainda os filtros feitos de papel impregnados com trietanolamina. Os resultados obtidos em laboratório com mistura de gás padrão de dimetilsulfeto e experimentos em campo confirmaram a qualidade dos filtros e indicaram que eles podem ser utilizados para evitar a oxidação de sulfetos orgânicos durante a sua amostragem.

In this work, oxidant scrubbers were evaluated for their ability to prevent sampling losses of dimethylsulfide caused by reactions with nitrogen dioxide. Various compounds and mixtures were used in the preparation of the oxidant scrubbers. An automatic flow analysis device was used to compare scrubbing efficiency for nitrogen dioxide. Among the scrubbers tested, the best were shown to be the one made with filter paper or glass wool coated with iron (II) sulfate, sulfuric acid and pyrogallic acid, and the one made from with paper coated with triethanolamine. The results obtained under laboratory conditions, using dimethylsulfide standard gas, and in field experiments confirmed that these scrubbers are suitable for the prevention of oxidation during sampling.

In the present paper, we report on the analytical use of a dynamic droplet based gas collection and an analysis system. A droplet formed at the tip of a tube represents a sampling approach that provides an indefinitely renewable surface and uses very little reagent. Sample gas flows past the droplet at a low flow rate. After the gas was sampled , the analysis can be carried out by different methodologies. The feasibility of the sensor is demonstrated by continuos determination of gaseous as: NO2, Cl2 and SO2.