In this study, aerosol samples collected at a remote site in the Amazonian
rainforest and an urban site in Manaus, Brazil, were investigated on a
single-particle basis using a quantitative ...energy-dispersive electron probe X-ray
microanalysis (ED-EPMA). A total of 23 aerosol samples were collected in four
size ranges (0.25–0.5, 0.5–1.0, 1.0–2.0, and 2.0–4.0 µm) during
the wet season in 2012 at two Amazon basin sites: 10 samples in Manaus, an
urban area; and 13 samples at an 80 m high tower, located at the Amazon Tall
Tower Observatory (ATTO) site in the middle of the rainforest, 150 km
northeast of Manaus. The aerosol particles were classified into nine particle
types based on the morphology on the secondary electron images (SEIs)
together with the elemental concentrations of 3162 individual particles:
(i) secondary organic aerosols (SOA); (ii) ammonium sulfate (AS); (iii) SOA
and AS mixtures; (iv) aged mineral dust; (v) reacted sea salts; (vi) primary
biological aerosol (PBA); (vii) carbon-rich or elemental carbon (EC)
particles, such as soot, tarball, and char; (viii) fly ash; and (ix) heavy
metal (HM, such as Fe, Zn, Ni, and Ti)-containing particles. In submicron
aerosols collected at the ATTO site, SOA and AS mixture particles were
predominant (50 %–94 % in relative abundance) with SOA and ammonium
sulfate comprising 73 %–100 %. In supermicron aerosols at the ATTO site,
aged mineral dust and sea salts (37 %–70 %) as well as SOA and ammonium
sulfate (28 %–58 %) were abundant. PBAs were observed abundantly in the
PM2−4 fraction (46 %), and EC and fly ash particles were absent in
all size fractions. The analysis of a bulk PM0.25−0.5 aerosol sample
from the ATTO site using Raman microspectrometry and attenuated total
reflection Fourier-transform infrared spectroscopy (ATR-FTIR) showed that ammonium
sulfate, organics, and minerals are the major chemical species, which is
consistent with the ED-EPMA results. In the submicron aerosols collected in
Manaus, either SOA and ammonium sulfate (17 %–80 %) or EC particles
(6 %–78 %) were dominant depending on the samples. In contrast, aged
mineral dust, reacted sea salt, PBA, SOA, ammonium sulfate, and EC particles
comprised most of the supermicron aerosols collected in Manaus. The SOA,
ammonium sulfate, and PBAs were mostly of a biogenic origin from the
rainforest, whereas the EC and HM-containing particles were of an
anthropogenic origin. Based on the different contents of SOA, ammonium
sulfate, and EC particles among the samples collected in Manaus, a
considerable influence of the rainforest over the city was observed. Aged
mineral dust and reacted sea-salt particles, including mineral dust mixed
with sea salts probably during long-range transatlantic transport, were
abundant in the supermicron fractions at both sites. Among the aged mineral
dust and reacted sea-salt particles, sulfate-containing ones outnumbered
those containing nitrates and sulfate + nitrate in the ATTO samples. In
contrast, particles containing sulfate + nitrate were comparable in
number to particles containing sulfate only in the Manaus samples, indicating
the different sources and formation mechanisms of secondary aerosols, i.e.,
the predominant presence of sulfate at the ATTO site from mostly biogenic
emissions and the elevated influences of nitrates from anthropogenic
activities at the Manaus site.
The Amazon Basin plays key role in atmospheric chemistry, biodiversity and climate change. In this study we applied nanoelectrospray (nanoESI) ultra-high-resolution mass spectrometry (UHRMS) for the ...analysis of the organic fraction of PM2.5 aerosol samples collected during dry and wet seasons at a site in central Amazonia receiving background air masses, biomass burning and urban pollution. Comprehensive mass spectral data evaluation methods (e.g. Kendrick mass defect, Van Krevelen diagrams, carbon oxidation state and aromaticity equivalent) were used to identify compound classes and mass distributions of the detected species. Nitrogen- and/or sulfur-containing organic species contributed up to 60 % of the total identified number of formulae. A large number of molecular formulae in organic aerosol (OA) were attributed to later-generation nitrogen- and sulfur-containing oxidation products, suggesting that OA composition is affected by biomass burning and other, potentially anthropogenic, sources. Isoprene-derived organosulfate (IEPOX-OS) was found to be the most dominant ion in most of the analysed samples and strongly followed the concentration trends of the gas-phase anthropogenic tracers confirming its mixed anthropogenic–biogenic origin. The presence of oxidised aromatic and nitro-aromatic compounds in the samples suggested a strong influence from biomass burning especially during the dry period. Aerosol samples from the dry period and under enhanced biomass burning conditions contained a large number of molecules with high carbon oxidation state and an increased number of aromatic compounds compared to that from the wet period. The results of this work demonstrate that the studied site is influenced not only by biogenic emissions from the forest but also by biomass burning and potentially other anthropogenic emissions from the neighbouring urban environments.
The Amazon Basin plays key roles in the carbon and water cycles, climate change, atmospheric chemistry, and biodiversity. It has already been changed significantly by human activities, and more ...pervasive change is expected to occur in the coming decades. It is therefore essential to establish long-term measurement sites that provide a baseline record of present-day climatic, biogeochemical, and atmospheric conditions and that will be operated over coming decades to monitor change in the Amazon region, as human perturbations increase in the future. The Amazon Tall Tower Observatory (ATTO) has been set up in a pristine rain forest region in the central Amazon Basin, about 150 km northeast of the city of Manaus. Two 80 m towers have been operated at the site since 2012, and a 325 m tower is nearing completion in mid-2015. An ecological survey including a biodiversity assessment has been conducted in the forest region surrounding the site. Measurements of micrometeorological and atmospheric chemical variables were initiated in 2012, and their range has continued to broaden over the last few years. The meteorological and micrometeorological measurements include temperature and wind profiles, precipitation, water and energy fluxes, turbulence components, soil temperature profiles and soil heat fluxes, radiation fluxes, and visibility. A tree has been instrumented to measure stem profiles of temperature, light intensity, and water content in cryptogamic covers. The trace gas measurements comprise continuous monitoring of carbon dioxide, carbon monoxide, methane, and ozone at five to eight different heights, complemented by a variety of additional species measured during intensive campaigns (e.g., VOC, NO, NO2, and OH reactivity). Aerosol optical, microphysical, and chemical measurements are being made above the canopy as well as in the canopy space. They include aerosol light scattering and absorption, fluorescence, number and volume size distributions, chemical composition, cloud condensation nuclei (CCN) concentrations, and hygroscopicity. In this paper, we discuss the scientific context of the ATTO observatory and present an overview of results from ecological, meteorological, and chemical pilot studies at the ATTO site.
Understanding the impact on human health during peak episodes in air pollution is invaluable for policymakers. Particles less than PM2.5 can penetrate the respiratory system, causing cardiopulmonary ...and other systemic diseases. Statistical regression models are usually used to assess air pollution impacts on human health. However, when there are databases missing, linear statistical regression may not process well and alternative data processing should be considered. Nonlinear Artificial Neural Networks (ANN) are not employed to research environmental health pollution even though another advantage in using ANN is that the output data can be expressed as the number of hospital admissions. This research applied ANN to assess the impact of air pollution on human health. Three well-known ANN were tested: Multilayer Perceptron (MLP), Extreme Learning Machines (ELM) and Echo State Networks (ESN), to assess the influence of PM2.5, temperature, and relative humidity on hospital admissions due to respiratory diseases. Daily PM2.5 levels were monitored, and hospital admissions for respiratory illness were obtained, from the Brazilian hospital information system for all ages during two sampling campaigns (2008–2011 and 2014–2015) in Curitiba, Brazil. During these periods, the daily number of hospital admissions ranged from 2 to 55, PM2.5 concentrations varied from 0.98 to 54.2 μg m−3, temperature ranged from 8 to 26 °C, and relative humidity ranged from 45 to 100%. Of the ANN used in this study, MLP gave the best results showing a significant influence of PM2.5, temperature and humidity on hospital attendance after one day of exposure. The Anova Friedman's test showed statistical difference between the appliance of each ANN model (p < .001) for 1 lag day between PM2.5 exposure and hospital admission. ANN could be a more sensitive method than statistical regression models for assessing the effects of air pollution on respiratory health, and especially useful when there is limited data available.
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•Artificial Neural Networks (ANN) was applied to predict PM2.5 impact on human health.•Multilayer perceptron (MLP) showed best results.•Study of annual behavior of PM2.5 revealed high pollution events on winter.•PM2.5 elemental composition is mainly from anthropogenic activities.•Main contributions to PM2.5 emissions were from traffic sources.
ANN models predict respiratory hospital admissions from meteorological conditions and PM2.5 concentrations.
In the 21st century, severe droughts associated with climate change will increase biomass burning (BB) in Brazil caused by the human activities. Recent droughts, especially in 2005, 2010, and 2015, ...caused strong socioeconomic and environmental impacts. The 2015 drought considered the most severe since 1901, surpassed the 2005 and 2010 events in respect to area and duration. Herein, based on satellite data, the 2005, 2010 and 2015 drought impacts on wildfire episodes and carbon monoxide (CO) variability during the dry and the dry-to-wet transition seasons were examined. The BB occurrences in the dry season were fewer during 2015 than during 2005 (−44%) and 2010 (−47%). Contrasting, the BB events in the dry-to-wet transition season, were higher during 2015 than during 2005 (+192%) and 2010 (+332%). The BB outbreaks were concentrated in the southern and southwestern Amazon during 2005, in the Cerrado region during 2010, and mainly in the central and northern Amazon during 2015, an area normally with few fires. The CO concentration showed positive variations (up to +30%) occurred in the southern Amazon and central Brazil during the 2005 and 2010 dry seasons, and north of 20 °S during the 2015–2016 dry-to-wet transition season. The BB outbreaks and the CO emissions showed a considerable spatiotemporal variability among the droughts of 2005, 2010, and 2016, first of them driven by local conditions in the tropical North Atlantic (TNA), characterized by warm than normal sea surface waters and the other two by the El Niño occurrences.
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For the 2015 drought, the number of BB events remained high during the dry-to-wet transition season and affected northern regions where fires are normally few.
The global burden of disease estimated that approximately 7.1 million deaths worldwide were related to air pollution in 2016. However, only a limited number of small- and middle-sized cities have air ...quality monitoring networks. To date, air quality in terms of particulate matter is still mainly focused on mass concentration, with limited compositional monitoring even in mega cities, despite evidence indicating differential toxicity of particulate matter. As this evidence is far from conclusive, we conducted PM
2.5
bioaccessibility studies of potentially harmful elements in a medium-sized city, Londrina, Brazil. The data was interpreted in terms of source apportionment, the health risk evaluation and the bioaccessibility of inorganic contents in an artificial lysosomal fluid. The daily average concentration of PM
2.5
was below the WHO guideline, however, the chemical health assessment indicated a considerable health risk. The in vitro evaluation showed different potential mobility when compared to previous studies in large-sized cities, those with 1 million inhabitants or more (Curitiba and Manaus). The new WHO guideline for PM
2.5
mass concentration puts additional pressure on cities where air pollution monitoring is limited and/or neglected, because decision making is mainly revenue-driven and not socioeconomic-driven. Given the further emerging evidence that PM chemical composition is as, or even more, important than mass concentration levels, the research reported in the paper could pave the way for the necessary inter- and intra-city collaborations that are needed to address this global health challenge.
Serpentine and amphibole asbestos occur naturally in certain geologic settings worldwide, most commonly in association with ultramafic rocks, along associated faults. Ultramafic rocks have been used ...in Piên County, Southern Brazil for decades for the purpose of road paving in rural and urban areas, but without the awareness of their adverse environmental and health impact. The aim of this study was the chemical characterization of aerosols re-suspended in two rural roads of Piên, paved with ultramafic rocks and to estimate the pulmonary deposition of asbestos aerosols. Bulk aerosol samples were analyzed by means of X-ray fluorescence spectrometry and X-ray diffraction analysis, in order to characterize elemental composition and crystallinity. Single-particle compositions of aerosols were analyzed by computer-controlled electron-probe microanalysis, indicating the presence of a few percentages of serpentine and amphibole. Given the chemical composition and size distribution of aerosol particles, the deposition efficiency of chrysotile, a sub-group of serpentine, in two principal segments of the human respiratory system was estimated using a lung deposition model. As an important finding, almost half of the inhaled particles were calculated to be deposited in the respiratory system. Asbestos depositions were significant (∼25 %) in the lower airways, even though the selected breathing conditions (rest situation, nose breathing) implied the lowest rate of respiratory deposition. Considering the fraction of inhalable suspended chrysotile near local roads, and the long-term exposure of humans to these aerosols, chrysotile may represent a hazard, regarding more frequent development of lung cancer in the population of the exposed region.
The intercontinental transport of aerosols from the Sahara desert plays a significant role in nutrient cycles in the Amazon rainforest, since it carries many types of minerals to these otherwise ...low-fertility lands. Iron is one of the micronutrients essential for plant growth, and its long-range transport might be an important source for the iron-limited Amazon rainforest. This study assesses the bioavailability of iron Fe(II) and Fe(III) in the particulate matter over the Amazon forest, which was transported from the Sahara desert (for the sake of our discussion, this term also includes the Sahel region). The sampling campaign was carried out above and below the forest canopy at the ATTO site (Amazon Tall Tower Observatory), a near-pristine area in the central Amazon Basin, from March to April 2015. Measurements reached peak concentrations for soluble Fe(III) (48 ng m−3), Fe(II) (16 ng m−3), Na (470 ng m−3), Ca (194 ng m−3), K (65 ng m−3), and Mg (89 ng m−3) during a time period of dust transport from the Sahara, as confirmed by ground-based and satellite remote sensing data and air mass backward trajectories. Dust sampled above the Amazon canopy included primary biological aerosols and other coarse particles up to 12 µm in diameter. Atmospheric transport of weathered Saharan dust, followed by surface deposition, resulted in substantial iron bioavailability across the rainforest canopy. The seasonal deposition of dust, rich in soluble iron, and other minerals is likely to assist both bacteria and fungi within the topsoil and on canopy surfaces, and especially benefit highly bioabsorbent species. In this scenario, Saharan dust can provide essential macronutrients and micronutrients to plant roots, and also directly to plant leaves. The influence of this input on the ecology of the forest canopy and topsoil is discussed, and we argue that this influence would likely be different from that of nutrients from the weathered Amazon bedrock, which otherwise provides the main source of soluble mineral nutrients.
The aim of this investigation was to quantify organic and inorganic gas emissions from a four-cylinder diesel engine equipped with a urea selective catalytic reduction (SCR) system. Using a bench ...dynamometer, the emissions from the following mixtures were evaluated using a Fourier transform infrared (FTIR) spectrometer: low-sulfur diesel (LSD), ultralow-sulfur diesel (ULSD), and a blend of 20% soybean biodiesel and 80% ULSD (B20). For all studied fuels, the use of the SCR system yielded statistically significant (p < 0.05) lower NO x emissions. In the case of the LSD and ULSD fuels, the SCR system also significantly reduced emissions of compounds with high photochemical ozone creation potential, such as formaldehyde. However, for all tested fuels, the SCR system produced significantly (p < 0.05) higher emissions of N2O. In the case of LSD, the NH3 emissions were elevated, and in the case of ULSD and B20 fuels, the non-methane hydrocarbon (NMHC) and total hydrocarbon of diesel (HCD) emissions were significantly higher.
The mitigation of pollution released to the environment originating from the industrial sector has been the aim of all policy-makers and its importance is evident if the adverse health effects on the ...world population are considered. Although this concern is controversial, petroleum refinery has been linked to some adverse health effects for people living nearby. Apart from home, school is the most important indoor environment for children and there is increasing concern about the school environment and its impact on health, also in developing countries where the prevalence of pollution is higher. As most of the children spend more than 40% of their time in schools, it is critical to evaluate the pollution level in such environment. In the metropolitan region of Curitiba, South Brazil, five schools nearby industries and highways with high density traffic, were selected to characterize the aerosol and gaseous compounds indoor and outdoor of the classrooms, during 2009–2011. Size segregated aerosol samples were collected for analyses of bulk and single particle elemental profiles. They were analyzed by electron probe X-ray micro-analysis (EPXMA), and by energy-dispersive X-ray fluorescence (EDXRF), to investigate the elemental composition of individual particles and bulk samples. The concentrations of benzene, toluene, ethylbenzene, and xylene (BTEX); NO2; SO2; acetic acid; and formic acid were assessed indoor and outdoor using passive diffusion tubes. BTEX were analyzed by GC–MS and other collected gasses by ion chromatography. Individual exposition of BTEX was assessed by personal passive diffusion tubes. Results are interpreted separately and as a whole with the specific aim of identifying compounds that could affect the health of the scholars. In view of the chemical composition and size distribution of the aerosol particles, local deposition efficiencies in the children's respiratory systems were calculated, revealing the deposition of particles at extrathoracic, tracheobronchial and pulmonary levels.
•Pollution in school environment can impact children's health, being critical to evaluate it.•Five schools were selected in Curitiba, Brazil to measure pollutants levels, in 2009–2011.•Results are interpreted aiming to identify compounds that could affect the scholars' health.
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