Biomass Burning In Brazil Research Articles

Beyond megacities: tracking air pollution from urban areas and biomass burning in Brazil

Most of the world’s population lives in rural areas or small to medium-sized cities (totalling 68% of the world population), all of which are impacted by distant air pollution sources. In Brazil, primary pollutant emissions have decreased in urban centres because of government actions, while secondary pollutants such as surface ozone (O3) increased. In addition, O3 and its precursors can be worsening air quality in areas already affected by biofuels production, especially ethanol. We provide almost 3 months of hourly data (June 7, 2019 to August 25, 2019) for concentrations of O3, CO2 and other priority pollutants from a mobile station positioned to distinguish among pollutant plumes (biomass burning, metropolitan area of São Paulo (MASP) and other cities). Although the concentrations of O3 and CO2 were highest in the plumes from biomass burning, the MASP accounted for up to 80% of the O3 concentration in communities over 200 km away.

Near-field emission profiling of tropical forest and Cerrado fires in Brazil during SAMBBA 2012

Abstract. We profile trace gas and particulate emissions from near-field airborne measurements of discrete smoke plumes in Brazil during the 2012 biomass burning season. The South American Biomass Burning Analysis (SAMBBA) Project conducted during September and October 2012 sampled across two distinct fire regimes prevalent in the Amazon Basin. Combined measurements from a Compact Time-of-Flight Aerosol Mass Spectrometer (C-ToF-AMS) and a Single Particle Soot Photometer (SP2) are reported for the first time in a tropical biomass burning environment. Emissions from a mostly smouldering tropical forest wildfire in Rondônia state and numerous smaller flaming Cerrado fires in Tocantins state are presented. While the Cerrado fires appear to be representative of typical fire conditions in the existing literature, the tropical forest wildfire likely represents a more extreme example of biomass burning with a bias towards mostly smouldering emissions. We determined fire-integrated modified combustion efficiencies, emission ratios and emission factors for trace gas and particulate components for these two fire types, alongside aerosol microphysical properties. Seven times more black carbon was emitted from the Cerrado fires per unit of fuel combustion (EFBC of 0.13 ± 0.04 g kg−1) compared to the tropical forest fire (EFBC of 0.019 ± 0.006 g kg−1), and more than 6 times the amount of organic aerosol was emitted from the tropical forest fire per unit of fuel combustion (EFOM of 8.00 ± 2.53 g kg−1, EFOC of 5.00 ± 1.58 g kg−1) compared to the Cerrado fires (EFOM of 1.31 ± 0.42 g kg−1, EFOC of 0.82 ± 0.26 g kg−1). Particulate-phase species emitted from the fires sampled are generally lower than those reported in previous studies and in emission inventories, which is likely a combination of differences in fire combustion efficiency and fuel mixture, along with different measurement techniques. Previous modelling studies focussed on the biomass burning season in tropical South America have required significant scaling up of emissions to reproduce in situ and satellite aerosol concentrations over the region. Our results do not indicate that emission factors used in inventories are biased low, which could be one potential cause of the reported underestimates in modelling studies. This study supplements and updates trace gas and particulate emission factors for fire-type-specific biomass burning in Brazil for use in weather and climate models. The study illustrates that initial fire conditions can result in substantial differences in terms of their emitted chemical components, which can potentially perturb the Earth system.

Long-range Transport of Aerosols from Biomass Burning over Southeastern South America and their Implications on Air Quality

ABSTRACT The long-range transport of aerosols is a global issue since it may significantly affect the air quality of regions without high concentrations of fine particulate matter (PM2.5). Two significant occurrences of long-range transport of aerosols over the state of Parana in Brazil, which occurred during the periods Aug. 16–18 and Sep. 10–14 of 2016, were studied in order to characterize the atmospheric synoptic conditions of these events and to estimate their contribution to the air quality conditions in the northern region of the state. The South American Low Level Jet (SALLJ) was the key meteorological component used to define the origin of the air mass trajectories over the region. In the first event, the SALLJ lost its configuration, bringing air masses from the western part of Sao Paulo (state), while in the second event, the SALLJ formed over southern Brazil and brought air masses from the northern and central parts of the nation. The significant number of fires from biomass burning in central Brazil associated with synoptic conditions contributed to the increase in PM2.5 concentrations by approximately 70–87% in the region. The transport of aerosols was a determining factor in PM2.5 exceeding the air quality standard in the region. Therefore, to minimize this problem, it is imperative to control biomass burning in Brazil.

Sources of atmospheric mercury in the tropics: continuous observations at a coastal site in Suriname

Abstract. Mercury measurements at a coastal site in Nieuw Nickerie (5°56' N, 56°59' W), Suriname, provide the only continuous records of atmospheric mercury in the tropics. Here we evaluate observations of total gaseous mercury (TGM) during 2007. Nieuw Nickerie typically samples marine air from the Atlantic Ocean, with occasional influence from continental South America. Over the year, average concentrations are 1.40 ng m−3. As the intertropical convergence zone passes over Suriname twice each year, the site samples both northern and southern hemispheric air masses. We use back trajectories to classify each measurement by hemisphere, as well as continental or ocean. For air passing over ocean before sampling, TGM concentrations are 10% higher in air coming from the Northern Hemisphere (1.45 ng m−3) than from the Southern Hemisphere (1.32 ng m−3). Air from the South American continent also carries higher TGM (1.43 ng m−3) than air from the South Atlantic Ocean, with most of these trajectories occurring in August and September. Biomass burning in Brazil peaks in the same months and likely contributes significantly to elevated concentrations seen in Nickerie. We also compare the observed seasonal cycle to two atmospheric mercury chemistry and transport models (GRAHM and GEOS-Chem). Both models simulate transition between northern and southern hemispheric air, thus capturing the seasonal cycle; however the models overestimate the TGM concentrations during months when Nickerie samples Northern Hemisphere air. It is difficult to determine whether the models' sources or sinks in the Northern Hemisphere tropics are responsible.

Comparison of Health Effects From Exposure to Air Pollution Derived From Combustion of Fossil Fuels and Biomass Burning in Brazil

Comparison of Health Effects From Exposure to Air Pollution Derived From Combustion of Fossil Fuels and Biomass Burning in Brazil

Biomass burning in Brazil's Amazonian “arc of deforestation”: Burning efficiency and charcoal formation in a fire after mechanized clearing at Feliz Natal, Mato Grosso

Estimates of greenhouse-gas emissions from deforestation are highly uncertain because of high variability in key parameters and because of the limited number of studies providing field measurements of these parameters. One such parameter is burning efficiency, which determines how much of the original forest's aboveground carbon stock will be released in the burn, as well as how much will later be released by decay and how much will remain as charcoal. In this paper we examined the fate of biomass from a semideciduous tropical forest in the “arc of deforestation,” where clearing activity is concentrated along the southern edge of the Amazon forest. We estimated carbon content, charcoal formation and burning efficiency by direct measurements (cutting and weighing) and by line-intersect sampling (LIS) done along the axis of each plot before and after burning of felled vegetation. The total aboveground dry biomass found here (219.3 Mg ha −1) is lower than the values found in studies that have been done in other parts of the Amazon region. Values for burning efficiency (65%) and charcoal formation (6.0%, or 5.98 Mg C ha −1) were much higher than those found in past studies in tropical areas. The percentage of trunk biomass lost in burning (49%) was substantially higher than has been found in previous studies. This difference may be explained by the concentration of more stems in the smaller diameter classes and the low humidity of the fuel (the dry season was unusually long in 2007, the year of the burn). This study provides the first measurements of forest burning parameters for a group of forest types that is now undergoing rapid deforestation. The burning parameters estimated here indicate substantially higher burning efficiency than has been found in other Amazonian forest types. Quantification of burning efficiency is critical to estimates of trace-gas emissions from deforestation.

SCIAMACHY CO over land and oceans: 2003–2007 interannual variability

Abstract. We present a new method to obtain accurate SCIAMACHY CO columns over clouded ocean scenes. Based on an improved version of the Iterative Maximum Likelihood Method (IMLM) retrieval algorithm, we now have retrieved five years of data over both land and clouded ocean scenes between 2003 and 2007. The ocean-cloud method uses the CH4 columns retrieved simultaneously with the CO columns to determine the cloud top height. The CH4 cloud top height is in good agreement with the FRESCO+ cloud top height determined from UV-VIS oxygen-A band measurements, providing confidence that the CH4 cloud top height is a good diagnostic of the cloud top height over (partially) clouded ocean scenes. The CO measurements over clouded ocean scenes have been compared with collocated modeled CO columns over the same clouds and agree well. Using clouded ocean scenes quadruples the number of useful CO measurements compared to land-only measurements. The five-year CO data set over land and clouded ocean scenes presented here is based on an improved version of the IMLM algorithm which includes a more accurate determination of the random instrument-noise error for CO. This leads to a smaller spread in the differences between single CO measurements and the corresponding model values. The new version, IMLM version 7.4, also uses updated spectroscopic parameters for H2O and CH4 but this has only a minor impact on the retrieved CO columns. The five-year data set shows significant interannual variability over land and over clouded ocean scenes. Three examples are highlighted: the Asian outflow of pollution over the northern Pacific, the biomass-burning outflow over the Indian Ocean originating from Indonesia, and biomass burning in Brazil. In general there is good agreement between observed and modeled seasonal cycles and interannual variability.

Preface to special section on Yoram J. Kaufman Symposium on Aerosols, Clouds, and Climate

Preface to special section on Yoram J. Kaufman Symposium on Aerosols, Clouds, and Climate

Avian Influenza and UV-B Blocked by Biomass Smoke

Washam (2005) described various poultry inoculation strategies being considered for controlling the spread of avian influenza in Southeast Asia and China. Longini et al. (2005) proposed that a future avian influenza A pandemic might be contained at the source by targeted prophylaxis, quarantine, and prevaccination. Washam (2005) correctly noted that “Asian farmers, though, are running out of options.” I propose a new option: Avian influenza might be controlled by a substantial reduction in regional scale biomass smoke in Southeast Asia that will allow natural solar ultraviolet-B radiation (UV-B) to suppress the virus before infection occurs. Influenza viruses and various non-pigmented bacteria are killed by UV-B wavelengths in sunlight (Hollaender and Oliphant 1944). Biomass smoke significantly suppresses natural levels of UV-B, and severe smoke pollution reduced UV-B by up to 95% during the burning seasons in Brazil in 1995 (Mims 1996) and 1997 (Mims FM III, White B, unpublished data). Reduced UV-B on 6 days in August 1997 was well correlated (r2 = 0.83) with an increase in the ratio of nonpigmented bacteria vulnerable to UV-B to pigmented bacteria that are protected from UV-B (Mims and White 1998). Although airborne influenza viruses were not measured, 1997 hospital admission records at Alta Floresta, Brazil, showed that influenza incidence was highest during the burning season (de Castro GC, personal communication). Human cases of avian influenza in Thailand and Vietnam peaked during the winter burning seasons of 2003 and 2004 (Thailand Ministry of Public Health 2005). Assuming similar optical properties of biomass smoke in Southeast Asia and Brazil, where UV-B and optical depth are highly correlated, optical depth measurements over Thailand and Vietnam by NASA’s Terra and Aqua satellites suggest highly suppressed UV-B during these avian influenza outbreaks (Mims FM III, unpublished data). Human cases of avian influenza in Thailand and Vietnam since December 2003 have peaked during both the rainy season and the burning season. Thus, periods of prolonged cloudiness and severe smoke pollution could play a role in initiating avian and other influenza outbreaks by attenuating the solar UV-B that might otherwise suppress influenza viruses in outdoor air exposed to sunlight. The transmission of avian influenza to people during these periods is enhanced by the fact that poultry raised for human consumption are often kept within several meters of where people live (World Health Organization 2004).

Modeled spectral optical properties for smoke aerosols in Amazonia

The optical properties of aerosols from biomass burning in Brazil were derived from measurements by the AERONET sun photometer network in Amazonia. A dynamical aerosol model was constructed from Mie Theory calculations, using as input a constant complex refractive index and the average size distribution of aerosols for 12 ranges of aerosol optical thickness. The aerosol optical properties were described for 24 wavelengths in the spectral range of 0.20–3.00 μm. The model was used to simulate radiances and irradiances and the results agreed well with the measurements. The derived optical model is immediately applicable to estimate aerosol forcing by biomass burning aerosol emitted on the development frontier in Amazonia.

Estimation of Surface and Top-of-Atmosphere Shortwave Irradiance in Biomass-Burning Regions during SCAR-B

Abstract Using in situ measurements of aerosol optical properties and ground-based measurements of aerosol optical thickness (τs) during the Smoke, Clouds and Radiation—Brazil (SCAR-B) experiment, a four-stream broadband radiative transfer model is used to estimate the downward shortwave irradiance (DSWI) and top-of-atmosphere (TOA) shortwave aerosol radiative forcing (SWARF) in cloud-free regions dominated by smoke from biomass burning in Brazil. The calculated DSWI values are compared with broadband pyranometer measurements made at the surface. The results show that, for two days when near-coincident measurements of single-scattering albedo ω0 and τs are available, the root-mean-square errors between the measured and calculated DSWI for daytime data are within 30 W m−2. For five days during SCAR-B, however, when assumptions about ω0 have to be made and also when τs was significantly higher, the differences can be as large as 100 W m−2. At TOA, the SWARF per unit optical thickness ranges from −20 to −60 W m−2 over four major ecosystems in South America. The results show that τs and ω0 are the two most important parameters that affect DSWI calculations. For SWARF values, surface albedos also play an important role. It is shown that ω0 must be known within 0.05 and τs at 0.55 μm must be known to within 0.1 to estimate DSWI to within 20 W m−2. The methodology described in this paper could serve as a potential strategy for determining DSWI values in the presence of aerosols. The wavelength dependence of τs and ω0 over the entire shortwave spectrum is needed to improve radiative transfer calculations. If global retrievals of DSWI and SWARF from satellite measurements are to be performed in the presence of biomass-burning aerosols on a routine basis, a concerted effort should be made to develop methodologies for estimating ω0 and τs from satellite and ground-based measurements.

Sphericity and morphology of smoke particles from biomass burning in Brazil

The degree of nonsphericity of smoke particles from biomass burning in Brazil was measured aboard the University of Washington C‐131A aircraft during the Smoke, Clouds, and Radiation‐Brazil (SCAR‐B) project for several regions, types of fuel, and combustion. The nonsphericity (αo) of the particles was obtained from electrooptical light‐scattering measurements, using an aerosol asymmetry analyzer, and from scanning electron microscopy (SEM) images of the particles. The electrooptical measurements provide a measure of the nonsphericity based on the difference between the light scattering coefficient for aligned and randomly oriented particles. The SEM photographs provide information on the geometric shapes of the particles. The maximum value of αo obtained during the SCAR‐B for biomass burning in Brazil was below 13%. The degree of nonsphericity of the particles is shown to be related to the combustion efficiency, the mass absorption efficiency, and the fraction of black carbon to total particle mass. It is concluded after smoke particles from biomass burning in Brazil have been in the atmosphere for more than about 1 hour that the spherical approximation (and therefore Mie theory) is reasonably valid for estimating the physical and optical properties of the particles.

Radiative characteristics of regional hazes dominated by smoke from biomass burning in Brazil: Closure tests and direct radiative forcing

Ground‐based Sun photometer measurements, and airborne measurements of the physical and optical properties of regional hazes dominated by smoke from biomass burning in Brazil, are used for aerosol radiative vertical column and local radiative closure tests. Optical depths at midvisible wavelengths of up to 2.5 measured by two independent methods (ground‐based Sun photometers and airborne measurements of the vertical profiles of aerosol optical extinction to the top of the smoke layer) agreed, on average, to within ∼20%. Local aerosol closure tests were carried out using in situ measurements of particle size distributions as inputs to a computational model of the aerosol. Calculated aerosol masses, aerosol absorption and scattering coefficients, and the amounts of solar radiation backscattered by the aerosol were generally within 25% of the measured values. The computational model was used to calculate a broader range of radiative transfer parameters, including aerosol mass scattering and absorption efficiencies, the asymmetry parameter, and upscatter fraction, across the solar spectrum. Regional values of direct aerosol radiative forcing produced by smoke aerosol in the cerrado and primary forest areas of Brazil are derived using the radiative transfer parameters as inputs to a radiative transfer model. The resulting net direct radiative forcing can result in either a cooling or a heating depending on the underlying surface albedo. Over a typical tropical forest the change in the daily average net shortwave flux per unit optical depth (at a wavelength of 550 nm) is −20 ± 7 W m−2 (where a negative value indicates cooling). Over the cerrado the forcing is −8± 9 W m−2, while over a dark surface, such as the ocean, the forcing is −26±6 W m−2. Over a reflective surface, such as a desert, we calculate a positive (heating) forcing of +25±12 W m−2.

Humidification factors of aerosols from biomass burning in Brazil

The light‐scattering coefficient of aerosols from biomass burning was measured as a function of relative humidity (RH) and wavelength in four regions of Brazil extending from the cerrado to the primary forests of the Amazon Basin. At a wavelength of 550 nm the ratio of the light‐scattering coefficient at a RH of 80% to that at an RH of 30% ranged from 1.01 to 1.51, with an average value of 1.16. The aerosol backscatter ratio as a function of RH decreased by 10 to 20% as the RH was increased from 30 to 80%. Measurements of the geometric growth of the aerosol with RH were consistent with the measured changes in light scattering. Use of these new measurements yields an estimate for the globally averaged direct radiative forcing by biomass burning aerosol of about 0.25 W m−2.

Effects of black carbon content, particle size, and mixing on light absorption by aerosols from biomass burning in Brazil

Black carbon mass absorption efficiencies of smoke particles were measured for various types of biomass fires during the Smoke, Clouds, and Radiation‐Brazil (SCAR‐B) experiment using thermal evolution measurements for black carbon and optical absorption methods. The obtained results range between 5.2 and 19.3 m2 g−1 with an average value of 12.1±4.0 m2 g−1. Particle size distributions and optical properties were also measured to provide a full set of physical parameters for modeling calculations. Mie theory was used to model the optical properties of the particles assuming both internal and external mixtures coupling the modeling calculations with the experimental results obtained during the campaign. For internal mixing, a particle model with a layered structure consisting of an absorbing black carbon core, surrounded by a nonabsorbing shell, was assumed. Also, for internal mixing, a discrete dipole approximation code was used to simulate packed soot clusters commonly found in electron microscopy photographs of filters collected during the experiment. The modeled results for layered spheres and packed clusters explain black carbon mass absorption coefficients up to values of about 25 m2 g−1, but measurements show even higher values which were correlated with the chemical composition and characteristics of the structure of the particles. Unrealistic high values of black carbon absorption efficiencies were linked to high concentrations of K, which influence the volatilization of black carbon (BC) at lower temperatures than usual, possibly causing artifacts in the determination of BC by thermal technique. The modeling results are compared with nephelometer and light absorption measurements.

Comparisons of techniques for measuring shortwave absorption and black carbon content of aerosols from biomass burning in Brazil

Six methods for measuring the shortwave absorption and/or black carbon (BC) content of aerosols from biomass burning were compared during the Smoke, Clouds, and Radiation‐Brazil (SCAR‐B) experiment. The methods were the optical extinction cell (OEC), integrating plate (IP), optical reflectance (OR), particle soot/absorption photometer (PSAP), thermal evolution (TE), and remote sensing (RS). Comparisons were made for individual smoke plumes and for regional hazes dominated by smoke. Taking the OEC as a primary standard, measurements of the absorption coefficient (σa) showed that the OR method had the lowest uncertainty (17%) in σa. The other optical methods had uncertainties ranging from 20 to 40%. However, with sufficient sample size, the values of σa derived from the optical methods converged to within 20% of each other. For biomass burning aerosols in regional hazes over Brazil, this led to systematic differences of ±0.02 in the values of the single‐scattering albedo derived from the various in situ techniques. It was found also that the BC content of the aerosol and σa were poorly correlated. This is likely due to a large uncertainty in the BC content of the aerosol measured by TE, and/or a high variability in the mass absorption efficiency of BC in biomass burning aerosol. Hence there is a high uncertainty in inferring σa from the BC content of smoke aerosol.

Emission factors of hydrocarbons, halocarbons, trace gases and particles from biomass burning in Brazil

Airborne measurements of the emissions of gases and particles from 19 individual forest, cerrado, and pasture fires in Brazil were obtained during the Smoke, Clouds, and Radiation‐Brazil (SCAR‐B) study in August‐September 1995. Emission factors were determined for a number of major and minor gaseous and particulate species, including carbon dioxide, carbon monoxide, sulfur dioxide, nitrogen oxides, methane, nonmethane hydrocarbons, halocarbons, particulate (black and organic) carbon, and particulate ionic species. The magnitude of the emission factors for gaseous species were determined primarily by the relative amounts of flaming and smoldering combustion, rather than differences in vegetation type. Hydrocarbons and halocarbons were well correlated with CO, which is indicative of emissions primarily associated with smoldering combustion. Although there was large variability between fires, higher emission factors for SO2and NOχwere associated with an increased ratio of flaming to smoldering combustion; this could be due to variations in the amounts of sulfur and nitrogen in the fuels. Emission factors for particles were not so clearly associated with smoldering combustion as those for hydrocarbons. The emission factors measured in this study are similar to those measured previously in Brazil and Africa. However, particle emission factors from fires in Brazil appear to be roughly 20 to 40% lower than those from North American boreal forest fires.

Direct Radiative Forcing by Smoke from Biomass Burning

Airborne measurements in smoke from biomass burning in Brazil have yielded optical parameters that permit an improved assessment of the effects of smoke on Earth's radiation balance. The global-mean direct radiative forcing due to smoke from biomass burning worldwide is estimated to be no more than about -0.3 watt per square meter (cooling), compared with +2.45 watts per square meter (warming) due to anthropogenic greenhouse gases. On regional scales, direct radiative forcing due to smoke can be large and might indirectly affect global climate.

Significant reduction of UVB caused by smoke from biomass burning in Brazil.

Solar UVB radiation, total ozone and the aerosol optical thickness (AOT) of the atmosphere were measured at various sites in Brazil during season of 1995. Smoke from biomass burning caused very significant AOT and up to an 81% reduction in UVB at Cuiabá, hundreds of kilometers from the most widespread burning. Little or no smoke was apparent upwind of the major burning regions at and near Manaus, and UVB was close to the expected values. There is an increased incidence of respiratory, cardiopulmonary and other diseases associated with severe air pollution, but the responsible biological mechanisms are unknown. The bactericidal effects of solar UVB are well known, and significantly reduced UVB resulting from severe air pollution in regions where UVB levels are ordinarily high might enhance the survivability of pathogenic organisms in air and water and on surfaces exposed to sunlight.

Hydrocarbon and carbon monoxide emissions from biomass burning in Brazil

Field measurements of hydrocarbon emissions from biomass burning in the cerrado (grasslands) and selva (tropical forest) regions of Brazil in 1979 and 1980 are characterized and quantified here. Regional consequences of burning activities include increased background mixing ratios of carbon monoxide and ozone, as well as reduced visibility, over extensive areas. Global extrapolation of the emission rate of hydrocarbons from these fires indicates that 6×1013 g C of gas phase hydrocarbons and 8×1014 g CO may be released annually from biomass burning. These emissions contribute significantly to the global budgets of hydrocarbons and carbon monoxide.