Size distribution and hygroscopic properties of aerosol particles from dry-season biomass burning in Amazonia

Abstract. Aerosol particle number size distributions and hygroscopic properties were measured at a pasture site in the southwestern Amazon region (Rondonia). The measurements were performed 11 September-14 November 2002 as part of LBA-SMOCC (Large scale Biosphere atmosphere experiment in Amazonia - SMOke aerosols, Clouds, rainfall and Climate), and cover the later part of the dry season (with heavy biomass burning), a transition period, and the onset of the wet period. Particle number size distributions were measured with a DMPS (Differential Mobility Particle Sizer, 3-850nm) and an APS (Aerodynamic Particle Sizer), extending the distributions up to 3.3 µm in diameter. An H-TDMA (Hygroscopic Tandem Differential Mobility Analyzer) measured the hygroscopic diameter growth factors (Gf) at 90% relative humidity (RH), for particles with dry diameters (dp) between 20-440 nm, and at several occasions RH scans (30-90% RH) were performed for 165nm particles. These data provide the most extensive characterization of Amazonian biomass burning aerosol, with respect to particle number size distributions and hygroscopic properties, presented until now. The evolution of the convective boundary layer over the course of the day causes a distinct diel variation in the aerosol physical properties, which was used to get information about the properties of the aerosol at higher altitudes. The number size distributions averaged over the three defined time periods showed three modes; a nucleation mode with geometrical median diameters (GMD) of ~12 nm, an Aitken mode (GMD=61-92 nm) and an accumulation mode (GMD=128-190 nm). The two larger modes were shifted towards larger GMD with increasing influence from biomass burning. The hygroscopic growth at 90% RH revealed a somewhat external mixture with two groups of particles; here denoted nearly hydrophobic (Gf~1.09 for 100 nm particles) and moderately hygroscopic (Gf~1.26). While the hygroscopic growth factors were surprisingly similar over the periods, the number fraction of particles belonging to each hygroscopic group varied more, with the dry period aerosol being more dominated by nearly hydrophobic particles. As a result the total particle water uptake rose going into the cleaner period. The fraction of moderately hygroscopic particles was consistently larger for particles in the accumulation mode compared to the Aitken mode for all periods. Scanning the H-TDMA over RH (30-90% RH) showed no deliquescence behavior. A parameterization of both Gf(RH) and Gf(dp), is given.

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Biogenic cloud nuclei in the central Amazon during the transition from wet to dry season

Atmospheric Chemistry and Physics ◽

10.5194/acp-16-9727-2016 ◽

2016 ◽

Vol 16 (15) ◽

pp. 9727-9743 ◽

Cited By ~ 17

Author(s):

James D. Whitehead ◽

Eoghan Darbyshire ◽

Joel Brito ◽

Henrique M. J. Barbosa ◽

Ian Crawford ◽

...

Keyword(s):

Biomass Burning ◽

Transition Period ◽

Aerosol Particles ◽

Dry Season ◽

Atmospheric Composition ◽

Size Distributions ◽

Wet Season ◽

Accumulation Mode ◽

Coarse Mode ◽

Biological Aerosol Particles

Abstract. The Amazon basin is a vast continental area in which atmospheric composition is relatively unaffected by anthropogenic aerosol particles. Understanding the properties of the natural biogenic aerosol particles over the Amazon rainforest is key to understanding their influence on regional and global climate. While there have been a number of studies during the wet season, and of biomass burning particles in the dry season, there has been relatively little work on the transition period – the start of the dry season in the absence of biomass burning. As part of the Brazil–UK Network for Investigation of Amazonian Atmospheric Composition and Impacts on Climate (BUNIAACIC) project, aerosol measurements, focussing on unpolluted biogenic air masses, were conducted at a remote rainforest site in the central Amazon during the transition from wet to dry season in July 2013. This period marks the start of the dry season but before significant biomass burning occurs in the region. Median particle number concentrations were 266 cm−3, with size distributions dominated by an accumulation mode of 130–150 nm. During periods of low particle counts, a smaller Aitken mode could also be seen around 80 nm. While the concentrations were similar in magnitude to those seen during the wet season, the size distributions suggest an enhancement in the accumulation mode compared to the wet season, but not yet to the extent seen later in the dry season, when significant biomass burning takes place. Submicron nonrefractory aerosol composition, as measured by an aerosol chemical speciation monitor (ACSM), was dominated by organic material (around 81 %). Aerosol hygroscopicity was probed using measurements from a hygroscopicity tandem differential mobility analyser (HTDMA), and a quasi-monodisperse cloud condensation nuclei counter (CCNc). The hygroscopicity parameter, κ, was found to be low, ranging from 0.12 for Aitken-mode particles to 0.18 for accumulation-mode particles. This was consistent with previous studies in the region, but lower than similar measurements conducted in Borneo, where κ ranged 0.17–0.37. A wide issue bioaerosol sensor (WIBS-3M) was deployed at ground level to probe the coarse mode, detecting primary biological aerosol by fluorescence (fluorescent biological aerosol particles, or FBAPs). The mean FBAP number concentration was 400 ± 242 L−1; however, this ranged from around 200 L−1 during the day to as much as 1200 L−1 at night. FBAPs dominated the coarse-mode particles, comprising between 55 and 75 % of particles during the day to more than 90 % at night. Non-FBAPs did not show a strong diurnal pattern. Comparison with previous FBAP measurements above canopy at the same location suggests there is a strong vertical gradient in FBAP concentrations through the canopy. Cluster analysis of the data suggests that FBAPs were dominated (around 70 %) by fungal spores. Further, long-term measurements will be required in order to fully examine the seasonal variability and distribution of primary biological aerosol particles through the canopy. This is the first time that such a suite of measurements has been deployed at this site to investigate the chemical composition and properties of the biogenic contributions to Amazonian aerosol during the transition period from the wet to the dry season, and thus provides a unique comparison to the aerosol properties observed during the wet season in previous similar campaigns. This was also the first deployment of a WIBS in the Amazon rainforest to study coarse-mode particles, particularly primary biological aerosol particles, which are likely to play an important role as ice nuclei in the region.

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Fluorescent biological aerosol particle concentrations and size distributions measured with an Ultraviolet Aerodynamic Particle Sizer (UV-APS) in Central Europe

Atmospheric Chemistry and Physics ◽

10.5194/acp-10-3215-2010 ◽

2010 ◽

Vol 10 (7) ◽

pp. 3215-3233 ◽

Cited By ~ 159

Author(s):

J. A. Huffman ◽

B. Treutlein ◽

U. Pöschl

Keyword(s):

Particle Number ◽

Fungal Spores ◽

Number Concentration ◽

Size Distributions ◽

Bacterial Cells ◽

Spores And Pollen ◽

Measurement Results ◽

The Mean ◽

Particle Sizer ◽

Biological Aerosol Particles

Abstract. Primary Biological Aerosol Particles (PBAPs), including bacteria, spores and pollen, are essential for the spread of organisms and disease in the biosphere, and numerous studies have suggested that they may be important for atmospheric processes, including the formation of clouds and precipitation. The atmospheric abundance and size distribution of PBAPs, however, are largely unknown. At a semi-urban site in Mainz, Germany we used an Ultraviolet Aerodynamic Particle Sizer (UV-APS) to measure Fluorescent Biological Aerosol Particles (FBAPs), which provide an estimate of viable bioaerosol particles and can be regarded as an approximate lower limit for the actual abundance of PBAPs. Fluorescence of non-biological aerosol components are likely to influence the measurement results obtained for fine particles (<1 μm), but not for coarse particles (1–20 μm). Averaged over the four-month measurement period (August–December 2006), the mean number concentration of coarse FBAPs was ~3×10−2 cm−3, corresponding to ~4% of total coarse particle number. The mean mass concentration of FBAPs was ~1μg m−3, corresponding to ~20% of total coarse particle mass. The FBAP number size distributions exhibited alternating patterns with peaks at various diameters. A pronounced peak at ~3 μm was essentially always observed and can be described by the following campaign-average lognormal fit parameters: geometric mean diameter 3.2 μm, geometric standard deviation 1.3, number concentration 1.6×10−2 cm−3. This peak is likely due to fungal spores or agglomerated bacteria, and it exhibited a pronounced diel cycle (24-h) with maximum intensity during early/mid-morning. FBAP peaks around ~1.5 μm, ~5 μm, and ~13 μm were also observed, but less pronounced and less frequent. These may be single bacterial cells, larger fungal spores, and pollen grains, respectively. The observed number concentrations and characteristic sizes of FBAPs are consistent with microscopic, biological and chemical analyses of PBAPs in aerosol filter samples. To our knowledge, however, this is the first exploratory study reporting continuous online measurements of bioaerosol particles over several months and a range of characteristic size distribution patterns with a persistent bioaerosol peak at ~3 μm. The measurement results confirm that PBAPs account for a substantial proportion of coarse aerosol particle number and mass in continental boundary layer air. Moreover, they suggest that the number concentration of viable bioparticles is dominated by fungal spores or agglomerated bacteria with aerodynamic diameters around 3 μm rather than single bacterial cells with diameters around 1 μm.

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Measurement of nonvolatile particle number size distribution

Atmospheric Measurement Techniques ◽

10.5194/amt-9-103-2016 ◽

2016 ◽

Vol 9 (1) ◽

pp. 103-114 ◽

Cited By ~ 14

Author(s):

G. I. Gkatzelis ◽

D. K. Papanastasiou ◽

K. Florou ◽

C. Kaltsonoudis ◽

E. Louvaris ◽

...

Keyword(s):

Size Distribution ◽

Black Carbon ◽

Biomass Burning ◽

Particle Number ◽

Number Concentration ◽

Experimental Methodology ◽

Particle Number Concentration ◽

Scanning Mobility Particle Sizer ◽

Number Size Distribution ◽

Particle Sizer

Abstract. An experimental methodology was developed to measure the nonvolatile particle number concentration using a thermodenuder (TD). The TD was coupled with a high-resolution time-of-flight aerosol mass spectrometer, measuring the chemical composition and mass size distribution of the submicrometer aerosol and a scanning mobility particle sizer (SMPS) that provided the number size distribution of the aerosol in the range from 10 to 500 nm. The method was evaluated with a set of smog chamber experiments and achieved almost complete evaporation (> 98 %) of secondary organic as well as freshly nucleated particles, using a TD temperature of 400 °C and a centerline residence time of 15 s. This experimental approach was applied in a winter field campaign in Athens and provided a direct measurement of number concentration and size distribution for particles emitted from major pollution sources. During periods in which the contribution of biomass burning sources was dominant, more than 80 % of particle number concentration remained after passing through the thermodenuder, suggesting that nearly all biomass burning particles had a nonvolatile core. These remaining particles consisted mostly of black carbon (60 % mass contribution) and organic aerosol (OA; 40 %). Organics that had not evaporated through the TD were mostly biomass burning OA (BBOA) and oxygenated OA (OOA) as determined from AMS source apportionment analysis. For periods during which traffic contribution was dominant 50–60 % of the particles had a nonvolatile core while the rest evaporated at 400 °C. The remaining particle mass consisted mostly of black carbon with an 80 % contribution, while OA was responsible for another 15–20 %. Organics were mostly hydrocarbon-like OA (HOA) and OOA. These results suggest that even at 400 °C some fraction of the OA does not evaporate from particles emitted from common combustion processes, such as biomass burning and car engines, indicating that a fraction of this type of OA is of extremely low volatility.

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Multi-year statistical and modelling analysis of submicrometer aerosol number size distributions at a rain forest site in Amazonia

10.5194/acp-2018-55 ◽

2018 ◽

Author(s):

Luciana Varanda Rizzo ◽

Pontus Roldin ◽

Joel Brito ◽

John Backman ◽

Erik Swietlicki ◽

...

Keyword(s):

Particle Size ◽

Rain Forest ◽

Amazon Basin ◽

Particle Number ◽

Dry Season ◽

Forest Site ◽

Size Distributions ◽

Wet Season ◽

Accumulation Mode ◽

Aitken Mode

Abstract. The Amazon Basin is a unique region to study atmospheric aerosols, given their relevance for the regional hydrological cycle and large uncertainty of their sources. Multi-year datasets are crucial when contrasting periods of natural conditions and periods influenced by anthropogenic emissions. In the wet season, biogenic sources and processes prevail, and the Amazonian atmospheric composition resembles pre-industrial conditions. In the dry season, the Basin is influenced by widespread biomass burning emissions. This work reports multi-year observations of high time resolution submicrometer (10–600 nm) particle number size distributions at a rain forest site in Amazonia (TT34 tower, 60 km NW from Manaus city), between years 2008–2010 and 2012–2014. Median particle number concentration was 403 cm−3 in the wet season and 1254 cm−3 in the dry season. The Aitken mode (~ 30–100 nm in diameter) was prominent during the wet season, while accumulation mode (~ 100–600 nm in diameter) dominated the particle size spectra during the dry season. Cluster analysis identified groups of aerosol number size distribution influenced by convective downdrafts, nucleation events and fresh biomass burning emissions. New particle formation and subsequent growth was rarely observed during the 749 days of observations, similar to previous observations in the Amazon Basin. A stationary 1D column model (ADCHEM – Aerosol Dynamics, gas and particle phase CHEMistry and radiative transfer model) was used to assess importance of processes behind the observed diurnal particle size distribution trends. Three major particle source types are required in the model to reproduce the observations: (i) a surface source of particles in the evening, possibly related to primary biological emissions (ii) entrainment of accumulation mode aerosols in the morning, and (iii) convective downdrafts transporting Aitken mode particles into the boundary layer mostly during the afternoon. The latter process has the largest influence on the modelled particle number size distributions. However, convective downdrafts are often associated with rain and thus act both as a source of Aitken mode particles, and as a sink of accumulation mode particles, causing a net reduction in the median total particle number concentrations in the surface layer. Our study shows that the combination of the three mentioned particle sources are essential to sustain particle number concentrations in Amazonia.

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Physical properties of the sub-micrometer aerosol over the Amazon rain forest during the wet-to-dry season transition - comparison of modeled and measured CCN concentrations

Atmospheric Chemistry and Physics ◽

10.5194/acp-4-2119-2004 ◽

2004 ◽

Vol 4 (8) ◽

pp. 2119-2143 ◽

Cited By ~ 123

Author(s):

J. Rissler ◽

E. Swietlicki ◽

J. Zhou ◽

G. Roberts ◽

M. O. Andreae ◽

...

Keyword(s):

Size Distribution ◽

Biomass Burning ◽

Time Resolution ◽

Large Scale ◽

Transition Period ◽

Cloud Condensation Nuclei ◽

Particle Diameter ◽

Hygroscopic Growth ◽

Condensation Nuclei ◽

Number Size Distribution

Abstract. Sub-micrometer atmospheric aerosol particles were studied in the Amazon region, 125 km northeast of Manaus, Brazil (-1°55.2'S, 59°28.1'W). The measurements were performed during the wet-to-dry transition period, 4-28 July 2001 as part of the LBA (Large-Scale Biosphere Atmosphere Experiment in Amazonia) CLAIRE-2001 (Cooperative LBA Airborne Regional Experiment) experiment. The number size distribution was measured with two parallel differential mobility analyzers, the hygroscopic growth at 90% RH with a Hygroscopic Tandem Mobility Analyzer (H-TDMA) and the concentrations of cloud condensation nuclei (CCN) with a cloud condensation nuclei counter. A model was developed that uses the H-TDMA data to predict the number of soluble molecules or ions in the individual particles and the corresponding minimum particle diameter for activation into a cloud droplet at a certain supersaturation. Integrating the number size distribution above this diameter, CCN concentrations were predicted with a time resolution of 10 min and compared to the measured concentrations. During the study period, three different air masses were identified and compared: clean background, air influenced by aged biomass burning, and moderately polluted air from recent local biomass burning. For the clean period 2001, similar number size distributions and hygroscopic behavior were observed as during the wet season at the same site in 1998, with mostly internally mixed particles of low diameter growth factor (~1.3 taken from dry to 90% RH). During the periods influenced by biomass burning the hygroscopic growth changed slightly, but the largest difference was seen in the number size distribution. The CCN model was found to be successful in predicting the measured CCN concentrations, typically within 25%. A sensitivity study showed relatively small dependence on the assumption of which model salt that was used to predict CCN concentrations from H-TDMA data. One strength of using H-TDMA data to predict CCN concentrations is that the model can also take into account soluble organic compounds, insofar as they go into solution at 90% RH. Another advantage is the higher time resolution compared to using size-resolved chemical composition data.

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Seasonality of greenhouse gas emission factors from biomass burning in the Brazilian Cerrado

10.5194/bg-2020-86 ◽

2020 ◽

Author(s):

Roland Vernooij ◽

Marcos Vinicius Giongo Alves ◽

Marco Assis Borges ◽

Máximo Menezes Costa ◽

Ana Carolina Sena Barradas ◽

...

Keyword(s):

Greenhouse Gases ◽

Greenhouse Gas ◽

Biomass Burning ◽

Large Scale ◽

Greenhouse Gas Emission ◽

Emission Factors ◽

Dry Season ◽

Total Carbon ◽

Vegetation Types ◽

Gas Emission

Abstract. Landscape fires, often referred to as biomass burning (BB), emit substantial amounts of (greenhouse) gases and aerosols into the atmosphere each year. Frequently burning savannas, mostly in Africa, Australia, and South America are responsible for over 60 % of total BB carbon emissions. Compared to many other sources of emissions, fires have a strong seasonality. Previous research has identified the mitigation potential of prescribed fires in savanna ecosystems; by burning early in the dry season when the vegetation has not fully cured, fires are in general patchier and burn less intense. While it is widely accepted that burned area and the total carbon consumed is lower when fires are ignited early in the dry season, little is known about the seasonality of emission factors (EF) of greenhouse gases. This is important because potentially, higher EFs in the early dry season (EDS) could offset some of the carbon benefits of EDS burning. Also, a better understanding of EF seasonality may improve large-scale BB assessments, which to date rely on temporally-static EFs. We used a sampling system mounted on an unmanned aerial vehicle (UAV) and cavity ring-down spectroscopy to estimate CO2, CO, CH4, and N2O EFs in the Estação Ecológica Serra Geral do Tocantins in the Brazilian states of Tocantins and Bahia. The protected area contains all major Cerrado vegetation types found in Brazil, and EDS burning was implemented on a large scale since 2014. We collected and analyzed over 800 smoke samples during the EDS and late dry season (LDS). Averaged over all measurements, the modified combustion efficiency (MCE) was slightly higher in the LDS (0.976 vs. 0.972) and the CH4 and CO EFs were 13 % and 15 % lower in the LDS compared to the EDS. This seasonal effect was larger in more wood-dominated vegetation types. N2O EFs showed a more complex seasonal dependency, with opposite seasonal trends for savannas that were dominated by grasses versus those with abundant shrubs. We found that the N2O EF for the open cerrado was less than half of those reported so far in the BB literature for savannas. This may indicate a substantial overestimation of the contribution of fires in the N2O budget. Overall, our data implies that in this region, seasonal variability in greenhouse gas emission factors may offset only a small fraction of the carbon mitigation gains in fire abatement programs.

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Landfill air pollution by ultrafine and microparticles in case of dry and windless weather conditions

Detritus ◽

10.31025/2611-4135/2020.13913 ◽

2020 ◽

pp. 139-146

Author(s):

Emília Hroncová ◽

Juraj Ladomerský ◽

Denisa Ladomerská

Keyword(s):

Ultrafine Particles ◽

Large Scale ◽

Particle Number ◽

Fine Particles ◽

Weather Conditions ◽

Municipal Waste ◽

Dust Particles ◽

Particle Sizer ◽

Ultra Fine Particles ◽

Surprising Finding

In the present article we give the results for ultra-fine particles and microparticles at a landfill of municipal waste, taking into consideration various factors. The landfill is a large-scale source of dust. There is little knowledge in terms of fractional composition of dust particles. We have performed concentration measurements of the number of ultrafine (10 to 100 nm) and microparticles (0.1 to 10 μm) in the field conditions of the municipal waste landfill using the TSI Technique (Optical particle sizer 3330 and Nanoscan SMPS nanoparticle sizer 3919). The particle number concentration in the atmosphere in case of dry and windless weather conditions at the landfill was in the range of about 2,500 to 5,500 of ultrafine particles per cm3. The mass concentrations of the microparticles was in the range of 29 to 163 μg.m-3 (assuming ρ=1 g.cm-3). There was an evident trend of increase of concentration of the ultrafine particles and microparticles in the lower location of the landfill occuring in the case of dry and windless weather conditions. The surprising finding was that passing haulage vehicles and in particular the operation of the compactor increase the mass concentration of microparticles, but they do not increase the concentration of the number of microparticles or even of ultrafine particles.

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Water Uptake by Fresh Indonesian Peat Burning Particles is Limited by Water Soluble Organic Matter

10.5194/acp-2017-136 ◽

2017 ◽

Author(s):

Jing Chen ◽

Sri Hapsari Budisulistiorini ◽

Masayuki Itoh ◽

Wen-Chien Lee ◽

Takuma Miyakawa ◽

...

Keyword(s):

Organic Matter ◽

Water Uptake ◽

Biomass Burning ◽

Water Soluble ◽

Chemical Characteristics ◽

Soluble Organic Matter ◽

Differential Mobility Analyzer ◽

Differential Mobility ◽

Hygroscopic Properties ◽

The Relationship

Abstract. The relationship between hygroscopic properties and chemical characteristics of Indonesian biomass burning (BB) particles, which are dominantly generated from peatland fires, was investigated using the humidified tandem differential mobility analyzer. In addition to peat, acacia (a popular species at plantation) and fern (a pioneering species after disturbance by fire) were used for experiments. Fresh Indonesian peat burning particles are almost non-hygroscopic (mean hygroscopicity parameter, κ

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Notably improved inversion of differential mobility particle sizer data obtained under conditions of fluctuating particle number concentrations

Atmospheric Measurement Techniques ◽

10.5194/amt-9-741-2016 ◽

2016 ◽

Vol 9 (2) ◽

pp. 741-751

Author(s):

Bjarke Mølgaard ◽

Jarno Vanhatalo ◽

Pasi P. Aalto ◽

Nønne L. Prisle ◽

Kaarle Hämeri

Keyword(s):

Size Distribution ◽

Particle Number ◽

Distribution Data ◽

Inversion Algorithm ◽

Differential Mobility ◽

Condensation Particle Counter ◽

Prior Probabilities ◽

Positive Correlations ◽

Particle Sizer

Abstract. The differential mobility particle sizer (DMPS) is designed for measurements of particle number size distributions. It performs a number of measurements while scanning over different particle sizes. A standard assumption in the data-processing (inversion) algorithm is that the size distribution remains the same throughout each scan. For a DMPS deployed in an urban area this assumption is likely to be violated most of the time, and the resulting size distribution data are unreliable. To improve the reliability, we developed a new algorithm using a statistical model in which the problematic assumption was replaced with more realistic smoothness assumptions, which were expressed through Gaussian process prior probabilities. We tested the model with data from a twin DMPS located at an urban background site in Helsinki and found that it provides size distribution data which are much more realistic. Furthermore, particle number concentrations extracted from the DMPS data were compared with data from a condensation particle counter. At 10 min resolution, the correlation for a period of 10 days was 0.984 with the new algorithm and 0.967 with the old one. Moreover, the time resolution was improved, and at 30 s resolution we obtained positive correlations for 89 % of the scans. Thus, the quality of the inverted data was clearly improved.

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