8 research outputs found
Chemical Fingerprinting of Biomass Burning Organic Aerosols from Sugar Cane Combustion: Complementary Findings from Field and Laboratory Studies
Agricultural fires are a major source of biomass-burning
organic
aerosols (BBOAs) with impacts on health, the environment, and climate.
In this study, globally relevant BBOA emissions from the combustion
of sugar cane in both field and laboratory experiments were analyzed
using comprehensive two-dimensional gas chromatography time-of-flight
mass spectrometry. The derived chemical fingerprints of fresh emissions
were evaluated using targeted and nontargeted evaluation approaches.
The open-field sugar cane burning experiments revealed the high chemical
complexity of combustion emissions, including compounds derived from
the pyrolysis of (hemi)cellulose, lignin, and further biomass, such
as pyridine and oxime derivatives, methoxyphenols, and methoxybenzenes,
as well as triterpenoids. In comparison, laboratory experiments could
only partially model the complexity of real combustion events. Our
results showed high variability between the conducted field and laboratory
experiments, which we, among others, discuss in terms of differences
in combustion conditions, fuel composition, and atmospheric processing.
We conclude that both field and laboratory studies have their merits
and should be applied complementarily. While field studies under real-world
conditions are essential to assess the general impact on air quality,
climate, and environment, laboratory studies are better suited to
investigate specific emissions of different biomass types under controlled
conditions
Effective Density and Morphology of Particles Emitted from Small-Scale Combustion of Various Wood Fuels
The effective density
of fine particles emitted from small-scale
wood combustion of various fuels were determined with a system consisting
of an aerosol particle mass analyzer and a scanning mobility particle
sizer (APM-SMPS). A novel sampling chamber was combined to the system
to enable measurements of highly fluctuating combustion processes.
In addition, mass-mobility exponents (relates mass and mobility size)
were determined from the density data to describe the shape of the
particles. Particle size, type of fuel, combustion phase, and combustion
conditions were found to have an effect on the effective density and
the particle shape. For example, steady combustion phase produced
agglomerates with effective density of roughly 1 g cm<sup>–3</sup> for small particles, decreasing to 0.25 g cm<sup>–3</sup> for 400 nm particles. The effective density was higher for particles
emitted from glowing embers phase (ca. 1–2 g cm<sup>–3</sup>), and a clear size dependency was not observed as the particles
were nearly spherical in shape. This study shows that a single value
cannot be used for the effective density of particles emitted from
wood combustion
Photochemical Aging Induces Changes in the Effective Densities, Morphologies, and Optical Properties of Combustion Aerosol Particles
Effective density (ρeff) is an important
property
describing particle transportation in the atmosphere and in the human
respiratory tract. In this study, the particle size dependency of
ρeff was determined for fresh and photochemically
aged particles from residential combustion of wood logs and brown
coal, as well as from an aerosol standard (CAST) burner. ρeff increased considerably due to photochemical aging, especially
for soot agglomerates larger than 100 nm in mobility diameter. The
increase depends on the presence of condensable vapors and agglomerate
size and can be explained by collapsing of chain-like agglomerates
and filling of their voids and formation of secondary coating. The
measured and modeled particle optical properties suggest that while
light absorption, scattering, and the single-scattering albedo of
soot particle increase during photochemical processing, their radiative
forcing remains positive until the amount of nonabsorbing coating
exceeds approximately 90% of the particle mass
Photochemical Aging Induces Changes in the Effective Densities, Morphologies, and Optical Properties of Combustion Aerosol Particles
Effective density (ρeff) is an important
property
describing particle transportation in the atmosphere and in the human
respiratory tract. In this study, the particle size dependency of
ρeff was determined for fresh and photochemically
aged particles from residential combustion of wood logs and brown
coal, as well as from an aerosol standard (CAST) burner. ρeff increased considerably due to photochemical aging, especially
for soot agglomerates larger than 100 nm in mobility diameter. The
increase depends on the presence of condensable vapors and agglomerate
size and can be explained by collapsing of chain-like agglomerates
and filling of their voids and formation of secondary coating. The
measured and modeled particle optical properties suggest that while
light absorption, scattering, and the single-scattering albedo of
soot particle increase during photochemical processing, their radiative
forcing remains positive until the amount of nonabsorbing coating
exceeds approximately 90% of the particle mass
Experimental set-up and global omics analyses.
<p>(A) An 80 KW common-rail-ship diesel engine was operated with heavy fuel oil (HFO) or refined diesel fuel (DF). The exhaust aerosols were diluted and cooled with clean air. On-line real-time mass spectrometry, particle-sizing, sensor IR-spectrometry and other techniques were used to characterise the chemical composition and physical properties of the particles and gas phase. Filter sampling of the particulate matter (PM) was performed to further characterise the PM composition. Lung cells were synchronously exposed at the air-liquid-interface (ALI) to aerosol or particle-filtered aerosol as a reference. The cellular responses were characterised in triplicate at the transcriptome (BEAS-2B), proteome and metabolome (A549) levels with stable isotope labelling (SILAC and <sup>13</sup>C<sub>6</sub>-glucose). (B) Heatmap showing the global regulation of the transcriptome, proteome and metabolome.</p
Chemical and physical aerosol characterisation.
<p>(A) The ship diesel engine was operated for 4 h in accordance with the IMO-test cycle. (B) Approximately 28 ng/cm<sup>2</sup> and 56 ng/cm<sup>2</sup> were delivered to the cells from DF and HFO, respectively, with different size distributions. The HFO predominantly contained particles <50 nm, and the DF predominantly contained particles >200 nm, both in mass and number. (C) Number of chemical species in the EA particles. (D) Transmission electron microscope (TEM) images and energy-dispersive X-ray (EDX) spectra of DF-EA and HFO-EA; heavy elements (black speckles, arrow); and contributions of the elements V, P, Fe and Ni in the HFO particles using EDX (* = grid-material). (E) Exemplary EA concentrations (right) and concentration ratios (left) for particulate matter-bound species. For all experiments, n = 3.</p
Summary of the main HFO- and DF-particle exposure effects.
<p>The arrows indicate the direction of regulation for cellular functions derived from the most statistically significant enriched Gene Ontology terms from the transcriptome, proteome, and metabolome (details in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0126536#pone.0126536.s012" target="_blank">S2 Table</a>).</p><p><sup>x</sup> BEAS-2B up, A549 down</p><p>* BEAS-2B down, A549 up</p><p>Summary of the main HFO- and DF-particle exposure effects.</p
Effects of shipping particles on lung cells.
<p>The net effects from the particles were referenced against the gaseous phase of the emissions. (A) Number of the regulated components in the transcriptome shows more genes regulated by the DF than the HFO particles (in BEAS-2B cells). Similar results were observed for the proteome (B) and metabolome (C) (in A549 cells). (D) Meta-analyses for the transcriptome and proteome using the combined Gene Ontology (GO) term analysis of the 10% most regulated transcripts and proteins. Individual GO terms are listed in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0126536#pone.0126536.s012" target="_blank">S2 Table</a>; the hierarchical pathways are indicated on the right. (E) Gene regulation of Wiki-pathway bioactivation; (F) gene regulation of Wiki-pathway inflammation; g, secreted metabolites; and h, metabolic flux measurements using <sup>13</sup>C-labelled glucose. For all experiments, n = 3.</p