Polar organic marker compounds in atmospheric aerosols during the LBA-SMOCC 2002 biomass burning experiment in Rondônia, Brazil: sources and source processes, time series, diel variations and size distributions

Abstract. Measurements of polar organic marker compounds were performed on aerosols that were collected at a pasture site in the Amazon basin (Rondônia, Brazil) using a high-volume dichotomous sampler (HVDS) and a Micro-Orifice Uniform Deposit Impactor (MOUDI) within the framework of the 2002 LBA-SMOCC (Large-Scale Biosphere Atmosphere Experiment in Amazônia – Smoke Aerosols, Clouds, Rainfall, and Climate: Aerosols From Biomass Burning Perturb Global and Regional Climate) campaign. The campaign spanned the late dry season (biomass burning), a transition period, and the onset of the wet season (clean conditions). In the present study a more detailed discussion is presented compared to previous reports on the behavior of selected polar marker compounds, including levoglucosan, malic acid, isoprene secondary organic aerosol (SOA) tracers and tracers for fungal spores. The tracer data are discussed taking into account new insights that recently became available into their stability and/or aerosol formation processes. During all three periods, levoglucosan was the most dominant identified organic species in the PM2.5 size fraction of the HVDS samples. In the dry period levoglucosan reached concentrations of up to 7.5 μg m−3 and exhibited diel variations with a nighttime prevalence. It was closely associated with the PM mass in the size-segregated samples and was mainly present in the fine mode, except during the wet period where it peaked in the coarse mode. Isoprene SOA tracers showed an average concentration of 250 ng m−3 during the dry period versus 157 ng m−3 during the transition period and 52 ng m−3 during the wet period. Malic acid and the 2-methyltetrols exhibited a different size distribution pattern, which is consistent with different aerosol formation processes (i.e., gas-to-particle partitioning in the case of malic acid and heterogeneous formation from gas-phase precursors in the case of the 2-methyltetrols). The 2-methyltetrols were mainly associated with the fine mode during all periods, while malic acid was prevalent in the fine mode only during the dry and transition periods, and dominant in the coarse mode during the wet period. The sum of the fungal spore tracers arabitol, mannitol, and erythritol in the PM2.5 fraction of the HVDS samples during the dry, transition, and wet periods was, on average, 54 ng m−3, 34 ng m−3, and 27 ng m−3, respectively, and revealed minor day/night variation. The mass size distributions of arabitol and mannitol during all periods showed similar patterns and an association with the coarse mode, consistent with their primary origin. The results show that even under the heavy smoke conditions of the dry period a natural background with contributions from bioaerosols and isoprene SOA can be revealed. The enhancement in isoprene SOA in the dry season is mainly attributed to an increased acidity of the aerosols, increased NOx concentrations and a decreased wet deposition.

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Polar organic marker compounds in atmospheric aerosols during the LBA-SMOCC 2002 biomass burning experiment in Rondônia, Brazil: sources and source processes, time series, diel variations and size distributions

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-10-10889-2010 ◽

2010 ◽

Vol 10 (4) ◽

pp. 10889-10923 ◽

Cited By ~ 1

Author(s):

M. Claeys ◽

I. Kourtchev ◽

V. Pashynska ◽

G. Vas ◽

R. Vermeylen ◽

...

Keyword(s):

Biomass Burning ◽

Malic Acid ◽

Transition Period ◽

Size Distributions ◽

Dry Period ◽

Coarse Mode ◽

Diel Variations ◽

Fine Mode ◽

Marker Compounds ◽

Organic Marker Compounds

Abstract. Measurements of polar organic marker compounds were performed on aerosols that were collected at a pasture site in the Amazon basin (Rondônia, Brazil) using a High-Volume dichotomous sampler (HVDS) and a Micro-Orifice Uniform Deposit Impactor (MOUDI). The samplings were conducted within the framework of the LBA-SMOCC (Large-Scale Biosphere Atmosphere Experiment in Amazônia – Smoke Aerosols, Clouds, Rainfall, and Climate: Aerosols From Biomass Burning Perturb Global and Regional Climate) campaign, which took place from 9 September till 14 November 2002, spanning the late dry season (biomass burning), the transition period, and the onset of the wet season (clean conditions). In the present study a more detailed discussion is presented compared to previous reports on the behavior of selected polar marker compounds, including: (a) levoglucosan, a tracer for biomass burning, (b) malic acid, a tracer for the oxidation of semivolatile carboxylic acids, (c) tracers for secondary organic aerosol (SOA) from isoprene, i.e., the 2-methyltetrols (2-methylthreitol and 2-methylerythritol) and the C5-alkene triols [2-methyl-1,3,4-trihydroxy-1-butene (cis and trans) and 3-methyl-2,3,4-trihydroxy-1-butene], and (d) sugar alcohols (arabitol, mannitol, and erythritol), tracers for fungal spores. The results obtained for levoglucosan are covered first with the aim to address its contrasting behavior with that of malic acid, the isoprene SOA tracers, and the fungal spore tracers. The tracer data are discussed taking into account new insights that recently became available into their stability and/or aerosol formation processes. During all three periods, levoglucosan was the most dominant identified organic species in the PM2.5 size fraction of the HVDS samples. In the dry period levoglucosan reached concentrations of up to 7.5 μg m−3 and exhibited diel variations with a nighttime prevalence. It was closely associated with the PM mass in the size-segregated samples and was mainly present in the fine mode, except during the wet period where it peaked in the coarse mode. Isoprene SOA tracers showed an average concentration of 250 ng m−3 during the dry period versus 157 ng m−3 during the transition period and 52 ng m−3 during the wet period. Malic acid and the 2-methyltetrols exhibited a different size distribution pattern: while the 2-methyltetrols were mainly associated with the fine mode during all periods, malic acid was prevalent in the fine mode only during the dry and transition periods, while it was dominant in the coarse mode during the wet period, consistent with different formation processes. The sum of arabitol, mannitol, and erythritol in the PM2.5 fraction of the HVDS samples during the dry, transition, and wet periods was, on average, 54 ng m−3, 34 ng m−3, and 27 ng m−3, respectively, and revealed minor day/night variation. The mass size distributions of arabitol and mannitol during all periods showed similar patterns and an association with the coarse mode, consistent with their primary origin. The results show that even under the heavy smoke conditions of the dry period a natural background with contributions from bioaerosols and isoprene SOA can be revealed. The enhancement in isoprene SOA in the dry season is mainly attributed to an increased acidity of the aerosols and a decreased wet deposition.

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Dicarboxylic acids, oxoacids, benzoic acid, <i>α</i>-dicarbonyls, WSOC, OC, and ions in spring aerosols from Okinawa Island in the western North Pacific Rim: size distributions and formation processes

Atmospheric Chemistry and Physics ◽

10.5194/acp-16-5263-2016 ◽

2016 ◽

Vol 16 (8) ◽

pp. 5263-5282 ◽

Cited By ~ 23

Author(s):

Dhananjay K. Deshmukh ◽

Kimitaka Kawamura ◽

Manuel Lazaar ◽

Bhagawati Kunwar ◽

Suresh K. R. Boreddy

Keyword(s):

Organic Carbon ◽

Benzoic Acid ◽

Biomass Burning ◽

Unsaturated Fatty Acids ◽

Glyoxylic Acid ◽

Water Soluble ◽

Size Distributions ◽

Strong Correlations ◽

Coarse Mode ◽

Fine Mode

Abstract. Size-segregated aerosols (nine stages from < 0.43 to > 11.3 µm in diameter) were collected at Cape Hedo, Okinawa, in spring 2008 and analyzed for water-soluble diacids (C2–C12), ω-oxoacids (ωC2–ωC9), pyruvic acid, benzoic acid, and α-dicarbonyls (C2–C3) as well as water-soluble organic carbon (WSOC), organic carbon (OC), and major ions (Na+, NH4+, K+, Mg2+, Ca2+, Cl−, NO3−, SO42−, and MSA−). In all the size-segregated aerosols, oxalic acid (C2) was found to be the most abundant species, followed by malonic and succinic acids, whereas glyoxylic acid (ωC2) was the dominant oxoacid and glyoxal (Gly) was more abundant than methylglyoxal. Diacids (C2–C5), ωC2, and Gly as well as WSOC and OC peaked at fine mode (0.65–1.1 µm) whereas azelaic (C9) and 9-oxononanoic (ωC9) acids peaked at coarse mode (3.3–4.7 µm). Sulfate and ammonium were enriched in fine mode, whereas sodium and chloride were in coarse mode. Strong correlations of C2–C5 diacids, ωC2 and Gly with sulfate were observed in fine mode (r =  0.86–0.99), indicating a commonality in their secondary formation. Their significant correlations with liquid water content in fine mode (r =  0.82–0.95) further suggest an importance of the aqueous-phase production in Okinawa aerosols. They may also have been directly emitted from biomass burning in fine mode as supported by strong correlations with potassium (r =  0.85–0.96), which is a tracer of biomass burning. Bimodal size distributions of longer-chain diacid (C9) and oxoacid (ωC9) with a major peak in the coarse mode suggest that they were emitted from the sea surface microlayers and/or produced by heterogeneous oxidation of biogenic unsaturated fatty acids on sea salt particles.

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Molecular markers of biomass burning and primary biological aerosols in urban Beijing: size distribution and seasonal variation

Atmospheric Chemistry and Physics ◽

10.5194/acp-20-3623-2020 ◽

2020 ◽

Vol 20 (6) ◽

pp. 3623-3644 ◽

Cited By ~ 3

Author(s):

Shaofeng Xu ◽

Lujie Ren ◽

Yunchao Lang ◽

Shengjie Hou ◽

Hong Ren ◽

...

Keyword(s):

Molecular Markers ◽

Biomass Burning ◽

Aerosol Particles ◽

Fungal Spores ◽

Chemical Compositions ◽

Plant Debris ◽

Urban Aerosols ◽

Biological Aerosols ◽

Coarse Mode ◽

Fine Mode

Abstract. Biomass burning and primary biological aerosol particles account for an important part of urban aerosols. Floods of studies have been conducted on the chemical compositions of fine aerosols (PM2.5) in megacities where the haze pollution is one of the severe environmental issues in China. However, little is known about their size distributions in atmospheric aerosols in the urban boundary layer. Here, size-segregated aerosol samples were collected in Beijing during haze and clear days from April 2017 to January 2018. Three anhydrosugars, six primary saccharides and four sugar alcohols in these samples were identified and quantified by gas chromatography/mass spectrometry (GC/MS). Higher concentrations of a biomass burning tracer, levoglucosan, were detected in autumn and winter than in other seasons. Sucrose, glucose, fructose, mannitol and arabitol were more abundant in the bloom and glowing seasons. A particularly high level of trehalose was found in spring, which was largely associated with the Asian dust outflows. Anhydrosugars, xylose, maltose, inositol and erythritol are mainly present in the fine mode (<2.1 µm), while the others showed the coarse-mode preference. The concentrations of measured tracers of biomass burning particles and primary biological particles in the haze events were higher than those in the non-hazy days, with enrichment factors of 2–10. Geometric mean diameters (GMDs) of molecular markers of biomass burning and primary biological aerosols showed that there was no significant difference in the coarse mode (>2.1 µm) between the haze and non-haze samples, while a size shift towards large particles and large GMDs in the fine fraction (<2.1 µm) was detected during the hazy days, which highlights that the stable meteorological conditions with high relative humidity in urban Beijing may favor the condensation of organics onto coarse particles.The contributions of reconstructed primary organic carbon (POC) by tracer-based methods from plant debris, fungal spores and biomass burning to aerosol OC in the total-mode particles were in the ranges of 0.09 %–0.30 % (on average 0.21 %), 0.13 %–1.0 % (0.38 %) and 1.2 %–7.5 % (4.5 %), respectively. This study demonstrates that the contribution of biomass burning was significant in Beijing throughout the whole year with the predominance in the fine mode, while the contributions of plant debris and fungal spores dominated in spring and summer in the coarse mode, especially in sizes >5.8 µm. Our observations demonstrate that the sources, abundance and chemical composition of urban aerosol particles are strongly size dependent in Beijing, which is important to better understand the environmental and health effects of urban aerosols and should be considered in air quality and climate models.

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Retrieval of aerosol microphysical and optical properties above liquid clouds from POLDER/PARASOL polarization measurements

Atmospheric Measurement Techniques ◽

10.5194/amt-6-991-2013 ◽

2013 ◽

Vol 6 (4) ◽

pp. 991-1016 ◽

Cited By ~ 69

Author(s):

F. Waquet ◽

C. Cornet ◽

J.-L. Deuzé ◽

O. Dubovik ◽

F. Ducos ◽

...

Keyword(s):

Biomass Burning ◽

Radiative Forcing ◽

Mineral Dust ◽

Spherical Particles ◽

Dust Particles ◽

Polarization Measurements ◽

Microphysical Properties ◽

Coarse Mode ◽

Fine Mode ◽

Aerosol Properties

Abstract. Most of the current aerosol retrievals from passive sensors are restricted to cloud-free scenes, which strongly reduces our ability to monitor the aerosol properties at a global scale and to estimate their radiative forcing. The presence of aerosol above clouds (AAC) affects the polarized light reflected by the cloud layer, as shown by the spaceborne measurements provided by the POlarization and Directionality of Earth Reflectances (POLDER) instrument on the PARASOL satellite. In a previous work, a first retrieval method was developed for AAC scenes and evaluated for biomass-burning aerosols transported over stratocumulus clouds. The method was restricted to the use of observations acquired at forward scattering angles (90–120°) where polarized measurements are highly sensitive to fine-mode particle scattering. Non-spherical particles in the coarse mode, such as mineral dust particles, do not much polarize light and cannot be handled with this method. In this paper, we present new developments that allow retrieving also the properties of mineral dust particles above clouds. These particles do not much polarize light but strongly reduce the polarized cloud bow generated by the liquid cloud layer beneath and observed for scattering angles around 140°. The spectral attenuation can be used to qualitatively identify the nature of the particles (i.e. accumulation mode versus coarse mode, i.e. mineral dust particles versus biomass-burning aerosols), whereas the magnitude of the attenuation is related to the optical thickness of the aerosol layer. We also use the polarized measurements acquired in the cloud bow to improve the retrieval of both the biomass-burning aerosol properties and the cloud microphysical properties. We provide accurate polarized radiance calculations for AAC scenes and evaluate the contribution of the POLDER polarization measurements for the simultaneous retrieval of the aerosol and cloud properties. We investigate various scenes with mineral dust particles and biomass-burning aerosols above clouds. For clouds, our results confirm that the droplet size distribution is narrow in high-latitude ocean regions and that the droplet effective radii retrieved from both polarization measurements and from total radiance measurements are generally close for AAC scenes (departures smaller than 2 μm). We found that the magnitude of the primary cloud bow cannot be accurately estimated with a plane parallel transfer radiative code. The errors for the modeling of the polarized cloud bow are between 4 and 8% for homogenous cloudy scenes, as shown by a 3-D radiative transfer code. These effects only weakly impact the retrieval of the Aerosol Optical Thickness (AOT) performed with a mineral dust particle model for which the microphysical properties are entirely known (relative error smaller than 6%). We show that the POLDER polarization measurements allow retrieving the AOT, the fine-mode particle size, the Ångström exponent and the fraction of spherical particles. However, the complex refractive index and the coarse-mode particle size cannot be accurately retrieved with the present polarization measurements. Our complete and accurate algorithm cannot be applied to process large amounts of data, so a simpler algorithm was developed to retrieve the AOT and the Ångström exponent above clouds in an operational way. Illustrations are provided for July–August 2008 near the African coast. Large mean AOTs above clouds at 0.865 μm (>0.3) are retrieved for oceanic regions near the coasts of South Africa that correspond to biomass-burning aerosols, whereas even larger mean AOTs above clouds for mineral dust particles (>0.6) are also retrieved near the coasts of Senegal. For these regions and time period, the direct AAC radiative forcing is likely to be significant. The final aim of this work is the global monitoring of the AAC properties and the estimation of the direct aerosol radiative forcing in cloudy scenes.

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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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Biogenic cloud nuclei in the Amazon

10.5194/acp-2015-1020 ◽

2016 ◽

Author(s):

J. D. Whitehead ◽

E. Darbyshire ◽

J. Brito ◽

H. M. J. Barbosa ◽

I. Crawford ◽

...

Keyword(s):

Biomass Burning ◽

Transition Period ◽

Aerosol Particles ◽

Dry Season ◽

Atmospheric Composition ◽

Wet Season ◽

Accumulation Mode ◽

Coarse Mode ◽

Dry Seasons ◽

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 above the canopy at a remote rainforest site in the Amazon, during the transition from wet to dry seasons, 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 non-refractory aerosol composition, as measured by an Aerosol Chemical Speciation Monitor (ACSM), was dominated by organic material (86 %). 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, possibly due to a stronger marine inﬂuence at that location, bringing higher sulphate loadings than are typically seen in the Amazon. 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 FBAP). The mean FBAP number concentration was 404 ± 237 l−1, however this was subject to a strong diurnal cycle, and ranged from around 200 l−1 during the day to as much as 1200 l−1 at night. FBAP dominated the coarse mode particles, comprising more than 90 % of particles detected by the WIBS-3 during the night. This proportion was also subject to a diurnal cycle, dropping to between 55 % and 75 % during the day, since non-FBAP 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. Application of Ward linkage cluster analysis using the z-score normalisation to the data suggests that FBAP were dominated (around 70 %) by fungal spores. Further, long-term measurements will be required in order to fully examine the seasonal variability, and distribution through the canopy of primary biological aerosol particles. 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 dry seasons, and thus provides a unique contrast 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 is likely to play an important role as ice nuclei in the region.

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Secondary organic aerosol formation from biomass burning emissions

10.5194/acp-2019-326 ◽

2019 ◽

Cited By ~ 2

Author(s):

Christopher Y. Lim ◽

David H. Hagan ◽

Matthew M. Coggon ◽

Abigail R. Koss ◽

Kanako Sekimoto ◽

...

Keyword(s):

Biomass Burning ◽

Secondary Organic Aerosol ◽

Total Concentration ◽

Organic Aerosol ◽

Oh Radicals ◽

Aerosol Formation ◽

Atmospheric Aging ◽

Aerosol Mass ◽

Photochemical Aging ◽

Organic Gases

Abstract. Biomass burning is an important source of aerosol and trace gases to the atmosphere, but how these emissions change chemically during their lifetimes is not fully understood. As part of the Fire Influence on Regional and Global Environments Experiment (FIREX 2016), we investigated the effect of photochemical aging on biomass burning organic aerosol (BBOA), with a focus on fuels from the western United States. Emissions were sampled into a small (150 L) environmental chamber and photochemically aged via the addition of ozone and irradiation by 254 nm light. While some fraction of species undergoes photolysis, the vast majority of aging occurs via reaction with OH radicals, with total OH exposures corresponding to the equivalent of up to 10 days of atmospheric oxidation. For all fuels burned, large and rapid changes are seen in the ensemble chemical composition of BBOA, as measured by an aerosol mass spectrometer (AMS). Secondary organic aerosol (SOA) formation is seen for all aging experiments and continues to grow with increasing OH exposure, but the magnitude of the SOA formation is highly variable between experiments. This variability can be explained well by a combination of experiment-to-experiment differences in OH exposure and the total concentration of non-methane organic gases (NMOGs) in the chamber before oxidation, measured by PTR-ToF-MS (r2 values from 0.64 to 0.83). From this relationship, we calculate the fraction of carbon from biomass burning NMOGs that is converted to SOA as a function of equivalent atmospheric aging time, with carbon yields ranging from 24 ± 4 % after 6 hours to 56 ± 9 % after 4 days.

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MicroRNA profiles of dry secretions through the first three weeks of the dry period from Holstein cows

Scientific Reports ◽

10.1038/s41598-019-56193-5 ◽

2019 ◽

Vol 9 (1) ◽

Cited By ~ 1

Author(s):

Ellie J. Putz ◽

Austin M. Putz ◽

Hyeongseon Jeon ◽

John D. Lippolis ◽

Hao Ma ◽

...

Keyword(s):

Regression Models ◽

Transition Period ◽

Mirna Profile ◽

Random Regression ◽

Q Value ◽

Dry Period ◽

Regulate Gene Expression ◽

Intramammary Infections ◽

Non Coding Rnas ◽

Insight Into

AbstractIn dairy cows, the period from the end of lactation through the dry period and into the transition period, requires vast physiological and immunological changes critical to mammary health. The dry period is important to the success of the next lactation and intramammary infections during the dry period will adversely alter mammary function, health and milk production for the subsequent lactation. MicroRNAs (miRNAs) are small non-coding RNAs that can post transcriptionally regulate gene expression. We sought to characterize the miRNA profile in dry secretions from the last day of lactation to 3, 10, and 21 days post dry-off. We identified 816 known and 80 novel miRNAs. We found 46 miRNAs whose expression significantly changed (q-value < 0.05) over the first three weeks of dry-off. Additionally, we examined the slopes of random regression models of log transformed normalized counts and cross analyzed the 46 significantly upregulated and downregulated miRNAs. These miRNAs were found to be associated with important components of pregnancy, lactation, as well as inflammation and disease. Detailing the miRNA profile of dry secretions through the dry-off period provides insight into the biology at work, possible means of regulation, components of resistance and/or susceptibility, and outlets for targeted therapy development.

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Quantifying primary and secondary humic-like substances in urban aerosol based on emission source characterization and a source-oriented air quality model

10.5194/acp-2018-779 ◽

2018 ◽

Author(s):

Xinghua Li ◽

Junzan Han ◽

Philip K. Hopke ◽

Jingnan Hu ◽

Qi Shu ◽

...

Keyword(s):

Organic Carbon ◽

Biomass Burning ◽

Coal Combustion ◽

Power Plants ◽

Water Soluble ◽

Aerosol Formation ◽

Source Characterization ◽

Air Quality Model ◽

Coal Burning ◽

Residential Coal

Abstract. Humic-like substances (HULIS) are a mixture of high molecular weight, water-soluble organic compounds that are widely distributed in atmospheric aerosol. Their sources are rarely studied quantitatively. Biomass burning is generally accepted as a major primary source of ambient humic-like substances (HULIS) with additional secondary material formed in the atmosphere. However, the present study provides direct evidence that residential coal burning is also a significant source of ambient HULIS, especially in the heating season in northern China based on source measurements, ambient sampling and analysis, and apportionment with source-oriented CMAQ modeling. Emissions tests show that residential coal combustion produces 5 to 24 % of the emitted organic carbon (OC) as HULIS carbon (HULISc). Estimation of primary emissions of HULIS in Beijing indicated that residential biofuel and coal burning contribute about 70 % and 25 % of annual primary HULIS, respectively. Vehicle exhaust, industry, and power plants contributions are negligible. Average concentration of ambient HULIS was 7.5 μg/m3 in atmospheric PM2.5 in urban Beijing and HULIS exhibited obvious seasonal variations with the highest concentrations in winter. HULISc account for 7.2 % of PM2.5 mass, 24.5 % of OC, and 59.5 % of water-soluble organic carbon, respectively. HULIS are found to correlate well with K+, Cl−, sulfate, and secondary organic aerosol suggesting its sources include biomass burning, coal combustion and secondary aerosol formation. Source apportionment based on CMAQ modeling shows residential biofuel and coal burning, secondary formation are important annual sources of ambient HULIS, contributing 57.5 %, 12.3 %, and 25.8 %, respectively.

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The Effectiveness of the Use of Enzymatic Hydrolyzate with Amino Acids, Vitamins and Minerals to Highly Productive Cows in the Transition Period

Vestnik APK Verhnevolzh`ia ◽

10.35694/yarcx.2020.50.2.006 ◽

2020 ◽

Author(s):

А.М. Френк ◽

Е.М. Гриневская ◽

А.И. Фролов ◽

А.Н. Бетин ◽

Н.И. Маслова

Keyword(s):

Transition Period ◽

Live Weight ◽

Gastrointestinal Diseases ◽

Feed Additive ◽

Dry Period ◽

Young Stock ◽

Service Period ◽

Farm Scale ◽

Feces Analysis ◽

Experimental Group

В условиях научно-производственного опыта исследована эффективность введения кормовой добавки «Абиотоник» в рацион высокопродуктивных голштинизированных симментальских коров (в транзитный период и на раздое). «Абиотоник» представляет собой усовершенствованный аналог известного импортного препарата «Чиктоник», отличаясь от иностранного аналога многократно увеличенной концентрацией пептона и наличием высокодефицитных микроэлементов (селена и элементоорганического соединения йода). Наши исследования показали, что скармливание препарата «Абиотоник» в дозе 150 мл/гол. способствовало росту продуктивности коров на 5,84%, улучшило физико-химические свойства молока и повысило его пищевую ценность. Применение кормовой добавки способствовало также профилактике желудочно-кишечных заболеваний у коров, повышению их резистентности, о чём свидетельствовали показатели крови и бактериологического исследования кала. Заболеваемость коров в опытной группе не наблюдалась. Использование препарата «Абиотоник» коровам в заключительной стадии сухостойного периода и в начале лактации привело к сокращению времени отделения плаценты у коров после отёла на 6,54%, или на 0,4 часа, повышению живой массы новорождённого молодняка на 1,6% и сокращению сервис-периода у опытных коров на 8 дней по сравнению с контрольными. Использование кормовой добавки «Абиотоник» способствовало получению дополнительного дохода от реализации молока в размере 1152 руб./гол. Полученные экспериментальные данные позволяют рекомендовать использование отечественной импортозамещающей кормовой добавки «Абиотоник» в рационах коров транзитного периода и на раздое в дозе 150 мл/гол. ежедневно в последней фазе сухостоя и через день в течение 40 суток после отёла. Under the conditions of scientific and farm scale trial the efficiency of introduction of the feed additive "Abiotonic" into the diet of highly productive Holsteinized Simmental cows (during the transition period and for days in milk) was studied. "Abiotonic" is an improved analogue of the known imported preparation "Chiktonik" differing from the foreign analogue by its manifoldly increased peptone concentration and the presence of highly deficient microelements (selenium and organo-element compounds of iodine). Our researches have shown that feeding the preparation "Abiotonic" at a dose of 150 ml / head contributed to an increase in cow productivity by 5.84%, improved the physicochemical properties of milk and increased its nutritional value. The use of a feed additive also contributed to the prevention of gastrointestinal diseases in cows, an increase in their resistance as evidenced by haematological parameters and bacteriological feces analysis. The incidence of cows in the experimental group was not observed. The use of the preparation "Abiotonic" for cows in the final stage of the dry period and at the beginning of lactation reduced the time for separation of the placenta in cows after calving by 6.54% or 0.4 hours, increased the live weight of newborn young stock by 1.6% and reduced the service period of experienced cows by 8 days compared with the control ones. The use of the "Abiotonic" feed additive contributed to the receipt of additional income from the sale of milk in the amount of 1152 rubles / head. The obtained experimental data allow us to recommend the use of domestic import-substituting feed additive "Abiotonic" in the diets of cows in the transition period and for days in milk at a dose of 150 ml / head daily in the last phase of dry period and every other day for 40 days after calving.

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