Construction of an airborne chemiluminescence ozone monitor for volcanic plumes

Volcanic plumes contain traces of bromine monoxide, BrO, which catalyze destruction of ozone, O3, mixed into the plume. Therefore, local depletion of O3 in the plume could be possible. However, calculations comparing mixing with the rate of O3 destruction suggest that no significant decline in the O3 concentration should be expected. On the other hand several studies at different volcanoes have found varying degrees of O3 depletion inside the plume. So far, ozone and its concentration distribution in volcanic plumes have only been insufficiently determined. Reliable ozone measurements would make a decisive contribution to the understanding of volcanic plume chemistry. The standard technique for ambient O3 monitoring is the short-path ultraviolet (UV) absorption instrument. But in volcanic plumes this technique suffers from strong interference of the overlapping SO2 absorption features in the UV. SO2 is one of the major compounds in volcanic plumes. We want to overcome this problem by relying on the chemiluminescence (CL) reaction between ozone and ethene, a standard technique for O3 measurement in the 1970s and 1980s, which we found to have no interference from trace gases abundant in volcanic plumes. The key component of a CL O3-instrument is a reaction chamber, where ethene is mixed into the ambient air and a photomultiplier tube detects the resulting photons. Field measurements with existing CL O3-monitors are complicated, because they are usually heavy and bulky. Therefore we designed a more compact and lightweight version (10 kg backpack size CL instrument), which was used in a field study at Mount Etna. However, the campaign was restricted to plumes that are pushed down to ground in areas accessible by foot. Here we report on a further improved version of the instrument weighing around 1 kg, which we can mount onto a drone to carry it into the plume. In particular, we describe the design advances making the reduction in weight and size possible.

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Towards a representation of halogen chemistry within volcanic plumes in a chemistry transport model

Geoscientific Model Development Discussions ◽

10.5194/gmdd-7-2581-2014 ◽

2014 ◽

Vol 7 (2) ◽

pp. 2581-2650 ◽

Cited By ~ 4

Author(s):

L. Grellier ◽

V. Marécal ◽

B. Josse ◽

P. D. Hamer ◽

T. J. Roberts ◽

...

Keyword(s):

Transport Model ◽

Computational Cost ◽

Ambient Air ◽

Heterogeneous Reactions ◽

Tropospheric Chemistry ◽

Volcanic Plume ◽

Large Set ◽

Chemistry Transport Model ◽

Volcanic Plumes ◽

The Impact

Abstract. Volcanoes are a known source of halogens to the atmosphere. HBr volcanic emissions lead rapidly to the formation of BrO within volcanic plumes as shown by recent work based on observations and models. BrO, having a longer residence time in the atmosphere than HBr, is expected to have a significant impact on tropospheric chemistry, at least at the local and regional scales. The objective of this paper is to prepare a framework that will allow 3-D modelling of volcanic halogen emissions in order to determine their fate within the volcanic plume and then in the atmosphere at the regional and global scales. This work is based on a 1-D configuration of the chemistry transport model MOCAGE whose low computational cost allows us to perform a large set of sensitivity studies. This paper studies the Etna eruption on the 10 May 2008 that took place just before night time. Adaptations are made to MOCAGE to be able to produce the chemistry occurring within the volcanic plume. A simple sub-grid scale parameterization of the volcanic plume is implemented and tested. The use of this parameterization in a 0.5° × 0.5° configuration (typical regional resolution) has an influence on the partitioning between the various bromine compounds both during the eruption period and also during the night period immediately afterwards. During the day after the eruption, simulations both with and without parameterizations give very similar results that are consistent with the tropospheric column of BrO and SO2 in the volcanic plume derived from GOME-2 observations. Tests have been performed to evaluate the sensitivity of the results to the mixing between ambient air and the magmatic air at very high temperature at the crater vent that modifies the composition of the emission, and in particular the sulphate aerosol content that is key compound in the BrO production. Simulations show that the plume chemistry is not very sensitive to the assumptions used for the mixing parameter (relative quantity of ambient air mixed with magmatic air in the mixture) that is not well known. This is because there is no large change in the compounds limiting/favouring the BrO production in the plume. The impact of the model grid resolution is also tested in view of future 3-D-simulations at the global scale. A dilution of the emitted gases and aerosols is observed when using the typical global resolution (2°) as compared to a typical regional resolution (0.5°), as expected. Taking this into account, the results of the 2° resolution simulations are consistent with the GOME-2 observations. In general the simulations at 2° resolution are less efficient at producing BrO after the emission both with and without the subgrid-scale parameterization. The differences are mainly due to an interaction between concentration effects than stem from using a reduced volume in the 0.5° resolution combined with second order rate kinetics. The last series of tests were on the mean radius assumed for the sulphate aerosols that indirectly impacts the production of BrO by heterogeneous reactions. The simulations show that the BrO production is sensitive to this parameter with a stronger production when smaller aerosols are assumed. These results will be used to guide the implementation of volcanic halogen emissions in the 3-D configuration of MOCAGE.

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Solubility of metals in aerosol samples from Mount Etna during the EPL-REFLECT campaign

10.5194/egusphere-egu2020-9858 ◽

2020 ◽

Author(s):

Chiara Giorio ◽

Sara D'Aronco ◽

Lidia Soldà ◽

Salvatore Giammanco ◽

Alessandro La Spina ◽

...

Keyword(s):

Trace Metals ◽

Human Health ◽

Organic Compounds ◽

Organic Ligand ◽

Mount Etna ◽

Urban Site ◽

Explosive Eruptions ◽

Chemical Components ◽

Volcanic Plume ◽

Volcanic Plumes

Volcanoes emit a chemically complex cocktail of gases and aerosols into the atmosphere, which can affect Earth&#8217;s climate (1) and human health. The vast majority of volcanogenic fatalities involve the obvious thermal and physical injuries resulting from an eruption, but many of the emissions from volcanoes are toxic and include compounds such as sulfates and metals, which are known to disrupt biological systems (2). Yet, there is a lack of knowledge on the toxicity of compounds found in volcanic plumes and their fate in the atmosphere.Research has focussed on the impacts of large-magnitude explosive eruptions. While emissions from many non-explosive eruptions are continuous and prolonged, their climatic and potential effects on human health have not been studied extensively. Once the plume disperses in the atmosphere, the aerosol particle components can mix and interact with oxidants and organic compounds present in the atmosphere. How these chemical components interact and how the interactions affect the Earth&#8217;s climate, particle toxicity and human health is largely unknown especially for trace metals.In the framework of the EPL-REFLECT (Etna Plume Lab &#8211; near-source estimations of Radiative EFfects of voLcanic aErosols for Climate and air quality sTudies), a field campaign on Mount Etna was done in July 2019 in which samples of atmospheric aerosol were collected during non-explosive degassing activity. Samples were collected both at the crater and in a transect following the volcanic plume down slope to the closest inhabited areas. Samples were analysed for trace metals and organic compounds, including solubility tests (3) to assess how tropospheric processing of the aerosol affects metal bioavailability and potentially the toxicity of the aerosol.&#160;(1) von Glasow, R. 2010. Atmospheric chemistry in volcanic plumes. Proceedings of the National Academy of Sciences, vol. 107, pp. 6594&#8211;6599., DOI: 10.1073/pnas.0913164107(2) Weinstein, P., Horwell, C.J., Cook, A. 2013. Volcanic Emissions and Health. In: Essentials of Medical Geology, Springer Netherlands, Dordrecht, pp. 217&#8211;238., DOI: 10.1007/978-94-007-4375-5_10(3) Tapparo, A., Di Marco, V., Badocco, D., D&#8217;Aronco, S., Sold&#224;, L., Pastore, P., Mahon, B.M., Kalberer, M., Giorio, C. 2019. Formation of metal-organic ligand complexes affects solubility of metals in airborne particles at an urban site in the Po Valley. Chemosphere, in press., DOI: 10.1016/j.chemosphere.2019.125025

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Observation and modelling of ozone-destructive halogen chemistry in a passive degassing volcanic plume

10.5194/acp-2021-145 ◽

2021 ◽

Author(s):

Luke Surl ◽

Tjarda Roberts ◽

Slimane Bekki

Keyword(s):

Heterogeneous Reactions ◽

Mount Etna ◽

Volcanic Plume ◽

Activation Process ◽

Aerosol Formation ◽

Strong Negative Correlation ◽

Volcanic Plumes ◽

Ozone Loss ◽

Halogen Chemistry ◽

Aircraft Observations

Abstract. Volcanoes emit halogens into the atmosphere that undergo chemical cycling in plumes and cause destruction of ozone. The impacts of volcanic halogens are inherently difficult to measure at volcanoes, and the complexity of the chemistry, coupled with the mixing and dispersion of the plume, makes the system challenging to model numerically. We present aircraft observations of the Mount Etna plume in the summer of 2012, when the volcano was passively degassing. Measurements of SO2 – an indicator of plume intensity – and ozone were made in the plume a few 10s of km from the source, revealing a strong negative correlation between ozone and SO2 levels. From these observations we estimate a mean in-plume ozone loss rate of 1.3 × 10−5 molecules of O3 per second per molecule of SO2. This value is similar to observation-derived estimates reported very close to the Mount Etna vents, indicating continual ozone loss in the plume up to at least 10's km downwind. The chemically reactive plume is simulated using a new numerical 3D model WRF-Chem Volcano (WCV), a version of WRF-Chem we have modified to incorporate volcanic emissions (including HBr and HCl) and multi-phase halogen chemistry. We used nested grids to model the plume close to the volcano at 1 km. The focus is on the early evolution of passively degassing plumes aged less than one hour and up to 10's km downwind. The model reproduces the so-called bromine explosion: the daytime bromine activation process by which HBr in the plume is converted to other more reactive forms that continuously cycle in the plume. These forms include the radical BrO, a species whose ratio with SO2 is commonly measured in volcanic plumes as an indicator of halogen ozone-destroying chemistry. We track the modelled partitioning of bromine between its forms. The model yields in-plume BrO / SO2 ratios (around 10−4 mol/mol) similar to those observed previously in Etna plumes. The modelled BrO / SO2 is lower in plumes which are more dilute (e.g. at greater windspeed). It is also slightly lower in plumes in the middle of the day compared than in the morning and evening, due to BrO's reaction with diurnally varying HO2. Sensitivity simulations confirm the importance of near-vent products from high temperature chemistry, notably bromine radicals, in initiating the ambient temperature plume halogen cycling. Note also that heterogeneous reactions that activate bromine also activate a small fraction of the emitted chlorine; the resulting production of chlorine radical Cl causes a strong reduction in the methane lifetime and increasing formation of HCHO in the plume. Modelled rates of ozone depletion are found to be similar to those derived from aircraft observations. Ozone destruction in the model is controlled by the processes that recycle bromine, with about three-quarters of this recycling occurring via reactions between halogen oxide radicals. Through sensitivity simulations, a relationship between the magnitude of halogen emissions and ozone loss is established. Volcanic halogens cycling impacts profoundly the overall plume chemistry, notably hydrogen oxide radicals (HOx), nitrogen oxides (NOx), sulfur, and mercury chemistry. In the model, it depletes HOx within the plume, increasing the lifetime of SO2 and hence slowing sulfate aerosol formation. Halogen chemistry also promotes the conversion of NOx into nitric acid (HNO3). This, along with the displacement of nitrate out of background aerosols in the plume, results in enhance HNO3 levels and an almost total depletion of NOx in the plume. The halogen-mercury model scheme is simple but includes newly-identified photo-reductions of mercury halides. With this set-up, the mercury oxidation is found to be slow and in near-balance with the photo-reduction in the plume. Overall, the model findings demonstrate that halogen chemistry has to be considered for a complete understanding of sulfur, HOx, reactive nitrogen, and mercury chemistry, and of the formation of sulfate particles in volcanic plumes.

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Observation and modelling of ozone-destructive halogen chemistry in a passively degassing volcanic plume

Atmospheric Chemistry and Physics ◽

10.5194/acp-21-12413-2021 ◽

2021 ◽

Vol 21 (16) ◽

pp. 12413-12441

Author(s):

Luke Surl ◽

Tjarda Roberts ◽

Slimane Bekki

Keyword(s):

Ambient Temperature ◽

Time Of Day ◽

Heterogeneous Reactions ◽

Mount Etna ◽

Volcanic Plume ◽

Aerosol Formation ◽

Volcanic Plumes ◽

Ozone Loss ◽

Halogen Chemistry ◽

Aircraft Observations

Abstract. Volcanoes emit halogens into the atmosphere that undergo complex chemical cycling in plumes and cause destruction of ozone. We present a case study of the Mount Etna plume in the summer of 2012, when the volcano was passively degassing, using aircraft observations and numerical simulations with a new 3D model “WRF-Chem Volcano” (WCV), incorporating volcanic emissions and multi-phase halogen chemistry. Measurements of SO2 – an indicator of plume intensity – and ozone were made in the plume a few tens of kilometres from Etna, revealing a strong negative correlation between ozone and SO2 levels. From these observations, using SO2 as a tracer species, we estimate a mean in-plume ozone loss rate of 1.3×10−5 molecules of O3 per second per molecule of SO2. This value is similar to observation-based estimates reported very close to Etna's vents, indicating continual ozone loss in the plume up to at least tens of kilometres downwind. The WCV model is run with nested grids to simulate the plume close to the volcano at 1 km resolution. The focus is on the early evolution of passively degassing plumes aged less than 1 h and up to tens of kilometres downwind. The model is able to reproduce the so-called “bromine explosion”: the daytime conversion of HBr into bromine radicals that continuously cycle in the plume. These forms include the radical BrO, a species whose ratio with SO2 is commonly measured in volcanic plumes as an indicator of halogen ozone-destroying chemistry. The species BrO is produced in the ambient-temperature chemistry, with in-plume BrO / SO2 ratios on the order of 10−4 mol/mol, similar to those observed previously in Etna plumes. Wind speed and time of day are identified as non-linear controls on this ratio. Sensitivity simulations confirm the importance of near-vent radical products from high-temperature chemistry in initiating the ambient-temperature plume halogen cycling. Heterogeneous reactions that activate bromine also activate a small fraction of the emitted chlorine; the resulting production of chlorine radical Cl strongly enhances the methane oxidation and hence the formation of formaldehyde (HCHO) in the plume. Modelled rates of ozone depletion are found to be similar to those derived from aircraft observations. Ozone destruction in the model is controlled by the processes that recycle bromine, with about three-quarters of this recycling occurring via reactions between halogen oxide radicals. Through sensitivity simulations, a relationship between the magnitude of halogen emissions and ozone loss is established. Volcanic halogen cycling profoundly impacts the overall plume chemistry in the model, notably hydrogen oxide radicals (HOx), nitrogen oxides (NOx), sulfur, and mercury chemistry. In the model, it depletes HOx within the plume, increasing the lifetime of SO2 and hence slowing sulfate aerosol formation. Halogen chemistry also promotes the conversion of NOx into nitric acid (HNO3). This, along with the displacement of nitrate out of background aerosols in the plume, results in enhanced HNO3 levels and an almost total depletion of NOx in the plume. The halogen–mercury model scheme is simple but includes newly identified photo-reductions of mercury halides. With this set-up, the mercury oxidation is found to be slow and in near-balance with the photo-reduction of the plume. Overall, the model findings demonstrate that halogen chemistry has to be considered for a complete understanding of sulfur, HOx, reactive nitrogen, and mercury chemistry and of the formation of sulfate particles in volcanic plumes.

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Field measurements of trace gases and aerosols emitted by peat fires in Central Kalimantan, Indonesia, during the 2015 El Niño

Atmospheric Chemistry and Physics ◽

10.5194/acp-16-11711-2016 ◽

2016 ◽

Vol 16 (18) ◽

pp. 11711-11732 ◽

Cited By ~ 83

Author(s):

Chelsea E. Stockwell ◽

Thilina Jayarathne ◽

Mark A. Cochrane ◽

Kevin C. Ryan ◽

Erianto I. Putra ◽

...

Keyword(s):

Optical Properties ◽

El Niño ◽

El Nino ◽

Trace Gases ◽

Field Measurements ◽

Optical Data ◽

Trace Gas ◽

Aerosol Optical Properties ◽

Central Kalimantan ◽

Peat Fires

Abstract. Peat fires in Southeast Asia have become a major annual source of trace gases and particles to the regional–global atmosphere. The assessment of their influence on atmospheric chemistry, climate, air quality, and health has been uncertain partly due to a lack of field measurements of the smoke characteristics. During the strong 2015 El Niño event we deployed a mobile smoke sampling team in the Indonesian province of Central Kalimantan on the island of Borneo and made the first, or rare, field measurements of trace gases, aerosol optical properties, and aerosol mass emissions for authentic peat fires burning at various depths in different peat types. This paper reports the trace gas and aerosol measurements obtained by Fourier transform infrared spectroscopy, whole air sampling, photoacoustic extinctiometers (405 and 870 nm), and a small subset of the data from analyses of particulate filters. The trace gas measurements provide emission factors (EFs; grams of a compound per kilogram biomass burned) for up to ∼  90 gases, including CO2, CO, CH4, non-methane hydrocarbons up to C10, 15 oxygenated organic compounds, NH3, HCN, NOx, OCS, HCl, etc. The modified combustion efficiency (MCE) of the smoke sources ranged from 0.693 to 0.835 with an average of 0.772 ± 0.053 (n  =  35), indicating essentially pure smoldering combustion, and the emissions were not initially strongly lofted. The major trace gas emissions by mass (EF as g kg−1) were carbon dioxide (1564 ± 77), carbon monoxide (291 ± 49), methane (9.51 ± 4.74), hydrogen cyanide (5.75 ± 1.60), acetic acid (3.89 ± 1.65), ammonia (2.86 ± 1.00), methanol (2.14 ± 1.22), ethane (1.52 ± 0.66), dihydrogen (1.22 ± 1.01), propylene (1.07 ± 0.53), propane (0.989 ± 0.644), ethylene (0.961 ± 0.528), benzene (0.954 ± 0.394), formaldehyde (0.867 ± 0.479), hydroxyacetone (0.860 ± 0.433), furan (0.772 ± 0.035), acetaldehyde (0.697 ± 0.460), and acetone (0.691 ± 0.356). These field data support significant revision of the EFs for CO2 (−8 %), CH4 (−55 %), NH3 (−86 %), CO (+39 %), and other gases compared with widely used recommendations for tropical peat fires based on a lab study of a single sample published in 2003. BTEX compounds (benzene, toluene, ethylbenzene, xylenes) are important air toxics and aerosol precursors and were emitted in total at 1.5 ± 0.6 g kg−1. Formaldehyde is probably the air toxic gas most likely to cause local exposures that exceed recommended levels. The field results from Kalimantan were in reasonable agreement with recent lab measurements of smoldering Kalimantan peat for “overlap species,” lending importance to the lab finding that burning peat produces large emissions of acetamide, acrolein, methylglyoxal, etc., which were not measurable in the field with the deployed equipment and implying value in continued similar efforts. The aerosol optical data measured include EFs for the scattering and absorption coefficients (EF Bscat and EF Babs, m2 kg−1 fuel burned) and the single scattering albedo (SSA) at 870 and 405 nm, as well as the absorption Ångström exponents (AAE). By coupling the absorption and co-located trace gas and filter data we estimated black carbon (BC) EFs (g kg−1) and the mass absorption coefficient (MAC, m2 g−1) for the bulk organic carbon (OC) due to brown carbon (BrC). Consistent with the minimal flaming, the emissions of BC were negligible (0.0055 ± 0.0016 g kg−1). Aerosol absorption at 405 nm was ∼  52 times larger than at 870 nm and BrC contributed ∼  96 % of the absorption at 405 nm. Average AAE was 4.97 ± 0.65 (range, 4.29–6.23). The average SSA at 405 nm (0.974 ± 0.016) was marginally lower than the average SSA at 870 nm (0.998 ± 0.001). These data facilitate modeling climate-relevant aerosol optical properties across much of the UV/visible spectrum and the high AAE and lower SSA at 405 nm demonstrate the dominance of absorption by the organic aerosol. Comparing the Babs at 405 nm to the simultaneously measured OC mass on filters suggests a low MAC ( ∼  0.1) for the bulk OC, as expected for the low BC/OC ratio in the aerosol. The importance of pyrolysis (at lower MCE), as opposed to glowing (at higher MCE), in producing BrC is seen in the increase of AAE with lower MCE (r2 =  0.65).

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Ageing and hygroscopicity variation of black carbon particles in Beijing measured by a quasi-atmospheric aerosol evolution study (QUALITY) chamber

Atmospheric Chemistry and Physics ◽

10.5194/acp-17-10333-2017 ◽

2017 ◽

Vol 17 (17) ◽

pp. 10333-10348 ◽

Cited By ~ 21

Author(s):

Jianfei Peng ◽

Min Hu ◽

Song Guo ◽

Zhuofei Du ◽

Dongjie Shang ◽

...

Keyword(s):

Black Carbon ◽

Atmospheric Aerosol ◽

Ambient Air ◽

Reaction Chamber ◽

Flow Chamber ◽

Study Quality ◽

Hygroscopic Growth ◽

Coating Materials ◽

Average Growth ◽

Evolution Study

Abstract. Measurements of ageing and hygroscopicity variation of black carbon (BC) particles in Beijing were conducted using a 1.2 m3 quasi-atmospheric aerosol evolution study (QUALITY) chamber, which consisted of a bottom flow chamber through which ambient air was pulled continuously and an upper reaction chamber where ageing of BC particles occurred. Within the reaction chamber, transmission of the solar ultraviolet irradiation was approximately 50–60 %, wall loss of primary gaseous pollutants was negligible, and BC exhibited a half-lifetime of about 3–7 h. Typically, equilibrium for the primary gases, temperature and relative humidity between the reaction chamber and ambient air was established within 1 h. Rapid growth of BC particles occurred, with an average total growth of 77 ± 33 nm and average growth rate of 26 ± 11 nm h−1. Secondary organic aerosols (SOA) accounted for more than 90 % of the coating mass. The O ∕ C ratio of SOA was 0.5, lower than the ambient level. The hygroscopic growth factor of BC particles decreased slightly with an initial thin coating layer because of BC reconstruction, but subsequently increased to 1.06–1.08 upon further ageing. The κ (kappa) values for BC particles and coating materials were calculated as 0.035 and 0.040 at the subsaturation and supersaturation conditions, respectively, indicating low hygroscopicity of coated SOA on BC particles. Hence, our results indicate that initial photochemical ageing of BC particles leads to considerable modifications to morphology and optical properties but does not appreciably alter the particle hygroscopicity in Beijing.

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A novel method for online analysis of gas and particle composition: description and evaluation of a Filter Inlet for Gases and AEROsols (FIGAERO)

Atmospheric Measurement Techniques ◽

10.5194/amt-7-983-2014 ◽

2014 ◽

Vol 7 (4) ◽

pp. 983-1001 ◽

Cited By ~ 169

Author(s):

F. D. Lopez-Hilfiker ◽

C. Mohr ◽

M. Ehn ◽

F. Rubach ◽

E. Kleist ◽

...

Keyword(s):

Optical Sensors ◽

Particle Morphology ◽

Field Measurements ◽

Ambient Air ◽

Molecular Composition ◽

Ionization Mass ◽

Desorption Process ◽

Particle Composition ◽

Temperature Programmed ◽

Chamber Studies

Abstract. We describe a novel inlet that allows measurement of both gas and particle molecular composition when coupled to mass spectrometric, chromatographic, or optical sensors: the Filter Inlet for Gases and AEROsols (FIGAERO). The design goals for the FIGAERO are to allow unperturbed observation of ambient air while simultaneously analyzing gases and collecting particulate matter on a Teflon® (hereafter Teflon) filter via an entirely separate sampling port. The filter is analyzed periodically by the same sensor on hourly or faster timescales using temperature-programmed thermal desorption. We assess the performance of the FIGAERO by coupling it to a high-resolution time-of-flight chemical-ionization mass spectrometer (HRToF-CIMS) in laboratory chamber studies of α-pinene oxidation and field measurements at a boreal forest location. Low instrument backgrounds give detection limits of ppt or lower for compounds in the gas-phase and in the picogram m−3 range for particle phase compounds. The FIGAERO-HRToF-CIMS provides molecular information about both gases and particle composition on the 1 Hz and hourly timescales, respectively for hundreds of compounds. The FIGAERO thermal desorptions are highly reproducible (better than 10%), allowing a calibrated assessment of the effective volatility of desorbing compounds and the role of thermal decomposition during the desorption process. We show that the often multi-modal desorption thermograms arising from secondary organic aerosol (SOA) provide additional insights into molecular composition and/or particle morphology, and exhibit changes with changes in SOA formation or aging pathways.

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Integrated method for the measurement of trace atmospheric bases

Atmospheric Measurement Techniques Discussions ◽

10.5194/amtd-4-6007-2011 ◽

2011 ◽

Vol 4 (5) ◽

pp. 6007-6040 ◽

Cited By ~ 1

Author(s):

D. Key ◽

J. Stihle ◽

J.-E. Petit ◽

C. Bonnet ◽

L. Depernon ◽

...

Keyword(s):

Nitrogen Cycle ◽

Field Measurements ◽

Ambient Air ◽

Integrated Approach ◽

Urban Park ◽

Sampling Strategies ◽

Road Vehicles ◽

Integrated Method ◽

The Many ◽

Global Nitrogen Cycle

Abstract. Nitrogenous atmospheric bases are thought to play a key role in the global nitrogen cycle, but their sources, transport, and sinks remain poorly understood. Of the many methods available to measure such compounds in ambient air, few meet the current need of being applicable to the complete range of potential analytes and fewer still are convenient to implement using instrumentation that is standard to most laboratories. In this work, an integrated approach to measuring trace atmospheric nitrogenous bases has been developed and validated. The method uses a simple acid scrubbing step to capture and concentrate the bases as their phosphite salts, which then are derivatized and analyzed using GC/MS and/or LC/MS. The advantages of both techniques in the context of the present measurements are discussed. The approach is sensitive, selective, reproducible, as well as convenient to implement and has been validated for different sampling strategies. The limits of detection for the families of tested compounds are suitable for ambient measurement applications, as supported by field measurements in an urban park and in the exhaust of on-road vehicles.

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Field measurements of trace gases and aerosols emitted by peat fires in Central Kalimantan, Indonesia during the 2015 El Niño

10.5194/acp-2016-411 ◽

2016 ◽

Cited By ~ 4

Author(s):

Chelsea E. Stockwell ◽

Thilina Jayarathne ◽

Mark A. Cochrane ◽

Kevin C. Ryan ◽

Erianto I. Putra ◽

...

Keyword(s):

Optical Properties ◽

El Niño ◽

El Nino ◽

Trace Gases ◽

Field Measurements ◽

Optical Data ◽

Trace Gas ◽

Aerosol Optical Properties ◽

Central Kalimantan ◽

Peat Fires

Abstract. Peat fires in Southeast Asia have become a major annual source of trace gases and particles to the regional-global atmosphere. The assessment of their influence on atmospheric chemistry, climate, air quality, and health has been uncertain partly due to a lack of field measurements of the smoke characteristics. During the strong 2015 El Niño event we deployed a mobile smoke sampling team in the Indonesian province of Central Kalimantan on the island of Borneo and made the first, or rare, field measurements of trace gases, aerosol optical properties, and aerosol mass emissions for authentic peat fires burning at various depths in different peat types. This paper reports the trace gas and aerosol measurements obtained by Fourier transform infrared spectroscopy, whole air sampling, photoacoustic extinctiometers (405 and 870 nm), and a small subset of the data from analyses of particulate filters. The trace gas measurements provide emission factors (EFs, g compound per kg biomass burned) for CO2, CO, CH4, non-methane hydrocarbons up to C10, 15 oxygenated organic compounds, NH3, HCN, NOx, OCS, HCl, etc.; up to ~90 gases in all. The modified combustion efficiency (MCE) of the smoke sources ranged from 0.693 to 0.835 with an average of 0.772 ± 0.053 (n = 35) indicating essentially pure smoldering combustion and the emissions were not initially strongly lofted. The major trace gas emissions by mass (EF as g/kg) were: carbon dioxide (1564 ± 77), carbon monoxide (291 ± 49), methane (9.51 ± 4.74), hydrogen cyanide (5.75 ± 1.60), acetic acid (3.89 ± 1.65), ammonia (2.86 ± 1.00), methanol (2.14 ± 1.22), ethane (1.52 ± 0.66), dihydrogen (1.22 ± 1.01), propylene (1.07 ± 0.53), propane (0.989 ± 0.644), ethylene (0.961 ± 0.528), benzene (0.954 ± 0.394), formaldehyde (0.867 ± 0.479), hydroxyacetone (0.860 ± 0.433), furan (0.772 ± 0.035), acetaldehyde (0.697 ± 0.460), and acetone (0.691 ± 0.356). These field data support significant revision of the EFs for CO2 (−8 %), CH4 (−55 %), NH3 (−86 %), CO (+39 %) and other gases compared with widely-used recommendations for tropical peat fires based on a lab study of a single sample published in 2003. BTEX compounds (benzene, toluene, ethylbenzene, xylenes) are important air toxics and aerosol precursors and were emitted in total at 1.5 ± 0.6 g/kg. Formaldehyde is probably the air toxic gas most likely to cause local exposures that exceed recommended levels. The field results from Kalimantan were in reasonable agreement with recent (2012) lab measurements of smoldering Kalimantan peat for “overlap species,” lending importance to the lab finding that burning peat produces large emissions of acetamide, acrolein, methylglyoxal, etc., which were not measureable in the field with the deployed equipment and implying value in continued similar efforts. The aerosol optical data measured include EFs for the scattering and absorption coefficients (EF Bscat and EF Babs, m2/kg fuel burned) and the single scattering albedo (SSA) at 870 and 405 nm, as well as the absorption Ångstrӧm exponents (AAE). By coupling the absorption and co-located trace gas and filter data we estimated black carbon (BC) EFs (g/kg) and the mass absorption coefficient (MAC, m2/g) for the bulk organic carbon (OC) due to brown carbon (BrC). Consistent with the minimal flaming, the emissions of BC were negligible (0.0055 ± 0.0016 g/kg). Aerosol absorption at 405 nm was ~52 times larger than at 870 nm and BrC contributed ~96 % of the absorption at 405 nm. Average AAE was 4.97 ± 0.65 (range, 4.29–6.23). The average SSA at 405 nm (0.974 ± 0.016) was marginally lower than the average SSA at 870 nm (0.998 ± 0.001). These data facilitate modeling climate-relevant aerosol optical properties across much of the UV/visible spectrum and the high AAE and lower SSA at 405 nm demonstrate the dominance of absorption by the organic aerosol. Comparing the Babs at 405 nm to the simultaneously measured OC mass on filters suggests a low MAC (~0.1) for the bulk OC, as expected for the low BC / OC ratio in the aerosol. The importance of pyrolysis (at lower MCE), as opposed to glowing (at higher MCE), in producing BrC is seen in the increase of AAE with lower MCE (r2 = 0.65).

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Detection of Volcanic Plumes by GPS: the 23 November 2013 Episode on Mt. Etna

Annals of Geophysics ◽

10.4401/ag-6622 ◽

2015 ◽

Vol 57 ◽

Author(s):

Massimo Aranzulla ◽

Flavio Cannavò ◽

Simona Scollo

Keyword(s):

Signal To Noise Ratio ◽

Explosive Eruptions ◽

Volcanic Plume ◽

Test Case ◽

Signal To Noise ◽

Volcanic Plumes ◽

Gps Network ◽

Mt Etna ◽

New Challenges ◽

Aviation Operations

The detection of volcanic plumes produced during explosive eruptions is important to improve our understanding on dispersal processes and reduce risks to aviation operations. The ability of Global Position-ing System (GPS) to retrieve volcanic plumes is one of the new challenges of the last years in volcanic plume detection. In this work, we analyze the Signal to Noise Ratio (SNR) data from 21 permanent stations of the GPS network of the Istituto Nazionale di Geofisica e Vulcanologia, Osservatorio Etneo, that are located on the Mt. Etna (Italy) flanks. Being one of the most explosive events since 2011, the eruption of November 23, 2013 was chosen as a test-case. Results show some variations in the SNR data that can be correlated with the presence of an ash-laden plume in the atmosphere. Benefits and limitations of the method are highlighted.

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