AS3.21

Atmospheric transformation processes have been extensively studied in the laboratory using simulation chambers with various designs and materials. These tools allow  kinetic experiments to be performed under well-controlled conditions whereby a selected volatile organic compound (VOC) is usually oxidized in synthetic air. While atmospheric chambers are invaluable to provide kinetic parameters that are needed in atmospheric chemical mechanisms, their limitation is that they do not test these chemical mechanisms under conditions that are representative of the complex atmosphere, i.e. containing multiple VOCs and inorganic species.

In the present work, a mobile rectangular atmospheric simulation chamber of ~ 9 m³, made of Teflon FEP foils, was built at IMT Lille Douai for laboratory and field studies. The whole setup – called DouAir – can be easily disassembled, transported and deployed in the field. This new tool allows trapping of real air masses on-site, providing observations on the fate of reactive trace gases, which when compared to box model simulations can provide a critical test of our understanding of atmospheric chemistry. The chamber allows both solar and artificial irradiation, the irradiance being monitored by spectroradiometry. The chamber is equipped with a large array of analytical instruments, including PTR-ToFMS and GC-MS for VOC measurements, CRM for total OH reactivity, PERCA for peroxy radicals, O₃ and NO_x analyzers, and SMPS for aerosols. Here we describe the DouAir setup and will discuss characterization experiments carried out to validate the chamber. DouAir was tested for the first time during an intensive field campaign in the Landes forest (France) during summer 2018: CERVOLAND (Characterization of Emissions and Reactivity of Volatile Organic Compounds in the Landes Forest). Examples of experiments performed during CERVOLAND will be presented.

How to cite: Bouzidi, H., Lahib, A., Reijrink, N., Duncianu, M., Perraudin, E., Flaud, P.-M., Villenave, E., Williams, J., Tomas, A., and Dusanter, S.: Characterization of a mobile atmospheric simulation chamber for laboratory and field studies: DouAir, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-14592, https://doi.org/10.5194/egusphere-egu21-14592, 2021.

Experiments at atmospherically relevant conditions were performed in the simulation chamber SAPHIR, investigating the reaction of isoprene with NO₃ and its subsequent oxidation. Due to the production of NO₃ from the reaction of NO₂ with O₃ as well as the formation of OH in subsequent reactions, the reactions of isoprene with O₃ and OH were estimated to contribute up to 15% of the total isoprene consumption each in these experiments. The ratio of RO₂ to HO₂ concentrations was varied by changing the reactant concentrations, which modifies the product distribution from bimolecular reactions of the nitrated RO₂. The reaction with HO₂ or NO₃ was found to be the main bimolecular loss process for the RO₂ radicals under all conditions examined.

Yields of the first-generation isoprene oxygenated nitrates as well as the sum of methyl vinyl ketone (MVK) and methacrolein (MACR) were determined by high resolution proton mass spectrometry using the Vocus PTR-TOF. The experimental time series of these products are compared to model calculations based on the MCM v3.3.1,¹ the isoprene mechanism as published by Wennberg et al.² and the newly developed FZJ-NO₃-isoprene mechanism,³ which incorporates theory-based rate coefficients for a wide range of reactions.

Among other changes, the FZJ-NO₃-isoprene mechanism contains a novel fast oxidation route through the epoxidation of alkoxy radicals, originating from the formation of nitrated peroxy radicals. This inhibits the formation of MVK and MACR from the NO₃-initiated oxidation of isoprene to practically zero, which agrees with the observations from chamber experiments. In addition, the FZJ-NO₃-isoprene mechanism increases the level of agreement for the main first-generation oxygenated nitrates.

¹ M. E. Jenkin, J. C. Young and A. R. Rickard, The MCM v3.3.1 degradation scheme for isoprene, Atmospheric Chem. Phys., 2015, 15, 11433–11459.

² P. O. Wennberg at al., Gas-Phase Reactions of Isoprene and Its Major Oxidation Products, Chem. Rev., 2018, 118, 3337–3390. 

³ L. Vereecken et al., Theoretical and experimental study of peroxy and alkoxy radicals in the NO3-initiated oxidation of isoprene, Phys. Chem. Chem. Phys., submitted.

How to cite: Carlsson, P. T. M., Vereecken, L., Novelli, A., Bernard, F., Bohn, B., Brown, S. S., Cho, C., Crowley, J., Hofzumahaus, A., Mellouki, A., Reimer, D., Rohrer, F., Shenolikar, J., Tillmann, R., Zhou, L., Kiendler-Scharr, A., Wahner, A., and Fuchs, H.: The role of radical chemistry in the product formation from nitrate radical initiated gas-phase oxidation of isoprene, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-7338, https://doi.org/10.5194/egusphere-egu21-7338, 2021.

The chemistry of the atmosphere is usually studied using three different approaches, i.e. field measurements, laboratory studies and chemical model calculations. All three are complementary and powerful means to investigate chemical transformations of pollutants and improve our understanding of the atmosphere. Atmospheric simulation chambers are one of the most direct and critical approaches to mimic and examine chemical transformations under controlled experimental conditions. In combination with box model simulations, they allow assessment of the accuracy of chemical mechanisms implemented in atmospheric models.

During the CERVOLAND field campaign (Characterisation of Emissions and Reactivity of Volatile Organic compounds in the LANDes forest) we deployed a new mobile atmospheric chamber (DouAir) to probe the oxidation of biogenic volatile organic compounds (BVOCs) in real air masses. Biogenic compounds emitted by the surrounding forest (mainly pines - (Maritime pine, Pinus pinaster Ait) were trapped in DouAir and their transformations were probed using state-of-the-art online instrumentation, including PTR-ToF-MS (VOCs), PERCA (peroxy radicals), O₃ and NO_x analysers, and SMPS (aerosols).

The objectives of the present study were to (1) reproduce in the laboratory selected field experiments performed during CERVOLAND, the chemical composition of the air mass being simplified, and (2) compare both the field and laboratory results to 0-D box model simulations using the Master Chemical Mechanisms (MCM). Comparing field observations, laboratory experiments and model simulations provides a critical test of our understanding of atmospheric oxidation processes involving biogenic compounds.

Here, we present ozonolysis experiments of primary biogenic VOCs (mainly monoterpenes) under dark conditions. Initial conditions used for the laboratory experiments were derived from reactant concentrations trapped in DouAir during CERVOLAND. The results show the capability of the model to reproduce oxidation rates of primary VOCs within uncertainty, although the model considerably overestimates measured peroxy radical concentrations. The addition of rapid self- and cross-reactions of monoterpene-derived peroxy radicals in the MCM improves the agreement with the measured peroxy radical concentrations.

How to cite: Lahib, A., Bouzidi, H., Reijrink, N., Duncianu, M., Perraudin, E., Flaud, P.-M., Villenave, E., Williams, J., Tomas, A., and Dusanter, S.: Investigating monoterpene ozonolysis reactions in the mobile DouAir atmospheric simulation chamber: field and laboratory experiments, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-14892, https://doi.org/10.5194/egusphere-egu21-14892, 2021.

Of the total global annual monoterpene emissions, Δ³-carene contributes 4.5 %, making it the 7^th most abundant monoterpene worldwide. As it is primarily emitted by pine trees, Δ³-carene can regionally gain in importance, for example in boreal forests and Mediterranean regions.  Oxidation products of monoterpenes such as organic nitrates and aldehydes are known to impact the formation of secondary pollutants such as ozone and particles, so understanding their atmospheric formation and fate is crucial.

The photooxidation and ozonolysis of Δ³-carene and the photooxidation and photolysis of its main daytime photooxidation product caronaldehyde were investigated in the atmospheric simulation chamber SAPHIR. Oxidation reactions were studied under atmospheric conditions with high (> 8 ppbv) and low (< 2 ppbv) NOx concentrations. Reaction rate constants of the reaction of Δ³-carene with OH and O₃, and of the reaction of caronaldehyde with OH as well as photolysis frequencies of caronaldehyde were determined. Production and destruction rates of the sum of hydroxyl and peroxy radicals (ROx = OH+HO2+RO2) were analysed to determine if there were unaccounted production and loss processes of radicals in the oxidation of Δ³-carene. The yield of Δ³-carene’s oxidation product caronaldehyde was determined from measured timeseries from OH photooxidation and ozonolysis experiments. Additionally, the OH yield from ozonolysis of Δ³-carene was determined.

Organic nitrate (RONO₂) yields of the reaction of RO₂ + NO, from RO₂ produced from the reactions of Δ³-carene and caronaldehyde with OH were determined by analyzing the reactive nitrogen species (NOy) in the chamber.

How to cite: Hantschke, L., Novelli, A., Bohn, B., Cho, C., Reimer, D., Tillmann, R., Rohrer, F., Glowania, M., Hofzumahaus, A., Wahner, A., Kiendler-Scharr, A., and Fuchs, H.: Photooxidation and ozonolysis of Δ3-carene and its oxidation product caronaldehyde in the atmospheric simulation chamber SAPHIR, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-1284, https://doi.org/10.5194/egusphere-egu21-1284, 2021.

Phthalates are chemical species widely used as plasticisers that are known to be absorbed by living organisms and negatively affect their health. Phthalates have been detected mostly indoors. For example, they have been measured in the gas phase, as part of particulate matter and on different surfaces in the form of dust.^1-4 Although their presence in this kind of environments is well known and widely documented, there are scarce studies on their behaviour when they are in contact with tropospheric oxidants such as ozone (O₃) or hydroxyl radicals.^5-7

The aim of this work is to measure, for the first time, the kinetics of the gas-phase reaction of O₃ with two phthalates: dimethyl phthalate (DMP) and diethyl phthalate (DEP). In a smog chamber at room temperature and atmospheric pressure, decay rates of DMF or DEF are measured by a Proton Transfer-Time of Flight-Mass Spectrometer (PTR-ToF-MS), while the O₃ concentration is determined by Fourier Transform Infrared (FTIR) spectroscopy. Gas-phase products are also monitored by PTR-ToF-MS and secondary organic aerosol (SOA) formation is also evaluated by a Fast Mobility Particle Sizer. The impact on the indoor air quality of DMP and DEP will be discussed considering their atmospheric lifetime and the generated products.

REFERENCES: 1. Bornehag, C.G.; Lundgren, B.; Weschler, C. J.; Sigsgaard, T.; Hagerhed-Engman, L.; Sundell, J. Environ. Health Perspect. 2005, 113, 1399-404; 2. Rudel, R. A.; Perovich, L. J. Atmos. Environ. 2009, 43, 170‑181; 3. Fromme, H.; Lahrz, T.; Piloty, M.; Gebhart, H.; Oddoy, A.; Rüden, H. Indoor Air 2004, 14, 188-195; 4. Larsson, K.; Lindh, C. H.; Jönsson, B.A.; Giovanoulis, G.; Bibi, M.; Bottai, M.; Bergström, A.; Berglung, M. Environ. Int. 2017, 102, 114-124; 5. Mansouri, L.; Mohammed, H.; Tizaoui, C.; Bousselmi, L. Desalination Water Treat. 2013, 51, 6698-6710; 6. Mohan, S.; Mamane, H.; Avisar, D.; Gozlan, I.; Kaplan, A.; Dayalan, G. Materials 2019, 12, 4119 (3); 7. Dueñas Moreno, J.; Rodríguez S, J.L.; Poznyak, T.; Chairez, I.; Dorantes-Rosales, H.J. J. Environ. Manage. 2020, 270, 110863 (7).

How to cite: Antiñolo, M., Baeza, M. T., Jiménez, E., and Albaladejo, J.: Gas-phase O3 reaction of dimethyl phthalate and diethylphthalate: a kinetic and product study, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-10814, https://doi.org/10.5194/egusphere-egu21-10814, 2021.

The Jülich Atmospheric Chemistry Project campaign (JULIAC) was performed using the atmospheric simulation chamber SAPHIR at Forschungszentrum Jülich (FZJ), Germany. Ambient air was continuously drawn into the chamber through a 50m high inlet line for one month in each season throughout 2019. The residence time of air inside the chamber was one hour. As the sampling point is surrounded by a mixed deciduous forest and is located close to a small–size city (Jülich), the sampled air was influenced by both anthropogenic and biogenic emissions. Measurements included hydroxyl radical (OH) achieved by laser induced fluorescence (LIF) instrument that implemented a newly implemented chemical modulation reactor (CMR) and by differential optical absorption spectroscopy (DOAS). Measurement of both instruments were in good agreement within about 10% and showed no evidence of unknown OH interferences. In addition to OH, hydroxyl and peroxy radicals (HO₂ and RO_2, respectively), and OH reactivity (k_OH, inverse of the OH lifetime) were measured together with a comprehensive set of trace gases concentrations and aerosol properties, allowing for the investigation of the seasonal and diurnal variation of atmospheric oxidant concentrations and their roles in the degradation of volatile organic compounds (VOCs) and contribution to secondary pollutants (ozone and particles).

The experimental budget analyses of OH, HO₂, RO_2, and RO_x radical production and destruction rate will be presented for the campaigns in spring and summer (April and August). For most conditions, the concentrations of radicals were sustained by regeneration of HO₂ and RO₂ radicals via reactions with nitric oxide (NO). The highest radical turnover rates of up to 17 ppbv·hr^-1 was observed during a heat wave period in August. For NO levels below 1ppbv, the budget shows a missing OH radical source up to 4 ppbv h^-1, while HO₂ and RO₂ productionand destruction rates were balanced. Above 2 ppbv of NO, missing HO₂ production and RO₂ loss paths with rates of up to 5 ppbv h^-1 were found. In addition, the dataset allows for a detail examination of the importance of radical production and destruction processes from isomerization reactions, HO₂ uptake on aerosol, chlorine nitrate chemistry.

How to cite: Cho, C., Hofzumahaus, A., Fuchs, H., Holland, F., Bohn, B., Bloss, W. J., Dorn, H.-P., Glowania, M., Hohaus, T., Lu, L., Lakshmisha, C., Niether, D., Monks, P. S., Reimer, D., Rohrer, F., Sommariva, R., Tan, Z., Tillmann, R., Kiendler-Scharr, A., and Wahner, A.: Experimental budgets of OH, HO2 and RO2 radicals during the JULIAC 2019 campaign, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-2344, https://doi.org/10.5194/egusphere-egu21-2344, 2021.

For the Jülich Atmospheric Chemistry Project campaign (JULIAC) at Forschungszentrum Jülich (FZJ), Germany, the atmospheric simulation chamber SAPHIR was used as a large photochemical flow reactor to study tropospheric chemistry in a rural environment. From an inlet at 50 m height above ground, ambient air was continuously fed through the chamber and exposed to natural solar radiation. A large set of instrumentation allowed for the measurement of NO, NO₂, NO₃, N₂O₅, ClNO₂, HCHO, HONO, RO₂, HO₂, OH, k_OH, CO, CO₂, CH₄, H2O, VOCs, aerosols, and O₃ in the sampled air. Intensive measurement phases were performed for one month in each season of 2019. One goal of the JULIAC project was to test our understanding of the chemistry of tropospheric ozone formation.

To determine the photochemical net ozone production rate in atmospheric air, O_X (O₃ + NO₂) was measured by commercial instruments at the inlet and inside the well mixed chamber. Through careful characterization of the flow reactor it is possible to predict a reference concentration of O_X from the inflow measurements which excludes photochemistry. The measured O_X concentration in the chamber was compared with the reference. At night, both concentrations agreed, but during daytime the chamber concentration was enhanced due to photochemical O_X production. The difference was used to determine diurnal profiles of the net ozone production with 1 hour time resolution. Production rates up to 15 ppbv/h were observed with an accuracy of 1 ppb_V/h. Uncertainties in the offsets of the instruments measuring at the inlet and inside the chamber were identified as large contributors (~0.5 ppb_V/h) to the overall error. The measured net ozone production rates are compared to production rates that are expected from the reactions of peroxy radicals (HO₂, RO₂) with NO, all of which were concurrently measured. The analysis includes other chemical reactions that may produce or destroy ozone or NO₂ in the lower troposphere.

Good agreement (within 10%) between measured and calculated ozone production rates during the spring and summer campaigns confirms that the main contributions to daytime O_X production and destruction in the troposphere are overall governed by the reactions of HO₂ and RO₂ with NO and the reaction of OH radicals with NO₂ in the rural environment studied in this project. The presentation will include a discussion of the role of the OH reactivity from VOCs for the local photochemical ozone production.

How to cite: Niether, D., Cho, C., Rohrer, F., Hofzumahaus, A., Novelli, A., Holland, F., Fuchs, H., Wesolek, C., Bohn, B., Wahner, A., Kiendler-Scharr, A., and Tillmann, R.: Seasonal ozone production rate measurements by use of SAPHIR as a large continuous flow reactor during the JULIAC campaign, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-7963, https://doi.org/10.5194/egusphere-egu21-7963, 2021.

Monoterpene plays an important role in the formation of secondary aerosols and ozone in the troposphere. However, the field characterization of monoterpene chemistry in ozone pollution is still very sparse. Here we report fast daytime oxidation of monoterpene by hydroxyl radical, nitrate radical and ozone based on field measurements in Eastern China. We find fast monoterpene oxidation produces peroxy radicals efficiently and enhances the photochemical ozone production largely with an additional 8.6 ppb of ozone production per day on average (14%), whose effect was even more important than that of isoprene chemistry in the analyzed dataset. We propose that the reduction of anthropogenic volatile organic compounds should be much more stringent in the presence of high monoterpenes to alleviating ozone pollution.

How to cite: Wang, H.: Unexpected Fast Monoterpene Oxidation In Eastern China, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-15908, https://doi.org/10.5194/egusphere-egu21-15908, 2021.

Aircraft observations of ozone, ozone precursors, and meteorological parameters were made over the New York City (NYC) and Baltimore areas during ozone exceedance events in summer 2018-2020.  Despite the continued reduction in anthropogenic emissions, ozone exceedance events still frequently occurred in the NYC area.  Ozone production efficiency, defined as the ratio of the ozone production rate to the NO_x oxidation rate, calculated using these observations,  was about 14 ppb ozone produced per ppb NOx oxidized. This high ozone production efficiency likely contributes to the persistent ozone exceedance problem over the Long Island Sound and Connecticut coastal area, downwind of NYC under prevailing southwesterly winds.  There is some evidence for a decreasing trend although COVID-19 restrictions had an impact on 2020 emissions.  A box model, constrained by observations, was used to examine atmospheric photochemical oxidation processes.  Ozone production rates and their sensitivity to nitrogen oxides (NO_x) and volatile organic compounds (VOCs) were calculated based on the model results. In general ozone production is VOC sensitive near emission sources and NOx sensitive away from source regions. While the Baltimore area is predominantly in the NOx sensitive region, the NYC area is transitioning from VOC sensitive to NOx sensitive.  Preliminary results show that controlling both NOx and VOCs reduces ozone production in the NYC area. Reducing VOCs can reduce ozone production in emission source regions and reducing NOx can reduce ozone production farther away from the source regions. The results from this work strengthen our understanding of ozone production and provide scientific information for emission control strategies to reduce air pollution in ozone non-attainment areas.

How to cite: Ren, X., Stratton, P., Daley, H., and Dickerson, R.: Ozone Photochemistry in New York City and Baltimore based on Aircraft Observations, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-6953, https://doi.org/10.5194/egusphere-egu21-6953, 2021.

It is well known that the high population density of urban regions leads to significant degradation of the quality of the air because of the emissions of pollutants that are by-products of energy production, transportation, and industry. The composition and chemistry of urban air has been studied for many decades and these studies have led to detailed understanding of the factors controlling, for example, the formation of ozone, peroxyacetyl nitrate and other secondary species. In the last 20 to 30 years, significant progress has been made in reducing emissions of volatile organic compounds (VOCs) and oxides of nitrogen (NO_x) in urban atmospheres. Substantial reductions in the abundance of secondary compounds, though, have been more elusive.

Research has continued to reveal more and more details of the complex processes involved in the atmospheric degradation of wide varieties of volatile organic compounds (VOCs) of anthropogenic and biospheric (BVOCs) origins. BVOCs include isoprene, monoterpenes and sesquiterpenes, and oxygenated VOCs (OVOCs, such as small alcohols). Emissions of BVOCs depend on several factors such as plant or tree species, temperature, and photosynthetically active radiation. They consist almost exclusively of unsaturated compounds with chemistry somewhat different from those of typical urban organic compound emissions. Oxidation of VOCs can lead to molecules of low volatility that are prone to uptake into the aerosol phase.

Recent studies conducted in megacities such as Paris, Mexico City, Los Angeles and those in China have led to significant advances in our understanding of the chemical evolution of urban plumes. However, important scientific questions remain on how mixing of anthropogenic and biogenic air masses modifies the composition of urban plumes and hence their impacts. Indeed, the proximity of cites to areas of strong biogenic emissions is not unusual. Many major cities at mid-latitudes are surrounded by forested areas.

ACROSS (Atmospheric ChemistRy Of the Suburban foreSt) is an integrative, innovative, multi-scale project awarded under the “Make Our Planet Great Again” (MOPGA) framework that seeks to definitively improve understanding of the impacts of mixing urban and biogenic air masses on the oxidation of atmospheric VOCs. The ACROSS working hypothesis is that this leads to changes in the production of oxygenated VOCs whose properties (e.g. vapor pressures) alter their importance in incorporation into SOA and their roles in production of ozone and other secondary species. Changes are also expected in the efficiency of radical recycling affecting the atmospheric oxidative capacity. Particularly important is NO_x transport to suburban biogenic environments and the resulting modification of key chemical processes.

A key highlight of ACROSS is an intensive, multi-platform measurement campaign in the summer of 2022. It will use instruments staged on an airborne platform, a tower in the Rambouillet Forest near Paris, and other ground sites. The data collected from this campaign will be analyzed and studied to extract information about tropospheric oxidation chemistry generally, but also changes observed in the situation of mixed urban and biogenic air masses.

This presentation will summarize plans for the ACROSS campaign.

How to cite: Cantrell, C., Michoud, V., Formenti, P., Doussin, J.-F., Alhajj Moussa, S., Cirtog, M., Gratien, A., and Picquet-Varrault, B. and the ACROSS Team: A Future Multi-Platform Atmospheric Chemistry Measurement Campaign to Study Oxidation in Mixed Anthropogenic-Biogenic Air Masses, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-15448, https://doi.org/10.5194/egusphere-egu21-15448, 2021.

As secondary organic aerosols (SOA) largely contribute to the mass of particles and may strongly affect health, it is essential to represent them as accurately as possible in air quality models (AQM). Their formation and aging involve multi-generation oxidations of numerous volatile organic compounds (VOC) combined with gas-particle partitioning processes.
 
Tracking the non-linear relationship between VOC emissions and aerosol formation demands comprehensive chemical mechanisms, which take into account the whole complexity of the SOA precursor oxidation to simulate aerosols under various conditions.
However, the use of explicit gas-phase chemical mechanism (e.g., MCM, GECKO-A) or molecular structure-limited parameterization (e.g., VBS, SOM, FGOM) could be problematical in large-scale SOA modeling, as the former is overwhelmingly computational expensive while the latter loses tracks of VOC oxidation products after few generations and specific properties relying on aerosol formation.
 
Consequently, we have developed semi-explicit SOA chemical mechanisms designed to model the SOA formation and evolution in 3D AQM. These mechanisms are reduced based on simulations of the near-explicit master chemical mechanism (MCM) performed under various conditions representative of ambient conditions and different lumping strategies. The new mechanisms integrate the crucial SOA species/reactions with different mechanism complexities. The mechanisms, therefore, preserve the complexity of the oxidation chemistry (dependence on NOx of the SOA formation, the influence of radical concentrations, humidity, photolysis, etc..) as well as the molecular composition of the organic aerosol. The mechanisms are implemented in a novel 0D aerosol model SSH-aerosol, which can use the molecular structure of lumped compounds to estimate the influence of non-ideality on SOA formation.

The current application has been conducted on the MCM degradation scheme of beta-caryophyllene (C₁₅H₂₄), the most representative sesquiterpene. A reduction of the average 90% CPU time and up to 92% number of S/IVOCs species has been achieved compared to the original MCM mechanism.

How to cite: Wang, Z., Couvidat, F., and Sartelet, K.: Automatic generation from MCM of reduced mechanisms to study the formation and evolution of SOA in 3D air quality models, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-1390, https://doi.org/10.5194/egusphere-egu21-1390, 2021.

Biomass is a significant renewable energy source and is expected to grow in importance in the transition away from fossil energy sources at a relatively low cost. Lignocellulosic biomass, which is the most abundant biomass, has critical importance as sustainable production of chemicals and fuels. Catalytic production methods of converting lignocellulosic biomass into furan derivatives have been improved significantly. One of these furan derivatives, 2,5-dimethylfuran (2,5-DMF), has attracted interest as a potential biofuel due to its physicochemical properties, in some aspects better than gasoline and ethanol, such as the low pollutant emissions in its combustion. However, before 2,5-DMF can be accepted as an alternative transport fuel, some outstanding problems, as its atmospheric fate, must be resolved.

2,5-DMF can be degraded by the main tropospheric oxidants, resulting in furan derivatives such as furanones which are efficient precursors of SOA. To this end, the present study had the aim of analyzing the OH radical photooxidation and ozonolysis of 2,5-DMF, characterizing the conditions that lead to the formation and growth of new particles. Factors such as relative humidity (RH), NOx and SO₂ level and pre-existing inorganic seed particles, which could influence in SOA formation, has been assessed. The study was carried out in two different chambers at (296±1) K and atmospheric pressure. Results for OH-photooxidation indicate that SOA yields decrease (from 6.2 to 0.4%) with the rise of 2,5-DMF concentration (from10 to 1000 ppb). In the absence of NOx and under high relative humidity (RH) conditions (60%), higher aerosol yields are favored. SOA formation is dependent on the initial seed surface for two kinds of inorganic seed particles ((NH₄)₂SO₄ and CaCl₂), being the effect slightly greater for CaCl₂. The ozonolysis only generates particles in the presence of SO₂ and the increase of relative humidity from 0 to 15% lowers the particle number and particle mass concentrations. The water-to-SO₂ rate constant ratio of the Criegee intermediate was derived from the SOA yield in experiments with different relative humidity values.

The obtained results provide detailed daytime chemistry about SOA formation from 2,5-DMF oxidation and improves our understanding of the chemical evolution of biomass burning plumes. Moreover, these results could be integrated into air quality simulation models, especially in developing countries which are suffering severe fine particulate matter pollution.

How to cite: Rodriguez Cervantes, A., Tajuelo Diaz-Pavón, M., Rodriguez Rodriguez, D., Escalona Verbo, A., Viteri Tovar, G., Aranda Rubio, A., and Diaz de Mera, Y.: Secondary organica aerosol formation from the reactions of 2,5-dimethylfuran with OH radicals and ozone, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-15921, https://doi.org/10.5194/egusphere-egu21-15921, 2021.

Corn is the 1st economic field crop in the world, whose price stability guarantees sustainable and equitable food security. Most previous farm commodity price prediction model only focus on detecting the autoregression of historical transaction, while ignoring other factors. For agricultural commodities, different climate condition leads to different harvest situation, thus bringing volatility to prices. Therefore, it is reasonable to propose a method based on climate indices to measure the degree of their influence on price fluctuation.

A multiple regression model is developed for predicting corn price movements at the nation level. The June-September season is selected to target the essential growing stages of corn which are especially sensitive to drought, high temperature stress and water stress. In order to describe the movements of price, the price difference between June and September is chosen as the dependent variable. Daily climate data are obtained from PRISM which integrates both satellite and meteorological station observation data, and monthly price data are sourced from USDA. 39-year trend from 1981-2019 is explored to construct a predictive model. The results show that the accuracy of predicting up and down of price is 85%. Specifically, temperature in July has an identifiable effect on price movements which explains 36.99% price variation. These results imply that during the key growing period, climate indices occupy an important position on improving crop price forecast ability.

How to cite: Deng, Q. and Sun, X.: The effects of climate on corn price movements in the United States, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-2428, https://doi.org/10.5194/egusphere-egu21-2428, 2021.