AS3.25
Atmospheric transport: from classical particles and gases to airborne microplastics.

AS3.25

EDI
Atmospheric transport: from classical particles and gases to airborne microplastics.
Convener: Silvia BucciECSECS | Co-conveners: Ignacio Pisso, Sabine Eckhardt, Petra Seibert
Presentations
| Thu, 26 May, 13:20–15:45 (CEST)
 
Room 0.11/12

Presentations: Thu, 26 May | Room 0.11/12

Chairpersons: Silvia Bucci, Ignacio Pisso
Atmospheric transport of aerosol and gases
13:20–13:27
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EGU22-6646
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ECS
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On-site presentation
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Jin Maruhashi, Volker Grewe, Christine Frömming, Patrick Jöckel, and Irene Dedoussi

The resilient growth of air travel demands a comprehensive understanding of the climate effects from aviation emissions. The current level of knowledge of the environmental repercussions of CO2 emissions is considerably higher than that of non-CO2 emissions, which includes nitrogen oxides (NOx), sulfur oxides (SOx), other aerosols like black carbon (BC), water vapor and contrails. Aircraft NOx emissions not only possess a high degree of uncertainty because of the non-linearity of the NOx – O3 chemistry, but are also responsible for producing the second strongest net warming effect out of all non-CO2 climate forcers from aviation, right after contrails [1]. This study employs global-scale simulations to characterize the transport patterns of nitrogen oxides and assess their climate effects across several regions (North America, South America, Africa, Eurasia and Australasia) from January to March and July to September in 2014. Radiative forcing effects from the short-term increase in O3, which are triggered by NOx emissions, are estimated. These emissions, which are introduced at a typical cruising altitude, are modelled as Lagrangian air parcels that are transported within the ECHAM5/MESSy Atmospheric Chemistry (EMAC) model [2]. In order to summarize the dynamical and radiative forcing characteristics of more than 10,000 simulated trajectories, a clustering approach with an adapted distance metric is applied. The method itself is an unsupervised machine learning algorithm, called QuickBundles [3], that is most commonly used in the field of neuroscience. A strong seasonal dependence is found for the contribution of NOx emissions to O3. In terms of residence times, NOx emitted in Northern regions resides mainly in the upper mid-latitudes while those initiated in the South remain mostly in the Tropics. Due to pronounced zonal jets, the location of emission does not necessarily correspond to the region that will be most affected, i.e., an emission starting in N. America in July will induce the greatest warming in Europe.

[1] Lee, D.S., Fahey, D.W., Skowron, A., Allen, M.R., Burkhardt, U., Chen, Q., Doherty, S.J., Freeman, S., Forster, P.M., Fuglestvedt, J., Gettelman, A., De León, R.R., Lim, L.L., Lund, M.T., Millar, R.J., Owen, B., Penner, J.E., Pitari, G., Prather, M.J., Sausen, R., Wilcox, L.J.: The contribution of global aviation to anthropogenic climate forcing for 2000 to 2018, Atmospheric Environment, Volume 244, 2021, 117834, ISSN 1352-2310, https://doi.org/10.1016/j.atmosenv.2020.117834.

[2] Jöckel, P., Kerkweg, A., Pozzer, A., Sander, R., Tost, H., Riede, H., Baumgaertner, A., Gromov, S., Kern, B., Development cycle 2 of the Modular Earth Submodel System (MESSy2), Geoscientific Model Development, 3, 717-752, doi: 10.5194/gmd-3-717-2010, 2010.

[3] Garyfallidis, E., Brett, M., Correia, M. M., Williams, G. B., Nimmo-Smith, I. QuickBundles, a Method for Tractography Simplification. Frontiers in neuroscience, 6, 175. https://doi.org/10.3389/fnins.2012.00175, 2012.

How to cite: Maruhashi, J., Grewe, V., Frömming, C., Jöckel, P., and Dedoussi, I.: A Lagrangian study of globally emitted aviation NOx and associated short-term O3 radiative forcing effects, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-6646, https://doi.org/10.5194/egusphere-egu22-6646, 2022.

13:27–13:34
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EGU22-2629
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ECS
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On-site presentation
Mingzhao Liu, Sabine Griessbach, and Lars Hoffmann

Sulfur dioxide (SO2) is one of the most abundant gases released by volcanic eruptions. It is of concern due to its potential to influence climate on the global scale. Next to advection and diffusion, various chemical and geophysical processes need to be considered to properly represent volcanic SO2 plumes in Lagrangian transport simulations. The chemical reaction of SO2 with the hydroxyl radical (OH) and wet deposition are major processes depleting SO2 from volcanic plumes. In this study, we implemented and revised new modules for OH chemistry and wet deposition in the Massive Parallel Trajectory Calculations (MPTRAC) Lagrangian transport model. In MPTRAC, the OH chemistry module adopts the newest JPL data evaluation to calculate the temperature- and pressure-dependent reaction coefficient of the termolecular reaction of SO2 and OH. Similar to other Lagrangian chemistry transport models, monthly mean zonal mean OH fields are applied in the MPTRAC simulations. However, here we propose to introduce a correction factor depending on the solar zenith angle in order to represent the diurnal variations of the OH concentrations. The wet deposition module of MPTRAC mainly uses cloud ice and liquid water content retrieved from ECMWF’s meteorological data as well as an effective Henry constant, considering both, the dissociation and dissolution of SO2 in cloud water. The revised and improved MPTRAC model is evaluated in the case study on the July 2018 eruption of Ambae, Vanuatu, the most voluminous volcano of the New Hebrides archipelago. It is reported that during the eruption, the island of Ambae suffered from acid rain, which means that the volcanic plume encountered clouds and significant wet deposition of SO2 due to precipitation. A series of sensitivity tests was conducted to assess the two new chemistry modules of MPTRAC. An inspection of the time series of SO2 total mass revealed that the diurnal variations due to the OH chemistry are now properly represented in the model. The trajectories of the SO2 parcels have large influence on the wet deposition because they determine whether they pass through cloudy regions or not at a certain time and location. Therefore, it is important to use the most accurate meteorological data and source information. With the revised MPTRAC model, we found that a significant part of the loss of SO2 total mass from the Ambae eruption is represented in the simulations. However, satellite observations reveal even shorter tropospheric lifetimes of the volcanic SO2 plume from the Ambae eruption, which indicates that future work needs to focus on including additional chemical and geophysical processes in the simulations.

How to cite: Liu, M., Griessbach, S., and Hoffmann, L.: Modeling of hydroxyl oxidation and wet deposition in volcanic sulfur dioxide plumes: the July 2018 Ambae eruption, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-2629, https://doi.org/10.5194/egusphere-egu22-2629, 2022.

13:34–13:41
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EGU22-803
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ECS
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On-site presentation
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Anastasia Poliakova, Antony G. Brown, and Inger G. Alsos

The problem of extra-regional long-distance pollen component (LDC) has been known since the first attempts of pollen analysis performed in the early 1920s. In addition, the interpretation of pollen analyses of Arctic sediments is complicated by the typically low concentrations of pollen and spores. Furthermore, local/regional pollen production is low in the Arctic that greatly increases the role of LDC.

In this study, we analysed for pollen and spores lacustrine sediments from Svalbard, Colesdalen valley, lake Tenndammen (N 78°06.118; E 15°02.024) as well as ten soil samples collected from the lake’s shores at ca 2-4 m from the water body. Based on pollen origin, we distinguished three groups: (1) regional pollen, which includes pollen and spores of the plants that are known from local flora of the Colesdalen valley or from Svalbard in whole, (2) exotic pollen, which comprises pollen of plants that are not growing in Svalbard, (3) pollen of mixed or unclear origin, which includes several types; where it is difficult to decide on their actual origin, types which can originate from Svalbard but also typical of the  LDC of other Arctic regions as these plants produce massive amount of pollen that travel with winds and marine currents. In total, 56 pollen taxa were identified from the sediments, whilst 35 pollen types were found in the soil samples. Major changes in pollen assemblages after ca 1900 CE were associated with human impact and three pathways of exotic pollen transport were inferred: long distance wind transportation, transport by bird and by human immigration.

Around 1920 CE, the first introduced plant taxa were identified, i.e., presence of Apiaceae and Fabaceae pollen. Large grains with a thick exines and an annulus diameter of 10.6-13 μm, identified as Poaceae/Cerealia type, were continuously present since ca 1920 CE. Moreover, since ca 1200 CE the contribution of regional pollen, long distance extra-regional pollen, and pollen with mixed and unclear origin in Colesdalen has been relatively stable around 1%, 29%, and 70% respectively. These proportions are also supported by our analyse of the previous palynological studies in Svalbard from 46 publications. Other exotic pollen, including Ulmus, Juglans, and the even more unexpected tropical pollen types of Albizia/Mimosa, Eucalyptus, Acalupha, and Passiflora are exclusively found in the sediments dating to the 1930s-1960s. This is the period associated with the most intensive mining activity and human traffic to and from Colesdalen, including a well-tracked transmigration to the sub-tropical regions and resorts of the former USSR. Additionally, the occurrence of Myrica (gale) type, and Erica type in the sediments throughout the ca 700 yr study period and registered in the soil samples are discussed in terms of geese seasonal migration to and from Scotland (UK), Belgium and the Netherlands. The pollen of Apiaceae, Fabaceae, Saxifragaceae, Campanula, Rosaceae, Papaver, Polemonium type, most likely originate from the regional vegetation. This research provides the first comprehensive examination of the LDC problem in Svalbard palynology, and demonstrates how the history of human occupation and transmigration can be directly reflected in lake sediments.

How to cite: Poliakova, A., Brown, A. G., and Alsos, I. G.: Exotic pollen in sediments from the high Arctic lake Tenndammen, Svalbard archipelago: Aspects of potential pollen sources and transportation ways, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-803, https://doi.org/10.5194/egusphere-egu22-803, 2022.

13:41–13:48
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EGU22-1303
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ECS
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Presentation form not yet defined
Marina Liaskoni, Lukas Bartik, and Peter Huszar

 

Wind-blown dust, emitted from the surface of the earth to the atmosphere as a result of the disintegration of material due to wind drag, can have a significant impact on the atmospheric concentration of PM levels, not only over arid, deserted areas, where their emission occurs, but due to long-range transport over distant areas too. Considering the increasing potential of longer dry periods between days with precipitation in a warming climate, one can expect however, that such emissions could be occasionally considerable also over non-arid areas, like Europe.

 

Here we provide a model based estimate of the regional impact of PM emissions from wind erosion (wind-blown dust - WBD) on urban and rural PM levels for a central European domain using a well-established wind-blown dust module (called ‘‘WBDUST’’) for the 2007-2016 period. As driving meteorological data, we used WRF simulations. WBD emissions were implemented into the CAMx chemistry transport model and we performed simulations with and without these emissions. Our results showed that both urban and rural PM levels are significantly increased if wind-blown dust is considered. The effects of the mineral content of WBD on ion chemistry and consequent effects on aerosol components (secondary (in-)organic aerosol) are analyzed too.

How to cite: Liaskoni, M., Bartik, L., and Huszar, P.: The potential role of wind-blown dust emissions in PM pollution over non-arid areas: a modeling study over Central Europe, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-1303, https://doi.org/10.5194/egusphere-egu22-1303, 2022.

13:48–13:55
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EGU22-4888
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Virtual presentation
Gisele Krysztofiak, Chaoyang Xue, Valéry Catoire, Hans Schlager, Sabine Eckhardt, and Klaus Pfeilsticker

During the SHIVA (Stratospheric Ozone: Halogen Impacts in a Varying Atmosphere) campaign in Nov. and Dec. 2011, polluted air masses were observed in the marine and terrestrial boundary layer (0 – ~2 km) and in the free troposphere (~2 – 12 km) over Borneo/Malaysia. The measurements include CO, CO2, CH4, N2O, NO2, and SO2 as primary pollutants, O3 and HCHO as secondary pollutants, and meteorological parameters. This set of trace gases combined with a Lagrangian particle dispersion model (e.g., FLEXPART) and emission inventories are used to fingerprint different sources (e.g., biomass burning) of local and regional air pollution.

The long-term trend and seasonal variation of biomass burning emissions in this region are first presented and discussed based on the FINN inventory the FLEXPART simulation. Results highlighted the recurrent influence of palm plantation fires near the Miri airport, allowing regular sampling of this fire at different age plumes. The study of the emission ratio compared to CO2 or CO can be used as a measure of combustion efficiency to help define the type of biomass burning. Additionally, the age of plume sampled by the aircraft measurement is determined by FLEXPART and compared with the ΔO3/ΔCO ratio measured in this study and bibliographic database in order to study the ozone production during the transport of biomass burning plumes and implement such database with palm fire data.

How to cite: Krysztofiak, G., Xue, C., Catoire, V., Schlager, H., Eckhardt, S., and Pfeilsticker, K.: Aircraft-Based Measurements of Biomass Burning Emissions of Malaysia Oil Palm Cultivation, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4888, https://doi.org/10.5194/egusphere-egu22-4888, 2022.

13:55–14:02
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EGU22-7206
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ECS
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On-site presentation
Andreas Plach, Markus Leuenberger, and Andreas Stohl

Flux towers are essential tools for collecting measurements of trace gas concentrations/fluxes to investigate source regions of greenhouse gases (GHGs) and other pollutants. Most flux towers provide observations at heights of several meters to tens of meters and therefore only sample potential source regions in their immediate vicinity, i.e., these towers have small so-called footprints. Here we are interested in estimating the footprint of one of the few European tall towers located close to Beromünster, Switzerland. The tower was initially set up as a CarboCount CH site — a dense GHG observation network run for four years (2012 - 2015) — and is continued since by the University of Bern. Measurements are taken at an altitude of 212m above ground. This relatively high observation height results in a larger tower footprint and therefore the tower observations are predestined for a source analysis on a much larger scale than typical for flux towers.

We will present preliminary results of a sensitivity study performed with the Lagrangian atmospheric transport model FLEXPART using different meteorological input data of various spatial resolution, different model internal time step settings, as well as two
different convection schemes used in the convective atmospheric boundary layer — a Gaussian Hanna-type turbulence model and a more realistic skewed turbulence scheme in which a larger area is occupied by downdrafts than by updrafts.

The range of simulated footprints will be used in combination with emission inventories of CO2 and CH4 to simulate observations at the tower. By comparing the simulated with the actual observations at the tower we aim to evaluate the quality of the simulated footprints for the respective input data and model setting.

How to cite: Plach, A., Leuenberger, M., and Stohl, A.: FLEXPART model sensitivity study for the footprint of a Swiss tall tower site, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7206, https://doi.org/10.5194/egusphere-egu22-7206, 2022.

14:02–14:09
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EGU22-1453
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ECS
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On-site presentation
Ioannis Katharopoulos, Dominique Rust, Martin Vollmer, Dominik Brunner, Stefan Reimann, Lukas Emmenegger, and Stephan Henne

Atmospheric inverse modelling is a ’top-down’ emission estimation method, which utilises numerical models to estimate emissions from observed and simulated concentrations of atmospheric compounds. Inverse emission modelling can be applied for the support of emission inventories and emission reporting, which are usually based on ’bottom-up’ methods. The latter employ activity data and emission factors for the relevant processes. Depending on the emitting process, both may be afflicted by large uncertainties, especially when spatially-resolved emissions are considered on sub-national scales. Inverse modelling offers an alternative tool to emission estimation, validation and optimization of emission inventories. It is widely used by the scientific community for different atmospheric compounds and from global to the facility scale.

Atmospheric inversions can be carried out by combining source sensitivities simulated by atmospheric transport models, observations, and an inversion framework. Here, we focus on emissions of synthetic greenhouse gases (GHG) in the Swiss domain. 'Bottom-up' estimates of these emissions are connected to large uncertainties in the leakage rates of these compounds from various applications (e.g., refrigeration, foam blowing). Globally, synthetic GHGs account for a considerable fraction of the total anthropogenic radiative forcing (~10%), and their future environmental impact depends on the replacement of compounds with long lifetimes by compounds with short lifetimes and minimal global warming potential (GWP). In Switzerland, synthetic GHGs contribute about 3.5% to national total GHG emissions according to bottom-up reporting.

Newly available synthetic gases observations, collected as part of the Swiss project IHALOME (Innovation in Halocarbon Measurements and Emission Validation), from the Swiss Plateau at the Beromünster and Sottens tall towers, allow us to localise and quantify the emissions in Switzerland and in the neighboring countries. We apply the Lagrangian Particle Dispersion Model (LPDM) FLEXPART, driven by meteorological fields of the Numerical Weather Prediction (NWP) model COSMO, at two different spatial resolutions (7 km x 7 km and 1 km x 1 km). During the last decade, FLEXPART-COSMO was successfully operated at 7 km x 7 km spatial resolution to estimate Swiss emissions of methane and nitrous oxide. Reliable simulations at 1 km x 1 km resolution were recently established and required an update of FLEXPART-COSMO's turbulence scheme.

Inversion results for the most important (by emissions) synthetic GHGs (HFCs and SF6) are presented. Special attention is given to comparisons between inversions for different transport model resolutions and the question if the high resolution simulations are able to enhance the capability of the inversion method to localise emissions. Additionally, the sensitivity of the inversions to different a priori emission fields is presented. Finally, the sensitivity of the inversion towards covariance parameters, either obtained from maximum likelihood optimisation or from expert judgment, is examined. Inversions with the high resolution model amplify the emission differences between the Swiss Plateau and the high altitude regions in the Alps by both increasing the emissions in the big cities and decreasing the emissions in the high altitude regions. At the same time, no significant difference in total national emissions is observed between high and low resolution model inversions.

How to cite: Katharopoulos, I., Rust, D., Vollmer, M., Brunner, D., Reimann, S., Emmenegger, L., and Henne, S.: Impact of transport model resolution on the estimate of Swiss synthetic greenhouse gases emissions by inverse modelling, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-1453, https://doi.org/10.5194/egusphere-egu22-1453, 2022.

14:09–14:16
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EGU22-2830
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ECS
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On-site presentation
Martin Vojta, Rona Thompson, Andreas Plach, and Andreas Stohl

Inverse modeling provides a powerful statistical tool to verify national greenhouse gas (GHG) emission inventories by making use of in-situ atmospheric observations. Regional inversions are often based on atmospheric transport simulations with Lagrangian Particle Dispersion Models (LPDMs), where a large number of virtual particles are released from observation sites and traced backward for a limited amount of time to establish a relationship between atmospheric concentrations and emission sources within the simulated period. In order to account for all emissions prior to this simulation period, which also contribute to the corresponding observations, a baseline needs to be defined. This baseline definition is a crucial task, bearing a lot of uncertainties. Most studies investigating halocarbons use statistical methods to calculate the baseline by selecting low concentration observations at individual stations. In this study we show that statistical baseline methods have large systematic problems, that accumulate with increasing backward simulation periods and lead to a non-negligible underestimation of emissions that systematically increases with the length of the backward simulation time. As an alternative, we present a global distribution based (GDB) approach, where baseline concentrations are determined directly from global concentration fields at the termination points of the backward trajectories. These global fields are simulated with the FLEXible PARTicle dispersion chemical transport model (FLEXPART CTM) using a nudging routine to push modeled concentrations towards observed concentrations. We illustrate that this method is fully consistent with the length of the backward simulation, has the ability to account for meteorological variability, and leads to inversion results, that agree well with global emissions calculated with a simple box model.

How to cite: Vojta, M., Thompson, R., Plach, A., and Stohl, A.: The importance of baseline methods for the consistent estimation of regional and global emissions from inverse modeling, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-2830, https://doi.org/10.5194/egusphere-egu22-2830, 2022.

14:16–14:23
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EGU22-8425
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ECS
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On-site presentation
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Lucie Bakels, Katharina Baier, Silvia Bucci, Marina Dütsch, Andreas Plach, Daria Tatsii, Martin Vojta, and Andreas Stohl

The Lagrangian atmospheric transport model, FLEXPART, is used to investigate a broad spectrum of topics within the atmospheric sciences, from the propagation of particles emitted during nuclear accidents to global moisture transport. Since its inception in 1998, FLEXPART has undergone many changes, with its last official release (version 10.4) published in 2019. At the same time, numerous versions have been developed across institutes to cater to various needs. To make it easier to modify FLEXPART, while not having to diverge from the main version and its updates, we introduce a more modular way of organising the source code. Running times are improved by consistent OpenMP parallelisation in all parts of the code, resulting in reasonable scaling behaviour. Alongside the restructuring of FLEXPART, other improvements have been made. For instance, the interpolation errors have been reduced by replacing the traditional FLEXPART-internal terrain-following coordinate system with the option of doing all calculations on the native ECMWF ETA coordinate systems. Accuracy improvements are being investigated by quantifying the conservation quantities of dynamical tracers.

How to cite: Bakels, L., Baier, K., Bucci, S., Dütsch, M., Plach, A., Tatsii, D., Vojta, M., and Stohl, A.: Revamping FLEXPART for the next generation of simulations, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-8425, https://doi.org/10.5194/egusphere-egu22-8425, 2022.

14:23–14:30
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EGU22-12682
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ECS
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On-site presentation
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Silvia Bucci, Marina Duetsch, and Andreas Stohl

We present here a semi-automatic system of source apportionment analysis for long-term observations sites (e.g. measurement stations) and measurements campaigns. We will use as an example the application to the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) campaign, which involved a one-year-long ship expedition into the Central Arctic (September 2019 - October 2020)

The system is based on the Lagrangian particle dispersion model FLEXPART (Stohl et al., 2005; Pisso et al., 2019). The simulations are driven with hourly ERA5 data at 0.5° horizontal resolution. The cluster of back-trajectories can be released at any time resolution along the period of interest (the higher the resolution, the higher the computational cost). For the one-year campaign, we have chosen a 3-hours resolution, which will therefore represent the resolution of our timeseries of source contribution. The system can also be adjusted for the number of particles released, length of simulations, and aerosol or gas species that need to be simulated, which will therefore be applied to each simulation release. For our example application we use 100000 particles and a maximum time of transport of 30 days, and CO, SO2, BC and a generic air tracer as chosen species.

The simulations can then be coupled with emissions fluxes, to give a description of the transport conditions of a specific species from its source to the point of measurements. We use in our case the ECLIPSE v4 database for anthropogenic emissions and the GFED one for the fires emissions. With a similar approach, any gridded information from model output or satellite data can also be coupled with the air tracer back-trajectories. In our example, the analysis has been coupled to daily-resolved satellite data of sea ice cover to provide an estimate of the sea ice influence and its seasonal variability vs. the influence from the open ocean and continental land surface. The results of the whole set of simulations, including the quick-looks and resulting time series can also be easily automatically organized in directories. In our application, the data and the plots have been collected and distributed on a dedicated website which allow for an easy browsing of the results for the MOSAiC campaign.

How to cite: Bucci, S., Duetsch, M., and Stohl, A.: A source attribution system based on Lagrangian simulations, emission inventories and satellite data: an example of application to the MOSAiC campaign, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-12682, https://doi.org/10.5194/egusphere-egu22-12682, 2022.

Atmospheric Microplastic
14:30–14:37
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EGU22-2146
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ECS
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Virtual presentation
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xiaohui wang

Atmospheric transport was considered as an important pathway through which MPs (microplastics) enter the ocean since the early 2019s, but the source, transport, and fate of atmospheric MP have not well known. Besides, the connection between terrigenous atmospheric MP emissions and impacts over the ocean is not well known. In this conference, we will present our research about the variations of atmospheric MP over the ocean based on the three transoceanic survey, include the west Pacific Ocean, south china sea and east Indian ocean. Results suggest that synthetic MP comprised 25.89 % of total atmospheric particles over the west Pacific Ocean, with most being cotton and cellulose (51.68%). We found that the atmospheric MP was sparsely distributed over ocean, with different characteristics. The mean abundance of atmospheric MP over the western Pacific Ocean during the sampling period were 0.841 ± 0.698 items/100 m3. The abundance of atmospheric MP over the Pearl River Estuary (4.2 ± 2.5 items/100 m3) was significantly higher than that over the East Indian Ocean (0.4 ± 0.6 items/100 m3). However, the abundance of atmospheric MP in the SCS (0.8 ± 1.3 items/100 m3) was not significantly different from the East Indian Ocean and Pearl River Estuary. Results indicated that the size of airborne MP fiber over ocean is probably not the limiting factor during the long-range transport. Research reveal that MP undergoes long-range transport, more than 1000 km away. Furthermore, backward trajectory model analysis preliminary showed the potential sources of atmospheric MP over ocean. Our study provides the better understanding on the impact of atmospheric transport on global plastic cycle.

How to cite: wang, X.: Atmospheric microplastics over ocean: abundance, distribution and transport, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-2146, https://doi.org/10.5194/egusphere-egu22-2146, 2022.

14:37–14:44
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EGU22-1506
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ECS
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On-site presentation
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Moritz Lehmann, Lisa Marie Oehlschlägel, Fabian Häusl, Andreas Held, and Stephan Gekle

Raindrops impacting water surfaces such as lakes or oceans produce myriads of tiny droplets which are ejected into the atmosphere at very high speeds. Here we combine computer simulations and experimental measurements to investigate whether these droplets can serve as transport vehicles for the transition of microplastic particles with diameters of a few tens of μm from ocean water to the atmosphere. Using the Volume-of-Fluid lattice Boltzmann method, extended by the immersed-boundary method, we performed more than 1600 raindrop impact simulations and provide a detailed statistical analysis on the ejected droplets. Using typical sizes and velocities of real-world raindrops – parameter ranges that are very challenging for 3D simulations – we simulate straight impacts with various raindrop diameters as well as oblique impacts. We find that a 4 mm diameter raindrop impact on average ejects more than 167 droplets. We show that these droplets indeed contain microplastic concentrations similar to the ocean water within a few millimeters below the surface. To further assess the plausibility of our simulation results, we conduct a series of laboratory experiments, where we find that microplastic particles are indeed contained in the spray. Based on our results and known data – assuming an average microplastic particle concentration of 2.9 particles per liter at the ocean surface – we estimate that, during rainfall, about 4800 microplastic particles transition into the atmosphere per square kilometer per hour for a typical rain rate of 10 mm/h and vertical updraft velocity of 0.5 m/s.

How to cite: Lehmann, M., Oehlschlägel, L. M., Häusl, F., Held, A., and Gekle, S.: Ejection of marine microplastics by raindrops: a computational and experimental study, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-1506, https://doi.org/10.5194/egusphere-egu22-1506, 2022.

Coffee break
Chairpersons: Sabine Eckhardt, Petra Seibert
15:10–15:17
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EGU22-8065
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ECS
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On-site presentation
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Max Beaurepaire, Rachid Dris, Bruno Tassin, and Johnny Gasperi

Although the topic of microplastic pollution has been a source of increasing scientific interest since 2004, some environments are less studied and less understood than other. In particular, microplastics in the atmospheric compartment have only been studied for a few years.

Here, the literature on microplastics in the atmospheric compartment is reviewed. Upon studying published articles up to December 2020, two main categories of sampling strategies were distinguished. Articles either indirectly studied the atmospheric compartment through collection of deposited particles, or directly sampled air using vacuum pumping methods. While general sampling strategies remained the same, analysing methods was more variable.

In the following study, total atmospheric fallout was monitored on two sampling sites in the Paris region. In total, three monitoring campaigns were conducted, each lasting 4 to 6 months. Total atmospheric fallout sampling was collected using passive samplers. Each sampler consisted in a 0.3 m² metal funnel held in place in a wooden crate, and connected to a glass bottle. Samples were collected over periods ranging from 3 to 10 days. After collection, samples underwent a treatment process consisting of a density-based separation followed by a Fenton treatment. Samples were then placed on an anodisc filter and characterized using an automated µFTIR mapping analysis with a Nicolet iN10 by Thermo Scientific. Microplastics could be identified down to a size of 25 µm, cutoff point determined by the µFTIR detectors.  Finally, results were analysed using the open access software for Systematic Identification of MicroPlastics in the Environment (siMPle) developed at the Aalborg university, Denmark and the Alfred Wagner Institute in Helgoland, Germany.

Preliminary results from the total atmospheric fallout monitoring campaigns showed orders of magnitudes of a few dozen particles deposited per square meter per day (p/m²/d). Results from samples collected in a peri-urban sampling site showed deposition rates of 14.3 to 47.1 p/m²/d, while results from a rural sampling site showed deposition rates of 4.3 to 18.9 p/m²/d. While a dozen different polymers were identified, the majority of particles were polypropylene, followed by polyethylene and polystyrene. As of yet, results between sites remain to be assessed. The results will also be compared with the frequency and intensity of rain events to assess the effect of precipitations on atmospheric deposition. In particular, several samples were collected during dry spells. The deposition rates on these samples may be compared to the deposition rate during single rain events or longer precipitation periods.   

 

How to cite: Beaurepaire, M., Dris, R., Tassin, B., and Gasperi, J.: Comparison of total atmospheric microplastic deposition on a peri-urban and an agricultural site in the Paris region, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-8065, https://doi.org/10.5194/egusphere-egu22-8065, 2022.

15:17–15:24
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EGU22-13404
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ECS
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On-site presentation
Daria Tatsii, Silvia Bucci, Gholamhossein Bagheri, Andreas Stohl, and Lucie Bakels

Investigation of the transport and distribution of atmospheric concentrations of microplastic (MP) particles is an important challenge, since MP may have a negative impact on human health and ecosystems. When considering particle shape, most of the atmospheric transport models assume only spherical particles, whereas MP particles cover a wide range of observed shapes. Non-spherical particles experience a larger drag in the atmosphere, which leads to a reduction of their settling velocity, hence longer atmospheric residence times. Here we study gravitational settling of one of the dominant microplastic shapes – fibers. To reduce the difference between model output and ground-based measurements, we have implemented a parameterization of the shape correction in the gravitational settling scheme of the Lagrangian transport model FLEXPART.

We have determined model sensitivity to the shape correction to explore its impact on particles transport for a range of scenarios.  This was done with a statistical comparison of 3D fields of mass concentration and deposition patterns of shape-corrected and non-corrected parameterization schemes. Using the model output, we quantified average horizontal transport distances and atmospheric residence times for spheres and fibers of different sizes and aspect ratios in different climatic regions and for different release heights of the MP particles.

How to cite: Tatsii, D., Bucci, S., Bagheri, G., Stohl, A., and Bakels, L.: Atmospheric transport of microplastic particles as a function of their size and shape, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-13404, https://doi.org/10.5194/egusphere-egu22-13404, 2022.

15:24–15:31
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EGU22-5155
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ECS
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On-site presentation
Mahrooz Rezaei, Sajjad Abbasi, Farnaz Ahmadi, and Andrew Turner

Airborne microplastic is a new area of research in the microplastic domain. Recently, microplastic presence was reported in areas remote from any urban, industrial, and agricultural sources. This reveals the role of the atmosphere in the transport and dispersion of microplastics. Dust storms can shift significant quantities of soil particles and associated microplastics, especially in arid and semi-arid regions. This study reports the presence, characteristics, and potential sources of microplastics in a severe dust storm in Shiraz, southern Iran, in May 2018. Using the method adopted by Bergmann et al. (2019), 22 dust samples were collected from parked cars directly after the event. Dust samples were analyzed for microplastic using the density extraction method and Raman Spectroscopy. The hybrid Lagrangian and Eulerian model of HYSPLIT (Hybrid Single-Particle Lagrangian Integrated Trajectory) was used for back trajectory analysis in order to determine the origin of air masses.

Results showed that MP concentrations ranged from 0.04 to 1.06 particles per g of dust. In total, 485 microplastics were detected in all dust samples. The main shape of microplastics was fibrous and polymer makeup was dominated by nylon, polypropylene, and polyethylene terephthalate. Scanning Electron Microscope (SEM) images revealed different degrees of weathering in microplastics. Results of modeling together with the geochemical evidence suggested that the Arabian Peninsula constitutes the principal distal and transboundary source. Results also estimated that about 2 * 1012 microplastics could be transported by such a dust event. According to the literature on MP concentrations in urban dust and remote arid soils, it was estimated that between 0.1 and 5% of MPs in the dust samples were originated from local sources, and the remainder arose from more distant sources. The outcome of this study is proving the atmospheric transport of microplastic far beyond its sources and a potential pathway for microplastics to the oceans and land through dust storm events.

How to cite: Rezaei, M., Abbasi, S., Ahmadi, F., and Turner, A.: Dust storms as a means of transport for microplastics in the atmosphere, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5155, https://doi.org/10.5194/egusphere-egu22-5155, 2022.

15:31–15:38
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EGU22-11611
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ECS
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Virtual presentation
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Christoph Georgi, Eike Esders, Christoph Thomas, and Andreas Held

Microplastics are ubiquitous in the environment and have also been observed in the atmosphere. Nevertheless, very little work has focused on atmospheric transport of microplastic particles. This gap must be filled to gain a comprehensive overview of microplastics in the environment.

This work focusses on short-distance transport of airborne microplastic particles investigated in a wind tunnel with a cross-section of 270 mm x 540 mm as an idealized and controllable environment. In a set of experiments, polystyrene (PS) microspheres with a diameter 0.5 µm are introduced into the wind tunnel in various heights under distinct flow conditions. Two different optical particle counters (GRIMM Mini-LAS 11-R, Alphasense OPC-N3) measure particle concentrations in three heights (27 -157mm), which results in a profile that gives an estimate of particle deposition and emission.

The experiments show that low wind speeds generate higher concentrations in the bottom layers, while high wind speeds lead to increasing concentrations upwards. Furthermore, the formation of a boundary layer causes opposite gradients above and within.

The insights gained on short-distance and vertical transport of microplastic particles will be the basis for further wind tunnel experiments with varying surface roughnesses.

Funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) – project number 391977956 – SFB1357 / B05.

How to cite: Georgi, C., Esders, E., Thomas, C., and Held, A.: Vertical concentration gradients and transport of airborne microplastics in wind tunnel experiments, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-11611, https://doi.org/10.5194/egusphere-egu22-11611, 2022.

15:38–15:45
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EGU22-9512
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ECS
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On-site presentation
Jürgen Gratzl, Teresa M. Seifried, Ayse Koyun, and Hinrich Grothe

Microplastic particles in the atmosphere, even in very remote locations (Allen 2021; Allen 2019, Materić 2020, 2021), have attracted considerable interest in recent years. The origin, chemical transformation, transport and abundance of airborne microplastics still remains largely unexplained. Detection techniques are scarce and often include visual classification with the naked eye or with an optical microscope (Lulu 2021).

In this study, fluorescence spectroscopy is used to characterize microplastic particles in the laboratory. Pure samples of polyethylene terephthalate (PET), polyethylene (PE) and polypropylene (PP), as well as everyday products (PET-drinking bottle, packaging) were shredded with a swing mill into particles < 100 μm. The samples were analyzed with a fluorescence spectrometer, revealing clear excitation-emission maxima, with slight differences among the samples. To test if fluorescence is a promising property for the online detection of airborne microplastics, we use a Bioaerosol Sensor, which enables single particle fluorescence measurements at two excitation wavelengths and in two emission windows. For this aim, the microplastic particles are dispersed in air and are characterized by the bioaerosol sensor.

 

Literature:

Allen, S., et al. "Evidence of free tropospheric and long-range transport of microplastic at Pic du Midi Observatory." Nature communications 12.1 (2021): 1-10.

Allen, Steve, et al. "Atmospheric transport and deposition of microplastics in a remote mountain catchment." Nature Geoscience 12.5 (2019): 339-344.

Materić, Dušan, et al. "Nanoplastics transport to the remote, high-altitude Alps." Environmental Pollution 288 (2021): 117697.

Materić, Dušan, et al. "Micro-and nanoplastics in Alpine Snow: a new method for chemical identification and (semi) quantification in the nanogram range." Environmental science & technology 54.4 (2020): 2353-2359.

Lv, Lulu, et al. "Challenge for the detection of microplastics in the environment." Water Environment Research 93.1 (2021): 5-15.

How to cite: Gratzl, J., Seifried, T. M., Koyun, A., and Grothe, H.: Characterization of microplastics using fluorescence spectroscopy and online single particle fluorescence measurements, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-9512, https://doi.org/10.5194/egusphere-egu22-9512, 2022.