Airborne mineral dust triggers ice formation in clouds and alters cloud microphysical properties by acting as ice-nucleating particles (INPs), potentially influencing weather and climate at regional and global scales. Asian dust is an important source of atmospheric INPs. However, the ice nucleation activity (INA) of Asian dust, especially its sensitivity to particle size and anthropogenic pollution aging, remains poorly understood. In this study, we investigated the immersion mode ice nucleation properties and particle chemical characterizations of collected size-resolved Asian dust samples, covering eight particle size classes ranging from 0.18 to 10.0 μm. We also examined the chemical modification of aged dust particles via particle chemistry and morphology analyses. The measured total INP concentrations in the immersion mode ranged from 10^-2 to 10² L^-1 in dust events at temperatures between -25 and -5 ℃. An explicit size dependence of both INP concentration and surface ice active density was observed. The nucleation efficiency of dust particles increased with increasing particle size, while the INP concentration first increased rapidly and then levelled, due to the significant decrease in the number concentration of larger particles. The mass fraction of Ca²⁺ in element Ca and the mean relative mass proportions of supermicron Ca²⁺ increased by 67.0% and 3.5-11.2% in aged Asian dust particles, respectively, suggesting the occurrence of heterogeneous reactions. On the other hand, the total INP concentrations and total ice nucleation active site densities were consistent between aged and normal dust particles (0.62-1.18 times) without a statistically significant difference. And the INP concentrations and surface active site densities of chemically aged supermicron dust (1.0-10.0 μm) in each particle size class were nearly equal to or slightly higher than those of normal Asian dust, which were 0.70-2.45 times and 0.64-4.34 times at -18 ℃, respectively. These results reveal that anthropogenic pollution does not notably change the INP concentrations and does not impair the INA of Asian dust. Our work provides direct observational evidence and clarifies the non-suppression effect of anthropogenic pollution on the INA of East Asian dust, advancing the understanding of the ice nucleation of airborne aged mineral dust.

How to cite: Wu, Z., Chen, J., and Hu, M.: Ice Nucleation Activity of Atmospheric Asian Dust Particles, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9051, https://doi.org/10.5194/egusphere-egu24-9051, 2024.

Atmospheric aerosols are drivers of climate. Their impact is direct by scattering or absorbing solar radiation, and indirect, by serving as cloud condensation and ice nuclei. Once released into the atmosphere, aerosols can interact and/or react with gas-phase species thereby initiating a process known as chemical aging. This process tends to modify their surfaces. Mineral dust constitutes a significant part of the global atmospheric aerosol mass budget, contributing to almost half of the yearly particle emissions. Dust particles can traverse considerable distances, impacting remote areas from their sources. Despite the pivotal role of mineral dust in the atmosphere, considerable uncertainties persist regarding their influence on climate and air quality. This uncertainty primarily stems from a limited understanding of the fate of dust in the atmosphere and the underlying chemical processes they induce.

The aim of this work is to explore the heterogeneous interaction of methylglyoxal (MGL) with natural mineral dust. MGL results from the oxidation of isoprene in the atmosphere and is regarded as a crucial precursor to secondary organic aerosols (SOA). Therefore, its atmospheric fate of significant consequence to Earth's climate. Uptake experiments were conducted in a Knudsen flow reactor, operating in the molecular flow regime, and coupled with a modulated molecular beam quadrupole mass spectrometer for real-time monitoring of gas-phase reactants and products. The uptake coefficients of MGL is determined on 29 different mineralogical origin surfaces, to elucidate the impact of chemical composition on the uptake efficiency of the dusts.  

The initial uptake coefficients, γ₀,is determined to range from 0.05 to 0.67. These values are in the same order of magnitude than reactive gases in the atmosphere, indicating a high affinity between MGL and mineral dust. A correlation between γ₀ and Al/Si ratio of natural dust sample is evidenced and discussed. Furthermore, focusing on natural Gobi desert dust, the impact of MGL concentration (0.1 to 2,200 ppb) on γ_qss is determined. γ_qss increases as MGL concentration is decreased. Results revealed that the heterogeneous loss of MGL on dusts is a major atmospheric sink comparable to its gas-phase oxidation or photolysis. In addition, MGL uptake mechanism is studied on Gobi dust using in-situ DRIFT (Diffuse Reflectance Infrared Fourier transform) spectroscopy, providing useful information on interaction mechanisms. These findings offer novel insights into the atmospheric fate of MGL, providing a more comprehensive understanding of its heterogeneous atmospheric fate.

How to cite: Lostier, A., Thevenet, F., and Romanias, M. N.: Uptake of methylglyoxal on a diversity of natural mineral dusts and proxies: Heterogeneous kinetics and uptake mechanism, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8613, https://doi.org/10.5194/egusphere-egu24-8613, 2024.

In urban and remote atmospheres, new particle formation (NPF) events often occur after dust storms, which can have further impacts on regional and global climate. Additionally, the levels of gaseous precursors and condensation sink (CS) resulting from anthropogenic emissions can also influence the occurrence and intensity of NPF events. Over the past decade, China has implemented various air quality improvement actions, leading to significant changes in air pollutant emissions. However, there have been limited studies on the long-term evolution of NPF events caused by the synergy of dust storms and anthropogenic emissions.

This study aims to analyze the characteristics of dust-related NPF events in Beijing from 2009 to 2017 and compare them with non-dust NPF events. The results show that the formation rates of dust-related NPF events decreased due to the reduction of SO₂ emissions. However, the growth rates remained stable, possibly due to the increasing oxidation capacity in Beijing. These findings contribute to a deeper understanding of the climate effects of natural dust under the influence of anthropogenic emission control measures.

How to cite: Shang, D., Hu, M., Wu, Z., and Guo, S.: The Long-Term Evolution of Dust-Related New Particle Formation Events under Emission Reduction in Beijing, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19506, https://doi.org/10.5194/egusphere-egu24-19506, 2024.

Understanding the intricate relationship between dust-induced aerosols and ecosystem carbon uptake is essential to resolving the complexities of global carbon cycling. Aerosols play a crucial role in altering surface solar radiation, thereby influencing plant productivity. Despite their recognized role in modulating weather patterns, the precise mechanisms underlying aerosol-induced alterations in gross primary productivity (GPP) remain unclear. Previous studies suggest that aerosols may exert positive or negative impacts on ecosystem carbon uptake, subject to aerosol loading and cloud conditions. The present study uses Moderate Resolution Imaging Spectroradiometer (MODIS) AOD and GPP along with the European Centre for Medium-Range Weather Forecasts (ECMWF-ERA5) reanalysis datasets to investigate the effects of aerosol-induced radiation perturbation and eco-hydro-meteorological feedback on GPP in Himalayan ecosystems. We observe that the long-range transportation of dust-induced aerosol particles from the Middle East over Northern India is influencing air quality and weather patterns. It creates a thermal gradient that keeps surface temperatures lower than the top of the atmosphere. Consequently, the reduction in surface temperature and vapor pressure deficits contribute to variations in carbon uptake. We plan to examine multiple events where high aerosol loading contributes to extreme weather conditions like dust storms. Further, we will validate our results with flux tower measurements. Our findings show the significance of the interactions among aerosol pollution, climate change, and the global carbon cycle, which have unavoidable implications on weather patterns and direct impacts on human health and the tourism industry.

Keywords: Aerosol optical depth, Carbon Uptake, Dust, Himalayan ecosystems

How to cite: Budakoti, S., Khadke, L., Verma, A., Mukherjee, S., and Ghosh, S.: Uncovering the Influence of Dust-Induced Aerosol Particles on Ecosystem Carbon Uptake, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-979, https://doi.org/10.5194/egusphere-egu24-979, 2024.

Dust aerosols, originating from wind erosion, desertification, and anthropogenic activities, ubiquitous in arid and semi-arid regions, profoundly influence radiation, clouds, precipitation, atmospheric chemistry, and biogeochemistry. This study investigates the impact of dust aerosols on air quality in the western region of China, mainly focusing on Xinjiang. As the largest provincial-level region in China, Xinjiang presents a diverse landscape ranging from vast deserts to mountainous terrains. The intricate interplay of geographical features, including the Taklamakan Desert and the Tianshan Mountains, contributes to the intricate transport pathways of dust aerosols. By selecting Xinjiang as the study area, we aim to capture the different impacts of dust aerosols on southern and northern Xinjiang. Simultaneously, we are committed to enhancing the accuracy of coarse dust aerosol (2.5 μm < D < 10 μm) simulations in the model. This research investigates the disparities in the impact of dust aerosols between northern and southern Xinjiang. Preliminary analyses suggest that the north and southern regions exhibit variations in dust aerosol concentrations, transport patterns, and associated air quality consequences. Based on hourly data of six conventional air pollutants from an automatic station in the oasis city at the edge of the Tarim Basin in 2016, as well as the analysis of 1664 PM2.5 and PM10 receptor samples from 14 different locations in the oasis city during different seasons, particularly in the dust and sandstorm season (March to May), the daily average concentrations of PM2.5 and PM10 ranged from 71 to 253 μg/m3 and 325 to 799 μg/m3, significantly exceeding those in the non-dust and non-heating season (20-59 μg/m3 and 87-196 μg/m3). During the dust and sandstorm season, dust emissions, primarily from natural sources, contribute to more than 60% of PM, highlighting their predominant role as significant contributors to PM concentrations. Therefore, enhancing the accuracy of simulating dust loa using models is crucial for understanding the impact of dust on air quality. Recent studies comparing global model simulations against measurements showed that most models underestimate coarse dust load in the atmosphere, and this underestimation can be associated with poorly resolved or poorly understood processes that result in too-little emission or too-fast deposition of these particles in the models. Therefore, we employ WRF-Chem to investigate the sensitivity of coarse mode particulate matter to size distribution and settling velocities based on existing dust simulation schemes. By comparing the simulation results with observational data to identify the optimal size distribution and settling velocities for effective coarse-mode dust simulation. Understanding the dynamics of dust aerosols in this region is crucial for comprehending their broader impacts on air quality and environmental health. And the regional differences are pivotal for implementing targeted air quality management strategies tailored to the specific challenges faced by each subregion.

How to cite: Han, B., Wang, P., Xin, Z., Yu, H., Yang, W., and Bai, Z.: Impact of Dust Aerosols on Air Quality in Southern Xinjiang, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9444, https://doi.org/10.5194/egusphere-egu24-9444, 2024.

   Atmospheric water-soluble organic carbon (WSOC) is a critical component of airborne particulates, plays an important role in Earth’s energy balance, air quality, and human health. Until now, molecular composition and potential sources of WSOC in non-urban areas under different weather conditions are poorly understood in China. In this study, aerosol samples were collected at three sites in northern China representing remote (Erenhot), rural (Zhangbei), and urban (Jinan) environments during springtime. The WSOC components were analyzed by high-performance liquid chromatography coupled with high-resolution mass spectrometry. During normal days, the results showed that the numbers of assigned formulas of WSOC present the trend of urban > rural > remote sites. The CHO compounds were the most abundant formula category, followed by the CHON compounds at all three sites. The CHO compounds detected at the remote site Erenhot were dominated by oxidized unsaturated organic compounds and biomass-burning-related organic aerosol. The CHON compounds are majorly low-oxygenated-aliphatic species. All these results indicate primary anthropogenic emissions are significant sources at the remote site. However, higher contributions of highly oxygenated CHO and CHON compounds were observed at the site of Jinan, reflecting more insensitive secondary oxidation processes in the urban area. Reduced sulfur-containing species from the combustion of coal or diesel were abundant at Erenhot and Zhangbei, while the aliphatic organosulfates likely from traffic emission and nitrooxy-organosulfates from biogenetic sources were dominant at Jinan. Dust storms significantly changed the molecular composition of WSOC at Erenhot and Zhangbei. The dust-bounded WSOC was dominated by lignin-like species from plant debris, such as flavonoids. This type of organic species presents high volatility and viscosity and is likely an efficient ice-nucleating substance.

How to cite: Wen, H., Zhou, Y., and Wang, X.: Molecular characterization of atmospheric water-soluble organic carbon in contrasting remote, rural, and urban environments in northern China: Comparison of normal and dust days, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3048, https://doi.org/10.5194/egusphere-egu24-3048, 2024.

Organic aerosols (OA) are an important component of fine particulate matter (PM_2.5), constituting a substantial portion of its total mass. Seasonal ambient PM_2.5 samples were collected in Xi’an from April 2018 to March 2019. In order to achieve a molecular-level understanding of the OA fraction, the samples were analyzed using an iodide chemical ionization mass spectrometer combined with a Filter Inlet for Gases and AEROsols (FIGAERO-CIMS). The sum of compounds identified by FIGAERO-CIMS represented 29% organic matter in PM_2.5 on an annual average, including compounds containing CHO, CHON, CHOS, and CHONS. In the winter, the concentration of identified compounds notably surpasses levels observed in the other seasons. It was especially evident during a severe pollution episode in January 2019. The relative contribution of compounds containing only CHO, i.e., no sulfur or nitrogen, increases during summer which is likely due to enhanced photochemical oxidation. It was also indicated by a slightly elevated oxidation state being observed in summer compared to other seasons. The CHON compounds are most likely mainly consisting of nitro-aromatics, e.g., phenols-like compounds, where biomass burning and secondary formation are the dominant sources. Both biogenic and anthropogenic volatile organic compounds are contributing to sulfate-containing organic compounds in urban Xi’an.

How to cite: Li, L., Shang, Y., Sun, T., Kong, X., Wang, S., and Hallquist, M.: Molecular characterization of PM2.5 in Xi'an, Northwest China to reveal seasonal variation in sources of the organic fraction, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17863, https://doi.org/10.5194/egusphere-egu24-17863, 2024.

After input from rivers, the aeolian input of particles is probably the main source of nutrients in the ocean. Dust also plays an important role in the transport of organic material into the deep sea. However, little is known about the adsorption capacity of mineral dust for dissolved organic material (DOM). In this study, we investigate the effects of dust-seawater interaction on the carbon cycle. We collected dust samples in the form of silty crusts (grainsize < 63 µm) from the ephemeral rivers Kuiseb and Omaruru in Namibia, Southern Africa. To characterize the source material, we analysed for total organic carbon (TOC), specific organic compounds, ¹³C/¹²C isotope ratio, elemental composition and specific surface area. Sorption experiments were performed through time series and isotope analysis. We added different amounts of dust to a mixture of artificial seawater with DOM and ¹³C labelled DOM, both extracted from Spirulina algae and each in naturally occurring concentration. Experiments with a moderate amount of dust showed a decline in dissolved organic carbon (DOC) over time. This finding was also confirmed by analyses of ¹³C/¹²C isotope ratio on dust samples, before and after suspension in seawater DOM solution. Both results indicate that dust adsorbed a significant portion organic carbon from the Spirulina DOM solution. However, the net uptake of DOM on mineral particle surfaces depends on the ratio between DOM concentration and the amount of dust used. If dust already contains organic components, which was the case in our experiment, at least some of these organic compounds will dissolve in contact with seawater if the ratio between the amount of dust or primary organic material contained and the DOM concentration in the initial test solution exceeds a certain value. In this case, the input of dust represents a source of DOM in the near surface seawater. Our study reveals that terrestrial, mineral dust may act as both a sink and a source for DOM in surface waters of the ocean. Subsequent studies will have to clarify the extent of the impact of these effects on the carbon cycle. 

How to cite: van Kaam, R., Kölling, M., Hinrichs, K.-U., and Zabel, M.: On various effects of dust on the concentration of dissolved organic carbon in the sea, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19439, https://doi.org/10.5194/egusphere-egu24-19439, 2024.

Biogenic dimethylated sulfur compounds such as dimethylsulfide (DMS), methanethiol (MeSH), and dimethylsulfoniopropionate (DMSP) are ubiquitous in marine environments, playing pivotal roles in the global sulfur cycle and climate regulation. Atmospheric dust deposition exerts a significant impact on the Northwest Pacific ecosystem. However, its impact on these compounds in the upper ocean remains inadequately understood. This research examines the effects of atmospheric dust deposition, along with the subsequent influx of nutrients and Fe ions on the phytoplankton community and biogenic sulfur cycle in the Northwest Pacific, utilizing a ship-based incubation experiment. Our findings reveal that nutrient influx, stemming from both dust deposition and nutrient addition, has spurred phytoplankton growth, in which dust deposition also altered the structure of the algae community. These changes have consequently increased DMSP production per phytoplankton cell, leading to higher DMSP concentrations. The abundant nutrient has further amplified the DMSP cleavage pathway, a source of DMS, resulting in elevated DMS levels. Interestingly, the increase in DMSP has offset the reduced DMSP demethylation pathway, a source of MeSH, thus raising MeSH concentrations. While Fe ion addition did not directly boost phytoplankton biomass, it induced environmental oxidative stress, which in turn promoted cellular DMSP synthesis, enhancing both DMSP and subsequently DMS and MeSH production. Nevertheless, the swift oxidation of MeSH by active Fe ions led to a reduction in its concentration. This study elucidates the responses of phytoplankton and biogenic dimethylated sulfur compounds to atmospheric dust deposition, along with the subsequent influx of nutrients and Fe ions. These insights are crucial for accurately modeling the implications of such environmental changes on future climate dynamics.

How to cite: Xu, F., Zhang, H.-H., and Yang, G.-P.: Responses of production and concentrations of marine biogenic sulfur to atmospheric dust deposition in the Northwest Pacific, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4962, https://doi.org/10.5194/egusphere-egu24-4962, 2024.

Evaporite salts from saline lakes and playas play active roles in the atmospheric cycles and the climate system, especially in the context of changing climate. This study investigates the chemical, isotopic, and hygroscopic characteristics of surface salt samples from two saline lakes, i.e., Mang’ai and Dalangtan (MA and DLT), in the Qaidam Basin. Samples from both lakes shared similar ionic compositions, with brines rich in Cl^-, Mg²⁺, and Na⁺, and lakebed salts being primarily NaCl-based. Disparities in composition between MA and DLT crust salts were observed. Isotopic analyses revealed consistent δ³⁴S values within samples from a single site, hinting at a common origin. The sulfur source for MA saline lake likely arises from nearby freshwater inflows and atmospheric deposits. The δ³⁷Cl values varied by sample type, with solid samples typically exhibiting higher values than brines, attributed to ³⁷Cl depletion during precipitation. On the hygroscopic properties, the ionic composition is identified as a key determinant. While brines started moisture absorption around 40% RH, lakebed salts commenced at 70% RH. The DLT playa salt, enriched in Na₂SO₄, demonstrated unique behavior, responding significantly only above 80% RH. The layered DLT samples showcased variable hygroscopic behaviors, particularly the early moisture uptake of the topmost layer, despite its ionic similarity to another layer, hinting at molecular or hydration disparities. In conclusion, this investigation unravels the multifaceted relationship between salt evaporites composition and their implications for atmospheric chemistry.

How to cite: Kong, X., Hao, Y., Qiu, Y., Li, J., Liu, W., Chen, L., Zhang, X., Tang, M., Niu, Z., and Wang, S.: Hygroscopic Properties of Plateau Surface Salts: Insights from Chemical Composition and Isotope Signatures, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17901, https://doi.org/10.5194/egusphere-egu24-17901, 2024.

Marine aerosols can act as ice nucleating particles (INPs) and thus influence cloud microphysical properties, water cycle, and global climate. The low concentrations and high variability of INPs in the marine atmosphere lead to difficulties in their measurement and characterization and lack of observational data. In particular, there is a large gap on atmospheric INPs over tropical oceans, especially the Indian Ocean, which may cause large uncertainties in the simulation of atmospheric INPs, resulting in radiation flux errors and thus affecting the climate sensitivity in models. In order to characterize atmospheric INPs over tropical oceans, airborne total suspended particles (TSP) and rainwater samples were collected during a cruise from the South China Sea to the eastern Indian Ocean during April to June 2021. Using the ice nucleation detection device (TJU-INA) combined with multiple treatments, the levels of total INPs and INP compositions including organic, nanoscale (<0.22 mm), biological and bacterial INPs in TSP and rainwater samples were measured, and the sources and influencing factors of INPS were investigated.

Organic INPs dominated INPs (71.7%), and nanoscale INPs also accounted for a large fraction (57.6%) of INPs in marine aerosols during the cruise, with slightly higher proportions in marine areas closer to continents. The concentrations of total, nanoscale and organic INPs were higher in the South China Sea closer to the continent, straits, and the eastern Indian Ocean near Sri Lanka, while the concentrations were lower in the open areas of the eastern Indian Ocean. Carbonaceous components emitted from the continents strongly affected the levels of total and nanoscale INPs. Biological INPs were generally higher near the coast and lower in the open ocean. However, high wind speeds in the eastern Indian Ocean south of the equator likely produced more sea spray aerosols, resulting in higher concentrations of biological INPs than in other open ocean areas. Scavenging of airborne particles by wet deposition likely led to reduction in airborne INPs.

After conversion, the spatial distribution of the levels of INPs in rainwater were comparable to that of INPs in marine aerosols. Organic INPs were also dominant in rainwater, which were likely affected by marine biological activities. However, the proportion of nanoscale INPs in rainwater was only half that in aerosols, while INPs larger than 0.2 μm were more abundant in rainwater, maybe because rainfall removed larger particles more easily. Additionally, Cyanobacteria were probably important contributors to ice nucleation activity in rainwater.

How to cite: Hu, W., Duan, P., Niu, M., Jin, R., Wu, Z., and Fu, P.: Characteristics of ice nucleating particles in the marine atmosphere from the South China Sea to the eastern Indian Ocean, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5168, https://doi.org/10.5194/egusphere-egu24-5168, 2024.

Aerosols over the oceans significantly influence the composition of the Earth’s atmosphere and climate. Over the vast expanse of oceans, aerosols are emitted at high rates, primarily through wave breaking and bubble bursting. Additionally, secondary aerosol particles can be formed by gas-phase reactions. Particles emitted from shipping activities, long-range transport from continents, and potential downward transport from the upper troposphere can also contribute to aerosols in the marine boundary layer (MBL). Hence, marine aerosols represent a highly heterogeneous and complex mixture pivotal in regulating the global radiation budget.

This study explores aerosol number size distributions over the North Atlantic Ocean measured on the research vessel S/Y Eugen Seibold. The cruises conducted between June 2020 and September 2021 covered a broad geographic range from polar (~67° N) to tropical (~3° N) waters. Aerosols were sampled at approximately 13 m above the ocean surface using two sets of instrumentation covering particle sizes of 10 nm to 430 nm and 520 nm to 20 µm.

Three aerosol size modes, Aitken, accumulation, and coarse, were consistently identified throughout the dataset, aligning with prior research. Additionally, we observed an intermittently occurring nucleation mode and a bimodal coarse mode. While the presence of a nucleation mode suggests aerosol formation over the open ocean, it did not exhibit the typical banana-shaped contour plots usually observed during new particle formation and subsequent growth. Prior research indicates that ships may act as emitters in this size range, in addition to secondary formation from atmospheric gases.

Here, we describe and discuss particle number size distributions observed over the open ocean, raising questions about the formation and lifecycle of aerosol modes. Our goal is to track the behavior of nucleation, Aitken, accumulation and coarse modes in the MBL with high temporal resolution, spanning the latitudinal range of the northern Atlantic Ocean. A comprehensive dataset is prepared by incorporating surface ocean data retrieved on board and satellite observations to disentangle the natural and/or anthropogenic origins of aerosols responsible for the observed particle number size distributions in the MBL.

How to cite: S Raj, S., Hrabe de Angelis, I., Basic, S., M. Aardema, H., A. Slagter, H., Weber, J., Ll. Calleja, M., Krüger, M., O. Andreae, M., Dragoneas, A., Nillius, B., Walter, D., Berkemeier, T., H. Haug, G., Pöschl, U., Schiebel, R., and Pöhlker, C.: Exploring aerosol size distributions from polar to tropical zones of the Atlantic Ocean, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15400, https://doi.org/10.5194/egusphere-egu24-15400, 2024.

Aerosol-bound nitrogen (N) serves as a significant external source of N nutrients for marine ecosystems. However, the measurement of aerosol N in the marine atmosphere is challenging due to difficulties in field sample collection. Specifically, the assessment of organic nitrogen (ON) abundance in marine aerosols remains largely unexplored. In this study, marine aerosols were collected from various regions, including the China Seas (Region 1), the Northwest Pacific to Southern Arctic Ocean (Region 2), and the Southwest Pacific to Antarctic (Region 3). A newly developed method enabling the simultaneous detection of inorganic N (IN) and ON in filter-based aerosol samples has been employed to determine the total quantities of IN and ON. Additionally, the concentrations of organic and elemental carbon (OC/EC) and major ions were measured.

Over the China Seas, the average aerosol IN and ON levels exhibited the following rank: Bohai & Yellow Sea (3.87 and 0.61 μg N m^-3) > East China Sea (1.50 and 0.27 μg N m^-3) > South China Sea (0.52 and 0.18 μg N m^-3). However, the average ratio of ON to total N (ON/TN) was higher in the South China Sea (27.1%) compared to the Bohai & Yellow Sea (16.1%) and East China Sea (16.0%). Notably, aerosol IN and ON showed a strong correlation with EC over the China Seas, particularly in the Bohai & Yellow Sea and East China Sea, indicating significant contributions of anthropogenic emissions to the marine aerosol N pool. In comparison, much lower aerosol N levels were observed in Region 2 and 3, with average IN concentrations of 0.064 and 0.021 μg N m^-3, and average ON concentrations of 0.049 and 0.024 μg N m^-3, respectively. On average, ON accounted for approximately half of the aerosol N in clean marine atmospheres, as observed in Region 2 and 3. Furthermore, the positive correlation between aerosol IN and ON with non-sea salt potassium (nss-K⁺) was observed in Region 2, but not in Region 3, suggesting a more prominent contribution of biomass burning emissions to marine aerosol N in the northern hemisphere compared to the southern hemisphere. Interestingly, aerosol ON exhibited a stronger correlation with secondary species such as nitrate (NO₃^-) and non-sea salt sulfate (nss-SO₄^2-) than with sodium (Na⁺) in both Region 2 and 3, indicating that secondary formation might play a dominant role in contributing to marine aerosol ON, surpassing primary sea salt emissions. Future research efforts should focus on molecular characterizations to gain a better understanding of the sources and transformations of marine ON aerosols.

How to cite: Yu, X., Yu, J. Z., Zhou, Y., Shi, G., and Lai, S.: Abundance of Organic and Inorganic Nitrogen in Marine Aerosols over the China Seas and the Pacific Ocean from Cruises to the Arctic and the Antarctic, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7585, https://doi.org/10.5194/egusphere-egu24-7585, 2024.

Wet deposition of reactive nitrogen (N_r) induced by typhoons has significant eco-environmental impacts on the oceans, especially under the growing frequency of landfalling typhoons in East Asia. However, little is known about the mechanism of how anthropogenic activities influence the ocean ecosystem by interacting with landfalling typhoons. Based on the Nested Air Quality Prediction Modeling System, the N_r wet deposition induced by landfalling typhoon Hagupit 2020, and the ecological response, were explored. The N_r wet deposition over both the Yellow Sea and the Sea of Japan after landfall was found to have increased by up to 1000 times that of the pre-landfall ocean influenced by the typhoon. This high N_r wet deposition was mainly due to the “pumping effect” mechanism of the typhoon, which is strong uplifts of the typhoon rapidly carried surface air pollutants up to high altitudes from the land, following a large wet deposition through long-range transport towards downwind ocean, finally led to a high-concertation chlorophyll-a bloom. This study improves our understanding of N_r wet deposition induced by landfalling typhoons, and helps in the establishment of effective and active measures and to reveal marine ecology damaged by extremely strong convective weather systems

How to cite: Ge, B.: Enhanced nitrogen wet deposition induced by landfalling typhoon over East Asia: Mechanism and Implications, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2728, https://doi.org/10.5194/egusphere-egu24-2728, 2024.