AS2.6 | Air-sea Chemical Fluxes: Impacts on Biogeochemistry and Climate
Air-sea Chemical Fluxes: Impacts on Biogeochemistry and Climate
Convener: Maria Kanakidou | Co-conveners: Parvadha Suntharalingam, Akinori Ito, Robert Duce, Cécile Guieu
| Tue, 25 Apr, 08:30–10:15 (CEST)
Room 0.11/12
Posters on site
| Attendance Tue, 25 Apr, 14:00–15:45 (CEST)
Hall X5
Orals |
Tue, 08:30
Tue, 14:00
Ocean-atmosphere flux exchanges of biogeochemically active constituents have significant impacts on global biogeochemistry and climate. Increasing atmospheric deposition of anthropogenically-derived nutrients (e.g., nitrogen, phosphorus, iron) to the ocean influences marine productivity and has associated impacts on oceanic CO2 uptake, and emissions to the atmosphere of climate active species (e.g., nitrous-oxide (N2O), dimethyl-sulfide (DMS), marine organic compounds and halogenated species). Atmospheric inputs of toxic substances (e.g., lead, mercury, cadmium, copper, persistent organic pollutants) into the ocean are also of concern for their impact on ocean ecosystem health. In recent decades the intensive use of plastics has led to significant levels of persistent micro- and nano- plastics being transported into the marine atmosphere and to the ocean, with considerable uncertainty remaining on transport pathways and oceanic impacts. Other influential recent changes include emission reductions for air pollution abatement which have resulted in changes in cloud and aerosol chemical composition, affecting atmospheric acidity, associated chemical processing and impacts via atmospheric deposition on ocean biogeochemistry.

In turn, oceanic emissions of reactive species and greenhouse gases influence atmospheric chemistry and global climate, and induce potentially important chemistry-climate feedbacks. While advances have been made by laboratory, field, and modelling studies over the past decade, we still lack understanding of many of the physical and biogeochemical processes linking atmospheric deposition of chemicals, nutrient availability, marine biological productivity, trace-gas sources and sinks and the biogeochemical cycles governing air-sea fluxes of these climate active species, as well as on the atmosphere-ocean cycle of microplastics and its impact on the environment and climate.
This session will address the above issues on the atmospheric deposition of nutrients and toxic substances to the ocean, the impacts on ocean biogeochemistry, and also the ocean to atmosphere fluxes of climate active species and potential feedbacks to climate. We welcome new findings from measurement programmes (laboratory, in-situ and remote sensing) and atmospheric and oceanic numerical models.
This session is jointly sponsored by GESAMP Working Group 38 on ‘The Atmospheric Input of Chemicals to the Ocean’ and the Surface Ocean-Lower Atmosphere Study (SOLAS).

Orals: Tue, 25 Apr | Room 0.11/12

Chairpersons: Akinori Ito, Maria Kanakidou, Parvadha Suntharalingam
Atmospheric Deposition
On-site presentation
Alexander Archibald, Ben Cala, Scott Archer-Nicholls, N. Luke Abraham, Paul Griffiths, Lorrie Jacob, Matthew Shin, Laura Revell, and Matthew Woodhouse

Dimethyl sulfide (DMS) is an important trace gas emitted from the ocean. The oxidation of DMS is important for global climate through the role DMS plays in setting the sulfate aerosol background in the troposphere. However, the mechanisms of DMS oxidation are very complex and have proved elusive to accurately determine in spite of decades of research. As a result the representation of DMS oxidation in global chemistry-climate models is often greatly simplified. Recent field observations and laboratory studies have prompted renewed efforts in constraining the uncertainty in the oxidation mechanism of DMS as incorporated in global chemistry-climate models. Here we build on recent laboratory and observational evidence and develop a new DMS mechanism for inclusion in the UKCA chemistry-climate model. We compare our new mechanism to the existing UKCA mechanism and to a range of recently developed mechanisms reported in the literature through a series of global and box model experiments. Our box model experiments highlight that there is significant variance in simulated secondary oxidation products of DMS across mechanisms used in the literature, with divergence in the sensitivity of these products to temperature exhibited. Our global model studies show that our updated and improved DMS scheme performs better than the current scheme when compared against observations. However, sensitivity studies underscore the need for further laboratory and observational constraints.

How to cite: Archibald, A., Cala, B., Archer-Nicholls, S., Abraham, N. L., Griffiths, P., Jacob, L., Shin, M., Revell, L., and Woodhouse, M.: Development, intercomparison and evaluation of an improved mechanism for the oxidation of dimethyl sulfide, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7047,, 2023.

On-site presentation
Juan Miguel González-Sánchez, Christos Panagiotopoulos, Candice Antich, France Van Wambeke, and Benjamin Misson

Biomass burning is a major contributor to the emission of particle matter in the atmosphere (up to 90 % of primary organic aerosol) and thus has an impact on climate, human health, and ecosystems. Once emitted, biomass burning-derived organic aerosol can be transported to the oceans. However, the impact and fate of this particulate matter and its major components in the marine biological carbon pump and the trophic chain are largely unknown. Understanding these processes is of paramount importance to better asses the carbon cycle. This work presents the first attempt to investigate the bioavailability of two biomass-burning tracers (i.e., levoglucosan and galactosan) in seawater inoculated with marine microorganisms. To do so, a novel method was developed to extract the anhydrosugar from their salty matrix and monitor their evolution for 44 days under controlled conditions. Along with the anhydrosugar concentration, multiple parameters (dissolved organic carbon, inorganic nutrient concentrations, prokaryotic production, heterotrophic prokaryotes abundance, and prokaryotic diversity) were monitored to achieve a complete picture of their fate in seawater. Furthermore, two control experiments (glucose- and non-amended) were run in parallel for comparison purposes. The results show that both levoglucosan and galactosan can be biodegraded at slow rates as their concentrations dropped from 2.5 ± 0.6 and 2.4 ± 0.3 μM to 0.1 ± 0.1 and 1.5 ± 0.7 μM, respectively, over a period of 44 days. The decrease in the levoglucosan and galactosan concentrations was accompanied by an increase in both prokaryotic production (up to 40 and 5 times greater, respectively, when compared to the non-amended experiment) and heterotrophic prokaryotes abundance (for levoglucosan, up to one order of magnitude greater than the non-amended experiment). While glucose was assimilated by heterotrophic prokaryotes within 1.7 days, levoglucosan and galactosan biodegradation did not start until at least 8.7 days after the experiments were set. These delays suggest that the chemical structure of these anhydrosugars can only be tackled by specific enzymatic abilities regulated by slow-growing heterotrophic prokaryotes. Prokaryotic diversity analyses revealed the predominance of a few bacterial genera from the Roseobacter clade that were specifically selected by the addition of the anhydrosugars. These results raise questions about the enzymatic capabilities of this widespread marine bacterial clade and the processing of semi-labile compounds accumulating in surface ocean waters. This work shows that biomass-burning organic compounds have the potential to be biodegraded by prokaryotic bacteria and thus contribute to the trophic chain and the production of CO2

How to cite: González-Sánchez, J. M., Panagiotopoulos, C., Antich, C., Van Wambeke, F., and Misson, B.: What happens to biomass burning-emitted particles in the Ocean? A laboratory experimental approach based on their tracers, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6011,, 2023.

On-site presentation
Andrea Milinković, Abra Penezić, Ana Cvitešić Kušan, Saranda Bakija Alempijević, Valentina Gluščić, Silva Žužul, Ivana Jakovljević, Sanda Skejić, Danijela Šantić, Ranka Godec, Gordana Pehnec, Carola Lehners, Maren Striebel, Jutta Niggemann, Anja Engel, Jelena Godrijan, Blaženka Gašparović, Mariana Ribas Ribas, Oliver Wurl, and Sanja Frka

The Mediterranean basin continuously receives anthropogenic aerosols from industrial and domestic activities from the European region, as well as high rates of aeolian material in the form of mineral dust from northern Africa. Moreover, combustion dominates over natural dust, whereas vegetation fires frequently burn throughout the Mediterranean coastal zone, especially during hot and dry summers. Once in the atmosphere, aerosols become an important external source of nutrients but also of toxins to the marine ecosystem through atmospheric deposition (AD), affecting the quality and quantity of organic matter (OM) produced by phytoplankton in the photic zone, and altering the CO2 uptake. AD onto sea surface cannot be completely understood without considering the interfacial processes within the sea surface microlayer (SML). As the uppermost millimeter of the sea surface, the SML represents the natural interface of the major environmental importance. It could serve as the first indicator of increasing human impact and climate change due to fast response of its biological and physico-chemical properties. However, surprisingly little research assessed the impact of AD on surface plankton communities, distinguishing between the SML and the water column bellow.

This work is designed to assess the magnitude and temporal variability of atmospheric concentrations and deposition fluxes of nutrients and trace metals, and to gain insight into the AD impacts on the nature of enrichments of organic compounds within surface layers in a typical Mediterranean coastal environment. The field campaign was conducted during the period of retrieval of sea surface oligotrophic conditions (February-July 2019) at the Adriatic coastal area. On-line black carbon (BC) concentrations were measured while the aerosol particles (PM10), wet and total deposition samples as well as the SML and underlying water (ULW; 0.5 m depth) samples were collected simultaneously. The first comprehensive insight into concentration levels of macro nutrients (N, P) and trace metals (e.g. Cu, Pb, Cd, Ni, Zn, Co) in atmospheric samples, their transport history, source apportionment and deposition fluxes to the coastal Adriatic area will be presented. The temporal dynamics of SML biology as well as concentrations of inorganic and organic constituents enabled the assessment of their sources and the nature of the enrichments taking place within the SML. Due to their significance throughout the Mediterranean coastal area, open-fire episodes and Saharan dust inputs were especially considered. In order to better understand the impacts of ambient AD from diverse sources on the physiology and biomass of the natural plankton population and consequently on the chemistry of the surface layers (SML and ULW), we further conducted the first in situ bioassay incubation experiment of its kind at the Adriatic Sea. We experimentally examined the impact of locally collected anthropogenic aerosols, that had different levels of biologically important nutrients, trace metals and organic pollutants, in contrast to the material mimicking biomass burning events.

Acknowledgment: This work has been supported by the Croatian Science Foundation under the IP-2018-01-3105 project: Biochemical responses of oligotrophic Adriatic surface ecosystems to atmospheric deposition inputs.

How to cite: Milinković, A., Penezić, A., Cvitešić Kušan, A., Bakija Alempijević, S., Gluščić, V., Žužul, S., Jakovljević, I., Skejić, S., Šantić, D., Godec, R., Pehnec, G., Lehners, C., Striebel, M., Niggemann, J., Engel, A., Godrijan, J., Gašparović, B., Ribas Ribas, M., Wurl, O., and Frka, S.: Insights to the short-term atmospheric deposition impacts on the biology and chemistry of the sea surface microlayer in the Adriatic Sea coastal region, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14624,, 2023.

On-site presentation
Priyanka Banerjee

Atmospheric transport and deposition of dust aerosol is very efficient in supplying iron to large part of global oceans. In this study, an Earth system model with ocean biogeochemistry component is used to explore how dust deposition can impact vertical distribution of dissolved iron (DFe) and phosphate in the upper 1000 m of the global oceans by impacting phytoplankton growth.  Although large areas of the global oceans show positive chlorophyll response following dust deposition, some regions (those having high levels of background DFe from continental shelf sediments and high atmospheric DFe input) experience net scavenging losses of DFe following dust depositions. Such regions experience a reduction in chlorophyll concentrations along with reduction in particulate organic carbon (POC) production and fluxes following dust deposition. While positive chlorophyll response is associated with low levels of background DFe and low atmospheric DFe input compared to regions experiencing negative chlorophyll response, the magnitude of chlorophyll increase depends on the background nitrate-to-iron ratio. With increase in the magnitude of positive chlorophyll response to atmospheric DFe deposition, an increase in POC production and resulting fluxes are encountered. Such an increase in POC flux can play the dual role of increase in scavenging removal of DFe as well as increase in PFe remineralization. The net result is that variation in NREG (Net REGeneration, taken as difference between PFe remineralization and DFe scavenging) in the upper 1000 m of the ocean has significant positive correlation with variation in POC fluxes, indicating that sinking organic matter following positive chlorophyll response to atmospheric iron deposition is the main driver of net DFe regeneration. Furthermore, a depth-wise difference between the impact of sinking POC and PFe fluxes on NREG is also evident. In the upper 150 m, high POC fluxes drive NREG while at deeper depths, PFe fluxes become important in driving NREG due to slow desorption release of iron from sinking PFe mass. As a result, with increase in POC fluxes, the depth of maximum NREG becomes shallower due to the shorter remineralization length scale of POC compared to lithogenic particles. On the contrary, with increases in the magnitude of atmospheric DFe , the depth of maximum NREG increases due to high dust deposition driving increased scavenging. Furthermore, increase in POC fluxes also leads to regeneration of phosphate at shallower depths. In this manner, the magnitude of chlorophyll response to atmospheric iron can significantly control the patterns of nutrient limitations.

How to cite: Banerjee, P.: Variable role of dust deposition on upper ocean nutrient distribution, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8622,, 2023.

Oceanic emissions
On-site presentation
Manuela van Pinxteren, Tiera-Brandy Robinson, Sebastian Zeppenfeld, Oliver Wurl, Heike Wex, Anja Engel, and Hartmut Herrmann

Transparent exopolymer particles (TEP) exhibit the properties of gels and are ubiquitously found in the world oceans. Here we demonstrate that TEP may enter the atmosphere as part of sea spray aerosol and likely influence cloud properties. We show number concentrations of TEP with a diameter > 4.5 µm, hence covering a part of the supermicron particle range measured in ambient aerosol and cloud water samples from the tropical Atlantic Ocean. Furthermore, TEP were analysed in generated aerosol particles using a plunging waterfall tank that was filled with the ambient seawater.

Based on Na+ concentrations in seawater and the atmosphere, the enrichment of TEP in the tank generated aerosol particles was well in-line with another study. The TEP enrichments in the ambient atmosphere were, however, up to two orders of magnitude higher compared to the tank study and such high values are thus far not reported for supermicron aerosol particles. We propose that the high enrichment of TEP in the particles and in cloud water result from a combination of enrichment during bubble-bursting transfer from the ocean and secondary in-situ atmospheric formation. We suggest that similar (biotic and abiotic) formation mechanism reported for TEP formation in the (sea)water might take place in the atmosphere as well, as the required conditions (e.g. high concentrations of dissolved TEP precursors such as polysaccharides, presence of bacteria in the cloud water) were given.

TEP concentrations in the atmosphere were two orders of magnitude higher than INP concentrations in the aerosol particles and cloud water, respectively. However, only a part of the TEP population, assumingly the one colonized by bacteria, might contribute to INP population, and are worth further studies.

The study contributes to the international SOLAS program.

Ref. : van Pinxteren, M., Robinson, T.-B., Zeppenfeld, S., Gong, X., Bahlmann, E., Fomba, K. W., Triesch, N., Stratmann, F., Wurl, O., Engel, A., Wex, H., and Herrmann, H.: High number concentrations of transparent exopolymer particles in ambient aerosol particles and cloud water – a case study at the tropical Atlantic Ocean, Atmos. Chem. Phys., 22, 5725–5742,, 2022.


How to cite: van Pinxteren, M., Robinson, T.-B., Zeppenfeld, S., Wurl, O., Wex, H., Engel, A., and Herrmann, H.: Transparent exopolymer particles (TEP) in the tropical oligotrophic Atlantic Ocean: Sea-to-air transfer and atmospheric in situ formation, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1134,, 2023.

On-site presentation
Guillaume Chamba, Maija Peltola, Theresa Barthelmeß, Matti Rissanen, Clémence Rose, Siddharth Iyer, Alexia Saint-Macary, Alfonso Saiz-Lopez, Manon Rocco, Karl Safi, Stacy Deppeler, Neil Barr, Mike Harvey, Anja Engel, Erin Dunne, Cliff Law, and Karine Sellegri

Understanding ocean-cloud interactions and their effect on climate requires that atmospheric new particle formation is characterized. Yet, the process of particle formation from marine biogenic gaz-phase emissions has not been evidenced in the open ocean lower atmosphere, partly due to the naturally low concentrations of these particles in remote oceanic places. Here we show, using new ship-borne air-sea interface enclosures, that new particles are formed in relation to marine micro-biology present in the seawater. The chemical analysis of newly formed clusters with API-ToF-MS shows unexpected results, implicating nucleating coumpounds and pathways that are usually not taken into account in nucleation processes.

How to cite: Chamba, G., Peltola, M., Barthelmeß, T., Rissanen, M., Rose, C., Iyer, S., Saint-Macary, A., Saiz-Lopez, A., Rocco, M., Safi, K., Deppeler, S., Barr, N., Harvey, M., Engel, A., Dunne, E., Law, C., and Sellegri, K.: Nighttime atmospheric nucleation driven by marine microorganisms, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8058,, 2023.

On-site presentation
Sneha Aggarwal, Olga Garmash, Delaney Kilgour, Chris Jernigan, Julika Zinke, Xianda Gong, Shengqian Zhou, Jiaoshi Zhang, Gabriel Freitas, Bruno Cunha, Tercio Silva, Jian Wang, Timothy Bertram, Joel Thornton, Matthew Salter, Paul Zieger, and Claudia Mohr

Sea spray aerosols (SSA) represent one of the largest sources of atmospheric particles since over two-thirds of the Earth’s surface is covered by oceans. They play an important role in climate and atmospheric chemistry, however, despite this a series of knowledge gaps hinder us from constraining their relevance. One critical question is why the physicochemical properties of nascent particles generated in the laboratory are so different from those measured in the ambient marine atmosphere. For example, a series of studies have highlighted that SSA generated in the laboratory exhibit essentially the same ability to act as cloud condensation nuclei as inorganic sea salt, regardless of the amounts of organic substances present in the seawater from which they were generated (e.g., Collins et al., 2016). This is in stark contrast to observations of ambient marine aerosols - their ability to act as cloud condensation nuclei is often significantly reduced in comparison (Swietlicki et al., 2000).

To address this discrepancy, we prepared a novel experimental setup in which we deployed a chemical ionisation mass spectrometer (CIMS) with an Aim inlet in a setup together with a sea spray simulation chamber, an oxidative flow reactor (OFR), and a differential mobility particle sizer (DMPS) at Graciosa Island, Azores, in the eastern north Atlantic Ocean during summer 2022 as a part of the AGENA campaign.

We used freshly-sampled ocean water to generate SSA that were aged in an OFR for an equivalent period of 3 to 3.5 days in the atmosphere. We recorded the gas-phase chemical composition of nascent and aged aerosols using the AIM-CIMS with multiple reagent ions, collected filter samples for offline analysis of the particle-phase chemical composition, and used a DMPS to compare the particle size distribution and concentration.

The first results of our study show that the volatile organic compounds released from the sampled ocean water considerably nucleate when they are oxidized in the OFR. Furthermore, the chemical analysis of these gases reveals an increase in the concentration of DMS oxidation products, such as methane sulfonic acid, when the nascent SSAs along with the gases in the tank headspace are exposed to oxidants in the OFR. However, we did not observe any substantial differences in the concentration and size distribution of the accumulation and larger-mode particles for primary and aged SSA. This could be attributed to extensive nucleation taking place in the OFR. It is possible that in the real world, these VOCs would rather condense on the primary SSA than form new particles.

In this presentation we will compare the properties of ambient SSA particles in the Eastern North Atlantic and those generated and aged with our experimental setup using real seawater in an attempt to address the discrepancy.

Collins, D. B., et al.Geophys. Res. Lett. 2016, 43 (18), 9975-9983.

Swietlicki, E., et al.Tellus B: Chemical and Physical Meteorology 2000, 52 (2), 201-227

How to cite: Aggarwal, S., Garmash, O., Kilgour, D., Jernigan, C., Zinke, J., Gong, X., Zhou, S., Zhang, J., Freitas, G., Cunha, B., Silva, T., Wang, J., Bertram, T., Thornton, J., Salter, M., Zieger, P., and Mohr, C.: Physicochemical Properties of Nascent vs. Aged Sea Spray Aerosols in the Eastern North Atlantic, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15506,, 2023.

On-site presentation
Steve Arnold, Natalie Brett, Siyuan Wang, Louisa Emmons, Wuhu Feng, Hannah Walker, Dwayne Heard, Daniel Stone, and Emily Kelly

Reactive volatile organic compounds (VOCs) in the remote marine atmosphere have impacts on climate through affecting atmospheric oxidation capacity (with subsequent effects on methane lifetime), and through affecting remote aerosol abundances, where they may modify cloud condensation nuclei (CCN) concentrations in regions of low CCN abundance. An improved understanding of aerosol and trace gas budgets in the remote marine atmosphere may aid in reducing uncertainties in the extent of anthropogenic warming and cooling contributions to radiative forcing of climate, since they are key components of the background natural atmospheric composition upon which anthropogenic influences are added. Glyoxal (CHOCHO) is a highly reactive oxygenated VOC, which observations have shown is ubiquitous throughout the global troposphere. In the remote marine atmosphere, glyoxal has the potential to act as a source of secondary organic aerosol and to modify the atmospheric oxidising capacity through impacts on radical photochemistry. In our recent work, we demonstrated the potential for acetaldehyde as a source of glyoxal in the remote atmosphere, via a minor oxidation pathway which dominates in-situ glyoxal production in clean marine air masses.

Here we present the first evaluation of global model-simulated glyoxal abundances in the remote marine atmosphere using high temporal (hourly) in situ measurements, and a collection of glyoxal observations synthesised from the literature. Measurements made using a sensitive laser-induced phosphorescence instrument at the Cape Verde Atmospheric Observatory in the tropical Atlantic  over two 4-week campaigns are compared with CAM-chem, a component of the Community Earth System Model (CESM) v2.2 including the MOZART-TS1 tropospheric chemistry mechanism. We show that the global model is capable of reproducing the magnitude of the in situ glyoxal observations from the tropical Atlantic marine boundary layer only when accounting for both the production of glyoxal from acetaldehyde oxidation, and the two-way sea-air exchange of acetaldehyde over the oceans. These model processes also improve the model-simulated glyoxal compared with remote sensing measurements in the tropical Pacific, but with a larger remaining bias. The model is not capable of reproducing observed nighttime glyoxal abundances at Cape Verde, with a large model underestimate. We show that the inclusion of a sea-air emission source of glyoxal, as a proxy for a potential source from the sea surface microlayer, allows the model to reproduce the observed magnitude of nighttime glyoxal. Our results demonstrate that an unconstrained global model is capable of reproducing observed daytime glyoxal abundances in the remote tropical Atlantic atmosphere, and further imply a coupling between acetaldehyde and glyoxal in the remote troposphere. The model results support the potential for a net sea surface to atmosphere source in sustaining nighttime glyoxal concentrations in this region.  


How to cite: Arnold, S., Brett, N., Wang, S., Emmons, L., Feng, W., Walker, H., Heard, D., Stone, D., and Kelly, E.: Evaluation of model-simulated glyoxal in the remote marine atmosphere and dependencies sea-air exchange processes, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15599,, 2023.

Virtual presentation
Frances Hopkins, Ruth Airs, Beth Williams, Qianyao Ma, Xiaoyu Zhu, and Jonathan Todd

The influence of dimethyl sulfide (DMS) on climate is potentially large but highly uncertain. Some of this uncertainty results from the over-simplification of biological drivers of marine DMS production within predictive models. The available models rely on chlorophyll (chl) as the sole biological parameter and often fail to replicate observations, particularly during highly productive events with elevated seawater DMS concentrations. The major precursor for DMS is dimethylsulfoniopropionate (DMSP), an abundant compatible solute produced by many marine eukaryotes and prokaryotes. Despite its importance, knowledge of how, why and by what DMSP is produced is limited. For example, haptophytes and dinoflagellates typically produce 50-100 times more DMSP per unit chl than diatoms and prochlorophytes - yet the relevant enzymes have until recently been poorly characterised, limiting our understanding. Furthermore, although the DMSP synthesis genes and their transcripts are widespread in surface ocean bacterial communities, the contribution by this group of organisms to total DMSP production is so far unquantified.

Here, we explore the diversity and expression of functional DMSP synthesis and lyase genes alongside DMS/P biogeochemical states and rates over a spring-summer time series (March – July 2021) at an established time series station in temperate shelf sea waters, to characterise the biological drivers of DMSP and DMS production.

DMSP concentrations ranged from <5 nmol L-1 to 160 nmol L-1, with peaks in mid April and late June. The April peak coincided with significant increases in the transcription of eukaryotic DMSP biosynthesis genes. As the season progressed, the eukaryotic transcripts fell dramatically, whilst an increase in transcription of prokaryotic (cyanobacterial) DMSP biosynthesis genes was observed. DMS concentrations in the spring/summer productive period were characterised by three sharp peaks in early May (27 nmol L‑1), early June (13 nmol L-1) and late June (20 nmol L-1),interspersed with lower concentrations of ~2 - 6nmol L-1. Each peak was associated with distinct prokaryotic community composition. Some relationships were observed between the DMS peaks and the transcription of eukaryotic DMS production genes and prokaryotic DMS degradation genes, demonstrating the fine balance of processes which determine net DMS production in the surface ocean.  Overall, we observed that both eukaryotic and prokaryotic autotrophs significantly contributed to seasonal variation in DMSP production in these temperate waters.

How to cite: Hopkins, F., Airs, R., Williams, B., Ma, Q., Zhu, X., and Todd, J.: Seasonal DMSP production dynamics in temperate waters driven by significant contributions from both eukaryotic and prokaryotic autotrophs, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15168,, 2023.

On-site presentation
Sinikka Lennartz, Heike Simon, Dennis Booge, Li Zhou, Thorsten Dittmar, and Christa Marandino

Carbon disulfide (CS2) is one of the most important precursors for atmospheric carbonyl sulphide (OCS), a climate relevant trace gas that can serve as a proxy to quantify terrestrial gross primary production. Currently, limited understanding of the production and consumption processes of CS2 in seawater preclude quantifying its marine emissions, which pose major uncertainties in the atmospheric budget of both OCS and CS2. Here we present controlled incubation experiments with natural dissolved organic matter (DOM) from three different oceanic locations, with and without UV light treatment. We show for the first time that in addition to its photochemical production, CS2 is also naturally degraded by UV light. CS2 is also produced in the dark: while the mechanism of this light independent production process is currently unknown, we show that dark production rates scale with the amount of organic sulphur present in DOM. Our results help to disentangle production and consumption processes of CS2 in seawater, in order to facilitate the interpretation of field measurements and ultimately enable modelling approaches.

How to cite: Lennartz, S., Simon, H., Booge, D., Zhou, L., Dittmar, T., and Marandino, C.: Carbon disulphide in the spotlight: UV-dependent production and consumption processes in seawater and their impact on oceanic emissions, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9269,, 2023.

Posters on site: Tue, 25 Apr, 14:00–15:45 | Hall X5

Chairpersons: Akinori Ito, Maria Kanakidou, Parvadha Suntharalingam
Jean-Daniel Paris, Martin Goxe, Mathis Lozano, Roberto Grilli, Livio Ruffine, Marc Delmotte, Sylvain Bermell, Stéphanie Dupré, and Vincent Riboulot

The global ocean is a net source of CH4 to the atmosphere. Large uncertainties remain on marine emissions that deserves effort to improve current estimates, and eventually predict their trajectories in a changing climate. Ocean CH4 emissions can either be CH4 emanating from seafloor sediments or in situ production in surface water linked to primary productivity. Sediment input into the water column can be either CH4 emanating from hydrate dissociation or free gas rising through the sediment. Ultimately, CH4 enters the atmosphere across the sea-air interface either from bubbles rising from the seafloor or by diffusion from dissolved gas. Estimates of global marine emissions diverge widely due to very large uncertainties linked to limited data coverage, methodological differences and the difficulty to capture the environmental factors that lead to high variability of the emissions.
As the world’s largest natural anoxic waterbody, the semi-enclosed Black Sea (BS) is characterized by widespread seafloor CH4 emissions from the shallow coast to the deep basin. The evolution of the anoxic properties of the BS is strongly linked to the amount of CH4 discharged and the supply of organic matter from the connected large rivers. Therefore, it is crucial to estimate the BS CH4 budget and understand the transfer mechanism to the atmosphere to better understand the impact of climate change. 
During the GHASS2 (Gas Hydrates, fluid Activities and Sediment deformations in the black Sea) cruise in September 2021, CH4 transfer to the atmosphere has been investigated at water depths ranging from 60 m to 1200m in the Western sector of the BS. CH4 partial pressures were measured in the surface water and in the atmosphere using optical spectrometers, respectively the SubOcean membrane inlet laser spectrometer (Grilli et al., 2021, and an ICOS-calibrated commercial analyzer (Picarro model G2401). We report eddy covariance measurements using  an open-path CH4 analyzer Li-7700 and a H2O-CO2 analyzer 7200RS from LiCor, a Gill 3D sonic anemometer, and an inertial navigation sensor (Lord). 
We compare flux estimates obtained from partial pressure gradient by the diffusive method under various schemes with the experimental eddy covariance set-up, applying available corrections for ship movement and interference with airflow. We also compare our results with previous reports for the area and conclude on the respective challenges and relative basin-scale representativity of the various measurement techniques.

How to cite: Paris, J.-D., Goxe, M., Lozano, M., Grilli, R., Ruffine, L., Delmotte, M., Bermell, S., Dupré, S., and Riboulot, V.: Marine methane fluxes to the atmosphere in the Western Black Sea: comparing eddy covariance and diffusive fluxes, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16526,, 2023.

Narin Choi, Joongeon An, Donghwi Kim, Andrew Loh, and Unhyuk Yim

While plastics are indispensable to our lives, they are known to emit harmful chemicals which can cause devastating effects to the environmental and human health. With the increasing concerns for global air pollution and climate change, the potential contributions of volatile organic compounds (VOCs) released from plastics have also been receiving increasing attention in recent years. Here, we developed and optimized a method for characterization of VOCs emitted from plastics. Using a selected-ion flow tube mass spectrometry (SIFT-MS), VOCs emissions were measured in real-time and data interpretations were performed using multivariate analysis. Expanded polystyrene (EPS), polypropylene (PP), high- and low-density polyethylene (HDPE and LDPE) and polyethylene terephthalate (PET) pellets were selected by their dominance as marine plastic debris. Emission characteristics of VOCs from selected polymers were monitored according to temperatures from 30℃ to 80℃. The emission of VOCs significantly increased with increasing temperatures for all plastic types, but varied in the order of LDPE, HDPE, PP, EPS, and PET. Partial least squares (PLS) analysis showed significant differences in compound group types, especially for compounds with relatively high molecular weight when heated at 80℃. The less-distinct differences in clustering of VOCs emitted at temperatures below 80℃, especially 60℃, were likely represented by additives and residuals during plastic production while VOCs emitted with temperatures above 80℃ were likely due to thermal degradation of polymers. The emitted compounds showed the highest mass concentrations with hydrocarbons such as alkane and alkene followed by monomers of each plastic type. These results suggested that the temperature threshold for VOCs emissions from residual materials and thermal degradations needs to be considered as one of the main factors for the analysis of VOCs from plastic debris.

How to cite: Choi, N., An, J., Kim, D., Loh, A., and Yim, U.: Optimization of analytical method for volatile organic compounds released from plastics and their emission characteristics by selected-ion flow tube mass spectrometry., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2508,, 2023.

Aldona Wiacek, Martin Hellmich, and Thomas Flesch

Open-Path Fourier Transform Infrared (OP-FTIR) spectroscopy is a well-established technique used to measure path-average trace gas concentrations [ppbv] in the atmospheric boundary layer.  Recently, the technique has been applied to derive trace gas fluxes from soils using the flux-gradient (FG) approach. We describe the novel application of OP-FTIR-FG to derive ocean-air fluxes of N2O [kg N2O ha-1 h-1] at a coastal site in the northwest Atlantic (2018, 2020-2021).  Details of OP-FTIR system deployment across Halifax Harbour (Nova Scotia, Canada) are presented and we describe the application of co-located 3-D sonic anemometer measurements to gas flux calculations.  Finally, we present a full error characterization of N2O flux and a case study of episodic negative (into ocean) flux.  This high frequency (30 min) and spatially averaging (560 m) method is well suited to coastal monitoring of ocean-air N2O fluxes and complementary to ocean-side measurements of N2O in complex circulation and microbial environments.  The possibility of other gas flux detection by this technique will be discussed.

How to cite: Wiacek, A., Hellmich, M., and Flesch, T.: Ocean-air trace gas (N2O) fluxes derived from open-path FTIR atmospheric concentration gradient measurements, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10739,, 2023.

Parv Suntharalingam, Zhaohui Chen, Jamie Shutler, and Andrew Watson

Oceanic uptake of atmospheric CO2 has been estimated to remove ~25% of  global anthropogenic emissions in recent decades (1990-2020), and this flux displays significant decadal variability (Global Carbon Budget: Friedlingstein et al. 2022). Key contributors to this ocean CO2 flux estimate are data products derived from interpolated surface ocean pCO2 measurements combined with air-sea gas-exchange parameterizations.  Although derived from a common surface ocean CO2 database (Surface Ocean CO2 Atlas (SOCAT), Bakker et al. 2016), these data products display variations on regional and global scales due to differences in their underlying construction methodologies. Here we assess three widely cited air-sea CO2 flux products, namely, Landschutzer et al. (2016), Roedenbeck et al. (2014) and Watson et al. (2020).  Our assessment uses the GEOSChem-LETKF data assimilation system (Chen et al. 2020), together with atmospheric CO2 observations from the NOAA-ESRL global network of surface sites (Obspack_CO2_Globalviewplus, 2020).  The individual air-sea flux products are implemented as alternative representations of the ocean prior flux, and we derive optimized estimates of surface CO2 fluxes in a set of atmospheric inverse analyses with the GEOSChem-LETKF system. We assess the performance of the individual ocean flux products on regional and global scales using a range of metrics derived from the atmospheric inversions including model concentration bias, CO2 flux error reduction, and comparison to independent atmospheric measurements from surface sites and aircraft. We also compare the derived posterior ocean fluxes to estimates from global ocean biogeochemistry models and discuss the implications for closure of the global carbon budget.

How to cite: Suntharalingam, P., Chen, Z., Shutler, J., and Watson, A.: Assessing Air-sea CO2 Flux Products with Constraints from Atmospheric Inverse Analyses, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10224,, 2023.

Akinori Ito and Takuma Miyakawa

Atmospheric iron (Fe) from anthropogenic, lithogenic, and pyrogenic sources contributes to ocean fertilization, climate change, and human health risk. However, significant uncertainties remain in the source apportionment, due to a lack of source-specific evaluation of Fe-laden aerosols. Here, the large uncertainties in the model estimates are investigated using different Fe emissions from metal production.  The anthropogenic and lithogenic factors are evaluated by using high-time-resolution measurements of Fe-laden species in fine particulate matter at Fukue observational site in downstream region of East Asian outflow. The better agreement in anthropogenic factor of aerosol Fe concentrations with the field data is obtained with the low estimate of smelting Fe emission. Our simulation with the low estimate of smelting Fe emission confirms that anthropogenic aerosols play dominant roles in bioaccessible Fe deposition to the northwestern Pacific, compared to lithogenic sources. Aerosol Fe co-emitted with sulfur dioxide from metal production predominantly contributes to atmospheric bioaccessible Fe input to the Southern Indian Ocean. Our simulation with different estimates of smelting Fe emission reveals that accurate representation of aerosol Fe from metal production is a key to reduce large uncertainties in bioaccessible Fe deposition to the Southern Ocean.

How to cite: Ito, A. and Miyakawa, T.: Contribution of metal production to bioaccessible Fe deposition into Southern Indian Ocean, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1513,, 2023.

Min-Woo Seok, Young Ho Ko, and Tae-Wook Kim

The frequency of wildfires has increased in the Siberian region. Wildfire plumes carrying black carbon and biologically important elements may have impacts on downwind ocean regions including Arctic seas such as the East Siberian Sea (ESS). However, the responses of marine environments to the wildfire plume introduced to the ESS are not well known. In this study, we tried to identify changes in ocean phytoplankton and sea-ice associated with wildfire activities by utilizing satellite-based and reanalysis data. The amount of carbon produced by wildfires in Boreal Asia coincides with the concentration of black carbon, indicating that wildfires are responsible for the majority of the black carbon in the atmosphere. In addition, we could detect wildfire plume-derived significant increases in ocean carbon uptake from satellite-based bio-optical variables (phytoplankton growth and biomass concentration). Summertime black carbon deposition has more than doubled over the last decade, and black carbon deposition was highly correlated with sea-ice melting rate, implying a contribution of black carbon deposition on sea-ice melting, which may increase ocean productivity by enhancing light availability in the upper ESS.   

How to cite: Seok, M.-W., Ko, Y. H., and Kim, T.-W.: Impacts of wildfire aerosol on carbon uptake and sea-ice in the East Siberian Sea, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4826,, 2023.

Heike Simon, Marc von Hobe, Thorsten Dittmar, and Sinikka Tina Lennartz

Sulfur containing trace gases impact Earth’s climate, and the ocean is a major natural source for the most abundant sulfur gas in the atmosphere, carbonyl sulfide (COS). Understanding and quantifying COS oceanic emissions is relevant for closing the gap in the atmospheric COS budget, which currently impedes conclusions about trends in stratospheric aerosol formation and gross primary production on a global level. The main production process of COS in surface seawater, photochemical production, remains one of the largest uncertainties in quantifying marine COS emissions. Precursors of COS are dissolved organic molecules, which form an enormously diverse mixture. How the composition of this diverse pool influences COS production has not yet been fully understood.

Here we present continuously measured COS concentrations in seawater and the marine boundary layer to quantify the relationship between photochemical production of COS in various marine regions: Along a North-South Atlantic transect from Bremerhaven to Cape Town and at two stations in the North Sea, one located in the open sea area close to Heligoland, one in the Wadden Sea area close to Spiekeroog Island. Samples of dissolved organic matter (DOM) were taken twice daily for subsequent analysis of the molecular composition and optical properties of the large precursor pool for COS photo- and dark production. Concentrations of COS in surface seawater showed distinct diurnal cycles with considerable day-to-day variations. The marine DOM pool differed with respect to sulfur containing molecules mainly between locations, and less along diurnal cycles. Our results will help to improve mechanistic models of marine COS cycling, especially with regard to the currently existing uncertainties in the global emission estimate of COS.

How to cite: Simon, H., von Hobe, M., Dittmar, T., and Lennartz, S. T.: Linking production of carbonyl sulphide to the composition of the marine dissolved organic matter pool, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9032,, 2023.