The MILAN Campaign: Studying Diel Light Effects on the Air–Sea Interface

Stolle, Christian; Ribas-Ribas, Mariana; Badewien, Thomas H.; Barnes, Jonathan; Carpenter, Lucy J.; Chance, Rosie; Damgaard, Lars Riis; Durán-Quesada, Ana María; Engel, Anja; Frka, Sanja; Galgani, Luisa; Gašparović, Blaženka; Gerriets, Michaela; Mustaffa, Nur Ili Hamizah; Herrmann, Hartmut; Kallajoki, Liisa; Pereira, Ryan; Radach, Franziska; Revsbech, Niels Peter; Rickard, Philippa; Saint, Adam; Salter, Matthew; Striebel, Maren; Triesch, Nadja; Uher, G; Upstill‐Goddard, Robert C.; Pinxteren, Manuela van; Zäncker, Birthe; Zieger, Paul; Wurl, Oliver

doi:10.1175/bams-d-17-0329.1

Cited by 22 publications

(25 citation statements)

References 103 publications

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“…For the ULW samples, the concentration of ∑PL was between 36.4 and 93.5 µg L -1 , for the SML samples between 61.0 and 118.1 µg L -1 . The measured total lipid concentrations are within the concentration range of the previous measurement studies in different oceanic regions (Frka et al, 2011;Gašparović et al, 2014;Stolle et al, 2019). The lipid classes FFA and phospholipids (PE, PG, PC) dominated within the PL while other lipid classes like TG, HC, ST showed not only a much lower concentration but also much less pronounced variance.…”

Section: Lipids and Lipid Classes In The Particulate Fractionsupporting

confidence: 79%

Concerted measurements of lipids in seawater and on submicron aerosol particles at the Cape Verde Islands: biogenic sources, selective transfer and high enrichments

Triesch¹,

Pinxteren²,

Frka³

et al. 2020

Preprint

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Abstract. Measurements of lipids as representative species for different lipid classes in the marine environment have been performed to characterize their oceanic sources and their transfer from the ocean into the atmosphere to marine aerosol particles. To this end, a set of lipid classes (hydrocarbons (HC), fatty acid methyl esters (ME), free fatty acids (FFA), alcohols (ALC), 1,3-diacylglycerols (1,3 DG), 1,2-diacylglycerols (1,2 DG), monoacylglycerols (MG), wax esters (WE), triacylglycerols (TG), phospholipids (PP) including phosphatidylglycerols (PG), phosphatidylethanolamine (PE), phosphatidylcholines (PC), glycolipids (GL) including sulfoquinovosyldiacylglycerols (SQDG), monogalactosyl-diacylglycerols (MGDG), digalactosyldiacylglycerols (DGDG) and sterols (ST)) is investigated in both the dissolved and particulate fraction in seawater, differentiated between underlying water (ULW) and the sea surface microlayer (SML), and in ambient submicron aerosol particle samples (PM1) at the Cape Verde Atmospheric Observatory (CVAO) applying concerted measurements. The different lipids are found in all marine compartments but in different compositions. At this point, a certain variability is observed for the concentration of dissolved (∑DLULW: 39.8–128.5 μg L−1, ∑DLSML: 55.7–121.5 μg L−1) and particulate (∑PLULW: 36.4–93.5 μg L−1, ∑PLSML: 61.0–118.1 μg L−1) lipids in seawater of the tropical North Atlantic Ocean along the campaign. Only slight SML enrichments are observed for the lipids with an enrichment factor EFSML of 1.1–1.4 (DL) and 1.0–1.7 (PL). On PM1 aerosol particles, a total lipid concentration between 75.2–219.5 ng m−3 (averaged: 119.9 ng m−3) is measured with high atmospheric concentration of TG (averaged: 21.9 ng m−3) as a potential indicator for freshly emitted sea spray. Besides phytoplankton sources, bacteria influence the lipid concentrations in seawater and on the aerosol particles, so that the phytoplankton tracer (chlorophyll-a) cannot sufficiently explain the lipid abundance. The concentration and enrichment of lipids in the SML is not related to physicochemical properties describing the surface activity. For aerosol, however, the high enrichment of lipids (as a sum) corresponds well with the consideration of their high surface activity, thus the EFaer (enrichment factor on submicron aerosol particles compared to SML) ranges between 9 × 104–7 × 105. Regarding the single lipid groups on the aerosol particles, a weak relation between EFaer and lipophilicity (expressed by the KOW value) was identified, which was absent for the SML. However, overall simple physico-chemical descriptors are not sufficient to fully explain the transfer of lipids. As our findings show that additional processes such as formation and degradation influence the ocean-atmosphere transfer of both OM in general and of lipids in particular, they have to be considered in OM transfer models. Moreover, our data suggest that the extend of enrichment of lipid classes constituents on the aerosol particles might be related to the distribution of the lipid within the bubble-air-water-interface. Lipids, which are preferably arranged within the bubble interface, namely TG and ALC, are transferred to the aerosol particles to the highest extend. Finally, the connection between ice nucleation particles (INP) in seawater, which are active already at higher temperatures (−10 °C to −15 °C), and the lipid classes PE and FFA suggests that lipids formed in the ocean have the potential to contribute to (biogenic) INP activity when transferred to the atmosphere.

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Section: Lipids and Lipid Classes In The Particulate Fractionsupporting

confidence: 79%

Concerted measurements of lipids in seawater and on submicron aerosol particles at the Cape Verde Islands: biogenic sources, selective transfer and high enrichments

Triesch¹,

Pinxteren²,

Frka³

et al. 2020

Preprint

Self Cite

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“…For the ULW samples, the concentration of PL was between 36.4 and 93.5 µg L −1 , for the SML samples between 61.0 and 118.1 µg L −1 . The measured total lipid concentrations are within the concentration range of the previous measurement studies in different oceanic regions (Frka et al, 2011;Gašparović et al, 2014;Stolle et al, 2019). Within the PL, the lipid classes FFA (ULW: 5.4-14.0 µg L −1 ; SML: 16.1-36.5 µg L −1 ) and PP (ULW: 15.2-54.9 µg L −1 ; SML: 17.6-37.4 µg L −1 ) had high concentrations in seawater, while other lipid classes such as TG (< 5.8 µg L −1 ) and ST (< 2.4 µg L −1 ) had concentrations lowered by a factor of 4-23.…”

Section: Lipids and Lipid Classes In The Particulate Fractionsupporting

confidence: 73%

Concerted measurements of lipids in seawater and on submicrometer aerosol particles at the Cabo Verde islands: biogenic sources, selective transfer and high enrichments

et al. 2021

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Abstract. In the marine environment, measurements of lipids as representative species within different lipid classes have been performed to characterize their oceanic sources and their transfer from the ocean into the atmosphere to marine aerosol particles. The set of lipid classes includes hydrocarbons (HC); fatty acid methyl esters (ME); free fatty acids (FFA); alcohols (ALC); 1,3-diacylglycerols (1,3 DG); 1,2-diacylglycerols (1,2 DG); monoacylglycerols (MG); wax esters (WE); triacylglycerols (TG); and phospholipids (PP) including phosphatidylglycerols (PG), phosphatidylethanolamine (PE), phosphatidylcholines (PC), as well as glycolipids (GL) which cover sulfoquinovosyldiacylglycerols (SQDG), monogalactosyl-diacylglycerols (MGDG), digalactosyldiacylglycerols (DGDG) and sterols (ST). These introduced lipid classes have been analyzed in the dissolved and particulate fraction of seawater, differentiating between underlying water (ULW) and the sea surface microlayer (SML) on the one hand. On the other hand, they have been examined on ambient submicrometer aerosol particle samples (PM1) which were collected at the Cape Verde Atmospheric Observatory (CVAO) by applying concerted measurements. These different lipids are found in all marine compartments but in different compositions. Along the campaign, certain variabilities are observed for the concentration of dissolved (∑DLULW: 39.8–128.5 µg L−1, ∑DLSML: 55.7–121.5 µg L−1) and particulate (∑PLULW: 36.4–93.5 µg L−1, ∑PLSML: 61.0–118.1 µg L−1) lipids in the seawater of the tropical North Atlantic Ocean. Only slight SML enrichments are observed for the lipids with an enrichment factor EFSML of 1.1–1.4 (DL) and 1.0–1.7 (PL). On PM1 aerosol particles, a total lipid concentration between 75.2–219.5 ng m−3 (averaged: 119.9 ng m−3) is measured. As also bacteria – besides phytoplankton sources – influence the lipid concentrations in seawater and on the aerosol particles, the lipid abundance cannot be exclusively explained by the phytoplankton tracer (chlorophyll a). The concentration and enrichment of lipids in the SML are not related to physicochemical properties which describe the surface activity. On the aerosol particles, an EFaer (the enrichment factor on the submicrometer aerosol particles compared to the SML) between 9×104–7×105 is observed. Regarding the individual lipid groups on the aerosol particles, a statistically significant correlation (R2=0.45, p=0.028) was found between EFaer and lipophilicity (expressed by the KOW value), which was not present for the SML. But simple physicochemical descriptors are overall not sufficient to fully explain the transfer of lipids. As our findings show that additional processes such as formation and degradation influence the ocean–atmosphere transfer of both OM in general and of lipids in particular, they have to be considered in OM transfer models. Moreover, our data suggest that the extent of the enrichment of the lipid class constituents on the aerosol particles might be related to the distribution of the lipid within the bubble–air–water interface. The lipids TG and ALC which are preferably arranged within the bubble interface are transferred to the aerosol particles to the highest extent. Finally, the connection between ice nucleation particles (INPs) in seawater, which are already active at higher temperatures (−10 to −15 ∘C), and the lipid classes PE and FFA suggests that lipids formed in the ocean have the potential to contribute to (biogenic) INP activity when transferred into the atmosphere.

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“…The results reported here are in agreement with recent laboratory work by Yu et al (2021), who observed little uptake of NO 2 on bulk sea water under dark conditions (γ = 1.6 × 10 −8 ); however, this may not take into account any effect of the organic sea-surface microlayer (SML) on NO 2 heterogeneous conversion. Variability in the observed HONO / NO 2 behaviour overnight may reflect geographical differences in the organic composition of the SML, which will vary in response to changes in local near-term biological activity, underlying surface water composition, anthropogenic inputs, wind speed and solar radiation (see Sabbaghzadeh et al, 2017;Stolle et al, 2020;Wurl et al, 2011;Wurl and Obbard, 2004). The geographical/spatial variability in SML composition is not well known (Engel et al, 2017).…”

Section: Spatial Variability and The Role Of Other Hono Sourcesmentioning

confidence: 99%

Is the ocean surface a source of nitrous acid (HONO) in the marine boundary layer?

et al. 2021

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Abstract. Nitrous acid, HONO, is a key net photolytic precursor to OH radicals in the atmospheric boundary layer. As OH is the dominant atmospheric oxidant, driving the removal of many primary pollutants and the formation of secondary species, a quantitative understanding of HONO sources is important to predict atmospheric oxidising capacity. While a number of HONO formation mechanisms have been identified, recent work has ascribed significant importance to the dark, ocean-surface-mediated conversion of NO2 to HONO in the coastal marine boundary layer. In order to evaluate the role of this mechanism, here we analyse measurements of HONO and related species obtained at two contrasting coastal locations – Cabo Verde (Atlantic Ocean, denoted Cape Verde herein), representative of the clean remote tropical marine boundary layer, and Weybourne (United Kingdom), representative of semi-polluted northern European coastal waters. As expected, higher average concentrations of HONO (70 ppt) were observed in marine air for the more anthropogenically influenced Weybourne location compared to Cape Verde (HONO < 5 ppt). At both sites, the approximately constant HONO/NO2 ratio at night pointed to a low importance for the dark, ocean-surface-mediated conversion of NO2 into HONO, whereas the midday maximum in the HONO/NO2 ratios indicated significant contributions from photo-enhanced HONO formation mechanisms (or other sources). We obtained an upper limit to the rate coefficient of dark, ocean-surface HONO-to-NO2 conversion of CHONO = 0.0011 ppb h−1 from the Cape Verde observations; this is a factor of 5 lower than the slowest rate reported previously. These results point to significant geographical variation in the predominant HONO formation mechanisms in marine environments and indicate that caution is required when extrapolating the importance of such mechanisms from individual study locations to assess regional and/or global impacts on oxidising capacity. As a significant fraction of atmospheric processing occurs in the marine boundary layer, particularly in the tropics, better constraint of the possible ocean surface source of HONO is important for a quantitative understanding of chemical processing of primary trace gases in the global atmospheric boundary layer and associated impacts upon air pollution and climate.

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The MILAN Campaign: Studying Diel Light Effects on the Air–Sea Interface

Cited by 22 publications

References 103 publications

Concerted measurements of lipids in seawater and on submicron aerosol particles at the Cape Verde Islands: biogenic sources, selective transfer and high enrichments

Concerted measurements of lipids in seawater and on submicron aerosol particles at the Cape Verde Islands: biogenic sources, selective transfer and high enrichments

Concerted measurements of lipids in seawater and on submicrometer aerosol particles at the Cabo Verde islands: biogenic sources, selective transfer and high enrichments

Is the ocean surface a source of nitrous acid (HONO) in the marine boundary layer?

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