to introduce that always scares me my colleague Amanda Brosser who is are you associate professor yeah it's official now just tenured professor at the university of Georgia in the chemistry department Amanda got her bachelor's science and chemistry at University of California, Berkeley and her master's in PhD at Scripps, where she worked with Lynn Russell. She did a postdoc at Berkeley before moving on to a faculty position at the University of Georgia. She's an expert in aerosols and marine aerosols with a focus on surfactants, which we'll hear about today. She is a collaborator on an NSF project, examining surfactants in the surface microlayer. She's on Felix's video. And today she'll talk to us about chemical and physical properties of surfactants of seawater and the sea surface microlayer and their influence on emissions of primary marine aerosol. And she told me she just worked up some data to present from our collaborative projects. So that's exciting. All right, take it away, Anna. All right. Thank you for that introduction. I'm excited to be talking to all of you today a little bit about the work that we do. And it's mainly focused, like Andrew said, on surfactants and understanding their sources and composition. And a lot of other work in my group is on aerosol particles. And so connecting the seawater to the aerosol is one of our main goals. And so the first part of this will all be about sea water and the surface macular. And the And then eventually I'll try to connect the surfactants in the seawater to the production of primary marine aerosol. And so, there we go. Like I said, the theme of our group is understanding the properties of surfactants in atmospheric aeros. And to do that, we have four different themes that tie it all together. And so we're looking at surfactants and their properties in the surface micro layer and in seawater. We're interested in understanding how they affect primary marine air cell, what their composition is once they're in the atmosphere. So you can, you can see my mouse if I do that. Okay. So we have a inlet here on the roof of the building. And so we can sample air straight into our laboratory. And then we also have instruments that we can characterize particle hygroscopic growth. So once those particles are in the atmosphere, how do they grow and affect cloud droplet formation? And so since this is more of a marine group, I'm talking to today. I'm just going to focus on these first two pieces. But I will introduce aerosols and do this all on the same page here. And so often I'm talking to chemistry audiences, and I'm just like, what is happening right now? So aerosol particles are in solid or liquid suspended in a gas. And we're interested in understanding, like I keep saying their sources. So are they coming from the ocean? Are they blowing dust? Are they anthropogenic? Are they natural? What their composition is? Are they sea salt? Are they sea salt coated in organic? Are they black carbon? All those things. and then we're interested in how many of them there are and what their sizes are. And once we can understand those things, we can look at the properties of those particles. So understand their hygroscopicity, their reflectivity, absorptivity, and lifetime in the atmosphere. And we can use those properties to inform how particles affect the world around us. And so aerosol can affect visibility. Chemical reactions can actually take place within the aerosol so we can have aqueous chemistry. They influence climate and they also influence human health. And so most of my work is focused on understanding the influence of aerosol on climate. And so particles can directly influence the climate and also indirectly. And so we're more interested. in this indirect effect where particles can act as cloud condensation nuclei. And so their ability to grow into a cloud droplet and to act as this cloud condensation nuclei is dependent both on the particle size, where larger particles grow more easily, as well as their hygroscopicity. So you could imagine species that are more soluble, like seafault, will more easily grow in the cloud droplet. And so models up until pretty recently have used both the particle size and the higher specificity or the composition to model the likelihood that a particle is a CCN. And so recent work has shown that surface tension, in addition to the surface tension from the particle size, will also play a role. And so we need to take into account these surface active organics that might not be changing the hygroscopicity so much, but they could be changing the surface section and affecting how the particles grow into cloud droplets. And so if we have more surfactants or depending on their composition, that could change their ability to be. And so I keep saying surfactant, but let's talk about that a little bit here. So surfactants are, well, to find them in a second, but we have a graph here where we have concentration on the x-axis and surface tension on the y-axis. And then we have levagucousin, glucose, and endemic acid, and these are organics that we think about when we think about aerosol particles, and these are organics, and they may be surface active, but they are not actually surfactants. And so the surface tension of pure water is around 72 milanutons per meter. And you can see that even at high concentrations, these organics are not really having a big effect on surface tension. But then actual surfactants do. And so they can greatly reduce surface tension. You can see down here. And these are just two examples. So surfactants have a polar head group and a non-polar tail. and we can classify them based on the charge on their polar head groups. So these are some examples of some anionic surfactants, catayonics refractives, and non-ionics refractions. And so like I was saying, I often present the chemistry groups. I really love to see a molecule. All right. And so what we can do with these curves is calculate something called a critical my cell concentration. And then we can use that concentration. Like, you might think of it as the concentration, you know, at which my cells form. But we also think about it in terms of the surfactant strength. So how much surfactants do we need to actually reduce our surface tension? And so that's calculated here as the intersection of these two lines in this example. And so you can see that here the different surfactants will have different critical myself concentration. But in the atmosphere, and in the ocean, we don't have just pure surfactants in water. So what happens if we add different salts or different things? And so here you can see that if we add just salt to our anionic surfactant in blue and our cationic surfactant, that shifts the curve and acts to make these surfactants stronger. And we don't really have a large effect with our non-ionic surfactants. and I won't get into all the charge stuff right now, but it's there. Okay. And so one more piece of background information is just how these surfactants affect marine aerosol and everything. And so waves over the ocean or wind over the ocean causes breaking waves. Those breaking waves trap air below the sea surface. And then that air rises in the form of bubbles. And as those bubbles are rising, they're scavenging those surface. active organics and surfactants like I was talking about, they want to partition to that air water interface. And so they're brought up to the surface and the bubbles can linger at the surface. They can create rafts or they can burst right away. And all of that is based on the properties of the seawater. And so we're interested in studying that. But we're interested in what the are in the sea water and how they affect this bubble bursting process. And then eventually, or I won't talk about it so much today, but we measure the composition once they're in the aerosol as well. And then these particles can also undergo photochemical reactions in the atmosphere or they can interact with different gases emitted from the sea surface or with other particles and change their composition as well. And then this last part is, what I was talking about was the hydroscopic growth to the waste or practice influence cloud droplet microphysics. But today we're mainly down here in the ocean atmosphere in the earth. All right. So the first study that I wanted to talk about was one that was actually done in collaboration with the Wasniak group and this was a couple years ago. So our goal here was to determine the characteristics of organic species in the surface marker layer and the subsurface water of the Delaware Bay. And so this was kind of a pilot study and then jumping off point for the next project that I'll be talking about. And this work was done by my student or in collaboration with the Wasniak group, but Trette wrote this part up and he's graduated. So it's very exciting. Okay, so what we did here, and in case you don't remember, Andrew, there's a picture of him. as I present this to non -Andrew school football. But we had three different sampling sites in the Delaware Bay. So we sampled in the Broadkill River, mid -bay, and then the mouth of the bay, on two different days. And so depending on the tides, we had different salinity on those two different days and different properties of the seawater. And so we, Andrew's group, put together this surface microlayer sample for us. So this is the glass plate method where you take a glass plate attached to a tough one pole, dip it into the water, pull it back out. And the first thing the glass touches is the micro layer on the way down. And the last thing it touches on the way back out is the micro layer as well. And so here's a picture of, again, Trette on the right. and Rachel doing the surface microlayer sampling. And so they're scraping the microlayer into a bottle. And so usually when I give this presentation, I talk about how long it takes, but like Felix and Andrew are very aware of this. Like it took us like one or two hours to fill up a whole bottle with this so that we could do our analyses. Yeah. And it sounds tedious, but it's actually a lot of fun. All right. So then we had our sample. We took it back to the lab. And I won't be talking about this so much, but we did ion chromatography for major ions, tensiometry to do surface tension. Then so that was on a subset of the water. Then we filtered the water and did two parallel solid phase extractions to isolate some of the large organics. And so I think some of you might be familiar with the PPL extractions. This is a very similar thing just packed with different materials. So we had C-18 to target anionic and non-ionic surfactants and graphetized carbon to target our cationic surfactants. Then we eluded and dried it. We did UVViz spectroscopy, which I won't talk about in this part, and high-res, mass spec and tethiometry of these. And so the first thing just to note is that we measured the surface center. So if you think back to those curves that I showed before, this is just the surface tension of just the water before we did any extracts. And so this is the depression. So we calculated what the surface central in the water should be based on the salinity and if there were no organics. And then we measured the surface tension in the lab. and then subtracted them. And so what you can see is that there is a pretty significant surface tension depression at all three sites. And so that's indicating that there are these surfractants, these surface active organics that are reducing the surface tension compared to if it was just salt water. And then what gets interesting is that in the midbay and the Broadkill River, the microlayers in green and the subsurface is in blue. The sub-surface, the microlayer actually had a larger surface tension depression than the subsurface water, indicating that there could be more surfactants or stronger surfactants in the microlayer than the subsurface. And that's something that we would expect, and we found that interesting, but also good to see. And then at the mouth of the bay, those surface tension depressions were pretty similar. And so, yeah, you can take what you will from that. Okay. And then the second part with surface tension is that we looked at the minimum surface function. So that would be that first point on the curve where we got our organic extract, then we rehydrated it in 40 micrometers of water, then made this measurement here. And so because that's the minimum that we can get, that's how we refer to it. So here you can see that the surface microlayer in both the mouth of the bay and the Brodkill River had much lower surface tension minimums than in the subsurface water. And so again, this could be showing that we have either stronger surfactants or higher concentrations in the micro layer. And so Trette took this a step further and looked at the high resolution mass spectra of this and you either, people either love Van Crevlin's or they hate them. So just if you hate them, just bear with me on this slide. But we have the microlayer and the top three panels, the subsurface and the bottom three panels, and then the mouth of the bay, mid bay, and Broad Hill River on the two different days. And so I won't talk about this too much, but the main, like, take home points here is that we had a higher H to C. ratio in the surface micro layer compared to the subsurface water and higher odyssey in the subsurface. And so the higher h to see is consistent with more surfactants or these longer chains being present in the surface micro layer compared to the subsurface water. And then we also won't talk about this too much, but tried to look at these specific regions in the the encrovaling diagram to look at what fraction could be lipids, what could be hydrocarbon like. So all of that is in the paper, and this is just a sprinkling of that. And then Trette did some MS-MS to identify specific molecules that could be present. And so in the mouth of the bay, my screen is blocking a little bit of this. Okay. So in the mouth of the bay, and in the mouth of the bay, Broadhill River, he identified oleic acid, which is a molecule that is surfactant-like. You have that long chain and that polar head group. And then in the mid -bay, he also in the Broghill River, he identified sucrose, which is not surfactant-like, but it is a large, larger organic molecule, but it's more soluble and less surfactant. All right. So with all of that, this study really showed us, yes, we can see surfactants in the migralayer. They are enriched, and we can use these different methods to analyze them. And then that helped, like Andrew said, we're collaborating on a project. That pilot study helped us get this. And so our goals here were to determine the seasonal and regional variability of the organic species and the surface micro layer and the subsurface water. And so actually moving out of the Delaware Bay and going into the open ocean and getting more variability regionally in our samples there. And then this is like the best picture of me and Andrew that I could find. So we're always just, you know, hard at work. Yeah, and then this work was, I'm going to show some work that Daniel Emmer and Amber Bert have just put together. And so this part's all new and I don't have all the answers to go with it. But we're excited about it and I wanted to share it today. All right. So I don't know if you talk to Felix all the time, but maybe he could tell you a little bit about this study. And so what we did was go out on the RV Sharp on three different cruises. So August 22, November 22, and August 2024. And we looked, we sampled at multiple different sites. And so we started here at the Delaware coast. And this was very similar to that mouth of the bay site that we had originally. And then in both August, August cruises, we went to the ocean shelf. And so this was a more open ocean-like space, but we were still on the shelf there. And then in one of them, we did the Virginia coast as well. And then finally, in the August 24 cruise, we made it to the open ocean. And so our first question that we were trying to answer here is what influences seasonal variability have. And so we can just look here and see that, so our markers are, our cruise track is overlaid on the chlorophyll concentration maps. And so that's also done on a log scale. And so that difference between the dark blue and the light blue is actually still not a lot. So dark blue is very, very low and the light blue is lower. And then you don't actually get higher chlorophyll until you get closer to the coast anyways um so we were trying to look at the seasonal variability and so you can see just in both august cruises the chlorophyll concentration is pretty low compared to the november cruise where there was a higher um average chlorical concentration and so even though chlorophyll is not a direct um marker of like vital plankton or any given species, it could indicate more primary productivity right there during our November cruise. And so that was our seasonal variability. We were also interested in that spatial variability that I was mentioning. And so you can see, especially in that August, 24 cruise where we start at the Delaware coast and then move to the ocean shelf and then the open ocean, that there's a real decrease in the chlorophyll concentration. And once we were in the open ocean, we were able, we're in that blue water that's more prevalent across the world. So away from the coast, actually understanding what is the real open ocean. And at that point, that was actually below our detection limit, or at least the detection limit for the cruise. Yeah. And then the last piece that we were interested in understanding is the temporal variability. ability. And so here we have, we sampled at multiple points throughout the day to try to understand the influence of UV exposure and radiation on the surfactant concentrations and compositions. And then the Wasniak group had to have more goals with this as well. And so we sampled at night around 2 a.m. in the afternoon, around 1 p.m. and then in the evening right before sunset on all of these cruises. And so that was to get nighttime, which should have zero UV exposure because it's 2 a.m. and it's been dark for a while. And then afternoon where we've had some throughout the day and then evening would be the most right before sunset. And we also duplicated our samples at night so that we could have a second set that we could irradiate. So take that to the lab and just put our own UV exposure on that to isolate the effect of this irradiation away from any other biological or other effects. And so for this, we used a solar simulator. And this was from Bill Miller's lab at EGA. And this is a picture of the solar simulator on the ship. And so on one cruise, we had it on the ship. And on the first cruise, we did it at home or back in the lab, but we were like, oh, we could do this. This will be fine. And it worked out on the ship just fine. So we were trying to simulate 12 hours of daylight by using this method. All right. And like we did on the first project I was talking about, we used the glass plate method again to sample the surface microlayer. And so Felix and Andrew worked with. the crew of the ship to come up with this really cool sampling device where we had three glass plates attached around the outside of a CTB, it wrote that frame, and we could use the ship wench or the crew could to actually dip that into the water, bring it back out. So it was the same exact idea where you're dipping the glass in the first thing it's touching is the microlayer, the last thing it's touching the microlayer. And then again, everybody squeegeing the microlayer into the bottles. And so you can see Ellie and Dan here doing that squeaging after it's back on board. All right. And so similar to the previous study, we had microlayer or subsurface water. And then we consolidated that into one big sample, then took subset. out for ion chromatography and tensiometry, we did the same or very similar in parallel solid phase extractions after the given water sample was filtered. And then we actually did those extractions on board the ship, then brought the cartridges back with us and eluded them. And then in this study we did the UVBIS spectroscopy to get the total concentration of surfactants Tensiometry to get the surface tension, and then we here added liquid chromatography to that high -resolution aspect to get those components again, but then also to do the lip-in composition. Okay. And since we also had someone on board taking off some pictures for us, I'll just show some of these pictures. So here we have Felix doing the filtering, and then my students, Mara, Amber looks like maybe they're just bugging him or they're there for moral support. And then Ellie, we have on the left side doing that solid phase extraction on the ship. All right. And so these are some very preliminary results that I wanted to show. And so this is what Dan has been working on. And so these are the surfactant concentration on the Y axis. and then the time of day that was sampled on the x -axis for both the Delaware coast on the top and the ocean shelf on the bottom. And the microlayer is solid and the subsurface is dashed. And so there's a couple of different things that we can, that we're learning from this and that we're looking more into now. But one of our things that we're noting is that if you look at the black samples for night and compare those to. to the red afternoon and the gold evening, you can see that the night always has a higher concentration of surfactants than the afternoon and the evening. And then, which is cool. And so that's interesting and that's maybe showing us that, well, I'll get there in a second. The other thing we can do is compare the black, the night, to the purple, which is the irradiated sample. And so what's interesting here is that the trends are always the same. And so on the left side was, this is kind of in order. So we sampled at night, we did the irradiation, then we did an afternoon evening, and then we sampled at night again, did another irradiation. And so the interesting thing is that they didn't always act the same. And so for the first night, we had this decrease in surfractance, but then for the second night, we kind of had an increase in surfactants. Yeah. So Dan is looking more into that. But another thing that we can note here is that the surface microlayer concentration is always higher than the subsurface. And we calculate an enrichment factor, which I'll show next. Yeah. And so this, the difference between the night and the irradiated and the actual like daytime irradiated samples shows that the actual UV exposure and irradiation is not the only thing controlling the concentration of surfactants in these samples. And so we isolated that component, but it is more complicated than just that. Okay, so this is the enrichment factor that I just mentioned, and this was calculated by taking just the concentration of surfactants in a microlayer, dividing it by the concentration in the subsurface and so anything greater than one is an enrichment. And so we can see here that all of our samples, so this was putting them all together from the two stations for the one study, they're all greater than one. And so if you're like, the way Dan plotted it, if you're like squinting at this, you're like, oh hey, there's like this increase here. But really the afternoon, evening, and the night all have this median enrichment factor around the same level. And it's not until we're looking at the irradiated samples that the median is actually much higher. And so that could indicate that either somehow the irradiation of the night samples is producing surfactants in the microlayer and making that concentration higher or it's preferentially breaking down surfactants that were in our subsurface water samples and making that lower and so either way contributing to a higher enrichment. The next thing we looked at the surface tension curves so like we I showed at the very beginning we have surface tension on the y -axis concentration that he got from the vivis on the x-axis and then there's a lot going on here and it took me and down in a couple minutes this morning to like talk it all through but there's just like a couple of things if you just generally look at it and so we have just in general this large surface tension depression from the organics that we extracted both from the Delaware coast and the ocean shelf and from both the microlayer and the subsurface And so there isn't really, if you're looking at this, there isn't one, like, trend that immediately stands out to you from the micro layer in the subservice. You can't just say, like, immediately, like, all of those are far the left or all of these are far to the right. They're kind of all, like, mixed together, the one minus the irradiated ones. And so if we look at this, I mean, I could look at this graph and talk about this graph all day. But if we look down here in the ocean shelf, you can see that their radiated stables are shifted to the right compared to all of the others. And so that's just showing that higher concentration that they already have. But the fact that their minimum surface tensions are so much higher than all of the others shows that they were probably, the serpactans were either being broken down and like changing their like the total amount of surfactants or they were changing their composition to make them less efficient their fractions and so either way they're unable to reduce that surface tension by very much and then just in general the shapes of the curves are pretty similar so the Delaware coast you know has like a sea shape where the ocean shelf starts to have more of a shape where we could actually maybe calculate a critical micell concentration from this. Yeah. Cool. There was a lot going on there. Okay. So another thing we looked at was the lipid identifications. And so Amber was working on this part and this is what we use the LTSAMS for. And so this is showing the number of lipids that were identified on the Y Act. and the carbon, the like number of carbons in that fatty acid chain, or both fatty acid chains for each one, for the microlayering green, the subsurface in blue. And this is taking all of the August 22 samples and putting them together. And so what she observed was the most, the largest number of identifications in the subsurface microlayer was for lipids with a C -18 chain and in the subsurface a C-15 chain. And then what we, I'm looking at my note because we were just talking about that. Yeah, so in total, there are a lot of lipids identified in both of these in the market layer and in the subsurface water, and most of them have this chain length between maybe seven carbons and all the way up to maybe like 35, and then it starts to taper off again. And so she also calculated an enrichment factor for the lipids, very specifically. And so for lipids that were identified both in the micro layer and in the subsurface, the enrichment factor was greater than one, 1.4.6. And so that could indicate preferential enrichment into the microlayer. But when she put together all the lipids, regardless of if they were in the micro layer or the subsurface, the enrichment factor was actually 0.6. And so this could indicate that there were some losses in the micro layer or maybe some combinations in the micro layer to reduce the number of lipids that were identified in the microlayer compared to the sector. And this I find overwhelming, so I don't know if you do. But what she then did was look at all of the lipid put it into a rainbow. nice, but all the lipid identifications in the micro layer, which is the top bar and the subsurface water, which is the bottom bar. And so unless you love lipids, like Cambridge does, you might not understand everything that's going on here, but the take home is that they're not exactly the same, right? And so just like we were seeing before, there are different lipids in the marker layer compared to the subsurface. And she actually identified fewer lipid. It's in the microlayer 163 compared to 189 in the subsurface water. So, I mean, the take home here is just like there were a lot of types identified in both. And the fractions are not exactly the same. And they get drastically different, especially towards the end in these white, great, and black boxes. Yeah. So another one you could start all day. And then the last piece she was looking at was the enrichment factor of specific lipid groups in the microlayer. And so what is intros, or yeah, so we have those lipids on the x-axis, the different classes, enrichment factor on the y-axis, and then they're split out into glyphal lipids, fossil lipids, and then other. And the total intensity measured by the mass spec is in that rainbow bar, and then the number of identifications is the number on top. And so what I found interesting here is that the glycolipids are all enriched in the microlayer compared to the subsurface. So they're above that dash line, which is at one, where the phospholipids, some are enriched and some are not. and it just depends on their specific lipid, lipid class. And so things that she is thinking about and knows a lot more about than I do is that based on some of these enrichment factors and these different ratios that she is calculated, she's thinking that bacteria could be a source of lipids in the microlayer. and that when there's lower nutrients, if there's lower nutrients in the surface microlayer, that could lead to a decrease in the phospholipid production and that for some specific lipids, there might be more degradation in the micro layer compared to the sub -surface. And so we're looking into all of this a little bit more. Okay, cool. All right. I don't know how much time I have. So you can just stop me, and I will stop talking about. something. The last part of that I wanted to talk about was now bringing this back into the aerosol. So we talked about that Michael Ayr and that subsurface a lot. And Felix was actually on board for this study, for this picture that Andrew was. He missed out on this gigantic flood. But what we were looking for here was we were trying to measure the effect of seasonal differences on the seawater physiochemistry and how that affects the primary marine aerosol production. And so this is being put together by Trette, again, and my other student regional. And so in this study, we, again, we have the floorfill maps, and we went to the bat station outside of Bermuda in summer. and in winter to get these differences. And so both of them are, you know, blue water, open ocean, very low chlorophyll concentrations, even in the summer compared to the winter. Yeah, that's all you need to know here. There we go. Okay, and so what we did was bring a marine aerosol generator with us on the ship. So we have a mobile lab where we can, bring this whole 20 foot shipping container. As you guys are aware, chemistry people are like, what are you talking about? So we set it on the ship and it has this glass tank in it. And here is Rachel looking really happy because everything's working. Yeah. And so we have, this is a schematic of what it actually looks like. So we have water pumping in from the front of the ship here into our model ocean at the bottom. And then we have a glass tank on the top, which is our model atmosphere. And so we are using a Venturi to pump ultra -pure air and water into the bottom of our model ocean to create those bubbles. So they could rise to the surface first. And then we could collect them and do the characterization, both physical and chemical characterization on that. And then what's interesting about this one and different from some other. model ocean atmosphere systems is that we constantly have four liters of water pumping through the system and so it's overflowing and creating a new surface all the time and so nothing stagnant so like you know trying to be like the real ocean and so these are just different parameters that go with it like I said we were pumping the four liters of per minute of seawater through and then we generally ran our venturi with five liters per minute of air but I'll show you a test where we ramped up that airflow to see how that affected the particles. Okay and so we have first just looking at the seawater characteristics in the summer compared to the winter. we had higher, obviously, sea surface temperature in the summer compared to the winter. And so sea surface temperatures on the right side, the right hand, the right hand y-axis in blue. And then chlorophyll A concentration is on the left y-axis in green. And so you can see that just overall chlorophyll concentrations were really low, likely. the depth of the mixed layer was different in the winter compared to the summer, making that clerical concentration look a little higher in the winter than the summer, but overall very low. In the atmosphere, even though we had our own tank that was not being influenced by the atmosphere, we still wanted to look at relative humidity and wind speed. And so those factors could be influencing, mixing, and other things in the surface ocean that could then affect the seawater and then the bubbles that we were producing. And so in the summer, we had a little bit lower wind speed compared to in the winter. And the winter we just had, it was a lot more variable as well. So that's that maroon trace. Like the wind speed would get really high and then drop off and then get really high again. Okay. And so what we calculated here was the number production efficiency of the particles. And so if you are familiar with, we usually measure number size distributions of aerosol. So that's the number of particles at any given size of particle. And then we used the flux of the total. divided by the flux of the bubble air to kind of normalize all of this. And so what we first looked at was this number of production efficiency versus air detainment rates. And so that's like the amount of air contributing to the bubbles. And so what we saw was that low airflow rates and we didn't get to do one and two in the summer. But at three and four liters per minute, there's very similar. number production efficiency. But then once we get up into the higher flow rates, so where we have more bubbles and more turbulence and just a lot more going on in our system, there's a bigger separation between summer and winter. And so in general, both of them are increasing with an increase in that air flow rate. But in the summer, it's much higher in the winter than in winter. And then we have, we also did this calculation for the mass of the particles. as well, which is more dependent on the size of the particles. And so what you can see here is that the season didn't really have an effect on the mass production efficiency and that they were very similar. It did have a big effect on the number production. OK, so then we can add that to this graph to make it even more overwhelming. And so we have teal on the left side, which is the number production efficiency. and the gray on the right side, which is the mass production efficiency. And so you, and then I put the averages on there as well. And so you can see in the summer we had basically twice as high number production efficiency compared to the winter. So that 400 times 200, or compared to 200, where the mass production efficiency was very similar. And so this just shows us that there's something that's different in the summer compared to the winter that's contributing to more particles being produced under otherwise very similar conditions. Yeah. And so one thing we're looking into, and Rachel is still looking more at this, is trying to connect the surfactant composition and the surfactant concentration to that number. production efficiency and so here on the top we have aerosol in panel A and then sea water in B and both of these are surfactant concentrations but they have different units because the concentration in waters are different than the concentration that would be in an aerosol particle or in the air and so what she was looking at is summer versus winter and just putting together all of those averages. And so in the summer, we had lower concentration of surfactants in the particles compared to the winter. And then the opposite was true in the seawater. And so there's some sort of preferential partitioning happening going from the seawater to the aerosol that was different in the summer compared to the winter and causing that flip. And then we calculated the enrichment factors going from. the seawater to the aerosol and saw a much higher enrichment and refractance of the winter compared to the summer. All right, and then there's just, this is the second to last one. Okay, so we looked at the particle number size distributions and mass size distributions like I was talking about. So we have summer on the left, winter on the right, and then number production efficiency, in oh do I not have a legend yeah the in the solid line and then the mass production efficiency and the dashed line and then day is blue and night is gray and so we were trying to see if there was some sort of day night dependence like we were talking about before with the UV exposure and there's really not and so the biggest controller here is the season summer has a lot more particles produced than the winter and the time of day, that's not really matter. And the last part that we did was I mentioned that we had that water continuously overflowing in our system. And so we looked at what would happen if we turned that off and we made it just a tank instead. And so here we have the number in teal again and the mass in gray. And so this was normal operation. Then we turned that water flow off in gray and in the gray shading and then turned it back on. And so what we saw was an immediate jump in the number of particles being produced when that sea water flow was turned off and a gradual increase in the mass when that was turned off. And so that shows that there's some dynamics happening with the way the bubble rafts are forming in the lifetime of the bubbles when they're not constantly being regenerated. Okay, cool. I will stop there and give you the conclusions real fast. So we saw surfactant like molecules present in the microlayer in subsurface water and preferential enrichment of surfactants with specific properties in the microlayer. There was more, there was a higher H-DC in the microlayer compared to the subsurface water and lower minimum surface hydrogen. And then in the second study, which we're still working on these conclusions, we have, again, a surfactant enrichment, and the concentrations decreased throughout the day, but they're not only controlled by irradiation. There's something else contributing to that. And then we have, we saw preferential enrichment of glycolipids and other specific lipids in the microlayer. And then for the last piece, the physiochemical properties of the seawater, maybe including surfractants, influence the number of production of our sea spray aerosol. And if we take that a step further, having higher numbers of particles in the summer compared to the winter could influence the number of CCN that we have and go further to influence the number, or I don't know, the brightness of the clouds as well. Okay, and with that, I just want to think my group, which is on the left, and then everyone from both cruises that I talked about today, and especially Felix and Andrew for our Sophie crews there. So I will stop right there and take any questions. Any questions for Amanda? George, go ahead. Yeah, that last slide, when you turned off the club, would you put that back up? When you had no flow, it's like a classic banana plot. Yeah. It's a show for atmospheric particles. It's just kind of interesting that it shows up that way. And you're not looking at the water. But again, the flow is off. so yeah yeah it does it does look like those soa production in them yeah i know this is not easy but does anybody try to measure the temperature of the surface micro layer so it might be different from bulk i don't know yeah wage in this actually he has a paper that shows um like In 2003, it shows the changes in temperature, pH. But they took water, brought it into the lab and... So it wasn't out. Yeah, you tried to do it out of the ocean. Yeah, and I don't know how you do that. The satellite did actually, the direct satellite measures used to be temperature. That's actually the subpoenae temperature. It's very very 1 millimeter a year temperature. But, you know, eventually the product produced it correctly with some other consideration. But maybe the original satellite data attribute to be used for this problem. And the reason I asked is he saw this partitioning going on. And so the only thing that it was obvious to be, it was, you know, obviously there's a solidity effect between, but there's also a temperature effect. But I don't know how big. And we go in different directions, some of versus one or two. Because if you have evaporation, you're going to have cooling, right? Yeah, that could be really, really cool. You would probably have to do it, I don't know, optically or something. It would be hard to make sure your probe was right at the microlayer. Okay. Hello. I think your work is really cool. I never even thought about the sea surface marker layer. I have two questions. One of them is a little funner, and the other one is just like a thought. But first, I really like to set up you all have for sampling on the with the glass panes on the side. They're on the outside too, right? Yeah. Yeah. How many glass panes did you lose if any on these cruises? That sounds like that's like you're going to know. That was, we lost zero on the first cruise. And Andrew and Felix can tell you more. I think we lost three on the second two. Okay, that's impressive. That's too pretty impressive. And the second was, I love that you talk a lot about air sauce as well too. How much I guess is there any work out there saying like how much these aerosols are influenced by things coming from the terrestrial side as well. So like you're looking at this SML coastal areas and then all the shelf and then a little further out. But how much of that obviously can be affected by productivity, but then also from the wind sort of bringing things from a family. Yeah. So atmospheric aerosol particles are really influenced by terrestrial inputs. And so part of why we have at that tank system is so that we can isolate what is just the primary marine aerosol coming right from the ocean. But we've, and I've tried to do it and other people have tried to do it, it's really incredibly hard to isolate what is just primary marine aerosol from what is anthropogenic and continental influence just because the mixing and the atmosphere. happen so fast. And so you can go to the Arctic or the Antarctic and still be getting a lot, like somewhere you think is very clean and still be getting a lot of anthropogenic influence. Okay. And then from the opposite side of that, like, because I love that you all did it, I love that anybody samples over a series, right? So throughout the day saying how things change from day to night, especially this is vertical migration of things that could bring up nutrients from the bomb. So are you all looking at microbes, Slater? Well, again, in depth. Yeah, that's all feeling. Andrew, you are helping Felix do that. Cool. That's going to be so fun. I'm so glad for doing this. Yeah. So I have two questions that are kind of unrelated from each other. The first one is thinking about a super cool setup you have for pumping bubbles through measuring rates of production. Have you thought about using that instead of something through there, like nothing through there, kind of thinking about like methane, seeing whether or not that way? important. This is this globally important process. Putting that thing, yeah, I'm just curious about it. Like that. Yeah, I think you cut out a little bit, but I think what you were asking was, what if we pumped methane through and created bubbles of methane? Is that what you're saying? Yeah. Yeah, so we've, I mean, you think about all the things, like, what if we did this and what if we did that? Yeah. Yeah, and it would probably, it's something that we could definitely do. Like we have an air, like, isolated air input part. And we've also questioned, like, what would happen if we were using ambient air instead of this, like, ultra-pure air. Like, we are scrubbing everything out of this air. And so, like, is there something, like, obviously in the actual air-sea system, you're taking ambient air? and putting it under the surface and so are the different gases and particles that are present there affecting the bubbles as well. And so we haven't done that, but it would be really cool. And then the other side of it of like actually looking at the gases that are coming out with the bubbles as well and taking those and putting them into some sort of chamber to do some reactions to see what type of like secondary marine aerosol we could form. That would also be very cool. Please another question. Yeah, Simi. Amanda, this is, I'm a lipid nerd, so I just want to preface my question. I actually think I'm on screen too, so let me move a little. This question is going to be a little bit in the weeds, but I saw something in your data that I wanted to point out when you showed the lipid. Okay, so if you take, what I have done before, if you take like a few leaders, of sea water from just below the surface and you filter it and you extract the lipids and you look at the polar lipid distribution. You see something that looks a lot like what you showed. So it seems to me when I'm like looking at your at your lipid distribution and it looks like phytoplankton heavy biomass, which is really interesting to see. You have like the sGGG is the sulfur lipid and then the MDG and the PGGG those are like the lipids. And I think from the slide previous, you had the broken down, like the monoacal versions of the same one. So if you have lipid data from bats, what you could do, so it's super, super phosphate limited at the bat station, and you see this lipid substitution to deal with the phosphate limitation where you get more betae lipids. And you had just one of those, you had DBTS, but if you have that for, for backs, if you have more of the Beattyin lipids, that might tell you that you're getting, phytoplime, like that's what's driving and the micropair. And then you could just look at your, and the distribution of lipids in your two locations, then use that to figure out what resources. That would be really cool. Yeah, and I know very little about lipid, so we'll take all the lipid advice you have. Yeah, so hopefully Amber is on here, so she's writing this down. We do have some extra water from that, so we could look at that, and that would be really cool. Yeah, I think specifically looking for the nitrogen containing if there are more at bats, that would be good way. Yeah, that would be cool. Yeah, unfortunately, we don't have any microlayer samples from bats. Or we do, but they're questionable. It was really cool. Anyone else? All right, why don't we all thank Amanda again? Thank you.
Amanda Frossard - SMSP Spring Seminar Series 2025
From Taylor Link March 14, 2025
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"Chemical and Physical Properties of Surfactants in Seawater and the Sea Surface Microlayer, and their Influence on Emissions of Primary Marine Aerosol Particles"
Amanda Frossard
Amanda Frossard
Assistant Professor of Chemistry
University of Georgia
March 14, 2025 at 12:00 PM
Zoom Only
Hosted by Andrew Wozniak
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- School of Marine Science and Policy
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