 It's one o'clock on Tuesday, the 1st of March, and you are watching Science at Soast. I'm your host, Pete McGinnis-Mark, streaming live from beautiful downtown Honolulu. Every week we bring both graduate students and postdocs doing their research at the School of Ocean Earth Science and Technology at UH Minoa. And today we've got a really fascinating topic. I know virtually nothing about this, so it's going to be quite an entertaining show. Our guest today is Kelly Trax, who is a graduate student within the Earth Sciences Department of Soast. And so Kelly, welcome to the show. Delighted to have you on and apologies in advance if I don't quite understand what you're doing. So why don't we get started? And if you can just briefly describe, you know, where did you do your undergraduate degree or how long have you been a graduate student at Minoa? Something like that. Yeah, yeah. I actually have two undergraduate degrees. I had to decide what to do in life. I left one career, started another, and the first career really from Missouri State University really taught me to be really adaptable and to build a lot of skill sets. And my professional geology degree I got at Mississippi State University. I then came to UH Minoa in order to get my master's degree. And they successfully got me so interested in my research, I decided to stay and get a PhD as well. So I'm very fortunate. Oh, excellent. So you're into the research part of your degree program already? Yeah. So the columns have wrapped up and I've been doing research pretty continuously since I got here. So many exciting things to explore and that I get to share today. It's great. Well, our topic today is detection of contamination in vegetation. And as I said, I know virtually nothing about that. But I think your first slide is going to help the viewers get a grasp of what it is you're actually doing. But here we see four different types of veggies. Can you describe what we're seeing in these four panels here? Yeah. So this is a species that's native to Hawaii. Actually, it's just a Oahu itself. It's a moss. They're a really fantastic, robust, resilient, very simple plant species. And mosses are very commonly used for environmental monitoring. So we kind of got up in the top right section. You can see there's a healthy one. There's a stressed plant. There's one that has low contamination. We would consider this an anthropogenic or human source of metals that can come from industry, highways, dumping, that kind of thing. And then you can see the high contamination. What's really interesting about these photos and what makes the technique that I'm developing really interesting is if there's a high level of stress or a high level of contamination of metals or pollutants, then there's an obvious reaction that can be seen in the plant species. But if the contamination is fairly low, but still at a level that would not be safe for the plant or for biota or for humans, it's not necessarily easy to see right off the bat. Okay. So for context, I was trying to think before the show, you're not trying, for example, to look for sudden Oahu death, the stress that they might be going through. But would the work be of relevance, say, to the Environmental Protection Agency? You're looking at metal contamination and vegetation as opposed to water stress? We actually have moved into looking at environmental stressors. So we considered that drought over watering. So the stress plant that we have here actually has a really short photo period. So in Hawaii, we don't have to worry as much about long and short day periods seasonally, but other places in the world would. So understanding how that how different photo periods might affect the plant throughout the year is really important to us. Cold, heat, all of that really matters. And photo periods is the number of daylight hours? Yes. Yes. So in Hawaii, our like our shortest day is 11 hours. Our longest is about 15. But in other places in the world, it can be as short as six hours and as long as 20. So. Right. And in those images, you had a stressed mass and you had one with mild contamination. I hope you're going to be able to tell us that with your technique, you can actually discriminate between the two types of ill health for the plant. Yes, actually, we can. We can tell the difference in photo periods. Photo period does seem to have less of an impact overall, which is actually fantastic because it means the technique would still work regardless of time of year. But over watering or drought can have a huge impact. And excessive nutrients, which would be of interest agriculture would also really flare up and has a very different profile. What's also interesting is the type of contaminant can also affect the signal that we end up seeing. Okay. And so this might be related to any agricultural crops here in Hawaii. I spent some time in Michigan, for example, where there's a lot of pollution in the groundwater and so forth. Hopefully it would be relevant to a whole variety of applications as well as geographic areas. Yeah, we started with mosses because they only collect contamination from the atmosphere. But we've started looking at aquatic species specifically so that we could potentially manage runoff. But we've also looked at what a soil might do. So there are a lot of plants that can be used as bioremediation. So if you have a soil that you know that's contaminated, you could use these plants for bioremediation, use the technique to monitor them and then remove them before they die and return all those toxic metals back to the soil. And this is a big issue or a small issue in Hawaii. Obviously it's easier that the experiment with pretty uniform amount of sunshine each day throughout the year, it must make your experiments easier. But what's the condition of our plants? Are they suffering stress or why do it here? Yeah, well, one of the major things that we really wanted to look at, but it's kind of challenging, would be algae. So we get all these algal blooms, which can be incredibly strenuous on an ecosystem. So being able to monitor those and see what's a part of it. We also have a lot of our environmental teams that look at cesspools, and this technique would also help by using the vegetation as an indicator. So we could get an early indication of problematic areas and then sample very specifically based upon art detection, which would be really nice. Now I see the relevance of your work in Hawaii with all of the cesspools, not only on Oahu, but all the islands. You must have a lot of nutrients going into the soil. So okay, now the viewers, you'll have to bear with us. I think you're going to introduce some physics to this discussion. So let's take a look at the second slide and we'll go into this as carefully as we can. So what is this? So we're going to keep this tremendously simple. So the technique basically has three pieces. One's a light source, one's a sample, and some ways of measuring it, but that means that we really have to understand the fundamentals of light because it's really key to the whole experiment, the research, the process, and the technique. So here is kind of just like a light spectrum. So we're very, very familiar here, especially in Hawaii with rainbows, and rainbows kind of show the entire spectrum of visible light. What's great about the technique that I'm using is we're fully functioning, working in that visible light spectrum, but there's light acts as energy, and that energy can then be imparted into the sample. And this is really what's key. What's important for us is to understand the specific wavelength. So there are shorter wavelengths, which means they're like they have kind of a higher energy, and then we have slower wavelengths, which have a lower energy. And so understanding that we need to input a higher energy to a sample and then watching that output come out is really important. And the colors are actually what help us in our technique see what that energy loss is and also classify what we're looking at. And some of the viewers may have heard of the term the electromagnetic spectrum, and I think that's what you're showing. So the astronomers on my care would make their measurements or, you know, if you go to a dentist and have an x-ray. Yeah, x-ray, right, right, right. Like, yeah, your microwave, there's, they're all on the spectrum of things, but we're working in just kind of the visible. And we've had other guests have come on to look at, say, the colors of minerals, for example, in reflected light. A lot of the planetary community will look at the spectral characteristics. You're doing something different. Yeah, I think your third slide is going to sort of introduce us to how you do your studies. Yeah, so this right here is kind of the fundamental part. So whenever you have any kind of particle, an atom, a sample, it could be a human being, it could be your hand. So we have a particular wavelength of light in this case. It's blue, we're just going to keep it simple, it's blue light. And we can shoot that light at, say, your hand. In our case, we're shooting at a plant, the moss, and it goes in, it gets absorbed by the plant for photosynthetic processes. But it's really interesting is it energizes the plant. It's all this energy and there's a little energy transfer. And so the energy absorbed and the rest of it gets released. And so we can measure the light that is emitted from our source, from our light, and then we can also measure what gets emitted. And then you can see in the figure on the right hand side, you see that there's kind of a shift in the wavelength based upon color, but we also have a reduction in the amount of energy that we see. You're using lasers, right? This isn't just a regular light bulb, which covers a wide spectrum. Yes, yes, yes. Well, tell us a bit about lasers that you use. Yeah, yeah. To be fair, this is a very broad field. And there are people who use the sun, because the sun is our huge, ginormous, powerful light bulb of sorts. And it has all spectrums of colors. The difficulty is that if you use a specific wavelength, a very specific color, then you also can very specifically know what the output is. So we use a lot of different lasers. We have a green one, and we have a blue one, and we even have one that's UV. Some of these are super high powered, and some of them are as powerful as a laser pointer. It doesn't take a whole lot of energy to do the technique, which is really fantastic. We mostly work with blues because of the specific pigment that chlorophyll is in plants. That's really why plants are fantastic for this technique, is because they naturally fluoresce. All we have to do is give them an input. And this fluorescence is the energy coming off after you've shone the laser beam. Does this happen instantly or the following week, or what's the time period? So to be clear, we may have heard of photo luminescence. So there's phosphorescence and there's fluorescence. Fluorescence is often so short, our naked eye can't see it. But phosphorescence will be for like seconds. It can last for a very long time. We are interested in the long lifespan. We're interested in the short, which actually allows us, if we use a time gating, so if we say, hey, I only want my detector to measure in 0.1 seconds, then my detector actually is taking an image so quickly, it can't even see sunlight. But the fluorescence is such a short lifetime, especially for biologic material like chlorophyll, that we do capture that. I see. All right. And is this similar? And when we go to like the Bishop Museum and they shine a UV light on some minerals, for example, and they turn lovely colors, is that the same sort of thing if the viewers are trying to understand what you're... It is, yes. I mean, it will depend on the length of time. That's really how you define fluorescence. But yes, that's a major concern when choosing the color of your laser and what time frame that you're detecting the signal back at in order to, what we would say, distinguish between a biologic and an inorganic object. So a rock versus a plant, both might fluoresce. And so we have to be very careful with what we're using. And I think you're going to show us in the fourth slide that not all vegetation fluoresce at the same wavelength. If we go into the fourth slide. Yes. Again, explain this to us. Yes, it gets even more complicated than that. So many plants have both chlorophyll A and chlorophyll B, but there are also plants that don't have any chlorophyll B at all. It's just an evolutionary quirk that certain plants have and others don't. So there on the bottom, you can kind of see this spread of wavelengths. You can think of blue being on the left and red being on the right hand side and you're moving across the light spectrum. And what it's basically showing on the left hand side is the absorption bands. So if we were to emit a light, these are the maximum points at which chlorophyll A or chlorophyll B will absorb that light. And what we want to do is try and hit these maximum peaks. So the highest points of these are where we would want to shine a laser so that we can get the maximum output of fluorescence. So input as much energy as possible to get as much energy out so that we can measure it. And those peaks or those wavelengths are where you turn your lasers to again increase the signal to night. Yes. Yeah. And we can make the laser specific. So we've started working on a technique where one of our lasers focuses on chlorophyll A and the other one focuses on chlorophyll B. The reason for that is because each plant has a specific ratio, it could actually help us monitor if the plant is being stressed and if there are changes between those two. But it could also help us differentiate between vegetation. You said that we're trying to tune the lasers. You do this at Soast at your H-mino or do you just go and buy a different laser and put it in your equipment? Both. That is a both. That's impressive. So usually lasers have kind of a range. And so there is a little bit of tuning, as it were, to kind of get it within the range that you want. But it's far easier to, especially if you just need a low power laser. So a lot of times we'll just buy a really low power unit to test. And then if we need something with bigger energy, then that's something or more intensity, that's something we can do. Now tell us a bit more about the experiments. And I think in slide five you show us a little bit on how you actually do this. Yes. It's not clear if that's you in the pictures, but walk us through this one. Yes. So this is a great way of showing you what the sample naturally looks like versus what it looks like when it fluoresces. So we take a sample and we give it maybe a metal solution, maybe a nutrient solution. Sometimes we just give it water because metabolic processes in the mosses start immediately once they have water added to them. Once we've done that, we'll put it underneath the laser and use a computer in order to control the detector. And then so we can get the timing resolution the same. And so we'll fire the laser at it and then just capture an image. So the light source goes in, gives us the excitation. It interacts with the sample, which you can see in the picture in the top right. And we get that red fluorescence naturally back and capture that image. So it's not a point of laser light. You can actually get an image from a small area of the plan. We can actually back up pretty far. In our case, we don't want to start getting extra input from things that aren't the sample. So plastics can be very reactive, unfortunately, and they'll fluoresce really bright blue and it can be really problematic. So we kind of try and keep it in focus. But that sample right there is about four inches by six inches. Kind of like a postcard size. And your lasers, maybe how many feet or inches away from the target? That particular setup is about half a meter. But another team has had success up to five meters or about 15 feet. And what do the results look like? Is that in slide six? So we take pictures of all of this and then we process those pictures. So the top image is showing you a control or a perfectly healthy nothing has been done to it except water been added, moss sample. And the bottom picture is showing you what happens to the moss's level of fluorescence after a tremendous amount of copper has been added. What would be really detrimental to plants and humans alike. And so what we do is in this image, so every picture you take, even if you just are on vacation or you go out to the beach, every picture you take is made up of millions of teeny tiny pixels and each pixel has a little coding. So it has a red code and a blue code and a green code. And so we can go in and for every single pixel we can pick out all of those codes and then we can add them all together and count them and we can create a profile from that or in our case we call that a histogram. So we did that for both images. What you end up seeing is this really stark contrast between the control and between the contaminated specimen. So we have this huge shift in that bottom plot showing this darkening, this deep red coloration that starts to really take over. And can you correlate that sharpening or the trend towards the darker pixels? Does that correlate directly with the amount of contaminant or the duration, the stress or different types of stress? It does. So we ran an experiment over 10 days giving incremental doses at very different levels and we found that regardless of a single massive dose or a bunch of tiny doses that accumulated to the same level, there was a trend that we found in the response of the moss and we can see it just slowly shift over to the side as we're going. Okay. And all of this work is being done in the laboratory right now. Is it going to be relatively easy to take it out into the field? So the one unit that we use has a cart but it has to have pretty much you have to plug it into a pretty powerful source. The chlorophyll specific unit that I've been working with more recently for my PhD, we're actually already in the phases of trying to test it portable. Our biggest challenge has been just getting like a portable power bank that we can run off of so we can keep the laser going but we've successfully used a cell phone camera instead of something more expensive, just whatever junk you have lying around. But we know the camera still works too. We've got a really fancy tablet that we can try out as well. Our biggest question is light intensity so we can do maybe early morning, late evening, but at noon because of the limited power of our current baby laser as I would call it. We'd be limited on time. Okay. What do you envisage say a pharma up in Haliva being would she be able to use this sort of thing if she was growing different crops to try and figure out what the degree of contamination or what a stress were? Highly plausible. It would be really important to know what a good sample looks like versus a bad sample so that we have some kind of benchmark to work from to make sure that our measurements are accurate. It would also be important to compare different vegetation types. The other thing about making the unit portable is we want it to be a remote system that could be attached to a drone. So testing in the field is really important so that we can start using maybe that five meter elevation to pass over a sample and just constantly do sampling in real time. Well I presume that the power supply will be quite a challenge for a drone which itself has limited flight duration. Yes, it really comes down to the laser intensity so the less intensity that the or less energy that it requires the less battery that we would need. The camera is also a big question mark too but a lot of drones come with a camera that's already mounted so it's really just making sure the laser and the camera are properly aligned. Okay so where do you see this research going Kelly? I mean is it something that could be commercialized or is this primarily a research tool? I think commercial is highly plausible. I mean I'm a one person kind of unit but the main goal was that right now in order to do wide sampling is often very labor intensive or we've had national labs come to us and say that the infrared units that they have are destructive and they would really like to be able to go back to the exact same leaf and know that it hasn't been damaged by the technique so that they can really monitor the health of it without without having impact or being affected by time of day and and there are limitations to satellite imagery. It's good but there are limitations to being able to be specific on the ground so there's certainly room for it for the technique. I think it's important to just tell the viewers that the lasers you're using aren't like these death star lasers. Oh gosh no literally literally like a laser pointer. We have looked into UV because it's eye safe which would be really important if we were running it over over top of something just for public safety. So we've got about two minutes left. Can you tell us a little bit what else are you doing? This sounds to be a great topic for a graduate student. You've got in slide eight you've got I think three different projects going. There is certainly no shortage of things so on the left hand side we've been trying to most of our images have been moss masses. We're trying to get a little bit smaller that way if we were wanting to pinpoint sample we would know that an individual sample that we collected is contaminated and is good representation for chemical analysis. We are also comparing it to a more traditional check link which is spectrophotometry which is basically where you completely dissolve the sample so you can get a pure pigment measurement. We want to make sure that our chlorophyll A B measurements are really matching up there. On the right hand side we have two invasive species so nobody cares what we do to them Duckweed and Azolla and they basically float on the top of surfaces so the Azolla actually can be found because it's fantastic in nutrient cycling can be found in pteropons. Kelly I'm going to have to stop you there's too much to talk about so we'll have to invite you back some other time but let me just remind the viewers you have been watching Science at Soast. I'm your host Pete McGinnis-Mark and today we had a fascinating discussion from Kelly Trucks about using lasers to look at contamination in vegetation. So Kelly thank you very much for being on the show I learned an awful lot this time so thank you and please come back sometime and so we'll see you again all next week at the same time so for now goodbye. Thank you so much for watching Think Tech Hawaii. If you like what we do please like us and click the subscribe button on YouTube and the follow button on Vimeo. You can also follow us on Facebook, Instagram, Twitter and LinkedIn and donate to us at thinktechawaii.com. Mahalo.