Transcript:

 

BRAD NEWBOLD 0:00
Hello everybody and welcome to We Measure the World, a podcast produced by scientists for scientists.

SARA ACEVEDO 0:07
Sadly in Chile a couple of years ago massive wildfires occurred, I saw an opportunity to do some impact for the community studying the soils because wildfire affected soils changes some properties sadly, one of them is the hydrophobicity and that is involved with erosion because always the wildfires obviously occur in the dry season but then the wet season started and you can see a lot of soil looses because that when I model a year and I calculate it I model infiltration I saw that is not the it’s not the same. So you cannot assume that soils are just increasing bulk density, you cannot assume that wildfire affected soil is like a regular soil.

BRAD NEWBOLD 0:56
That’s just a small taste of what we have in store for you today. We Measure the World explores interesting environmental research trends, how scientists are solving research issues, and what tools are helping them better understand measurements across the entire soil plant atmosphere continuum. Today’s guest is Dr.Sara Acevedo, Sara received her master’s in soils and geochemistry from UC Davis and her doctorate in engineering sciences from lab Pontificia Universidad Católica de Chile. She is currently assistant professor at that same University where she teaches courses in environmental biophysics and statistical methods, and soon geology and Soil Sciences and soil conservation. She is also a researcher at the Center for Sustainable Urban Development. Her research centers around lab and field studies related to soil environmental science, with specific focus on soil physics. And her recent interest has been to understand urban soil ecosystem services. And today, she’s here to talk about her studies looking into urban soils, geochemistry, soil physics, and more. Sara, thanks so much for being here.

SARA ACEVEDO 2:02
Thanks, Brad. Thanks, Shaun. Thanks for having me here. I really appreciate being here today.

BRAD NEWBOLD 2:09
So to get started, what we’d like to do with each of our guests is to have them talk a little bit about their background. So, we’d love to know how you got into the sciences, how you got into soil science and soil physics.

SARA ACEVEDO 2:22
Okay, so, my path in science overall is has been not very straight not linear. So, for example, I started studying chemistry as my the equivalent of my bachelor degree in Chile. Well, by the way, I am a Chilean scientist, and, and when I started with my chemistry uh a my chemistry degree, I took some courses, some classes related to soil, and then my first job was, was as a research assistant in water quality lab. So, I started like to focus on water. And then I realized that the water quality the amount of water was related with soil and then I became interested in soil science. So, then I, this pushed me to study soils and I apply for a scholarship and I got my master’s degree in soil science your chemistry at UC Davis, and then eventually my PhD in Engineering Sciences focus on only soil physics. So, basically, I started with water, then with soil, then again with water, but now more looking for the relationship between soil and water right. And whenever I am asked, What do you do for a living? I my answer is like, I try to disentangle the soil water relationship. So that’s my, I love that. And now, because I am studying my career as a researcher, I am looking what could we how can I make an impact in this a disciplines so now I am interested in soil physics, but focus on the humans and soils focus on the ecological ecosystem services now. So started with water, now soil water, the relationship between soil and water, and now in cities. So to sum up, that was my, my path.

BRAD NEWBOLD 4:41
So you mentioned there, ecosystem services. For our general audience who have some science background, can you get a little bit more into details about what that means that that term that phrase there ecosystem services.

SARA ACEVEDO 4:57
So an ecosystem service is, is what a resource in nature provide us, right? For example, soil provide us food, provide us a water because soil can filt- filter water, and provide us clean water, right. And when I said hydrological ecosystem services, I can translate it to the water, pass through soil. And we need that, because water is into a cycle, right. And part of the cycle covers that the water should pass through the soil and provide us a groundwater, water for plants and avoiding runoff. So, when we’re talking about a ecosystem services, soil provide us a lot of safety, because we need food. So food safety, clean water, and now I am interested in trying to quantify that is those ecosystem services.

BRAD NEWBOLD 6:11
So how would that look and we can get into this, this is kind of a transition into some of your recent research, how do those ecosystem services especially the soil ecosystem services, look within an urban environment? I would I would assume those ecosystem services, especially when in relation to the soil would be much different within an urban environment as opposed to an agricultural or other natural environments.

SARA ACEVEDO 6:36
Yeah, well, Brad said it perfectly, because I think I am trying to solve there is a clear gap of my areas soil physics in relationship with non agriculture environments, because it’s easy for us to understand that well I apply water to plants to crops I am getting crops right I am getting food. In urban soil in the urban context, soils provide us support like for like walking in a park for example. But at the same time, the soil in the urban context can decrease the amount of water that going through the natural water cycle. So, what is the natural water cycle are what is the natural ecosystem services in the soil is not with us. So we are using it. So commonly in the cities, we are sealing soil, we are applying like a pathways, I don’t know, a we are loosing a non-native species like grass. So we’re using a lot of a lot of more water that, for example, I am from Chile, Chile is very similar to California, like, between Los Angeles and San Francisco. So and we’re using a lot of water for keeping that grass alive in the cities. So that’s the difference. So the ecosystem services that the soil providers in cities are related to the water cycle. So now we know that there are a lot of extreme events related to weather. So sometimes we have drought, right, and at the same time, we can have a extremely heavy rains. So the infiltration and the runoff are playing a role in the how the soil can provide us. Provide us these ecosystem services for us. You are Brad, you’re an anthropologist.

BRAD NEWBOLD 8:47
That’s that is my background. Yes.

SARA ACEVEDO 8:49
You’re right, you’re right. I think they this is my opinion, we can discuss it, I don’t know if the ecosystem services are like super focused on the like, human center, like it’s like the soil and the water providers, right. Yeah, I think in the urban soils people is living in cities now. So, people people is not living in the rural areas anymore, at least in the same percentage as like I don’t know 50 years ago. So now humans we are very egocentric. So, we are trying to quantify how the soil can provide me a something. So in the urban context is I think is is more evident, right. Yeah.

SHAUN WELDON 9:35
So with your with your studies, are you looking as as urban centers expand? Are you looking at impacts to surrounding native soils as well?

SARA ACEVEDO 9:47
That is that a good question a challenge for me and a headache constantly in my head in my head because urban soils in terms in terms of for example, legacy survey data have been neglected because the ecosystem services in agricultural soils are more evident, right like food, they are not data in comparison to agricultural, I don’t know, a soil service. And it’s hard to compare is in terms of geological in terms of a background, for example, for metals. So, that is not my areas of study directly. But I am collaborating with colleagues that, at the same time that they’re studying with me filtration, the same samples or use are being used for heavy metal analysis. And we can quantify it, and we’re quantifying I don’t know, elements, but we’re not sure if that elements were in that same amount, like, Is that normal? Yeah, with the filtration with heavy metals. We are like, kind of blind at this, at this moment. There are some colleagues, that they are pushing the term like, urban rurale boundaries, like trying to figure out in which areas of the city we can like find not urbanized soil. So I don’t have the clear answer for that question. But yeah.

BRAD NEWBOLD 11:29
I was also thinking with, I mean, with urban soils, so Sara, you mentioned that, you know, in these urban environments, we, you know, humans are putting seals on top of, on top of the those soils. And in my mind, and maybe this is for those who are not, not soil scientists, but But again, as as a human, we see that seal is there. And our focus then becomes on the roads and the walkways and the buildings and other things. And, but there’s still there’s still soil underneath, there’s still there’s still activity going on. There’s still infiltration, there’s water movement, nutrient movement, other things going on. And so it’s it’s it’s kind of one of those things where at least in my mind, I have to like reconceptualize, okay, just because this is an urban environment, there’s still things going on, within the soil, that, that, that researchers, like you, thankfully are looking at, to try to help us better utilize our soils help us especially within the civil engineering side of things, being able to, to, to still develop those cities, but do so you know, sustainably and, and safely when it comes to Yeah, how how our constructions, our human constructions interact with those those previously native soils with the top soils that then may or may not get removed. There’s other things that we tried to do to, you know, to improve with, you know, green city projects are the things like that, but But still, it’s it’s, it’s a, at least from my perspective, it does seem like a challenge to be able to figure out what is going on beneath those beneath those urban environments. And what impacts do we have on on the soil beneath and vice versa, like you talked about with those ecosystem services, there’s still surfaces that that those soils provide to us stability for our buildings and roadways. I know we’ll get into some of your research into into park and you know, places where we try to maintain the greenery or beautify our cities or, or other things like that. So that being said, in studying some of these urban environments, and urban soils, and you’ve talked about, you’ve done some research, looking at different the soil characteristics and soil properties in some of these urban environments. So looking at metals and amount of organic organic matter, infiltration and those kinds of things. Can you give us a little insight into some of those research projects that you’ve had? Looking into those? What are some of the main questions you’re looking at? And how do you go about? Or I guess Yeah, the main questions that you’re looking at the main hypotheses that you’re testing and how are you going about that, that research?

SARA ACEVEDO 14:28
When I just started reading about about soil physical properties in urban soils, I read a lot of statements or even like, how do you say axioms like when a statement is like a reality, saying that the soils, the human soils are very heterogeneous, and also a compacted like suffering compactation. And this these statements were from research Obviously a per view mayde by a recognized scientist, but from other cities, even other climates. So, at the beginning, my, like, my first hypothesis was, let’s see, our soils in the urban context in central Chile, a Mediterranean climate area are the statements at the unity and competition are real. So I have some just preliminary data regarding a compactation. I have not a observed high densities, like in any of the park that I already study. Disclaimer, this is just under development, preliminary data, but I was super curious about how this statement in another places where was this allegedly compactation? And for example, in other urban contexts we have it’s snowing, it’s snowing, it’s not happening in. In Santiago. Also, there are some chemical addition in winter in some cities, like for de icing, I think that’s the process right? When you add salt for removing some a snow packs in some cities, and that is not happening Sin Santiago. So my first thought is related with my preliminary data in urban soil. physical property is that the urban context plus the climate, the conditions are different. So I cannot compare Santiago or maybe Los Angeles, Los Angeles, California cannot be compared directly for example, for example, with Boston with a with I don’t know what other city, New York St- St. Petersburg in Russia in Russia, I don’t know. So, I think first a climate and human action. So, the salt is added by humans not by the nation right. So a lot of a social differences and also climate difference. So, were I am, I am, I am um seeing, like a trend that we cannot compare city’s, because in the anthropic pressures are different, plus the climate, much more differences between cities. So that’s my first like my first findings. Also regarding a regarding to soil hydrualic properties, I started measuring infiltration with the MiniDisc Infiltrometer and I had found a lot of homogeneity not heterogeneity for the audience for the general audience. Sometimes for scientists, not finding differences is like a knife like p values greater than 0.05 Like oh my god! And I am I am seeing that a lot of homogeneity. And at the beginning, it was like, not very unattract air. Sounds unattractive for me. However, I am thinking about like, if life gives you lemons, right? So what what if they constructed soil? I am going to use some technical words the techno soils, the anthroposols that some names, technical names for human soils, what if maybe, they’re not a lot of heterogeneity, and that could be an advantage for modeling. So, if all the human soils in a big area are similar, probably if I model them using a numerical approach, because the parameters the inputs for my model are similar, but I am decreasing uncertainty. So that’s my that are my second like thought of findings about my preliminary data. So not compactation, different processes, different climates. And if may we disclaimer is still a work in progress. If there are a lot of homogeneity, maybe I am have to move from the field, and then go into the computer and start comparing modeling with real results.

SHAUN WELDON 19:41
In your interactions with you know, municipalities like cities and things like that. Have you found that they kept records of, of some of that development process for those things? Or was it just kind of our best practice at this time is to use this kind of soil and and they just kind of threw it in there to make it look nice.

SARA ACEVEDO 20:03
Yeah, now currently, because I am an all run scientist, now, I am in the field in the computer in the lab and also, I am in a private by private I like asking to a the all manager in the parks like, Hey, how are you, sir? Have you? Do you know if 10 years ago the soil was similar? Yeah, I am a I have to talk about about my research with a lot of cities. Yeah, it has been a lot of fun, though, because I have to ask, because commonly the maintainers, the manager of the parks, know, everything, more than even the records of the municipalities of the of the government. Yeah. So for example, in that way, I figured out that in the campus of my university is like, pilot study for me, because it’s close to my office. Yeah. And the people who is in charge of the gardens, like the parks in the campus, a start a talking to me like, Sara, come, come come here, come here. In that part, there are always a lot of bonding. And I said, Really, and I took some samples, or people saying, look at that, in that part, they, Oh, a manager, put a lot of rocks and then they put soil. So I got some clues. And yeah, so I had to a research in in a new way for me.

BRAD NEWBOLD 21:46
as you’re going about your talked about your modeling in these particular areas, what are some of the some of the key you mentioned parameters, were some of the key parameters that and inputs that you have to to the models that you have been working with or hope to work with?

SARA ACEVEDO 22:01
Well, my approach is from the simplest to the most complex. So, I am starting with a filtration and soil texture like a basic characterization. And then I am interested in measuring a saturated hydraulic conductivity and the Van Genuchten parameters from the soil retention water curve. So, that is my laboratory approach for then getting parameterization of the soils. And then I started a with simple models, I have focused on infiltration and runoff. So a probably I am going to start with some simple water valance models for that. But a lot of them use a KSAT Van Genuchten parameter here.

BRAD NEWBOLD 22:52
One really quickly as I was looking through one of your publications, so you mentioned KSAT so saturated hydraulic conductivity, we’ve got unsaturated hydraulic conductivity. You also mentioned using near saturated hydraulic conductivity. Can you can you explain what what near saturated hydraulic conductivity would represent? How closely saturated is your saturated hydraulic conductivity?

SARA ACEVEDO 23:18
Well, that’s a is a very good question, at least for me, the near saturated hydraulic conductivity is a PSI estimation that I got from Anna feeding from a curb base on infiltration on time. That is my like Professor answer for that. And for me, for example, I can only compare like the results with the MiniDisc like this near case, not near k with k set. So for me, it’s more than an operational differences because the processors are so the case that is more time consuming. And sometimes I need like an estimation of what could be this. Okay, more than the sack value. So that’s why I made that difference. All

BRAD NEWBOLD 24:17
right. So that near saturated then is like, like you mentioned, so like you said, you’re fitting to a curve. So you have an original example potentially, where you have that full curve, is that is that correct? And then you’re seeing where that that near the near saturation, and then you’re taking that point and being able to extrapolate that and and use it for other for other examples, other samples and things.

SARA ACEVEDO 24:42
Okay, yeah, I think I think that’s unfair, right? Because hydraulic conductivity depends on suction and also water content. And where I own the field, I cannot control the water content. Commonly I just a make sure that the soil is not very wet. And then I make that measurement. I don’t have the laboratory control conditions. So that’s why I made that difference.

BRAD NEWBOLD 25:14
But I understand the approach and especially like you mentioned, with time consuming, and I’m sure, you know, Shaun could talk about how time consuming working with these curves can be as your, you know, wetting and drying and you know, back and forth, yeah, it can take quite a long time. So being able to have have a, a simplified or a shortcut to be able to, to approximately, you said estimate or approximate those final results would be super helpful. Along those lines you also mentioned, and with your background in in chemistry, there’s some research into toxins and metals and other things that you were finding in the soils. were you seeing, I guess, what were you seeing in with those results, whether preliminary or not? And how how are they? How do they seem to be compared to other locations, whether urban rural, or elsewhere?

SARA ACEVEDO 26:10
Yeah, for example, South America was colonized by Spaniards by Spain, so the shape of the cities are like, in a concentric way, like people started close to the river, like in a central square. And then people start like developing houses in different rings. And in Santiago, they’re like, like a highway that a split Santiago in like two parts, like they all Santiago like the old city, and the newer part of city outside that ring. And in terms of soil physical properties, soils within in or out of the of this ring, there was pretty similar bone density, very similar infiltration, I am seeing like something similar. So, like, not very funny for me, like the soil faces this of the team. However, for the soil chemist in the team uh and this is a thing that has been reported in an in other cities, basically, the oldest areas of the city concentrates a organic matter and also heavy metals. So the relationship among them, it depends, because organic matter can stabilize metals accumulate them, so what I am talking about just concentration amount, not by your availability, uh, we can see that so they are more uh they’re more occurrence of higher concentration of heavy metals in the inner ring Santiago than the older side of the city. And that allow us to a figure out that there are an effect of the human pressure in the city in the soil. Because all the soils in terms of bulk density, even texture are similar. And there’s some hotspots of heavy metals something so we are a we as a humanity are a producing some impact in the soil. And for example, pH has been reported as also change in different levels of urbanization in cities. However, we didn’t see that in Santiago, and we think I am suggesting innovate. And that probably is because the human processes of applying salt maybe could be different in different latitudes.

BRAD NEWBOLD 29:15
Are you seeing or is there a general understanding of where these where these heavy metals are coming from? Is it just from just just human use in general, or are there other outside sources? I know like there’s, you know, depending on if cities are near, you know, mines or older mines or if Yeah, if you’re, you know, downstream from from other, you know, yeah, other other situations like that, whether it’s mines or other things that these heavy metals then could can get either just deposited where they are and and infiltrate or is it infiltration via, you know, the rivers and streams and and waterways?

SARA ACEVEDO 29:56
Yeah, so, in Santiago, it’s kind of complicated because Chile it overall is a mining country. So that means we have metals everywhere. That was our main export source of PIV in Chile. So a lot of copper around a lot of ores. And we don’t we are not sure about the background in the city. So as I mentioned before, now we’re getting those results, and we cannot tell if maybe the amount of copper in the city is because the human activity or maybe the natural occurrence of that metal in Santiago, however, a lead is commonly related with traffic. Because a like 20 years ago, 10 years ago, the gasoline?

BRAD NEWBOLD 30:50
Right, yeah, yeah. So yeah. Yeah. To when gasoline was was not anymore. Right. Right.

SARA ACEVEDO 30:57
Exactly. So that is like a fingerprint of the use of gasoline in cities. And the evidence said that lead, Zinc, and copper, the source could be traffic, like a the legacy of those cars around in the city. I didn’t mention that I am, because where I am, I am just starting my research, I am focusing on top soils. And in that way, I can also collaborate with my colleagues who are working with a studies in metals in soil. In the future, I want to dig a little more. Yeah. And in that case, maybe we can now if the metal concentration can be produced by legacy, or natural occurrences. The those, those hypotheses will be a avoided in the future not now.

SHAUN WELDON 32:06
So as you get into those kinds of future studies, then you’ll be able to also determine the fate of some of those chemicals and metals that are that are moving through the..

SARA ACEVEDO 32:17
Yeah, so do you mean what’s the future like the following step or?

SHAUN WELDON 32:22
So does I guess one of the questions that I’m thinking of here is, does Santiago for example, use? How deep is the water table there? Is metals are metals moving through there?

SARA ACEVEDO 32:35
Yeah. Okay, so I think you’re thinking like me, and trying to connect this to a these two branches like metals and filtration, yeah. Well, Santiago, is located in our basing, we have a river crossing the city. And the water table, I don’t have those numbers now in my mind, however, wearing made the ranan climate, so we have two seasons, like the dry season and the wet season. And obviously in the wet season a there are a lot of infiltration through the, through the groundwater in the city. And I don’t I do not have more information more that I think a for example, in Santiago, a the groundwater the water overall in, in Chile in the central part, it has great quality. So, for example, I have also collaborated with water quality before because my background, so I think it shouldn’t, it should worry about metals. A like leached out due to infiltration is not a problem, at least now. Maybe in the future. I don’t know. But now, they are not evidence of that, at least in Santiago.

BRAD NEWBOLD 34:09
Anything else that you would like to cover when it comes to urban soils. I know you’ll get talked about this for a long time. Anything else that you’d like to bring up was in particular on this on this topic Sara?

SARA ACEVEDO 34:21
I want to mention not not related with urban soils. However related with my like, my computer component of my research. So now I am promoting in my lab and now as a professor, proudly with my students and developing reproducible research a and trying to move to open source science. So I think it’s us a society as scientists like we have to to ensure quality data and reproducibility of our results. And that’s why I already develop some packages. So my first one was for a processing data from the MiniDisc because the Mini Disc has a macro associated with the with a Van Ganuchten parameters according to texture, and that’s okay However, now I am using our for processing data and I did not want to move like a open and close or working with with two a software’s at the same time. So, I moved all that information from the macro to our packet. So, in that way, I can download that information to my Rs grip, and work and run all together without a having to open and closing every Excel macro, when I am running one measurement. And at the beginning, I was hesitant to do that because I thought why because I can do that in the macro. Or if I am doing in our way I am sharing my my work. And when a person in a conference told me that he was using the bucket, and he saved a lot of time processing data, and he got the same results with the macro a and I started thinking if promoting this open source research could be a way to accelerate the, the science through reproducibility. Because for me, it’s important that I am having the same results, I am using exactly the same Van Ganuchten parameter every time that I am modeling, for example. And also, I already a develop on our package for flooding, soil texture. And also other colleagues are using it. So I’m very happy about that. And I really like to use colors in my, in my publications, I really think that data visualization is very important. So I took our classic package a very commonly using R. And I tried to put my way to plot the soil triangle in my own way. And I think it’s important that scientist uh should be push should be a force include forced to use a more reversible tools.

BRAD NEWBOLD 37:59
Open source sharing of information, but I mean, that’s that’s how the process should work. Right? That that when we shouldn’t be hoarding our data and our our results and all that, yes, we want to publish yes, we want to move forward in our careers, other things like that, but, but we want to also be able to, to impact, you know, hopefully, you know, are not just, you know, our local area, but but be able to share with us to help, you know, help improve things throughout the world. And if there’s things that we can find and discover here, where we are, yeah, being able to share that open source, other things like that is one of the quickest ways to be able to do that, aside from you know, waiting for it, you know, again, how long does it take to publish a paper, right? It takes forever, or, or conferences come around, you know, once a year, or the things, but when you have, you know, open source and sharing that that’s something that can happen, you know, in real time, essentially, in many ways. Yeah.

SHAUN WELDON 38:57
And I think that’s important. Someone was saying earlier that everything is connected. So this data that she has on this somebody else can be using, to to include into their research, which, you know, nobody can study everything all at once. So this this important research that she has can be used by others here. And she can use stuff from other people as well. And that’s critical to know

SARA ACEVEDO 39:17
So I am trying to I am trying to open the process, because sometimes I am sharing some data but not all my data because I want to publish that right. However, I am opening the way that I am processing the data. Because I can make sense. Yeah. If my uh my, for example, my Van Ganuchten calculations are open for everyone that can double check that I’ll be happy. Maybe I am. I am not because a that package is in the middle of in revision from and so it’s okay. But at the beginning, for example, maybe it’s very useful to a Share your methodologies. And I want to say thanks to METER because you guys are being always super open to help scientists to start when I started using the equipment, I had a lot of question and if we have open or methodologies uh, we can accelerate in getting the results more quickly and more accurately. So I think that’s important.

BRAD NEWBOLD 40:28
Alright, with the last bit of our time, let’s switch gears I would love to learn more about your research into wildfire affected soils, we have several other of our of our customers who are doing certain, you know, research into similar things out in the field, it seems that some of your stuff has been done in the lab and trying to, in trying to mimic wildfire affected soils and other things like that. Can you talk to us, I guess in general about about that those research projects and what you’ve been trying to find out and what you have been finding?

SARA ACEVEDO 41:03
Yeah, one part of my thesis was a to compare a, I was at the beginning very focused on the equipment like HYPROP. So, I want to use HYPROP for compare things. And sadly, in Chile a couple of years ago, like five years ago, massive wildfires occurred similar to campfire maybe. So, in the same order of magnitude. And I, I saw an opportunity to do some a impact for the community a studying the soils because wildfire affected soils changes some properties sadly, one of them is the hydrophobicity and that is involved with a erosion because always the wildfires obviously occur in the dry season summer, but then the wet, the wet season started and you can you can see a lot of soil losses because that my research was focused on the methodology like studying curves, one challenge that I had was the Hydrphobicity in the lab, it was super hard to saturate that samples in also great challenge for me was tried to capture the effect of fire in the cylinder. So, for the audience a when we are analyzing soil hydraulic properties, commonly we use some metal cores. So, a cylinder that you try to bring to the lab the intact core right and sometimes, because in the movement of the car, when you are a bringing the samples of the to the lab, for example, I could see like the millimeters affected by the wildfire in the soil, their cylinders are five centimeters, and one challenge in the lab for me was tried to keep that effect like very carefully like this one millimeter amount of arches in that court. So, it was challenging obviously, in also I tried to figure out if this changes, when for example, when I calculated the Van Ganuchten parameters from that measurements, how the modeling can be affected. So, those were the findings of the of the day paper fears, some insights about how to handle that maybe that that bilevel a solid color and also is not the same modeling a organic matter the loss of organic matter as a soil with a less organic matter. So, basically I said I have this this this soil with less organic matter because was affected by a wildfire in God the banking of the parameters using Rosetta this build transfer function and then I measure the real one and when I model like a year I think and I calculate it sorry I model infiltration I saw that is not the it’s not the same. So you cannot assume that soils are just a decrease in for example or increasing bone density. You can not assume that burn or a wildfire affected soil is like a regular soil. So I think that’s the, the, the main message of that paper. And also colleague, a master’s student in my lab, try to a, like forensic study. Good. I see. She had this wildfire, a course, the real ones, and trying to compare with soils burn in the lab. And I think that paper doesn’t have a rule of thumb for for all the cases, but these paper a highlight what could happen in every in in every texture or a different level of organic matter. It’s very interesting.

BRAD NEWBOLD 45:49
That is very interesting. What What were some of the, I guess, maybe you might know or not, but what are some of the key soil properties that that you saw the most change in when it comes to these wildfire affected soils? As opposed to you know, quote unquote, normal soils?

SARA ACEVEDO 46:07
So the first yeah, the first one is there a amount of organic matter, we could see an evident decrease of organic matter in the first centimeters, then hydrophobicity. And there are a lot of ways to quantify a hydrophobicity We tried. We tried using alcohol with infiltrometer. And it worked very well in the hydrophobicity increases, and also it affects case because we a we observe a lot of resistance of water to wind through the soil, because the hydrophobicity and don’t want to do some wrong statement. However, there are some changes in pH and I think, electric conductivity, however, I am not sure if with the amount of samples that we took, we have enough A we have enough a statistical support for a make a statement that that so I think organic matter and sort of hydraulic properties related with hydrophobicity.

BRAD NEWBOLD 47:15
Any other thoughts or questions Shaun on that one?

SHAUN WELDON 47:17
One question on that one is we did you look at different severity of wildfires to look at the different effects to the soil?

SARA ACEVEDO 47:28
Yeah, however, a we took two approaches. So the first one was the information from our satellite like models that you can like sense the whole big was the temperature in the surface and in the atmosphere. And then government classification of the wildfire. And also it’s not in the paper. However, we use it a lot. We use color like based on Munsell because ashes tends to have some gray grave colors. And if you have like the original color of the soil, you can see like a dilution of the hue on the Chroma. And you can like see how gray is the soil in comparison with an area not burned not affected. So you can see how, how much arches like were incorporated in the soil looking in the color. Like, like rough [inaudible].

BRAD NEWBOLD 48:35
Interesting. What were the primary? What I guess what’s the primary soil type that that you’re working with, with, with these cores?

SARA ACEVEDO 48:43
A soil in Santiago is Have you have you seen this temporal areas in California? Like kind of similar like like with batches or small trees.

BRAD NEWBOLD 48:56
Right right, okay.

SARA ACEVEDO 48:57
And also commercial, a plantation of trees, like for exploitation of a oak tree, right. Okay. Because those a ecosystem are prone to a wildfire.

BRAD NEWBOLD 49:12
Okay. Yeah, that is very similar to California. Where you do have a lot of those oak forests. Yeah. And Chaparral and others things.

SARA ACEVEDO 49:21
Yeah, it’s like we had like our own campfire like event in Santiago in knowing in central Chile and sadly it’s getting more a it’s happening like every year at different scales sadly.

BRAD NEWBOLD 49:37
Yeah. Yeah, definitely.

SARA ACEVEDO 49:39
Yeah. I think that’s why it’s very important to quantify this affecting the soil.

BRAD NEWBOLD 49:44
Yeah, I think and with with California as as a model as well, as well, like you mentioned where you do have these wildfire events, followed by wet season. And and just the the, not just the natural impact, but the huge the human impact. Uh of that as well, where you have your, your landslides and erosion and, and impacts on. Yeah, if there’s any kind of whether or not there’s urban areas or other things like that, that’s a bit outside. But But yeah, just that general human impact on on roads and homes and, you know, whatever else may be out there, so.

SARA ACEVEDO 50:22
Yeah, and because they, well when I talked to Chile, just imagine they’re all siloed off, there are a lot of settlements located in hills. Okay. So those also can be affected, sadly, by fires, and also can be prone to erosion by a heavy rains after the dry seasons.

BRAD NEWBOLD 50:44
Yeah. And that’s the thing, too, is like, even if they may not be directly impacted by by a wildfire, but there’s those other subsequent effects through erosion and other things that then could lead to, yeah, slope stability issues, you know, all those kinds of things so.

SARA ACEVEDO 51:01
It can be that related with metal, maybe everything I have.

BRAD NEWBOLD 51:09
All right, well, what do you see is the future of your research here, Sara, you can focus on on your urban environment studies and just kind of let us know what what do you see in the next, I don’t know, 5 to 10 years of what you’d like to be able to find out and accomplish?

SARA ACEVEDO 51:29
Well, I think, as I mentioned before, the lack of information is the main challenge in my area, however, I can take that as an advantage, because maybe I can like plant a seed, like, see the whole the site code to analyze the oversold properties in CDC in Santiago, because they lack of information, I have a lot of flexibility for developing my own framework. So my the future of my research depends on me, because I am kind of free at the beginning. I am very interested also in starting an archive. Because I think a urban soils could be like a thermometer of human impact in soils of Rome. So my plan is being the who take the decision about the soil physical properties, the analysis, and then start doing soil archive in my university. So in that way, maybe in 10, and 20 years from now, maybe this questions that we are discussing now, could we have a new approach? And maybe we can answer that easily. Also, my research depends on if I can talk with the decision makers, because for example, the development of sustainable green areas in cities is necessary. So water is getting scars, how decision makers can use my data, for example, now in Chile, a, there are some new laws or new proposal for using reclaimed water in cities. And what happened with that type of water in the soil. There are some evidence about if you use reclaimed or grey water, a maybe you can change the structure in the topsoil, in what happened with the soil hydraulic properties, in that case is in other scenarios. Also, irrigation plants can be affected if the soils are hydrophobic, compacted, you need to know first what we’re doing to the soil for taking proper decisions. So I think the future of my research depends on me. And then if I can talk with decision makers in the future, and try to apply this knowledge to climate smart cities, or resilient cities, and so on.

BRAD NEWBOLD 54:13
Sounds good, good luck with that then any any final questions that you…

SHAUN WELDON 54:17
No, I’ve learned a lot today it’s been it’s been a really great conversation. I think this research you’re doing is going to be giving that basis for future studies that you’re that you’re lacking in the history in yours. I think that’s fantastic. It’s a great contribution.

SARA ACEVEDO 54:31
Yeah, I want to make a history

BRAD NEWBOLD 54:34
There you go, there you go. Make history.

SARA ACEVEDO 54:37
That’s the idea.

BRAD NEWBOLD 54:38
All right. Well, our time’s up for today. Thank you again Sara for joining us.

SARA ACEVEDO 54:43
Time, flies!

BRAD NEWBOLD 54:44
Yeah, we really appreciate you taking time to talk with us.

SARA ACEVEDO 54:48
Thank you for having me and having some patience and my English is not very well. So thanks for for being so kind yeah.

BRAD NEWBOLD 55:00
Your english is much better than my Spanish. So I’m not gonna speak for Shaun, but we appreciate it. No, it has been a really interesting conversation. So thank you very much.

SARA ACEVEDO 55:10
Yeah, I had a lot of fun. And I hope that the audience enjoyed this conversation as I enjoy.

BRAD NEWBOLD 55:18
I think they will. And if you in the audience have any questions about this topic or want to hear more, feel free to contact us at metergroup.com or reach out to us on Twitter @meter_env. And you can also view the full transcript from today in the podcast description. That’s all for now. Stay safe, and we’ll catch you next time on We Measure the World.