Arizona researchers are looking into ways to keep desert dust on the ground

Dust getting in the air can be a big problem in the desert — as we’ve seen this week — when heavy winds can pick it up and create a moving wall of dust. But Ferran Garcia-Pichel says dust storms aren’t the only issue — recurring, lower levels of dust in the air also have implications for public health and aviation, among other things.

So researchers at Arizona’s public universities have been looking into ways to keep dust on the ground — and not just by spraying it with water, as you can often see at construction sites.

Garcia-Pichel is one of those researchers. He’s a professor in Arizona State University's School of Life Sciences and the Biodesign Institute, where he researches microbiology and environmental microbiology. He says at some point, scientists realized microbial communities that live in the desert could be part of the solution, and as it turns out, he says, they can be a big part.

Garcia-Pichel joined The Show to talk more about his work.

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Full conversation

MARK BRODIE: Ferran, you're looking at these microbial communities and it seems you found there's a short-term solution and a longer-term solution?

FERRAN GARCIA-PICHEL: So there is two routes to this idea. One is, it comes from our lab, and we've been working for many years on these communities, and if you look at the composition of the dust in the air, and you do a little bit of forensics or CSI by looking at the DNA that's in this dust, you can tell that all of the signal that you find in this dust comes from areas of the desert that are human-impacted. But the natural desert does not emit much at all. You can't hardly find any signatures from the things that are typical there. So that tells us the natural desert, the untouched desert, is impervious to erosion pretty much.

And so that's why making or trying to figure out how to return these natural communities called biocrusts to the top of the desert would be a solution to this problem. So when a field goes fallow, for example, if we could accelerate the return of these communities, we would solve the problem in a way that is not just effective, but it's also self-sustaining. These are living communities that every time that it rains, they grow a bit more and they recover.

MARK BRODIE: And you're not using more water to do it, right?

FERRAN GARCIA-PICHEL: Well, it just what comes from the air.

MARK BRODIE: Right.

FERRAN GARCIA-PICHEL: Yes. So that was one leg. The other leg comes from the engineering sort of thing, side of things. And this is a methodology called EICP, which that was originally developed to self-restore concrete, but that found an application, various other applications. And this is based on adding a mixture of chemicals with a particular reaction that happens in there, that essentially makes also a crust, but it's a chemical crust.

And this is a chemical process, and we have developed it to apply to those fallow fields, and you can make a crust that's impervious, that makes the soil impervious to erosion within a day. So the idea of this project was, can we put A and B together and do a one-two punch approach? Really like think about this as reforestation.

MARK BRODIE: Mm-hmm.

FERRAN GARCIA-PICHEL: But instead of using trees, we use microbes.

MARK BRODIE: Right. How easy or difficult would it be to scale that up? I mean, if you have a fallow field, we're talking about a lot of land here.

FERRAN GARCIA-PICHEL: Correct. And so this is a problem. And at this point, we were really pushing the envelope a bit. We had been doing sort of demonstration scale experiments, pilot experiments, sort of square-yard size, and it works. But this was already an issue for us. Can we scale it up to the acre scale? And each one of them has different problems associated with it, or with each.

For example, the chemical process, yes, it's a problem to have enough materials, but the delivery becomes a problem. For the biological restoration, the issue becomes, how do we get enough inoculum to put back? How do we develop effective nurseries or microbial nurseries, should I say, to get the inoculum?

MARK BRODIE: You have to grow it.

FERRAN GARCIA-PICHEL: You have to grow it.

MARK BRODIE: So is it fair to say then that what you're finding is more applicable for fallow fields and keeping the dust on the ground than, for example, an active construction zone where people are going to be walking around and would presumably be stepping on and kicking up the biocrust that you'd be putting there anyway?

FERRAN GARCIA-PICHEL: Yes. I think you're right in the logic of it. We can't say for sure because we haven't done construction sites. The research we've done is on these fallow fields. So anyway, we've been, you know, we've been at it for four years now, and we have made some progress, and we also have found out things that were not expected and so, which I think are important.

MARK BRODIE: Like what?

FERRAN GARCIA-PICHEL: So for example, one of the things that we were surprised about was that in some cases the best thing to do to make the fallow field crust is do nothing. And that was very surprising to us.

MARK BRODIE: Just leave it be?

FERRAN GARCIA-PICHEL: Just leave it be. That's not what we're doing as a society, and I'll explain this. So we picked a site as a test site along I-10 in Pinal County, an area that's really prone to these episodes of high dust in the air. And one of the things we had to do because this was an experiment is we had to ask the farmer, "Please do not plow the field." And what happens was the soils crusted by themselves.

And so that turned then into, OK, so now we have a different approach to apply our eventually successful approaches. If we don't have to treat absolutely everything, but let's just go treat the soils that have low carbonate because they will not crust. So that sort of suddenly, we had a way of prioritizing.

MARK BRODIE: Oh, interesting. So you didn't have to do the whole field necessarily, for example, just the areas where there was a certain level.

FERRAN GARCIA-PICHEL: More or less correct. The whole field is probably acting as one, but in terms of regional, there's soils that have high carbonate, soils that have — so we did a survey between here and Tucson, and we found out which soils are more prone to self-crusting, we don't need to touch this.

Now, the problem with not doing anything is that it's not possible, because farmers have also a mandate to plow to prevent the growth of weeds. So now we have a regulatory issue here because they are mandated by one agency to plow the field and prevent weeds from growing. From the other one, they are also mandated to keep the dust down. So as scientists, we cannot solve that.

MARK BRODIE: What does all this cost? Like, how feasible is it financially to, for example, in the areas where if you leave it, it's not just going to crust over on its own, to either grow or import a crust?

FERRAN GARCIA-PICHEL: Yes. The actual cost will probably go down the bigger we go. However, it is not cheap. You need people, you need monitoring, but how much is the cost of public health? I don't have an answer for you at how much it would eventually cost, but it wouldn't be cheap.

MARK BRODIE: So for non-farm areas where there's a lot of dust, at least for the foreseeable future, is trying to tamp down the dust with water the answer? Like, are there other things that you're maybe looking into for construction sites, for example, or for the open desert?

FERRAN GARCIA-PICHEL: Yes. For the open desert, if it's a pristine desert, you need nothing. It does not provide a lot of dust if it's open and untouched, so. If you're patient, even the agricultural fields, the construction sites, the natural crust, if you don't keep the human pressure on it, will eventually come back. 20 years?

MARK BRODIE: That's a long time, yeah.

FERRAN GARCIA-PICHEL: Are you willing to wait for 20 years? So that's the key. The intervention would make it a couple years.

MARK BRODIE: All right, that is Ferran Garcia-Pichel. He is a professor in ASU's School of Life Sciences and the Biodesign Institute. Ferran, thank you so much. I appreciate it.

FERRAN GARCIA-PICHEL: It's my pleasure to talk about what I do. I love it.