消逝如沙 | Nature Podcast

来源：Nature自然科研

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Host: Nick Howe

If I think of digging up sand, the first thing I think of is building a sandcastle. But the mining of sand is no child’s play. It’s a huge industry around the world, and its impacts are being felt by both people and the planet. In fact, humanity’s demand for sand is so large that it might outstrip supply by the middle of the century. A Comment piece in this week’s Nature sifts through this sandy problem, and one of its authors, Mette Bendixen, spoke with reporter Adam Levy.

Interviewer: Adam Levy

What is sand actually useful for?

Interviewee: Mette Bendixen

So, sand is the key ingredient actually in modern society. It’s used in buildings and construction and infrastructural projects. It is used in electronics, in glass, even in toothpaste and wine. So, we have a big use of sand globally.

Interviewer: Adam Levy

What is the actual scale of sand mining then?

Interviewee: Mette Bendixen

So, besides from water, sand is the natural resource we humans extract the most of – it even exceeds fossil fuels – so we’re talking around 30 to 50 billion tonnes that’s being used per year globally.

Interviewer: Adam Levy

It seems like, you know, we talk about fossil fuel extraction a lot, not just because of climate change but because of the impacts locally – why don’t we talk about sand extraction so much?

Interviewee: Mette Bendixen

Yeah, I’ve been wondering about that too. I think sand is something you take for granted. Sand is something you’re used to thinking is just everywhere. It’s in beaches, you have big deserts throughout the world. The thing about the deserts though is that you can’t use that as construction material because when the grains are being transported by wind, they’re simply too smooth and too rounded and they’re too well sorted. For the construction sand, that is not something that we can use unfortunately. The sand we use is coming from rivers, it’s coming from beaches.

Interviewer: Adam Levy

So, there’s this huge amount of sand being extracted. What are the actual impacts of this mining?

Interviewee: Mette Bendixen

It affects both nature and people. In South Asia, we see that ecosystems are being destroyed. River banks are collapsing which means that people lose their houses as they simply fall into the river, and that means that people have to move, and the Vietnamese government has estimated that up to a half a million people will need to move away from the flood plains and the river banks of the Mekong delta within the near future.

Interviewer: Adam Levy

But the way sand is being extracted is also causing big problems.

Interviewee: Mette Bendixen

Yes, a lot of the sand that is mined today is mined illegally. It’s being controlled by actual ‘sand mafias’. In Kenya, kids drop out of school to mine sand.

Interviewer: Adam Levy

You’re also looking at ways in which this problem could potentially be fixed. How would we begin to get a handle on sand mining?

Interviewee: Mette Bendixen

Yeah, so we say that the solutions lie in the alternatives, and that means alternative technologies. Just last year, the Imperial College London, they were actually able to make this concrete-like material with sand from the desert and with half the CO2 footprint. I think what is important also to do is reuse, which can be done when you destroy older buildings and simply reuse the material here so It’s not just being lost.

Interviewer: Adam Levy

So, how do we get from these recommendations to actually implementing something for the world that would reduce this pressure on sand?

Interviewee: Mette Bendixen

We call upon the United Nations to establish a global monitoring programme for sand resources because really, we need to understand how much sand do we have, where is this sand and how much of it is being extracted. Right now, we don’t have that. We don’t have that global overview, so we cannot use this material in a sustainable way. And I feel like the problem of sand scarcity is getting more attention right now, so I feel like we’re towards creating a momentum where this will get more focus.

Interviewer: Adam Levy

How do you actually feel about whether we can and we will turn this problem around?

Interviewee: Mette Bendixen

I think there is becoming an increasing awareness that we need to do something about this issue because sand is not something we should take for granted, and after having worked with this, I realise now how much sand is actually being used. Just outside my door, they were redoing the asphalt there and I realised well, that’s sand there, just across my building from where I sit there’s being built a new building. There’s just sand everywhere and you don’t think of that.

Host: Nick Howe

That was Mette Bendixen talking to reporter Adam Levy. Catch her Comment piece over at nature.com/opinion. ⓝ

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