Scientifically Speaking | The world is running out of useful sand

Published on Mar 16, 2022 02:10 PM IST

Much of the world’s concrete will disintegrate and need to be replaced. Unfortunately, as ludicrous as it may seem, the world is running out of the sand needed for reconstruction

I spent many years just a short bicycle ride from the sandy banks of the Kangsabati river. Sadly, whenever I visit now, I come crashing back to reality. The river still exists, but it looks nothing like it did a few decades ago.(Shutterstock) PREMIUM
I spent many years just a short bicycle ride from the sandy banks of the Kangsabati river. Sadly, whenever I visit now, I come crashing back to reality. The river still exists, but it looks nothing like it did a few decades ago.(Shutterstock)
ByAnirban Mahapatra

Whenever I think about my hometown, Medinipur, I always think of the river next to it. I spent many years just a short bicycle ride from the sandy banks of the Kangsabati river. Sadly, whenever I visit now, I come crashing back to reality. The river still exists, but it looks nothing like it did a few decades ago. Years of a constant stream of lorries that dug up and took away sand for construction of nearby houses has decimated the wide sandy banks of the river. Not only is the aesthetic appeal of the river gone, but the entire fragile ecosystem surrounding it has also been disrupted. Perhaps, things will never return to the way that they were in the past.

The same story has occurred across much of India where the amount of sand used annually has tripled in the last 20 years. People are being killed for sand in cities and towns across the country. Sand mafias and pirates are fighting for the rights of a resource that we had taken for granted. 

And the same stories are making headlines in dozens of countries like China and Sierra Leone. River sand mining hasn’t simply destroyed my childhood river, but rivers all across the world, from Mexico to Vietnam. 

Most of what humans build requires sand. Sand is needed for buildings made of concrete and for roads made of asphalt. Sand is needed for glass windows. And there’s an incredible amount of sand in aggregate — a slurry made with gravel that forms much of concrete. 

In his wonderful book, The World in a Grain: The Story of Sand and How It Transformed Civilization, journalist Vince Beiser travels the world in search of sand. Beiser extolls its virtues. “Sand is the main material that modern cities are made of. It is to cities what flour is to bread, what cells are to our bodies: the invisible but fundamental ingredient that makes up the bulk of the built environment in which most of us live.”

As much of the world’s concrete disintegrates due to age, weathering, or shoddy quality, it will need to be replaced. Unfortunately, the world is running out of useful sand. Ironically, Dubai has to import sand from Australia for its development needs! And Singapore has built up and extended its area by pouring in sand from other countries. Countries have redefined their borders by building up with sand, but there’s much less of it left to use now.

At first blush, the idea that the world is running out of sand may seem ludicrous. After all, aren’t many parts of the world facing desertification? Isn’t sand in deserts like the Sahara and the Gobi actually increasing? But there’s a twist here. Not all sand is made the same way or useful for the same tasks. 

The sand that makes up desert dunes is shaped by wind erosion. Desert sand isn’t as suitable for construction as sharp-edged quartz sand found on beaches, in riverbeds, and on ocean floors that have been formed through water erosion. Desert sand is round in shape while the sand we desire in building materials like concrete has to have jagged interlocking edges. Beiser compares trying to build with desert sand with attempting to construct buildings with marbles instead of with blocks. 

Technically, there are many kinds of sand — from the white sand on beaches across the islands of the Caribbean, which are inedible bits of calcium carbonate that are pooped out by parrotfish that eat coral, to the black sand that is made from ground-up volcanic rock. In fact, sand is often described by its size and hardness more than its chemical composition. That said, the most famous sand is silica sand which is made up of silicon dioxide. 

Silicon Valley is named after the silicon found in this kind of sand. Silicon chips inside smartphones, tablets, computers, and cars are made from sand. Here also, not all sand will do. Some of the purest quartz deposits are mined near Spruce Pine, North Carolina, a sparsely populated town in the Appalachian Mountains of the United States. The ultra-fine quartz mined here is used to make crucibles needed by the semiconductor industry. High-purity silica sands are also needed to make glass, fibre-optic cables, and solar panels. 

What is clear is that we have taken sand for granted for too long. Today, we would do well to heed Beiser’s stark warning: Like many other natural resources, we must not treat sand like we have an inexhaustible supply of it.

Anirban Mahapatra, a scientist by training, is the author of COVID-19: Separating Fact From Fiction

The views expressed are personal

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