Harvesting metals from plants

We are surrounded by objects made of metals and minerals: from complex machines such as cars, computers and smartphones to simple objects such as batteries, coins and cutlery. All the metals and minerals in these objects are obtained by mining, the process of digging materials out of the ground. This can be done in two different ways. There is surface mining, which scrapes a piece of land to get to the materials below, and there is underground mining, which uses tunnels to reach the metals and minerals directly underground. Any material that cannot be grown must be mined, but this might change: a group of scientists, including Alan Baker from the University of Melbourne, and Antony van der Ent from the University of Queensland (both in Australia), are developing agromining (also called phytomining), which uses plants (rather than bulldozers and excavators) to extract specific metals and minerals from the ground.

Mining plants

These scientists have discovered that there are about 700 plants that flourish in metal-rich soils. Their roots suck the metals out of the ground and store them in their sap, stems and leaves. Antony van der Ent is experimenting with macadamia trees, known for accumulating manganese. Dr Baker and some of his colleagues, for their part, are experimenting in a vegetable plot in Malaysia with plants that accumulate the metal nickel. Every few months a farmer harvests part of the plants and, using a simple process, extracts the metal. Nickel is particularly interesting, as two-thirds of metal-loving plants feed on nickel. Scientists like van der Ent and Baker hope that, in a few years, a part of global demand for certain metals and minerals will be supplied by this kind of agriculture. They imagine a future where farmers can farm fruit and vegetables as well as minerals and metals.

The problems with traditional mining

This is particularly important because there is an increasing demand for certain materials. Nickel is a key element in stainless steel. It is also used in the green economy, to make batteries for electric cars, for example. But the traditional mining of nickel is not an environmentally friendly activity. Mining destroys vegetation in and around the mine. The soil that is dug up is easily eroded and often ends up washed into rivers and seas, causing damage to the local flora and fauna. Furthermore, there have been many cases of water and soil contamination caused by the chemicals used in the nickel mining processes. Mining other metals and minerals also presents similar problems. Furthermore, mining is a hard, dangerous job – miners are often involved in serious accidents.

Prospects for the future

None of these problems would exist in agromining. Scientists like Dr Baker believe that hyper-accumulating plants could even reduce the environmental costs of traditional mines. In fact, these plants could be grown on old, closed mines: they would extract the remaining metals left in the soil, stop erosion and begin reforestation. Also, agromining could be done in metal-rich soils that are toxic for normal agriculture. It could also be the perfect solution for bringing vegetation back to deforested areas. It would make agriculture possible in what are now poor, deserted areas and provide farming jobs to local populations. Agromining could also serve the medical industry, says Dr van der Ent. There are plants that collect zinc and selenium, for example, which can be used to make food supplements. Perhaps only this is old news: we already know we need to eat vegetables to obtain important metals and minerals. What might be new, in the future, is that we will be cooking and eating those farmed vegetables with cookware and cutlery partly produced with farmed metals.

USEFUL LINKS 1) Read more about agromining here: https://www.abc.net.au/news/2021-04-09/trees-that-bleed-metal-could-help-power-the-future/100051066 https://www.nytimes.com/2020/02/26/science/metal-plants-farm.html 2) Watch this interview with Dr Antony van der Ent talking about hyper-accumulating plants: https://www.youtube.com/watch?v=GcLH6WxkVkI 3) Here is an animated video explaining how and why some plants love nickel: https://www.youtube.com/watch?v=L89sLg4H4BA 4) How are metals extracted from plants? Here is a project of the Université de Lorraine explaining how it is done: https://life-agromine.com/en/388-2/ 5) Did you know that some plants can also purify the air, absorbing harmful pollutants? NASA did an interesting study to discover which plants are most effective at this: https://www.youtube.com/watch?v=lPNYdSZRSdg https://en.wikipedia.org/wiki/NASA_Clean_Air_Study

COMPREHENSION 1) Read the article and cross out the WRONG alternative (two answers are correct and one is incorrect). 1. Traditional mining includes

surface mining.
agromining.
underground mining.

2. Scientists like Dr Baker and Dr van der Ent want to

improve traditional mining.
find alternatives to traditional mining.
substitute excavators with plants to obtain metals.

3. Metal-loving plants have

roots that suck the metals out of the ground.
leaves that absorb metals from the air.
sap that contains metals.

4. Metal-rich soils are

perfect for a small number of plants.
toxic for most plants.
ideal only for macadamia plants.

5. Agromining scientists focus on nickel because

a very large number of metal-loving plants feed on nickel.
there is a great demand for nickel, for example, in the green economy.
nickel is environmentally friendly.

6. Mining can be a problem because

it harms local plants and animals.
it’s an expensive activity.
it can pollute water and soil.

7. Compared to traditional mining, agromining

requires just as much digging.
is less dangerous for the workers employed.
is less harmful for the environment.

8. According to scientists like Dr Baker, agromining can

clean old mines.
introduce farming where it was not previously possible.
replace traditional agriculture.

9. Agromining can produce

new jobs.
metal rich soils.
materials to make everyday objects.

10. Agromining is

already used on a large, industrial scale.
still in its infancy.
the potential solution to many problems.

VOCABULARY 2) Complete the sentences with the following words. Put the verbs and nouns in the right form, if necessary. cutlery * to scrape * roots * sap * stem * plot * to harvest * key * steel * cookware 1. ‘________’ can mean many things: the story of a book, a secret plan, or a small piece of land. 2. As a noun, the word ________ means a small object used for opening doors; as an adjective it means very important. 3. The ________ are the part of the plant that grows underground. 4. The ________ of a plant is the equivalent of the trunk of a tree. 5. The ________ is a liquid that brings nutrients to all parts of a plant. You can say that it’s the ‘blood’ of the plant. 6. Farmers are very busy in early Autumn when they ________ the fruit and vegetables they grew during the summer months. 7. ________ is a very strong metal, stronger than iron. 8. The utensils, pots and pans one uses to cook are called ________, whereas the utensils used for eating, such as forks, spoons and knives are called tableware or ________. 9. I fell and ________a knee. I need to disinfect it. GRAMMAR – Past simple and past continuous 3) Complete the sentences using the verbs provided. Use the past simple or the past continuous. 1. I ________ (to interview) Dr van der Ent while he ________ (to work) in his laboratory. 2. Dr Baker ________ (to discover) hyper-accumulating plants while he ________ (to do) research for the University of Melbourne. 3. I ________ (to watch) a documentary on agromining, when I ________ (to realize) how amazing plants really are. 4. I ________ (to see) Dr van der Ent on TV last night. He ________ (to talk) about the properties of macadamia trees. 5. The miner ________ (to mine) for gold, but he ________ silver instead. 6. I ________ (to listen) to the radio when I ________ (to hear) about agromining. 7. While I ________ (to plant) carrots in the vegetable garden, I ________ (to injure) my hand. 8. The scientist ________ (to speak), but nobody ________ (to listen). 9. I ________ (to cut) vegetables when Wendy ________ (to arrive). 10. I ________ (to feel) agitated, so I ________ (to prepare) myself a chamomile tea. SHORT ESSAY 4) What’s your relationship to plants? Do you have house plants? Do you like gardening? Do you like walking in nature? Do you like eating your greens? Describe. (60-80 words) 5) Read NASA’S list of air-purifying plants (https://en.wikipedia.org/wiki/NASA_Clean_Air_Study). Do you have any of them in your home, or are there any you would like to own? Describe them, say why you like them and where they are (or where you would put them) in your home. (60-80 words)

___ (Carlo Dellonte) (Image credits: Wikimedia Commons, Wikimedia Commons)

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Harvesting metals from plants

Mining plants

The problems with traditional mining

Prospects for the future