Actually, Metal Does Grow on Trees

Believe it or not, some plants are actually in love with metal. These plants are referred to as hyper-accumulating plants because they absorb toxic but valuable metals from the soil and are able to collect them in their sap. Their roots are basically a magnet that attracts and craves metals, usually nickel. If the stems of these plants are cut open, they produce a neon blue-green sap that actually contains one-quarter nickel. They absorb nickel at an extraordinarily high level.

Scientists have researched nickel-absorbing plants for hundreds of years. The “father” of modern mineral smelting, George Agricola, started the research 500 years ago. In the 16th century, he wrote, “If you knew what to look for in a leaf, you could deduce which metals lay in the ground below.” Alan Baker, a botany professor at the University of Melbourne, has researched the relationship between plants and their soils since the 1970s. Another scientist, Rufus Chaney, an agronomist at the U.S. Department of Agriculture, invented the word “phytomining” in 1983. Phytomining refers to extracting materials from hyper-accumulating plants. Dr. Baker helped start the first phytomining trial in Oregon in 1996.

Nickel is very important for our everyday use. Nickel is crucial in making stainless steel and batteries for electric vehicles. It is also a vital component in renewable energy technology. However, despite all its pros, there are also cons. Nickel is toxic to plants and humans in larger doses. When found in the soil, it either makes the plants surrounding the area adjust or it kills them. When nickel is mined and processed, it can also destroy the land and leave a mess.

Hyper-accumulating plants are an ecological choice to help boost the nickel industry. There’s no need to genetically modify or selectively breed to increase the plants’ level of absorption. As of now, there are at least 65 types of nickel-absorbing plants. Phytomining may become more common in places with larger quantities of nickel in the soil, such as Indonesia and the Philippines, which are the world’s largest nickel producers. Nickel isn’t the only metal these hyper-accumulators are “in love” with. Some of these plants absorb cobalt, zinc, and similar metals.

There are many ideas about how to use hyper-accumulators to increase mining revenue and decrease pollution. A great idea on how to reduce pollution is to plant hyper-accumulators in abandoned mine areas in order to decrease the level of pollution that usually goes into the waterways.

These plants can also collect the remaining nickel from the abandoned mine in order to make some extra revenue miners might not have been able to get the first time around. This increases the amount of money that goes into the industry, boosting the economy.

The use of hyper-accumulating plants may someday be essential in order to decrease pollution caused by mining certain metals. Currently, the most common way of extracting nickel costs millions of dollars and leaves acidic waste behind. Using hyper-accumulators will only cost a fraction of traditional mining and decrease the acidic waste as well. Planting hyper-accumulators in the same field as other plants will be very beneficial in the future as they will absorb the nickel in the soil, making it more fertile for other plants.

The future goal of phytomining is to make it an industry that is as common as growing coffee and coconuts. Small farmers could grow hyper-accumulators on metal-rich soil for six to twelve months, and collect roughly 500 pounds of nickel citrate, which can be worth thousands of dollars. Mining companies will benefit as they are collecting metal from the farmers. It would be a win-win situation and would help the economy.

[Sources: The New York Times; Associated Press]

This is a fascinating article. Great job, Valeria! – Shoko MiyagiUW-Madison (2020-07-21 09:27)