NewsGreen antidote

Green antidote

How cannabis plants are supposed to help cleanse contaminated soils in South Africa

A few kilometers west of Johannesburg, it is believed to have landed on another planet. Purple lakes, emerald-blue streams, huge orange-colored spoil heaps made of sand. Every now and then a rusted steel frame appears like an iron dinosaur: relics of a winding tower that once abseiled down elevators.

South Africa’s wealth has been gained here over the past 130 years, although only a small minority has benefited from it. But today everyone, especially the population living on the western outskirts of the metropolis, has to do with the toxic consequences of gold mining. The name of the largest South African township, Soweto, is composed of “South Western Township” and is sometimes only a stone’s throw away from the poisonous nightmare landscapes.

Highly toxic chemicals such as mercury, arsenic and cyanide were once – and in some cases still are today – used to extract gold. In addition, together with the precious metal, numerous heavy metals such as cadmium, lead, nickel and cobalt are extracted from the depths – sometimes even radioactive uranium is among them. In “Robinson See” near Randfontein, radioactive radiation was measured that was up to 40,000 times the normal value. “Hardly anyone is aware of the true extent of environmental pollution,” says Tiago Campbell, an environmental science student at Johannesburg’s Witwatersrand University.

Actually, the devastated landscape should be restored by the mining companies after the robbery of the natural resources. But they weren’t too strict about their obligations – or they went bankrupt before they could be called to account. The groundwater is now acidic like vinegar and radioactive dust, which causes cancer in humans, is blown off the spoil heaps. Tiago Campbell has decided to put an end to this grievance. And that is supposed to happen with the hemp plant “Cannabis sativa”, which among other things is due to marijuana.

Cannabis, also called “mop crop” (rag plant), is known for its cleaning power, known in specialist circles as phytoremediation. The plant has roots up to 2.5 meters deep, grows like weeds and absorbs toxic substances. Tiago Campbell has already planted them in the poisoned soil of the disused gold mines – they continued to grow cheerfully. The plant has already proven its cleaning powers in Chernobyl and in the Italian steel town of Puglia, where it absorbed the released dioxin. With cannabis sativa greening, even the lunar landscape in western Johannesburg could be brought back to life, Campbell is convinced: and at a fraction of the costs that would otherwise be incurred for the rehabilitation of landscapes.

Versatile fiber

Hemp has another advantage: it can be used in many ways. In addition to ropes, its fibers can also be used to make clothes and biological plastic: Houses are now even being built with hemp bricks. After all, cannabis is currently opening up a whole new future in South Africa: after it has been approved as a medicinal product, marijuana is also about to be approved as a relaxation drug in the Cape of Good Hope.

Tiago Campbell warns, however, against using his plants grown on toxic soils for such purposes: Their highly enriched active ingredients could prove to be “much too high”.

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