- The Growth Op @growthop
Cannabis holds promise for cleaning up toxic mines and industry sites
Those interested in cleaning up the toxic legacy of mines and industries in South Africa may have happened upon an unlikely cleanser: cannabis.
According to the Mail & Guardian, industrial cannabis — industrial hemp is a class of cannabis sativa grown for industrial or medicinal use — is now on the radar of some as a promising tool to remove toxic heavy metals from mining and industry wastelands in and around the country’s largest city, Johannesburg.
Remnants of yesteryear include high concentrations of arsenic, cadmium, cobalt, copper, zinc, and uranium, the Mail & Guardian quotes Mariette Liefferink, chief executive of the Federation for a Sustainable Environment, as saying.
Among the group’s objectives is to protect and promote environmental health and functional ecosystems for future generations and facilitating remediation of existing environmental degradation, the website notes.
Tiago Campbell, an environmental science master’s student at the University of the Witwatersrand, is researching cannabis as an instrument to scrub toxic land, according to the Mail & Guardian. Though the scale of the job is not yet known, Campbell, nonetheless, said cannabis has phytoremediation properties that can allow it to remove toxins and help render industrial pollutants harmless.
ScienceDirect cites a study that defines phytoremediation as “the use of green plants to treat and control wastes in water, soil and air.” While promising, calling the method “an important part of the new field of ecological engineering,” the information does add that the approach’s success to date has revolved around lower concentrations of wastes.
“Applications of wetlands, grasslands, crops, and tree plantations have been successful for a variety of wastes, usually present in low concentrations that are not acutely phytotoxic,” it points out.
Cannabis may also serve as a heavy metal hyper-accumulator, Campbell told the Mail & Guardian. That means the plant potentially punches above its weight by absorbing toxins at higher concentrations than its growing medium.
A study published last year in the International Journal of Phytoremediation reports that phyto-tolerant or phyto-accumulator plants can survive on contaminated soils and “reduce the toxicity.”
But the phytoremediation properties are not the only things that weed has going for it. It also has a rapid growth rate, high-stress tolerance, a deep and probing root system and can store carbon dioxide.
Indeed, hemp may be outpaced only by bamboo. “Hemp and bamboo both grow easily and prolifically,” reports Bambu Batu, The House of Bamboo. Additionally, both crops “grow very easily without pesticides and herbicides,” it notes.
With all these attributes, Campbell suggests that cannabis can be put to good use for the environment. “It’s a weed. It is an opportunistic plant that will take advantage of its environment and that gives it resistance to a contaminated soil source,” Campbell told the Mail & Guardian.
Clearly, the cannabis produced in these areas could not be used for medicinal or recreational use. /
Clearly, the cannabis produced in these areas could not be used for medicinal or recreational use. But Campbell reportedly noted this his research shows the heavy metals in the plants can be extracted to unsafe levels and then made into other products, such as bioplastics, textiles and hempcrete for construction, per the Mail & Guardian.
Hempcrete has been gaining profile, including a U.S. couple that is now offering the Traveler, a DIY cabin that the two have been building and designing with the mix of hemp hurd, lime and sand mix for the past three years.
Here at home, Alberta-based Just BioFiber is also working with hempcrete. Company founder Mac Radford previously told Bloomberg two years ago that the company is struggling to keep up with demand.
Information from Calgary-based Earthmaster Environmental Strategies and Ontario’s University of Waterloo notes the former has successfully remediated both petroleum hydrocarbon and salt-impacted sites in seven Canadian provinces and territories.
Areas of interest for remediation have been worldwide, including in B.C. One study released more than a decade ago, for example, considered metal contaminated soil in temperature humid regions of the province.
And back in 2008, after farmers in the Taranto region of Italy discovered a toxic chemical in their land, they decided to do something to clean up things. That cleaning involved planting a variety of cannabis to reverse the harm wrought by a nearly steel plant.
A study, this one from the late 1990s, was cited in a U.S. Environmental Protection Agency report with respect to cost. “At appropriate sites, the cost of applying phytoremediation techniques may range from half to less than 20 per cent of the cost of using physical, chemical, or thermal techniques.”
More than two decades later, authors of the 2020 study looking at the promise and potential of in situ non-phytoremediation strategy concluded the review “identifies the urgent need to conduct field-scale application of this strategy and use it as potential tool for re-establishing plant cover and population diversity during restoration of derelict land post-industrial/mining activities.”
And a study released in 2003 considered the overall impact. “The possibilities of growing hemp easily in different climates and using its biomass in non-food industries can make heavy metal contaminated soils productive. This means economical advantage along with a better quality of soil.”
Subscribe to Weekend Dispensary, a new weekly newsletter from The GrowthOp.