Industrial Hemp as a tool for phytoremediation

Since the uprising of industrialization, the environment has been exposed to a vast array of pollutants leading to air, water, and soil contamination. Among the most toxic pollutants encountered near industrialized areas, we have heavy metals, characterized by their low bio-solubility and biodegradability in the soil. A working solution to such a problem is the practice of phytoremediation, an alternative technique where plants are used for the uptake, retention, and overall elimination of contaminating agents in the soil. A desired characteristic of plants in phytoremediation is the usage of species that are not designated for later consumption. Fortunately, industrialized Hemp it’s a versatile plant used by humans to produce oils, fibers, and bio-energy fuels (i.e. bioethanol, biogas, biodiesel, and others). Also, Hemp is useful as a phytoextractor for phytoremediation of heavy metal-polluted soil due to its innate nature of high growth rate and abundant production of biomass. Furthermore, Hemp cultivation is characterized by its low cost and low environmental impact. Therefore, it is crucial to investigate the proficiency of Hemp as a phytoremediation agent given the economic and ecological benefits that come with phytoremediation.

A study led by Colorado State University tested the tolerance of Se (Selenium) in Hemp and its capacity of phytoremediation in Se rich soil. Selenium is a compound that is essential for humans at small concentrations but quite toxic at moderate concentrations. Thus, it is important to carefully select plants able to do phytoremediation on soils rich with Se. Also, it is a plus to select plants able to undergo biofortification when seeded in Se rich soil given the nutritional value that they will withhold. Herein, Hemp was shown to be quite tolerant of Se (based on biomass production) by being able to withhold up to 80µM of Se in the soil. Moreover, Hemp was found to benefit from these condition by showing higher growth rates, generating a higher concentration of antioxidants, and even showcasing herbivore protection. Additionally, concentrations of up to 80µM of Se did not have any significant effect on the cannabinoid and terpenoid profile of Hemp. Further, when compared to the specie Indian Mustard, the best Se phytoremediation species documented so far, Hemp appeared to be more resistant to Se and produced larger amounts of biomass.

In conclusion, the elimination of heavy metal pollutants is vital given the inevitable outcome of such pollutants ending up in natural sources used by the general population. Such an outcome could result in fatal casualties to both humans and even entire ecosystems.  When compared to physicochemical techniques available, phytoremediation is more cost-effective, eco-friendly, and efficient in the decontamination of soils. Specifically, Hemp has caught the attention of scientists not only for its ability to absorb pollutants in the soil but also for its ability to stop the migration of neighboring pollutants to nearby areas. Additionally, Hemp is capable of being used as both a phytoextractor and phytostabilizer to aid with the cleaning of polluted soil, and possess the particularity of containing small quantities of hazardous pollutants residues when the plant is harvest. Further, today’s society has made nuclear energy an alternative to solve the current elevated energy demands given its efficiency when compared to fossil fuels energy-based sources and natural/renewable energy-based sources (i.e. solar, wind, waves, etc.). Unfortunately, nuclear energy requires the use of radioactive elements like Uranium which leaves traces of hazardous residues that contaminate the environment. However, Hemp is currently studied as a plausible solution for phytoremediation of contaminated soils from pollutants as hazardous as Uranium. Thus, making Hemp a prime candidate for phytoremediation in the immediate future.

Khan A.G. (2020) In Situ Phytoremediation of Uranium Contaminated Soils. In: Shmaefsky B. (eds) Phytoremediation. Concepts and Strategies in Plant Sciences. Springer, Cham. https://doi.org/10.1007/978-3-030-00099-8_5

Stonehouse, G. C., McCarron, B. J., Guignardi, Z. S., El Mehdawi, A. F., Lima, L. W., Fakra, S. C., & Pilon-Smits, E. A. H. (2020). Selenium Metabolism in Hemp (Cannabis sativa L.) – Potential for Phytoremediation and Biofortification. Environmental Science and Technology, 54(7), 4221–4230. https://doi.org/10.1021/acs.est.9b07747

Yan, A., Wang, Y., Tan, S. N., Mohd Yusof, M. L., Ghosh, S., & Chen, Z. (2020, April 30). Phytoremediation: A Promising Approach for Revegetation of Heavy Metal-Polluted Land. Frontiers in Plant Science. Frontiers Media S.A. https://doi.org/10.3389/fpls.2020.00359