Phytodegradation and Environmental Remediation

By Andrew Poitras

When oil spills, the effects can be observed across layers of biota. The quality of soil, groundwater, and drinking water are subject to the consequences of ecotoxicity1. Contamination represents a great potential harm to human and environmental health, with increased risks of respiratory and neurological diseases and various forms of cancer2.

Phytodegradation is an emerging technique that addresses contamination and restores the health and functionality of affected land. It is the process by which hazardous substances, such as crude oil or petroleum, are broken down into their base components3. These components are then incorporated into the plant’s tissue and contribute to the overall growth of the organism. This function remediates the immediate area by degrading the contaminant surrounding the plant3.

Certain species of plants sequester organic hydrocarbons found in crude oil and mitigate the spread of chemicals. The root system of the non-perennial grass species Miscanthus, for example, uptakes and degrades inorganic and organic contaminants and facilitates the contaminant’s degradation4. Miscanthus adapts to various climates and has a strong resistance to abiotic stressors, which can arise from contaminated soils. Planted into the target area, trace elements and contaminants collect in the roots and stems; once the plants are saturated, they can be harvested as biomass and properly stored to prevent re-entry of contaminants into the ecosystem5.

Aquatic contamination can also be remediated by wetland plants. Scirpus grossus absorbs and metabolizes organic compounds from diesel-contaminated water6. Once metabolized, these volatile organic hydrocarbons are degraded, then harmlessly transpired through the leaves. Scirpus grossus’s ability to withstand large concentrations of diesel in contaminated water make it an ideal remediator6.

The rate at which uptake occurs depends on the health and efficiency of the plant, and there are techniques to boost these factors7. An example is supplementation with humic acid, a water-soluble compound composed of molecular groups which assist uptake. Humic acid is suggested to improve microbial activity in the rhizosphere and improves the health of the plant by increasing its overall uptake ability and efficiency8.

Understanding the long-term implications of oil contamination is paramount when considering a remediation strategy. Because phytodegradation is an organic and passive process, the contamination is progressively halted at the source, and environmental harm is decreased9. Contamination of volatile hydrocarbons in media represent a huge threat to the health of ecosystems and human communities. Miscanthus and Scirpus grossus are some of the many plants that offer organic solutions to these problems. Supplementation with treatments such as humic acid ensures efficiency of the breakdown process. These means serve to naturally remediate and prevent the spread of harmful contaminants.

References:

1 Reaser DF. (2018). Oil spills. Salem Press Encyclopedia.

2 Reports from Nanjing Agricultural University Advance Knowledge in Cancer Risk (Contamination and health risk assessment of PAHs in soils and crops in industrial areas of the Yangtze River Delta region, China). (2017). Obesity, Fitness & Wellness Week.

 3 STONE AB. Phytoremediation Plants Clean Contaminated Soil. (2017). Countryside & Small Stock Journal. 101(5):24.

4 Florien Nsanganwimana. Bertrand Pourrut. Michel Mench. Francis Douay. (2014). Suitability of Miscanthus species for managing inorganic and organic contaminated land and restoring ecosystem services: A review. Journal of Environmental Management. Volume 143, Pages 123-134. ISSN 0301-4797,

5 Angela Dorhman. Bradley Rowe. Effect of Watering Regimen on Chlorophyll Fluorescence and Growth of Selected Green Roof Plant Taxa. (2006) HortScience December vol. 41 no. 7 1623-1628

6 Israa Abdulwahab Al-Baldawi. Siti Rozaimah Sheikh Abdullah. Nurina Anuar. Fatihah Suja. Idris Mushrifah. (2015). Phytodegradation of total petroleum hydrocarbon (TPH) in diesel-contaminated water using Scirpus grossus. Ecological Engineering. Volume 74. Pages 463-473. ISSN 0925-8574

7 Soyoung Park. Ki Seob Kim. Jeong-Tae Kim. Daeseok Kang. Kijune Sung. Effects of humic acid on phytodegradation of petroleum hydrocarbons in soil simultaneously contaminated with heavy metals. (2011). Journal of Environmental Sciences. Volume 23. Issue 12. Pages 2034-2041. ISSN 1001-0742

8 Maji D. Misra P. Singh S. Kalra A. Humic acid rich vermicompost promotes plant growth by improving microbial community structure of soil as well as root nodulation and mycorrhizal colonization in the roots of Pisum sativum. (2017). Applied Soil Ecology. 2017;110:97-108. doi:10.1016/j.apsoil.2016.10.008.

9 Xiaoxue Wang. Ningfeng Wu. Jun Guo. Xiaoyu Chu. Jian Tian. Bin Yao. Yunliu Fan. (2008). phytodegradation of organophosphorus compounds by transgenic plants expressing a bacterial organophosphorus hydrolase. Biochemical and Biophysical Research communications. Volume 365. Issue 3. Pages 453-458. ISSN 0006-291X

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