Many plants hold the capacity to uptake and absorb different chemicals and substances from the soil. Since the world has gone through and is currently going through vigorous industrialization, the chemical waste of factories and other chemicals is usually disposed of into water bodies. If plants are allowed to grow or flourish in these areas, then they are able to uptake many of the chemicals and then either these plants can be harvested, disposed of and they can help to clean up the environment and make it safer. The biggest benefit of Phytoremediation is that it is a low-cost option for cleaning the environment, it is every effective, and it also doesn’t produce any other harmful agent because the plants are controlled and planted only in areas that are at risk of being polluted.
In their paper titled ‘Phytoremediation of heavy metals—Concepts and applications’ by Hazrat Ali, Ezzat Khan, and Muhammad Anwar Sajad, the writers try to explain the serious problem of metal pollution. Heavy metals present in the soil lead to death and depletion of the microbes present naturally in the soil that decreases the fertility of the soil, making it less suitable for growth of any kind of vegetation. There are several methods of Phytoremediation according to them. These are ‘phytoextraction, Phyto filtration, phytostabilization, phytovolatilization and phytodegradation.’ (Ali et al., 871). Phytoextraction takes up the contaminants from the soil and translocates them to the shoots for being diverted to an exterior part of the plant. Phytofiltration is the process that removes pollutants from the water with the help of plants. Phytostabilization makes use of plants in contaminated soil to remove the pollutants. Phytovolatilization takes the contaminants from the soil into the plants for being released into the air and phytodegradation converts and degrades organic compounds from the plants with the help of enzymes. (Ali et al., 873). It is mostly the absorption and release of heavy metals from the soil such as Cd, Ni, Zn, As, Se, Cu, Co, Mn, Fe, Pb, Cr, U. The plant species mostly used are Brassica juncea that targets heavy metals. Trifolim spp also has the ability to extract heavy metals. Grasses are also preferred because of their faster growth rate. Species of maize and barley can also be used. The concentration factor differs according to the species. It is easier to trace and remove certain metals while others might be difficult to eradicate in a smaller period of time. (Ali et al., 881).
In their paper named ‘Phytoremediation: An Eco-Friendly Green Technology for Pollution Prevention, Control and Remediation’ the authors Tanveer Bilal Pirzadah, Bisma Malik, Inayatullah Tahir, Manoj Kumar, Ajit Varma and Reiaz Ul Rehman discuss the effects of herbicides, pesticides, fertilizers, hydrocarbons, trichloroethylene and fossil fuels that are the main soil and pollutants. It has been recorded even in the case of nuclear energy pollution; plants have been known to take up radioactive particles. (Pirzadah et al., 112). It is the process of taking up the plants’ biomass after they have taken up metals and pollutants from the soil. There is metal accumulating plant species that accumulate pollutants in the aerial plants of the plant such as the leaves. Hyperaccumulators are plants that have the ability to store metal pollutants even in the roots and leaves and shoots. Ni, Cd, Cu, Pb, Cr, Co, Zn and Mn by dry weight are metals found abundantly in polluted soils. (Pirzadah et al., 115). The highest pollutant absorption species include Oats, Indian mustard, Barley, Garden Bean, and Alpine penny-cress. The absorption rate of the plants includes the investigation on soil with nitrogen fertilizer containing Cu and Pb upon the Indian mustard and Amarnath. Cu uptake by the plants was 15.7-21.4 mg kg−1and was higher than lead uptake 12.7-16.9 mg kg−1. Pb uptake was 10.1-11.6 mg kg−1 and Cu was 11.6- 14.3 mg kg−1. Thus, the results showed that the species of plants were able to remove most of the lead and copper from the contaminated soil that contained the nitrogen fertilizer. (Pirzadah et al., 119).
In their paper ‘Plant growth and metal uptake by a non-hyperaccumulating species (Lolium perenne) and a Cd-Zn hyperaccumulator(Noccaea caerulescens) in contaminated soils amended with biochar’ by Frederic Rees, Cyril Germain, Thibault Sterckeman and Jean-Louis Morel, the authors explore the use of biochar for the curing of soil that has been contaminated with pollutants. The investigation for this was done by experimental means by employing a non-hyperaccumulating species of plant and a hyperaccumulator species grown in acidic and alkaline soils that had strains of Cd, Pb, and Zn and they had been added to wood-derived biochar. (Rees et al., 57).
The results of the experiment showed that the biochar that was added to the soil decreased the ease of the metals to reach the plants by increasing the acidity of the soil. Adversely the availability of the Ca, P and N was decreased to the plant. The results showed that the growth of the plant L. perenne increased, however, the concentration of the metals in the aerial parts of the plant was reduced to a large degree. (Rees et al., 59).This was due to the presence of the biochar in the soil. In the other soil with metals, with 0.5% increase in the dose of biochar, there was a relevant decrease in the production of the shoot. The N.caerulescens was a plant that was not majorly affected by the addition of biochar in the soil. However an increase in Cd uptake by 5% biochar was seen in both soils with the plants and Zn uptake was also recorded in the second soil. (Rees et al., 63).
Therefore, the result showed that the addition of biochar to the soil immobilized the metals, and many of them could not be taken up by the plants that were planted in that soil. This, however, can also lead to a deficiency in the uptake of essential nutrients needed by the plant to survive hence the hyperaccumualtors will then uptake the metals needed to be extracted from the soil. (Rees et al., 70).
References
Ali, Hazrat, Khan, Ezzat, Sajad Anwar Mohammad. (2013). ‘Phytoremediation of heavy
metals—Concepts and applications.’ Chemosphere. Science Direct. 869-881.
Pirzadah, Bilal, Tanveer, et al., (n.d). ‘Phytoremediation: An Eco-Friendly Green Technology for
Pollution Prevention, Control and Remediation.’ 111-122.
Rees, Frederic, et al., (2015). ‘Plant growth and metal uptake by a non-hyperaccumulating
species (Lolium perenne) and a Cd-Zn hyperaccumulator(Noccaea caerulescens) in contaminated soils amended with biochar.’ Springer International Publishing Switzerland. 57-73.
