Phytoextraction of Nickel from Contaminated Soils by Employing Bioamendments

Abstract

Phytoremediation is an emerging technology in which the plants are employed to absorb and bio-magnify elements from polluted environments and metabolize them into various biomolecules. Once inside the plant, chemicals can be stored in roots, stems, or leaves or changed into less harmful chemicals within the plant or changed into gases that are released into the atmosphere. A number of amendments are used either to mobilize or immobilize heavy metals in soils. The basic principle involved in the mobilization technique is to release the metals into soil solution, which is subsequently removed by plants. In contrast, in the case of the immobilization technique the metal concerned is removed from soil solution either through adsorption, complexation and precipitation reactions, thereby rendering the metals unavailable for plant uptake and leaching to groundwater. In the present study, a pot experiment was conducted with marigold to determine the effect of different bio amendments such as farmyard manure, composted poultry manure, press mud compost and prosopisbiochar on phytoextraction of Ni from contaminated soil. The experiment was carried out by using completely randomized design and the results were statistically scrutinized. Of marigold, the highest Ni content (103 pg g 1) in the above ground biomass was found in the plants grown on soil amended with press mud compost (T4) followed by composted poultry manure (T3). In contrast, the root biomass of marigold had significantly higher Ni content due to the application of farmyard manure (T2) followed by prosopisbiochar (T5). There was a positive correlation between the Ni uptake by marigold and bioavailable fractions of Ni in soil. However, marigold showed greater potential in tolerating and accumulating higher concentration Ni and therefore could be employed along with bioamendments for phytoextraction of Ni from contaminated soil.