Ability of Urtica dioica L. to adsorb heavy metals (Pb, Cd, As, and Ni) from contaminated soils

Abstract

ABSTRACT Landfill leachate contains heavy metals that contaminate water and soil near the landfill site. Phytoremediation is a process of decontaminating soil or water by using native plants to adsorb and accumulate or break down pollutants. This study aimed to evaluate absorption and accumulation of heavy metals from simulated landfill soil by nettle. Nettle seeds were collected from the Tonekabon landfill site and planted in 243 pots. After reaching the 6-leaf stage, the plants were exposed to three concentrations of four heavy metals (Pb, Cd, As, and Ni) during the growing season. An atomic absorption spectrometer was used to measure the concentrations of the heavy metals in nettle plants and the morphological features of nettle fibers. The results showed that increases in the concentrations of the heavy metals in the soils led to their higher concentrations in all organs of the nettle plants (Pb> Ni> Cd> Ar), and larger quantities of the heavy metals were accumulated in the aerial parts of the plants. In parallel with this result, the dry weights of stem, leaf and root, and leaf area index also decreased. Values of TF> 1 and BAC <1 in plant organs showed the ability of nettle to accumulate more heavy metals when they were present at higher concentrations in the soil. Bioremediation using native plants for removal of heavy metals from soil and their accumulation in these plants is a low-cost and environmentally friendly technology. Nettle is a plant that grows wild in the landfills in northern Iran and, due to its ability to accumulative heavy metals in its organs, is a suitable plant species for their removal from soil.