Oxalic acid-assisted phytoextraction of heavy metal contaminated wastewater through Lemna minor L

Abstract

The present research was carried out to investigate the performance of oxalic acid (OA) through Lemna minor L. (duckweed) in the phytoextraction of lead (Pb) from metal contaminated water. Zero, 100 μM, 250 μM, and 500 μM Pb concentration and combinations with 2.5 ml of OA were provided to the plants in the form of solution after defining intervals. Continuous aeration was provided to the plants and kept a pH level at 6.5. Results from this research depicted that increasing concentration level of Pb inhibited the overall plant growth, biomass, frond area, chlorophyll, and antioxidant enzyme activities like peroxidase (POD), superoxide-dismutase (SOD), catalases (CAT), and ascorbate-peroxidase (APX). Moreover, Pb stress enhances the concentration, hydrogen peroxide, malondialdehyde, and electrolyte leakage substances in plants. Furthermore, the addition of OA alleviated the Pb-induced toxicity in the plants, increasing the Pb accumulation and its endorsement in the L. minor. The OA addition increased the Pb accumulation in plants at 0, 100, 250 and 500 μM. At higher concentration, Pb showed harmful effect as related to the other low doses. Under the application of OA, Pb higher accumulation and concentration in L. minor were measured, which showed that it could be the most suitable plant for the phytoextraction of lead-contaminated soil and wastewater.

Keywords: Biomass; Lead; Lemna minor L.; Oxalic acid; Phytoextraction; Superoxide-dismutase.