Abstract
Extensive usage of heavy metals (HMs) in chemical reactions and processes eventually contaminate the environmental segments and is currently a major environmental concern. HMs such as cadmium (Cd), copper (Cu), lead (Pb), chromium (Cr) and nickel (Ni) are considered the most harmful pollutants as they have adequate potential of bioaccumulation. The current research was carried out to assess the HMs toxicity of textile and tannery wastewater and effect of acetic acid (AA) on phytoextraction of HMs by duckweed (Lemna minor L.) in a hydroponic system. Plants were treated with different treatments having different hydroponic concentrations of AA (5 and 10 mM) and textile and tannery effluents, where these two effuents were equally mixed and then diluted with good quality water with different ratios (25, 50, 75, and 100%) along with three replications of each treatment. Results were recorded for growth attributes, chlorophylls, antioxidant enzymes, electrolytic leakage, reactive oxygen species and HMs accumulation in plants. HMs accumulation disrupts the growth parameters, chlorophyll contents and carotenoids contents along with increased activities of antioxidant enzyme such as catalases (CAT), superoxide dismutase (SOD), peroxidases (POD) and ascorbate peroxidase (APX). Addition of AA in the hydroponic experimental system significantly improves the antioxidant defense mechanism and alleviated the HM induced toxicity in plants. Cr, Cd, Pb, Cu and Ni concentrations were maximally increased up to 116 & 422%, 106 & 416%, 72 & 351%, 76 & 346%, and 41 & 328% respectively under AA (10 mM) application. The results revealed that duckweed can be applied as potential phyto-remedy to treat industrial wastewater.
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•Various industrial wastewater dilutions differentially affected biomass of Lemna minor.•Cd, Cr, Pb, Cu, and Ni concentrations increased in plants with increasing concentrations in industrial wastewaters.•Acetic acid enhanced the biomass of plants under industrial wastewater irrigation.•Acetic acid increased metal accumulation in plants with industrial wastewater treatments.