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In the present study, Brassica napus, a food plant, was grown for phytoextraction of selected heavy metals (HMs) from marble industry wastewater (WW) under oxalic acid (OA) amendment. The hydroponic experiment was performed under different combination of WW with OA in complete randomized design. Photosynthetic pigments and growth reduction were observed in plants treated with WW alone amendments. The combination of OA in combination with WW significantly enhanced the growth of plants along with antioxidant enzyme activities compared with WW-treated-only plants. HM stress alone enhanced the hydrogen peroxide, electrolyte leakage, and malondialdehyde contents in plants. OA-treated plants were observed with enhanced accumulation of cadmium (Cd), copper (Cu), and lead (Pb) concentrations in the roots and shoots of B. napus. The maximum concentration and accumulation of Cd in root, stem, and leaves was increased by 25%, 30%, and 30%; Cu by 42%, 24%, and 17%; and Pb by 45%, 24%, and 43%, respectively, under OA amendment. Average daily intake and hazard quotient (HQ) were calculated for males, females, and children in two phases of treatments in phytoremediation of metals before and after accumulation into B. napus leaves and stems. HQ of metals in the leaves and stem was < 1 before metal accumulation, whereas > 1 was observed after HM accumulation for all males, females, and children. Similarly, the hazard index of the three study types was found > 1. It was observed that the estimated excess lifetime cancer risk was of grade VII (very high risk), not within the accepted range of 1 × 10 -4 to 1 × 10 -6 . Based on the present study, the increased levels of HMs up to carcinogenicity was observed in the B. napus which is not safe to be consumed later as food., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Abstract\nKEY MESSAGE/HIGHLIGHTS\nNOVELTYWater contamination with metals poses significant environmental challenges. The occurrence of heavy metals (HMs) prompts modifications in plant structures, emphasizing the necessity of employing focused safeguarding measures. Cadmium (Cd), lead (Pb), and chromium (Cr) emerge as particularly menacing toxins due to their high accumulation potential. Increasing the availability of organic acids is crucial for optimizing toxic metal removal via phytoremediation. This constructed wetland system (CWs) was used to determine how oxalic acid (OA) treatments of textile wastewater (WW) effluents affected morpho-physiological characteristics, antioxidant enzyme activity, oxidative stress, and HM concentrations in Phragmites australis. Multiple treatments, comprising the application of OA at a concentration of 10 mM and WW at different dilutions (25%, 50%, 75%, and 100%), were employed, with three replications of each treatment. WW stress decreased chlorophyll and carotenoid content, and concurrently enhanced HMs adsorption and antioxidant enzyme activities. Furthermore, the application of WW was found to elevate oxidative stress levels, whereas the presence of OA concurrently mitigated this oxidative stress. Similarly, WW negatively affected soil-plant analysis development (SPAD) and the total soluble proteins (SP) in both roots and shoots. Conversely, these parameters showed improvement with OA treatments. P. australis showed the potential to enhance HM accumulation under 100% WW stress. Specifically, there is an increase in root SP ranging from 9% to 39%, an increase in shoot SP from 6% to 91%, and an elevation in SPAD values from 4% to 64% compared to their respective treatments lacking OA inclusion. The OA addition resulted in decreased EL contents in the root and shoot by 10%–19% and 13%–15%, MDA by 9%–14% and 9%–20%, and H2O2 by 14%–21% and 9%–17%, in comparison to the respective treatments without OA. Interestingly, the findings further revealed that the augmentation of OA also contributed to an increased accumulation of Cr, Cd, and Pb. Specifically, at 100% WW with OA (10 mM), the concentrations of Cr, Pb, and Cd in leaves rose by 164%, 447%, and 350%, in stems by 213%, 247%, and 219%, and in roots by 155%, 238%, and 195%, respectively. The chelating agent oxalic acid effectively alleviated plant toxicity induced by toxins. Overall, our findings demonstrate the remarkable tolerance of P. australis to elevated concentrations of WW stress, positioning it as an eco-friendly candidate for industrial effluent remediation. This plant exhibits efficacy in restoring contaminants present in textile effluents, and notably, oxalic acid emerges as a promising agent for the phytoextraction of HMs.HMs stress decreased the physiology and morphology of Phragmites australis L.OA improved the photosynthetic pigments and antioxidant enzymesHMs accumulation and bioavailability increased under OAPhragmites australis L. showed higher efficacy for textile effluent treatment under OAHMs stress decreased the physiology and morphology of Phragmites australis L.OA improved the photosynthetic pigments and antioxidant enzymesHMs accumulation and bioavailability increased under OAPhragmites australis L. showed higher efficacy for textile effluent treatment under OAThe adoption of ecological or nature-based approaches for treating textile industry wastewater poses significant challenges. Despite laboratory and field demonstrations showcasing the potential of macrophytes for remediating metal-polluted wastewater, this study investigates the Phragmites australis to address heavy metal contamination in wastewater.This research bridges this gap by presenting the outcomes of applying oxalic acid single and in combination with wastewater to Phragmites australis, focusing on the accumulation of cadmium, chromium, and lead from textile wastewater.The adoption of ecological or nature-based approaches for treating textile industry wastewater poses significant challenges. Despite laboratory and field demonstrations showcasing the potential of macrophytes for remediating metal-polluted wastewater, this study investigates the Phragmites australis to address heavy metal contamination in wastewater.This research bridges this gap by presenting the outcomes of applying oxalic acid single and in combination with wastewater to Phragmites australis, focusing on the accumulation of cadmium, chromium, and lead from textile wastewater. [ABSTRACT FROM AUTHOR]