Water-based drilling muds (WBMs) used in oil and gas operations are a significant source of aquatic pollution due to their complex mixture of heavy metals, hydrocarbons, and chemical additives. Eichhornia crassipes (water hyacinth), a fast-growing aquatic macrophyte, has been widely studied for its phytoremediation potential. However, the biochemical and oxidative stress responses of E. crassipes in WBM-contaminated aquatic environments remain underexplored. This study investigates the morphological, physiological, and enzymatic responses of E. crassipes to varying concentrations of WBM to evaluate its remediation performance and stress tolerance. A six-week experimental study was conducted using six treatment groups exposed to 0%, 20%, 40%, 60%, 80%, and 100% WBM concentrations. Total dissolved solids (TDS) and electrical conductivity (EC) were measured at weeks 0 and 6 to assess ionic mobilization. Plant growth parameters (height and stem girth), chlorophyll content (SPAD units), and antioxidative biomarkers, including catalase (CAT), superoxide dismutase (SOD), and vitamin C (ascorbic acid), were analyzed in leaf, stem, and root tissues. Data were subjected to ANOVA with significance set at p < 0.05.n TDS and EC significantly increased across all WBM treatments post-exposure, indicating enhanced solubilization of drilling mud constituents. Plant height and stem girth exhibited concentration-dependent responses, with moderate WBM levels (40–60%) supporting partial adaptive growth, while extreme concentrations (100% and 20%) resulted in growth suppression. Chlorophyll content declined markedly in WBM-exposed plants, with the most severe reduction observed at higher contaminant loads. Catalase and SOD activities showed tissue-specific and concentration-dependent variations, with peak responses at 60–80% WBM in stems and roots, reflecting oxidative stress mitigation. Vitamin C accumulation exhibited a biphasic trend, with moderate WBM exposure stimulating ascorbate synthesis, while excessive contamination inhibited antioxidant capacity. Eichhornia crassipes demonstrates a nuanced phytoremediation response in WBM-contaminated aquatic systems, characterized by adaptive oxidative stress management and morphological plasticity. However, the plant's remediation efficacy is contingent on contaminant concentration, with high pollutant loads overwhelming its detoxification mechanisms. The findings emphasize the need for optimized phytoremediation strategies that consider dilution, exposure duration, and supplemental treatment measures to enhance the plant's performance in drilling waste management.

Keywords: Phytoremediation, Water-Based Drilling Mud, Eichhornia crassipes, Oxidative Stress, Antioxidant Enzymes, Catalase, Superoxide Dismutase, Vitamin C, Aquatic Pollution, Heavy Metals, Hydrocarbons, Environmental Remediation.

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Authors' contributions:

Both the authors made an equal contribution in the Conception and design of the work, Data collection, Drafting the article, and Critical revision of the article. Both authors have read and approved the final copy of the manuscript.