Phytoremediation and Growth Response of Common Duckweed (Lemna minor L.) to Copper and Chromium in Market Dumpsite Leachate: A Case Study from Maiduguri, Nigeria

Background and Objective: The prevalence of heavy metals in water poses a serious environmental challenge due to their toxicity, non-biodegradability, bioaccumulation, and carcinogenic potential, threatening both human health and aquatic ecosystems. This study aimed to evaluate the phytoremediation potential of the floating aquatic plant, duckweed (Lemna minor L.), for removing copper (Cu) and chromium (Cr) from dumpsite leachate. Materials and Methods: Lemna minor was exposed to varying concentrations of dumpsite leachate (0, 25, 50, 75, and 100% v/v) for 14 days. Physicochemical parameters of the leachate, including pH, electrical conductivity (EC), total dissolved solids (TDS), salinity, oxidation-reduction potential (ORP), and chemical oxygen demand (COD), were measured. Plant growth responses, including frond number, fresh weight, relative growth rate, and leaf pigmentation, were recorded. Statistical analyses were conducted to determine significant differences (p<0.05) across treatments. Results: At 50% v/v leachate, L. minor significantly reduced Cu by 42.2%, Cr by 25.3%, EC by 42.4%, TDS by 37.4%, salinity by 37.4%, ORP by 61.9%, and COD by 17.8%, while pH increased from 7.1 to 9.5. Higher leachate concentrations (100% v/v) caused significant decreases in frond number, biomass, relative growth rate, and pigmentation, indicating stress. Conclusion: Lemna minor can effectively tolerate and remediate up to 50% v/v of dumpsite leachate, highlighting its potential for phytoremediation of heavy-metal-contaminated waters. Further research is recommended to optimize environmental and ecophysiological conditions to enhance its remediation efficiency.