Sediment‑Macrophyte Interactions in Heavy Metal Contaminated Lakes: Insights into Bioaccumulation and Phytoremediation Potential

Abstract

Abstract Heavy metal contamination in freshwater systems has been extensively studied. However, many tropical ecosystems still lack baseline data on metal distribution and effective remediation strategies. Thus, this study investigated sediment-macrophyte metal dynamics, critical for assessing ecological risks and phytoremediation potential. Concentrations of five heavy metals (HM), namely Cadmium (Cd), Lead (Pb), Chromium (Cr), Copper (Cu), and Manganese (Mn) were analyzed in sediments and common macrophytes (Ludwigia erecta and Vossia cuspidata) from two municipal lakes in North-Central Nigeria. Field sampling was conducted from April to August 2022 in Tagwai and Old Gawu Lakes. Sediment and macrophyte samples were analyzed using standard protocols. Bioaccumulation factors (BAFs), Spearman correlation, and Principal Component Analysis (PCA) were applied to quantify metal uptake efficiency, assess sediment-plant metal relationships, and characterize variations in metal profiles across the lakes. Despite low sediment-based ecological risk (RI< 150), macrophyte bioaccumulation indicated notable HM bioavailability. Ludwigia erecta showed high Cd uptake in Old Gawu (BAF = 1.53) and elevated Pb and Cr bioaccumulation in Tagwai, while Vossia cuspidata accumulated Mn, Pb, and Cr above sediment levels (BAF > 1). These patterns demonstrate that Cd, Pb, and Cr remain bioavailable revealing a higher ecological concern than is reflected by sediment-based indices alone. These findings highlight species-and site-specific metal accumulation patterns and suggest that V. cuspidata holds greater potential for phytoremediation in multi-metal contaminated environments. The study emphasizes the importance of incorporating macrophytes into ecological risk assessments and management strategies for tropical lake systems.