Accumulation and Phytoremediation Potentiality of Trace and Heavy Metals in Some Selected Aquatic Plants from a Highly Urbanized Subtropical Estuary

Abstract

The global concern over trace and heavy metal contamination in aquatic environments necessitates the development of effective remediation strategies. Using aquatic plants for heavy metal removal is a relatively economical and sustainable technology worldwide. This study involved collecting sediment and aquatic plant samples (Acanthus ilicifolius, Typha elephantina, and Cynodon dactylon) from a highly urbanized estuary to analyze metal concentrations in sediment, assess ecological risks, and explore the phytoremediation potential. Trace and heavy metals were detected using Energy Dispersive X-ray Fluorescence Spectroscopy (EDXRF). The sediment metal concentrations were found in decreasing order of Fe, Ti, Mn, Rb, Zr, Zn, Sr, Cu, Co, and As. Fe, Sr, and As concentrations were below certified values, whereas Cu, Zn, and Rb exceeded them. Cumulatively, the pollution load index (PLI) values were close to 1 (0.845), indicating that the study area is likely experiencing metal pollution. The Contamination Factor (CF) values, ranging from 1 to 3, indicated a moderate degree of sediment pollution for Ti, Mn, Cu, Zn, and Rb. The Enrichment Factor (EF) values similarly showed moderate enrichment for these metals, with Cu exhibiting the highest degree of enrichment. Ecological risk assessment highlighted the only metal, Cu, as posing the greatest risk among the studied metals. In terms of phytoremediation potential, the bioconcentration factor (BCF) followed the decreasing order of C. dactylon > A. ilicifolius > T. elephantina for most metals, with low BCF values (<1) indicating low accumulator potential. However, the translocation factor (TF) values for Zn (1.464) and Rb (1.299) in A. ilicifolius species were greater than 1, indicating low accumulation potential but hyper-metabolizing capabilities, allowing the plant to accumulate metals in its aerial parts, making it effective for phytostabilization.