Title: Impact of Co-Exposure to Cadmium and Lead on Eichhornia crassipes: Bioaccumulation and Physiological Alterations
Authors: Maria Onyemowo Ochigbo-Ejembi ,, Esther Bosede Adelanwa , Aisha Oiza Musa , Victor Ochigbo , Regina Anya Otogo , and Mathias Ahii Chia ,,
Volume: 8
Issue: 11
Pages: 135-146
Publication Date: 2024/11/28
Abstract:
Heavy metal contamination poses a significant global environmental challenge that threatens aquatic ecosystems, agriculture, and human health. In contaminated aquatic environments, disruptions to ecosystem dynamics negatively affect flora, fauna, and microbial life. Existing research on heavy metal bioaccumulation often overlooks the concurrent uptake of multiple metals at various concentrations. This study explores the simultaneous bioaccumulation of cadmium (Cd) at concentrations of 0.01, 0.50, and 1.00 mg L-1 and lead (Pb) at 0.05, 1.00, and 1.50 mg L-1 by Eichhornia crassipes. We monitored the physiological responses of these macrophytes over a 15-day exposure to these metals. The study recorded a significant increase in Pb concentration within the plant tissue on days 9 (0.044 ± 0.01 mg kg-1) when 1.00 mg L-1 Pb combined with 0.50 mg L-1 Cd and 12 (0.043 ± 0.03 mg kg-1) at 1.50 mg L-1 Pb combined with 1.00 mg L-1 Cd, and a consistent increase in Cd accumulation throughout the exposure period. Chlorophyll a, chlorophyll b, and total chlorophyll levels significantly decreased following Cd and Pb metal exposure. Additionally, peroxidase (POD) activity markedly increased by day 9 across all metal concentrations following treatment with Pb and Cd, except in a few cases with decreased activity. In contrast, catalase (CAT) activity showed significant fluctuations during the study period. These findings indicated that E. crassipes can take up high levels of Cd and Pb from contaminated waters, initially boosting antioxidant enzyme activities, such as CAT and POD. Nonetheless, prolonged exposure may overwhelm these defense mechanisms, leading to potential cellular damage.