Accumulation of Heavy Metals by Some Aquatic Macrophytes in Two Streams along the Tiko-Douala Highway, Cameroon

Aims: This study was aimed at determining the ecological health of two roadside streams across the Tiko-Douala highway, Cameroon, and investigating the phytoremediation potentials of dominant aquatic macrophytes within these streams.

Study Design: Water, sediments, and aquatic plant samples were collected from Camp 7 and Moqouo streams, and analyzed for ammonium nitrogen, nitrate nitrogen, phosphates, magnesium, cadmium, and lead, including other relevant water quality parameters.

Place and Duration of Study: In the Life Science Laboratory of the University of Buea, and Soil and Water Laboratory of the University of Dschang, Cameroon between June 2021 and June 2022.

Methodology: Six water samples and six sediment samples were collected per stream, and two of the most dominant plant species (Pennisetum purpureum Schumach (Poaceae) and Dicanthelium clandestinum L. (Poaceae) from Camp 7, Commelina benghalensis L. (Commelinaceae) and Oldenlandia corymbosa L.(Rubiaceae) from Moqouo stream) were collected for heavy metal analysis. Heavy metal concentration and bioaccumulation factors were determined for each plant.

Results: High concentrations of phosphates were recorded in Camp 7 (1.19 mg/L) and Moqouo (2.17 mg/L) streams. Dissolved oxygen levels were 0.69 mg/L and 0.80 mg/L in Camp 7 and Moqouo respectively. Sediment cadmium levels ranged from 0.33± 0.02 to 0.63± 0.16 mg/kg, and lead ranged from 0.34 ±0.03 to 0.37 ± 0.12 mg/kg in Moqouo and Camp 7 respectively.

Conclusion: The Mouqouo and Camp 7 streams are rich in phosphates and thus not suitable for drinking and irrigation. Cadmium and lead in stream water were within the permissible limits but sediments contained higher concentrations than water and therefore they could be released gradually into the water column. All plants in the study except (Dicanthelium cladestinum) accumulated cadmium and lead, and could be potential plants for the phytoremediation of these metals.