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Comparative study of nutrients and heavy metals in Rwandan macrophytes: Cyperus papyrus and Leersia hexandra


C. Kayirangwa
T. Muhizi
M.J.P. Mpatswenumugabo

Abstract

Macrophytes have been recommended to be naturally most efficient in water purification by fixing heavy metals and nutrients. This study  aimed at comparing both nutrient and heavy metal contents in two Rwandan wetland plants, Cyperus papyrus and Leersia  hexandra. Different plant parts and water samples were collected from Nyabugogo, Nyabarongo, Akanyaru and Akagera wetlands in Rwanda. Atomic Absorption Spectroscopy, Ultraviolet-Visible spectrophotometer and Flame Photometer were used to analyze the  presence of heavy metals and nutrients. Results from the study revealed that Nitrogen was the most abundant nutrient in water with  mean concentration of 9.160mg/mL, while Phosphorus was the least concentrated (0.160mg/mL) from all the sampling sites. However,  the highest concentration of plant nutrients in leaves was Potassium (26.67mg/g). On the other side, the highest concentration of heavy  metals in water was 40.2 mg/L for Fe in Nyabugogo site while its lowest concentration was found in Akanyaru with 10.05 mg/L. The  highest concentration heavy metal in plant was Fe (2.699mg/g) while the least concentrated was Pb (0.060mg/g). This study showed that   Leersia hexandra contains a high quantity of all heavy metals analyzed, therefore, a further investigation on Leersia hexandra should be  conducted prior to being used as key material in phytoremediation. 


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eISSN: 2707-7209