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