Bioaccumulation of rare earth element lanthanum in pistia stratiotes (water lettuce) and oreochromis niloticus (nile tilapia) in artificial wastewater system

Abstract

Rare earth elements (REEs) are a series of chemical elements found in the earth’s crust that are vital to many modern technologies, including consumer electronics, computers, communications and clean energy technologies. However, during the production of REEs, the activity is susceptible in causing environmental contamination by discharging the REE industrial wastewater into the environment especially ponds, lakes and rivers. The REE wastewater containing Lanthanum (La) residue and other radioactive elements will be uptaken by the aquatic plants and freshwater fishs through bioaccumulation process. Therefore, this study aims to determine the effectiveness of the aquatic plant, i.e. Pistia stratiotes and freshwater fish (Oreochromis niloticus) as bioaccumulation agents of rare earth metals, especially Lanthanum (La) in REE artificial wastewater system. The study was carried out by subjecting P. stratiotes (water lettuce) and O. niloticus (Nile tilapia) to 4 levels of Lanthanum Chloride (LaCl3) treatments (i.e. 1, 3, 5 and 10 ppm) for 12 days in aquaponics artificial wastewater system. The samples were collected every two days and dried prior to digestion. The dried plant parts (root and leaf) and fish tissues (stomach and flesh) were acid-digested and then analyzed the REE metal (La) accumulation using the Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). Overall results showed REE (i.e. La) was accumulated in the highest amount in the stomach compared to other parts of the plant and fish tissues.