An investigation on Bioaccumulation of Heavy Metals and Radionuclides in Sonneratia caseolaris, a mangrove grown in Sri Lanka

Abstract

 Due to untreated industrial effluents and agrochemical discharges, many aquatic ecosystems in lagoons and estuaries are been polluted with heavy metals and radionuclides. Present study was designed to investigate the absorption and deposition of metal elements and radionuclides by Sonneratia caseolaris, a mangrove grow in lagoons and estuaries in Sri Lanka. It is a plant which is consumed routinely by Sri Lankan folks as a food, beverage as well as a medicine. Soil samples and different parts of the plant Sonneratia caseolaris grown in the Maadu Ganga estuary were collected. X ray Fluorescence Spectroscopy and High purity Germanium detector were used to analyze metal elements and radionuclides levels in samples respectively. According to the obtained results, sediment of the area is polluted with elements such chromium, lead, zinc and arsenic, but it is not polluted with any artificial or naturally occurring radionuclide. The results indicated that, the absorption and deposition of metal elements in different parts of the plant is independent of the sediment concentrations. Therefore, despite of the polluted sediment, there is no significant bioaccumulation of metal elements in the plant Sonneratia caseolaris. The bioaccumulation of naturally occurring radionuclide in different parts of the plant occur only in moderate level. Therefore, the results of the present study reveals that the routine consumption of the parts of the plant Sonneratia caseolaris is not harmful, in the aspect of heavy metals as well as radionuclides.