Bioaccumulation of heavy metals (Cu, Zn, Fe) in freshwater snail (<i>Pila ovata</i>; Oliver 1804) from Ikpoba River of Southern Nigeria

Abstract

In this study, the levels and bioaccumulation behaviors of copper, zinc and iron were determined in various body organs, viz: viscera and shell of freshwater snail, Pila ovata (Oliver 1804) collected from the upper and lower catchments of Ikpoba River, southern Nigeria. Heavy metal concentrations in snail and sediment samples were measured using an atomic absorption spectrophotometer. The mean concentrations (µgg^-1) of Cu, Zn and Fe in the snail were estimated to be as follow, 4.56 – 6.71, 35.35 – 77.09 and 1257.21 – 1762.59, respectively. This study showed that under natural conditions, P. ovata is capable of bioaccumulating trace essential metals to elevated levels especially Fe and Zn up to 10 times higher than that found in the sediment. The accumulation pattern was strongly correlated with the amount of trace metals in the sediments. Bioaccumulation of Cu, Zn and Fe varied between the viscera and the shell. The viscera had the highest concentrations (µgg^-1) of all metals than the shells; Cu, 2.03 – 5.8 (Viscera), 0.05 – 3.30 (Shell), Zn, 23.64 – 45.02 (Viscera), 1.87 – 15.15 (Shell) and Fe, 360.33 – 1526.59 (Viscera), 83.99 – 373.93 (Shell), which suggest that ingestion may be the main uptake route of these essential metals. A holistic biomonitoring approach is therefore proposed for these impacted areas to guide regulators in a direction of improvement.

Keywords: heavy metals, bioaccumulation, freshwater snail, sediment, Ikpoba River

Journal of Aquatic Sciences Vol. 21(1) 2006: 23-28