A study of the levels and seasonal variation of heavy metal contamination of E. radiata from creeks in Burutu area of Delta state, Nigeria

Abstract

Levels of heavy metal concentrations in tissues of Egeria radiata from Obotebe and Gbekobor Creeks in Burutu 
Local Government Area were investigated. E. radiata samples were collected fortnightly for 12 months in 2008. The 
soft tissues of E. radiata were extracted, weighed and dried in oven for three days at 600C. Ten grams of the dried 
samples were homogenized and digested before analysis using the atomic absorption spectrophotometer (AAS) to 
determine levels of heavy metals such as (copper, lead, manganese, cadmium, mercury, chromium and nickel). The 
results obtained showed that tissues of E. radiata from the creeks were contaminated with heavy metals. The mean 
concentrations of heavy metals in tissues of E. radiata followed an increasing sequence of Hg < Cd < Cr < Mn < Pb < 
Cu < Ni. Heavy metal concentrations in tissues of E. radiata were higher but were not significant in the dry season 
than in the rainy season. Levels of heavy metals in tissues of E. radiata were found to be below the FAO/WHO 
acceptable limits of heavy metal pollution in fishes and shell fish. Mean levels of lead (Pb), manganese (Mn) and 
Cadmium (Cd) were found to be higher than world standard but not significant. Nickel were significantly lower than 
world standard. There is a need for constant monitoring of levels of heavy metals in the area of study in order to 
forestall any significant rise in their levels.