The levels of lead (Pb) in water, sediment and a commercially important fish species (Chrysichthys nigrodigitatus) (Lacepède 1803) from Ologe Lagoon, Lagos, Nigeria

Abstract

The levels of lead (Pb) in water, sediment and a commercially important fish species, Chrysichthys nigrodigitatus were measured from April, 2007 to February, 2008 (spanning dry and rainy seasons) at three sampling sites- Morogbo, Otto and Imude in Ologe lagoon . The highest concentration (5.85+ 1.10 μg/l) of Pb in water was recorded in Otto (site nearest to vehicular traffic) in December (Dry Season) and the lowest concentration (3.13+ 0.72μg/l) was observed in Imude (site relatively unaffected by human activities) in June. The highest concentration (4.12+1.25 μg/g) of Pb in sediment was recorded in December (Dry Season) and the lowest, 0.05+0.01 μg/g was observe in April (Rainy season). Seasonal dynamics had no significant effect on the level of Pb in sediment (P > 0.05) but the concentration of Pb in the sediment of Otto (site nearest to vehicular traffic) was significantly greater than the other two sites (P < 0.05). Pb concentrations in Chrysichthys nigrodigitatus decrease with increase in fish weight. However, there was no significant (P > 0.05) correlation between Pb levels in fish tissues and their body weight. Although Pb level in water was below WHO standards, vehicular traffic had effects on sedimentary Pb level.

Keywords: Lead, Chrysichthys nigrodigitatus, Seasonal dynamics, vehicular traffic, Ologe lagoon, Nigeria