Pollution Status of Heavy Metals in Sediments, Water and Biota of Kalabari Creeks, Rivers State, Nigeria

Pollution status of five heavy metals (V, Cd, Pb, Ni, Cu, and Fe) were assessed in Kalabari creeks in the lower reaches of New Calabar River. Sediments, periwinkle (Tympanotonus fuscatus) and water were collected from June 2009 to April 2010 to cover dry and rainy seasons. Sediments were prepared by acid digestion using a mixture of concentrated perchloric acid HClO4, nitric acid (HNO3) and sulphuric acid H2SO4 in the ratio 1:3:1, while periwinkle samples were digested with aqua regia HN03 and HCl in the ratio of 1:3. Solvent extraction was used to preconcentrate water samples by using ammonium pyrrolidine dithiocarbamate (APDC) and methyl isobutyl ketone MIBK. Bulk Scientific Atomic Absorption Spectrophotometer (A.A.S) model 200A equipped with air-acetylene flame was used for analyses except for vanadium for which nitrous oxide flame was used. The result of ANOVA indicated that the heavy metals were significant at P<0.05 in all the samples, while results of t-test at 95% confidence limit indicated no significant difference in mean levels of heavy metals. However, similar trend of levels of heavy metals occurred in water, bottom sediments and periwinkle samples in both seasons. The mean levels of Cd and V were below detection limit (BDL) <0.001 in all the samples investigated. The result revealed that Fe, Ni, Pb and Cu were above FMENV and WHO standards for aquatic organisms. Thus, consumers of periwinkle of the River are at risk of being poisoned by these four heavy metals.