Inorganic Ion Levels of Soils and Streams in some Areas of Ogoniland, Nigeria as Affected by Crude Oil Spillage

The inorganic ion concentrations of soils and streams in the three locations (Yorla, Zaakpon and Goi) in Ogoniland,Nigeria affected by crude oil spillage were investigated. In general, inorganic ion concentrations of polluted soilsand streams varied significantly (p = 0.05) from those of unpolluted soils and streams. Anions such as nitrate (NO ₃ ^- ), sulphate (SO ₄ ^2- ) and chloride(Cl^-) showed significantly (p = 0.05) higher values inthe polluted soils and steams than in the unpolluted controls. The phosphate (PO ₄ ^3- ) values were lowerin the polluted soils and streams than in the unpolluted controls.PO ₄ ^3- , NO ₃ ^- , SO ₄ ^2- and Cl^- concentrations were generally significantly (p = 0.05) higher in soils and streams from Yorla, Zaakpon and their control than in Goi North, Goi South and Goi control.Exchangeable cations and trace metal concentrations weresignificantly (p = 0.05) higher in the polluted soils andstreams than in the unpolluted controls. Yorla and Zaakponpolluted soils and streams had higher concentrations of theexchangeable cations and trace metals compared to valuesfrom Goi, except for Na. Results also showed significantlyhigher values of heavy metals (Pb, Cd, Cr and Ni) in the polluted soils compared to their controls, and values werealso significantly (p = 0.05) higher in Yorla, Zaakpon andtheir control compared to Goi North, Goi South and Goicontrol. Values obtained in polluted streams were higherthan in the unpolluted though not significant at the 5%level (p = 0.05). The anionic and cationic concentrationsof Yorla and Zaakpon soils and streams were generally higherthan those of Goi, indicating that Yorla and Zaakpon areaswere more polluted than Goi.Although the concentrations of most of the anions andcations analysed in the polluted soils and streams werewithin the World Health Organisation's permissible valuesfor the protection of humans and environment, the streams ofYorla, Zaakpon and Goi are in general being polluted withinorganic ions. This may make these soils and streamsunacceptable for domestic and industrial uses if not treated,and soils (farmlands) may also become unsuitable for agricultural purposes.