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 soils and streams varied significantly (p = 0.05) from those of unpolluted soils and streams. Anions such as nitrate (NO(-)3), sulphate (SO(2-)4) and chloride (Cl-) showed significantly (p = 0.05) higher values in the polluted soils and steams than in the unpolluted controls. The phosphate (PO(3-)4) values were lower in the polluted soils and streams than in the unpolluted controls. PO(3-)4, NO(-)3, SO(2-)4 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 were significantly (p = 0.05) higher in the polluted soils and streams than in the unpolluted controls. Yorla and Zaakpon polluted soils and streams had higher concentrations of the exchangeable cations and trace metals compared to values from Goi, except for Na. Results also showed significantly higher values of heavy metals (Pb, Cd, Cr and Ni) in the polluted soils compared to their controls, and values were also significantly (p = 0.05) higher in Yorla, Zaakpon and their control compared to Goi North, Goi South and Goi control. Values obtained in polluted streams were higher than in the unpolluted though not significant at the 5% level (p = 0.05). The anionic and cationic concentrations of Yorla and Zaakpon soils and streams were generally higher than those of Goi, indicating that Yorla and Zaakpon areas were more polluted than Goi. Although the concentrations of most of the anions and cations analysed in the polluted soils and streams were within the World Health Organisation's permissible values for the protection of humans and environment, the streams of Yorla, Zaakpon and Goi are in general being polluted with inorganic ions. This may make these soils and streams unacceptable for domestic and industrial uses if not treated, and soils (farmlands) may also become unsuitable for agricultural purposes.