Radioactivity concentration and heavy metal assessment of soil and water, in and around Imirigin oil field, Bayelsa state, Nigeria

摘要

The alpha and beta activity concentration and heavy metal assessment of soil and water in and around Imirigin oil field has been carried out. Study area was subdivided into five locations, Soil and water samples were collected from field undisturbed environment and oil spilled areas. Sample collection and preparation follows standard procedures.In situmeasurement was conducted for pH and electrical conductivity, heavy metal analysis was carried out using Atomic absorption Spectrophotometer (AAS) and gross alpha and beta activity concentration was by using gas filled proportional counter. Average value for pH and E.C. are 6.5±0.2 and 46.8±1.0 µs/cm respectively for soil and 6.4±0.5 and 406.1±5.2 µs/cm respectively for water. The mean values obtained for ASS analysis for soil are 11.9±1.0, 3.3±0.4, 1.7±0.7, 8.1±0.5, 42.5±1.9, 3.3±0.5, 8.0±0.6, 0.08±0.02 and 79.5±2.2 mg/kg. For Ca, Mg, Zn, Ni, Fe, Cd, Pb, Hg and Cr respectively for water, mean value obtained are 8.3±0.5, 4.2±0.4, 1.6±0.4, 1.5±0.3, 1.3±0.2, 0. 0.06±0.004, 0.07±0.003, 0.05±0.01 and ND mg/l for Ca, Mg, Na, K, Fe, Pb, Cd, Hg and AS respectively. Gross alpha and beta activities mean concentrations for soil are 0.53±0.02 Bq/g and 29.29±0.17 Bq/g respectively, and 4.02±0.01 Bq/l and 54.23±1.76 Bq/l respectively for water. The results show that the level of the various metals obtained differs from location to location. Values obtained in soil are within reported values in the Niger Delta region except Iron level. Heavy metals such as Ca, Fe and Cd exceed the WHO limits for drinking water. The mean values for alpha and beta activity in soil are above reported values in similar environment while mean values obtained in water samples are above WHO recommended maximum permissible limit for drinking water. These values obtained shows that drinking water from sampled locations may pose some long term health hazards to the public users though soil from the area is still safe as construction material for buildings.