SOURCE:

Faculty: Health Sciences And Technology
Department: Radiology

CONTRIBUTORS:

Fotso U. Daniel
Chiegwu H. U.

ABSTRACT:

Man’s ingestion of radioactive material may result from drinking contaminated water in the environment. This study was aimed to determine the gross alpha and gross beta activity in surface and underground water in Nnewi North Local Government Area, Anambra state, in order to know if water is safe for consumption. This is important because most of the internal exposure to man may result from the ingestion of contaminated water. Among the contaminants are: 241Am, 241Cm, 238Pu, 239Pu, 222Rn, 226Ra, which are alpha emitters; 45Ca, 14C, 134Cs, 89Sr, 90Sr, and tritium which are beta emitters. An aggregate of nineteen (19) water samples, nine (9) water samples from surface water sources and ten (10) water samples from underground water sources were analyzed for gross alpha and beta activity. Water samples were collected into 2 liter plastic kegs, acidified with Trioxonitrate (V) acid (HNO3) at the point of collection following the Environmental Protection Agency (EPA) procedures. Sample preparation and analysis was done at the CERT (Center of Energy Research and Training), Ahmadu Bello University, Zaria. The measured quantity (500ml) of water samples were evaporated to dryness in order to get the residue (about 77mg) which was transferred to a proportional gas-flow system (MPC 2000B-DP) and counted for 2700 second (45 minutes). Results indicated that the water sample under investigation had a mean gross alpha concentration of 0.48487±0.03453 Bq/L and mean gross beta concentration of 1.14587±0.07677 Bq/L for surface water and mean gross alpha concentration of 0.11587±0.00674 Bq/L and mean gross beta concentration of 0.35542±0.01267 Bq/L for underground water. Both alpha and beta emitters were less than 0.5 Bq/l for gross alpha and 1.0 Bq/L for gross beta activity (especially in underground water) which was lower compared to the maximum acceptable contamination limit as prescribed by the WHO. The annual equivalent effective dose derived from water consumption was calculated and found to be less than 0.3 mSv/yr provided that the water consumption was on average, 730 liters per adult inhabitant per year (2L per day) and 365 liters per children inhabitant per year (1L per day). Consumption of water in the region is safe but the areas where higher concentrations were observed should be monitored.