Concentration of radon and other elements in groundwaters of the Jos and Bukuru younger granite aquifers

Abstract

The Jos-Bukuru crystalline rocks have high radioactivity, but not much is known about the 
concentration of radon in the waters of its aquifers. In this work, the activity concentra
tions of radon-222 (222Rn) were investigated from 20 water samples collected at different 
locations within the Jos-Bukuru area. The analysis of radon was done using liquid scintil
lation counter. A total of 15 out of the 20 water samples were analyzed for anions and 
cations. The anions (SO4
−2 and Cl−) were analyzed using a multiparameter and HCO3
− by 
titration. The cations (major ions, trace elements, and rare earth elements were analyzed 
using inductively coupled plasma mass spectrometry. Radon concentration in groundwa
ter of the study area ranges from 1.62 to 24.55 Bq/l with a mean value of 15.62 Bq/l. only 
25% of the water sources had radon above the 10 Bq/l recommended by the WHO. These 
values were obtained within the Jos and Bukuru boitite younger granite aquifers. The vari
ation in radon content in water is the result of: (1) the actual use of the wells in the area 
such as extraction of groundwater which increases the groundwater circulation thereby 
decreasing the radon content and (2) bad well constructions with inflow of surface water, 
and (3) bedrock geology. Radon behaved independently with regard to the major ions and 
some of the trace elements but showed a positive but not significant relationship with 
uranium and some of the rare earth elements indicating a possible contribution of these 
elements to the concentration of radon in the waters. The annual effective doses due to 
ingestion of 222Rn in water for the three categories of people vary from 0.038, 0.077, and 
0.271 mSv/y for adults, children, and infants, respectively. These are within the recom
mended limits of 0.1 mSv/y for adults and children but high for infants. The composition 
of the groundwaters in the area is dominated by natural water–rock interactions while 
other areas were highly impacted by anthropogenic sources. On the basis of total dis
solved solids, all the samples are within the range of desirable to permissible for drinking.