Activity concentrations of the selected radionuclides (40)K, (226)Ra and (232)Th were measured in surface soil samples collected from 38 cities in the southwest region of Nigeria by means of gamma spectroscopy with a high-purity germanium detector. Measured activity concentration values of (40)K varied from 34.9 +/- 4.4 to 1,358.6 +/- 28.5 Bq kg(-1) (given on a dry mass (DM) basis) with a mean value of 286.5 +/- 308.5 Bq kg(-1); that of (226)Ra varied from 9.3 +/- 3.7 to 198.1 +/- 13.8 Bq kg(-1) with a mean value of 54.5 Bq kg(-1) and a standard deviation of 38.7 Bq kg(-1), while that of (232)Th varied from 5.4 +/- 1.1 to 502.0 +/- 16.5 Bq kg(-1) with a mean value of 91.1 Bq kg(-1) and standard deviation of 100.9 Bq kg(-1). The mean activity concentration values obtained for (226)Ra and (232)Th are greater than the world average values reported by the United Nations Scientific Committee on Effects of Atomic Radiation for areas of normal background radiation. Radiological indices were estimated for the radiation/health hazards of the natural radioactivity of all soil samples. Estimated absorbed dose rates in air varied from 12.42 +/- 2.25 to 451.33 +/- 19.06 nGy h(-1), annual outdoor effective dose rates from 0.015 +/- 0.003 to 0.554 +/- 0.023 mSv year(-1), internal hazard index from 0.10 +/- 0.03 to 3.02 +/- 0.16, external hazard index from 0.07 +/- 0.01 to 2.60 +/- 0.11, representative level index from 0.19 +/- 0.03 to 6.84 +/- 0.29, activity index from 0.09 +/- 0.02 to 3.42 +/- 0.15, and radium equivalent activity from 26.95 +/- 5.04 to 963.15 +/- 41.87 Bq kg(-1). Only the mean value of the representative level index exceeds the limit for areas of normal background radiation. All other indices show mean values that are lower than the recommended limits.

The leaching of powdered sphalerite using hydrogen peroxide and nitric acid has been investigated. The important variables such as concentrations of hydrogen peroxide and nitric acid as well as stirring speed and particle size were examined. The effect of reaction temperature was also examined on the leaching reaction process. The hydrogen peroxide and nitric acid concentrations have significant effects on the leaching of sphalerite. The leaching of sphalerite is dependent on temperature and stirring speed and inversely proportional on the ore particle size. The apparent activation energy is found to be 28.7kJmol-1 suggesting that the reaction is chemical-control at the surface of the particles.

Activity concentrations of (40)K, (226)Ra, (228)Ac and (235)U were measured in 11 dug and 9 drilled well water samples from 3 large cities in Ogun state, Southwestern Nigeria, consumed by the population living in the cities. The measurement was done using co-axial type high-purity germanium (HPGe) detector (Canberra Industries Inc.). The measured activity concentrations in the water samples ranged from 1.74 +/- 1.83 to 4.69 +/- 0.17 Bq l(-1); 2.89 +/- 0.62 to 7.79 +/- 7.22 Bq l(-1); 0.35 +/- 0.07 to 1.17 +/- 0.40 Bq l(-1) and 0.18 +/- 0.05 to 4.77 +/- 0.34 Bq l(-1) for (40)K, (226)Ra, (228)Ac and (235)U, respectively. Total annual effective dose rates from the ingestion of these radionuclides in the untreated wells were estimated using measured activity concentrations in the radionuclides and their ingested dose conversion factors. Estimated annual effective dose rates ranged from 0.04 to 6.82; 0.01 to 1.36 and 0.01 to 1.49 mSv y(-1) for age groups <1, 2-7 and > or =17 y, respectively. Committed dose for age group > or =17 y ranged from 8.8 x 10(-4) to 8.9 x 10(-2) Sv. The calculated annual effective dose values due to the ingestion of (226)Ra in the Awujale, Ake, Saboab, Alagbon, Alapora and Totoro samples exceeded International Commission on Radiological Protection limit of 1.0 mSv y(-1) for individual public exposure. These wells are recommended for treatment that would remove radium from their waters.

Citrus sinensis seed and peel oils were extracted by solvent extraction using n-hexane, after air drying and grinding. Soaps were formed by saponification methods. Fatty acid composition of the oil samples were analyzed using Gas Chromatograph-Flame Ionization Detector (GC-FID). Physicochemical properties of the oils and soaps were determined following standard methods. Antimicrobial activities were assessed by the agar disc and hole-in plate methods. The seed and peel oil yield were 38 and 30%, respectively and the colors were golden yellow and brownish-yellow, respectively. Physicochemical properties of the oil samples determined were: refractive index (

Gamma spectrometry of well water was done to measure the activity concentrations of gamma-emitters 226Ra and 228Ra from 238U and 232Th series, respectively, and 40K in their waters. Measurements were done using high-purity (HPGe) co-axial detectors (Canberra, GC 2018-7500 ) coupled to Canberra Multichannel Analyser system. Activity concentrations ranged from 0.57 to 26.86, 0.20 to 60.06 and 0.35 to 29.01 Bq l(-1) for 226Ra, 228Ra and 40K, respectively. Activity concentrations were compared with data from other parts of the world and used to estimate annual effective dose for three age groups. Total annual effective doses from the intake of these radionuclides in the waters ranged from 0.02 to 76.84, 0.02 to 38.80 and 0.05 to 481.60 mSv y(-1) for age group <1, 2-7 and > or =17 y, respectively. These values are considerably higher than both the World Health Organisation and the International Commission on Radiological Protection limits.