Body size in animals is an important trait affecting species niche differentiation and restricting similarity. Using camera-trap data over 2008–2010, we used photo-captures from 50 cameras spread throughout Mudumalai Tiger Reserve (Western Ghats, India) to assess the activity budgets of 21 mammal species ranging in body size from 1 kg to 2088 kg. Large carnivores were mostly cathemeral whereas small cat and civet species were purely nocturnal. Mongoose species were mainly diurnal possibly due to their terrestrial feeding habits and reduce competition with other sympatric small carnivores. All large and small-bodied herbivores were cathemeral and nocturnal respectively, whereas medium-sized herbivores were active during the day. Overall, small mammals tended to be mostly nocturnal, whereas large mammals were cathemeral mainly due to energy requirements and other ecological constraints. Body size showed significant negative relationship with mean vector length (clustering of activity in time) thus implying that the daily amount of time being active increased with body size. The shorter activity time (12 h) in small mammals resulted in higher mean vector length probably to utilize the available time to fulfil energy needs. The observed cathemeral activity in large mammals may be associated with travel over larger areas to acquire large quantities of food therefore they are active for a longer duration. Our results clearly support the allometric relationship between body size and activity budgets in mammals and its association with niche differentiation.

Bitumen samples and soil samples around a bituminous deposit in Ondo State, Nigeria, wereanalysed for 40K, 226Ra and 232Th employing gamma-rayspectrometry. The activity concentrations of 40K, 226Ra and232Th in soil varied from (45.2 ± 5.3) to (484.2 ± 25.9), BDL (belowdetectable limit) to (27.7 ± 2.1) and (22.8 ± 2.7) to (62.4 ± 6.8) Bq.kg-1,respectively. The corresponding mean values were (240.2 ± 133.5), (13.3 ± 8.0) and (40.0 ±10.2) Bq.kg-1, respectively. The mean activity concentrations of theradionuclides in the bitumen were (58.4 ± 36.4), (16.1 ± 13.3) and (32.5 ± 13.1)Bq.kg-1, respectively, for 40K, 226Ra and232Th. The mean absorbed dose and effective dose for the soil samples were(41.5 ± 8.9) nGy.h-1 and (50.7 ± 10.9) μSv.y-1, respectively, whilethose of the bitumen samples were (29.5 ± 15.6) nGy.h-1 and (36.1 ± 19.1)μSv.y-1, respectively. For radiological hazard assessment, the radiumequivalent activity and the external hazard index were determined. The values of theradium equivalent activity and external hazard index obtained for the soil and bitumensamples were lower than the recommended limit.

Farming on soils situated in high background radiation areas can result to enhanced radiation exposure scenarios and pathways to humans. To assess the likely levels of exposures, farm soil samples were collected from different farmlands in three old tin mining localities (Bitsichi, Bukuru and Ropp) in Jos Plateau Nigeria, known for high radiations. The soil samples were analyzed for the activity concentrations of 226Ra, 232Th and 40K, using gamma-ray spectroscopy. The outdoor annual effective dose rates were calculated using the activity concentrations of the radionuclides and were found to vary from 0.07 mSv to 2.02 mSv across the three localities. Considering dust generation from soil tillage and inadvertent ingestion of soil particles, the likely internal radiation hazards were estimated using conservative dust and soil loading factors. The total average annual effective dose rates due to 226Ra and 232Th that could result from dust inhalation and ingestion of soil particles were 16.9 µSv, 8.1 µSv and 8.8 µSv, respectively for Bitsichi, Bukuru and Ropp. Though these values are about 5% the outdoor exposures to the farmers in those farms and greater than 1 µSv y-1, from the point of view of radiation protection and risk, they are significant. It suffices to say, therefore, that the results of this study will create the possibility of the importance to evaluate the health risk among the farming population and workplace environments which often is not covered by regulations concerning health protection.

Naturally occurring radioactive materials (NORMS) and fallout 137Cs were estimated in surface soils from the highly mineralized Singhbhum region of Eastern India. The activity concentrations varied from 50.67-109.14 Bq/kg (238U), 48.12-142.55 Bq/kg (226Ra), 28.73-89.78 Bq/kg (232Th), 494.84-1121.36 Bq/kg (40K) and 1.8-7.48 Bq/kg (137Cs). Correlation between radionuclides was studied. 232Th/238U concentration (Clark value) was also calculated. Radiation hazard for the samples was assessed by radium equivalent activity (Raeq), external hazard index (Hex), internal hazard index (Hin) and absorbed gamma dose rate (D). Raeq values ranged from 216-263 Bq/kg, Hex values from 0.58-0.71 Bq/kg, Hin values from 0.73-1 Bq/kg and D values from 100-121 nGy/h. Calculated and observed dose rates in air were compared with the help of parametric and non-parametric tests. The tests showed significant difference between the calculated and observed dose rates.

The radionuclide contents of sediment samples collected from 20 surface-water dams in southwestern Nigeria have been determined by low-level gamma-spectroscopy. The average concentration of 40K in each of the dams varied between 110.9 ± 11.9 Bq kg-1 and 1025.9 ± 36.8 Bq kg-1 with an overall mean (± SD) of 549.3 ± 247.6 Bq kg-1 while that of 238U varied from 17.1 ± 3.6 to 51.9 ± 8.7 Bq kg-1 with an overall mean (± SD) of 27.6 ± 8.5 Bq kg-1 and that of 232Th varied from 26.2 ± 3.6 Bq kg-1 to 130.1 ± 23.7 Bq kg-1 with overall mean (± SD) of 62.0 ± 26.1 Bq kg-1. The variability of the values shows the wide disparity in the measured activity concentrations. The mean radium equivalent of 158.9 Bq kg-1 was calculated for the sediments in the dams. No artificial gamma emitting radionuclide was detected in the samples.