Assessment of Levels of Natural Radioactivity in Sand Samples Collected from Ekalakala in Machakos County, Kenya

Table 4

Average specific activity of ²³⁸U, ²³²Th, and ⁴⁰K calculated from sand samples collected at depths of 0 m–0.3 m and 0.3 m–0.5 m from Ekalakala River.

Sample	Specific activity (Bqkg^−1)
	^238U	^232Th	^40K
1	15.0 ± 1.0	18.5 ± 2.6	1370 ± 90
2	13.5 ± 1.5	16.1 ± 1.0	1340 ± 30
3	10.2 ± 0.7	11.9 ± 1.8	1290 ± 100
4	12.6 ± 0.9	18.0 ± 1.1	1040 ± 60
5	16.6 ± 3.4	26.2 ± 3.7	1470 ± 60
6	9.7 ± 1.1	11.5 ± 1.6	820 ± 20
7	11.3 ± 2.1	15.4 ± 1.3	1850 ± 40
8	20.4 ± 1.0	19.6 ± 2.4	1390 ± 50
9	17.7 ± 1.7	19.4 ± 0.9	1380 ± 70
10	10.5 ± 2.6	13.8 ± 1.0	930 ± 30
11	14.3 ± 3.1	13.0 ± 2.0	1120 ± 50
12	24.0 ± 1.3	25.9 ± 2.6	1740 ± 50
13	14.0 ± 1.8	18.6 ± 1.6	1340 ± 30
14	12.0 ± 1.7	16.0 ± 1.5	1330 ± 30
15	12.7 ± 2.3	15.7 ± 1.3	1240 ± 40
Range	9.7–24.0	11.5–26.2	820–1850
Mean	14.3 ± 3.8	17.3 ± 4.2	1300 ± 300
World mean	33	45	420