Natural radioactivity measurements and evaluation of radiological hazards in the soil of an iron beneficiation plant in China

Figures & data

Figure 1. Schematic diagram of soil sampling points.

Table 1. Specific activities of ²³⁸U, ²³²Th, ²²⁶Ra and ⁴⁰K in soil samples.

		Country of origin Activity concentration (Bq kg^−1)
Sample No.	Sample codes	^238U	^232Th	^226Ra	^40K
1	N	11.0 ± 0.7	49.7 ± 3.1	12.2 ± 0.8	656.6 ± 41.5
2	S	14.2 ± 0.9	51.2 ± 3.2	20.8 ± 1.3	626.6 ± 40.1
3	W	11.7 ± 0.7	43.8 ± 2.8	15.2 ± 1.0	658.8 ± 41.7
4	E	11.9 ± 0.8	41.9 ± 2.6	14.1 ± 0.9	620.9 ± 39.3
5	NTP	11.9 ± 0.8	45.9 ± 2.9	23.8 ± 1.5	644.3 ± 40.8
6	V1	12.5 ± 0.8	36.8 ± 2.3	8.8 ± 0.6	553.5 ± 35.0
7	V2	12.4 ± 0.8	38.2 ± 2.4	8.7 ± 0.5	572.6 ± 36.2
8	V3	11.0 ± 0.7	42.9 ± 2.7	10.6 ± 0.7	547.9 ± 34.6
9	V4	9.8 ± 0.6	45.3 ± 2.9	10.6 ± 0.7	504.6 ± 31.9
10	V5	8.7 ± 0.5	40.6 ± 2.6	9.9 ± 0.6	513.9 ± 32.5
11	V6	9.4 ± 0.6	39.2 ± 2.5	10.7 ± 0.7	564.7 ± 35.7
12	V7	10.4 ± 0.7	38.7 ± 2.4	9.2 ± 0.6	487.1 ± 30.8
13	V8	10.7 ± 0.7	40.0 ± 2.5	10.4 ± 0.7	541.0 ± 34.2
14	V9	10.6 ± 0.7	43.9 ± 2.8	9.0 ± 0.6	502.5 ± 31.8
15	V10	10.9 ± 0.7	51.6 ± 3.3	11.0 ± 0.7	565.8 ± 35.8
16	V11	9.4 ± 0.6	41.1 ± 2.6	9.7 ± 0.6	506.3 ± 32.0
17	V12	10.3 ± 0.7	37.3 ± 2.4	10.8 ± 0.7	568.5 ± 36.0
18	V13	11.6 ± 0.7	40.0 ± 2.5	8.7 ± 0.6	572.6 ± 36.2
19	V14	9.6 ± 0.6	41.2 ± 2.6	11.7 ± 0.7	557.4 ± 35.3
20	V15	9.0 ± 0.6	35.6 ± 2.2	8.3 ± 0.5	562.6 ± 35.6
21	V16	10.9 ± 0.7	37.0 ± 2.3	9.6 ± 0.6	522.1 ± 33.0
22	V17	12.8 ± 0.8	42.8 ± 2.7	10.9 ± 0.7	503.1 ± 31.8
23	V18	10.0 ± 0.6	42.8 ± 2.7	10.7 ± 0.7	582.6 ± 36.8
24	V19	9.9 ± 0.6	39.0 ± 2.5	9.3 ± 0.6	512.4 ± 32.4
25	V20	8.7 ± 0.5	38.0 ± 2.4	9.6 ± 0.6	489.2 ± 30.9
26	V21	10.3 ± 0.6	40.2 ± 2.5	9.2 ± 0.6	570.2 ± 36.1
27	V22	12.4 ± 0.8	40.1 ± 2.5	9.6 ± 0.6	525.1 ± 33.2
28	V23	9.8 ± 0.6	39.9 ± 2.5	8.7 ± 0.6	526.5 ± 33.3
29	V24	10.2 ± 0.6	41.0 ± 2.6	9.7 ± 0.6	581.8 ± 36.8
30	V25	9.4 ± 0.6	42.9 ± 2.7	10.5 ± 0.7	533.1 ± 33.7
31	V26	10.7 ± 0.7	47.1 ± 3.0	10.2 ± 0.6	550.7 ± 34.8
32	V27	9.6 ± 0.6	44.1 ± 2.8	11.2 ± 0.7	499.5 ± 31.6
33	V28	11.0 ± 0.7	46.0 ± 2.9	11.3 ± 0.7	609.0 ± 38.5
Min		8.7	35.6	8.3	487.1
Max		14.2	51.6	23.8	658.8
Ave.		10.7	42.0	11.1	555.6

Table 2. Comparison of average specific activities in soils in the study area with those reported by other researchers in different countries.

	Activity Concentration (Bq kg^−1)
Location	^238U	^232Th	^226Ra	^40K	Type	Reference
Vietnam	NG^a	36	30	331	Quarry towns	[39]
Bangladesh	65.9	83.17	NG	946.9	Naturally	[40]
Ghana	NG	31	27	132	Quarry towns	[41]
Malaysia (Langkawi Island)	NG	4.5-1272	8.3-2411	61-136	Naturally	[42]
Malaysia (Penang Island)	NG	9-5622	8-2641	68-495	Naturally	[43]
India	NG	203.74	53.36	479.19	Naturally	[44]
Mumbai	161	20	169	172	Phosphate fertilizer plant	[9]
Cameroon	99	157	125	671	Bauxite mining	[45]
Togo	158.6	47.8	173	30.1	Phosphate ore mining	[46]
Thailand	103	103	64	494	Coal-based power plant	[47]
Egypt	947	39.1	1469	152.5	Phosphate rocks	[48]
Tunisia	221.3	39.1	236	35.4	Phosphate treatment plants	[49]
Jordan	NG	35.5	29.0	265.7	Naturally	[50]
China	10.7	42.0	11.1	555.6	Iron beneficiation plant	This research
China Average	39.5	49.1	36.5	580.0	Naturally	[38]
Worldwide Average	33	45	32	420	Naturally	[30]

^a Not given.

Figure 2. Geo-Spatial distribution of ²³⁸U in the soils of the study area.

Figure 3. Geo-Spatial distribution of ²³²Th in the soils of the study area.

Figure 4. Geo-Spatial distribution of ²²⁶Ra in the soils of the study area.

Figure 5. Geo-Spatial distribution of ⁴⁰K in the soils of the study area.

Table 3. Radiation hazard indicators in soil samples.

Sample No.	Sample codes	Raeq (Bq kg^−1)	DR (nGy h^−1)	AED (μSv y^−1)	ELCR (10^−3)	Hex	Hin	AUI
1	N	133.8	62.5	76.6	0.3	0.4	0.4	0.8
2	S	142.3	63.6	78.0	0.3	0.4	0.4	0.9
3	W	128.6	59.3	72.8	0.3	0.3	0.4	0.7
4	E	121.8	56.7	69.5	0.2	0.3	0.4	0.7
5	NTP	139.0	60.1	73.7	0.3	0.4	0.4	0.8
6	V1	104.0	51.1	62.6	0.2	0.3	0.3	0.6
7	V2	107.4	52.7	64.6	0.2	0.3	0.3	0.6
8	V3	114.1	53.8	66.0	0.2	0.3	0.3	0.7
9	V4	114.2	52.9	64.9	0.2	0.3	0.3	0.7
10	V5	107.5	50.0	61.3	0.2	0.3	0.3	0.6
11	V6	110.2	51.6	63.2	0.2	0.3	0.3	0.6
12	V7	102.0	48.5	59.5	0.2	0.3	0.3	0.6
13	V8	109.3	51.7	63.4	0.2	0.3	0.3	0.6
14	V9	110.5	52.4	64.2	0.2	0.3	0.3	0.7
15	V10	128.4	59.8	73.3	0.3	0.3	0.4	0.8
16	V11	107.5	50.3	61.7	0.2	0.3	0.3	0.6
17	V12	107.9	51.0	62.5	0.2	0.3	0.3	0.6
18	V13	110.0	53.4	65.5	0.2	0.3	0.3	0.6
19	V14	113.5	52.6	64.5	0.2	0.3	0.3	0.7
20	V15	102.5	49.1	60.2	0.2	0.3	0.3	0.6
21	V16	102.7	49.2	60.3	0.2	0.3	0.3	0.6
22	V17	110.8	52.7	64.7	0.2	0.3	0.3	0.7
23	V18	116.8	54.8	67.2	0.2	0.3	0.3	0.7
24	V19	104.5	49.5	60.7	0.2	0.3	0.3	0.6
25	V20	101.6	47.4	58.1	0.2	0.3	0.3	0.6
26	V21	110.6	52.8	64.8	0.2	0.3	0.3	0.6
27	V22	107.4	51.8	63.6	0.2	0.3	0.3	0.6
28	V23	106.3	50.6	62.0	0.2	0.3	0.3	0.6
29	V24	113.1	53.7	65.9	0.2	0.3	0.3	0.6
30	V25	112.9	52.5	64.4	0.2	0.3	0.3	0.7
31	V26	120.0	56.4	69.1	0.2	0.3	0.4	0.7
32	V27	112.7	51.9	63.7	0.2	0.3	0.3	0.7
33	V28	124.0	58.3	71.5	0.3	0.3	0.4	0.7
Min		101.6	47.4	58.1	0.2	0.3	0.3	0.6
Max		142.3	63.6	78.0	0.3	0.4	0.4	0.9
Ave.		113.9	53.5	65.6	0.2	0.3	0.3	0.7
World wide safe limit		370	57	1000	1.45	1	1	1

Table 4. Descriptive statistics of activity concentration of ²³⁸U, ²³²Th, ²²⁶Ra and ⁴⁰K in soil samples.

	^238U	^232Th	^226Ra	^40K
Mean	10.7	42.0	11.1	555.6
Median	10.6	41.1	10.4	553.5
Standard Deviation	1.3	4.0	3.3	48.0
Variance	1.6	16.1	10.7	2301.7
Skewness	0.7	0.8	2.8	0.6
Kurtosis	0.3	0.3	8.6	−0.3
Range	5.5	16.0	15.5	171.7
Minimum	8.7	35.6	8.3	487.1
Maximum	14.2	51.6	23.8	658.8

Figure 6. Box plots of the results on ²³⁸U, ²³²Th, ²²⁶Ra and ⁴⁰K activity concentrations in the soil samples.

Figure 7. Frequency distribution and Quantile-quantile (Q-Q) plots of the activity concentrations for ²³⁸U of the investigated soil samples.

Figure 8. Frequency distribution and Quantile-quantile (Q-Q) plots of the activity concentrations for ²³²Th of the investigated soil samples.

Figure 9. Frequency distribution and Quantile-quantile (Q-Q) plots of the activity concentrations for ²²⁶Ra of the investigated soil samples.

Figure 10. Frequency distribution and Quantile-quantile (Q-Q) plots of the activity concentrations for ⁴⁰K of the investigated soil samples.

Table 5. Pearson’s correlation matrix between radioactive variables of the investigated soil samples.

Variables	^238U	^232Th	^226Ra	^40K	Raeq	DR	AED	ELCR	Hex	Hin	AUI
^238U	1	0.320	0.467	0.452	0.478	0.562	0.563	0.409	0.421	0.437	0.431
^232Th	0.320	1	0.549	0.418	0.863	0.855	0.856	0.720	0.555	0.738	0.903
^226Ra	0.467	0.549	1	0.626	0.829	0.709	0.709	0.682	0.773	0.662	0.735
^40K	0.452	0.418	0.626	1	0.773	0.814	0.813	0.711	0.582	0.731	0.513
Raeq	0.478	0.863	0.829	0.773	1	0.973	0.973	0.855	0.747	0.865	0.901
DR	0.562	0.855	0.709	0.814	0.973	1	1.000	0.846	0.684	0.871	0.860
AED	0.563	0.856	0.709	0.813	0.973	1.000	1	0.846	0.684	0.870	0.860
ELCR	0.409	0.720	0.682	0.711	0.855	0.846	0.846	1	0.671	0.833	0.731
Hex	0.421	0.555	0.773	0.582	0.747	0.684	0.684	0.671	1	0.559	0.696
Hin	0.437	0.738	0.662	0.731	0.865	0.871	0.870	0.833	0.559	1	0.725
AUI	0.431	0.903	0.735	0.513	0.901	0.860	0.860	0.731	0.696	0.725	1

Figure 11. Dendrogram shows the clustering of radiological parameters.

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