Trace element and radiological characterisation of ash and soil at a legacy site in the former Raša coal-mining area

Figure 1

Figure 2

Figure 3

Mean radium equivalent indices (Raeq), absorbed dose rates (Ḋ), and annual effective doses (E) in soil and ash samples at the Štrmac legacy site calculated from activity concentrations of activity concentration of 226Ra, 232Th, and 40K

Sample type	Raeq (Bq/kg)	Ḋ (nGy/h)	E (mSv/year)
Ash (n=19)	399 (122–751)	184 (57–346)	0.23 (0.07–0.42)
Soil (n=6)	153 (80–213)	71 (38–99)	0.09 (0.05–0.12)

Comparison between measured and certified values for standard reference materials SRM 2710 and PTXRFIAEA08 Natural Soil*

Element	SRM 2710			Natural soil
	Mean±SD	Certified value ± error	Relative error (%)	Mean ± SD	Certified value ± error	Relative error (%)
Mg	0.8±0.2	0.853±0.04	-6.3	-	-	-
Al	6.5±0.2	6.44±0.08	1.1	17.99±0.06	15.2±0.4	18.4
Si	27.0±0.3	29.0±0.2	-6.8	17.68±0.06	18.7±0.4	-5.4
S	0.26±0.01	0.240±0.006	8.1	0.109±0.05	0.071±0.004	54.5
K	2.03±0.04	2.1±0.1	-3.7	0.023±0.003	0.034±0.002	-33.1
Ca	1.12±0.02	1.25±0.03	-10.3	-	-	-
Fe	3.28±0.03	3.4±0.1	-3.1	8.82±0.03	9.0±0.3	-2.2
Na	9000±400	11400±600	-21.3	-	-	-
P	1400±200	1060±150	30.7	-	-	-
Ti	2670±60	2830±100	-5.7	9200±100	9410±380	-1.9
V	90±20	76.6±2.3	21.5	280±50	270±19	4.7
Cr	80±30	39	98.0	30±20	31±3	6.7
Mn	9700±200	10100±400	-4.1	180±30	174±13	2.8
Ni	21±2	14.3±1	49.2	-	-	-
Cu	3150±40	2950±130	6.7	50±10	36±3.4	48.1
Zn	7100±100	6952±91	1.6	40±10	69±6	-34.2
Ga	-	-	-	50±20	33±3	45.9
As	400±100	626±38	-27.6	-	-	-
Se	-	-	-	60±40	2.3±0.3	2354.1
Br	250±50	15±2	1524.0	-	-	-
Sr	-	-	-	30±30	4.6±0.6	562.3
Zr	-	-	-	200±50	266±18	-23.8
Ba	540±70	707±51	-23.5	-	-	-
Hg	140±80	33±2	316.2	-	-	-
Pb	6800±200	5532±80	22.1	-	-	-

Ranking of sampling locations by measured S and V levels (from highest to lowest)

Sampling location	S (%)	Sampling location	V (mg/kg)
12	8.26	6	210
1	3.6	1	200
6	2.94	8	200
8	0.293	2	150
9	0.227	3	150
2	0.18	9	150
11	0.176	5	140
10	0.156	10	140
3	0.09	12	130
5	0.09	11	120
7	0.06	7	90

Trace element concentrations (in mg/kg) in measured soil samples with limits of detection (LOD) for each element and comparison with trace element concentrations obtained with HR-ICP-MS in one sample taken close to location 1 reported by Petrović (48)

Soil Samples	Cu	Zn	As	Se	Br	Rb	Sr	Y	Pb
1	180±50	70±20	20±10	20±10	30±10	--	550±20	60±20	70±40
2	73±9	120±10	--	--	30±30	210±40	250±30	--	120±90
3	51±6	160±50	--	--	--	360±50	70±50	--	130±20
5	44±8	130±10	--	--	60±30	330±40	140±30	--	200±100
6	86±8	130±10	--	--	40±20	130±30	210±30	--	170±80
7	30±30	90±10	--	--	20±20	120±20	504±6	--	90±60
8	39±8	110±10	--	20±20	60±30	260±40	100±30	--	200±100
9	37±7	120±10	--	--	--	230±40	130±20	--	110±90
10	24±8	100±10	--	40±20	30±30	220±40	90±20	--	100±100
11	41±7	100±10	--	23±9	--	180±30	130±20	--	140±90
12	72±9	13±7	20±10	--	--	--	580±40	--	--
Petrović	37.8	120	14.8	21.8	--	--	128	--	48.2
LOD	10	20	20	30	40	50	30	20	90

Minor and trace element concentrations (in mg/kg) in measured soil samples with limits of detection (LOD) for each element and comparison with trace element concentrations obtained with HR-ICP-MS in one sample taken close to location 1 reported by Petrović (48)

Soil samples	Na	P	Cl	Ti	V	Cr	Mn	Co	Ni
1	--	--	--	1180±70	200±10	160±40	200±100	--	20±10
2	1600±100	600±60	140±30	4170±70	150±20	450±40	1490±60	--	140±10
3	2300±100	760±60	120±10	5030±80	150±20	300±100	1700±100	--	159±6
5	2600±100	740±60	150±30	5390±70	140±20	350±30	2170±70	170± 30	144±9
6	2000±100	130±60	200±30	4510±70	210±20	320±40	1000±50	--	104±8
7	1230±40	400±100	160±60	2600±200	90±10	400±200	500±40	--	82±4
8	3300±100	1470±70	130±30	4850±70	200±20	380±30	1770±60	--	100±10
9	2400±100	890±70	230±30	4740±70	150±20	270±30	1340±60	--	126±8
10	4000±200	800±70	120±30	6070±80	140±20	570±40	1370±60	--	110±8
11	3800±200	1350±80	400±40	5810±80	120±20	380±30	2180±70	--	85±8
12	--	--	100±30	710±60	130±20	100±60	360±80	--	--
Petrović (48)	--	--	--	--	183	167	--	--	96.3
LOD	200	100	50	40	50	50	60	200	10

Sample labels and geographical coordinates

1st field campaign (May 2019)
Sample label	Sample type	Geographical coordinates
0	Soil	45° 7' 14.40"N	14° 7' 36.86" E
1		45° 7' 10.80"N	14° 7' 40.40" E
2		45° 7' 9.98"N	14° 7' 41.97" E
3		45° 7' 8.87" N	14° 7' 43.53" E
5		45° 7' 11.41" N	14° 7' 46.35" E
6		45° 7' 13.12" N	14° 7' 44.07" E
7		45° 7' 13.55" N	14° 7' 48.76" E
8		45° 7' 11.09" N	14° 7' 44.22" E
9		45° 7' 14.97" N	14° 7' 48.27" E
10		45° 7' 16.45" N	14° 7' 49.44" E
11		45° 7' 17.60" N	14° 7' 50.48" E
12	Ash	45° 7'10.88" N	14° 7'39.14" E
13
14		45° 7' 11.31" N	14° 7' 38.83" E
15

Measured elements in this study (mg/kg) compared to world soils and Croatian legislation

Element	This research (mg/kg)	Croatian legislation (51) (mg/kg)	World soils (52, 53) (mg/kg)	World soils (54) (mg/kg)	Topsoil Europe (54) (mg/kg)	Geochemical atlas (50) (mg/kg)
Al	11700–92200		80000			78500
As	20	30	5	6.83	11.6	18
Br	20*–60		10	10
Ca	8620–290000		14000			13300
Cl	100–400		300	300
Co	170*	60	10	11.3	10.4	18
Cr	100–570	120	80	59.5	94.8	121
Cu	24–180	120	25	38.9	17.3	35.5
Fe	9300–49200		35000			41800
K	150–10500		14000			12500
Mg	8900–15000		9000			6800
Mn	200–2180		530	488	524	1082
Na	1230–4000		10000			3400
Ni	20–159	75	20	29	37	74.6
P	130–1470		750			650
Pb	70*–200	150	17		32	48.7
Rb	120–360		65	68	87
S	600–82600		800
Se	20*–40		0.3	0.44
Si	22000–311100		280000
Sr	70–580		240		130	86
Ti	710–6070		4000	7038	6070	4300
V	90–200		90	129	68	148
Y	60		20	23	23	28
Zn	13*–160	200	70	267	68.1	108

Major and minor element concentrations (in %) in measured soil samples with limits of detection (LOD) for each element

Soil samples	Mg	Al	Si	S	K	Ca	Fe
1	1.5±0.1	2.3±0.2	2.2±0.1	3.6±0.2	0.015±0.09	29±3	1.58±0.02
2	1.25±0.01	7.91±0.03	22.82±0.07	0.180±0.005	1.45±0.01	7.21±0.03	4.22±0.04
3	1.29±0.004	9.22±0.03	26±1	0.09±0.01	1.5±0.1	1.11±0.03	4.92±0.06
5	1.13±0.01	8.85±0.03	27.90±0.09	0.09±0.004	1.43±0.01	0.984±0.009	4.73±0.08
6	0.82±0.01	6.3±0.02	19.32±0.03	2.94±0.01	0.763±0.008	6.94±0.02	3.44±0.02
7	1.03±0.03	5.3±0.1	16±1	0.06±0.01	1.25±0.03	19.4±0.04	2.574±0.08
8	1.03±0.01	8.34±0.04	28.4±0.1	0.293±0.006	1.43±0.01	1.31±0.01	4.33±0.07
9	1±0.01	7.88±0.03	30.5±0.1	0.227±0.006	1.34±0.01	1.26±0.01	4.1±0.08
10	0.98±0.01	8.76±0.03	31.11±0.08	0.156±0.006	1.34±0.01	0.862±0.09	4.43±0.09
11	0.89±0.01	8.24±0.04	26.9±0.01	0.176±0.006	1.29±0.01	1.19±0.01	3.95±0.07
12	1.25±0.02	1.17±0.01	1.16±0.01	8.26±0.04	--	26.2±0.1	0.93±0.01
LOD	0.01	0.007	0.006	0.007	0.005	0.01	0.002

Mean, minimum, and maximum activity concentrations (Bq/kg) of natural radionuclides in soil and ash samples from Štrmac

Sample type		238U	232Th	226Ra	210Pb	40K
		Activity concentration (Bq/kg)
Soil	Average±SD	80±33	44±19	61±23	179±70	381±127
	Min	50	21	23	52	134
	Max	138	67	81	239	464
Ash	Average±SD	403±174	22±12	355±125	255±84	162±67
	Min	88	7	96	49	36
	Max	828	44	681	393	319

Pollution indices of selected elements in respect to reference values from Table 6 used in PI calculation*

Variables	Croatian ordinance (51)	World soils (52, 53)	World soils (54)	Topsoil Europe (54)	Geochemical atlas of Croatia (50)
As	0.67	4	2.93	1.72	1.11
Co	2.83	17	15.04	16.35	9.44
Cu	1.5	7.2	4.63	10.4	5.07
Cr	4.75	7.13	9.58	6.01	4.71
Fe		1.41			1.18
Mn		4.11	4.47	4.16	2.01
Ni	2.12	7.95	5.48	4.3	2.13
Pb	0.93	8.24		4.38	2.87
S		103.25
Se		133.33	90.91
Sr		2.42		4.46	6.74
V		2.22	1.55	2.94	1.35
Zn	0.8	2.29	0.6	2.35	1.48

Activity concentrations (Bq/kg) of natural radionuclides in soil and ash samples from Štrmac

	Sample code	Sample type	238U	232Th	226Ra	210Pb	40K
			Activity concentration ± relative uncertainty (Bq/kg)
1st field campaign
	0	Soil	99±7	22±2	81±1	231±47	134±4
	2		58±6	44±2	44.1±0.9	52±47	433±10
	6		62±8	57±2	58.9±0.8	160±31	446±10
	7		50±4	20.8±0.9	23.2±0.6	171±33	354±9
	9		72±6	51±2	75±1	219±37	453±11
	11		138±9	67±3	81±1	238±37	464±12
	14	Ash	458±10	17±2	349±3	288±29	302.6±0.9
	15		372±9	16±2	314±3	240±46	319±1
2nd field campaign
	A1	Ash	605±13	44±2	295±2	306±24	188±4
	A2a		567±10	34±2	440±2	318±20	183±6
	A2b		413±10	32±3	465±4	260±42	149±7
	A3a		440±15	42±3	551±3	341±31	173±7
	A3b		828±19	41±2	681±3	393±29	140±6
	A3c		401±12	29±2	376±2	303±24	162±7
	B1a		663±15	18±1	405±3	392±26	147±5
	B1b		306±8	16±1	341±2	227±27	147±6
	B2a		340±9	18±1	332±3	240±40	36±2
	B2b		308±8	13±1	316±2	168±31	137±8
	B2c		403±9	21±2	396±3	296±25	55±3
	B3a		304±7	7±1	326±2	230±37	141±6
	B3b		459±12	13±1	318±3	251±24	160±5
	C1		88±6	10±2	96±1	49±39	147±5
	C2		211±7	27±2	274±2	149±19	226±6
	D1		236±11	18±2	236±2	204±35	153±6
	D2		250±7	9±1	225±2	193±33	118±5