Risk assessment and source analysis of heavy metal contamination in the soil of the Juanshui River Mouth

Figures & data

Figure 1. Map of the study area.

Figure 2. Map of the sampling sites.

Table 1. Location of sampling sites.

		1	2	3	4	5	6
Section A-A	Longitude	112.92	112.92	112.92	112.92	112.92	112.92
	Latitude	27.78	27.78	27.77	27.77	27.78	27.78
Section B-B	Longitude	112.90	112.90	112.90	112.90	112.90	112.90
	Latitude	27.76	27.76	27.76	27.76	27.76	27.76

Table 2. Classification criteria of single-factor index pollution.

Pi	Pi≤ 1		1< Pi ≤ 2	2< Pi ≤ 3		Pi > 3
Pollution level	No pollution		Low pollution	Medium Pollution		Heavy Pollution

Table 3. Classification criteria of comprehensive soil pollution degree.

NIPI	Pollution Grade	Quality Value
PN≤ 0.7	1	Practically uncontaminated
0.7< PN≤ 1.0	2	Relatively uncontaminated
1.0< PN≤ 2.0	3	Low contamination
2.0< PN≤ 3.0	4	Moderate contamination
PN> 3.0	5	High contamination

Table 4. Toxicity coefficient of heavy metals.

Heavy metals	Cr	Cu	Cd	Pb	Hg	As
${\mathrm{T}}_r^i$	2	5	30	5	40	10

Table 5. Classification criteria of potential ecological risk levels.

Ei r	Ecological Grade	RI
$E_r^i$< 40	Low risk	$RI$<150
40≤ $E_r^i$< 40	Moderate risk	150≤$RI$<300
80≤ $E_r^i$< 160	Considerable risk	300≤$RI$<600
160≤ $E_r^i$< 320	High risk	$RI$≥600
$E_r^i$≥ 320	Very high risk

Table 6. Soil heavy metal contents in the mouth of the Juanshui River (mg/kg).

		Cr	Cu	Cd	Pb	Hg	As	pH	OM
Section A-A	Min	72.23	33.97	0.503	49.68	0.106	17.78	4.26	6.23
	Max	102.98	47.86	5.526	117.78	0.304	39.03	7.21	34.67
	Mean	85.98	38.59	1.37	75.30	0.17	29.10	6.42	13.85
	SD^a	5.36	1.76	1.03	10.56	0.03	4.92	0.62	12.84
	CV	0.06	0.05	0.78	0.14	0.15	0.17	0.10	0.93
Section B-B	Min	75.23	25.80	0.222	38.08	0.090	11.42	5.28	6.23
	Max	105.64	118.12	2.561	74.22	0.399	24.99	7.81	34.67
	Mean	90.44	35.25	0.98	55.03	0.13	17.20	6.43	13.67
	SD^a	1.76	6.74	0.43	5.59	0.02	1.56	0.20	14.49
	CV	0.02	0.19	0.45	0.10	0.12	0.09	0.50	1.06
Background		54	22	0.60	40	0.10	15	-	-

^aSD: standard deviation.

Figure 3. Spatial distribution of heavy metal contents (mg kg⁻¹⁾ in soil sections.

Figure 4. Pollution index (P) on A-A section (left) and B-B section (right).

Table 7. Results of pollution index of heavy metals in soil sections.

Number		Pi						PN
		Cr	Cu	Cd	Pb	Hg	As
Section A-A	1	1.64	1.91	1.48	2.35	1.91	2.34	2.13
	2	1.54	1.77	1.29	1.87	1.66	2.23	1.99
	3	1.42	1.65	2.07	1.89	1.49	1.99	1.87
	4	1.56	1.74	1.18	1.85	2.10	2.11	1.94
	5	1.65	1.75	5.98	1.90	1.56	1.47	4.55
	6	1.65	1.75	5.98	1.90	1.56	1.47	4.55
	Mean	1.58	1.76	3.00	1.96	1.71	1.94	2.84
Section B-B	1	1.69	2.24	0.88	1.30	1.27	1.19	1.87
	2	1.66	1.60	1.76	1.48	1.38	1.22	1.64
	3	1.74	1.61	1.83	1.48	1.34	1.27	1.69
	4	1.65	1.25	0.64	1.09	1.14	0.94	1.41
	5	1.64	1.52	1.67	1.44	1.57	1.14	1.59
	6	1.66	1.43	2.86	1.46	1.09	1.12	2.32
	Mean	1.68	1.61	1.61	1.37	1.30	1.15	1.76

Figure 5. Potential ecological risk index (RI) on A-A section (left) and B-B section (right).

Table 8. Results of potential ecological risk index of heavy metals in soil sections.

Number	Ei r							RI
		Cr	Cu	Cd	Pb	Hg	As
Section A-A	Min	2.84	8.27	38.63	9.25	59.42	14.71	148.60
	Max	3.31	9.56	179.37	11.73	76.57	23.44	278.23
	Mean	3.16	8.81	89.87	9.80	68.58	19.36	199.57
	RI	18.93	52.88	539.19	58.80	411.46	116.14	-
Section B-B	Min	3.29	6.24	19.23	5.47	43.58	9.43	158.35
	Max	3.48	11.18	85.83	7.39	62.70	12.68	158.35
	Mean	3.35	8.03	48.25	6.87	51.89	11.47	129.86
	RI	20.10	48.17	289.48	41.22	311.35	68.82	-

Table 9. Correlation coefficients of heavy metals.

	Cr	Cu	Cd	Pb	Hg	As	OM	pH
Cr	1.000**
Cu	0.095	1.000**
Cd	0.223	0.011	1.000**
Pb	−0.094	0.079	0.211	1.000**
Hg	−0.156	−0.003	−0.103	0.346*	1.000**
As	−0.199	−0.185	−0.433**	0.381**	0.281*	1.000**
OM	0.123	0.634**	0.158	0.350*	0.314*	−0.274	1.000**
pH	0.191	0.095	−0.164	−0.501**	−0.247	−0.231	−0.385**	1.000**

*Correlation is significant at the 0.05 level.

**Correlation is significant at the 0.01 level.

Table 10. Results of PCA for sources of heavy metals.

	PC1	PC2	PC3
Eigenvalue	3.185	3.185	1.004
Of variance(%)	53.082	18.256	16.739
Cumulative(%)	53.082	71.338	88.077
Cr	−0.625	0.003	0.634
Cu	0.482	−0.243	0.752
Cd	0.082	0.975	0.165
Pb	0.930	0.249	0.057
Hg	0.880	−0.075	0.031
As	0.957	−0.131	−0.064