Assessment of Heavy Metal Pollution Characteristics andEcological Risk in Soils around a Rare Earth Mine in Gannan

Table 4

Characteristics of heavy metals in the soil surface layer of the study area.

Sampling time	Projects		Content (mg^−kg^−1) content (mg^−kg^−1)
	Projects		Mn	Cu	Cr	As	Cd	Ni	Pb	Zn
High water period	Minimum value		164	3.54	3.6	0.96	0.025	2.23	45.1	42
	Maximum value		1354	44.7	135.8	13.4	0.27	27.9	377.6	95
	Average value		448.97	18.92	30.33	3.00	0.14	13.13	92.99	64.18
	Standard deviation		239.75	9.33	22.44	1.80	0.58	6.40	47.36	11.00
	Coefficient of variation		53%	49%	74%	60%	414%	49%	51%	17%
Withered water period	Minimum value		126	1.16	5.09	1.02	0.113	<2	35.7	32.4
	Maximum value		1111.3	41.7	71	12.2	0.541	24.2	214	96
	Average value		471.12	16.48	27.28	3.12	0.26	11.97	94.01	61.07
	Standard deviation		289.18	9.31	15.36	1.61	0.09	5.63	35.90	12.52
	Coefficient of variation		61%	56%	56%	52%	35%	47%	38%	21%
Background values for topsoil in Ganzhou			243	15.17	34.56	8.85	0.09	12.35	34.19	58.05
Background values for topsoil in Jiangxi			259	20.8	48.0	10.4	0.10	19.0	32.1	69.0
Background values for topsoil in China			540	20.0	53.9	9.2	0.07	24.9	23.6	67.7