Multivariate Analysis of Confined Groundwater Hydrochemistry of a Long-Exploited Sedimentary Basin in Northwest China

Table 1

Descriptive statistics of hydrochemistry in Yinchuan, China.

Parameters	Confined water					Phreatic water	National standard
Category	Minimum	Maximum	Mean	SD	CV	/	/
pH	8.06	8.43	8.21	0.16	0.02	7.57	6.5–8.5
TH	129	441	244	71	0.29	662	450
TDS	307	799	472	162	0.34	889	1,000
Ca^2+	11.5	94.1	44.4	19.8	0.45	111.5	—
Mg^2+	5.8	73	37.1	13.4	0.36	107.0	—
K^+	1.0	3.5	2.0	0.6	0.30	7.2	—
Na^+	27.2	168	75	48	0.64	147.0	200
	19.9	258	67	58	0.87	138.0	250
	17.7	175	84	45	0.54	294.0	250
	195	484	285	61	0.21	—	—
	0.0	2	0.1	0.4	3.46	17.9	20
	0.0	0.9	0.1	0.2	3.52	0.1	0.20
	0.1	0.7	0.2	0.1	0.66	1.3	1

Units: mg/L (except for pH).
“Phreatic water” is the quality of phreatic water located in the central of the depression cone.