Mapping saline water intrusion into the coastal aquifer with geophysical and geochemical techniques: the University of Lagos campus case (Nigeria)

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Table 1 pH, TDS, EC and macroelements contents (mg/L) of water samples obtained from boreholes and lagoon in the area

Physical parameter/major elements	Range	Mean	Standard deviation	Number of samples exceeding standards	Lagoon water	USEPA standards (2002,2009) (a, b, c, d)
pH	4.27-7.08	6.58	4.6	19	7.08	6.5-8.5^a,c
TDS	18-312	88.9	58.4	0	2000*	500^a,c
EC	37-630	178.7	117.8	0	3999
Ca	2.76-23.19	9.2	5.9	0	249
Mg	1.92-7.49	7.4	6.5	0	776
Na	19.42-164.68	56.8	39.4	0	6511	30^b-60^c
K	o.66-11.03	26.05	64.39	0	223
P	<0.02-0.16	0.059	0.041	0	2
S	1.0-34	9.44	7.96	0	596
Si	4.5-36.52	11.8	7.03	0	40
Cl	14-286	79	70.3	1	8976	250^b,c

a – USEPA maximum contaminant Level; b –USEPA Secondary Maximum Contaminant Level; c – National Primary Drinking Water Standard; * maximum recordable value of the instrument.