Assessment of Groundwater Quality along the Cooum River, Chennai, Tamil Nadu, India

Table 6

Statistics of three years (2009–2011) groundwater quality data—postmonsoon.

Postmonsoon
Parameter	Year	pH	EC; (μS/cm)	TDS; (mg/L)	BOD; (mg/L)	COD; (mg/L)	Na; (mg/L)	Pb; (mg/L)
	2009	7.7	2004	2605	8.97	23.7	313	0.081
Max	2010	7.7	2073	2673	8.39	24.3	300	0.08
	2011	7.75	2207	2716	8.25	24.6	310	0.083
	2009	6.7	508	905	4.3	10.3	120	0.03
Min	2010	6.6	557	981	4.37	10.9	127	0.03
	2011	6.7	567	993	4.46	11.3	133	0.03
	2009	7.222	1358.1	1873.35	6.6555	17.365	207.45	0.0528
Mean	2010	7.187	1422.35	1944.08	6.644	18.072	207.7	0.055
	2011	7.2545	1490.05	2007.3	6.755	18.645	216.3	0.0578
	2009	0.2658	453.16	574.18	1.25741	3.9141	56.049	0.014152
Std.	2010	0.29113	455.259	570.488	1.28389	3.987	58.448	0.01407
	2011	0.284225	465.6663	581.9234	1.268574	3.997562	58.22199	0.014413
	2009	3.680421	33.3672	30.64991	18.8928	22.54017	27.01808	26.80303
CV%	2010	4.050786	32.00752	29.34488	19.32405	22.06175	28.14059	25.58182
	2011	3.917913	31.25172	28.99036	18.77978	21.4404	26.91724	24.93599