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

Table 5

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

Premonsoon
Parameter	Year	pH	EC; (μS/cm)	TDS; (mg/L)	BOD; (mg/L)	COD; (mg/L)	Na; (mg/L)	Pb; (mg/L)
	2009	8.31	2173	2677	8.34	24.2	287	0.081
Max	2010	8.26	2296	2713	8.35	24.6	303	0.083
	2011	8.3	2371	2892	8.56	24.8	313	0.087
	2009	6.85	498	987	4.39	13.3	130	0.025
Min	2010	6.71	631	1048	4.24	11.1	137	0.03
	2011	7.04	583	1010	4.64	11.8	150	0.036
	2009	7.51	1355	1894.15	6.8135	18.73	219.75	0.0585
Mean	2010	7.4185	1515.95	2029	6.74	18.755	226.55	0.055
	2011	7.548	1523.75	2073.5	6.8995	19.72	230	0.0642
	2009	0.41391	570.724	575.614	1.27868	3.4278	53.18	0.01494
Std.	2010	0.44131	536.77	577.915	1.37405	4.0111	55.006	0.014567
	2011	0.36026	559.887	585.852	1.34849	3.9107	57.544	0.014468
	2009	5.51145	42.11985	30.38904	18.76686	18.30112	24.20023	25.53846
CV%	2010	5.9487	35.40816	28.48275	20.3865	21.38683	25.40013	26.48545
	2011	4.7729	36.74402	28.25426	19.54475	19.83114	25.01913	22.53583