INTRODUCTION:

Water is the fundamental element and it is linked up with the origin, evolution and undoubtedly the destiny of life. Next to oxygen, water essential substance for all living organism on earth and only a tiny proportion of the global freshwater is present in rivers.¹ Unfortunately rivers are perhaps the worst polluted freshwater ecosystem in earth. Most rivers in India are polluted and their water unfit for human use. Many rivers and water bodies are becoming saturated with organic compounds from industrial effluents, posing a major threat to both human health and aquatic life.² In the last few decades there had been an increasingly greater emphasis on the deterioration of the water quality of Indian rivers unmindfully used for the disposal of domestic and industrial wastes for beyond their assimilative capacities and have been rendered grossly polluted.^2-3

Pollution from domestic sewage, waste water discharge from industries and agricultural runoff etc., find their way into rivers, which can lead to large scale deterioration of water quality. The consequence of this is increased river pollution, loss of aquatic life and uptake of polluted water by plants and animals, which eventually gets into human body resulting in health related problems.⁴ The situation is compounded by the fact that the common man in most of the countries does not have access to portable water and in many instances; raw river water is used as source of drinking water. Untreated sewage discharge not only damage for aquatic life but also hazardous to human health used for drinking purpose in the downstream areas.⁵ In the wake of increasing urbanization and industrialization, the pollution potential of Vaigai River is gaining momentum day by day. The present study is an attempt to make an assessment of the change in the water quality of Vaigai River in Madurai

Study area

Madurai is situated in the South of Tamil Nadu state, India. The city is located on 9°48’ North longitude and 78°06’ East longitude. Madurai Municipal Corporation covering 51.82 km area has a total population of 1,462,420 persons (2011 Census). The city has grown on both sides of Vaigai River. The Vaigai River rises in the Periyar plateau of the Western Ghats in the state of Tamil Nadu and flows generally south to Madurai. The river flows 23 km in Madurai and the people which fall in the way of river dump wastes in the river; this has caused severe pollution in the river to the extent that its water is no more potable and is posing threat to the survival of aquatic flora and fauna. The sampling locations are spread throughout the study area. Ten different locations selected in the river are given in table 1.

Table 1: Name and station code of water samples collected in Vaigai River at Madurai

S.No	Station Code	Name of the Station
1	S1	Thuvariman
2	S2	Kochadai
3	S3	Nagu Nagar
4	S4	West Ponnagaram
5	S5	Thathaneri
6	S6	Sellur
7	S7	Poondhotam
8	S8	AV Bridge
9	S9	Theppakulam
10	S10	Vandiyur

MATERIALS AND METHODS:

The water samples were collected at 10 different stations in the month of May 2011. Water was always taken 45 to 60 cm depth from the surface of the water. The samples were brought up to the surface with minimum disturbance. A centigrade thermometer was used and the temperatures were noted at about 8 inch below the surface of the water, during the hours of collections. The samples were analyzed for the following physicochemical parameters viz., pH, electrical conductivity (EC), total dissolved solids (TDS), dissolved oxygen (DO), chemical oxygen demand (COD), total hardness (TH), total alkalinity (TA),calcium, magnesium, sodium, ﬂuoride, chloride, sulphate and nitrate. The standard methods and procedures were used for quantitative estimation of water quality parameters and followed as in, “Standard methods of analysis of water and waste water” (APHA).⁶

RESULTS AND DISCUSSION:

The standard permissible value prescribed by Bureau of Indian Standard ⁷ and World Health Organization⁸ are presented in table 2. The results of physicochemical analysis of the water samples are given table 3 and 4.

Temperature

Temperature of water may not be as important in pure water because of the wide range of temperature tolerance in aquatic life, but in polluted water, temperature can have profound effects on dissolved oxygen (DO) and biological oxygen demand (BOD).⁹ Water temperature of the studied site varied from 28.4^oC to 30.5^oC.Higher temperature during summer was due to greater heating.⁴

Turbidity

Turbidity in water is caused by suspended and colloidal matter such as clay, silt, finely divided organic and inorganic matter and other microscopic organisms. Turbidity is a measure of the dispersion of light in a column of water.¹⁰ In the present study turbidity has noted minimum of 9.4 NTU at S1 and maximum of 43.3 at S9. The drinking water limit for turbidity as prescribed by WHO are 2.5 NTU and Indian standards up to 5 NTU. This shows that the water is clearly in excess of drinking water turbidity standards.

Table- 2: Standard parameters for water characterization

S. No	Parameter	Standard Values
S. No	Parameter	BIS	WHO
1	pH	6.5-8.5	6.5-8.5
2	Specific Conductance (µmhos/cm)	750-2250	500
3	Turbidity (NTU)	5	2.5
4	Total dissolved solids (mg/l)	500	500
5	Dissolved oxygen(mg/l)	8	8
6	Chemical oxygen demand (mg/l)	10	10
7	Total alkalinity (mg/l)	200	250
8	Total hardness (mg/l)	300	500
9	Calcium (mg/l)	75	75
10	Magnesium (mg/l)	30	30
11	Sulphate (mg/l)	200	250
12	Chloride(mg/l)	250	250
13	Sodium(mg/l)	100	100
14	Potassium(mg/l)	12	10
15	Fluoride(mg/l)	1	1

pH is an important factor that determines the suitability of water for various purposes, including toxicity to animals and plants .The pH ranged from 7.7 to 8.6. It was found to be slightly acidic to slightly alkaline. The variation can be due to the exposure of river water to atmosphere, biological activities and temperature change.⁹ As per WHO standards ⁸ pH for aquatic life is in the range of 6.5 to 9.0 and for drinking purpose standard is 6.5 to 8.5. Irrigation water with a pH outside the normal range may cause, a nutritional imbalance .⁹ Except S10 the pH values of the other stations were found within the limit prescribed by WHO.

Table -3: Physical parameters of water samples collected in Vaigai River at Madurai

S. No	Station Code	S1	S2	S3	S4	S5	S6	S7	S8	S9	S10
1	Water Temperature ^oC	28.4	29.3	29.2	28.5	29.4	29.1	29.4	30.2	30.1	30.0
2	Appearance	C	C	B	C	G	G	G	G	G	G
3	Odour	OL	OL	OL	OL	OL	OL	OL	OL	OL	OL
4	Turbidity (NTU)	9.4	10.7	12.9	17.1	23.4	23.9	28.6	42.5	43.3	43.2
5	pH	7.7	7.9	8.1	8.0	8.1	8.4	8.6	8.4	8.5	8.6
6	EC (µmhos/cm)	208	298	490	621	878	892	912	923	898	879
7	DO (mg/l)	5.3	5.6	5.8	6.4	6.5	6.6	6.6	6.8	7.2	7.2

C – Clear; B – Brownish; G – Greenish; CL-Colourless; OL – Odourless

Table 4: Chemical parameters of water samples collected in Vaigai River at Madurai

S. No	Station Code	S1	S2	S3	S4	S5	S6	S7	S8	S9	S10
1	TDS	347	481	818	988	1395	1489	1528	1612	1598	1586
2	Alkalinity	84	109	194	226	312	309	356	312	298	327
3	T H	112	128	233	445	603	612	656	621	678	656
4	Ca²⁺	56	87	125	241	339	307	345	362	389	357
5	Mg²⁺	34	39	71	162	212	224	198	178	152	181
6	Na⁺	77	79	135	142	236	298	312	278	297	245
7	K⁺	13	17	28	34	65	59	62	46	54	58
8	NO₃^-	6.9	6.8	14.5	18.9	34.2	36.8	36.5	38.6	48.3	47.5
9	SO₄^2-	39	65	79	127	169	165	187	198	245	249
10	Cl^-	59	92	118	145	289	292	263	278	345	352
11	F^-	0.26	0.28	0.31	0.36	0.55	0.58	0.59	0.63	0.68	0.78
12	COD	4.4	4.8	5.1	7.9	13.8	21.2	23.2	24.8	25.9	28.8

Figure 1. pH of water samples collected in Vaigai River at Madurai

Electrical Conductivity

Conductivity is a measure of the ability of an aqueous solution to carry an electric current. This ability depends on the presence of ions, on their total concentration, mobility, and valence and on the temperature of measurement.¹⁰ In the present observation the electrical conductivity varied from 258µmhos/cm to 923 µmhos/cm. High EC values were observed for six sampling points namely S5 to S10 indicating the presence of high amount of dissolved inorganic substances in ionized form. High electrical conductivity indicates a larger quantity of dissolved minerals salts, thereby making it sour and unsuitable for drinking.

Figure 2. Electrical conductivity of the water samples collected in Vaigai River at Madurai

Dissolved Oxygen

Dissolved oxygen content is one of the most important factors in stream health. Its deficiency directly affects the ecosystem of a river due to bioaccumulation and biomagnifications. The oxygen content in water samples depends on a number of physical, chemical, biological and microbiological processes. In liquid waste, dissolved oxygen is the factor which determines whether the biological changes are brought about by aerobic or anaerobic organisms; it reflects the physical and biological processes prevailing in the water.¹² The DO concentrations varied from 5.3 mg/l to 7.2 mg/l. The values indicate relatively mild organic pollution.

Total Dissolved Solids

TDS is a measure of the solid materials dissolved in the river water. The concentration of TDS that are too high or too low may limit growth and lead to the death of the many aquatic life forms.¹³ In the present study TDS ranged from minimum of 347 mg/l at S1 and maximum of 1612 mg/ l at S8. Total dissolved solids analysis has great implications in the control of biological and physical waste water treatment processes. The largest amount of TDS adds to the highest turbidity and electrical conductivity. Except the sampling points S1and S2 all the other stations showed higher TDS values than the prescribed limit given by BIS and WHO.

Alkalinity

The Alkalinity of natural waters is due primarily to the salts of weak acids, although weak or strong bases may also contribute. Bicarbonate represents the major form of alkalinity, with that carbonate and hydroxide alkalinity also.It is the quantitative capacity of water sample to neutralize a strong acid to a designated pH.¹⁶ In the present study observed values ranged from 84 mg/l to 356 mg/l. Higher values can be attributed to the industrial effluents discharged into river and this may cause corrosion in water pipe lines.¹⁴ Total alkalinity values for all the investigated samples in S5 to S10 were found to be greater than the value prescribed by WHO and BIS, except samples from sampling points S1 to S4.

Total hardness

Hardness of water is an important consideration in determining the suitability of water for domestic and industrial uses. Although hard water has no known effect on health, but is unsuitable for domestic uses.¹⁵ It also forms heat insulating scales in the boilers reducing their efficiency. In the present study the observed values range from 112 mg/l to 678 mg/l. The values for sample from points S4 to S10 were higher than the prescribed limit.

Calcium

Calcium is directly related to hardness. In order of abundance, calcium is the fifth element which is commonly present in all water bodies where it usually comes from the leaching of rocks. Calcium is very essential for nervous system and for formation of bones and teeth.¹⁴ Calcium concentration ranged from 56 mg/l to 389 mg/l and found above permissible limit of BIS and WHO in stations S2 to S10.

Magnesium

Magnesium is also directly related to hardness. Magnesium content in the investigated water samples ranged from 34 mg/l to 224 mg/l which were found above BIS and WHO limit in all stations.

Figure 3. Total dissolved solids (mg/l) of the water samples collected in Vaigai River at Madurai

Figure 4. Concentration of Sodium and Chloride ion (mg/l) of the water samples collected in Vaigai River at Madurai

Sodium

Excess sodium in water produces the undesirable effects of changing soil properties and reducing soil permeability. The percentage of sodium is often taken important parameter indicating in deciding the suitability of water for irrigation. In the present study sodium value ranged from 77 mg/l to 312 mg/l. The values for sample from points S3 to S10 were higher than the prescribed limit.

Potassium

The major source of potassium in natural fresh water is weathering of rocks but the quantities increase in the polluted water due to disposal of waste water. Potassium content in the water samples varied from 13 mg/l to 65 mg/l.

Chloride

Chlorides occur naturally in all types of water. This is the most common inorganic anion present in water. High concentration of chloride is considered to be the indicators of pollution due to organic wastes of animal or industrial origin. Man and animals excrete high quantities of chloride; therefore it indicates sewage contamination.¹⁵ In the present study chloride value ranged from 59 mg/l to 352 mg/l. The values for sampling station S5 to S10 were higher than the prescribed limit. Higher chloride concentration in samples may be due to big discharge of sewage near the sampling sites.

Figure 5. Concentration of Calcium and Magnesium of the water samples collected in Vaigai River at Madurai

Fluoride

Fluoride concentration is an important aspect of hydro geochemistry, because of its impact on human health. Probable source of high fluoride in Indian water seems to be that during weathering and circulation of water in rock and soil. In the present study fluoride value ranged from 0.26 mg/l to 0.78 mg/l. The content of fluoride is found that within the prescribed limit.

Nitrate

Nitrate determination is important in assessing the potential biological productivity of surface waters. Increasing concentration of nitrogen compounds in river and reservoirs lead to eutrophication. The nitrate content in the study area varied in the range 6.8 mg/l to 48.3mg/l and found above the prescribed limit.

Sulphate

Sulphate content of natural waters is an important consideration in determining their suitability for public and industrial supplies. Discharge of industrial wastes and domestic sewage tends to increase its concentration.¹⁵ The sulphate concentration varied between 39 mg/l and 249 mg/l. The values for all samples found within the prescribed limit.

Chemical Oxygen Demand

Chemical oxygen demand (COD) is a measure of the oxidation of reduced chemicals in water. It is commonly used to indirectly measure the amount of organic compounds in water. The measure of COD determines the quantities of organic matter found in water.¹⁶ Chemical oxygen demand gives valuable information about the pollution potential of industrial effluents and domestic sewage. The COD values ranged from 4.4 mg/l to 28.8 mg/l. The highest values of COD indicates that most of the pollution in study area is caused by industrial effluents discharged by industrial units like bleaching and dyeing along the river banks and inside the river also. The values for sample from points S5 to S10 were higher than the prescribed limit.

CONCLUSION:

The analysis of the water quality parameters of river water from 10 different stations in Madurai city show that the pH, total alkalinity,sulphate,fluoride values are within permissible limits, the TDS, TH, chloride, sodium, magnesium, COD values of some stations were above the desirable limits. The above data on the water quality parameters of Vaigai river at Madurai city clearly showed that the river water, like many major rivers suffers heavy pollution potential and the study reveals that the quality of water is deteriorated very badly, as a result of addition of urban waste, which enters the river from both the banks during its course through the heart of Madurai city. Further, the raw sewage must be treated before it is discharged into the river stream. Inadequate water, sanitation and hygiene account for a large part of the burden of illness and death. Drinking and bathing in polluted water supplies are among the most common routes for the spread of infectious disease. Direct discharge of human and animal waste not only impairs the quality of water, but also affects the health of the people of downstream of Vaigai river were the same water is used for washing, bathing and drinking purposes.

REFERENCES:

1. Sawyer CN, Mc Carty PL and Parkin GF. Chemistry for Environmental Engineering. Mc Graw Hill Publication, New York.1994.

2. Singh Omkar, Kumar Vijay and Rai SP. Water quality aspects of some wells, springs and rivers in parts of the Udhampur district (JandK), Journal of Environmental Science Engineering. 47(1); 2005: 25-32.

3. Sivakumar AA, Arunadevi P and Aruchami M. Studies on water quality of the river Ambarapalayam, Coimbatore District, Tamil Nadu. Nature Environ. Poll. Tech. 2(3); 2003:305-308.

4. Abida B and Harikrishna. Study on the Quality of Water in Some Streams of Cauvery River, E-Journal of Chemistry. 5(2); 2008: 377-384.

5. Ahipathi MV and Puttaiah ET. Ecological Characteristics of Vishabhavathi River in Bangalore (India). Environmental Geology.40; 2006: 1217-1222.

6. APHA, AWWA, WPCF. Standard methods for the examination of water and wastewater, 20th edition. WashingtonDC, USA. American Public Health Association.1998.

7. Bureau of Indian Standard. Indian Standard Specification for Drinking Water. BIS Publication No. IS: 10501, New Delhi, 1991.

8. WHO Recommendations, Water and Sanitation. Guidelines for Drinking Water Quality, Vol.1. WHO Geneva.1984.

9. Nagaraju A, Suresh Sand Hudson-Edwards K. Hydro geochemistry of Waters of Mangampeta Barite Mining Area, Cuddapah Basin AndraPradesh, India. Turkish Journal of Engineering and Environmental Sciences. 30; 2006: 203-219.

10. Rajkumar S, Velmurugan P, Shanthi K and Lakshmanaperumalasamy P. Water Quality of Kodaikanal Lake, Tamilnadu in Relation to Physicochemical and Bacteriological Characteristics, Capital Publishing Company. 2004; 339-346.

11. Rajan MR and Paneerselvam I. Evaluation of drinking water quality in Dindigul city, Tamil Nadu. Indian Journal of Environment and Ecoplanning. 10(3); 2005: 771-776.

12. Matkar LS and Gangotri MS. Physicochemical analysis of sugar industrial effluents, Journal of Industrial Pollution Control. 18(2); 2002:139-144.

13. Shyamla R, Shanthi M and Lalitha P. Physicochemical Analysis of Bore well Water Samples of Telungupalayam Area in Coimbatore District, Tamilnadu, India, E-Journal of Chemistry. 5(4); 2008: 924-929.

14. Siamak Gholami and Srikantaswamy S.Analysis of Agricultural Impact on the Cauvery River Water around KRS Dam.World Applied Sciences Journal. 6(8); 2009:1157-1169.

15. Morisawa MC.River Forms and Processes, Longman Publishers, New York.1995.

16. Ashish Kumar and Yogendra Bahadur. Physicochemical studies on the pollution potential of River Kosi at Rampur, India.World Journal of Agricultural Sciences. 5(1); 2009:01-04.

Received on 06.08.2012 Modified on 16.08.2012

Asian J. Research Chem. 5(9): September, 2012; Page 1108-1112