According to a report published by the Central Water Commission in 2015 on the status of trace and toxic metals in Indian rivers in the country, a large number of rivers in India are contaminated by heavy metals. A survey done by the Agency for Toxic Substances and Disease Registry (ATSDR) has revealed that 70 percent of water in India is extensively contaminated by heavy metals and other contaminants [1, 2].
The paper, Heavy metal assessment in water and sediments at Jayakwadi dam (Godavari river), Maharashtra, India, published in International Journal of Environment, informs that the contamination of surface water sources such as rivers, lakes, ponds, dams and reservoirs from metals can often make the water non-potable due to the health hazards of consuming toxic metals.
Metals such as lead, arsenic, copper, cadmium, chromium, mercury and nickel are referred to as trace elements. These are normally found in low concentration in the environment. In increased concentration, these trace elements are capable of creating health problems and environmental issues [1].
The source of contamination
Certain industrial processes like mining play an important part in surface-water contamination. The industrial effluents and solid wastes containing metals get discharged into the water. The use of insecticides and pesticides in farms also introduce toxic metals to water. The health hazards of consuming these metals vary from poisoning to damage to the vital organs.
Keeping these hazards in mind, agencies like the Bureau of Indian Standards (BIS) and Indian Council of Medical Research (ICMR) have formulated drinking water standards for the use of humans, livestock and irrigation in India. Biological monitoring studies to evaluate the toxicity of various chemical compounds in water are essential so that preventive measure can be taken to ensure the safety of the environment and water [1].
Evaluation of Godavari water
The paper discusses the findings of a study on the presence of heavy metals in the water and in the sediments at the Jayakwadi dam on river Godavari in Marathwada. Godavari is the second longest river in India, originating in Maharashtra and flowing through Telangana, Andhra Pradesh, Chattisgarh, Madhya Pradesh, Odisha and Karnataka. It is dammed at Paithan in Marathwada. The Jayakwadi dam, constructed on the upper reaches of Godavari, is an important source of water for drinking, irrigation and fishing. The dam water, however, is exposed to pollution from the discharge of untreated sewage residues from small scale industries, automobile waste and surface runoff from the adjoining areas.
What the study found
To estimate the heavy metal concentration in Godavari’s water, the water as well as the sediment samples from the dam were collected in three different seasons--summer, winter and monsoon.
The study found that the sediments as well as the water had very high concentration of zinc, chromium, cadmium, mercury and lead. The content of mercury was the highest in the samples (15.24 - 18.21 µg/L), followed by lead (14.31 - 18.38 µg/L), cadmium (1.95 - 2.29 µg/L), chromium (0.68 - 4.00 µg/L) and finally zinc (0.88 - 1.77 µg/L).
The concentration of zinc and mercury were found to be the highest in summer because of the reduced level of water in the dam and the water from multiple sources like agricultural runoff, domestic activities, wastewater and effluent discharges reaching the dam. The concentration of heavy metals such as chromium, cadmium and lead were found to be high during the monsoon as the flowing river collects industrial effluents, solid wastes, pesticides from surrounding farms, industries and residences.
The paper ends by saying that the study is of considerable significance to the area since the dam on Godavari is the lifeline of the Marathwada region. It calls for further studies in the area and urgent remedial action to be taken for the safety of the population that depends on the water from the dam.
References:
1. Central Water Commission (2015) Status of Trace and Toxic Metals in Indian Rivers.
2. Ghorade, Lamture and Patil (2012) Assessment of heavy metal content in Godavari river water, IMPACT: International Journal of Research in Applied, Natural and Social Sciences, 2 (6), 23-26
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