Survey Report on Heavy metal Pollution in Indian Rivers

In News

The Central Water Commission (CWC) has released a survey report on heavy metal pollution in Indian rivers. This is the third such survey conducted by CWC.

In-Detail

• The survey was conducted for the period between May 2014 to April 2018.
• As per the survey, almost all major rivers across the country have one or more heavy metals in excess than the prescribed limit of the Bureau of Indian Standards (BIS).
• Samples from two-thirds of water monitoring stations across major rivers contained one or more heavy metal contaminants.
• Only one-third of the samples from water quality stations were found to be safe.
• Of the 442 samples, 287 i.e., 65% of the samples are polluted by heavy metals.
• Samples from 101 stations had two metal contaminations and 6 stations had three metal contamination.
• The most common contaminant in 156 sampled sites was iron with levels above safe limits.
• Interestingly, none of the sites registered arsenic contamination in excess of the prescribed safe limits.
• Contamination from heavy metals like copper, nickel, cadmium, lead and chromium was also found in some samples.
• The study was conducted in 67 rivers across 20 river basins.
• While lead, cadmium, chromium, nickel and copper contamination was more common during the non-monsoon period, iron, lead, chromium and copper exceeded tolerance levels during the monsoon period.
• The study found that zinc and arsenic levels were always within the prescribed limits throughout the survey period and in all samples.

Contamination and Diseases

• The presence of heavy metals is unavoidable in drinking water.
• Trace amounts of these metals in water are beneficial for health. But, when present above safe limits, it leads to a range of diseases.
• Heavy exposure to these metals may lead to physical, muscular, and neurodegenerative diseases like Parkinson’s, Alzheimer’s, muscular dystrophy and multiple sclerosis.
• Common heavy metal contaminants are lead, cadmium, arsenic, iron, mercury, chromium, nickel, zinc, antimony and copper.

Other Findings

• The samples of the rivers are not equally taken. While in some rivers, the samples were taken at only a single site, in major rivers like the Ganga, the Yamuna and the Godavari, samples were taken at various sites.
• Seasonal variation in contamination levels was clearly identified in the survey.
• The samples were collected during pre-monsoon, monsoon and post-monsoon periods.

Sources of Heavy Metal Contamination

• The major sources of heavy metal contamination are mining, milling, plating and surface finishing industries that release a lot of heavy metal contaminants into the environment.