42 rivers have extremely high concentration of neurotoxic heavy metals

India’s 42 rivers have at least two toxic heavy metals beyond the permissible limit, says a research conducted by Central Water Commission.

The study, which tested samples of river water collected from 16 river basins during three seasons—summer, winter and monsoon—found huge amount of lead in 69 rivers. The study also showed that most rivers (137) had iron beyond permissible limits.

While Ganga, the national river, was found to be polluted with five heavy metals—chromium, copper, nickel, lead and iron—six rivers–Arkavathi, Orsang, Rapti, Sabarmati, Saryu and Vaitarna—had unacceptably high concentration of four pollutants.

After testing samples collected from 414 stations setup along rivers, water at 136 stations was declared fit for use and at 168 stations were found unfit for drinking due to iron concentration in it.

This is worrying because a majority of Indians still use water directly from rivers for their domestic use. With an increase in population, the pressure on these rivers will only increase. According to the report, mining, milling, plating and surface finishing industries are the main sources of heavy metal pollution and the concentration of such toxic metals has increased rapidly over the past few decades.

“Consequently, concentrations of toxic metals in grains and vegetables grown in contaminated soils have increased at alarming rates. This poses a serious threat to humans and the environment because of its toxicity, non-biodegradability and bioaccumulation,” says the study released this week.

Other sources of metal pollution listed in the study are domestic wastewater effluents, storm water runoff from urbanised areas, industrial waste, sanitary landfill, agricultural runoff and fossil fuel combustion.

Corrective measures recommended

The CWC, in its report, also recommends that quality of water should be monitored at least four times a year. The autonomous body also suggests, “All the toxic metallic elements like chromium and its other associated heavy metals coming from the tanneries, mining and other industries should be treated chemically and biologically before such wastes find their way to River.”

Meanwhile, a data expert found a missing element from this 2018 report: mercury. “While CWC’s last report, which was released in 2014, did measure concentration of mercury in river water, it seems as if it chose to omit the metal from this year’s report. Is it too less or too much to mention?” questions the expert.

For more insights, grab your copy of State of India’s Environment in Figures 2018, India’s most authoritative annual data sets on state of environment and development  

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