A team of scientists from the Indian Institute of Technology (IIT) Kanpur has found that Ganga river can get rid of the heavy metal pollution by a minimum of 50 per cent in a short time span of a few months if industrial wastewater discharge is cut down for 51 days.

In contrast, inputs from agricultural runoff and domestic sewage like nitrate and phosphate remained almost the same as these sources were not impacted by the nationwide confinement.

Based on these observation, they  dismissed the general perception that the Covid-19 pandemic induced lockdown improved all water quality parameters of the Ganga river and instead asserted that the different pollutants should be considered individually.

Researchers in their article, titled “A Time-Series Record during COVID-19 Lockdown Shows the High Resilience of Dissolved Heavy Metals in the Ganga River,” said that they could quantify the impact of restricted anthropogenic activities on the water chemistry resilience of large rivers following Covid-19 induced lockdown with minimal human action.

In the normal times, it is estimated that industrial wastewater contributes nearly 20 per cent of the total volume of wastewater generated in the Ganga Basin.

The research was supported by the Indo-U.S. Science and Technology Forum (IUSSTF), a bilateral organization under the Department of Science and Technology (DST) and U.S. Department of States. It is published in ‘Environmental Science and Technology Letters.

“We therefore conclude that the Ganga river has a high resilience toward dissolved heavy metal concentrations and that the river system would revert toward pristine dissolved heavy metal concentrations in a short time span of a few months following reductions of industrial wastewater discharge,” said the team of scientists comprising Tanuj Shukla, Indra S Sen,  Soumita Boral and Sanjeet Sharma.

“We further emphasise that Covid-19 lockdown improved only the dissolved heavy metal load of the Ganga river, and not all the vital parameters of river water quality, as claimed previously,” they added.

“Therefore, the statement that the Covid-19 pandemic improved all water quality parameters of the Ganga river is incorrect, and the different pollutants should be considered individually,” the scientists asserted.