Chhath puja devotees have to stand waist-deep amid thick and toxic froth while offering their prayers every year. This thick white foam floats over the Yamuna river. This has become a normal event. People wonder what is the main cause of this white foam over Yamuna river? Why does it happen only at a specific time of the year?
We know that soapy water forms a layer of bubbles by trapping air and the same might happen in case of Yamuna river.
Rivers have twigs, dead decaying plants and leaves. These things do not dissolve in water on decomposition, but break surface tension in water and create bubbles by allowing air to enter in it and eventually turns into a natural thin foam layer. But, all froth and foam is not natural.
So, what is the reason for the harmful or toxic layer of foam in the Yamuna river?
As per experts, high phosphates level from untreated effluents may be the main cause of frothing in Yamuna.
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Why does it happen only during October-November every year?
Senior Programme Manager of the Water Programme at the Centre for Science and Environment (CSE), Sushmita Sengupta, spoke to The Indian Express and explained the whole process.
She said that phosphates and surfactants are used in industries and households. They go in the Yamuna river throughout the year, but water flow in the river is less during winters, so these pollutants remain concentrated and form a thick layer of toxic foam.
This sprinkling of water is not helpful and phosphates level in rivers should be controlled. River water should be clean. A healthy and clean river can itself dilute the phosphates level.
This foam or presence of phosphates in water can lead to the algae growth that prevent sunlight and oxygen from mixing with water bodies that may be harmful for the ecosystem of the river.
Marine life may be destroyed due to this froth. Marine life helps maintain water quality of Yamuna river. Doctors also warned people that it may cause skin irritation if someone comes in direct contact with such water.
Who is responsible for keeping Yamuna clean in the area it foams?
The Delhi Jal Board – which comes under the Delhi government – has been stating that the location of frothing suggests that it does not come under DJP’s purview.
For now, the froth is only seen near Kalindi Kunj, which is downstream of the Okhla barrage. Speaking to The Indian Express, a senior official said that “if the sewage from Delhi was to blame, the frothing would have been seen across the entire stretch of the river.”
AAP MP Raghav Chadha, who is also vice-chairman of DJB, in a press conference on 8 November, said the Okhla barrage is maintained by the Irrigation Department of the Uttar Pradesh government.
“It must be that the load of pollutants is high at that point near Okhla, which is why we see the foam at that point,” Sengupta told the newspaper, adding that multiple stretches of the river are likely to be polluted.