Every year, before the Chhath festival, images and videos of the Yamuna River in Delhi go viral, showcasing white foam floating on the surface. While it may appear visually striking, this foam is actually highly dangerous and toxic. Bathing in this water can lead to serious health issues. Despite this, people participating in Chhath continue to bathe in the river and conduct their rituals.
A thick layer of toxic foam has been observed on the surface of the Yamuna River near Kalindi Kunj in Delhi for several days, prompting the Delhi government to impose a ban on fishing in affected areas due to high pollution levels. So, what causes this phenomenon in the Yamuna River?
Historical Context of Foam Formation
The presence of toxic foam in the Yamuna is not a recent phenomenon. Each year during Chhath Puja, images of devotees standing in waist-deep foam make headlines. Notably, even the ancient Sanskrit poet Avaghosa referenced the foam in his poetry from the 1st century.
The Science Behind the Foam
Foam formation on water surfaces can occur naturally when dead plant matter creates a fatty layer that gets agitated by waves or waterfalls, similar to the bubbles in soapy water. While organic foam can last long, the excessive foam currently seen in the Yamuna cannot be attributed to these natural processes.
According to Sushmita Sengupta from the Centre for Science and Environment, high phosphate levels in the river are the primary cause of this foam. Phosphates, commonly found in detergents, reduce water’s surface tension and persist in the water, leading to eutrophication—a process that enriches water bodies with nutrients, promoting algae growth and depleting oxygen essential for aquatic life.
Phosphate Concentration and Pollution Sources
Raw sewage continuously flows into the Yamuna, carrying household and industrial detergents that often exceed the phosphate limits set by the Bureau of Indian Standards. A Delhi Pollution Control Committee report indicates phosphate concentrations ranging from 6.9 mg/l at Okhla to 13.42 mg/l at Khajoori Paltan.
Anshuman, a senior fellow at TERI, notes that agitation of water, caused by winds or rain, along with phosphate presence, leads to foam formation. The Okhla Barrage further churns the water, increasing foam accumulation downstream.
In healthy rivers, phosphates would typically dilute over time, allowing for natural cleansing. However, the high concentration in the Yamuna hampers this process, leading to persistent foam. Additionally, phosphates can irritate the skin, and the combination of sewage and other pollutants makes the foam potentially toxic.
This situation underscores the critical need for measures to combat pollution in the Yamuna, safeguarding both its ecosystem and the health of nearby communities.
