Heavy metals in Veeranam lake, finds study on birds

CHENNAI: Veeranam lake, which supplies drinking water to Chennai, is highly contaminated with heavy metals. A study conducted by a group of researchers from Tamil Nadu, Saudi Arabia and the US institutions has found high accumulation of heavy metals in fish and water birds at the lake. The Chennai Metropolitan Water Supply and Sewerage Board (Metro Water) draws around 170 million litres of water daily from the lake for drinking water supply to the city.

Alarmingly, heavy metal contamination was found in the tissues of commonly consumed freshwater fishes like Tilapia and Rohu.

As per the research, the amount of metals such as lead, chromium, nickel, zinc, arsenic, copper and mercury found in the tissue, liver, kidney, feathers of waterbirds and their prey (fishes, crabs and others) exceeds the Indian (ISI) and the United States Environmental Protection Agency’s threshold values.

“According to the current research findings, the quantity of metals extracted from the lake is alarming, and adequate rules must be implemented to protect aquatic environments,” it said.

The researchers collected dead carcasses of Indian pond herons and black-crowned night heron birds around the lake and caught fishes and other prey at random locations in the lake. The analysis showed the prey species having accumulated metals in their tissue, and levels of metals in the carcasses of waterbirds positively correlated with the metals of their prey species.

Report highlights risks to humans, animals; calls for study on Veeranam pollution

The report pointed out that excessive build-up of lead will increase cellular stress and memory loss in birds. High levels of chromium will affect DNA and protein, which will negatively affect the inheritance of characters. Nickel will affect cellular communication and cause tumour development. Zinc and arsenic will result in malformations and physiological disorders respectively.

“The current investigation reveals an alarmingly high percentage of metals in the lake, which serves as a warning about its quality. Apart from supplying drinking water to the surrounding human population and Chennai, the lake irrigates hundreds of hectares of farmland,” the report pointed out.

The research added that the primary source of metals in the lake is the Cauvery River. “Along the Cauvery river are many small, medium, and large-scale enterprises, including tanneries, battery factories, and distilleries. In addition, the river conveys wastewater from the river basin’s communities. Additionally, the river is laden with sewage from the local panchayat, cities, and municipalities.”

Moreover, the Cauvery basin is renowned for its agricultural techniques, in which farmers apply enormous quantities of pesticides, fertilizers, and chemicals to seasonally cultivated crops.

“Nonetheless, the contaminated water harms both animal and human health, since the lake serves as a source of potable water for a substantial population. Globally, preserving a freshwater environment is essential for conserving aquatic-dependent biota,” the report said.

It called for a comprehensive study to improve the quality and management of aquatic habitats since they provide clean drinking water to human civilisation and serve as a habitat for many species of flora and fauna.