Living in a lakeview apartment may not be as refreshing as realtors want one to believe. The water bodies emit several tonnes of greenhouse gases, thanks to sewage flow and dumping of waste.
A study by researchers from the Department of Environmental Science, Bangalore University, has shown that the annual CO2 emissions in six lake series, which are in turn connected to other lakes in a cascading manner, has gone up by more than half a tonne/year between 2017 and 2019.
Byramangala lake, which is in the Vrushabhavati valley, had the highest amount of CO2 emission. In the three-year period, the annual emission also increased from 8.1 to 8.8 tonnes. During this period, Varthur lake also witnessed a 7.7 tonne to 8.4 tonne increase in annual CO2 emission. In Yalemallappa Chetty lake, it went up from 6.9 to 7.5 tonnes.
Nandini N, professor and principal investigator at the department in Bangalore University, and the lead author of the study, said apart from CO2, methane, hydrogen sulfide and other gases are also emitted by lakes.
While low levels of such gases are produced in a normal situation, she said the flow of untreated sewage and dumping of garbage have exacerbated the situation. “Sewage water is rich in nutrients and toxic chemicals. It enhances algal growth and leads to eutrophication of the lake. Algae on decomposition settles at the bottom of the lake resulting in production of greenhouse gases, which will enter into the lake column resulting in alteration of regional climate.”
Long-term exposure to toxic gases can cause serious health issues. “This is particularly true for residents in the vicinity. It is important to stop the flow of untreated sewage to lakes. A detailed study is needed to understand the effects of emission of such gases from polluted water bodies,” she said.
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