The Dal Lake in Srinagar is accumulating toxic heavy metals at alarming rates, with a recent study suggesting that within 35 years, arsenic levels could rise 239-fold, lead 76-fold, and mercury 100-fold.
Exposure to high concentrations of these metals—such as through consuming contaminated fish—poses severe health risks, including neurological damage and an increased likelihood of certain cancers. Researchers have noted that while current levels are concerning, they are not yet critical.
The study, conducted by scientists at the University of Kashmir, is among the first to project the future concentrations of these harmful metals in the lake. Although previous studies have highlighted pollution threats to the lake’s ecosystem, this research provides a long-term perspective on the problem.
Spanning 24 square kilometers and fed by five streams, Dal Lake is a major tourist attraction, offering boat rides, houseboat stays, and supporting local livelihoods and fisheries. However, environmental scientists have long been wary of the impact of untreated sewage, agricultural runoff, and industrial emissions, which contribute to the accumulation of heavy metals in the water body.
“Most previous studies provided a one-time snapshot of pollution levels in the lake,” said Shahnawaz Hassan, a research scholar from the university’s environmental science department. “Our study looks at how metal concentrations have changed over time and what the future might hold.”
To assess these changes, Hassan and his team collected sediment samples from the lakebed using specialized cylindrical extraction tools. Since sediment layers accumulate over centuries, the top layers reflect recent deposits, while the deeper layers represent older accumulations.
The study found that heavy metal concentrations were highest in the topmost layer, decreasing with depth. The lowest levels were observed in the deepest layers, dating back 3,700 years, indicating a consistent increase in metal deposits over time.
Currently, the top layer contains 0.92 micrograms of arsenic per gram of sediment, 64 micrograms per gram of lead, and 0.006 micrograms per gram of mercury. These findings were recently published in the journal Environmental Chemistry and Ecotoxicology.
Through time-trend analysis, the researchers projected that if the current accumulation rates persist, the concentrations of arsenic, lead, and mercury will reach hazardous levels within 35 years.
“Right now, the concentrations are concerning but not yet alarming. However, if left unchecked, they will reach dangerous thresholds in the coming decades,” Hassan warned. “We hope our findings will encourage further research to pinpoint the exact sources of heavy metal contamination and implement measures to curb it.”
Heavy metals such as lead and mercury can accumulate in fish tissues, affecting their reproductive abilities. Studies in lakes across Europe and North America have linked mercury contamination to declining fish populations due to reproductive failure.
These metals also pose risks to human health through bio-magnification, a process where metal concentrations increase as they move up the food chain. People consuming contaminated fish may experience severe health effects, including neurological damage, organ failure, developmental disorders, and a heightened risk of certain cancers.
To protect the lake’s ecosystem and public health, researchers emphasize the need for immediate action to identify and control heavy metal sources entering the lake.
