The melting of the Himalayan glaciers are releasing pollutants, accumulated for decades, into the downstream ecosystems. A study in AGU’s Journal of Geophysical Research found that the chemicals used in pesticides have been accumulating in glaciers and ice sheets since the 1940s and are now released as the Himalayan glaciers are melting. The pollutants are ending in the Himalayan lakes affecting aquatic life including fish making it toxic for human consumption.
It can be seen that most remote places also can be repositories for pollutants and are not limited to a particular place. The glaciers contain the high levels of atmospheric pollutants due to their proximity to south Asian countries, home to some of the heavily polluted regions in the world.
Pollutants can travel long distances through atmosphere, dust and water and that ice sheets at the poles contain pollutants that have travelled long distances before falling onto the ice and being formed into glaciers. The phenomenon known as Arctic paradox is now seen in Himalayan glaciers.
On the central Tibetan Plateau between Gangdise-Nyainqȇntanglha mountains to the north and the Nyainqȇntanglha range to the south, lies Nam Co Basin which is home to 300 glaciers and that between 1999 and 2015 there have been almost 20 percent decrease in the volume of ice formation. Due to global warming, the glaciers are melting and releasing decades of accumulated pollutants into the ecosystem. Xiaoping Wang, a geochemist at Chinese Academy of Sciences, and his team have measured the concentration of the class of chemicals in pesticides called perfluoroalkyl acids(PFAAs) in glacial ice and snow, water runoff and in lake water in Nam Co Basin.
They found that glaciers release close to 1,342 milligrams per day into the lake and level of PFAAs in the lake as high as 2,172 picograms per liter. The estimated annual input of PFAAs into the lake is close to 1.81 kilograms per year. The influx of PFAAs can have an impact on aquatic life in the lakes and downstream. They have a long lifespan and do not regularly biodegrade and are passed down readily through organisms and ecosystems. The study does not include the toxic risk assessment of the levels on aquatic life but eating fish from this lake can be detrimental to human health. The accumulation potential of these chemicals in the body is extraordinary. The microorganisms and insect take up these molecules and get transferred into fishes and other predators and the contaminants keep getting higher up in concentration as well as the food chain.
The Nam Co Basin also feeds direct water into India. The study throws light upon the pollutants cycle around the globe. Similar studies have been conducted at the poles but as much information is not known as the pollutants in the Himalayas. The earth is a closed ecosystem and everything released on Earth stays on the planet.
Journal Reference: Journal of Geophysical Research