I was using this website for weather conditions around the world called Ventusky (https://www.ventusky.com/) and one of its features allows you to view SO2 concentration. I stumbled upon this high concentration of SO2 near Zhezkazgan in Kazakhstan (https://www.ventusky.com/?p=47.47;65.97;6&l=so2). I googled it but couldn't find anything. Satellite images show desert and mountains. Any ideas what could this be?