Composition and origin of organic matter in surface sediments of Lake Sarbsko: A highly eutrophic and shallow coastal lake (northern Poland)

► First data on methanogenic potential of coastal lakes on the Polish coast. ► Composition of lake phytoplankton vs. planktonic biomarkers in sediments. ► Organic matter composition and preservation in oxygenated polymictic lake. ► Degradation of organic matter vs. composition of lake water.