The activities, fluxes and inventories of ²¹⁰Pb and ¹³⁷Cs in sediments collected from freshwater lakes, brackish-water lakes and seabeds in the East Asia are studied to elucidate their geochemical behaviors and characteristics concerning sedimentation environments. The surface concentrations varied widely by location. The average flux of excess ²¹⁰Pb increased from freshwater lakes to brackish-water lakes to seawater, and the average flux of ¹³⁷Cs showed an inverse trend. The inventories of excess ²¹⁰Pb and ¹³⁷Cs were in good correlation in samples from the same lake or adjacent areas. The inventory ratio (¹³⁷Cs/excess ²¹⁰Pb) was in the order of samples from seawater, increasing in brackish-water, further increasing in freshwater, and samples from Chinese lakes showed higher values. It is inferred that the inventory ratio may become a kind of index of sedimentation environment, geological, and/or radiochemical events.