Sapropel waa magac tilmaamaya nooc ka mid ah kaydka sedimentary hodanka ah ee organic kaas oo ku urura xagga hoose ee biyaha macaan ama biyaha cusbada ah. Sapropel waxay caadi ahaan ka kooban tahay dhirta iyo walxaha bakhtiiyey, oo ay ku jiraan algae, plankton, iyo walxo kale oo dabiici ah, waxaana badanaa loo isticmaalaa sidii bacrimin ama qaboojiyaha ciidda. Erayga "sapropel" waxaa inta badan loo adeegsadaa si isku mid ah ereyga "dhoobo haro," waxaana caadi ahaan laga helaa qulqulka harooyinka, balliyada, iyo hareeraha.