sapropel vs gunk

sapropel and gunk both are nouns.

Word	Noun	Adjective	Verb	Adverb
sapropel	Yes	No	No	No
gunk	Yes	No	No	No

As nouns, gunk is a hypernym of sapropel; that is, gunk is a word with a broader meaning than sapropel:

sapropel: sludge (rich in organic matter) that accumulates at the bottom of lakes or oceans
gunk: any thick, viscous matter

Other hypernyms of sapropel include goo, gook, goop, guck, muck, ooze, slime, sludge.

sapropel (noun)	gunk (noun)
sludge (rich in organic matter) that accumulates at the bottom of lakes or oceans	any thick, viscous matter