堆積 and 沈殿: Shelf Dust and Mud in a Bottle
Read accumulation on a riverbed or shelf alongside sediment settling in liquid. Compare the observed process, accumulated state, and settled result without confusing precipitation with rainfall.
Sand and dust accumulating
堆積 (たいせき) means sedimentation or accumulation. 「川底の砂の堆積を観察した。」 — “We observed sand accumulating on the riverbed.” The sentence reports an observation of sand accumulating on the riverbed.
「棚にほこりが堆積している。」 — “Dust has accumulated on the shelf.” Here the subject is dust on a shelf. 堆積している describes its accumulated state; no liquid is mentioned in this example.
Sediment settling in liquid
沈殿 (ちんでん) means sedimentation or precipitation. 「泥が瓶の底に沈殿した。」 — “Mud settled and formed sediment at the bottom of the bottle.” 沈殿した describes the result of mud settling and forming sediment at the bottle's bottom.
「液体を静かに置き、沈殿の様子を観察した。」 — “We left the liquid still and observed the sedimentation.” This sentence reports leaving a liquid still and observing sedimentation. Keep that observed process distinct from the settled result in the bottle example.
Follow the material and process
A shelf and the bottom of a bottle are both locations where material is found. Their locations alone do not make the examples the same process in liquid. Read the accumulated dust and the settled mud in their respective contexts.
The English gloss sedimentation appears for both words, and precipitation is also a gloss for 沈殿. In these examples, 沈殿 concerns material settling in liquid. Reading precipitation as rainfall would change the context of the sentences.
Do 「棚にほこりが堆積している。」 and 「泥が瓶の底に沈殿した。」 describe the same process in liquid?
Show the answer and why
No. The first describes dust accumulated on a shelf; the second describes mud that settled and formed sediment at the bottom of a bottle. Keep each material and process distinct rather than treating shelf dust as sediment settling in liquid.