powdered green laver
Only when written 青粉
Dried and ground green seaweed (similar to aonori). The kanji 青粉 literally means 'blue/green powder'.
See also: 青のり
Sprinkling powdered green laver on food enhances the flavor.
blue-green algae; cyanobacteria
Refers to the microorganisms themselves, especially Microcystis. Usually written in katakana.
algal bloom; water bloom
The phenomenon of excessive growth of algae or cyanobacteria in water bodies. Often used interchangeably with 水の華.
See also: 水の華
When blue-green algae bloom, the water turns green and murky.
This summer, a large-scale algal bloom occurred in the lake.
Katakana spelling is standard for the algae and bloom senses, and common for the powdered laver sense.
Kanji spelling for the powdered green laver sense; rarely used in modern writing.
From 青 (ao, 'blue/green') + 粉 (ko, 'powder') for the powdered seaweed sense. The algae sense is an extension of the color and appearance, but the exact derivation is uncertain.