Locals in Ikoma awake to find the Tatsutagawa River has turned very verdant.

An interesting linguistic quirk of the Japanese language is that some of the things we’d call “green” in English are referred to in Japanese as being ao, which literally translates as “blue.” For example, the color of the trees in a dense forest is usually described as ao, as is the stoplight color that means “go.”

However, while ao usually means “blue” but can sometimes mean “green,” the standard word for “green,” midori, doesn’t have that same sort of flexibility. So when people in the town of Ikoma, Nara Prefecture, started calling city hall on Wednesday with reports that the Tatsutagawa River had turned midori, they meant green – and REALLY green.

For comparison, here’s what the Tatsutagawa River (which is also pictured at the top of this article) usually looks like,


Locals first noticed the waterway had acquired a fluorescent hue at around 5 in the morning, which isn’t long after the sun comes up in midsummer in Japan. Despite its antifreeze-like color, no noticeable chemical odors were reported.

Specialists from the municipal and prefectural government were dispatched and began searching upstream, tracing the strange color to Mochigawa, a smaller waterway which feeds into the Tatsutagawa River. There they found a reddish-brown substance on a section of the smaller river’s concrete embankment which, when washed with a high-pressure hose, dissolved into a liquid with the same bright green color that the river had turned downstream, as shown in the video below.

The subsequent investigation determined the substance to be fluorescein sodium, the sodium salt of fluorescein, an organic compound that acts as a dye. Because of its bright color, fluorescein sodium is used as adiagnostic aid in both optometry and plumbing, where it helps identify injuries to the cornea and retina as well as leaks in taps or pipes. It’s also an ingredient in certain bath powders and, according to Nara Women’s University food and nutrition professor Hitoshi Takamura, a safe and legally admissible food coloring.

No injuries or medical ailments have been reported as a result of the river’s sudden shift in color. The authorities are advising local farmers and home gardeners against using the river’s water to water their plants, however, and are continuing their investigation into how so much fluorescein sodium got onto the embankment/into the river in the first place, with the working theory that it was illegally dumped by someone.

Source: NHK News Web
Top image: Wikipedia/663highland
● Want to hear about SoraNews24’s latest articles as soon as they’re published? Follow us on Facebook and Twitter!