Italian officials stumped after patch of Venice's famed Grand Canal turns fluorescent green

Italian officials are stumped after a patch of Venice's famed Grand Canal turned a fluorescent green over the weekend.

Footage released by the Vigili del Fuoco, Italy’s national firefighters, shows a patch of Venice's famed Grand Canal turning a fluorescent green Sunday morning in the Rialto area.

Environmental officials with the Regional Agency for Environmental Protection and Prevention of Veneto said they are investigating alongside Venice's police and fire departments. 

Authorities said the green substance was present on the surface and soluble in the water. Samples were taken at different levels of the surface water body to evaluate how much of the substance tended to settle on the seabed.

Some samples were also carried out in the canals bordering the Rialto Bridge, where the anomalous substance gradually spread, also due to the effect of the tide.

A first analysis of the samples excludes the presence of substances dangerous for the environment, authorities said.



A fluorescent patch has colored part of the Grand Canal and the lagoon in Venice, Italy, green. (Vigili del Fuoco)

From previous experiences following similar events, the phenomenon has often been traced back to the use of fluorescein, according to officials. It's caused by the powdered tracer that dilutes in water and detects the proper functioning of a sewage system. 

Fluorescein is not dangerous for the aquatic environment and does not contain persistent, bioaccumulative and toxic components.

Under sunlight, fluorescein is able to dissolve after a few days depending on the quantity of powder used. More laboratory investigations will be carried out Monday, authorities said. 

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