It seems it isn’t easy being green, especially if you are the Chicago River. For the last forty years they have been dyeing the water the brightest shade of emerald green to mark St Patrick’s Day. It isn’t your monitor playing up. The water really is that colour!
You would think as a fan of all things riverine I might object to pumping an artificial colour into a watercourse but legend has it that the tradition was actually a result of work to improve water quality in the city of Chicago. Tracer dyes are used to locate the sources of pollution and temporarily colour the water. The use of the bright green tracer dye that was used by the city prompted the somewhat lateral leap towards colouring every year. The dye that was originally used contained the now banned chemical fluorescein and the mix now used is a secret formula.
There is a great animation of the process here (with music)
The fountains at the White House were dyed green in 2009 in honour of Chicago born Michelle Obama.
Tracer systems have now progressed and it is even possible to use nanotechnology to determine the exact form of the pollutant but we don’t usually aim for such a drastic result!
Happy St Patrick’s Day!
Re, adding dye to waterways, the coast guards in US and probably world wide also add dye to the holding tanks of sail boats, to highlight any illegal discharges within the coastal limit. From what I have seen, in the scheme of things, this is actually a pointless and bullying tactic against a tiny minority of folks. As a private individual, you can get up to $5000 fine for emptying a 5 gallon holding tank in the wrong place. Fair enough, except, twice in a month the San Francisco Bay was flooded with hundreds of thousands of gallons of effluent discharged by mistake by the authorities – minimal fine! Also the yards are anal about eco rules for applying and disposing of bottom paint – it is copper based. (one good size private sail boat uses probably 2 gallons a year). You pay through the nose for disposal. Meanwhile, the US navy have yards in the same areas as private yards, where they apply their copper based bottom paint to boats by the hundreds of gallons. The public cant buy the Navy bottom paint because it is too toxic! Plus the NAvy have been observed actually applying that stuff in the water. Double standards and a really bad double standard at that. Can you tell I support the little guy!