"A modern day miracle occurs each year as part of the St. Patricks Day Parade celebration when the Chicago River turns an incredible shade of Irish green. This spectacular transformation ranks right up there with the parting of the sea by Moses and the Pyramids of Egypt."
Podcast
9 comments:
anyone know how to reduce the size of the pic?
When you insert the picture, you should be able to choose position and size (small, medium, large). If not, I guess you have to do it manually and upload.
In "compose" if you click on the pic you should get small squares around the pic click and drag the lower right hand side square and make it smaller. Good luck. :)
Sigma sells Fluorescein for $235 CAD/kilo. I wonder how many kilos they put in the Chicago River? Maybe a cash-starved cell biologist could recover some for their experiments...
Maybe Ben could collect some samples for us.
Acute fluorescein toxicity to turbot (Scophthalmus maximus) was investigated by exposing fish to different fluorescein concentrations (0.5, 0.7, 0.9, 1.1 and 1.3 milligrams) at 14.0 C for 24, 48 or 96 h. The lethal concentration inducing 50% fish mortality (LC50) was 997.1 +/- 11.4 mg/l (mean +/- standard deviation) after a 24, 48 or 96 h exposure. Toxicity affected the central nervous system. Early postmortem findings were a brown-green coloring of some tissues and encephalon congestion.
So maybe we don't even need water samples. One could simply count the percentage of dead fish in the water and then calculate the fluorescein concentration of the Chicago River based on the LD50 data.
They use vegetable dye. 40 pounds of it. It is non-toxic. They used to use an oil based chemical, but stopped in 1966 and switched to vegetable dye due to environmental concerns. These two websites talk about it.
http://illinois-travel.suite101.com/article.cfm/st_pats_green_river_in_chicago
http://www.pbase.com/tianphoto/chicago_river
On an interesting note, the vegetable dye is really orange. It just appears to be green when diluted in the river. The orange color of the dye is evident in the pictures on the above websites, where you see the workers pouring the dye into the river.
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