Brown shades of color in the air due nuclear radiation forming NO2, NO3 and nitric acid.
Read more: http://u2r2h-documents.blogspot.com/2007/01/wtc-poofed-from-space.html#ixzz6UBkuPZLQ
some search fu on the terms
nitric acid
uranium
extraction
nitric acid is used extracting uranium from ore and waste
were they concentrating uranium at the port?
were they dissolving it in solvents to ship it?
if it was a stockpile towards making a dirty bomb, would a clean bomb mostly vaporize it?