It looks like verdigris...
Verdigris is the common name for the green coating or patina formed when copper, brass or bronze is weathered and exposed to air or seawater over a period of time. It is usually a basic copper carbonate, but near the sea will be a basic copper chloride. (from wikipedia)
But it's not verdigris, it is iridescent green latex paint, a unique color created in part by Caltrans chemists in Sacramento to capture the original shimmering oil-based paint color of the bridge AND meet state environmental standards.
For more on the bridge color here.
For more green bridge pics visit Tash at Palos Verdes Daily Photo.