This is is a great picture, beautiful even. Lovely dress and model....The only negative thing I have to say (and if I'm wrong someone please correct me) is that there seems to be a purple/violet film over the whole thing, which if there is I feel takes away from it. I would love to see this pic in normal lighting.
i think what you're seeing is natural light. but that the eye is throwing the purple onto everything , because i would bet money that the bridge is white, like the sky is blue if you really look at it.