Red-blooded evidence - creation.com
They themselves reference to:
Burtis, C.A., Ashwood, E.R., Clinical Chemistry, W.B. Saunders Company, Philadelphia, 1994 edition.
Baselt, R.C., and Cravey, R.H., Disposition of toxic drugs and chemicals in Man, Year Book Medical Publishers, Inc, Chicago, 1989 edition.
For blood chemistry, and:
The New Encyclopedia Britannica, 15:925, 15th Ed., 1992.
for seawater chemistry.
Anyways, as they say in the article, this argument should make little sense even for a proponent of evolution. Amphibians came out of the water like 350M years ago. Does anyone expect that seawater back then will have the same chemistry as right now ? Surely not, so whoever thought of comparing our blood with current water proportions had a flawed reasoning from the outset.