1. Environmental Monitoring and Compliance Branch, Environmental Services Division, U.S. E.P.A., Region VII, 25 Funston Road, Kansas City, Kansas 66115 (T.T.H., B.J.F., C.E.F., H.E.K. R.D.K., C.J.W.); and Computer Science Corporation, 25 Funston Road, Kansas City, Kansas 66115 (L.A.J., H.G.P.)