SUBROUTINE DWNFR1(FR,FR0,ID,IZZ,DW1)
C     ====================================
C
C     dissolved fraction for frequency FR
C
      INCLUDE 'IMPLIC.FOR'
      INCLUDE 'BASICS.FOR'
      INCLUDE 'MODELQ.FOR'
      PARAMETER (TKN=3.01,CKN=5.33333333,CB0=8.59d14)
      PARAMETER (SQFRH=5.734152D7)
C
      cb=cb0*bergfc
c
      IF(FR.LT.FR0) THEN
         XN=SQFRH*IZZ/SQRT(FR0-FR)
         if(xn.le.tkn) then
            xkn=un
          else
            xn1=un/(xn+un)
            xkn=ckn*xn*xn1*xn1
         end if
         BETA=CB*Z3(IZZ)*XKN/(XN*XN*XN*XN)*ELEC23(ID)
         BETA3=BETA*BETA*BETA
         BETA32=SQRT(BETA3)
         F=(DWC1(IZZ,ID)*BETA3)/(UN+DWC2(ID)*BETA32)
         DW1=UN-F/(UN+F)
       ELSE
         DW1=UN
      END IF
      RETURN
      END