--- MITgcm/pkg/dic/fe_chem.F	2003/10/02 18:30:07	1.1.2.1
+++ MITgcm/pkg/dic/fe_chem.F	2007/10/26 21:08:13	1.10
@@ -1,3 +1,6 @@
+C $Header: /home/ubuntu/mnt/e9_copy/MITgcm/pkg/dic/fe_chem.F,v 1.10 2007/10/26 21:08:13 dfer Exp $
+C $Name:  $
+
 #include "DIC_OPTIONS.h"
 #include "GCHEM_OPTIONS.h"
 
@@ -20,7 +23,6 @@
 #include "PARAMS.h"
 #include "GRID.h"
 #include "DIC_BIOTIC.h"
-#include "PTRACERS.h"
 
 C     == Routine arguments ==                
 C     bi, bj, iMin, iMax, jMin, jMax - Range of points for which calculation
@@ -30,8 +32,12 @@
       _RL  fe(1-OLx:sNx+OLx,1-OLy:sNy+OLy,Nr,nSx,nSy)
       INTEGER bi,bj,iMin,iMax,jMin,jMax
       INTEGER myIter,myThid
+#ifdef AD_SAFE
+      _RL thx, thy, theps
+#endif
 CEndOfInterface
 
+#ifdef ALLOW_FE
 
       INTEGER I,J,K
       _RL  lig, FeL
@@ -50,26 +56,41 @@
 C ligand balance in surface layer
 C in surface layer
 
-       DO j=jMin,jMax
-        DO i=iMin,iMax
-         DO k=1,nR
-          IF(hFacC(i,j,k,bi,bj) .gt. 0.0)THEN
+       DO j=jmin,jmax
+        DO i=imin,imax
+         DO k=1,Nr
+          IF (hFacC(i,j,k,bi,bj) .GT. 0. _d 0) THEN
 
 C   Ligand,FeL,Fe calculation
             
               lig=(-ligand_stab*fe (i,j,k,bi,bj)+
-     &              ligand_stab*ligand_tot-1
+     &              ligand_stab*ligand_tot-1. _d 0
      &             +((ligand_stab*fe (i,j,k,bi,bj)
-     &                -ligand_stab*ligand_tot+1)**2+4
-     &                *ligand_stab*ligand_tot)**0.5)/(2*ligand_stab)
+     &                -ligand_stab*ligand_tot+1. _d 0)**2
+     &               +4. _d 0*ligand_stab*ligand_tot)**0.5 _d 0
+     &            )/(2. _d 0*ligand_stab)
  
               FeL = ligand_tot-lig
               freefe(i,j,k,bi,bj) = fe (i,j,k,bi,bj)-FeL
+#ifdef MINFE
+#ifdef AD_SAFE
+              thx=freefe(i,j,k,bi,bj)
+              thy=freefemax
+              theps=1. _d -8
+              freefe(i,j,k,bi,bj) =
+     &                 ( 1. _d 0 - tanh((thx-thy)/theps) ) * thx/2.+
+     &                 ( 1. _d 0 + tanh((thx-thy)/theps) ) * thy/2.
+
+#else
+              freefe(i,j,k,bi,bj) = min(freefe(i,j,k,bi,bj),freefemax)
+#endif
+              fe(i,j,k,bi,bj) = FeL+freefe(i,j,k,bi,bj)
+#endif
           END IF  
          ENDDO
         ENDDO
        ENDDO    
 c
+#endif 
         RETURN
-        END                      
-
+        END