anchor.diff:              cff1=bw(i,iwO2_)*32.0d0/1000.0d0
               cff2=11.5d0*0.748d0**cff1
               cff3=cff2*1.02d0**(tsm(i,k)-20.0d0)
  -            !Kads(i,k,iwPO4)=poro(k)/(1.0d0-poro(k))/cff3
  +            !Kads(i,k,iwPO4)=poro(i,k)/(1.0d0-poro(i,k))/cff3
             END DO
   !
             DO itrc=1,NBGCPW
  
positive.code: !
  !  Secondary reactions (nmol cm-3 s-1)
  !
              cff1=(1.0d0-poro(k))*dens
  !
  !  - Re-oxydations of 
  !
             !R(6)=K06*poro(k)*pw(i,k,iwNH4)*pw(i,k,iwO2_)/(pw(i,k,iwO2_)+Ksnit) ! Wijsman
              R(6)=K06*poro(k)*pw(i,k,iwNH4)*pw(i,k,iwO2_) ! Fossing
              Rpw(iwNH4)=Rpw(iwNH4)-R(6)
              Rpw(iwO2_)=Rpw(iwO2_)-R(6)*2.0d0
              Rpw(iwNO3)=Rpw(iwNO3)+R(6)
  
negative.code: !
  !          DO itrc=1,NBGCPW
  !            DO k=1,Nbed-1
  !              cff1=porod(i,k)*usmd(i,k)
  !              cff2=dens*(1.0d0-porod(i,k))*usmd(i,k)*Kads(i,k,itrc)
  !              pwflux(i,k,itrc)=(cff1+cff2)*(pw(i,k,itrc)-pw(i,k+1,itrc))/dzd(i,k)
  !            END DO
  !            pwflux(i,Nbed,itrc)=pwflux(i,Nbed-1,itrc)
  