ecearth3/sources/nemo-3.6/CONFIG/ORCA1L75_OFF_PISCES_standalone/MY_SRC/p4zsed.F90

MODULE p4zsed
   !!======================================================================
   !!                         ***  MODULE p4sed  ***
   !! TOP :   PISCES Compute loss of organic matter in the sediments
   !!======================================================================
   !! History :   1.0  !  2004-03 (O. Aumont) Original code
   !!             2.0  !  2007-12 (C. Ethe, G. Madec)  F90
   !!             3.4  !  2011-06 (C. Ethe) USE of fldread
   !!             3.5  !  2012-07 (O. Aumont) improvment of river input of nutrients 
   !!----------------------------------------------------------------------
#if defined key_pisces
   !!----------------------------------------------------------------------
   !!   'key_pisces'                                       PISCES bio-model
   !!----------------------------------------------------------------------
   !!   p4z_sed        :  Compute loss of organic matter in the sediments
   !!----------------------------------------------------------------------
   USE oce_trc         !  shared variables between ocean and passive tracers
   USE trc             !  passive tracers common variables 
   USE sms_pisces      !  PISCES Source Minus Sink variables
   USE p4zsink         !  vertical flux of particulate matter due to sinking
   USE p4zopt          !  optical model
   USE p4zlim          !  Co-limitations of differents nutrients
   USE p4zsbc          !  External source of nutrients 
   USE p4zint          !  interpolation and computation of various fields
   USE iom             !  I/O manager
   USE prtctl_trc      !  print control for debugging

   IMPLICIT NONE
   PRIVATE

   PUBLIC   p4z_sed  
   PUBLIC   p4z_sed_alloc
 

   !! * Module variables
   REAL(wp), PUBLIC, ALLOCATABLE, SAVE, DIMENSION(:,:,:) :: nitrpot    !: Nitrogen fixation 
   REAL(wp), PUBLIC, ALLOCATABLE, SAVE, DIMENSION(:,:  ) :: sdenit     !: Nitrate reduction in the sediments
   REAL(wp) :: r1_rday                  !: inverse of rday

   !!* Substitution
#  include "top_substitute.h90"
   !!----------------------------------------------------------------------
   !! NEMO/TOP 3.3 , NEMO Consortium (2010)
   !! $Id: p4zsed.F90 9241 2018-01-16 12:59:31Z cetlod $ 
   !! Software governed by the CeCILL licence (NEMOGCM/NEMO_CeCILL.txt)
   !!----------------------------------------------------------------------
CONTAINS

   SUBROUTINE p4z_sed( kt, knt )
      !!---------------------------------------------------------------------
      !!                     ***  ROUTINE p4z_sed  ***
      !!
      !! ** Purpose :   Compute loss of organic matter in the sediments. This
      !!              is by no way a sediment model. The loss is simply 
      !!              computed to balance the inout from rivers and dust
      !!
      !! ** Method  : - ???
      !!---------------------------------------------------------------------
      !
      INTEGER, INTENT(in) ::   kt, knt ! ocean time step
      INTEGER  ::   ji, jj, jk, ikt
#if ! defined key_sed
      REAL(wp) ::   zrivalk, zrivsil, zrivno3
#endif
      REAL(wp) ::  zwflux, zfminus, zfplus
      REAL(wp) ::  zlim, zfact, zfactcal
      REAL(wp) ::  zo2, zno3, zflx, zpdenit, z1pdenit, zolimit
      REAL(wp) ::  zsiloss, zcaloss, zws3, zws4, zwsc, zdep, zwstpoc
      REAL(wp) ::  ztrfer, ztrpo4, zwdust, zlight
      !
      CHARACTER (len=25) :: charout
      REAL(wp), POINTER, DIMENSION(:,:  ) :: zpdep, zsidep, zwork
      REAL(wp), POINTER, DIMENSION(:,:  ) :: zsedcal, zsedsi, zsedc
      REAL(wp), POINTER, DIMENSION(:,:  ) :: zdenit2d, zironice, zbureff
      REAL(wp), POINTER, DIMENSION(:,:  ) :: zwsbio3, zwsbio4, zwscal
      REAL(wp), POINTER, DIMENSION(:,:  ) :: zfesupply, znsupply
      REAL(wp), POINTER, DIMENSION(:,:,:) :: zirondep, zsoufer

      !!---------------------------------------------------------------------
      !
      IF( nn_timing == 1 )  CALL timing_start('p4z_sed')
      !
      IF( kt == nittrc000 .AND. knt == 1 )   r1_rday  = 1. / rday
      !
      ! Allocate temporary workspace
      CALL wrk_alloc( jpi, jpj, zdenit2d, zbureff, zwork )
      CALL wrk_alloc( jpi, jpj, zsedcal,  zsedsi, zsedc  )
      CALL wrk_alloc( jpi, jpj, zwsbio3, zwsbio4, zwscal )
      CALL wrk_alloc( jpi, jpj, zfesupply, znsupply      )
      CALL wrk_alloc( jpi, jpj, jpk, zsoufer )
      !
      zdenit2d (:,:) = 0._wp
      zbureff  (:,:) = 0._wp
      zsedsi   (:,:) = 0._wp
      zsedcal  (:,:) = 0._wp
      zsedc    (:,:) = 0._wp
      zwork    (:,:) = 0._wp

     

!!!!Begin EC-Earth modification for mass conservation of carbon. Author Raffaele Bernardello, January 2019
! 
!   We don't get satisfying mass conservation for passive tracers in NEMO. Drift in total mass is of 
!   the order of a few thousandths/year. Over a long spinup (thousands of years) this results in a drift of 
!   several points %. After much researching and asking around it seems we are not the only ones with this problem 
!   however, we haven't been able to find the reason. We need a workaround in order to run the ocean spinup needed for 
!   CMIP6. Unlike other tracers, DIC does not have a total mass correction available in PISCES 
!   code. So we are creating one here. Other tracers (NO3, Alk, PO4) are periodically adjusted in total mass to conserve 
!   the initial amount. This can't be done with DIC because the spun-up state will be used to run transient simulations
!   with increase of atmospheric CO2 and consequent ocean uptake. So, the ocean DIC needs to be trully equilibrated.
!   
!   Here, we compute the total amount of C in the ocean at the beginning of the leg. Then we do the same at the end 
!   of the leg. Plus, we consider the accumulated air-sea co2 flux, sedimentation of C and Cal, and river input during the leg. 
!   The change in internal mass has to equal the sum of sink and sources. The residual is used to compute a homogeneous 
!   global correction to be applied uniformly everywhere to DIC. 
!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!
! initialize cumulative sedimentation
!      IF( kt == nittrc000 ) THEN 
!        zsedc_cum = 0._wp
!      END IF               !already initializes in p4zsms.F90
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
      ! Iron input/uptake due to sea ice : Crude parameterization based on Lancelot et al.
      ! ----------------------------------------------------
      IF( ln_ironice ) THEN  
         !                                              
         CALL wrk_alloc( jpi, jpj, zironice )
         !                                              
         DO jj = 1, jpj
            DO ji = 1, jpi
               zdep    = rfact2 / fse3t(ji,jj,1)
               zwflux  = fmmflx(ji,jj) / 1000._wp
               zfminus = MIN( 0._wp, -zwflux ) * trb(ji,jj,1,jpfer) * zdep
               zfplus  = MAX( 0._wp, -zwflux ) * icefeinput * zdep
               zironice(ji,jj) =  zfplus + zfminus
            END DO
         END DO
         !
         tra(:,:,1,jpfer) = tra(:,:,1,jpfer) + zironice(:,:) 
         ! 
         IF( lk_iomput ) THEN  
            IF( knt == nrdttrc .AND. iom_use( "Ironice" ) ) THEN 
               zwork(:,:) = zironice(:,:) * 1.e+3 * rfact2r * fse3t(:,:,1) * tmask(:,:,1) 
               CALL iom_put( "Ironice", zwork(:,:) ) ! iron flux from ice
            ENDIF
            IF( iom_use( "IronSupply" ) ) THEN
                CALL wrk_alloc( jpi, jpj, zfesupply )
                zfesupply(:,:) = 0._wp
                zfesupply(:,:) = zfesupply(:,:) + zironice(:,:) * 1.e+3 * rfact2r * fse3t(:,:,1) * tmask(:,:,1)
            ENDIF
         ENDIF
         !
         CALL wrk_dealloc( jpi, jpj, zironice )
         !                                              
      ENDIF

      ! Add the external input of nutrients from dust deposition
      ! ----------------------------------------------------------
      IF( ln_dust ) THEN
         !                                              
         CALL wrk_alloc( jpi, jpj,      zpdep, zsidep )
         CALL wrk_alloc( jpi, jpj, jpk, zirondep      )
         !                                              ! Iron and Si deposition at the surface
         IF( ln_solub ) THEN
            zirondep(:,:,1) = solub(:,:) * dust(:,:) * mfrac * rfact2 / fse3t(:,:,1) / 55.85 + 3.e-10 * r1_ryyss 
         ELSE
            zirondep(:,:,1) = dustsolub  * dust(:,:) * mfrac * rfact2 / fse3t(:,:,1) / 55.85 + 3.e-10 * r1_ryyss 
         ENDIF
         zsidep(:,:) = 8.8 * 0.075 * dust(:,:) * mfrac * rfact2 / fse3t(:,:,1) / 28.1 
         zpdep (:,:) = 0.1 * 0.021 * dust(:,:) * mfrac * rfact2 / fse3t(:,:,1) / 31. / po4r 
         !                                              ! Iron solubilization of particles in the water column
         !                                              ! dust in kg/m2/s ---> 1/55.85 to put in mol/Fe ;  wdust in m/j
         zwdust = 0.03 * rday / ( wdust * 55.85 ) / ( 270. * rday )
         DO jk = 2, jpkm1
            zirondep(:,:,jk) = dust(:,:) * mfrac * zwdust * rfact2 * EXP( -fsdept(:,:,jk) / 540. )
         END DO
         !                                              ! Iron solubilization of particles in the water column
         tra(:,:,1,jppo4) = tra(:,:,1,jppo4) + zpdep   (:,:)
         tra(:,:,1,jpsil) = tra(:,:,1,jpsil) + zsidep  (:,:)
         tra(:,:,:,jpfer) = tra(:,:,:,jpfer) + zirondep(:,:,:) 
         ! 
         IF( lk_iomput ) THEN
            IF( knt == nrdttrc ) THEN
                IF( iom_use( "Irondep" ) ) THEN 
                   zwork(:,:) = zirondep(:,:,1) * 1.e+3 * rfact2r * fse3t(:,:,1) * tmask(:,:,1) 
                   CALL iom_put( "Irondep", zwork(:,:) ) ! surface downward dust depo of iron
                ENDIF
                IF( iom_use( "pdust" ) )  THEN
                   zwork(:,:) = dust(:,:) / ( wdust * rday )  * tmask(:,:,1) 
                   CALL iom_put( "pdust"  , zwork(:,:) ) ! dust concentration at surface
                ENDIF
            ENDIF
            IF( iom_use("IronSupply" ) )   &
              & zfesupply(:,:) = zfesupply(:,:) + zirondep(:,:,1) * 1.e+3 * rfact2r * fse3t(:,:,1) * tmask(:,:,1)
         ELSE                                    
            IF( ln_diatrc )  &
              &  trc2d(:,:,jp_pcs0_2d + 11) = zirondep(:,:,1) * 1.e+3 * rfact2r * fse3t(:,:,1) * tmask(:,:,1)
         ENDIF
         !
         CALL wrk_dealloc( jpi, jpj,      zpdep, zsidep )
         CALL wrk_dealloc( jpi, jpj, jpk, zirondep      )
         !                                              
      ENDIF
     
      ! Add the external input of nutrients from river
      ! ----------------------------------------------------------
      IF( ln_river ) THEN
         DO jj = 1, jpj
            DO ji = 1, jpi
               DO jk = 1, nk_rnf(ji,jj)
                  tra(ji,jj,jk,jppo4) = tra(ji,jj,jk,jppo4) +  rivdip(ji,jj) * rfact2
                  tra(ji,jj,jk,jpno3) = tra(ji,jj,jk,jpno3) +  rivdin(ji,jj) * rfact2
                  tra(ji,jj,jk,jpfer) = tra(ji,jj,jk,jpfer) +  rivdic(ji,jj) * 5.e-5 * rfact2
                  tra(ji,jj,jk,jpsil) = tra(ji,jj,jk,jpsil) +  rivdsi(ji,jj) * rfact2
                  tra(ji,jj,jk,jpdic) = tra(ji,jj,jk,jpdic) +  rivdic(ji,jj) * rfact2
                  tra(ji,jj,jk,jptal) = tra(ji,jj,jk,jptal) +  ( rivalk(ji,jj) - rno3 * rivdin(ji,jj) ) * rfact2
               ENDDO
            ENDDO
         ENDDO
         !
         IF( lk_iomput ) THEN
             !
            IF( iom_use("IronSupply" ) )  &
               & zfesupply(:,:) = zfesupply(:,:) + rivdic(:,:) * 5.e-5 * rfact2 * tmask(:,:,1)
            !
            IF( iom_use("NitrSupply" ) ) THEN 
                CALL wrk_alloc( jpi, jpj, znsupply )
                znsupply(:,:) = 0._wp
                znsupply(:,:) = znsupply(:,:)  + rivdin(:,:) * rfact2 * tmask(:,:,1)
            ENDIF
            !
            IF( knt == nrdttrc ) THEN
               IF( iom_use( "rivDIC"  ) )  CALL iom_put( "rivDIC" , rivdic(:,:) * tmask(:,:,1) )
               IF( iom_use( "rivTAlk" ) )  CALL iom_put( "rivTAlk", rivalk(:,:) * tmask(:,:,1) )
               IF( iom_use( "rivNO3"  ) )  CALL iom_put( "rivNO3" , rivdin(:,:) * tmask(:,:,1) )
               IF( iom_use( "rivPO4"  ) )  CALL iom_put( "rivPO4" , rivdip(:,:) * tmask(:,:,1) )
               IF( iom_use( "rivIron" ) )  CALL iom_put( "rivIron", rivdic(:,:) * 5.e-5 * tmask(:,:,1) )
               IF( iom_use( "rivSi"   ) )  CALL iom_put( "rivSi"  , rivdsi(:,:) * tmask(:,:,1) )
            ENDIF
         ENDIF
         !
      ENDIF
      
!!!!Begin EC-Earth modification for mass conservation of carbon. Author Raffaele Bernardello, April 2019
!
!keep track of actual amount of dic coming from rivers
      riverdicsum=riverdicsum+glob_sum(rivdic(:,:)*e1e2t(:,:)*h_rnf(:,:))*1.E3*rfact2
!!!!End of EC-Earth modification

      ! Add the external input of nutrients from nitrogen deposition
      ! ----------------------------------------------------------
      IF( ln_ndepo ) THEN
         tra(:,:,1,jpno3) = tra(:,:,1,jpno3) + nitdep(:,:) * rfact2
         tra(:,:,1,jptal) = tra(:,:,1,jptal) - rno3 * nitdep(:,:) * rfact2
         !
         IF( iom_use( "NitrSupply" ) )  &
           &  znsupply(:,:) = znsupply(:,:) + nitdep(:,:) * rfact2
         !
      ENDIF

      ! Add the external input of iron from sediment mobilization
      ! ------------------------------------------------------
      IF( ln_ironsed ) THEN
         tra(:,:,:,jpfer) = tra(:,:,:,jpfer) + ironsed(:,:,:) * rfact2
         !
         IF( lk_iomput .AND. knt == nrdttrc .AND. iom_use( "Ironsed" ) )  &
            &   CALL iom_put( "Ironsed", ironsed(:,:,:) * 1.e+3 * tmask(:,:,:) ) ! iron inputs from sediments
         !
         IF( iom_use( "IronSupply" ) ) THEN 
            DO jk = 1, jpkm1
               zfesupply(:,:) = zfesupply(:,:) + ironsed(:,:,jk) * 1.e+3 * tmask(:,:,jk) * fse3t(:,:,jk)
            ENDDO 
         ENDIF
         !
      ENDIF

      ! Add the external input of iron from hydrothermal vents
      ! ------------------------------------------------------
      IF( ln_hydrofe ) THEN
         tra(:,:,:,jpfer) = tra(:,:,:,jpfer) + hydrofe(:,:,:) * rfact2
         !
         IF( lk_iomput .AND. knt == nrdttrc .AND. iom_use( "HYDR" ) )   &
            &   CALL iom_put( "HYDR", hydrofe(:,:,:) * 1.e+3 * tmask(:,:,:) ) ! hydrothermal iron input
         !
         IF( iom_use( "IronSupply" ) ) THEN 
            DO jk = 1, jpkm1
              zfesupply(:,:) = zfesupply(:,:) + hydrofe(:,:,jk) * 1.e+3 * tmask(:,:,jk) * fse3t(:,:,jk)
            ENDDO  
         ENDIF
         !
      ENDIF

      ! OA: Warning, the following part is necessary, especially with Kriest
      ! to avoid CFL problems above the sediments
      ! --------------------------------------------------------------------
      DO jj = 1, jpj
         DO ji = 1, jpi
            ikt  = mbkt(ji,jj)
            zdep = fse3t(ji,jj,ikt) / xstep
            zwsbio4(ji,jj) = MIN( 0.99 * zdep, wsbio4(ji,jj,ikt) )
            zwscal (ji,jj) = MIN( 0.99 * zdep, wscal (ji,jj,ikt) )
            zwsbio3(ji,jj) = MIN( 0.99 * zdep, wsbio3(ji,jj,ikt) )
         END DO
      END DO

#if ! defined key_sed
      ! Computation of the sediment denitrification proportion: The metamodel from midlleburg (2006) is being used
      ! Computation of the fraction of organic matter that is permanently buried from Dunne's model
      ! -------------------------------------------------------
      DO jj = 1, jpj
         DO ji = 1, jpi
           IF( tmask(ji,jj,1) == 1 ) THEN
              ikt = mbkt(ji,jj)
# if defined key_kriest
              zflx =    trb(ji,jj,ikt,jppoc) * zwsbio3(ji,jj)    * 1E3 * 1E6 / 1E4
# else
              zflx = (  trb(ji,jj,ikt,jpgoc) * zwsbio4(ji,jj)   &
                &     + trb(ji,jj,ikt,jppoc) * zwsbio3(ji,jj) )  * 1E3 * 1E6 / 1E4
#endif
              zflx  = LOG10( MAX( 1E-3, zflx ) )
              zo2   = LOG10( MAX( 10. , trb(ji,jj,ikt,jpoxy) * 1E6 ) )
              zno3  = LOG10( MAX( 1.  , trb(ji,jj,ikt,jpno3) * 1E6 * rno3 ) )
              zdep  = LOG10( fsdepw(ji,jj,ikt+1) )
              zdenit2d(ji,jj) = -2.2567 - 1.185 * zflx - 0.221 * zflx**2 - 0.3995 * zno3 * zo2 + 1.25 * zno3    &
              &                + 0.4721 * zo2 - 0.0996 * zdep + 0.4256 * zflx * zo2
              zdenit2d(ji,jj) = 10.0**( zdenit2d(ji,jj) )
              !
              zflx = (  trb(ji,jj,ikt,jpgoc) * zwsbio4(ji,jj)   &
                &     + trb(ji,jj,ikt,jppoc) * zwsbio3(ji,jj) ) * 1E6
              zbureff(ji,jj) = 0.013 + 0.53 * zflx**2 / ( 7.0 + zflx )**2
           ENDIF
         END DO
      END DO 

#endif

      ! This loss is scaled at each bottom grid cell for equilibrating the total budget of silica in the ocean.
      ! Thus, the amount of silica lost in the sediments equal the supply at the surface (dust+rivers)
      ! ------------------------------------------------------
#if ! defined key_sed
      zrivsil =  1._wp - sedsilfrac
#endif

      DO jj = 1, jpj
         DO ji = 1, jpi
            ikt  = mbkt(ji,jj)
            zdep = xstep / fse3t(ji,jj,ikt) 
            zws4 = zwsbio4(ji,jj) * zdep
            zwsc = zwscal (ji,jj) * zdep
# if defined key_kriest
            zsiloss = trb(ji,jj,ikt,jpgsi) * zws4
# else
            zsiloss = trb(ji,jj,ikt,jpgsi) * zwsc
# endif
            zcaloss = trb(ji,jj,ikt,jpcal) * zwsc
            !
            tra(ji,jj,ikt,jpgsi) = tra(ji,jj,ikt,jpgsi) - zsiloss
            tra(ji,jj,ikt,jpcal) = tra(ji,jj,ikt,jpcal) - zcaloss
#if ! defined key_sed
            tra(ji,jj,ikt,jpsil) = tra(ji,jj,ikt,jpsil) + zsiloss * zrivsil 
            ! Loss of biogenic silicon, Caco3 organic carbon in the sediments. 
            ! The factor for calcite comes from the alkalinity effect
            ! -------------------------------------------------------------
            zfactcal = MIN( excess(ji,jj,ikt), 0.2 )
            zfactcal = MIN( 1., 1.3 * ( 0.2 - zfactcal ) / ( 0.4 - zfactcal ) )
            zrivalk  =  sedcalfrac * zfactcal
            tra(ji,jj,ikt,jptal) =  tra(ji,jj,ikt,jptal) + zcaloss * zrivalk * 2.0
            tra(ji,jj,ikt,jpdic) =  tra(ji,jj,ikt,jpdic) + zcaloss * zrivalk
            zsedcal(ji,jj) = (1.0 - zrivalk) * zcaloss * fse3t(ji,jj,ikt) 
            zsedsi (ji,jj) = (1.0 - zrivsil) * zsiloss * fse3t(ji,jj,ikt) 
#endif
         END DO
      END DO

      DO jj = 1, jpj
         DO ji = 1, jpi
            ikt  = mbkt(ji,jj)
            zdep = xstep / fse3t(ji,jj,ikt) 
            zws4 = zwsbio4(ji,jj) * zdep
            zws3 = zwsbio3(ji,jj) * zdep
            zrivno3 = 1. - zbureff(ji,jj)
# if ! defined key_kriest
            tra(ji,jj,ikt,jpgoc) = tra(ji,jj,ikt,jpgoc) - trb(ji,jj,ikt,jpgoc) * zws4 
            tra(ji,jj,ikt,jppoc) = tra(ji,jj,ikt,jppoc) - trb(ji,jj,ikt,jppoc) * zws3
            tra(ji,jj,ikt,jpbfe) = tra(ji,jj,ikt,jpbfe) - trb(ji,jj,ikt,jpbfe) * zws4
            tra(ji,jj,ikt,jpsfe) = tra(ji,jj,ikt,jpsfe) - trb(ji,jj,ikt,jpsfe) * zws3
            zwstpoc              = trb(ji,jj,ikt,jpgoc) * zws4 + trb(ji,jj,ikt,jppoc) * zws3
# else
            tra(ji,jj,ikt,jpnum) = tra(ji,jj,ikt,jpnum) - trb(ji,jj,ikt,jpnum) * zws4 
            tra(ji,jj,ikt,jppoc) = tra(ji,jj,ikt,jppoc) - trb(ji,jj,ikt,jppoc) * zws3
            tra(ji,jj,ikt,jpsfe) = tra(ji,jj,ikt,jpsfe) - trb(ji,jj,ikt,jpsfe) * zws3
            zwstpoc = trb(ji,jj,ikt,jppoc) * zws3 
# endif

#if ! defined key_sed
            ! The 0.5 factor in zpdenit is to avoid negative NO3 concentration after
            ! denitrification in the sediments. Not very clever, but simpliest option.
            zpdenit  = MIN( 0.5 * ( trb(ji,jj,ikt,jpno3) - rtrn ) / rdenit, &
                            zdenit2d(ji,jj) * zwstpoc * zrivno3 )
            z1pdenit = zwstpoc * zrivno3 - zpdenit
            zolimit = MIN( ( trb(ji,jj,ikt,jpoxy) - rtrn ) / o2ut, z1pdenit * ( 1.- nitrfac(ji,jj,ikt) ) )
            tra(ji,jj,ikt,jpdoc) = tra(ji,jj,ikt,jpdoc) + z1pdenit - zolimit
            tra(ji,jj,ikt,jppo4) = tra(ji,jj,ikt,jppo4) + zpdenit + zolimit
            tra(ji,jj,ikt,jpnh4) = tra(ji,jj,ikt,jpnh4) + zpdenit + zolimit
            tra(ji,jj,ikt,jpno3) = tra(ji,jj,ikt,jpno3) - rdenit * zpdenit
            tra(ji,jj,ikt,jpoxy) = tra(ji,jj,ikt,jpoxy) - zolimit * o2ut
            tra(ji,jj,ikt,jptal) = tra(ji,jj,ikt,jptal) + rno3 * (zolimit + (1.+rdenit) * zpdenit )
            tra(ji,jj,ikt,jpdic) = tra(ji,jj,ikt,jpdic) + zpdenit + zolimit
            sdenit(ji,jj) = rdenit * zpdenit * fse3t(ji,jj,ikt) 
            zsedc(ji,jj)   = (1. - zrivno3) * zwstpoc * fse3t(ji,jj,ikt) 
#endif
         END DO
      END DO
! EC-Earth C mass conservation correction 
! cumulate sedimentation
      zsedc_cum = zsedc_cum + glob_sum( (zsedc(:,:) + zsedcal(:,:) ) * 1.E3 * e1e2t(:,:) * tmask(:,:,ikt) ) ! mol C
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

      ! Nitrogen fixation process
      ! Small source iron from particulate inorganic iron
      !-----------------------------------
      DO jk = 1, jpkm1
         DO jj = 1, jpj
            DO ji = 1, jpi
               !                      ! Potential nitrogen fixation dependant on temperature and iron
               zlim = ( 1.- xnanono3(ji,jj,jk) - xnanonh4(ji,jj,jk) )
               IF( zlim <= 0.2 )   zlim = 0.01
#if defined key_degrad
               zfact = zlim * rfact2 * facvol(ji,jj,jk)
#else
               zfact = zlim * rfact2
#endif
               ztrfer = biron(ji,jj,jk)       / ( concfediaz + biron(ji,jj,jk)       )
               ztrpo4 = trb  (ji,jj,jk,jppo4) / ( concnnh4   + trb  (ji,jj,jk,jppo4) ) 
               zlight =  ( 1.- EXP( -etot_ndcy(ji,jj,jk) / diazolight ) ) 
               nitrpot(ji,jj,jk) =  MAX( 0.e0, ( 0.6 * tgfunc(ji,jj,jk) - 2.15 ) * r1_rday )   &
                 &         *  zfact * MIN( ztrfer, ztrpo4 ) * zlight
               zsoufer(ji,jj,jk) = zlight * 2E-11 / (2E-11 + biron(ji,jj,jk))
            END DO
         END DO
      END DO

      ! Nitrogen change due to nitrogen fixation
      ! ----------------------------------------
      DO jk = 1, jpkm1
         DO jj = 1, jpj
            DO ji = 1, jpi
               zfact = nitrpot(ji,jj,jk) * nitrfix
               tra(ji,jj,jk,jpnh4) = tra(ji,jj,jk,jpnh4) +             zfact
               tra(ji,jj,jk,jptal) = tra(ji,jj,jk,jptal) + rno3      * zfact
               tra(ji,jj,jk,jpoxy) = tra(ji,jj,jk,jpoxy) + o2nit     * zfact 
               tra(ji,jj,jk,jppo4) = tra(ji,jj,jk,jppo4) + concdnh4 / ( concdnh4 + trb(ji,jj,jk,jppo4) ) &
               &                     * 0.002 * trb(ji,jj,jk,jpdoc) * xstep
               tra(ji,jj,jk,jpfer) = tra(ji,jj,jk,jpfer) + 0.002 * 4E-10 * zsoufer(ji,jj,jk) * xstep
           END DO
         END DO 
      END DO

      IF( iom_use( "IronSupply" ) ) THEN 
         DO jk = 1, jpkm1
            zfesupply(:,:) = zfesupply(:,:) + 0.002 * 4E-10 * zsoufer(:,:,jk) * xstep * fse3t(:,:,jk)
         ENDDO 
      ENDIF


      IF( lk_iomput ) THEN
         IF( knt == nrdttrc ) THEN
            zfact = 1.e+3 * rfact2r  !  conversion from molC/l/kt  to molC/m3/s
            IF( iom_use("Nfix"   ) ) &
              &   CALL iom_put( "Nfix", nitrpot(:,:,:) * nitrfix * rno3 * zfact * tmask(:,:,:) )  ! nitrogen fixation  
            !
            IF( iom_use("INTNFIX") ) THEN   ! nitrogen fixation rate in ocean ( vertically integrated )
               zwork(:,:) = 0.
               DO jk = 1, jpkm1
                 zwork(:,:) = zwork(:,:) + nitrpot(:,:,jk) * nitrfix * rno3 * zfact * fse3t(:,:,jk) * tmask(:,:,jk)
               ENDDO
               CALL iom_put( "INTNFIX", zwork ) 
            ENDIF
            !
            IF( iom_use("NitrSupply") ) THEN   ! nitrogen fixation rate in ocean ( vertically integrated )
               DO jk = 1, jpkm1
                 znsupply(:,:) = znsupply(:,:) + nitrpot(:,:,jk) * nitrfix * rno3 * zfact * fse3t(:,:,jk) * tmask(:,:,jk)
               ENDDO
               CALL iom_put( "NitrSupply", znsupply(:,:) ) 
               CALL wrk_dealloc( jpi, jpj, znsupply )
            ENDIF
            IF( iom_use( "IronSupply" ) )  THEN
              CALL iom_put( "IronSupply", zfesupply(:,:) ) 
              CALL wrk_dealloc( jpi, jpj, zfesupply )
            ENDIF
            IF( iom_use( "SedCal"     ) )  CALL iom_put( "SedCal"    , zsedcal(:,:) * zfact )
            IF( iom_use( "SedSi"      ) )  CALL iom_put( "SedSi"     , zsedsi (:,:) * zfact )
            IF( iom_use( "SedC"       ) )  CALL iom_put( "SedC"      , zsedc  (:,:) * zfact )
            IF( iom_use( "Sdenit"     ) )  CALL iom_put( "Sdenit"    , sdenit (:,:) * rno3 * zfact )
         ENDIF
      ELSE
         IF( ln_diatrc ) THEN 
            zfact = 1.e+3 * rfact2r  !  conversion from molC/l/kt  to molC/m3/s
            trc2d(:,:,jp_pcs0_2d + 12) = nitrpot(:,:,1) * nitrfix * rno3 * zfact * fse3t(:,:,1) * tmask(:,:,1)
         ENDIF
      ENDIF
      !
      IF(ln_ctl) THEN  ! print mean trends (USEd for debugging)
         WRITE(charout, fmt="('sed ')")
         CALL prt_ctl_trc_info(charout)
         CALL prt_ctl_trc(tab4d=tra, mask=tmask, clinfo=ctrcnm)
      ENDIF
      !
      CALL wrk_dealloc( jpi, jpj, zdenit2d, zbureff, zwork )
      CALL wrk_dealloc( jpi, jpj, zsedcal , zsedsi , zsedc )
      CALL wrk_dealloc( jpi, jpj, zwsbio3 , zwsbio4, zwscal )
      CALL wrk_dealloc( jpi, jpj, jpk, zsoufer )
      !
      IF( nn_timing == 1 )  CALL timing_stop('p4z_sed')
      !
 9100  FORMAT(i8,3f10.5)
      !
   END SUBROUTINE p4z_sed


   INTEGER FUNCTION p4z_sed_alloc()
      !!----------------------------------------------------------------------
      !!                     ***  ROUTINE p4z_sed_alloc  ***
      !!----------------------------------------------------------------------
      ALLOCATE( nitrpot(jpi,jpj,jpk), sdenit(jpi,jpj), STAT=p4z_sed_alloc )
      !
      IF( p4z_sed_alloc /= 0 )   CALL ctl_warn('p4z_sed_alloc: failed to allocate arrays')
      !
   END FUNCTION p4z_sed_alloc


#else
   !!======================================================================
   !!  Dummy module :                                   No PISCES bio-model
   !!======================================================================
CONTAINS
   SUBROUTINE p4z_sed                         ! Empty routine
   END SUBROUTINE p4z_sed
#endif 

   !!======================================================================
END MODULE p4zsed