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FCHEM.for
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C=======================================================================
C FCHEM, Subroutine, U. Singh
C Determines floodwater chemistry
C-----------------------------------------------------------------------
C REVISION HISTORY
C US Written
C 03/13/2002 CHP added to modular model.
C changed IMMOB to IMMOBIL because name taken in NTRANS.
C 01/14/2005 CHP Added initialization for ALI, FTI, FPH
! 02/21/2006 CHP Limit flood N species to non-negative values.
! 03/02/2006 CHP ALGFON instead of DLTFON for N content of algae
C-----------------------------------------------------------------------
! Called by: Flood_chem
! Calls: OPFLOODN, EQUIL2
C=======================================================================
SUBROUTINE FCHEM (CONTROL, ISWITCH,
& BD1, SURCEC, DLAYR, EF, FLDH4, FLDN3, FLDU, !Input
& FLOOD, LFD10, NSWITCH, OC, OXMIN3, OXMIN4, !Input
& OXU, OXH4, OXN3, OXLT, PH, SNH4, SNO3, SRAD, !Input
& SW1, TMAX, TMIN, UREA, XHLAI, YRDOY, YRDRY, !Input
& AKILL, ALGFON, DailyCalc, DLTSNH4, DLTSNO3, !I/O
& DLTUREA, DLTFUREA, DLTFNO3, DLTFNH4, DLTOXU, !I/O
& DLTOXH4, DLTOXN3, IBP, IMMOBIL, !I/O
& ALGFIX, ALI, FNI, TOTAML) !Output
USE ModuleDefs
USE FloodModule
IMPLICIT NONE
SAVE
INTEGER NSWITCH, YRDRY, DYNAMIC
REAL BD1, FLDU, FLDH4,FLDH4C,FLDN3,FLDN3C
REAL FLDNI,FLDNC,FPI,FLDH3C
REAL ALGACT,FPH,AMLOSS,OXRNTRF
REAL FUHYDR, ALI, FNI, FTI, SURCEC
REAL OXLT,OXFAC,OXU,OXUC,OXN3,OXN3C,OXH4,OXH4C
REAL ALGFIX
REAL TOTAML
INTEGER IHDAY,LFD10, IBP
LOGICAL AKILL, DailyCalc, IMMOBIL
REAL EF,FLOOD
REAL OXMIN3, OXMIN4
INTEGER YRDOY, KILL,IST,IHR,I,K
REAL ALGALN,WALB,FRAD,AK,AMPEF,FTEMP,TK
REAL YALGA,TOTUH,HTMFAC,HEF,PHSHIFT,TEMPFU,UALGCT,FUHYDRC
REAL FUHYDRM,PHFUHYD,FPH1,FLDH3,WIND,ALOGHK,HK,FNH3M,FNH3P
REAL AMLOS1,GLOS1,TFACTOR,WF2,PHFACT,RNTRFI,HOXRNT,XMIN
REAL ELAG, SW1
REAL OC(NL)
REAL XHLAI, PH(NL), SNH4(NL), DLAYR(NL)
REAL SNO3(NL), SRAD, UREA(NL), TMIN, TMAX
REAL DLTFUREA, DLTFNO3, DLTFNH4
REAL DLTOXU, DLTOXH4, DLTOXN3
REAL TMPFUREA, TMPFNO3, TMPFNH4
REAL TMPOXU, TMPOXH4, TMPOXN3
REAL DLTUREA(NL), DLTSNO3(NL), DLTSNH4(NL)
REAL TMPUREA, TMPNO3, TMPNH4
REAL FAC1
REAL ALGFON
TYPE (ControlType) CONTROL
TYPE (SwitchType) ISWITCH
DYNAMIC = CONTROL % DYNAMIC
!***********************************************************************
!***********************************************************************
! Seasonal initialization - run once per season
!***********************************************************************
IF (DYNAMIC .EQ. SEASINIT) THEN
!-----------------------------------------------------------------------
! Need initialization section here
TOTAML = 0.0
FNI = 0.1
FPI = 0.5
IMMOBIL = .FALSE.
YALGA = 0.1
ALGFIX = 0.0
ALGACT = 0.1
ALI = 1.0
FTI = 1.0
FPH = 7.0
CALL OPFLOODN (CONTROL, ISWITCH,
& ALGACT, ALI, AMLOSS, BD1, EF, FLDH3C, FLDH4,
& FLDH4C, FLDN3C, FLDU, FLOOD, FNI, FPH, FTI,
& FUHYDR, OXRNTRF, YRDOY)
!***********************************************************************
!***********************************************************************
! Daily rate calculations
!***********************************************************************
ELSEIF (DYNAMIC .EQ. RATE) THEN
!-----------------------------------------------------------------------
! Copy flood N variables into temporary variables to compute
! changes for today.
TMPFUREA = FLDU + DLTFUREA
TMPFNO3 = FLDN3 + DLTFNO3
TMPFNH4 = FLDH4 + DLTFNH4
TMPUREA = UREA(1) + DLTUREA(1)
TMPNO3 = SNO3(1) + DLTSNO3(1)
TMPNH4 = SNH4(1) + DLTSNH4(1)
TMPOXU = OXU + DLTOXU
TMPOXN3 = OXN3 + DLTOXN3
TMPOXH4 = OXH4 + DLTOXH4
! Compute concentrations of N in floodwater.
FLDH4C = TMPFNH4 * 100.0 / FLOOD
FLDN3C = TMPFNO3 * 100.0 / FLOOD
FAC1 = 1.0 / (BD1 * 1.E-01 * DLAYR(1))
OXFAC = 1.00/(BD1*OXLT*1.0E-01)
ALGALN = 0.0
WALB = 0.1
FRAD = SRAD*(1.0-WALB)*EXP(-0.65*XHLAI) ! .85->.65
ALI = 1.0 - EXP(-FRAD/5.0)
!
! Potential Hydrolysis
!
AK = 0.008 + 0.005*OC(1)
AK = AMIN1 (AK,1.0)
!
! Floodwater Evaporation (EF) initialization at begin of day
!
! AMPEF(hr) is 0.2*EF(daily) Inc to .38
!
AMPEF = 0.38*EF
AMLOSS = 0.0
OXRNTRF = 0.0
FTEMP = (TMAX + TMIN)*0.5
IF (FTEMP .LT. 30.0) THEN
FTI = (FTEMP-15.0)*0.1
ELSEIF (FTEMP .GE. 30.0) THEN
FTI = 1.0-(FTEMP-30.0)*0.05
ENDIF
FTI = AMIN1 (FTI,1.0)
!
! Biological activity of floodwater
!
ELAG = AMIN1 (FNI,FPI,ALI,FTI)
ALGACT = ELAG*(3.0-ALGACT)*ALGACT ! 3->3.5
IF (XHLAI .GT. 1.0) THEN
ALGACT = AMIN1 (ALGACT,ALI)
ENDIF
ALGACT = AMIN1 (ALGACT,1.00)
ALGACT = AMAX1 (ALGACT,0.10)
FLDNI = TMPFNH4 + TMPFNO3
IF (.NOT. AKILL) THEN
IF (.NOT. IMMOBIL) THEN
IF (ALGALN .GT. FLDNI) THEN
ALGFIX = ALGALN
ENDIF
ALGALN = FLDNI
ALGALN = AMAX1 (ALGALN,ALGFIX)
!
! Trying to determine amount of N in algae at peak algal growth
! Maximum N fixed by algae = 5 kg N/ha
!
IF (ALGALN .GE. ALGFIX .AND. ALGALN .GT. 0.8) THEN
ALGALN = AMIN1 (ALGALN,8.0)
TMPFNO3 = TMPFNO3 - ALGALN * TMPFNO3 / FLDNI
TMPFNH4 = TMPFNH4 - ALGALN * TMPFNH4 / FLDNI
IMMOBIL = .TRUE.
ALGFIX = ALGALN
ELSE
IF (KILL .EQ. 1 .AND. FLDNI .GT. 0.0) THEN
TMPFNO3 = TMPFNO3 - ALGALN * TMPFNO3 / FLDNI
TMPFNH4 = TMPFNH4 - ALGALN * TMPFNH4 / FLDNI
IMMOBIL = .TRUE.
ALGFIX = ALGALN
ENDIF
ENDIF
ENDIF
IF (YALGA .LE. ALGACT) THEN
KILL = 0
ELSE
KILL = KILL + 1
IF (KILL .EQ. 2) THEN
AKILL = .TRUE.
ALGFON = ALGFON + ALGFIX
ALGFIX = 0.0
ENDIF
ENDIF
ENDIF
YALGA = ALGACT
IF (ALGACT .GE. 0.2 .OR. YRDOY .LT. LFD10) THEN
DailyCalc = .FALSE.
IHDAY = 12
IST = 1
IHR = 12
ELSE
DailyCalc = .TRUE.
IHDAY = 1
IST = 6
IHR = 6
ENDIF
TOTUH = 0.0
DO I = IST, IHR
K = 7 - I
IF (I .GT. 6) THEN
K = I - 6
ENDIF
HTMFAC = 0.931 + 0.114*K-0.0703*K**2+0.0053*K**3
!
! First approximation of floodwater temperature
!
FTEMP = TMIN + HTMFAC*(TMAX + 2.0 - TMIN)
IF (I .EQ. 13) THEN
FTEMP = TMIN
ENDIF
!
! Calculate Hourly Floodwater Evaporation (HEF)
!
IF (I .LE. 6 .OR. I .GT. 9) THEN
HEF = AMPEF*SIN(3.141593*FLOAT(I)/12.0) + 0.08 ! 10->9
ENDIF
HEF = ABS (HEF)
!
! Calculate indices for biological activity
!
IF (I .EQ. 6) THEN
FNI = (FLDH4C+FLDN3C)/15.0+0.10 ! 15->10
ENDIF
FNI = AMIN1 (FNI,1.0)
PHSHIFT = 0.5 + 2.0*ALGACT ! 2->2.5
!
! Urea hydrolysis function of surface layer OC or
! biological activity, whichever is greater.
!
TEMPFU = 0.04 * FTEMP - 0.2
TEMPFU = AMIN1 (TEMPFU, 0.9)
UALGCT = 0.1*ALGACT
FUHYDR = AMAX1 (AK, UALGCT) * TEMPFU * TMPFUREA
TMPFUREA = TMPFUREA - FUHYDR
TMPFNH4 = TMPFNH4 + FUHYDR
TOTUH = TOTUH + FUHYDR
IF (I .LE. 6 .OR. I .GT. 8) THEN
FPH = 7.0 + PHSHIFT*SIN(3.1412*FLOAT(I)/12.0)
!
! Add effects of UREA hydrolysis on floodwater pH here
!
IF (FUHYDR .GT. 0.05) THEN
FUHYDRC = FUHYDR*100.0/FLOOD
FUHYDRM = FUHYDRC*0.001/14.0
PHFUHYD = AMIN1(10.0,-LOG10(FUHYDRM))
FPH1 = FPH
FPH = FPH + ALI*(10.0-PHFUHYD)/10.0
ENDIF
ENDIF
FPH = AMAX1 (FPH,7.0)
!
! Ammonia loss routine ... calculate floodwater NH3
!
TK = FTEMP + 273.
FLDH4C = TMPFNH4 * 100.0 / FLOOD
FLDN3C = TMPFNO3 * 100.0 / FLOOD
IF (I .LE. 6 .OR. I .GT. 9 .OR. FLDH3C .GE. FLDH4C) THEN
FLDH3C = FLDH4C/(1.0+10.0**(0.09018+2729.92/TK-FPH))
FLDH3C = MAX(0.0, FLDH3C)
ENDIF
FLDH3 = FLDH3C*FLOOD*0.01
WIND = 7.15*HEF ! 7.15->5.75
IF (XHLAI .GT. 1.0) THEN
WIND = 5.75*HEF/(XHLAI*1.5)
ENDIF
ALOGHK = 155.559-8621.06/TK-25.6767*ALOG(TK)+0.035388*TK
HK = EXP (ALOGHK)
FNH3M = FLDH3C*0.001/14.0
FNH3P = AMAX1 (0.0,10.*FNH3M/HK) ! 1.552
IF (FNH3P .GT. 0.0) THEN
AMLOS1 = 0.036 * FNH3P + 0.0082 * WIND +
& 0.000036 * FNH3P**2 * WIND * FLOOD
ENDIF
IF (NSWITCH .EQ. 7) THEN
AMLOS1 = 0.0
ENDIF
IF (FNH3P .LE. 0.0) THEN
AMLOS1 = 0.0
ENDIF
GLOS1 = AMLOS1
IF (FLDH3C .LE. 0.0 .OR. AMLOS1 .LE. 0.0) THEN
AMLOS1 = 0.0
ENDIF
FLDH3 = AMIN1 (FLDH3,TMPFNH4)
AMLOS1 = AMIN1 (AMLOS1,FLDH3)
TMPFNH4 = TMPFNH4 - AMLOS1
AMLOSS = AMLOSS + AMLOS1
TOTAML = TOTAML + AMLOS1
FLDH4C = TMPFNH4*100.0/FLOOD
!
! Now do some nitrification in the oxidised layer - thickness from
! flooding. Denitrification in NTRANS routine should take care of
! any nitrate accumulation
! TFACTOR = EXP(-6602/TK+24.1)
TFACTOR = EXP(-6572/TK+21.4) !UPS UH 03/21/03
FLDNI = TMPFNH4 + TMPFUREA + TMPFNO3
FLDNC = FLDNI*100.0/FLOOD
WF2 = 0.15 ! .85 --> .15
PHFACT = 0.3*PH(1)-1.65
PHFACT = AMIN1 (PHFACT,1.0)
PHFACT = AMAX1 (PHFACT,0.0)
RNTRFI = TFACTOR*WF2*PHFACT/13.0
RNTRFI = AMIN1 (RNTRFI,0.90)
HOXRNT = RNTRFI*TMPNH4*OXLT/DLAYR(1)
! XMIN = SMIN4(1)
XMIN = 0.001
HOXRNT = AMAX1(0.0, AMIN1 (HOXRNT,TMPNH4-XMIN))
TMPNH4 = TMPNH4 - HOXRNT
TMPNO3 = TMPNO3 + HOXRNT
OXRNTRF = OXRNTRF + HOXRNT
OXH4C = TMPNH4
OXN3C = TMPNO3
OXUC = TMPUREA
TMPOXN3 = OXN3C/OXFAC
TMPOXU = OXUC /OXFAC
TMPOXH4 = OXH4C/OXFAC
!
! Recompute equilibria after nitrification/denitrification
!
CALL EQUIL2 (
& BD1, SURCEC, DLAYR, FLOOD, IHDAY, 1, !Input
& OXLT, OXMIN3, OXMIN4, SW1, YRDOY, YRDRY, !Input
& IBP, TMPFUREA, TMPOXU, TMPUREA) !I/O
CALL EQUIL2 (
& BD1, SURCEC, DLAYR, FLOOD, IHDAY, 2, !Input
& OXLT, OXMIN3, OXMIN4, SW1, YRDOY, YRDRY, !Input
& IBP, TMPFNO3, TMPOXN3, TMPNO3) !I/O
CALL EQUIL2 (
& BD1, SURCEC, DLAYR, FLOOD, IHDAY, 3, !Input
& OXLT, OXMIN3, OXMIN4, SW1, YRDOY, YRDRY, !Input
& IBP, TMPFNH4, TMPOXH4, TMPNH4) !I/O
END DO
! Changes to urea, NO3 and NH4 due to flood initialization processes
!Flood variables
DLTFUREA = MAX(0.0, TMPFUREA) - FLDU
IF (DLTFUREA + FLDU < 1.E-9 .AND. FLDU > 1.E-5) THEN
DLTFUREA = -FLDU
ENDIF
DLTFNO3 = MAX(0.0, TMPFNO3) - FLDN3
IF (DLTFNO3 + FLDN3 < 1.E-9 .AND. FLDN3 > 1.E-5) THEN
DLTFNO3 = -FLDN3
ENDIF
DLTFNH4 = MAX(0.0, TMPFNH4) - FLDH4
IF (DLTFNH4 + FLDH4 < 1.E-9 .AND. FLDH4 > 1.E-5) THEN
DLTFNH4 = -FLDH4
ENDIF
!Oxidation layers
DLTOXU = MAX(0.0, TMPOXU) - OXU
DLTOXH4 = MAX(0.0, TMPOXH4) - OXH4
DLTOXN3 = MAX(0.0, TMPOXN3) - OXN3
!Surface variables
DLTUREA(1) = MAX(0.0, TMPUREA) - UREA(1)
DLTSNO3(1) = MAX(0.0, TMPNO3) - SNO3(1)
DLTSNH4(1) = MAX(0.0, TMPNH4) - SNH4(1)
!***********************************************************************
!***********************************************************************
! Daily OUTPUT
!***********************************************************************
ELSEIF (DYNAMIC .EQ. OUTPUT .OR. DYNAMIC .EQ. SEASEND) THEN
!-----------------------------------------------------------------------
CALL OPFLOODN (CONTROL, ISWITCH,
& ALGACT, ALI, AMLOSS, BD1, EF, FLDH3C, FLDH4,
& FLDH4C, FLDN3C, FLDU, FLOOD, FNI, FPH, FTI,
& FUHYDR, OXRNTRF, YRDOY)
!***********************************************************************
!***********************************************************************
! END OF DYNAMIC IF CONSTRUCT
!***********************************************************************
ENDIF
!***********************************************************************
RETURN
END SUBROUTINE FCHEM