Institute of Food and Agricultural Sciences (IFAS)
Biogeochemistry of Wetlands
S i
Science
and
dA
Applications
li ti
Phosphorus Cycling Processes
Wetland Biogeochemistry Laboratory
Soil and Water Science Department
University of Florida
Instructor
K. Ramesh Reddy
[email protected]
6/22/2008
6/22/2008
WBL
1 1
Institute of Food and Agricultural Sciences (IFAS)
Phosphorus Cycling Processes
DRP
PP
Water column
DRP
PP
Soil
6/22/2008
WBL
2
1
Phosphorus Cycling Processes
Topic Outline
Water Column
¾ Introduction
¾ Forms of phosphorus
¾ Inorganic Phosphorus retention
mechanisms
¾ Organic phosphorus dynamics
¾ Phosphorus exchange between soil and
overlying water column
¾ Regulators of phosphorus reactivity and
Soil
mobility
¾ Phosphorus memory in wetlands
6/22/2008
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3
Phosphorus Cycling Processes
Learning Objectives
‰
‰
‰
‰
‰
‰
‰
Id tif sources, and
Identify
d iinorganic
i and
d organic
i fforms off
phosphorus
Inorganic phosphorus retention mechanisms in soil
Descibe the influence of soil type on inorganic
phosphorus retention
Role of enzymes and microorganisms in organic
phosphorus mineralization
Biotic regulation phosphorus retention
Ph
Phosphorus
h
exchange
h
between
b t
soilil and
d overlying
l i water
t
column
Draw the phosphorus cycle and indentify, storages,
abiotic and biotic processes, and fluxes in soil and water
column
6/22/2008
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4
2
Terminology
¾ Total Phosphorus (TP)
¾ Dissolved total P (DTP)
¾ Total P in solutions filtered through 0.45 um membrane filter
¾ Dissolved reactive P (DRP) or Soluble Reactive P (SRP)
¾ Water samples filtered through 0.45 um membrane filter and
analyzed for ortho-P.
¾ Dissolved Organic P (DOP)
¾ DTP – DRP = DOP
¾ Particulate inorganic P (PIP)
¾ Particulate matter or soil extracted with acid
¾ Particulate organic P (POP)
¾ TP-PIP = POP
6/22/2008
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5
Phosphorus Cycle
Plant biomass P
Runoff,
Atmospheric
Deposition
Outflow
Litterfall
POP
DIP
PIP
DIP
Periphyton P
Peat
accretion
DIP
DOP
6/22/2008
DOP
POP
DOP
AEROBIC
[Fe, Al or
Ca-bound P]
DIP
Adsorbed
IP
PIP
ANAEROBIC
WBL
6
3
Fertilizers, Animal wastes
Biosolids, Wastewaters
Phosphorus Transfer
Uplands
[sink/source]
Wetlands &
Streams
[sink/source]
Lake
Lake [sink]
Okeechobee
6/22/2008
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7
Phosphorus Imports from
Various Sources: Florida
Animal
Manures
Atmospheric
Deposition
10%
Composts (?)
Natural weathering of minerals (?)
0%
8%
8%
69%
Wastewater
Fertilizers
5%
Biosolids
Total = 61,300 mt P per year
6/22/2008
WBL
1996
8
4
Fertilizer Phosphorus Inputs
[[8%]]
[5%]
[20%]
Florida
42,660
metric ton year-1
North America
1.85 x 106
metric tons year-1
[17%]
[Mullins et al., 2005]
[50%]
World
14 x 106
metric tons year-1
[Mullins et al., 2005]
6/22/2008
WBL
1996 Florida
2003 North America
2003 World 9
Phosphorus Loads from Uplands
‰
‰
‰
‰
Uplands have been a steady source of P to
wetlands and aquatic systems, where
substantial
b t ti l amounts
t off P has
h accumulated
l t d iin
soils and sediments
Best management practices and other remedial
measures can significantly reduce P loads from
uplands to wetlands and aquatic systems
How will wetlands and aquatic systems respond
to P load reduction?
How long P memory lasts in wetlands and
aquatic systems before they reach stable
condition?
6/22/2008
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10
5
Phosphorus Memory
in a Watershed
‰
Capacity for storing phosphorus in
various ecosystem components
(uplands, wetlands, and aquatic
systems)
‰
‰
‰
‰
Water Column
P
Transient pools
Stable pools
Detritus
Capacity for showing effects as the
result of past practices
Length of time over which
phosphorus release extends before
returning to a stable condition
6/22/2008
P
Soil
WBL
11
Phosphorus Transfer
[4157]
[Lake Okeechobee Basin]
Phosphorus Budget
[tons/year]
Uplands (82%)
[754]
[415] (10%)
Wetlands
& Streams
(8%)
6/22/2008
Lake
Okeechobee
WBL
12
6
Phosphorus Gradient in
Wetlands
Phosphorus
Loading
Phosphorus
Outflow
Gradient in nutrient enrichment in
soil and water column
[ Distance from inflow]
6/22/2008
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13
Water column TP - WCA-2A transect
Total P (µg/L)
150
100
50
0
0
2
4
6
8
10
12
14
16
Distance from Inflow (km)
6/22/2008
WBL
14
7
Phosphorus accretion rates in
Everglades WCA-2A
P A
ACCUMULATION (g m-2 y-1)
1.2
1.0
0.8
0.6
0.4
0.2
0
0
2
4
6
8
10
12
14
16
DISTANCE FROM INFLOW (km)
6/22/2008
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15
Total P concentration in WCA-2A soil (0-10 cm)
1990
6/22/2008
1998
WBL
16
8
Everglades – Soil phosphorus
6/22/2008
WBL
17
Soil Phosphorus
Depth (cm)
D
Blue Cypress Marsh-1992
0-4
0-4
4-8
4
8
8-12
8-12
16-20
12-16
16-20
20-24
24-28
32-36
40-44
24-28
32 36
32-36
Unimpacted
36-40
0
6/22/2008
1,000 2,000
Impacted
p
0
1,000 2,000
Total
WBL P (mg /kg)
18
9
Waterr Column Phosph
horus
Phosphorus Memory
External Load
Reduction
Background
Level
Internal
Memory
Lag time for Recovery
Time - Years
6/22/2008
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19
Ecological Significance –
Phosphorus Loading
PLANTS
WATER
N C
P
Microbial
Biomass
P
SOIL
6/22/2008
NC P
Labile
DETRITUS
DETRITUS
Microbial
Biomass
N
P N
WBL
20
10
Phosphorus Cycle
Plant biomass P
Runoff,
Atmospheric
Deposition
Outflow
Litterfall
POP
DIP
DOP
PIP
DIP
Periphyton P
Peat
accretion
DIP
DOP
6/22/2008
POP
DOP
AEROBIC
[Fe, Al or
Ca-bound P]
DIP
Adsorbed
IP
PIP
ANAEROBIC
WBL
21
Phosphorus in Wetlands
Phosphorus
loading
Organic
phosphorus
p
p
Uptake by
algae and
plants
Soil porewater
phosphorus
[dissolved]
Metal o
oxides
ides
and clay mineral
surfaces
Discrete
phosphate
minerals
6/22/2008
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22
11
Soil Phosphorus Forms
¾ Inorganic P
¾
—
KCl Pi - Bioavailable P
KCl-Pi
—
NaOH-Pi - Fe-/Al- P [slowly available]
—
HCl-Pi - Ca-/Mg- P [slowly available]
Organic P
Microbial Biomass P - Bioavailable P
— NaOH-Po - Fulvic Acid -P [slowly available]
— NaOH-Po - Humic Acid -P [very slowly available]
—
Residual P -Highly resistant [unavailable]
—
6/22/2008
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23
Phosphate ions and pH
¾ H3PO4 = H+ + H2PO4- pK = 2.15
¾ H2PO4- = H+ + HPO42- pK = 7.20
¾ HPO42- = H+ + PO43- pK = 12.35
Oxidation number for P
PO43- [[+5]]
PH3 [-3]
H3PO4 [[+5]
5]
H2PO4 [+5]
HPO42- [+5]
6/22/2008
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24
12
Total In
norganic P (mg k
kg-1)
Inorganic PhosphorusOrganic Soils - WCA-2A
3,000
1 000
1,000
Y = 0.01X1.54
R2 =0
0.897;
897; n=390
n 390
300
100
30
WCA1
WCA2
10
WCA3
3
HWMA
EAA
1 50
100
200
500
1,000 2,000
5,000
Total Phosphorus (mg kg-1 )
6/22/2008
WBL
25
Stream Sediments –
Okeechobee Drainage Basin
KCl-Pi (available)
13%
2%
Fe- and Al-bound P
29%
Alkali extractable organic P
50%
Ca- and Mg-bound P
Residual P
6%
DL-Stream
T l P = 877
Total
8 mg P/kg
P/k
7%
11%
6/22/2008
WBL
10%
1%
71%
Rucks-Stream
Total P + 93 mg P/kg
26
13
Organic Wetland Soils –
Drainage Effects
<0 1%
<0.1%
23%
KCl-Pi (available)
1%
Fe- and Al-bound P
4%
Alkali extractable organic P
72%
Ca- and Mg-bound P
Residual P
Peat Depth < 10 cm
Total
T
t l P = 836 mg P/kg
P/k
1% 7%
24%
47%
Peat Depth > 30 cm
Total P = 411 mg P/kg
6/22/2008
21%
WBL
27
¾
¾
¾
¾
¾
Pore water
ater P
Exchangeable
Fe-/Al- bound P
Ca-/Mg-bound P
R id l P
Residual
6/22/2008
WBL
Bioavailability
y
Inorganic Phosphorus
High
Low
28
14
Inorganic Phosphorus
™Acid soils
™AlPO4 . 2H2O [Variscite]
™FePO4 . 2H2O [Strengite]
™Alkaline soils
™Ca (H2PO4)2 [Monocalcium phosphate]
™Ca HPO4. 2H2O [Dicalcium phosphate]
™Ca8 ((H2 PO4)6 . H2O [[Octacalcium phosphate]
p
p
]
™Ca3 (PO4)2 [Tricalcium phosphate]
™Ca5 (PO4)3 OH [Hydroxyapatite]
™Ca5 (PO4)3 F [Fluorapatite]
6/22/2008
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29
1 mm
5 mm
Phosphate Minerals
Apatite
Vivianite
W. G. Harris, 2002
6/22/2008
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30
15
Phosphate Availability
¾ Readily available phosphates
¾ Soil porewater.
porewater
¾ Slowly available phosphates
¾ Fe, Al, and Mn phosphates (acid soils) and Ca and Mg
phosphates (alkaline soils) that have been freshly
precipitated or are held mostly on the surface of fine
particles in the soil. Labile organic compounds.
¾ Very
V
slowly
l l available
il bl phosphates
h
h t
¾ Precipitates of Fe, Al, Mn, Ca, and Mg phosphates that
have aged and are well crystallized. Phosphates that were
held on particle surfaces have penetrated the particles, little
remaining on the surface. Stable organic compounds
6/22/2008
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31
Phosphorus
¾ Is P one of the redox elements ?
¾ HPO42- + 10H+ + 8e- = PH3 + 4H2O
¾ Is P solubility affected by changes in
redox potential?
¾ FePO4 + H+ + e- = Fe2+ + HPO42-
6/22/2008
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32
16
Phosphorus Retention
by Soils
¾ Adsorption –Desorption
Desorption
¾ Precipitation – Dissolution
¾ Immobilization - mineralization
Retention = Adsorption + Precipitation
+ Immobilization
6/22/2008
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33
Sorption of Phosphate
¾ Intensity factor : Concentration of
phosphate
h
h t iin soilil porewater.
t
¾ Capacity factor : Ability of solid
phases to replenish phosphate as it
is depleted from solution.
Solid
phas
e
6/22/2008
Padsorbed
Psolution
WBL
34
17
Inorganic Phosphate
Reactions
¾ Precipitation by Al, Fe, Mn, Ca, and Mg ions
¾ Al3+ + H2PO4- + 2H2O = 2H+ + Al (OH)2 H2PO4 (insoluble) (Variscite)
¾ Anion exchange
¾
Al OH2+
Al OH2+ H2PO4 + OH-
OH + H2PO4- =
¾ Reaction with hydrous oxides
OH
OH + H2PO4- = Al
OH
Al
OH
OH + OHH2PO4
¾ Fixation by silicate clays
¾ Al2 SiO5 (OH)4 + 2H2PO4- = 2Al (OH)2 H2PO4 + Si2O52-
6/22/2008
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35
Charge
pH- Dependent Charge
on Solid Phase
Negative charge
[loss of H+]
[-]
0
[[+]]
Positive charge
[gains H+]
3
4
5
6
ZPC
[
[zero
point
i t charge]
h
]
7
8
9
10
pH
6/22/2008
WBL
36
18
Variable Charge on Solid Phase
No charge
Solid phase
Soil
Solution
Negative charge
Solid phase
Al – OH + OH- =
COOH
+ OH- =
AlOH + H+
AlO- + H+
Negative charge
[high pH]
6/22/2008
=
Al–O- + H2O
COO- + H2O
AlOH2+
AlOH + H+
AlOH2+
No charge
[Intermediate pH]
Positive charge
[low pH]
WBL
37
Inorganic Phosphate Reactions
Alkaline pH conditions:
¾ Ca2+ + 2H2PO4- = Ca (H2PO4)2
¾ Ca (H2PO4)2 + Ca2+ + 2OH- = 2CaHPO4 + 2H2O
¾ 2CaHPO4 + Ca2+ + 2OH- = 2Ca3 (PO4)2 + 2H2O
6/22/2008
WBL
38
19
Sorption of Phosphate
Solid phase
Solution phase
I
I:
Initial equilibrium
condition
= Phosphate ions
II
II: Increase in solution
P concentration --Rapid adsorption to
solid surface
[Time = seconds to minutes]
III
III: Diffusion into
solid phase
[Time = hours to days]
6/22/2008
WBL
39
Water
Pw
Pad
Ps
Soil
Pret
ption
Deso
orption Adsorp
Phosphorus Sorption Isotherm
Smax
EPCo
slope = KD
P desorption under
So ambient conditions
Phosphorus in Soil Porewater
6/22/2008
WBL
40
20
Deso
orption Adsorpttion
Phosphorus Sorption Isotherm
Low P Load
EPCo
High P Load
EPCo
P Retention
P Release
Phosphorus in Soil Porewater
6/22/2008
WBL
41
Influence of Phosphorus
Loading on EPC0
[Nair et al. 1997]
Land use Total P (mg/kg) EPCo (mg/L)
6/22/2008
Intensive
2,330
5.0
Holding
Pasture
181
1.4
31
0.1
Beef
31
0.1
Forage
Native
23
18
0.2
0.1
WBL
42
21
Influence of Phosphorus
Loading on EPC0
[Everglades – WCA-2a]
2
EPCo (mg P/L)
Anaerobic 0-10 cm
1.5
Aerobic 0-10 cm
1
0.5
0
0
2
4
6
8
10
12
Distance from inflow (km)
6/22/2008
WBL
43
Phosphorus Sorption
[Richardson, 1985]
3000
P sorbed, mg/kg
g
Swamp forest
Mineral/peat soil
2400
Houghton fen
Peat soil
1800
Pocosin bog
Mineral/peat soil
1200
600
Pocosin bog
Peat soil
0
0
30
90
150
210
P in solution, mg/L
6/22/2008
WBL
44
22
P Sorption by WCA-2A soils
2,000
Sorrbed P (mg P/kg)
Ambient PW-P
1,500
Site 1
1,000
500
Sorption
0
0.01
0.1
1
10
100
Site 8
Ambient PW-P
1,500
[Anaerobic]
1 000
1,000
Desorption
500
0
0.001
6/22/2008
Desorption
[Anaerobic]
0.01
0.1
1
10
Sorption
100
Solution P concentration
(mg P/L)
WBL
45
Phosphorus Sorption Isotherm
™ Linear Equation
™ S = KL C
™ where: S = mass of P sorbed per mass of solid phase;
C = P concentration in solution; KL = adsorption
coefficient related to binding strength
™Freundlich Equation
™ S = KF CN [log S = N log C + log KF]
™ where: S = mass of P sorbed per mass of solid phase;
C = P concentration in solution; KF = adsorption
coefficient related to binding strength; N = empirical
constant
6/22/2008
WBL
46
23
Phosphorus Sorption Isotherm
™ Langmuir Equation
™ S = [k C Smax]/1 + k C
™ C/S = [1/Smax] C + 1/k Smax
™ where: S = mass of P sorbed per mass
(C/S)
Slope = 1/Smax
1/kSmax
of solid phase; C = P concentration in
solution; k = constant related to
binding strength; Smax = maximum
amount of P sorbed per mass of solid
phase
6/22/2008
C
WBL
47
Desorption Adsorption
Phosphorus Sorption Isotherm
Adsorption
Smax
Precipitation
EPCo
slope = KD
P desorption under
So ambient conditions
Phosphorus in Soil Porewater
6/22/2008
WBL
48
24
Saturation Index (SI)
Ca Ab = aC + bA
[C]a [A]b
K=
[Ca Ab]
[C]a [A]b
Saturation
Sat ration Index
Inde (SI) = IAP/K
Ion Activity Product (IAP) =
SI < 1 = Solution is “undersaturated”
SI > 1 = Solution is “supersaturated”
SI = 1 = Solution saturated (near equilibrium)
6/22/2008
WBL
49
Inte
ensity Factorr
Precipitation of
Phosphate
P in solution; t = 0
1
Supersaturation with
respect to B
2
A
3
B
Supersaturation with
respect to C
C
Capacity Factor
6/22/2008
WBL
50
25
Co-precipitation of
Phosphorus
Coating of hydrated ferric oxide
(Fe2O3 nH2O) co-precipitated
with ferric phosphate,
aluminum phosphate, and
calcium phosphate
Silt or Clay Particle
6/22/2008
WBL
51
Retention
Release
Overlying Water
Sediment/Soil
P rele
ease P retentio
on
Phosphorus Retention Isotherm
Pmax
EPCw
slope = A
P release under
ambient conditions
Phosphorus in Water Column
6/22/2008
WBL
52
26
Phosphorus Retention Isotherm
0
P added to water column – range of concentrations
High
EPCw
6/22/2008
WBL
53
Phosphorus Retention by
Wetlands Soils and Stream
Sediments
[Okeechobee Basin
Basin, Florida]
¾ Wetlands
¾ Pr = 118 [SRP] - 54.2
¾ EPCw = 0.47 mg P/L
r2 = 0.71 n = 11
¾ Stream sediments
¾ Pr = 128 [SRP] - 12.4
¾EPCw = 0.1 mg P/L
6/22/2008
WBL
r2 = 0.95 n = 175
54
27
40
EPCw=33 ug/L
20
0
-20 0
-40
20
60
40
P release
by
y sediments
DRP
P retention/rele
ease
2
(mg/ m Year)
Phosphorus Retention by
Mud Sediments – Lake Okeechobee
-60
-80
-100
80
100 120 140
P retention
by sediments
-120
Water Column DRP ug/L
6/22/2008
WBL
55
Phosphorus Adsorption Coefficient
[Organic Soils]
1,200
r2 = 0.89
n = 36
K [L/kg]
1,000
800
600
400
200
0
0
20
40
60
80
Ash content (%)
6/22/2008
WBL
56
28
Phosphorus Retention Capacity
Mineral Wetland Soils - Okeechobee
Sma
ax (mmoles P/k
kg)
Basin
50
40
30
Smax = 1.74 + 0.172 [Fe + Al]
r2 = 0.78 n = 285
20
10
0
0.1
0.3
1
3
10
30
100 300
Oxalate Extractable [Fe + Al] (mmol/kg)
Phosphorus Retention –
Peat/Mineral Wetland Soils
P sorbed [mg/kg]/
lo
og of P in solution
200
160
120
80
40
00
6/22/2008
Y = 1.21+0.015(x)
1 21+0 015(x)
R2 = 0.87
Richardson, 1985
2
4
6
8
10
Oxalate extractable Al, g/kg
WBL
58
29
Phosphorus solubility as a
function of pH and Eh
6/22/2008
WBL
59
Iron solubility as a
function of pH and Eh
6/22/2008
WBL
60
30
Dissolved P (uM P)
Dissolved P in Sediments
6/22/2008
WBL
61
Phosphorus Solubility under
Anaerobic Soil Conditions
FeS
SO42-
Fe2+ + PO43-
H2S + FePO4
[Strengite]
FePO4
[Strengite]
Fe(OH)2-PO4
Fe3(PO4)2
[Vivianite]
6/22/2008
WBL
62
31
Lake Okeechobee
32P
activity (cpm/mll)
a
7000
6000
Reduced
5000
4000
3000
2000
1000
0
6/22/2008
Oxidized
Littoral
Peat
Mud
Mud
Mud
Mud
WBL
63
Mechanisms of Phosphorus
Release in Wetlands
™ Reduction of insoluble ferric p
phosphate
p
to more
soluble ferrous phosphate
™ Release occluded phosphate by reduction of
hydrated ferric oxide coating
™ Higher solubility of ferric and aluminum phosphates
due to increased soil pH
™ Displacement of phosphate from ferric and aluminum
phosphate
p
p
by
y organic
g
anions
™ Increased phosphate availability during sulfate
reduction
™ Increased solubility of calcium phosphate in alkaline
soils as result of pH decrease under flooded
conditions
6/22/2008
WBL
64
32
Regulators of Inorganic
Phosphorus Retention
™
™
™
™
™
™
™
™
pH and Eh
Phosphate concentration
Clay content
Iron and aluminum oxides
Organic matter content
Calcium carbonate content
Time of reaction/aging
Temperature
6/22/2008
WBL
65
Phosphorus Cycle
Plant biomass P
Runoff,
Atmospheric
Deposition
Outflow
Litterfall
POP
DIP
PIP
DIP
Periphyton P
Peat
accretion
DIP
DOP
6/22/2008
DOP
POP
DOP
AEROBIC
[Fe, Al or
Ca-bound P]
DIP
Adsorbe
d IP
PIP
ANAEROBIC
WBL
66
33
Organic Phosphorus
Plant Litter
Attached
to plant
Detritus
deposited
on soil surface
Decomposed
detritus from
pervious years
POP
POP
Leaching
EA
DOP
DOP
EA
Epiphytic
periphyton
i h t
EA
DIP
Benthic
periphyton
Microbial
biomass
POP
EA
DOP
EA
DIP
Inorganic
solids
DIP
Inorganic
solids
Microbial
biomass
Well decomposed
detritus accreted
into soil
6/22/2008
POP
EA
DOP
EA
WBL
67
Organic Phosphorus
Plants
Animals
Microbes
Detrital Matter
Phytin
Phospholipids
Nucleic acids
Sugar phosphates
Humus
Inorganic Phosphate
6/22/2008
WBL
68
34
Organic P fractions (% of total organic P)
in growing organisms and soils*
E. coli
Fungi Spirodella Nicotiana
Soils
Nucleic Acids
65
58
60
52
2
Phospholipids
15
20
30
23
5
Monoesters
20
22
10
25
>50
*From Magid, et al., (1996) after numerous sources.
6/22/2008
WBL
69
Soil Phosphorus
Blue Cypress Marsh
1,000
TPo (mg kg-1)
T
TPo = -49 + 0.89 TP
800
600
NE
NW
SW
400
400
6/22/2008
600
800
TP (mg kg-1)
WBL
1000
70
35
Organic Phosphorus
6/22/2008
Bioavailability
y
¾ Microbial biomass P
¾ Labile organic P
¾ Fulvic acid - P
¾ Humic acid - P
¾ Residual organic P
Hi h
High
Low
WBL
71
Solution 31P NMR spectrum of an
alkaline extract of a Swedish
tundra soil
Soil phosphorus
composition
O th h
Orthophosphate
h t monoesters
t
Phospholipids
Inorganic
orthophosphate
DNA
Polyphosphate end-groups
Phosphonates
p
20
6/22/2008
P
Pyrophosphate
h
h
10
0
ChemicalWBL
shift (ppm)
-10
Mid-chain
polyphosphates
l h
h
-20
72
36
Organic Matter Decomposition
and Nutrient Release
Oxygen
Reduction
Extracellular
Enzymatic
Activity
Nitrate
Reduction
Hydrolysis
Organic Complex
Matter Organic
Compounds
Simple
Organic
Compounds
Acid
Fermentation
Short-chain
Fatty Acids
Hydrogen
Periphyton/
Macrophytes
6/22/2008
Manganese
Reduction
Iron
Reduction
CO2
Bioavailable
Nutrients
Sulfate
Reduction
CO2
Reduction
CH4
Bioavailable
Nutrients
WBL
73
Phosphorus Availability
Detrital Matter
Ph i
Phytin
Phospholipids
Nucleic acids
Sugar phosphates
Organic P
+
Organic
+ P
Enzymes
Phosphatases
6/22/2008
WBL
74
37
Enzyme – Catalyzed Reaction
S+E
ES
S = Substrate
E = Enzyme
P = Product
R
R-OH
OH + HO
HO-PO
PO32-
R-O
O-PO
PO32- + H2O
Ester
linkage
E+P
Alkaline phosphatase
6/22/2008
WBL
75
Phosphatase Activity
Periphyton APA along the WCA 2a
Nutrient Gradient
July 1996 [Newman, S]
500
400
300
200
100
0
0
6/22/2008
2
Source: Newman, unpubl’d data
4
6
8
10
12
Distance from the S10s (km)
WBL
14
16
76
38
Periphyton
6/22/2008
WBL
77
Phosphatase-Cyanobacterial Cells
C
PPB
6/22/2008
WBL
78
39
Alkaline Phosphatase Activity
Everglades- WCA-2A
p-nitrophenoll
(mg g-1 hr-1)
25
May 1996
20
Litter
15
10
0-10 cm
5
10-30 cm
0
0 1
2 3 4 5
6 7 8 9 10 11
Distance from inflow (km)
6/22/2008
WBL
79
Soil Phosphatase Activity
AP
PA, mg MUF/g ho
our
Blue Cypress Marsh
400
NE
NW [R]
300
SW
200
100
0
Mar
June
July
2001
6/22/2008
Sept
Dec
Jan
2002
WBL
80
40
Phosphatase Activity
μg p-nitrophenol g-1 h-1
[Sunnyhill Farm Wetland]
400
Acid Phosphatase
Alkaline Phosphatase
Total Phosphatase
300
200
100
0
Oxygen
Eh (mV) 616
pH
4.7
6/22/2008
Nitrate
228
7.5
Sulfate
-162
7.7
Bicarbonate
-217
6.6
WBL
81
Organic P Mineralization
mg P g-1 dw h-1
Sunnyhill Farm Wetland
140
120
100
80
60
40
20
0
y = 0.36x - 0.32
R2 = 0.72
0
100
200
300
Total Phosphatase Activity
mg p-nitrophenol g-1 h-1
6/22/2008
WBL
82
41
Microbial Biomass P
[Sunnyhill Farm Wetland]
Microbial P,
(% of total P)
30
20
10
0
Eh (mV)
pH
Oxygen
616
4.7
6/22/2008
Nitrate
228
7.5
Sulfate
-162
7.7
icarbonate
-217
6.6
WBL
83
Microbial Biomass Phosphorus
[Water Conservation AreaArea-2A]
Microbial biomass P
((as % total P)
Feb'96
Aug.'96
Mar. '97
25
20
15
0-10 cm Soil
Depth
10
5
0
0
2
4
6
8
10
Distance from inflow (km)
42
Lake Apopka Marsh
70
Soluuble reactive P, mg m-2
g m-2
1.5
SO4 -S
1
0.5
NO3 -N
O2
0
0
2
4
6
Time, days
60
50
40
30
20
10
0
0
4
2
6
Time, days
6/22/2008
WBL
85
Lake Apopka Marsh
Soluble P, mg L-1
Deepth, cm
0
2
4
6
8
Dissolved Fe, mg L-1
1
2
3
0
30
20
Water
10
0
-10
Soil
-20
6/22/2008
WBL
86
43
Periphyton-Phosphorus-Interactions
BP = Benthic Periphyton
FP = Floating Periphyton
EP = Epiphytic Periphyton
FP
EP
Soluble P
Ca
Water
Ca -P
BP
Soluble P
Soil
6/22/2008
WBL
87
Calcareous Periphyton Mats
6/22/2008
WBL
88
44
Calcareous Periphyton Mats
Without CaCO3
With CaCO3
6/22/2008
WBL
89
6/22/2008
WBL
90
45
6/22/2008
WBL
91
Distribution of 32P between
Water and Benthic Periphyton
Water DRP = 5 ug L-1
Light = 10 W m-2
Periphyton
Abi ti
Abiotic
10%
74%
22%
88%
Biotic
6/22/2008
2%
5%
Water
1 hour
WBL
12 hour
92
46
Periphyton-PhosphorusCaCO3 Interactions
P
P
P
Periphyton
P
P
P
Solution P
CaCO3
6/22/2008
WBL
93
Plant Tissue Phosphorus
Phosphorus-WCA--2A
WCA
Total P (mg kg-1)
T
3000
2500
Live-above ground
Detritus-above ground
Below ground
2000
1500
1000
500
0
F-1
Typha
Impacted
6/22/2008
F-3
Typha
F-3
Cladium
Transition
WBL
F-5
Cladium
Unimpacted
94
47
Phosp
phorus Accumulattion
(g/m2 year)
Everglades-WCA 2A
1.2
R2 = 0.969
1
0.8
0.6
0.4
0.2
0
0
5
10
15
20
25
Calcium Accumulation
6/22/2008
30
35
(g/m 2 year)
WBL
95
Soil/Sediment-Water
Interactions
DIP
Water
DOP
Diffusion
PIP
Resuspension
POP
Sedimentation
Soil/Sediment
DIP DOP
Porewater
PIP
POP
48
Total Phosphorus in WCA-2A soils (0-10 cm)
1990
1998
6/22/2008
WBL
DeBusk et al. 2001
97
Waterr Column Phosph
horus
Phosphorus Memory
External Load
Reduction
Background
Level
Internal
Memory
Lag time for Recovery
Time - Years
6/22/2008
WBL
98
49
Internal Phosphorus Load
Water Column
Soil
6/22/2008
WBL
99
Nutrient Impacts in Wetlands
External
Nutrient
Load
Periphyton
Vegetation
Water
Internal
Nutrient
Load
Detritus
0-10 cm
10-30 cm
6/22/2008
Microbial/Chemical
Processes
WBL
100
50
Soluble Phosphorus Flux
from Sediments
6/22/2008
WBL
101
Lower St. Johns
River- SRP Profiles
[Malecki et al. 2003]
Beauclair
Bluff
Racy
Point
-20
-20
-20
-20
-20
-20
-20
-15
-15
-15
15
-15
15
-15
15
-15
-15
-10
-10
-10
-10
-5
-5
-5
-5
0
0
-10
-10
-10
-5
-5
Depth (cm)
Collee
Cove
Doctors
Lake
5
0
55
10
10
10
15
15
15
20
20
0
25
25
20
30
30
25
35
35
30
40
35
0
4
8
12
45
0
4
8
12
SRP concentration (mg -1
L
-1
SRP conc. (mg L-1)
SRP conc. (mg L )
4.09 ± 0.03
2.64 ± 0.85
mg m-2 d-1
mg m-2 d-1
6/22/2008
)
WBL
55
55
10
10
10
10
15
15
15
15
20
20
20
20
25
25
25
25
30
30
30
30
35
35
0
35
35
4
8
12
-1
SRP concentration (mg L-1 )
SRP conc. (mg L )
0
4
8
12
SRP concentration
SRP
conc. (mg(mg
L-1L ) -1)
7.38 ± 1.71
1.26 ± 0.29
mg m-2 d-1
mg m-2 d-1
102
51
Internal vs. External Loads
Lower
St. Johns River Estuary
TN
44%
32%
Total Non-point
Total Point Source
Total Internal Load
24%
Total = 7,969 mt year-1
TP
25%
42%
Total Non-point
Total Point Source
Total Internal Load
33%
6/22/2008
[J. R. white 2004]
WBL
Total = 1,600 mt year-1
103
Phosphorus Flux
from Soil to Water Column
Station
Porewater
Benthic
Incubated
equilibrators chambers Soil cores
[mg P/m2 day]
[km]
1.4
0.3
10.0
6.5
3.3
0.8
9.1
1.5
ND
ND
10.1
6/22/2008
-0.001
WBL
104
52
Flooded Agricultural Land
Lake Griffin Flow-way, Florida
Station
P – Flux
mg P m-2 day-1
DRP
TP
EPCw
mg L-1
1D
0.40
0.74
0.11
2E
0.94
1.54
0.25
3D
1.62
2.38
0.43
5C
0.25
0.34
0.07
P memory = 30 – 140 years
6/22/2008
WBL
Reddy et al., 1997
105
Internal Phosphorus Load
Everglades -WCA-2A
P flux
((mg P /m2 dayy)
6
5
4
3
2
1
0
0
2
4
6
8
10
12
Distance from inflow (km)
6/22/2008
WBL
106
53
P flux
(m
mg P /m2 day)
Phosphorus Flux from Flooded
Agricultural Land
6
5
4
3
2
1
0
0
y = 5.31 e-0.051x
R2 = 0.95
10
20
30
40
Time after flooding (months)
6/22/2008
WBL
107
Soluble Phosphorus Flux
from Wetlands
mg/m2 day
Lake Apopka Marsh
2- 5.5
Disney World
0.3 - 1.1
0.02 – 0.16
Orange County
STA-1W
0.3- 1.6
6/22/2008
WBL
108
54
Soluble Phosphorus Flux
from Sediments [mg P/m2 day]
Lake Apopka
Lake Okeechobee
Mud Zone
Peat Zone
Sand Zone
Littoral Zone
Lower St
St. Johns River
Lake Barco
Indian River Lagoon
Otter Creek
Tampa Bay
6/22/2008
1 - 5.3
0.1 - 1.9
0.2 - 2.2
0.1 - 0.5
0.6 - 1.5
1 3 - 7.4
1.3
74
0.02 - 0.05
0.6 - 1.7
-0.8 - 3.3
1.9 - 6.3
WBL
109
Soluble Phosphorus Flux
from Sediments
DRP
PP
Water column
DRP
PP
Sediment
6/22/2008
WBL
110
55
Lake Apopka Marsh Soils
Soluble P released into floo
odwater
(mmol P/kg)
[Effect of Chemical Amendments on Phosphorus Release]
0.15
CaCO3
01
0.1
Ca(OH)2
6.3 t/ha
8.6 t/ha
0.05
0
0.15
Dolomite
CaCO3 + Ca(OH)2
0.1
4 3 + 3.2
4.3
3 2 t/ha
t/h
0.05
8.2 t/ha
0
0
200 400 600 800 1,000
0
200 400 600 800 1,000
Ca2+ added (mmol/kg)
6/22/2008
WBL
111
Lake Apopka Marsh Soils
Solub
ble P released into flo
oodwater
(mmol P/kg)
[Effect of Chemical Amendments on Phosphorus Release]
0.15
(a)
Alum
4.0 t/ha
0.05
1.0 t/ha
0
5
4
0.15
Alum + CaCO3
0.1
(c)
2.1 + 4.3 t/ha
(d)
FeCl3 + CaCO3
0.5 + 2.5 t/ha
0.05
0
0
10
20
30
40 0
Al3+ added (mmol/kg)
6/22/2008
(b)
FeCl3
0.1
WBL
10
20
30
40
Fe3+ added (mmol/kg)
112
56
Processes Controlling Phosphorus
PO43-
O2
Water Column
diffusion
precipitation
FePO4
Soil/Sediment
(amorphous)
burial
Periphyton/Detritus
Fe3+ + PO43-
Organic
g
P
oxidation
Fe2+
Aerobic
PO43-
diffusion
burial
diffusion
reduction
Fe2+ + PO43-
FePO4
Organic P
(amorphous)
3 Fe2+ + 2 PO43-
Fe3(PO4)2
precipitation
Anaerobic
Fe2+
+ CO3
(vivianite)
FeCO3
2-
(siderite)
3Ca2+ + 2PO43-
B-Ca3(PO4)2
(beta tricalcium phosphate))
Ca2+ + CO326/22/2008
CaCO3
(calcite))
WBL
113
Phosphorus Cycle
Plant biomass P
Runoff,
Atmospheric
Deposition
Outflow
Litterfall
POP
DIP
PIP
DIP
Periphyton P
Peat
accretion
DIP
DOP
6/22/2008
DOP
POP
DOP
AEROBIC
[Fe, Al or
Ca-bound P]
DIP
Adsorbe
d IP
PIP
ANAEROBIC
WBL
114
57
Phosphorus Cycling Processes
Summary
™ Common inorganic phosphorus pools include: loosely bound;
fractions associated with Al, Fe, and Mn oxides and hydroxides;
Ca and Mg bound fraction; minerals
™ Phosphate is not commonly used as an oxidant, but is affected by
redox dynamics. Oxidized forms of iron can react with
phosphorus and form insoluble compounds
™ Soil’s capacity to adsorb phosphorus is regulated by the EPCo, at
which point adsorption equals desorption
™ Inorganic
I
i phosphorus
h
h
retention
t ti iis regulated
l t db
by pH,
H Eh
Eh, phosphate
h
h t
concentration (there is a limited amount of substrate for
adsorption), concentrations of Fe, Al, and calcium carbonate, and
temperature
6/22/2008
WBL
115
Phosphorus Cycling Processes
Summary
™ Much of the organic phosphorus is present as monoesters and
diesters. Monoesters include sugar phosphates,
phosphoproteins, mononucleotides, and inositol phosphates.
Diestersinclude nucleic acids, phospholipids, and aromatic
compounds. Compared to monoesters, diesters are more
accessible to microbial attack.
™ Organic phosphorus availability from monoesters requires
enzymatic cleavage of the ester linkage. This occurs primarily
g several extracellular enzymes
y
such as p
phosphatases
p
through
through hydrolysis of phosphate esters.
™ The “phosphorus memory” can extend the time required for a
wetland or an aquatic system to reach an alternate stable
condition to meet environmental regulation such as TMDLs (total
daily maximum daily load
6/22/2008
WBL
116
58