Transcript soils.ifas.ufl.edu

Institute of Food and Agricultural Sciences (IFAS)
Biogeochemistry of Wetlands
Science and Applications
Phosphorus Cycling Processes
Wetland Biogeochemistry Laboratory
Soil and Water Science Department
University of Florida
Instructor
K. Ramesh Reddy
[email protected]
7/16/2015
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Institute of Food and Agricultural Sciences (IFAS)
Phosphorus Cycling Processes
DRP
PP
Water column
DRP
PP
Soil
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Phosphorus Cycling Processes
Topic Outline
Water Column
 Introduction
 Forms of phosphorus
 Inorganic Phosphorus retention




mechanisms
Organic phosphorus dynamics
Phosphorus exchange between soil and
overlying water column
Regulators of phosphorus reactivity and
mobility
Phosphorus memory in wetlands
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Soil
3
Phosphorus Cycling Processes
Learning Objectives







Identify sources, and inorganic and organic forms of
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
Phosphorus exchange between soil and overlying water
column
Draw the phosphorus cycle and indentify, storages,
abiotic and biotic processes, and fluxes in soil and water
column
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Terminology
 Total Phosphorus (TP)
 Dissolved total P (DTP)
 Total P in solutions filtered through 0.45 um membrane filter
 Dissolved reactive P (DRP) or Soluble Reactive P (SRP)
 Water samples filtered through 0.45 um membrane filter and
analyzed for ortho-P.
 Dissolved Organic P (DOP)
 DTP – DRP = DOP
 Particulate inorganic P (PIP)
 Particulate matter or soil extracted with acid
 Particulate organic P (POP)
 TP-PIP = POP
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Phosphorus Cycle
Plant biomass P
Runoff,
Atmospheric
Deposition
Outflow
Litterfall
POP
DIP
PIP
DIP
Periphyton P
Peat
accretion
DIP
DOP
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DOP
POP
DOP
AEROBIC
[Fe, Al or
Ca-bound P]
DIP
Adsorbed
IP
PIP
ANAEROBIC
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Fertilizers, Animal wastes
Biosolids, Wastewaters
Phosphorus Transfer
Uplands
[sink/source]
Wetlands &
Streams
[sink/source]
Lake
Lake [sink]
Okeechobee
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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
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1996
8
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]
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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 amounts of P has accumulated in
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?
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Phosphorus Memory
in a Watershed

Capacity for storing phosphorus in
various ecosystem components
(uplands, wetlands, and aquatic
systems)




Transient pools
Stable pools
P
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
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Water Column
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P
Soil
11
Phosphorus Transfer
[4157]
[Lake Okeechobee Basin]
Phosphorus Budget
[tons/year]
Uplands (82%)
[754]
[415] (10%)
Wetlands
& Streams
(8%)
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Lake
Okeechobee
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Phosphorus Gradient in
Wetlands
Phosphorus
Loading
Phosphorus
Outflow
Gradient in nutrient enrichment in
soil and water column
[ Distance from inflow]
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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)
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Phosphorus accretion rates in
Everglades WCA-2A
P 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)
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Total P concentration in WCA-2A soil (0-10 cm)
1990
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1998
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Everglades – Soil phosphorus
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Soil Phosphorus
Depth (cm)
Blue Cypress Marsh-1992
0-4
0-4
4-8
8-12
8-12
16-20
12-16
16-20
20-24
24-28
32-36
40-44
24-28
32-36
Unimpacted
36-40
0
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1,000 2,000
Impacted
0
1,000 2,000
Total
WBL P (mg /kg)
18
Water Column Phosphorus
Phosphorus Memory
External Load
Reduction
Background
Level
Internal
Memory
Lag time for Recovery
Time - Years
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Ecological Significance –
Phosphorus Loading
PLANTS
WATER
N C
DETRITUS
P
Microbial
Biomass
P
SOIL
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NC P
Labile
DETRITUS
Microbial
Biomass
N
P N
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Phosphorus Cycle
Plant biomass P
Runoff,
Atmospheric
Deposition
Outflow
Litterfall
POP
DIP
PIP
DIP
Periphyton P
Peat
accretion
DIP
DOP
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DOP
POP
DOP
AEROBIC
[Fe, Al or
Ca-bound P]
DIP
Adsorbed
IP
PIP
ANAEROBIC
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Phosphorus in Wetlands
Phosphorus
loading
Organic
phosphorus
Uptake by
algae and
plants
Soil porewater
phosphorus
[dissolved]
Metal oxides
and clay mineral
surfaces
Discrete
phosphate
minerals
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Soil Phosphorus Forms
 Inorganic P

—
KCl-Pi - Bioavailable P
—
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]
—
—
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Residual P -Highly resistant [unavailable]
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Phosphate ions and pH
 H3PO4 = H+ + H2PO4- pK = 2.15
 H2PO4- = H+ + HPO42- pK = 7.20
 HPO42- = H+ + PO43- pK = 12.35
Oxidation number for P
PO43- [+5]
PH3 [-3]
H3PO4 [+5]
H2PO4- [+5]
HPO42- [+5]
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Total Inorganic P (mg kg-1)
Inorganic PhosphorusOrganic Soils - WCA-2A
3,000
1,000
Y = 0.01X1.54
R2 =0.897; 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 )
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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
Total P = 877 mg P/kg
7%
11%
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10%
1%
71%
Rucks-Stream
Total P + 93 mg P/kg
26
Organic Wetland Soils –
Drainage Effects
<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 P = 836 mg P/kg
1% 7%
24%
47%
Peat Depth > 30 cm
Total P = 411 mg P/kg
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21%
27





Pore water P
Exchangeable
Fe-/Al- bound P
Ca-/Mg-bound P
Residual P
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Bioavailability
Inorganic Phosphorus
High
Low
28
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]
Ca3 (PO4)2 [Tricalcium phosphate]
Ca5 (PO4)3 OH [Hydroxyapatite]
Ca5 (PO4)3 F [Fluorapatite]
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1 mm
5 mm
Phosphate Minerals
Apatite
Vivianite
W. G. Harris, 2002
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Phosphate Availability
 Readily available phosphates
 Soil porewater.
 Slowly available phosphates
 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.
 Very slowly available phosphates
 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
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Phosphorus
 Is P one of the redox elements ?
 HPO42- + 10H+ + 8e- = PH3 + 4H2O
 Is P solubility affected by changes in
redox potential?
 FePO4 + H+ + e- = Fe2+ + HPO42-
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Phosphorus Retention
by Soils
 Adsorption –Desorption
 Precipitation – Dissolution
 Immobilization - mineralization
Retention = Adsorption + Precipitation
+ Immobilization
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Sorption of Phosphate
Intensity factor : Concentration of
phosphate in soil porewater.
Capacity factor : Ability of solid
phases to replenish phosphate as it
is depleted from solution.
Solid
phas
e
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Padsorbed
Psolution
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Inorganic Phosphate
Reactions
 Precipitation by Al, Fe, Mn, Ca, and Mg ions
 Al3+ + H2PO4- + 2H2O = 2H+ + Al (OH)2 H2PO4 (insoluble) (Variscite)
 Anion exchange

Al OH2+
OH + H2PO4- =
Al OH2+ H2PO4 + OH-
 Reaction with hydrous oxides
Al
OH
OH + H2PO4- = Al
OH
 Fixation by silicate clays
OH
OH + OHH2PO4
 Al2 SiO5 (OH)4 + 2H2PO4- = 2Al (OH)2 H2PO4 + Si2O52-
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Charge
pH- Dependent Charge
on Solid Phase
Negative charge
[loss of H+]
[-]
0
[+]
Positive charge
[gains H+]
3
4
5
6
ZPC
[zero point charge]
7
8
9
10
pH
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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]
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=
Al–O- + H2O
COO- + H2O
AlOH2+
AlOH + H+
No charge
[Intermediate pH]
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AlOH2+
Positive charge
[low pH]
37
Inorganic Phosphate Reactions
Alkaline pH conditions:
 Ca2+ + 2H2PO4- = Ca (H2PO4)2
 Ca (H2PO4)2 + Ca2+ + 2OH- = 2CaHPO4 + 2H2O
 2CaHPO4 + Ca2+ + 2OH- = 2Ca3 (PO4)2 + 2H2O
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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]
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Water
Pw
Pad
Ps
Soil
Pret
Desorption Adsorption
Phosphorus Sorption Isotherm
Smax
EPCo
slope = KD
P desorption under
So ambient conditions
Phosphorus in Soil Porewater
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Desorption Adsorption
Phosphorus Sorption Isotherm
Low P Load
EPCo
High P Load
EPCo
P Retention
P Release
Phosphorus in Soil Porewater
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Influence of Phosphorus
Loading on EPC0
[Nair et al. 1997]
Land use Total P (mg/kg) EPCo (mg/L)
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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
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42
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)
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43
Phosphorus Sorption
[Richardson, 1985]
3000
P sorbed, mg/kg
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
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44
P Sorption by WCA-2A soils
2,000
Sorbed P (mg P/kg)
Ambient PW-P
1,500
Site 1
1,000
[Anaerobic]
500
Sorption
0
0.01
0.1
1
10
100
Site 8
Ambient PW-P
1,500
[Anaerobic]
1,000
Desorption
500
0
0.001
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Desorption
0.01
0.1
1
10
Sorption
100
Solution P concentration
(mg P/L)
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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
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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
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
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(C/S)
Slope = 1/Smax
1/kSmax
C
47
Desorption Adsorption
Phosphorus Sorption Isotherm
Adsorption
Smax
Precipitation
EPCo
slope = KD
P desorption under
So ambient conditions
Phosphorus in Soil Porewater
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Saturation Index (SI)
Ca Ab = aC + bA
[C]a [A]b
K=
[Ca Ab]
[C]a [A]b
Saturation Index (SI) = IAP/K
Ion Activity Product (IAP) =
SI < 1 = Solution is “undersaturated”
SI > 1 = Solution is “supersaturated”
SI = 1 = Solution saturated (near equilibrium)
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Intensity Factor
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
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50
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
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Retention
Release
Overlying Water
Sediment/Soil
P release P retention
Phosphorus Retention Isotherm
Pmax
EPCw
slope = A
P release under
ambient conditions
Phosphorus in Water Column
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Phosphorus Retention Isotherm
0
P added to water column – range of concentrations
High
EPCw
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Phosphorus Retention by
Wetlands Soils and Stream
Sediments
[Okeechobee Basin, Florida]
 Wetlands
 Pr = 118 [SRP] - 54.2
 EPCw = 0.47 mg P/L
r2 = 0.71 n = 11
 Stream sediments
 Pr = 128 [SRP] - 12.4
EPCw = 0.1 mg P/L
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r2 = 0.95 n = 175
54
40
EPCw=33 ug/L
20
0
-20 0
-40
-60
-80
-100
20
P release
by sediments
DRP retention/release
(mg/ m2 Year)
Phosphorus Retention by
Mud Sediments – Lake Okeechobee
40
60
80
100 120 140
P retention
by sediments
-120
Water Column DRP ug/L
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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 (%)
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56
Phosphorus Retention Capacity
Mineral Wetland Soils - Okeechobee
Smax (mmoles P/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]/
log of P in solution
200
160
120
80
40
00
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Y = 1.21+0.015(x)
R2 = 0.87
Richardson, 1985
2
4
6
8
10
Oxalate extractable Al, g/kg
WBL
58
Phosphorus solubility as a
function of pH and Eh
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59
Iron solubility as a
function of pH and Eh
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60
Dissolved P (uM P)
Dissolved P in Sediments
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61
Phosphorus Solubility under
Anaerobic Soil Conditions
FeS
SO42-
Fe2+ + PO43-
H2S + FePO4
[Strengite]
FePO4
[Strengite]
Fe(OH)2-PO4
Fe3(PO4)2
[Vivianite]
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62
Lake Okeechobee
32P
activity (cpm/ml)
7000
6000
Reduced
5000
4000
3000
2000
1000
0
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Oxidized
Littoral
Peat
Mud
WBL
Mud
Mud
Mud
63
Mechanisms of Phosphorus
Release in Wetlands
 Reduction of insoluble ferric phosphate 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 by organic anions
 Increased phosphate availability during sulfate
reduction
 Increased solubility of calcium phosphate in alkaline
soils as result of pH decrease under flooded
conditions
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64
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
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65
Phosphorus Cycle
Plant biomass P
Runoff,
Atmospheric
Deposition
Outflow
Litterfall
POP
DIP
PIP
DIP
Periphyton P
Peat
accretion
DIP
DOP
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DOP
POP
DOP
AEROBIC
[Fe, Al or
Ca-bound P]
DIP
Adsorbe
d IP
PIP
ANAEROBIC
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66
Organic Phosphorus
Plant Litter
Attached
to plant
Detritus
deposited
on soil surface
Decomposed
detritus from
pervious years
POP
POP
Leaching
EA
DOP
DOP
EA
EA
Epiphytic
periphyton
DIP
Benthic
periphyton
Microbial
biomass
POP
EA
DOP
EA
DIP
Inorganic
solids
DIP
Inorganic
solids
Microbial
biomass
Well decomposed
detritus accreted
into soil
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POP
EA
DOP
WBL
EA
67
Organic Phosphorus
Plants
Animals
Microbes
Detrital Matter
Phytin
Phospholipids
Nucleic acids
Sugar phosphates
Humus
Inorganic Phosphate
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68
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.
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69
Soil Phosphorus
Blue Cypress Marsh
1,000
TPo (mg kg-1)
TPo = -49 + 0.89 TP
800
600
NE
NW
SW
400
400
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600
800
TP (mg kg-1)
WBL
1000
70
 Microbial biomass P
 Labile organic P
 Fulvic acid - P
 Humic acid - P
 Residual organic P
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Bioavailability
Organic Phosphorus
High
Low
71
Solution 31P NMR spectrum of an
alkaline extract of a Swedish
tundra soil
Soil phosphorus
composition
Orthophosphate monoesters
Phospholipids
Inorganic
orthophosphate
DNA
Polyphosphate end-groups
Phosphonates
20
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Pyrophosphate
10
0
ChemicalWBL
shift (ppm)
-10
Mid-chain
polyphosphates
-20
72
Organic Matter Decomposition
and Nutrient Release
Organic Complex
Matter Organic
Compounds
Extracellular
Enzymatic
Activity
Oxygen
Reduction
Hydrolysis
Manganese
Reduction
Nitrate
Reduction
Simple
Organic
Compounds
Acid
Fermentation
Short-chain
Fatty Acids
Hydrogen
Periphyton/
Macrophytes
7/16/2015
WBL
Iron
Reduction
CO2
Bioavailable
Nutrients
Sulfate
Reduction
CO2
Reduction
CH4
Bioavailable
Nutrients
73
Phosphorus Availability
Detrital Matter
Phytin
Phospholipids
Nucleic acids
Sugar phosphates
Organic P
+
Organic
+ P
Enzymes
Phosphatases
7/16/2015
WBL
74
Enzyme – Catalyzed Reaction
S+E
ES
S = Substrate
E = Enzyme
R - O-PO32- + H2O
Ester
linkage
7/16/2015
E+P
P = Product
R-OH + HO-PO32-
Alkaline phosphatase
WBL
75
Phosphatase Activity
Periphyton APA along the WCA 2a
Nutrient Gradient
July 1996 [Newman, S]
500
400
300
200
100
0
0
7/16/2015
2
Source: Newman, unpubl’d data
4
6
8
10
12
Distance from the S10s (km)
WBL
14
16
76
Periphyton
7/16/2015
WBL
77
Phosphatase-Cyanobacterial Cells
C
PPB
7/16/2015
WBL
78
Alkaline Phosphatase Activity
Everglades- WCA-2A
p-nitrophenol
(mg g-1 hr-1)
25
20
May 1996
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)
7/16/2015
WBL
79
Soil Phosphatase Activity
APA, mg MUF/g hour
Blue Cypress Marsh
400
NE
NW [R]
300
SW
200
100
0
Mar
June
July
2001
7/16/2015
Sept
Dec
Jan
2002
WBL
80
Phosphatase Activity
mg 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
7/16/2015
Nitrate
228
7.5
WBL
Sulfate
-162
7.7
Bicarbonate
-217
6.6
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
7/16/2015
WBL
82
Microbial Biomass P
[Sunnyhill Farm Wetland]
Microbial P,
(% of total P)
30
20
10
0
Eh (mV)
pH
7/16/2015
Oxygen
616
4.7
Nitrate
228
7.5
WBL
Sulfate
-162
7.7
icarbonate
-217
6.6
83
Microbial Biomass Phosphorus
[Water Conservation Area-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)
Lake Apopka Marsh
70
SO4 -S
1
0.5
NO3 -N
O2
0
0
2
4
Soluble reactive P, mg m-2
g m-2
1.5
6
Time, days
7/16/2015
60
50
40
30
20
10
0
0
2
4
6
Time, days
WBL
85
Lake Apopka Marsh
Soluble P, mg L-1
Depth, cm
0
2
4
6
8
Dissolved Fe, mg L-1
1
2
3
0
30
20
Water
10
0
-10
Soil
-20
7/16/2015
WBL
86
Periphyton-Phosphorus-Interactions
BP = Benthic Periphyton
FP = Floating Periphyton
EP = Epiphytic Periphyton
FP
EP
Soluble P
Ca
Water
Ca -P
BP
Soluble P
Soil
7/16/2015
WBL
87
Calcareous Periphyton Mats
7/16/2015
WBL
88
Calcareous Periphyton Mats
Without CaCO3
With CaCO3
7/16/2015
WBL
89
7/16/2015
WBL
90
7/16/2015
WBL
91
Distribution of 32P between
Water and Benthic Periphyton
Water DRP = 5 ug L-1
Light = 10 W m-2
Water
Periphyton
Abiotic
10%
74%
22%
88%
Biotic
7/16/2015
2%
5%
1 hour
WBL
12 hour
92
Periphyton-PhosphorusCaCO3 Interactions
P
P
P
Periphyton
P
P
P
Solution P
7/16/2015
CaCO3
WBL
93
Plant Tissue PhosphorusWCA-2A
Total P (mg kg-1)
3000
2500
Live-above ground
Detritus-above ground
Below ground
2000
1500
1000
500
0
F-1
Typha
Impacted
7/16/2015
F-3
Typha
F-3
Cladium
Transition
WBL
F-5
Cladium
Unimpacted
94
Phosphorus Accumulation
(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
30
35
Calcium Accumulation (g/m 2 year)
7/16/2015
WBL
95
Soil/Sediment-Water
Interactions
DIP
Water
DOP
Diffusion
PIP
Resuspension
POP
Sedimentation
Soil/Sediment
DIP DOP
Porewater
PIP
POP
Total Phosphorus in WCA-2A soils (0-10 cm)
1990
7/16/2015
1998
WBL
DeBusk et al. 2001
97
Water Column Phosphorus
Phosphorus Memory
External Load
Reduction
Background
Level
Internal
Memory
Lag time for Recovery
Time - Years
7/16/2015
WBL
98
Internal Phosphorus Load
Water Column
Soil
7/16/2015
WBL
99
Nutrient Impacts in Wetlands
External
Nutrient
Load
Periphyton
Vegetation
Water
Internal
Nutrient
Load
Detritus
0-10 cm
10-30 cm
7/16/2015
Microbial/Chemical
Processes
WBL
100
Soluble Phosphorus Flux
from Sediments
7/16/2015
WBL
101
Lower St. Johns
RiverSRP
Profiles
[Malecki et al. 2003]
Beauclair
Bluff
Racy
Point
-20
-20
-20
-20
-20
-20
-20
-15
-15
-15
-15
-15
-15
-15
-10
-10
-10
-10
-5
-5
-5
-5
0
0
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
4
8
12
SRP concentration (mg L-1-1)
SRP conc. (mg L )
35
35
-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
SRP conc. (mg L-1)
0
4
8
12
SRP concentration (mg -1
L -1)
SRP conc. (mg L )
4.09 ± 0.03
2.64 ± 0.85
m-2
mg m-2 d-1
mg
7/16/2015
d-1
7.38 ± 1.71
1.26 ± 0.29
m-2
mg m-2 d-1
mg
WBL
0
4
8
12
-1
SRP concentration
SRP
conc. (mg(mg
L L ) -1)
d-1
102
Internal vs. External Loads
TN
32%
44%
Lower
St. Johns River Estuary
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%
7/16/2015
[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
7/16/2015
-0.001
WBL
104
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
7/16/2015
WBL
Reddy et al., 1997
105
Internal Phosphorus Load
Everglades -WCA-2A
P flux
(mg P /m2 day)
6
5
4
3
2
1
0
0
2
4
6
8
10
12
Distance from inflow (km)
7/16/2015
WBL
106
P flux
(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)
7/16/2015
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
7/16/2015
WBL
108
Soluble Phosphorus Flux
from Sediments [mg P/m2 day]
Lake Apopka
Lake Okeechobee
Mud Zone
Peat Zone
Sand Zone
Littoral Zone
Lower St. Johns River
Lake Barco
Indian River Lagoon
Otter Creek
Tampa Bay
7/16/2015
WBL
1 - 5.3
0.1 - 1.9
0.2 - 2.2
0.1 - 0.5
0.6 - 1.5
1.3 - 7.4
0.02 - 0.05
0.6 - 1.7
-0.8 - 3.3
1.9 - 6.3
109
Soluble Phosphorus Flux
from Sediments
DRP
PP
Water column
DRP
PP
Sediment
7/16/2015
WBL
110
Lake Apopka Marsh Soils
Soluble P released into floodwater
(mmol P/kg)
[Effect of Chemical Amendments on Phosphorus Release]
0.15
CaCO3
0.1
0.05
Ca(OH)2
6.3 t/ha
8.6 t/ha
0
0.15
Dolomite
CaCO3 + Ca(OH)2
0.1
0.05
4.3 + 3.2 t/ha
8.2 t/ha
0
0
200 400 600 800 1,000
0
200 400 600 800 1,000
Ca2+ added (mmol/kg)
7/16/2015
WBL
111
Lake Apopka Marsh Soils
Soluble P released into floodwater
(mmol P/kg)
[Effect of Chemical Amendments on Phosphorus Release]
0.15
(a)
Alum
0.1
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)
7/16/2015
(b)
FeCl3
WBL
10
20
30
40
Fe3+ added (mmol/kg)
112
Processes Controlling Phosphorus
PO43-
O2
Water Column
diffusion
precipitation
FePO4
Soil/Sediment
(amorphous)
burial
Periphyton/Detritus
Fe3+ + PO43-
Organic P
oxidation
Aerobic
Fe2+
PO43-
diffusion
burial
diffusion
reduction
FePO4
Fe2+ + PO43-
Organic P
(amorphous)
3 Fe2+ + 2 PO43-
Anaerobic
Fe3(PO4)2
precipitation
Fe2+ + CO323Ca2+ + 2PO43-
(vivianite)
FeCO3
(siderite)
B-Ca3(PO4)2
(beta tricalcium phosphate))
Ca2+ + CO327/16/2015
WBL
CaCO3
(calcite))
113
Phosphorus Cycle
Plant biomass P
Runoff,
Atmospheric
Deposition
Outflow
Litterfall
POP
DIP
PIP
DIP
Periphyton P
Peat
accretion
DIP
DOP
7/16/2015
DOP
POP
DOP
AEROBIC
[Fe, Al or
Ca-bound P]
DIP
Adsorbe
d IP
PIP
ANAEROBIC
WBL
114
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 phosphorus retention is regulated by pH, Eh, phosphate
concentration (there is a limited amount of substrate for
adsorption), concentrations of Fe, Al, and calcium carbonate, and
temperature
7/16/2015
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
through several extracellular enzymes such as phosphatases
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
7/16/2015
WBL
116