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Rupesh Bhomia, Todd Osborne,
Odi Villapando and K. R. Reddy
Soil and Water Sciences Dept., University of Florida, Gainesville, FLSouth Florida Water Management District, West Palm Beach, FL
18th April
Nutrient Storages in the Everglades Stormwater
Treatment Areas
Slide 2 of 15
Understand wetland biogeochemical processes that regulate phosphorus (P) removal efficiency and dictate long-term stabilization of P in Everglades STAs
Key Question• Can internal loading of P to the water column be
reduced or controlled, especially in the lower reaches of the treatment trains?
Objectives• Determine existing nutrient (P) storages in STA soils• Compare the differences in soil nutrient storages
between emergent and submerged vegetation
RATIONALE
Submerged AquaticVegetation (SAV)
Emergent Aquatic Vegetation (EAV)
RAS*
Pre STA Soil
Floc
*RAS = Recently Accreted Soil
WaterT
T
T = Transfer
D
D
D = Decompositionand leaching
A
A
A = Accretion
Pr
Pr = Precipitation
UU
U
U = Uptake
U
N
STA-2
Two treatment flow ways (cells) in STA-2 • Cell 1 (EAV) –> Treatment area = 744 ha• Cell 3 (SAV) –> Treatment area = 930 ha
STUDY LOCATION
Slide 4 of 15
Study cells
Cell 1Cell 3
Flow direction
Soil sampling stations
Slide 5 of 15
• Floc – comprised of unconsolidated material• RAS – determined based on color and texture• Pre-STA – layer representing antecedent soils
(before STAs began operations)
SAMPLING AND ANALYSIS
𝐒𝐨𝐢𝐥 𝐧𝐮𝐭𝐫𝐢𝐞𝐧𝐭 𝐬𝐭𝐨𝐫𝐚𝐠𝐞𝐠
𝐦𝟐
=Nutrient conc.
mgKg x BD
gcc x depth (cm)
100
RAS = Recently Accreted Soil
• Bulk density (BD) and nutrient (P, C & N) concentrations
• Nutrient storages were calculated for each layer
Slide 6 of 15
SPATIAL TRENDS – Bulk Density
Higher bulk density in SAV than EAV cells, in all soil sections
Slide 7 of 15
SPATIAL TRENDS – Phosphorus in Floc
Cell 1EAV
Cell 3SAV
TP (mg kg-1)
TP (mg kg-1)
Cell 1EAV
Cell 3SAV
P mass storage (g m-2)
(g m-2)
Avg. depth (cm) – EAV- 7.7 and SAV- 10.7
Slide 8 of 15
SPATIAL TRENDS – Phosphorus in RAS
Cell 1 EAV
Cell 3SAV
TP (mg kg-1)
TP (mg kg-1)
Cell 1 EAV
Cell 3SAV
P mass storage (g m-2)
(g m-2)
Avg. depth (cm) – EAV- 2.5 and SAV- 3.0
Slide 9 of 15
SPATIAL TRENDS – Phosphorus in pre-STA soils
Cell 1EAV
Cell 3SAV
TP (mg kg-1)
TP (mg kg-1)
Cell 1EAV
Cell 3SAV
P mass storage (g m-2)
(g m-2)
Avg. depth (cm) – EAV- 19.1 and SAV- 16.4
Slide 10 of 15
STA-2 Type Depth P N C S Ca
Cell-1 cm g m-2
EAV Floc 7.7 ± 0.4 2 ± 0.1 38 ± 2 487 ± 28 13 ± 1 96 ± 14
RAS 2.5 ± 0.2 1.7 ± 0.2 47 ± 3 680 ± 50 20 ± 2 182 ± 36
Pre-STA 19.1 ± 0.3 6.1 ± 0.3 787 ± 28 12641 ± 433 225 ± 10 1035 ± 41
Cell-3
SAV Floc 10.7 ± 0.5 8.5 ± 0.8 124 ± 9 2313 ± 161 44 ± 3.6 3621 ± 261
RAS 3 ± 0.2 3.3 ± 0.3 78 ± 8 1452 ± 134 30 ± 3 1233 ± 126
Pre-STA 16.4 ± 0.7 17.5 ± 2 1128 ± 42 18098 ± 735 278 ± 14 1815 ± 142
SOIL NUTRIENT STORAGES
Phosphorus storage in vegetation biomassEAV ~ 3 - 4 g P m-2
SAV ~ 0.5 – 1.5 g m-2
0
50
100
150
200
250
300
350
400
0 500 1000 1500 2000 2500 3000
T Ca
(g
kg-1
)
TP (mg kg-1)
RAS-EAVRAS-SAV
RAS
Slide 11 of 15
VEGETATION INDUCED DIFFERENCES
0
50
100
150
200
250
300
350
400
0 500 1000 1500 2000 2500 3000
T C
a (g
kg
-1)
TP (mg kg-1)
Floc-EAVFloc-SAV
SAV Floc
EAV Floc
Floc
0
50
100
150
200
250
300
350
400
0 500 1000 1500 2000 2500 3000
T C
a (g
kg-1
)
TP (mg kg-1)
Pre-STA-EAVPre-STA-SAV
Pre-STA
0
20
40
60
80
100
0 200 400 600 800 1000
T C
a (g
kg
-1)
TP (mg kg-1)
Pre-STA-EAVPre-STA-SAV
Slide 12 of 15
DIFFERENCES – Phosphorus forms
0
200
400
600
800
1000
0 500 1000 1500 2000 2500 3000H
Cl P
(mg
kg-1
)
TP (mg kg-1)
Floc EAV STA-2 C1
SAV STA-2 C3
Ino
rgan
ic P
y = 0.19x + 9.49
R² = 0.83
y = 0.73x - 153.98R² = 0.97
0
200
400
600
800
1000
0 500 1000 1500 2000 2500 3000H
Cl P
(mg
kg-1
)TP (mg kg-1)
Floc EAV STA-2 C1
SAV STA-2 C3
Ino
rgan
ic P
Sampling transect
Cell 1EAV
Cell 3SAV
0
200
400
600
800
1000
0 500 1000 1500 2000 2500 3000
HCl
P (
mg
kg-1
)
TP (mg kg-1)
RAS EAV STA-2 C1
SAV STA-2 C3
Slide 13 of 15
VEGETATION DIFFERENCES– Phosphorus forms
Org
anic
PO
rgan
ic P
0
500
1000
1500
2000
2500
0 500 1000 1500 2000 2500 3000T
Org
P (
mg
kg-1
)
TP (mg kg-1)
FlocEAV STA-2 C1
SAV STA-2 C3
y = 0.81x - 9.49R² = 0.99
0
500
1000
1500
2000
2500
0 500 1000 1500 2000 2500 3000T
Org
P (
mg
kg-1
)
TP (mg kg-1)
FlocEAV STA-2 C1
SAV STA-2 C3
Sampling transect
Cell 1EAV
Cell 3SAV
0
500
1000
1500
2000
2500
0 500 1000 1500 2000 2500 3000
T O
rg P
(m
g kg
-1)
TP (mg kg-1)
RASEAV STA-2 C1
SAV STA-2 C3
Slide 14 of 15
• Significant P enrichment in floc near inflows with concentrations diminishing towards outflows
• Floc P enrichment in EAV (Cell 1) was greater & spatially extensive compared to SAV (Cell 3)
• Nutrient (P, C, N, S) storages were typically higher in SAV (Cell 3) in comparison to EAV (Cell 1)
• SAV floc had higher percentage of TP as inorganic P (up to 55%) in comparison to EAV floc (20%)
• EAV floc had higher percentage of TP as organic P (up to 80%) in comparison to SAV floc (30-35%)
SUMMARY
THANK YOU!!!
This study is funded by a research grant from the South Florida WaterManagement District (SFWMD). The SFWMD Lab and the WetlandBiogeochemistry Lab, UF are acknowledged for their analytical services.