geochemistry of phosphorus in a carbonate aquifer affected by seawater intrusion
DESCRIPTION
Geochemistry of phosphorus in a carbonate aquifer affected by seawater intrusion. René M. Price (FIU) Jeremy C. Stalker (FIU) Jean L. Jolicoeur (FIU). Naples. Everglades National Park. A. 2003 Salinity contour In wells < 25 m. A’. A. A '. Sea Level. 0. Biscayne Aquifer. - PowerPoint PPT PresentationTRANSCRIPT
Geochemistry of phosphorus in a carbonate aquifer affected
by seawater intrusion
René M. Price (FIU) Jeremy C. Stalker (FIU)Jean L. Jolicoeur (FIU)
Naples
Everglades National Park
2003 Salinity contourIn wells < 25 m
A
A’
50
100
300
Hawthorn Group
Floridan Aquifer
met
ers
Sea Level 0 Biscayne AquiferTamiami Sands
Gray Limestone AquiferUnnamed Sands
1000
Hawthorn Group (Aquiclude)
Surficial Aquifer
Seawater IntrusionSeawater Intrusion
A A'
Sites sampled in Sept. 2007 Surface water Porewater (30-60 cm) Wells (2 – 8 m)
Geochemical Parameters P, N, TOC Ca2+, Mg2+, N+, K+, Cl-, SO4
2-, HCO3-
pH, Temp, Sal.
Groundwater Sampling
0
2
4
6
8
10
0 10 20 30 40
salinity (psu)
TP
(m M
)
Surface Water
Groundwater
Gulf of Mexico
0
2
4
6
8
10
0 10 20 30 40
salinity (psu)P
O43-
(m M
)
Surface Water
Groundwater
Gulf of Mexico
(Boyer et al., 1999)
y = 0.12x - 0.49
R2 = 0.59
0
2
4
6
8
10
0 10 20 30 40
salinity (psu)P
O43-
(m M
)
Surface Water
Groundwater
Gulf of Mexico
Linear (Groundwater)
y = 0.1427x
R2 = 0.4061
0
2
4
6
8
10
0 10 20 30 40
salinity (psu)
TP
(m M
)
Surface Water
Groundwater
Gulf of Mexico
Linear (Groundwater)
-2.0
-1.5
-1.0
-0.5
0.0
0.5
1.0
0 25 50 75 100
% seawater
SI a
rag
on
ite
Surface water
Supersaturation (mineral precipitation)
undersaturation (mineral dissolution)
-2.0
-1.5
-1.0
-0.5
0.0
0.5
1.0
0 25 50 75 100
% seawater
SI a
rag
on
ite
Surface water
-2.0
-1.5
-1.0
-0.5
0.0
0.5
1.0
0 25 50 75 100
% seawater
SI a
rag
on
ite
Surface water
groundwater
-2.0
-1.5
-1.0
-0.5
0.0
0.5
1.0
0 25 50 75 100
% seawater
SI c
alci
te
Surface water
groundwater
-10.0
-8.0
-6.0
-4.0
-2.0
0.0
0 25 50 75 100
% seawater
SI a
pat
ite
Surface water
groundwater
Research Question
How much P is incorporated in Biscayne Aquifer limestone?
What are the adsorption/desorption characteristics of P in fresh versus salty
groundwater?
Water-Rock Interactions
Ion Exchange
CaCO3
Dissolution
P Extraction Methods
0.5 g rock Dried and weighed
Sequential Extraction1. MgCl – loosely adsorbed fraction 2. HCl digestion followed by filtration
for total P determinations3. Total P determination on filter
residue for organic fraction
Phosphorus in Biscayne Aquifer Limestone
0
10
20
30
40
50
looselyadsorbed
HCl organic total
P Fraction
g P
/g r
ock
Adsorption/Desorption cube experiments
• Cube 0.2m on a side of Key Largo Limestone. • freshwater (DIW) and seawater matrix
• with PO43- varying from 0 to 20μM
6
2
3 4 5
6
2
3 4 55
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.01.0
conservative non-conservative
Breakthrough Curves
C/C
o
liters
DIW with 8 and then 20 mM of P
Adsorption
Liters through the cube
0 10 20 30 40 50
Pout / P
in (
%)
0.0
0.2
0.4
0.6
0.8
1.020 mM of P : 60% of P adsorbed 8 mM of P : 80% of P adsorbed
DIW vs. Seawater with 8 mM of PO43-
Adsorption
Liters through the cube
0 10 20 30 40 50
Pout / P
in (
%)
0.0
0.2
0.4
0.6
0.8
1.0
DIW + 8 mM of PO4 : 80% of P Adsorbed SW + 8mM of PO4: 15% of P Adsorbed
Desorption
Liters through the cube
0 20 40 60 80 100
P ou
t (m M
/L)
0
5
10
15
20
Sal
inity
fra
ctio
n
0.0
0.2
0.4
0.6
0.8
1.0
Seawater DIWSalinity
Geochemical Analysis
Cl - (mM)
0 100 200 300 400 500 600
Ca
2+ (
mM
)
0
2
4
6
8
10
12
14
Left - DI, Right - SW
Seawater mixing line
SW + PSW FlushingDI + PDI FlushingSW + DI Mixed
Cl- (mM)
0 100 200 300 400 500 600
HC
O3- (
mM
)
0.0
0.5
1.0
1.5
2.0
2.5
3.0
Left - DI, Right - SW
Seawater mixing line
SW FlushingDI + PDI FlushingSW + DI Mixed
Water Table
Seawater Intrusion
Brackish Zone
OceanP Ion Exchange
CaCO3
Dissolution
Conclusions
Publications• Price, R.M, and P.K. Swart, 2006, Geochemical indicators of
groundwater recharge in the Surficial Aquifer System, Everglades National Park, Florida, USA, in Harmon, R.S., and Wicks, C., eds., Perspectives on karst geomorphology, hydrology, and geochemistry—A tribute volume to Derek C. Ford and William B. White: Geological Society of America Special Paper 404:251-266.
• Price, R.M., P.K. Swart, and J.W. Fourqurean, 2006, Coastal groundwater discharge-an additional source of phosphorus for the oligotrophic wetlands of the Everglades, Hydrobiologia, 569:23-36.
• Price, R.M, J.D. Happell, Z. Top, and P. K. Swart. 2003, Use of tritium and helium to define groundwater flow conditions in Everglades National Park. Water Resources Research, 39(9), doi:10.1029/2002WR001929.
Acknowledgements• Jim Fourqurean –FIU Biology and SERC• Len Scinto-FIU SERC• Tatiana Marquez-FIU Environmental Sciences• Srikumar Roy- IIT Kharagpur, India• Kevin Cunningham-USGS• Chris Reich-USGS• Kevin Cunningham-USGS• Chris Reich-USGS• Thomas Smith III- USGS• Gordon Anderson - USGS• Vic Engel - ENP• Jana M. Newman – SFWMD
Funding Provided by: South Florida Water Management District and the Southeast Environmental Research Center
PHREEQC Results
Chloride (mM)
0 100 200 300 400 500 600
Sat
urat
ion
inde
x
-2
-1
0
1
2SW SIcDI SIcSW SIaDI SIa
Western Coastline of ENPSept. 2007
Gulf of Mexico(Boyer et al. 1999)
y = -0.74x + 103.57
R2 = 0.02
0
50
100
150
200
250
0 5 10 15 20 25 30 35 40
salinity (psu)
To
tal N
(m M
)
Surface Water Groundwater Linear (Groundwater)