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Proposal Seminar
Biogeochemical Controls Regulating Long-term Burial of Phosphorus in Wetland Soils
M. M. Fisher
Dissertation Proposal
November 5, 2004
Proposal Seminar
Source of Impairment to US Waters
02468
10121416
PATHOGENS
METALS
NUTRIENTS
SILTATIO
NDO
FISH pH
HABITAT
THERMAL
BIOLO
GICAL
FLOW
ALT
ERATION
PESTICID
ES
TURBIDIT
Y
SUSPENDED SOLI
DS
SALINIT
Y
UNKNOWN
% o
f A
ll Im
pai
rmen
ts
Source: 1998 USEPA 303d List of Impaired Waters
Background
40% of US Surface Waters Impaired
Proposal Seminar
•35% of large lakes do not meet designated use due to excess nutrients
Florida: Nutrient Impairment
Source: Integrated Water Quality Assessment for Florida: 2004 305(b) Report and 303(d) List Update.
Proposal Seminar
Eutrophication leads to:1. undesirable changes in flora and fauna; algal
blooms, fisheries impacts.2. for wetlands: changes in primary producers to
higher nutrient status plants such as cattails; loss of diversity.
Restoration of aquatic ecosytems req’d. by 1972 Clean Water Act to fishable & swimmable condition.
Nutrients, Legislation, and Restoration
Proposal Seminar
• Meet FDEP surface water criteria (TSI)• Reference lake/wetland approach• Historical anecdotal information:
• status of the fishery• extent of submerged aquatic vegetation• water clarity
• Investigate the soil/sedimentary record (paleolimnolgy)
Establishing Restoration Targets
Proposal Seminar
Source: Engstrom and Brezonik. 1998. Modern and historic accumulation rates of phosphorus in Lake Okeechobee sediments. J. Paleolimn. 20:31-46.
Lake Okeechobee, Florida
Sediment TP, mg/kg
Sed
imen
t D
ep
th,
cm
Proposal Seminar
Source: Rydin, E. 2000. Potentially mobile P in Lake Erken sediments. Water Res. 34:2037-2042.
Lake Erken, Sweden
Proposal Seminar
Dep
th (
or ti
me)
Concentration
soilwater
Typical sediment nutrient profile
Proposal Seminar
Peat Soil Phosphorus: Predominately Organic
Blue Cypress Marsh
400
600
800
TP
o (m
g kg
-1)
400 600 800 1000TP (mg kg-1)
NE
NW
SW
TPo = 0.89*TP -491,000
Proposal Seminar
H1: Changes in soil phosphorus fractions, with respect to depth (time) are principally due to biogeochemical changes in soil organic matter (SOM).
Ho: Changes in phosphorus fractions, with respect to depth (time) are principally due to other factors such as changes in phosphorus loading rates.
Hypothesis
Proposal Seminar
Determine the distribution of soil organic P (SOP) fractions, as a function of depth, or time.
Characterize SOM fractions, as a function of depth, or time.
Coupling of biogeochemical transformations of SOP and SOM pools to stability and long-term burial
Objectives
Proposal Seminar
Study LocationsBlue Cypress Marsh
Conservation Area (BCMCA)
Water Conservation Area 2A (WCA2A)
Proposal Seminar
Study Location: Blue Cypress Marsh Conservation Area
Size = 120 km2
Histosols, 1 - > 5 m
Sawgrass, maidencane, slough
Soft water, pH 6.5
Impacted Pristine
Proposal Seminar
Study Location: Water Conservation Area 2A
Size = 447 km2
Histosols, 1 - 2 m
Sawgrass, slough, tree islands
Calcareous
Impacted Pristine
Proposal Seminar
Experimental MethodsSoil O-P Fractionation
Experiment I Phosphorus Fractionation
Experiment II Autoclave Extraction (0.5 g, 90 min, 128C)
Experiment III Potentially Mineralizable organic P
(0.5 g, anaerobic, 10d, 40C)
Experiment IV Thermal Extraction
Proposal Seminar
Preliminary Results: Organic PhosphorusCharacterization
Proposal Seminar
0 400 800-160
-140
-120
-100
-80
-60
-40
-20
0
BCMCA (B4)
WCA2A (E5)
Depth Distribution of Total Phosphorus
TP, mg/kg
Proposal Seminar
BCMCA
9%
9%
29%
17%
36%
Bicarb-Pi
HCl-Pi
FAP
HAP
Res. P
TP = 327 mg/kg
WCA2A
23%
28%21%
25%
3%
TP = 197 mg/kg
Experiment I: Organic P Fractionation
(0-50 cm, unimpacted sites)
Proposal Seminar
0 40 80
-140
-120
-100
-80
-60
-40
-20
0
BCMCAWCA2A
HEP, % of TP
0 40 80
De
pth
, cm
Impacted Unimpacted
Autoclave extraction[HEP = Hot water extractable P]
Proposal Seminar
0
20
40
60
80
100
160
200
260
300
360
550
0-10 cm
160
200
260
300
360
550
Temperature, C
40-50 cm
160
200
260
300
360
550
90-100 cm)
% o
f TP
Thermal P ExtractionBCMCA
Proposal Seminar
C:N
Dep
th,
cm
0 10 20 30 40
-140
-120
-100
-80
-60
-40
-20
0
BCMCA
WCA2A
Everglades & Blue Cypress MarshCarbon : Nitrogen Ratio
Proposal Seminar
C:P
De
pth
, cm
Everglades & Blue Cypress MarshCarbon : Phosphorus Ratio
0 4000 8000
-140
-120
-100
-80
-60
-40
-20
0
WCA2A
BCMCA
Proposal Seminar
Preliminary Conclusions
BCMCA historically higher nutrient status marsh.
Thermal techniques indicate increasing O-P stability.
Proposal Seminar
Experimental MethodsCharacterize SOM (BCMCA)
Experiment I OM fluorescence
Experiment II E4:E6
Experiment III Isotope analysis: 13C , 15N, 14C (ecosystem history, transformation rates)
Experiment IV 13C-NMR (broad classes of SOM)
Experiment V Lignin, cellulose, hemicellulose
Proposal Seminar
Preliminary Results:OM Characterization
Proposal Seminar
HIX0 2 4 6 8 10 12
-140
-120
-100
-80
-60
-40
-20
0
Plant tissue
Detritus
Dep
th, c
m
Experiment I: Humification Index
Proposal Seminar
E4:E6
0 2 4 6 8 10 14
-140
-120
-100
-80
-60
-40
-20
0
B4
C1
+humic
+MW
+fulvic
Experiment II: E4 E6 Ratio
Proposal Seminar
Preliminary Conclusions
Increased humic characteristics of SOM extracts with respect to depth.
Slight increase in apparent molecular weight of SOM extracts with respect to depth.
Proposal Seminar
Model: SOP Diagenesis
Dep
th
SOP
RecalcitranceHumic character
Time
Proposal Seminar
“In paleolimnology...diagenesis is at best an annoyance and at worst a nightmare, weakening
nearly every generalization that investigators may wish to make”
(Binford, Deevey, and Crisman, 1983, Paleolimnology: an historical perspective on
lacustrine ecosystems)
Proposal Seminar
Wet soil
1M HCL3 hrs
0.5M NaOH 16 hrs
Separate into fulvic and humic fractions
Wet soil residue
0.5M NaHCO3
16 hrs
Sequential O-P Fractionation
Ivanoff, D.B., K.R. Reddy, and S. Robinson. 1998. Chemical fractionation of organic phosphorus in selected Histosols. Soil Science. 163:36-45.
Proposal Seminar
0
100
200
300
400
500
250 350 450 550 650Flu
ore
scen
ce In
ten
sity
Wavelength, nm
Example: Fluorescence
Humification Index (HIX) = 435 480300-345
Increased absorbance: red-shift
Proposal Seminar
Pyrolysis Extraction
Inert atmosphere160, 200, 260, 300, 360, 550 oCBatch loaded1 hour combustionExtract w/ 1M HCl
Proposal Seminar
Chen, Y., N. Senesi, and M. Schnitzer. 1977. Information provided on humic substances by E4/E6 ratios. Soil Sci. Soc. Am. J. 41:352-358
E4:E6
17 hr, 0.5 M NaOH ExtractAbsorb. 445 & 465Ratio is related to molecular
weight