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