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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
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Proposal Seminar Source of Impairment to US Waters 0 2 4 6 8 10 12 14 16 PATHOGENS METALS NUTRIENTS SILTATION DO FISH pH HABITAT THERMAL BIOLOGICAL FLOW ALTERATION PESTICIDES TURBIDITY SUSPENDED SOLIDS SALINITY UNKNOWN % of All Impairments Source: 1998 USEPA 303d List of Impaired Waters Background 40% of US Surface Waters Impaired
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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.
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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
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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
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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 Sediment Depth, cm
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Proposal Seminar Source: Rydin, E. 2000. Potentially mobile P in Lake Erken sediments. Water Res. 34:2037-2042. Lake Erken, Sweden
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Proposal Seminar Depth (or time) Concentration soil water Typical sediment nutrient profile
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Proposal Seminar Peat Soil Phosphorus: Predominately Organic Blue Cypress Marsh 400 600 800 TPo (mg kg -1 ) 4006008001000 TP (mg kg -1 ) NE NW SW TP o = 0.89*TP -49 1,000
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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
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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
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Proposal Seminar Study Locations Blue Cypress Marsh Conservation Area (BCMCA) Water Conservation Area 2A (WCA2A)
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Proposal Seminar Study Location: Blue Cypress Marsh Conservation Area Size = 120 km 2 Histosols, 1 - > 5 m Sawgrass, maidencane, slough Soft water, pH 6.5 ImpactedPristine
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Proposal Seminar Study Location: Water Conservation Area 2A Size = 447 km 2 Histosols, 1 - 2 m Sawgrass, slough, tree islands Calcareous ImpactedPristine
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Proposal Seminar Experimental Methods Soil 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
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Proposal Seminar Preliminary Results: Organic Phosphorus Characterization
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Proposal Seminar 0400800 -160 -140 -120 -100 -80 -60 -40 -20 0 BCMCA (B4) WCA2A (E5) Depth Distribution of Total Phosphorus TP, mg/kg
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Proposal Seminar BCMCA 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)
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Proposal Seminar 04080 -140 -120 -100 -80 -60 -40 -20 0 BCMCA WCA2A HEP, % of TP 04080 Depth, cm ImpactedUnimpacted Autoclave extraction [ HEP = Hot water extractable P]
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Proposal Seminar 0 20 40 60 80 100 160200260300360550 0-10 cm 160200260300360550 Temperature, C 40-50 cm 160200260300360550 90-100 cm) % of TP Thermal P Extraction BCMCA
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Proposal Seminar C:N Depth, cm 010203040 -140 -120 -100 -80 -60 -40 -20 0 BCMCA WCA2A Everglades & Blue Cypress Marsh Carbon : Nitrogen Ratio
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Proposal Seminar C:P Depth, cm Everglades & Blue Cypress Marsh Carbon : Phosphorus Ratio 040008000 -140 -120 -100 -80 -60 -40 -20 0 WCA2A BCMCA
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Proposal Seminar Preliminary Conclusions BCMCA historically higher nutrient status marsh. Thermal techniques indicate increasing O-P stability.
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Proposal Seminar Experimental Methods Characterize SOM (BCMCA) Experiment I OM fluorescence Experiment II E4:E6 Experiment III Isotope analysis: 13 C, 15 N, 14 C (ecosystem history, transformation rates) Experiment IV 13 C-NMR (broad classes of SOM) Experiment V Lignin, cellulose, hemicellulose
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Proposal Seminar Preliminary Results: OM Characterization
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Proposal Seminar Experiment I: Humification Index
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Proposal Seminar E4:E6 024681014 -140 -120 -100 -80 -60 -40 -20 0 B4 C1 +humic +MW +fulvic Experiment II: E4 E6 Ratio
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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.
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Proposal Seminar Model: SOP Diagenesis Depth SOP Recalcitrance Humic character Time
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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)
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Proposal Seminar Wet soil 1M HCL 3 hrs 0.5M NaOH 16 hrs Separate into fulvic and humic fractions Wet soil residue 0.5M NaHCO 3 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.
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Proposal Seminar 0 100 200 300 400 500 250350450550650 Fluorescence Intensity Wavelength, nm Example: Fluorescence Humification Index (HIX) = 435 480 300-345 Increased absorbance: red-shift
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Proposal Seminar Pyrolysis Extraction Inert atmosphere 160, 200, 260, 300, 360, 550 o C Batch loaded 1 hour combustion Extract w/ 1M HCl
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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 Extract Absorb. 445 & 465 Ratio is related to molecular weight
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