Presentation on theme: "Proposal Seminar Biogeochemical Controls Regulating Long-term Burial of Phosphorus in Wetland Soils M. M. Fisher Dissertation Proposal November 5, 2004."— Presentation transcript:
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 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
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 Sediment Depth, cm
Proposal Seminar Source: Rydin, E. 2000. Potentially mobile P in Lake Erken sediments. Water Res. 34:2037-2042. Lake Erken, Sweden
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
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 Locations Blue Cypress Marsh Conservation Area (BCMCA) Water Conservation Area 2A (WCA2A)
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
Proposal Seminar Study Location: Water Conservation Area 2A Size = 447 km 2 Histosols, 1 - 2 m Sawgrass, slough, tree islands Calcareous ImpactedPristine
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
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
Proposal Seminar Preliminary Results: OM Characterization
Proposal Seminar Experiment I: Humification Index
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 Depth SOP Recalcitrance Humic 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 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.
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