PHOSPHORUS MANAGEMENT IN THE OKEECHOBEE BASIN: Legacy Phosphorus Implications to Restoration and Management

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1 PHOSPHORUS MANAGEMENT IN THE OKEECHOBEE BASIN: Legacy Phosphorus Implications to Restoration and Management June 2, 2010 K. R. Reddy, M. Clark, J. Mitchell, E. Dunne A. Cheesman, and Y. Wang University of Florida-IFAS

2 Phosphorus Load, metric tons year Phosphorus Loads to Lake Okeechobee 28-year average = 500 mt P year -1 [ ] WY-Load 5-year average TMDL 140 mt P year Source: SFWMD, 2010

3 Phosphorus Memory Water Column Phosphorus External Load Reduction Internal Memory Lag time for Recovery Time - Years Background Level WBL 3

4 Phosphorus Forms Surface Soils: 0-10 cm Reactive Phosphorus Inorganic P extracted with acid/alkali Organic P extracted with alkali % of Total P 65% Non-reactive Phosphorus Total P Reactive P 35% Reddy et al., 2010 WBL 4

5 Non-Reactive Phosphorus Surface soils: 0-10 cm Non-reactive Phosphorus (mg kg -1 ) y = 0.35 x + 30 R 2 = 0.76, n = Total Phosphorus (mg kg -1 ) Reddy et al., 2010 WBL 5

6 Phosphorus Transfer Phosphorus Surface Runoff Soil Surface Subsurface transport Spodic horizon Long-Term Storage Short-Term Storage

Phosphorus 10% of Reactive P 11,000 mt P 25% of Reactive P 28,000

7 65% LOB Surface Soils 170,000 mt P Reactive P 110,500 mt P 35% Non-reactive P 59,440 mt P Lake Okeechobee Basin [LOB] Legacy Phosphorus 10% of Reactive P 11,000 mt P 25% of Reactive P 28,000 mt P P release 500 mt P year years 56 years Lake Okeechobee WBL 7

8 Lake Okeechobee Mud sediment 40% lake bottom 1035 mg kg -1 P (0-10cm) 21,390 mt P (0-10cm) Contribute 112 mt P yr -1 Internal Loads = External WBL 8

9 Lake Okeechobee Sediments Legacy Phosphorus External Load mt P year -1 Lake Okeechobee 12 years 31 years Internal Load 112 mt P year -1 10% of Reactive P mt P Reactive P 13,900 mt P 25% of Reactive P 3,475 mt P Non-reactive P 7,490 mt P 65% 35% MUD zone sediments Lake Okeechobee 21,390 mt P WBL 9

10 Long-term Strategies to Control Phosphorus Loads Hydrologic manipulation to increase P retention Establish Phosphorus Retention Areas (PRAs) In-situ remediation using various chemical and biological technologies micro watershed approach Strategic placement of managed STAs Research and monitoring to evaluate effectiveness WBL 10

11 Isolated Wetlands - LOB Upland (U) Edge (E) [Shallow Marsh] Center (C) [Deep Marsh] Larson East Larson West WBL 11

12 Larson East U2 U3 E4 E5 C4 C5 E3 U4 C3 C2 C1 E2 U5 U1 E1 WBL 12

13 Biogeochemical Indicators Inorganic phosphorus forms Phosphorus sorption parameters Partition coefficients EPC 0 Phosphorus saturation Organic phosphorus forms Microbial biomass P NMR-spectra-organic P forms Phosphorus and carbon storage WBL 13

14 Soil Phosphorus Extraction Methods Water extractable Mehlich-1 Mehlich 3 Ammonium oxalate extractable HCl- extractable NaOH - extractable Total WBL 14

15 Soil Phosphorus Forms - Center March % 9% 28% 7% 0% 0% October % 4%0% 6% 7% June % 6% 0%4% 21% Labile Pi Fe, Al bound Pi Mg, Ca bound Pi Labile Po 48% 22% 47% 12% Microbial biomass P Organic P 54% Residue P 39% 0% 5% 9% 46% 5% 2% 1% 12% 15% 31% c 6% 1% 1% 15% 15% 28% 6% 4% 1% 11% 12% 47% 19% 31% 38% March 2007 Dec 2008 Aug 2009 Jan 2010

16 Phosphorus Sequestration in Wetland Soils Solution 31 P NMR Cheesman et al WBL 16

17 Phosphorus pools: NMR spectra Larson Wetland Upland 10 0 Chemical Shift (ppm) -10 Edge = Shallow marsh 10 0 Chemical Shift (ppm) -10 Inorganic P Monoesters Diesters Pyrophosphate 10 0 Chemical Shift (ppm) -10 Center = Deep marsh

18 Phosphorus pools: NMR spectra Beaty Wetland Chemical shift (ppm) Upland Edge = Shallow marsh Inorganic P Monoesters DNA Chemical shift (ppm) Pyrophosphate Center = Deep marsh Chemical shift (ppm)

19 Isolated Wetlands

21 Macro-elements 6 C 12 7 N P 31 8 O S 32 WBL 21

22 Coupled Biogeochemical Cycles Plant Community Nutrient/ Sediment Loading Hydroperiod Organic Matter Carbon (Carbon (productivity) Cycle) Sulfur Cycle Cycle Nitrogen Cycle cycle Phosphorus Phosphorus Cycle Cycle Stable Organic Matter (Accretion/Stability) (P WBL 22

23 LOB: Isolated Wetlands- Exclosures West Wetland East Wetland WBL 23

24 LOB: Isolated Wetlands δ 13 C δ 15 N δ 15 N δ 13 C Live Standing Dead Litter Soil Upland Center WBL 24

25 Isolated Wetlands- Proposed Research and Monitoring Determine P storage in various components of wetlands Determine the influence of carbon and nitrogen cycling on P reactivity and mobility Determine stability of organic P and non-reactive P under range of redox conditions Determine the stable isotopic composition of various components of wetlands Develop parameters and rate coefficients needed for modeling efforts WBL 25

Phosphorus Biogeochemistry of the Everglades: Implications to Restoration

Phosphorus Biogeochemistry of the Everglades: Implications to Restoration K. R. Reddy, S. Newman, L. J. Scinto, J. R. White, and M. S. Koch University of Florida South Florida Water Management District