Phosphorus Biogeochemistry of the Everglades: Implications to Restoration

Transcription

1 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 Florida International University Louisiana State University Florida Atlantic University Greater Everglades Ecosytem Restoration Conference July 28-August 1, 2008, Naples, Florida

2 Phosphorus Cycling Processes Topic Outline Introduction Forms of phosphorus Abiotic processes Biotic processes Ecosystem phosphorus memory Implications to restoration Water Column Soil 8/19/2008 2

3 Phosphorus Gradients Phosphorus Limited Wetlands Fast Slow Phosphorus Enriched Wetlands C:N:P Ratios [High] Low Organic Matter Accumulation Slow turnover rates Longer residence time High nutrient use efficiency C:N:P Ratios [Low] High Organic Matter Accumulation High turnover rates Shorter residence time Low nutrient efficiency

4 HLRB EAA WCA-3A WCA-1 WCA-2A Phosphorus Gradients High WCA-3A BCNP WCA-3B ENP Low

5 Phosphorus Gradients WCA-2a Total Phosphorus (mg kg -1 ) Depth (cm) [O] [T] [E] [E] = Eutrophic Site I (1.9km) [T] = Transition/eutrohphic Site II (3.5 km) 25 [O] = Oligotrphic Site (8.3km) 30

6 Phosphorus Cycle Runoff, Atmospheric Deposition Plant biomass P Litterfall Outflow DIP POP DOP DIP Periphyton P PIP AEROBIC DIP DOP POP Peat accretion DOP DIP Adsorbed IP [Fe, Al or Ca-bound P] PIP ANAEROBIC

7 Inorganic Phosphorus- Organic Soils Total Inorganic P (mg kg -1 ) 3,000 1, Y = 0.01X 1.54 R 2 =0.897; n=390 WCA1 WCA2 WCA3 HWMA EAA ,000 2,000 5,000 Total Phosphorus (mg kg -1 ) 8/19/2008 WBL 7

8 Soil Cores - WCAs Benthic periphyton Floc Calcareous soil Soil Soil S. Newman, SFWMD)

9 Organic Wetland Soils Drainage Effects KCl-Pi (available) 23% <0.1% 1% 4% 72% Fe- and Al-bound P Alkali extractable organic P Ca- and Mg-bound P Residual P Peat Depth < 10 cm Total P = 836 mg P/kg 47% 1% 7% 24% Peat Depth > 30 cm Total P = 411 mg P/kg 21% 8/19/2008 WBL 9

10 Organic Wetland Soils Fire Effects Labile P Fe- & Al-bound P Ca-&Mg-bound P Pre Surface Burn Organic P Post Surface Burn Pre Peat Burn Post Peat Burn Smith et al., 2001

11 Inorganic Phosphorus Retention S max Water P w Adsorption slope = KD Soil P ad Solid phase P s P ret Porewater Desorption S o EPC o Phosphorus in Soil Porewater P adsorbed P solution EPC 0 = Equlibrium P concentration at which point adsorption equals desorption

12 Inorganic Phosphorus Retention-WCA-2A 2.0 EPCo (mg P L -1 ) Anaerobic Aerobic Distance from inflow (km) EPC 0 = Equlibrium P concentration at which point adsorption equals desorption Solid phase P adsorbed Porewater P solution

13 Phosphorus Cycle Runoff, Atmospheric Deposition Plant biomass P Litterfall Outflow DIP POP DOP DIP Periphyton P PIP AEROBIC DIP DOP POP Peat accretion DOP DIP Adsorbed IP [Fe, Al or Ca-bound P] PIP ANAEROBIC

14 Phosphorus Loading Biotic Processes PLANTS WATER DETRITUS N C Labile DETRITUS NC P P Microbial Biomass Microbial Biomass SOIL P N P N

15 Short-term P partitioning: 32 P 18 days Floc 35% Soil 27% Metaphyton 12% Water 10% Utricularia spp. 7% Consumer 3% Macrophyte dead 3% Epiphyton dead 3% Roots 1% Other macrophytes 1% Epiphyton live <1% (Noe et al. Freshwater Biology 2003)

16 Organic Phosphorus Plants Animals Microbes Detrital Matter Phytin Phospholipids Nucleic acids Sugar phosphates Humus Inorganic Phosphate

17 Organic Phosphorus WCA-2A [ 31 P NMR spectrascopy] Enriched (Typha) Unenriched (Cladium) monoesters DNA monoesters DNA Floc monoesters DNA monoesters DNA Soil Chemical shift (ppm) Turner et al., 2006

18 Organic Phosphorus Isolated Wetlands- Okeechobee Basin µg P cm Polyphosphate Orthophosphate Phosphomonoesters DNA Phospholipids Pyrophosphate Pasture upland Shallow marsh Deep marsh Cheesman et al., 2008

19 p-nitrophenol (mg g -1 hr -1 ) Alkaline Phosphatase Activity Everglades- WCA-2A Litter 0-10 cm cm Distance from inflow (km) Wright and Reddy, /19/2008 WBL 19

20 500 Phosphatase Activity Periphyton APA along the WCA 2a Nutrient Gradient July 1996 [Newman, S] Distance from the S10s (km) 8/19/2008 WBL 20 Source: Newman, unpubl d data

21 Biotic and Abiotic Interactions Epiphytic Benthic Soluble P Floating Ca-P Water Soil Soluble P Ca-P

22 32 P Partitioning- Periphyton Abiotic Biotic Water 5% 2% 74% 88% 10% 22% Water DRP: 5 ug l -1 Light : 10 W m -2 1 hr 12 hr (Scinto and Reddy, Aquatic Botany, 2003)

23 Periphyton-Phosphorus- CaCO 3 Interactions P P P P P Periphyton P Solution P CaCO 3 (Scinto and Reddy, Aquatic Botany, 2003)

24 Phosphorus and Calcium Accumulation-WCA-2a R 2 = Phosphorus accumulation (g m- 2 yr -1 ) Calcium accumulation (g m -2 yr -1 )

25 Sulfur-Calcium -Phosphorus Interactions under Aerobic Soil Floodwater Conditions O 2 Aerobic soil Ca + P H + + SO 4 2- H 2 S + O 2 Ca - P Anaerobic soil SO 4 2- H 2 S

26 Sulfur-Iron -Phosphorus Interactions under Anaerobic Soil Conditions Inputs Water FeRB Soil FeS Fe 2+ + PO 4 3- FePO 4 [Strengite] Fe(OH) 2 -PO 4 SO 4 2- H 2 S + FePO 4 SRB [Strengite] Fe 3 (PO 4 ) 2 [Vivianite]

27 Phosphorus Memory in the Everglades Legacy phosphorus in various ecosystem components (uplands, wetlands, and aquatic systems) Transient pools Stable pools Capacity for showing effects as a result of past practices Length of time over which phosphorus release extends before returning to a stable condition Water Column P Detritus P Soil

28 Legacy Phosphorus 1998

29 Phosphorus Accretion-WCA-2A 1.2 Phosphorus Accretion (g m -2 y -1 ) Distance from inflow (km)

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

31 P flux (mg P m -2 day -1 ) Phosphorus Memory - Everglades -WCA-2A Distance from inflow (km) Fisher and Reddy, 2001

32 Ecological Significance Detritus Production Biomass Production Release of Plant Available N Feedback Mechanism Microbial Biomass Legacy Phosphorus White, 1999

33 Research Needs Identification of inorganic and organic P compounds Stability of legacy P under range of hydrologic/redox conditions Multiple roles of microbial and plant mediated processes on P retention and release Develop methods to reduce P memory effects to enhance the recovery Linkage between P biogeochemistry and other elemental cycles Forecast models based on mechanistic understanding of biogeochemical processes

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