1. Nutrients as Pollutants

2. Major Determinants of Water Quality and the Impact or Availability of Water Pollutants Organisms Solubility Oxygen pH Nutrients (N, P) Metals (Hg, Pb, As) Organic Chemicals (PCBs, Dioxins)

3. Nutrients: Nitrogen and Phosphorus

4. Both are limiting to primary productivity Excess amounts can severely alter ecosystems Availability in the environment is controlled by Oxygen pH Organisms Sources: fertilizers, manures, wastewater discharge

5. Eutrophication Photosynthetic life O2O2 bacteria Nutrient Additions Nutrient addition increases primary productivity (algae) Sunlight is limited at greater depth Photoautotrophs die and become food for aerobic heterotrophs Aerobic autotrophs consume O 2 Oxygen content in water is reduced If oxygen is reduced sufficiently, aerobic microbes cannot survive, and anaerobic microbes take over

6. Nitrogen

7. NH 4 + and NO 3 - Forms are controlled by organisms NH 4 + is converted to NO 3 - by aerobic bacteria The process is called nitrification These bacteria, therefore, are controlled by oxygen levels Nitrifying bacteria do not function well at low pH. Organisms Oxygen pH

8. Dominant Forms: NH 4 + and NO 3 - NO 3 - is more mobile in the environment than NH 4 + _ _ _ _ _ __ _ _ Soil particles possess a negative electrical charge NH 4 + NO 3 - Leaching to ground Or surface water Sources: fertilizers, manures, wastewater discharge

9. Groundwater and Nitrates (NO 3 - ) Nitrates do not interact significantly with soil material and can move rapidly to groundwater. 3. Areas where the aquifer confining unit is thin are also particularly vulnerable. What areas are particularly vulnerable? 2. Areas where natural groundwater recharge occurs 1. The unconfined, surficial aquifer

10. 55 – 24 million years ago Miocene Clays (Hawthorne Formation) Sandy Materials The Floridan aquifer is a confined aquifer. The water-bearing unit is permeable limestone. Low Permeability Confining Unit (poor water movement) Unconfined aquifer is extensive throughout the state of Florida Low permeability rock (confining) Unconfined Aquifers

11. Recharge

12. Thin sandy overburden Where the Confining Layer is Thin Groundwater

13. residential and commercial septic systems in rural areas about 300 row crop and vegetable farms 44 dairies with more than 25,000 animals 150 poultry operations with more than 38 million birds Lower Suwannee River Watershed Nitrates NO 3 Drinking water standard: 10 ppm

14. Possible sources of nitrate in the ground water in the vicinity of the river include fertilizer, animal wastes from dairy and poultry operations, and septic-tank effluent. Nitrate concentrations were higher in the measured springs than in the river. Flow Groundwater Nitrate Discharge to Rivers

15. Environmental and Health Hazard Methemoglobinemia Nitrate is converted to nitrite in infants (pH, organisms) Nitrite converts iron in the hemoglobin of red blood cells to form methemoglobin which cannot bind oxygen Adults possess an enzyme that reverses the conversion Infants possess 60% less of the enzyme

16. Phosphorus

17. Phosphorus Limiting Element to Primary Productivity Chlorophyll ATP Phospholipids ATP Additions increase Productivity Present in Fertilizers, animal wastes, wastewater

18. Fertility Only 10-15% of applied fertilizer phosphorous is used by plants The rest is bound to soil particles or forms insoluble solids Most phosphorus is unavailable to plants This leads to excess application

19. Plant Availablity and pH H 2 PO 4 - HPO 4 -2 pH 3-6pH 8-11 pH 6-8 Optimum pH = 6.5 for plant availability Most Available At low pH, P binds to iron and aluminum At high pH, P binds to calcium

20. Acidic Conditions (low pH)

21. Acid Conditions (Low pH) Aluminum and Iron availability is increased at low pH Al(OH) 3 FeOOH Solubility increased at low pH (Acids dissolve Metals) Al 3+ Fe 3+ Al(OH) 3 + 3H + = Al 3+ + 3H 2 O example solid In solution solids

22. Aluminum Precipitation at Low pH H 2 PO 4 - (pH 3-6) Al 3+ + H 2 PO 4 - + 2H 2 0 = Al(OH) 2 H 2 PO 4 + 2H + (solid) Al(PO 4 ) Solid Al 3+ + PO 4 -3 = Al(PO 4 ) simplified Form of available P at low pH: H 2 PO 4 - combines with free Al 3+ and Fe 3+ time Fe 3+ + PO 4 3- = FePO 4

23. Basic Conditions (High pH)

24. Calcium Binding in Basic Conditions Ca 2+ + 2H (PO 4 ) -2 = Ca [H (PO 4 )] CaHPO 4 (solid) Ca 5 (PO 4 ) 3 OH (Apatite mineral) H (PO 4 ) -2 is the available form of P at high pH Calcium is often present at high pH time

25. Binding of Phosphorus Binding of Phosphorus Low pH High pH Aluminum and Iron phosphates Calcium Phosphates Insoluble solids There is a limited ability to immobilize phosphorus If the capacity is exceeded, phosphorus becomes more mobile Mobile phosphorus can contaminate surface and groundwater

26. P-impacted Unimpacted *

27. Extra Credit: 1.Indicate one of the dominant forms of N in the environment 2.Methemoglobinemia is caused by what nutrient? 3.At low pH phosphorus binds to ______________________ 4.At high pH phosphorus binds to _____________________

28. South Florida and Phosphorus

29. Phosphorus loading to S. Florida Ecosystem Inputs North and South of Okeechobee Dairy/Beef Crop production

30. Sugar, Rice, Veg. 700,000 ac EAA Crops: Everglades Agricultural Area

31. Celery26020014080200000 Endive2001751501251007550250 Escarole 2001751501251007550250 Lettuce (Head)2001751501251007550250 Radish100400000000 Romaine2001751501251007550250 Sugar Cane120100804020000 0 Phosphorus Fertilization (lbs/ac) Low Soil P V. High Soil P Based on how much P is already in soils

32. Phosphorus loading to S. Florida Ecosystem Agriculture Overstimulation of primary productivity

33. Dairy and Beef

34. Kissimmee drainage basin 12,000 km 2 In 1521 Ponce de Leon brought horses and cattle to Florida. No other part of our country had cattle until the Pilgrims brought cattle in the early 1600's Florida's ranchers now raise the third largest number of cattle of any state east of the Mississippi (1947)

35. Phosphorus Solid Manure: 5.5 g / kg total Phosphorus One cow can excrete between 40 and 60 g of phosphorus per day Subject to movement via runoff, stream flow, soil water movement, and groundwater movement

36. Cattle and Dairy Okeechobee, Highlands, and Glades Counties: 328,000 head (19% of total) Okeechobee County is ranked number one for all cattle in the state

37. The Kissimmee river alone contributes about 20% of the phosphorus flowing into Lake Okeechobee The Lower Kissimmee River Basin is among largest sources of external phosphorus loading to Lake Okeechobee Kissimmee – Okeechobee - Everglades Okeechobee, in turn, is a source of phosphorus to the Everglades urban

38. Surface Water Improvement Management Act: SWIM SWIM Plan priority basins Mandated phosphorus load level of 397 tons/yr Clean Water act: 154.3 tons per year DEP: 140 tons per year Lake (1987) Target level of 40 ppb in Lake Okeechobee urban

39. The Dairy Rule (1987) creating lagoons to capture and contain dairy waste Dairy Buy-Out Program to facilitate removal of animals from dairies not able to comply Works of the District Rule permits are required for all discharges into waterways Implement Best Management Practices (BMPs) buffer areas around places animals congregate, eliminating phosphorus fertilization near tributaries to the lake, reducing phosphorus imports in animal feeds, reducing animal density Some Strategies 19 of 45 Dairies Remain

40. Phosphorus concentrations in the Lake remain at about 117 ppb 2007: 146 ton reduction of P entering Okeechobee The target level is 40 ppb. From a baseline of 433 tons/yr

41. Internal Loading Decomposition of submerged aquatic vegetation releasing phosphorus back into the water column Dissolution of Iron and Aluminum compounds in sediments which bind and store phosphorus. Two Sources

42. Phosphorus and Iron Phosphorus has a strong affinity for iron FePO 4 Solid Precipitate Readily incorporates into bottom sediments Internal Loading

43. Fe 3+ high oxygen Fe 2+ low oxygen Iron Exists in Two Different Forms Depending on Oxygen Content Forms insoluble solids with Phosphate Phosphorus compounds become soluble Fe 3+ + PO 4 3- = FePO 4 solid

44. Internal Loading Dissolved phosphorus combines with oxidized iron (Fe 3+ ) to create an insoluble compound that becomes buried in lake sediments. If oxygen contents are reduced (anoxic bottom sediments) the Fe 3+ converts to Fe 2+ which solubilizes the compound returning P to water. P released by sediments is taken up by photosynthetic algae faster than it can be returned to the sediments Fe 3+ + PO 4 3- = Fe(PO 4 ) solid (PO 4 )Fe to water 2+ Fe 3+ high oxygen Fe 2+ low oxygen 3- Simplified:

45. RECOMMENDATION – Control Internal Phosphorus Loading. Phosphorus-rich mud sediments need to be removed from the lake to the maximum extent that is practical, in order to reduce internal phosphorus loading. Unless this internal loading is substantially reduced, it may take as long as 100 years for the lake to respond to watershed phosphorus control programs. Lake Okeechobee Action Plan Developed by the Lake Okeechobee Issue Team December 6, 1999

46. Next: Arsenic, Fluoride, Mercury