1. CHARACTERIZATION OF SORPTION AND DEGRADATION OF ORGANIC PESTICIDES APPLIED TO CARBONATIC SOILS Gabriel Nuffield Kasozi Source: usda.gov

2. Outline Introduction Hypothesis Objective of the study Materials and Methods Preliminary results

3. Introduction Carbonatic soils are composed of more than 40% Carbonates Carbonatic soils are composed of more than 40% Carbonates Over 500 carbonatic soils in USA and 12 are in South Florida Over 500 carbonatic soils in USA and 12 are in South Florida 85% of Florida vegetables and Tropical fruits grown on Carbonatic soils 85% of Florida vegetables and Tropical fruits grown on Carbonatic soils Source: BMP project report, 2002

4. Pesticide use Estimated Annual Total Pesticides Use in SFWMD 14,590 tons. Pesticides Detected in Water Resources in South FL and PR PesticideChemical classWhere detected AtrazineS-triazineGround, surface water (FL; PR) 1,2,4 AmetryneS-triazineGround, surface water (FL; PR) 3,4 DiuronSubstituted ureaSurface water (FL) 1 EndosulfanOrganochlorineSurface water (FL) EnthropropOrganophosphateSurface, ground water (PR) 3 DiazinonorganophosphateSurface, ground water (PR) 3 LindaneorganochlorineSurface, ground water (PR) 3 1 Miles and Pfeuffer (1997); 2 Potter et al., (2002); 3 Dumas and Rosario (2003); 4 Conde- Costas and Rodriguez (1997); FL= Florida; PR = Puerto Rico

5. Dade Hydrogeologic Cross-section

6. Introduction Sorption and degradation determine the fate of an applied organic pesticide Source: SFWMD

7. Hypothesis Organic pesticides are adsorbed less on carbonatic soils as compared to non-carbonatic soils The nature of soil organic matter affects the degree of pesticide sorption Pesticides degrade faster in Carbonatic soils than in non-carbonatic soils

8. Objective of the study Characterize and compare chemical and physical properties of carbonatic soils with those of associated non-carbonatic soils and soils from other areas Characterize sorption and degradation of selected pesticides and create a database for sorption and transformation of these pesticides on carbonatic soils

9. Objective of the study Characterize organic matter (formation, composition and functionality) Identify the dominant component controlling sorption of pesticides

10. Materials and Methods Soils Soils Soil samples will be taken from South Florida, Puerto Rico and Uganda Biscayne, Perrine, Pennsuco, Chekika, Krome, Lauderhill, Tamiami Proposed Pesticides Proposed Pesticides Atrazine, Ametryne, Oxamyl, Diuron, Endosulfan, Lindane, Carbaryl, Enthroprop, Diazinon

11. Materials Experiment 1 Experiment 1 Characterization of soil physical and chemical properties pH, TOC, CEC, Clay Minerals, CaCO 3 Determination of organic carbon Walkley-Black method Thermogravimetry Sorption isotherms determination (Batch slurry method)

12. Methods Experiment 2 Experiment 2 Characterization of organic matter Stable isotope δ 13 C, δ 15 N, and C/N ratios n-Alkanes by GC-FID Liquid and Solid state 13 C and 1 H NMR Pyrolysis GC-MS

13. Materials and Methods Experiment 3 Characterization of the nature of binding existing between OM and pesticides 13 C NMR NanoESI-GC-MS Flow Calorimetry

14. Materials and Methods Experiment 4 Characterization of degradation of pesticides in carbonatic soils Solvent extractable disappearance of the parent pesticide Degradation rate coefficients and half- life (t 1/2 ) will be determined

15. Materials and Methods Data Analysis Sorption data will be fit using the Freundlich model Degradation data will be fit using first order kinetics

16. Preliminary Results Table of results ε = Walkley and Black ; Π = Thermogravimetry Soil% CaCO 3 Π % OC ε % OM Π Biscayne805.829.82 Perrine872.794.75 Pennsuco-2.37- Krome671.453.45 Chekika871.93.94 LauderHill-35.78- Tamiami-36.25- Matecumbe-28.13-

17. Preliminary Results Comparison of TG with Walkley-Black for OC determination Literature Conversion factor: 1.724

18. Preliminary Results Table of results Soil solution ratio: 1:2 SoilpH (KCl) (1 M) pH (H 2 O) Biscayne7.668.11 Perrine7.788.00 Krome7.598.51 Chekika7.728.29 Lauderhill6.987.39

19. Preliminary Results Linear Sorption Isotherm for Biscayne

20. Preliminary Results Linear Sorption Isotherm for Krome

21. Preliminary Results Sorption coefficients of Diuron Soil seriesSorption coefficient K D K oc Biscayne5.84101 Perrine2.692 Chekika2.6136 Krome3.11222 Lauderhill139.49390 Iowa11.09240 † Literature400 † † (Wauchope et al., 1992, and Nkedi-Kizza et al., 1985)

22. Preliminary Results Sorption coefficients of Atrazine Soil seriesSorption ceofficient K D K oc Biscayne 2.16 37 Perrine0.7129 Chekika0.7640 Krome0.82 57 Lauderhill45.20101 Iowa4.0688 † Literature100 † † (Wauchope et al., 1992, and Nkedi-Kizza et al., 1985)

23. Advisory Committee: Dr. Peter Nkedi-Kizza Dr. Yucong Li Dr. David Hodell Dr. David Powell Dr. Willie Harris