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Dry deposition and spray drift of pesticides to nearby water bodies
Table of Contents
Preface
Sammenfatning og konklusioner
Summary and conclusions
1 Introduction
2 Modelling dry deposition of to water bodies
2.1 Introduction
2.2 Emission
2.3 Atmospheric diffusion
2.4 Exchange between the air and the surface: general principles
2.5 Exchange between the air and the surface: vegetation
2.6 Exchange between the air and the surface: water
2.6.1 Laminar boundary layer resistance for water
2.6.2 Surface resistance for water
2.7 Results for example situations
2.8 Possibilities for generalisation
2.9 Dependence on the wind speed
2.10 Effect of the upwind field length
2.11 Effect of the length of the non-spray zone
2.12 Parameter choice in the decision tool PestSurf
3 Spray drift
3.1 Spray properties
3.1.1 Equipment
3.1.2 Drop size distribution
3.1.3 Droplet velocity
3.1.4 Droplet movement
3.1.5 Boom height
3.1.6 Air-assistance, shielding etc.
3.1.7 Factors influencing drop generation
3.1.8 Atomiser systems currently used in Denmark
3.1.9 Recommendations for research/development
3.1.10 Review of spray drift experiments
3.2 Application technique
3.2.1 Droplet size
3.2.2 Boom height
3.2.3 Drift reducing equipment
3.2.4 Driving speed
3.3 Climatic factors
3.3.1 Wind speed
3.3.2 Humidity and temperature
3.3.3 Spray-free zone
3.3.4 Potential drift reduction exploiting technical possibilities
4 Modelling spray drift
4.1 Introduction
4.2 Size distribution and speed
4.3 Entrainment flow
4.4 Terminal velocity of water drops
4.5 Drop evaporation
4.6 Wind speed above and in crops
4.7 Position and velocity of the drops
4.8 Effect of turbulence
4.9 Empirical model for spray drift
5 Discussion and conclusions
5.1 General comparison dry deposition and spray drift
5.2 Comparison for pesticides that are used in Denmark
References
Appendix A. Calculation of the fraction of the pesticide in the gas phase in the soil
Deriviation of the equation for the fraction in the gas phase
Derivation of Kd from Kom , Koc or Kow
Derivation of KH from molecular weight, vapour pressure and solubility
Temperature dependence of the vapour pressure
Temperature dependence of the solubility
Temperature dependence of the Henry’s law coefficient
References
Appendix B. Viscosity of air and water and estimation of diffusivity of pesticides in air and water
Diffusivity of gaseous pesticides in air
Diffusivity of pesticides in water
Dynamic viscosity and kinematic viscosity of air
Viscosity and kinematic viscosity of (sea)water
References
Appendix C. Derivation of the basic equation for the surface resistance of water
References
Appendix D. Experimental values of aqueous phase mass transfer coefficients
Rockland Lake
Lake 302 N
Pyramid Lake
Crowley Lake
Mono Lake
Siblyback Lake
Dozmary Pool
Relations between u(10) and k(600) for sea areas
Estuaries
Wind tank
References
Appendix E. Example model runs
References
Appendix F. Parameters necessary to calculate the drop temperature and the ventilation coefficient for water vapour
Latent heat of evaporation of water
Diffusivity of water vapour in air
Thermal conductivity of air
Saturation pressure of water vapour
References
Appendix G. Documentation of PESTDEP
Emission
Emission from crops
Emission from normal moist fallow soil
Dry deposition
Atmospheric diffusion
Integration of processes in the PESTDEP model
Example of an input file.
References
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