Fate of Pesticides in Environment Air, water and soil Transportation Processes Models

1. FATE OF PESTICIDE
IN ENVIRONMENT
Presented by: Arooba Nosheen

2. • Pesticides are chemical compounds
that are used to kill pests, including
insects, rodents, fungi and unwanted
plants.
Pesticide
• Life cycle of a chemical (pesticide) or
biological (enzyme) pollutant after
its release in the environmentFate

3. CLASSIFICATION
According to their intended target organism According to their intended use
• Disinfectant
• Repellent
• Sanitizer

4. FATE OF PESTICIDE IN
ENVIRONMENT
Break down Processes
• Photo Degradation
• Microbial Breakdown
• Chemical Breakdown
Transfer Processes
• Volatilization
• Run off
• Spray Drift
• Leaching
• Uptake
• Adsorption

5. UPTAKE
Uptake of pesticides and other chemicals into plants or
microorganisms
Pesticide residues may be broken down or remain inside the plant or
animal, when the animal dies or as the plant decays released back
It depends upon soil and pesticide properties and environmental
conditions

6. VOLATILIZATION
• Volatilization is the process of
conversion of solid or liquid
into gas, which can easily move
away from its initial application
site.
• Volatilization depends upon
temperature, humidity, air
movements and soil texture.

7. ADSORPTION
• The adsorption (Sticking) of pesticide occur
as a result of interaction between a chemical
and a soil particle.
• It depends upon the type of pesticide, soil
moisture, soil pH and soil texture
• Pesticides strongly adsorbed to the clay and
soil organic matter that do not readily leach
through the soil profile

8. RUN OFF
• Runoff is the movement of water over
the sloping surface that occurs when
water is applied faster than it enters
the soil
• Pesticide losses from runoff are
greatest when rains heavily right after
the spray
• The runoff of pesticide depend on
slope of the area, soil texture, moisture
and physiochemical properties of
pesticide

9. LEACHING
• Leaching refers to the movement of
pesticides through the soil rather than
over surface
• Groundwater contamination occur
through this

10. SPRAY DRIFT
• Spray drift is the airborne movement of
spray droplets away from a treatment
site during application
• It can contaminate water bodies, cause
harm to fish, aquatic plants and animals
• It depends on the droplet size, Wind
speed and the distance between the
nozzle and target plane

11. BREAK DOWN PROCESSES
Chemical
Breakdown
is the break down of pesticide by hydrolysis, oxidation-
reduction and ionization that usually happen through the
presence of acidity or alkalinity
Biological
Breakdown
is the result of microbial metabolism of pesticide, and is
often the main source of pesticide degradation
Photo
degradation
is the breakdown of pesticides by light and can occur on
foliage, on the surface of soil and in the air

12. TRANSPORT OF PESTICIDE IN THE
ENVIRONMENT

13. TRANSPORT OF PESTICIDE IN AIR
• Pesticide emission occurs from plant canopy or soil surface to the
atmosphere.
• The emission potential depends upon the ratio of emission and the usage
of pesticide.
• Dry and wet deposition of the pesticide occur

14. TRANSPORT OF PESTICIDE IN SOIL
Once the pesticide is in the soil, it will most likely follow one of the three
pathway
• Moving through the soil with water
• Attaching to soil particles
• Being metabolized by microorganisms
Soil texture and structure plays a vital role in the transport processes of
pesticide.

15. TRANSPORT OF PESTICIDE IN
WATER
• Water transport of pesticide can occur through wet deposition, run off from
surfaces, infiltration of water through the grounds and open water currents
• Water that is moving at a high velocity can better carry heavier pesticides than
water that is slowly moving.
• Pesticides in Open water system may float, diffuse or deposit on the sediments at
the bottom of waterbody
• Pesticides that move from the ground surface through the soil may reach shallow
ground waters or deeper aquifer.

16. COMPUTER SIMULATION MODELS

17. SPRAY PESTICIDE MODELS
• Spray pesticide models (Cheng, 1990) based on diffusion are available for
the design and evaluation of spray application systems to minimize aerial
drift and volatile losses as well as to elevate accurate targeting of the spray.

18. PESTICIDE RUNOFF MODELS
• Pesticide runoff models (Cheng, 1990) from the small plot to the watershed-
scales are being used to develop best-management practices.
• Initially the hydrologic processes that contribute to runoff and erosion were
determine. Then reactivity of pesticides were coupled to runoff models.
• These runoff models are more useful for evaluation of alternative
management strategies and are less useful for predictive purposes.

19. PESTICIDE LEACHING MODELS
• Conceptual screening models for pesticides typically consider solubility, sorption,
persistence, volatility, and mobility.
• Such models rank the behavior of the pesticide and its potential movement in soil.
• However, screening models are not environmental fate prediction models and are
inappropriate outside the idealized conditions that lead to their derivation.

20. PROCESS-BASED SIMULATION
MODELING
Process-based simulation modeling includes pesticide reactivity and transport
Recently, they have been extended and applied for management of larger-scale field
environments, for example,
The erosion/productivity impact calculator (EPIC) (Sharpley and Williams, 1990),
Groundwater loading effects of agricultural management systems (GLEAMS) (Leonard
et al., 1987)
Pesticide root zone model (PRZM) (Carsel et al., 1984)
Leaching estimation and chemistry model—pesticides (LEACHM-P) (Wagenet and
Hutson, 1989).

21. REFERENCES
• Gavrilescu, M. (2005). Fate of pesticides in the environment and its
bioremediation. Engineering in Life Sciences, 5(6), 497-526.
• National Research Council. (1993). Soil and water quality: an agenda for
agriculture. National Academies Press.
• Seiber, J. N. (2002). Environmental fate of pesticides (pp. 127-161). Marcel Dekker:
New York.
• http://www.who.int/topics/pesticides/en/