FATE OF PESTICIDES 際際滷share.pptx
- 1. FATE OF PESTICIDE IN THE ENVIRONMENT AND ENVIRONMENTAL CONCERNS
- 2. INTRODUCTION There is increased used of pesticide to enhance production. They are not only harmful to target organisms, but also non target organisms. Spread of contamination can be during transporting, manufacturing and accumulation of degraded by products in the environment. Recurrent application of pesticides accumulates its concentration in water, soil and food chain.
- 3. Transfer processes Adsorption Volatization Spray drift Run off Leaching Absorption
- 4. Adsorption It is binding of the pesticide to soil particle. Amount of pesticide adsorbed varies with pH, type of pesticide, soil moisture and soil texture. Pesticides are strongly adsorbed to soil that are high in clay and organic matter. They are not strongly adsorbed to sandy soils.
- 5. Volatization Its the process of liquid or solid converting into gases , which an move from initial point of application. Hot, dry and windy weather and small spray droplets increases Volatization. Drenching pesticides into the soil can help reduce volatization.
- 6. Spray drift Its the airborne movement of spray droplets from treatment site during application. Spray drift is affected by: Droplet size the smaller, more likely to drift Wind speed the stronger, more likely to drift Distance between nozzle and target plants Drift is harmful to people, animals and beneficial insects
- 7. Run off Its movement of pesticide in water over a sloping surface. Pesticide are either mixed with water or bound to eroded soil. Run off occurs when water is added to a field faster than it can be absorbed into the soil. Run off from areas that have been sprayed with chemicals can contaminate rivers, lakes and ponds. Contaminated water can affect human, cattle and crops downstream If heavy rains are expected, delay spraying to avoid run off.
- 8. Leaching It is the movement of pesticides in water through the soil. Leaching can occur downwards or sidewards. This leads to contamination of groundwater.
- 9. Absorption This is the uptake of pesticides by plants or microorganisms. They may be broken down or remain in the plants or animals. The chemical residues may get back to the soil after the animal or plant dies and decays.
- 10. PESTICIDES ENVIRONMENTAL CONCERNS INTRODUCTION Pesticide use in agriculture has lead to increased productivity. However, there has been increased pesticides residues in our food and in our environment leading to negative effects on human health and environment.
- 11. Effects of pesticides in the environment Effects on human health It can been categorized as: Acute - those with quick side effects Chronic those with long term felt effects Health effect on people with direct exposure Health effect on people with indirect exposure Health effects on consumers.
- 12. Health effect on people with direct exposure Cancers high risk among farm workers than general population Depression since they affect neurology of person Diabetes linked to exposure to organochlorine/ organophosphates Respiratory disorder e.g. asthma Compromised immunity Birth defects
- 13. Health effects on people with indirect exposure They can be exposed through: exposure to dust / soil contaminated clothing that is contaminated toys for kids that are contaminated Effects can be felt in workers homes or among people living near the area that is frequently sprayed. All health effects among those with direct contact are same for this group.
- 14. Health effects on consumers When PHI is not adhered to, chemical residues remain in the product. This has potential to cause harm They bring about: i. Cancers ii. General health complications iii. Compromised immunity
- 15. Effects of pesticides on Organisms i) Target organisms Leads to resistance due to mutations in target organisms Resurgence - increase in pest after spray ii) non target organisms Reduction of natural enemies e.g. bees, earthworms
- 16. Effects on water, soil and air ecosystem Alter soil microbial diversity Disturbs soil enzymatic activity Pesticide has a direct effect of death of fish Cause bird mortality Causes of death of birds through chemical: Direct ingestion of pesticide granules and treated seeds Sprayed plants Direct exposure to spray Contaminated water and prey
- 17. BIOREMEDIATION Bio means life mediate means solve problem It is the use of living organisms to promote breakdown of environmental pollutants. Other names are biotreatment, bioreclaimation and biorestoration Microorganisms that are used in bioremediation process are called bioremediators.
- 18. Types of bioremediation i. In situ Done at the site Treatment of contaminated material in place Only certain types of soil can be used Difficult to achieve complete degradation Types of in situ bioremediation intrinsic uses microorganisms that are already present in environment accelerated bioremediation- substrate or nutrients are added to environment to help process happen faster
- 19. Types of bioremediation ii) Ex situ Done away from site Involves removal of material for treatment process Use bioreactors for degradation Methods Land farming- contaminated soil is excavated and spread over bed. It is periodically tilled until pollutants are degraded Composting- mixing contaminated soil with organic material that is rich microbes
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