Fate of Pesticides in the Environment . MINA NEJADAMIN BIOM 430 Spring’ 11. Overview. Xenobiotics Pesticides Fate of pesticides in the environment Aerobic & Anaerobic Biodegradation Pesticides as water pollutants Human health effects of pesticides Ecological effects of pesticides
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Fate of Pesticides in the Environment MINA NEJADAMIN BIOM 430 Spring’ 11
Overview • Xenobiotics • Pesticides • Fate of pesticides in the environment • Aerobic & Anaerobic Biodegradation • Pesticides as water pollutants • Human health effects of pesticides • Ecological effects of pesticides • Pesticide monitoring in surface water • Pesticide management and control
Xenobiotics • stranger to life by its dictionary meaning • a chemical that is not produced and found in significant concentrations also does not exist long terms in organisms by its scientific meaning • Exist in different forms: • Certain fertilizers and agrochemicals • Environmental contaminants, such as industrial and domestic wastes and effluents • By-products of biological processes, such as fermentation, distillation and animal production
Xenobiotics • pesticides, Polychlorinated biphenyls (PCBs), dyes, and chlorinated solvents • Structurally related, to natural compounds • Suspected of being carcinogenic • Used as industrial solvents, degreasing agents, and insulators in electrical transformers
The production rates & major uses of Xenobiotics Most widely distributed xenobiotics are pesticides.
Pesticides • any substance intended to control, destroy, or attract a pest • Algicide -- algae • Fungicide -- fungi • Herbicide -- weeds • Insecticide -- insects • Miticide --mites • Rodenticide – rodents
Fate of pesticides in the environment • Adsorption • Transfer • Degradation • Microbial degradation • Chemical degradation • Photodegradation
Fate of pesticides in the environment • Adsorption: the adverse attraction between soil particles and chemicals • Effecting factors: organic matter and clay levels in soil, particle surface area, available sites for binding of pesticides, and moisture • Transfer: Volatilization, runoff and leaching are the most widely used types • Effecting factors: temperature, humidity, air movement, and vapor pressure
Fate of pesticides in the environment • Degradation: breakdown of pesticides • Microbial degradation • Chemical degradation • Photodegradation • Microbial Degradation: occurs when microorganisms such as, fungi and bacteria use pesticides as a food source • occur rapidly and under the optimum soil conditions that maximize the microbial growth • affected from the pesticides, the frequency of pesticides influence the rapidity
Fate of pesticides in the environment • Chemical degradation: the breakdown of pesticides with chemical reactions in the soil, living organisms do not involve to the process • the rapidity of the reactions are influenced by temperature, moisture, pH, adsorption, chemical and physical properties of the both pesticide and soil • hydrolysis, the pesticide reacts with water during the process
Fate of pesticides in the environment • Photodegradation: the degradation by using sunlight • The intensity and spectrum of sunlight • length of exposure • the properties of the pesticide • the application site • Pesticides applied to foliage are more exposed to sunlight than pesticides that are incorporated into the soil
Aerobic & Anaerobic Biodegradation WHY ANAEROBIC BIODEGRADATION? • aerobic processes require oxygen and the oxygen delivery systems used in these processes are very expensive • in some conditions such as degradation of contaminated groundwater and PCBs only anaerobic bacteria can be used to gain more efficient processes • in most cases in order to make an aerobic degradation process, an anaerobic process is needed primarily
Pesticides as water pollutants • The impact on water quality is associated with the following factors: • Active ingredient in the pesticide formulation • Contaminants that exist as impurities in the active ingredient • Additives that are mixed with the active ingredient (wetting agents, diluents or solvents, extenders, adhesives, buffers, preservatives and emulsifiers) • Degradate that is formed during chemical, microbial or photochemical degradation of the active ingredient.
The ecological impacts of pesticides in water are determined by the following: criteria:
Human health effects of pesticides • Human health effects are caused by: • Skin contact: handling of pesticide products • Inhalation: breathing of dust or spray • Ingestion: pesticides consumed as a contaminant on/in food or in water • For the majority of the population, a principal vector is through ingestion of food that is contaminated by pesticides • Degradation of water quality by pesticide runoff has two principal human health impacts • consumption of fish and shellfish that are contaminated by pesticides • the direct consumption of pesticide-contaminated water
Ecological effects of pesticides • Bioconcentration: The movement of a chemical from the surrounding medium into an organism • Biomagnification: The increasing concentration of a chemical as food energy is transformed within the food chain • Very high concentrations can be observed in top predators, including man • The important point is that many of these effects are chronic (not lethal), are often not noticed by casual observers, yet have consequences for the entire food chain
Pesticide monitoring in surface water • Monitoring data for pesticides are generally poor in much of the world and especially in developing countries • Many developing countries have difficulty carrying out organic chemical analysis due to • problems of inadequate facilities • impure reagents • financial constraints • New techniques using immunoassay procedures for presence/absence of specific pesticides may reduce costs and increase reliability
Pesticide management and controlExamples & Experiences • The European experience • The Netherlands National Institute of Public Health and Environmental Protection concluded that "groundwater is threatened by pesticides in all European states.” • This is obvious both from the available monitoring data and calculations concerning pesticide load, soil sensitivity and leaching • It has been calculated that on 65% of all agricultural land the standard for the sum of pesticides (0.5; mg/l) will be exceeded • In recognition of pesticide abuse and of environmental and public health impacts the European countries have adopted a variety of measures that include (FAO/ECE, 1991):
Examples & Experiences • The Danish example • In 1986 the Danish Government initiated an Action Plan for sustainable agriculture which would prevent the use of pesticides for two purposes (WWF, 1992) • Safeguard human health • Protect the environment • The objective was to achieve a 50% reduction in the use of agricultural pesticides by 1997 from the average amount of pesticides used during the period 1981-85 • This was to be measured by a decline in total sales (by weight) of the active ingredients and, decrease in frequency of application
Summary • Pesticides can have a negative influence on environment especially water resources, public health and wildlife • Be aware of the possible means of the pesticide transport from the target site to an off target site • common sense, concerning handling, mixing, applying and disposing of pesticides and pesticide containers • Follow labeled directions in order to minimize risk associated with negative pesticide affects on the environment and public health
Works cited: • 1- Corbett, J. R. The Biochemical Mode of Action of Pesticides. London: Academic, 1974. Print. • 2- Goodman, B. A., Late M J. Allison, K. J. Oparka, and J. R. Hillman. "Xenobiotics: Their Activity and Mobility in Plants and Soils." Journal of the Science of Food and Agriculture 59.1 (1992): 1-20. Print. • 3- Zhang, Chunlong, and George N. Bennett. "Biodegradation of Xenobiotics by Anaerobic Bacteria." Applied Microbiology and Biotechnology 67.5 (2005): 600-18. Print. • 4- Hill, David W., and Perry L. McCarty. "Anaerobic Degradation of Selected Chlorinated Hydrocarbon Pesticides." Water Pollution Control Federation 39.8 (1967): 1259-277. Print. • 5- Barnard, C., S. Daberkow, M. Padgitt, M. Smith, and N. Uri. "Alternative Measures of Pesticide Use." Science of The Total Environment 203.3 (1997): 229-44. Print. • 6- Fishel, Fred. "Pesticides and the Environment." MU Guide 91.9: 1-6. Print. • 7- Matsumura, Fumio, and Murti C. R. Krishna. Biodegradation of Pesticides. New York: Plenum, 1982. Print. • 8- Kuhr, Ronald J., and Naoki Motoyama. Pesticides and the Future: Minimizing Chronic Exposure of Humans and the Environment. Amsterdam: IOS, 1998. Print. • 9- Menzie, C. M. "Fate of Pesticides in the Environment." Annual Review of Entomology 17.1 (1972): 199-222. Print. • 10- Arnold, D. J., and G. G. Briggs. "Fate of Pesticides in Soil: Predictive and Practical Aspects." Progress in Pesticide Biochemistry and Toxicology 7 (1990): 101-22. Print. • 11- Mogensen AS, Haagensen F, Ahring BK (2003b) Anaerobic degradation of linear alkylbenzenesulfonate. Environ ToxicolChem 22:706–711 • 12- Schink B (2002) Anaerobic digestion: concepts, limits and per- spectives. Water SciTechnol 45:1–8 • 13- Baker KH, Herson DS (1994) Bioremediation. McGraw Hill, New York, NY • 14- Master ER, Lai VW-M, Kuipers B, Cullen WR, Mohn WW (2002) Sequential anaerobic-aerobic treatment of soil contaminated with weathered Aroclor 1260. Environ SciTechnol 36:100–103 • 15- Williams PP (1977) Metabolism of synthetic organic pesticides by anaerobic microorganisms. Residue Rev 66:63–135
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