الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
The pesticides are like a two-edged sword, not only detrimental to the target organisms but also to the non-target organisms. They improve the quantity and quality agricultural production while have many direct and indirect impact on humans and environment. Consequently, it is impossible today stopping pesticide application but at the same time it impossible accepting using of pesticide without understanding its fate and behaviour in environment as well as its side-effects on non-target organisms, to achieve the purpose of its using and avoiding its risks. The intensive use of pesticides is readily to reduce yield loses and to stabilizes production, but it also leads to major risks of environmental pollution. An ideal pesticide should be present in the suitable position for a sufficient time, also it must be biodegradable and toxic only to the target organism. Indeed, once the pesticide finishes its role, it turns to be a pollutant, it must be removed from environment. With increased concern about environmental protection including soil, water and plant quality around the world, more emphasis is being placed on understanding the behaviour of agricultural pesticides and then finding the best management practice to reduce their impact on the environment. Therefore, it is very important to understand the fate and behaviour of pesticides in agriculture environment. Fate and behaviour of pesticides in soil, water and plant are determined by a combination of the adsorption-desorption, leaching, dissipation and bioavailability processes. Moreover, the sideeffects of pesticides on non-target organisms in their ecosystem play essential role to evaluate the pesticides.However, the review and literature describing the environmental behaviour and sideeffects of pesticides in particular insecticide fenitrothion and herbicide thiobencarb is poor although their wide application in many countries including Egypt. Modeling the behaviour of pesticides and their effects will be supporting the development of an environmentally friendly pesticides. Simulation of pesticide behaviour in the environment has been increasingly used for some years for research purposes and, in the last decade, for regulation. In general, the modeling reduces the cost and the time as well as predicts the behaviour under different conditions. Therefore, our study included two approaches; experimental approach with various scales to monitor the fate and behaviour of pesticides and approach of the modeling to predict the behaviour of pesticides in soil. The study aimed to understand and determin the experimental and simulating behaviour, and side-effects of two wide applied pesticides in rice paddy fields; fenitrothion (insecticide) and thiobencarb (herbicide), in soil-plant-water system under Egyptian conditions.112 The study includes two parts:Part 1. Study the behaviour of fentrothion and thiobencarb by various scales. Adsorptiondesorption isotherm, mobility using soil columns and lysimeter techniques, persistence in soil and water under laboratory conditions. Also, leaching using lysimeter facilities, bioavailability, persistence under field conditions. In addition, modeling of adsorption-desorption kinetics and isotherms. Part 2. Study the side-effects of fentrothion and thiobencarb on non-target organisms; soil organism (earthworms) and water organism (fish) including the toxicity, biochemically (enzymes activity of AChE, GST, SOD) and histological characteristics.The technical grade 97.0% a.i. and EC 50% formulation of fenitrothion (O, O-dimethyl O-4-nitro-m-tolyl phosphorothioate) and thiobencarb (S-4-chlorobenzyl diethyl thiocarbamate) were tested. Also, it was used two common Egyptian soil types; alluvial soil (clay soil). The organic and mineral soil components were fractionated. Rice plant Oryza sativa, variety Giza 101 was tested in the laboratory and field lysimeter. For side-effects study, it was used the adults of earthworm (Aporrectodea caliginosa) and fish Nile Tilapia (Oreochromis niloticus L.), a common type in Egypt and inparticular in rice fields. The pesticide residues weredetermined using HPLC 1260 (DAD-diod array detector), GC-MS a thermo Scientific gas chromatograph GC Trace 1300 coupled with an EI Mass spectrometer ISQ 7000 model (Thermo Scientific USA) and UV-Vis Spectrophotometer (Thermo Corporation, Nicolet, evolution 100, Germany), λmax was 266 nm and 233 nm for fenitrothion and thiobencarb, respectively. To achieve the objectives of this study, the batch sorption and desorption kinetic experiments were performed to obtain the equilibrium time. Five kinetic models (Elovich, Intraparticle diffusion, modified Freundlich, Pseudo-first-order rate and Pseudo-second-order rate) were tested to describe the experimental data. Also, adsorption and desorption isotherms by soil and its components HA, clay, silt and sand fractions were quantified using the batch equilibration technique. The isotherm data were modeled with the Freundlich, Langmuir, Temkin, Elovich, Redlich-Peterson and Halsey isotherm models. The validity of mathematical models was tested by various statistical parameters, the model that produced relatively high correlation coefficient (R2) and low values of normalized standard deviation (Δqe %) and summed squared error (SSE) as well as the agreement its trends of experimental and calculated model data, is the best fit model to describe the experimental data. In addition, the mobility of tested pesticides was investigated using the bench-scale soil columns, the laboratory minilysimeter and the field lysimeter. Rice plant uptake of tested pesticides at 1 and 10 µg/mL 111(equivalent to 1F and 10 F recommended rates) in laboratory was monitored at time of 0, 4, 8, 12, 16, 20, 24 and 28 days. The uptake of rice plant was determined at 10th week of pesticide application in the field. Moreover, the persistence of fenitrothion and thiobencarb at concentration of 75 μg/g soil was studied under laboratory and field conditions. On the other hand, the toxicity of tested pesticides on the earthworm was evaluated using filter paper contact test and soil mixing test. The side-effects of tested pesticides on the fish Nile tilapia were investigated. The toxicity by static bioassay technique was carried out. The side-effects at ½ LC50–96h on the biochemical indicators were studied on the AChE as a target of action of many pesticides, GST which play a key role in cellular detoxification and SOD which prevent the oxidative stress. Moreover, the histological examination of the fish exposed to the fenitrothion and thiobencarb individually. In general, the statistical analysis was used to detect the significant effects as well as to compare among treatments and variables.