Spatial heterogeneity in the soil system has a profound influence on the flow of water and chemicals in the unsaturated zone. Incorporating intrinsic soil variability and extrinsic variability into root zone leaching models will provide a better representation of pollutant distribution in natural field conditions. In this study, a stochastic framework (SF) was developed to represent spatial variability of soil properties in one-dimensional solute transport models, and implemented with two existing root zone leaching models, Opus and GLEAMS. The accuracy of soil water, bromide and pesticide transport predictions from Opus-SF and GLEAMS-SF was evaluated using field-measured soil water content, bromide and pesticide mass data from a 3.9-ha agricultural field in the Dougherty Plain of Georgia and a 0.05-ha field plot in Nomini Creek watershed in Virginia. Results from the rate-based Opus-SF and capacity-based GLEAMS-SF were compared to determine if there were significant differences in their predictions. In the stochastic approach, the heterogeneous field is conceptualized as a collection of vertical, non-interacting soil columns differing in soil properties. The horizontal variations of soil hydraulic and retention properties in each horizon are treated as random functions of zero transverse spatial correlation length, after accounting for any spatial trends. The spatially variable parameters were generated using the Latin hypercube sampling method, and the stochastic simulation of the model was performed using Monte-Carlo simulation techniques. Statistical tests indicated that Opus-SF and GLEAMS-SF did not predict the central tendency and distribution of depth-averaged soil water content and total pesticide mass observed in the field on most sampling dates. But their predictions were sufficiently accurate for most management-type applications. Soil hydraulic and retention properties derived from texture data at the Nomini Creek site substantially reduced the variability in soil water content predictions from both models, but had less impact on bromide and pesticide mass predictions from both models. The mean values predicted by Opus-SF and GLEAMS-SF were similar, but not equal to those predicted by the deterministic version of the models. Soil water and solute transport predictions from Opus-SF and GLEAMS-SF were not substantially different from corresponding results from the traditional Monte-Carlo approach, although soil water predictions from the two modeling approaches were significantly different for the first 150 days of simulation. Comparison between results from Opus-SF and GLEAMS-SF showed that the distributions and medians of soil water content predicted by the two models were significantly different on most sampling dates. The distributions and medians of pesticide mass predicted by the two models were closer than soil water content, but were significantly different on more than half of the field sampling dates. The more functional GLEAMS-SF model was able to simulate depth-averaged soil water content in the root zone better than the more physically based Opus-SF, although GLEAMS-SF was not able to simulate the depth distribution of soil water as accurately as Opus-SF. GLEAMS-SF was also able to predict solute movement at least as well as Opus-SF. GLEAMS-SF was able to simulate spatial variations of depth-averaged soil water content and pesticide mass in the field with reasonable accuracy employing fewer parameters that exhibit relatively lesser spatial variability. / Ph. D.

Concern about externalities associated with pesticide use in developing countries has motivated the development of integrated pest management (IPM) programs in these areas. In the Philippines, the IPM Collaborative Research Support Program (IPM CRSP) was established to specifically address the widespread misuse of pesticides in the rice-vegetable systems of Nueva Ecija, one of the major rice and onion producing regions in the country. IPM CRSP initiatives include research on the optimal use of pesticides, complementary weed control strategies, and alternative cultural and biological controls. If successful, the program should generate benefits that can be measured in economic terms. These benefits include improvements in water quality, food safety, pesticide applicator safety, and long run sustainability of pest management systems. This study was designed to measure the health and environmental benefits of the IPM CRSP in the Philippines. A survey questionnaire was administered to 176 onion farmers in five villages in Nueva Ecija to identify farm and farmer characteristics, pesticide usage, pest management practices, perceptions about pesticide hazards, awareness of IPM strategies, and willingness to adopt specific technologies being developed under the IPM CRSP. In addition, a contingent valuation survey was used to elicit farmers' willingness-to-pay to avoid risks posed by pesticides to different environmental categories. A comprehensive economic measure of the benefits of IPM CRSP was derived by 1) assessing the hazards associated with pesticide usage, 2) providing an ex ante measure of program impacts on pesticide usage, 3) predicting IPM adoption rates, and 4) estimating society's willingness-to-pay to avoid the health and environmental risks from pesticides under Philippine conditions. A measure of the amount of risks avoided as a result of IPM CRSP adoption was combined with farmers' willingness to pay bids for risk avoidance to derive a monetary value of the program benefits. The estimated economic benefits of the IPM CRSP to farmer residents in 5 villages in Nueva Ecija amount to 230,912.00 pesos for one onion season. / Ph. D.

This study evaluates the adoption and impacts of Integrated Pest Management (IPM) adoption for rice in Cambodia. Extent of adoption and characteristics of adopters are discovered. Farmers are considered high adopters of IPM if they used two non-pesticide or minimal-pesticide practices to control rice insect, disease, weed, or rodent pests in the last twelve months; farmers are considered low adopters if they used one practice; farmers are considered non-adopters if they used zero practices. IPM practices include pest-resistant variety; stale seedbed (sequential harrowing or harrowing followed by a non-selective herbicide); apply Trichoderma on seeds or seedlings, no insecticide spray for the first 40 days; apply bio-pesticides such as neem, Bt, and metarhizium, and Beauvaria; Sarcocystis bait for rodents; hand weeding at recommended growth stage; and/or another practice specified by the farmer. Out of 394 farmers surveyed, 40 (10.15%) were found to be high adopters, 228 (57.86%) were found to be low adopters, and 126 (31.97%) were found to be non-adopters of IPM. IPM practices currently include mostly hand-weeding and no spray for 40 days; few other practices were adopted. Our study reveals a need for broader education on rice IPM throughout Cambodia. The high frequency of pesticide applications among rice farmers, the finding that adoption of IPM was not found to have a meaningful influence on the number of pesticide applications, and the finding that less than one-quarter of farmers in our study have received training on IPM reveal the need for increased knowledge of IPM in Cambodia, and the need for future education on IPM to focus on reducing pesticide use. / Master of Science / This study evaluates the adoption and impacts of Integrated Pest Management (IPM) for rice in four provinces in Cambodia. IPM is an ecologically-friendly pest management philosophy that offers alternatives to reliance on harmful chemical pesticides. Farmers are divided into groups of high adopters, low adopters, and non-adopters depending on the number of IPM practices used. Proportion and characteristics of adopters, frequency and type of IPM practices, and scope of IPM training in the region are discovered. Determinants of adoption and the effect of adoption on level of pesticide use on rice are analyzed using econometric analysis. Out of 394 farmers surveyed, 40 (10.15%) were found to be high adopters, 228 (57.86%) were found to be low adopters, and 126 (31.97%) were found to be non-adopters of IPM. Adopters primarily use only two types of IPM practices. Less than one-quarter of farmers in our study have received training on IPM. Farmers who have more years of experience in rice cultivation, and farmers who consider agricultural extension a top source of agricultural information are more likely to adopt IPM. Farmers who have more family members who are able to work, and farmers who consider input suppliers a top source of agricultural information are less likely to adopt IPM. Adoption of IPM was not found to meaningfully influence the number of pesticide applications on rice. Our study reveals the need for increased training on rice IPM in Cambodia, and the need for future IPM education to focus on reducing pesticide use.

This project investigates the effect of plasticulture and copper-based crop protectants on water quality on the Eastern Shore of Virginia. Water and sediment copper concentrations in both plasticulture and non-plasticulture containing watersheds were measured to determine the scope of copper in Eastern Shore tidal creeks. Runoff from a variety of land-uses including agricultural, plasticultural, residential and natural areas were collected and measured for copper to determine where copper-containing runoff originates. Copper concentrations in plasticulture impacted tidal creeks were higher than background (0 - 3 ug/L) only in spikes, during or immediately after runoff-producing rainfall events. These spikes registered as high as 263 ug/L total copper, or 127 ug/L dissolved copper. Plasticulture and copper-based crop protectants were affirmed as the cause of these spikes because control watersheds indicated no high copper spikes. Runoff from different land-uses verify that copper is present in high concentrations only in runoff from fields engaged in plasticulture and using copper-based crop protectants. Sediment copper concentrations were found to be within the natural range, but exhibited some variability based on proximity to agricultural copper inputs. / Master of Science

The object of this study is to design a commercial plant for the production of a Pesticide formed by the condensation of para-dichlorobenzene with chloral. / Master of Science

About 50 synthetic organic chemicals (SOCs), including pesticides and polyaromatic hydrocarbons (PAHs), have been identified as possible contaminants in the Occoquan Watershed. Since 1982, water, sediment, and fish samples have been collected from the streams and reservoirs of the watershed 2-4 times per year. The Occoquan Watershed Monitoring Laboratory (OWML) collected samples and analyzed for a targeted set of compounds. Beginning in 1993, new SOC screening methods consisting of solid-phase extraction (SPE) followed by gas chromatography with mass spectrometric detection (GC/MS) were developed for water and sediment samples. A similar method for fish tissue was developed in this study using methanol extraction with C-18 and alumina SPE cleanup. Method detection limits (MDLs) ranged from 0.03-0.37 mg/kg wet weight and recoveries in matrix spikes ranged from 15-92%. Very few SOCs in OWML's database were found at levels above method detection limits. In water, atrazine was the most commonly detected compound (87 detections out of 610 samples analyzed). It was also found in 8 sediment samples and 1 fish organ sample. Atrazine concentrations were highest in the spring; summer provided the most frequent detections. Detections occurred at multiple locations during the same sampling period; stations furthest west (nearest to agricultural areas) tended to show the highest values. Rainfall events were associated with 23% of atrazine detections. The raw and finished water samples from the two water treatment plants in the basin showed that the average atrazine removal by conventional treatment was 37%. / Master of Science

Microbial populations from subsurface soil collected from a hydrocarbon contaminated site and a pristine site with no history of contamination had the ability to degrade pentachlorophenol (PCP) in anaerobic enrichment cultures. Increasing concentrations of PCP in nitrate, sulfate and yeast extract-mineral salts media were used to acclimate the cultures. Nitrate enrichments, previously incubated in an anaerobic phenol-mineral salts medium, showed 23% degradation in medium containing 40 μg ml⁻¹ PCP during a 32 d incubation period. Cultures not adapted to phenol degradation did not degrade PCP at concentrations over 20 μg ml⁻¹. Enrichment cultures grown in the anaerobic yeast extract-mineral salts medium did not degrade PCP at concentrations over 20 μg ml⁻¹ and phenol adaptation did not enhance PCP degradation. The sulfate reducing enrichment containing 1 μg ml⁻¹ PCP showed 71.3% degradation after 32 d incubation. No degradation occurred at or above 5 μg ml⁻¹ PCP. PCP intermediates, 2,4,6-trichlorophenol (TCP) and 3,4,5 TCP were found in the spent culture of the nitrate reducing enrichment. In the spent culture of the sulfate reducing enrichment, 3,4,5 TCP and 2,3,4,5-tetrachlorophenol were found. Attempts to obtain a pure culture of an anaerobic PCP degrading bacterium were unsuccessful. / Master of Science

Thesis (MSc)--Stellenbosch University, 2005. / ENGLISH ABSTRACT: The agricultural sector in South Africa relies heavily on the use of pesticides to protect crops against pest organisms. Pesticides can affect non-target organisms such as the meso- and macrofauna in the soil detrimentally. Since these organisms play an important role in the processes of mineralization and decomposition in the soil and contribute to soil fertility, it is important that they are protected. A large amount of published literature exists on the biological importance of soil meso- and macrofauna and the effects that various agricultural practices have on them. The main aim of this study was to investigate the influence of agricultural practices on the abundance and diversity of meso- and macrofauna in different vineyard soils. A comparative study was conducted of an organically managed, conventionally managed and an uncultivated control soil. A secondary aim was to determine the effect of these agricultural management practices on the biological activity of these animals. Soil samples were taken, from which mesofauna (Collembola and Acari) were extracted with a modified Tullgren extractor, identified and counted. Earthworms were extracted from the soil using hand sorting methods. Soil parameters such as pH, water holding capacity, organic matter content, soil texture and soil respiration were determined. Bait lamina and litter-bags were also used to help determine the biological activity within the soil. The mesofauna diversity was quantified using the Shannon Weiner diversity index, as well as a diversity index described by Cancela da Fonseca and Sarkar (1996). Differences in abundance of both the meso-and macrofauna were statistically measured using ANOVA's. Biological activity results were also interpreted using ANOV A's. Results indicate that the abundance of the meso fauna was the highest at the organically treated vineyard soil and lowest in the conventionally managed soil where pesticide application took place. The earthworms also showed the same trend as the mesofauna, but were much more influenced by seasonal changes. Biological activity, according to the bait lamina and the litter-bag results, was higher in both the conventionally and organically managed soils than in the control, but no statistical significant differences were found between the two experimental soils. The soil respiration (C02-flux), also indicating biological activity, was highest in the organically treated soil and lowest in the conventionally treated soil. The different sampling techniques used gave variable results and although the organically managed soil proved to have higher abundances of both meso- and macrofauna, the biological activity did not show the same trends. In conclusion the data did not give enough evidence as to whether organic management practices were more beneficial than conventional management practices for the maintenance of soil biodiversity. / AFRIKAANSE OPSOMMING: Die Suid Afrikaanse Landbousektor steun hewig op die gebruik van verskillende chemiese pestisiede om oeste teen pes organismes te beskerm. Pestisiede kon ook verskeie ander nie-teikenorganismes soos die meso- en makrofauna in die grond negatief affekteer. Hierdie organismes behoort beskerm te word omdat hulle 'n belangrike rol speel in grondprosesse soos mineralisering, en die afbreek van organiese materiaal. Hierdie organismes dra ook by tot die vrugbaarheid van die grond. Daar is heelwat gepubliseerde literatuur beskikbaar wat verband hou met die biologiese belangrikheid van grond meso- en makrofauna en die effekte wat verskeie landbou behandelings op hulle het. Die primêre doel van hierdie studie was om vas te stel watter invloed konvensionele landboupraktyke op die hoeveelheid en diversiteit van meso- en makrofauna in verskillende wingerdgronde het. 'n Vergelykende studie is gedoen om wingerdgronde wat konvensioneel en organies behandel is sowel as 'n onbehandelde kontrolegrond met natuurlike plantegroei met mekaar te vergelyk. 'n Sekondêre doel van hierdie studie was ook om die effek van die verskillende boerderymetodes op die biologiese akitiwiteit in die grond te ondersoek. Grondmonsters is geneem, waaruit die meso fauna (Collembola en Acari) deur middel van 'n aangepaste Tullgren ekstraktor ge-ekstraheer, geïdentifiseer en getel. Die erdwurms is deur middel van handsorteringsmetodes versamel. Die volgende grond parameters is gemeet: pH, waterhouvermoë, organiese materiaal inhoud, grondtekstuur en grondrespirasie. "Bait lamina" en "litter bags" is ook gebruik om biologiese aktiwiteit in die grond te bepaal. Die diversiteit van mesofauna is bepaal met die Shannon Weiner diversiteitsindeks, as ook 'n diversiteitsindeks wat deur Cancela da Fonseca en Sarkar (1996) ontwikkel is. Die resultate van beide die meso- en makrofauna hoeveelhede in die verskillende wingerdgronde is met mekaar vergelyk deur van ANOV A's gebruik te maak. Die resultate van die biologiese aktiwiteit is ook deur middel van ANOVO's statisties met mekaar vergelyk. Die resultate het aangetoon dat die hoeveelheid mesofauna die hoogste in die organies behandelde grond en die laagste in konvensionele grond was. Die erdwurms het dieselfde patroon as die mesofauna getoon, maar is baie meer deur seisoenale faktore geaffekteer, bv. reënval. Volgens die resultate van die "bait lamina" en die "litter bags" was die biologiese aktiwiteit in die grond hoër in beide die eksperimentele grond as in die kontrolegrond. Die grondrespirasie (C02-puIs) was hoër in die kontrolegrond as in die ander eksperimentele gronde. Daar was groot variasie tussen die resultate wat met die verskillende tegnieke verkry is en alhoewel die organiese perseel hoër hoeveelhede van beide meso- en makrofauna gehad het, het die biologiese aktiwiteit nie dieselfde tendens gewys nie. Vanuit die data wat verkry is kon daar dus nie met sekerheid afgelei word dat organiese boerderymetodes beter vir die biodiversiteit van gronde,soos hier gemeet, is as konvensionele boerderymetodes nie.

Thesis (Ph.D)--Stellenbosch University, 2000. / ENGLISH ABSTRACT: Copper oxychloride is a fungicide that is extensively used in vineyards in the Western Cape to treat and prevent fungal diseases. It is however not clear what the effects are on soil organisms, which play an important role in soil fertility, in South African soils. There is paucity of data linking results obtained in the laboratory to effects observed in the field, which will only become useful if a clear relation can be demonstrated. The aims of this study were to: ~ Determine the effects of copper oxychloride on field populations of earthworms and simultaneously monitor lysosomal membrane stability, measured as neutral red retention time (NRRT). ~ Validate experimental field studies by doing inventories of earthworm populations in long-term sprayed vineyards. ~ Determine the LC50 of copper oxychloride and simultaneously measuring NRRT, and linking them to the experimental field studies. ~ Conduct bioassays, burrowing activity- and soil-avoidance experiments to investigate their relations to earthworm population responses in the experimental field studies. Earthworms were sampled by hand-sorting in the field tests on treated and untreated field plots in the Western- (October 1998 - July 1999) and Northern Cape (April 1998 - October 1999). Soil samples and worms were analysed for copper contents and coelomocytes of live earthworms were used to conduct the neutral red retention assays. Acute toxicity tests were conducted over a period of 28 days during which the earthworms (Eisenia fetiday were exposed to different concentrations of copper oxychloride. Change in biomass and mortality were measured as endpoints, as well as NRRT. Bioassays, burrowing activity and soil-avoidance were conducted by exposing Aporrectodea caliginosa to grassland- and vineyard soil as well as grassland soil spiked with 60 J.1g.g-1copper in the form of copper oxychloride. Growth and mortality were recorded in the bioassays as well as copper concentrations In earthworm body tissues and substrates used over a period of28 days. Burrowing activity and soil-avoidance were determined by measuring the length of tunnels burrowed by A. caliginosa in soil profiles over a period of 4 days under different exposure regimes. Results from the field tests showed that spraying of copper oxychloride had a negative effect on earthworm populations at the prescribed application rates. NRR T in earthworms from the exposure plots was significantly (p<0.05) lower after just one spraying application. It was concluded that spraying copper oxychloride at prescribed application rates caused a decrease in field populations of earthworms and that NRRT was an early and reliable biomarker since it was indicative of later effects observed at the population level. Results obtained from the field inventory of earthworms in vineyards at Nietvoorbij, Robertson end Worcester confirmed data from the two field studies. The calculated LC50 of 882.78 I1g.g-1 for copper oxychloride and 519.40 I1g.g-1 for copper was ecologically relevant if a safety factor of 10 was applied. NRRT which manifested earlier than effects on biomass change in the acute toxicity tests, were significant when viewed against the background of responses of field populations of earthworms. From the bioassay experiments it was found that A. caliginosa exposed to copper oxychloride spiked soil had significantly (p<0.05) higher weight loss and mortality than those in grassland- and vineyard soil. This indicated that changes in biomass and mortality were indicative of population responses in the field and can be considered as ecologically relevant. Burrowing activity of A. caliginosa was significantly (p<0.05) lower in vineyard and copper oxychloride spiked soil than in grassland soil. Similarly in the soil avoidance experiments it was found that A. caliginosa avoided vineyard- and copper oxychloride contaminated soil. It is therefore concluded that burrowing activity and soil avoidance were ecologically relevant endpoints since they corresponded with population responses in the field. The study thus revealed that the long-term usage of copper oxychloride could have negative effects on earthworm populations. The spraying of copper oxychloride can have important implications on the sustainable use of agricultural soils since earthworms and other soil organisms play such an important role in soil fertility. The use of biomarkers and other ecotoxicological indicators can provide an early warning that soil organisms are under environmental stress. / AFRIKAANSE OPSOMMING: Die fungisied koperoksichloried word wyd gebruik in die Wes-Kaap om swamsiektes in wingerde te beheer en te voorkom. Dit is egter nie bekend wat die effek daarvan op Suid Afrikaanse grondbiota, wat 'n belangrike rol speel in grondvrugbaarheid, is nie. Daar is ook 'n tekort aan inligting wat die resultate van laboratoriumondersoeke in verband bring met veldstudies. Die doelstellings van die studie was om: ~ Die effek van koperoksichloried op erdwurmpopulasies in die veld te ondersoek en terselfdertyd membraanstabiliteit, as moontlike biomerker, gemeet as neutraal rooi retensietye (NRRT), te monitor. ~ Die geldigheid van eksperimentele veldstudies te toets deur ook grondanalises te doen in wingerde wat oor langtermyn met koperoksichloried bespuit is. ~ Die LC50 van koperoksichloried vir erdwurms te bepaal en terselfdertyd NRR T te meet asook om dié gegewens in verband te bring met die resultate van seisoenale veldstudies oor die uitwerking op erdwurmpopulasies. ~ Bio-evaluerings ("bioassays"), tonnelaktiwiteit- en vermydingseksperimente te onderneem en die verband tussen die toksiteitstoetse en populasieresponse, soos waargeneem in die veld, te ondersoek. Erdwurms is versamel deur handsortering tydens die veldtoetse in die Wes- (Oktober 1998 - Julie 1999) en Noord-Kaap (April 1998 - Oktober 1999) op kontrole en bespuite persele. Grondmonsters en erdwurms is spektrofotometries geanaliseer om koperinhoude te bepaal. Die selomosiete van lewende wurms is gebruik om NRR T te bepaal. Akute toksisiteitstoetse is uitgevoer oor 'n tydperk van 28 dae waartydens Eisenia fetida blootgestel is aan verskillende koperoksichloried konsentrasies. Veranderinge in biomassa en mortaliteit is bepaal asook NRRT. Bioevaluerings ("bioassays"), tonnelaktiwiteit- en vermydingseksperimente IS uitgevoer deur Aporrectodea caliginosa bloot te stel aan grasveld- en wingerdgrond asook grasveldgrond wat met koperoksichloried gekontamineer is. Groei en mortalitiet is bepaal in die "bioassays" asook koperkonsentrasies in die grond en erdwurm liggaamsweefsels oor 'n tydperk van 28 dae. Tonnelaktiwiteit en grondvermyding is bepaal deur die lengte van tonnels wat deur A. caliginosa gegrawe is te meet oor 'n tydperk van vier dae vir die verskillende blootgestelde groepe. Die resultate het aangedui dat koperoksichloriedbespuiting 'n negatiewe invloed het op erdwurmpopulasies teen die voorgeskrewe toedieningsprogram. NRRT in erdwurms van die blootstellingperseel, was beduidend (p<0.05) laer na 'n enkele bespuiting. Daar is verder bevind dat NRR T 'n betroubare en vroeë biomerker is, aangesien dit 'n aanduiding gegee het van latere effekte wat op populasievlak na vore getree het. Veldopnames in Nietvoorbij, Robertson en Worcester het die geldigheid van data verkry uit die veldstudies ondersteun. Die berekende LC50 van 882.78 ug.g" vir koperoksichloried en 519.40 ug.g" VIr koper was ekologies relevant indien 'n veiligheidsfaktor van 10 toegepas is. NRRT se ekologiese relevansie is bevestig deur dit te vergelyk met response wat in die veldtoetse waargeneem is. Deur bioevalueringseksperimente is bevind dat gewigsverlies en mortaliteit van A. caliginosa beduidend hoër was in koperoksichloried gekontamineerde grond as in die grasveld- (kontrole) en wingerdgronde. Veranderinge in biomassa en mortalitiet was aanduidend van populasieresponse soos waargeneem in die veldstudies en kan dus as ekologies relevante eindpunte beskou word. Tonnelaktiwiteit van A. caliginosa was beduidend (p<0.05) laer in wingerd- en koperoksichloried gekontamineerde grond as in grasveldgrond. Dieselfde is gevind in die grondvermydingstoetse waar A. caliginosa wingerd- en koperoksichloried gekontamineerde grond vermy het. Dit kan dus afgelei dat tonnelaktiwiteit en grondvermyding ook ekologies bruikbare eindpunte is aangesien dit verband hou met populasieresponse soos waargeneem in die veldstudies. Hierdie studie het getoon dat die herhaalde gebruik van koperoksichloried 'n nadelige invloed kan hê op erdwurmbevolkings. In die lig van die belangrike rol wat erdwurms en ander grondorganismes speel in grondvrugbaarheid kan die oormatige gebruik van hierdie fungisied ernstige implikasies inhou vir volhoubare benutting van landbougronde. Die gebruik van biomerkers en ander ekotoksikologiese eindpunte kan egter as vroeë waarskuwingsmetode dien dat die grondorganismes onder omgewingstres verkeer.

Le devenir des pesticides en polyculture d’étang est peu étudié, en particulier la contamination de la chair des poissons proposés aux consommateurs. Cinq sites, correspondant chacun à un étang et à son bassin versant, ont été caractérisés. Ils s’échelonnent sur un gradient d’intensification agricole allant de 0% à 85% de la surface mise en culture. La somme des concentrations de pesticides quantifiés dans l’eau s’échelonne de 0,17 à 8,81 µg/L. La réponse biologique des poissons, évaluée par la recherche de huit biomarqueurs (EROD, CYP 3A, GST, CAT, SOD, GSH, GPx et AChE), a permis d’établir des différences entre les espèces et les sites étudiés. Une recherche ciblée de pesticides épandus sur grandes cultures, a été effectuée par une méthode multi-résidus, dans l’eau, les sédiments et la chair de poisson. L’isoproturon (valeur maximale 2,69µg/L) et le métazachlore (valeur maximale 0,54 µg/L) présentent les concentrations les plus élevées dans l’eau; la trifluraline (0,5 à 13 µg/kg PS) et l’isoproturon (0,7 à 56,4 µg/kg PS) dans les sédiments. Les profils de résidus dans la chair de poisson sont variables et seuls la trifluraline, l’isoproturon, le métazachlore et le carbendazime (valeurs maximales de 21 ; 0,75 ; 0,13 et 0,2 µg/kg PF, respectivement) sont quantifiés. Les facteurs de bioamplification et les demi-vies dans le muscle ont été évalués (10-6 < BMF < 10-3, 1j <DT50 < 40 j) pour la plupart des molécules. Au final, de nombreux facteurs, liés en particulier aux caractéristiques des sites (non maîtrisables) et aux pratiques de gestion (améliorables), influencent le profil des pesticides dans le muscle et la réponse biologique des poissons / Dam pond is connected to its watershed. Use of pesticides on watershed may lead to dissipation in the environment Transfer of registered pesticides remains poorly studied. Thus, the main objective of this work was to improve knowledge about the fate of pesticides in polyculture pond, especially contamination of fish flesh. Five sites, each site corresponding to a pond and its watershed, were characterized. They are placed on a gradient of crop proportion ranging from 0% to 85% of the watershed area. The sum of quantified molecules in water ranged from 0.17 to 8.81 µg / L. The biological response of fish, assessed by evaluation of eight biomarkers (EROD, CYP 3A, GST, CAT, SOD, GSH, GPx, and AChE), establish differences between species and sites studied. A study of 14 targeted pesticides was conducted by a multi-residues method in water, sediments and fish flesh. Isoproturon (maximum value 2.69 µg/L) and metazachlor (maximum value 0.54 µg/L) are the main contaminants in water; Trifluralin (0.5 to 13 µg/kg PS) and isoproturon (0.7 to 56.4 µg/kg PS) in sediments. Trifluralin, isoproturon, carbendazim and metazachlor (maximum values of 21, 0.75, 0.13 and 0.2 µg/kg PF, respectively) are quantified in muscle of fish. Low levels observed in fish can be explained by a low potential to bioaccumulate (measured ex-situ for some molecules, between 10-6 and 10-3). However, half-lives in the muscle may be several weeks depending, explaining the possibility to find molecules in fish flesh. Finally, many factors, particularly related to site characteristics (uncontrollable) and management practices (upgradable), influence profile of pesticides in muscle and biological responses of fish