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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

Tillage effects on leaching and persistence of pesticides in coastal plain soil

Zacharias, Sebastian 24 November 2009 (has links)
The effect of tillage practices on leaching and persistence of atrazine and metolachlor was evaluated in a field study in the Coastal Plain region of Virginia. Field data were also used to validate pesticide transport models, GLEAMS and PRZM. The study was conducted on two 18x27 m plots located in a field that was in the second year of a two-year no-till wheat-beaDs-com rotation. One plot was conventionally tilled using a moldboard plow and a disk harrow before planting of com and application of chemicals. Soil samples were collected on six sampling dates during the crop growing season at 20 randomly selected locations in each plot with the 0-150 cm sampling depth divided into eight increments. Bromide concentrations were analyzed to provide an estimate of solute movement. High rainfall following chemical application led to rapid leaching of bromide, with the chemical moving faster in the no-till profile. Pesticide concentrations also showed a greater potential for leaching in the no-till plot in the early stages of the study. Chemical concentrations were higher in the no-till profile initially, and were higher in the tilled profile toward the end of the season. Atrazine dissipation was higher in the no-till plot, but there was no marked difference in metolachlor dissipation between the two tillage treatments. Over 35% of atrazine mass remained in the soil profile in both plots at the end of the crop growing season. Pesticide concentrations were found to vary largely over the two plots. The field data were used to evaluate the ability of the pesticide transport models, GLEAMS and PRZM, to represent chemical concentration distribution, depth of solute center of mass, and pesticide mass in the no-till and the conventionally-tilled root zone. The models were evaluated in three sequential steps. The fast simulation was completely uncalibrated, using best available estimates for the input parameters. For the second simulation hydrology parameters were calibrated to minimize errors in the hydrology component so as to better evaluate the prediction of pesticide behavior in soil. The third stage of the evaluation used pesticide dissipation half-life calculated from the field data. Model performance was evaluated using both objective and subjective criteria. GLEAMS and PRZM predicted pesticide concentration in soils reasonably well when run without any calibration. Bromide concentrations were predicted closer to the observed values than pesticides. Overall predictions by both models were better in the conventional tillage plot than in the no-till plot. The comparative effect of tillage on observed chemical concentrations was represented better by GLEAMS than by PRZM. The models under-predicted leaching of pesticides in the early sampling dates. Predicted pesticide mass in the root zone were reasonably close to the field measured values. Calibration of the hydrology component of the models did not improve the prediction of pesticide behavior in soils. The use of field pesticide half-life resulted in better prediction of pesticide persistence but did not improve the overall prediction of pesticide behavior in the two plots. The study identifies selection of input parameters and correct interpretation of results as important factors in the effective use of GLEAMS and PRZM as management tools. / Master of Science
32

Estimating the marginal productivity of pesticides on irrigated corn and grain sorghum farms in western Kansas

Sleper, James R. January 2011 (has links)
Typescript (photocopy). / Digitized by Kansas Correctional Industries
33

The abundance and diversity of meso- and macrofauna in vineyard soils under different management practices

Nel, Werner 03 1900 (has links)
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.
34

Modelling the behaviour and fate of priority pesticides in South Africa.

Maharaj, Simone January 2005 (has links)
The use of pesticides poses a serious threat to the limited water resources of South Africa. The amounts which are not taken up by crop plants, are often washed away by runoff into surface waters, or leached through the soil, causing groundwater pollution. The problem of pesticide pollution is often intensified by inappropriate usage, disposal and monitoring in agriculture and predictive models have proven to be an effective tool for improving management practices. Research, however, has focused mainly on surface water contamination and groundwater impacts are largely unknown. Furthermore, pesticide registration in South Africa is largely determined by international standards and there is a need for impact assessments to be carried out under local conditions. The aims of this study included the determination of priority pesticides in South Africa based on usage and properties, the determination of pesticide sorption in two selected South African soils, and an assessment of pesticide fate by modelling.
35

Removal of pentachlorophenol and methyl-parathion by spent mushroom compost of oyster mushroom.

January 2001 (has links)
by Law Wing Man. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2001. / Includes bibliographical references (leaves 192-206). / Abstracts in English and Chinese. / Acknowledgments --- p.i / Abstract --- p.ii / List of Figures --- p.vi / List of Tables --- p.xii / Abbreviations --- p.xv / Chapter 1. --- Introduction / Chapter 1.1. --- Pesticides --- p.1 / Chapter 1.1.1. --- Types and uses --- p.1 / Chapter 1.1.2. --- Development of pesticides --- p.1 / Chapter 1.1.3. --- The case against pesticides --- p.3 / Chapter 1.2. --- Pentachlorophenol --- p.4 / Chapter 1.2.1. --- Production --- p.4 / Chapter 1.2.2. --- Toxicity --- p.4 / Chapter 1.2.3. --- Persistency --- p.6 / Chapter 1.3. --- Methyl-parathion --- p.9 / Chapter 1.3.1. --- Production --- p.9 / Chapter 1.3.2. --- Toxicity --- p.9 / Chapter 1.3.3. --- Environmental fate --- p.12 / Chapter 1.4. --- Conventional methods dealing with pesticides --- p.12 / Chapter 1.5. --- Bioremediation --- p.15 / Chapter 1.6. --- Spent mushroom compost --- p.17 / Chapter 1.6.1. --- Background --- p.17 / Chapter 1.6.2. --- "Physical, chemical and biological properties of SMC " --- p.19 / Chapter 1.6.3. --- Recycling of agricultural residuals --- p.21 / Chapter 1.6.3.1. --- Definition --- p.21 / Chapter 1.6.3.2. --- Types of recycling --- p.22 / Chapter 1.6.4. --- Potential uses of SMC as bioremediating agent --- p.23 / Chapter 1.6.4.1. --- Use of microorganisms in SMC --- p.23 / Chapter 1.6.4.2. --- Use of ligninolytic enzymes in SMC --- p.24 / Chapter 1.7. --- Ligninolytic enzymes --- p.28 / Chapter 1.7.1. --- Background --- p.28 / Chapter 1.7.2. --- What are white rot fungi? --- p.29 / Chapter 1.7.3. --- Why is lignin so difficult to degrade? --- p.29 / Chapter 1.7.4. --- Three main ligninolytic enzymes --- p.32 / Chapter 1.7.4.1. --- Lignin peroxidases (LiP) --- p.32 / Chapter 1.7.4.2. --- Manganese peroxidase (MnP) --- p.36 / Chapter 1.7.4.3. --- Laccase --- p.37 / Chapter 1.8. --- Why SMC was chosen to be the bioremediating agent in my project? --- p.40 / Chapter 1.9. --- Bioremediation of chlorophenols and PCP --- p.44 / Chapter 1.9.1. --- Bacterial system --- p.44 / Chapter 1.9.2. --- Fungal system --- p.45 / Chapter 1.10. --- Bioremediation of methyl-parathion --- p.49 / Chapter 1.10.1. --- Bacterial system --- p.49 / Chapter 1.10.2. --- Fungal system --- p.51 / Chapter 1.11. --- Proposal and experimental plan of the project --- p.51 / Chapter 1.11.1. --- Study the removal of pesticides in both aquatic and soil system --- p.52 / Chapter 1.11.2. --- Research strategy --- p.52 / Chapter 1.11.3. --- Optimization of pesticide removal --- p.53 / Chapter 1.11.4. --- Identification of breakdown products --- p.54 / Chapter 1.11.5. --- Toxicity assay --- p.54 / Chapter 1.11.6. --- Isotherm plot --- p.55 / Chapter 1.12. --- Objectives of the study --- p.56 / Chapter 2. --- Material and Methods --- p.58 / Chapter 2.1. --- Material --- p.59 / Chapter 2.2. --- Production of Spent Mushroom Compost (SMC) --- p.59 / Chapter 2.3. --- Characterization of SMC --- p.60 / Chapter 2.3.1. --- PH --- p.60 / Chapter 2.3.2. --- Electrical conductivity --- p.60 / Chapter 2.3.3. --- "Carbon, hydrogen, nitrogen and sulphur contents " --- p.60 / Chapter 2.3.4. --- Ash content --- p.61 / Chapter 2.3.5. --- Metal analysis --- p.61 / Chapter 2.3.6. --- Anion content --- p.62 / Chapter 2.3.7. --- Chitin assay --- p.62 / Chapter 2.4. --- Characterization of soil --- p.63 / Chapter 2.4.1. --- Soil texture --- p.63 / Chapter 2.4.2. --- Moisture content --- p.64 / Chapter 2.5. --- Basic studies on the removal capacity of pesticides by SMC --- p.65 / Chapter 2.5.1. --- Preparation of pentachlorophenol and methyl- parathion stock solution --- p.66 / Chapter 2.6. --- Experimental design --- p.65 / Chapter 2.6.1. --- In aquatic system --- p.65 / Chapter 2.6.2. --- In soil system --- p.68 / Chapter 2.7. --- Extraction of pesticides --- p.68 / Chapter 2.7.1. --- In aquatic system --- p.68 / Chapter 2.7.2. --- In soil system --- p.69 / Chapter 2.8. --- Quantification of pesticides --- p.69 / Chapter 2.8.1. --- By high performance liquid chromatography --- p.69 / Chapter 2.8.2. --- By gas chromatography-mass spectrometry --- p.71 / Chapter 2.9. --- Optimization of pesticides degradation by SMC in both aquatic and soil systems --- p.72 / Chapter 2.9.1. --- Effect of initial pesticide concentrations on the removal of pesticides --- p.72 / Chapter 2.9.2. --- Effect of amount of SMC used on the removal of pesticides --- p.73 / Chapter 2.9.3. --- Effect of incubatoin time on the removal of pesticides --- p.73 / Chapter 2.9.4. --- Effect of initial pH on the removal of pesticides --- p.73 / Chapter 2.9.5. --- Effect of incubation of temperature on the removal of pesticides --- p.74 / Chapter 2.10. --- The study of breakdown process of pesticides --- p.74 / Chapter 2.10.1. --- GC/MS --- p.74 / Chapter 2.10.2. --- Ion chmatography --- p.74 / Chapter 2.11. --- Microtox® assay --- p.75 / Chapter 2.12. --- Assessment criteria --- p.75 / Chapter 2.12.1. --- In aquatic system --- p.75 / Chapter 2.12.2. --- In soil system --- p.76 / Chapter 2.13. --- Statistical analysis --- p.77 / Chapter 3. --- Results / Chapter 3.1. --- Characterization of SMC and soil --- p.78 / Chapter 3.2. --- Quantification of pesticides by HPLC and GC/MS --- p.82 / Chapter 3.3. --- Extraction efficiencies of pesticides with hexane --- p.82 / Chapter 3.4. --- Stability of pesticides against time --- p.82 / Chapter 3.5. --- Effect of sterilization of soil in the removal abilities of pesticides…… --- p.88 / Chapter 3.6. --- Optimization of removal of pentachlorophnol --- p.88 / Chapter 3.6.1. --- Effect of incubation time --- p.88 / Chapter 3.6.1.1. --- In aquatic system --- p.88 / Chapter 3.6.1.2. --- In soil system --- p.88 / Chapter 3.6.2. --- Effect of initial PCP concentrations and amout of SMC used --- p.91 / Chapter 3.6.2.1. --- In aquatic system --- p.91 / Chapter 3.6.2.2. --- In soil system --- p.94 / Chapter 3.6.3. --- Effect of pH --- p.97 / Chapter 3.6.3.1. --- In aquatic system --- p.97 / Chapter 3.6.3.2. --- In soil system --- p.97 / Chapter 3.6.4. --- Effect of incubation temperature --- p.97 / Chapter 3.6.4.1. --- In aquatic system --- p.97 / Chapter 3.6.4.2. --- In soil system --- p.101 / Chapter 3.6.5. --- Potential breakdown intermediates and products --- p.101 / Chapter 3.6.5.1. --- In aquatic system --- p.101 / Chapter 3.6.5.2. --- In soil system --- p.104 / Chapter 3.7. --- Microtox® assay of PCP --- p.110 / Chapter 3.7.1. --- In aquatic system --- p.110 / Chapter 3.7.2. --- In soil system --- p.110 / Chapter 3.8. --- Optimization of removal of methyl-parathion --- p.113 / Chapter 3.8.1. --- Effect of incubation time --- p.113 / Chapter 3.8.1.1. --- In aquatic system --- p.113 / Chapter 3.8.1.2. --- In soil system --- p.113 / Chapter 3.8.2. --- Effect of initial concentration and amount of SMC --- p.115 / Chapter 3.8.2.1. --- In aquatic system --- p.115 / Chapter 3.8.2.2. --- In soil system --- p.117 / Chapter 3.8.3. --- Effect of incubation temperature --- p.120 / Chapter 3.8.3.1. --- In aquatic system --- p.120 / Chapter 3.8.3.2. --- In soil system --- p.120 / Chapter 3.8.4. --- Potential breakdown intermediates and products --- p.121 / Chapter 3.8.4.1. --- In aquatic system --- p.121 / Chapter 3.8.4.2. --- In soil system --- p.124 / Chapter 3.9. --- Microtox ® assay of methyl-parathion --- p.133 / Chapter 3.9.1. --- In aquatic system --- p.133 / Chapter 3.9.2. --- In soil system --- p.133 / Chapter 4. --- Discussion / Chapter 4.1. --- Characterization of SMC and soil --- p.137 / Chapter 4.2. --- Stability of pesticides against time in aquatic and soil system --- p.141 / Chapter 4.3. --- Effect of sterilization of soil in the removal abilities of pesticides --- p.142 / Chapter 4.4. --- Optimization of removal of PCP --- p.142 / Chapter 4.4.1. --- Effect of incubation time --- p.142 / Chapter 4.4.1.1. --- In aquatic system --- p.142 / Chapter 4.4.1.2. --- In soil system --- p.143 / Chapter 4.4.2. --- Effect of initial PCP concentrations and amount of SMC --- p.144 / Chapter 4.4.2.1. --- In aquatic system --- p.144 / Chapter 4.4.2.2. --- In soil system --- p.147 / Chapter 4.4.3. --- Effect of pH --- p.149 / Chapter 4.4.3.1. --- In aquatic system --- p.149 / Chapter 4.4.3.2. --- In soil system --- p.150 / Chapter 4.4.4. --- Effect of incubation temperature --- p.150 / Chapter 4.4.4.1. --- In aquatic system --- p.150 / Chapter 4.4.4.2. --- In soil system --- p.152 / Chapter 4.4.5. --- Potential breakdown intermediates and products --- p.152 / Chapter 4.4.5.1. --- In aquatic system --- p.152 / Chapter 4.4.5.2. --- In soil system --- p.158 / Chapter 4.5. --- Microtox® assay of PCP --- p.159 / Chapter 4.5.1. --- In aquatic system --- p.159 / Chapter 4.5.2. --- In soil system --- p.160 / Chapter 4.6. --- Removal of PCP by the aqueous extract of SMC --- p.162 / Chapter 4.7. --- Optimization of removal of methyl-parathion --- p.164 / Chapter 4.7.1. --- Effect of incubation time --- p.164 / Chapter 4.7.1.1. --- In aquatic system --- p.164 / Chapter 4.7.1.2. --- In soil system --- p.165 / Chapter 4.7.2. --- Effect of initial methyl-paration concentrations and amount of SMC used --- p.165 / Chapter 4.7.2.1. --- In aquatic system --- p.165 / Chapter 4.7.2.2. --- I in soil system --- p.166 / Chapter 4.7.3. --- Effect of incubation temperature --- p.168 / Chapter 4.7.3.1. --- In aquatic system --- p.168 / Chapter 4.7.3.2. --- In soil system --- p.169 / Chapter 4.7.4. --- Potential breakdown intermediates and products --- p.169 / Chapter 4.7.4.1. --- In aquatic system --- p.169 / Chapter 4.7.4.2. --- In soil system --- p.170 / Chapter 4.8. --- Microtox® assay of Methyl-parathion --- p.173 / Chapter 4.8.1. --- In aquatic system --- p.173 / Chapter 4.8.2. --- In soil system --- p.174 / Chapter 4.9. --- Removal of methyl-parathion by the aqueous extract of SMC --- p.174 / Chapter 4.10. --- The ability of different types of SMC in the removal of organic pollutants --- p.176 / Chapter 4.11. --- The storage of SMC --- p.178 / Chapter 4.12. --- The effect of scale in the removal of pesticides --- p.180 / Chapter 4.13. --- Cost-effectiveness of using SMC as crude enzymes sources --- p.180 / Chapter 4.14. --- The effect of surfactant on the removal of PCP --- p.182 / Chapter 4.15. --- Prospects for employment SMC in removal of pollutants --- p.185 / Chapter 5. --- Conclusions --- p.186 / Chapter 6. --- Future investigation --- p.190 / Chapter 7. --- References --- p.192
36

Pesticide levels in agricultural drainage systems in Quebec

Bastien, Charlotte January 1991 (has links)
A study was conducted to measure pesticide concentrations from two tile-drained potato fields in Saint-Leonard d'Aston, Quebec. Soil and water samples were analysed for the pesticides metribuzin, fenvalerate and aldicarb in 1989, and for metribuzin and phorate in 1990. / Metribuzin concentrations up to 3.47 $ mu$g/l were detected in the tile drain water. Surface runoff samples had metribuzin concentrations up to 47.086 $ mu$g/l. Aldicarb was not detected in any of the water samples. Fenvalerate was detected in surface runoff at a level of 0.05 $ mu$g/l during the 1989 growing season. Phorate was not detected in subsurface drain water in the 1990 growing season. / Pesticide levels were higher in the surface soil layer (0-5 cm), than at 25 cm depth. Fenvalerate was detected at a level of 0.013 $ mu$g/g in the surface (0-5 cm) soil samples. Phorate concentrations of up to 0.020 $ mu$g/g were detected in soil samples. Aldicarb was not detected in the soil samples. Metribuzin was found mostly in the soil surface layer with concentrations of up to 0.23 $ mu$g/g during the 1990 growing season.
37

Towards integrated control of cotton pests in Guatemala : an economic analysis

Pira, Lars Henrik. January 1981 (has links)
No description available.
38

Modelling the behaviour and fate of priority pesticides in South Africa.

Maharaj, Simone January 2005 (has links)
The use of pesticides poses a serious threat to the limited water resources of South Africa. The amounts which are not taken up by crop plants, are often washed away by runoff into surface waters, or leached through the soil, causing groundwater pollution. The problem of pesticide pollution is often intensified by inappropriate usage, disposal and monitoring in agriculture and predictive models have proven to be an effective tool for improving management practices. Research, however, has focused mainly on surface water contamination and groundwater impacts are largely unknown. Furthermore, pesticide registration in South Africa is largely determined by international standards and there is a need for impact assessments to be carried out under local conditions. The aims of this study included the determination of priority pesticides in South Africa based on usage and properties, the determination of pesticide sorption in two selected South African soils, and an assessment of pesticide fate by modelling.
39

Die bepaling van sekere plaagdoderreste in die bloed van plaaswerkers op appelplase in die Elgin-distrik

Morren, Carel-Jan Hendrikus January 1994 (has links)
Thesis (Masters Diploma (Technology)--Cape Technikon, Cape Town,1994 / Pesticides are generally used in south-Africa for the control of various pests; from insects and fungi to weeds. The agricultural industry is probably the biggest user of pesticides and therefore workers in this part of the labour force have the biggest risk of being exposed to the hazards of these essential products. During the 1988/89 deciduous fruit season the deciduous fruit industry earned approximately R1000 million in foreign exchange. It is therefore very important for this industry to produce fruit of high quality in a very competitive market. Of the total deciduous exports, apples comprised approximately 62,5%. The EIgin-Grabouw area is the biggest producer of apples. This industry is clearly very dependant on pesticides to protect its crops against pests. From time to time farm - workers are exposed to pesticides, a study was therefore performed to access the levels of exposure of farm workers. Blood and urine samples were collected in a comprehensive biological monitoring program in the Elgin area to determine, uusing clinical tests, the level of exposure to pesticides. It was decided later that the determination of pesticide residues in blood would form part of this main study. Other tests included serum and red cell cholinesterase. Samples were collected during August (start of spraying season), November (midseason) and February (end of spraying season). A multi-residue method was developed to extract organophosphate and organochlorine pesticides in whole blood. Although various methods exist, they allow only for the extraction of either organophosphates or organochlorines and not multi-residue extractions. This multi-residue method is based on the liquid/liquid extraction of a blood/Celite/ethanol mixture to extract the following pesticides: Azinphos-methyl, Chlorpyrifos, Endosulfan, Methidathion and Prothiophos. The pesticide residue levels were determined on gas chromatographs equipped with DB-5 and DB-2I0 capillary columns and flame photometric-, electron capture- and nitrogen/phosphorous detectors. The results were confirmed on a gas chromatograph with mass-selective detector in selective ion mode. Of the 402 blood samples analysed, 23 samples showed positive for organophoshates and 29 for organochlorines, and were sent for analysis on the mass spectrometer. Of those samples only one could be positively identified. The presence of the pesticide Endosulfan-B was confirmed. The confirmation of the pesticides was complicated by interfering substances that leached from the rubber stoppers of the collection vessels into the blood. Although the study showed that for practical purposes no pesticides were present, other important information was obtained about the handling and analyses of blood samples for pesticides.
40

Avaliação dos níveis de pesticidas organoclorados em águas na região de Apucarana-PR usando a microextração em fase líquida com cromatografia gasosa acoplada à espectrometria de massa

Mikalouski, Flavianny Brencis da Silva 01 April 2015 (has links)
Dissertação composta por 3 artigos. / CAPES / O meio ambiente está em constante modificação, principalmente devido à influência antrópica. O monitoramento destes ambientes tem como objetivo caracterizar o meio, prever danos futuros e remediar possíveis impactos. No ambiente, as águas superficiais são dinâmicas, com constantes mudanças e crescente demanda, necessitando da garantia de qualidade para seu uso, realizada através de análises físico-químicas, microbiológicas e de compostos traço. Neste estudo, amostras de águas superficiais, de 12 pontos distintos da cidade de Apucarana-Paraná (Brasil), foram coletadas no período de um ano. As amostras foram submetidas às análises físico-químicas e microbiológicas, analisadas com base na quimiometria, a fim de demonstrar a influência do meio urbano e rural, e os fatores mais relevantes para a caracterização do ambiente. Considerando os ambientes de influência rural, foram analisadas a presença de pesticidas organoclorados, com a otimização do método de microextração líquido-líquido dispersiva, e uso instrumental da cromatografia gasosa acoplada a espectrometria de massa. Os dados apontam que os ambientes estão livres de contaminação e dentro dos padrões de aceitação, tanto para os parâmetros físico-químicos quanto microbiológicos. Os ambientes de interesse também apresentaram-se isentos de contaminação por pesticidas organoclorados no período de pesquisa. / The environment is constantly changing, mainly due to human influence. Environmental monitoring has object to environment, predict future damage and remedy potential impacts. Surface water is a dynamic medium, with constant changes and increasing demand, requiring quality assurance for their use, performed by physical-chemical, microbiological and analysis compounds traits. In this study, surface water samples of 12 different points of the city of Apucarana, Paraná (Brazil), were collected within one year. The samples were subjected to physical, chemical and microbiological analyzes, analyzed based on chemometrics in order to demonstrate the influence of urban and rural areas, and the most important factors to characterize the environment. Considering the influence of rural environments were analyzed the presence of organochlorine pesticides in the optimization of the method of liquid-liquid microextraction dispersive, and instrumental use of gas chromatography-mass spectrometry. Data indicates that the environments are free from contamination and within the acceptable standards for both the physical-chemical and microbiological parameters. The environments of interest also presented free of contamination by organochlorine pesticides in the research period. / 5000

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