CETA ESTUDIOS TENDIENTES A ESTABLECER EL COMPORTAMIENTO...
Tres Arroyos area is located Southwest Buenos Aires province. In this area, intensive agricultural practices take place with high yields of winter cereals and oilseeds. Anually, large\namounts of different plaguicides are employed, including organophosphates, in particular, chlorpyrifos. The effect...
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| Formato: | Tesis doctoral acceptedVersion |
| Lenguaje: | Español Inglés |
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Universidad de Buenos Aires. Facultad de Ciencias Veterinarias
2015
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| Acceso en línea: | http://repositoriouba.sisbi.uba.ar/gsdl/cgi-bin/library.cgi?a=d&c=avaposgra&cl=CL1&d=HWA_1343 https://repositoriouba.sisbi.uba.ar/gsdl/collect/avaposgra/index/assoc/HWA_1343.dir/1343.PDF |
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| Sumario: | Tres Arroyos area is located Southwest Buenos Aires province. In this area, intensive agricultural practices take place with high yields of winter cereals and oilseeds. Anually, large\namounts of different plaguicides are employed, including organophosphates, in particular, chlorpyrifos. The effect of insecticides has been studied worldwide because of the great\nconcern with the effects that many of these compounds have on non- target organisms and the\nimpact they can have on water quality. The organisms that live in water bodies located in agricultural zones can be affected by chlorpyrifos and other organophosphate plaguicides at the nervous system level and other metabolic pathways. There are several studies on\nchlorpyrifos in Argentina but none in our study zone. Also, no studies have been performed regarding its behavior on solid matrices (soils, sediments) characteristic of our region.\nUnderstanding dissemination and behavior of this insecticide is crucial to assess its impact and final fate on the environment. In this thesis, studies of interaction and recovery of\nchlorpyrifos, pure and in commercial formulations, on solid matrices with different\nphysicochemical characteristics have been performed. In addition, half-life times have been\nevaluated on soils with different initial concentrations of chlorpyrifos. In aquatic\nenvironments of Tres Arroyos district, physicochemical analysis of water was conducted and\nconcentrations of nutrients (nitrate, phosphate) and chlorpyrifos were assessed and associated with local agricultural practices. Sediments and aquatic biota have been analyzed\nfor chlorpyrifos. The responses of Rhinella arenarum larvae exposed for up to 96 hours to water samples from Claromecó and Tres Arroyos have been studied. To complete these\nstudies, an assessment of the risk that this insecticide could create at the concentrations found\nin the study area was carried on. Studies of behavior on solid matrices show that recoveries of pure chlorpyrifos (98%)\nare lower on matrices with high organic matter contents and low pH. Recoveries depend on the initial concentrations applied. When a commercial formulation (48% chlorpyrifos) was\nassayed, recovery percentages increased with the initial concentration of up to 25 ppm. When\nconcentrations higher than 25 ppm were employed, recovery started to decrease. Half-time\nlifes of 15 and 6 days were determined for initial concentrations of 3 and 6 ppm of chlorpyrifos when persistence on an agricultural soil of Buenos Aires province was studied. In both cases degradation was 99,9 % after 21 days.\nWhen water and sediments from aquatic environments of Tres Arroyos where\nanalyzed for chlorpyrifos, seasonal variations were observed related to crops. The highest concentrations in water were observed in 2009, in winter and summer campaigns. Concentrations of chlorpyrifos in sediments were hard to relate to seasonal variations.\nIn the analysis of chlorpyrifos on local biota, results from Australoheros facetus\n(?chanchita?), Oligosarcus jenynsii (?dientudo?), Rhamdia quelen (?bagre sapo?), Mugil sp.\n(?lisa?) y Cyrtograpsus angulatus (?cangrejo de las rocas?) showed dependence in concentration of chlorpyrifos with the type of tissue and its lipid content. In all species, higher\nconcentrations were observed in brain, liver and gonads. In O. jenynsii and A. facetus, males were twice as contaminated as females, while in R. quelen, the opposite was observed. On the other hand, the highest concentrations were found in specimens of R. quelen and A. facetus, species that live near the bottom of streams. C. angulatus (cangrejo de las rocas) exhibited\nchlorpyrifos values up to 157 times smaller than fish species and did not show differences between males and females. Biochemical biomarkers responses on Rhinella arenarum larvae suggested that, even\nwhen water samples contained chlorpyrifos traces, primary target AChE was not affected.\nNevertheless, significant responses of CE, GST and GSH were obtained together with a strong antioxidant response of CAT, though we cannot rule out the influence of other pollutants not\ndetected in chemical analysis. In the assessment of nutrient (nitrate, phosphate) levels in water, we concluded that\nthey depend on a number of factors and are hard to predict. Nitrate levels did not vary significantly between winter and summer campaigns. On the other hand, phosphate\nconcentrations were extremely high all year round with maximums in spring and summer. Risk assessment revealed high levels of acute and chronic risk for some species of\naquatic invertebrates and vertebrates and potential risk for local population health.\n |
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