Sorção, dessorção e lixiviação do ametryn e fitorremediação do picloram em solos brasileiros

• Autor(a) principal: Silva, Leandra de Oliveira Cruz da
• Data de Publicação: 2011
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/212
• topic: Herbicida; Persistência no solo; Impacto ambiental; Herbicide; Persistence in soil; Environmental impact; CNPQ::CIENCIAS EXATAS E DA TERRA::QUIMICA::QUIMICA ANALITICA

Chemical control of weeds has become indispensable practice in large scale agriculture. However, the use of herbicides without the basic knowledge of their interactions with soil and climate is a high risk of environmental contamination and biodiversity loss. The objective of this study was to evaluate the processes of sorption, desorption and leaching of ametryn and phytoremediation of picloram in Brazilian soils. To this end, in a first step, several experiments were conducted to evaluate the sorption, desorption and leaching of ametryn in Red-Yellow Latosol (LVA), Red-Yellow humic Latosol (LVAh), Red Latosol (LV) and Yellow Latosol (LA), with different pH values, and to compare the chromatographic method with the biological in studies of the mobility of this herbicide. In another experiment was evaluated the half-life of picloram in two soils {Red-Yellow Ultisol (PVA) and Red- Yellow Latosol (LVA)}, cultivated or not with remediating species (Eleusine coracana). Organic matter content and soil pH affected the sorption, desorption and leaching of ametryn. Soils with higher organic matter content and lower pH values had higher rates of sorption, decreased mobility and smaller percentages of desorption, indicating the occurrence of hysteresis. The results of the chromatographic method were confirmed by the biological method (bioassay), proving that this technique was efficient as a primary method or complementary to the chemical method in confirmation of results and/or reduction of costs and time of analysis. The persistence of picloram in soils varied depending on the chemical characteristics of soils (half-lives of 99 and 151 days for the LVA and PVA, respectively). The species E. coracana was effective for remediation of soils contaminated with picloram. The cultivation of the species decreased by 56.6% and 49% of the time in days to reach the half-life of picloram in LVA and PVA, respectively, compared with soils without cultivation.