The influence of organic matter from swine wastewater on the interaction and transport of alachlor in soil/Influencia da materia organica proveniente de agua residuaria de suinocultura na interacao e transporte do alaclor no solo

This study evaluated the effects of total and dissolved organic matter produced from two swine wastewater treatment systems, a biodigester and a manure lagoon, on the adsorption, desorption, and leaching of alachlor (2-chloro-N-(2,6-diethylphenyl)-N-(methoxymethyl)acetamide) in soil. It was used the batch equilibrium method to test adsorption and desorption, and the results are presented in Freundlich isotherms. It also used disturbed soil columns to evaluate the miscible displacement of alachlor in soil treated with total and dissolved organic matter. This assay was used to monitor the concentration of alachlor in the leached material, the amount of total organic carbon, and the pH. The addition of swine wastewater promoted greater adsorption and desorption of alachlor compared with the control. The dissolved organic matter promoted less soil adsorption of alachlor compared with the total organic matter and also interacted with the alachlor and/or competed with the exchangeable cation sites in the soil, resulting in greater leaching. The total organic matter contributed to the emergence of new sorption sites in the soil column, and the solids present in the composition may have blocked pesticide passage, resulting in lower loss of alachlor due to leaching. Keywords: adsorption, hydro-dispersive parameters, infrared spectroscopy, leaching, pesticide. Este trabalho avaliou o efeito da aplicagao de materia organica total e dissolvida proveniente de dois sistemas de tratamento de agua residuaria de suinocultura, biodigestor e esterqueira, na adsorcao, dessorcao e lixiviacao de alaclor (2-cloro-2,6-dietil-N(metoximetil acetamida)) no solo. O metodo do equilibrio foi utilizado para o teste de adsorcao e dessorcao e os resultados foram apresentados em isotermas de Freundlich. Utilizou-se tambem colunas de solo deformado para avaliar o deslocamento miscivel do alaclor no solo tratado com materia organica total e dissolvida. Este ensaio foi realizado para monitorar a concentracao de alaclor no lixiviado, o teor de carbono organico total e o pH. A adicao de agua residuaria de suinocultura promoveu maior adsorcao e dessorcao do alaclor comparado ao controle. A materia organica dissolvida promoveu menor adsorcao de alaclor ao solo comparada a total e tambem interagiu com o alaclor e/ou competiu com os sitios sortivos do solo, resultando em maior lixiviacao. A materia organica total contribuiu com o surgimento de novos sitios de sorcao na coluna de solo e os solidos p