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The isotopic composition (13C and 15N) and C:N ratio of sediment and particulate were investigated to assess the origin and dynamic of the organic matter in two river basins located in the Parana State, Brazil. The main sources of organic matter, plants, litter and soil, were analyzed in the study. This study was carried out during the dry and wet seasons. Although organic matter contribution for the particulate material has been mixed, the main contribution in the two seasons for both rivers was autochthonous characterized by delta13C and C:N ratio values ranging from -31.0 to -21.8 per thousand and from 5.1 to 11.4, respectively. The soil with delta13C values ranging from -25.9 to -20.6 per thousand, and C:N ratio from 10.2 to 15.8, was the main carbon source for the river sediment for the two tributaries in the wet and dry seasons. The sediment delta15N values for both the rivers in the wet season showed an 15N enrichment trend in most of studied sites when compared to the dry season values, suggesting major input of nutrients as dissolved organic nitrogen and sewage nitrate. In the dry season, 14N enriched compounds, could have been used by phytoplankton, causing 15N enrichment. The isotope and C:N ratio data clearly showed that the agricultural activity has been influencing the origin and dynamic of organic matter in the two rivers, with potential biochemical consequences for the lower basin of the major Tibagi river.

RESUMOand total suspended solids (TSS). Besides the simple installation and operation, the technique was efficient in the recovery of this type of effluent and can be used in reuse system carwash water.

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ResumoO processo de lavagem de solo com substâncias tensoativas, Lauril éter sulfato de sódio (LESS) e Lauril sulfato de sódio (SDS), foi combinado à oxidação química utilizando peróxido de hidrogênio, com vistas à remediação in situ de solo argiloso contaminado com hidrocarbonetos de petróleo. A avaliação da eficiência do processo baseou-se na remoção dos hidrocarbonetos poliaromáticos e na comparação das características físicas e químicas do solo contaminado e não-contaminado oriundos da mesma região. A combinação dessas duas técnicas, lavagem do solo e aplicação de agente oxidante, apresentouse como processo de remediação eficaz para solos argilosos contaminados com derivados de petróleo em regiões subtropicais. Palavras-chave: Lavagem de Solo. Fluorescência. Agente Oxidante. Óleo Bruto. Hidrocarbonetos Poliaromáticos. AbstractThe process of washing soil with surfactants, sodium lauryl ether sulphate (LESS) and sodium lauryl sulphate (SDS) was combined with chemical oxidation using hydrogen peroxide, with a view to in situ remediation of clay soil contaminated with hydrocarbons oil. The evaluation of the efficiency of the procedure was the removal of polyaromatic hydrocarbons and the comparison of physical and chemical characteristics of contaminated soil and uncontaminated from the same region. The combination of these two techniques, soil washing and application of an oxidizing agent, presented as a process of effective remediation for soils contaminated with petroleum products in subtropical regions.