The dissolved organic matter in rivers has different origin and its composition can vary both by natural conditions and the anthropic activity that takes place near rivers. This mobile fraction of the organic matter is composed of sub-fractions of different molecular weight and polarity, which confer different complexing capacity for the pollutants and thus a different impact on the environment. The aim of this study was to isolate and characterize the organic matter dissolved in a representative basin of a temperate zone in South America, such as Bio Bio River located in the VIII region of Chile. The material was characterized chemically and spectroscopically after fractionating by molecular weight and polarity. It is concluded that the dissolved organic matter of the Rucalhue sector has a terrestrial origin, with a high aromatic carbon content, in contrast with that from Laja and Concepción, which has a greater anthropic impact. The dissolved organic matters from the sectors with high anthropic activity have larger molecular size and higher organic carbon content and conductivity.

O objetivo deste estudo foi utilizar a técnica de difusão em filmes finos por gradiente de concentração (DGT) para a avaliação da disponibilidade de cobre em solos com elevados níveis do metal, que foi alterado com biossólidos, além de comparar esta técnica com procedimentos de extração simples e sequenciais, considerando a extractabilidade do metal. A ordem de importância das frações de cobre no solo foi: residual > reduzida > oxidável > solúvel. A aplicação do biossólido diminuiu as frações solúvel e reduzida, bem como aumentou a quantidade de metal associada à fração oxidada. A quantidade de cobre extraída por DGT da solução de solo foi 13% do metal total em solução. No caso do solo, esse valor foi inferior a 0,3% do total do metal. Também relacionou-se diretamente o metal extraído por DGT com o metal disponível com CaCl2 ou o metal ligado à matéria orgânica do solo.

The aim of this study was to use the technique of diffusion gradients in thin films (DGT) to evaluate the availability of copper in soil with high presence of this metal treated with biosolids, and to compare this technique, in terms of metal extractability, with simple and sequential extraction procedures. The order of importance of the copper fractions in the soil was: residual > oxidizable > reducible > soluble. Biosolid application decreased of both soluble and reducible fractions and increased the amount of metal attached to the oxidizable fraction. Copper amount extracted by DGT from the soil solution was 13% of total metal in solution. In the case of soil, this amount was less than 0.3% of total metal. Furthermore, it was possible to directly relate the metal extracted by DGT with the available metal with CaCl2 or the metal bound to organic matter.