Complejación de metales por sustancias húmicas acuáticas como proceso natural, tomando como caso de estudio el Lago de Xochimilco

22 This work discusses the importance of organic matter, specifically Aquatic Humic Substances (SHA) 23 within the speciation and distribution of metals within an aquatic system, in this case Xochimilco 24 Lake, a site with great ecological importance. This lake is the natural habitat of the endemic species 25 “axolotl” (ajolote). In this research, complexation reactions between SHA and metals (Cu, Mn, Pb 26 and Zn) were carried out under different reaction conditions, the source of AHS was water samples 27 taken in Xochimilco Lake in presence and absence of pH buffer dissolution and varying the 28 concentration of metals. The results show that there is a direct competition between the major 29 elements and trace elements to react with the AHS. Under the pH conditions of Xochimilco Lake 30 complexes formation is possible. 31

INFLUENCE OF THE DIAMETER OF NANOPARTICLES IN COMPLEXES METAL-AQUATIC HUMIC SUBSTANCES

Nanoparticles are emerging as the object of research in all fields of chemistry, their special properties are matter for concern, because a considerable portion of these materials are eliminated in the environment. A key point of the discussion is how nanoparticles will interact with other components in natural waters. In this project, the main objective will be to study the interactions of nanoparticles with metallic ions in the presence of humic substances in environmental systems. It is intended to differentiate free and labile metal ions using nanoparticles and organic matter in the form of aquatic substances (extracted from samples collected on the coast of São Paulo). It is intended to simulate the environmental systems and to verify the competition between the complexants. The differentiation of the free and complexed ions will be done using an ultrafiltration system equipped with polyethersulfone membrane (1KDa) and determination of the metals by atomic absorption spectrometry with flame atomization and graphite furnace.