Differentiation of organic matter's properties of the Rio Negro basin by crossflow ultra-filtration and UV-spectrofluorescence

Cross-flow ultra-filtration from the Rio Negro basin (Amazon) samples was u ndertaken with tangential flow equipment producing concentrated fractions o n which UV-fluorescence produced information about the individual character istics of the organic matter in different size fractions. The major novelty is that conductance (ionic strength) and fluorescence were both linearly ( r>0.95) correlated with total organic carbon (TOC) determined at each indiv idual station. The physico-chemical characteristics (fluorescent sensitivit y and electro-mobility) of the organic carbon seem to be constant within ea ch size fraction (particulate, colloidal and dissolved). The complexing cap acity of copper was found to be elevated, with as consequence that more tha n 80% of the metal transport occurred in the dissolved phase. By comparing these various results, we have deduced that the functional groups responsib le for complexation are not the same as those responsible for fluorescence and conductance. (C) 1999 Elsevier Science Ltd. All rights reserved.