title: Effects of UV-visible irradiation on natural organic matter from the Amazon basin.
abstract: The aim of this work was to evaluate the effects of UV-visible irradiation on organic carbon concentration, fluorescence intensity and metal transport ability of the natural organic matter (NOM) at fixed pH values and under several types of atmosphere (air, N(2), O(2)). The water samples were obtained from various sampling sites along the Rio Negro (Amazon basin) and the NOM metal transport ability was determined with regard to Cu(2+). As a first step we measured the concentration of total organic carbon (TOC) and its fluorescence intensity before and after an irradiation for a given time. The results demonstrated that when photodegradation happened, the dominant reactions involved O(2) and the fluorescent sites were among the first to be altered. Then we determined by spectrofluorometry the complexing capacity (C(L)) before and after irradiation. Fluorescence and complexing site densities (C(L)/TOC ratio) increased after a short irradiation time (20 min, i.e. before the photodegradation happened) and decreased after longer irradiation times. Therefore, we conclude that a change of the macromolecular structure activates previously inactive fluorophores and complexing sites prior to photodegradation.
authors.affiliation: Laboratoire de Recherche en Chimie Marine des Organométalliques, Université de Toulon et du Var, B.P. 132, 83957 La Garde Cedex, France. patel@univ-tln.fr
authors.forename: N
authors.initials: N
authors.lastname: Patel-Sorrentino
authors.forename: S
authors.initials: S
authors.lastname: Mounier
authors.forename: Y
authors.initials: Y
authors.lastname: Lucas
authors.forename: J Y
authors.initials: JY
authors.lastname: Benaim
mesh_terms: D000388:Air; D001938:Brazil; D003300:Copper / Q000737:chemistry*; D005453:Fluorescence; D006863:Hydrogen-Ion Concentration; D009584:Nitrogen; D009930:Organic Chemicals / Q000032:analysis* / Q000528:radiation effects*; D010100:Oxygen; D045483:Rivers / Q000737:chemistry*; D013050:Spectrometry, Fluorescence; D013997:Time Factors; D014466:Ultraviolet Rays
chemical_list: D009930:Organic Chemicals; D003300:Copper; D009584:Nitrogen; D010100:Oxygen