title: Assessing Transformations of Algal Organic Matter in the Long-Term: Impacts of Humification-Like Processes.
abstract: Algae and cyanobacteria are important contributors to the natural organic matter (NOM) of eutrophic water resources. The objective of this work is to increase knowledge on the modifications of algal organic matter (AOM) properties in the long term to anticipate blooms footprint in such aquatic environments. The production of AOM from an alga (Euglena gracilis) and a cyanobacteria (Microcystis aeruginosa) was followed up and characterized during the stationary phase and after one year and four months of cultivation, in batch experiments. Specific UV absorbance (SUVA) index, organic matter fractionation according to hydrophobicity and apparent molecular weight were combined to assess the evolution of AOM. A comparison between humic substances (HS) mainly derived from allochthonous origins and AOM characteristics was performed to hypothesize impacts of AOM transformation processes on the water quality of eutrophic water resources. Each AOM fraction underwent a specific evolution pattern, depending on its composition. Impacts of humification-like processes were predominant over release of biopolymers due to cells decay and led to an increase in the hydrophobic compounds part and molecular weights over time. However, the hydrophilic fraction remained the major fraction whatever the growth stage. Organic compounds generated by maturation of these precursors corresponded to large and aliphatic structures.
authors.affiliation: EA 4330 Groupement de Recherche Eau, Sol, Environnement (GRESE), Ecole Nationale Supérieure d\'Ingénieurs de Limoges (ENSIL), University of Limoges, Parc d\'ESTER Technopôle, 16 rue Atlantis, Limoges Cedex F-87068, France. maud.leloup@ensil.unilim.fr.
authors.forename: Maud
authors.initials: M
authors.lastname: Leloup
authors.affiliation: EA 4330 Groupement de Recherche Eau, Sol, Environnement (GRESE), Ecole Nationale Supérieure d\'Ingénieurs de Limoges (ENSIL), University of Limoges, Parc d\'ESTER Technopôle, 16 rue Atlantis, Limoges Cedex F-87068, France. virginie.pallier@ensil.unilim.fr.
authors.forename: Virginie
authors.initials: V
authors.lastname: Pallier
authors.affiliation: EA 4330 Groupement de Recherche Eau, Sol, Environnement (GRESE), Ecole Nationale Supérieure d\'Ingénieurs de Limoges (ENSIL), University of Limoges, Parc d\'ESTER Technopôle, 16 rue Atlantis, Limoges Cedex F-87068, France. rudy.nicolau@ensil.unilim.fr.
authors.forename: Rudy
authors.initials: R
authors.lastname: Nicolau
authors.affiliation: EA 4330 Groupement de Recherche Eau, Sol, Environnement (GRESE), Ecole Nationale Supérieure d\'Ingénieurs de Limoges (ENSIL), University of Limoges, Parc d\'ESTER Technopôle, 16 rue Atlantis, Limoges Cedex F-87068, France. feuillade@ensil.unilim.fr.
authors.forename: Geneviève
authors.initials: G
authors.lastname: Feuillade-Cathalifaud
mesh_terms: D005591:Chemical Fractionation; D005056:Euglena gracilis / Q000737:chemistry / Q000254:growth & development / Q000378:metabolism*; D005068:Eutrophication; D006812:Humic Substances / Q000032:analysis; D057927:Hydrophobic and Hydrophilic Interactions; D046931:Microcystis / Q000737:chemistry / Q000254:growth & development / Q000378:metabolism*; D009930:Organic Chemicals / Q000032:analysis* / Q000378:metabolism
chemical_list: D006812:Humic Substances; D009930:Organic Chemicals
keywords: XAD fractionation; algae; cyanobacteria; organic matter; size fractionation; transformation processes