title: Hydrological variation modulates pharmaceutical levels and biofilm responses in a Mediterranean river.
abstract: The Llobregat is a Mediterranean river that is severely impacted by anthropogenic pressures. It is characterized by high flow variability which modulates its chemical and biological status. The present work evaluates the effects of flow changes on the concentration of pharmaceutically active compounds (PhACs) and their relationship to cellular parameters of river biofilms. To this end, at two selected sampling sites at the lower course of the Llobregat river, surface water samples were collected twice a week over two hydrologically different periods exhibiting low and high river flows. Higher levels of PhACs were detected at the downstream sampling site. Irrespective of the flow regime, analgesics, anti-inflammatories and lipid regulators were the most abundant substances at both sampling sites with total concentrations of up to 1,000 ng/L and 550 ng/L at the upstream and downstream sites, respectively. Antibiotics (fluoroquinolones) and psychiatric treatment drugs were also detected at high levels in the second campaign achieving concentrations of up to 500 ng/L. The principal component analysis (PCA) performed with the PhACs concentrations of the two campaigns revealed differences in the various therapeutic groups depending on sampling site and period. After a flash flood event during the second sampling period, dilution of PhACs occurred, but their average concentrations measured before the flood were restored within two weeks. For the majority of compounds, PhAC concentrations displayed an inverse relationship with river discharge The effects of water containing different concentrations of PhACs on biofilm communities were evaluated and related to flow regime variations. Translocation of biofilm communities from a less to a more polluted site of the river demonstrated an increase in bacteria mortality in the translocated biofilms. After the flood, extracellular peptidase activity and chlorophyll-a concentration were significantly reduced, and biofilm growth rate was significantly lower.
authors.affiliation: IDAEA-CSIC, Jordi Girona 18-26, Barcelona, Spain.
authors.forename: Victoria
authors.initials: V
authors.lastname: Osorio
authors.affiliation: Institute of Aquatic Ecology, University of Girona, Girona, Spain.
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Proia
authors.affiliation: Institute of Aquatic Ecology, University of Girona, Girona, Spain.
authors.forename: Marta
authors.initials: M
authors.lastname: Ricart
authors.affiliation: IDAEA-CSIC, Jordi Girona 18-26, Barcelona, Spain. Electronic address: spsqam@idaea.csic.es.
authors.forename: Sandra
authors.initials: S
authors.lastname: Pérez
authors.affiliation: IDAEA-CSIC, Jordi Girona 18-26, Barcelona, Spain.
authors.forename: Antoni
authors.initials: A
authors.lastname: Ginebreda
authors.affiliation: Cetaqua, Water Technology Centre, UPC North Campus, Paseo de los Tilos, 3, Barcelona, Spain.
authors.forename: Jose Luís
authors.initials: JL
authors.lastname: Cortina
authors.affiliation: Institute of Aquatic Ecology, University of Girona, Girona, Spain; Catalan Institute for Water Research (ICRA), Scientific and Technological Park of the University of Girona, Emili Grahit 101, Girona, Spain.
authors.forename: Sergi
authors.initials: S
authors.lastname: Sabater
authors.affiliation: IDAEA-CSIC, Jordi Girona 18-26, Barcelona, Spain; Catalan Institute for Water Research (ICRA), Scientific and Technological Park of the University of Girona, Emili Grahit 101, Girona, Spain.
authors.forename: Damià
authors.initials: D
authors.lastname: Barceló
mesh_terms: D018441:Biofilms / Q000254:growth & development*; D004784:Environmental Monitoring; D062070:Hydrology; D019083:Mediterranean Region; D004364:Pharmaceutical Preparations / Q000032:analysis*; D045483:Rivers / Q000737:chemistry*; D014872:Water Movements; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D004364:Pharmaceutical Preparations; D014874:Water Pollutants, Chemical
keywords: Biofilms; Hydrological variation; Pharmaceuticals; River