.CONTRIBUTORS TO VOLUME 48 ´ ´ Rocıo Aguilar-Martınez Department of Analytical Chemistry, University Complutense of Madrid, Ciudad Universitaria, 28040 Madrid, Spain Ian Allan School of Biological Sciences, University of Portsmouth, King Henry I Street, Portsmouth PO1 2DY, UK David A. Alvarez US Geological Survey, Columbia Environmental Research Center, 4200 New Haven Road, Columbia, MO 65201, USA ´ Damia Barcelo Department of Environmental Chemistry, IIQAB-CSIC, Jordi Girona 18-26, 08034 Barcelona, Spain Michael E. Bartkow National Research Centre for Environmental Toxicology (ENTOX), University of Queensland, Coopers Plains, Queensland 4108, Australia Per-Anders Bergqvist ˚ Environmental Chemistry, Department of Chemistry, Umea ˚, University, SE-901.