This special volume includes 14 papers on oceanography, biogeochemical processes, climate change, marine contamination and ecotoxicology by researchers from Spain and Portugal. The papers were presented at the XIV Seminario Ibérico de Química Marina which was held in Cadiz from 22 to 24 September 2008. The seminars began more than 25 years ago, and 2008 was the 14th edition as a consolidated, multidisciplinary scientific meeting. Every two years a representative number of marine scientists meet with the aim of advancing our current knowledge of all aspects of marine chemistry.