1. Unidade de Geologia Marinha; Laboratório Nacional de Energia e Geologia; Apartado 7586,; P-2721-866; Amadora; Portugal
2. Environmental Research Division; SWFSC, NMFS, NOAA; 1352 Lighthouse Avenue,; Pacific Grove; California; 93950-2097; USA
3. Department of Environmental Chemistry; Institute of Environmental Assessment and Water Research, CSIC; Jordi Girona, 18,; E-08034; Barcelona, Catalonia; Spain
4. Climatic Research Unit; University of East Anglia; Norwich; NR2 4HG; UK