1. Horn Point Laboratory; University of Maryland Center for Environmental Science; P.O. Box 775 Cambridge MD 21613 USA
2. Plymouth Marine Laboratory; Prospect Place The Hoe, Plymouth PL1 3DH UK
3. PBL Netherlands Environmental Assessment Agency; PO Box 303 Bilthoven 3720 AH The Netherlands
4. Department of Earth Sciences, Geochemistry, Faculty of Geosciences; Utrecht University; P.O. Box 80.021 Utrecht 3508 TA The Netherlands
5. Natural Environmental Research Council; National Oceanography Centre; Joseph Proudman Building, 6 Brownlow St. Liverpool L3 5DA UK