Pathways and mean residence times of dissolved pollutants in the ocean derived from transient tracers and stable isotopes

During the past decades, a variety of transient tracers have been used to derive information on pathways and mean residence times of oceanic water masses. Here, we discuss how information obtained in such studies can be applied to studying the spreading of dissolved pollutants in the ocean. The discussion focuses on the transient tracers tritium/He-3 and the (H2O)-O-18/(H2O)-O-16 ratio of water. These tracers are used in combination with CFCs and C-14 in a case study of Arctic Ocean contaminant transport to: (1) separate the freshwater components contained in the near-surface waters; (2) infer mean pathways of freshwater and associated contaminants from the (H2O)-O-18/(H2O)-O-16 distribution in the surface waters; and (3) determine mean residence times of the surface, intermediate, deep and bottom waters. (C) 1999 Elsevier Science B.V. All rights reserved.