Scavenging of thorium isotopes in the Arctic regions: Implications for the fate of particle-reactive pollutants

The sources of inorganic pollutants to the Arctic areas are reviewed using previously published results, The removal of particle-reactive pollutants is discussed using thorium scavenging as an analog. The scavenging of Th-234 from the upper water column (similar to 100 m) and sediment inventory of Th-230 from the deep Arctic waters is compared to different ocean basins in the subarctic areas. Such a comparison shows that Th-234 is in equilibrium with its parent, U-238, in certain regions of the Canada Basin of the Arctic Ocean, while it is deficient in other regions of the arctic as,veli as in sub-polar ocean basins. This implies that the particle-reactive pollutants in the deep Arctic of the Canada Basin are less likely to be removed from the deep waters and will eventually be transported out of this area, We have utilized the Th-230 inventory in sediments from the Arctic area to determine the removal rates of particle-reactive nuclides, The Th-230 inventory in the deep Arctic Ocean of the Canada Basin is much lower than the Norwegian Sea and the Fram Strait of the Arctic as well as all other sub-polar world oceans. These observations suggest that any pollutants into the deep Arctic areas of the Canada Basin are less likely to be removed locally and mag be transported out of this area. In those areas, the colloidal material could potentially play a major role in the removal of particle-reactive contaminants, (C) 2001 Elsevier Science Ltd. All rights reserved.