Transport of radionuclides by sea-ice and dense-water formed in western Kara Sea flaw leads

Ž 239,240 . A transport assessment of particle-bound and dissolved artificial radionuclides Cs and Pu by sea-ice and dense-water formed in western Kara Sea flaw leads close to the Novaya Zemlya dumping sites is presented in this study. We both performed a ‘‘best estimate’’ based on available data, and a ‘‘maximum assessment’’ relying on simulated constant 137 239,240 Ž . releases of 1 TBq Cs and Pu from individual dumping bays. The estimates are based on a combination of i the Ž . content of particulate matter in sea-ice; ii analytical data and numerical simulations of radionuclide concentrations in shelf Ž . Ž . surface deposits, suspended particulate matter SPM , and the dissolved phase; and iii estimates of lead-ice and dense-water formation rates as well as modeling results of local ice drift pathways. In the ‘‘best estimate’’ case, 2.90 GBq Cs and 0.51 GBq Pu attached to sea-ice sediments can be exported from the lead areas toward the central Arctic basin. The radionuclide burden of the annually formed dense lead water in the ‘‘best estimate’’ amounts to 4.68 TBq Cs and 0.014 TBq Pu. In the ‘‘maximum assessment’’, potential export-rates of ice-particle bound Cs and Pu toward the central Arctic would amount to 0.64 and 0.16 TBq, respectively. As much as f900 TBq Cs and f6.75 TBq 239,240 Ž . Pu could be annually taken up by 34.75 dense-water rejected in the lead area. Assuming the unlikely instantaneous 137 239,240 Ž . release of the total Cs and Pu inventories f1 PBq and 10 TBq, respectively from the Novaya Zemlya dumping sites into the dissolved phase, the dense lead water locally formed during one winter season could take up f90% of the Cs and f68% of the Pu released. q 2000 Elsevier Science B.V. All rights reserved.