Optical properties of the Kara Sea

This study was motivated by the need to understand dispersion processes whi ch affect the redistribution of nuclear wastes in the Arctic from dump site s in the Kara Sea and in the rivers which flow into the Kara Sea. We focus on vertical profiles of light beam transmission and fluorometry made over t he delta region fronting the Ob and Yenisey Rivers and over the East Novaya Zemlya Trough (ENZT). The delta region fronting the Ob River Estuary conta ins a large repository of particles in a dense bottom nepheloid layer with a maximum centered similar to 100 km in front of the estuary entrance and c overing an area of roughly 200 km diameter. This suspended particle mass re pository appears to contain both sediments and detritus and lends credence to the Lisitsyn [1995] concept of the marginal filter zone. In the deep wat er of the ENZT we found a strong increase of beam attenuation with depth, i ndicating a relatively large increase of particle mass concentration from s imilar to 50 m to the bottom (depths in excess of 300 m). The strongest con centration was adjacent to the southeast coast of Novaya Zemlya. We suggest that a type of hyperpycnical flow occurs from accumulation of sediments in the bottom waters of Novaya Zemlya fjords which then cascades down the ste ep slopes adjacent to the island, producing the particle mass distribution as observed by the transmissometer. The accumulation of these repositories of high particle mass concentrations in suspension would suggest that the r esidence time is high but that storm-driven events could act to disperse th e material.