The Role of Ice Cover in the Formation of Bottom Sediment Chemical Composition on the East Siberian Shelf

Transfer functions for reconstruction of the duration of ice-free period at stations in the Chukchi, East Siberian and Laptev seas have been developed by comparison of hydrometeorological data and the chemical composition of bottom sediments accumulated during observation period. It has been established that in addition to the previously discussed processes through which the ice cover affects the chemical composition of bottom sediments (primary bioproductivity and redox conditions of bottom waters), there are several mainly local processes developed on the East Siberian shelf. These are the changes of terrestrial aqueous and solid runoff; coastal abrasion rate; current structure and water exchange through the Bering Strait between the Pacific and Arctic oceans; and intensity and direction of the ice/iceberg rafting of sediments. It is shown that some typical elements (Br, Ca, As, Fe, Ga) can be used as universal geochemical proxies for qualitative reconstruction of ice conditions.