Galina A Pavlova

Biogeochemical processes in the Chukchi Sea

Study of biogeochemical processes in water and sediments of the Chukchi Sea in August 2004 revealed atypical maximums of the concentration of biogenic elements (N, P, and Si) and the rate of microbial sulfate reduction in the surface layer (0–3 cm) of marine sediments. The C: N: P ratio in the organic matter (OM) of this layer does not fit the Redfield-Richards stoichiometric model. Specific features of biogeochemical processes in sea are likely related to the complex dynamics of water, high primary productivity (110–1400 mg C/(m2 day)), low depth of basin (<50 m in 60% of the water area), reduced food chain due to low population of zooplankton, high density of zoobenthos (up to 4230 g m−2), and high activity of microbial processes. Drastic decrease in the concentration of biogenic elements, iodine, total alkalinity (Alk), and population of microorganisms beneath the 0–3 cm layer testify to a large-scale OM decay at the water-seafloor barrier. Our original experimental data support the high annual rate of OM mineralization at the bottom of the Chukchi Sea.

Early diagenesis in recent bottom sediments of the Dvina Bay (White Sea)

Investigations in the water column and bottom sediments including entrapped water were carried out on expeditions of the P.P. Shirshov Institute of Oceanology in the Dvina Bay, the White Sea. We studied the transformation of particulate organic matter at the biogeochemical barrier between the water and bottom and in the underlying Holocene sediments. Low rates of the early diagenesis of sediments caused by low values of primary production in the conditions of high fluxes of terrigenous organic matter were established. The low temperatures of microorganisms habitat play the secondary role.