Grain-size, mineral and chemical compositions of suspended particulate matter (SPM) from waters of the Severnaya (North) Dvina River mouth area during the spring flood in May 2004 is studied. Data published on composition of riverine SPM in the White Sea basin are very poor. The spring flood period when more than half of annual runoff is supplied from the river to the sea in during short time is understood more poorly. The paper considers comparison results of the grain size compositions of SPM and bottom sediments. Data of laser and hydraulic techniques of grain size analysis are compared. Short-period variations of SPM concentration and composition representing two diurnal peaks of the tide level are studied. It is found that SPM is mainly transferred during the spring flood as mineral aggregates up to 40 µm diameter. Sandy-silty fraction of riverine SPM settles in delta branches and channels, and bulk of clay-size material is supplied to the sea. Mineral and chemical compositions of SPM from the North Dvina River are determined by supply of material from the drainage basin. This material is subjected to intense mechanic separation during transfer to the sea. Key regularities of formation of mineral composition of SPM during the flood time are revealed. Effect of SPM grain size composition on distribution of minerals and chemical elements in study in the dynamic system of the river mouth area are characterized.

Supplement to: Kravchishina, Marina D; Shevchenko, Vladimir P; Filippov, Alexander S; Novigatsky, Alexander N; Dara, O M; Alekseeva, Tatyana N; Bobrov, Vyacheslav A (2010): Composition of the suspended particulate matter at the Severnaya Dvina River mouth (White Sea) during the spring flood period. Translated from Okeanologiya, 2010, 50(3), 396-416, Oceanology, 50(3), 365-385