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[References: p. 81 (50 tit.)]

This report presents the results of studies of the sea water carbonate system performed in September 2011 at the inner, middle, and outer shelf of the east of the Laptev Sea. It was shown that the key factor controlling the carbonate chemistry of the shelf waters during the warm season is the significant terrigenous runoff. In the autumn season, the surface waters of the inner and middle shelf of the eastern part of the Laptev Sea are a source of carbon dioxide to the atmosphere; those of the outer shelf act as a sink of atmospheric CO2. It is found that the waters of the inner shelf of the east of the Laptev Sea over the entire water column are now corrosive against calcium carbonate. The surface and near-bottom waters of the middle shelf are also undersaturated with respect to aragonite. It was shown that the main factors determining the undersaturation are the significant volume of freshwaters supplied with the riverine runoff and the ice melting, as well as the large amount of labile allochthonous organic matter involved into the modern biogeochemical cycle at the shelf. The performed studies showed that the shelf waters of the eastern part of the Laptev Sea constitute one of the most corrosive zones with respect to calcium carbonate in the World Ocean.