River Dominated Margins are extremely dependent not just on the nutrients input, but also on carbon transport from the rivers. Some research estimates the amount of the carbon export with the largest rivers runoff as 5.42×10⁸ tC/year for export carbon straight from the Atmosphere, and consumption of total atmospheric carbon within the rock weathering processes as 4×10⁸ tC/year.
During our expeditions in the June of 2005, 2006 and August of 2016 we had been studying the hydrochemical conditions of the Lower reaches of Amur River to understand the scale of Carbonate system processes within the Amur River Basin. In these expeditions about 13 hydrochemical stations along the Lower reaches have been made. In 2016 estuary of the Amur River also has been observed. Within those expeditions pH, TA, HS (Humic Substances) parameters additionally with major ions (Na+, K+, Ca²+, Mg²+, Cl-, SO4²-) and DOC were measured.
In the study we have find that Amur River Basin it's abundant sink of the carbon dioxide from the Atmosphere. Photosynthesis and rock weathering processes play an important role in the sinking of CO2. These processes are responsible for the total carbon export by the Amur River to the Amur Estuary which is equal to 3.8×10⁶ tC/year. Simultaneously Amur River Basin is prominent source of the CO2 emissions to the Atmosphere, which are equal to 4.5×10⁶ tC/year. The Amur River emissions of carbon dioxide are sufficiently exceeded the Amur River waters carbon runoff. We have assumed several reasons for this situation. One of that processes which could have a significant impact is microbiological oxidation of the organic matter. Additionally the methane generation in the bottom sediments of the Amur River Basin water bodies could be expected. In the course of the study, we also established that the alkalinity runoff of the Amur River (equal to 1.65×10¹¹ mol/year) affects the northern part of the surface sea waters of the Sea of Japan and the Sea of Okhotsk near the coast of Sakhalin Island in relation to the normalized total alkalinity (Tishchenko et al., 2025).

Tishchenko P.Ya., Zvalinsky V.I., Pavlova G.Yu., Tishchenko P.P., Chichkin R.V., Shkirnikova E.M., and Anokhina R.S. Export and emission of carbon dioxide by downstream of Amur River // WATER RESOURCES, 2025, Vol. 52, No. 2, рр. 102–114

Amur River,Amur Estuary,Carbonate system,carbon dioxide emissions,Sea of Japan,Sea of Okhotsk