Export and Emission of carbon dioxide by downstream of Amur River

Measurements of pH, total alkalinity, humic substances were carried out in June 2005, 2006 in the waters of the downstream Amur River along distance 489 km on the 13 hydrochemical stations between the cities of Komsomolsk-on-Amur and the Nikolaevsk-on-Amur. In August 2016, hydrochemical observations were carried out at the mouth Amur River, which included measurements of pH, total alkalinity, humic substances, concentrations of major ions of river water (Na+, K+K+, Ca2+, Mg2+, Cl–Cl–) and dissolved organic carbon. The average annual rate of chemical weathering in the Amur River basin has been established which equal to 10.7 t/(km2 year). Weathering of rocks and producing of organic matter by photosynthesis lead to the consumption of the atmospheric CO2 in the river basin. Amur River annually exports this atmospheric CO2 into the marine environment equaled to . It has been established that the Amur River waters annually emit of carbon dioxide to the atmosphere. The balance of opposite processes (CO2 export and CO2 emission) showed that the ecosystem of the Amur River is a weak source of carbon dioxide to the atmosphere. The annual export of total alkalinity by the Amur into the marine environment (mol/year) increases normalized total alkalinity in the surface layer off the eastern shores of the Sakhalin Island (Sea of Okhotsk) and in the northern part of the Sea of Japan.