ИСТИНА

The role of the Arctic Ocean in the global carbon cycle has been widely discussed over the past decade. Interest in this problem is caused by climatic changes that occur in middle and high latitudes and are expressed in increasing average air temperature, melting permafrost, increasing river flow, as well as increasing the duration of the ice-free period in the Arctic seas. The destruction of permafrost and changes in hydrological conditions, in particular the growth of river flow, increase the role of the Arctic basin in the global cycle of greenhouse gases. But the Arctic Ocean is not only a basin with huge hydrocarbon reserves. It also receives the runoff of the world's largest rivers, whose catchments run, among other things, in the permafrost zone. Therefore, it is important to study the role of the great Siberian rivers as a source of greenhouse gases on the Russian Arctic shelf. In presented work the direct measurements of fluxes and concentrations of carbon dioxide, the spatial variability of gas exchange characteristics in the Ob and Lena rivers is investigated. Measurements were carried out from the river ships. To calculate the fluxes, the eddy covariance method was used. Throughout the summer, rivers serve as a source of greenhouse gas emissions into the atmosphere. On average, emissions of carbon dioxide on two rivers practically coincide. But, unlike the Ob Bay, there is a slight increase in methane flow in the Lena Delta. Additional sources of methane can be sources on the Arctic shelf. Along the whole ship route the Lena River is supersaturated with carbon dioxide in respect to the atmosphere. This leads to significant positive CO2 fluxes in the coastal zone of the Laptev Sea. Possible coastal and river sources of greenhouse gases are investigated. Measurements of the turbulent fluxes of latent and apparent heat, as well as momentum, are used to determine the exchange coefficients and the roughness parameter of the river flow.