Component elements of the carbon cycle in the middle and lower Yenisei River

An integrated study of the middle and lower Yenisei River was performed in the summer of 2012. It involved monitoring the key elements and ecological processes associated with the carbon cycle of the river ecosystem (the study area is more than 1800 km long). Measurements of the production and destruction processes have shown the failure of the “neutral pipe” hypothesis claiming that any river is a simple drain of carbon from terrestrial ecosystems to the ocean. The Yenisei River is not a purely heterotrophic ecosystem. It also has autotrophic areas, where the primary production of planktonic photosynthesis is higher than respiration (above the Angara River and near the Bolshaya and Malaya Heta rivers). According to the data, the respiration rate of the plankton community in the river depends mostly on the water temperature and the content of inorganic phosphorous that can restrict the amount of organic matter consumed by bacterioplankton.