ИСТИНА

Among the changes taking place in the modern biosphere cycles of biogenic elements (primarily carbon), the most important is a combined effect of climatic and local anthropogenic factors related to land use, which drives CO2 balance in the ecosystems into the source to the atmosphere, or increases emissions of other biogenic greenhouse gases. To estimate this, the simple way is to evaluate soil emission, since it comprises in anthropogenically modified (AM) ecosystems 70-99% of total respiration. Field measurements were conducted in August-September of 2014-2016. The fluxes of CO2, methane and nitrous oxide were estimated in natural and AM biotopes in the Arctic landscapes (Komi Republic, Svalbard, Yamal Peninsula, Eastern Chukotka, North of Arkhangelsk Oblast). It is shown that significant deviations from background emission (27 types of AM ecosystems) occur in all cases. Depending on the nature and duration of the anthropogenic influence (AI), or types of ecosystems, it can be observed either increase or decrease in soil emissions compared to natural rates. Nevertheless, acting together anthropogenic factors with a high probability provide additional net source of CO2. This is due to the elimination of primary production and the delayed CO2 emission from soils. CO2 emission factors among AM biotopes are the following (in descending order of importance): the anthropogenic factor net duration, the thickness of permafrost active layer, air temperature, the thickness of organic horizon, and storage of above-ground phytomass. The greatest CO2 fluxes were determined for coalmine pit (4.81 gC m-2 h-1) and for roadsides of active gravel roads (2.84 gC m-2 h-1) in tundra. These values are an order of magnitude higher than the average rate of anthropogenic land sources of CO2 in Arctic and northern boreal subzones, and 40-60 times above the natural rates. AM methane sources depending on the type of AI could show positive (emission increase) or negative (emission reduction) effect on radiation forcing, whereas anthropogenic sources of N2O have only positive effect. Despite the fact that the influence of weather conditions can significantly affect soil emissions, taking into account 4 times lower, on average, primary production rates at all AM sites, this means that they continue to be a net sources of CO2 to the atmosphere. On residential areas in the Arctic, up to 25% of the total net source of CO2 into the atmosphere per year can be attributed to soil emissions. Calculations show that local anthropogenic soil emissions are comparable with the impact of climate change over the same period.The research is performed under the program of scientific studies by the Presidium of the RAS «Fundamental research for Arctic development”.