Аннотация: Greenhouse gas (GHG) emission from inland waters of permafrost-affected regions is one of the key factors of circumpolar aquatic ecosystem response to climate warming and permafrost thaw. Riverine systems of central and eastern Siberia contribute a significant part of the water and carbon (C) export to the Arctic Ocean, yet their C exchange with the atmosphere remains poorly known due to lack of in situ GHG concentration and emission estimates. Here we present the results of continuous in situ pCO(2) measurements over a 2600 km transect of the Lena River main stem and lower reaches of 20 major tributaries (together representing a watershed area of 1 661 000 km(2), 66% of the Lena's basin), conducted at the peak of the spring flood. The pCO(2) in the Lena (range 400-1400 mu atm) and tributaries (range 400-1600 mu atm) remained generally stable (within ca. 20 %) over the night-day period and across the river channels. The pCO(2) in tributaries increased northward with mean annual temperature decrease and permafrost increase; this change was positively correlated with C stock in soil, the proportion of deciduous needleleaf forest, and the riparian vegetation. Based on gas transfer coefficients obtained from rivers of the Siberian permafrost zone (k = 4.46md(-1)), we calculated CO2 emission for the main stem and tributaries. Typical fluxes ranged from 1 to 2 gCm(-2) d(-1) ( 99% CO2, 1% CH4), which is comparable with CO2 emission measured in the Kolyma, Yukon, and Mackenzie rivers and permafrost-affected rivers in western Siberia. The areal C emissions from lotic waters of the Lena watershed were quantified by taking into account the total area of permanent and seasonal water of the Lena basin (28 000 km(2)). Assuming 6 months of the year to be an open water period with no emission under ice, the annual C emission from the whole Lena basin is estimated as 8.3 +/- 2.5 TgCyr(-1), which is comparable to the DOC and dissolved inorganic carbon (DIC) lateral export to the Arctic Ocean.
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Держатели документа:
Tomsk State Univ, BIO GEO CLIM Lab, Tomsk, Russia.
Umea Univ, Climate Impacts Res Ctr CIRC, Dept Ecol & Environm Sci, Linnaeus Vag 6, S-90187 Umea, Sweden.
Russian Acad Sci, Siberian Branch, VN Sukachev Inst Forest, KSC SB RAS, Krasnoyarsk 660036, Russia.
CNRS, UMR 5563, Geosci & Environm Toulouse, 14 Ave Edouard Belin, F-31400 Toulouse, France.
Russian Acad Sci, N Laverov Fed Ctr Integrated Arctic Res, Arkhangelsk, Russia.
Доп.точки доступа:
Vorobyev, Sergey N.; Karlsson, Jan; Kolesnichenko, Yuri Y.; Korets, Mikhail A.; Pokrovsky, Oleg S.; Government Council on Grants, Russian Federation [14.B25.31.0001]; Forsvarsdepartementet, Sveriges [2016-05275]