CURRENT LIMITATIONS FOR CARBON RELEASE FROM WATERSHEDS OF CENTRAL SIBERIAN PLATFORM Anatoly PROKUSHKIN*, Oleg POKROVSKY**, Mikhail KORETS*, William H. McDOWELL*** *VN Sukachev Institute of Forest SB RAS, Krasnoyarsk, RF **LMTG-CNRS, Toulouse, France ***University of New Hampshire, Durham, USA prokushkin@ksc.krasn.ru ENVIROMIS-2010, Tomsk, July 7, 2010
• The Arctic drainage basin (~24 × 10 6 km 2 ) processes about 11% of global runoff (Lammers et al. 2001) and 13% of dissolved organic carbon (DOC) (Raymond et al. 2007). 17-42 Tg • Arctic and subarctic regions demonstrate most significant changes during last decades which include northward shifts of vegetation, declining permafrost and increased river discharge (Serreze et al., 2000; Kharuk et al., 2005; Peterson et al., 2002; Schuur et al., 2008). • However, differences in geomorphology, hydrology, permafrost regime, soil types and vegetation among basins of Eurasian rivers exert uncertainty in overall response of hydrologic C export under global warming. In particular, largest Siberian rivers from west to east (Ob’, Yenisey, Lena, Kolyma) demonstrates drastic diversity in watershed properties, and their reaction to climate change remain poorly understood. •
Permafrost 100% 60% 10%
Large Arctic river discharge and C export DOC export, gC/m 2 /a Ob’ 0.99-1.01 Yenisey 1.15-2.23 Lena 1.19-2.34 Dittmar T, Kattner G (2003) Tg/a Raymond et al. (2007) PARTNERS and current program by University of Boulder, CO http://www.r-arcticnet.sr.unh.edu/v4.0/index.html
Among subarctic basins least attention was paid to the vast area of traps of Siberian platform (approximately 1,500,000 km2). The Nizhnyaya Tunguska River and its major tributary the Kochechum River draining “south” and “north” of Siberian platform provide unique opportunity for studying responses of carbon and other elements fluxes in permafrost landscapes to global warming due to almost monolithologic terrains with negligible human activity (Pokrovsky et al., 2005). The purpose of this study was dual: 1) to fill the gap in our knowledge about riverine export of dissolved C from basaltic watersheds in Central Siberia underlain by permafrost and 2) estimate potential changes of terrestrial carbon export induced by global warming.
Nizhnyaya Tunguska basin N. Tunguska River at Tura – Southern part of watershed Kochechum River at Tura – Northern part of watershed Kochechum River Tura research station N. Tunguska River Carbon density map …
River basin characteristics Table 1 Sampling site Station Specific runoff, mm Drainage area, Latitude km 2 Longitude 1939-1995 2006 2007 2008 2009 61.30 N Nizhnyaya 108.00 E Tunguska 6623 77400 121 - - - - Nizhnyaya 64.15 N 100.15 E Tunguska 6625 268000 190 192 291 349 227 64.95 N Tembenchi 6629 98.80 E 18900 421 355 495 493 348 Table 2 Station name and Latitude Period of record MAT, o C WMO ID: Longitude entire years MAP, mm ERBOGACEN 61.30N 1936-2008 24817 108.00E 59 -6,9 333,0 Tura 64.17N 1939-2008 24507 100.07E 78 -9,0 369,9 Tembenchi 64.57N 1967-1993 23499 98.51E 20 -11,5 459,4
Vegetation classes (GLC 2000) Kochechum N. ¡Tunguska Tundra, ¡% 34.5 1.6 Dark ¡coniferous ¡evergreen ¡forests, ¡% 0.03 8.3 Larch ¡forests, ¡% 61.9 79.3 Deciduous ¡forests, ¡% 0.0 4.9 Peatlands, ¡% 0.8 1.7 Recent ¡burns, ¡% 0.2 1.1 Total ¡area, ¡% 97.2 95.8
Annual river discharge 100 N. Tunguska (Tura) 90 80 70 Discharge (km3/y) 60 50 40 y = 0,3559x - 648,51 30 2 = 0,3472 R 20 10 0 Peterson et al., 2002 1930 1940 1950 1960 1970 1980 1990 2000 2010 Year 15 Tembenchi (Tembenchi) 20 N. Tunguska (Yerbogachen) 18 12 16 Discharge (km3/y) 14 9 Discharge (km3/y) 12 10 6 8 6 y = 0,0284x - 47,758 3 4 R 2 = 0,1134 y = -0,0338x + 75,875 2 R 2 = 0,0593 0 0 1930 1940 1950 1960 1970 1980 1990 2000 2010 1930 1940 1950 1960 1970 1980 1990 2000 2010 Years Year
Seasonal discharge patterns 60 60 N. Tunguska (Tura) N. Tunguska (Tura) 50 50 Discharge (km3/y) Discharge (km3/y) 40 40 30 30 20 20 10 10 y = 0,2389x - 435,88 y = 0,1435x - 265,38 R 2 = 0,3873 2 = 0,1143 R 0 0 1930 1940 1950 1960 1970 1980 1990 2000 2010 1930 1940 1950 1960 1970 1980 1990 2000 2010 Year Year Summer-fall Snowmelt (July-October) (May-June)
River discharge (2006-2009) 24000 Nizhnyaya Tunguska 2006 2007 22000 2008 20000 2009 18000 16000 Discharge, m 3 /s 14000 12000 10000 8000 -15 6000 -17 4000 2000 -19 18 O (pro mille) 0 0 30 60 90 120 150 180 210 240 270 300 330 360 -21 DOY 24000 2006 Kochechum 2007 -23 22000 2008 20000 2009 Kochechum -25 Tunguska 18000 Discharge (m3/s) 16000 -27 19.09.08 18.11.08 17.01.09 18.03.09 17.05.09 16.07.09 14.09.09 14000 Date (dd.mm.yy) 12000 10000 8000 6000 4000 2000 0 0 30 60 90 120 150 180 210 240 270 300 330 360 DOY
Discharge and C concentration peaks 25000 50 45 20000 40 35 DOC and DIC (mgC/l) 15000 30 Q (m3/s) 25 25000 50 Q 10000 20 45 DIC DOC 15 20000 40 5000 10 35 DOC and DIC (mgC/l) 5 15000 30 Q (m3/s) 0 0 25 25.10.2005 02.07.2006 09.03.2007 14.11.2007 21.07.2008 28.03.2009 03.12.2009 10000 20 Date 15 N. Tunguska 5000 10 5 0 0 25.10.2005 02.07.2006 09.03.2007 14.11.2007 21.07.2008 28.03.2009 03.12.2009 Date Kochechum
C export by Tunguska 40 y = 21,146x 1,2036 R 2 = 0,996 35 DOC 30 DIC -1 ) Carbon flux (Gg d 25 20 50 15 y = 27,384x 45 R 2 = 0,9893 10 40 -1 ) 5 35 Carbon flux (Gg d 30 0 0,0 0,2 0,4 0,6 0,8 1,0 1,2 1,4 1,6 1,8 2,0 25 Discharge (km 3 d -1 ) 20 15 10 5 0 0,0 0,2 0,4 0,6 0,8 1,0 1,2 1,4 1,6 1,8 2,0 Discharge (km 3 d -1 )
C export by Kochechum 20 snowmelt 20 Summer-fall 18 0,9799 y = 14,671x 18 R 2 = 0,9843 16 16 DOC export (Gg/day) 14 14 12 Export (GgC/d) 12 10 10 8 8 6 6 4 4 2 2 0 0 0,00 0,20 0,40 0,60 0,80 1,00 1,20 0,00 0,20 0,40 0,60 0,80 1,00 1,20 Discharge (km3/day) Discharge (km3/d) Southern part of watershed exports more Corg, suggesting C limitation in Putorana plateau
Annual riverine C export normalized to specific runoff 7,0 7,0 DOC DIC DOC DIC 6,0 6,0 y = 0,0184x 5,0 5,0 R 2 = 0,9529 y = 0,0092x Riverine C flux (gC/m 2 ) 2 ) R 2 = 0,9764 Riverine C flux (gC/m 4,0 4,0 3,0 3,0 y = 0,0115x R 2 = 0,9508 2,0 2,0 1,0 1,0 y = 0,0042x R 2 = 0,7122 0,0 0,0 0 50 100 150 200 250 300 350 400 450 500 0 50 100 150 200 250 300 350 400 450 500 Annuaul river discharge (km 3 ) Specific runoff (mm) Tunguska Kochechum Water limitation of Corg export from both watersheds
Seasonal pattern 4,0 y = 0,0112x + 1,5486 4,0 R 2 = 0,9869 Snowmelt 3,5 Summer-fall 3,5 3,0 3,0 2 ) y = 0,0052x + 1,1816 2 ) Riverine C flux (gC/m R 2 = 0,9071 2,5 Riverine C flux (gC/m 2,5 2,0 2,0 1,5 1,5 y = 0,0117x - 0,5618 R 2 = 0,9958 y = 0,0161x - 0,1078 1,0 1,0 R 2 = 0,9976 0,5 0,5 0,0 0,0 0 50 100 150 200 250 300 350 400 450 500 0 50 100 150 200 250 300 350 400 450 500 Specific runoff (mm) Specific runoff (mm) Tunguska Kochechum
Seasonal DOC Yields of Yukon Sub-basins 100 DOC Yield (mmol C m -2 ) Spring 80 Summer through Autumn 60 40 20 Winter 0 0 50 100 150 200 250 Water yield (mm) Striegl et al., WRR, 2007
Other important C species in river water POC pCO2 100 90 Corg=2% 80 70 60 y = 0,0038x RSM (mg/l) R 2 = 0,5867 50 40 30 Corg=8% 20 10 0 100 1000 10000 100000 Discharge (m3/s) Current student works
CO 2 Striegl et al., GRL, 2005 Active Respiration DIC export Layer to river Soil DOC DOC export to river Permafrost Increased CO 2 CO 2 Increased Respiration Respiration DIC export DIC export to river to river Active Active No change Increased Layer Soil DOC Soil DOC Layer or decreased DOC export (Increased (Increased Soil DOC Soil DOC DOC export to river depth and depth and Thawed to river Thawed duration) duration) Permafrost Permafrost Permafrost Permafrost
Conclusions River basins draining Siberian platform demonstrate significant potential to increase the release of terrestrial carbon to the Arctic Ocean. Increased hydrological C losses are projected through: • (i) enhancement of temperature-controlled DOC, DIC, POC and CO2 production processes within watersheds; • (ii) raised precipitation, thereby increasing C mobilization from organic-rich layers; • (iii) introduction of a new source of C as vegetation shift northward and • (iv) release of old C from degrading permafrost (likely less important in mountainous region like Putorana Plateau) .
Acknowledgements • Authors thank stuff of Tura research station and personally Sergey Tenishev for their profound help with field sampling throughout the year. Especially under -55 o C … The researches are supported by ongoing RFBR- CNRS and the RFBR-CRDF Joint projects. A. Prokushkin greatly acknowledges annual support provided by Siberian Branch of Russian of Academy of Sciences to Tura research station.
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