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Pan‐Arctic patterns in black carbon sources and fluvial discharges deduced from radiocarbon and PAH source apportionment markers in estuarine surface sediments
Author(s) -
Elmquist Marie,
Semiletov Igor,
Guo Laodong,
Gustafsson Örjan
Publication year - 2008
Publication title -
global biogeochemical cycles
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.512
H-Index - 187
eISSN - 1944-9224
pISSN - 0886-6236
DOI - 10.1029/2007gb002994
Subject(s) - arctic , fluvial , environmental science , radiocarbon dating , estuary , oceanography , total organic carbon , deposition (geology) , physical geography , flux (metallurgy) , geology , sediment , environmental chemistry , geography , geomorphology , paleontology , chemistry , organic chemistry , structural basin
A pan‐arctic geospatial picture of black carbon (BC) characteristics was obtained from the seven largest arctic rivers by combining with molecular combustion markers (polycyclic aromatic hydrocarbons) and radiocarbon ( 14 C) analysis. The results suggested that the contribution from modern biomass burning to BC ranged from low in the Yukon (8%) and Lena (5%) Rivers to high in the Yenisey River (88%). The Mackenzie River contributed almost half of the total arctic fluvial BC export of 202 kton a −1 (kton = 10 9 g), with the five Russian‐Arctic rivers contributing 10–36 kton a −1 each. The 14 C‐based source estimate of fluvially exported BC to the Arctic Ocean, weighted by the riverine BC fluxes, amount to about 20% from vegetation/biofuel burning and 80% from 14 C‐extinct sources such as fossil fuel combustion and relict BC in uplifted source rocks. Combining these pan‐arctic data with available estimates of BC export from other rivers gave a revised estimate of global riverine BC export flux of 26 × 10 3 kton a −1 . This is twice higher than a single previous estimate and confirms that river export of BC is a more important pathway of BC to the oceans than direct atmospheric deposition.