[1] Surface sediments were collected during the 2000 TransArctic Expedition along the Siberian Arctic coastline, including the Ob, Yenisey, Khatanga, Lena, and Indigirka estuaries. Sediments were characterized for elemental composition (total organic carbon, TOC, black carbon, BC, and total N, as well as major and trace elements), isotopic signature (d Sr), and organic molecular composition to better understand river export variations over the large spatial scale of the Siberian Arctic. On average, 79 ± 9% of the total C in sediments was organic while 21 ± 9% was inorganic. BC made up 9 ± 4% of the TOC pool, with a general increasing trend from west to east along the Siberian coast. The combined Nd-and Sr-isotopes (e Nd and 87 Sr/ C values were significantly correlated with the ratio of BC/TOC (R 2 = 0.91, n = 6), consistent with the distribution pattern of increasing permafrost zone from the west to the east along the Siberian coast. Together, our results suggest that older OC was derived from the release of recalcitrant BC during permafrost thawing and riverbank and coastal erosion, likely enhanced by ongoing environmental changes in the northern ecosystem.

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Mercury speciation analysis in soil samples by ion chromatography, post-column cold vapor generation and inductively coupled plasma mass spectrometry

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