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DISSOLVED ORGANIC CARBON IN PEATLAND WATERSHEDS OF WEST SIBERIA

FREY, KAREN E  University of California, Los Angeles.
Smith, Laurence C  University of California, Los Angeles.

Since the Last Glacial Maximum, West Siberia has accumulated a major fraction of the global soil carbon pool in the form of peat, which now represents the most extensive peatlands in the world (Smith et al. 2004). This store of carbon is a significant source of dissolved organic carbon (DOC) to the region’s watersheds that ultimately discharge to the Arctic Ocean. Field campaigns to West Siberia have yielded DOC concentrations from 98 watersheds throughout the region (Fig. 1). A strong dependence of DOC concentration on average annual surface air temperature and/or permafrost is observed in these sampled streams and rivers. Preliminary results reveal a robust contrast between cold permafrost watersheds with uniformly low DOC and warm non-permafrost watersheds with DOC increasing rapidly as a function of peatland abundance. A critical surface air temperature threshold, which is also approximately coincident with the permafrost boundary, appears to separate the two DOC regimes. Climate model scenarios predict significant warming of West Siberia in the next century. Given similar hydrological conditions, this suggests a likely increase in DOC export both to West Siberian peatland watersheds and the adjacent Arctic Ocean.

REFERENCES
Smith, L. C., MacDonald, G. M., Velichko, A. A., Beilman, D. W., Borisova, O. K., Frey, K. E., Kremenetski, K. V. & Sheng, Y., 2004, Siberian peatlands a net carbon sink and global methane source since the early Holocene: Science, v. 303, p. 353–356.



Figure 1. West Siberia and the locations of 98 water samples collected throughout the region.


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