Dissolved black carbon in Antarctic lakes: Chemical signatures of past and present sources

Authors

Alia L. Khan, University of Colorado Boulder
Rudolf Jaffe, Southeast Environmental Research Center and Department of Chemistry and Biochemistry, Florida International UniversityFollow
Yan Ding, Southeast Environmental Research Center and Department of Chemistry and Biochemistry, Florida International UniversityFollow
Diane M. McKnight, University of Colorado Boulder

Abstract

The perennially ice-covered, closed-basin lakes in the McMurdo Dry Valleys, Antarctica, serve as sentinels for understanding the fate of dissolved black carbon from glacial sources in aquatic ecosystems. Here we show that dissolved black carbon can persist in freshwater and saline surface waters for thousands of years, while preserving the chemical signature of the original source materials. The ancient brines of the lake bottom waters have retained dissolved black carbon with a woody chemical signature, representing long-range transport of black carbon from wildfires. In contrast, the surface waters are enriched in contemporary black carbon from fossil fuel combustion. Comparison of samples collected 25 years apart from the same lake suggests that the enrichment in anthropogenic black carbon is recent. Differences in the chemical composition of dissolved black carbon among the lakes are likely due to biogeochemical processing such as photochemical degradation and sorption on metal oxides.

Comments

DOI: 10.1002/2016GL068609

This material is based upon work supported by the National Science Foundation through the Florida Coastal Everglades Long-Term Ecological Research program under Cooperative Agreements #DEB-1237517, #DBI-0620409, and #DEB-9910514. Any opinions, findings, conclusions, or recommendations expressed in the material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.

Recommended Citation

Khan, A. L., R. Jaffé, Y. Ding, and D. M. McKnight (2016), Dissolved black carbon in Antarctic lakes: Chemical signatures of past and present sources, Geophys. Res. Lett., 43, 5750–5757, doi:10.1002/2016GL068609.