Dissolved black carbon in Antarctic lakes: Chemical signatures of past and present sources. Issue 11 (8th June 2016)

• Record Type: Journal Article
• Authors: Khan, Alia L.; Jaffé, Rudolf; Ding, Yan; McKnight, Diane M.
• Is Part Of: Geophysical research letters. Volume 43:Issue 11(2016)
• Page Start: 5750
• Page End: 5757
• Publication Date: 2016-06-08
• Subjects: dissolved black carbon -- cryosphere -- recalcitrance -- Antarctic lakes -- limnology -- fate and transport; Geophysics -- Periodicals; Planets -- Periodicals; Lunar geology -- Periodicals; 550
• DOI: 10.1002/2016GL068609
• Languages: English
• ISSNs: 0094-8276

Abstract

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. Key Points: Antarctic lakes are sentinels for understanding the fate of dissolved black carbon from glacial‐melt Dissolved black carbon is preserved in glacier‐fed surface waters for millennia There has been a recent shift from a wildfire signature of dissolved black carbon to an anthropogenic signature