Khan, Alia听1听;听Jaffe, Rudolf听2听;听Ding, Yan听3听;听McKnight, Diane听4
1听颁鲍-叠辞耻濒诲别谤/滨狈厂罢础础搁
2听Florida International University听
3听Florida International University
4听颁鲍-叠辞耻濒诲别谤/滨狈厂罢础础搁
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 the enrichment in anthropogenic black carbon is recent. Differences in the chemical composition of dissolved black carbon among the lakes is likely due to biogeochemical processing such as photochemical degradation and sorption on metal oxides.