01706nas a2200145   4500008004100000245009500041210006900136260001200205520122100217100001901438700001901457700001401476700002401490856004601514       2016                        eng d00aDissolved black carbon in Antarctic lakes: chemical signatures of past and present sources0 aDissolved black carbon in Antarctic lakes chemical signatures of  c06/20163 a<p><span style="color: rgb(51, 51, 51); font-family: 'Open Sans', Arial, Helvetica, 'Lucida Sans Unicode', sans-serif; font-size: 16px; line-height: 24px; background-color: rgb(249, 249, 249);">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&thinsp;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.</span></p>1 aKhan, Alia, L.1 aJaffé, Rudolf1 aDing, Yan1 aMcKnight, Diane, M.  uhttp://doi.wiley.com/10.1002/2016GL068609