Researchers have discovered that the ice-covered lakes in Antarctica’s McMurdo Dry Valley uphold the thawed fragments of black carbon from ancient wildfires. The study was published in the American Geophysical Union journal Geophysical Research Letters, and was co-authored by Drs. Yan Ding and Rudolf Jaffe of the Southeast Environmental Research Center at Florida International University.
The authors analyzed the long-term history of the lakes and found no record of local forest fires burning in neighboring areas. This provides more certainty that the woody signatures have come over from Africa, South America or Australia. Overall, there have been relatively limited direct measurements of dissolved black carbon in the cryosphere due to the problems of sample collection from these remote environments. These are the first known measurements of this kind from freshwater lakes in Antarctica, according to the American Geophysical Union.
The study reveals that dissolved black carbon can stay in freshwater and saline surface waters for thousands of years, while conserving the chemical signature of the original source materials. The prehistoric seawaters of the lake bottom waters have preserved the dissolved black carbon with a woody chemical signature. In contrast, the waters are supplemented in black carbon from fossil fuel combustion. The distinctions in the chemical composition of dissolved black carbon among the lakes are possibly due to biogeochemical processing that includes the sorption on metal oxides and photochemical degradation.
This study may provide information and conclusions on how the black carbon signatures have moved over time and how the dissolved black carbon is carried to the world’s oceans and lakes. See the original article here >>