The Elemental Carbon Records Of The Last 150ka In The Weinan Loess Section

The term "elemental carbon" inculdes a wide spectrum of carbon-rich,and O-H-S-N-poor compounds produced by combustions. Since elementalcarbon (EC) well records the fire history, studying the EC will not onlyhelp to understand the dynamic process of vegetation evolution, but alsobe an important way to reconstruct the paleoclimate history. The ECabundance and carbon isotope ratios of the last 150ka loess samples fromthe Weinan Loess Section have been analyzed using chemical methods forthe first time, and the paleovegetation and paleoclimate information ofthe loess have been obtained. The study suggests that the EC can be usedas a new climatic proxy for pa1eoc1imate studies of loess, particularlyin revealing short-term climate changes.The range of EC abundance is 0. 1‰-0. 75‰, with average of 0. 26‰.There are 4 peaks greater than 0. 5‰ at 11. 97ka, 19. 95ka, 27. 41ka and99. 16ka, respectively. On the whole, the fluctuation of the EC abundancecoincides with the climate changes.The â– ¹³C values of the EC show isotopic characteristic of C₄. vegetation,varying from -8. 97‰ to -21. 34‰, with average of- 17. 31‰, suggestingthat the pa1eoyegetation of the Weinan was dominated in grass1and withoccasionally forest since the last 150ka. This cognition is coincidentwith the resu1ts of organic carbon, pollen and phyto1ith.The f1uctuations of the EC abundance correlate we1l with that of 5ls0 in GRIP ice core, indicating the existence of some short--term climatechange events, such as Younger Dryas, Heinrich events and Bond's cycles.The spectra of the EC abundance show similar cyc1es with the orbitalvariations. Thus it suggests that the changes of the EC abundance areaffected by the 1ong--term climate changes driven by the orbita1variations as well as the short--term c1imate changes.