Organic geochemistry analysis to decipher temporal carbon variations in Lop Nur Salt Lake, China

Abstract

Saline lakes store and release carbon across different spatial and temporal scales, and are important for determining carbon budget; however, it is difficult to evaluate their carbon response and feedbacks to environmental change over long time scales. In this paper, we reconstruct the carbon variation history of Lop Nur Salt Lake, China over the last ∼25 ka through the application of organic geochemical proxies. Organic carbon fraction measurements of different temperature fractions, coupled with their carbon isotope characteristics provide a useful perspective on the drivers of salt lake carbon variations. Lop Nur salt lake lacustrine sediments record the final shrinking of the salt lake in response to inland Asian aridification. Our study focuses on the residual oxidizable carbon fraction and post-oxidative carbon depletion mechanism in Lop Nur salt lake sediments during 12–6 ka. This information allows us to evaluate ecosystem climatic feedbacks. Our results indicate that more negative carbon isotopic values since 6 ka is likely related to the high carbon capacity of saline water. This mechanism is potentially significant, especially with regard to ecological degradation scenarios associated with global warming.