Fast quantitative analysis of n-alkanes, PAHs and alkenones in sediments

Abstract

The study of different organic biomarker classes is essential to elucidate global Earth dynamics since different biogeochemical processes play a role in regulating environmental and climatic conditions. However, multiproxy analysis generally consists of labor-intensive and time-consuming methodologies, which hamper the study of a large number of samples. Here, we develop and validate a fast analytical method to quantify different classes of organic biomarkers (PAHs, n-alkanes and alkenones) in sediments. This new method sequentally extracts and fractionates the target compounds using a pressure liquid extraction (PLE) system, which allows us to selectively obtain the analytes by reducing the time of analysis, sample handling and solvent usage. We show that our method provides reproducible results and high recoveries (>70%), and can be applied to a wide range of sedimentary environments, such as oceanic basins, continental slope and shelf, and lakes. Moreover, the method provides reproducible estimates of paleoclimatic indices, such as the carbon preference index (CPI), the average chain length (ACL) and the U37K'-derived sea-surface temperature (SST). Therefore, this new method enables fast quantitative multiproxy analysis of oceanic, coastal and lake sediments.