New insights into spatiotemporal source apportionment of n-alkanes under mixed scenario: A pilot study on Lake Chaohu, China

N-alkanes are idealmolecular markers for the source apportionment of organicmatter. However, the estimation of both biogenic and anthropogenic sources under mixed scenario using n-alkanes and their related proxies still remains an issue. In this study, we investigated spatiotemporal variations of n-alkanes in suspended particulate matter of Lake Chaohu for their source apportionment. Overall, Sigma(29) n-alkanes ranged from 324.1 to 113685 ng.L-1. C17H36 was the most abundant homologue and was followed by C-18, C-27 and C-29 homologues. Carbon preference indexes (CPIs) in most samples (at least 85%) were b 21 for algae dominance and ACL(bio) > 26 for terrestrial plant dominance. For anthropogenic n-alkanes, their carbon-chain distribution presented obviously spatiotemporal variations. The sources of anthropogenic n-alkanes in summer and winter were typical dominances of light petroleum and incomplete fossil fuel burning/heavy oil emission, respectively. New developed proxies, anthropogenic average chain length (ACL(anthro)) and the ratio of unit short- to long-carbon anthropogenic n-alkanes (L/H), are effective for quantifying the relative contributions of different anthropogenic sources. We recommend log(10)L/H > 0.5 and ACL(anthro) < 20.5 for light petroleum input dominance, log(10)L/H < -0.5 and ACL(anthro) > 26.5 for incomplete fossil fuel burning at high temperature/heavy oil emission dominance. (C) 2020 Elsevier B.V. All rights reserved.