Journal of Marine Sciences ›› 2023, Vol. 41 ›› Issue (1): 121-130.DOI: 10.3969-j.issn.1001-909X.2023.01.010

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Paleoenvironmental indication of n-alkanes composition: A case study of sediments from the Pearl River Estuary since the mid-Holocene

CHEN Guosheng1(), QIU Zihui1, KONG Deming1,2,*()   

  1. 1. College of Ocean and Meteorology, Guangdong Ocean University, Zhanjiang 524088, China
    2. Key Laboratory of Climate, Resources and Environment in Continental Shelf Sea and Deep Sea of Department of Education of Guangdong Province, Zhanjiang 524088, China
  • Received:2022-10-24 Revised:2023-01-30 Online:2023-03-15 Published:2023-04-28

Abstract:

The multiple indices of n-alkanes including ∑oddC25-33, CPI, ACL, C31/C27 and Pmar-aq from a sediment core HKUV16 retrieved in the Pearl River Estuary were analyzed to explore their sources and environmental changes since the mid-Holocene. The distribution features of n-alkanes of core HKUV16 indicated that they were mainly from terrestrial higher vegetation. From 8.0 to 7.0 ka BP, ∑oddC25-33, CPI, and Pmar-aq increased, while ACL and C31/C27 were low, which showed that terrestrial organic matter input increased and woody vegetation increased. The decrease of ∑oddC25-33 during 7.0~3.2 ka BP indicated that the input of terrestrial organic matter decreased, while the ACL and C31/C27 showed an increase-decrease-increase trend, suggesting that the Pearl River Basin might have experienced dry-wet-dry climate change. From 3.2 to 2.2 ka BP, high ACL and C31/C27 indicated that herbaceous plants expanded and the climate was relatively arid. The multi-indices showed that the input of n-alkanes to the Pearl River Estuary before 2.2 ka BP was mainly affected by East Asian summer monsoon. However, increasing human activities since 2.2 ka BP might have become the dominant factor for the ecological environment of the Pearl River Basin.

Key words: Pearl River Estuary, n-alkanes, mid-Holocene, summer monsoon

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