Size-fractionated distribution of glycerol dialkyl glycerol tetraether core lipids in surface sediments of a large-river delta-front estuary

Jinpeng Wang; Bin Zhao; Peng Yao; Thomas S Bianchi; Julius S Lipp; Marcus Elvert; Zhiqiang Yu; Zhigang Yu; Kai-Uwe Hinrichs

doi:10.1016/j.scitotenv.2023.169626

Size-fractionated distribution of glycerol dialkyl glycerol tetraether core lipids in surface sediments of a large-river delta-front estuary

Sci Total Environ. 2024 Feb 20:912:169626. doi: 10.1016/j.scitotenv.2023.169626. Epub 2023 Dec 28.

Authors

Jinpeng Wang¹, Bin Zhao², Peng Yao³, Thomas S Bianchi⁴, Julius S Lipp⁵, Marcus Elvert⁵, Zhiqiang Yu⁶, Zhigang Yu⁷, Kai-Uwe Hinrichs⁵

Affiliations

¹ State Environmental Protection Key Laboratory of Water Environmental Simulation and Pollution Control, South China Institute of Environmental Sciences, Ministry of Ecology and Environment, Guangzhou 510535, China; State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China; MARUM-Center for Marine Environmental Sciences, University of Bremen, Leobener Straße 8, D-28359 Bremen, Germany.
² Key Laboratory of Marine Eco-Environmental Science and Technology, First Institute of Oceanography, Ministry of Natural Resources, Qingdao 266061, China.
³ Frontiers Science Center for Deep Ocean Multispheres and Earth System, Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, Ocean University of China, Qingdao 266100, China; Laboratory for Marine Ecology and Environmental Science, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266237, China. Electronic address: yaopeng@ouc.edu.cn.
⁴ Department of Geological Sciences, University of Florida, Gainesville, FL 32611-2120, USA.
⁵ MARUM-Center for Marine Environmental Sciences, University of Bremen, Leobener Straße 8, D-28359 Bremen, Germany.
⁶ State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China.
⁷ Frontiers Science Center for Deep Ocean Multispheres and Earth System, Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, Ocean University of China, Qingdao 266100, China; Laboratory for Marine Ecology and Environmental Science, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266237, China.

PMID: 38159761
DOI: 10.1016/j.scitotenv.2023.169626

Abstract

Glycerol dialkyl glycerol tetraether core lipids (GDGTs) are microbial biomarkers ubiquitously distributed in terrestrial and marine environments. Dispersal and fate of GDGTs in an estuary largely depends on sediment grain size, however, their size distribution patterns remain poorly understood. Here, surface sediments collected from the Changjiang Estuary were separated into <20, 20-32, 32-63, 63-125 and >125 μm fractions, and analyzed for GDGTs as well as total organic carbon (TOC), stable isotopic composition (δ¹³C) of TOC and lignin phenols, to investigate the size and spatial distributions of GDGTs and the particle size effects on GDGTs proxies in this large river delta-front estuary. The concentrations of isoprenoidal GDGTs (isoGDGTs) were higher in the finest fractions and in off-estuary sites. On the contrary, branched GDGTs (brGDGTs) were high not only in the finest fractions but in coarser fractions (>32 μm fractions), and thus at both near- and off-estuary sites. The branched and isoprenoid tetraether (BIT) index increased with increasing grain size, and decreased sharply from the estuary (~0.52) to the shelf (~0.16). BrGDGTs were positively correlated with crenarcheaol in both high and low BIT regions. The brGDGTIIIa/IIa ratios in all size fractions were <0.59, further indicating that the brGDGTs were mainly derived from terrestrial input with minimum in-situ production. Fractional TOC source assignments derived from the BIT index was significantly positively correlated with the fractions of terrestrial OC from a mixing model based on δ¹³C-TOC and lignin contents, indicating that BIT may track a broader pool of terrestrial OC than just soil OC. This work provides novel, yet preliminary insights into the size fractionated distribution characteristics of GDGTs and the applicability of BIT as a proxy for OC sources in estuarine sediments. More work is needed to further clarify the particle size effects on other GDGTs proxies in estuarine systems.

Keywords: BIT; Changjiang Estuary; Size fractionation; Surface sediments; brGDGTs; isoGDGTs.