Leaf Wax and Sr‐Nd Isotope Evidence for High‐Latitude Dust Input to the Central South China Sea and Its Implication for Fertilization. Issue 11 (4th June 2021)

• Record Type: Journal Article
• Authors: Yang, Yi; Bendle, James A.; Pancost, Richard D.; Yan, Yan; Ruan, Xiaoyan; Warren, Bridget; Lü, Xiaoxia; Li, Xuejie; Yao, Yongjian; Huang, Xianyu; Yang, Huan; Xie, Shucheng
• Is Part Of: Geophysical research letters. Volume 48:Issue 11(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-06-04
• Subjects: aeolian dust -- carbon and hydrogen isotopes -- leaf wax -- n‐alkane -- South China Sea -- Sr‐Nd isotopes; Geophysics -- Periodicals; Planets -- Periodicals; Lunar geology -- Periodicals; 550
• DOI: 10.1029/2020GL091853
• Languages: English
• ISSNs: 0094-8276

Abstract

Abstract: Recent time‐series from sediment traps show abnormally high chlorophyll‐ a concentrations and primary productivity in the oligotrophic central South China Sea (SCS), especially during wintertime. Here we present new insights from compound‐specific hydrogen isotopic analysis of leaf wax n ‐alkanes and Sr‐Nd isotope compositions extracted from four basin‐wide surface sediment transects. We find that the deepest surface sediments in the central basin contain the most depleted n ‐alkane hydrogen isotopes, suggesting inputs from higher latitude soils in northern China. This is supported by the Sr‐Nd isotope compositions of the same surface sediments. We propose that aeolian dust is transported by the winter monsoon and might fertilize the phytoplankton bloom in the central SCS. This process may have been enhanced in ancient times when the winter monsoon was stronger, driving both vertical mixing and dust transport to the central basin. Plain Language Summary: Recent studies observe abnormally high winter primary productivity and nitrate concentrations in the surface waters of the central South China Sea (SCS). However, this is a nutrient limited region of the ocean, so the drivers of this primary productivity are unclear. Here we analyze leaf wax carbon and hydrogen isotopes, and Sr‐Nd isotopes, along four shallow‐to‐deep‐water sediment transects to trace the sources of dust and organic matter in the sediments of the central basin. Our results suggest the central basin sediments receive significant terrestrial inputs of dust and nutrients from northern Asia via long‐range aeolian transport during the winter monsoon. These results give new insights to terrestrial‐marine connections and the carbon cycle of the SCS. This process may provide a new mechanism to understand the glacial‐interglacial productivity changes in marginal seas. Key Points: High concentrations of leaf‐wax n ‐alkanes are observed in the South China Sea (SCS) central basin n ‐Alkane carbon preference index and hydrogen isotopic composition trace aeolian dust deposition from higher latitudes to the central basin Aeolian dust plays a significant role in regulating deposition of terrestrial organic matter in the central SCS