Pollen quantitative distribution in marine and fluvial surface sediments from the northern South China Sea: New insights into pollen transportation and deposition mechanisms

Abstract

In order to improve the understanding of pollen transportation and deposition mechanisms in northern South China Sea (SCS), 45 seafloor surface sediment samples from the SCS and nine surface sediment samples from the Pearl River mouth were analyzed palynologically. The spatial distributions of pollen and spore taxa suggest that various transport mechanisms and the production at the source. The dominant pollen Pinus, Poaceae, Cyperaceae and fern spores are most abundant in the river mouth and decrease with increasing distance from the land, suggesting they are mainly derived from the Pearl River drainage basin and strongly dispersed by river plume and ocean currents, which reflects a dominant pollen transportation pattern in the northern SCS. Podocarpus and temperate broad-leaved components pollen, such as evergreen Quercus and Castanopsis pollen, is common in marine samples and is scattered in the Pearl River samples, reflecting their extensive source areas and dispersal in more than one route. However, some pollen types of conifers are mostly deposited close to the shore, such as Dacrydium, Picea and Abies, which are restricted near Hainan Island and Taiwan Island. Excluding evergreen Quercus and Castanopsis pollen, the total tropical and subtropical components poorly reflect their parent plants, and fewer such pollen are transported over long distances. However, the source areas of some other pollen taxa (e.g., Phyllocladus, Artemisia and Chenopodiaceae) are unclear. Spatially varying ratios of spores to pollen indicate that spores are relatively easily transported by water over longer distances than are pollen grains. This study provides a sound basis for interpreting Quaternary pollen deposits from the northern SCS, and for further evaluation of pollen dispersal and deposition in marine and fluvial deposits.