文摘
We analyzed the pollen and spore distributions in sediments from the northern South China Sea to support reconstruction of the region's paleoenvironment. 1) Based on PCA analysis in the two areas with water depths of < 200 m and > 200 m, pollen and spores found at water depths of < 200 m are transported by rivers and ocean currents, while in samples from water depths of > 200 m, wind transport is dominant. 2) Tree pollen was abundant on the continental shelves near Guangdong and southeastern Hainan Island, the center of the study area, and deep basins in the south. Pinus pollen was abundant, with the highest levels on the continental shelf near Guangdong and in the marine area south of 15掳N. Pollen from tropical and subtropical broad-leaved trees (e.g., Castanopsis, Quercus) had low abundances. Castanopsis pollen appeared to originate near Hainan Island, Guangdong, and the Indochina Peninsula. Herbaceous pollen was less abundant, with pollen from the Poaceae and Artemisia scattered among the northern and southern regions, with the highest levels near Guangdong and a distribution that followed the rivers or sea surface circulation. Poaceae pollen was most abundant along the Guangdong and Vietnam coasts due to their proximity to tropical and subtropical grasslands and crops. Monolete spores and Cyperaceae pollen were most abundant near the Pearl River Estuary, southern Hainan Island, and southwestern Taiwan, probably originating from fluvial river discharge. Trilete spores (mostly Dicranopteris) were most abundant on the continental shelf of southeastern Hainan Island and the continental slope far from Guangdong. 3) Pollen and spore assemblages from airborne, sea surface water and sediment samples were compared. From August to September, airborne pollen and spores mainly belong to trees (Ulmaceae, Pinus) and herbaceous pollen, and have seasonal characteristics. Ocean surface waters in August-September mainly contain D. dichotoma, Rhizoma polypodiodis nipponicae and other trilete spores, but no Pinus pollen, with clear seasonality characteristic. Pollen and spore assemblages in surface sediments are dominated by trilete spores, Pinus and herbaceous pollen, and appear to integrate the pollen characteristics of the four seasons.
