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Amphorotia is a diatom genus of considerable morphological and biogeographical significance. It was established by transferring several Eunotia species and describing several new species. The most species were found dispersed towards Southeast Asia. In coastal areas of China, a number of species of Amphorotia were found and the assemblages contained several new taxa. This article provides additional information on five previously described species and describes one new species, Amphorotia zhujiangensis sp. nov., and one uncertain but special species, A. sp. These are based on fossil material from a deltaic borehole, subaquatic sediment cores and surface sediments collected in the Pearl River estuary region. Morphological data were derived from light and scanning electron microscopy. A detailed morphological comparison of seven Amphorotia species is included, indicating the existence of a diverse group in brackish waters. Relationships within the family Eunotiaceae are briefly discussed. The biogeo...

Learning pollen transport mechanisms is the basis for correct interpretation of fossil pollen data. Firstly, 33 seabed surface sediment samples from the northeastern Indian Ocean were selected for pollen analysis. Utilizing the 90°E Indian Ridge as a dividing line, more Trilete spores (mainly Microlepia)and herbaceous pollen were present to the west or northwest of the line, possibly originating in Sri Lanka and India. More Polypodiaceae spores and tree pollen (Pinus excluded) were present to the east or southeast of the boundary, possibly originating in Sumatra Island. Based on the PCA analysis, the ocean current from the southeast to the northwest and the distance from land masses around the study area affect the percentage of pollen. Then, based on a fossil pollen analysis on the YDY05 core from the northeastern Indian Ocean, we determined that since 16 ka BP, the pollen terrestrial area might change from Sumatra Island to Sri Lanka Island and India, probably due to the climate and sea level change.

In order to provide a reference for reconstructing the paleoclimate of the northeastern Indian Ocean, 36 airborne pollen samples were analyzed using methods for airborne pollen, and 26 surface water samples were analyzed using a lab method for surface water. We found that little pollen is airborne over the Indian Ocean in spring, but airborne pollen types and concentrations can help to deduce paleomonsoon strength and direction. The conclusions included the following: (1) Pollen in the sediment was transported mainly via ocean currents instead of the early summer or spring wind. (2) Airborne pollen types and concentrations are proportional to the wind speed and inversely proportional to the pollen distance transported and depend on whether the wind is from the land or from the sea. If the wind is from the land, the pollen concentration is proportional to the angle between the wind direction and the coastline. (3) The pollen concentration in the sample collected from a water depth of 30–45 m is higher than in the samples collected from a depth of 5 m. The pollen concentration and salinity are higher in the equatorial area than in the Northern Hemisphere.

Rapid expansion of the Pearl River Delta Plain (PRDP) of South China in recent millennia has been attributed to climatic changes or human impact. We have addressed this issue through detailed examination of pollen, charcoal, organic matter, chemical elements and foraminifera in a 6.5 ka marine core SCSF47 in the continental shelf of the northern South China Sea. Our results reveal a sharp acceleration in terrestrial sediment input around 2.8 ka BP connected to dramatic increases in pollen concentration, total organic carbon, and charcoal. These increases, combined with results of analysis of surface pollen samples in the area, indicate that the Pearl River's influence strengthened. The main source of pollen changed from the Pearl River basin to the PRDP during this time, indicating accelerated formation of the PRDP. Moreover, significant increases in charcoal concentration and Pinus pollen indicate that human activities intensified in this area during the past 2.8 ka, implying that human activities accelerated development of the PRDP. Our study provides evidence that the PRDP's accelerated formation in the late Holocene was mostly due to human activities, as the precipitation and other climatic variables have not changed much during this period. The findings suggest that ongoing global warming and human activities may substantially affect deltas and facilitate predictions of deltas' responses to such drivers.

This study presents a marine palynological record of the Asian summer monsoon and sea level change in the Last Glacial Maximum (LGM) and the deglacial period in the northern South China Sea (SCS). A fossil core STD 235 (855 cm in length) and 273 surface sediment samples from the northern SCS were pollen analysed to reconstruct the paleoenvironment of the continental shelf during the last glacial period. Results from fossil pollen show that the main pollen source region fundamentally changed from the LGM to the deglacial period as sea level rapidly rose. The modern marine surface samples show that pollen concentrations in the estuary of the Pearl River are extremely high, and modern pollen assemblages are in good agreement with the regional vegetation. However, wind transport becomes more important in the deeper ocean as the percentages of Pinus, a taxon with very high pollen production and dispersal capacity, is highest in these sediments, which otherwise have very low pollen concentrations. The concentration of total pollen between surface and fossil pollen samples is compared in order to determine the possible vegetation sources areas for the marine core. Pollen concentration as high as >100 grains/g at the LGM suggested that the paleo-shoreline was located within 80 km of the core. Consequently, pollen would mostly have derived from the exposed continental shelf in the northern SCS. By contrast, pollen concentrations were very low due to a much greater transport distance (318 km at present, core STD 235) under higher sea levels, and windblown pollen played a more important role because of the limitation of riverine input into the deep ocean during this highstand period. Such alternation of pollen flux and source distance should be repeated during all glacial-interglacial cycles, reflecting closely sea level and climate dynamics. According to fossil pollen assemblages from Core STD 235, we conclude that wetland and/or grassland communities with sparse subtropical trees dominated most of the exposed shelf during the LGM rather than forest that characterizes the region today. The existence of a predominantly open landscape on the exposed continental shelf suggests lower precipitation during the LGM, which in turn indicates a weaker Asian summer monsoon. This finding is supported by other records from the Okinawa Trough and the East China Sea, suggesting that a weaker summer monsoon was a key characteristic of the LGM in East Asia.

The species abundances and assemblage of fossil diatoms are used as micropaleontological proxy to reconstruct the northwestern South China Sea continental margin paleo-environment over the last glacial - interglacial cycle and Holocene. Analysis of fossil diatom assemblages in piston core 111PC show a flora over the most recent ~160 kyr. BP dominated by tropical-subtropical planktonic and coastal species, assigned to six local diatom assemblage zones similar to foraminifera-based marine oxygen-isotope stages (MIS 6-1). Diatom abundance and species fluctuations in the core profile study area respond to the glacial – interglacial climate gyration and climate instability. Diatom abundance was higher in the late-Wurm, compared to mid-Wurm glacial and postglacial (Holocene) stages and even lower during the Riss and early-Wurm glacial stages. Change tendency of diatom abundance is significantly different from stations to the southwest but comparable to northeast South China Sea. In MIS 5, relative abundance of tropical diatom taxa decreases upward in response to climate shifts from interglacial to last glacial interval. Diatom species distribution with higher relative abundance of coastal taxa responded to climate-fluctuation during the MIS 4 and MIS 3 transition while biased by local deposition character.

Previous studies of pollen in northern Borneo lack basic data on surface soil pollen as a basis for the quantitative reconstruction of paleoclimate and modern palynological comparison. In this study, we conducted palynological analysis on 86 surface soil samples from northern Borneo, in addition to core NS07-25 from the southern South China Sea (SCS). The results reveal that the principal pollen component of the modern soil in northern Borneo is ferns (95.19%) and the second one is trees (4.07%). Fern spores dominate the pollen diagram of tropical rainforests in Borneo. In the northeast to southwest transect, fern spores and tree pollen represent approximately 94.47% and 4.41% of the topsoil pollen, respectively. At the highest-altitude site of the northwest to southeast transect, tree pollen and Polypodiaceae spores had the highest percentages. At low altitudes, the tree pollen content was low and Microlepia spores were abundant. Based on the principal component analysis of pollen samples, components 1 and 2 are probably related to humidity and temperature, respectively, which are crucial factors influencing pollen distribution. According to the near analysis function from ArcGIS, the pollen and spores in core NS07-25 may have originated from northern Borneo, during 37.52–26 ka BP, and

In order to provide a reference for reconstructing the paleoclimate of the northeastern Indian Ocean, 36 airborne pollen samples were analyzed using methods for airborne pollen, and 26 surface water samples were analyzed using a lab method for surface water. We found that little pollen is airborne over the Indian Ocean in spring, but airborne pollen types and concentrations can help to deduce paleomonsoon strength and direction. The conclusions included the following: (1) Pollen in the sediment was transported mainly via ocean currents instead of the early summer or spring wind. (2) Airborne pollen types and concentrations are proportional to the wind speed and inversely proportional to the pollen distance transported and depend on whether the wind is from the land or from the sea. If the wind is from the land, the pollen concentration is proportional to the angle between the wind direction and the coastline. (3) The pollen concentration in the sample collected from a water depth of 30-45 m is higher than in the samples collected from a depth of 5 m. The pollen concentration and salinity are higher in the equatorial area than in the Northern Hemisphere.