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The palaeoceanographic studies are largely limited by poor carbonate preservation in high-latitude regions. To improve our knowledge in this key area, we studied a sediment core (ANT32-RA05C) in terms of paleomagnetic and 230Th dating and geochemical properties, collected from the continental slope of the Ross Sea, Antarctica. The two major results are as follows: 1) the sedimentation rate based on 230Th isotopes is 1.37 cm/kyr, agreeing well with the correlation of the relative paleomagnetic intensity of the core ANT32-RA05C to changes in Earth’s magnetic intensity and 2) the sediments contain ice-rafted debris (IRD) over 30%, with a considerable contribution of siliceous deposits. Integrating geochronological and geochemical properties of the studied core, a correlation of the regional paleoenvironmental process to the EPICA Dome C (EDC) Antarctic temperature is established, inferring that the IRD input and primary productivity are both enhanced in a warm climate. Moreover, a leading phase of biogenic processes to changes in the ice sheet in the Ross Ice Shelf is observed, highlighting a dominant role of the oceanic circulation in the ice-sheet retreat during the last deglaciation. Overall, the sedimentary record in the Ross Sea documents some key features of the paleoenvironmental processes in the Late Pleistocene, which could be correlated with large-scale changes in Antarctica and thus are worthy of further investigation in the future.

The North Pacific subtropical gyre (NPSTG) redistributes heat and moisture between low and high latitudes and plays a key role in modulating the global climate change and ecosystem. Recent evidence suggests intensification and poleward shift of the subtropical gyres over the last decades due to global warming, but insufficient observations have hampered insight into the integrated effects of ocean-atmosphere interactions at longer timescales. Here we present the first high-resolution (∼12 years) grain-size record from Core CF1 in the Okinawa Trough, western subtropical North Pacific, to reconstruct the evolution of the western boundary Kuroshio Current (KC) of NPSTG during the Late Holocene. Our results indicate the KC slow-down during 4.6–2.0 ka, followed by quick enhancement after 2.0 ka, with centennial-scale variabilities (500–700 years) superimposed on the long-term trend. Over millennial timescales, gradually increased pole-to-equator thermal gradient, due to orbital forcing mechanisms, resulted in long-term enhanced KC, whereas solar activity triggered phase changes in the tropical Pacific mean state and controlled KC anomalies on centennial timescales. We suggest that both forcing mechanisms resulted in ocean-atmosphere feedback provoking concurrent changes in mid-latitude westerly and subtropical easterly winds over the North Pacific, alternating their dominance as source regions causing the dynamic changes of KC at different timescales. Our findings offer insight into the role of external forcing mechanisms in the NPSTG changes before the Anthropocene, which have profound implications for the deeper understanding of changes in ocean gyres under global warming scenarios.

Changes in marine export productivity may have played a prominent role in the atmospheric CO2 rise and associated warming of the last deglaciation, via their impact on the air-sea partitioning of CO2. To study the evolution of marine export production in the western subtropical Pacific Ocean during the last deglaciation and the mechanisms governing these changes, 230Th-normalization has been applied on a sediment core retrieved from the Okinawa Trough. The reconstructed export productivity record shows two prominent peaks, centered around 14 and 17 ka. Given that phytoplankton growth at our study site is limited by the availability of nutrients today, elevated macro-nutrient supply must have been responsible for sustaining the two deglacial productivity peaks. Specifically, higher nutrient supply originating from the subpolar gyre via subsurface water advection, with enhanced vertical mixing in the subpolar gyre during early HS1 and enhanced wind-driven upwelling during the B/A, would have fueled phytoplankton productivity and export. In contrast, reduced nutrient supply to the euphotic zone caused by gyre circulation changes would have lead to decreased export production during the Holocene. These observations lend support to a predominant control of nutrient availability on the evolution of the marine carbon cycle in the subtropical west Pacific Ocean across the last deglaciation.

In this study,a total of 274 surface sediments from the offshore area of Shandong Peninsula were collected and analyzed for grain-size,total organic carbon(TOC),and major elementss.Results show that SiO2 is the highest major element,followed by Al2O3 as the second.These two major elements make up 77.8% of the total major elements.The composition of major elements depends upon the type of sediment or grain-size.SiO2 is usually enriched in the coarse-grained sediments,whereas Al2O3、Fe2O3、MgO、MnO、P2O5 and K2O are relatively concentrated in fine-grained sediments.However,Na2O and TiO2 are independent from sediment types.The results of correlation and R-factor analysis suggested that the distribution of major element in the surface sediments from the offshore area of Shandong Peninsula can be classified to three groups.The first group consists of SiO2、Al2O3、Fe2O3、MgO、K2O、TiO2、P2O5、TOC,the second includes CaO and CaCO3,and Na2O and MnO belong to the last groups.These three groups may probably represent terrigenous,marine biogenous and marine authigenic sediments respectively.The chemical weathering index of the surface sediments varies from 50-65,depending upon their provenance.The CIA and TiO2/Al2O3 values suggest that the Huanghe sediments are mainly deposited along the offshore area of Shandong Peninsula,controlled by the coastal currents and the sea bottom geomorphology.