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Search Results: 1 - 10 of 29896 matches for " ZhiMin Jian "
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Pulleniatina Minimum Event during the last deglaciation in the southern South China Sea
Yang An,ZhiMin Jian
Chinese Science Bulletin , 2009, DOI: 10.1007/s11434-009-0290-4
Abstract: The planktonic foraminiferal faunal census of core MD 05-2894 (7°2.25′N, 111°33.11′E, water depth 1982 m), retrieved from the southern South China Sea (SCS) during the “Marco Polo” cruise in 2005, was performed to investigate the abundance changes of a subsurface dweller, Pulleniatina obliquiloculata. The results display that the abundance of P. obliquiloculata nearly declines to zero during 16.0-14.9 ka, corresponding to the Heinrich 1 (H1) cold interval. The unexpected decrease of P. obliquiloculata occurs in the adjacent cores, roughly between 17 and 14.8 ka based on the previous studies. Accordingly, the Pulleniatina Minimum Event in the last deglaciation can serve as a good stratigraphical indicator, at least in the southern SCS. To further explore the changes of sea surface temperature (SST) and sub-surface seawater temperature (SSST), we made parallel Mg/Ca measurements on surface dweller Globigerinoides ruber and subsurface dweller P. obliquiloculata tests. Since the last deglaciation, the SSTs show a continuous increasing trend towards the late Holocene, while the warming of the subsurface water is punctuated by a 2°C-cooling interval across the deglacial Pulleniatina Minimum Event. Both increased δ18O differences between G. ruber and P. obliquiloculata, and increased temperature differences between surface and subsurface water suggest a shoaling of the mixed layer during the deglacial Pulleniatina Minimum Event. Therefore, we consider that the significant changes in the upper ocean structure are responsible for the Pulleniatina Minimum Event during the last deglaciation in the southern SCS.
Paleoproductivity records for the past 30 ka in the southern Nansha area, the South China Sea
Dianyong Fang,Zhimin Jian,Pinxian Wang
Chinese Science Bulletin , 2000, DOI: 10.1007/BF02886085
Abstract: This note presents productivity variations for the past 30 ka in the southern Nansha area, the South China Sea, from the gravity core 17962 (7°11′N, 112° 5′E, core length: 8 m, water depth: 1 968 m). Estimated surface productivity demonstrates that at the last glacial maximum the productivity was about 1.6 times as much as that in the Holocene, and the change may be ascribed to an increase of terrestrial nutrients as sea level lowered in the glacial time.
Benthic foraminiferal fauna turnover at 2.1 Ma in the northern South China Sea
BaoQi Huang,ZhiMin Jian,PinXian Wang
Chinese Science Bulletin , 2007, DOI: 10.1007/s11434-007-0114-3
Abstract: Quantitative analysis of benthic foraminifera from ODP Site 1146 in the northern South China Sea (SCS) shows that abundance of Bulimina alazanensis, sometimes up to about 90%, decreased gradually since 3.2 Ma, especially at 2.1 Ma. Abundance of other benthic foraminiferal species, Globobulimina subglobosa and Cibicidoides wuellerstorfi, increased after 2.1 Ma. Comparison with changes in oxygen and carbon isotopes of planktonic and benthic foraminifera shows that high abundance values of B. alazanensis corresponded with lower values of oxygen isotope, but for carbon isotope, high values of the species were consistent with heavier carbon isotope of benthic foraminifera and lighter carbon isotope of planktonic foraminifera, respectively, and vice versa. Considering factors such as uplift of Bashi Strait, expansion of the North Hemisphere Glaciation, strengthening of East Asian winter monsoon and variations in oxygen and carbon isotope of foraminifera, changes of B. alazanensis in ODP Site 1146 suggest that the source of deep water masses of the northern South China Sea changed from the warm Pacific deep water with high oxygen content to Pacific Intermediate water with low oxygen content at 2.1 Ma. In addition, the strengthened East Asian winter monsoon resulted in increased primary productivity, high nutrient and suboxic bottom water. Variations in species of B. alazanensis seemed to be unable to tolerate environmental stress induced by deep water masses and productivity changes.
Benthic foraminiferal fauna turnover at 2.1 Ma in the northern South China Sea
huang baoqi,jian zhimin,wang pinxian,
HUANG
,BaoQi,JIAN,ZhiMin,WANG,PinXian

科学通报(英文版) , 2007,
Abstract: Quantitative analysis of benthic foraminifera from ODP Site 1146 in the northern South China Sea (SCS) shows that abundance of Bulimina alazanensis, sometimes up to about 90%, decreased gradually since 3.2 Ma, especially at 2.1 Ma. Abundance of other benthic foraminiferal species, Globobulimina sub- globosa and Cibicidoides wuellerstorfi, increased after 2.1 Ma. Comparison with changes in oxygen and carbon isotopes of planktonic and benthic foraminifera shows that high abundance values of B. alazanensis corresponded with lower values of oxygen isotope, but for carbon isotope, high values of the species were consistent with heavier carbon isotope of benthic foraminifera and lighter carbon isotope of planktonic foraminifera, respectively, and vice versa. Considering factors such as uplift of Bashi Strait, expansion of the North Hemisphere Glaciation, strengthening of East Asian winter mon- soon and variations in oxygen and carbon isotope of foraminifera, changes of B. alazanensis in ODP Site 1146 suggest that the source of deep water masses of the northern South China Sea changed from the warm Pacific deep water with high oxygen content to Pacific Intermediate water with low oxygen content at 2.1 Ma. In addition, the strengthened East Asian winter monsoon resulted in increased pri- mary productivity, high nutrient and suboxic bottom water. Variations in species of B. alazanensis seemed to be unable to tolerate environmental stress induced by deep water masses and productivity changes.
Supported Nanosized α-FeOOH Improves Efficiency of Photoelectro-Fenton Process with Reaction-Controlled pH Adjustment for Sustainable Water Treatment
Chuan Wang,Hong Liu,Zhimin Sun,Jian Huang,Yang Liao
International Journal of Photoenergy , 2012, DOI: 10.1155/2012/689807
Abstract: The overall photoelectro-Fenton (PE-Fenton) process for water treatment with neutral initial pH includes three steps of pH reduction, PE-Fenton reaction, and pH elevation. Reaction-controlled pH adjustment (RCpA), which utilizes the intrinsic electrochemical reactions instead of chemical addition, has been employed to lower the pH, maintain the lowered pH for the Fenton reaction, and recover the pH for final effluent discharge. This study demonstrated that the overall efficiency of this sustainable PE-Fenton process was improved by rapidly recycling the iron substance. Nanosized iron oxide was prepared and employed to ensure such rapid recycling. SEM and XRD results showed that the as-prepared iron oxide was α-FeOOH with 20?nm in size. The experimental results of dimethyl phthalate (DMP) degradation showed that diatomite-supported α-FeOOH (N-α-FeOOH/diatomite) could efficiently reduce the DMP concentration and total organic carbon. Furthermore, compared with Fe3+, the N-α-FeOOH/diatomite saved 160?min for iron settlement at 20?mg L?1 DMP concentration. Also, with the increment in the initial DMP concentration, extra energy consumed by the individual step of PE-Fenton reaction using the N-α-FeOOH/diatomite became negligible compared with that using free iron ions with the increment in the initial DMP concentration. This development is expected to be a major step of the PE-Fenton process with RCpA towards actual water treatment. 1. Introduction The cathodic electro-Fenton reaction (E-Fenton) with electrogenerated H2O2 and added Fe2+ as an advanced oxidation process (AOP) has recently been developed on the basis of a well-established Fenton’s reagent [1–4] for the degradation of recalcitrant organic pollutants in aqueous media. The cathodic and coupled anodic reactions of the E-Fenton reaction are expressed as follows [4–6]: During this process, the electrogenerated H2O2 interacts with the added Fe2+ to form nonselective and highly active hydroxyl radicals that destroy the organic substrates. Many reports have demonstrated that the E-Fenton process is a promising AOP for water purification [7–9]. Two hurdles must be surpassed for the development for a realistic application of the E-Fenton process. The first is the narrow pH required for the Fenton reaction [10–12]. The medium pH for the Fenton reaction must be maintained within the narrow range of 2.0–4.0 to preclude the iron precipitate. This pH limitation obviously requires chemical addition of an acid and a base to obtain the desired pH, essentially hampering the realistic application of the PE-Fenton
Solar forced transient evolution of Pacific upper water thermal structure during the Holocene in an earth system model of intermediate complexity
Yue Wang,ZhiMin Jian,Ping Zhao,HaoWen Dang,Dong Xiao
Chinese Science Bulletin , 2013, DOI: 10.1007/s11434-012-5576-2
Abstract: Forced by transient solar activities since 7 ka, the thermal structures of the Pacific upper water at boreal winter are featured by an enhanced response of 3-dimensional Western Pacific Warm Pool (WPWP) in an Earth system model of Intermediate Complexity at centennial scales. During solar maximum periods, the magnitude of surface ocean temperature variations is 30% larger in the western tropical Pacific than in the Ni o3 region, while at subsurface, it is 40% larger in the subtropical North Pacific than in the western Equatorial Pacific. They compromise stronger zonal and meridional thermal gradients in surface and subsurface Pacific respectively which are both linearly responded to solar forcing at centennial periods. The surface gradient is most sensitive at 208-year period while the subsurface gradient shows more significance at periods longer than 208-year. Also noteworthy are two differences: (1) the phase lags at these periods of surface gradient are slightly smaller than that of subsurface; (2) the 148-year and 102-year periods in surface gradient are lost in subsurface gradient. These modeled features preliminary confirm the centennial fluctuations of WPWP in paleo-proxies and a potential solar forcing during the Holocene.
Late quaternary upper-water column structure in upwelling areas of the South China Sea
Huang Baoqi,Jian Zhimin,Cheng Xinrong,Wang Pinxian
Chinese Science Bulletin , 2001, DOI: 10.1007/BF02900664
Abstract: Based on a quantitative analysis of planktonic foraminifera in two gravity cores (17928 and 17954), the history of the upper-water structure of the eastern and west ern slopes of the South China Sea (SCS) over the last 220 Ka was reconstructed using the transfer function technique. Our results show that lower sea surface temperature (SST) and shallower depth of thermocline (DOT) exist at Core 17928, off Luzon, in the glacial periods; on the contrary, the same situation turned up in the interglacial at Core 17954, off Vietnam. These changes of the upper-water column structure in the two areas are induced by coastal upwelling, which in turn is driven by monsoons, namely, winter monsoon leads to upwelling at the eastern slope, and summer monsoon gives birth to upwelling on the western slope. Moreover, the intensity of upwellings is also closely related to the evolution of the East Asian monsoon. Therefore, we assume that the changes of the upwelling in the two sites indicate strengthenning of winter and summer monsoon during the glacial and inter glacial periods, respectively.
Early Pleistocene formation of the asymmetric east-west pattern of upper water structure in the equatorial Pacific Ocean
HaiYan Jin,ZhiMin Jian,XinRong Cheng,JianQing Guo
Chinese Science Bulletin , 2011, DOI: 10.1007/s11434-011-4547-3
Abstract: Surface- and subsurface-dwelling planktonic foraminifera from the upper 43 m of Hole A at the Ocean Drilling Program (ODP) Site 807, which was recovered from the western Pacific warm pool during ODP Leg 130, were analyzed for stable oxygen and carbon isotopes. By comparing these results with data from ODP Site 851 in the eastern equatorial Pacific, this study has reconstructed the paleoceanographic changes in upper ocean waters in the equatorial Pacific since 2.5 Ma. During the period from 1.6–1.4 Ma, the oxygen isotopes of surface and subsurface waters were found to markedly change in the western and eastern equatorial Pacific, further confirming the final formation of the well-defined asymmetric east-west (E-W) pattern at that time. This feature was similar to the zonal temperature gradient (sea surface temperature is higher in the west and lower in the east) and the asymmetric upper water structure (thermocline depth is deeper in the west and shallower in the east) in the modern equatorial Pacific. The zonal gradient change of subsurface water δ 18O was greater than that of surface water δ 18O, indicating that the formation of the asymmetric E-W pattern in the equatorial Pacific should be much more related to the shoaled thermocline and markedly decreased subsurface water temperature in the eastern equatorial Pacific. Moreover, since ~1.6 Ma, the carbon isotopic differences between surface and subsurface waters clearly decreased in the equatorial Pacific, and their long-term eccentricity periods changed from 400 ka to ~500 ka, reflecting the reorganization of the ocean carbon reservoir. This probably resulted from the deep water reorganization in the Southern Ocean at that time and its enhanced influence on the tropical Pacific (especially subsurface water). Our study demonstrates that the tropical ocean plays an important role in global climate change.
Shifts of the Kuroshio axis over the last 20 000 years
Jian Zhimin,Y. Saito,Wang Pinxian,Li Baohua,Chen Ronghua
Chinese Science Bulletin , 1998, DOI: 10.1007/BF02884649
Abstract: Core 255 from the southern Okinawa Trough was selected to monitor the shift of the Kuroshio axis over the last 20 000 years. During the last glacial maximum the Kuroshio axis had ever shifted outside the Okinawa Trough. It entered the Okinawa Trough again at about 6 500 a BP, leading to abrupt increase of sedimentation rate, distinctly coarser sediment and remarkably increased abundance of foraminiferal indicators of the Kuroshio in the core. But, during about 4 000-3 000 a BP the abundance of the Kuroshio indicatorPulleniatina obliquiloculata sharply decreased again, indicating that the Kuroshio axis had ever shifted casterly for a short period or the Kuroshio was weakened and that moment.
Modeling the impact of Australian Plate drift on Southern Hemisphere climate and environment
Botao Zhou,Ping Zhao,Zhimin Jian,Jinhai He
Chinese Science Bulletin , 2005, DOI: 10.1360/04wd0218
Abstract: Using a global atmosphere-ocean coupled model with the present-day and 14 MaB.P. oceanic topography respectively, two experiments are implemented to investigate the effect of different locations of Australian Plate on the atmospheric circulation in middle-high latitudes of the Southern Hemisphere. The results show that when Australian Plate lay south at 14 MaB.P., both anticyclone circulations in the subtropical oceans and cyclone circulation around 60°–70°S are strengthened. Subtropical highs and circumpolar low pressure appear stronger, which results in much stronger Antarctic Oscillation and shorter period of Antarctic Oscillation Index (AOI) at 14 MaB.P. The rainfall and the surface air temperature also change correspondingly. The precipitation decreases around 40°S and increases around 60°–70°S, and the surface air temperature rises in high latitudes of the South Pacific and descends over the Weddell Sea and its north side. Besides, due to the changes of the temperatures and winds, Antarctic sea ice coverage also changes with its increasing in the Ross Sea and its west regions and decreasing in the Weddell Sea.
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