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| Registros recuperados: 11 | |
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| Li, Chen; Jian, Zhimin; Jia, Guodong; Dang, Haowen; Wang, Jianxin. |
| Marine nitrogen fixation contributes to the budget of biologically available N, thus fuels phytoplankton productivity and carbon cycle through biological pump. Modern N‐fixation rates are proved to be constrained by oceanographic condition and nutrient supply to the surface waters. However, the paleoceanographic reconstruction of N‐fixation and its regulation mechanism remain highly uncertain in many regions. Here we present records of N‐fixation changes in the South China Sea (SCS) over the past 250,000 years reconstructed by compound‐specific nitrogen isotopes of individual amino acids. The δ15N of source amino acids (δ15NSrc), reflecting the δ15N of the substrate nitrate originating from the subsurface water, is distinctly lower during interglacial... |
| Tipo: Text |
Palavras-chave: Compound-specific delta N-15; Upper water structure; Bulk sedimentary delta N-15; Nitrogen fixation; Orbital time scale; South China Sea. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00509/62061/66237.pdf |
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| Jian, Zhimin; Wang, Yue; Dang, Haowen; Lea, David W.; Liu, Zhengyu; Jin, Haiyan; Yin, Yaqian. |
| The El Niño−Southern Oscillation (ENSO), which is tightly coupled to the equatorial thermocline in the Pacific, is the dominant source of interannual climate variability, but its long-term evolution in response to climate change remains highly uncertain. This study uses Mg/Ca in planktonic foraminiferal shells to reconstruct sea surface and thermocline water temperatures (SST and TWT) for the past 142 ky in a western equatorial Pacific (WEP) core MD01-2386. Unlike the dominant 100-ky glacial−interglacial cycle recorded by SST and δ18O, which echoes the pattern seen in other WEP sites, the upper ocean thermal gradient shows a clear half-precessional (9.4 ky or 12.7 ky) cycle as indicated by the reconstructed and simulated temperature (ΔT) and δ18O... |
| Tipo: Text |
Palavras-chave: Thermocline temperature; Half-precession; Western equatorial Pacific; Meridional gradient. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00614/72647/71649.pdf |
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| Wan, Sui; Jian, Zhimin. |
| Deep ocean circulation is widely considered as one of the important factors for increasing CO2 concentration and decreasing radiocarbon activity (C-14) of the atmosphere during the last deglaciation. The AMS C-14 ages of benthic and planktonic foraminifers from 18 samples of Core MD05-2904 (water depth of 2066m) in the northern South China Sea (SCS) and 15 samples of Core MD05-2896 (water depth of 1657m) in the southern SCS were analyzed in this study for reconstructing the intrabasin deep oceanic processes and hence exploring the deep water exchanges between the SCS and the Pacific since the last glacial period. The results show that during the Holocene the average apparent ventilation age of deep water was younger in the southern SCS (1350years) than in... |
| Tipo: Text |
Palavras-chave: Deep water renewal; AMS 14C dating; Last glacial cycle; South China Sea. |
| Ano: 2014 |
URL: https://archimer.ifremer.fr/doc/00289/40040/39257.pdf |
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| An, Yang; Jian, Zhimin. |
| The planktonic foraminiferal faunal census of core MD 05-2894 (7 degrees 2.25'N, 111 degrees 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... |
| Tipo: Text |
Palavras-chave: Pulleniatina Minimum Event; Subsurface seawater temperature; Upper ocean structure; The last deglaciation; The southern South China Sea. |
| Ano: 2009 |
URL: https://archimer.ifremer.fr/doc/00207/31841/30286.pdf |
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| Zhang, Hongrui; Liu, Chuanlian; Jin, Xiaobo; Shi, Jiangnan; Zhao, Shaohua; Jian, Zhimin. |
| In this study, paleoproductivity on millennial scales was precisely reconstructed from core MD12-3428cq in the northern South China Sea (SCS) over the past 24 kyr, based on a transfer function derived from the strong exponential negative correlation between relative abundance of Florisphaera profunda (%FP) in core top sediments and basin-wide satellite-based primary productivity (PP) in the SCS. To detect the potential driving mechanisms of PP, correlation analyses were carried out among our PP records and other paleoenvironment parameters. PP peaked during 18–15 ka in parallel with the strong East Asian Winter Monsoon (EAWM). From 15 ka to the early Holocene, a decrease in PP coincided with sea level progradation and weakening of EAWM, which ultimately... |
| Tipo: Text |
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| Ano: 2016 |
URL: https://archimer.ifremer.fr/doc/00361/47208/47162.pdf |
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| Wang, Tingting; Ravelo, Ana Christina; Ren, Haojia; Dang, Haowen; Jin, Haiyan; Liu, Jingjing; Jian, Zhimin. |
| We report the differences between δ15N of organic nitrogen bound in foraminifera tests (foraminifera‐bound δ15N, or FB‐δ15N), which is considered an effective recorder of thermocline nitrate δ15N in the oligotrophic areas, and bulk sedimentary δ15N (δ15Nbulk) of core MD12‐3433, located in the northern South China Sea (SCS), to explore possible causes of the offset between these two proxies in the SCS. The offset can be best explained by the influence of the terrigenous input on δ15Nbulk, as evidenced by its general correlation with sea level changes, C:N ratios, and inorganic nitrogen contribution to total nitrogen. Moreover, our new record is compared to six previously published δ15Nbulk records of the SCS based on their geographical proximity to the... |
| Tipo: Text |
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| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00441/55238/56719.pdf |
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| Bian, Yeping; Jian, Zhimin; Weng, Chengyu; Kuhnt, Wolfgang; Bolliet, Timothe; Holbourn, Ann. |
| A palynological analysis of a marine sediment core in the southern Philippines, provides a detailed regional vegetation and climate history for the West Pacific Warm Pool (WPWP) since the Last Glacial Maximum (LGM). Chronology was determined by a detailed oxygen isotope record. A higher representation of pollen from tropical upper montane rainforest during the LGM indicate that this forest type moved down along elevation, probabaly due to the lowered temperature. During the last deglaciation and the early Holocene, mangroves were more expanded and tropical mid and upper montane rainforests were restricted, suggesting a rising sea-level and temperature increase. Herbaceous pollen and pteridophyte spore records indicate a much drier condition during the LGM... |
| Tipo: Text |
Palavras-chave: Last Glacial Maximum; Tropical rainforests; Palynological analyses; Sea-level change; River discharge. |
| Ano: 2011 |
URL: https://archimer.ifremer.fr/doc/00213/32468/30921.pdf |
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| Dang, Haowen; Jian, Zhimin; Bassinot, Franck; Qiao, Peijun; Cheng, Xinrong. |
| The Holocene variability in sea surface and thermocline water temperatures (SST and TWT) in the Indo-Pacific Warm Pool (IPWP) has been reconstructed by planktonic foraminiferal Mg/Ca from sediments of the western tropical Philippine Sea. Afterward the Younger Dryas interval (YD), SST warmed gradually till similar to 10 ka and remained approximately constant afterwards, but TWT rose more rapidly to a peak between similar to 12 and similar to 10 ka and then declined by similar to 1.5 degrees C through the Holocene. The trend of TWT closely followed the boreal summer insolation and could be correlated to tropical climate changes represented by southward movement of the Inter-tropical Convergence Zone (ITCZ) and related changes in East Asian monsoons. |
| Tipo: Text |
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| Ano: 2012 |
URL: https://archimer.ifremer.fr/doc/00266/37690/36815.pdf |
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| Fan, Weijia; Jian, Zhimin; Chu, Zhihui; Dang, Haowen; Wang, Yue; Bassinot, Franck; Han, Xiqiu; Bian, Yeping. |
| The hydrological characteristics, including temperatures and salinities, of the upper water over the last 30 ka from two sites connected by the Indonesian Throughflow (ITF) across the Makassar Strait are reconstructed and compared. The thermocline hydrological gradient in the strait was larger during 13.4~19 ka BP and 24.2~27 ka BP than that in the Holocene. The weakened ITF during those periods in the last glacial period, corresponding to the decreased trade wind stress under an El Niño-like climate mean state, likely accounts for the increased thermocline gradient. The thermocline water temperature variabilities of the two sites, in particular the highest peaks at ~7 ka BP, are different from the records of the open western Pacific. Reoccurrence of the... |
| Tipo: Text |
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| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00436/54756/56204.pdf |
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| Registros recuperados: 11 | |
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