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عنوان فارسی مقاله:
شار در حال تکامل از گرد و غبار آسیایی در اقیانوس آرام شمالی از اواخر الیگوسن
عنوان انگلیسی مقاله:
Evolving flux of Asian dust in the North Pacific Ocean since the late Oligocene
سال انتشار : 2016
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مقدمه انگلیسی مقاله:
1. Introduction
Asia interior is the second largest center of dust emission in the world (Engelbrecht and Derbyshire, 2010). The aeolian deposits of Asian dust in the Chinese loess, the pelagic sediments of NPO, and the Greenland ice cores serve as important archives for the late Cenozoic climate changes (Biscaye et al., 1997; Guo et al., 2002; Rea et al., 1998). Aeolian flux is one of the mostly used proxies that is believed to reflect the aridity of Asian interior (e.g., Sun and An, 2005). The best records for the long-term changes in flux of Asian dust is in the central NPO, where the pelagic sediment can extend back to the early Cenozoic Era (Pettke et al., 2002). The pelagic sediment in NPO is mainly composed of the mineral dust from the Asian interior and volcanic ash from the circumPacific volcanoes with precipitates of authigenic minerals, hydrothermal products, and biogenic organic carbon, opal and carbonate (Nakai et al., 1993; Ziegler et al., 2007). A chemical procedure, which involves sequential leaching by weak acid, reductive and oxidative reactants, and alkaline solution, has been employed to remove the carbonate minerals, amorphous Fe-Mn hydroxides, organic matter, and biogenic opal in the pelagic sediment (Rea and Janecek, 1981). The leaching residue, which is mainly detrital silicates, is regarded as ‘operationally defined aeolian dust’ (ODED) (Olivarez et al., 1991; Rea and Janecek, 1981). Flux of the ODED (FODED, g/cm2 /ka) is then can be calculated from the faction of ODED in the bulk sample (fODED, g/g) given that dry bulk density (D, g/cm3 ) and deposition rate (R, cm/ka) of the sediments were known (Rea and Janecek, 1981): FODED ¼ f ODED D R ð1Þ The reconstructed fluxes of ODED in NPO show a dramatic increase since 3–4 Ma (Janecek, 1985; Janecek and Rea, 1983; Rea et al., 1998). However, the detailed evolutions of FODED are very different among different sites. For example, the FODED reconstructed from ODP 885/886 sites shows a pronounced increase at 8 Ma, and then a decreasing trend until the second increasing step at 3.6 Ma (Rea et al., 1998). The first increasing step of FODED has not been registered in the site LL44-GPC3 and DSDP site 576 (Janecek, 1985; Janecek and Rea, 1983). However, the first increasing step of FODED recorded in ODP site 885/886 has been frequently htreferred to reflect the increasing aridity of Asian interior regardless the inconsistence with the other records (Guo et al., 2004; Pettke et al., 2000; Sun and An, 2002; Zheng et al., 2004). It is unlikely that the flux of Asian dust evolves differently among the different sites in the NPO because Asian dust has been largely dispersed after long-range transportation. Geochemical signature for the contribution of Asian dust in the pelagic sediments has been detected all cross the NPO (Nakai et al., 1993; Olivarez et al., 1991; Pettke et al., 2000, 2002; Seo et al., 2014; Serno et al., 2014; Stancin et al., 2006; Weber et al., 1996). The limited changes in position of the depositional sites associated with sea- floor spreading also cannot explain the inconsistent record of FODED among the different sites (Snoeckx et al., 1992). One of the major errors in calculating the FODED in Eq. (1) is sourced from the sedimentation rate (R). The pelagic sediments in NPO are characterized by low deposition rate of several meters per million years (Janecek and Rea, 1983; Rea et al., 1993, 1998). The slow deposition rate and the early recovery (before 1990s) of the ODP and DSDP cores prevent high-resolution magnetic reversal stratigraphy (Janecek and Rea, 1983; Rea et al., 1993, 1998). The pelagic sediments in the deep NPO are mostly deposited below the carbonate compensation depth, and thus are subject to extensive dissolution of carbonate. Therefore, the widely used biotic stratigraphy based on calcareous nannofossil is generally inapplicable (Janecek and Rea, 1983; Rea et al., 1993, 1998).
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کلمات کلیدی:
Scientific Application of Baseline Observations of Atmospheric ... https://books.google.com/books?isbn=9400939094 Dieter H. Ehhalt, Graeme Pearman, Ian Galbally - 2012 - Science The measured dust flux in the zone from 40 to 50 N could not be obtained for the ... Thus atmospherically transported Asian dust appears to be a major source of ... The annual dust flux to the North Pacific waters appears to be dominated by ... [PDF]Saharan and Asian dust: similarities and ... - Atmos. Chem. Phys www.atmos-chem-phys.net/11/3263/2011/acp-11-3263-2011.pdf by L Su - 2011 - Cited by 43 - Related articles Apr 5, 2011 - ... and Asian dust transported over the North Pacific Ocean and reach Midway ... dust lifting regions for Asia can be seen from the dust flux. Can Asian dust trigger phytoplankton blooms in the oligotrophic ... onlinelibrary.wiley.com/doi/10.1029/2011GL050415/full by SH Wang - 2012 - Cited by 23 - Related articles Mar 15, 2012 - [3] In this study, we present a satellite perspective on the dust flux and ... The northern SCS is characterized as a sink area of Asian dust [e.g.,Lin et al., .... in the western North Pacific, it was found that Asian dust transported to ... [PDF]Transport of Mineral Aerosol From Asia Over the North Pacific Ocean https://www.rsmas.miami.edu/.../Uematsu_Prospero_SEAREX%20Asian%20dust%20... by RAYL MCDONALD - 1983 - Cited by 651 - Related articles tons of Asian dust are transported annually to the central North Pacific; larger quantities are ...... Estimates of the Mineral Dust Flux Into the North Pacific Ocean*.
