海南岛东南部海湾350年古风暴事件沉积与历史文献记录对比

本项研究试图从沉积记录中分析古风暴事件的时间序列。以海南岛东南部黎安潟湖和新村潟湖钻孔沉积物为研究对象,选取沉积物粒度、有机质和碳酸盐含量等参数建立台风事件的鉴别指标,同时利用放射性核素210Pb计年确定沉积物柱状样的年代序列,对海南岛东南部的古风暴活动进行了分析。结果显示,柱状岩心的粒度指标、有机质和碳酸盐含量清晰地记录了海南省东南部过去350年期间的35次特大风暴潮事件,与历史文献资料对比良好。基于历史文献和沉积记录的风暴潮事件恢复了近350年来的风暴活动历史,发现海南省东南部特大风暴事件频数与厄尔尼诺强度有显著关系,同时还可能受到太平洋涛动和太阳黑子活动等多种因素的综合影响。恢复海岸带地区长时间尺度高分辨率的古风暴记录,为探讨全新世以来古风暴活动的气候响应机制提供了有效信息。     

The potential of contribution of mangrove-derived organic matter in intertidal sediments as a proxy of mangrove development in the northern Beibu Gulf

Located between terrestrial and marine ecosystems, mangrove forests are sensitive to changes in climate. The responses of mangrove ecosystems to climate change in the future can be understood by reconstructing past mangrove dynamics using proxies preserved in the intertidal sediments. Considering the complexity of the proxies commonly used, it is necessary to develop a relatively simple, inexpensive proxy. In this study, available chemical tracers (δ13C_org and C:N) of the four cores (YLW02, YLW03, O18, and Q37) from the intertidal zone of the northern Beibu Gulf (NBG) and a three-end-member (mangrove, sea grass, and suspended particulate matter) model was utilized to determine the contribution of mangrove-derived organic matter (CMOM) in carbonate-free sediments. Compared with the summed concentration of mangrove pollen (SCMP), a significant positive correlation between CMOM and SCMP is displayed. The calculated CMOM for an additional 210Pb-dated sediment core from the Yingluo Bay, NBG (YLW01) clearly indicates a mangrove development going through degradation, flourishing, relative degradation, and relative flourishing, which are separately in correspondence with the lowest, highest, lower, and higher air temperature and rainfall in the time intervals of 1890–1918 AD, 1919–1956 AD, 1957–1990 AD, and 1991–2010 AD. This suggests that CMOM preserved in intertidal sediments has a potential to reconstruct historical mangrove development in high resolution, at the very least, along the coasts of the NBG.     

Evidence for climatic and oceanographic controls on terrigenous sediment supply to the Indian Ocean sector of the Southern Ocean over the past 63,000?years

Multiple proxy studies on sediment core SK 200/22a from the sub-Antarctic sector of the Indian Ocean revealed millennial-scale fluctuations in terrigenous input during the last 63,000?years. The marine isotope stages 1 (MIS 1) and MIS 3 are characterized by generally low concentrations of magnetic minerals, being dominated by fine-grained magnetite and titano-magnetite. Within the chronological constraints, periods of enhanced terrigenous input and calcite productivity over the last 63,000?years are nearly synchronous with the warming events recorded in Antarctic ice cores. An equatorward shift of the westerly wind system in association with a strengthening of the Antarctic Circumpolar Current (ACC) system may have promoted wind-induced shallow-water erosion around oceanic islands, leading to enhanced terrigenous input to the core site. Major ice-rafted debris events at 13?C23, 25?C30, 45?C48 and 55?C58?ka BP are asynchronous with ??¹⁸O and carbonate productivity records. This out-of-phase relation suggests that ice-sheet dynamics and ACC intensity were the primary factors influencing ice rafting and terrigenous input to the Indian sector of the Southern Ocean, with only limited support from sea-surface warming.     

珠江口河流输沙、河口沉积与粒度信息之间的联系

河口三角洲地区泥沙供应充分，是现代沉积速率较高的区域。快速沉积的泥沙包含高分辨率的环境信息。采用放射性同位素测年方法研究了珠江口伶仃洋大铲湾海域6个柱样的现代沉积速率，以2mm的间隔分析了其中2个柱样上部的粒度，并对其平均粒径和珠江流域的年输沙量进行了快速傅里叶变换，以期获取河流泥沙供应、河口沉积速率和沉积物垂向粒度变化的对应关系。结果表明，大铲湾海域的沉积速率为1～3cm／a，受动力条件和泥沙供应条件的影响显著。2个柱样的平均粒径的最显著重现周期与珠江年输沙量的周期性有较好的对应关系，并可能反映了季节的、年的和多年的沉积速率信息。对于每年沉积厚度在厘米级的环境，以毫米级的高分辨率进行粒度分析，有可能揭示出沉积物供应的季节变化和年际变化。本研究亦可为其他河口的相关工作提供借鉴。     

台湾以东黑潮沉积物中的生源要素对近千年来气候环境变化的响应

基于台湾以东黑潮主流系沉积物中碳、氮、磷等生源要素指标的变化,在沉积物年代学的基础上,探讨了近千年来气候环境变化在黑潮沉积物中的历史记录。结果表明,近千年来台湾以东、琉球岛弧南侧斜坡的黑潮主流区平均沉积速率可达34.2 cm/ka,据其变化可大致分成的3个沉积阶段,与中世纪暖期、小冰期和现代暖期的划分基本一致。沉积物中碳以无机碳为主,总无机碳（TIC）的含量从1850年开始逐渐增大并伴随剧烈波动,恰好与大气CO₂水平的快速升高相对应;总有机碳（TOC）含量的变化则与东亚夏季风强度的变化关系密切,在夏季风较弱的小冰期其含量明显高于夏季风较强的中世纪暖期和现代暖期,这是由于较弱的夏季风有利于亚洲大陆风尘的产生和向海输送,从而促进了研究海域的初级生产力。1850年以来,沉积物中的C∶N∶P逐渐从低于转变为高于Redfield比,反映了上层水体营养盐结构从氮缺乏到氮充足的转变,这与近现代以来急剧增加的全球氮排放密切相关。总体来说,黑潮主流系沉积物中的生源要素指标,明确记录和响应了近千年来的气候环境变化,尤其是近150多年以来不断加剧的人类活动所造成的气候环境剧变。     

Hydrothermal Mineralizing Processes and Associated Sedimentation in the Santorini Hydrothermal Embayments

Seven sediment cores from the Palaea and Nea Kameni hydrothermal embayments (PK and NK) on Santorini have been studied by using sediment smear slides, X-ray diffraction, and radiocarbon techniques to determine their lithology, mineralogy, and age, respectively. The cores have been analyzed chemically for a suite of elements, including selective chemical leaching, to determine the partition of elements between coexisting phases. Lithologically and chemically, the sediments from the two embayments are very different. Sediments from PK are oxidized in the upper parts of the cores and reduced at depth; they comprise mainly hydrothermal pyritiferous diatomaceous ooze with minor Fe oxyhydroxide, volcanic debris, gypsum, and siderite. Sediments from NK are oxidized throughout and comprise predominantly amorphous iron oxyhydroxides and goethite; they are thought to have formed by direct precipitation from solution. In PK, biogenic, detrital seawater evaporate, and hydrothermal sediment phases have been identified but only the detrital inputs can be correlated between cores. Mn shows a pronounced enrichment towards the outer part of the embayment because of its dispersion down the embayment and precipitation in the more-oxidizing sediments towards the open sea. In NK, the sediments contain detrital, seawater evaporate, and hydrothermally precipitated and scavenged phases. The presence of substantial amounts of organic matter in the PK sediments but not in the NK sediments is probably the main reason why geochemical processes in the two embayments are different. Age dates obtained from the cores by using the 14 C technique indicate that sedimentation in the PK embayment commenced at approximately 50 AD, whereas in the NK embayment it commenced at approximately 1900 AD, which is consistent with the known history of Santorini. Based on these dates, calculated metal accumulation rates in both embayments are higher than in any other dated hydrothermal metalliferous sediments with the exception of those in the Atlantis II Deep of the Red Sea. Sediment ponding in the embayments is the principal cause of these results.     

昆明滇池沉积速率的测定

于１９８９年１２月采用＾２１０Ｐｂ法测定昆明滇池（草海和外海）两个柱样的沉积速率，其值分别为０．２９ｃｍ／ａ和０．２８ｃｍ／ａ，平均值约为０．２９ｃｍ／ａ。在沉积柱１２ｃｍ以上，由于人为影响，其沉积速率没有规律，估计约有３０－４０年的历史。在１２ｃｍ以下，＾２１０Ｐｂｅｘ随深度的变化明显地表现出规律性，以０．２９ｃｍ／ａ的速率计算，从１２ｃｍ到４０ｃｍ这一段大约有９０年的沉积历史。     

近百年来黄河改道及输沙量变化对山东半岛泥质楔沉积物粒度特征的影响

对山东半岛泥质楔柱状样进行沉积物粒度分析,并在210Pb测年基础上结合黄河年输沙量、悬浮泥沙粒径、河口位置及沿岸流强弱替代指标等数据研究近百年来黄河改道及输沙量变化对远端沉积区沉积特征的影响。研究结果显示,研究区沉积物粒度的变化是黄河入海泥沙特征和沿岸流等水动力作用共同影响的结果。1884–1939年及1947–1999年,研究区沉积物粒度特征的变化主要受到沿岸流强弱的影响;1939–1947年及1999–2012年,受1938–1947年花园口决堤以及20世纪90年代末以来黄河年输沙量持续偏低致使源区泥沙不足的影响,沉积物粒度相对粗化,与沿岸流强度的相关性减弱。与黄河入海泥沙近端沉积区不同,研究区粒度特征对黄河尾闾改道事件不敏感,且对花园口决堤及年输沙量低于临界值的响应有一定程度的延迟,这与该区沉积物经历了再悬浮过程及中间复杂的物质混合有关。黄河改道及输沙量变化仍然是远端沉积区沉积特征演化不可忽视的因素。     

Impact of gamma densitometry on the luminescence signal of quartz grains

Most of the marine sediment cores collected in the past 10 years by the ODP and IMAGES programs have been processed using a multi-sensor core logger (MSCL, Geotek). This system estimates the density of sediment using the γ-ray attenuation of a ¹³⁷Cs source. To date, optically stimulated luminescence (OSL) dating has not been applied to sediments from cores treated in this way, because of the possible impact of this exposure on the existing luminescence signal. We have investigated the effect of such γ-ray irradiation by test exposure, measurement and estimation, and conclude that the usual ¹³⁷Cs exposure from γ-ray attenuation densitometry has no impact on the luminescence signal of quartz grains in sediment cores. For longer exposure to the ¹³⁷Cs source, a formula is provided to calculate the received dose. This result will permit the OSL dating technique to be applied to the voluminous body of marine cores already collected and processed by MSCL.     

Spatial and temporal variations of sedimented organic matter in Xiaohai Lagoon, Hainan Island

The characteristics of grain-size,total organic carbon(TOC) and total nitrogen(TN) contents,TOC/TN ratios,stable carbon isotope(δ13C) and 210 Pb dating were measured in six sediment cores from the Xiaohai Lagoon.The results show distinct spatial and temporal variations in sedimentation patterns.The sediments are dominated by clayey silt,sandy silt and by silty sand in the southern,middle lagoon and the northern lagoon,respectively.TOC and TN contents decline from south to north.Sedimentation rates,determined by 210 Pb dating,tend to decrease from south to middle.However,the determination of sedimentation rate in the north is difficult.These spatial variations are related to the variations in sediment sources and hydrodynamic conditions in the Xiaohai Lagoon.The variations of organic matter signatures can be divided into two stages in the cores from the southern and middle lagoon.Before 1988,the organic matter signatures are relatively stable.The contribution of terrestrial organic carbon sources varies between 60% and 85%.After 1988,the organic matter signatures demonstrate significant variations.TOC and TN contents increase rapidly,TOC/TN ratios decrease,δ13C values shift to higher and the contribution of terrestrial organic carbon sources decreases to 40%-50%.The contributions of phytoplankton organic matter have increased in the sediment since 1988.Increasing aquaculture activities have had a significant impact on organic matter signatures since 1988.The sedimentation rates have increased rapidly in the southern and middle lagoon since 1988 due to the anthropogenic activities which include aquaculture,mining and deforestation.These activities have caused eutrophication and increased siltation in the southern and middle lagoon.     

Hydrothermal Mineralizing Processes and Associated Sedimentation in the Santorini Hydrothermal Embayments

Abstract

Seven sediment cores from the Palaea and Nea Kameni hydrothermal embayments (PK and NK) on Santorini have been studied by using sediment smear slides, X-ray diffraction, and radiocarbon techniques to determine their lithology, mineralogy, and age, respectively. The cores have been analyzed chemically for a suite of elements, including selective chemical leaching, to determine the partition of elements between coexisting phases. Lithologically and chemically, the sediments from the two embayments are very different. Sediments from PK are oxidized in the upper parts of the cores and reduced at depth; they comprise mainly hydrothermal pyritiferous diatomaceous ooze with minor Fe oxyhydroxide, volcanic debris, gypsum, and siderite. Sediments from NK are oxidized throughout and comprise predominantly amorphous iron oxyhydroxides and goethite; they are thought to have formed by direct precipitation from solution. In PK, biogenic, detrital seawater evaporate, and hydrothermal sediment phases have been identified but only the detrital inputs can be correlated between cores. Mn shows a pronounced enrichment towards the outer part of the embayment because of its dispersion down the embayment and precipitation in the more-oxidizing sediments towards the open sea. In NK, the sediments contain detrital, seawater evaporate, and hydrothermally precipitated and scavenged phases. The presence of substantial amounts of organic matter in the PK sediments but not in the NK sediments is probably the main reason why geochemical processes in the two embayments are different.

Age dates obtained from the cores by using the ¹⁴C technique indicate that sedimentation in the PK embayment commenced at ～ 50 AD, whereas in the NK embayment it commenced at ～ 1900 AD, which is consistent with the known history of Santorini. Based on these dates, calculated metal accumulation rates in both embayments are higher than in any other dated hydrothermal metalliferous sediments with the exception of those in the Atlantis II Deep of the Red Sea. Sediment ponding in the embayments is the principal cause of these results.     

厦门大嶝海域柱样沉积物中微体古生物特征及其地质意义

本文分析测定了福建厦门大嶝海域三个沉积物柱样中的了孢粉、硅藻、有孔虫和＾１４Ｃ年代，对其微体古生物组合特征，沉积环境和地层年代进行了初步的探讨。划分出两个孢粉带，即下部的栎属－蕨类带和上部的松属－蕨类－禾本科带，表明自下而上气候由热湿变为暖干。硅藻以柱状小环藻－具槽直链藻组合为代表，有孔虫组合则以毕克卷转虫占优势，表明为近岸浅水环境，但柱样上下有些差异。     

Can beach dune ridges of the Texas Gulf Coast preserve climate signals?

A study of the evolution of North Padre Island (southern Texas Gulf Coast) dunes was carried out using LIDAR topographic data, dune vibracores through the center of the dunes, and grab samples of shoreface sand at four locations along a cross-shore profile. Grain-size analyses of the vibracores show vertical variations in shoreface sand deposition over decimeter depth intervals. A dune ridge growth model is introduced that describes the dune vertical accretion rate as a function of island progradation and freshwater lens expansion. This model allows indirect dating of the dune core samples based on a known island progradation rate (1?m/year), and height and spacing of the dunes calculated from the topographic data. A sand provenance model is also proposed that links the sand deposition in the dunes with sand sourced from various depths along the shoreface profile, depending on storm activity. We present evidence linking the changes in storm-sand deposition in the dune cores with yearly climatic fluctuations in the Gulf of Mexico associated with landfalling tropical storm activity in the period from 1942?C1965. This record of storm-induced sand variability is negatively correlated with El Ni?o-Southern Oscillation (Pacific) sea surface temperature variability, and positively correlated with North Atlantic decadal sea surface temperature variability.     

珠江口淇澳岛滨海湿地沉积环境演化及其对人类活动的响应

滨海湿地作为人类活动和全球变化反应最为敏感的区域,其沉积记录可以反映出周边地区环境变化及人类活动信息。珠江口淇澳岛滨海湿地钻孔分析结果表明,在中全新世期间淇澳岛附近海域为河口湾环境,在风化层以上开始出现淤积,但在4 200 a BP前后受极冷气候的影响,沉积物粗化;自2 500 a BP以来,沉积环境相对稳定,在小冰期期间略有变化。沉积速率计算结果显示:淇澳岛附近海域自中全新世高海面以来的平均沉积速率为0.29 cm/a,4 160~2 500 a BP、2 500 a BP-1488年、1488-1893年、1893-1986年、1990-2007年期间的平均沉积速率分别为:0.17 cm/a、0.23 cm/a、0.35 cm/a、1.37 cm/a和5.94 cm/a,沉积速率逐渐增大,反映了珠江三角洲演化过程中沉积相与沉积环境的变化;1986-1990年期间的海堤建造极大地扰动了该钻孔上部的沉积过程,在工程施工期间共沉积了厚度约112 cm的沉积层,而在海堤建成后,沉积速率也显著增大。沉积物总有机碳、总氮和C/N值的垂向分布表明,在4 160~2 500 a BP期间受海洋环境影响较大,沉积物中有机碳以海源为主,2 500 a BP以来沉积物中碳、氮含量明显增大,C/N也相应变大,有机碳主要来源于陆源输入,但在小冰期期间海源有机碳贡献略有所增大;近百年来由于受人类活动影响显著,陆源有机碳的贡献快速增加。     

Tracking historical storm records from high-barrier lagoon deposits on the southeastern coast of Hainan Island,China

The relationship between storm activity and global warming remains uncertain. To better understand storm–climate relationships, coastal lagoon deposits are increasingly being investigated because they could provide high-resolution storm records long enough to cover past climate changes. However, site-specific sediment dynamics and high barriers may bias storm reconstructions. Here, we aimed to investigate these factors through the reconstruction of five distinct storm records (XCL-01, XC-03, XC-06, XC-07, XC-08) from different water depths in a lagoon with a high barrier (i.e., Xincun Lagoon of Hainan Island). Sediment cores were characterized using high-resolution grain size and XRF measurements, to identify storm events. These data were coupled with a numerical simulation to obtain bed shear stress data with high-spatial resolution to better understand storm-induced sediment transport mechanisms. 210Pb dating and Pb pollution chronostratigraphic markers indicated that the chronology of the storm deposit sequences of the cores span the period between 117 a and 348 a. The grain size and XRF results indicated numerous, highly variable and short-duration fluctuations, suggesting that storm-induced coarse-grained sediments were deposited at these core sites. The inconsistent storm events recorded in these cores suggest that these sites have different preservation potentials for storm deposits. However, the consistence between storm sediment records and historical documents for Core XCL-01 indicates that high-barrier lagoons could provide long-term storm event records with high preservation potential.     

中国西南广西英罗湾红树林近130年来演化指标——沉积物中的红树叶片亚化石

Located in the intertidal zone of the tropical and subtropical coasts, mangrove forests are an important ecosystem in the global carbon cycle and serve as a protector of local seashores. Under the double impacts of climate change,especially sea-level rise, and human activity, mangrove forests around the world have faced degradation, against which the reconstruction of the historical development of mangrove forests using an effective indicator has been regarded as a necessary strategy for designing a predictable model. As the primary product of mangrove forest, it is reasonable that the content of leaf fragments of mangrove(CLFM) buried in sediments in the form of sub-fossils potentially has the same indicative function for the development of mangrove forests as that of widely-used mangrove pollen. In this study, the leaf fragments of mangrove in two sediment cores(YLW02 and YLW03) drilled in the Yingluo Bay in Guangxi, Southwest China were picked out and weighted for calculation of CLFM, which was used as an indicator of mangrove development after examination of parallelism and a statistical correlation of the CLFM with the concentration of mangrove pollen. The results clearly show that the vertical distribution of the CLFM for the core taken from the landward margin of mangrove forests(YLW03) only parallels that of the local mangrove species(Rhizophora. stylosa) with a significantly positive correlation(R=0.56, P=0.05), while the vertical distribution of the CLFM for the core taken from the interface between seaward margin of mangrove forest and the trunk of tidal creeks of the bay(YLW02) parallels the summed concentration of mangrove pollen(SCMP) with a more positive correlation than that of YLW03(R=0.85, P=0.01), indicating that the trunk outlet of tidal creeks must have been the site where mangrove production gathered from the overall forest rather than from local production. The variations in the CLFM of both cores indicate that overall the mangrove forests in the Yingluo Bay have increasingly flourished over the last 130 years except for the interval of 1940–1950 AD in response to an increase in air temperature and decrease in rainfall, which would have resulted in an increase in seawater salinity;while the coupled extreme increases in air temperature and in rainfall in summer, which would have resulted in extreme decreases in seawater salinity, would be responsible for the relative degradation of mangrove forests in the interval of 1940–1950 AD.     

Control of incised-valley fill stacking patterns by accelerated and decelerated sea-level rise: the Changjiang example during the last deglaciation

The evolution of paleo-Changjiang incised-valley fills in relation to step-like, postglacial sea-level rises is presented, based on sedimentary facies analyses and ¹⁴C age dating on three sediment cores. Timing of rapid transgressions deduced from the succession of incised-valley fills correlate well with Barbados's very rapid, sea-level rise periods. By contrast, estuarine deposits aggraded actively, and the coastline did not retreat markedly during the Younger Dryas (YD) cooling event when the rising rate decelerated considerably relative to stages before and after the YD.     

Long-term variability of oceanic frontal zones associated with large-scale atmospheric forcing

Global satellite sea surface temperature (SST) measurements and NCEP/NCAR reanalysis wind data for the period of 1982–2009 have been used to study the relationship between long-term variability of oceanic frontal zones (OFZ) and large-scale atmospheric forcing. Statistically significant positive correlations between the maximum magnitude of the meridional gradient of zonally averaged SST and meridional shear of zonal wind (which is an estimate of the Ekman convergence intensity) were found for all subpolar and subtropical OFZ of the World Ocean. Variability of the latitudinal position of OFZ cores may be associated with Ekman advection variability due to zonal wind variations. Strengthening of zonal wind results in a shift of subpolar OFZ cores to the south/north in the Northern/Southern hemispheres.     

Laminated sediments from the central Peruvian continental slope: A 500 year record of upwelling system productivity, terrestrial runoff and redox conditions

Sedimentological studies including X-ray digital analyses, mineralogy, inorganic contents, and organic geochemistry on cores of laminated sediments accumulated in the oxygen minimum zone of the central Peruvian margin reveal variable oceanographic and climate conditions during the last 500 yr. Coherent upcore variations in sedimentological and geochemical markers in box cores taken off Pisco (B0405-6) and Callao (B0405-13) indicate that variability in the climate proxies examined has regional significance. Most noteworthy is a large shift in proxies at 1820 AD, as determined by ²¹⁰Pb and ¹⁴C radiometric dating. This shift is characterized by an increase in total organic carbon (TOC) in parallel with an abrupt increase in the enrichment factor for molybdenum Mo indicating a regional intensification of redox conditions, at least at the sediment water interface. In addition there was lower terrestrial input of quartz, feldspar and clays to the margin. Based on these results, we interpret that during several centuries prior to 1820, which corresponds to the little ice age (LIA), the northern Humboldt current region was less productive and experienced higher terrestrial input related to more humid conditions on the continent. These conditions were probably caused by a southward displacement of the inter-tropical convergence zone and the subtropical high pressure cell during the LIA. Since 1870, increases in TOC and terrigenous mineral fluxes suggest an increase of wind-driven upwelling and higher productivity. These conditions continued to intensify during the late 20th century, as shown by instrumental records of wind forcing.     

赣北黄茅潭近代湖泊~(137)Cs蓄积特点、SCP计数和事件性沉积及其对~(210)Pb计年的矫正

对赣北黄茅潭近代湖泊沉积岩芯进行了~(137)Cs、~(210)Pb测试和SCP(球状碳粒)计数分析,阐述了~(137)Cs蓄积特征,结合SCP计数、粒度指标及降水记录厘定了一些事件性沉积层位。研究表明,1986年前后是沉积环境中~(137)Cs行为的转折点;在这之前,~(137)Cs以大气散落为主,其蓄积行为大致与降水存在正相关关系,在这之后,~(137)Cs以流域侵蚀为主,其蓄积行为与降水呈负相关关系。1953—1954年、1974—1975年、1998—1999年,流域降水丰沛,相应沉积层位~(137)Cs比活度低,这与流域强烈侵蚀稀释了进入湖泊的~(137)Cs有关。1963—1964年沉积层位~(137)Cs蓄积峰稳定而显著,与高通量的大气散落有关,也与当时降水量低,大雨、暴雨次数少,流域侵蚀强度低造成较低的沉积速率等密切相关,是可靠的定年时标。1986年存在同样的气候环境特点,其蓄积峰可能也是存在的,但需要进一步确认。基于~(210)Pb方法,利用多种计年模式计算了沉积岩芯的年代,发现与这些事件性沉积层位具有较大差异。研究认为,在长江中游这种降水高、流域侵蚀强度高的较为复杂的沉积环境中,~(210)Pb计年存在较大误差。复杂沉积环境中近代沉积的定年,有必要深度挖掘~(137)Cs环境行为,在全面阐述其蓄积特点的基础上,辅以SCP计数、粒度指标及降水等识别事件性沉积层位,矫正~(210)Pb计年,是精确建立近代沉积时标的必要方法。