南海沉积物中的放射虫及其古环境意义

In this paper a systematic study of radiolarian from surface sediments of all the South China Sea (SCS) has initially been done for its deposit ecology, biogeography and paleoenvironment significance. The paleoenvironment information obtained by radiolarian analysis and other sedimentary method for core samples is also made use as the synthesis proxy for revealing the paleoenvironment changes in the SCS and the relations of it with the past globe change during last 200ka. Some results come out of this study as: 1) Radiolarian skeleton chemistry composition and skeleton morphological features were analyzed, chiefly dividing them as 15 types of basic morphological features: 2) Analysis of biogeographical feature demonstrates that the fauna in SCS obviously belonging to a transitional type of west Pacific - Indian Ocean and has a particularity of itself: 3) Tendency of radiolarian population distribution is lower in shallow continental shelf area, increasing gradually toward the abyssal region; 4) Nine character boundaries of radiolarian depth distribution in the sediments from whole the South China Sea may be recognized; 5)Two radiolarian transfer functions for paleotemperature and paleo-primary productivity in the South China Sea have also been established respectively. The equation of transfer function for winter paleotemperature has only an average estimated error of 0.18678 ℃ and the equation for paleo-primary productivity has the calculation accuracy of 85.31%; 6) Changes of radiolarian individuals, numbers of species and H(S) values in core NS93-5 show the completely different oceanic geographical circumstance and ecology structure in the Last Maximum Glacial with present; 7) The abundance variation of some raiolarian warm species and cold species indicate the changes of water masse features along with the paleoenvironment evolution, showing that this sea area clearly is controlled in 6 issues of oxygen isotopes by the cold water masses; 8) By comparative analysis of δ ~(18)O curves with GISP2;s ice core can core 17940 of the northern SCS, the occurring characters of D/O's events 1-21 and Heinrich's events H1-H6 have been revealed in this sea area by core NS93-5, which prove the existence of paleoclimatic tele-connections between the southern SCS and Arctic region since about 200ka BP.

珠穆朗玛峰东绒布冰川表层雪中的气候和环境记录

Snow chemistry research helps to found the basis of studying ice cores. Samples of fresh snow and snow pits were collected from East Rongbuk Glacier on the north slope of Mt. Qomolangma during October, 2002. Major soluble ions (Na~+, NH_4~+, K~+, Mg~(2+), Ca~(2+), Cl~-, NO_3~- and SO_4~(2-)) andδ~(18)O were detected for analysis. Source analysis showed that major sources contributing to the snow chemistry in Mt. Qomolangma region are remote Asian dust and salt lake dust, sea-salt aerosols from Indian monsoon, local rock-mineral dust, human activities and natural atmospheric procedures. Principal factor analysis indicated that high-concentration group was dominated by continental dust with little oceanic source, indicating continental or local precipitation, while the low group dominated by oceanic aerosols indicated oceanic precipitation. Local mineral dust was a minor a source characterized mainly by Ca~(2+), Mg~(2+) contribution. Ammonia related mainly with continental dusts and nitrogen-circulation processes in the atmosphere, it also had a peculiar source should be seasonal agriculture activities in the south Asia. Nitrate showed bad correlations with other ions for its special chemical characteristics. δ~(18)O and major soluble ions displayed obvious seasonal variations. The summer precipitation had very low ion loadings and relatively lower heavy oxygen isotope from the Indian Ocean with occasionally ion peaks formed by local evaporation. While the winter and spring precipitation had high ion loadings and δ~(18)O value for the great amount of continental dust and evaporated vapors. Frequent fluctuations of δ~(18)O and ion concentration occur during the transitional period, indicating alternated precipitations by various air mass types. Ion concentration in snow from the Qomolangma region is comparable with from the Antactica, representing relatively pure background of atmospheric environment on earth. While the high concentration is close to the glaciers' located near the major sources of Asian dust. Compared with the snow chemistry of South Slope of Mt. Qomolangma, the North Slope has lower sea-salt ion concentration during summer monsoon and higher concentration of all major ions during pre- and post-monsoon period due to it's special geophysical location.

单种属泥炭纤维素碳稳定同位素组成与全新世青藏高原东部西南季风变化

泥炭的形成和积累主要受控于气候，其次是地质、地貌和水文等因素。作为一种重要和理想的气候信息载体，泥炭己经与冰芯、海洋及湖泊沉积、黄土堆积、洞穴碳酸盐沉积、树轮和珊瑚礁等其它类型的自然地质档案一样，逐渐为国内外致力于古气候变化研究的学者所接受，并将其重点应用于全新世以来气候变化信息的提取。本研究在已有的泥炭混合植物残体纤维素碳稳定同位素记录青藏高原东部地区气候信息的基础上，首次提取泥炭中单一种属植物残体一木里苔草（Calexmulieensis）纤维素，测定其碳稳定同位素，并以其时间序列作为一种新的西南季风代用指标，揭示该区域全新世以来气候变化。研究表明：1．木里苔草的碳稳定同位素时间序列是西南季风强度变化的敏感代用指标。约11800～11加0 cal aBP期间，木里苔草纤维素的613C记录处于最大值，表明该时段西南季风活动鼻弱，气候干冷，对应于普遍发生并存在的新仙女木事件；它清晰地指示了该区全新世的下限年龄为约11200 cal aBP（14c年龄约9900aB玲从约11200 oal aBP起该区迅速进入湿暖的全新世阶段，季风活动迅速增强；在约10800～5500 cal aBP期间，季风总体保持在强盛状态，但其间有4次突然减弱，气候变干冷；约从5500 cala即起季风活动在波动中逐渐减弱，其中有4次减弱最为明显。2．木里苔草纤维素碳同位素所记录的犯000年以来的所有9次西南季风活动的突然减弱与同时期北大西洋发生的冰力｝漂移碎屑沉积物事件（IRD事件）一一对应。这种密切的相关关系表明，西南季风强度的波动可能是对全球气候变化特别是对海洋热盐环流引起的地球南北方气撇动变化的响应。3．木里苔草纤维素碳稳定同位素所指示的西南季风有952，乓57，475，312，211和77年等一系列周期。其中557年和77年两个周期分别与北大西洋深层海水环流的550年的周期和76年的气候周期非常吻合。这表明西南季风与北大西洋气候间有很好的相关关系。由于557年和77年的季风周期又都分别类似于53。年和80年的太阳活动周期，这表明太阳活动可能对西南季风和北大西洋气候间的联系有着影响。4．红原泥炭木里苔草纤维素和泥炭混合纤维素别3c时间序列在千年至万年时间尺度上的变化趋势很相近。两种代用记录都一致反映了冰后期的气候变化，即均指示西南季风强度变化可分为三个明显的大阶段。这说明它们对过去12000年的西南季风变化具有相同的响应。对于目前经过较详细研究的那些全球大范围发生的突然气候变化事件，木里苔草纤维素δ~(13)C代用记录与泥炭混合纤维素δ~(13)C代用记录一样，都有相同的响应，但是，相对于泥炭中单一的木里苔草敏感地记录到历次北大西洋I劝事件而言，泥炭混合纤维素δ~(13)C记录对其中的几次突然气候变化事件似乎没有表现出明显的响应。这个结果表明对数百年尺度的突然气候变化，木里苔草纤维素比混合纤维素的酬3c指标似乎要更敏感一点。因此，在能获得足够数量的单种植物·残体的情况下，单种植物残体纤维素的δ~(13)C指标有很好的使用价值。