【作者】 尚婷；

【导师】 朱赖民；

【作者基本信息】 西北大学 ， 地球化学， 2008， 硕士

【摘要】 为了对南海和北极海域海洋沉积物物质来源和环境质量状况进行研究,应用地球化学的基本理论和方法,采用现代分析技术手段对南海和北极海域表层沉积物的地球化学特征进行了全面、系统的研究,在此基础上,应用海洋沉积物污染元素评价方法(地质累积指数法和富集因子法)对南海和北极海域海洋沉积环境环境质量状况进行了评价。通过对南海和北极海域海洋表层沉积物地球化学的全面研究,获得如下结论和认识:(1)南海表层沉积物微量元素含量从深海盆区到陆架区呈由大到小的变化规律,与中国大陆沉积物接近,具有明显的“亲陆性”。北极楚科奇海微量元素在中间采样站位值较低,而离陆较近的周围采样站位有着较高的含量,受陆源物质输入影响明显。白令海由于水深较深,各微量元素在其海域的分布较复杂。相关系数分布结果说明沉积物的物源组成较为接近,沉积物在风化迁移过程中所受的分异作用较小,这与研究区的低温环境、化学风化作用弱相一致。(2)南海北部陆架区、中南半岛中东部和加里曼丹岛西北部沿大陆区域稀土元素富集,西南部巽他陆架和东南部岛礁区以及中、西沙附近区域∑REE较低。稀土元素示踪结果表现出“亲陆性”,反映出主要来自陆源。楚科奇海表层沉积物中∑REE的分布,高值区主要分布在海区西南侧、西侧和巴罗角以北海域,低值区重要分布在海区中部;白令海表层沉积物中∑REE的分布,南北两侧较中部采样站位值低。稀土元素物源示踪结果显示,楚科奇海与白令海表层沉积物主要来源于周边大陆;与中国黄土、地壳平均值的对比结果显示,北极地区是处于干冷气候下的以物理风化为主的环境中。(3)南海表层沉积物在深海区中重金属元素的富集,主要与深海盆区样品粒度较细,粘土含量较高有关,反映出“粒度控制率”的一般规律,同时也说明火山物质的加入不是深海盆区重金属富集的主要原因。背景值检验结果表明,大部分海区中污染物含量均落在污染物的背景范围之内。环境质量评价结果表明,在靠近大陆的浅海区分别受到不同程度的非自然来源影响。北极楚科奇海、白令海表层沉积物背景值计算结果表明,楚科奇海和白令海各重金属元素背景值比较接近。重金属评价结果表明,整体上北极楚科奇海与白令海表层沉积物中重金属没有受到人为物质的污染,仍然处于自然变动范围之内。(4)南海表层沉积物铂族元素(PGE)基本上富集于离陆源较近的浅海区,在深海盆区亦表现出一定的富集,尤以Au为最明显,除与深海盆区样品粒度较细,粘土含量较高有关外,幔源物质对南海表层沉积物铂族元素组成有一定的影响。利用深海沉积物对南海全区进行地质累积指数评价结果显示,污染主要分布于靠近大陆的浅海区;用中国东部地壳值进行富集因子计算结果显示,各铂族元素均有着异常高的EF值,明显指示为非陆壳来源,表现为海洋沉积物的自然特征。(5)南海表层沉积物铅同位素继承了扬子块体的铅同位素组成特征,其铅同位素处于红河和湄公河河流沉积物钾长石铅同位素值范围之内,并且中国香港和台湾地区气溶胶对西北部、北部浅海研究区有一定的影响。楚科奇海和白令海铅同位素值在太平洋北部铅同位素值变化范围之内,并且与流入北极拉普捷夫海的西伯利亚东部勒拿河铅同位素平均值接近,太平洋北部尤以对白令海的影响更为明显。(6)南海表层沉积物钕同位素在浅海区∈Nd较小,高值区亦与火山活动相对应,缺乏火山活动的地区存在较高的∈Nd值,可能有火山灰沉降引起。二元混合计算结果表明表层沉积物中以陆源输入为主,(硅铝组分)陆源组分占83%,(基性岩组分)幔源组分占17%,陆源组分高值区主要分布于浅海地带的陆架区,幔源组分高值区主要分布于巴拉望岛西侧深海区,沉积物中火山碎屑的理论分布特征与研究区域内火山灰的实际分布特征相一致。更多还原

【Abstract】 For make a marine sediment research to surface sediments in the South China Sea and Arctic sea area, adopting basic theory and method of geochemistry and modem analytic technique to give a whole and systemic research for the study area.Analysing the geochemistry of contaminated elements in the study area, and then judge the environment quality condition.After those study ,obtaining some conclusion as follows:(1)The trace elements contents of surface sediment in shelf area are higher than those in deep sea area’s in South China Sea,and they are close to the Chinese Mainland sediments’.There is lower trace element concentration in middle sample stations than closing to continent’s in Chukchi Sea.Because of deep water in Bering Sea, there is a complex distribution of trace elements.Correlation coefficient show that the sediments compositon is very near,which consist with its low temperature environment and feeble chemicial weathering.(2)REE enrich in north of sloping continental area, middle east of Indo-China Peninsula and northwest of Kalimantan Island in South China Sea,low content in southwest of Sunda sloping continental area, southeast of island reef area, Xisha and Pratas Islands .REE tracing results show they are mainly terrigenous.EREE distribution of the surface sediments in Chukchi Sea, high-values are mainly located in the southwest area adjacent to the west and north of Point Barrow area, a significant low in the area of Central. DREE distribution of surface sediments in Bering Sea, the central REE values area higher than that two sides’. REE tracing results show that the Bering Sea and Chukchi Sea surface sediments primarily from neighboring mainland . Contrasting with China loess, the average crust results show that the Arctic region is in a dry and cold climate of physical weathering to the Lord’s environment.(3)Heavy metal enrich in the deep sea areas of surface sediments in South China Sea ,mainly because of deep basin area smaller sample size, the higher clay content, reflecting the "granularity rate control", and showing that volcanic material addition in deep basin area is not the main reason for heavy metal accumulation. Background value test results show that the majority of the content of contaminated elements are within the scope of the background. Environmental quality evaluation results show that shallow areas closing to the mainland were subject to different degrees of unnatural sources of influence.Background values calculated results in Arctic show that the heavy metal background values in Chukchi Sea are close to Bering Sea’s.Evaluation results show that heavy metals of surface sediments in Arctic Chukchi Sea and the Bering Sea have not been artificially contaminated, remain within the scope of natural change.(4)Basically, the PGE enrich in the shallow water areas, some concentration in the deep basin area well, particularly for the most obvious Au, in addition to the deep basin area smaller sample size, higher clay content, PGE of the mantle material certainly affect the composition. deep-sea sediments for geologic evaluation results show that pollution mainly distributed in the shallow water near the mainland. Eastern China crust for enrichment factor values calculated results show that the platinum group elements are extremely high with EF values for non-continental crust sources and marine sediment characteristics.(5)Surface sediments in the South China Sea inherited the lead isotope of Yangtze block.Its lead isotope composition within the scope of the Red River and Mekong River K-feldspar lead isotopes . Aerosols Pb isotope values of Hong Kong and Taiwan affect north-west and north shallow water area.Pb isotope values of Chukchi Sea and the Bering Sea are within the scope of northern Pacific’s, and closing to lead isotope average of Lena River’s in eastern Siberia flowing into the Laptev Sea,and north Pacific especially impact on the Bering Sea.(6)Lower (?)Nd is in shallow water areas of surface sediments in South China Sea,and high-value areas are relative to volcanic activity areas. Higher (?)Nd values in lack of volcanic activity regions may be volcanic ash from the settlement. The dual mixed results show that surface sediments are mainly terrigenous, which (alumina components) accounted for 83%, (component-rock) mantle components accounted for 17 %.Land-based component high-value areas mainly distributed in the shallow shelf areas, high-value component of mantle-derived mainly distributed in deep sea basin of West Palawan Island, the theoretical distribution of pyroclastic sediments consist with the actual distribution of volcanic ash.更多还原