湄洲湾表层沉积物中重金属的地球化学特征

根据1984年湄洲湾表层沉积物中重金属的分析资料,讨论了它们的地球化学特征和主要来源。沉积物中重金属的含量(Fe、Mn、Cu、Ni 的质量分数均值分别为3.21%、730×10~(-6)、19.4×10~(-6)、44×10~(-6)分布比较均匀,Pb、Zn 和Co 含量(质量分数均值分别为47.0×10~(-6)、25.8×10~(-6)和243×10~(-6))偏高,微量金属含量不受Fe-Mn 氧化物和有机物控制,本地区的金属来源受陆源输入的影响明显。     

湄州湾沉积物地球化学特征

根据湄州湾表层沉积物70个样品18个化学成分的分析结果,得出:本海区沉积物属于海相陆源物,其中细颗粒主要来自台湾海峡,粗颗粒来自当地陆域;化学成分含量按聚类分析,可归为三组:粘土矿物组、碳酸盐组和分散组,微量元素Zn,Cr,Be,Cu和Sr的含量与地壳及台湾海峡相似,但低于胶州湾,说明该海区污染很少。     

鲁苏榴辉岩的地球化学

以微量元素、稀土元素、Ｓｒ和Ｎｄ同位素变异特征为依据，确定鲁苏榴辉岩为多成因、多来源和多阶段，指出主要是在印支期扬子陆块与华北陆块碰撞造山作用过程中，挤入的上地幔碎片以及不同原岩类型的壳内高压变质岩碎块。燕山晚期的区域构造热事件使得某些榴辉岩的同位素体系再平衡。     

Geochemistry and environment evolution of Core E in the Laizhou Bay since last stage of Middle Pleistocene

IwrincrIONOn the evolution of palcoenvironment, salt-water encroachmnt and the distributionof subsurface brine in the LaizhOu Bay area, many researches had been carried out, and muchknowledge abeut the gcolOgical features in this area since Late QUaternary was aCquired' ) (H8nand Wu, l992; Han and Meng, l994; Wen et al. l989). However there was IittIe studyon the sediment geOChemical characteristics since Quaternary. In this Paper, the element strati-graphic characteristics and evolut…     

Geochemical and hydrodynamic constraints on the distribution of trace metal concentrations in the lagoon of Nouméa, New Caledonia

Seawater samples were collected in the lagoon of Nouméa (southwest New Caledonia) along two transects from eutrophic coastal bays to the oligotrophic barrier reef. Land-based emissions to the lagoon were measured with dissolved and particulate concentrations of chromium (Cr) and nickel (Ni), used as tracers of both terrigenous and industrial (Ni ore treatment) activities, as well as dissolved and particulate concentrations of zinc (Zn), used as a tracer of urban effluents. The spatial variability of metal concentrations was related to geochemical and hydrodynamic conditions, i.e., respectively: (1) natural and anthropogenic emission sources, and chemical processes occurring in the water column; and (2) water residence times. The parameter used to describe the residence time of water masses was the local e-flushing time, i.e. the time required for a tracer mass contained within a given station to be reduced by a factor 1/e. High metal concentrations were found in coastal areas (up to 9000 ng dissolved Ni L⁻¹), and steeply decreased with distance from the coast (down to 101 ng dissolved Ni L⁻¹ near the barrier reef) to reach levels similar to those found in remote Pacific waters, suggesting a rapid renewal of waters close to the barrier. Distributions of metals in the lagoon are controlled upstream by land-based emission sources and later chemical processes. Then hydrodynamics constrain metal distributions, as shown by the observed relationship between local e-flushing times and the spatial variability of metal concentrations. In addition, a change in the direction of prevailing winds yielded a decrease of dissolved metal concentrations at the same site by a factor of 2.5 (Cr and Ni) and 2.9 (Zn). It is suggested that the residence time is a key parameter in the control of elemental concentrations in the lagoon waters, as much as land-based emission sources.     

细菌、病毒与浮游植物相互关系及其对海洋地球化学循环的作用

本文综述了近年来国内外在海洋地球化学循环，特别是微生物环研究方面的发展现状，探讨了浮游植物，细菌，病毒相互之间的关系及其对海洋地球化学循环的影响。     

Retention of arsenic and phosphorus in iron-rich concretions of Tagus salt marshes

Iron-rich concretions are frequently found around plant roots in Tagus estuary (Portugal) where radial delivery of O₂ takes place. Salt marsh sediments exhibit cracks that are an additional feature to introduce O₂ and other solutes in the upper sediments. Metal concentrations in salt marsh sediments are clearly above the background levels reflecting the anthropogenic sources from a large city with 2.5 million inhabitants, and several industrial centres. In order to evaluate how both oxidised structures influences the redistribution of redox sensitive elements in salt marsh sediments, concretions were collected from roots of Halimione portucaloides below the oxygenated zone. These tubular cylindrical structures were analysed for Fe, Al, Mn, As, and P along 1-cm radial transect in a millimetre scale from the inner part to the adjacent anoxic sediment. In addition, oxidised cracks were analysed for the same spatial resolution, from the sediment–water interface to anoxic layers (2-cm transept). The parallelism between Fe, As, and P concentrations at this microscale is the most noticeable aspect. Iron and As presented very high concentrations in the 4-mm concretions (3.4 mmol g⁻¹ and 3.1 μmol g⁻¹, respectively) and decreased sharply to the host sediment. Oxygen released from roots oxidise the solid sulphides, and the reduced Fe and As are transported towards the root by both diffusion and pore water flow associated with the root water uptake. Subsequently, Fe(III) precipitates and As is retained by sorption and/or coprecipitation. These elements are also enriched in the first 2-mm of oxidised cracks, but in lower concentrations (50% and 30%, respectively). Manganese concentrations in concretions were low (11.8 μmol g⁻¹), indicating that Fe dominates the sediment chemistry. Phosphorus and iron concentrations in the ascorbate fraction were higher in the oxidising surfaces of concretions (10.7 μmol g⁻¹ and 1.6 mmol g⁻¹, respectively) and of cracks (5.1 μmol g⁻¹ and 0.47 mmol g⁻¹). The parallelism of Fe and As distributions includes not only their similar redox chemistries, but also that to phosphate, including control by coprecipitation of the host iron phases. The mechanisms involved in the mobilisation of As and P are however different, whereas As comes from the oxidation of iron sulphides; dissolved P derives from reduction of ferri-hydroxide phases.     

Advances in the Study of Geochemistry and Paleo-oceanography of the Co-rich Crust

The current advances in the study of geochemistry and paleo-oceanography of the Co-rich crust are reviewed in this paper. We summarize the study of geochemistry of the Co-rich crust, discuss the diffusion of elements in the Co-rich crust and the exchange with ambient seawater. Besides, we discuss the effect of phosphatization and substrate rocks on the composition of the Co-rich crust. We also introduce the application of stable isotopes (including the stable isotopes of Pb, Nd, and Hf), radioactive isotopes (including the radioactive isotopes of Be, U and Th), and elements (including the major elements, minor elements and rare earth elements) to the study of paleo-oceanography of the Co-rich crust.     

东太平洋沉积物U的地球化学

本文对地矿部“海洋四号”科学考察船１９８７－１９８９年在东赤道太平洋ＣＣ区所取得的２７个深海表层沉积样品进行Ｕ的地球化学分析，探讨了Ｕ在深海沉积中的地球化学行为，结果表明，不同类型沉积的Ｕ含量不同，平均值由大至小的次序的含沸石粘土（２．１６×１０＾－６），硅质粘土（１．９５×１０＾－６），硅质软泥（１．６５×１０＾－６），钙质硅质粘土（１．５９×１０＾－６），在同类型沉积中Ｕ的分散性较大；Ｕ在区域     

南海西沙西南海域表层沉积物特征

西沙西南海域表层沉积物样品矿物成分，地球化学，微体古生物分析测试结果表明：沉积物可分为７种类型，沉积环境主要是陆坡，部分为深海平原，海洋生物，海洋化学以及火山物质的沉积起到了积极的作用，陆源物质的影响较小，它们主要来源于北部大陆和南部岛礁等物源区。