植物硅酸体化学成分的研究

植物硅酸化学在分的研究,在植物学和地质学中都有重要意义,前者是为了研究不同化学元素在植物生理,生化中的作用;后者是了解不同植物硅酸体中Ｃ与Ｏ元素的含量,为利用硅酸体进行年代学研究,进行Ｃ与Ｏ同位素及古环境研究提供依据,本文除对硅酸体化学成分的重要意义进行阐述外,并研究了１６个种属植物硅酸体的化学成分,将为硅酸体研究在我国的应用提供有意义的科学依据。     

植物硅酸体AMS^14C测年和同位素分析

在现代植物和地层样品的植物硅酸体中，封闭了一部分原来植物细胞的有机物质可以用于ＡＭＳ＾１４Ｃ（加速器质谱计＾１４Ｃ测年）和碳同位素分析。而且植物硅酸体本身所含有的氧、氢同位素与植物生长环境中的氧、氢同位素有直接的关系，可以利用植物硅酸体氧、氢同位素进行古环境分析。它的最大的优势还在于可以高分辩率、连续地从黄土剖面中获取植物硅酸体化，本有可能成为类似于利用深海有孔虫进行氧同位素天空的新的陆地生物化石     

太湖水体有机污染与主要环境因子的响应

根据１９８７－１９８８年有关研究资料，分析太湖ＣＯＤ，ＢＯＤ５和ＴＯＮ的时空变化及其与ＴＯＣ的关系，研究ＣＯＤ出入湖量和水文气象因子对湖体ＣＯＤ的影响。结果表明，ＣＯＤ是太湖有机污染的重要指标；在不同时期和湖区，其含量差异明显，丰水期低，枯水期高。各湖区污染排列为：五里湖＞梅梁湖＞湖心区＞东太湖。进入太湖有机物量的增减，是ＣＯＤ在湖体中消长的主导因素，但水位和温度等条件因子对有机污染程度亦有重要曩     

植物硅酸体研究在我国海洋地质学中的应用

对海岸带、浅海、半深海现代及第四纪沉积物进行的植物硅酸体研究表明,植物硅酸体可以在恢复海洋古气候、古环境的研究工作中发挥重要作用,不但可用于解决一些哑地层中的相关问题,在时间尺度上其分辨率也是较高的.     

植物硅酸体的研究及在我国第四纪地质学中的初步应用

本文简述了国外植物硅酸体(植物蛋白石)这门新兴学科的进展情况,介绍了植物硅酸体研究在我国第四纪地质学中如古气候与古环境、地层时代、考古等方面的初步应用。     

东海嵊山岛风尘黄土中的植物硅酸体与环境研究

东海岛屿风尘黄土地层的存在是下蜀黄土在东部的继续与延伸，红外释光测年（IRSL）表明，东海嵊山岛黄土剖面形成年代约为50－10kaBP，即形成于晚更新世末次冰期期间；植物硅酸体分析发现该剖面样品含有丰富的禾本科植物硅酸体化石，且在剖面中变化较大，在对植物硅酸体进行分类的基础上，运用了判别分析、冷暖比值判别和古植被类型判别的方法，对植物硅酸体所反映的古环境进行了分析，将岛屿风尘地层中的植物硅酸体划分为7个变化阶段，反映了岛屿黄土堆积期的7次气候变化过程，探讨了该地区末次冰期期间古环境、古气候变迁特征，发现该剖面沉积期间主要为干冷的草原环境且经过了一系列冷－暖气候变迁。     

我国第四纪海陆相地层中盾形化石的亲缘关系及环境意义

本文研究认为,我国海陆相地层中常见的盾形化石是植物硅酸体众多形态中的一种类型。并对盾形化石的生理、生态意义进行了讨论。     

藻类光合固碳的研究技术与解析方法

藻类的光合固碳构成水域初级生产力的基础。藻类固碳的研究是藻类生理生态学的重要部分,对认识藻类在水域物质循环中的作用有重要意义。特别是近年来大气ＣＯ_２浓度升高与水域生物圈的关系倍受关注;大气ＣＯ_２浓度升高是否会通过影响水域中无机碳浓度和ｐＨ影响水域生态系统,藻类的光合固碳对大气ＣＯ_２浓度的作用如何等是目前科学界所关心的问题。因此,研究ＣＯ_２浓度变化与藻类的关系十分重要。开展此研究的基础是藻类固碳的研究技术与解析方法。尽管有关藻类光合作用以及固碳特性的研究已有很长的历史,但是目前尚没有任何专业书…     

植物硅酸体的研究及应用简介

本文综述了植物硅酸体及其化石的研究概况,以及它在恢复古环境中的应用。     

海水中溶解有机碳测定方法评述

海水中的有机物主要是以溶解形式存在的,溶解有机碳（ＤＯＣ）在全球碳循环中有重要的作用,对于化学海洋学和生物海洋学的研究具有十分重要的意义。Ｓｕｇｉｍｕｒａ和Ｓｕｚｕｋｉ１９８８年用高温催化氧化法（ＨＴＣＯ）测定海水中的溶解有机碳（ＤＯＣ）得到的测定数据比过去传统方法的高２～４倍,这一结果在海洋学界引起人们极大兴趣。然而在１９９１年国际ＤＯＣ测定互校工作后,Ｓｕｚｕｋｉ修订了他早期的工作。近几年来,通过对ＤＯＣ测定方法的重新评价,结果发现用高温催化氧化法和传统的湿氧化法测得的ＤＯＣ数据相似,但下面…     

Nitrate isotope dynamics in the lower euphotic-upper mesopelagic zones of the western South China Sea

The dual isotopes(N and O) of nitrate were measured using a denitrifier bacterial method in the western South China Sea(WSCS) during September 2015 to elucidate key information during N transformation in the lower euphotic zone(LEZ)-upper mesopelagic zone(UMZ,down to 500 m in this study) continuum,which is a vital sub-environment for marine N cycle and sequestration of atmospheric CO₂ as well.The N isotopic composition(δ¹⁵N) of nitrate generally decreased from 500 m toward ...     

Authigenic minerals from the Paola Ridge (southern Tyrrhenian Sea): Evidences of episodic methane seepage

Paola Ridge, along the NW Calabrian margin (southern Tyrrhenian Sea), is one of the few reported deep sea sites of precipitation of authigenic carbonates in the Tyrrhenian Sea. Here, the changing composition of the seeping fluids and the dynamic nature of the seepage induced the precipitation of pyrite, siderite and other carbonate phases. The occurrence of this array of authigenic precipitates is thought to be related to fluctuation of the sulfate-methane transition zone (SMTZ).Concretions of authigenic minerals formed in the near sub-bottom sediments of the Paola Ridge were investigated for their geochemical and isotopic composition. These concretions were collected in an area characterized by the presence of two alleged mud volcanoes and three mud diapirs. The mud diapirs are dotted by pockmarks and dissected by normal faults, and are known for having been a site of fluid seepage for at least the past 40 kyrs. Present-day venting activity occurs alongside the two alleged mud volcanoes and is dominated by CO₂-rich discharging fluids. This discover led us to question the hypothesis of the mud volcanoes and investigate the origin of the fluids in each different domed structure of the study area.In this study, we used stable isotopes (carbon and oxygen) of carbonates coupled with rare earth element (REE) composition of different carbonate and non-carbonate phases for tracing fluid composition and early diagenesis of authigenic precipitates. The analyses on authigenic precipitates were coupled with chemical investigation of venting gas and sea-water.Authigenic calcite/aragonite concretions, from surficial sediments on diapiric structures, have depleted ¹³C isotopic composition and slightly positive δ¹⁸O values. By contrast, siderite concretions, generally found within the first 6 m of sediments on the alleged mud volcanoes, yielded positive δ¹³C and δ¹⁸O values. The siderite REE pattern shows consistent LREE (light REE) fractionation, MREE (medium REE) enrichment and positive Gd and La anomalies. As shown by the REE distribution, the ¹³C-depleted composition and their association with chemosymbiotic fauna, calcite/aragonite precipitated at time of moderate to high methane flux close to the seafloor, under the influence of bottom seawater. Authigenic siderite, on the other hand, formed in the subseafloor, during periods of lower gas discharges under prolonged anoxic conditions within sediments in equilibrium with ¹³C-rich dissolved inorganic carbon (DIC) and ¹⁸O-rich water, likely related to methanogenesis and intermittent venting of deep-sourced CO₂.     

Isotope paleontology: growth and composition of extant calcareous species

Isotope paleontology uses the isotopic composition of fossil remains of organisms to make inferences about the physical surroundings of growth of the organisms (especially temperature), and to obtain clues about life history and modes of growth. In calcareous fossils, oxygen isotopes are mainly used in the former, and carbon isotopes in the latter. However, since physical surroundings and organism response are intimately associated, both types of information are contained in each of the isotopic signals. To explore the potential of isotope paleontology, and to provide a basis for reconstruction, a broad range of extant organisms has been studied, taking the pioneering work of Epstein and associates as a starting point. Results are summarized for a representative sampling of these studies, with emphasis on work at the laboratories of the authors, from the mid-seventies to the present. The organisms considered are nannoplankton, benthic algae, planktonic and benthic deep-sea foraminifera, “larger” foraminifera, sponges, corals, bryozoans, polychaetes, arthropods, bivalves, gastropods, cephalopods, and vertebrates (fish otoliths). The survey broadly suggests that, regarding oxygen isotopes, materials tend to be precipitated close to equilibrium with the surrounding seawater (as postulated by Urey), and that for carbon isotopes disequilibrium is the rule. Life spans, growth rates, differential seasonal growth, and age of reproductive activity can be extracted under favorable circumstances from individual shells and skeletal parts. In detail, the interpretation of isotope records of individual shells is quite complicated, and simple models will fail to give satisfactory results in many or most cases.     

Characteristics of silicon and oxygen isotopic compositions of basalts near East Pacific Rise 13°N

In this study, 13 groups of silicon and oxygen isotopes and major elements of the basalts near the East Pacific Rise 13°N are used to study the fractionation of silicon and oxygen isotopes. Among these data, δ30Si values of basalts vary from -0.4%o to 0.2%o with a mean value of δ30Si of （-0.18±0.22）%o. The δ180 values range from 4.1%o to 6.4%o with a mean δ180 value of （＋5.35±0.73） %0. Since the δ30Si values increase in the series of basalt-basaltic andesite- andesite, and δ180 values display a positive correlation with the SiO2 content, we propose that the fractionation of silicon and oxygen isotopes is influenced by the SiO2 content in igneous rocks. Compared with the igneous rocks from Manus Basin with clinopyroxene as their dominant mineral phase, MORBs in this study containing olivine and plagioclase as primary minerals have lower δ180 and δ30Si values, indicating that the fractionation of silicon and oxygen isotopes is also affected by different Si-O bridges in silicate minerals. Furthermore, our samples from the EPR are defined as E-MORB based on K/Ti ratios. Probably, the difference in δ30Si and δ30O between our samples and a normal MORB are cause by the enriched components in E-MORBs.     

Reactivity of dolomitizing fluids and Mg source evaluation of fault-controlled dolomitization at the Benicàssim outcrop analogue (Maestrat basin,E Spain)

The mechanisms responsible for the formation of huge volumes of dolomitized rocks associated with faults are not well understood. We present a case study for high-temperature dolomitization of an Early Cretaceous (Aptian–Albian) ramp in Benicàssim (Maestrat basin, E Spain). In this area, seismic-scale fault-controlled stratabound dolostone bodies extend over several kilometres away from large-scale faults. This work aims at evaluating different Mg sources for dolomitization, estimating the reactivity of dolomitizing fluids at variable temperature and quantifying the required versus available fluid volumes to account for the Benicàssim dolostones. Field relationships, stable ¹³C and ¹⁸O isotopes, as well as radiogenic ⁸⁷Sr/⁸⁶Sr isotopes, indicate that dolomitization at Benicàssim was produced by a high-temperature fluid (>80 °C). ¹³C and ¹⁸O isotopic compositions for dolomite vary from +0.5 to +2.9‰ V-PDB and from +21.1 to +24.3 V-SMOW, respectively. A Mg source analysis reveals that the most likely dolomitizing fluid was seawater-derived brine that interacted with underlying Triassic red beds and the Paleozoic basement. Geochemical models suggest that evolved seawater can be considerably more reactive than high-salinity brines, and the maximum reactivity occurs at about 100 °C. Mass-balance calculations indicate that interstitial fluids with high pressure and/or high temperature relative to the normal geothermal gradient cannot account for the volume of dolomite at Benicàssim. Instead a pervasive fluid circulation mechanism, like thermal convection, is required to provide a sufficient volume of dolomitizing fluid, which most likely occurred during the Late Cretaceous post-rift stage of the Maestrat basin. This study illustrates the importance of fluid budget quantification to critically evaluate genetic models for dolomitization and other diagenetic processes.     

Fluid sources and stable isotope signatures in authigenic carbonates from the Northern Apennines,Italy

Authigenic carbonates are frequently associated with methane cold-seep systems, which extensively occur in various geologic settings worldwide. Of interest is the relation between the fluids involved in their formation and the isotopic signals recorded in the carbonate cements. Along the Northern Apennines foothills (Italy), hydrocarbons and connate waters still seeping nowadays are believed to be the primary sources for the formation of fossil authigenic carbonate found in Plio-Pleistocene marine sediments. Four selected outcrops of dolomitic authigenic carbonates were analysed to compare signature of seeping fluids with fractionation of stable carbon and oxygen isotopes recorded in the carbonate.Along the foothills, deep methane-rich fluids spontaneously rise to the surface through mud volcanoes or are exploited in wells drilled nearby to the fossil Plio-Pleistocene authigenic carbonates. The plumbing system providing fluids to present-day cold seeps was structurally achieved in Late Miocene and Plio-Pleistocene. δ¹³C values of methane, which vary from −51.9 to −43.0‰ VPDB, indicate that gas composition from the deep hydrocarbon reservoirs is relatively uniform along the foothills. On the contrary, δ¹³C in fossil authigenic carbonates strongly varies among different areas and also within the same outcrop.The different carbon sources that fed the investigated carbonates were identified and include: thermogenic methane from the deep Miocene reservoirs, ¹³C-enriched CO₂ derived from secondary methanogenesis and microbial methane from Pliocene successions buried in the Po Plain. The δ¹³C variability documented among samples from a single outcrop testifies that the authigenic carbonates might represent a record of varying biogeochemical processes in the hydrocarbon reservoirs. The sources of stable oxygen isotopes in authigenic carbonates are often ascribed to marine water. Oxygen isotopic fractionation in the dolomite cements indicates that marine pore water couldn't be the sole source of oxygen. δ¹⁸O values provide a preliminary evidence that connate waters had a role in the carbonates precipitation. The concomitant occurrence of active cold seepages and fossil record of former plumbing systems suggests that generation and migration of hydrocarbons are long-lasting and very effective processes along the Northern Apennines foothills.     

WebGIS技术在海洋地质领域中的应用

WebGIS是指利用World Wide Web向各种类型的用户提供地理空间信息服务的地理信息系统,是Internet与GIS结合的产物,通过向用户提供多样化的、直观易懂的图形用户界面,来动态地客户化地表现数据。在海洋地质领域中WebGIS主要应用于海洋地质图件的管理、发布以及海洋地质调查船的实时动态监控。随着全国海洋地质资源信息化的发展,WebGIS在海洋地质领域将拥有良好的应用前景。     

Growth of the European abalone (Haliotis tuberculata L.) in situ: Seasonality and ageing using stable oxygen isotopes

The ormer, Haliotis tuberculata is the only European abalone species commercially exploited. The determination of growth and age in the wild is an important tool for fisheries and aquaculture management. However, the ageing technique used in the past in the field is unreliable. The stable oxygen isotope composition (¹⁸O/¹⁶O) of the shell depends on the temperature and oxygen isotope composition of the ambient sea water. The stable oxygen isotope technique, developed to study paleoclimatological changes in shellfish, was applied to three H. tuberculata specimens collected in north-west Brittany. For the specimens collected, the oxygen isotope ratios of the shell reflected the seasonal cycle in the temperature. From winter-to-winter cycles, estimates of the age and the annual growth increment, ranging from 13 to 55 mm per year were obtained. This study shows that stable oxygen isotopes can be a reliable tool for ageing and growth studies of this abalone species in the wild, and for validating other estimates.     

过渡族金属元素同位素在海底热液活动研究中的应用

过渡族金属元素(Fe、Cu、Zn等)同位素的地球化学特征研究是近年来新兴起的研究方向,在沉积地球化学、宇宙化学、成矿过程、岩浆作用和生物科学等多个领域都取得了重要进展。主要介绍了过渡族金属元素同位素在现代海底热液活动研究中的应用以及取得的重要成果,指出利用过渡族金属元素同位素研究现代海底热液活动具有广阔的发展前景。在分析总结已有研究工作的基础上,探讨了该领域的研究发展方向,包括:(1)丰富过渡族金属元素同位素组成的分析数据;(2)加强模拟实验工作;(3)探讨海底热液活动对过渡族金属元素在大洋内循环和平衡的作用。