Phytoplankton driven distribution of dissolved and particulate lipids in a semi-enclosed temperate sea (Mediterranean): Spring to summer situation

The relationship between changes in lipid classes and phytoplankton composition and abundance in the northern Adriatic was studied during spring and summer 2008 at two stations with different nutrient levels, i.e. at the western mesotrophic and eastern oligotrophic areas. Changes in the phytoplankton community depended on temporal surface nutrient depletion and bottom accumulation; that is, microphytoplankton, mainly diatoms Pseudo-nitzschia sp., developed at nutrient richer surface layers of the mesotrophic area in spring and at deeper layers of the oligotrophic site in late summer. In other periods nanophytoplankton dominated. Dissolved organic carbon (DOC) and lipid content were comparable for the two stations, while particulate organic carbon (POC) was richer at the mesotrophic side. Total lipid concentrations varied in the range from 8.0 to 92.2 μg l⁻¹ and from 16.9 to 76.9 μg l⁻¹ in the dissolved and particulate fractions, respectively. DOC and POC contents were in the ranges from 0.77 to 1.58 mg l⁻¹ and from 0.06 to 0.56 mg l⁻¹, respectively. Lipid and organic carbon distribution did not follow phytoplankton progression, indicating decoupling between organic matter production and decomposition throughout the investigation period. The main sources of lipids were marine phytoplankton and bacteria. Low nutrient conditions caused increased biosynthesis of lipids. Also, increasing oligotrophy led to an increasing number of phytoplankton taxa. The synthesis and accumulation of glycolipids by the developed taxa were enhanced during nutrient exhaustion, contributing in late summer, on average, 20.2 and 22.0% at the mesotrophic and oligotrophic stations, respectively, in the particulate fraction. The distribution of bacterial lipids and lipid breakdown products implies that bacterial lipid degradation was significant in spring, while very probably lipid abiotic degradation took place during summer.     

湖北宜昌西陵峡地区大气降雨氢氧同位素特征分析

通过测定湖北宜昌西陵峡地区2009年5月至10月降雨样品的氢氧同位素组成,分析了该区降雨的氢氧同位素特征及其与降雨量的关系,并与区内2007年同期的降雨同位素资料进行了对比.结果表明,该区大气降雨线公式为:δ(D) =8.45δ(18 O)+11.55,与全球降雨线和全国降雨线公式相比,斜率和截距均偏大,这与凝结物在未...     

济阳坳陷车西地区下古生界储层裂缝参数特征与裂缝类型

根据车西地区下古生界潜山的岩芯观察与稳定碳氧同位素数据,结合钻井地质、生产动态资料,划分了车西地区下古生界储层裂缝类型;研究了裂缝长度、宽度、倾角、充填等特征参数,并探讨了各参数间的相互关系;总结了裂缝特征参数与构造部位、埋藏深度、油气产量的关系。     

Measuring correlations between atmospheric oxygen and carbon dioxide mole fractions: A preliminary study in urban air

On 25 and 26 October 1986 the air in Cambridge, Massachusetts was monitored for O₂ and CO₂ mole fraction. O₂ concentrations were detected from changes in the relative refractivity of dried air between two lines of ¹⁹⁸Hg at 2537.269 and 4359.562 Å using dual-wavelength interferometry. Changes in oxygen mole fraction were resolved with two-minute time resolution to a precision of ±2.0 ppm. Changes in O₂ were shown to be strongly anticorrelated with changes in CO₂ as expected for combustion processes. The demonstrated instrumental capabilities are appropriate for measuring changes in O₂ mole fraction in background air which could be of importance to a broad range of biogeochemical studies.     

X-ray photoelectron study of oxygen bonding in crystalline C–S–H phases

We recorded the photoelectron spectra of various crystalline calcium silicate hydrates (C–S–Hs) and have examined their O 1 s photoelectron spectra. The spectra are asymmetric, with contributions assigned primarily to bridging and non-bridging oxygen species. There is an increased contribution due to the presence of non-bonding oxygen atoms with increasing calcium:silicon ratio. Additionally, there are slight changes in theO 1s-binding energies with changes in calcium:silicon ratio. These changes are explained in terms of bonding and silicate structure.     

高压-工频电加热裂解油页岩技术室内试验及 氧的驱动效应分析

高压-工频电加热原位裂解油页岩是吉林大学与俄罗斯托木斯克理工大学合作研究的具有占地面积小、污染小、工艺简单等优点的油页岩开采技术。先对油页岩使用高压电击穿,再使用电加热的二步法,可以达到快速裂解油页岩的效果。为了确定裂解油页岩的工艺参数,以及更好地掌握高压-工频电加热裂解油页岩技术,本文对油页岩在有、无氧气条件下的裂解过程进行了热分析试验。试验表明,在有氧与无氧加热条件下,都可完成油页岩的裂解,且裂解过程是相同的,都属于二段式裂解过程。氧在油页岩加热裂解时具有驱动作用,可以降低油页岩的裂解温度、节省能量、提高裂解速度。     

碳酸钙同质多象转变过程中氧同位素分馏的实验研究

本文通过“一步法”和“两步法”的“附晶生长法”分别合成了碳酸钙矿物，对其进行了同质多象转变过程中的氧同位素分馏行为的研究。同时通过真空条件下的同质多象转变实验，对文石和方解石的酸分馏系数的差异进行了实验验证。结果发现：①在50℃和70℃下，如果文石与水之间的氧同位素分馏未达到平衡，由母体文石经过同质多象转变生成的次生方解石完全继承的母体矿物的氧同位素组成。如果文石与水之间的氧同位素分馏达到平衡，由互过同质多象转变生成的次生方解石部分继承母体文石的氧同位素组成，并且次生方解石相对于母体文石富集^18O。②在0℃和25℃下，“一步法”的“附晶生长法”的实验结果表明，由六方方解石经过同质多象转变生成的次生方解石也完全继承母体矿物的氧同位素组成，并且在该温度下，矿物与水之间的氧同位素分馏与温度无关。     

太平洋三海区热液烟囱物的地球化学标型特征研究

以成因矿物学的理论和方法，运用电子探针、中子活化、常规化学分析和稳定同位素分析等多种地球化学实验测试技术，较系统地研究了太平洋三区四地热液烟囱物的地球化学组成和变化，揭示了研究区不同热液喷发类型中的地球化学标型特征。高温热液类型的硫化物，由高温热液矿物组成，除本身富合Fe，Zn，Cu，Pb等金属元素外，氧同位素换算温度也表现最高或中高；中低温热液类型的烟囱物，金属元素合量较低，氧同位素换算温度也表现较低。由此论证了不同标型特征的热液矿物地球化学特征与热液喷发环境之间相互依存的紧密关系。     

The complex diagenetic history of discontinuities in shallow‐marine carbonate rocks: New insights from high‐resolution ion microprobe investigation of δ18O and δ13C of early cements

Sedimentary gaps are a major obstacle in the reconstruction of a carbonate platform's history. In order to improve the understanding of the early diagenesis and the succession of events occurring during the formation of discontinuity surfaces in limestones, secondary ion mass spectrometry was used for the first time to measure the δ ¹⁸O and δ ¹³C signatures of 11 early cement and fabric stages in several discontinuity surfaces from the Jurassic carbonate platform of the Paris Basin, France. Pendant cements show a high variability in δ ¹⁸O, which was impossible to detect by the less precise microdrilling method. The morphology of a given cement can be produced in various environments, and dogtooth cements especially can precipitate in marine phreatic and meteoric phreatic to vadose environments. Marine dogtooth cements and micritic microbially induced fabrics precipitated directly as low‐magnesium calcite in marine waters, as attested to by the preservation of their initial δ ¹⁸O and δ ¹³C signals. Five discontinuity types are recognized based on high‐resolution geochemical analyses, and their palaeoenvironmental history can be reconstructed. Two exposure surfaces with non‐ferroan pendant or meniscus cements formed in the oxidizing vadose zone. A hardground displays marine fibrous cements and non‐ferroan dogtooth cements that formed in a subtidal environment in oxidizing water. Two composite surfaces have undergone both marine and subaerial lithification. Composite surface 1 displays non‐luminescent ferroan dogtooth cements that precipitated in reduced conditions in seawater, followed by brown‐luminescent dogtooth cements characteristic of a meteoric phreatic environment. Composite surface 2 exhibits microbially induced fabrics that formed in marine water with abundant organic matter. The latter discontinuity, initially formed in a subtidal environment, was subsequently exposed to meteoric conditions, as evidenced by ferroan geopetal cements. A high‐resolution ion microprobe study is essential to precisely document the successive diagenetic environments that have affected carbonate rocks and discontinuities with a polygenic and intricate history.     

基于热膨胀性质的ZrO2 固体电解质性能与相关系模型

ZrO₂固体电解质室温下各相的相对含量、高温可相变量是决定材料抗热震性和导电性能的关键因素.固体电解质抗热震性与导电性能的匹配,对低氧含量下的钢水定氧起着重要作用.以此为前提,建立了电解质材料体系的抗热震性与室温相比例之间的线性模型,提出了其高温电导率与相变之间的演化模型.为制备用于测低氧活度的高精度冶金氧传感器提供参考依据.