半连续培养下东海原甲藻和中肋骨条藻种群生长过程与种间竞争研究   总被引：17，自引：0，他引：17  

王宗灵  李瑞香  朱明远  陈炳章  郝彦菊 《海洋科学进展》2006,24(4):495-503

采用半连续培养方法研究了温度和营养盐(N和P)限制对中国东海2种重要赤潮生物东海原甲藻和中肋骨条藻生长及种间竞争的影响。结果表明,东海原甲藻在20℃和25℃时生长状态良好,具有明显的指数增长期,15℃时细胞生长明显受到影响;中肋骨条藻具有较广的温度适应性,15~25℃时均具有明显的指数增长期。东海原甲藻可以忍受低营养盐环境并种群增长,而中肋骨条藻细胞增长需要较丰富的营养盐。在营养盐充足的环境里中肋骨条藻具有竞争优势,相反,在营养盐限制的环境中,东海原甲藻是竞争的优胜者。实验结果与东海原甲藻赤潮爆发现场的环境调查结果基本一致,可以作为解释东海原甲藻赤潮形成原因的依据。  相似文献   

盐湖溶液热化学(Ⅳ) Li_2B_4O_7—Li_2SO_4—LiCl—H_2O体系298.15K时稀释热、热容和表观摩尔热焓的研究          下载免费PDF全文

李积才  翟宗玺  曾忠民  王鲁英 《盐湖研究》1993,(4)

用连续滴定量热法测定了四元体系Li_2B_4O_7—Li_2SO_4—LiCl—H_2O及其次级体系Li_2B_4O_7—Li_2SO_4—H_2O和Li_2B_4O_7—LiCl—H_2O 298.15K时的稀释热,并结合Debye-Hückel热焓极限公式研究了该体系的平均表观摩尔热焓。  相似文献   

Determination of part-per-trillion levels of atmospheric dimethyl sulfide by isotope dilution gas chromatography/mass spectrometry     

Donald C. Thornton  Alan R. Bandy  Robert G. Ridgeway  Arthur R. Driedger III  Marija Lalevic 《Journal of Atmospheric Chemistry》1990,11(4):299-308

Stable isotopic dilution was applied to the determination of dimethyl sulfide (DMS) in ambient air at the low part-per-trillion by volume (pptrv) levels. Perdeuterated DMS was used as an internal standard in the gas chromatography/mass spectrometry determination. The isotopically labelled internal standard provided insensitivity to possible losses of DMS in sampling and analysis. The lower limit of detection (LLD) was 1 pptrv with a sample acquisition time of 2 min.  相似文献   

Lacustrine basin hydrocarbon exploration – current thoughts     

Barry Jay Katz 《Journal of Paleolimnology》2001,26(2):161-179

Although much of the world's petroleum resource-base is associated with marine systems, regionally lacustrine petroleum systems are important. Individual accumulations may exceed several billion barrels. In each of these cases the oil is derived from a lacustrine source rock and may be produced from either nonmarine or marine reservoir rocks. The purpose of this paper is to describe the factors that control lacustrine source rock development and the nature of lacustrine reservoirs. Lacustrine oils display different physical and chemical characteristics than their marine counterparts. These differences can be related to the nature of their precursor material. Although the nature of the products are different, the geochemical threshold criteria for defining source rocks in both settings are the same because of common expulsion requirements. Commercially significant lacustrine systems require the presence of large, long-lived lakes. Such lake settings are tectonic in origin and restricted to climatic settings where precipitation exceeds evaporation. Within these large lake systems three primary factors determine source rock potential and quality. These factors are primary productivity level, organic preservation potential, and matrix sedimentation rate, which controls the dilution of preserved organic matter. Source rock potential is maximized where both productivity and preservation potential are maximized and sedimentation rate is minimized. To some degree these factors can compensate for each other. Hydrocarbon reservoir potential within lacustrine basins is partially impacted by overall tectonic setting. Within extensional settings, transport distances tend to be limited, with much of the sediment being transported away from the basin. The sediments delivered to the lake are poorly sorted and sedimentologically immature, commonly resulting in poor reservoirs due to both primary properties and their susceptibility to diagenesis. Within rifts better reservoirs tend to develop along platform or flexural margins. Stacking of reservoirs is important in lacustrine systems but baffles and barriers are often present between individual sand units. These barriers form as a result of lake level fluctuations. In compressional settings transport distances tend to be longer, resulting in more mature, better sorted sediments leading to higher quality reservoirs. These reservoirs typically develop in fluvial-deltaic and wave-dominated shoreline settings. Lacustrine carbonate reservoirs are locally important. These carbonates tend to develop during lake level lowstands and are dependent on diagenesis (dissolution and karstification) for porosity and permeability development. Lacustrine reservoirs are often stratigraphically and areally limited and display low individual well production rates. Within pure lacustrine systems exploration opportunities appear to be often restricted by either reservoir presence or quality (i.e., production rates). The best exploration opportunities in lacustrine basins appear to be associated with hybrid systems where a lacustrine source and marine reservoir exist.  相似文献   

孟加拉湾晚第四纪的碳酸盐溶解旋回     

丁旋  郝诒纯  万晓樵  方念乔 《沉积学报》2001,19(2):192-198

孟加拉湾由于陆源物质大量输入产生稀释效应,使碳酸盐含量表现为冰期时减小、间冰期时增大的“大西洋型”旋回。通过对该区四支活塞岩芯的有孔虫溶解指数、浮游有孔虫沉积通量、CaCO₃ 沉积通量和 >16 0 μm粗组分沉积通量的分析发现,研究区碳酸盐溶解作用强烈,表现出冰期减弱而间冰期增强的总趋势,且溶解作用滞后于浮游有孔虫壳的氧同位素旋回,尤以氧同位素 4、5期的高溶解度情况与印度洋和太平洋氧同位素 5期晚期至 4期为CaCO₃溶解高峰一致。因此,孟加拉湾地区的CaCO₃ 旋回是大西洋型稀释作用与太平洋型溶解作用两者叠加的产物.  相似文献   

Geochemical engineering; taking stock     

R. D. Schuiling 《Journal of Geochemical Exploration》1998,62(1-3)

Geochemical engineering makes use of optimized geochemical processes for the solution of environmental problems. It has developed in a few years from a collection of unrelated scientific and technological incidents into a coherent concept about how and where we can improve our geo-environment. All solutions to problems of pollution are based on neutralization/breakdown, concentration, dilution, isolation or immobilization, which serve to eliminate the pollutant, make it more manageable, or prevent its entry into the mobile phase, usually water, from which it can affect the biosphere. All of these solutions have their counterpart in nature, where many examples are found of high concentrations of potentially harmful substances. A major prerequisite of geochemical engineering solutions is that they should be compatible with the natural evolution of the system in its geo-environment. The advantages of this approach are that we can devise low-cost technologies (nature does most of the hard work itself), interfere least with nature, and quite often end up with useful by-products. Disadvantages are that technologies based on natural geochemical processes tend to be slow. The application of geochemical engineering concepts requires a better understanding of our environment and its ongoing processes than is necessary for a ‘classical' technology. In most environmental technologies the conditions are externally imposed on the system to be treated, and the natural evolution of the system is eliminated, or at best neglected. The concept of seeking a closer conformity with nature is paralleled in other disciplines like agriculture or the medical sector, where we see a similar evolution in the direction of techniques that are more in harmony with nature. Geochemical engineering brings many advantages, particularly in developing countries, or in countries where the state of the economy does not permit the introduction of expensive high-tech environmental technologies. So far, most of the applications of geochemical engineering concepts have focussed on solutions to environmental problems, but there are a number of cases where the environmental issue is more indirect, as e.g. in civil engineering. Geochemical engineering may be practised on a large, almost global scale, down to that of individual minerals, in accordance with the fact that geochemical processes also act on vastly different scales. An overview will be given of some of the problems that are being studied.  相似文献   

河流中单向性同流扩散器近区的稀释   总被引：4，自引：2，他引：2       下载免费PDF全文

槐文信  那宇彤 《水科学进展》1998,9(4):319-324

用三维湍浮力流模式结合混合有限分析法对河流中单向性同流扩散器的近区稀释特性进行精确的数值分析,所得结果与Parr的试验资料吻合良好,进而给出了稀释度在近区的经验公式,并且分析了浮力射流的分叉现象和吸附现象以及出现这两种现象的原因,发现水面对稀释有延迟作用,对分叉有促进作用.  相似文献   

Long-Term Observations of Isotope Ratio Accuracy and Reproducibility Using Quadrupole ICP-MS     

Thomas Ulrich  Balz S. Kamber  Jon D. Woodhead  Lizzy A. Spencer 《Geostandards and Geoanalytical Research》2010,34(2):161-174

High precision isotope ratio and trace element determination can be achieved with modern quadrupole ICP-MS provided that short and long-term instrument performance is accurately monitored. Here we present results for the isotope ratios ⁶Li/⁷Li, ¹⁴⁷Sm/¹⁴⁹Sm, ¹⁶⁰Dy/¹⁶¹Dy, ²⁰⁷Pb/²⁰⁶Pb, ²⁰⁸Pb/²⁰⁶Pb, ²⁰⁶Pb/²⁰⁴Pb and ²³⁵U/²³⁸U with which we determined long-term isotope ratio stability of relevance to both trace element and isotope determination. With respect to trace element determination, we first present long-term observations regarding oxide formation rates of Ba and Nd on light REE and heavy REE, as well as Zr on Ag. These showed good correlations and could be used to correct effectively the interference. The efficacy of this correction was demonstrated with analyses of the rock reference material BHVO-2 at both low and high oxide formation rates. Next, we studied the long-term reproducibility of a Dy isotope ratio that was measured to correct for the isobaric interference on Gd. It was found that, regardless of tuning condition, the ratio reproduced very well (0.58% RSD, 1s) and that the estimate of the Gd concentration did not suffer from the large correction (> 10%) caused by the Dy isobar. Long-term reproducibilities of Li, Sm and U isotope ratios, required for accurate mass bias correction when isotopically enriched internal standards of these elements are employed, were measured in the rock reference materials AGV-2 and JA-3 over a time period of up to 3 years. As expected, the Li isotope ratio showed the largest variability (RSD = 7%), but the other two ratios had relative external reproducibilities of only 1.01% (1s, U) and 0.67% (Sm). The mass bias-induced scatter in measurements for Sm and U was so small that the internal standard correction was effective, even for samples with high concentrations of these elements. With regard to Pb-isotope ratio determination, we also present long-term reproducibility for NIST SRM 982, run as an unknown and two accuracy tests for Pb separated from granitoids and from meteorites. It is demonstrated that the obtained ratios, including those involving ²⁰⁴Pb, are accurate relative to MC-ICP-MS determinations and of comparable precision to conventional TIMS analysis. The excellent agreement between all data sets shows the potential of modern quadrupole ICP-MS instrumentation for Pb-isotope determination, particularly for samples with very low Pb content.  相似文献   

Accurate and Precise Elemental Abundance of Zinc in Reference Materials by an Isotope Dilution Mass Spectrometry TIMS Technique     

Osama Y. Ghidan  Robert D. Loss 《Geostandards and Geoanalytical Research》2010,34(2):185-191

A thermal ionisation mass spectrometric technique enabled the abundance of Zn in geological and biological reference materials and water samples to be measured by double spiking isotope dilution mass spectrometry enriched in the ⁶⁷Zn and ⁷⁰Zn isotopes. In the past, thermal ionisation mass spectrometry proved to be difficult for low-level zinc isotopic measurements. The size of Zn samples used for isotopic determination, in particular the biological RMs, represents an important breakthrough. These results represent the most accurate and precise concentrations measured for Zn in these samples. The maximum fractional uncertainty was that for TILL-3 (2%), while the minimum fractional uncertainty was 0.7% for both BCR-1 and W-2. The inhomogeneity of Zn in HISS-1 was revealed while other reference materials appeared homogeneous at the 95% confidence uncertainty. The certified concentration of Zn in HISS-1 and IMEP-19 by their producers are 28% and 3.8% higher than the values measured in this work. These are the first Zn concentration measurements in these materials by the isotope dilution-TIMS technique, except for BCR-1, NIES N^o 9 and IMEP-19. Reducing the blank enabled accurate measurement in water at the ng g^-1 level demonstrating the applicability of the technique for low-level Zn samples.  相似文献   

Mass Fractions of S,Cu, Se,Mo, Ag,Cd, In,Te, Ba,Sm, W,Tl and Bi in Geological Reference Materials and Selected Carbonaceous Chondrites Determined by Isotope Dilution ICP‐MS          下载免费PDF全文

Zaicong Wang  Harry Becker  Frank Wombacher 《Geostandards and Geoanalytical Research》2015,39(2):185-208

Mass fractions of S, Cu, Se, Mo, Ag, Cd, In, Te, Ba, Sm, W and Tl were determined by isotope dilution sector field ICP‐MS in the same sample aliquot of reference materials using HF‐HNO₃ digestion in PFA beakers in pressure bombs and glassy carbon vessels in a high‐pressure asher (HPA‐S) for comparison. Additionally, Bi was determined by internal standardisation relative to Tl. Because isobaric and oxide interferences pose problems for many of these elements, efficient chromatographic separation methods in combination with an Aridus desolvator were employed to minimise interference effects. Repeated digestion and measurement of geological reference materials (BHVO‐1, BHVO‐2, SCo‐1, MAG‐1, MRG‐1 and UB‐N) gave results with < 5% relative intermediate precision (1s) for most elements, except Bi. Replicates of NIST SRM 612 glass digested on a hot plate were analysed by the same methods, and the results agree with reference values mostly within 2% relative deviation. Data for the carbonaceous chondrites Allende, Murchison, Orgueil and Ivuna are also reported. Digestion in a HPA‐S was as efficient as in pressure bombs, but some elements displayed higher blank levels following HPA‐S treatment. Pressure bomb digestion yielded precise data for volatile S, Se and Te, but may result in high blanks for W.  相似文献