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71.
光合细菌净化对虾养殖水质的研究 总被引:11,自引:0,他引:11
养殖水体中大量氨氮,硫化物的产生以及溶解氮的降低严重影响了对虾的正常生长。本文报道了光合细菌在实验室环境中净化水质的情况,结果表明,光合细菌参降低养殖水体中的氨氮和H2S含量,并提高水体中溶解氧的含量。 相似文献
72.
H.J. Hirche K.N. Kosobokova B. Gaye-Haake I. Harms B. Meon E.-M. Nthig 《Progress in Oceanography》2006,71(2-4):288
After a short introduction to the physical setting and the history of biological research the pelagic ecosystem of the Kara Sea is described. Main emphasis is on regional aspects of the plankton communities and their seasonal dynamics using mostly data collected between 1996 and 2001. In the zooplankton, for which most data were available, four regional aggregations were separated: (1) the rivers and estuaries of the Southern Kara Sea, (2) the south-western and (3) the central Kara Sea, and (4) the northern troughs and slope. The phytoplankton communities had a similar distribution. To provide components for detailed carbon budgets the regional dynamics of bacterial, phytoplankton and zooplankton biomass and production are described and carbon requirements of bacteria and zooplankton are estimated. For completeness a short literature review on higher trophic levels is included. Finally, recent observations of the pelago-benthic coupling are considered. Estimates of the carbon requirements from the plankton and benthos reveal a large underestimation of primary production, which to date, together with seasonal aspects, shows the largest gap in our knowledge. 相似文献
73.
74.
The behaviour of two species of foraminifera (Allogromia laticollaris and Ammonia beccarii) towards living and dead bacteria and inorganic particles was monitored using a cell-permeant fluorescent nucleic acid stain. The foraminifera were studied in seawater containing fluorescently labelled dead and living bacteria, and/or polystyrene particles of the same size as a control. Time-lapse observations under a fluorescence microscope clearly revealed pseudopodial transport of stained bacteria and uptake of bacteria inside the foraminifera. In contrast, no uptake of polystyrene particles was ever observed, although the foraminifera collected these particles and deposited them along the outside of the test. We conclude that foraminifera distinguish food and non-food particles while collecting. There appears to be a variation of uptake rate and final amount of ingested and digested bacteria. These variations occur between individuals of different size and species, and between sampling times (September 2001 and July 2002). 相似文献
75.
This paper presents a review of the past decade's highlights of research on the isolation and characterisation of particulate
organic matter (POM) in the world's oceans. The emphasis is on chemical studies but, in keeping with the growing interdisciplinary
nature of marine science, advances in other disciplines are also discussed, particularly those in biological sciences. Increasing
evidence for the importance of picoplankton, bacteria and viruses as POM constituents is highlighted, including the recent
recognition of large populations of autotrophic bacteria able to harvest light for energy. The transport of POM to bottom
waters was thought to be largely confined to large, rapidly sinking faecal pellets. However, recent studies have highlighted
the importance of organic aggregates and flocs formed by diatoms such as Rhizosolenia and other microalgae. Ascending particles have also been discovered, many of which are lipid-rich. Several studies have shown
that resuspension of bottom sediments and lateral advection of material from continental shelves can lead to anomalously high
particle fluxes measured in sediment traps moored in deep water. Many new approaches for characterizing POM have emerged,
such as pyrolysis gas chromatography-mass spectrometry and direct temperature-resolved mass spectrometry for analysis of higher
molecular weight materials and biopolymers. Lipid biomarker techniques have also advanced, exciting new possibilities being
raised by the ability to measure stable and radioactive carbon isotopes for individual compounds. The techniques of molecular
biology, such as the polymerase chain reaction (PCR), are being increasingly applied to provide complementary information
to more conventional microscopy and flow cytometry on the identity of organisms in the sea. The combination of these techniques
with advanced chemical analysis methods promises to greatly increase our knowledge of the origins, transport and fate of organic
matter in the oceans.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
76.
Most crude oils spread on open water to an average thickness as low as 0.1 mm. The application of dispersants enhances the transport of oil as small droplets into the water column, and when combined with the turbulence of 1 m waves will quickly entrain oil into the top 1 m of the water column, where it rapidly dilutes to concentrations less than 100 ppm. In less than 24 h, the dispersed oil is expected to mix into the top 10 m of the water column and be diluted to concentrations well below 10 ppm, with dilution continuing as time proceeds. Over the multiple weeks that biodegradation takes place, dispersed oil concentrations are expected to be below 1 ppm. Measurements from spills and wave basin studies support these calculations. Published laboratory studies focused on the quantification of contaminant biodegradation rates have used concentrations orders of magnitude greater than this, as it was necessary to ensure the concentrations of hydrocarbons and other chemicals were higher than the detection limits of chemical analysis. However, current analytical methods can quantify individual alkanes and PAHs (and their alkyl homologues) at ppb and ppm levels. To simulate marine biodegradation of dispersed oil at dilute concentrations commonly encountered in the field, laboratory studies should be conducted at similarly low hydrocarbon concentrations. 相似文献
77.
We describe here a simple digital in-line holographic microscope (DIHM) that was used to investigate the microbial life forms that exist in perennial springs and glacial melt-water pools on Axel Heiberg Island at near 80°N latitude in the Canadian High Arctic. The instrument determined an upper limit of the density of microbial organisms in the springs and also found an abundance of algae and bacteria in the pools formed from glacial run off. The discovery of life in extra-terrestrial regions of our solar system has been the aim of several space missions. DIHM can capture the dynamics of objects throughout an imaging volume with wavelength limited resolution. The simplicity of DIHM technology furthermore allows the construction of very light-weight and rugged instruments that we believe can be easily adapted for space missions and exobiological studies. 相似文献
78.
海洋沉积物中现存微生物化学标志物完整极性膜脂研究进展 总被引:3,自引:0,他引:3
完整极性膜脂作为活的微生物细胞的化学标志物,能够反映海洋沉积物中现存微生物群落结构和生物量等信息.与生物学方法相比,完整极性膜脂分析技术具有无需培养、快速和普适性等特点.综述了海洋沉积物中细菌和古菌的细胞膜完整极性膜脂的组成特点及其在生物地球化学和微生物生态学等研究中的应用,重点评述了在生物地球化学循环中有特殊作用的微生物,如厌氧氨氧化细菌、甲烷氧化古菌、氨氧化古菌、具有四醚膜脂结构的海洋泉古菌等,或者是一些特殊生态系统,如冷泉、海底深部生物圈等研究中完整极性膜脂应用的进展.还简要介绍了完整极性膜脂的分析方法,并对其应用前景进行了展望. 相似文献
79.
Bacterial calcification as a possible trigger for francolite precipitation under sulfidic conditions
Francolite (carbonate-fluor-apatite) is known to form in sediments where intense organic-matter decay occurs, but under oxic-to-suboxic conditions, because the alkalinity rise accompanying bacterial sulfate reduction (anoxic conditions) increases francolite solubility, hence preventing its supersaturation and precipitation. However, lagoonal, organic matter-rich, cryptalgal carbonates of Jurassic age located in the French Jura Mountains contain francolite that formed during early diagenesis, under anoxic-sulfidic and highly alkaline conditions. To explain this paradoxical situation, we propose the following “chain of reactions”: the presence of abundant biomass in the sediment would supply the “raw material” to the reactional system, i.e., the initial P budget, released through organic decay. The development of cryptalgal, bacterial mats at the sediment–water interface would have limited exchanges between the water column and the pore space, hampering pore water renewal and favoring the early onset of sulfate-reducing reactions. The onset of sulfate reduction would increase pore water alkalinity, potentially preventing francolite precipitation. In addition, the presence of sulfide ions would induce organic matter sulfurization, resulting in a relative pH rise. Alkalinity and pH rises would trigger the development of conditions leading to carbonate supersaturation, inducing bacterial-structure calcification. The sudden fall in alkalinity induced by early calcification would allow francolite precipitation, despite sulfidic conditions. 相似文献
80.
de Oliveira AJ Hollnagel HC Lima Mesquita Hde S Fontes RF 《Marine pollution bulletin》2007,54(7):921-927
Physical and chemical characteristics of intertidal sediments and their relationships with bacteria and cyanobacteria were analyzed at four stations at Pereque Beach. Granulometric analysis showed that Pereque beach has sediment that is classified as sand. The lowest value of the sediment C/N rates (6.08), mainly due to a higher concentration of organic nitrogen, was found at the northern part of Pereque Beach, where organic matter of marine source was more prominent. In this area, density (9.6x10(6)cells cm(-3)), biomass (1992.04ngC cm(-3)) and activity of bacteria were higher than at the southern end. In contrast, cyanobacteria density varied from 2.0 to 4.0x10(5)cells cm(-3), with biomass and total chlorophyll a of the sediment being higher at the southern part, where there are water input from Pereque River and higher organic matter of continental origin. The variability in the microbial population is discussed in the light of the sediment granulometry, organic matter quality, fresh water inflow and pollution. 相似文献