贵州草海沉积物碳酸盐碳同位素异常正值的发现及其环境指示意义

对贵州草海沉积物柱芯碳酸盐碳同位素组成测定的结果显示,其δ13C值的变化范围为- 14.25‰至23.10‰,变化幅度为37.35％,这是迄今所发现的湖泊沉积物碳酸盐中最大的碳同位素变化幅度,其中的部分同位素值也是迄今发现的最大碳同位素值.综合碳酸盐氧同位素、碳酸盐含量和有机质含量指标,认为草海沉积物碳酸盐碳同位素组成...     

Consequences of linseed oil spills in salt marsh sediments

In a simulated spill in a salt marsh, linseed oil penetrated rapidly into the sediments at a rate of 10(-7) cm2 s(-1). The oil concentration remained unchanged for the first month after the spill, but 60% of the oil disappeared from the top 30 cm after a further month. The oil adsorbed to and accumulated in the muddy sediments (top 15 cm) leading to decreased sediment permeability, pH, Eh, abundance of plant roots and infauna and to the establishment of anoxic conditions. These changes accompanied transformations in the original fatty acid composition of the linseed oil, mainly associated with a decrease in 18 : 3omega3, an increase in the other fatty acids and the presence of 'new' fatty acids. A rapid increase in the abundance of heterotrophic aerobic and anaerobic bacteria and aerobic oil degrading bacteria, suggested that these micro-organisms degraded the oil. The role of the bacteria in oil degradation was confirmed in laboratory experiments where the fatty acids composition of the linseed oil underwent identical transformations to those obtained in the field. The degradation of linseed oil appears to be a sequential process initiated by aerobic and/or anaerobic bacteria and continued by sulphate reducing bacteria, which were unable to degrade the raw oil.     

太湖人工生态系统中氮循环细菌分布

对太湖五里湖的以水生高等植物为主的湖泊人工生态系统,用最大可能数法,测定了该系统内各种生态类型水生高等植物群落内的４类氮循环细菌的分布。结果表明反硝化细菌的最大可能数,在水生高等植物群落内水体中较敞水区湖水高２－５个数量级差异极显著;漂服植物各落内水体的反硝化细菌ＭＰＮ值较沉水和浮叶植物群落内水体高２－３个数量级,差异极显著;     

抚仙湖不同污染来源沉积物微生物解磷能力分析

以云南抚仙湖为研究对象,分析了不同污染来源沉积物微生物量、碱性磷酸酶活性(APA)和微生物解磷能力的垂向分布特征和水平分布特征.结果表明,抚仙湖各采样点沉积物微生物生物量与APA垂向分布趋势相似,总体上随着深度增加逐渐降低,微生物作用主要表现在表层.在空间分布上,富营养化星云湖以泄水为主的南岸隔河口微生物生物量和APA最高,其次为以农业面源污染为主的北岸梁王河口和以磷矿开发为污染来源的北岸东大河口,再次为受人类活动影响较小、以自生有机污染为主的湖心和东岸老凹嘴,以自然水土流失为主的西岸尖山河口微生物生物量和APA最低.沉积物微生物生物量和APA体现了不同外源污染对抚仙湖各湖区的影响不同.抚仙湖沉积物微生物对有机磷和无机磷均有解磷能力,并且无机磷解磷能力大于有机磷.沉积物解无机磷细菌数量和APA决定了抚仙湖沉积物磷释放强度,造成了抚仙湖较高强度的内源磷污染负荷.     

Simulation of the impacts of diagenesis or low-grade metamorphism on neutrophilic microaerobic Fe(II)-oxidizing biofilm

The microaerobic iron-oxidizing bacteria in circumneutral environment produce extracellular polymeric substances(EPS)with unique morphologic features,such as stalks or sheaths,which can be regarded as geobiological signatures.The Archean and early Palaeoproterozoic oceans were anoxic with high soluble Fe(II)that were suggested to have been oxidized through the metabolism of Fe(II)-oxidizing bacteria.The precursor of the ultrafine hematite in banded iron formation(BIF),e.g.,ferrihydrite,was suggested to be the mineral record of microbial Fe(II)-oxidation at that time.However,both the biological materials and primary iron minerals were prone to being altered by diagenetic or low-grade metamorphic processes.This makes it difficult to interpret the genesis of Precambrian BIFs.Here,we report experimental simulation on the effects of diagenesis or low-grade metamorphism on neutrophilic microaerobic Fe(II)-oxidizing bacteria and their biomass.Stalks,sheaths,and iron oxide spheroidal aggregates are partially preserved after the 100 MPa/300°C treatments,which indicates the mixed organic matters and iron oxides could survive the diagenetic or low-grade metamorphic processes.Some organic-mineral mixing structures carry information on microbial processes,though they appear similar to pseudomorphs of fossilized bacteria.     

Experimental study on reduction of U (VI) by an anaerobic bacterium, Shewanella putrefaciens: Application to sandstone-hosted interlayer oxidation-zone type uranium deposits, China

A lot of fossil bacteria and algae, which were re-placed by uraninite ( pitchblende), were first found inthe ores when the authors studied the sandstone-hostedinterlayer oxidation-zone type uranium deposits innorthwest China[1,2]. It is known that a powerful radia-tion from the uranium ores is harmful and, evendeadly to any life, including microorganism. Whatmechanism does this inconceivable fact result from?Up to the present time in China, there has been no ex-perimental investigation on red…     

Vertical quantitative and dominant population distribution of the bacteria isolated from the Muztagata ice core

With rapid development of microbiology on ex-treme environment, many microorganisms have been found on glacial surface and in deep glacier around the world. The extensive 16S rRNA sequence analysis of bacteria isolated from glacial samples indicates that the bacteria in ice are highly similar to those from ocean, lake, terrestrial sediment and agricultural soil on the earth[1,2]. This suggests a close relationship be-tween the microorganisms in glacial region and those in other environments s…     

Influence of nitrate and dissolved organic carbon loading on the interaction of Microcystis aeruginosa and heterotrophic bacteria from hyper-eutrophic lake (Taihu Lake,China)

To investigate the interaction between cyanobacteria and heterotrophic bacteria under gradients of glucose and nitrate, a cyanobacterial strain of Microcystis aeruginosa was grown in microcosms with and without a freshwater bacterial mixture, which was collected from Lake Taihu. Concentrations of glucose (1350, 975, 600, 300, 150, and 37.5 μmol C L⁻¹) and nitrate (150, 300, and 9000 μmol N L⁻¹) were used in a range of combinations giving 9 different treatments of glucose:nitrate. In the microcosm without the bacterial mixture, M. aeruginosa abundance gradually increased with days in all treatments. However, M. aeruginosa had much lower density in some treatments with the bacterial mixture. The difference in M. aeruginosa growth could be explained by competition with bacteria in the cultures in which these were added. The abundance of M. aeruginosa and bacteria when grown together was nearly equal and the number of the bacterial species was highest in the treatment with 300 μmol C L⁻¹ and 150 μmol N L⁻¹. Our results suggest that at this glucose:nitrate ratio M. aeruginosa and the bacterial mixture maintain a balance, and bacteria maintain diversity. In conclusion, we propose that dissolved organic carbon and nitrate availability fundamentally affects the structure as well as stoichiometry of pelagic associations.     

Mineralogical and geochemical features of bacterial mats and travertines of the Khoito-Gol thermal spring (East Sayan)

The mineralogical and geochemical features of the Khoito-Gol ecosystem (fresh thermal waters-microorganisms-travertines) of the Baikal Rift Zone and the aspects of the interaction among its components were studied. The research has shown that the behavior, distribution, and accumulation of trace elements are determined mostly by the geochemical barriers of geologic and biologic genesis in the flowing-water habitat of bacteria of the Khoito-Gol spring. Formation of biominerals by different functional groups of its bacterial community is considered.