Stable Sulfur Isotopic Evidence for Historical Changes of Sulfur Cycling in Estuarine Sediments from Northern Florida     

Volker Brüchert  Lisa M. Pratt 《Aquatic Geochemistry》1999,5(3):249-268

Data on abundance and isotopic composition of porewater and sedimentary sulfur species are reported for relatively uncontaminated and highly contaminated fine-grained anoxic sediments of St. Andrew Bay, Florida. A strong contrast in amount and composition of sedimentary organic matter at the two sites allows a comparative study of the historical effects of increased organic loading on sulfur cycling and sulfur isotopic fractionation. In the contaminated sediments, an increase in organic loading caused increased sedimentary carbon/sulfur ratios and resulted in higher rates of bacterial sulfate reduction, but a lower efficiency of sulfide oxidation. These differences are well reflected in the isotopic composition of dissolved sulfate, sulfide, and sedimentary pyrite. Concentration and isotopic profiles of dissolved sulfate, organic carbon, and total sulfur suggest that the anaerobic decomposition of organic matter is most active in the upper 8cm but proceeds at very slow rates below this depth. The rapid formation of more than 90% of pyrite in the uppermost 2 cm which corresponds to about 3 years of sediment deposition allows the use of pyrite isotopic composition for tracing changing diagenetic conditions. Sediment profiles of the sulfur isotopic composition of pyrite reflect present-day higher rates of bacterial sulfate reduction and lower rates of sulfide oxidation, and record a profound change in the diagenetic cycling of sulfur in the contaminated sediments coincident with urban and industrial development of the St. Andrew Bay area.  相似文献   

Dynamics of attached bacteria at the water-sediment interface in a mesotrophic swampy bog of Japan     

Motoo Utsumi  Yukihiro Nojiri  Nozomi Ytow  Humitake Seki 《Journal of Oceanography》1998,54(2):179-184

The population dynamics of attached bacteria at the water-sediment interface were studied in a mesotrophic swampy bog, Matsumi-ike, near Tsukuba, Japan. The density of attached bacteria was higher at the sediment boundary layer than in the water column, and low inside the sediment (deeper, than 10 mm below the sediment surface) throughout the year. The density of bacteria attached on the glass slide was highest during spring when the source of organic matter in the water column was mainly withered cattail, and gradually decreased toward summer, while the phytoplankton became the dominant source of organic matter in the water column. The epibacterial populations in the water column and at the boundary showed almost the same seasonal fluctuation in attachment and detachment rates. However, bacterial growth rates did not show the same seasonal fluctuation, and annual average growth rates on the glass slides were all lower than that of bacterioplankton (free-living bacteria in water) in the water column.  相似文献   

松江鲈肌酸激酶的基因克隆、表达与功能分析     

刘莹莹  陈学昭  于珊珊  柴迎梅  林啸鹏  祝茜 《海洋学报》2018,40(12):21-30

前期蛋白质质谱分析发现,松江鲈（Trachidermus fasciatus Heckel）经鳗弧菌（Vibrio anguillarum）刺激后,其皮肤黏液中的肌酸激酶（creatine kinase,CK）的表达明显上调。目前,肌酸激酶在鱼类中的功能研究尚未深入开展。本文利用RACE技术克隆获得了松江鲈CK基因的全长cDNA序列（命名为TfM-CK）。TfM-CK基因的cDNA全长为1 474 bp,开放阅读框为1 146 bp,编码381个氨基酸。序列比对分析显示,TfM-CK序列高度保守。实时荧光定量PCR显示,TfM-CK mRNA广泛表达于松江鲈各组织,在肌肉中的相对表达量最高,其次为血液。鳗弧菌刺激后,TfM-CK mRNA在肌肉、皮肤、脾脏和头肾中均上调表达。其中,脾脏中的表达量高达对照组的900多倍。原核重组表达纯化的TfM-CK （rTfM-CK）蛋白酶活测定实验结果显示,重组蛋白的酶活为22.0 U/mg。rTfM-CK对鳗弧菌、大肠杆菌（Escherichia coli）、巨大芽孢杆菌（Bacillus megaterium）和金黄色葡萄球菌（Staphylococcus aureus）有较强的凝集作用。由以上实验结果推测,TfM-CK可能通过细菌凝集作用参与到了松江鲈抵抗病原菌的先天免疫防御过程中。本研究为认识鱼类肌酸激酶的功能及其在病原菌防御过程中的分子免疫机制机制提供了参考。  相似文献   

Heterotrophic bacterial floras in industrial area and unpolluted marine environments around Qingdao     

Du Zongjun  Li Yun  Yu Dehua  Wang Xianghong  Chen Jixiang  P. A. W. Robertson  B. Austin  Xu Huaishu 《中国海洋大学学报(英文版)》2002,1(1):59-62

From Oct. 1999 to Oct. 2000, the heterotrophic bacterial floras in the industrial marine environment around the Qingdao Power Plant (QPP) and in the unpolluted marine environments were investigated. The results showed that the numbers of the heterotrophic bacteria around QPP were much higher than those in unpolluted environments, and the average numbers in QPP Seawater, QPP Sediment, Unpolluted Seawater and Unpolluted Sediment were 5.4×10⁴cfu(mL)⁻¹, 5.0×10⁵cfug⁻¹, 3.0×10²cfu(mL)⁻¹ and 1.3×10⁵cfug⁻¹ respectively. Totally, 118 strains were isolated from QPP and 99 of them were Gram-negative. One hundred and twenty one strains were isolated from the unpolluted environments and 104 of them were Gram-negative. All the Gram-negative bacteria belonged to 13 genera. The distribution of the bacteria was varied in different marine environments. The results showed that the unpolluted marine environments contained much more Vibrio than seawater and sediment around QPP.  相似文献   

Balance Between Autotrophic and Heterotrophic Components and Processes in Microbenthic Communities of Sandy Sediments: A Field Study     

Kristina Sundbäck  Per Nilsson  Claes Nilsson  Benno Jönsson 《Estuarine, Coastal and Shelf Science》1996,43(6):689-706

The microscopic community of a microtidal sandy sediment on the Swedish west coast was studiedin situat two depths (0·5 and 4 m) on four occasions (January, April, August and October). Biomass of microalgae, bacteria, ciliates and meiofauna, as well as primary and bacterial productivity, were quantified. Meiofaunal grazing on algae and bacteria was measured simultaneously by radiolabelling intact sediment cores. Autotrophic biomass dominated the microbial community at both depths and on all sampling occasions, accounting for 47–87% of the microbial biomass. Meiofauna contributed 10–47%, while bacteria and ciliates together made up less than 6%. The microflora was dominated by attached (epipsammic) diatoms, but occasional ‘ blooms ’ of motile species occurred. Vital cells of planktonic diatoms contributed to benthic algal biomass in spring. Primary productivity exceeded bacterial productivity in April and August at both depths, while the balance was reversed in October and January. Meiofauna grazed between 2 and 12% of the algal biomass per day, and between 0·3 and 37% of the bacterial biomass. Almost an order of magnitude more algal (17–138 mg C m⁻²) than bacterial (0·1–33 mg C m⁻²) carbon was grazed daily. At the shallow site, primary productivity always exceeded grazing rates on algae, whereas at the deeper site, grazing exceeded primary productivity in October and January. Bacterial productivity exceeded grazing at both depths on all four occasions. Thus, meiofaunal grazing seasonally controlled microalgal, but not bacterial, biomass. These results suggest that, during summer, only a minor fraction (<10%) of the daily microbenthic primary production appears to enter the ‘ small food web ’ through meiofauna. During spring and autumn, however, a much larger fraction (≈30–60%) of primary production may pass through meiofauna. During winter, meiofaunal grazing is a less important link in the shallow zone, but at sublittoral depths, algal productivity may be limiting, and meiofauna depend on other food sources, such as bacteria and detritus.  相似文献   

Emission of nitrogen oxides (NO x ) from a flooded soil fertilized with urea: Relation to other nitrogen loss processes     

I. E. Galbally  J. R. Freney  W. A. Muirhead  J. R. Simpson  A. C. F. Trevitt  P. M. Chalk 《Journal of Atmospheric Chemistry》1987,5(3):343-365

Emissions of nitric oxide and other odd nitrogen oxides (NO _x ) from a flooded rice field were studied after urea had been broadcast into the floodwater.The NO _x flux from the fertilized area was very low (0.2×10^-9 g N m^-2 s^-1) for the first few days after application of urea and was high (0.95×10^-9 g N m^-2 s^-1) in the subsequent period when significant nitrite and nitrate were present in the floodwater. At night, little if any NO _x was exhaled but ambient NO₂ was absorbed by the floodwater. An uptake velocity for NO₂ of 3×10^-4 m s^-1 was measured during one night. Maximum NO _x losses were observed near 1300 h when temperature and solar ultraviolet light were maximum.While the amounts of nitrogen oxides emitted are of little agronomic importance (2×10^-3 per cent of the fertilizer nitrogen was lost as NO _x during the 10-day study period), they may well be of significance as a source for some gas reactions in the atmosphere and for the global nitrogen cycle.Of the fertilizer nitrogen applied (as urea) approximately 30% was lost to the atmosphere by NH₃ volatilization, 15% by denitrification, presumably as N₂, and the remainder, less minor losses of NO and N₂O, remained in the plant/soil/water system.Now at Forestry Department, Australian National University, G.P.O. Box 4, ACT 2601, Australia.  相似文献   

Mn-oxide: a major source of easily mobilisable Co and Ni under reducing conditions in New Caledonia FerralsolsLes oxydes de Mn : une source majeure de Co et Ni facilement mobilisables en conditions réductrices dans les Ferralsols de Nouvelle-Calédonie     

Cécile Quantin  Thierry Becquer  Jacques Berthelin 《Comptes Rendus Geoscience》2002,334(4):273-278

Chemical and bacterial reduction and dissolution of Fe and Mn-oxide and the concomitant solubilisation of Co and Ni were studied in a surface horizon of a New-Caledonia Ferralsol. Chemical extractions showed that Mn and Co were in a large part associated in Mn-oxides. The main part of Ni was associated with goethite, but a very small fraction was also associated with Mn-oxides. Anaerobic reducing bacterial activity was responsible for Fe solubilisation at a smaller extent than for Mn solubilisation and consequently for associated metal release. Submicroscopic investigations revealed the presence of a Mn-oxide containing Co, Ni and Al, close to a lithiophorite–asbolane mixed-layers Mn-oxide, which can be considered as a main source of easily available metals in this soil. To cite this article: C. Quantin et al., C. R. Geoscience 334 (2002) 273–278.  相似文献   

Acceleration of Selenate Reduction by Alternative Drying and Wetting of Soils   总被引：1，自引：0，他引：1  

朴河春  刘广深等 《中国地球化学学报》1996,15(3):278-284

In nature selenate reduction and nitrate denitrification both follow a similar biogeo-chemical mechanism.It has been proved that abiotic stresses such as alternative drying and wetting can exert an important influence on nitrate denitrification as well as on selenate reduction.Our experimental results lend great support to the above conclusion.  相似文献   

湖泊中磷的循环与沉积作用   总被引：5，自引：1，他引：5  

东野脉兴 《化工矿产地质》1996,18(4):258-262

地壳存在大量微溶性磷酸盐矿物，是湖泊中无限的磷源。中国云南省的滇池周围分布着大量早寒武世梅树村期磷块岩，其可溶性大于内生磷灰石，因此滇池湖水中磷的浓度提高，达０．０４～０．３８ｍｇ／Ｌ，是一般湖水中磷浓度的４～１０倍。藻类与细菌在滇池大量繁殖，摄取磷等营养物质，死亡后又被分解生成可溶性颗粒有机磷，磷质又返回湖水中，而那些分解后的水溶部分、不易分解的顽性组分或者不能为后来的生物所利用的组分，形成泥状沉积物或有机泥浆沉入湖底加入湖相沉积物。  相似文献   

与细菌活动有关的成矿作用——两个欧洲铅锌矿床实例   总被引：4，自引：0，他引：4  

胡明安 《矿床地质》1997,16(1):61-70

法国布·玛和西班牙拉·弗矿床分别产于富含干酪根的白云岩和沥青的铁质白云岩中。正构烷、烷基环已烷、藿烷和甾烷等生物标志化合物研究揭示了成矿时发生过细菌活动。细菌在沉积－成岩早期发育于还原水体中，或在成岩期－成岩期后由大气降水自地表带来，其赖以生存的有机质既可以是生物聚合体（布·玛矿床），亦可以是地质聚合体（拉·弗矿床）。这些微生物在１００℃以下的温度条件下生存繁殖，使硫酸盐还原生成硫化氢，导致铅锌硫化物沉淀  相似文献