中国南极长城站室内空气微生物含量七年前后的比较   总被引：3，自引：0，他引：3  

陈皓文 《海洋湖沼通报》1999,(4):48-52

中国南极长城站室内空气微生物含量的考察结果表明,七年后,虽然一些室内空气微生物含量有所下降,即空气质量有所改善,但总体来看,略是上升势。与友邻科考站相比,长城站的多少有点偏高。也比非南极的较高纬度的某些室内空气微生物含量高。结果意味着长城站尚有提高空气质量、改善环境状况的余地。  相似文献   

西伯利亚水库和叶尼塞河中物质及生态系统条件的预测：生物物理方法     

Andrei Degermendzhy  Vladimir Gubanov 《湖泊科学》1998,10(S1):203-228

An avenue to integrate theoretical, experimental and field research methods to forecast water quality in water bodies for different scenarios of water management is proposed. Exploration of the laws of organization, stability and controllability of laboratory "ideal" water microbial communities (model ecosystems) is the basis to build the following biophysical research chain:to formalize with primary field information a conceptual block-diagram of a water ecosystem →to real chemical and other density-dependent and population-growth-controlling factors → to find our limiting factors for natural ecosystems → to conduct experiments with isolated chemical factors and hydrobionts to derive kinetic dependencies and quantitative parameters→ to transfer regularities of operation and kinetic dependencies to the natural ecosystem→ retrospective verification of the model on the base of available field and derived theoretical-experimental data →prognostic calculations for the scenario. Efficiency of the approach is demonstrated in microalgal "blooming" models for Krasnoyarsk and Kantat reservoirs and in prognostication of radioecological state of great Yenisei river:1) radionuclide distribution in the Yenisei''s bottom sediment is nonuniform-"spotty"; 2) it is theoretically shown, that due to biological interactions and tro-phical radioniclide migration there is "spotive" type of space radionuclide distribution. The research is to make use of the novel methods of ecological biophysics:Monitoring:spectral analysis of surface waters (algal pigments), fluorescent techniques to evaluate productivity and condition of algae; rapid bioassays for water toxicity (bioluminescence, chemotaxis techniques). Kinetic experiments:microcosms on evaluating self-purification rates; special cultivators to evaluate the rates of growth of hydrobionts and radioactive engulfing, nutrition spectra; methods of finding growth limiting factors. Models:application of Bellman Principle to optimizing the river water use; theory and peculiarities of microbiological decomposition of pollutants in the river ecosystem. The composition of Prognostication Simulation Model is the next:1) hydrodynamical unit to calculate 2-dimensional space-time rate of stream on any depth; 2) hydrophysical unit to calculate:water temperature and level of solar radiation inside the water body; 3) ecosystem unit to calculate dynamic of concentration of phytoplankton, zooplankton, bacteria, major chemical matters and pollutants in water, content pollutants inside of hydrobionfs cells and dynamic of bentos; 4) radioe-cological unit to forecast the dynamic of radionuclides in the water body and bottom, their hydro-bont''s concentration; 5) database. Reservoirs and river models are provided by monitoring and kinetic experiments data.  相似文献   

Dissolved organic matter variations in coastal plain wetland watersheds: The integrated role of hydrological connectivity,land use,and seasonality          下载免费PDF全文

Jacob D. Hosen  Alec W. Armstrong  Margaret A. Palmer 《水文研究》2018,32(11):1664-1681

Dissolved organic matter (DOM) is integral to fluvial biogeochemical functions, and wetlands are broadly recognized as substantial sources of aromatic DOM to fluvial networks. Yet how land use change alters biogeochemical connectivity of upland wetlands to streams remains unclear. We studied depressional geographically isolated wetlands on the Delmarva Peninsula (USA) that are seasonally connected to downstream perennial waters via temporary channels. Composition and quantity of DOM from 4 forested, 4 agricultural, and 4 restored wetlands were assessed. Twenty perennial streams with watersheds containing wetlands were also sampled for DOM during times when surface connections were present versus absent. Perennial watersheds had varying amounts of forested wetland (0.4–82%) and agricultural (1–89%) cover. DOM was analysed with ultraviolet–visible spectroscopy, fluorescence spectroscopy, dissolved organic carbon (DOC) concentration, and bioassays. Forested wetlands exported more DOM that was more aromatic‐rich compared with agricultural and restored wetlands. DOM from the latter two could not be distinguished suggesting limited recovery of restored wetlands; DOM from both was more protein‐like than forested wetland DOM. Perennial streams with the highest wetland watershed cover had the highest DOC levels during all seasons; however, in fall and winter when temporary streams connect forested wetlands to perennial channels, perennial DOC concentrations peaked, and composition was linked to forested wetlands. In summer, when temporary stream connections were dry, perennial DOC concentrations were the lowest and protein‐like DOM levels the highest. Overall, DOC levels in perennial streams were linked to total wetland land cover, but the timing of peak fluxes of DOM was driven by wetland connectivity to perennial streams. Bioassays showed that DOM linked to wetlands was less available for microbial use than protein‐like DOM linked to agricultural land use. Together, this evidence indicates that geographically isolated wetlands have a significant impact on downstream water quality and ecosystem function mediated by temporary stream surface connections.  相似文献   

Decadal and seasonal changes in landcover at Padre Island: Implications for the role of the back-barrier in signaling island state change     

Kenton R. Fisher  Ryan C. Ewing  Orencio Duran Vinent 《地球表面变化过程与地形》2023,48(1):163-178

Long-term and seasonal geomorphological changes at Padre Island, Texas are identified and linked with potential external drivers. Aerial and satellite images from 1950 to 2018, monthly images from 2019 to 2020, and a 2018 LiDAR data set are used to assess long-term and seasonal geomorphological changes within a 50 km² area of Padre Island near Port Mansfield, Texas. Trends in landcover are evaluated by mapping and comparing the relative areal coverage of each facies. Vegetated dunes, absent initially, emerged in the fore-island and expanded into the back-barrier to cover 14% of the study area. The active vegetation-free back-barrier dune field steadily decreased in areal extent from 12% to 6% as vegetation spread. Nebkha dune coverage fluctuated between 4% and 7%. Expansive microbial mats colonized the wind tidal and deflation flats surrounding the vegetated dunes and back-barrier dune field giving rise to a remarkably different landscape over the 50-year period studied. An assessment of external forcing factors identifies increased rates of relative sea level rise and decreased sediment influx as the most likely primary factors driving the geomorphological changes. These changes have induced a widespread shift toward stabilization of island sediments by vegetation and microbial mats, which in turn has starved the back-barrier of sediments resulting in low rates of accretion and increased flooding. These findings highlight the sensitivity of the back-barrier and, in particular, the dune facies to changes in sea level and sediment supply, and show that microbial mats are effective at stabilizing island sediments and may be harbingers to barrier island response to rising sea level. As shown in this study, long-term monitoring of geomorphic facies changes and topography can detect important shifts in the island state that can be used to inform decision making for these sensitive coastal landscapes.  相似文献   

Crystallization pathways in the Great Artesian Basin (Australia) spring mound carbonates: Implications for life signatures on Earth and beyond     

Fulvio Franchi  Silvia Frisia 《Sedimentology》2020,67(5):2561-2595

Recent studies of continental carbonates revealed that carbonates with similar fabrics can be formed either by biotic, biologically-induced, biologically-influenced or purely abiotic processes, or a combination of all. The aim of this research is to advance knowledge on the formation of carbonates precipitated (or diagenetically altered) in extreme, continental environments by studying biotic versus abiotic mechanisms of crystallization, and to contribute to the astrobiology debate around terrestrial analogues of Martian extreme environments. Both fossil (upper Pleistocene to Holocene) and active carbonate spring mounds from the Great Artesian Basin (South Australia) have been investigated. These carbonates consist of low-Mg to high-Mg calcite tufa. Four facies have been described: (i) carbonate mudstone/wackestone; (ii) phytohermal framestone/boundstone; (iii) micrite boundstone; and (iv) coarsely crystalline boundstone. The presence of filaments encrusted by micrite, rich in organic compounds, including ultraviolet-protectants, in phytohermal framestone/boundstone and micrite boundstone is clear evidence of the existence of microbial mats at the time of deposition. In contrast, peloidal micrite, despite commonly being considered a microbial precipitate, is not directly associated with filaments in the Great Artesian Basin mounds. It has probably formed from nanocrystal aggregation on colloid particulate. Thus, where biofilms have been documented, it is likely that bacteria catalyzed the development of fabrics. It is less certain that microbes induced calcium carbonate precipitation elsewhere. Trace elements, including rare earth element distribution from laminated facies, highlight strongly evaporative settings (for example, high Li contents). Carbon dioxide degassing and evaporation are two of the main drivers for an increase in fluid alkalinity, resulting in precipitation of carbonates. Hence, although the growth of certain fabrics is fostered by the presence of microbial mats, the formation of carbonate crystals might be independent from it and mainly driven by extrinsic factors. More generally, biological processes may be responsible for fabric and facies development in micritic boundstone whilst micrite nucleation and growth are driven by abiotic factors. Non-classical crystallization pathways (aggregation and fusion of nanoparticles from nucleation clusters) may be more common than previously thought in spring carbonate and this should be carefully considered to avoid misinterpretation of certain fabrics as by-products of life. It is proposed here that the term ‘organic-compound catalyzed mineralization’ should be used for crystal growth in the presence of organic compounds when dealing with astrobiological problems. This term would account for the possibility of multiple crystallization pathways (including non-classical crystallization) that occurred directly from an aqueous solution without the direct influence of microbial mats.  相似文献   

Late Cambrian microbial build-ups,Llano Area,Central Texas: A three-phase morphological evolution     

Pankaj Khanna  Heath H. Hopson  André W. Droxler  Dylan A. Droxler  Daniel Lehrmann  Brian Kubik  Jacob Proctor  Pulkit Singh  Paul M. Harris 《Sedimentology》2020,67(2):1135-1160

Although Late Cambrian microbial build-ups were recognized in the Point Peak Member of the Wilberns Formation in Central Texas (USA) nearly 70 years ago, only a few studies focused specifically on the build-ups themselves. This study focuses on the interpretation of the regional (15 measured sections described in literature representing an area of 8000 km²) and local (field and drone photogrammetry studies in a 25 km² area from within south Mason County) microbial build-up occurrence, describes their growth phases and details their interactions with the surrounding inter-build-up sediments. The study establishes the occurrence of microbial build-ups in the lower and upper Point Peak members (the Point Peak Member is informally broken up into the lower Point Peak and the upper Point Peak members separated by Plectotrophia zone). The lower Point Peak Member consists of three <1 m thick microbial bioherms and biostrome units, in addition to heterolithic and skeletal/ooid grainstone and packstone beds. One, up to 14 m thick, microbial unit associated with inter-build-up skeletal and ooid grainstone and packstone beds, intercalated with mixed siliciclastic–carbonate silt beds, characterizes the upper Point Peak member. The microbial unit in the upper Point Peak member displays a three-phase growth evolution, from an initial colonization phase on flat based, rip-up clast lenses, to a second aggradation and lateral expansion phase, into a third well-defined capping phase. The ultimate demise of the microbial build-ups is interpreted to have been triggered by an increase of water turbidity caused by a sudden influx of fine siliciclastics. The lower Point Peak member represents inner ramp shallow subtidal and intertidal facies and the upper Point Peak member corresponds to mid-outer ramp subtidal facies. Understanding the morphological architecture and depositional context of these features is of importance for identifying signatures of early life on Earth.  相似文献   

鄱阳湖洲滩湿地植物演替对土壤微生物量的影响     

温秀婷  郑博福  陈晨晨  龚磊强  詹慧英  余定坤  朱致睿  沈瑞昌 《湖泊科学》2024,36(3):881-889

湿地植物演替对土壤微生物量具有显著影响,但不同土壤理化环境下的植物演替对湿地土壤微生物量影响的具体差异还不清楚。以鄱阳湖土壤理化性质不同的4个碟形子湖(包括相对肥沃的东湖和白沙湖以及相对贫瘠的蚌湖和大湖池)为研究对象,运用空间代替时间的方法,在泥滩带、湿生植被带(苔草)和挺水植被带(南荻或芦苇)采集0～10 cm表层土壤,分析不同土壤理化性质条件下植物群落演替对土壤微生物量的影响。采用土壤微生物量碳(MBC)和微生物熵(qMB)指示土壤微生物量。蚌湖、大湖池、东湖和白沙湖洲滩湿地表层土壤MBC的平均值分别为1077.27、888.29、942.45和1162.46 mg/kg,土壤qMB的平均值分别为6.07%、6.17%、3.60%和3.79%。在泥滩—苔草—南荻植物演替洲滩,土壤MBC先增加后减少;但是在泥滩—苔草—芦苇植物演替洲滩,土壤MBC持续增加。植物演替没有显著改变土壤qMB。尽管植物的生长会增加所有洲滩湿地的土壤MBC,但增加的幅度在相对贫瘠的蚌湖和大湖池明显强于相对肥沃的东湖和白沙湖。蚌湖和大湖池的土壤qMB也显著高于东湖和白沙湖。在植被演替梯度上,洲滩湿地土壤MBC和...  相似文献   

过硫酸氢钾复合物对对虾养殖底泥硝化作用、氨氧化微生物丰度和群落结构的影响     

赵珍  王宝杰  刘梅  蒋克勇  王雷 《海洋科学》2021,45(11):54-61

采用在模拟池塘中投放过硫酸氢钾复合物（KMPS）进行对比实验的方法,探究KMPS对养殖底质硝化作用的影响。通过对氨氮和亚硝态氮含量的检测,探究对不同时期氮素转化的影响,低频率高剂量投放组中的氨氮和亚硝态氮含量显著降低,而高频率低剂量组中氨氮和亚硝态氮的含量显著上升。高频率低剂量KMPS的投放使氨氧化古菌（AOA）和氨氧化细菌（AOB）丰度降低,而低频率高剂量KMPS的投放不会造成丰度降低,而且还表现出部分时期AOB丰度的上升。进一步对群落结构进行分析发现KMPS的投放使AOA群落中Nitrosopumilu属相对丰度降低,Nitrososphaera属的相对丰度上升,这种相对丰度的变化与KMPS的投放方式无关;但AOB群落受到KMPS投放方式的影响,低频率高剂量的KMPS投放下AOB群落优势属相对丰度显著提高。以上结果均说明低频率高剂量KMPS的投放起到了促进底质硝化作用的效果。同时,可为KMPS用于对虾养殖池塘底质改良开辟一个新的途径。  相似文献   

高产壳聚糖酶菌株的筛选和发酵产酶条件研究   总被引：13，自引：1，他引：12  

逄玉娟  韩宝芹  刘万顺  杨菊林 《中国海洋大学学报(自然科学版)》2005,35(2):287-292

为探讨专一性地降解甲壳质或壳聚糖的甲壳质酶或壳聚糖酶 ,从采集的土样中分离到 4株产壳聚糖酶能力较强的菌株 ,经摇瓶复筛 ,菌株YJ0 2产酶能力最强。对其发酵产酶条件的研究结果表明其产酶最适培养基组分为 (% ,w/v) :粉末壳聚糖 2 .0 ,葡萄糖 0 .1,NH4NO3 1.0 ,酵母提取物 0 .5 ,K2 HPO40 .0 7,KH2 PO40 .0 3 ,NaCl0 .5 ,MgSO4·7H2 O 0 .0 5 ,起始 pH 6.0。最适产酶培养条件是 :5 0 0mL三角烧瓶装瓶量为 15 0mL ,2 .0 % (v/v)接种量 ,3 0℃ ,15 0r/min培养 72h。在最适产酶培养条件下 ,72h时菌株YJ0 2发酵液中壳聚糖酶活力可达到 17.0 4U/mL。  相似文献   

地表灌溉对沉积含水层中碘迁移释放过程的影响     

周海玲  苏春利  李俊霞 《吉林大学学报(地球科学版)》2018,48(6):1810-1820

灌溉等人为活动会造成外源物质的输入,如硝酸盐、有机质等,从而引起浅层地下水环境发生周期性波动。为研究农业灌溉对沉积含水层中碘迁移富集过程的影响,选取代表性富碘沉积物,通过室内实验模拟了灌溉活动外源物质输入条件下,盆地地下水系统中碘迁移释放的（生物）地球化学过程。实验结果表明：厌氧条件下,外源有机质输入可促使微生物利用有机质作为电子供体,还原固相铁矿物相,进而造成搭载于铁氧化物/氢氧化物表面的碘释放,以碘离子形式在地下水中富集;而在NO₃^-输入情况下,微生物会优先利用NO₃^-为电子受体,至硝酸盐被全部消耗后,Fe（Ⅲ）可进一步被还原为Fe（Ⅱ）。研究结果表明,人为活动造成浅表环境外源物质的输入可直接影响浅层地下水中碘的迁移释放过程。伊利石黏土矿物吸附的铁氧化物矿物相可能为浅层环境中碘的主要搭载介质,微生物作用下,铁氧化物/氢氧化物的还原溶解是高碘地下水形成的主控因素。  相似文献