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1.
湖泊生态系统产甲烷与甲烷氧化微生物研究进展 总被引：3，自引：1，他引：2
湖泊生态系统是重要的大气甲烷来源,其甲烷释放量占全球自然生态系统的40%.产甲烷和甲烷氧化微生物在湖泊甲烷生产和消耗过程中发挥关键作用.本文综述了近期有关湖泊生态系统甲烷产生与氧化过程的研究进展,重点介绍产甲烷与甲烷氧化微生物在湖泊中的分布特征、代谢途径以及调控机制.现有研究表明,湖泊中甲烷的生成不仅仅依靠赋存于沉积物和水体厌氧层的产甲烷古菌,还可能来自有氧环境中其他产甲烷微生物的代谢作用.湖泊中的甲烷在脱离水体逸散至大气之前,被甲烷氧化微生物利用,转化成二氧化碳和小分子有机化合物(如甲醇、甲醛和甲酸等).除了传统依赖氧气作为电子受体的好氧氧化过程外,新近研究还揭示了多种厌氧甲烷氧化过程,包括依赖还原硫酸盐、硝酸盐和亚硝酸盐以及Fe~(3+)/Mn~(4+)等金属离子的甲烷氧化过程.文献综合分析表明,反硝化型厌氧甲烷氧化过程主要发生在淡水湖泊中,而硫酸盐还原型主要发生在高盐度或者高碱度湖泊中.水体温度、溶解氧浓度可以显著影响产甲烷与甲烷氧化微生物的丰度与群落结构,其他湖泊环境条件,如盐度、pH和有机质类型等都可能改变产甲烷与甲烷氧化微生物的分布和代谢活性.不同湖泊类型的比较研究,有助于全面掌握影响湖泊产甲烷与甲烷氧化微生物的时空分布与代谢特征的主导因素. 相似文献
2.
草海是由喀斯特盆地积水发育而形成的一个完整的、典型的高原湖泊湿地生态系统,同时也是中国面积最大的岩溶构造湖.甲烷氧化菌作为一类能够将甲烷氧化为CO2和水的独特微生物,其活动与生态系统中能量流动和元素循环的关键步骤密不可分.为了解贵州草海喀斯特高原湖泊湿地中甲烷氧化菌的群落结构特征及功能,利用宏基因组技术对浅水沼泽、莎草湿地、深水沉积物进行研究.结果表明,草海湿地中主要的好氧甲烷氧化菌为Methylobacter和Methylomonas,主要的厌氧甲烷氧化菌为Candidatus_Methylomirabilis_oxyfera,属于NC10门的反硝化型厌氧甲烷氧化菌.所研究的4种代谢功能基因种类多样性表现为碳代谢＞氮代谢＞硫代谢＞甲烷代谢;基于KEGG数据库共注释到6大类功能和18条与碳、甲烷、氮、硫相关的完整代谢路径.PCoA分析表明浅水沼泽和莎草湿地中甲烷氧化菌的种类和功能相似,且与深水沉积物存在差异.物种与功能相关性网络分析结果显示Methylacidiphilum_fumariolicum和Methylacidiphilum_kamchatkense与草海湖泊湿地中的各个代谢功能均具有较强的相关性.显著影响草海湿地中大多数甲烷氧化菌的群落结构的环境因素是硝酸盐、电导率、总磷和有机质. 相似文献
3.
城市河流沉积物中氮素与好氧甲烷氧化菌群落特征响应关系 总被引：1，自引：0，他引：1
由于人类活动的影响大量未经处理的废污水汇入城市河流,高浓度的污染物影响了河流中微生物对生物地球化学物质迁移和转化的介导作用.本文选取典型的城市河流——北运河作为研究区域,分析了北运河沉积物中氮素形态以及含量的空间和季节差异性,并结合克隆文库分子生物学的方法,探讨了氮素形态和含量的差异对好氧甲烷氧化菌(aerobic methane-oxidizing microorganisms,MOB)群落特征的影响.结果表明:北运河沉积物中铵态氮(NH_4~+-N)为氮素的主要存在形态,存在显著的空间差异,其含量在下游显著高于上游,但季节差异不显著.NH_4~+-N含量的空间差异对MOB的群落结构和群落分布有显著影响,对群落多样性影响不显著.NH_4~+-N含量的空间分布特征与MOB的群落聚类特征一致,NH_4~+-N对MOB群落分布的影响显著高于其他形态的氮素,其含量越高,则与MOB群落分布的响应关系越紧密.北运河中NH_4~+-N的来源影响了沉积物中MOB的主要来源,MOB高同源性菌群的来源与NH_4~+-N等主要污染物的来源一致.沉积物中MOB物种之间联系的紧密程度依赖于氮素的主要存在形态及其含量水平.NH_4~+-N含量较高的下游沉积物中微生物彼此之间关系及集聚程度更强,受外界环境变化的干扰程度更强,受人类活动引起环境变化的敏感程度更高.城市河流中氮素的形态和含量差异对甲烷的氧化过程有显著影响.探究城市河流沉积物中高含量的NH_4~+-N对甲烷产生及消耗的影响过程是控制河流温室气体排放的关键. 相似文献
4.
《中国科学:地球科学》2018,(12)
在世纪时间尺度上,甲烷的全球增温潜势大约是二氧化碳的30倍.甲烷排放被认为导致了地球史上多次全球气候变化事件的发生和大规模的物种灭绝现象.因此,研究甲烷生成过程对于理解全球气候变化至关重要.长期以来一直认为,海洋中可检测到的生源甲烷完全是由低氧和无氧环境中产甲烷古菌的厌氧代谢活动产生的.但是,有众多研究报道显示,全球海洋范围内的许多含氧表面水体和近表水体中的甲烷是过饱和的,由此造成向大气甲烷净排放.含氧海水生成甲烷的现象被称为"海洋甲烷悖论".尽管该悖论仍未完全得到解决,但是最近的研究已经提出了一些有关含氧海水中甲烷生成的科学假说.文章将对甲烷在全球气候中的重要性的理解进行总结,并分析含氧海水环境中甲烷生成的生物过程及其机理.此外,我们将初步探讨相关微生物代谢过程与气候及海洋环境的全球性变化之间的关系. 相似文献
5.
青藏高原达索普冰芯2 ka来温度与甲烷浓度变化记录 总被引：14，自引：0，他引：14
通过对喜马拉雅山达索普冰芯气泡中包裹气体的提取分析和对冰芯中氧同位素分析, 讨论了近2 ka来达索普冰芯记录的温度与大气甲烷浓度的变化. 结果表明, 该冰芯中d 18O记录所反映的温度变化事件与青藏高原北部的敦德冰芯记录的气候事件及中国东部乃至北半球的温度变化趋势十分相似, 近百年来的升温趋势同中世纪暖期时的升温趋势基本一致; 自工业革命以来, 达索普冰芯气泡中记录的甲烷浓度呈快速的增长趋势, 与全球大气甲烷浓度的变化趋势一致. 工业革命以前, 达索普冰芯记录的大气中甲烷浓度在825 nmol·mol-1上下波动, 是目前青藏高原大气中CH4浓度(2000±100 nmol·mol-1)的40%左右. 与南极及格陵兰同时代的冰芯记录相比, 达索普冰芯中记录的CH4浓度要高出15%~20%左右, 而且达索普冰芯甲烷浓度具有更强的波动性, 这种波动与温度变化关系紧密. 相似文献
6.
陆地-大气和陆地-水体的碳输送与碳交换共同决定了陆地生态系统的碳平衡,但长期以来青藏高原水体由于缺乏有效的观测数据,导致青藏高原水体一直是全球碳循环研究中被忽视的碳汇功能区。本研究聚焦青藏高原水体,重新认知水体碳侵蚀与碳沉积对青藏高原固碳的重要作用,系统分析河湖库-大气间的碳运移与交换时空格局与驱动机制。通过归纳总结发现:(1)青藏高原河流岩石风化速率以及CO2消耗速率较高,强烈的侵蚀作用对地球系统吸收和平衡CO2浓度起着重要的调控作用;(2)青藏高原湖泊是内陆生态系统的重要碳库,12 ka以来湖泊沉积物碳储量约为73 kg C/m2;(3)青藏高原湖泊浮游植物和水生植物影响内陆水体C沉积,年均初级生产力达(553±36) mg C/(m2·d)。(4)青藏高原湖泊目前为“碳源”,碳排放量约为2.27 Tg C/a。此外,本文还阐明青藏高原水体碳源汇过程评估的不确定性,以及从方法学角度分析如何加强其水体的碳循环研究,厘清全球变化下青藏高原水体的碳源汇机制,并展望了青藏高原水体碳源汇功能未来研究所面临... 相似文献
7.
膦酸酯是新近发现的一类生物可利用磷,其广泛存在于水生生态系统,是水体有机磷库的重要组成,构成水体磷氧化还原循环的关键环节。随着研究的深入,越来越多的蓝藻藻株被证实参与膦酸酯的生物利用与合成,有助于阐明其适应低磷环境的机制,促进了对蓝藻磷策略与水体磷循环的全面理解,具有重要的生态学意义。与此同时,蓝藻对膦酸酯的利用性状,使得膦酸酯作为环境污染物与蓝藻磷源的双重作用开始显现,这会对水体浮游生物竞争格局的研究产生深远影响;而蓝藻的甲基膦酸代谢也被认为是水体好氧甲烷发生的来源之一。本文回顾了蓝藻膦酸酯利用与合成的研究历史,对目前蓝藻膦酸酯代谢过程生态风险与生态意义的研究进展进行了梳理,并对这一领域未来发展趋势进行了评述。 相似文献
8.
《中国科学:地球科学》2017,(12)
埃迪卡拉纪(635~541Ma)记录了地质历史上最大的全球碳循环扰动事件(即"Shuram Excursion"事件,简称SE事件).在约25~50个百万年的时间里,全球海水无机碳同位素组成持续负偏,最大负偏至–12‰.这一碳同位素负偏被认为是当时古海洋中存在的超大型溶解有机碳库被完全氧化或空间差异性氧化的结果,同时也被认为是古海洋微型生物碳泵强烈储碳而形成超大型溶解有机碳库的关键证据.随着研究的深入,这一认识受到了挑战,新假说认为陆源沉积老碳的氧化或古海洋海底释放的富烃流体的氧化同样可以导致这一碳循环扰动事件.为解决这一争论,本文基于碳循环质量平衡原理对上述各种假说进行了数值模拟与评估,结果表明:(1)在给定的埃迪卡拉纪大气氧水平下(≤40%目前大气氧水平),全球规模的陆源有机碳氧化假说和溶解有机碳完全氧化假说受限于氧化剂,大气氧将分别在4Myr和6Myr内消耗殆尽,难以在长时间尺度上形成全球规模的–12‰碳同位素负偏信号;(2)全球范围内的富烃流体氧化假说由于对参加反应的流体烃类的需求量过大也面临挑战;(3)全球海洋溶解有机碳库的空间差异性氧化(部分氧化)假说所要求的DOC库部分氧化(50%)所需的氧化剂和DOC总量都具有可行性. 相似文献
9.
三种碳源对乌梁素海好氧不产氧光合细菌群落结构的影响 总被引：3，自引：1，他引：2
好氧不产氧光合细菌(AAPB)营光合异养,在水体碳循环中起着重要作用.但是,碳源对AAPB群落结构的影响尚不明确.本文基于16S rDNA和光合反应中心合成中的关键基因——pufM基因,运用变性梯度凝胶电泳(DGGE)技术,比较分析了在微生物分离培养中常用的3种碳源(葡萄糖、丙酮酸钠、酵母提取物)对乌梁素海水体总细菌及AAPB群落结构的影响.结果表明,不同碳源诱导7~21 d后,水体总细菌群落丰富度及多样性指数均有不同程度的提升,AAPB群落则呈现先升后降的趋势.3种碳源中,丙酮酸钠添加后对总细菌及AAPB菌群的丰富度和多样性的提升效果最好.测序及系统发育结果表明,乌梁素海水体经诱导后新检测到了一些原环境中未发现的菌属,一些具有特殊碳代谢能力的菌属丰度得到了提升.本研究为充分认识和理解AAPB的生态学作用和意义,及其富集、分离和培养提供了基础依据. 相似文献
10.
富营养化湖泊夏季表层水体温室气体浓度及其影响因素 总被引：6，自引：5，他引：1
为研究富营养化湖泊水体温室气体浓度及其影响因素,以太湖西岸和竺山湾为例,共调查研究了27个点位,采用顶空平衡法对其表层水体中溶解的甲烷(CH_4)和氧化亚氮(N_2O)浓度进行测定.结果表明,太湖近岸带蓝藻水华堆积区表层水体中CH_4和N_2O两种温室气体浓度远远高于开阔湖区点位,CH_4和N_2O最高浓度分别为3.79±0.095和0.078±0.003μmol/L.蓝藻水华堆积区和开阔湖区CH_4平均浓度分别为2.33±1.46和0.14±0.059μmol/L,N_2O的平均浓度分别为0.054±0.024和0.023±0.012μmol/L.两种气体在水中均呈现过饱和状态,其中蓝藻水华堆积区表层水体中CH_4和N_2O饱和度远远高于开阔湖区点位.此外,入湖河流河口区域表层水体溶解性N_2O浓度较高.将水中CH_4和N_2O浓度与水体环境因子之间进行相关性分析,表明水体总氮、总磷、铵态氮和溶解性有机碳浓度与CH_4和N_2O浓度呈显著正相关,CH_4浓度与硝态氮浓度呈显著负相关.研究结果揭示了太湖蓝藻水华堆积区是CH_4和N_2O两种温室气体重要的潜在排放源,蓝藻水华暴发对湖泊温室气体的排放具有重要影响,但该过程的驱动机制及影响因素仍需要进一步研究. 相似文献
11.
C. J. Schubert F. S. Lucas E. Durisch-Kaiser R. Stierli T. Diem O. Scheidegger F. Vazquez B. Müller 《Aquatic Sciences - Research Across Boundaries》2010,72(4):455-466
The build-up of methane in the hypolimnion of the eutrophic Lake Rotsee (Lucerne, Switzerland) was monitored over a full year. Sources and sinks of methane in the water column were characterized by measuring concentrations and carbon isotopic composition. In fall, high methane concentrations (up to 1 mM) were measured in the anoxic water layer. In the oxic layer, methane concentrations were much lower and the isotopic composition shifted towards heavy carbon isotopes. Methane oxidation rates peaked at the interface between oxic and anoxic water layers at around 8–10 m depth. The electron balance between the oxidants oxygen, sulphate, and nitrate, and the reductants methane, sulphide and ammonium, matched very well in the chemocline during the stratified season. The profile of carbon isotopic composition of methane showed strong indications for methane oxidation at the chemocline (including the oxycline). Aerobic methane oxidizing bacteria were detected at the interface using fluorescence in situ hybridization. Sequencing the responsible organisms from DGGE bands revealed that aerobic methanotrophs type I closely related to Methylomonas were present. Sulphate consumption occurred at the sediment surface and, only towards the end of the stagnation period, matched with a zone of methane consumption. In any case, the flux of sulphate below the chemocline was not sufficient to oxidize all the methane and other oxidants like nitrate, iron or manganese are necessary for the observed methane oxidation. Although most of the methane was oxidized either aerobically or anaerobically, Lake Rotsee was still a source of methane to the atmosphere with emission rates between 0.2 mg CH4 m?2 day?1 in February and 7 mg CH4 m?2 day?1 in November. 相似文献
12.
Dan Lei Jia Liu Junwei Zhang Andreas Lorke Shangbin Xiao Yuchun Wang Wei Wang Ye Li 《洁净——土壤、空气、水》2019,47(9)
Four field campaigns are carried out to quantify the methane (CH4) oxidation rate in Xiangxi Bay (XXB) of the Three Gorges Reservoir (TGR), China. The water depth of the sampling site varied from 13 to 30 m resulting from the water level fluctuation of the TGR. The CH4 oxidation rates are measured in situ as the decline of dissolved CH4 concentration versus time in incubated, and those rates. The CH4 oxidation rates range from 1.18 × 10?3 to 3.69 × 10?3 µmol L?1 h?1, with higher values and stronger variation during summer. A static floating chamber method is used to measure CH4 emitted to the atmosphere resulting in an annual mean flux of 4.79 µmol m?2 h?1. The CH4 emission rate is significantly negatively correlated with the water level. The results show that a large fraction of CH4 is consumed in the water column with a range of 28.97–55.90 µmol m?2 h?1, accounting for ≈69–98% of the total CH4 input into the water column, and more than 90% is consumed outside the summer, when the water level is lowest. Water depth, which is dominated by water level of the TGR, is a potentially important driver for CH4 oxidation and atmospheric emission in the tributary bay. 相似文献
13.
The global warming potential of methane (CH4) is about 30 times stronger than that of carbon dioxide (CO2) over a century timescale. Methane emission is hypothesized to have contributed to global climate change events and mass extinctions during Earth’s history. Therefore, the study of CH4 production processes is critically important to the understanding of global climate change. It has been a dogma that biogenic CH4 detectable in the oceans originates exclusively from the anaerobic metabolic activity of methanogenic archaea in hypoxic and anoxic environments, despite reports that many oxic surface and near-surface waters of the world’s oceans are CH4-supersaturated, thereby rendering net sea-to-air emissions of CH4. The phenomenon of CH4 production in oxic marine waters is referred to as the “ocean methane paradox”. Although still not totally resolved, recent studies have generated several hypotheses regarding the sources of CH4 production in oxic seawater. This review will summarize our current understanding of the importance of CH4 in the global climate and analyze the biological processes and their underpinning mechanisms that lead to the production of CH4 in oxic seawater environments. We will also tentatively explore the relationships of these microbial metabolic processes with global changes in climate and environment. 相似文献
14.
A. N. Dzyuban 《Water Resources》2011,38(5):615-620
Concentration of dissolved methane was determined in the water of some tributaries of the Rybinsk Reservoir subject to different
anthropogenic impact; the features of its distribution and the extent of transformations in summer are shown. Its concentration
in water of the mouth areas varies within the limits of 2.2 to 280 μl CH4/l; the rate of methane oxidation is 0.01–230 μl CH4/(l day). Methanogenesis processes with a rate of 15–28 μl CH4/(l day) were recorded in surface waters of heavily polluted rivers. A correlation was found to exist between the characteristics
of methane cycle and the ecological conditions of the water body. 相似文献
15.
The concentrations of two greenhouse gases, nitrous oxide (N2O) and methane (CH4), and the bacterial processes involved in their production (nitrification and denitrification for N2O, and methanogenesis for CH4), were determined in surface waters of two coastal areas under the influence of freshwater inputs, on one part in the Gulf of Lions and the Rhone River plume, in northwestern Mediterranean Sea, and on the other part in the inner Thermaikos Gulf, in Aegean Sea, eastern Mediterranean Sea. High concentrations of dissolved CH4 and N2O were recorded in the surface waters of Gulf of Lions and Gulf of Thermaikos, up to 1300 nM for CH4, and 40 nM for N2O. No direct relationship could be found between the concentration and production of the biogases, as they may also be produced in deep water or bottom sediment in shallow areas, or derived from anthropogenic activity or ship contamination in polluted areas. Irrespective of the origin of CH4 and N2O, the presence of extremely high concentrations of these two gases in superficial seawater implies that they can easily escape to the atmosphere; consequently, these nearshore waters enriched in greenhouse gases may play an important role in the increase in atmospheric concentration of both CH4 and N2O. 相似文献
16.
Carbon dioxide (CO2) and methane (CH4) concentrations and evasion rates were measured in surface waters draining Mer Bleue peatland (Ontario, Canada) between spring and autumn 2005. All sites exhibit a consistent pattern of supersaturation throughout the year, which is broadly related to hydrological and temperature changes between spring snowmelt and autumn freezing. Both measurements and estimates of CO2 and CH4 evasion from open water to the atmosphere suggest that parts of the catchment (including beaver dams) are significant degassing hot spots. We present data showing how vertical gaseous carbon fluxes compare with lateral carbon fluxes and make an initial estimate of the importance to the overall carbon budget of CO2 and CH4 evasion to the atmosphere from water surfaces at Mer Bleue. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
17.
J. Schneider von Deimling G. Rehder J. Greinert D.F. McGinnnis A. Boetius P. Linke 《Continental Shelf Research》2011,31(7-8):867-878
Tommeliten is a prominent methane seep area in the Central North Sea. Previous surveys revealed shallow gas-bearing sediments and methane gas ebullition into the water column. In this study, the in situ methane flux at Tommeliten is re-assessed and the potential methane transport to the atmosphere is discussed, with regards to the hydrographic setting and gas bubble modeling. We have compiled previous data, acquired new video and acoustic evidence of gas bubble release, and have measured the methane concentration, and its C-isotopic composition in the water column. Parametric subbottom sonar data reveal the three-dimensional extent of shallow gas and morphologic features relevant for gas migration. Five methane ebullition areas are identified and the main seepage area appears to be 21 times larger than previously estimated. Our video, hydroacoustic, subbottom, and chemical data suggest that ～1.5×106 mol CH4/yr (～26 tons CH4/yr) of methane gas is being released from the seepage area of Tommeliten. Methane concentration profiles in the vicinity of the gas seeps show values of up to 268 nM (～100 times background) close to the seafloor. A decrease in δ13C-CH4 values at 40 m water depth indicates an unknown additional biogenic methane source within the well oxygenated thermocline between 30 and 40 m water depth. Numerical modeling of the methane bubbles due to their migration and dissolution was performed to estimate the bubble-derived vertical methane transport, the fate of this methane in the water column, and finally the flux to the atmosphere. Modeling indicates that less than ～4% of the gas initially released at the seafloor is transported via bubbles into the mixed layer and, ultimately, to the atmosphere. However, because of the strong seasonality of mixing in the North Sea, this flux is expected to increase as mixing increases, and almost all of the methane released at the seafloor could be transferred into the atmosphere in the stormy fall and winter time. 相似文献
18.
Matthias Koschorreck Katrin Wendt-Potthoff Burkhard Scharf Hans H. Richnow 《Journal of Volcanology and Geothermal Research》2008
The biogeochemistry of methane in the sediments of Lake Caviahue was examined by geochemical analysis, microbial activity assays and isotopic analysis. The pH in the water column was 2.6 and increased up to a pH of 6 in the deeper sediment pore waters. The carbon isotope composition of CH4 was between − 65 and − 70‰ which is indicative for the biological origin of the methane. The enrichment factor ε increased from − 46‰ in the upper sediment column to more than − 80 in the deeper sediment section suggesting a transition from acetoclastic methanogenesis to CO2 reduction with depth. In the most acidic surface layer of the sediment (pH < 4) methanogenesis is inhibited as suggested by a linear CH4 concentration profile, activity assays and MPN analysis. The CH4 activity assays and the CH4 profile indicate that methanogenesis in the sediment of Lake Caviahue was active below 40 cm depth. At that depth the pH was above 4 and sulfate reduction was sulfate limited. Methane was diffusing with a flux of 0.9 mmol m− 2 d− 1 to the sediment surface where it was probably oxidized. Methanogenesis contributed little to the sediments carbon budget and had no significant impact on lake water quality. The high biomass content of the sediment, which was probably caused by the last eruption of Copahue Volcano, supported high rates of sulfate reduction which probably raised the pH and created favorable conditions for methanogens in deeper sediment layers. 相似文献
19.
Specific features of CH4 distribution and the extent of its transformations in the water of reservoirs in the Upper Volga basin are considered. Methanogenesis was detected in water at some stations. The quantitative characteristics of CH4 and methane oxidation are shown to correlate with the environmental conditions of the reservoir. 相似文献
20.
The influence of winter on methane (CH4) stored in pore water and emitted through snow was investigated in a temperate poor fen in New Hampshire over two winters. Methane accumulated beneath ice layers (1 cm) deposited by freezing rain, resulting in snow-pore air mixing ratios as high as 140 ppmv during the first winter and 600 ppmv during the second. An early winter snow crust of 300 kg m?3 caused no discontinuity in a linear mixing ratio profile and therefore was not observed to retard snowpack emissions. Methane concentration-depth profiles in pore water steepened and concentrations increased by as much as 400 μM at the 10 and 20 cm depths as the ice cover formed. This suggests that the peat-ice cover plays an important part in CH4 build-up in pore water by limiting the transport of gases between the peat and the atmosphere. Pore water concentrations gradually declined through late winter. The seasonality of dissolved CH4 in pore water over two winters and one summer showed an average annual amplitude of 1.3 gCH4m?2 (25–75cm depth range), with a winter maximum of 4.7gCH4m?2. Emissions during the winter with average snowfall accounted for a larger percentage (9.2% in 1993–1994) of total annual emission than the winter with below-average snowfall and warmer air temperature (2% in 1994–1995). Emissions averaged 56 and 26mg m?2 day?1 during the first and second winter (December, January and February), respectively. 相似文献