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1.
Microbial populations in contaminant plumes 总被引：4，自引：1，他引：3
Received, May 1999/Revised, October 1999/Accepted, October 1999 相似文献
2.
Francis H. Chapelle 《Hydrogeology Journal》2000,8(1):41-46
2 (methanogenesis). In aquifers contaminated by anthropogenic contaminants, an excess of available organic carbon often exists,
and microbial metabolism is limited by the availability of electron acceptors. In addition to changes in groundwater chemistry,
the solid matrix of the aquifer is affected by microbial processes. The production of carbon dioxide and organic acids can
lead to increased mineral solubility, which can lead to the development of secondary porosity and permeability. Conversely,
microbial production of carbonate, ferrous iron, and sulfide can result in the precipitation of secondary calcite or pyrite
cements that reduce primary porosity and permeability in groundwater systems.
Received, January 1999/Revised, July 1999, August 1999/Accepted, October 1999 相似文献
3.
Influence of dissimilatory metal reduction on fate of organic and metal contaminants in the subsurface 总被引：5，自引：0，他引：5
Geobacter become dominant members of the microbial community when Fe(III)-reducing conditions develop as the result of organic contamination,
or when Fe(III) reduction is artificially stimulated. These results suggest that further understanding of the ecophysiology
of Geobacter species would aid in better prediction of the natural attenuation of organic contaminants under anaerobic conditions and in
the design of strategies for the bioremediation of subsurface metal contamination.
Received, May 1999/Revised, October 1999/Accepted, October 1999 相似文献
4.
Recent studies on bacterial populations and processes in subseafloor sediments: A review 总被引：22，自引：0，他引：22
Subsurface bacteria also occur in hydrothermal sediments with large temperature gradients (up to 12 °C/m) and with population
numbers similar to non-hydrothermal sites at temperatures from psychrophilic to mesophilic. At greater depths and temperatures,
populations decline rapidly, but they are still significant up to hyperthermophilic temperatures and are even stimulated by
subsurface seawater flow. These results suggest that temperature alone does not limit bacteria in non-hydrothermal sediments
until about 4 km, and evidence exists that bacterial processes may even be sustained by interaction with thermogenic processes
as temperatures increase during deep burial.
Experiments demonstrate that in the presence of readily degradable organic substrates, actively growing bacteria can move
faster than sediment deposition; hence, these bacteria are not necessarily trapped and buried. However, bacterial growth decreases
with depth to such an extent that subsurface bacteria would not be able to keep up with sedimentation rate and hence would
be buried. In some circumstances, such as in sapropel layers with high organic matter in the Mediterranean, bacteria may be
buried within a specific deposition horizon. Subsurface bacteria can utilize old and recalcitrant organic matter, but only
very slowly, and they seem to have a strategy of high biomass and low growth rate, commensurate with their geological habitat
of generally low energy flux.
Received, March 1999/Revised, August 1999/Accepted, November 1999 相似文献
5.
Modeling microbial processes in porous media 总被引：8，自引：1，他引：7
The incorporation of microbial processes into reactive transport models has generally proceeded along two separate lines
of investigation: (1) transport of bacteria as inert colloids in porous media, and (2) the biodegradation of dissolved contaminants
by a stationary phase of bacteria. Research over the last decade has indicated that these processes are closely linked. This
linkage may occur when a change in metabolic activity alters the attachment/detachment rates of bacteria to surfaces, either
promoting or retarding bacterial transport in a groundwater-contaminant plume. Changes in metabolic activity, in turn, are
controlled by the time of exposure of the microbes to electron acceptors/donor and other components affecting activity. Similarly,
metabolic activity can affect the reversibility of attachment, depending on the residence time of active microbes. Thus, improvements in quantitative analysis of active
subsurface biota necessitate direct linkages between substrate availability, metabolic activity, growth, and attachment/detachment
rates. This linkage requires both a detailed understanding of the biological processes and robust quantitative representations
of these processes that can be tested experimentally. This paper presents an overview of current approaches used to represent
physicochemical and biological processes in porous media, along with new conceptual approaches that link metabolic activity
with partitioning of the microorganism between the aqueous and solid phases.
Received, January 1999 · Revised, June 1999, July 1999 · Accepted, October 1999 相似文献
6.
macroscale processes that perturb general groundwater chemistry and therefore mineral–water equilibria; and microscale interactions, where attached organisms locally perturb mineral–water equilibria, potentially releasing limiting trace nutrients
from the dissolving mineral.
In the contaminated unconfined glacio-fluvial aquifer near Bemidji, Minnesota, USA, carbonate chemistry is influenced primarily
at the macroscale. Under oxic conditions, respiration by native aerobic heterotrophs produces excess carbon dioxide that promotes
calcite and dolomite dissolution. Aerobic microorganisms do not colonize dolomite surfaces and few occur on calcite. Within
the anoxic groundwater, calcite overgrowths form on uncolonized calcite cleavage surfaces, possibly due to the consumption
of acidity by dissimilatory iron-reducing bacteria. As molecular oxygen concentration increases downgradient of the oil pool,
aerobes again dominate and residual hydrocarbons and ferrous iron are oxidized, resulting in macroscale carbonate-mineral
dissolution and iron precipitation.
Feldspars, in contrast, weather exclusively at the microscale near attached microorganisms, principally in the anoxic region
of the plume. Native organisms preferentially colonize feldspars that contain trace phosphorus as apatite inclusions, apparently
as a consequence of the low P concentration in the groundwater. These feldspars weather rapidly, whereas nearby feldspars
without trace P are uncolonized and unweathered. Feldspar dissolution is accompanied by the precipitation of secondary minerals,
sometimes on the bacterial cell wall itself.
These observations suggest a tightly linked biogeochemical system whereby microbial processes control mineral diagenesis at
many scales of interaction, and the mineralogy and mineral chemistry influence microbial ecology. Only the macroscale interaction,
however, is easily observable by standard geochemical methods, and documentation of the microscale interactions requires microscopic
examination of microorganisms on mineral surfaces and the locally intense diagenetic reactions that result.
Received, May 1999/Revised, October 1999/Accepted, October 1999 相似文献
7.
Current knowledge on groundwater microbial pathogens and their control 总被引：12，自引：2，他引：10
Received, January 1999/Revised, July 1999, August 1999/Accepted, October 1999 相似文献
8.
Received: 23 March 1999 / Accepted: 25 August 1999 相似文献
9.
Received: 10 May 1999 / Accepted: 16 October 1999 相似文献
10.
以南京市运粮河沉积物为研究对象,通过磷脂脂肪酸(PLFA)技术分析了不同水期城市纳污河流沉积物微生物群落结构特征。结果表明:在不同的水期运粮河沉积物微生物量出现了显著差异,温度是导致微生物量在丰、平、枯三期出现显著差异的主要因素(P<0.05);在相同水期,营养物质含量高的地方对应着高的微生物量;16:0 iso、17:0 anteiso、15:0 iso这几种PLFA所指示的革兰氏阳性菌(G+)是影响运粮河沉积物微生物群落构成的主要菌落,导致沉积物微生物群落结构出现显著差异的环境因素是水期;单不饱和/支链脂肪酸比值可以作为反映水环境系统整体营养水平的指标,在C/N比值升高时微生物会将单不饱和脂肪酸转变成环丙基或者饱和脂肪酸以适应新的环境;PLFA含量比[c(i15:0)+c(i17:0)]/[c(a15:0)+c(a17:0)]可以作为指示水环境碳素含量的标志。 相似文献
11.
R. Scherreiks 《International Journal of Earth Sciences》2000,89(1):90-107
Received: 25 June 1999 / Accepted: 30 November 1999 相似文献
12.
M. Friberg A. Larionov G. A. Petrov D. G. Gee 《International Journal of Earth Sciences》2000,89(1):21-39
Received: 7 May 1999 / Accepted: 2 November 1999 相似文献
13.
微生物修复石油污染地下水的实验研究 总被引：6，自引：0，他引：6
为修复陕北黄土区石油污染地下水,采用优化土著微生物菌群的生物技术,进行了地下水中石油的降解与修复实验研究。在实验装置内加入了1.5%的优化菌群制剂,优化出的菌群初步鉴定主要有:假单胞菌属、微球菌属、放线菌属、真菌类的青霉属和曲霉属等。实验结果显示,在实验装置中人为添加石油含量为182.5 mg/l、862.5 mg/l、1695.0 mg/l时,经过28~37 d的微生物修复,地下水中石油的降解率为27.47%~92.46%,而无菌对照中的石油含量变化在5%以内,说明在无菌条件下地下水中石油降解缓慢。该实验过程验证了微生物修复技术在地下水石油污染修复中的有效性,探索了应用的可行性。 相似文献
14.
The coastal zone of the Sagar island has been studied. The island has been subjected to erosion by natural processes and to
a little extent by anthropogenic activities over a long period. Major landforms identified in the coastal area of the Sagar
island are the mud flats/salt marshes, sandy beaches/dunes and mangroves. The foreshore sediments are characterized by silty,
slightly sandy mud, slightly silty sand and silty sand. Samples 500 m inland from high waterline are silty slightly sandy
mud, and by clayey slightly sandy mud. The extent of coastline changes are made by comparing the topographic maps of 1967
and satellite imageries of 1996, 1998 and 1999. Between 1967 and 1999 about 29.8 km2 of the island has been eroded and the accreted area is only 6.03 km2. Between 1996 and 1998 the area underwent erosion of 13.64 km2 while accretion was 0.48 km2. From 1998 to 1999, 3.26 km2 additional area was eroded with meager accretion. Erosion from 1997 to 1999 was estimated at 0.74 km2 /year; however, from 1996 to 1999, the erosion rate was calculated as 5.47 km2/year. The areas severely affected by erosion are the northeastern, southwestern and southeastern faces of the island. As
a consequence of coastal erosion, the mud flats/salt marshes, sandy beaches/dunes and mangroves have been eroded considerably.
Deposition is experienced mainly on the western and southern part of the island. The island is built primarily by silt and
clay, which can more easily be eroded by the waves, tides and cyclonic activities than a sandy coast. Historic sea level rises
accompanied by land subsidence lead to differing rates of erosion at several pockets, thus periodically establishing new erosion
planes. 相似文献
15.
基于岩芯、薄片及物性资料,研究鄂尔多斯盆地东北部奥陶系马五1+2微生物岩沉积特征及其油气储集意义。研究区发育有不同规模的由蓝细菌群落构成的微生物碳酸盐岩建造,由叠层石、菌纹层白云岩、蓝细菌凝块岩以及菌黏结颗粒岩构成了藻坪和微生物丘建造。微生物丘纵向上建造规模较小,单旋回厚度一般小于1 m,发育于潮下高能环境,并由花斑状砂屑云岩、蓝细菌凝块岩、菌黏结砂屑云岩、菌纹层白云岩构成了丘基-丘核-丘坪的向上变浅序列,也常与颗粒滩相伴生构成丘滩复合体。其中,发育于丘核部位的蓝细菌凝块岩和菌黏结砂屑云岩中窗格孔和粒间孔发育,表现为中孔低渗特征,可作为盆地东北部的储集岩之一。 相似文献
16.
17.
Effects of horizontal strain in estimating specific storage and compaction in confined and leaky aquifer systems 总被引：6，自引：1，他引：5
T. J. Burbey 《Hydrogeology Journal》1999,7(6):521-532
Mathematical and numerical distinctions are made between developments of governing equations involving groundwater flow and
granular displacement where (1) only vertical strain and no change in total normal load are assumed, and (2) such limitations
are eliminated. The former is referred to here as the Jacob-Terzaghi method; the latter is referred to as the Biot method.
Numerical comparisons of drawdown, compaction, and strain are made for hypothetical confined and leaky aquifer systems for
one- and three-dimensional strain problems. Simulation results indicate that incorporation of horizontal strain results in
reduced drawdowns. Vertical compaction for a specified stress distribution is greatly reduced when horizontal strain is invoked.
The distribution of strain components indicates that approximately two-thirds of the total volume strain originates from horizontal
compaction in pumped aquifers. Incorporation of horizontal strain also affects the distribution of flux through the overlying
confining layer as a function of distance from the pumping well and may ultimately affect the interpretation of aquifer-test
data.
Received, January 1999 / Revised, May 1999, August 1999 / Accepted, August 1999 相似文献
18.
P. McMahon 《Hydrogeology Journal》2001,9(1):34-43
Several important biogeochemical reactions are known to occur near the interface between aquifer and aquitard sediments.
These reactions include O2 reduction; denitrification; and Fe3+, SO4
2–, and CO2 (methanogenesis) reduction. In some settings, these reactions occur on the aquitard side of the interface as electron acceptors
move from the aquifer into the electron-donor-enriched aquitard. In other settings, these reactions occur on the aquifer side
of the interface as electron donors move from the aquitard into the electron-acceptor-enriched, or microorganism-enriched,
aquifer. Thus, the aquifer/aquitard interface represents a mixing zone capable of supporting greater microbial activity than
either hydrogeologic unit alone. The extent to which biogeochemical reactions proceed in the mixing zone and the width of
the mixing zone depend on several factors, including the abundance and solubility of electron acceptors and donors on either
side of the interface and the rate at which electron acceptors and donors react and move across the interface. Biogeochemical
reactions near the aquifer/aquitard interface can have a substantial influence on the chemistry of water in aquifers and on
the chemistry of sediments near the interface.
Electronic Publication 相似文献
19.
Received: 9 November 1998 / Accepted: 6 October 1999 相似文献
20.
大兴安岭多年冻土区不同林型土壤微生物群落特征 总被引：1，自引：1，他引：0
高纬度多年冻土区是全球变化的敏感区域,揭示不同林型土壤微生物群落的演变规律,对于理解气候变化对寒区生态系统的影响机制具有重要意义。以大兴安岭多年冻土区3种典型林型（落叶松林、樟子松林和白桦林）为研究对象,运用磷脂脂肪酸法（PLFA）系统研究土壤微生物群落结构间差异及与土壤因子的关系。结果表明：不同林型土壤中共检测到38种PLFA生物标记,含量较高的PLFA为16∶0、18∶0、19∶0和18∶2ω6c;各类群微生物中,细菌PLFA含量最高,占总磷脂脂肪酸的83.78%~90.55%,其次为真菌,放线菌最低;白桦林土壤总磷脂脂肪酸、革兰氏阴性菌、革兰氏阳性菌、真菌和放线菌的含量最高分别为22.03、5.13、4.90、1.88和0.77 nmol·g-1,而樟子松林最低分别为14.25、2.75、2.75、1.34和0.51 nmol·g-1。Shannon-Wiener多样性指数主要表现为白桦林 > 落叶松林 > 樟子松林。冗余分析结果为：土壤含水量、全氮、总有机碳与总磷脂脂肪酸、细菌、革兰氏阳性菌和革兰氏阴性菌呈显著正相关（P<0.05）;铵态氮、硝态氮、全磷与真菌和放线菌呈显著正相关（P<0.05）。大兴安岭多年冻土区不同林型间土壤微生物群落特征存在显著差异,土壤含水量、全氮和总有机碳是影响多年冻土微生物群落结构的主要因素。 相似文献