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1.
The carbonate system of waters of the inner, middle, and outer shelves was studied for a long period in the eastern part of the Laptev Sea. It is shown that the inner and middle shelves is a heterotrophic province and is a source of CO2 to the atmosphere during August–September. The average CO2 flux is 7.9 mmol m–2 day–1 and during one month waters of inner and middle shelves release into the atmosphere up to 0.7 Tg of carbon (C). The outer part of the shelf absorbs up to ~0.1 Tg C at an average rate of 3.9 mmol m–2 day–1 during the month. Generally, the ice-free zone of the eastern shelf of the Laptev Sea is a source of CO2 in the studied season: the amount of C released into the atmosphere within a month is ~0.6 Tg. 相似文献
2.
The role of CO2 in karst has been of interest for decades, and emphasized by IGCP 379, International Geoscience Programme, UNESCO started in 1995. There are still open questions about the dynamics of carbon in karst systems, particularly the flux of carbon between the surface and subsurface and between different components in the karst subsurface. This research report focuses on the variations of hydrochemistry and PCO2 (partial pressures of carbon dioxide) in subtropical karst groundwater, using high-resolution auto-monitoring hydrochemical data (15-min intervals). The aim of this study was to understand how hydrochemistry and PCO2 in karst systems respond to recharge over different time scales and what the controlling factors are. An auto-monitoring hydrochemistry station was installed about 300 m upstream from the exit in the active stream channel of Xueyu Cave, a typical subtropical karst cave. Four years of high-resolution continuous pH, specific conductivity (Spc), temperature and water-level data were collected. A thermodynamic model was used to link the continuous data to monthly water quality data, allowing the calculation of CO2 partial pressures and calcite saturation (SIc) levels on a continuous basis. Seasonal, diurnal and storm-scale variations were captured in the hydrochemistry and calculated PCO2 records, indicating that the cave stream is a dynamic and variable system. Seasonal features (higher specific conductivity and lower pH in summer; lower specific conductivity and higher pH in winter) tend to covary with temperature which influences the production of CO2 in soils, thus being the driving force for the variations (the soil CO2 effect). Due to the buffer effect of a thick vadose zone and large void cave space, diurnal variations are not obvious compared with epikarst springs in SW China. Storm-scale fluctuations due to storm events occur during the summer rainy season. Piston flow effects, dilution and soil CO2 effects determine the variations in different storm events. At the beginning of the rains, the piston effect drives the variations, characterized by increase in Spc, SIc and pH in the cave stream and decrease in PCO2. With heavy rainfall, decrease in Spc shows control by the dilution effect, while decrease in SIc and pH and increase in PCO2 indicates the greater influence of soil CO2. These results imply that the soil and cave voids are important factors influencing the hydrochemical evolution of karst groundwater. Future works need to use such high-resolution technology widely for tracing the PCO2 and hydrochemical variations in different karst aquifers. 相似文献
3.
Percolation-theory and fuzzy rule-based probability estimation of fault leakage at geologic carbon sequestration sites 总被引：1，自引：0，他引：1
Yingqi Zhang Curtis M. Oldenburg Stefan Finsterle 《Environmental Earth Sciences》2010,59(7):1447-1459
Leakage of CO2 and displaced brine from geologic carbon sequestration (GCS) sites into potable groundwater or to the near-surface environment
is a primary concern for safety and effectiveness of GCS. The focus of this study is on the estimation of the probability
of CO2 leakage along conduits such as faults and fractures. This probability is controlled by (1) the probability that the CO2 plume encounters a conductive fault that could serve as a conduit for CO2 to leak through the sealing formation, and (2) the probability that the conductive fault(s) intersected by the CO2 plume are connected to other conductive faults in such a way that a connected flow path is formed to allow CO2 to leak to environmental resources that may be impacted by leakage. This work is designed to fit into the certification framework
for geological CO2 storage, which represents vulnerable resources such as potable groundwater, health and safety, and the near-surface environment
as discrete “compartments.” The method we propose for calculating the probability of the network of conduits intersecting
the CO2 plume and one or more compartments includes four steps: (1) assuming that a random network of conduits follows a power-law
distribution, a critical conduit density is calculated based on percolation theory; for densities sufficiently smaller than
this critical density, the leakage probability is zero; (2) for systems with a conduit density around or above the critical
density, we perform a Monte Carlo simulation, generating realizations of conduit networks to determine the leakage probability
of the CO2 plume (P
leak) for different conduit length distributions, densities and CO2 plume sizes; (3) from the results of Step 2, we construct fuzzy rules to relate P
leak to system characteristics such as system size, CO2 plume size, and parameters describing conduit length distribution and uncertainty; (4) finally, we determine the CO2 leakage probability for a given system using fuzzy rules. The method can be extended to apply to brine leakage risk by using
the size of the pressure perturbation above some cut-off value as the effective plume size. The proposed method provides a
quick way of estimating the probability of CO2 or brine leaking into a compartment for evaluation of GCS leakage risk. In addition, the proposed method incorporates the
uncertainty in the system parameters and provides the uncertainty range of the estimated probability. 相似文献
4.
A bidirectional labeling method was established to distinguish the proportions of HCO3? and CO2 utilization pathways of microalgae in Lake Hongfeng. The method was based on microalgae cultured in a medium by adding equal concentrations of NaH13CO3 with different δ13C values simultaneously. The inorganic carbon sources were quantified according to the stable carbon isotope composition in the treated microalgae. The effects of extracellular carbonic anhydrase (CAex) on the HCO3? and CO2 utilization pathways were distinguished using acetazolamide, a potent membrane-impermeable carbonic anhydrase inhibitor. The results show utilization of the added HCO3? was only 8% of the total carbon sources in karst lake. The proportion of the HCO3? utilization pathway was 52% of total inorganic carbon assimilation. Therefore, in the natural water of the karst area, the microalgae used less bicarbonate that preexisted in the aqueous medium than CO2 derived from the atmosphere. CAex increased the utilization of inorganic carbon from the atmosphere. The microalgae with CAex had greater carbon sequestration capacity in this karst area. 相似文献
5.
Based on the analyses and comparisons of water chemistry, stable carbon isotopes and deposition rates of speleothems, the
authors found that there are two kinds of speleothems in the tunnels at the Wujiangdu Dam site, Guizhou, China, namely the
CO2-outgassing type and the CO2-absorbing type. The former is natural, as observed in general karst caves, and the product of karst processes under natural
conditions. The latter, however, is special, resulting from the carbonation of a cement-grouting curtain and concrete. Due
to the quick absorption of CO2 from the surrounding atmosphere, evidenced by the low CO2 content in the air and the high deposition rate of speleothems (as high as 10 cm/a) in the tunnels, the contribution of the
carbonation process to the sink of CO2 in the atmosphere is important (in the order of magnitude of 108 tons c/a) and should be taken into consideration in the study of the global carbon cycle because of the use of cement on
a worldwide scale.
Received: 21 July 1997 · Accepted: 13 January 1997 相似文献
6.
我国是世界能源消费和CO2总排放量第一大国,碳减排任务艰巨,责任重大。据调查,我国岩溶碳汇与森林、土壤碳汇在同一数量级,但其要在国家层面发挥重大作用,其影响因素及机理需要进一步调查和阐释,估算精度还有待提高。系统总结了流域尺度岩溶碳循环过程,并重点揭示了生物作用对岩溶碳循环的影响;研究了水圈二氧化碳的再循环规律;评估了外源水对岩溶作用的影响程度和促进强度;利用数学回归模型估算区域岩溶碳汇通量,提高了由点到面岩溶碳汇通量估算精度,并提出增加岩溶碳汇潜力技术途径,为我国岩溶碳汇通量科学估算提供支撑。 相似文献
7.
Geochemical detection of carbon dioxide in dilute aquifers 总被引：1，自引：0，他引：1
Background
Carbon storage in deep saline reservoirs has the potential to lower the amount of CO2 emitted to the atmosphere and to mitigate global warming. Leakage back to the atmosphere through abandoned wells and along faults would reduce the efficiency of carbon storage, possibly leading to health and ecological hazards at the ground surface, and possibly impacting water quality of near-surface dilute aquifers. We use static equilibrium and reactive transport simulations to test the hypothesis that perturbations in water chemistry associated with a CO2 gas leak into dilute groundwater are important measures for the potential release of CO2 to the atmosphere. Simulation parameters are constrained by groundwater chemistry, flow, and lithology from the High Plains aquifer. The High Plains aquifer is used to represent a typical sedimentary aquifer overlying a deep CO2 storage reservoir. Specifically, we address the relationships between CO2 flux, groundwater flow, detection time and distance. The CO2 flux ranges from 103 to 2 × 106 t/yr (0.63 to 1250 t/m2/yr) to assess chemical perturbations resulting from relatively small leaks that may compromise long-term storage, water quality, and surface ecology, and larger leaks characteristic of short-term well failure. 相似文献8.
Variations in the atmospheric carbon dioxide concentration and the average global near-surface air temperature are compared over the last 50-year period. It turns out that, within the interannual time scales, the carbon dioxide concentration variations generally lagged behind the corresponding temperature variations. However, within time scales of more than 40 years in the 1980s–1990s, when the growth of CO2 and temperature accelerated, carbon dioxide was in the lead. This fact indicates that atmospheric pollution actually could have begun to affect the climate at that time. 相似文献
9.
典型岩溶水系统碳汇通量估算 总被引：6，自引：1，他引：5
现代岩溶学研究成果表明,碳酸盐岩在全球碳循环中响应极其迅速,水循环过程中的碳汇效应显著。本研究选取广西桂林寨底地下河系统、广西环江大安地下河系统、重庆北碚青木关地下河系统三个典型岩溶地下水系统,利用各系统地下河的流量和HCO3-浓度的监测资料,采用简单化学平衡模式法估算碳汇通量(CO2)。结果显示,寨底地下河系统的单位面积年碳汇通量为68.82 t/(km2.a),大安地下河系统的单位面积年碳汇通量为81.18 t/(km2.a),青木关地下河系统的单位面积年碳汇通量为100.07 t/(km2.a)。分析认为同一个岩溶水系统的结构特征和环境条件基本上是稳定的;地下河的流量和HCO3-浓度是影响岩溶碳汇强度的关键因素,尤其是地下河流量的变化对碳汇强度的影响显著;不同岩溶水系统的碳汇通量不但受水化学条件和地下水动力条件的控制,同时受土地利用变化的影响。该研究对于改进碳循环模型和评价岩溶地质碳汇有重要意义。 相似文献
10.
Greenhouse gases and greenhouse effect 总被引：1，自引：0，他引：1
G. V. Chilingar O. G. Sorokhtin L. Khilyuk M. V. Gorfunkel 《Environmental Geology》2009,58(6):1207-1213
Conventional theory of global warming states that heating of atmosphere occurs as a result of accumulation of CO2 and CH4 in atmosphere. The writers show that rising concentration of CO2 should result in the cooling of climate. The methane accumulation has no essential effect on the Earth’s climate. Even significant
releases of the anthropogenic carbon dioxide into the atmosphere do not change average parameters of the Earth’s heat regime
and the atmospheric greenhouse effect. Moreover, CO2 concentration increase in the atmosphere results in rising agricultural productivity and improves the conditions for reforestation.
Thus, accumulation of small additional amounts of carbon dioxide and methane in the atmosphere as a result of anthropogenic
activities has practically no effect on the Earth’s climate. 相似文献
11.
Cheng Zeng Vivian Gremaud Haitao Zeng Zaihua Liu Nico Goldscheider 《Environmental Earth Sciences》2012,65(8):2285-2297
About two hydrological years of continuous data of discharge, temperature, electrical conductivity and pH have been recorded
at the Glarey spring in the Tsanfleuron glaciated karst area in the Swiss Alps, to understand how glaciated karst aquifer
systems respond hydrochemically to diurnal and seasonal recharge variations, and how calcite dissolution by glacial meltwater
contributes to the atmospheric CO2 sink. A thermodynamic model was used to link the continuous data to monthly water quality data allowing the calculation of
CO2 partial pressures and calcite saturation indexes. The results show diurnal and seasonal hydrochemical variations controlled
chiefly by air temperature, the latter influencing karst aquifer recharge by ice and snowmelt. Karst process-related atmospheric
CO2 sinks were more than four times higher in the melting season than those in the freezing season. This finding has implication
for understanding the atmospheric CO2 sink in glaciated carbonate rock terrains: the carbon sink will increase with increasing runoff caused by global warming,
i.e., carbonate weathering provides a negative feedback for anthropogenic CO2 release. However, this is a transient regulation effect that is most efficient when glacial meltwater production is highest,
which in turn depends on the future climatic evolution. 相似文献
12.
François Guyot Damien Daval Sébastien Dupraz Isabelle Martinez Bénédicte Ménez Olivier Sissmann 《Comptes Rendus Geoscience》2011,343(2-3):246-259
Geological storage of carbon dioxide (CO2) is one of the options envisaged for mitigating the environmental consequences of anthropogenic CO2 increases in the atmosphere. The general principle is to capture carbon dioxide at the exhaust of power plants and then to inject the compressed fluid into deep geological formations. Before implementation over large scales, it is necessary to assess the efficiency of the process and its environmental consequences. The goal of this paper is to discuss some environmental mineralogy research perspectives raised by CO2 geological storage. 相似文献
13.
E. M. Galimov 《Geochemistry International》2017,55(5):401-417
It was shown that the history of the biosphere is closely related to processes caused by low solar luminosity. Solar radiation is insufficient to maintain the Earth’s surface temperature above the freezing point of water. Positive temperatures are kept owing to the presence of greenhouse gases in the atmosphere: CO2, CH4, and others. Certain stages in the development of the biosphere and climate are related to these effects. Methane was the main carbon-bearing gas in the primordial atmosphere. It compensated the low solar luminosity. Life originated under the reduced conditions of the early Earth. Methane-producing biota was formed. Methane remained to be the main greenhouse gas in the Archean. The release of molecular oxygen into the atmosphere 2.4 Ga ago resulted in the disruption of the established mechanism of the compensation of the low solar luminosity. Methane ceased to cause a significant greenhouse effect, and the content of carbon dioxide was insufficient to play this role. A global glaciation began and had lasted for approximately 200 million years. However, the increasing CO2 content in the atmosphere reached eventually a level sufficient for the compensation for the low solar luminosity. The glaciation period came to an end. Simultaneously, a conflict arose between the role of CO2 as a gas controlling the thermal regime of the planet and as an initial material for biota production. As long as the resource of biotic carbon was inferior to that of atmospheric CO2, the uptake of atmospheric CO2 related to sporadic increases in biologic production was insufficient for a significant change in the thermal regime. This was the reason for a long-term climate stabilization for 1.5 billion years. By 0.8 Ga, the resource of oceanic biota reached the level at which variations in the uptake of atmospheric CO2 related to variations in the production of organic and carbonate carbon became comparable with the resource of atmospheric CO2. Since then, an oscillatory equilibrium has been established between the intensity of biota development and climate-controlling CO2 content in the atmosphere. Glaciation and warming periods have alternated. These changes were triggered by various geologic events: intensification or attenuation of volcanism; growth, breakup, or migration of continents; large-scale magmatism; etc. A new relation between atmospheric CO2 and biotic carbon was established in response to the emergence of terrestrial biota and the appearance of massive buffers of organic carbon on land. The interrelation of the biosphere and climate changed. 相似文献
14.
Christopher W. Hunt Joseph E. Salisbury Douglas Vandemark Wade McGillis 《Estuaries and Coasts》2011,34(1):68-77
Four surveys of the adjacent Cocheco, Bellamy, and Oyster estuaries reveal spatial heterogeneity with respect both to river-born
carbon dioxide (CO2) fluxes and CO2 exchange with the atmosphere (−17 to 51 mmol m−2 day−1), a finding partially explained by CO2 inputs from contributing watersheds. Nonuniform nutrient and organic carbon loading from upstream rivers and within the estuaries
is considered as a mechanism resulting in the variability between estuaries. Conditions during the surveys included spring
river runoff and phytoplankton blooms, drought with baseline river flow, and a historic flood which led to a large CO2 release to the atmosphere. This study highlights the variability of CO2 transport and release found between proximate estuaries over a wide range of flow conditions. 相似文献
15.
Carbonate characteristics of the water mass of the deepwater part of the Arctic Ocean (AO) in the continental slope area were
determined, and the range and reasons of their variability during summer-fall season were revealed. The AO water area is a
meaningful sink for atmospheric carbon dioxide. The warm intermediate Atlantic waters (AW) are also undersaturated with carbon
dioxide relative to its content in the atmosphere. While these waters move along AO continental slope, the value pCO2 in the AW core decreases to 8–10 μatm (mainly, due to drop in the water temperature). The potential absorption capacity of
the AO deepwater basin is estimated at approximately 48 Tg of carbon (without sea ice taken into account). Joint analysis
of carbonate and hydrological parameters showed that near-bottom waters formed on the shallow shelf of the Laptev Sea, which
is rich in inorganic and organic carbon of terrestrial and marine genesis, take part in formation of halocline waters of the
AO. They are modified due to interaction with AW penetrating to the shelf and are transferred to the deepwater AO segment,
where they occur in the halocline according to their density. Transformed near-bottom waters of the Laptev Sea shelf, similar
to waters of the halocline of Pacific origin in the eastern sector of the AO, are traced above the continental slope in Amundsen
Basin on the basis of higher CO2 concentrations. 相似文献
16.
Safe pipeline transportation of carbon dioxide is a critical issue in the developing field of carbon capture and storage technology. Inadequate fluid thermo- and regimes for on- and offshore transport through high-pressurized pipelines can induce pipe material obsolescence or even pipeline rupture. In such cases, CO2 (Carbon dioxide) will be released and dispersed in the ambient medium. The dispersion is influenced by the total amount of released fluid, jet pressure and direction, the released concentrations, leakage hole size, ambient material properties and is also affected by the dynamical conditions of the environmental medium. The goal of this study is the hydrodynamical characterization of carbon dioxide jet expansion and dispersion in the ambient atmosphere in case of onshore pipeline accidental leaks. Numerical simulations were carried out by means of a 3D turbulent CFD (computational fluid dynamics) code which includes multi-component flow treatment. The influence of the jet release pressure and size of the leakage hole on harmful CO2 concentration distances will be analyzed. 相似文献
17.
M N PATIL T DHARMARAJ R T WAGHMARE T V PRABHA J R KULKARNI 《Journal of Earth System Science》2014,123(1):177-185
An increase in carbon dioxide (CO2) concentrations in the atmosphere due to anthropogenic activities is responsible for global warming and hence in recent years, CO2 measurement network has expanded globally. In the monsoon season (July–September) of year 2011, we carried out measurements of CO2 and water vapour (H2O) concentrations along with wind and air temperature over a tropical site in south-east India having rural topography. To collect these observations, the instrumentations used were the sonic anemometer for wind and temperature, and the open path H2O/CO2 infrared gas analyzer for CO2 and H2O concentrations. Using these observations, we explored the diurnal variability of CO2 flux along with sensible and latent heat. The CO2 flux was positive during night-time and negative during daytime and in phase with convective instability. The CO2 flux relationships with the meteorological parameters such as wind speed, temperature and heat fluxes have been analysed. The seasonal (monsoon) half hour mean of CO2 flux which was ?3.55 μmol m???2 s???1 indicated the experimental site as a CO2 sink region (net seasonal uptake). An increase in CO2 concentrations during weekends was not observed due to unavailability of heavy vehicular traffic. 相似文献
18.
In investigating early karstification of one-dimensional conduits by computer models, so far one has assumed that the CO2 content of the calcite aggressive water stems entirely from the surface. Subterranean sources of CO2, however, can rejuvenate the solutional power of water already close to equilibrium with respect to calcite, and boost dissolution
rates. In a first scenario we have investigated the influence of a punctual source of CO2 as the most simple case of release of CO2 into a karstifiable fracture at some position KL from its entrance of the widening joint with length L, (K<1). The results
show that only a small increase of the p
CO2 in the solution to about 0.01 atm is sufficient to reduce the breakthrough times to about 0.3 with respect to the case, where
no CO2 is delivered. Other sources of CO2 are due to the metabolic activity of microorganisms. The existence of such diverse subterraneous microbial life in karst
systems is demonstrated. Whether situated on the fissure surfaces or free floating in the karst water, one basic product of
their metabolism is CO2. This contributes over the whole flow path to the p
CO2 of the karst water. Therefore in a second scenario we assumed a constant rate of CO2-input along parts of the fracture, as could be delivered by the activity of aerobic bacteria dwelling at its walls. Such
a scenario also applies to an extended diffuse CO2 migration from volcanic activity deep underground. In this case drastic reductions of the breakthrough time by about one
order of magnitude are observed. These reductions are enhanced when the fracture aperture width of the initial fracture decreases.
The physicochemical mechanisms of enhancement of karstification are discussed in detail by considering the evolution of the
fracture aperture width and of the dissolution rates in space and time.
Received: 17 December 1998 · Accepted 23 April 1999 相似文献
19.
The distributions of the partial pressure of carbon dioxide (pCO2) and total alkalinity (TA) were examined for a 6-month period in the Wailuku and Wailoa rivers and coastal waters of Hilo
Bay on the west coast of the Island of Hawaii, USA. Main results for the largest and turbulent Wailuku River show in the watershed
an oversaturation in CO2 with respect to atmospheric equilibrium and a CO2 undersaturation in the estuary. In the Wailoa river-estuary system, extremely high pCO2 values ranging from 1500 to 10500 ppm were measured with significant shifts in pCO2 from drought to flood period. In the two rivers, water residence time, groundwater inputs and occasional flood events are
the predominant drivers of the spatial and temporal patterns in the distribution of pCO2. In Hilo Bay, CO2 oversaturation dominates and the bay was a source of CO2 to the atmosphere during the study period. TA is conservative along the salinity gradient, indicating calcification in the
bay is not a significant source of CO2 to the atmosphere. 相似文献
20.
《Proceedings of the Geologists' Association. Geologists' Association》2017,128(3):431-437
A substantial decrease in atmospheric carbon dioxide (CO2) concentration during the mid-Palaeozoic is likely to have been the consequence partially of the evolution of rooted land plants. The earliest land plants evolved in the Ordovician but these were small cryptophytes without any roots. Much of the evidence for the evolution of vascular plants comes from the Old Red Sandstone of South Wales and the Welsh Borderland. Plants with large rooting systems evolved during the Middle Devonian and resulted in an increase in chemical weathering of silicate rocks. This, in turn, caused a contemporaneous drop in atmospheric CO2 concentration from approximately 25 times present concentration in the Cambrian to twice the present concentration by the late Carboniferous. The supposed mechanism for CO2 removal from the atmosphere involves oceanic carbonate precipitation, enhanced by plant-enhanced chemical weathering of Ca and Mg silicates. 相似文献