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气泡释放是天然水体释放CH4的主要途径之一,准确量化水体气泡释放量对于辨析其“汇、源”特性至关重要。自然水体释放气泡的不连续性、不确定性使得监测其过程较为困难。本研究针对水体气泡释放监测难题,通过改进倒置漏斗型气泡通量监测装置提出了一种气泡释放过程连续监测方法。本方法测量对象为定长时间监测水域释放气泡的体积,经室内外实验验证,其理论量程为3.6～132 mL/(m2·min),测量结果能够较好的表征10～40 m水深缓流水体气泡体积通量变化特征。运用该方法于2021年6—11月对三峡水库支流香溪河库湾开展CH4气泡通量连续监测,并分析不同环境因子对其产生的影响。结果表明:监测期间,研究水域CH4气泡通量变化范围为0.02～8.13 mg/(m2·d),且各采样点间CH4气泡通量呈现较高的时空变异性;CH4气泡通量与水温、水体pH呈显著正相关关系,与水深及水体电导率呈显著负相关关系。其中,水深可能是决定水体是否通过气泡形式释放CH4的重... 相似文献
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Gas exsolution and flow during supersaturated water injection in porous media: I. Pore network modeling 总被引：1，自引：0，他引：1
Weishu ZhaoMarios A. Ioannidis 《Advances in water resources》2011,34(1):2-14
Degassing and in situ development of a mobile gas saturation take place when an aqueous phase saturated with gas at a pressure higher than the subsurface pressure is injected in water-saturated porous media. In the first part of this work, a pore network model is used to study the key physical aspects of this novel and hitherto unexplored way of introducing a gas phase in the subsurface. Following heterogeneous nucleation, growth of gas phase clusters driven by convective diffusion of solute from the bulk aqueous phase, is shown to result in a ramified pattern of gas-occupied pores, which is controlled by capillary and buoyancy forces. The interplay between mass transfer and immiscible displacement processes, namely gas cluster coalescence, mobilization under the action of buoyancy forces and fragmentation resulting from capillary instabilities, is seen to favour the propagation of a stable gas saturation front. Pore network model predictions of the macroscopic mass transfer rate coefficient are in fair agreement with a recently published empirical correlation. 相似文献
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Geologic carbon sequestration is the capture of anthropogenic carbon dioxide (CO2) and its storage in deep geologic formations. The processes of CO2 seepage into surface water after migration through water-saturated sediments are reviewed. Natural CO2 and CH4 fluxes are pervasive in surface-water environments and are good analogues to potential leakage and seepage of CO2. Buoyancy-driven bubble rise in surface water reaches a maximum velocity of approximately 30 cm s−1. CO2 rise in saturated porous media tends to occur as channel flow rather than bubble flow. A comparison of ebullition versus dispersive gas transport for CO2 and CH4 shows that bubble flow will dominate over dispersion in surface water. Gaseous CO2 solubility in variable-salinity waters decreases as pressure decreases leading to greater likelihood of ebullition and bubble flow in surface water as CO2 migrates upward. 相似文献
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