Gaseous tracer technique for estimating air-water interfacial areas and interface mobility
Gaseous tracer technique for estimating air-water interfacial areas and interface mobility
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DOI：
10.2136/sssaj1999.6361554x
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发表时间：
1999-11-01
影响因子：
2.9
通讯作者：
Annable, MD
中科院分区：
文献类型：
--
作者：
Kim, H;Rao, PSC;Annable, MD
进行了一系列气体混相驱替实验，以估计非饱和砂柱的空气-水界面面积（A (i)）和含水量。直链烃（正癸烷）作为气体界面示踪剂，二氯甲烷和氯仿作为水分配气体示踪剂。采用气相色谱技术，以氮气为流动相，水为不流动液，在室温下进行示踪实验。示踪剂实验覆盖的物质饱和度（S-w）范围为1.5 ~ 56%。在最低S-w（1.5%）下测得的最大ni值(类似于1500 cm（2) cm(-3)）略小于用氮吸附技术测定的固体表面积(类似于2000 cm(2) cm(-3))，随着S-w的增加，a(i)值呈指数下降，在S-w为56%时降至类似于80 cm(2) cm（-3）。在有限的S-w范围内（0.29 < S-w < 0.55），其中测量了水界面和气体界面示踪剂数据，使用气态示踪剂（正癸烷）测量的a(i)值仅为先前使用水界面示踪剂（十二烷基苯磺酸钠[SDBS]）测量的a(i)值的2至3倍，空气-水界面的速度估计在孔隙水速度的23%至36%之间。使用水分配示踪剂测量的含水量与基于重量测量的含水量相差在+/-5%以内。
A series of gaseous miscible displacement experiments were conducted to estimate specific air-water interfacial areas (a(i)) and water contents in an unsaturated sand column. A straight-chain hydrocarbon (n-decane) was used as the gaseous interfacial tracer and methylene chloride and chloroform were used as the water-partitioning gaseous tracers. A gas chromatographic technique was employed for the tracer experiments conducted at room temperature using nitrogen as the mobile phase and water as the immobile liquid. Tracer experiments covered a mater saturation (S-w) range of 1.5 to 56%. The largest ni value (similar to 1500 cm(2) cm(-3)), measured at the lowest S-w (1.5%), was somewhat smaller than the solid surface area (similar to 2000 cm(2) cm(-3)) determined using the nitrogen-sorption technique, As S-w increased, a(i) values decreased exponentially to similar to 80 cm(2) cm(-3) at S-w of 56%. Within a limited S-w range (0.29 < S-w < 0.55), where both aqueous and gaseous interfacial tracer data were measured, the a(i) values measured using a gaseous tracer (n-decane) mere 2 to 3 times larger than those measured in a previous study using an aqueous interfacial tracer (sodium dodecyl-benzene sulfonate [SDBS]), The velocity of the air-water interface was estimated to be between 23 and 36% of the bulk pore-water velocity. The water contents measured using water-partitioning tracers were within +/-5% of those based on gravimetric measurements.