CAJ | 학술논문

土壤气体扩散系数是研究土壤气体传输过程的一个重要参数，它随土壤质地、容重和孔隙的改变而变化，难以估算，为准确测定和研究其特征，依据气体扩散原理设计并研制了土壤气体扩散系数测定装置。以石英砂和砂质壤土为试验材料，利用该装置研究了气体扩散系数与不同含水量和容重下的充气孔隙度间的关系。结果表明：砂质壤土原状土和装填土的气体扩散系数差别很小；土壤相对扩散系数随土壤总孔隙度减小而变小，且粒径较小的土壤具有相对较小的气体扩散系数；原状和装填砂质壤土的相对扩散系数与充气孔隙度之间的关系均可以用幂函数方程来拟合，方程中的参数与土壤质地密切相关，原状土非活性孔隙度为0。Buckingham模型的预测值与实测结果基本一致（均方根误差=0.008），但Millington and Quirk模型（均方根误差=0.032）和SWLR模型（均方根误差=0.023）的预测结果偏差较大。
토양기체확산계수시연구토양기체전수과정적일개중요삼수，타수토양질지、용중화공극적개변이변화，난이고산，위준학측정화연구기특정，의거기체확산원리설계병연제료토양기체확산계수측정장치。이석영사화사질양토위시험재료，이용해장치연구료기체확산계수여불동함수량화용중하적충기공극도간적관계。결과표명：사질양토원상토화장전토적기체확산계수차별흔소；토양상대확산계수수토양총공극도감소이변소，차립경교소적토양구유상대교소적기체확산계수；원상화장전사질양토적상대확산계수여충기공극도지간적관계균가이용멱함수방정래의합，방정중적삼수여토양질지밀절상관，원상토비활성공극도위0。Buckingham모형적예측치여실측결과기본일치（균방근오차=0.008），단Millington and Quirk모형（균방근오차=0.032）화SWLR모형（균방근오차=0.023）적예측결과편차교대。
Soil gas diffusion coefficient is an important parameter for describing soil gas diffusion process. Its value varies with soil texture, water content, bulk density, and thus is difficult to predict. In this study, we designed a testing apparatus of soil gas diffusion coefficient based Currie’s one chamber method and investigated its relationship with air filled porosity. The apparatus was composed of 2 components: a polyvinyl chloride soil chamber on the top with cutting ring and O ring, and gas chamber below. The soil chamber was connected with air and gas chamber on both sides. The gas chamber was made of transparent resin as an observation window. A stainless steel plate was located between soil chamber and gas chamber for gas diffusion control. In addition, KE-25 O2 sensor from Figaro Inc., Japan was used to transmit voltage to computer screen. From prepared calibration curve of gas concentration and voltage, the gas concentration and the gas diffusion coefficient could be calculated. A preliminary experiment showed that the measurement error caused by gas leakage was 0.000006, smaller than measurement results, indicating that the gas leakage could be ignored and the measurements were relatively accurate. In the laboratory experiment, quartz sand of 3 particle sizes were prepared to investigate the changes of relative gas diffusion coefficient with different total porosity and undisturbed and disturbed sandy loams were used to study the changes of relative gas diffusion coefficient with air-filled porosities. Meanwhile, the relative gas diffusion coefficient estimation based on measurements was compared with 3 models (Buckingham method, Millington and Quirk method, structure-dependent water-induced linear reduction model SWLR model). The results showed that relative diffusion coefficient of quartz sand increased with increasing total porosity regardless of particle sizes and also increased with particle sizes regardless of total porosity. The relationship between relative diffusion coefficient and air-filled porosity followed power function. For the sandy loam, disturbed and undisturbed soils yielded similar results with values smaller than 0.006. Among the three models, the relative diffusion coefficients estimated only from the Buckingham method was closer to that from measurement-based results with bias of -0.219×10-3 and root mean square error of 0.799×10-3, indicating caution should be paid when estimators from empirical models were used and the value couldn’t replace the measurements. The study would provide valuble information for relative gas diffusion coefficient measurements and calculation.