模拟冻融循环对黑土黏化层孔隙结构的影响

Pore characteristics of mollisol argillic horizon under simulated freeze-thaw cycles

以东北典型黑土区耕地土壤为研究对象,采用室内模拟冻融以及CT(Computerized tomography)扫描相结合的方法,通过孔隙数目、平均面积、成圆率3个指标的量化与分析,研究了冻融循环对黏化层土壤孔隙特征的影响规律,以期为探明该区土壤侵蚀机理提供科学依据。研究结果表明,冻融循环不同程度地降低了原状土和填充土的孔隙数目和面积,均在循环3次时达到最低值,冻融循环对≥5 mm孔隙影响较为明显。相对原状土而言,前期含水量对黏化层填充土柱孔隙特征的影响较小。黏化层结构对模拟冻融循环的响应特征印证了季节性冻融循环对黑土区黏化层可蚀性的影响,进而诱发土壤侵蚀、促进沟蚀发展的可能。

Taking the cropland soil in mollisol region of northeastern China as the test object, we used simulated freeze-thaw combined with computerized tomography （CT） scanning to study the effects of freeze-thaw cycles on pore characteristics of argillic horizon by quantifying and analyzing the number, average area and roundness of pores. The study was aimed to provide scientific evidences for understanding the mechanism of soil erosion in the region. Results showed that freeze-thaw cycles reduced the number and area of pores in both undisturbed soil and remoulded soil to different degrees and their minimum values appeared after three freeze-thaw cycles. Freeze-thaw cycles significantly affected soil pores with the diameter ≥5 mm. Initial water content during freeze-thaw cycles had less effect on the pore characteristics of argillic horizon in remoulded soil compared with undisturbed soil. Responses of pore characteristics to simulated soil freeze-thaw cycles confirm the effects of seasonal freeze-thaw cycles on argillic horizon, which then induce soil erosion and accelerate the development of gully.