广西某露天矿区不同复垦模式下土壤的孔隙特征

Soil Pore Characteristics under Different Reclamation Modes for a Open-Pit Mine Area in Guangxi

广西铝土矿区复垦土壤孔隙结构对土壤复垦质量有重要影响,但其微结构特征尚不明确。为探究当地复垦土壤孔隙结构特征,研究选取草地复垦模式(RG)和裸地复垦模式(RW),利用X射线CT扫描技术扫描40 cm的原状土柱,用Avizo2020渲染功能,结合Image J软件及其插件获得表征土壤孔隙二维分布和三维特征的参数,并对土壤孔隙结构进行三维重构和可视化分析。结果表明,RG处理模式土壤中二维小、中孔隙数量较RW处理模式有所减少,大孔隙数量较RW处理模式明显增多。在0~20 cm土层深度内,RG处理模式下的孔隙面密度相较于RW处理模式降低了近30%;在20~40 cm土层深度内,RG处理模式下的孔隙面密度和孔隙复杂度均大于RW处理模式。RG处理模式下的三维总孔隙数较RW处理模式明显降低,RG处理模式下的孔隙度(3.046%)高于RW处理模式(2.900%),说明RW处理模式的孔隙多但并不是大孔隙。RG处理模式的连通度(0.399)大于RW处理模式(0.273),弯曲度和比表面积(1.329,4.026 mm^(-1))小于RW处理模式(1.342,4.334 mm^(-1))。在三维结构中,因2个处理模式的复垦年限均为2 a,两者孔隙结构均以点状形式分布,同时呈现出倾斜层状结构。但相较于RW,RG处理模式下的孔隙多为大孔隙,存在清晰可见的长条状孔隙,这预示着RG处理模式下的土壤朝着更为稳定的结构发展。因此,在广西露天铝土矿区的土壤复垦过程中,草地复垦模式更能促进土壤结构和水肥运移通道的改善,有利于提高土壤质量。

The pore structure of reclaimed soil in the bauxite deposit of Guangxi plays a crucial role in soil reclamation quality,but its microstructure characteristics remain unclear.This study aimed to investigate the pore structure features of local-ly reclaimed soil by examining two reclamation modes:grassland reclamation(RG)and bare land reclamation(RW).X-ray CT scanning technology was employed to scan undisturbed 40 cm soil columns.The ImageJ software and its plugins,in conjunc-tion with the Avizo2020 rendering function,were utilized to obtain parameters that characterize the two-dimensional distribution and three-dimensional characteristics of soil pores.This allowed for the three-dimensional reconstruction,visualization and anal-ysis of soil pore structure.The results indicated a decrease in the quantity of two-dimensional small and medium pores in the soils of the RG treatment model compared to the RW treatment model,while there was a notable increase in the number of large pores in comparison to the RW treatment model.In the 0~20 cm soil layer,the pore surface density of the RG treatment was a-bout 30%lower than that of the RW treatment.In the 20~40 cm soil layer,the pore surface density and pore complexity of the RG treatment surpassed those of the RW treatment.The three-dimensional total pore number was significantly reduced in the RG treatment mode compared to the RW treatment mode.The porosity of the RG treatment(3.046%)was higher than that of the RW treatment(2.900%),indicating that the RW treatment resulted in more pores,but not larger ones.The connectivity of the RG treatment(0.399)exceeded that of the RW treatment(0.273).However,the tortuosity and specific surface area(1.329,4.026 mm^(-1))were lower in the RG treatment compared to the RW treatment(1.342,4.334 mm^(-1)).In terms of three-dimensional structure,both treatments had a two-year reclamation time,resulting in a point-like distribution of pore struc-ture and displaying an inclined layered structure.However,compared to the RW treatment,the pores in the RG treatment were mainly distributed in macropores,with clearly visible elongated pores.This suggests that the RG-treated soil is progressing to-ward a more stable structure.Hence,within the soil reclamation process in Guangxi′s open-pit bauxite mining area,the grass-land reclamation model proves more effective in enhancing soil structure and optimizing water and fertilizer transport channels compared to bare land reclamation,ultimately resulting in improved soil quality.