粤北岩溶丘陵区不同地貌部位土壤钙的分布特征——以英德市九龙镇为例

Characteristics of Calcium Ions Migration at Different Geomorphological Positions in Karst Hilly Area of Northern Guangdong:A Case Study on Jiulong Town in Yingde City

为了解岩溶丘陵区不同地貌条件对于土壤钙元素迁移或富集的影响,选择粤北英德市九龙镇典型岩溶丘陵区2座山丘作为研究区,分别对顶部、峭壁、坡麓、积水洼地和干旱沟谷进行了岩石裸露率、土层厚度和植被等调查;并采集不同样地土壤,利用原子吸收分光光度计测定了土壤中全钙、交换性钙、水溶性钙质量分数,结果表明：积水洼地土壤的全钙质量分数最高,达62.397 g/kg;其次是丘顶、坡麓、峭壁、沟谷,积水洼地的交换性钙和水溶性钙质量分数同样为最高,分别是4.582和0.223 g/kg,交换性钙和水溶性钙在丘顶、峭壁、坡麓和沟谷4个部位土壤中的差异不明显,分别在1.560∽2.421 g/kg之间和0.057∽0.180 g/kg之间。研究表明,土壤的碳酸盐质量分数和p H值与全钙、交换性钙、水溶性钙都呈极显著正相关,全钙与交换性钙、交换性钙与水溶性钙有极显著正相关;地形不仅影响土壤钙水平方向的分布,还影响其垂向分布。

Two hills in a typical Karst hilly area in Jiulong, Yingde, were selected as the study area. To understand soil calcium element migration and enrichment in different geomorphic conditions in Karst area, the bareness rate of rock, soil thickness and vegetation at hill top, cliff, slope, dry gully, hill foot and water depression were surveyed, and different soil samples were collected. Atomic absorption spectrophotometer was used to measure the contents of total calcium, exchangeable calcium, and water soluble calcium. The results showed that the total calcium content of soil in water depression was 62.397 g/kg, the highest in all the geomorphic locations, next were hill top, slope, cliff, and gully successively. The highest contents of exchangeable calcium and water soluble calcium also occurred in the soil of water depression, which were, respectively, 4.582 and 0.223 g/kg. The contents of exchangeable calcium and water soluble calcium were not significantly different at hill top, slope, cliff, and gully, which were 1.560-2.421 g/kg and 0.057-0.180 g/kg respectively. The research indicated that soil carbonate content and p H value had significant positive correlations with total calcium, exchange calcium, and water soluble calcium. There were significant positive correlationship between total calcium and exchange calcium, and between exchange calcium and water soluble calcium. It was shown that terrain affected not only the horizontal but also the vertical distribution of soil calcium.