Soil water and its karst effect in epikarst dynamic system.

This paper studied the soil physical properties, soil CO₂, soil water and spring water chemistry in a mature forest and a shrub in Nongla of Guangxi, China, as well as the relationships between the chemistry of soil water and spring water, aimed to understand the karst effect of the soil water in Nongla epikarst dynamic system. Significant differences were observed in the soil bulk density and non-capillary porosity under forest and shrub, which affected soil water content. The fixed CO₂ in soil water had a significant negative correlation with soil CO₂, and the free CO₂ in soil water was 0 mg · m^-3 in the forest and 5.33 · 10³ mg · m^-3 in the shrub. In soil water and spring water, there was a negative correlation between pH and Ca²⁺, Mg²⁺, and Cl^- concentrations, and a positive correlation between K⁺, Na⁺, and HCO₃^- concentrations and organic C content. After the eluviation of rain water, the ion concentrations in leached soil water increased greatly, and accordingly, its corrosion ability enhanced greatly. The karst process in forest environment was stable and intensive, while that in shrub environment was active but weak. [ABSTRACT FROM AUTHOR]