The impact of land use and land cover changes on solute dynamics in seepage water of soil from karst hillslopes of Southwest China

Land use and land cover changes can cause variations in terrestrial energy, water balance and availability of nutrients. To understand the role of vegetation in regulating the hydrochemistry of karst hillslopes, overland flow and soil seepage water from two hillslopes covered with and without vegetation were studied in the Huanjiang Observation and Research Station for Karst Ecosystems, Guangxi, SW China. Dissolved major ions, as well as isotopic compositions of dissolved inorganic C (DIC) were examined. Water from the vegetated control slope had higher solute concentrations (except NO3-) and lower δ13C values than water from the disturbed slope. The dynamics of K+ and NO3- in soil water sampled in time-sequence from the control slope was different from the disturbed slope. Specifically, K+ and NO3- concentrations of the control slope decreased gradually over time, while K+ and NO3- concentrations of the disturbed slope increased, and other ionic concentrations increased in both of the slopes.