Temporal and spatial variations in hydro-geochemistry of cave percolation water and their implications for four caves in Guizhou, China

Soil water and cave drip water from four cave systems in Guizhou, Southwest China, were monitored and sampled monthly from April 2003 to May 2004 to understand spatio-temporal variations in hydro-geochemistry of cave percolation water. The results indicated that among the 5 drip water sites from the Liangfeng Cave (LFC), there were no significant differences among the hydro-geochemical parameters. In the Xiniu Cave (XNC), the drip rates were variable and responded quickly to precipitation events in the 3# (No. 3) drip site with variable water head; both bulk and variation in drip rates were smaller in the 2# with constant water head. However, in the Qixing Cave (QXC) and Jiangjun Cave (JJC), drip rates, concentrations of major ions and saturation index for calcite (SIC) were smaller, and Mg/Ca ratios in Group I (1#, 2#, 6#, 7# and 8# in the QXC; 2# and 3# in the JJC) were larger than those in Group II (3#, 4#, 5# and 9# in the QXC; 1# and 4# in the JJC). These differences might be the result of different hydrogeological processes above the caves, which are divided into five categories based on hydro-geochemistry data. The formation of some proxies in speleothem, such as Mg/Ca, is likely to be affected by those processes.