ABSTRACT
The purpose of this study is to examine how the chemistry of the aquifer reflects karst features, and to characterize the differences in the relationships of water quality of aquifer systems in sinkhole and non-sinkhole areas. Sinkholes and associated karst conduits interrupt the lateral continuity of the overburden and confining units, induce changes in local flow pathways, and intercept chemical components in surface water and overlying aquifers. Distributions of sinkholes and water-quality variables in this study reflect the characteristics of a typical fractured karst aquifer system. Nitrogen compounds (NO3 − and NH4 +) are dispersed along the orientation of major regional fracture lineaments, know as sinkhole alignments. Temperature is inversely correlated with alkalinity, calcium and total organic carbon. The inverse correlation indicates that rapid vertical flows carry warm surface water into the limestone aquifer where karst features are present. Two groups of chemical variables represent chemistry of a typical limestone aquifer and potential-related variables respectively. This findings strongly demonstrate the penetration of the sinkholes and their associated vertical karst features. Groundwater quality not only reflects the confining conditions of the limestone aquifer but also reflects interactions between the surficial and confined limestone aquifer, which are due to karstic feature development. General results of spatial correlations between karst features and water quality variables indicate that the karst features are predominant local pathways for introducing contaminations.
