Variation of typical pollution components and pollution way of karst water in Baotu Spring region

Jinan City is famous the Baotu Spring which enjoys a reputation as The Finest Spring Under Heaven. The quality of karst groundwater has changed greatly since the end of 1950s, which imposes effects on the spring. Using hydrochemical data collected and measured in recent 60 years, this study attempts to address this issue. Selecting several chemical indexes of water quality, including salinity, NO3-、SO42-and Cl-, and the analysis of hydrogeological conditions and human activities, the hydrochemical variations of karst water are studied for three typical water-rich areas in the piedmont of the spring region. Meanwhile，the pollution ways of water quality are revealed for the three areas of the western, central and eastern parts of the Baotu Spring region. The results show that the variation characteristics of karst water quality are similar in these three areas before 1986, with small-amplitude growth of typical pollution components. While they had significant differences after 1986. Among them, the amount of increase of the typical pollution components is the least in the western spring region, where the pollution of karst water quality is mainly affected by point pollutant sources and surface sewage infiltration. The variation of typical pollution components exhibits a steady growth trend in the central area, where the water quality is mainly affected by the rainfall and the non-point source pollution in the southern area of Baotu Spring region. The amount of increase of typical pollution components of karst water is the largest in eastern Baotu Spring region, where the pollution is from point pollutant sources and the recharge of pore water due to artificial exploitation of karst water. These results would be an important guidance for the protection of karst water in the three water-rich areas of the spring region.