Tracer tests for pollutant sources of the Zengpiyan remainder cave in Guilin, China

The composition and source of groundwater pollutant are complex around Zengpiyan cave, one of the archaeological sites in Guilin City. The purpose of this work is to find out the structure characteristics of groundwater systems and identify migration pathways of the groundwater pollutants and their pollution sources. Combining the artificial sampling and highresolution online tracer technique and using sodium fluorescein and rhodamine B as the tracers, three tracer tests have been carried out around the study site. Based on these test results, the groundwater seepage field was analyzed and the average velocity of the groundwater was calculated. The results show that the flow velocity is about 1.6-33.91 m/d with anan average value of 12.92 m/d. The flow system in the karst area is basically dominated by a dissolution fracture network. There exists a northeastsouthwest trending main runoff zone; and it is unlikely to exist largescale karst channels that control the flow. The three tracer tests all indicate a hydraulic connection between the release points of pollutants and groundwater around the study site. Therefore, the localities such as residential areas, schools and previous brickyard can be identified as the pollutant sources which have a optional to pollute the groundwater in the relic cave. So it is necessary to expand the scope of protection of the relics, especially taking actions to prevent the leakage of the septic containers of the Zengpiyan scenic, which are now poorly closed and seriously harm to the environment of the relic cave.