Current situation of groundwater organic pollution and control measures in Guanshanhu Lake to Baiyun areas, Guiyang City

The research area is situated in the typical exposed-covered karst area in central Guizhou hilly plain of the Guizhou plateau, where many karst underground rivers and springs have been developed, which is indicative of abundant groundwater resources. In order to clarify the organic pollution status and distribution characteristics in the groundwater, 43 representative sites were selected and water samples were collected both in dry and rainy seasons to analyze organic components, on the basis of the classification of 12 groundwater systems and the potential pollution sources in each groundwater system. The results show that 32 of 86 samples contain organic contaminants. The concentrations of 10 organic pollutants out of 27 organic components analysed are above recommended limits. The pollutant detected ratio of chloroform is the highest with a value of 29.07%, while the ratios of other organic components are lower than 5%, except for one sample with dichloropropane level exceeding the standard. The organic pollutants are detected in 9 groundwater systems, where the contamination sources are mostly located in vicinity of the waste discharges from industries and mines especially from medium-to small-scale enterprises, and some streams and trenchs that divert contaminated substances as well. These pollutants reach groundwater in a concentrated infiltration way through karstic conduits such as sinkholes and karst windows. In overall, the detected ratio of the organic pollutants is relatively high but most of their concentrations are below the national standards; the groundwater in this area is slightly polluted. To prevent the water from further deterioration, it is necessary to implement integrated water management measures via controlling the pollution sources in medium-to small-scale industries, accelerating the construction of pipeline network for industrial and domestic wastewater and improving the pollution monitoring network.