降雨事件下西南岩溶区地下水环境背景值获取方法探究.

The environmental background value of groundwater is an important criterion for determining the causes of groundwater exceedance and identifying the impact of anthropogenic activities on the groundwater environment. In Southwest China, rainfall is abundant and uneven in time, and the karst groundwater cycle is rapid under the influence of rainfall, so it is of great significance to investigate the method of obtaining environmental background values of groundwater in karst area, Southwest China under rainfall events. The anomalous data of water chemistry indicators before and after rainfall were identified by the hydrochemistry map method, Grubbs method and hydrochemistry map combined with Grubbs method, respectively. The effects of the above methods in identifying the anomalous data were compared, and the background eigenvalues of each indicator were calculated. The results show that the background eigenvalues of groundwater environment derived from different anomaly identification methods differ to different degrees before and after rainfall events; the hydrochemistry map combined with Grubbs method can minimize the impact of rainfall events; the method identifies 22 groups of anomalous data before rainfall, and the anomalous data identification rate after rainfall is 79.2%(19 groups)with a repetition rate of 70.8%(17 groups); the background eigenvalues derived before and after the rainfall event are better clustered and less different. In summary, rainfall events affect the statistics and characterization of the environmental background values of groundwater in karst areas, and the hydrochemistry map combined with Grubbs method is the optimal method for identifying anomalous data from rainfall events. So, it is recommended that groundwater sampling should avoid rainfall events as much as possible, so as to more accurately obtain the environmental background values of groundwater in karst areas. [ABSTRACT FROM AUTHOR]