为查明不同含水层之间的水力联系和地表水与地下水之间的补给关系,有时要进行一些示踪试验。一般选用的示踪剂都有一定的优缺点,适合于特定的水文地质条件。例如,强电解质盐类,灵敏度较低,用量大,会破坏地下水的天然动态;有机染料,虽然检出方便,但吸附性强,适用的含水层受到限制;其它化学试剂和放射性同位素,灵敏度较高,用量少, Tracing tests are sometimes conducted to find out the hydraulic connections between different aquifers and the replenishment between surface and groundwater. General tracer selection has some advantages and disadvantages, suitable for specific hydrogeological conditions. For example, the strong electrolyte salts, low sensitivity, large amount, will undermine the natural dynamics of groundwater; organic dyes, although the detection of convenient, but strong adsorption, applicable aquifer is limited; other chemical reagents and radioisotopes, the sensitivity of High, less dosage,