intrinsic tracer

例句：

1. 1.The research team used an intrinsic tracer to study the movement of water in the river.
   研究小组使用一种内源示踪剂来研究河水在河中的流动。
2. 2.The intrinsic tracer helped us understand the behavior of the animals in the forest.
   内源示踪剂帮助我们理解森林中动物的行为。
3. 3.The use of intrinsic tracers is becoming increasingly popular in environmental monitoring.
   在环境监测中使用内源示踪剂越来越受欢迎。