chemical tracer

例句：

1. 1. Chemicaltracers are used to track the movement of pollutants in water systems.
   化学示踪剂被用来追踪水体系统中污染物的运动。
2. 2. The research team developed a new type of chemical tracer that could detect bacteria in the food chain.
   研究团队开发了一种新类型的化学示踪剂，可以检测食物链中的细菌。
3. 3.The scientist used a chemical tracer to study the movement of oil in the ocean.
   科学家使用一种化学示踪剂来研究海洋中石油的运动。