Carbon monoxide is a good tracer for moving smoke plumes, even across large distances.

一氧化碳可以用来追踪烟尘羽的移动情况，即使经过遥远的距离。

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The isotope tracer method presents the advanced method of carbon isotope, nitrogen isotope, oxygen isotope and Pb tracer.

同位素示踪法着重阐述了较先进的碳、氮、氧和铅同位素的示踪。

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Conclusions the activated carbon can be used as a useful lymphatic tracer and drug carrier, for it is characterized by avirulence, high lymphatic tropism, long residence time in the lymph nodes.

结论活性炭有较强的趋淋巴性，在淋巴结中驻留时间长，其本身无毒性，可作为淋巴结示踪剂及药物载体。

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One of the experiments involves erecting three-metre high tents over a section of the crops, allowing the team to expose the plants to a "carbon tracer" - a form of carbon that is different from atmospheric carbon so it is possible for the researchers to track its movements from the surrounding air, through the plants and into the soil.

BBC: Measuring bioenergy crops' carbon footprint credentials