isotope tracer A radioactive isotope, whose movement can be monitored, which is used to trace the pathways by which individual substances move through an organism, a living system, the abiotic environment, etc. Non-radioactive chemical analogues of certain substances may be used for the same purpose if their movement can be monitored (e.g. caesium, which can be substituted for potassium).

isotope tracer Radioactive isotope, whose movement can be monitored, that is used to trace the pathways by which individual substances move through an organism, a living system, the abiotic environment, etc. Nonradioactive chemical analogues of certain substances may be used for the same purpose if their movement can be monitored (e.g. caesium, which can be substituted for potassium).