An unmanned aerial vehicle may be used to mark airborne material in a plume. The unmanned aerial vehicle may store a macroscopic and/or microscopic tracer material. A sensor and/or control unit may detect a substance of interest in a plume. The sensor may be configured to detect multiple different substances sharing a particular characteristic. The unmanned aerial vehicle may be piloted along a gradient of increasing concentration of the substance of interest. The tracer material may be ejected into the plume. The tracer material may be configured to react and/or interact with the substance of interest. The unmanned aerial vehicle may be piloted a predetermined distance from the plume after the tracer material has been ejected. Additional and/or different tracer material may be ejected into the plume if it is determined from measurements that ejecting additional tracer material would be beneficial.