Abstract: A method is disclosed for intermittently mitigating hazardous sulfur compounds, such as hydrogen sulfide, mercaptans and sulfur oxides, from a fluid in the head space of a wellbore. The method comprises contacting the fluid with a foamed aqueous stream comprising an active scavenging agent, such as a triazine, and a stiff foaming agent. The scavenging agent reacts with hazardous sulfur compounds to eliminate the compounds from the fluid stream in the vapor space of the wellbore without withdrawing the hydrocarbon from the wellbore and without releasing hazardous sulfur compounds to the environment.